[Technical Field]
The present invention relates to an ink jet
recording sheet and more particularly to an ink jet
recording sheet of slight-coat type which shows no
uneven spread of ink, is excellent in ink absorption, is
high in density and sharpness of recorded images, can
provide a recorded dot close to a true circle and
besides, is excellent in water resistance of recorded
dots.
[Background Art]
The ink jet recording method performs
recording of letters or images by allowing ink droplets
ejected by various working principles to deposit on a
recording sheet such as paper. The ink jet recording
has such favorable features that it makes high-speed
recording possible, that it produces little noise, that
it can easily perform multi-color recording, that there
is no limitation as to kind of patterns, and that it
requires no developing-fixing. Thus, the ink jet
recording is rapidly becoming widespread as devices for
recording various characters including kanji and color
images. Furthermore, the images formed by the multi-color
ink jet recording method are by no means inferior
to those printed by a multi-color press of those
obtained by a color-photography. Besides, use of the
ink jet recording extends to a field of full-color image
recording where number of copies is not so many, since
costs per copy are less than those employing the
photographic process.
As for the recording sheets used for ink jet
recording, efforts have been made from the aspects of
printer hardwares or ink composition in order to use
woodfree papers or coated papers used for ordinary
printing or writing. However, improvements in recording
sheets have come to be required increasingly in order to
go side by side with developments in printer hardwares
such as ever increasing speed, development of ever finer
definition and images of full color.
That is, for recording sheets, it is required
that image density of the printed ink dots be high and
hue characteristics be bright and appealing, and the ink
absorbing speed be high and as a result, the ink applied
do not bleed or spread even though the recorded dots are
put over additionally. Moreover, the diffusion of the
recorded dot in the transverse direction should not be
greater than needed and the circumference of dots should
be sharp and demarcating.
The ink jet recording sheets as to their form
can be roughly classified into those of plain paper type
represented by so-called fine papers·bond papers and
those of coated type which comprise a support such as
paper, for example, fine paper, synthetic paper or
synthetic resin film and an ink-receiving layer provided
on the support.
The coated type includes ink jet recording
sheets of low-coat type of about 1-10 g/m2, intermediate-coat
type of about 10-20 g/m2 and high-coat type
of more than 20 g/m2.
Especially, recently, among low-coat type
sheets, slight-coat type sheets of 0.5-5.0 g/m2 which is
the coating amount of the lower limit are close to plain
papers and are preferred in both the appearance and the
handling, and the slight-coat type sheets are increasingly
desired. However, in the case of color recording,
not only monochromatic recording of yellow, magenta,
cyan or black, but also overlapping recording of these
colors are effected and the deposition amount of ink is
very large. Therefore, in the case of slight-coat type
sheet, ink cannot be completely absorbed by the coat
layer and it becomes necessary to absorb a part of the
deposited ink by the base paper per se used as a support
by using a base paper of relatively lower sizing.
Japanese Patent Kokai No.60-63191 discloses
ink jet recording sheets having a high ink absorption
and capable of providing recorded dots of good shape.
This patent publication is characterized in that a
filler and a fibrous material are contained together in
the surface layer of the recording material (ink jet
recording sheet). It describes that the material has a
base comprising a fibrous material and filler particles
which are thinly scattered and deposited on the surface
of the base. It mentions the state of the filler and
the fibrous material being present together in the
surface layer, but does not mention the state of the
fibrous material constituting the base being exposed at
the surface layer.
In order to solve these problems, Japanese
Patent Kokoku No.3-26665 discloses an example of ink jet
recording sheet comprising a base paper having a
Stöckigt sizing degree of 4 seconds or less at a
standard of 60 g/m2 in basis weight and, provided
thereon, a coat layer containing fine particle silica
and a water soluble polymer binder, Japanese Patent
Kokai No.59-38087 discloses an example of ink jet
recording material comprising a base having a sizing
degree of 0-10 seconds and an ink absorbing layer
provided thereon, and Japanese Patent Kokai No.59-9516
discloses an example of ink jet recording sheet comprising
a base paper having a Stöckigt sizing degree of 0-5
seconds and impregnated with polyvinylpyrrolidone or the
like.
Japanese Patent Kokai No.5-221115 discloses an
ink jet recording sheet of the present applicant. The
ink jet recording sheet disclosed in this publication
comprises a support provided with an ink-receiving layer
on one side and a backcoat layer on another side wherein
the ink-receiving layer contains starch particles or
processed starch particles thereof or at least one
specific ethylene-vinyl acetate copolymer resin and a
cationic dye fixer, said fixer being contained in such
an amount that the cationic charge quantity is 0.2-40
meq./m2 per unit area of the recording sheet. The
object is to attain high image density, excellent ink
absorption, reduction of spread in color-overlapping
portions, inhibition of yellowing and inhibition of
curling. However, the ink-receiving layer of this
patent publication is specified in cationic charge quantity
given by the fixer and contains specific materials
as essential components and the publication does not
suggest use of specific particles and cationic charge
quantity of ink jet recording sheet per unit weight.
Moreover, various proposals have been made to
improve water resistance of dyes. For example, Japanese
Patent Kokai No.56-84992 discloses a method of adding
polycationic polyelectrolytes to the surface and
Japanese Patent Kokai No.55-150396 discloses a method of
imparting water resistance by producing chelates with
dyes in the aqueous ink. Furthermore, Japanese Patent
Kokai No.60-11389 discloses an ink jet recording sheet
characterized by containing a basic oligomer to improve
both the water resistance and the light resistance of
dyes. As an example of using polyvinylamine copolymers,
Japanese Patent Kokai No.64-8085 discloses a recording
material (ink jet recording sheet) improved in water
resistance and light resistance by containing cationic
polymers or salts thereof (polyvinylamine derivatives).
However, the polyvinylamine derivatives are polymers or
copolymers containing substantially no (meth)acrylic
acid monomer unit.
As described above, when coating amount of the
ink-receiving layer is small, a base paper of relatively
low sizing degree is used to allow the support per se to
absorb a part of the deposited ink. However, when the
excess ink which cannot be absorbed by the ink-receiving
layer is absorbed by the support per se, the recorded
image is low in density and lacks sharpness. In
addition, as aforementioned, the ink jet recording sheet
specified in the cation charge quantity comprises
combination of specific materials of the ink-receiving
layer and differs in function and effect from the ink
jet recording sheet of the present invention which is
slight-coat type.
In JP-A-60219084, an ink jet recording medium is disclosed, wherein the
ink receiving layer comprises cationic colloidal silica coated at an
amount of 3-10 g/m2.
In JP-A-60219083, an ink jet recording medium is disclosed, wherein the
ink receiving layer comprises a mixture of cationic and anionic colloidal silica.
The object of the present invention is to
provide a slight-coat type ink jet recording sheet which
shows no uneven spread of ink, is excellent in ink
absorption, is high in density and sharpness of the
recorded image, can provide a recorded dot close to a
true circle and besides, is excellent in water
resistance of recorded dots.
[Disclosure of Invention]
As a result of intensive research, the
inventors have invented an ink jet recording sheet
which shows no uneven spread of ink, is excellent in ink
absorption, is high in density and sharpness of the
recorded image, can provide a recorded dot close to
a true circle and besides, is excellent in water
resistance of recorded dots.
That is, the first embodiment of the present invention invention relates to an ink
jet recording sheet comprising a support and an ink-receiving
layer coated thereon wherein the ink-receiving
layer is a coated layer mainly composed of a non-spherical
cationic colloidal silica and is contour-coated
along the surface of the support, the coating
amount being 0.5-5.0 g/m2.
The contour-coated layer is a layer coated at
a covering rate of at least 70% on the surface of the
support.
The ink-receiving layer comprises a composition
mainly composed of a non-spherical cationic
colloidal silica and a binder.
The ink-receiving layer comprises 100 parts by
weight of a non-spherical cationic colloidal silica and
5-20 parts by weight of a binder.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 4-20% by weight in
coating liquid concentration on a support.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 4-10% by weight in
coating liquid concentration on a support by a size
press.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 10-20% by weight
in coating liquid concentration on a support by a rod
coater.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 10-20% by weight
in coating liquid concentration on a support by a
transfer roll coater.
The non-spherical cationic colloidal silica is
acicular or columnar.
The ink jet recording sheet of the second embodiment of
the present invention comprises a support and an ink-receiving layer
coated thereon wherein the component of the ink-receiving
layer is mainly composed of a non-spherical
cationic colloidal silica and the ink-receiving layer is
a coated layer which is contour-coated along the surface
of the support, the coating amount being 0.5-5.0 g/m2
and the total cationic charge quantity of the recording
sheet is 0.5-20 meq/100 g.
The contour-coated layer is a layer coated at
a covering rate of at least 70% on the surface of the
support.
The ink-receiving layer comprises a composition
mainly composed of a non-spherical cationic
colloidal silica and a binder.
The ink-receiving layer comprises 100 parts by
weight of a non-spherical cationic colloidal silica and
5-20 parts by weight of a binder.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 4-20% by weight in
coating liquid concentration on a support.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 4-10% by weight in
coating liquid concentration on a support by a size
press.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 10-20% by weight
in coating liquid concentration on a support by a rod
coater.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 10-20% by weight
in coating liquid concentration on a support by a
transfer roll coater.
The non-spherical cationic colloidal silica is
acicular or columnar.
The ink jet recording sheet of the third embodiment of
the present invention comprises a support and an ink-receiving layer
coated thereon wherein the support contains a
polyvinylamine copolymer prepared by copolymerization
reaction of N-vinylformamide and acrylonitrile and
having a molecular weight of 50000 or more and a molar
ratio of vinylamine of 20 mol% or more, the ink-receiving
layer component is mainly composed of non-spherical
cationic colloidal silica and the ink-receiving
layer is contour-coated along the surface of
the support, the coating amount being 0.5-5.0 g/m2.
The total cationic charge quantity of the
recording sheet is 0.5-20 meq/100 g.
The contour-coated layer is a layer coated at
a covering rate of at least 70% on the surface of the
support.
The ink-receiving layer comprises a composition
mainly composed of a non-spherical cationic
colloidal silica and a binder.
The ink-receiving layer comprises 100 parts by
weight of a non-spherical cationic colloidal silica and
5-20 parts by weight of a binder.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 4-20% by weight in
coating liquid concentration on a support.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 4-10% by weight in
coating liquid concentration on a support by a size
press.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 10-20% by weight
in coating liquid concentration on a support by a rod
coater.
The ink-receiving layer is obtained by coating
an ink-receiving layer composition of 10-20% by weight
in coating liquid concentration on a support by a
transfer roll coater.
The non-spherical cationic colloidal silica is
acicular or columnar.
The ink jet recording sheet of the present
invention will be explained in detail below.
The ink jet recording sheet of the present
invention comprises a support and a slightly coated ink-receiving
layer which is contour-coated along the
surface of the support wherein the components of the
ink-receiving layer are specified.
In the first ink jet recording sheet of the
present invention, the ink-receiving layer is a coated
layer contour-coated along the surface of a base paper.
The term "contour-coated layer" means a surface of a
coated layer coated with components of the ink-receiving
layer along the projected portions (mountains) and the
dented portions (valleys) of the surface of a base
paper, and the coated surface has the surface contour
similar to that of the bass paper.
The "contour-coating" generally means coating
on the surface of a base paper by an air knife coater,
thereby to form a thick-coated layer which is reflective
of the surface contour of the base paper. This
expression is cited for the slight-coat type ink jet
recording sheet of the present invention.
The "contour-coated layer" can be compared by
another expression to a row of mountains covered with
snow which are seen far away, namely, the row of
mountains in the surface of the base paper and the
snowscape of the mountains is the surface of the ink-receiving
layer. If the snowfall is small, trees not
covered with snow are seen in places. Similarly, if the
coating amount is small, there is seen the state of pulp
fibers being exposed at the surface of the ink-receiving
layer. If the snowfall is large, the contour of the
mountains is recognized and a somewhat larger amount of
snow lies on the slope of the mountains. Similarly, if
the coating amount is large, shape of the pulp fibers
can be recognized on the surface of the ink-receiving
layer and a somewhat larger amount of ink-receiving
layer component covers the dented portions (valleys)
between the pulp fibers.
If the snowfall is larger, the slope of the
mountains is covered with a large amount of snow and the
contour of the mountains cannot be definitely seen.
Similarly, if the coating amount is larger, the dented
portions (valleys) between the pulp fibers are filled up
with the ink-receiving layer component and the shape of
the pulp fibers cannot be recognized and the surface of
the ink-receiving layer flattens. In this case, the ink
jet recording sheet as a coated paper is reminded of
from a plain paper and is outside the scope of the ink
jet recording sheet of the present invention.
The contour-coated layer in the ink jet
recording sheet of the present invention is a layer
coated on the surface of the support at a covering rate
of at least 70% and this means that the support is
coated to such an extent that the shape of pulp fibers
of the surface of the ink-receiving layer present on the
support, namely, the base paper can be sufficiently
recognized. The support is uniformly covered with ink-receiving
layer, namely, with non-spherical cationic
colloidal silica along the surface of the pulp fibers
and is thinly covered therewith in conformity with the
shape of the surface of the pulp fibers. The surface
covering rate of the ink-receiving layer is such that
70% or more of the surface of the pulp fibers is
covered. Thereby, the characteristics aimed at by the
present invention can be sufficiently exhibited. The
covering rate is preferably at least 80%, more
preferably at least 90%.
The reason therefor is as follows. In the
case of the surface of the ink-receiving layer coated
being uniform, when ink is applied to the surface of the
ink-receiving layer by an ink jet printer, the ink does
not spread in the planar direction of the ink-receiving
layer because of the uniform surface of the ink-receiving
layer and the recorded dot can be expressed in
the form of nearly a true circle and the excess ink
permeates in the thickness direction of the base paper
from the surface. On the other hand, if the covering
rate of the ink-receiving layer over the pulp fibers is
less than 70%, the ratio of the ink spreading in planar
direction at the surface of the ink-receiving layer is
high and as a result, the shape of the recorded dot is
out of true circle. Furthermore, permeation into the
base paper is irregular and ink bleeds.
In the present invention, the contour-coated
layer is preferably coated on the surface of support in
the form of continuous layer of a uniform thickness and
when the continuous layer is formed, this is prescribed
to be a covering rate of 100%. Thickness of the coated
layer relates to the coating amount, but the layer is
preferably a continuous layer even if the thickness is
thin. Thickness of the coat layer is about 0.3-3 µm.
However, the contour-coated layer does not necessarily
completely cover the surface of the support and a
covering rate of at least 70% is preferred. For
measuring the covering rate, a scanning electron
microscope can be used and image analysis is carried out
to calculate area ratio.
In the ink jet recording sheet of the present
invention, as a means to measure the covering rate of
the coat layer on the surface of pulp fibers at the ink-receiving
layer, a scanning electron microscope can be
used and image analysis is conducted to calculate the
area ratio.
The ink jet recording sheet according to the
present invention is characterized by having a type
close to slight-coat type paper and plain paper by
forming an ink-receiving layer contour-coated along the
surface of a support. When the ink jet recording sheet
is subjected to recording using an ink jet printer,
recorded dots close to true circles can be obtained.
The applied ink is instantaneously absorbed by the non-spherical
cationic colloidal silica which is superior in
absorbability and excess ink permeates in the direction
of thickness which is sectional direction of the coated
layer. Therefore, there are obtained recorded dots free
from uneven ink spread.
The ink jet recording sheet of the present
invention has component of ink-receiving layer mainly
composed of a non-spherical cationic colloidal silica.
The non-spherical cationic colloidal silica
used in the present invention is non-spherical colloidal
silica which is cation-modified by coating the surface
with a hydrated metal oxide which is a cation modifier.
The term "non-spherical" used here means "substantially
not spherical" and means various forms such as acicular,
columnar, rosary-like, rod-like, platy, bulky, fibrous
and spindle-like forms. Moreover, it includes fibrous
form made by agglomeration into a long chain form.
Especially preferred are acicular and columnar ones.
As the non-spherical cationic colloidal silica
used in the present invention, there may be preferably
used colloidal silica covered with a cation modifier
comprising a metal oxide hydrate such as aluminum oxide
hydrate, zirconium oxide hydrate, tin oxide hydrate or
the like and especially preferred is one cation-modified
with aluminum oxide hydrate.
Methods of cation modification used include
those described in U.S Patent No.3,007,878 and Japanese
Patent Kokoku No.47-26959.
The diameter of pulp fibers which form a base
paper is in the order of several 10 µm and the maximum
shorter diameter of the non-spherical cationic colloidal
silica used in the present invention is 50 nm or less,
preferably 30 nm or less and the length of the colloidal
silica is 300 nm or less, preferably 100 nm or less.
Since the ratio of the diameter of pulp fibers
and the particle diameter of the colloidal silica is
several hundredth or less, even the surface of pulp
fibers projected over the surface of base paper can be
thinly coated with such a small coating amount as
described above.
The non-spherical cationic colloidal silica is
normally used in the form of colloidal dispersion in
water with keeping the size of primary particles.
In the non-spherical cationic colloidal silica
used in the ink jet recording sheet of the present
invention, coating amount of the metal oxide hydrate as
a cation modifier is advantageously in the range of 1-30%
by weight in terms of metal oxide on the basis of
silica (in terms of SiO2). If the coating amount is
less than 1% by weight, water resistance of the image
recorded with ink on the ink jet recording sheet is
conspicuously deteriorated and if it is too much, film
properties on the coated surface become brittle to cause
cracking. The coating amount is preferably 2.5-25% by
weight, more preferably 5-20% by weight.
Furthermore, the dispersion of the non-spherical
cationic colloidal silica may further contain
an acid component such as acetic acid, citric acid,
sulfuric acid, phosphoric acid or the like for colloid
stability.
The component of the ink-receiving layer of
the ink jet recording sheet of the present invention is
mainly composed of the non-spherical cationic colloidal
silica and is further constituted of the non-spherical
cationic colloidal silica and a binder, the amount of
the binder being 5-20 parts by weight, preferably 7-15
parts by weight for 100 parts by weight of the colloidal
silica.
That the effect of the present invention can
be exhibited with use of a small amount of binder in the
coating liquid for the ink-receiving layer is due to the
binder effect of the colloidal silica per se. Even
though there is the binding effect of the colloidal
silica per se, if the amount of binder is less than 5
parts by weight, this is insufficient and if it exceeds
20 parts by weight, the binder damages the ink
absorbability.
In the ink jet recording sheet of the present
invention, concentration of the coating liquid for the
ink-receiving layer is preferably 4-20% by weight. If
the concentration is less than 4% by weight, it is
difficult to coat the layer in a given amount on the
support and if it is more than 20% by weight, the
coating amount exceeds the desired amount in the case of
some coating methods and the resulting sheet becomes
like the coated paper type. This is not preferred.
For coating the ink-receiving layer using a
coating liquid of the above specific concentration,
there may be used various apparatuses such as blade
coater, roll coater, air knife coater, bar coater, rod
coater, gate roll coater, curtain coater, short-dowel
coater, gravure coater, flexogravure coater, and size
press in the manner of on- or off-machine. Of these
coaters, size press, rod coater, transfer roll coater
and air knife coater are preferred.
After coating, the coated sheet may be
finished by calenders such as machine calender,
temperature gradient (TG) calender, super calender and
soft calender.
Especially, when the coating liquid of the
ink-receiving layer comprising the above composition has
a concentration of 4-10% by weight, it is preferred to
use a size press. If the concentration of the coating
liquid is less than 4% by weight here, it is difficult
to coat the liquid in a given amount on the support and
if it is more than 10% by weight, the coating amount
exceeds the desired amount and the resulting sheet
becomes close to coated paper type. This is not
preferred.
Further, when the coating liquid of the ink-receiving
layer comprising the above composition has a
concentration of 10-20% by weight, it is preferred to
use rod coater, transfer roll coater or air knife
coater. If the concentration of the coating liquid is
less than 10% by weight, it is difficult to coat the
layer in a given amount on the support and if it is more
than 20% by weight, the coating amount exceeds the
desired amount and the resulting sheet becomes like the
coated paper type. This is not preferred.
As aforementioned, with reference to the ink
jet recording sheet of the present invention, the
surface state of the ink-receiving layer is explained
above figuratively, and specifically the coating amount
of the ink-receiving layer is 0.5-5.0 g/m2, preferably
1.0-4.0 g/m2. Within this range, the ink jet recording
sheet of the present invention can be obtained and can
be handled as a type near the plain papers. If the
coating amount is more than 5.0 g/m2, no ink jet
recording sheet close to plain papers can be obtained.
On the other hand, if it is less than 0.5 g/m2, the
component of the ink-receiving layer cannot cover
uniformly the surface of the support and this is
undesirable.
The ink jet recording sheet of the present
invention can contain ultrafine inorganic pigments in
addition to the non-spherical cationic colloidal silica.
Examples of the ultrafine inorganic pigments are as
shown below.
That is, mention may be made of silica
(colloidal silica), alumina or alumina hydrates (alumina
sol, colloidal alumina, cationic aluminum oxide or
hydrates thereof, pseudoboehmite), surface-treated
cationic colloidal silica, aluminum silicate, magnesium
silicate and magnesium carbonate.
Furthermore, inorganic pigments usable in
combination with the ultrafine inorganic pigments may be
any of those which are known. As examples thereof,
mention may be made of precipitated calcium carbonate,
ground calcium carbonate, kaolin, talc, calcium sulfate,
barium sulfate, titanium dioxide, zinc oxide, zinc
sulfide, zinc carbonate, satin white, aluminum silicate,
diatomaceous earth, calcium silicate, synthetic
amorphous silica, aluminum hydroxide, lithopone,
zeolite, hydrated halloycite and magnesium hydroxide.
Among these inorganic pigments, preferred are
porous inorganic pigments and examples are porous synthetic
amorphous silica, porous magnesium carbonate and
porous alumina and especially preferred is porous synthetic
amorphous silica of great volume of micro pore.
Moreover, organic pigments such as styrene
plastic pigments, acrylic plastic pigments, polyethylene,
microcapsules, urea resin and melamine resin
may be used together with the ultrafine inorganic
pigments.
The binders used together with the non-spherical
cationic colloidal silica include polyvinyl
alcohol, vinyl acetate, oxidized starch, etherified
starch, cellulose derivatives such as carboxymethyl
cellulose and hydroxyethyl cellulose, casein, gelatin,
soybean protein, silyl-modified polyvinyl alcohol;
conjugated diene copolymer latexes such as maleic
anhydride resin, styrene-butadiene copolymer and methyl
methacrylate-butadiene copolymer; acrylic polymer
latexes such as polymers or copolymers of acrylic esters
and methacrylic esters and polymers or copolymers of
acrylic acid and methacrylic acid; vinyl polymer latexes
such as ethylene-vinyl acetate copolymer; functional
group-modified polymer latexes obtained by modifying the
above-mentioned various polymers with monomers containing
functional group such as carboxyl group; aqueous
binders such as thermosetting synthetic resins, for
example, melamine resin and urea resin; synthetic resin
binders such as polymethyl methacrylate, polyurethane
resin, unsaturated polyester resin, vinyl chloride-vinyl
acetate copolymer, polyvinyl butyral and alkyd resin.
These may be used alone or in combination of two or
more.
Moreover, known cationic resins may also be
used together for fixing the dyes.
Furthermore, as other additives there may be
used pigment dispersant, thickener, flowability
improver, antifoamer, foam inhibitor, releasing agent,
foaming agent, penetrant, coloring dye, coloring
pigment, fluorescent whitener, ultraviolet absorber,
antioxidant, preservative, antifungal agent, water-resisting
agent, wet strengthening agent and dry
strengthening agent.
The second ink jet recording sheet of the
present invention comprises a support and a slight-coat
type ink-receiving layer which is contour-coated along
the surface of the support where components of the ink-receiving
layer are specified and the total cationic
charge quantity of the recording sheet is within a
specific range per 100 g of the recording sheet.
The total cationic charge quantity of the ink
jet recording sheet of the present invention is 0.5-20
meq/100 g, preferably 1.0-15 meq/100 g in conformity
with the slight-coat type ink jet recording sheet. If
the total cationic charge quantity is less than 0.5
meq/100 g, it is insufficient for attaining the object
of the present invention and if it is more than 20
meq/100 g, the coating amount of the ink-receiving layer
must also be increased and the resulting ink jet
recording sheet is outside the scope of the slight-coat
type ink jet recording sheet of the present invention.
The total cationic charge quantity concerns
with fixability of ink dyes and in the case of the
slight-coat type ink jet recording sheet of the present
invention within the scope of the present invention,
when an ink is applied by an ink jet printer, the
anionic ink dye can be fixed in the ink-receiving layer
and besides, the solvent for the ink can be rapidly
absorbed into the support. As a result, it becomes
possible to carry out ink jet recording of images of
high image density and sharpness.
The components of ink-receiving layer which
contributes to the total cationic charge quantity
include the non-spherical colloidal silica of the
present invention as a main component and cationic dye
fixing agents and the like. The total cationic charge
quantity within the range of the present invention is
the total cationic charge quantity per 100 g of the ink
jet recording sheet coated with the ink-receiving layer
containing the above-mentioned cationic materials.
Furthermore, the cationic charge quantity resulting from
other materials than the components of the ink-receiving
layer, namely, the cationic materials, for example,
fillers comprising basic pigments such as calcium
carbonate which are contained in the support per se can
be added to the total cationic charge quantity and the
resulting value can be employed as the total cationic
charge quantity of the whole ink jet recording sheet and
this is included in the present invention.
The total cationic charge quantity of the ink
jet recording sheet can be measured by the following
method. First, a recording sheet comprising a base
paper as a support and an ink-receiving layer coated
thereon is taken and subjected to maceration by adding
an deionized water. A given amount thereof is taken and
adjusted to pH 4-5 with addition of a buffer. Then, an
anionic substance for colloidal titration is added,
followed by filtration to obtain a sample of a given
concentration. The total cationic charge quantity is
measured using this sample by colloidal titration
method.
The total cationic charge quantity is a
cationic charge quantity of the recording sheet per 100
g and expediently, this is calculated by multiplying the
sum of the cationic charge quantity of the support and
that of the ink-receiving layer by a factor obtained by
converting the total weight of the basis weight of the
support and the coating amount of the ink-receiving
layer into the weight per 100 g. The unit is meq/100 g.
The third ink jet recording sheet of the
present invention comprises a support containing a
specific polyvinylamine copolymer and a slight-coat type
ink-receiving layer which is contour-coated along the
surface of the support.
The support used in the ink jet recording
sheet of the present invention contains a polyvinylamine
copolymer which is prepared by copolymerization reaction
of N-vinylformamide and acrylonitrile and has a molar
ratio of vinylamine of 20 mol% or more and a molecular
weight of 50000 or more. The ink jet recording sheet of
the present invention comprises the above-mentioned
support and the ink-receiving layer coated thereon and
is excellent in water resistance of the recorded image.
The ink for ink jet recording comprises an
aqueous ink mainly composed of a direct dye and an acid
dye and the dye can be fixed by the reaction of the
anionic portion of the dye with the cationic substance
such as polyvinylamine copolymer used in the present
invention. When a polyvinylamine copolymer is used as
the cationic substance in making a base paper (support),
the polyvinylamine copolymer strongly adsorbs to the
pulp and is retained in the base paper (support). Since
the dye in the recording ink is fixed by the polyvinylamine
copolymer adsorbed into the support, water
resistance of the recorded image is developed.
In the ink jet recording sheet comprising a
support containing the polyvinylamine copolymer and an
ink-receiving layer provided thereon, when the ink for
ink jet recording is first applied to the ink-receiving
layer, the ink is absorbed in the ink-receiving layer
and excess ink is absorbed in the thickness direction of
the recording sheet, namely, into the support and the
polyvinylamine copolymer contained in the support
contacts with the dye in the ink whereby the dye is
fixed. Since the fixed dye is firmly set with the
support, it is never dissolved away even when water is
applied from outside. That is, a recorded image having
water resistance is obtained.
Even in the case the polyvinylamine copolymer
is one obtained by copolymerization of N-vinylformamide
with acrylonitrile, if the vinylamine ratio is less than
20 mol%, a sufficient water resistance can hardly be
obtained and if the molecular weight is less than 50000,
fixability of the polyvinylamine copolymer in the pulp
and ink-receiving layer decreases and the recorded image
tends to deteriorate in water resistance.
The polyvinylamine copolymers used in the
present invention can be contained in an amount of 1% by
weight or more, preferably in an amount of 3% by weight
or more based on the solid content of pulp in the
support.
The polyvinylamine copolymers used in the
present invention are copolymers as exemplified in
Japanese Patent Kokai Nos.64-40694 and 4-11094.
As the monomers used for synthesis of the
polyvinylamine copolymers, mention may be made of, for
example, N-vinylacetamide, N-vinylpropionamide, methyl
N-vinylcarbamate, ethyl N-vinylcarbamate and isopropyl
N-vinylcarbamate in addition to N-vinylformamide.
As the monomers copolymerized with N-vinylformamide,
mention may be made of, for example, acrylonitrile,
(meth)acrylic esters of alcohols of 1-4 carbon
atoms with (meth)acrylic acid, acrylamide and (meth)acrylic
acid. Especially preferred are acrylonitrile
and acrylamide.
Supports used in the present invention include
base papers prepared by mixing wood pulp, for example,
chemical pulp such as LBKP and NBKP, mechanical pulp
such as SGW, PGW, RMP, TMP, CTMP, CMP and CGP or
recycled pulp such as DIP and known pigments in addition
to the above polyvinylamine copolymer as main components
with at least one of known additives such as binder,
sizing agent, fixing agent, retention aid, cationizing
agent and strengthening agent and making paper from the
resulting mixture by a paper former such as Foudrinier
machine, cylinder machine and twin wire machine.
More preferred are the above base papers
subjected to surface sizing with water-soluble polymers
such as starch and polyvinyl alcohol. When the sized
base papers are used, coatability and fixability of the
ink-receiving layer can be improved.
The ink-receiving layer may be provided on
such base papers as they are or after subjected to
calendering using calendering apparatuses such as
machine calender, temperature gradient (TG) calender and
soft calender to control the flattening.
The ink for ink jet recording used in the
present invention is an aqueous ink comprising the
following colorants, solvents and other additives.
The colorants include water-soluble dyes such
as direct dyes, acid dyes, basic dyes, reactive dyes and
food dyes.
The solvents for the aqueous ink include water
and various water-soluble organic solvents, for example,
alkyl alcohols of 1 to 4 carbon atoms such as methyl
alcohol, ethyl alcohol, n-propyl alcohol, isopropyl
alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl
alcohol and isobutyl alcohol; amides such as dimethylformamide
and dimethylacetamide; ketones or ketone
alcohols such as acetone and diacetone alcohol; ethers
such as tetrahydrofuran and dioxane; polyalkylene
glycols such as polyethylene glycol and polypropylene
glycol; alkylene glycols having 2 to 6 alkylene groups
such as ethylene glycol, propylene glycol, butylene
glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol,
hexylene glycol and diethylene glycol; and
lower alkyl ethers of polyhydric alcohols such as
glycerin, ethylene glycol methyl ether, diethylene
glycol methyl (or ethyl) ether and triethylene glycol
monomethyl ether. Of these many water-soluble organic
solvents, preferred are polyhydric alcohols such as
diethylene glycol and lower alkyl ethers of polyhydric
alcohols such as triethylene glycol monomethyl ether and
triethylene glycol monoethyl ether.
As other additives, mention may be made of,
for example, pH regulators, chelating agents, preservatives,
viscosity modifiers, surface tension modifiers,
wetting agents, surface active agents and anticorrosive
agents.
The ink jet recording sheet of the present
invention can be used not only as sheet for ink jet
recording, but also as any recording sheets on which an
ink which is liquid state at the time of recording is
put for recording.
For example, these recording sheets include an
image-receiving sheet for heat transfer recording which
comprises heating an ink sheet comprising a thin support
such as a resin film, a high-density paper or a
synthetic paper coated with a heat-meltable ink mainly
composed of dye or pigment from the back side to melt
the ink and transferring the molten ink; an ink jet
recording sheet which makes use of droplets of a heated
and molten ink and splashing them, an ink jet recording
sheet which uses an ink prepared by dissolving an oil-soluble
dye in a solvent and an image-receiving sheet on
which images are transferred from a photosensitive and
pressure-sensitive donor sheet coated with microcapsules
containing a photopolymerizable monomer and colorless or
colored dye or pigment.
These recording systems are common in that the
ink is in a liquid state at the time of recording. A
liquid ink permeates or diffuses vertically and
horizontally through the ink-receiving layer until it
hardens, solidifies or becomes fixed. Ink absorbing
ability of the recording sheets in conformity with the
respective recording system is required, so that the ink
jet recording sheet of the present invention can be
utilized successfully in these recording systems.
Furthermore, the ink jet recording sheets of
the present invention can be used as the recording
sheets for electrophotographic recording system which is
widely used in copiers, printers and the like, where a
toner is fixed by heating.
First, the ink jet recording sheet of the
present invention comprises a support and an ink-receiving
layer coated thereon wherein the ink-receiving
layer is a coat which is mainly composed of a non-spherical
cationic colloidal silica and which is
contour-coated along the surface of the support at a
coating amount of 0.5-5.0 g/m2. When an ink is applied
to the surface of the ink-receiving layer of the
recording sheet, the ink does not spread in the surface
direction, but permeates through the surface of the ink-receiving
layer and excess ink permeates in the
thickness direction of the base paper. Thereby,
recorded dots close to true circle can be obtained and
an ink jet recording sheet high in density of recorded
image and in sharpness can be obtained.
Secondly, the ink jet recording sheet of the
present invention comprises a support and an ink-receiving
layer coated thereon wherein the ink-receiving
layer is a coat which is mainly composed of a non-spherical
cationic colloidal silica and which is
contour-coated along the surface of the support at a
coating amount of 0.5-5.0 g/m2 and the total cationic
charge quantity of the recording sheet is 0.5-20 meq/100
g. When an ink is applied to the surface of the ink-receiving
layer of the recording sheet, the anionic ink
dye is rapidly fixed in the ink-receiving layer
(partially in the base paper) and the ink does not
spread in the direction of the surface and the excess
ink permeates in the direction of thickness of the base
paper. Thereby, recorded dots close to true circle can
be obtained and an ink jet recording sheet high in
density of recorded image and in sharpness can be
obtained.
Furthermore, thirdly, the ink jet recording
sheet of the present invention comprises a support and
an ink-receiving layer coated thereon wherein the
support contains a polyvinylamine copolymer prepared by
copolymerization reaction of N-vinylformamide and
acrylonitrile and having a molecular weight of 50000 or
more and a molar ratio of vinylamine of 20 mol% or more,
the ink-receiving layer component is mainly composed of
a non-spherical cationic colloidal silica and the ink-receiving
layer is contour-coated along the surface of
the support at a coating amount of 0.5-5.0 g/m2. When
an ink is applied to the surface of the ink-receiving
layer of the recording sheet, the anionic ink dye is
rapidly fixed in the ink-receiving layer and the ink
does not spread in the direction of the surface and
then, the excess ink permeates in the direction of
thickness of the support (base paper). The excess ink
contacts with the polyvinylamine copolymer in the
support to result in fixing of the dye. It is presumed
that the excellent water resistance can be obtained by
this fixation of the dye.
[Best Mode for Carrying Out the Invention]
Examples of the present invention will be
explained below, but the present invention is not
limited to these examples. In the examples, "part" and
"%" indicate part by weight and % by weight, respectively,
unless otherwise notified.
The ink jet recording sheets prepared in the
following examples and comparative examples were
evaluated by the following methods and the results are
shown in Tables 1-6 and 8.
[Ink absorbability]
Ink absorbability and sharpness of image were
conducted by visually judging the degree of ink mixing
at the boundary between the solid portions printed by
superposing inks, for example, the boundary between
red print (magenta + yellow) and green print (cyan +
yellow). When the red print portion and the green print
portion did not overlap and separated, the characteristic
is good and when they overlapped in a large area
to form a black line, the characteristic is bad. In the
case of the ink jet recording sheets which are inferior
in ink absorbability, the quality of the resulting image
(sharpness of image) is considerably damaged and therefore
the sheets are worthless even if other characteristics
such as image density are good.
The evaluation criteria are as follows.
A: The characteristics are good. B: Practically acceptable. C: Practically unsatisfactory. D: The characteristics are bad.
[Image density]
The image density was measured on the solid
portion printed with a black ink by a reflective
densitometer (Macbeth RD918 manufactured by Macbeth Co.,
Ltd.). The higher value indicates the higher image
density and the superior result. Normally, 1.20 or more
is satisfactory.
[Covering rate]
The covering rate (%) was obtained in the
following manner. X-ray photograph of a metal element
of the material on the surface of pulp fibers of the ink
jet recording sheet was taken by a scanning electron
microscope and the covering rate on the support was
measured as an area ratio using an image analyzer.
[Shape factor of dot]
Single color dot was printed with a black ink
using an ink jet printer (IO-720 manufactured by Sharp
Corporation) and length of perimeter L of the dot and
area A of the dot were measured by an image analyzer,
and shape factor C of the dot defined by the following
formula was calculated. With the shape factor C
increasing and departing from 1.0, the shape of dot
becomes irregular due to spread of the dot.
C = L2/(4π × A)
where C denotes shape factor of dot, L denotes length of
perimeter of dot and A denotes area of dot.
[Examples 1-5 and Comparative Examples 1-4]
Example 1
[Preparation of base paper]
To a pulp slurry comprising 83 parts of LBKP
having a freeness of 450 ml cfs and 8 parts of NBKP
having a freeness of 480 ml csf were added 0.8 part of
cationized starch, 0.4 part of aluminum sulfate and 0.10
part of an alkyl ketene dimer, thereby adjusting the pH
of the pulp slurry to 8.2. A paper was prepared using
the pulp slurry by Fourdriner machine, dried and
finished by a machine calender. The resulting base
paper had a basis weight of 85 g/m2 and a Stöckigt
sizing degree of 25 seconds.
[Preparation of ink jet recording sheet]
On the thus obtained base paper was coated,
as a composition of ink-receiving layer, an aqueous
dispersion of 10% in solid concentration which was
mainly composed of 1000 parts of an aqueous dispersion
of acicular cation-modified colloidal silica (particle
size: 10-20 nm in width × 50-200 nm in length; cationic
charge quantity: 0.41 meq/g) prepared by modifying
acicular colloidal silica with aluminum oxide hydrate in
an amount of about 6.2% by weight in terms of Al2O3
based on silica (in terms of SiO2) and 50 parts of a 60%
aqueous solution of a cationic resin (Polyfix 601;
cationic charge quantity: 6.9 meq/g, manufactured by
Showa Kobunshi Co., Ltd.) as a dye fixer by a size press
so that the dry solid content was 0.5 g/m2 and the coat
was dried and calendered. Thus, an ink jet recording
sheet was obtained.
Example 2
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that the coating was
carried out using a rod coater so that the dry solid
content was 1.0 g/m2.
Example 3
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that the coating was
carried out using a transfer roll coater so that the dry
solid content was 3.0 g/m2.
Example 4
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that the coating was
carried out using an air knife coater so that the dry
solid content was 5.0 g/m2.
Comparative Example 1
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that the coating was
carried out using a size press so that the dry solid
content was 0.3 g/m2.
Comparative Example 2
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that the coating was
carried out using an air knife coater so that the dry
solid content was 5.5 g/m2.
Example 5
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that a 10% aqueous
dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length;
cationic charge quantity: 1.90 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 29.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2) was used in
place of the acicular cation-modified colloidal silica
used in Example 1 and the coating was carried out using
a transfer roll coater so that the dry solid content was
3.0 g/m2.
Comparative Example 3
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that 250 parts of a
40% aqueous dispersion of spherical colloidal silica
(primary particle size: 300 ± 30 nm; cationic charge
quantity: -0.01 meq/g) was used in place of the acicular
cation-modified colloidal silica used in Example 1 and
the coating was carried out using a transfer roll coater
so that the dry solid content was 3.0 g/m2.
Comparative Example 4
An ink jet recording sheet was prepared in the
same manner as in Example 1 except that 333 parts of a
30% aqueous dispersion of powdered silica (Nipsil E220A
manufactured by Japan Silica Kogyo Co., Ltd.; average
particle size: 1.0 µm; cationic charge quantity: -0.09
meq/g) was used in place of the acicular cation-modified
colloidal silica used in Example 1 and the coating was
carried out using a transfer roll coater so that the dry
solid content was 3.0 g/m2.
The ink jet recording sheets obtained in
Examples 1-5 and Comparative Examples 1-4 were evaluated
and the results are shown in Table 1.
Examples or Comparative Examples | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot |
Example 1 | A | 1.38 | A | 81 | 1.12 |
Example 2 | A | 1.30 | B | 72 | 1.15 |
Example 3 | A | 1.40 | A | 84 | 1.10 |
Example 4 | A | 1.52 | A | 96 | 1.08 |
Comparative Example 1 | C | 1.27 | C | 68 | 1.27 |
Comparative Example 2 | A | 1.52 | A | 95 | 1.10 |
Example 5 | A | 1.45 | A | 84 | 1.12 |
Comparative Example 3 | B | 1.23 | C | 65 | 1.20 |
Comparative Example 4 | B | 1.10 | C | 62 | 1.29 |
As can be seen from the results of Table 1,
the ink jet recording sheets of the present invention
were high in covering rate of the contour-coated layer,
superior in ink absorbability, image density and
sharpness, and small in shape factor of dot which
indicates shape of the recorded dot close to true
circle.
On the other hand, Comparative Examples 1 and
2 are examples where coating amount of the ink-receiving
layer was outside the range of the present invention.
In Comparative Example 1, ink absorbability and
sharpness were inferior and in Comparative Example 2,
the results were good, but the sheet was not preferable
to be handled as a plain paper. In Comparative Example
3, spherical colloidal silica was used and since it was
not cation-modified, sharpness of image was inferior,
the covering rate was low and the shape factor of dot
was inferior. In Comparative Example 4, since the
particle size of the inorganic pigment used was great,
sharpness of the image was inferior, the covering rate
was low and the shape factor of dot was inferior.
[Examples 6-11 and Comparative Examples 5-9]
Example 6
[Preparation of base paper]
To a pulp slurry comprising 83 parts of LBKP
having a freeness of 450 ml cfs and 8 parts of NBKP
having a freeness of 480 ml csf were added 0.8 part of
cationized starch, 0.4 part of aluminum sulfate and 0.10
part of an alkyl ketene dimer, thereby adjusting the pH
of the pulp slurry to 8.2. A paper was prepared using
the pulp slurry by Fourdriner machine, dried and
finished by a machine calender. The resulting base
paper had a basis weight of 85 g/m2 and a Stöckigt
sizing degree of 25 seconds.
[Preparation of ink jet recording sheet]
On the thus obtained base paper was coated, as
a composition of ink-receiving layer, an aqueous
dispersion of 10% in solid concentration which was
mainly composed of 1000 parts of a 10% aqueous
dispersion of acicular cation-modified colloidal silica
(particle size: 10-20 nm in width × 50-200 nm in length;
cationic charge quantity: 0.41 meq/g) prepared by
modifying acicular colloidal silica with aluminum oxide
hydrate in an amount of about 6.2% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 300 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and 50
parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity: 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
by a rod coater so that the dry solid content was 1 g/m2
and the coat was dried and calendered. Thus, an ink jet
recording sheet was obtained.
Example 7
An ink jet recording sheet was prepared in the
same manner as in Example 6 except that the coating was
carried out using a size press so that the dry solid
content was 0.5 g/m2.
Example 8
An ink jet recording sheet was prepared in the
same manner as in Example 6 except that the coating was
carried out using a rod coater so that the dry solid
content was 2 g/m2.
Example 9
An ink jet recording sheet was prepared in the
same manner as in Example 6 except that the solid
concentration of the aqueous dispersion was 15% and the
coating was carried out using an air knife coater so
that the dry solid content was 5 g/m2, followed by
drying and calendering.
Example 10
On the base paper prepared in Example 6 was
coated, as a composition of ink-receiving layer, an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 1000 parts of a 10% aqueous
dispersion of acicular cation-modified colloidal silica
(Snowtex UP-AK (1) manufactured by Nissan Chemical
Industries, Ltd., agglomerate, particle size: 10-20 nm
in width × 50-200 nm in length; cationic charge
quantity: 0.71 meq/g) prepared by modifying acicular
colloidal silica with aluminum oxide hydrate in an
amount of about 11% by weight in terms of Al2O3 based on
silica (in terms of SiO2), 300 parts of a 10% aqueous
solution of polyvinyl alcohol (PVA 117 manufactured by
Kuraray Co., Ltd.) as an adhesive and 100 parts of a 30%
aqueous solution of a cationic resin (Sumirez Resin
1001; cationic charge quantity 3.5 meq/g, manufactured
by Sumitomo Chemical Co., Ltd.) as a dye fixer by a
transfer roll coater so that the dry solid content was
2 g/m2 and the coat was dried and calendered. Thus, an
ink jet recording sheet was obtained.
Example 11
On the base paper prepared in Example 6 was
coated, as a composition of ink-receiving layer, an
aqueous dispersion of 15% in solid concentration which
was mainly composed of 1000 parts of a 10% aqueous
dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length;
cationic charge quantity: 1.90 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 29.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 300 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and 50
parts of a 60% aqueous solution of a cationic resin
(Polyfix 601; cationic charge quantity 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
by an air knife coater so that the dry solid content was
5 g/m2 and the coat was dried and calendered. Thus, an
ink jet recording sheet was obtained.
Comparative Example 5
On the base paper prepared in Example 6 was
coated, as a composition of ink-receiving layer, an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 250 parts of a 40% aqueous
dispersion of spherical colloidal silica (primary
particle size: 300 ± 30 nm; cationic charge quantity:
-0.01 meq/g), 300 parts of a 10% aqueous solution of
polyvinyl alcohol (PVA 117 manufactured by Kuraray Co.,
Ltd.) as an adhesive and 50 parts of a 60% aqueous
solution of a cationic resin (Polyfix 601; cationic
charge quantity 6.9 meq/g, manufactured by Showa
Kobunshi Co., Ltd.) as a dye fixer by a transfer roll
coater so that the dry solid content was 2 g/m2 and the
coat was dried and calendered. Thus, an ink jet
recording sheet was obtained.
Comparative Example 6
On the base paper prepared in Example 6 was
coated, as a composition of ink-receiving layer, an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 333 parts of a 30% aqueous
dispersion of spherical colloidal silica (primary
particle size: 80 nm; cationic charge quantity: 0.80
meq/g) which was prepared by modifying spherical
colloidal silica with aluminum oxide hydrate in an
amount of 12.5% by weight in terms of Al2O3 based on
silica (in terms of SiO2), 300 parts of a 10% aqueous
solution of polyvinyl alcohol (PVA 117 manufactured by
Kuraray Co., Ltd.) as an adhesive and 50 parts of a 60%
aqueous solution of a cationic resin (Polyfix 601;
cationic charge quantity 6.9 meq/g, manufactured by
Showa Kobunshi Co., Ltd.) as a dye fixer by a rod coater
so that the dry solid content was 2 g/m2 and the coat
was dried and calendered. Thus, an ink jet recording
sheet was obtained.
Comparative Example 7
On the base paper prepared in Example 1 was
coated, as a composition of ink-receiving layer, an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 1000 parts of a 10% aqueous
dispersion of acicular colloidal silica (agglomerate,
particle size: 10-20 nm in width × 50-200 nm in length;
cationic charge quantity: -0.02 meq/g), 300 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and
100 parts of a 30% aqueous solution of a cationic resin
(Sumirez Resin 1001; cationic charge quantity 3.5 meq/g,
manufactured by Sumitomo Chemical Co., Ltd.) as a dye
fixer by a transfer roll coater so that the dry solid
content was 2 g/m2 and the coat was dried and
calendered. Thus, an ink jet recording sheet was
obtained.
Comparative Example 8
On the base paper prepared in Example 6 was
coated, as a composition of ink-receiving layer, an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 333 parts of a 30% aqueous
dispersion of powdered silica (Nipsil E220A manufactured
by Japan Silica Kogyo Co., Ltd.; average particle size:
1.0 µm; cationic charge quantity: -0.09 meq/g), 300
parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 50 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601; cationic charge quantity:
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a transfer roll coater so that the dry
solid content was 2 g/m2 and the coat was dried and
calendered. Thus, an ink jet recording sheet was
obtained.
Comparative Example 9
An ink jet recording sheet was prepared in the
same manner as in Comparative Example 7 except that the
solid concentration of the aqueous dispersion was 15%
and the coating was carried out using an air knife
coater so that the dry solid content was 5 g/m2,
followed by drying and calendering.
The ink jet recording sheets obtained in
Examples 6-11 and Comparative Examples 5-9 were
evaluated and the results are shown in Table 2.
Examples or Comparative Examples | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot |
Example 6 | A | 1.38 | A | 81 | 1.12 |
Example 7 | A | 1.30 | B | 72 | 1.15 |
Example 8 | A | 1.40 | A | 84 | 1.10 |
Example 9 | A | 1.52 | A | 96 | 1.08 |
Example 10 | A | 1.41 | A | 85 | 1.13 |
Example 11 | A | 1.48 | A | 93 | 1.10 |
Comparative Example 5 | B | 1.08 | C | 64 | 1.24 |
Comparative Example 6 | B | 1.15 | C | 69 | 1.21 |
Comparative Example 7 | A | 1.17 | C | 85 | 1.21 |
Comparative Example 8 | B | 1.12 | C | 49 | 1.36 |
Comparative Example 9 | C | 1.18 | B | 68 | 1.31 |
As can be seen from the results of Table 2, as
for the ink jet recording sheets of Examples 6-11 and
Comparative Examples 5-9, the ink jet recording sheets
of the Examples which used non-spherical colloidal
silica and had a covering rate within the range of the
present invention were superior in ink absorbability,
image density and sharpness, and small in shape factor
of dot which means shape of the recorded dot close to
true circle.
On the other hand, in Comparative Examples 5
and 6, spherical colloidal silica was used and hence,
the shape factor of the dot was great and shape of the
recorded dot was inferior. In Comparative Example 7,
acicular colloidal silica which was not cation-modified
was used in place of the acicular colloidal silica of
Example 10 which was cation-modified, and since the
colloidal silica was not cation-modified, image density
and sharpness were inferior. In Comparative Example 9,
the coating amount was large, namely, 5 g/m2, but the
covering rate was low because particle size of the
inorganic pigment used was great. In Comparative
Example 8, the coating amount was 2 g/m2 and the
particle size of the inorganic pigment used was great
and the covering rate was low.
[Examples 12-20 and Comparative Examples 10-15]
Example 12
To a pulp slurry comprising 90 parts of LBKP
having a freeness of 450 ml csf and 10 parts of NBKP
having a freeness of 480 ml csf were added 9 parts of
kaolin, 0.8 part of cationized starch, 0.4 part of
aluminum sulfate and 0.10 part of an alkyl ketene dimer,
thereby adjusting the pH of the pulp slurry to 8.2. A
paper was prepared using the pulp slurry by Fourdriner
machine and dried to obtain a base paper of 85 g/m2 in
basis weight. Subsequently, on the thus obtained base
paper was coated, as a composition of ink-receiving
layer, an aqueous dispersion of 4% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of acicular cation-modified colloidal
silica (particle size: 10-20 nm in width × 50-200 nm in
length, cationic charge quantity: 0.41 meq/g) prepared
by modifying acicular colloidal silica with aluminum
oxide hydrate in an amount of about 6.2% by weight in
terms of Al2O3 based on silica (in terms of SiO2), 50
parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity:
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a size press so that the dry solid
content was 0.5 g/m2 and the coat was dried and
calendered. Thus, an ink jet recording sheet was
obtained.
Example 13
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that the composition
of ink-receiving layer had a solid concentration of 6%
and was coated using a size press so that the dry solid
content was 2 g/m2.
Example 14
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that the composition
of ink-receiving layer had a solid concentration of 10%
and was coated using a size press so that the dry solid
content was 4.5 g/m2.
Comparative Example 10
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that the composition
of ink-receiving layer had a solid concentration of 3%
and was coated using a size press so that the dry solid
content was 0.3 g/m2.
Comparative Example 11
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that the composition
of ink-receiving layer had a solid concentration of 12%
arid was coated using a size press so that the dry solid
content was 5.5 g/m2.
Example 15
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that as the
composition of ink-receiving layer, there was used an
aqueous dispersion of 6% in solid concentration which
was mainly composed of 1000 parts of a 10% aqueous
dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length,
cationic charge quantity: 1.90 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 29.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 100 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and
16.7 parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity: 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
and this was coated by a size press so that the dry
solid content was 2 g/m2 and the coat was dried and
finished by a machine calender to obtain an ink jet
recording sheet.
Example 16
A paper was prepared in the same manner as in
Example 12 and then, an oxidized starch was coated
thereon by a size press at 0.5 g/m2, dried and finished
by a machine calender to obtain a sized base paper used
in Example 16. Then, the 6% aqueous dispersion of
Example 15 was coated thereon, dried and calendered
under the same conditions as in Example 15 to prepare an
ink jet recording sheet. The dry solid content in this
case was 2.5 g/m2.
Example 17
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that as the composition
of ink-receiving layer, there was used an aqueous
dispersion of 8% in solid concentration which was mainly
composed of 1000 parts of a 10% aqueous dispersion of
columnar cationic colloidal silica used in Example 15
(particle size: 40 nm in width × 100-300 nm in length,
cationic charge quantity: 1.90 meq/g), 150 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and
16.7 parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity: 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
and this was coated by a size press and dried so that
the dry solid content was 2 g/m2 and finished by a
machine calender to obtain an ink jet recording sheet.
Comparative Example 12
An ink jet recording sheet was prepared in the
same manner as in Example 17 except that in place of the
columnar cationic colloidal silica used in Example 17
there was used 333 parts of a 30% aqueous dispersion of
spherical cationic colloidal silica (primary particle
size: 80 nm; cationic charge quantity: 0.80 meq/g)
prepared by modifying spherical colloidal silica with
aluminum oxide hydrate in an amount of 12.5% by weight
in terms of Al2O3 based on silica (in terms of SiO2).
The dry solid content was 2.0 g/m2.
Comparative Example 13
An ink jet recording sheet was prepared in the
same manner as in Example 17 except that in place of the
columnar cationic colloidal silica used in Example 17
there was used 1000 parts of a 10% aqueous dispersion of
acicular colloidal silica (agglomerate, particle size:
10-20 nm in width × 50-200 nm in length; cationic charge
quantity: -0.02 meq/g). The dry solid content was
2.0 g/m2.
Comparative Example 14
An ink jet recording sheet was prepared in the
same manner as in Example 6 except that in place of the
columnar cationic colloidal silica used in Example 17
there was used 333 parts of a 30% aqueous dispersion of
powdered silica (Nipsil E220A manufactured by Japan
Silica Kogyo Co., Ltd.; average particle size: 1.0 µm;
cationic charge quantity: -0.09 meq/g). The dry solid
content was 2.0 g/m2.
Example 18
An ink jet recording sheet was prepared in the
same manner as in Example 12 except that as the
composition of ink-receiving layer, there was used an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 1000 parts of a 10% aqueous
dispersion of columnar cationic colloidal silica used in
Example 15 (particle size: 40 nm in width × 100-300 nm
in length, cationic charge quantity: 1.90 meq/g), 200
parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity:
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer and this was coated by a size press and
dried so that the dry solid content was 4.0 g/m2 and
finished by a calender to obtain an ink jet recording
sheet.
Comparative Example 15
An ink jet recording sheet was prepared by
coating the 10% aqueous dispersion used in Example 18 by
an air knife coater, drying the coat and calendering the
dried coat. The dry solid content was 6.0 g/m2.
The ink jet recording sheets prepared in
Examples 12-18 and Comparative Examples 10-15 were
evaluated and the results are shown in Table 3.
Examples or Comparative Examples | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot |
Example 12 | A | 1.33 | B | 74 | 1.14 |
Example 13 | A | 1.40 | A | 86 | 1.09 |
Example 14 | A | 1.55 | A | 96 | 1.07 |
Comparative Example 10 | C | 1.26 | C | 66 | 1.28 |
Comparative Example 11 | A | 1.50 | A | 98 | 1.09 |
Example 15 | A | 1.38 | A | 85 | 1.10 |
Example 16 | A | 1.41 | A | 90 | 1.09 |
Example 17 | A | 1.36 | A | 83 | 1.12 |
Comparative Example 12 | B | 1.32 | C | 71 | 1.24 |
Comparative Example 13 | A | 1.35 | C | 82 | 1.25 |
Comparative Example 14 | B | 1.11 | C | 44 | 1.46 |
Example 18 | A | 1.34 | A | 78 | 1.08 |
Comparative Example 15 | A | 1.32 | A | 92 | 1.08 |
As can be seen from the results of Table 3,
the ink jet recording sheets of the present invention
were high in covering rate of the contour-coated layer
and superior in ink absorbability, image density and
sharpness, and small in shape factor of dot which means
shape of recorded dot close to true circle.
In Examples 12-14 and Comparative Examples 10-11,
the binder was used in the same amount. In Comparative
Example 10, the desired amount could not be coated
because the concentration of the coating solution was
low. On the other hand, Comparative Example 11 gave
good results, but since the concentration of the coating
solution was high, the layer was coated in an amount
more than needed and the sheet was not preferred to be
handled as a plain paper.
Example 15 and Example 16 compared unsized
base paper and sized base paper and when sized base
paper was used, a larger amount of layer could be coated
with the same concentration of coating liquid and the
sheet was superior in various characteristics.
[Examples 19-25 and Comparative Examples 16-21]
Example 19
[Preparation of base paper]
To a pulp slurry comprising 90 parts of LBKP
having a freeness of 450 ml csf and 10 parts of NBKP
having a freeness of 480 ml csf were added 9 parts of
kaolin, 0.8 part of cationized starch, 0.4 part of
aluminum sulfate and 0.10 part of an alkyl ketene dimer,
thereby adjusting the pH of the pulp slurry to 8.2. A
paper was prepared using the pulp slurry by Fourdriner
machine and size pressed with 0.5 g/m2 of oxidized
starch, thereafter, dried and finished by a machine
calender to obtain a base paper of 85 g/m2 in basis
weight.
[Preparation of ink jet recording sheet]
On the thus obtained base paper was coated, as
a composition for ink-receiving layer, an aqueous
dispersion of 10% in solid concentration which was
mainly composed of 1000 parts of a 10% aqueous dispersion
of acicular cation-modified colloidal silica
(particle size: 10-20 nm in width × 50-200 nm in length,
cationic charge quantity: 0.41 meq/g) prepared by
modifying acicular colloidal silica with aluminum oxide
hydrate in an amount of about 6.2% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 50 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and
16.7 parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity: 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
by a rod coater so that the dry solid content was 1.5
g/m2 and the coat was dried and calendered. Thus, an
ink jet recording sheet was obtained.
Example 20
An ink jet recording sheet was prepared in the
same manner as in Example 19 except that the composition
for ink-receiving layer had a solid concentration of 15%
and was coated using a rod coater so that the dry solid
content was 2.5 g/m2.
Example 21
An ink jet recording sheet was prepared in the
same manner as in Example 19 except that the composition
for ink-receiving layer had a solid concentration of 20%
and was coated using a rod coater so that the dry solid
content was 5.0 g/m2.
Comparative Example 16
An ink jet recording sheet was prepared in the
same manner as in Example 19 except that the composition
for ink-receiving layer had a solid concentration of 5%
and was coated using a rod coater so that the dry solid
content was 0.3 g/m2.
Comparative Example 17
An ink jet recording sheet was prepared in the
same manner as in Example 19 except that the composition
for ink-receiving layer had a solid concentration of 25%
and was coated using a rod coater so that the dry solid
content was 6.5 g/m2.
Example 22
On the base paper prepared in Example 19 was
coated an aqueous dispersion of 10% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length,
cationic charge quantity: 1.90 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 29.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 100 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and
16.7 parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
by a rod coater so that the dry solid content was 2.1
g/m2, dried and finished by a calender to obtain an ink
jet recording sheet.
Example 23
A base paper prepared in Example 19 without
size pressing was used in Example 23 as a base paper.
Then, the 10% aqueous dispersion of Example 22 was
coated, dried and calendered under the same conditions
to obtain an ink jet recording sheet. The dry solid
content was 1.3 g/m2.
Example 24
On the base paper prepared in Example 19 was
coated an aqueous dispersion of 15% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
used in Example 22 (particle size: 40 nm in width × 100-300
nm in length, cationic charge quantity: 1.90 meq/g),
150 parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity:
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a rod coater so that the dry solid
content was 2.0 g/m2, dried and finished by a calender
to obtain an ink jet recording sheet.
Comparative Example 18
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that in place of the
columnar cationic colloidal silica used in Example 24
there was used 333 parts of a 30% aqueous dispersion of
spherical cationic colloidal silica (primary particle
size: 80 nm; cationic charge quantity: 0.80 meq/g)
prepared by modifying spherical colloidal silica with
aluminum oxide hydrate in an amount of 12.5% by weight
in terms of Al2O3 based on silica (in terms of SiO2).
The dry solid content was 2.0 g/m2.
Comparative Example 19
An ink jet recording sheet was prepared in the
same manner as in Example 6 except that in place of the
columnar cationic colloidal silica used in Example 24
there was used 1000 parts of a 10% aqueous dispersion of
acicular colloidal silica (agglomerate, particle size:
10-20 nm in width × 50-200 nm in length; cationic
charge quantity: -0.02 meq/g). The dry solid content
was 2.0 g/m2.
Comparative Example 20
An ink jet recording sheet was prepared in the
same manner as in Example 24 except that in place of the
columnar cationic colloidal silica used in Example 24,
there was used 333 parts of a 30% aqueous dispersion of
powdered silica (Nipsil E220A manufactured by Japan
Silica Kogyo Co., Ltd.; average particle size: 1.0 µm;
cationic charge quantity: -0.09 meq/g). The dry solid
content was 1.8 g/m2.
Example 25
On the base paper prepared in Example 19 was
coated an aqueous dispersion of 20% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
used in Example 24 (particle size: 40 nm in width × 100-300
nm in length; cationic charge quantity: 1.90 meq/g),
200 parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity:
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a rod coater so that the dry solid
content was 4.5 g/m2, the coat was dried and finished by
a calender to obtain an ink jet recording sheet.
Comparative Example 21
An ink jet recording sheet was prepared by
coating the 20% aqueous dispersion used in Example 25,
drying and calendering the coat. The dry solid content
was 7.0 g/m2.
The ink jet recording sheets prepared in
Examples 19-25 and Comparative Examples 16-21 were
evaluated and the results are shown in Table 4.
Examples or Comparative Examples | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot |
Example 19 | A | 1.45 | A | 82 | 1.10 |
Example 20 | A | 1.48 | A | 88 | 1.08 |
Example 21 | A | 1.57 | A | 98 | 1.06 |
Comparative Example 16 | C | 1.20 | C | 63 | 1.30 |
Comparative Example 17 | A | 1.52 | A | 98 | 1.07 |
Example 22 | A | 1.44 | A | 91 | 1.10 |
Example 23 | A | 1.33 | A | 82 | 1.11 |
Example 24 | A | 1.38 | A | 85 | 1.10 |
Comparative Example 18 | B | 1.32 | C | 69 | 1.22 |
Comparative Example 19 | A | 1.34 | C | 81 | 1.23 |
Comparative Example 20 | B | 1.09 | C | 42 | 1.48 |
Example 25 | A | 1.50 | A | 93 | 1.10 |
Comparative Example 21 | A | 1.41 | A | 95 | 1.08 |
As can be seen from Table 4, the ink jet
recording sheets of the present invention were high in
covering rate of the contour-coated layer and superior
in ink absorbability, image density and sharpness, and
small in shape factor of dot which means that the shape
of recorded dot was close to a true circle.
In Examples 19-21 and Comparative Examples 16-17,
the binder was used in the same amount. In Comparative
Example 16, the desired amount of the layer could
not be coated because the concentration of the coating
liquid was low. On the other hand, Comparative Example
17 gave good results, but since the concentration of the
coating liquid was high, the layer was coated in an
amount more than needed and the sheet was not preferred
to be handled as a plain paper.
Example 22 and Example 23 compared unsized
base paper and sized base paper and when sized base
paper was used, a larger amount of layer could be coated
with the same concentration of coating solution and the
sheet was superior in various characteristics.
In Example 24 and Comparative Examples 18-20,
the material used was changed. When materials other
than those of the present invention were used, the
results were inferior.
In Example 25 and Comparative Example 21, the
coater was changed. When the sheet was prepared using
the air knife coater of Comparative Example 21, good
evaluation results were obtained, but since the
concentration of the coating liquid was high, the layer
was coated in an amount more than needed and the sheet
was not preferred to be handled as a plain paper.
[Examples 26-32 and Comparative Examples 22-27]
Example 26
To a pulp slurry comprising 90 parts of LBKP
having a freeness of 450 ml csf and 10 parts of NBKP
having a freeness of 480 ml csf were added 9 parts of
kaolin, 0.8 part of cationized starch, 0.4 part of
aluminum sulfate and 0.10 part of an alkyl ketene dimer,
thereby adjusting the pH of the pulp slurry to 8.2. A
paper was prepared using the pulp slurry by Fourdriner
machine and dried to obtain a base paper of 85 g/m2 in
basis weight. Subsequently, on the thus obtained base
paper was coated, as a composition for ink-receiving
layer, an aqueous dispersion of 10% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of acicular cation-modified colloidal
silica (particle size: 10-20 nm in width × 50-200 nm in
length; cationic charge quantity: 0.41 meq/g) prepared
by modifying acicular colloidal silica with aluminum
oxide hydrate in an amount of about 6.2% by weight in
terms of Al2O3 based on silica (in terms of SiO2), 50
parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a transfer roll coater so that the dry
solid content was 1.5 g/m2 and the coat was dried and
finished by a machine calender. Thus, an ink jet
recording sheet was obtained.
Example 27
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that the composition
for ink-receiving layer had a solid concentration of 15%
and was coated using a transfer roll coater so that the
dry solid content was 2.5 g/m2.
Example 28
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that the composition
for ink-receiving layer had a solid concentration of 20%
and was coated using a transfer roll coater so that the
dry solid content was 5.0 g/m2.
Comparative Example 22
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that the composition
for ink-receiving layer had a solid concentration of 5%
and was coated using a transfer roll coater so that the
dry solid content was 0.3 g/m2.
Comparative Example 23
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that the composition
for ink-receiving layer had a solid concentration of 25%
and was coated using a transfer roll coater so that the
dry solid content was 6.5 g/m2.
Example 29
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that as the
composition for ink-receiving layer, there was used an
aqueous dispersion of 10% in solid concentration which
was mainly composed of 1000 parts of a 10% aqueous
dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length;
cationic charge quantity: 1.90 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 29.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 100 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and
16.7 parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity 6.9 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
and this was coated by a transfer roll coater so that
the dry solid content was 1.3 g/m2 and the coat was
dried and finished by a machine calender to obtain an
ink jet recording sheet.
Example 30
A paper was prepared in the same manner as in
Example 26 and then, 0.5 g/m2 of an oxidized starch was
coated thereon by a size press, dried and finished by a
calender to obtain a sized base paper used in Example
30. Then, the 10% aqueous dispersion of Example 29 was
coated thereon, dried and calendered under the same
conditions to prepare an ink jet recording sheet. The
dry solid content was 2.1 g/m2.
Example 31
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that in place of the
composition for ink-receiving layer of Example 26, there
was used an aqueous dispersion of 15% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
used in Example 29 (particle size: 40 nm in width × 100-300
nm in length; cationic charge quantity: 1.90 meq/g),
150 parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer and this was coated by a transfer roll
coater so that the dry solid content was 2.0 g/m2, dried
and finished by a machine calender to obtain an ink jet
recording sheet.
Comparative Example 24
An ink jet recording sheet was prepared in the
same manner as in Example 31 except that in place of the
columnar cationic colloidal silica used in Example 31,
there was used 333 parts of a 30% aqueous dispersion of
spherical cationic colloidal silica (primary particle
size: 80 nm; cationic charge quantity: 0.80 meq/g)
prepared by modifying spherical colloidal silica with
aluminum oxide hydrate in an amount of 12.5% by weight
in terms of Al2O3 based on silica (in terms of SiO2).
The dry solid content was 2.0 g/m2.
Comparative Example 25
An ink jet recording sheet was prepared in the
same manner as in Example 31 except that in place of the
columnar cationic colloidal silica used in Example 31,
there was used 1000 parts of a 10% aqueous dispersion of
acicular colloidal silica (particle size: 10-20 nm in
width × 50-200 nm in length); cationic charge quantity:
-0.02 meq/g). The dry solid content was 2.0 g/m2.
Comparative Example 26
An ink jet recording sheet was prepared in the
same manner as in Example 31 except that in place of the
columnar cationic colloidal silica used in Example 31,
there was used 333 parts of a 30% aqueous dispersion of
powdered silica (Nipsil E220A manufactured by Japan
Silica Kogyo Co., Ltd.; average particle size: 1.0 µm;
cationic charge quantity: -0.09 meq/g). The dry solid
content was 1.8 g/m2.
Example 32
An ink jet recording sheet was prepared in the
same manner as in Example 26 except that in place of the
composition for ink-receiving layer of Example 26, there
was used an aqueous dispersion of 20% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
used in Example 29 (particle size: 40 nm in width × 100-300
nm in length; cationic charge quantity: 1.90 meq/g),
200 parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 16.7 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer and this was coated by a transfer roll
coater so that the dry solid content was 4.5 g/m2 and
dried and finished by a machine calender to obtain an
ink jet recording sheet.
Comparative Example 27
An ink jet recording sheet was prepared by
coating the 20% aqueous dispersion used in Example 32 by
an air knife coater, drying the coat and calendering the
dried coat. The dry solid content was 5.5 g/m2.
The ink jet recording sheets prepared in
Examples 26-32 and Comparative Examples 22-27 were
evaluated and the results are shown in Table 5.
Examples or Comparative Examples | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot |
Example 26 | A | 1.42 | A | 81 | 1.12 |
Example 27 | A | 1.46 | A | 86 | 1.09 |
Example 28 | A | 1.55 | A | 97 | 1.05 |
Comparative Example 22 | C | 1.17 | C | 61 | 1.34 |
Comparative Example 23 | A | 1.50 | A | 96 | 1.08 |
Example 29 | A | 1.32 | A | 80 | 1.13 |
Example 30 | A | 1.43 | A | 89 | 1.11 |
Example 31 | A | 1.37 | A | 84 | 1.11 |
Comparative Example 24 | B | 1.30 | C | 66 | 1.24 |
Comparative Example 25 | A | 1.32 | C | 79 | 1.25 |
Comparative Example 26 | B | 1.06 | C | 41 | 1.50 |
Example 32 | A | 1.48 | A | 92 | 1.10 |
Comparative Example 27 | A | 1.45 | A | 93 | 1.09 |
As can be seen from the results of Table 5,
the ink jet recording sheets of the present invention
were high in covering rate of the contour-coated layer
and superior in ink absorbability, image density and
sharpness and small in shape factor of dot which means
that the shape of recorded dot was close to true circle.
In Examples 26-28 and Comparative Examples 22-23,
the binder was used in the same amount. In Comparative
Example 22, the desired amount of the layer could
not be coated because the concentration of the coating
liquid was low. On the other hand, Comparative Example
23 gave good results, but since the concentration of the
coating liquid was high, the layer was coated in an
amount more than desired and the sheet was not preferred
to be handled as a plain paper.
Example 29 and Example 30 compared unsized
base paper and sized base paper and when sized base
paper was used, a larger amount of layer could be coated
with the same concentration of coating liquid and the
sheet was superior in various characteristics.
In Example 31 and Comparative Examples 24-26,
the material used was changed. When materials other
than those of the present invention were used, the
results were inferior.
In Example 32 and Comparative Example 27, the
coater was changed. When the sheet was prepared using
the air knife coater of Comparative Example 27, good
evaluation results were obtained, but since the
concentration of the coating solution was high, the
layer was coated in an amount more than desired and
the sheet was not preferred to be handled as a plain
paper.
[Examples 33-39 and Comparative Examples 28-34]
Example 33
[Preparation of base paper]
To a pulp slurry comprising 90 parts of LBKP
having a freeness of 450 ml csf and 10 parts of NBKP
having a freeness of 480 ml csf were added 9 parts of
kaolin, 0.8 part of cationized starch, 0.4 part of
aluminum sulfate and 0.10 part of an alkyl ketene dimer,
thereby adjusting the pH of the pulp slurry to 8.2. A
paper was prepared using the pulp slurry by Fourdriner
machine and dried to obtain a base paper of 85 g/m2 in
basis weight. The cationic charge quantity of the
resulting base paper was previously measured to obtain
0.02 meq/100 g.
[Preparation of ink jet recording sheet]
On the thus obtained base paper was coated, as
a composition for ink-receiving layer, an aqueous dispersion
of 10% in solid concentration which was mainly
composed of 1000 parts of a 10% aqueous dispersion of
acicular cationic colloidal silica (particle size: 10-20
nm in width × 50-200 nm in length; cationic charge
quantity: 0.46 meq/g) prepared by modifying acicular
colloidal silica with aluminum oxide hydrate in an
amount of about 7.0% by weight in terms of Al2O3 based
on silica (in terms of SiO2), 50 parts of a 10% aqueous
solution of polyvinyl alcohol (PVA 117 manufactured by
Kuraray Co., Ltd.) as an adhesive and 16.7 parts of a
60% aqueous solution of a cationic resin (Polyfix 601,
cationic charge quantity 6.9 meq/g, manufactured by
Showa Kobunshi Co., Ltd.) as a dye fixer by a transfer
roll coater so that the dry solid content was 0.5 g/m2
and the coat was dried and finished by a machine
calender. Thus, an ink jet recording sheet was
obtained. The total cationic charge quantity of the
resulting ink jet recording sheet was measured by
colloidal titration to obtain 0.57 meq/100 g.
Example 34
An ink jet recording sheet was prepared in the
same manner as in Example 33 except that the ink-receiving
layer was coated so that the dry solid content
thereof was 2.0 g/m2. The total cationic charge
quantity of the resulting ink jet recording sheet
was measured by colloidal titration to obtain 2.30
meq/100 g.
Example 35
An ink jet recording sheet was prepared in the
same manner as in Example 33 except that the ink-receiving
layer was coated so that the dry solid content
thereof was 4.5 g/m2. The total cationic charge
quantity of the resulting ink jet recording sheet
was measured by colloidal titration to obtain 5.00
meq/100 g.
Comparative Example 28
An ink jet recording sheet was prepared in the
same manner as in Example 33 except that the ink-receiving
layer was coated so that the dry solid content
thereof was 0.3 g/m2. The total cationic charge
quantity of the resulting ink jet recording sheet
was measured by colloidal titration to obtain 0.35
meq/100 g.
Comparative Example 29
An ink jet recording sheet was prepared in the
same manner as in Example 39 except that in place of the
acicular cationic colloidal silica used in Example 33,
there was used 333 parts of a 30% aqueous dispersion of
spherical cationic colloidal silica (primary particle
size: 80 nm; cationic charge quantity: 0.80 meq/g)
prepared by modifying spherical colloidal silica with
aluminum oxide hydrate in an amount of 12.5% by weight
in terms of Al2O3 based on silica (in terms of SiO2).
The total cationic charge quantity of the resulting ink
jet recording sheet was measured by colloidal titration
to obtain 0.75 meq/100 g.
Comparative Example 30
An ink jet recording sheet was prepared in the
same manner as in Example 34 except that in place of the
acicular cationic colloidal silica used in Example 34,
there was used 1000 parts of a 10% aqueous dispersion of
acicular colloidal silica (agglomerate, particle size:
10-20 nm in width × 50-200 nm in length; cationic charge
quantity: -0.02 meq/g). The total cationic charge
quantity of the resulting ink jet recording sheet was
measured by colloidal titration to obtain 1.30 meq/100 g.
Example 36
On the base paper prepared in Example 33 was
coated an aqueous dispersion of 10% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length,
cationic charge quantity: 1.90 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 29.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 50 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and 50
parts of a 60% aqueous solution of a cationic resin
(Polyfix 601, cationic charge quantity 6.9 meq/g, manufactured
by Showa Kobunshi Co., Ltd.) as a dye fixer by
a rod coater so that the dry solid content was 1.0 g/m2,
dried and finished by a machine calender to obtain an
ink jet recording sheet. The total cationic charge
quantity of the resulting ink jet recording sheet
was measured by colloidal titration to obtain 3.40
meq/100 g.
Comparative Example 31
An ink jet recording sheet was prepared in the
same manner as in Example 36 except that in place of the
columnar cationic colloidal silica used in Example 36
there was used 333 parts of a 30% aqueous dispersion of
powdered silica (Nipsil E220A manufactured by Japan
Silica Kogyo Co., Ltd.; average particle size: 1.0 µm;
cationic charge quantity: -0.09 meq/g). The total
cationic charge quantity of the resulting ink jet
recording sheet was measured by colloidal titration to
obtain 1.70 meq/100 g.
Comparative Example 32
A base paper as prepared and dried in Example
33 was used as the ink jet recording sheet of Comparative
Example 32 as it was. The total cationic charge
quantity of the ink jet recording sheet was measured by
colloidal titration to obtain 0.02 meq/100 g.
Example 37
[Preparation of base paper]
To a pulp slurry comprising 90 parts of LBKP
having a freeness of 450 ml csf and 10 parts of NBKP
having a freeness of 480 ml csf were added 10 parts of
precipitated calcium carbonate (TP-121 manufactured by
Okutama Kogyo Co., Ltd.) as a loading material, 0.8 part
of cationized starch (Cato 3210 manufactured by Oji
National Co., Ltd.), 0.4 part of aluminum sulfate and
0.1 part of an alkyl ketene dimer (SPK-903 manufactured
by Arakawa Kagaku Co., Ltd.). Using the pulp slurry, a
paper was prepared by Fourdriner machine, dried and
finished by a machine calender to obtain a base paper of
85 g/m2 in basis weight. The cationic charge quantity
of the resulting base paper was previously measured to
obtain 3.50 meq/100 g.
[Preparation of ink jet recording sheet]
Using the thus obtained base paper, an ink jet
recording sheet was prepared in the same manner as in
Example 42 except that the ink-receiving layer was
coated so that the dry solid content thereof was 5.0
g/m2. The total cationic charge quantity of the
resulting ink jet recording sheet was measured by
colloidal titration to obtain 19.50 meq/100 g.
Comparative Example 33
An ink jet recording sheet was prepared in the
same manner as in Example 36 except that the ink-receiving
layer was coated so that the dry solid content
thereof was 5.5 g/m2. The total cationic charge
quantity of the resulting ink jet recording sheet
was measured by colloidal titration to obtain 21.10
meq/100 g.
Example 38
On the base paper prepared in Example 37 was
coated an aqueous dispersion of 10% in solid concentration
which was mainly composed of 1000 parts of a 10%
aqueous dispersion of columnar cationic colloidal silica
(particle size: 40 nm in width × 100-300 nm in length,
cationic charge quantity: 1.13 meq/g) prepared by
modifying columnar colloidal silica with aluminum oxide
hydrate in an amount of 17.5% by weight in terms of
Al2O3 based on silica (in terms of SiO2), 200 parts of a
10% aqueous solution of polyvinyl alcohol (PVA 117
manufactured by Kuraray Co., Ltd.) as an adhesive and 33
parts of a 30% aqueous solution of a cationic resin
(Sumirez Resin 1001, cationic charge quantity 3.5 meq/g,
manufactured by Showa Kobunshi Co., Ltd.) as a dye fixer
by an air knife coater so that the dry solid content was
3.0 g/m2, and the coat was dried and finished by a
machine calender to obtain an ink jet recording sheet.
The total cationic charge quantity of the resulting ink
jet recording sheet was measured by colloidal titration
to obtain 7.25 meq/100 g.
Example 39
The same composition for ink-receiving layer
as of Example 38 except that the solid concentration of
the aqueous dispersion was 4% was coated by a size press
so that the dry solid content thereof was 0.5 g/m2 and
the coat was dried and finished by a machine calender to
prepare an ink jet recording sheet. The total cationic
charge quantity of the resulting ink jet recording sheet
was measured by colloidal titration to obtain 4.05
meq/100 g.
Comparative Example 34
A base paper as prepared and dried in Example
37 was used, as it was, as the ink jet recording sheet
of Comparative Example 34. The total cationic charge
quantity of the resulting ink jet recording sheet was
measured by colloidal titration to obtain 3.50 meq/100 g.
The ink jet recording sheets prepared in
Examples 33-39 and Comparative Examples 28-34 were
evaluated and the results are shown in Table 6.
Examples or Comparative Examples | Total cationic charge quantity (meq./100 g) | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot |
Example 33 | 0.57 | A | 1.33 | B | 75 | 1.14 |
Example 34 | 2.30 | A | 1.41 | A | 86 | 1.09 |
Example 35 | 5.00 | A | 1.56 | A | 96 | 1.06 |
Comparative Example 28 | 0.35 | C | 1.24 | C | 65 | 1.27 |
Comparative Example 29 | 0.75 | B | 1.26 | C | 73 | 1.21 |
Comparative Example 30 | 1.30 | C | 1.29 | C | 84 | 1.28 |
Example 36 | 3.40 | A | 1.38 | A | 79 | 1.12 |
Comparative Example 31 | 1.70 | C | 1.08 | C | 40 | 1.48 |
Comparative Example 32 | 0.02 | D | 1.02 | D | 0 | 1.98 |
Example 37 | 19.50 | A | 1.56 | A | 99 | 1.05 |
Comparative Example 33 | 21.10 | A | 1.55 | A | 100 | 1.06 |
Example 38 | 7.25 | A | 1.32 | A | 91 | 1.10 |
Example 39 | 4.05 | A | 1.30 | A | 75 | 1.13 |
Comparative Example 34 | 3.50 | C | 1.06 | D | 0 | 1.76 |
As can be seen from the results of Table 6,
the ink jet recording sheets of the present invention
were high in covering rate of the contour-coated layer
and superior in ink absorbability, image density and
sharpness and small in shape factor of dot which means
that the shape of the recorded dot was close to true
circle.
In Examples 33-35 and Comparative Example 28,
comparison was made using the same acicular cationic
colloidal silica. As for the ink jet recording sheet of
Comparative Example 28 which was small in the coating
amount, the total cationic charge quantity was outside
the range of the present invention, the shape factor of
dot was great and both the ink absorbability and the
sharpness were inferior. In Example 33 and Comparative
Example 29, the same coating amount was employed, but in
the ink jet recording sheet of Comparative Example 29
where the material used was outside the scope of the
present invention, the shape factor of dot was great and
sharpness was inferior.
In Example 34 and Comparative Example 30, the
same coating amount was employed, but in the ink jet
recording sheet of Comparative Example 30 where the
material used was outside the scope of the present
invention, the shape factor of dot was great and both
the ink absorbability and the sharpness were inferior.
The ink jet recording sheet of Comparative Example 31
where powdered silica which was outside the present
invention was used was inferior in all of the
characteristics.
Regarding Example 37 and Comparative Example
33, the total cationic charge quantity of the ink jet
recording sheet of Example 37 was within the range of
the present invention and the sheet was superior in all
of the characteristics. On the other hand, in Comparative
Example 33 the coating amount was increased and the
total cationic charge quantity of the ink jet recording
sheet was also outside the range of the present invention.
The results of evaluation on the characteristics
were good, but the sheet was not preferable to be
handled as a plain paper.
In Comparative Examples 32 and 34, the base
paper was handled, as it was, as the ink jet recording
sheet and the sheet was inferior in all of the
characteristics.
[Examples 40-44 and Comparative Examples 35-42]
Preparation Example 1
A polyvinylamine copolymer was synthesized by
a known process, for example, by the process in accordance
with Japanese Patent Kokai No.4-11094. In a reaction
apparatus provided with a stirrer, a nitrogen-introducing
pipe and a cooling pipe were charged 4 g of
a starting material consisting of N-vinylformamide and
acrylonitrile at a molar ratio of 45/55 and 35.9 g of
desalted water. After the content was heated to 60°C
with stirring in a nitrogen gas stream, thereto was
added 0.12 g of 10 wt% aqueous solution of 2,2'-azobis-2-amidinopropane
dihydrochloride. The content was kept
at 60°C for 3 hours with stirring to obtain a copolymer.
The reaction rate of the monomers at this time was about
93%. Furthermore, concentrated hydrochloric acid in an
amount equivalent to the formyl group in the copolymer
was added to the copolymer, followed by keeping at 75°C
for 8 hours with stirring to hydrolyze the copolymer.
The resulting copolymer solution was added to acetone
and the precipitated polyvinylamine copolymer was vacuum
dried and dissolved in desalted water. The polyvinylamine
copolymer had a weight-average molecular weight of
about 80,000. The molar ratio of vinylamine measured by
the method of determination of the amount of primary
amine with copper-(ethylenedinitro)tetraacetic acid
described in "Bunseki Kagaku Binran" was about 40 mol%.
Preparation Example 2
A polyvinylamine copolymer was obtained in the
same manner as in Preparation Example 1 except that the
molar ratio of N-vinylformamide and acrylonitrile was
changed to 24/78. The weight-average molecular weight
of the polyvinylamine copolymer was about 80,000 and the
molar ratio of vinylamine was 20 mol%.
Preparation Example 3
A polyvinylamine copolymer was obtained in the
same manner as in Preparation Example 1 except that the
molar ratio of N-vinylformamide and acrylonitrile was
changed to 24/78 and polymerization time was 1 hour.
The weight-average molecular weight of the polyvinylamine
copolymer was about 30,000 and the molar ratio of
vinylamine was 20 mol%.
Preparation Example 4
A polyvinylamine copolymer was obtained in the
same manner as in Preparation Example 1 except that the
molar ratio of N-vinylformamide and acrylonitrile was
changed to 12/88. The weight-average molecular weight
of the polyvinylamine copolymer was about 70,000 and the
molar ratio of vinylamine was about 10 mol%.
[Preparation of base paper]
To a pulp slurry comprising 70 parts of LBKP
having a freeness of 380 ml csf and 30 parts of NBKP
having a freeness of 450 ml csf were added 10 parts of
precipitated calcium carbonate (TP 121 manufactured by
Okutama Kogyo Co., Ltd.) as a loading material, 0.6 part
of aluminum sulfate, 0.1 part of an alkyl ketene dimer
(Sizepine K903 manufactured by Arakawa Kagaku Co., Ltd.)
and 0.8 part of amphoteric starch (Cato 3210 manufactured
by Oji National Co., Ltd.). Using the pulp
slurry, a paper was prepared by Fourdriner machine,
dried and finished by a machine calender to obtain a
base paper of 85 g/m2 in basis weight.
[Base paper prepared using polyvinylamine copolymer]
Base papers were prepared using polyvinylamine
copolymers in the above formulation of the base paper
with changing the kind and the amount of the polyvinylamine
copolymers as shown in Table 7.
Base paper | Polyvinylamine copolymer | Molecular weight | Molar ratio (%) | Amount (Part) |
Base paper 1 | No | - | - | - |
Base paper 2 | Preparation Example 1 | About 80,000 | 40 | 1 |
Base paper 3 | Preparation Example 1 | About 80,000 | 40 | 3 |
Base paper 4 | Preparation Example 2 | About 80,000 | 20 | 3 |
Base paper 5 | Preparation Example 3 | About 30,000 | 20 | 3 |
Base paper 6 | Preparation Example 4 | About 70,000 | 10 | 3 |
Example 40
An ink jet recording sheet was prepared using
the base paper 2 obtained above and an ink-receiving
layer was coated thereon.
On the base paper was coated, as a composition
for ink-receiving layer, an aqueous dispersion of 10% in
solid concentration which was mainly composed of 1000
parts of a 10% aqueous dispersion of acicular cationic
colloidal silica (particle size: 10-20 nm in width ×
50-200 nm in length; cationic charge quantity: 0.46
meq/g) prepared by modifying acicular colloidal silica
with aluminum oxide hydrate in an amount of about 7.0%
by weight in terms of Al2O3 based on silica (in terms of
SiO2), 50 parts of a 10% aqueous solution of polyvinyl
alcohol (PVA 117 manufactured by Kuraray Co., Ltd.) as
an adhesive and 16.7 parts of a 60% aqueous solution of
a cationic resin (Polyfix 601, cationic charge quantity
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a transfer roll coater so that the dry
solid content was 3.0 g/m2 and dried and finished by a
machine calender. Thus, an ink jet recording sheet was
obtained.
Example 41
An ink jet recording sheet was prepared by
coating an ink-receiving layer on the base paper 3
obtained above.
On the base paper was coated, as a composition
for ink-receiving layer, an aqueous dispersion of 10% in
solid concentration which was mainly composed of 1000
parts of a 10% aqueous dispersion of columnar cationic
colloidal silica (particle size: 40 nm in width × 100-300
nm in length, cationic charge quantity: 1.90 meq/g)
prepared by modifying columnar colloidal silica with
aluminum oxide hydrate in an amount of 29.5% by weight
in terms of Al2O3 based on silica (in terms of SiO2), 50
parts of a 10% aqueous solution of polyvinyl alcohol
(PVA 117 manufactured by Kuraray Co., Ltd.) as an
adhesive and 34 parts of a 60% aqueous solution of a
cationic resin (Polyfix 601, cationic charge quantity
6.9 meq/g, manufactured by Showa Kobunshi Co., Ltd.) as
a dye fixer by a size press so that the dry solid
content was 0.5 g/m2, and the coat was dried and
finished by a machine calender to obtain an ink jet
recording sheet.
Example 42
An ink jet recording sheet was prepared in the
same manner as in Example 41 except that a rod coater is
used in place of the size press and the coating amount
was 1.0 g/m2.
Example 43
An ink jet recording sheet was prepared in the
same manner as in Example 41 except that an air knife
coater was used in place of the size press, the concentration
of the coating liquid for ink-receiving layer was
15% and the coating amount was 5.0 g/m2.
Comparative Example 35
An ink jet recording sheet was prepared in the
same manner as in Example 41 except that the coating
amount was 0.3 g/m2.
Comparative Example 36
An ink jet recording sheet was prepared in the
same manner as in Example 41 except that an air knife
coater was used in place of the size press, the concentration
of the coating liquid for ink-receiving layer was
15% and the coating amount was 5.5 g/m2.
Example 44
An ink jet recording sheet was prepared in the
same manner as in Example 40 except that the base paper
4 was used and a rod coater was used in place of the
transfer roll coater.
Comparative Example 37
An ink jet recording sheet was prepared in the
same manner as in Example 44 except that in place of the
acicular cationic colloidal silica used in Example 44,
there was used 333 parts of a 30% aqueous dispersion of
spherical cationic colloidal silica (primary particle
size: 80 nm; cationic charge quantity: 0.80 meq/g)
prepared by modifying spherical colloidal silica with
aluminum oxide hydrate in an amount of 12.5% by weight
in terms of Al2O3 based on silica (in terms of SiO2).
Comparative Example 38
An ink jet recording sheet was prepared in the
same manner as in Example 44 except that in place of the
acicular cationic colloidal silica used in Example 44,
there was used 1000 parts of a 10% aqueous dispersion of
acicular colloidal silica (an agglomerate, particle
size: 10-20 nm in width × 50-200 nm in length; cationic
charge quantity: -0.02 meq/g).
Comparative Example 39
An ink jet recording sheet was prepared in the
same manner as in Example 44 except that in place of the
acicular cationic colloidal silica used in Example 44,
there was used 333 parts of a 30% aqueous dispersion of
powdered silica (Nipsil E220A manufactured by Japan
Silica Kogyo Co., Ltd.; average particle size: 1.0 µm;
cationic charge quantity: -0.09 meq/g).
Comparative Examples 40-42
Ink jet recording sheets of Comparative
Example 40, Comparative Example 41 and Comparative
Example 42 were prepared in the same manner as in
Example 44 except that the base paper 5, the base paper
6 and the base paper 1 were used, respectively.
The ink jet recording sheets prepared in
Examples 40-44 and Comparative Examples 35-42 were
evaluated and the results are shown in Table 8.
Evaluation of the water resistance was conducted in the
following manner.
[Water resistance]
One drop of distilled water was dripped on a
letter portion and a ruled line portion printed with
magenta ink and the letter and the line were left to
stand to dry and then, the degree of spreading was
visually judged. The criteria for evaluation are as
follows:
A: The characteristics are good. B: The characteristics are practically
acceptable. C: The characteristics are bad.
Examples or Comparative Examples | Ink absorbability | Image density | Sharpness | Covering rate (%) | Shape factor of dot | Sharpness |
Example 40 | A | 1.44 | B | 89 | 1.08 | A |
Example 41 | A | 1.34 | A | 77 | 1.13 | A |
Example 42 | A | 1.35 | A | 83 | 1.11 | A |
Example 43 | A | 1.46 | A | 95 | 1.09 | A |
Comparative Example 35 | B | 1.23 | C | 69 | 1.25 | A |
Comparative Example 36 | A | 1.48 | A | 98 | 1.10 | A |
Example 44 | A | 1.46 | A | 88 | 1.09 | A |
Comparative Example 37 | B | 1.30 | C | 72 | 1.20 | A |
Comparative Example 38 | C | 1.23 | C | 81 | 1.25 | B |
Comparative Example 39 | C | 1.12 | C | 46 | 1.46 | B |
Comparative Example 40 | A | 1.45 | A | 87 | 1.10 | C |
Comparative Example 41 | A | 1.44 | A | 85 | 1.12 | C |
Comparative Example 42 | A | 1.43 | A | 86 | 1.11 | C |
As can be seen from the results of Table 8,
the ink jet recording sheets of the present invention
were high in covering rate of the contour-coated layer
and superior in ink absorbability, image density and
sharpness and small in shape factor of dot which means
that the shape of the recorded dot was close to a true
circle, and were excellent in water resistance.
In Examples 41-43 and Comparative Examples 35-36,
comparison was made using the same columnar cationic
colloidal silica. As for the ink jet recording sheet of
Comparative Example 35 which was small in the coating
amount, the shape factor of dot was great and the sharpness
was inferior. In the ink jet recording sheet of
Comparative Example 36, a large coating amount was
employed and the results of evaluation on the characteristics
were good, but the sheet was not preferred to be
handled as a plain paper.
In Example 44 and Comparative Examples 37-39,
the same coating amount was employed, but in the ink jet
recording sheets of Comparative Examples where the
material used was outside the scope of the present
invention, the shape factor of dot was great and the
sharpness was inferior.
As for the ink jet recording sheets of
Comparative Examples 40-42, the base paper used was
outside the present invention and they were inferior in
water resistance, though superior in other characteristics.
[Industrial Applicability]
The slightly coated type ink jet recording
sheet of the present invention comprises a support and
an ink-receiving layer which is contour-coated on the
support and mainly composed of a non-spherical cationic
colloidal silica and further, the total cationic charge
quantity is specified and the support used contains a
specific polyvinylamine copolymer, whereby no uneven
spread of ink occurs, ink absorbability is excellent,
density and sharpness of the recorded image are high,
the recorded dot is close to true circle and water
resistance is excellent.