WO2005003459A1

WO2005003459A1 - Method of producing coated inkjet printable paper directly on a papermaking machine

Info

Publication number: WO2005003459A1
Application number: PCT/FR2004/001502
Authority: WO
Inventors: Jean Fayard; Claude Riou
Original assignee: International Paper Sa
Priority date: 2003-06-26
Filing date: 2004-06-17
Publication date: 2005-01-13
Also published as: FR2856709B1; FR2856709A1

Abstract

The invention relates to a method of producing paper which is coated on at least one of the faces thereof, using at least 4 g/m2 per face of dry deposit, with an inkjet printable layer, whereby at least 50 wt.- % of the dry extract comprises pigments having a specific surface area which is greater than or equal to 100 m2/g and which is measured using the BET method, in accordance with French standard NF ISO 9277: 1995. The invention is characterised in that the step involving the coating of the inkjet printable layer is performed directly during the paper production process, in-line on a papermaking machine.

Description

The present invention relates to the technical field of stationery. More specifically, it relates to a new process for the production of high quality ink jet printable papers, this technique being equally well suited to the manufacture of matte, semi-glossy or glossy inkjet printable papers. . The inkjet printing technique has experienced a certain and growing success in recent years. This technique makes it possible to write letters or images using ink droplets ejected, by different technologies, towards a support, such as paper, on which they form points which create the image. The inks can be either aqueous-based (the most common) or solvent-based or oil-based, depending on the intended applications. The intrinsic qualities of inkjet technology explain its development: it offers high-speed recording possibilities, with little noise, allows contactless and impact-free recording, with high definition, gives access to images of quality in color, with no development or fixation of the image. In addition, major developments in electronics, ensuring wide distribution and improved performance of personal computers and digital cameras, and the increasingly cheaper purchase prices of inkjet printers, have led more and more users towards this inkjet printing technology. Today inkjet printing technology is used to print letters, reports, brochures, digital photographs, postcards, labels, posters, etc. The requirements of users of this technology for inkjet printable media are therefore increasingly important. In this context, it is necessary to be able to supply papers that can be printed by inkjet, on the one hand, technical performance of the definition, color rendering, gloss, stability type, adapted to the increasingly sophisticated applications envisaged and , on the other hand, a reduced cost price to facilitate greater use. To date, it can be considered that there are two main families of supports for inkjet printing: supports called "ordinary papers" and supports called "special papers". The so-called “ordinary paper” supports make it possible to make prints of low to medium quality and are obtained at a low cost. These “ordinary papers” are produced on a paper machine according to a manufacturing process schematized by the following successive stages:

• arrival of a paper pulp by a head box of the paper machine on a formation and draining table to obtain a fibrous mattress, "pressing of the fibrous mattress thus formed, in the form of a sheet,

• drying,

"treatment by a sizing press, simple or at pre-dosage with a coating composition containing starch, a sizing agent and various additives, with a maximum deposit of 1 to 2.5 g of dry extract per m ² and per side. The coating composition used may be lightly pigmented with pigments, most often of the calcium carbonate or kaolin type. The percentage by weight of pigment does not exceed 50% of the total weight of the coating composition ,

• drying, "smoothing by calendering between rollers, in order to improve the surface condition of the paper and, consequently, its printability, and" winding. These supports are entirely produced on a paper machine and this, in a single operation linking all the above steps. The term “paper machine” designates all the elements or stations which are linked together to carry out the successive stages, ranging from the manufacture of a fibrous mat from a paper pulp, until a final sheet of paper. The production speeds of the supports, known as “ordinary papers”, are generally between 400 m / min and 1,500 m min and correspond to the running speed on the paper machine. These so-called “ordinary paper” supports are sold in price ranges close to those of normal reprographic paper. The “special” supports have a high quality rendering, but are obtained with a much higher cost price and are, therefore, much more expensive to purchase. These supports are obtained by additional coating, outside of the paper machine, of an adequate pigment formulation. The manufacturing process is therefore carried out in two operations. The first operation is identical to that described above is used for the manufacture of supports, called "ordinary papers". The second operation is carried out on another machine, called a coater, and comprises the following successive stages: ^B unwinding of the support,

• depositing a highly pigmented coating composition on the support, at a rate of 8 to 25 g of dry deposit per m ² and per side, using a specific coating technology, of the air knife type , curtain, waterfall, coating on chrome ... This coating composition generally contains more than 50% by weight of specific coating pigments, such as, for example, silica or alumina, "drying of the layer, "winding and, optionally, calendering of the coated paper obtained. The second coating operation is carried out at relatively low speeds, varying from 50 to 500 m / min, because of the need for correct drying of the thick layer deposited and the constraints inherent in certain coating technologies used, such as, for example , the coating on chrome which requires for the drying of the layer in contact with the chrome roller, the passage of water vapor through the fibers of the support. The manufacturing speeds, the complexity of the techniques used and the number of steps required explain the high cost of so-called “special” supports. In this context, the present invention aims to provide a new process for manufacturing high quality papers, printable by inkjet, and at a lower cost than that of “special” papers of the prior art, coated outside the paper machine. The process of the present invention also has the advantage of being suitable both for the manufacture of papers that can be printed by matt inkjet, semi-gloss or gloss. After a large number of tests, both in the laboratory and in the pilot, the inventors were able to demonstrate, after adaptations and adjustments on the paper machine, that it is possible to obtain high quality papers. , printable by inkjet, by coating a specific pigmented layer directly on a paper machine. The subject of the present invention is a process for manufacturing coated paper, on at least one of its faces, at a rate of at least 4 g / m ² per dry deposition face, with a printable layer. by inkjet, at least 50% by weight of the dry extract of which consists of pigments having a specific surface, measured according to the BET method, described in standard NF - ISO 9277: 1995, greater than or equal to 100 m ² / g, the step of coating the printable layer by ink jet being carried out directly during the manufacture of the paper, online on a paper machine. Producing inkjet printable papers online, on a paper machine, reduces manufacturing costs, since these papers are obtained in a single operation comprising different stages all carried out on a paper, whereas, until now, to obtain the same quality of paper, two operations, using complicated technologies, carried out on a paper machine, on the one hand, and on a coater, on the other hand, had to be implemented. It was not obvious for those skilled in the art to transpose the coating formulations used in non-machine coatings onto a paper machine. Indeed, the rheological properties and some of the essential components of the coating formulations had to be completely revised to adapt them to the constraints of coating on a paper machine, such as shear forces, speed and drying possibilities. In fact, the roller systems used at the size press (simple or pre-dosing), are generally used to make the layer penetrate at least partially in the support to reinforce its physical or mechanical properties, or in the case of the invention, it is important that the layer deposited remains as much as possible on the surface. This was obtained by using coating formulations comprising at least 50% of pigments such as silica or alumina having a specific surface greater than or equal to 100 m ² / g (measured according to the BET method, Brunauer, S., Emmet, PH, Teller, E., J. Am.Chem.Soc., 60.309A (1938), standard NF - ISO 9277: 1995). These pigments are not used directly on a paper machine because of their cost, their difficulty of dispersion and implementation. In addition, the viscosity of the coating dispersion had to be adjusted to values greater than or equal to 1500 cps measured at 25 ° C. with a Brookfield viscometer, at 100 rpm, mobile 6. These viscosity values are important because it the coating dispersion must not become too fluid under the effect of the shearing of the coating instrument (sizing press or other) otherwise the layer penetrates too much into the support and it is then not possible to obtain the properties inkjet required. By inkjet printable layer or paper is meant a high quality layer or paper giving good printing results with an inkjet printer, such as high color optical densities, no smearing of a color in another (in English "bleeding"), a high resolution and a precise and fine outline of the lines (in English "feathering"). We can, for example, define optical densities (d) of high colors as follows: on an HP 930 printer, with the plain paper setting, standard quality, at least d = 2.50 for black d = 1, 55 for cyan d = 1.37 for magenta d = 1, 10 for yellow. Optical densities are measured using a Gretag MacBeth D19C densitometer. It is also possible to define an ink jet printable paper, within the meaning of the invention, as a high quality paper of which at least one of its faces is coated with a pigmented layer of which at least 50% by weight of the dry extract is made up of pigments, this pigmented layer having a viscosity at 25 ° C greater than or equal to 1500 cps measured with a Brookfield viscometer, at 100 rpm, mobile 6, the coating being carried out at a rate of at least 4 g / m ² per dry deposit face of pigmented layer. The pigments of the pigmented layer are expensive pigments of the silica, silica gel, fumed silica or pyrogenic alumina type having a specific surface greater than or equal to 100 m ² / g (measured according to the BET method, Brunauer, S., Emmet, PH, Teller, E., J. Am.Chem.Soc., 60.309A (1938), standard NF - ISO 9277: 1995). More precisely, the method according to the invention comprises the following stages: "formation of a fibrous mat from a paper pulp and draining, * pressing of the fibrous mat thus formed, in the form of a sheet," drying of the sheet obtained "coating of the ink jet printable layer on the sheet of paper obtained after drying," drying, "smoothing," and winding. Apart from the coating step, the other steps are conventional for those skilled in the art of paper making. Pulp is made from cellulose fibers. These fibers are mainly extracted from wood or recovered paper or cardboard for recycling. The production of wood pulp consists in separating the cellulose fibers. According to the chosen process, of mechanical, chemical, semi-chemical, thermomechanical type, different kinds of pasta with different technical characteristics are obtained. Recycled pulp, for its part, is obtained by suspending in water recovered paper and cardboard products brewed in a pulper which ensures defibration. A purification operation intended to separate the fiber from the other products is then implemented. The pulp is optionally diluted to adapt its concentration before arriving on the paper machine and then deaerated. Mineral fillers such as calcium carbonate, kaolin, talc, titanium dioxide and adjuvants such as retention agents, dyes, defoamers, adhesives, optical brighteners can also be added. The first section of the paper machine consists of a head box intended to project the paper pulp then containing approximately 99.5% of water onto a training mat, in order to form a fibrous mat. This training mat is actually an endless cloth or sieve on which the fibrous mat will drip. This fabric is subjected to a jerky back and forth movement which facilitates the homogeneous formation of the fibrous carpet and its drainage. The fibers naturally tend to align themselves in the direction of movement of the flow of dough. Drainage is carried out by means of suction boxes and / or doctor blades which will suck through the fabric a certain proportion of the water contained in the fibrous mat. On leaving the training table, the fibrous mat contains 75 to 85% water. This percentage of water is reduced to around 55 - 70% in the press section. Pressing consists in compressing the fibrous mat between two cylinders covered with absorbent felt in order to obtain a sheet with reduced water content and having better compactness and an improved surface condition. The pre-drying step is then performed, for example, using steam heated rollers. Then deny the sleeping step which will be detailed later. Then the post-drying step is then carried out, for example, using steam heated rollers or sometimes with infrared radiant panels just after the press. At the end of the latter, the sheet of paper contains only about 4 to 6% of water. Smoothing is carried out by passing the sheet between rollers of polished steel (hard calendering) or between steel rollers and plastic coating (soft calendering), placed against each other. This calendering operation makes it possible to equalize the surface of the paper by compression. At the end of the paper machine, the sheet of paper is wound on a winder. The method according to the invention makes it possible to manufacture, directly on a paper machine, papers that can be printed by inkjet, as well mat, as semi-gloss or gloss. These papers have a print quality comparable to that of “special papers” of the prior art, but are obtained at a lower cost. In particular, their manufacturing process does not implement a second coating step outside of the paper machine on another industrial tool, since the coating of a pigmented formulation that is inkjet printable is carried out directly on the paper machine. , during the manufacture of the papers therefore according to a continuous process. The pigmented coating formulation is in the form of a dispersion comprising a porous or absorbent pigment having a specific surface greater than or equal to 100 m ² / g (measured according to the BET method, Brunauer, S., Emmet, PH, Teller , E., J. Am.Chem.Soc., 60.309A (1938), standard NF - ISO 9277: 1995), a polymeric binder, one or more additives, called rheological additives, intended to maintain the coating formulation at the surface of the paper while minimizing its penetration into the mass of the paper during the shearing occurring at level of the rollers, possibly a cationic compound intended to fix anionic inks, and additives traditionally used in stationery. As a polymeric binder, polyvinyl alcohol (PVA) or its derivatives, starches or their derivatives, celluloses or their derivatives may be used in an amount of 5 to 40% by weight of the dry extract of the formulation. The rheological additives will advantageously be chosen from polyvinylpyrrolidones (PVP) of different molecular weights and acrylic polymers of the Sterocol ^® type from BASF in an amount of 0.5 to 20% by weight of the dry extract of the formulation. These rheological additives are, in particular, important for the production of glossy or semi-glossy papers because, to obtain good gloss, it is essential that the layer remains on the surface of the support. In this case, it is therefore necessary that the viscosity, under the shearing of the coating formulation, remains high to avoid penetration into the mass of the paper. As cationic compound intended to fix anionic inks, mention may be made of polydadmac, dicyandiamide formaldehyde or polyamines in an amount of 0.5 to 20% by weight of the dry extract of the formulation. The conventional additives used in the manufacture of paper are, for example, defoamers, surfactants, brighteners, slip agents ... The pigment having a specific surface greater than or equal to 100 m ² / g

(measured according to the BET method, Brunauer, S., Emmet, PH, Teller, E., J. Am.Chem.Soc., 60.309A (1938), standard NF - ISO 9277: 1995) is chosen according to the quality of paper that one wishes to obtain, namely matte, semi-gloss or gloss. In the case of matt papers, use preferably a porous absorbent pigment or the type precipitated silica (e.g., FK320 DS or Sipernat ^® from Degussa) or silica gel (e.g., Sylojet ^® Grace). In the case of semi-glossy paper or glossy, use preferably a pigment of the type fumed silica (e.g. Aerosil ^® from Degussa) or fumed alumina (e.g. Disperal ^® HP 14 Sasol or Aluminum Oxide C from Degussa or Degussa VP W 630 dispersion). These pigments are in the form of very fine particles (of the order of a few tens of nanometers). These primary particles have no internal porosity but are in the form of aggregates (of of the order of 150-200 nm) which have porosity and can therefore create a micro-porous layer capable of absorbing the inks. In addition, these particles make it possible to develop a certain shine with a low smoothing at the end of the paper machine. The pigmented coating formulation has a Brookfield viscosity at

25 ° C greater than or equal to 1500 centipoise measured with a Brookfield viscometer, at 100 rpm, mobile 6. In the case of the production of matte or semi-glossy papers, the pigmented coating formulation is deposited using '' a metering size press (in English “metering size press”), a tool commonly installed on current paper machines, or a pre-metering press with two rollers (in English “gâte roll”) installed in line on the paper machine. It is therefore not necessary, for the manufacture of mat or semi-gloss papers according to the method of the invention, to use the heavy equipment commonly used in the prior art for the manufacture of "special papers" coated outside. paper machine. In the case of the production of glossy papers, the pigmented coating formulation is deposited using a coating system, of the trailing blade type, pencil on blade, curtain, spraying (“Spray coating” type from Metso), installed online on the paper machine. In the case of glossy papers, a preparation of the paper by passing through a size press with or without predosing integrated into the paper machine is generally carried out. This passage through a size press with or without pre-dosing serves to improve the mechanical properties and the surface condition of the support by depositing a solution of starch or any other polymer conventionally used in stationery, to which is optionally added a surface fining agent and a small amount of pigment (less than 50% by weight of the dry extract of the formulation), such a formulation being used conventionally in stationery and not being characteristic of the invention. The coating speed corresponds to the speed of the paper machine and is preferably between 400 and 1500 m / min. The pigmented coating formulation is applied on one or two sides (if a paper printable by inkjet on both sides) paper at a rate "of 4 to 6 g / m ^z dry deposition per side in the case of matt paper, • from 6 to 15 g / m ² of dry deposit per side in the case of semi-gloss papers, "and from 10 to 22 g / m ² of dry deposit per side in the case of glossy papers. In the case of a deposit on one side, on the back is deposited a non-functional layer for the inkjet intended to straighten the curl of the paper This back layer is composed of starch and, optionally, an inexpensive pigment (calcium carbonate, kaolin, etc.). A person skilled in the art of stationery is familiar with this type of formulation and is able to use the formulation adapted to obtain this straightening of the tile. The invention makes it possible to obtain papers which can be printed by ink jet which have ink jet performance comparable to the papers of the prior art coated outside the paper machine (optical densities of the colors, resolution of the lines, mixing of the colors) but at a much lower cost since they are made in a single operation The method according to the invention also makes it possible to obtain semi-gloss inkjet printable papers, after calendering on a paper machine, characterized by a gloss measured at 75 ° at the using a SHEEN model 156 glossmeter from 25 to 60 and, more precisely, from 35 to 50 and glossy inkjet printable papers, after calendering on a paper machine or super-calendering outside the machine, characterized by a gloss measured at 75 ° greater than 60. The gloss value depends on the weight of pigmented coating formulation deposited and on the way in which the calendering is carried out: pressure applied between the rollers, number of rollers, coating and hardness of these rollers. The examples which follow illustrate practical cases of implementation of the invention. These examples allow a better understanding of the invention and a good perception of all its advantages as well as its variant embodiments, without however limiting its scope.

EXAMPLES

EXAMPLE 1: Method for producing a mat inkjet paper. A paper machine is used, schematized by the sequence of the following stations: "Beloit Bel Baie II headbox, width 4.37 m, ^» Wet presses,

"pre - drying, 34 steam heated cylinders

"spoiler"

"post-drying, infrared panels and 16 steam-heated cylinders

"smooth with two steel rollers,

"winding.

The following dispersion 1 is prepared: based on FK 320 DS (precipitated silica) of

Degussa as a pigment. This pigment has a specific surface of 170 m ² / g (measured according to the BET method, Brunauer, S., Emmet, PH, Teller, E., J.

Am.Chem.Soc., 60.309A (1938), standard NF - ISO 9277: 1995)

This dispersion prepared at a Brookfield viscosity of 2500 cps is coated, on one face of the support, with the aid of the roll coating at the rate of 5 g / m ² of dry deposit. The other side of the support, for its part, is still coated with the roll coating, at a rate of 2 to 5 g / m ² of dry deposit with a dispersion of starch and kaolin prepared with 40% extract. dry, whose only technical justification is to straighten the paper tile.

A mat inkjet paper of 100 g / m ² , printable by ink jet on one side, is thus obtained at the speed of 700 m / min.

In the same way, dispersion 1 can be coated at the speed of 700 m / min, using the roll coating, on both sides of the paper, at a rate of 5 g / m ² by weight of material. dries per side, to obtain a mat inkjet paper printable by inkjet on both sides.

EXAMPLE 2: Method for producing a semi-gloss inkjet paper.

We use a paper machine shown schematically by the sequence of the following stations: "Beloit Bel Baie II head box, width 4.37 m," wet presses,

• pre - drying, 34 steam heated cylinders "squeeze roll" type press,

"post-drying, Infra-red panels and 16 steam-heated cylinders ¹ smooth with two steel rollers,

• winding.

The following dispersion 2 is prepared: based on MOX 170 from Degussa as a pigment. This pigment has a specific surface of 170 m ² / g (measured according to the BET method, Brunauer, S., Emmet, PH, TeUer, E., J. Am.Chem.Soc., 60.309A (1938), NF standard - ISO 9277: 1995)

This dispersion prepared at a Brookfield viscosity of 3000 cps is coated on one side of the support using the roll coating at the rate of 13 g / m ² of dry deposit.

The other side of the support, for its part, is still coated with the roll coating, at a rate of 5 to 8 g / m ² of dry deposit with a dispersion of starch and kaolin prepared at 40

% of dry extract, the only technical justification of which is to straighten the paper tile.

A semi-gloss ink jet paper of 130 g / m ² , printable by ink jet on one side, is thus obtained at the speed of 500 m / min.

Similarly, dispersion 2 can be coated at the speed of 450 m / min using the roll coating on both sides of the paper, at a rate of 13 g / m ² by weight of dry matter per side, to obtain a semi-gloss paper, printable by inkjet on both sides.

The gloss measured with a SHEEN model 156 glossmeter at 75 ° of such inkjet paper is 45.

EXAMPLE 3 Process for producing a semi-gloss inkjet paper.

We use a paper machine shown schematically by the sequence of the following stations: "Valmet headbox, width 6.65 m,

• wet presses,

"pre - drying of 39 steam heated cylinders,

"pre-dosing bar press" Optisizer with large Metso rod "type bar," post-drying, infrared panels and 15 steam-heated cylinders

»Smooth with two steel rollers

"winding.

The following dispersion 3 is prepared: based on Aluminum oxide C from Degussa as pigment. This pigment has a specific surface of 100 m ² / g (measured according to the BET method, Brunauer, S., Emmet, PH, TeUer, E., J. Am.Chem.Soc., 60.309A

(1938), standard NF - ISO 9277: 1995)

This dispersion prepared at a Brookfield viscosity of 2500 cps is coated, on one face of the support, using the pre-dosing press press at the rate of 12 g / m ² of dry deposition.

The other side of the support, for its part, is still coated using the pre-dosing press press at a rate of 5 to 8 g / m ² of dry deposit with a dispersion of starch and kaolin prepared at 40%. dry extract, the only technical justification for which is to straighten the paper tile.

A semi-gloss ink jet paper of 80 g / m ² , printable by ink jet on one side, is thus obtained at the speed of 600 m / min.

Likewise, dispersion 3 can be coated at a speed of 580 m / min using the pre-dosing presser on both sides of the paper, at a rate of 12 g / m ² by weight of dry matter. per side, to obtain a semi-gloss paper printable by inkjet on both sides.

The gloss measured with a SHEEN model 156 gloss meter at 75 ° of such inkjet paper is 50.

EXAMPLE 4 Process for producing a glossy inkjet paper.

We use a paper machine shown schematically by the sequence of the following positions Beloit Converflow headbox, width 4.72 m, wet presses, pre-drying of 35 steam-heated cylinders, pre-metering bar press of the “Optisizer de Metso” type bar, post-drying of 14 steam-heated cylinders , 2 Beloit dragging blades, Each dragging blade being followed by a dryer of 7 steam-heated cylinders, the first being teflon-coated to prevent the layer from adhering, Smooth with two steel rollers, winding.

At the size press, the following formulation, prepared with 22% of dry extract, is coated at the rate of 2 to 3 g / m ² of dry deposit:

The following dispersion 4 is prepared

This dispersion prepared at a Brookfield viscosity of 2500 cps is coated, on one face of the support, using the trailing blade, at a rate of 18 g / m ² of dry deposit. The other side of the support is coated with the other grating blade at the rate of 8 to 10 g / m ² of dry deposit with a dispersion of starch and calcium carbonate prepared at 50% dry extract, the only technical justification for which is to straighten the paper tile.

We thus obtain at the speed of 550 m / min, after calendering between the two steel rollers at the end of the machine, a shiny inkjet paper printable on one side of 120 g / m ² . Similarly, dispersion 4 can be coated at the speed of 500 m / min using trailing blades on both sides of the paper, at a rate of 18 g / m ² by weight of dry deposit per side, to obtain a glossy paper printable by inkjet on both sides.

The gloss measured using a SHEEN model 156 gloss meter at 75 ° of such inkjet paper is 65.

Claims

CLAIMS 1 - Process for manufacturing coated paper, on at least one of its faces, at a rate of at least 4 g / m ² per dry deposition face, with a layer that can be printed by ink jet, of which at least 50% by weight of the dry extract consists of pigments having a specific surface area measured according to the BET method, described in standard NF - ISO 9277: 1995, greater than or equal to 100 m ² / g, characterized in that l coating step of the

by inkjet is carried out directly during the production of paper, online on a paper machine. 2 - The manufacturing method according to claim 1, characterized in that it comprises the following successive steps, carried out on a paper machine: "formation of a fibrous mat from a paper pulp and draining," pressing of the fibrous mattress thus formed, in sheet form, "drying of the sheet obtained," coating of the printable layer by ink jet, on the sheet of paper obtained after drying, "drying," smoothing, "and winding. 3 - Manufacturing process according to claim 1 or 2, characterized in that the coating step is carried out using a pigmented coating formulation whose pigments are chosen from silica, silica gel, fumed silica and pyrogenic alumina. 4 - Manufacturing process according to one of claims 1 to 3, characterized in that the coating step is carried out from a pigmented coating formulation having a Brookfield viscosity at 25 ° C greater than or equal to 1500 centipoise. 5 - Manufacturing process according to one of claims 1 to 4, characterized in that the papers obtained are mat papers. 6 - Manufacturing process according to one of claims 1 to 4, characterized in that the papers obtained are semi-glossy papers. 7 - Manufacturing process according to one of claims 1 to 4, characterized in that the papers obtained are glossy papers. 8 - Manufacturing process according to one of claims 5 or 6, characterized in that the coating step is carried out on a press encoUeuse predosing film integrated in the paper machine. 9 - A manufacturing method according to one of claims 5 or 6, characterized in that the coating step is carried out on a press encoUeuse pre-dosage by two rollers integrated in the paper machine. 10 - The manufacturing method according to claim 7, characterized in that the coating step is carried out on a trailing blade coater, pencil on blade, curtain or spray, integrated in the paper machine.