CA2093553A1 - Preparation of an absorbent sheet - Google Patents
Preparation of an absorbent sheetInfo
- Publication number
- CA2093553A1 CA2093553A1 CA002093553A CA2093553A CA2093553A1 CA 2093553 A1 CA2093553 A1 CA 2093553A1 CA 002093553 A CA002093553 A CA 002093553A CA 2093553 A CA2093553 A CA 2093553A CA 2093553 A1 CA2093553 A1 CA 2093553A1
- Authority
- CA
- Canada
- Prior art keywords
- substance
- sheet
- screen
- deposition
- discharge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F13/00—Bandages or dressings; Absorbent pads
- A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
- A61F13/15577—Apparatus or processes for manufacturing
- A61F13/15617—Making absorbent pads from fibres or pulverulent material with or without treatment of the fibres
- A61F13/15658—Forming continuous, e.g. composite, fibrous webs, e.g. involving the application of pulverulent material on parts thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
- B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
Abstract
A B S T R A C T
A sheet of an absorbent material which, comprises a blend of a fibrous substance and of a granulated substance in which the granulated substance is non-uniformly distributed in the sheet, there being alternating zones of higher and of lower density of said substance along the sheet, is prepared by vacuum depositing (16) a dispersion of the fibrous substance (20) on a moving screen (14) and continuously applying the granulated substance (24) while changing the zone of application in a pendulum-like fashion (34, 36) along the screen.
A sheet of an absorbent material which, comprises a blend of a fibrous substance and of a granulated substance in which the granulated substance is non-uniformly distributed in the sheet, there being alternating zones of higher and of lower density of said substance along the sheet, is prepared by vacuum depositing (16) a dispersion of the fibrous substance (20) on a moving screen (14) and continuously applying the granulated substance (24) while changing the zone of application in a pendulum-like fashion (34, 36) along the screen.
Description
2093~3 ,~ -- 1 -- , PREPARATlON OF AN ABSORBENT SHEET
, . ~, .;,. ~ .- ;
FIELD OF THE INVENTION .`~ The present invention concerns means and process fOI the preparation of a sheet of absorbent material (hereinafter, at times "absorbent sheet"). More specifically, the present invention provides a process and 5 means for the formation of an absorbent sheet comprising a blend of a ~Irst, fibrous substance, and a second, granulatecl substance, wherein the second substance is non-uniformly distributed, there being portions of increased concentration of said second substance, where said second substance is most needed. ~ ;:
A specific application of the present application is in the formation of an absorbent sheet for use as an absorbent medium in disposable diapers.
'," "':.~'' `',' BACKGROUND OF THE lNVENTION
Disposable diapers generally comprise a liquid absorbent layer sandwiched between an external, liquid impervious layer, and an internal, liquid permeable liner. In order to perform its function well, the absorbeni ~ ~layer has to be capable of absorbing large quantities of liquids, many folds ~ :
2093~3 larger than its own weight. The main component of the absorbent layer is a fibrobs substance such as wood pulp fibers, and in order to improve the liquid absorbance, this layer is supplemented with granules of super absorbent polymers (SAP) which typically constitute about 17-20% of the absorbent layer. SAP is capable of absorbing about 35-40 times its weight in liquid whereas wood pulp fibers are capable of absorbing only about 7 times their weight in liquid. However, SAP, is an expensive material and costs about thxee times more than wood pulp fibers.
Good liquid absorbance is most important in the front half of the diaper at the area coming in contact with the child's genitals and crotch region. Thus, in view of its high price tag it would have been desirable to have the bulk of the SAP in a diaper in the front half and only a small part of the SAP in the rear half of the diaper. A very desirable ratio between the ,.-~ " . -- ~
amount of SAP in the front and in the rear half of the diaper would be about 8:2, i.e. 80% of the SAP in the front half of the diaper and only 20% in the rear half. However, none of the methods available to date in preparing a disposal diaper allows such a distribution of SAP.
The absorbent material of disposable diapers is typically formed as a continuous sheet, which is then sandwiched between the liquid impervious layer on the one hand and the liquid permeable liner on the other hand and cut according to the desired shape. The absorbent sheet is typically produced in a vacuum chamber having a moving screen at its bottom through which the vacuum is applied. Fibers are introduced into this chamber by a stream of air and are then deposited on the screen. The moving screen is typically a foraminous belt on which a continuous sheet of absorbent material is formed; or a rotating drum having shaped depression in which the fibres are deposited, whereby the formed sheet assumes some of the shape characteristics of the subsequently formed disposable diapers.
SAP is discharged from a pipe situated above the belt in the chamber and 2993~3 thus applies the SAP illtO the forming b]end of material which forms the sheet. In accordance with known means the SAP was either continuously applied, in which case it became evenly distributed along the formed sheet, and eventually evenly distributed in the produced disposable diapers, or 5 alternatively, the discharge pipe was provided with an intricate and very expensive valve mechanism which allowed the controlled intermittent discharge of SAP only on portions which cventually formed the front half of the disposable diaper.
None of these SAP application means enables to obtain about 10 an 8:2 distribution ratio mentioned above.
It is an object of the present invention to provide novel means for the preparation of an absorbent sheet comprising a blend of two substances, one being a fibrous substance and the other being a particulate substance, in which sheet, the second substance is unevenly distributed.
A particular object of the present invention is to provide means for the preparation of an absorbent sheet for use in disposable diapers in which SAP is located predominantly in the front half.
~ arious other objects of the invention will be eleviated in the following description and claims.
SUMMARY OF THE IN~IENTION
The present invention provides a process for the manufacture of a sheet of an absorbent material, the sheet comprising a blend of a first, fibrous substance, and of a second, granulated substance, said second 25 substance being non-uniformly distributed in said sheet, there being alternating zones of higher and of lower density of said second substance along said sheet, said process comprising:
introducing a dispersion of said first substance into a vacuum chamber having a continuous moving porous screen at its bottom, the 2ns~3s3 vacuum in the chamber being applied through saicl screen, whereby said first substance is being cleposited on said screen, and continuously discharging said second substance and depositing it onto an area of said screen from a discharge opening of a discharge means, said discharge means being adapted S to cyclically reciprocate the zone of deposition of the second substance on the screen between two points on a line parallel to the direction of movement of the screen; whereby zones of higher and of lower density of said second substance along said sheet are formed, two zones of equal density being distanced from one another by a distance equal to the distance 10 travelled by the belt during one cycle of reciprocation of said discharge means.
In accordance with a second aspect, the present invention provides an apparahls for the manufacture of a continuous sheet of an absorbent material, the sheet comprising a blend of a first fibrous substance 15 and of a second, granulated substance, said second substance being non~
uniformly distributed, there being alternating zones of higher and of lower density of said second substance along said sheet, said apparatus comprising:
a vacuum chamber having a foraminous screen at its bottom and capable of moving at a constant speed driving the sheet deposited thereon 20 through and out of said chamber, and having vacuum forming means adapted to form a vacuum through said screen;
means for introducing said first substance into said chamber in a dispersed form; and discharge means for said second substance having a discharge 25 opening adapted to continuously discharge said second substance and depositing it onto an area of said screen, and being further adapted to cyclically reciprocate the zone of deposition of the second substance on the belt between two points on a ]ine parallel to the direction of movement of the screen.
, . ~, .;,. ~ .- ;
FIELD OF THE INVENTION .`~ The present invention concerns means and process fOI the preparation of a sheet of absorbent material (hereinafter, at times "absorbent sheet"). More specifically, the present invention provides a process and 5 means for the formation of an absorbent sheet comprising a blend of a ~Irst, fibrous substance, and a second, granulatecl substance, wherein the second substance is non-uniformly distributed, there being portions of increased concentration of said second substance, where said second substance is most needed. ~ ;:
A specific application of the present application is in the formation of an absorbent sheet for use as an absorbent medium in disposable diapers.
'," "':.~'' `',' BACKGROUND OF THE lNVENTION
Disposable diapers generally comprise a liquid absorbent layer sandwiched between an external, liquid impervious layer, and an internal, liquid permeable liner. In order to perform its function well, the absorbeni ~ ~layer has to be capable of absorbing large quantities of liquids, many folds ~ :
2093~3 larger than its own weight. The main component of the absorbent layer is a fibrobs substance such as wood pulp fibers, and in order to improve the liquid absorbance, this layer is supplemented with granules of super absorbent polymers (SAP) which typically constitute about 17-20% of the absorbent layer. SAP is capable of absorbing about 35-40 times its weight in liquid whereas wood pulp fibers are capable of absorbing only about 7 times their weight in liquid. However, SAP, is an expensive material and costs about thxee times more than wood pulp fibers.
Good liquid absorbance is most important in the front half of the diaper at the area coming in contact with the child's genitals and crotch region. Thus, in view of its high price tag it would have been desirable to have the bulk of the SAP in a diaper in the front half and only a small part of the SAP in the rear half of the diaper. A very desirable ratio between the ,.-~ " . -- ~
amount of SAP in the front and in the rear half of the diaper would be about 8:2, i.e. 80% of the SAP in the front half of the diaper and only 20% in the rear half. However, none of the methods available to date in preparing a disposal diaper allows such a distribution of SAP.
The absorbent material of disposable diapers is typically formed as a continuous sheet, which is then sandwiched between the liquid impervious layer on the one hand and the liquid permeable liner on the other hand and cut according to the desired shape. The absorbent sheet is typically produced in a vacuum chamber having a moving screen at its bottom through which the vacuum is applied. Fibers are introduced into this chamber by a stream of air and are then deposited on the screen. The moving screen is typically a foraminous belt on which a continuous sheet of absorbent material is formed; or a rotating drum having shaped depression in which the fibres are deposited, whereby the formed sheet assumes some of the shape characteristics of the subsequently formed disposable diapers.
SAP is discharged from a pipe situated above the belt in the chamber and 2993~3 thus applies the SAP illtO the forming b]end of material which forms the sheet. In accordance with known means the SAP was either continuously applied, in which case it became evenly distributed along the formed sheet, and eventually evenly distributed in the produced disposable diapers, or 5 alternatively, the discharge pipe was provided with an intricate and very expensive valve mechanism which allowed the controlled intermittent discharge of SAP only on portions which cventually formed the front half of the disposable diaper.
None of these SAP application means enables to obtain about 10 an 8:2 distribution ratio mentioned above.
It is an object of the present invention to provide novel means for the preparation of an absorbent sheet comprising a blend of two substances, one being a fibrous substance and the other being a particulate substance, in which sheet, the second substance is unevenly distributed.
A particular object of the present invention is to provide means for the preparation of an absorbent sheet for use in disposable diapers in which SAP is located predominantly in the front half.
~ arious other objects of the invention will be eleviated in the following description and claims.
SUMMARY OF THE IN~IENTION
The present invention provides a process for the manufacture of a sheet of an absorbent material, the sheet comprising a blend of a first, fibrous substance, and of a second, granulated substance, said second 25 substance being non-uniformly distributed in said sheet, there being alternating zones of higher and of lower density of said second substance along said sheet, said process comprising:
introducing a dispersion of said first substance into a vacuum chamber having a continuous moving porous screen at its bottom, the 2ns~3s3 vacuum in the chamber being applied through saicl screen, whereby said first substance is being cleposited on said screen, and continuously discharging said second substance and depositing it onto an area of said screen from a discharge opening of a discharge means, said discharge means being adapted S to cyclically reciprocate the zone of deposition of the second substance on the screen between two points on a line parallel to the direction of movement of the screen; whereby zones of higher and of lower density of said second substance along said sheet are formed, two zones of equal density being distanced from one another by a distance equal to the distance 10 travelled by the belt during one cycle of reciprocation of said discharge means.
In accordance with a second aspect, the present invention provides an apparahls for the manufacture of a continuous sheet of an absorbent material, the sheet comprising a blend of a first fibrous substance 15 and of a second, granulated substance, said second substance being non~
uniformly distributed, there being alternating zones of higher and of lower density of said second substance along said sheet, said apparatus comprising:
a vacuum chamber having a foraminous screen at its bottom and capable of moving at a constant speed driving the sheet deposited thereon 20 through and out of said chamber, and having vacuum forming means adapted to form a vacuum through said screen;
means for introducing said first substance into said chamber in a dispersed form; and discharge means for said second substance having a discharge 25 opening adapted to continuously discharge said second substance and depositing it onto an area of said screen, and being further adapted to cyclically reciprocate the zone of deposition of the second substance on the belt between two points on a ]ine parallel to the direction of movement of the screen.
2~93~,3 In accordance with one embodiment of the invention, in a ~lrst half of the cycle the area of deposition moves at the same direction and at an average speed being essentially the same as that of the belt.
For many applications, e.g. in the case of absorbent sheets for S use in disposable cliapers, the second substance should have a higher concentration along the midline of the formed sheet and a lower concentra-tion at peripheral portions of the sheet and the discharge opening is thus preferably adapted to deposit said second substance on an area on the sheet's midline.
In accordance with the present invention, the density of the second substance in the formed sheet follows a longitudinal cyclical distnbution pattern, there being portions having a relatively high concentra-tion of said second substa1lce, these being the portions on which the second substance is deposited during the first half of the cycles; other portions in 15 between having a relatively low concentration of said substance, these being the portions on which said second substance is deposited during the second half of said cycle.
In accordance with one embodiment of the present invention, said discharge means is an elastic pipe, having an opening at its bottom end 20 which opening is situated above the belt, said bottom end being colmected to driving means adapted to reciprocate said bottom end between a first and a second position, whereby the zone of deposition of said second substance reciprocate between the two points on said line.
Suitably, said driving means consist of a driving wheel 25 connected to the bottom end of the pipe by means of a connecting rod, whereby rotation of said wheel causes reciprocation of the pipe's bottom end. The rotation of the driving wheel is typically coupled to and synchro-nized with the screen's movement.
2~93~3 _ 6 A specific embodiment of the present invention concerns the preparation of an absorbent sheet intended to be used as the absorbent layer of a disposable diaper. In such a case, the first substance will typically be wood pulp fibers and the second substance will typically be SAP. As will 5 be appreciated by the artisan, the distance between zones of equal density in sheets intended to be used as the absorbent layer of disposable diapeIs, is about equal to the diaper's length. Such a sheet is cut at a later stage of ; ~ .
manufacture in a manner so that a zone of high concentration of said second substance will be the front half o~ the diaper. -In the following the invention will be illustrated with reference to a specific embodiment concerned with the preparation of an absorbent sheet for use in the preparation of disposable diapers. It will no doubt be ~ .
appreciated by the artisan that the invention is not limited to this specific embodiment.
BRIEF DESCRIPI ION OF THE DR~WINGS
Fig. 1 is a schematical representation of an apparatus of the invention;
Fig. 2 shows a cross-sectional view through a sheet formed in the apparatus of Fig. 1; :;
Fig. 3 shows a view from above of a disposable diaper containing an absorbent layer prepared in accordance with the invention; and ~ ~ :
Fig. 4 is a schematical representation of a cross-section through lines 4-4 in Fig. 3.
25 DESCRIPrION OF A SPEC~FIC EMBODIP~ENT
Reference is first being made to Fig. 1 showing apparatus for the preparation of an absorbent sheet for disposable diapers. The apparatus shown schematically in Fig. 1 comprises a chamber 12 having in its bottom a continuously moYing foraminous belt 14. Vacuum in the chamber is ' ''~: `' 2093~ ~i3 : -formed through the belt, represented schematically by arrows 16, by appropriate vacuum forming means (not shown) knownper se. The vacuum chamber 12 has an inlct 18 through which a dispersed fibrous substance such as wood pulp fibers is introduced, typically by the use of pressurized S air represented schematically by arrow 20. As a result of the combined dispersion action of the pressurized air 20 and vacuum formed through belt 14, the fibers are being uniformly deposited on belt 14.
In chamber 12 there is also an elastic discharge pipe 22, adapted to discharge a granulated substance, such as SAP on the midline of the belt 14. Pipe 22 has a discharge opening 24 situated a short distance above belt 14. The bottom end 23 of pipe 22 is fitted with a clasp member 25 articulatecl to a rocl 26 pivotly connected to the periphery of driving wheel 28. Owing to the rotation of wheel 28, the pipe assumes a cyclical reciprocating, pendulum-like motion in a line parallel to the 15 direction of movement of the belt between a first position represented by a singly dotted line 30 and a second position represented by a triply dotted line 32. In the first position, the SAP discharged from pipe 22 is deposited on a first zone 34 ancl in the second position at zone 36.
In the first part of the cycle, when the pipe moves between 20 first position 30 to the seconcl position 32, the area of deposition advancesfrom zone 34 to zone 36 at an average speed being about the same as that of the belt, i.e. the SAP is deposited on about the same portion of the forming sheet, and in the second half of the cycle the pipe moves in the counter direction. The cycle time of the pipe's reciprocating movement is 25 the same as the time the belt travels a distance equal to the length of the formed sheet intended for a single diaper. Although the cycle time is constant, the distance travelled by the bottom end of the pipe can be ~ ~
changed by changing the position of clasp member 25. - -':~
.~:'. , ~.
20~33e753 In the speci~ic cmbodiment shown in Fig. 1, in which the distance between zone 34 and 36 is equal to about half a diaper length, the distribution of SAP in the formed sheet assumes a profile similar to that shown in Fig. 2 in which about 80~o of the SAP 48 is concentrated in the S first half 40 of each repeating unit 42 and only about 20% is concentrated in the second half 44.
For the production of the disposable diapers, the formed sheet are lined on one side with a liquid impervious layer (not shown) and on the other side with a liquicl permeable liner (also not shown) and then formed 10 into a disposable diaper by combining the three layers and then cutting to form the diapers.
A disposable diaper is shown in Fig. 3 and a schematical longitudinal cross-sectional view of the diaper is shown in Fig. 4. The diaper 50 has an internal liquid permeable liner i2, an intermediate 15 absorbent layer 54 and an external liquid impervious layer 56 fitted with adhesive fastening strips ~8. The absorbent layer 64 consists of a fibrous substance, e.g. wood pump 55 and SAP 56. As can be seen, the SAP 56 in the absorbent layer is unevenly distributed and concentrated mainly in the front half of the cliaper in the portion 60 marked by a dotted line. The 20 increased concentration of the SAP in the mid line of the diaper versus the periphery is in view of the fact that the discharge pipe is situated above the mid line of the formed felt-like sheet.
In the above embociiment, the sheet is formed on a foraminous belt. However, it will no doubt be appreciated by the artisan that the 25 invention may be practiced also where the sheet of absorbent material is formed by a process known as "drum forming". Such a process utilizes a rotahng foraminous drum, having typically foraminous depressions in which the sheet assumes some of the shape characteristics it will eventually have in the disposable diaper.
:
For many applications, e.g. in the case of absorbent sheets for S use in disposable cliapers, the second substance should have a higher concentration along the midline of the formed sheet and a lower concentra-tion at peripheral portions of the sheet and the discharge opening is thus preferably adapted to deposit said second substance on an area on the sheet's midline.
In accordance with the present invention, the density of the second substance in the formed sheet follows a longitudinal cyclical distnbution pattern, there being portions having a relatively high concentra-tion of said second substa1lce, these being the portions on which the second substance is deposited during the first half of the cycles; other portions in 15 between having a relatively low concentration of said substance, these being the portions on which said second substance is deposited during the second half of said cycle.
In accordance with one embodiment of the present invention, said discharge means is an elastic pipe, having an opening at its bottom end 20 which opening is situated above the belt, said bottom end being colmected to driving means adapted to reciprocate said bottom end between a first and a second position, whereby the zone of deposition of said second substance reciprocate between the two points on said line.
Suitably, said driving means consist of a driving wheel 25 connected to the bottom end of the pipe by means of a connecting rod, whereby rotation of said wheel causes reciprocation of the pipe's bottom end. The rotation of the driving wheel is typically coupled to and synchro-nized with the screen's movement.
2~93~3 _ 6 A specific embodiment of the present invention concerns the preparation of an absorbent sheet intended to be used as the absorbent layer of a disposable diaper. In such a case, the first substance will typically be wood pulp fibers and the second substance will typically be SAP. As will 5 be appreciated by the artisan, the distance between zones of equal density in sheets intended to be used as the absorbent layer of disposable diapeIs, is about equal to the diaper's length. Such a sheet is cut at a later stage of ; ~ .
manufacture in a manner so that a zone of high concentration of said second substance will be the front half o~ the diaper. -In the following the invention will be illustrated with reference to a specific embodiment concerned with the preparation of an absorbent sheet for use in the preparation of disposable diapers. It will no doubt be ~ .
appreciated by the artisan that the invention is not limited to this specific embodiment.
BRIEF DESCRIPI ION OF THE DR~WINGS
Fig. 1 is a schematical representation of an apparatus of the invention;
Fig. 2 shows a cross-sectional view through a sheet formed in the apparatus of Fig. 1; :;
Fig. 3 shows a view from above of a disposable diaper containing an absorbent layer prepared in accordance with the invention; and ~ ~ :
Fig. 4 is a schematical representation of a cross-section through lines 4-4 in Fig. 3.
25 DESCRIPrION OF A SPEC~FIC EMBODIP~ENT
Reference is first being made to Fig. 1 showing apparatus for the preparation of an absorbent sheet for disposable diapers. The apparatus shown schematically in Fig. 1 comprises a chamber 12 having in its bottom a continuously moYing foraminous belt 14. Vacuum in the chamber is ' ''~: `' 2093~ ~i3 : -formed through the belt, represented schematically by arrows 16, by appropriate vacuum forming means (not shown) knownper se. The vacuum chamber 12 has an inlct 18 through which a dispersed fibrous substance such as wood pulp fibers is introduced, typically by the use of pressurized S air represented schematically by arrow 20. As a result of the combined dispersion action of the pressurized air 20 and vacuum formed through belt 14, the fibers are being uniformly deposited on belt 14.
In chamber 12 there is also an elastic discharge pipe 22, adapted to discharge a granulated substance, such as SAP on the midline of the belt 14. Pipe 22 has a discharge opening 24 situated a short distance above belt 14. The bottom end 23 of pipe 22 is fitted with a clasp member 25 articulatecl to a rocl 26 pivotly connected to the periphery of driving wheel 28. Owing to the rotation of wheel 28, the pipe assumes a cyclical reciprocating, pendulum-like motion in a line parallel to the 15 direction of movement of the belt between a first position represented by a singly dotted line 30 and a second position represented by a triply dotted line 32. In the first position, the SAP discharged from pipe 22 is deposited on a first zone 34 ancl in the second position at zone 36.
In the first part of the cycle, when the pipe moves between 20 first position 30 to the seconcl position 32, the area of deposition advancesfrom zone 34 to zone 36 at an average speed being about the same as that of the belt, i.e. the SAP is deposited on about the same portion of the forming sheet, and in the second half of the cycle the pipe moves in the counter direction. The cycle time of the pipe's reciprocating movement is 25 the same as the time the belt travels a distance equal to the length of the formed sheet intended for a single diaper. Although the cycle time is constant, the distance travelled by the bottom end of the pipe can be ~ ~
changed by changing the position of clasp member 25. - -':~
.~:'. , ~.
20~33e753 In the speci~ic cmbodiment shown in Fig. 1, in which the distance between zone 34 and 36 is equal to about half a diaper length, the distribution of SAP in the formed sheet assumes a profile similar to that shown in Fig. 2 in which about 80~o of the SAP 48 is concentrated in the S first half 40 of each repeating unit 42 and only about 20% is concentrated in the second half 44.
For the production of the disposable diapers, the formed sheet are lined on one side with a liquid impervious layer (not shown) and on the other side with a liquicl permeable liner (also not shown) and then formed 10 into a disposable diaper by combining the three layers and then cutting to form the diapers.
A disposable diaper is shown in Fig. 3 and a schematical longitudinal cross-sectional view of the diaper is shown in Fig. 4. The diaper 50 has an internal liquid permeable liner i2, an intermediate 15 absorbent layer 54 and an external liquid impervious layer 56 fitted with adhesive fastening strips ~8. The absorbent layer 64 consists of a fibrous substance, e.g. wood pump 55 and SAP 56. As can be seen, the SAP 56 in the absorbent layer is unevenly distributed and concentrated mainly in the front half of the cliaper in the portion 60 marked by a dotted line. The 20 increased concentration of the SAP in the mid line of the diaper versus the periphery is in view of the fact that the discharge pipe is situated above the mid line of the formed felt-like sheet.
In the above embociiment, the sheet is formed on a foraminous belt. However, it will no doubt be appreciated by the artisan that the 25 invention may be practiced also where the sheet of absorbent material is formed by a process known as "drum forming". Such a process utilizes a rotahng foraminous drum, having typically foraminous depressions in which the sheet assumes some of the shape characteristics it will eventually have in the disposable diaper.
:
Claims (10)
1. A process for the manufacture of a sheet of an absorbent material, the sheet comprising a blend of a first, fibrous substance, and of a second, granulated substance, said second substance being non-uniformly distributed in said sheet, there being alternating zones of higher and of lower density of said second substance along said sheet, said process comprising:
introducing a dispersion of said first substance into a vacuum chamber having a continuous moving porous screen at its bottom, the vacuum in the chamber being applied through said screen, whereby said first substance is being deposited on said screen; and continuously discharging said second substance and depositing it onto an area of said screen from a discharge opening of a discharge means, said discharge means being adapted to cyclically reciprocate the zone of deposition of the second substance on the screen between two points on a line parallel to the direction of movement of the screen; whereby zones of higher and of lower density of said second substance along said sheet are formed, two zones of equal density being distanced from one another by a distance equal to the distance travelled by the belt during one cycle of reciprocation of said discharge means.
introducing a dispersion of said first substance into a vacuum chamber having a continuous moving porous screen at its bottom, the vacuum in the chamber being applied through said screen, whereby said first substance is being deposited on said screen; and continuously discharging said second substance and depositing it onto an area of said screen from a discharge opening of a discharge means, said discharge means being adapted to cyclically reciprocate the zone of deposition of the second substance on the screen between two points on a line parallel to the direction of movement of the screen; whereby zones of higher and of lower density of said second substance along said sheet are formed, two zones of equal density being distanced from one another by a distance equal to the distance travelled by the belt during one cycle of reciprocation of said discharge means.
2. A process according to Claim 1, wherein the zone of deposition of said substance is on the sheet's midline.
3. A process according to Claim 1, wherein in a first half of the cycle, the area of deposition moves at the same direction and at an average speed being essentially the same as that of the belt.
4. A process according to any one of Claim 1, for the manufac-ture of an absorbent sheet for use as an absorbent layer of a disposable diaper.
5. A process according to Claim 4, wherein said first substance is wood pulp and said second substance is a super absorbent polymer.
6. An apparatus for the manufacture of a continuous sheet of an absorbent material, the sheet comprising a blend of a first fibrous substance and of a second, granulated substance, said second substance being non-uniformly distributed, there being alternating zones of higher and of lower density of said second substance along said sheet, said apparatus comprising:
a vacuum chamber having a foraminous screen at its bottom and capable of moving at a constant speed, driving the sheet deposited thereon through and out of said chamber, and having vacuum forming means adapted to form a vacuum through said screen;
means for introducing said first substance into said chamber in a dispersed form; and discharge means for said second substance having a discharge opening adapted to continuously discharge said second substance and depositing it onto an area of said screen, and being further adapted to cyclically reciprocate the zone of deposition of the second substance on the belt between two points on a line parallel to the direction of movement of the screen.
a vacuum chamber having a foraminous screen at its bottom and capable of moving at a constant speed, driving the sheet deposited thereon through and out of said chamber, and having vacuum forming means adapted to form a vacuum through said screen;
means for introducing said first substance into said chamber in a dispersed form; and discharge means for said second substance having a discharge opening adapted to continuously discharge said second substance and depositing it onto an area of said screen, and being further adapted to cyclically reciprocate the zone of deposition of the second substance on the belt between two points on a line parallel to the direction of movement of the screen.
7. An apparatus according to Claim 6, wherein the area of deposition of said second substance is on the sheet's midline.
8. An apparatus according to Claim 6, wherein in a first half of a cycle the area of deposition moves at the same direction and at an average speed being essentially the same as that of the belt.
9. An apparatus according to any one of Claim 6, wherein said discharge means is an elastic pipe, having an opening at its bottom end which opening is situated above the screen, said bottom end being connected to driving means adapted to reciprocate said bottom end between a first and a second position, whereby the zone of deposition of said second substance reciprocates along said line.
10. An apparatus according to any one of Claim 6, wherein said driving means consist of a driving wheel connected to the bottom end of the pipe by means of a connecting rod, whereby rotation of said wheel causes reciprocation of the pipe's bottom end.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IL10492993A IL104929A (en) | 1993-03-03 | 1993-03-03 | Preparation of an absorbent sheet |
| IL104929 | 1993-03-03 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2093553A1 true CA2093553A1 (en) | 1994-09-04 |
Family
ID=11064585
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002093553A Abandoned CA2093553A1 (en) | 1993-03-03 | 1993-04-06 | Preparation of an absorbent sheet |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US5514324A (en) |
| EP (1) | EP0613726B1 (en) |
| AT (1) | ATE158959T1 (en) |
| CA (1) | CA2093553A1 (en) |
| DE (1) | DE69314464T2 (en) |
| IL (1) | IL104929A (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6066775A (en) | 1997-10-09 | 2000-05-23 | Amir Paper Products | Absorbent core and method for construction thereof |
| WO2000061300A1 (en) * | 1997-10-09 | 2000-10-19 | Amir Paper Products | Absorbent core and method for construction thereof |
| CN1332086C (en) | 1998-10-06 | 2007-08-15 | M&J纤维技术有限公司 | Plant for producing web-shaped product of fibres and powder |
| US20030100873A1 (en) * | 2001-10-31 | 2003-05-29 | Kent Hermansson | Disposable pant diaper |
| US20030129915A1 (en) * | 2002-01-04 | 2003-07-10 | Tyco Healthcare Retail Services Ag | Process for making a super absorbent polymer-impregnated non-woven absorbent core for personal hygiene products |
| US7001167B2 (en) * | 2002-07-30 | 2006-02-21 | Kimberly-Clark Worldwide, Inc. | Apparatus and form for making an air formed fibrous web |
| US7103445B2 (en) | 2002-11-27 | 2006-09-05 | Kimberly-Clark Worldwide, Inc. | System and method for controlling the dispense rate of particulate material |
| US7962993B2 (en) | 2005-09-30 | 2011-06-21 | First Quality Retail Services, Llc | Surface cleaning pad having zoned absorbency and method of making same |
| US7694379B2 (en) | 2005-09-30 | 2010-04-13 | First Quality Retail Services, Llc | Absorbent cleaning pad and method of making same |
| US20100310837A1 (en) * | 2009-06-03 | 2010-12-09 | Eric Bryan Bond | Structured fibrous web |
| US8759606B2 (en) * | 2009-06-03 | 2014-06-24 | The Procter & Gamble Company | Structured fibrous web |
| US20100312208A1 (en) * | 2009-06-03 | 2010-12-09 | Eric Bryan Bond | Fluid Permeable Structured Fibrous Web |
| US20100312212A1 (en) * | 2009-06-03 | 2010-12-09 | Eric Bryan Bond | Fluid Permeable Structured Fibrous Web |
| US20100310810A1 (en) * | 2009-06-03 | 2010-12-09 | Eric Bryan Bond | Structured Fibrous Web |
| US20100310845A1 (en) * | 2009-06-03 | 2010-12-09 | Eric Bryan Bond | Fluid permeable structured fibrous web |
| US9549858B2 (en) * | 2010-01-06 | 2017-01-24 | Ching-Yun Morris Yang | Ultra-thin absorbent article |
| US20110162989A1 (en) | 2010-01-06 | 2011-07-07 | Ducker Paul M | Ultra thin laminate with particulates in dense packages |
| GB2539668A (en) * | 2015-06-23 | 2016-12-28 | Concepts For Success (C4S E K) | Method for applying particles to a moving web and apparatus therefor |
| US11141320B2 (en) | 2016-03-31 | 2021-10-12 | Kimberly-Clark Worldwide, Inc. | Absorbent cores and methods for forming absorbent cores |
| CN108778204B (en) | 2016-03-31 | 2021-11-26 | 金伯利-克拉克环球有限公司 | Absorbent core and method of forming an absorbent core |
| KR102554740B1 (en) | 2016-03-31 | 2023-07-13 | 킴벌리-클라크 월드와이드, 인크. | Absorbent cores and methods for forming absorbent cores |
| US10918529B2 (en) | 2016-03-31 | 2021-02-16 | Kimberly-Clark Worldwide, Inc. | Absorbent cores and methods for forming absorbent cores |
| EP4218700A1 (en) * | 2016-08-05 | 2023-08-02 | Ontex BV | Improved particle dispersing device and method for absorbent articles |
Family Cites Families (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA588172A (en) * | 1959-12-01 | A. Fox Herbert | Fibrous mat and method of manufacture | |
| US2746895A (en) * | 1951-06-19 | 1956-05-22 | Wood Conversion Co | Manufacture of fibrer felts |
| DE1134009B (en) * | 1960-05-23 | 1962-07-26 | Mak Maschb Kiel G M B H | Method and device for boarding carded pile and / or wadding made from the same sections |
| US3187386A (en) * | 1960-06-23 | 1965-06-08 | Ind Dev Co Inc | Felting apparatus |
| US3939532A (en) * | 1972-05-15 | 1976-02-24 | Conwed Corporation | Manufacture of fibrous web structures |
| US4264289A (en) * | 1979-02-21 | 1981-04-28 | Kimberly-Clark Corporation | Apparatus for dry fiber forming |
| US4388056A (en) * | 1981-07-06 | 1983-06-14 | The Procter & Gamble Company | Apparatus for continuously making an air-laid fibrous web having patterned basis weight distribution |
| FR2544754B1 (en) * | 1983-04-20 | 1986-09-26 | Saint Gobain Isover | IMPROVEMENTS TO DEVICES FOR FORMING FIBER FELTS |
| SE447808B (en) * | 1985-05-08 | 1986-12-15 | Kmw Ab | KIT AND APPARATUS FOR PREPARING A MATERIAL COAT |
| US4927582A (en) * | 1986-08-22 | 1990-05-22 | Kimberly-Clark Corporation | Method and apparatus for creating a graduated distribution of granule materials in a fiber mat |
| US4927346A (en) * | 1986-12-08 | 1990-05-22 | Nordson Corporation | Apparatus for depositing particulate material into a pad of fibrous material in a forming chamber |
| NZ222302A (en) * | 1986-12-08 | 1989-09-27 | Nordson Corp | Spraying moisture absorbent particles into a layer of forming non woven wadding |
| US5017324A (en) * | 1986-12-08 | 1991-05-21 | Nordson Corporation | Method for depositing particulate material into a pad of fibrous material in a forming chamber |
| US5102585A (en) * | 1990-01-09 | 1992-04-07 | Kimberly-Clark Corporation | Method for intermittently depositing particulate material in a substrate |
| US5156902A (en) * | 1990-01-09 | 1992-10-20 | Kimberly-Clark Corporation | Method and apparatus for intermittently depositing particulate material in a substrate and article made therewith |
| US5028224A (en) * | 1990-01-09 | 1991-07-02 | Kimberly-Clark Corporation | Apparatus for intermittently depositing particulate material in a substrate |
| US5213817A (en) * | 1991-12-12 | 1993-05-25 | Mcneil-Ppc, Inc. | Apparatus for intermittently applying particulate powder material to a fibrous substrate |
| US5248524A (en) * | 1992-01-27 | 1993-09-28 | Paragon Trade Brands | Method and apparatus for zoned application of particles in fibrous material with dual dispensing nozzles |
| US5429788A (en) * | 1994-03-28 | 1995-07-04 | Kimberly-Clark Corporation | Apparatus and method for depositing particulate material in a composite substrate |
-
1993
- 1993-03-03 IL IL10492993A patent/IL104929A/en not_active IP Right Cessation
- 1993-04-05 AT AT93302661T patent/ATE158959T1/en not_active IP Right Cessation
- 1993-04-05 EP EP93302661A patent/EP0613726B1/en not_active Expired - Lifetime
- 1993-04-05 DE DE69314464T patent/DE69314464T2/en not_active Expired - Fee Related
- 1993-04-06 CA CA002093553A patent/CA2093553A1/en not_active Abandoned
- 1993-04-07 US US08/043,579 patent/US5514324A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| ATE158959T1 (en) | 1997-10-15 |
| EP0613726B1 (en) | 1997-10-08 |
| IL104929A0 (en) | 1993-07-08 |
| US5514324A (en) | 1996-05-07 |
| IL104929A (en) | 1995-11-27 |
| EP0613726A1 (en) | 1994-09-07 |
| DE69314464T2 (en) | 1998-03-26 |
| DE69314464D1 (en) | 1997-11-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |