HIGHLY ABSORBENT COMPOSITE AND METHOD OF MAKING THE SAME

• US 20100062165A1
• Filed: 11/17/2009
• Published: 03/11/2010
• Est. Priority Date: 12/13/1996
• Status: Active Grant

• Current Assignee: Migaku Suzuki, Ryoichi Matsumoto, Shingo Mori
• Original Assignee: Migaku Suzuki, Ryoichi Matsumoto, Shingo Mori
• Inventors: Mori, Shingo, Matsumoto, Ryoichi, SUZUKI, Migaku
• Granted Patent: US 9,163,355 B2
• Time in Patent Office: Days
• US Class Current: 427/372.200
• CPC Class Codes: A61F 13/53 characterised by the absorbing medium A61F13/20 takes precedence
• CPC Class Codes: A61F 13/5323 having absorbent material located in discrete regions, e.g. pockets
• CPC Class Codes: A61F 2013/530145 being short
• CPC Class Codes: A61L 15/28 Polysaccharides or their derivatives A61L15/225 takes precedence
• CPC Class Codes: A61L 15/60 Liquid-swellable gel-forming materials, e.g. super-absorbents
• CPC Class Codes: C08K 7/02 Fibres or whiskers
• CPC Class Codes: D06M 15/05 Cellulose or derivatives thereof
• CPC Class Codes: D06M 15/07 Cellulose esters
• CPC Class Codes: D06M 23/08 Processes in which the treating agent is applied in powder or granular form adhesives for multi-layer textile fabrics D06M17/00
• CPC Class Codes: D06M 23/10 Processes in which the treating agent is dissolved or dispersed in organic solvents; Processes for the recovery of organic solvents thereof
• CPC Class Codes: D06M 23/16 Processes for the non-uniform application of treating agents, e.g. one-sided treatment; Differential treatment
• CPC Class Codes: D21H 21/22 Agents rendering paper porous, absorbent or bulky
• CPC Class Codes: Y10T 428/13 Hollow or container type article [e.g., tube, vase, etc.]
• CPC Class Codes: Y10T 428/1303 Paper containing [e.g., paperboard, cardboard, fiberboard, etc.]
• CPC Class Codes: Y10T 428/1314 Contains fabric, fiber particle, or filament made of glass, ceramic, or sintered, fused, fired, or calcined metal oxide, or metal carbide or other inorganic compound [e.g., fiber glass, mineral fiber, sand, etc.]
• CPC Class Codes: Y10T 428/1348 Cellular material derived from plant or animal source [e.g., wood, cotton, wool, leather, etc.]
• CPC Class Codes: Y10T 428/1352 Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1359 Three or more layers [continuous layer]
• CPC Class Codes: Y10T 428/1362 Textile, fabric, cloth, or pile containing [e.g., web, net, woven, knitted, mesh, nonwoven, matted, etc.]
• CPC Class Codes: Y10T 428/1386 Natural or synthetic rubber or rubber-like compound containing
• CPC Class Codes: Y10T 428/139 : Open-ended, self-supporting conduit, cylinder, or tube-type article
• CPC Class Codes: Y10T 428/1393 : Multilayer [continuous layer]
• CPC Class Codes: Y10T 428/23921 : With particles
• CPC Class Codes: Y10T 428/23929 : Edge feature or configured or discontinuous surface
• CPC Class Codes: Y10T 428/23936 : Differential pile length or surface
• CPC Class Codes: Y10T 428/23979 : Particular backing structure or composition
• CPC Class Codes: Y10T 428/23993 : Composition of pile or adhesive
• CPC Class Codes: Y10T 428/296 : Rubber, cellulosic or silicic material in coating

Abstract

A composite structure mainly composed of hydratable fine fibers in the form of microfibril and a water swellable solid body, the fibers being obtained from cellulose or derivatives thereof, and at least part of the surface of the solid body is covered with the fine fibers. The absorbent composite can be formed in various form of, for example, particle, pellet, sheet and the like, especially of a sheet type with a supporting sheet of a non-woven fabric. The present invention further provides a method of making the composite structure.

Claims

1. A method of making a highly absorbent composite, comprising the steps of:

dispersing hydratable fine fibers in the form of microfibril obtained from cellulose or a derivative thereof and water-swellable solid body in a dispersion medium comprising a mixture of water and a water miscible organic solvent and being capable of suppressing the swelling of said water-swellable solid body and of hydrating and dispersing said hydratable fine fibers in the form of microfibril to form a dispersion liquid;

separating said water-swellable solid body and said hydratable fine fibers in the form of microfibril from said dispersion medium; and

removing the liquid component to separate the solid component and then drying.

2. The method of claim 1, wherein said dispersion liquid is applied onto a supporting sheet, and then liquid removing and drying are conducted, whereby a highly absorbent composite of absorbent polymer particles and hydratable fine fibers in the form of microfibril is formed on said supporting sheet.

3. The method of claim 1, wherein said organic solvent is one selected from a group consisting of alcohols such as methanol, ethanol and isopropyl alcohol, polyvalent alcohols such as ethylene glycol, diethylene glycol, propylene glycol, low molecular weight polyethylene glycol and glycerin and acetone, methyl ethyl ketone, dioxane and dimethyl sulfoxide, and any combination thereof.

4. The method of claim 1, wherein the suspension concentration of said hydratable fine fibers in the form of microfibril in said dispersion medium is 0.1 to 5 percent by weight and wherein the concentration of said absorbent polymer particles in said dispersion medium is 5 to 50 percent by weight based on the total weight of said dispersion liquid.

5. A method of making an absorbent sheet comprising the steps of:

preparing a three component dispersion slurry by adding and dispersing a short-cut staple fiber component and absorbent polymer particles in a dispersion liquid where hydratable fine fibers in the form of microfibril are dispersed in a dispersion medium;

forming a slurry layer by spreading said three component dispersion slurry on at least either surface of a supporting sheet; and

removing said dispersion medium from said slurry layer and then drying.

8. The method of claim 5, wherein said short-cut staple fiber component is thermally fusible fibers, and which further comprises the step of heating and melting said staple fiber component at the melting or higher temperatures, in or after said step of removing the dispersion medium.

6. A method of making an absorbent sheet comprising the steps of:

preparing a two component dispersion liquid by dispersing hydratable fine fibers in the form of microfibril and absorbent polymer particles in a dispersion medium;

forming a first slurry layer by spreading said two component dispersion liquid n at least either surface of a supporting sheet;

forming a second slurry layer covering said first slurry layer by feeding a dispersion liquid where a short-cut staple fiber component is dispersed in a dispersion medium from the top of said first slurry layer; and

removing said dispersion medium from said first and second slurry layers, and then drying.

7. A method of making an absorbent sheet comprising a supporting sheet, a first layer comprising two components of hydratable fine fibers in the form of microfibril and a short-cut staple fiber component, and a second layer comprising three components of absorbent polymer particles, a hydratable fine fibers in the form of microfibril and a short-cut staple fiber component, said first and second layers being laid on at least one surface of said supporting sheet in desired pattern, comprising the steps of:

forming a slurry layer by spreading said slurry where hydratable fine fibers in the form of microfibril and short-cut staple fiber component are dispersed in a dispersion medium so that said absorbent polymer particles are covered; and

removing said dispersion medium from said slurry layer containing absorbent polymer particles and then drying.

9. A method of making an absorbent sheet having a liquid pervious supporting sheet and an absorbent layer forming a plurality of highly absorbing areas having a higher absorbing capacity than the remaining areas distributed in a predetermined pattern, comprising the steps of:

preparing a dispersion liquid in the form of slurry containing absorbent polymer particles;

coating the surface of said liquid pervious supporting sheet with said dispersion liquid prepared in said suspending step so that a plurality of high absorption areas having higher absorbing capacity than the remaining areas and distributed in a desired pattern are formed; and

drying the absorption layer formed in said coating step.

10. The method of claim 9, wherein in said coating step the surface of said liquid pervious supporting sheet is coated with said dispersion liquid by pulsating the flow of said dispersion liquid.

11. The method of claim 9, wherein in said coating step the surface of said liquid pervious supporting sheet is coated with said dispersion liquid through discharge nozzles each having a plurality of discharge outlets.

12. The method of claim 9, wherein the route of feeding said dispersion liquid into said discharge nozzles is partially or wholly pulsated.

13. A method of making an absorbent sheet comprising the steps of:

feeding continuously a slurry containing absorbent polymer particles onto a liquid pervious sheet material having a number of dents with openings formed in the bottom thereof, whereby filling up said dents with said slurry and leaving only the solid component in said dents by allowing the solvent in said slurry to pass the sheet material through said openings; and

removing and drying said sheet material and said solid component.

14. A method of making an absorbent sheet comprising the steps of:

preparing a dispersion liquid in the form of slurry by dispersing absorbent polymer particles into a dispersion medium consisting of a water soluble polyvalent alcohol whose dependence on temperature is high or a mixture of said alcohol with water;

storing said dispersion liquid while keeping a low temperature to maintaining the viscosity of the dispersion liquid high;

forming said dispersion liquid into a sheet;

removing said dispersion medium from said sheet; and

drying said sheet to form a highly absorbent body;

wherein in said storage step said low temperature condition is kept to maintain the low viscosity, and the viscosity of said dispersion liquid slurry is lowered by heating said dispersion liquid in succession in the process from the transfer of said dispersion liquid lading to said forming step up to said removing step, whereby the dispersion of said dispersion liquid in the form of slurry is stabilized and the forming and removal of solvent are carried out with ease.

15. The method of claim 14, wherein the temperature of said dispersion liquid is kept low while dispersed and stored so as to remain stably dispersed with a high viscosity, and wherein the viscosity is lowered by heating or adding an amount of water in the process leading to the removing step whereby the forming and the removing are carried out with ease.

16. The method of claim 14, wherein said dispersion medium is a mixture of a polyvalent alcohol and water, the ratio of the polyvalent alcohol to water being 9/1 to 5/5.

17. The method of claim 14, wherein the concentration of water to said polyvalent alcohol in said dispersion medium is increased in succession in said preparation step, said forming step and said removing step.

18. The method of any of claim 14, wherein said dispersion liquid contains a short-cut staple fiber component coexistent with said absorbent polymer particles to make a co-dispersion system.

19. The method of claim 18, wherein said short-cut staple fiber component is hydratable fine fibers in the form of microfibril finer than said absorbent polymer particles.

20. The method of claim 18, wherein said staple fiber component has a length longer than the average particle diameter of said absorbent polymer particles and is fibrous material of 10 mm or shorter in fiber length and 3 denier or less in diameter.

21. The method of claim 18, wherein said short-cut staple fiber component is a combination of hydratable fine fibers in the form of microfibril shorter and finer than the average particle diameter of said absorbent polymer particles and of fibrous material having a fiber length longer than the average particle diameter of said absorbent polymer particles and of 10 mm or shorter in length and 3 denier or less in diameter.

22. The method of claim 18, wherein said polyvalent alcohol is selected from a group consisting of ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, low molecular weight polyethylene glycol and glycerin.

23. The method of claim 18, wherein said dispersion liquid in the liquid feeding zone of said forming step is kept at a temperature of 30°

C. or higher and 20°

C. higher than the temperature in said storage step.

24. The method of claim 23, wherein heating in said liquid feeding zone is done by directly blowing saturated steam thereinto so that the solvent/water ratio is adjusted by the effect of heating of and water addition to said dispersion liquid in said liquid feeding zone.

25. The method of claim 14, wherein the formed sheet obtained in said forming step is transferred to a steam treatment apparatus where heating of said formed sheet and water displacement of said polyvalent alcohol are carried out whereby liquid removal is facilitated.

26. An apparatus of making an absorbent sheet comprising a plurality of nozzles for applying a dispersion liquid slurry containing absorbent polymer particles in a band pattern on one surface of a liquid pervious supporting sheet running continuously, and means having a mechanism for pulsating the flow of said dispersion liquid in the form of slurry for feeding said dispersion liquid to said nozzles.

28. The apparatus of claim 26, wherein a heat press means is provided for pressing said liquid pervious supporting sheet and said slurry under heat after said dispersion liquid slurry is applied.

27. An apparatus of making an absorbent sheet, comprising a plurality of nozzles having a plurality of discharge outlets for applying a dispersion liquid in the form of slurry containing absorbent polymer particles in a band pattern on one surface of a liquid pervious supporting sheets running continuously, and means for feeding said dispersion liquid to said nozzles.