Water-disintegratable fibrous sheet having layered structure and wiping sheet comprising the same

• US 6,187,141 B1
• Filed: 09/16/1998
• Issued: 02/13/2001
• Est. Priority Date: 09/24/1997
• Status: Expired due to Term

• Current Assignee: Unicharm Corporation
• Original Assignee: Unicharm Corporation
• Inventors: Yamada, Daisuke, Konishi, Takayoshi, Takeuchi, Naohito
• Primary Examiner(s): Silverman, Stanley S.
• Assistant Examiner(s): Halpern, Mark
• Application Number:
  US09/154,285
• Time in Patent Office: 881 Days
• Field of Search: 162/158, 162/168.1, 162/111, 162/112, 162/125, 162/127, 162/129, 162/130, 162/132, 162/133, 162/175, 162/176, 162/177, 162/178, 424/402, 428/74, 428/249, 428/490
• US Class Current: 162/127
• CPC Class Codes: A47K 10/16 Paper towels; Toilet paper; Holders therefor dispensers A47K10/32
• CPC Class Codes: B32B 2432/00 Cleaning articles, e.g. mops or wipes
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: D21H 11/04 Kraft or sulfate pulp
• CPC Class Codes: D21H 17/26 Ethers thereof
• CPC Class Codes: D21H 17/66 Salts, e.g. alums
• CPC Class Codes: D21H 27/38 at least one of the sheets having a fibrous composition differing from that of other sheets
• CPC Class Codes: Y10T 428/237 Noninterengaged fibered material encased [e.g., mat, batt, etc.]
• CPC Class Codes: Y10T 428/31819 Next to cellulosic
• CPC Class Codes: Y10T 442/2762 Coated or impregnated natural fiber fabric [e.g., cotton, wool, silk, linen, etc.]

Abstract

A water-disintegratable fibrous sheet having a layered structure comprising: (a) at least one first fiber web comprising pulp of conifer and pulp of hardwood; (b) at least one second fiber web comprising pulp of conifer, having a content of pulp of hardwood less than that in said first fiber web or containing no pulp of hardwood, said first and second fiber webs forming said layered structure; and (c) a water-insoluble or water-swellable binder being added to at least one of said first and second fiber webs. The fibrous sheet excellent in water-disintegratability and strength can be obtained.

Claims

1. A water-disintegratable wiping sheet used in a wet state comprising two water-disintegratable fibrous sheets, wherein

each of said water-disintegratable fiber sheets comprises:

a first fiber web comprising pulp of conifer and pulp of hardwood without a binder;

a second fiber web comprising pulp of conifer, said second fiber web containing no pulp of hardwood and said first fiber web and second fiber web forming a layered structure; and

a water-insoluble or water-swellable binder added to only said second fiber web;

said second fiber web has a higher wet strength than the first fiber web, and

said first fiber web is more water disintegratable than said second fiber web, and wherein

said two water-disintegratable fibrous sheets have a wet strength of 75 g/25 mm or higher and are partially bonded one on the other with a water-soluble adhesive so that said second fiber web faces outside of said wiping sheet.

2. A water-disintegratable wiping sheet as claimed in claim 1, wherein a content of said hardwood pulp in said fist fibrous web is 60% by weight or less to a total fiber content of said first fiber web.

3. The water-disintegratable wiping sheet as claimed in claim 2, wherein the content of said hardwood pulp in said first fiber web is 10 to 50% by weight.

4. The water-disintegratable wiping sheet as claimed in claim 3, wherein said binder is water-insoluble or water-swellable carboxymethyl cellulose, and said adhesive is water-soluble carboxymethyl cellulose.

5. The water-disintegratable wiping sheet as claimed in claim 4, wherein said water-insoluble or water-swellable carboxylmethyl cellulose as the binder has a degree of etherification of 0.3 to 0.6 and a pH of 5.0 or more.

6. The water-disintegratable wiping sheet as claimed in claim 5, wherein at least one of sodium carbonate and sodium hydrogen carbonate is added to said fibrous sheet.

7. The water-disintegratable wiping sheet as claimed in claim 6, wherein at least one metallic salt selected from the group consisting of salts of calcium, zinc and magnesium is added to said fibrous sheet.

8. The water-disintegratable wiping sheet as claimed in claim 7, wherein said fibrous sheet is impregnated with an organic solvent which is at least one compound selected from the group consisting of monohydric alcohol and polyhydric alcohol.