Paper making and fiber liberation – Processes and products – Multi-layer waterlaid webs or sheets
Reexamination Certificate
1998-09-16
2001-02-13
Silverman, Stanley S. (Department: 1731)
Paper making and fiber liberation
Processes and products
Multi-layer waterlaid webs or sheets
C162S129000, C162S112000, C162S130000, C162S132000, C162S141000, C162S142000, C162S158000, C162S149000, C162S164100, C162S168100, C162S113000, C424S402000, C428S074000, C428S208000, C428S490000
Reexamination Certificate
active
06187141
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a water-disintegratable fibrous sheet that can be easily dispersed by a water stream. More particularly, the invention relates to a water-disintegratable fibrous sheet excellent in water-disintegratability and strength, and a water-disintegratable wiping sheet comprising a plurality of the water-disintegratable fibrous sheets laminated with each other.
2. Description of the Prior Art
Fibrous sheets are used for cleansing human skin, e.g., skin around anus, or cleaning a toilet room. The fibrous sheet is preferably water-disintegratable to be thrown away and drained in a toilet as it is. If it is not excellent in water-disintegratability, it requires a long time to be dispersed in a septic tank, and brings danger of clogging drainpipes of a toilet, when being thrown away and drained in a toilet. However, in general, a packed fibrous sheet impregnated with a cleansing liquid or the like has to be strong enough to endure conducting wiping operations while being impregnated with a cleansing liquid, and at the same time, has to keep water-disintegratability in the event of being thrown away and drained in a toilet. Therefore, a water-disintegratable fibrous sheet that has good water-disintegratability and strength sufficient to use is demanded.
Unexamined Published Japanese Patent Application No. H1-168999 discloses an easily water-dispersible cleaning product containing water-insoluble carboxymethylated pulp in a salt form of calcium. Unexamined Published Japanese Patent Applications No. H9-132896 and No. H9-132897 each discloses a water-disintegratable sheet, in which sodium carbonate is added to water-insoluble or water-swellable carboxymethyl cellulose. However, when a large amount of the binder, i.e., water-insoluble or water-swellable carboxymethylated pulp, is used to enhance sheet strength, water-disintegratability of the sheet is deteriorated.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a fibrous sheet and a wiping sheet that have good water-disintegratability and strength sufficient to practical use.
The above and other objects of the present invention are accomplished by 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 the first fiber web or containing no pulp of hardwood, the first and second fiber webs forming the layered structure; and
(c) a water-insoluble or water-swellable binder being added to at least one of the first and second fiber webs.
In the water-disintegratable fibrous sheet of the invention, by laminating layers having different water-disintegratability and strength with each other to form a fibrous sheet, a water-disintegratable fibrous sheet excellent in water-disintegratability and strength can be obtained.
Furthermore, by laminating the water-disintegratable fibrous sheets of the present invention, a wiping sheet excellent in water-disintegratability and strength can be obtained.
REFERENCES:
patent: 4610761 (1986-09-01), Eklund et al.
patent: 5129988 (1992-07-01), Parrington, Jr.
patent: 5437766 (1995-08-01), Van Phan et al.
patent: 5487813 (1996-01-01), Vinson et al.
patent: 5635028 (1997-06-01), Vinson et al.
patent: 5851352 (1998-12-01), Vinson et al.
patent: 01168999 (1989-07-01), None
patent: 0372388 (1990-06-01), None
patent: 0496524 (1992-07-01), None
patent: 05311120 (1993-03-01), None
patent: 1-168999 (1989-07-01), None
patent: 9-132897 (1997-05-01), None
patent: 9-132896 (1997-05-01), None
patent: WO 92/13137 (1992-08-01), None
Konishi Takayoshi
Takeuchi Naohito
Yamada Daisuke
Halpern Mark
Koda & Androlia
Silverman Stanley S.
Uni-Charm Corporation
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