Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation is water absorbency-increasing or...
Reexamination Certificate
1999-07-09
2001-04-03
Copenheaver, Blaine (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation is water absorbency-increasing or...
C442S301000, C442S414000, C428S378000
Reexamination Certificate
active
06211101
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a durable hydrophilic fiber. More specifically, this invention relates to a durable hydrophilic fiber and a fabric obtainable by using the fiber, useful mainly as a surface layer or a second sheet of the hygienic materials such as disposable diaper or sanitary napkin, as a shape preserver for water absorbing products, or further as industrial and medical wiping cloths.
2. Description of the Related Art
Hygienic articles such as a disposable diaper are formed of three layers of a surface material, an absorbing material and a backing material in the order from the side contacting directly to the skin. The surface material is required to possess good water permeability for rapid transmission of liquid to be absorbed to the absorbing material and also good dry touch which prevents absorbed liquid to flow back and provides skin dry feeling. It is preferable to be hydrophilic to improve water permeability. However, on the other hand, it is preferable to be hydrophobic to improve dry touch.
To achieve this paradoxical purpose, a non-woven fabrics made of polyolefin or polyester type fiber to which small amount of surface active agent is applied to afford desired hydrophilicity. (JP-A-63-6166; JP-A-63-49158)
However such surface materials using fiber to which surface active agent is applied have a drawback that, after once or twice liquid absorption, water permeability decreases rapidly caused by efflux of surface active agent resulting in unpleasant feeling due to remaining of liquid on the surface material.
Also known is a non-woven fabric made of durable hydrophilic fiber to which a surface active agent containing a water-soluble modified silicone is applied thus reducing the efflux of applied surface active agent and keeping hydrophilicity after repeated water transmission (JP-A-63-303184; JP-A-1-148879; JP-A-1-148880; JP-A-2-169774; JP-A-3-59169). However, such non-woven fabrics or knit/woven textiles consisting of durable hydrophilic fiber with these surface active agents, though showing comparatively good durable hydrophilicity, due to the water-soluble modified silicone contained as the necessary component, had a problem of poor strength of web or non-woven laminates caused by reduced friction between fibers. Further it was a problem that, in the stage of winding non-woven product, wound-up shape is unstable due to over flatness between non-woven webs.
According to JP-B-3-50030, it is proposed that hydrophilic polyolefin fiber can be achieved by applying the mixture of surface active agents such as alkylene oxide adduct to the compound having alkylolamide and active hydrogen or alkyl phosphate and so on. However this process cannot give enough durable hydrophilicity and anti-electrostaticity.
SUMMARY OF THE INVENTION
The object of this invention is to provide a durable hydrophilic fiber and a fabric using such fiber having durable hydrophilicity overcoming problems existing in the prior art above-mentioned, also having low slip between fibers not to reduce the strength of fibrous laminate such as non-woven fabrics.
The present inventors tried hard to solve above-mentioned problems and came to the conclusion that applying a mixture of specific surface active agents as the fiber finisher (fiber treating agent) can solve the problems and completed this invention.
To solve the above-mentioned problems, this invention features as the following:
1. A durable hydrophilic fiber comprising
a fiber consisting of a thermoplastic resin to which 0.2-1.5% by weight of fiber-treating agent based on the fiber is applied
wherein the fiber-treating agent contains at least 40% by weight of a mixture consisting of 20-80% by weight of the following component (A) and 80-20% by weight of the following component (B),
wherein component (A) is a betaine compound represented by formula (1)
R
1
R
2
R
3
—N
+
—CH
2
COO
−
(1)
(R
1
represents an alkyl group having 8-30 carbon atoms or such an alkyl group wherein its hydrogen atom is replaced by a hydroxyl- or a carboxyl-group; R
2
and R
3
each represents independently a hydrogen, an alkyl group having 1-5 carbon atoms or such an alkyl group wherein its hydrogen atom is replaced by a hydroxyl- or a carboxyl-group.),
and component (B) is an ester compound of
a dicarboxylic acid having 2-20 carbon atoms,
and an ester of hydroxy-fatty acid having 5-30 carbon atoms which 10 to 100 mol % (on the basis of the number of hydroxyl groups existing in the molecule of said hydroxy-fatty acid ester) of oxyalkylene units are added to its hydroxyl group.
2. The durable hydrophilic fiber according to the above clause 1, wherein the fiber-treating agent contains at least 80% by weight of mixture consisting of 20 to 50% by weight of said component (A), 20 to 50% by weight of said component (B) and, additionally 20 to 60% by weight of an anionic surface active agent (C).
3. The durable hydrophilic fiber according to the above clause 1 or 2, wherein said component (A) is an alkyl dimethylbetaine compound in which R
1
is an alkyl group having 8-20 carbon atoms, and R
2
and R
3
are both methyl group.
4. The durable hydrophilic fiber according to the above clause 1 or 2, wherein the “ester of hydroxy-fatty acid” having 5-30 carbon atoms which 10 to 100 mol % (on the basis of the number of hydroxyl groups existing in the molecule of said hydroxy-fatty acid ester) of polyoxyalkylene units are added to its hydroxyl group in the component (B) is a hardened castor oil polyoxyethylene adduct.
5. The durable hydrophilic fiber according to any of the above clause 1-4, wherein the component (B) is a maleic acid ester of a hardened castor oil polyoxyethylene addict.
6. The durable hydrophilic fiber according to any of the above clause 1-5, wherein at least one component of the thermoplastic resin is polyolefin resin.
7. The durable hydrophilic fiber according to any of the above clause 1-5, wherein at least one component of the thermoplastic resin is polyester resin.
8. A fabric made of the fiber described in any of the above clause 1-7.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The invention is described in detail as the following. As fibers usable in this invention, thermoplastic fibers from thermoplastic resins such as polyolefin resin, polyester resin or polyamide resin can be illustrated. Among them, hydrophobic polyolefin or polyester thermoplastic fibers are preferable for application to hygienic materials especially surface material or second sheet because of dry touch. Polyolefin resin include homopolymers of ethylene or propylene, or crystalline coplymers with other &agr;-olefin, or mixtures of these, &agr;-olefin coplymers include two or three monomers copolymer in which propylene is dominating. Examples of such copolymers are butene-1 or 4-methylpentene-1 with dominating propylene. Polyester resins are illustrated by polyethylene tereplithalate, polybutylene terephthalate, and copolyesters such as poly(ethyleneterephthalate-coethyleneisoplithalate), and copolyetherester. Depending application, a mixture of polyester resin, polyamide resin (Nylon 6, Nylon 66 etc.) or polyolefin resin can be successfully used under appropriate selection.
When the durable hydrophilic fibers of this invention are conjugate fibers consisting of two or more resins, several complex formations can be illustrated such as sheath-core, parallel, eccentric sheath-core, multi-layer, radial or island-sea formations.
Concerning the combination of resin in the conjugate fibers, polyolefin/polyolefin such as HDPE/PP, LLDPE/PP, LDPE/PP, “bipolymer” or “terpolymer” of propylene and other “&agr;-olefin(s)”/PP, LLDPE/HDPE, LDPE/HDPE and so on; or polyolefin/polyester such as PP/PET, HDPE/PET,LLDPE/PET,LDPE/PET and so on; or polyester/polyester such as copolyester/PET are illustrated. Further fibers from polyamide/polyester or polyolefin/polyamide can be illustrated. (As the codes used in the above description, HDPE means high density polyethylene, LLDPE means linear low density polyethylene, LDPE mean
Katsuya Masahito
Suzuki Masayasu
Tsutsui Toshihiko
Chisso Corporation
Copenheaver Blaine
McDermott & Will & Emery
Torres Norca L.
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