JP2006288604A - Sheet for skin care - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet for skin care which is flexible, excels in the touch (the feel of the skin), and has a high liquid absorptivity, and a wet sheet in which its sheet is impregnated with a liquid compound. <P>SOLUTION: In the sheet for the skin care which comprises a spunbonded fabric capable of being impregnated with the liquid compound, the spunbonded fabric has an average fineness of 0.5 or less dtex, is formed of a superfine long-fiber comprising a water insoluble thermoplastic resin, and contains a water-soluble thermoplastic resin in the spunbonded fabric at a rate of 0.001-10 weight%. The surface of the spunbonded fabric at 30% or more may be covered with the water-soluble thermoplastic resin. The water-soluble thermoplastic resin, for example, may be water-soluble thermoplastic polyvinylalcohol. The wet sheet, in which the sheet for the skin care is impregnated with the liquid compound, is suitable for a face mask, a makeup removing sheet, and a sheet for cleaning the body, etc. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a skin care sheet formed of a nonwoven fabric composed of ultrafine fibers and a wet sheet obtained by impregnating the sheet with a liquid compound (for example, a face mask, a makeup removing sheet, a sweat wipe sheet, an oil removing sheet, etc. Skin care products).

  Conventionally, fiber sheets composed of papers and fabrics have been used for impregnating liquid compounds such as cosmetics as skin care sheets such as face masks, makeup removing sheets, sweat wiping sheets and oil removing sheets. I came. Such a skin care sheet is required to be sufficiently impregnated with an aqueous or oily liquid compound, excellent in touch (skin feel) and adhesion to the skin, and free from fiber collapse even when used. The However, a fiber sheet that satisfies these characteristics in a well-balanced manner has not been developed. Therefore, various skin care sheets have been proposed to satisfy such requirements.

For example, Japanese Patent Application Laid-Open No. 2003-95861 (Patent Document 1) discloses a skin care composed of a spunlace nonwoven fabric having a convex portion having a cross-sectional height of 0.1 to 5 mm and a cross-sectional area of 0.01 to 200 mm ^2. A sheet has been proposed. In this document, the spunlace nonwoven fabric is composed of non-pulp fibers such as synthetic fibers and fibers combining synthetic fibers with rayon or cotton, and is composed of ultrafine fibers having a fineness of 0.01 to 5.5 dtex. Nonwoven fabric is described.

  However, this sheet has low liquid absorbency of liquid compounds such as cosmetics and emulsions, particularly hydrophilic liquid compounds. Furthermore, since the fineness of the ultrafine fibers is high, the touch and the adhesion to the skin are not sufficient.

  Japanese Patent Application Laid-Open No. 2003-93152 (Patent Document 2) is composed of an inner layer composed of a fiber assembly mainly composed of a hydrophobic component and an upper and lower outer layer composed of a fiber assembly composed mainly of a hydrophilic fiber. A sheet is described in which an assembly having a structure of at least three layers is impregnated with a cosmetic. In this document, as the hydrophilic fibers constituting the outer layer, ultrafine fibers (fiber diameter of 10 μm or less, preferably 5 μm or less, preferably composed of cellulose fibers having a hydrophilic functional group, alginic acid fibers, collagen fibers, etc. Preferably, 3 μm or less) is described.

However, since the outer layer of the sheet is composed of hydrophilic fibers, the liquid absorbency of the oily liquid compound is low. Furthermore, since this sheet has a three-layer structure, it is not easy or economical to manufacture.
JP 2003-95861 A (Claim 1, paragraph numbers [0004] [0005] [0016] [0028], Tables 1 and 2) JP2003-93152A (Claim 1, paragraph numbers [0011] [0012]).

  An object of the present invention is to provide a skin care sheet that is flexible and excellent in touch (skin feel) and has a high liquid absorbency, and a wet sheet in which a liquid compound is impregnated in the sheet.

  Another object of the present invention is to provide a skin care sheet having high adhesion to the skin and high liquid absorbency for both aqueous and oily liquid compounds, and a wet sheet obtained by impregnating the sheet with the liquid compound. There is to do.

  Still another object of the present invention is to provide a skin care sheet that has high mechanical strength even when the fiber diameter is small, and that can suppress the generation of fiber waste and floating due to use, and a wet sheet obtained by impregnating the sheet with a liquid compound. There is.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have formed a specific ultra-long fiber composed of a water-insoluble thermoplastic resin, and 0.001 to 10% by weight of a water-soluble thermoplastic resin. The present inventors have found that the non-woven fabric contained in a ratio is flexible and excellent in touch (skin feel) and has high liquid absorbency, thereby completing the present invention.

That is, the skin care sheet of the present invention is a sheet made of a nonwoven fabric that can be impregnated with a liquid compound, and the nonwoven fabric has an average fineness of 0.5 dtex or less and is made of a water-insoluble thermoplastic resin. It is formed of long fibers and contains a water-soluble thermoplastic resin in a proportion of 0.001 to 10% by weight in the nonwoven fabric. 30% or more of the surface of the nonwoven fabric may be coated with a water-soluble thermoplastic resin. The water-soluble thermoplastic resin is, for example, water-soluble thermoplastic polyvinyl alcohol, for example, at least selected from the group consisting of α-olefin units (particularly ethylene units) having 4 or less carbon atoms and C _1-4 alkyl-vinyl ether units. The modified polyvinyl alcohol etc. which contain 0.1-20 mol% (especially 3-20 mol%) of 1 type of units may be sufficient. The ratio of the water-soluble thermoplastic resin may be, for example, about 0.001 to 4% by weight in the nonwoven fabric. The water-insoluble thermoplastic resin may be a polyester resin, a polyamide resin, a polyolefin resin, a modified polyvinyl alcohol containing 25 to 70 mol% of ethylene units, and the like. Furthermore, the nonwoven fabric may be subjected to at least one process selected from the group consisting of hydroentanglement, hot embossing, and needle punching.

  The present invention also includes a wet sheet in which the skin care sheet is impregnated with a liquid compound. The wet sheet is suitable as a skin care product such as a face mask, a makeup removing sheet, and a body washing sheet (such as a sweat wiping sheet and an oil removing sheet).

  In this specification, the term “skin care” is not only meant as skin (skin) care with skin lotion or milky lotion (so-called skin care), but also as a broad concept that includes other actions that can be associated with the skin. Use. Accordingly, the skin care sheet includes, for example, a sheet used in contact with the skin, such as a sheet for cleaning the skin.

  In the present invention, since a non-woven fabric composed of ultrafine fibers containing a water-soluble thermoplastic resin in a proportion of 0.001 to 10% by weight is used, it is flexible and excellent in the touch (skin feel), and also has a liquid absorption property. high. In addition, it has high adhesion to the skin and high liquid absorbency with respect to both aqueous and oily liquid compounds. Furthermore, even if the fiber diameter is small, the mechanical strength is high, and the generation of fiber scraps and floating due to use can be suppressed. Therefore, such a nonwoven fabric is used as a skin care sheet, and wet sheets impregnated with a liquid compound are also used as face masks, makeup removing sheets, body washing sheets (sweat wipe sheets, oil removing sheets, etc.). Suitable for various skin care products.

  Hereinafter, the present invention will be described in detail.

[Skin care sheet]
The skin care sheet of the present invention is composed of a nonwoven fabric that can be impregnated with a liquid compound. Furthermore, the said nonwoven fabric is comprised with the ultra fine long fiber of the average fineness of 0.5 dtex or less.

(Ultra-thin fiber)
The ultrafine fibers in the present invention are composed of a water-insoluble thermoplastic resin. The water-insoluble thermoplastic resin is not particularly limited as long as it is not dissolved in a hydrophilic solvent (especially water) and can be melt-spun. For example, polyester resin [aromatic polyester (polyethylene terephthalate, polytrimethylene) Polyalkylene arylate resins such as terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate), aliphatic polyester (polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, hydroxybutyrate-hydroxyvalerate) Polymer, aliphatic polyester such as polycaprolactone or copolyester, etc.)], polyamide resin (nylon 6, nylon 66, nylon 610, nylon 10, nylon 12, nylon) Aliphatic polyamides or copolyamides such as -12), polyolefin resins (polypropylene, polyethylene, ethylene-propylene copolymers, olefin homo- or copolymers such as polybutene, polymethylpentene, etc.), hydrophobic monomers (especially , Ethylene) water-insoluble modified polyvinyl alcohol containing more than 20 mol% and not more than 70 mol%, thermoplastic elastomer (polystyrene, polydiene, polyolefin, polyester, polyurethane, polyamide, etc.), halogenated Examples thereof include vinyl resins (for example, vinyl chloride resins and fluorine-containing vinyl resins). These water-insoluble thermoplastic resins can be used alone or in combination of two or more.

Among these water-insoluble thermoplastic resins, polyester resins (especially poly C _2-4 alkylene arylates such as polyethylene terephthalate, poly poly (ethylene terephthalate)) are preferable because they can be combined with water-soluble thermoplastic resins (especially water-soluble thermoplastic PVA). Aliphatic polyesters such as lactic acid), polyamide resins (especially aliphatic polyamide resins such as nylon 6 and nylon 66), polyolefin resins (especially poly C _2-4 olefin resins such as polypropylene and polyethylene), And the modified polyvinyl alcohol which contains 25-70 mol% of ethylene units is preferable. In particular, a water-insoluble thermoplastic resin is a water-soluble thermoplastic resin from the viewpoint that a water-soluble thermoplastic resin (for example, water-soluble thermoplastic polyvinyl alcohol (PVA)) is likely to remain in a nonwoven fabric after extraction with a hydrophilic solvent. It may be a resin having a reactivity or affinity group. For example, in the case of water-soluble thermoplastic PVA, the water-insoluble thermoplastic resin may be a polyester resin, a polyamide resin, an olefin resin, a modified polyvinyl alcohol, or the like.

  Furthermore, the ultrafine fibers need to have an average fineness of 0.5 dtex or less, for example, 0.4 dtex or less (for example, 0.001 to 0.4 dtex), preferably 0.3 dtex or less (for example, 0.01 to 0.3 dtex), more preferably 0.25 dtex or less (for example, 0.05 to 0.25 dtex). When the average fineness of the ultrafine fibers is larger than 0.5 dtex, the ultrafineness is not sufficient, the fiber surface area is reduced, and the flexibility and liquid absorbency are remarkably reduced. Moreover, although there is no limitation in particular regarding a lower limit, 0.001 dtex or more is preferable at the point of the ease of production.

(Nonwoven fabric)
The nonwoven fabric of this invention is comprised with the said ultra-fine long fiber. Since such a nonwoven fabric is composed of long fibers, other nonwoven fabrics (for example, dry nonwoven fabrics obtained by needle-punching or water-entanglement of webs composed of short fibers, or shortcut fibers dispersed in water) Compared with wet nonwoven fabrics obtained by rolling up and drying, etc., the productivity is high, and fibers do not easily fall out of the nonwoven fabric. Furthermore, the strength of the nonwoven fabric is higher than that of the nonwoven fabric composed of short fibers and the nonwoven fabric composed of shortcut fibers.

  The nonwoven fabric of the present invention further contains a water-soluble thermoplastic resin in a proportion of 0.001 to 10% by weight in the nonwoven fabric. The proportion of the water-soluble thermoplastic resin present in the nonwoven fabric is preferably 0.001 to 4% by weight (for example, 0.01 to 4% by weight), more preferably 0.03 to 3.5% by weight in the nonwoven fabric. It may be about (especially 0.05 to 3% by weight). When the proportion of the water-soluble thermoplastic resin is more than 10% by weight, the elution of the water-soluble thermoplastic resin becomes high during use, and the flexibility of the nonwoven fabric decreases. On the other hand, when the proportion of the water-soluble thermoplastic resin is less than 0.001% by weight, the liquid absorbency (particularly water absorption) of the nonwoven fabric is lowered.

  In the present invention, it is preferable that 30% or more (for example, 30 to 100%) of the nonwoven fabric surface (including the surface layer of the nonwoven fabric and the fiber surface inside the nonwoven fabric) is coated with a water-soluble thermoplastic resin, more preferably. It is 35% or more (for example, 35 to 99%), more preferably 40% or more (for example, 40 to 90%). Such a coverage may be, for example, 45% or more (for example, 45 to 80%), preferably 50% or more (for example, 50 to 70%). If the coverage with the water-soluble thermoplastic resin is too low, the liquid absorbency (particularly water absorption) of the ultra-thin fiber non-woven fabric is lowered. The coverage with the water-soluble thermoplastic resin on the nonwoven fabric surface can be measured by X-ray photoelectron spectroscopy.

The water-soluble thermoplastic resin is not particularly limited as long as it can be dissolved and removed with a hydrophilic solvent (particularly water) at a temperature of 120 ° C. or lower as long as it is solid at room temperature and melt spinning is possible. Examples of such water-soluble thermoplastic resins include cellulose resins (C _1-3 alkyl cellulose ethers such as methyl cellulose, hydroxy C _1-3 alkyl cellulose ethers such as hydroxymethyl cellulose, and carboxy C _1-3 such as carboxymethyl cellulose. Alkyl cellulose ethers), polyalkylene glycols (poly _C2-4 alkylene oxides such as polyethylene oxide and polypropylene oxide), polyvinyl resins (polyvinyl pyrrolidone, polyvinyl ether, polyvinyl alcohol, polyvinyl acetal, etc.), acrylic copolymers And alkali metal salts thereof ((meth) acrylic acid, (meth) acrylic acid ester such as hydroxyethyl (meth) acrylic acid ester, (meth) acrylamide etc.) Copolymers containing units composed of acrylic monomers), vinyl copolymers or alkali metal salts thereof (vinyl monomers such as isobutylene, styrene, ethylene, vinyl ether, and maleic anhydride). Unsaturated carboxylic acids or copolymers thereof, etc.), resins having solubilizing substituents or alkali metal salts thereof (polyesters, polyamides, polystyrenes, etc. introduced with sulfonic acid groups, carboxyl groups, hydroxyl groups, etc.), etc. Can be mentioned. These water-soluble thermoplastic resins can be used alone or in combination of two or more.

  Among these water-soluble thermoplastic resins, polyvinyl alcohol resins such as polyvinyl alcohol (PVA) are excellent in water absorption and in melt spinning stability when melt-spun together with the water-insoluble thermoplastic resin. In particular, water-soluble thermoplastic PVA is preferable.

  PVA includes, in addition to homopolymers, for example, modified PVA into which a functional group has been introduced by copolymerization, terminal or side chain modification, and the like. Ordinary generally commercially available PVA cannot be melt-spun since its melting temperature and thermal decomposition temperature are close to each other (that is, not thermoplastic). is required.

  The water-soluble thermoplastic PVA has a viscosity average polymerization degree (hereinafter simply referred to as “polymerization degree”) of, for example, about 200 to 800, preferably about 230 to 600, and more preferably about 250 to 500. The PVA used for ordinary fibers generally has a degree of polymerization of 1500 or more (for example, a degree of polymerization of about 1700 or about 2100) because a higher strength fiber is obtained as the degree of polymerization is higher. In view of that, it can be said that the water-soluble thermoplastic PVA used in the present invention has an extremely low polymerization degree of 200 to 800. If the degree of polymerization is too small, sufficient spinnability cannot be obtained when spinning, and as a result, a satisfactory composite long fiber nonwoven fabric may not be obtained. On the other hand, if the degree of polymerization is too large, the melt viscosity is too high, and when spinning, the polymer cannot be discharged from the spinning nozzle, and a satisfactory composite long fiber nonwoven fabric may not be obtained.

  The degree of polymerization (P) of the water-soluble thermoplastic PVA is measured according to JIS-K6726. The degree of polymerization of the water-soluble thermoplastic PVA is obtained from the intrinsic viscosity [η] (dl / g) measured in water at 30 ° C. after completely re-saponifying and purifying the water-soluble thermoplastic PVA.

P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  The saponification degree of the water-soluble thermoplastic PVA used in the present invention is preferably in the range of 90 to 99.99 mol%, more preferably in the range of 92 to 99.9 mol%, particularly in the range of 94 to 99.8 mol%. preferable. If the degree of saponification is too low, the thermal stability of PVA may be poor and stable composite melt spinning may not be performed due to thermal decomposition or gelation. On the other hand, if the degree of saponification is too high, it is difficult to stably produce water-soluble thermoplastic PVA.

  The water-soluble thermoplastic PVA can be obtained by saponifying the vinyl ester unit of the vinyl ester polymer. Vinyl compound monomers for forming vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valenate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and Examples include vinyl versatate. These vinyl compound monomers can be used alone or in combination of two or more. Of these, lower aliphatic vinyl carboxylates such as vinyl acetate and vinyl propionate are preferred from the viewpoint of high productivity of water-soluble thermoplastic PVA, and vinyl acetate is usually used.

The water-soluble thermoplastic PVA may be a homopolymer or a modified PVA into which copolymer units are introduced. However, from the viewpoint of composite melt spinnability, water absorption, fiber properties, and nonwoven fabric properties, the copolymer units may be It is preferable to use the modified PVA introduced. Examples of the copolymerizable monomer in the modified PVA include α-olefins (α-C _2-10 olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene), (meth) acrylic, and the like. Acids and salts thereof, (meth) acrylic acid esters [(meth) acrylic such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate Acid C _1-6 alkyl ester etc.], (meth) acrylamide and derivatives thereof [N-C _1-6 alkyl (meth) such as (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide] Acrylamide etc.], vinyl ethers [methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i- B pills vinyl ether, and C _1-10 alkyl vinyl ethers such as n- butyl vinyl ether, hydroxyl group-containing vinyl ethers [ethylene glycol ether, 1,3-propanediol vinyl ether, 1,4 C _2-10 such as butane diol ether Alkanediol-monovinyl ether, etc.], allyl esters (eg, allyl acetate), allyl ethers [C _1-10 alkyl allyl ether, such as propyl allyl ether, butyl allyl ether, hexyl allyl ether, etc.] mer [polyoxyethylene group, a polyoxypropylene group, a vinyl monomer having a polyoxy C _2-6 alkylene group such as polyoxybutylene group, etc.], vinyl silanes (bi and vinyl trimethoxysilane Rutori like C _1-4 alkoxysilane), hydroxyl group-containing α- olefins or ester thereof [isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol , 7-octen-1-ol, 9-decen-1-ol, C _3-12 alkenols such as 3-methyl-3-buten-1-ol or esterified products thereof], N-vinylamides [N-vinyl Formamide, N-vinylacetamide, N-vinylpyrrolidone, etc.], unsaturated carboxylic acids [fumaric acid, maleic acid, itaconic acid, citraconic acid, maleic anhydride, itaconic anhydride, citraconic anhydride, etc.], having a sulfonic acid group Monomer [ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methyl Such Ropansuruhon acid], a monomer having a cationic group [vinyloxy-ethyl trimethyl ammonium chloride, Binirokishitetora C _1-10 alkyl ammonium chlorides, such as vinyloxy butyl trimethyl ammonium chloride, vinyloxy ethyl dimethylamine, vinyloxy methyldiethylamine, etc. Binirokishitori C _1-10 alkyl amine, N- acrylamide trimethyl ammonium chloride, N- acrylamide butyl trimethylammonium chloride such as N- acrylamide tetra C _1-10 alkylammonium chloride, N- acrylamide dimethylamine such as N- acrylamide di C _1-10 alkylamine, (meth) allyl trimethyl ammonium chloride (meth) Arirutori C _1-10 alkyl ammonium Niu Chloride, di C _1-3 alkylaryl amines, such as dimethyl allyl amine, allyl C _1-3 alkyl amines such as allyl ethyl amine] and the like. These monomers can be used alone or in combination of two or more. The content of these monomers is usually 20 mol% or less when the number of moles of all units constituting the modified PVA (or copolymer PVA) is 100%. Moreover, in order to exhibit the merit of being copolymerized, it is preferable that 0.01 mol% or more is the said copolymerization unit.

In the modified PVA, among these copolymerizable monomers, α-C _2-6 olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexene, methyl vinyl ether, C _1-6 alkyl vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether, C ₂ such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether and 1,4-butanediol vinyl ether _-6 alkanediol - vinyl, allyl esters represented by allyl acetate, propyl allyl ether, butyl allyl ether, C _1-6 alkyl allyl ether such as hexyl allyl ether, N- vinylformamide, N- Biniruaseto Bromide, N- vinylamides such as N- vinylpyrrolidone, a monomer having an oxy-C _2-4 alkylene group such as polyoxyethylene, 3-buten-1-ol, 4-penten-1-ol, 5-hexen C _3-10 alkenols such as -1-ol, 7-octen-1-ol, 9-decene-1-ol, and 3-methyl-3-buten-1-ol are preferable.

In particular, the copolymerizable monomers are ethylene, propylene, 1-butene, isobutene having 4 or less α-olefins, methyl vinyl ether, ethyl, from the viewpoint of copolymerizability, mixed melt spinnability and fiber properties. C _1-4 alkyl-vinyl ethers such as vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, and n-butyl vinyl ether are more preferable. The content ratio of copolymerizable monomers (particularly units derived from α-olefins having 4 or less carbon atoms and C _1-4 alkyl-vinyl ethers) is, for example, 0.1 to 20 in the water-soluble thermoplastic PVA. It is about mol%, preferably about 0.5 to 18 mol%.

  Furthermore, the copolymerizable monomer is particularly preferably ethylene from the viewpoint of improving the fiber properties. When the copolymerizable monomer is ethylene, the content ratio of ethylene units may be, for example, about 3 to 20 mol%, preferably about 5 to 18 mol% in the water-soluble thermoplastic PVA. .

  Examples of the method for producing the water-soluble thermoplastic PVA used in the present invention include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, and an emulsion polymerization method. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is usually performed without a solvent or in a solvent such as alcohol is employed. For example, examples of alcohol used as a solvent in solution polymerization of water-soluble thermoplastic PVA include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Examples of the initiator used for the copolymerization include azo initiators such as α, α′-azobisisobutyronitrile and 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, Well-known initiators, such as peroxide type initiators, such as n-propyl peroxycarbonate, are mentioned. These initiators can be used alone or in combination of two or more. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of 0-200 degreeC is suitable.

  The content ratio of alkali metal ions in the water-soluble thermoplastic PVA used in the present invention is, for example, 0.00001 to 0.05 parts by weight, preferably 0, in terms of sodium ions with respect to 100 parts by weight of the water-soluble thermoplastic PVA. The amount is about 0.0001 to 0.03 parts by weight, more preferably about 0.0005 to 0.01 parts by weight. PVA having an alkali metal ion content of less than 0.00001 parts by weight is difficult to produce industrially. Moreover, when there is too much content of an alkali metal ion, the polymer decomposition | disassembly at the time of a composite melt spinning, gelatinization, and a thread breakage will be remarkably, and it may be unable to fiberize stably. Examples of the alkali metal ion include potassium ion and sodium ion.

  In the present invention, the method for incorporating a specific amount of alkali metal ions into the water-soluble thermoplastic PVA is not particularly limited.

  Examples of water-soluble thermoplastic PVA include a method of containing alkali metal ions in PVA, for example, a method of adding a compound containing alkali metal ions after polymerizing PVA, and a saponification of a vinyl ester polymer in a solvent. In this case, by using an alkaline substance containing alkali metal ions as a saponification catalyst, alkali metal ions are blended in the PVA, and the PVA obtained by saponification is washed with a washing solution, whereby the alkali metal contained in the PVA is obtained. Although the method of controlling ion content etc. are mentioned, the latter method is preferable. The content of alkali metal ions can be determined by atomic absorption method.

  Examples of the alkaline substance used as the saponification catalyst include potassium hydroxide and sodium hydroxide. The ratio (molar ratio) of the alkaline substance used for the saponification catalyst is, for example, 0.004 to 0.5 mol, preferably 0.005 to 0.05 mol, relative to 1 mol of vinyl acetate units in polyvinyl acetate. Degree. The method for adding the saponification catalyst is not particularly limited, and may be a method of adding all at the beginning of the saponification reaction, or a method of adding in the middle after adding the saponification reaction at the initial stage. .

  Examples of the saponification reaction solvent include alcohols such as methanol, esters such as methyl acetate, sulfoxides such as dimethyl sulfoxide, amides such as dimethylformamide, and the like. These solvents can be used alone or in combination of two or more. Among these solvents, alcohols such as methanol are preferable, and the water content is about 0.001 to 1% by weight (preferably 0.003 to 0.9% by weight, more preferably 0.005 to 0.8% by weight). Methanol controlled to be more preferable. Examples of the cleaning liquid include alcohols such as methanol, ketones such as acetone, esters such as methyl acetate and ethyl acetate, hydrocarbons such as hexane, and water. Of these, methanol, methyl acetate, water or a mixture thereof is preferred.

  The amount of the cleaning liquid can be appropriately selected so as to satisfy the content ratio of the alkali metal ions, but is usually about 300 to 10,000 parts by weight, preferably about 500 to 5000 parts by weight with respect to 100 parts by weight of the water-soluble thermoplastic PVA. . The washing temperature is, for example, about 5 to 80 ° C, preferably about 20 to 70 ° C. The washing time is, for example, about 20 minutes to 100 hours, preferably about 1 hour to 50 hours.

  In addition, a plasticizer can be added to the water-soluble thermoplastic PVA for the purpose of adjusting the melting point and the melt viscosity within a range that does not impair the object and effect of the present invention. As the plasticizer, conventionally known plasticizers can be used, and examples thereof include diglycerin, polyglycerin alkyl monocarboxylic acid esters, and compounds obtained by adding ethylene oxide and / or propylene oxide to glycols. Among these, a compound in which about 1 to 30 mol% of ethylene oxide is added to 1 mol of sorbitol is preferable.

  The nonwoven fabric of the present invention is formed of ultrafine fibers composed of the water-insoluble thermoplastic resin and contains the water-soluble thermoplastic resin in a specific ratio, thereby allowing a liquid compound, for example, an aqueous or oily liquid. Compounds can also be impregnated. In particular, since the ultrafine fiber nonwoven fabric of the present invention contains a part of the water-soluble thermoplastic resin in the nonwoven fabric (especially the surface thereof), it has high liquid absorbency, especially water retention. Specifically, the water retention rate of the nonwoven fabric is, for example, 300% or more (for example, about 300 to 2000%), preferably 500% or more, and more preferably 600% or more. If the water absorption is too low, a sufficient water absorption function cannot be achieved, and it is not suitable for applications requiring water absorption. Such liquid absorbency includes a water-soluble thermoplastic resin in a nonwoven fabric composed of ultrafine fibers of a specific thickness, and if necessary, it is dried under specific conditions and dried under specific conditions. It is achieved by things. Although there is no upper limit on the water retention rate, it is generally difficult to produce a nonwoven fabric having a water retention rate exceeding 2000%.

  In addition, the water retention rate of a nonwoven fabric is measured as follows. That is, after a 20 cm × 20 cm nonwoven fabric weighed (a) after being completely dried in advance was immersed in 500 ml of pure water at 20 ° C. for 5 minutes, one of the four corners of the nonwoven fabric was picked up with tweezers and pulled up onto the water. The total weight was precisely weighed (b) when the state was held for about 30 seconds, and the water retention rate obtained by the following formula was measured.

Water retention rate (%) = {(b−a) / a} × 100
(In the formula, a represents the weight of the absolutely dried nonwoven fabric, and b represents the total weight of the nonwoven fabric when held for about 30 seconds while being pulled up on water).

The tensile strength (B) (unit: N / 5 cm) in the machine direction and transverse direction of the nonwoven fabric of the present invention satisfies the relationship of B / A ≧ 0.25 with respect to the basis weight (A) (unit: g / m ² ). For example, B / A ≧ 0.3 (for example, 10 ≧ B / A ≧ 0.3), preferably B / A ≧ 0.4 (for example, 5 ≧ B / A ≧ 0.4) More preferably, B / A ≧ 0.5 (for example, 3 ≧ B / A ≧ 0.5). In the case of B / A <0.25, the strength of the nonwoven fabric is insufficient, and a sufficient function alone cannot be achieved.

On the other hand, the tensile strength (B) (unit: N / 5 cm) and the basis weight (A) (unit: g / m ² ) preferably satisfy the relationship of B / A ≦ 10. If B / A is too large, the flexibility of the nonwoven fabric may be reduced. The value of B / A can be changed depending on the average fineness, the spinning take-up speed, the thermocompression bonding / entanglement conditions, and specifically, the average fineness is increased, the spinning take-up speed is increased, The value of B / A can be increased by strengthening the crimping / entanglement conditions.

  The nonwoven fabric of the present invention is, as necessary, a stabilizer (a heat stabilizer such as a copper compound, an ultraviolet absorber, a light stabilizer, an antioxidant, etc.), fine particles, as long as the purpose and effect of the present invention are not impaired. It may contain additives such as colorants, antistatic agents, flame retardants, plasticizers, lubricants, crystallization rate retarders and the like. These additives can be used alone or in combination of two or more. These additives can be added during the polymerization reaction or in subsequent steps. In particular, when an organic stabilizer such as hindered phenol, a copper halide compound such as copper iodide, or an alkali metal halide compound such as potassium iodide is added as a heat stabilizer, the melt retention stability during fiberization can be improved. Since it improves, it is preferable.

  When the nonwoven fabric of the present invention is produced by the method described later (method for extracting and removing the water-soluble thermoplastic resin), fine particles, particularly inert fine particles such as inorganic fine particles, are converted into water-soluble thermoplastic resin before spinning or When added to a water-insoluble thermoplastic resin, spinnability and stretchability can be improved. The average particle diameter of the fine particles is, for example, about 0.01 to 5 μm, preferably about 0.02 to 3 μm, and more preferably about 0.02 to 1 μm. The type of fine particles is not particularly limited. For example, inorganic fine particles such as silicon-containing compounds (such as silica), metal oxides (such as titanium oxide), metal carbonates (such as calcium carbonate), and metal sulfates (such as barium sulfate) are used. Can be mentioned. These fine particles can be used alone or in combination of two or more. Among these fine particles, silicon oxide such as silica, particularly silica having an average particle diameter of about 0.02 to 1 μm is preferable.

[Method for producing nonwoven fabric]
The method for producing the nonwoven fabric of the present invention is not particularly limited, and a method for producing a nonwoven fabric by spinning ultrafine fibers composed of a water-insoluble thermoplastic resin and a water-soluble thermoplastic resin in the above-mentioned proportion, water-insoluble thermoplasticity It may be a method of adding the above-mentioned ratio of water-soluble thermoplastic resin to a non-woven fabric formed of ultrafine fibers composed of resin, but a composite composed of water-soluble thermoplastic resin and water-insoluble thermoplastic resin A method of producing by dissolving (extracting) the water-soluble thermoplastic resin with a hydrophilic solvent from a nonwoven fabric formed of long fibers is preferable.

  In such a production method for extracting and removing a water-soluble thermoplastic resin, a composite continuous fiber nonwoven fabric composed of a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin is a production method in which melt spinning and nonwoven fabric formation are directly connected (so-called The spunbonded nonwoven fabric can be efficiently manufactured by a manufacturing method).

  Examples of the method for producing a spunbond nonwoven fabric include the following methods. First, a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin are melted and kneaded in separate extruders, and then the melted polymer flows are guided to the spinning head, merged, the flow rate is measured, and the spinning nozzle Discharge from the hole. Next, after the discharged yarn is cooled by a cooling device, it is pulled and thinned by a high-speed air current so as to obtain a desired fineness using a suction device such as an air jet nozzle. After that, the nonwoven web is formed by depositing on the movable collection surface while opening the fiber. Finally, a composite continuous fiber non-woven fabric can be obtained by partially thermocompressing and winding the web.

  The cross-sectional shape (cross-sectional shape perpendicular to the fiber length direction) of the composite long fiber constituting the composite long-fiber non-woven fabric is not particularly limited, and is an irregular cross-section [for example, hollow, flat, elliptical, polygonal, 3-14 leaf shape, T-shape, H-shape, V-shape, dogbone (I-shape), etc.], but usually a round cross section. In the present invention, the inside of the cross section is a composite structure composed of a phase composed of a water-insoluble thermoplastic resin and a phase composed of a water-soluble thermoplastic resin in order to form ultrafine fibers. .

  Specifically, the composite long fiber has a structure in which a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin can be separated in the axial direction (length direction) of the composite long fiber, that is, the water-soluble thermoplastic resin has a shaft. It is necessary to have a structure that can be dissolved and removed continuously in the direction to obtain ultrafine fibers by the remaining water-insoluble thermoplastic resin. Therefore, the composite long fiber is composed of a water-soluble resin phase extending in the axial direction and a plurality of water-insoluble resin phases extending coaxially with the water-soluble resin phase. And a water-soluble thermoplastic resin for dividing the ultrafine fiber component into a plurality of components. As the composite cross-sectional structure of such a composite long fiber, in consideration of the splitting property and the uniformity of the long fiber after ultra-thinning, the cross-sectional structure of a mandarin orange or a fan-shaped structure (that is, a water-insoluble thermoplastic resin) A phase composed of water-soluble thermoplastic resin and a phase composed of water-soluble thermoplastic resin alternately arranged radially from the center of the cross section), a laminated structure (that is, composed of water-insoluble thermoplastic resin) Phase and a phase composed of water-soluble thermoplastic resin are alternately arranged in a strip shape), sea-island structure (that is, sea component composed of water-soluble thermoplastic resin, and water-insoluble thermoplasticity) A structure composed of island components made of resin is preferable. These structures may be combined.

  The ultrafine fiber forming component (that is, the water-insoluble thermoplastic resin component) constituting the composite long fiber is, for example, 2 to 800, preferably 3 to 500, more preferably 3 to 200, depending on the water-soluble thermoplastic resin. It is preferable to be divided to the extent. When the composite cross-sectional structure of the composite long fiber has, for example, a mandarin orange cross-section or fan-type structure, or a bonded type structure, the ultrafine fiber forming component constituting the composite long fiber is a water-soluble thermoplastic resin. In view of productivity, it is preferably divided into about 2 to 50 (preferably 2 to 20, more preferably 3 to 15). Further, when the composite cross-sectional structure is a sea-island type, the number of island components that are ultrafine fiber forming components is preferably in the range of 2 to 800 in terms of productivity, more preferably 5 to 500 (especially 10). ˜200). In particular, a composite long fiber having a cross-sectional structure or a fan-shaped or cross-sectional structure such as a mandarin orange or a bonded type, and having ultrafine fiber-forming components divided into 6 to 15 is a point of water absorption. Is particularly good.

  When high wipeability is required for use as a skin care application, it may be a cross-sectional type or a fan-shaped structure of mandarin oranges arranged radially, or a laminated structure arranged in a strip shape. Since an excellent touch and adhesion to the skin are required, a sea-island structure in which fine fibers are easily obtained is particularly preferable.

  The ratio (weight ratio) between the water-insoluble thermoplastic resin and the water-soluble thermoplastic resin in the composite long-fiber nonwoven fabric used in the present invention is appropriately set according to the purpose and is not particularly limited. However, the water-insoluble thermoplastic resin / water-soluble Thermoplastic resin can be selected from the range of about 5/95 to 90/10, for example, 10/90 to 85/15, preferably 20/80 to 85/15, more preferably 30/70 to 85/15 ( In particular, it is about 50/50 to 85/15).

  In the present invention, the fiberizing conditions of the composite long fibers constituting the composite long-fiber nonwoven fabric need to be appropriately set according to the combination of the polymers and the structure of the composite cross section, but mainly pay attention to the following points. It is desirable to determine the fiberizing conditions.

The spinneret temperature is, for example, Mp + 10 ° C. to Mp + 80 ° C., preferably Mp + 15 ° C. to Mp + 70 ° C., when the melting point of the polymer constituting the composite long fiber is Mp (° C.). Preferably, it is about Mp + 20 ° C. to Mp + 60 ° C. Shear rate at spinning (gamma), for example, 500～25000Sec ^-1, preferably 1000～20000Sec ^-1, more preferably 1500~10000sec about ^-1. The draft (V) in spinning is, for example, about 50 to 2000, preferably about 100 to 1500. Further, when viewed from the combination of polymers to be composite-spun, a combination of polymers having melt viscosities measured by the shear rate at the time of passing through the nozzle at the spinneret temperature, for example, at a melt spinnerette temperature, a shear rate of 1000 sec ^{− From} the viewpoint of spinning stability, it is preferable to perform composite spinning with a combination in which the difference in melt viscosity at ¹ is within 2000 poise (preferably within 1500 poise).

The melting point Tm of the polymer in the present invention is a peak temperature of a main endothermic peak observed by a differential scanning calorimeter (DSC: manufactured by Mettler, trade name “TA3000”, etc.). The shear rate (γ) is calculated as γ = 4Q / πr ³ where r (cm) is the nozzle radius and Q (cm ³ / sec) is the amount of polymer discharged per single hole. The draft (V) is calculated by V = A · πr ² / Q, where the take-up speed is A (cm / sec).

  In the production of composite fibers, if the spinneret temperature is too low, the melt viscosity of the polymer is too high, and the spinning and thinning properties due to high-speed airflow are inferior. If it is too high, the water-soluble thermoplastic resin tends to thermally decompose. Therefore, stable spinning cannot be performed. On the other hand, if the shear rate is too low, it is easy to break the yarn, and if it is too high, the back pressure of the nozzle becomes high and the spinnability is lowered. Furthermore, if the draft is too low, unevenness in fineness will increase and stable spinning will be difficult, and if the draft is too high, it will be easy to break the yarn.

  In the present invention, when the discharged yarn is drawn and thinned using a suction device such as an air jet nozzle, the yarn take-up speed is about 1000 to 6000 m / min (preferably 2000 to 5000 m / min). As described above, it is preferable that the pulverization is performed by high-speed airflow. The take-up conditions of the yarn by the suction device are appropriately selected depending on the melt viscosity of the molten polymer discharged from the spinning nozzle hole, the discharge speed, the spinning nozzle temperature, the cooling conditions, etc. If the take-up speed is too low, the cooling of the discharged yarn will be performed. Adhesion between adjacent yarns may occur due to delay in solidification, and the orientation / crystallization of the yarn does not progress, and the resulting composite nonwoven fabric is undesirably coarse and low in mechanical strength. On the other hand, if the take-up speed is too high, the discharge yarns cannot follow the stringing / thinning property, and the yarns are cut, making it impossible to produce a stable composite long fiber nonwoven fabric.

  Further, in order to stably produce the composite long-fiber nonwoven fabric, the distance between the spinning nozzle hole and the suction device such as an air jet nozzle is preferably about 30 to 200 cm (particularly 40 to 150 cm). Such spacing depends on the polymer used, the composition, and the spinning conditions described above, but if the spacing is too small, fusion between adjacent yarns may occur due to a delay in cooling and solidification of the discharged yarn, Further, the orientation and crystallization of the yarn does not proceed, and the resulting composite nonwoven fabric is coarse and has low mechanical strength. On the other hand, if the interval is too wide, the cooling and solidification of the discharged yarn proceeds too much, so that the warp / thinning property of the discharged yarn cannot follow and the yarn is cut, and a stable composite long fiber nonwoven fabric is produced. I can't.

The composite long fibers refined by a suction device such as an air jet nozzle are dispersed and collected so as to have a substantially uniform thickness on the surface of the collecting sheet to form a web. The distance between the suction device and the collection surface is, for example, about 30 to 200 cm, preferably about 40 to 150 cm, from the viewpoint of productivity and fiber physical properties of the obtained nonwoven fabric. The basis weight of the web is from the viewpoint of the productivity and post-processability of the nonwoven fabric, for example, from 5 to 500 g / m ² , preferably 10 to 400 g / m ² , more preferably 50 to 50- It is about 300 g / m ² . From the viewpoint of productivity, the thickness of the suction-thinned web-forming composite long fiber is, for example, about 0.2 to 8 dtex, preferably about 0.5 to 7 dtex, and more preferably about 1 to 6 dtex.

In the present invention, the water-insoluble thermoplastic resin can be made ultrafine by extracting and removing the water-soluble thermoplastic resin from the composite long-fiber nonwoven fabric with a hydrophilic solvent. Hydrophilic solvents include water, alcohols (methanol, ethanol, isopropanol, butanol, etc.), ketones (acetone, etc.), ethers (dioxane, tetrahydrofuran, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, butyl cellosolve, etc.) ), Carbitols (carbitol, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, etc.). These hydrophilic solvents can be used alone or in combination of two or more. Among these hydrophilic solvents, water, C _1-3 alcohols such as ethanol, ketones such as acetone, mixed solvents of water and other hydrophilic solvents, and the like are usually used.

  The method for extracting the water-soluble thermoplastic resin from the composite long-fiber nonwoven fabric with a hydrophilic solvent is not particularly limited, and is a conventional method, for example, a dyeing machine such as a circular, a beam, a zicker, or a Wiens, or a vibro washer or a relaxer. A method of using the hot water treatment facility, a method of injecting a high-pressure water flow, and the like can be appropriately selected. Among these methods, the method of injecting a high-pressure water stream is a very effective method in that the split ultrafine fibers are strongly entangled with each other, and further, the water absorption is further improved by capillary action. In many cases, it is difficult to reduce the adhesion amount of the water-soluble thermoplastic resin to the range specified in the present invention only by spraying the water. Therefore, it is preferable to use a method in which the nonwoven fabric is stirred in a hydrophilic solvent bath after the treatment with a high-pressure water stream so that the amount of the water-soluble thermoplastic resin adhered is within the range specified in the present invention. When water is used as the hydrophilic solvent, the extraction water may be neutral, or may be an aqueous alkaline solution, an acidic aqueous solution, or an aqueous solution to which a surfactant is added.

  In particular, in the present invention, in the extraction and removal of the water-soluble thermoplastic resin with a hydrophilic solvent, the removal treatment is performed so that a part of the water-soluble thermoplastic resin remains in the nonwoven fabric. For that purpose, the amount of hydrophilic solvent used for the removal treatment, the treatment method, the treatment time, the treatment temperature, etc. are appropriately selected in advance so that the liquid absorbency (water absorption) defined in the present invention is obtained. These conditions are preferably determined in advance.

  Specifically, as a method for extracting and removing the water-soluble thermoplastic resin with a hydrophilic solvent, a method in which the composite long fiber nonwoven fabric is stirred in a hydrophilic solvent bath to dissolve and remove the water-soluble thermoplastic resin is preferable. The ratio of the hydrophilic solvent is about 100 to 2000 times (weight basis), preferably about 200 to 1000 times, more preferably about 200 to 500 times that of the composite long fiber nonwoven fabric. If the amount of the hydrophilic solvent is too small, dissolution and removal of the water-soluble thermoplastic resin may be insufficient, and the intended ultra-thin fiber nonwoven fabric may not be obtained. Moreover, when there is too much quantity of a hydrophilic solvent, the division | segmentation property from a composite long fiber to a very fine long fiber may fall. In addition, when extraction removal is inadequate, the method of extracting and removing a water-soluble thermoplastic resin again using the fresh hydrophilic solvent which does not contain a water-soluble thermoplastic resin is used.

  The extraction treatment temperature may be appropriately adjusted according to the purpose and the type of the solvent. For example, when extraction is performed using hot water, the treatment is preferably performed at 40 to 120 ° C, and the treatment is performed at 60 to 110 ° C. It is more preferable to perform the extraction treatment at 80 to 100 ° C. If the treatment temperature is too low, the extractability of the water-soluble thermoplastic resin is not sufficient and the productivity is lowered. On the other hand, if the treatment temperature is too high, the dissolution time of the water-soluble thermoplastic resin becomes extremely short, and stable production at the target water-soluble thermoplastic resin ratio may be difficult. Once the water-soluble thermoplastic resin is completely extracted and removed from the nonwoven fabric, the water-soluble thermoplastic resin is then applied to the nonwoven fabric using a method such as applying a solution containing the water-soluble thermoplastic resin. Even when added, it is difficult to obtain excellent water absorption as defined in the present invention.

  The extraction processing time can also be adjusted as appropriate according to the purpose, equipment to be used, and processing temperature, but in the case of batch processing, considering production efficiency, stability, quality and performance of the resulting ultra-thin fiber nonwoven fabric, etc. Is preferably about 10 to 200 minutes (particularly 10 to 150 minutes), and in the case of continuous treatment, it is preferably 1 to 50 minutes (particularly 1 to 20 minutes).

  About extraction processing (especially extraction processing with water), it is 50 degrees C or less (for example, about 10-50 degreeC, normally near room temperature) in order to improve the splitting property and splitting property from a composite long fiber to an ultrafine fiber ), The temperature of the water is gradually increased, and the temperature is raised to a predetermined temperature (for example, about 80 to 120 ° C., preferably about 80 to 110 ° C.). In this temperature range, 5 minutes to 10 hours It is effective to use an operation for performing the extraction process (especially 10 minutes to 5 hours). Such treatment is particularly effective when the composite cross-sectional structure of the composite fiber is a mandarin orange cross-sectional or fan-shaped structure, a bonded structure, a sea-island structure, or the like.

  The rate of gradually increasing the temperature is preferably about 0.2 to 30 ° C./minute (particularly 1 to 20 ° C./minute). When the temperature is gradually raised under such conditions, the water-soluble thermoplastic resin component shrinks when dissolved, and as a result, the ultrafine fibers composed of the water-insoluble thermoplastic resin that is the remaining component have fine crimps. Thus, the splitting property of the ultrafine long fiber is improved, and the water absorption of the obtained ultrafine long fiber nonwoven fabric is further improved. A preferable shrinkage is about 0.1 to 10% (particularly 0.3 to 7%). The degree of fine crimp is, for example, a crimp rate of 1 to 50%, preferably 1 to 40%, and more preferably about 1 to 30%. In known long-fiber nonwoven fabrics, generally, melt-spun fibers are drawn and simply laminated on the collection surface, so the fibers constituting the nonwoven fabric do not have crimps. On the other hand, the fibers constituting the nonwoven fabric of the present invention have crimps due to the shrinkage of the water-soluble thermoplastic resin (particularly water-soluble thermoplastic PVA) during its production. Therefore, in skin care applications, it has an effect of adsorbing dirt and cosmetics.

  In addition to such a method, various methods such as a method of dividing by injection of a high-pressure water stream and a method of dividing by passing between pressure rolls can be applied as a method of improving the splitting property of the composite long fiber. This is performed in combination with a method for extracting and removing the water-soluble thermoplastic resin.

  In order to satisfy the water absorption specified in the present invention, the drying temperature after the extraction treatment of the water-soluble thermoplastic resin is, for example, 120 ° C. or less (for example, 30 to 120 ° C.), preferably 100 ° C. or less (for example, 40 ˜100 ° C.), more preferably about 90 ° C. or less (for example, 50 to 90 ° C.), and may be room temperature. If the drying temperature is too high, crystallization of the remaining water-soluble thermoplastic resin (especially water-soluble thermoplastic PVA) proceeds, so that the water content in the nonwoven fabric is lowered and the water absorption performance is lowered.

  The drying time can also be adjusted as appropriate according to the purpose, equipment to be used, and drying temperature, but considering the production efficiency, stability, quality and performance of the resulting ultra-thin fiber nonwoven fabric, etc., when performing batch processing Is about 24 hours (for example, 1 minute to 24 hours), and in the case of continuous processing, it is about 1 hour (for example, 1 minute to 1 hour).

  The nonwoven fabric from which most of the water-soluble thermoplastic resin has been removed is substantially formed from a bundle of ultrafine fibers that is a bundle of ultrafine fibers. As a result, the ultra-thin fiber nonwoven fabric of the present invention is a bundling body, so that it is less likely to generate fluff and has a predetermined amount of water-soluble heat compared to the case where conventional individual individual ultra-fine fibers are independent from each other. It becomes easy to leave the plastic resin. Therefore, the water absorption of the nonwoven fabric is improved, and the shape stability of the nonwoven fabric is also improved.

  In addition, it is also possible to solve the converging state by using an entanglement method such as water entanglement, and to make the ultrafine fibers exist independently from the converging body. Such a method is effective when it is desired to impart flexibility, and can be appropriately adjusted by changing the degree of entanglement.

  Furthermore, in the present invention, when the amount of the remaining water-soluble thermoplastic resin is large, for example, when the water-soluble thermoplastic resin is present in 1% by weight or more in the nonwoven fabric, the fibers constituting the nonwoven fabric remain. Since it is fixed by the water-soluble thermoplastic resin, it is preferable from the viewpoint of maintaining the form of the nonwoven fabric.

In the present invention, the basis weight of the nonwoven fabric is, for example, from 5 to 500 g / m ² , preferably from 10 to 400 g / m ² , more preferably from 30 to 300 g / m, from the viewpoint of productivity and processability of the obtained nonwoven fabric. ² (particularly about 40 to 300 g / m ² ), for example, about 50 to 300 g / m ² .

  Of the water-soluble thermoplastic resins used in the present invention, water-soluble thermoplastic PVA and the like have biodegradability and decompose into water and carbon dioxide when treated with activated sludge or buried in soil. Is done. The activated sludge method is preferable for the treatment of waste liquid (drainage) after dissolving PVA. When an aqueous solution in which PVA is dissolved is continuously treated with activated sludge, it is decomposed in 2 days to 1 month. Moreover, since PVA used for this invention has low combustion heat and the load with respect to an incinerator is small, you may incinerate PVA by drying the waste_water | drain which melt | dissolved PVA.

  In the present invention, the ultra-fine fiber nonwoven fabric (or ultra-fine fiber nonwoven fabric web) thus obtained is hydroentangled, partially hot-pressed (such as hot embossing), or mechanically compressed (such as needle punch). ) And the like can be applied. These processes may be processed alone or in combination of two or more. Among these, from the viewpoint of shape retention, hot-pressure fusion such as hydroentanglement and hot embossing is preferable, and in particular, hydroentanglement and hot embossing may be combined.

  In hydroentanglement, specifically, morphological stability as a non-woven fabric is obtained by entanglement of ultrafine fibers by injecting a high-pressure water stream onto the non-woven fabric using a high-pressure hydroentanglement machine. To improve. The pressure in hydroentanglement is, for example, about 0.1 to 300 MPa, preferably 1 to 100 MPa, and more preferably about 5 to 50 MPa. The passing speed of the hydroentanglement machine is, for example, 0.1 to 50 m / min, preferably 0.5 to 30 m / min, and more preferably about 1 to 10 m / min. Hydroentanglement may be performed at any stage, but when water-soluble thermoplastic resin is extracted with a hydrophilic solvent, it is usually performed before extraction.

  In the hot embossing, specifically, the long fibers are bonded to each other by partial hot pressure bonding through the obtained web between a heated metal roll (embossing roll) having an uneven pattern and a heated smooth roll. Combined to improve the morphological stability as a nonwoven fabric. The temperature of the heating roll, the pressure for hot pressing, the processing speed, the pattern of the embossing roll, etc. in the thermocompression bonding process can be appropriately selected according to the purpose. Moreover, there is no restriction | limiting in particular about in which stage thermocompression bonding is performed, It is possible to implement suitably as needed. For example, it may be before the water-soluble thermoplastic resin is extracted with a hydrophilic solvent, or may be after divided ultra-thinning by jetting a high-pressure water stream. The portion thermocompression-bonded with such an embossed pattern is 1 to 40% (preferably 5 to 30%, more preferably 10 to 25%) of the surface area of the nonwoven fabric from the viewpoints of form stability, flexibility and water absorption. Degree.

  In particular, in the present invention, when water-entangled after hot embossing, the properties of the nonwoven fabric such as flexibility can be improved and the shape retention can also be improved.

  Furthermore, the ultra-thin fiber non-woven fabric of the present invention may be subjected to post-processing treatment such as hydrophilization treatment by plasma discharge treatment or corona discharge treatment according to the purpose.

  In addition, the ultra-fine long-fiber nonwoven fabric obtained in the present invention is not only used alone, but also laminated with other nonwoven fabrics (long-fiber nonwoven fabrics, short-fiber nonwoven fabrics, etc.), woven fabrics (woven fabrics, knitted fabrics, etc.), etc. It can also be used as a laminate. By laminating with other nonwoven fabrics or woven fabrics, a practical function can be further imparted depending on the application. For example, a melt blown nonwoven fabric may be laminated on one side of the ultra-thin fiber nonwoven fabric of the present invention.

  The ultra-thin fiber non-woven fabric obtained in this way exhibits good liquid absorption performance (particularly water absorption performance), but various hydrophilic treatments may be performed as necessary for the purpose of further improving water absorption. Examples of the hydrophilic treatment method include sulfonation treatment, discharge treatment such as corona discharge and plasma discharge, graft polymerization treatment, and fluorine gas treatment.

  The nonwoven fabric thus obtained is used as a skin care sheet, and its thickness can be selected depending on the application, but can be selected from a range of about 10 μm to 5 mm, for example, 30 μm to 3 mm, preferably 50 μm. ˜2 mm, more preferably about 100 μm to 1 mm (particularly 200 to 500 μm).

[Skin care sheet]
The skin care sheet of the present invention is composed of the nonwoven fabric and has high flexibility and liquid absorption. In the present invention, the skin care sheet is not particularly limited as long as it is a sheet for use in contact with the skin and impregnated with a liquid compound, and various skin care sheets are applicable. The sheet for skin care of the present invention may be a sheet used by impregnating these liquid compounds at the time of use, or may be a sheet (so-called wet sheet) used by impregnating a liquid compound in advance.

In the present invention, the liquid compound includes not only a liquid substance such as a solvent or liquid oil, but also a solution or dispersion (such as a cosmetic or emulsion) containing an active ingredient in the liquid substance. The solvent may be a lipophilic solvent, but is preferably a hydrophilic solvent from the viewpoint of safety to the human body. Examples of the hydrophilic solvent include water, lower aliphatic alcohols (for example, C _1-6 alkyl alcohols such as ethanol and isopropanol), alkylene glycols (for example, ethylene glycol, diethylene glycol, propylene glycol, etc.) and the like. . These hydrophilic solvents can be used alone or in combination of two or more. Liquid oils include, for example, unsaturated higher fatty acids (eg, oleic acid, oleyl alcohol, etc.), animal and vegetable oils (eg, jojoba oil, olive oil, palm oil, camellia oil, macadamian nut oil, avocado oil, sorghum Oil, sesame oil, wheat germ oil, linseed oil, castor oil, squalane, etc.), mineral oil (eg, liquid paraffin, polybutene, silicone oil, etc.), synthetic oil (eg, synthetic ester oil, synthetic polyether oil, etc.), etc. Is mentioned. These liquid oils can be used alone or in combination of two or more.

  These liquid substances can be used alone or in combination of two or more. For example, liquid oil may be used in combination as an additive (oil) for a hydrophilic solvent such as water or ethanol. Of these liquid substances, water, lower alcohols or mixtures thereof are usually used, preferably water and / or ethanol (especially water). For example, when water and a lower alcohol (particularly ethanol) are used in combination, the ratio of the two is water / lower alcohol = 100/0 to 30/70, preferably 100/0 to 50/50, more preferably 100. It is about / 0 to 70/30, for example, about 99/1 to 80/20.

  As active ingredients, conventional additives such as humectants, emollients, UV protection agents, surfactants, astringents, enzymes, refreshing agents, bactericides or antibacterial agents, emollients (eg salicylic acid or Derivatives thereof, lactic acid, urea, etc.), antioxidants (eg, tocopherol or derivatives thereof, polyphenols such as anthocyanins), whitening agents (eg, ascorbic acid or derivatives thereof, cysteine, placenta extract, arbutin, kojic acid, lucinol) , Ellagic acid, chamomile extract, etc.), antiperspirants (eg, astringents such as aluminum compounds, zinc compounds, tannins), rough skin prevention agents (eg, glycyrrhizinate, vitamins, etc.), anti-inflammatory agents (eg, For example, allantoin, guaiazulene, glycyrrhizic acid or a salt thereof, glycyrrhetinic acid or Salts, ε-aminocaproic acid, tranexamic acid, ibuprofen, indomethacin, etc., blood circulation promoters (eg, peony, rosemary, clove), vitamins (eg, vitamin A, vitamin B, vitamin C, vitamin D, vitamins) E, vitamin K, etc.), amino acids (eg, tryptophan, cysteine, etc.), cell activators (eg, riboflavin, pyridoxine, nicotinic acid, pantothenic acid, α-tocopherol, or derivatives thereof, plant extracts such as yukinoshita extract, etc. ), Fragrances (eg, synthetic fragrances, essential oils, essential oil components), colorants (eg, lakes, pigments, dyes, etc.), inorganic salts (eg, sodium sulfate, sodium bicarbonate, potassium chloride, etc.), and the like. These additives can be used alone or in combination of two or more. Among these additives, for example, moisturizers, ultraviolet inhibitors, surfactants, astringents, refreshing agents, enzymes, bactericides or antibacterial agents are commonly used for skin care sheets.

  Examples of the humectant include alkylene glycols (for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butylene glycol, polyethylene glycol, polyalkylene glycol such as diethylene glycol monoethyl ester, and monoalkyl esters thereof) ), Polyhydric alcohols (eg, glycerin, pentaerythritol, etc.), organic acids (eg, lactic acid, sodium pyrrolidonecarboxylate, etc.), amino acids (eg, serine, glycine, threonine, alanine, etc.), sugars (eg, sorbitol) Sugar alcohols such as hyaluronic acid, sodium hyaluronate, sodium chondroitin sulfate, chondroitin heparin and other polysaccharides), proteins (eg , Vitronectin, fibronectin, keratin, elastin, etc. royal jelly), and the like. These humectants can be used alone or in combination of two or more. Of these humectants, alkylene glycols such as dipropylene glycol and 1,3-butylene glycol, polyhydric alcohols such as glycerin, and sugars such as sodium hyaluronate are preferable.

  Examples of emollients include higher fatty acids or fats and oils (for example, oleic acid, isostearic acid, oxystearic acid, oleyl alcohol, isopropyl stearate, octyl oxystearate, glyceryl oxystearate, decyl oleate, 12-stearoyl stearin). Octyldodecyl acid, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene hydrogenated castor oil, etc.), waxes (eg, lanolin, lanolin alcohol, lanolin oil, polyoxyethylene lanolin, polyoxyethylene propylene lanolin, polyoxy Ethylene beeswax etc.), sugars (eg polyoxyethylene methylglycoside, sesquistearic acid methylglycoside, sorbic monooleate) , Sorbitan monolaurate, polyoxyethylene dioleic acid methylglycoside, sesquistearic acid polyoxyethylene methylglycoside, etc.), ceramides, squalane, squalene, honey, emulsified oil components (eg triglyceride oil, squalane, ester oil) For example, an emulsion obtained by emulsifying an oil component such as monoglyceride with a nonionic emulsifier. These emollients can be used alone or in combination of two or more. Of these emollients, polyoxyethylene group-containing saccharides such as polyoxyethylene methylglycoside, fats and oils such as glyceryl oxystearate and polyoxyethylene hydrogenated castor oil, and waxes such as lanolin are preferable.

  Examples of the surfactant include an anionic surfactant [for example, alkyl sulfate (such as sodium lauryl sulfate), alkyl ether sulfate (such as sodium lauryl ether sulfate, triethanolamine lauryl ether sulfate), and acylmethyl taurate. , Acyl glutamate (such as sodium acyl glutamate), amide ether sulfate, glycerin fatty acid esters (such as glyceryl monostearate), polyoxyethylene glycerin fatty acid esters (such as polyoxyethylene glyceryl monostearate), sulfosuccinate (dioctyl) Sodium sulfosuccinate, disodium lauryl sulfosuccinate, disodium polyoxyethylene sulfosuccinate, etc.)], amphoteric surfactants [for example, alkyl acetate betaine, Betaine acetate, imidazolinium betaine (amine oxide type semipolar surfactant)], nonionic surfactants [eg fatty acid alkanolamide (lauric acid diethanolamide, coconut fatty acid diethanolamide, etc.), polyoxyethylene alkyl Ethers (polyoxyethylene octyldodecyl ether, etc.), polyoxyethylene-polyoxypropylene block copolymers, etc.], cationic surfactants (eg, alkyltrimethylammonium chloride, dialkyldimethylammonium chloride, etc.) and the like. . These surfactants can be used alone or in combination of two or more. Of these surfactants, anionic surfactants such as sodium lauryl sulfate, triethanolamine lauryl ether sulfate, and disodium lauryl polyoxyethylene sulfosuccinate are preferred.

  The ultraviolet ray preventing agent includes an ultraviolet ray absorbing agent and an ultraviolet ray protecting agent. Examples of UV inhibitors include benzophenone-based absorbers (for example, oxybenzone, oxybenzonesulfonic acid, sodium hydroxymethoxybenzophenone sulfonate, etc.), and cinnamic acid-based absorbers (for example, octyl methoxycinnamate, methyl diisopropylcinnamate) , Ethyl diisopropylcinnamate, isopropyl p-methoxycinnamate, di-p-methoxycinnamate mono-2-ethylhexanoate glyceryl, etc.), p-aminobenzoic acid-based absorbents (for example, aminobenzoic acid, p -Ethyl aminobenzoate, octyl p-aminobenzoate, octyl p-dimethylaminobenzoate, etc.), salicylic acid-based absorbents (for example, octyl salicylate), dibenzoylmethane-based absorbents (for example, 4-t-butyl- 4'-methoxybenzoylmethane, etc. , Urocanic acid or its esters, beta-isopropyl furanone, such as beta-carotene and the like. Examples of the ultraviolet protective agent include inorganic pigments that scatter ultraviolet rays, such as titanium oxide (titanium dioxide), zirconium oxide, zinc oxide, and iron oxide. These ultraviolet inhibitors can be used alone or in combination of two or more. Of these ultraviolet light inhibitors, benzophenone-based absorbers such as oxybenzone and inorganic pigments such as titanium oxide and zinc oxide are widely used.

  Examples of astringents include oxyacids or salts thereof (eg, citric acid, sodium citrate, lactic acid, tartaric acid, etc.), aluminum or zinc compounds (eg, aluminum chloride, alum, zinc sulfate, sulfophenoxo zinc, etc.) , Proanthocyanidins, tannic acid, plant extracts containing tannin (for example, extracts of hamamelis, birch extract, etc.), mussel extract, sorghum extract, horsetail extract and the like. These astringents can be used alone or in combination of two or more. Of these astringents, oxyacids such as citric acid, tannic acid and alum are preferred.

  Examples of the refreshing agent include menthol or a derivative thereof, camphor, thymol, peppermint oil, and the like. These refreshing agents can be used alone or in combination of two or more. Of these cooling agents, menthol is widely used.

  Examples of the enzymes include lipolytic enzymes (lipases) and proteolytic enzymes (proteases). These enzymes can be used alone or in combination of two or more. Of these enzymes, lipolytic enzymes are widely used.

  Examples of the disinfectant or antibacterial agent include quaternary ammonium salts (for example, benzalkonium chloride, distearylmethylammonium chloride, etc.), benzoic acids (for example, benzoic acid, sodium benzoate, p-hydroxybenzoate ester, etc.), Salicylic acids (for example, salicylic acid, sodium salicylate, etc.), trichlorocarbanilide, triclosan and the like can be mentioned. These fungicides or antibacterial agents can be used alone or in combination of two or more. Among these bactericides or antibacterial agents, benzoic acids such as sodium benzoate and salicylic acids such as salicylic acid are widely used.

  The proportion of these additives can be appropriately selected depending on the application. For example, the proportion of a liquid substance such as water or ethanol is usually 30 to 99% by weight, preferably 40 to 95% in the total liquid compound containing the additive. % By weight, more preferably about 50 to 90% by weight.

  Among the skin care sheets, a sheet used by impregnating the liquid compound at the time of use can be used, for example, as a sheet for impregnating skin lotion or emulsion and applying it to the skin. Further, it can be used as a sheet impregnated with the liquid substance in order to remove makeup or wipe off secretions such as sweat. As the lotion or emulsion, conventional lotions or emulsions can be used, and any of aqueous and oily agents may be used. The skin care sheet of the present invention has a high liquid absorbency with respect to both hydrophilic and lipophilic liquid compounds, but since it has a water-soluble thermoplastic resin on its surface, it is particularly hydrophilic. It is useful as a sheet for impregnating the liquid compound.

  On the other hand, specific examples of the wet sheet include a face mask (face pack), a makeup removing sheet, a body washing sheet (for example, a sweat wipe sheet, an oil removing sheet, and the like).

  The skin care sheet of the present invention is particularly suitable for a face mask or makeup removing sheet mainly composed of a hydrophilic component because it has a high liquid absorbency with respect to a hydrophilic liquid compound. Furthermore, since the adhesiveness with respect to skin is high, when using as a face mask, a sheet | seat can be closely_contact | adhered also to fine gaps, such as the base of a nose, and the active ingredient of a face mask can osmose | permeate skin. In addition, when used as a makeup removal sheet, the flexibility of the sheet allows the sheet to adhere to minute gaps on the face, and makeup (such as makeup cosmetics such as foundation, white powder, lipstick, and eye makeup) is effective. Can be removed. Furthermore, since the constituent fibers are extremely fine, irritation to the skin is extremely low. Specifically, the face mask (face pack) and the makeup removing sheet may be, for example, a sheet impregnated with a solution containing a moisturizing agent or an emollient in a hydrophilic solvent. As the hydrophilic solvent, for example, water or ethanol, particularly a mixed solvent of water and ethanol can be used. Examples of the humectant or emollient include dipropylene glycol, 1,3-butylene glycol, glycerin, sodium hyaluronate, polyoxymethyl glycoside, and the like. The total ratio of the humectant and the emollient is, for example, about 0.1 to 50% by weight, preferably 1 to 30% by weight, and more preferably about 5 to 20% by weight in the solution.

  The skin care sheet of the present invention is suitable for a body washing sheet because it has a large surface area and an excellent adsorptivity to dirt. Furthermore, since it is highly flexible and has high adhesion to the skin, for example, the sheet can be adhered to minute gaps in the body, so that it can be washed well. Specifically, the body washing sheet is, for example, an astringent (citric acid, etc.) enzyme (lipolytic enzyme, etc.), a cooling agent (menthol, etc.), a preservative (sodium benzoate, etc.) in a hydrophilic solvent. It may be a sheet impregnated with a solution containing the above. The hydrophilic solvent is usually water. The ratio of the astringent is, for example, about 0.01 to 10% by weight in the solution, preferably about 0.03 to 5% by weight, and more preferably about 0.05 to 3% by weight. The ratio of enzymes is 1-50 weight% in a solution, for example, Preferably it is 3-30 weight%, More preferably, it is about 5-20 weight%. The proportion of the preservative is, for example, about 0.01 to 10% by weight in the solution, preferably about 0.03 to 5% by weight, and more preferably about 0.05 to 3% by weight. The ratio of the refreshing agent is, for example, about 0.001 to 1% by weight in the solution, preferably about 0.005 to 0.5% by weight, and more preferably about 0.001 to 0.1% by weight.

  Since the skin care sheet of the present invention is soft and excellent in touch (skin feel) and has high liquid absorption, various skin care sheets such as face masks, makeup removing sheets, body washing sheets (sweat wipes sheets) , Oil removal sheet, etc.).

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. Details of the plasticizer and thermoplastic polymer (water-insoluble thermoplastic resin) used in the examples are shown below. Further, in the examples, each physical property value was measured as follows. In the examples, “parts” and “%” are based on weight unless otherwise specified.

[Plasticizer and thermoplastic polymer]
Plasticizer: Compound obtained by adding an average of 2 moles of ethylene oxide to 1 mole of sorbitol PET: Polyethylene terephthalate (intrinsic viscosity 0.7, melting point 255 ° C.)
Nylon: 6-nylon (intrinsic viscosity 2.6, melting point 222 ° C.)
PP: Polypropylene (melt index (MI) 35 with a temperature of 230 ° C. and a load of 21.18 N)
EVOH: ethylene-vinyl alcohol copolymer (MI35 having an ethylene content of 32 mol%, a temperature of 190 ° C., and a load of 21.18 N).

[Analysis method of PVA]
The analysis method of PVA followed JIS-K6726 unless otherwise specified. Incidentally, the modified amount, using a modified polyvinyl ester or modified PVA, 500MHz ¹ H-NMR (JEOL (JEOL) (KK), GX-500) was determined by measuring by the device. The content of alkali metal ions was determined by atomic absorption method.

[Melting point]
The melting point of PVA was raised to 250 ° C. at a heating rate of 10 ° C./min in a nitrogen atmosphere using a differential scanning calorimetry (DSC) apparatus (Mettler, TA3000), cooled to room temperature, and then raised again. The temperature at the peak top of the endothermic peak indicating the melting point of PVA when the temperature was raised to 250 ° C. at a rate of 10 ° C./min was examined.

[Spinning state]
The melt spinning state was visually observed and evaluated according to the following criteria.

◎: Extremely good ○: Good △: Somewhat difficult ×: Poor

[Nonwoven fabric state]
The obtained nonwoven fabric was visually observed and touched and evaluated according to the following criteria.

◎: Uniform and extremely good ○: Almost homogeneous and good △: Somewhat difficult ×: Poor

[Percentage of PVA in non-woven fabric]
A 30 cm × 30 cm nonwoven fabric sample was immersed in 2000 ml of water in an autoclave and heat-treated at 120 ° C. for 1 hour. After the treatment, the nonwoven fabric was taken out from the hot water and lightly squeezed, and the same operation was performed by replacing the extract. The PVA in the nonwoven fabric was completely extracted and removed by a total of three repeated treatments. From the weight change before and after the treatment, the proportion of PVA in the nonwoven fabric was determined.

[Nonwoven fabric surface coverage with PVA]
The constituent elements and bonding state of the nonwoven fabric surface were analyzed by X-ray photoelectron spectroscopy (XPS), and the proportion of PVA occupying the nonwoven fabric surface was calculated from the results.

[Nonwoven fabric basis weight, thickness]
Measured according to JIS L1906 “General Long Fiber Nonwoven Fabric Test Method”.

[Average fiber diameter]
Using a scanning electron microscope (SEM), take a photograph of the surface of the nonwoven fabric magnified 500 times, draw two diagonal lines on this photograph, and calculate the value obtained by converting the thickness of the fiber that intersects this diagonal line into a magnification. Using. And the average value of 100 of these fibers was made into the average fiber diameter, the circle | round | yen which uses this fiber diameter as a diameter was calculated | required, and the fineness of the fiber was computed by making the circle | round | yen into a cross-sectional area.

[Water retention rate]
A 20 cm × 20 cm non-woven fabric weighed in advance after being absolutely dried is immersed in 500 ml of pure water at 20 ° C. for 5 minutes and then kept for about 30 seconds with the non-woven fabric pulled up on the water. The weight was precisely weighed to determine the water retention rate of the nonwoven fabric.

[Water absorption]
Measured according to JIS L1906 water absorption rate A method (drop method).

[Face mask evaluation]
A solution composed of 5% by weight of dipropylene glycol, 5% by weight of 1,3-butylene glycol, 5% by weight of glycerol, 0.2% by weight of sodium hyaluronate, 10% by weight of ethanol, and 74.8% by weight of purified water. The nonwoven fabric obtained in Examples and Comparative Examples was impregnated to prepare a face mask, and the following evaluation test was performed.

(1) Ease of spreading The ease of spreading the face mask was subjected to sensory evaluation in four stages according to the following criteria.

◎: Can be expanded very easily ○: Can be expanded easily △: Difficult to expand ×: Damaged

(2) Adhesion The sensory evaluation of the adhesion of the face mask to the face was performed in four stages according to the following criteria.

A: Extremely excellent adhesion ○: Excellent adhesion Δ: Low adhesion ×: No adhesion

(3) Touch The touch at the time of face mask poultice was subjected to sensory evaluation in four stages according to the following criteria.

◎: Soft ○: Slightly soft △: Slightly soft ×: Hard

(4) Difficulty in drying The feel of the face mask poultice was sensorially evaluated in four stages according to the following criteria.

◎: Very difficult to dry ○: Difficult to dry △: Slightly dry ×: Drys immediately.

[Evaluation of makeup removal]
A non-woven fabric obtained in Examples and Comparative Examples was impregnated with a solution composed of 10% by weight of 1,3-butylene glycol, 5% by weight of polyoxyethylene methylglycoside, 15% by weight of ethanol and 70% by weight of purified water. A makeup removal sheet was prepared and subjected to the following evaluation tests.

(1) Cosmetic removability A lipstick is uniformly applied on an acrylic plate (application amount 0.1 g), and a lipstick is removed in a state where a load of 300 g is applied on a test piece impregnated with a cleansing liquid cut to 5 cm × 5 cm. did. The weight of the acrylic plate after this operation was measured, and the removal rate was calculated according to the following formula.

Removal rate (%) = {(W1-W2) /0.1} × 100
(In the formula, the weight of the acrylic plate before removal is W1 (g), and the weight of the acrylic plate after removal is W2 (g)).

  The removal rate obtained was evaluated in four stages according to the following criteria.

◎: Removal rate of 90% or more ○: Removal rate of 70% or more and less than 90% Δ: Removal rate of 50 or more and less than 70% ×: Removal rate of less than 50%

(2) Feel at the time of wiping A test for removing the lipstick applied to the lips was conducted, and the feeling at the time of wiping was subjected to sensory evaluation in four stages according to the following criteria.

◎: Soft ○: Slightly soft △: Slightly soft ×: Hard

[Body washing sheet]
Sebum degradation component (8-acetylated sucrose modified 95 ° alcohol) 15 wt%, L-menthol 0.02 wt%, sodium benzoate 0.2 wt%, citric acid 0.1 wt%, and purified water 84. A non-woven fabric obtained in Examples and Comparative Examples was impregnated with a solution composed of 68% by weight to prepare a body washing sheet, and the following evaluation test was performed.

(1) Artificial sebum removal property A certain amount of artificial sebum (the following model sebum stain) is applied to the inner part of the forearm, and a body-washing sheet is placed on the application part, and the pressure is 100 gf / cm ² from the top of the sheet. The artificial sebum was removed by pressing for 2 seconds. The skin feel after washing was subjected to sensory evaluation in four stages according to the following criteria.

(Model sebum dirt)
As model sebum stain, cotton seed oil 47% by weight, myristic acid 24% by weight, squalane 9% by weight, cholesteryl palmitate 2% by weight, cholesterol 0.2% by weight, lauric acid 0.2% by weight, myristic acid 2.5% by weight A mixture of 6% by weight palmitic acid, 0.9% by weight stearic acid, 6.4% by weight oleic acid and 1.8% by weight trioleic acid was prepared. .

(Evaluation criteria)
◎: Not sticky at all ○: Not sticky △: Slightly sticky ×: Sticky

(2) Artificial sweat removal property A certain amount of artificial sweat (the following model sweat stain) is applied to the inner part of the forearm, and a body washing sheet is placed on the application part, and 100 gf / cm ² (9800 Pa) is applied from the top of the sheet. The artificial sweat was removed by pressing for 5 seconds with pressure. The skin feel after washing was subjected to sensory evaluation in four stages according to the following criteria.

(Model sweat dirt)
0.5 g of L-histidine hydrochloride monohydrate, 5 g of sodium chloride and 2.2 g of sodium dihydrogen phosphate dihydrate were dissolved in water, and 15 ml of a 0.1 mol / liter sodium hydroxide solution and Water was added to prepare an artificial sweat having a pH of 5.5.

(Evaluation criteria)
◎: Not sticky at all ○: Not sticky △: Slightly sticky ×: Sticky

(3) Touch at the time of wiping The touch when 10 reciprocations were performed on the inner side of the forearm using a body washing sheet was subjected to sensory evaluation in four stages according to the following criteria.

◎: Soft ○: Slightly soft △: Slightly soft ×: Hard

(4) Sheet strength The state of the sheet after 10 reciprocations using the body washing sheet on the inner side of the forearm was compared with the state before use, and was evaluated in four stages according to the following criteria.

A: No change at all O: Almost no change Δ: Slight fuzz is generated ×: Breakage occurs.

Example 1
[Production of ethylene-modified PVA]
A 100 L pressurized reaction vessel equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 29 kg of vinyl acetate and 31 kg of methanol, heated to 60 ° C., and then nitrogen was bubbled through the system for 30 minutes. Replaced. Next, ethylene was introduced so that the reactor pressure was 5.9 kg / cm ² (5.8 × 10 ⁵ Pa). Prepare a 2.8 g / L solution of 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol as an initiator, and perform nitrogen substitution by bubbling with nitrogen gas. did. After adjusting the polymerization tank internal temperature to 60 ° C., 170 ml of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 5.9 kg / cm ² (5.8 × 10 ⁵ Pa), the polymerization temperature at 60 ° C., and the above initiator solution at 610 ml / hour. Polymerization was carried out with continuous addition of AMV. After 10 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate.

  46.5 g (acetic acid in polyvinyl acetate) was added to 200 g of polyvinyl acetate methanol solution (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 50% by adding methanol to the obtained polyvinyl acetate solution. Saponification was performed by adding an alkaline solution (NaOH in 10% methanol) having a molar ratio (MR) of 0.1 to the vinyl unit. After about 2 minutes have passed since the alkali was added, the gelled product was pulverized with a pulverizer and allowed to stand at 60 ° C. for 1 hour to allow saponification to proceed. Then, 0.5% acetic acid water and methanol were mixed. 1000 g of mixed solution (acetic acid water / methanol = 20/80 (weight ratio)) was added to neutralize the remaining alkali. After confirming the end of neutralization using a phenolphthalein indicator, 2000 g of a mixed solution of water and methanol (water / methanol = 20/80 (weight ratio)) was added to the white solid PVA obtained by filtration. It was left and washed at room temperature for 3 hours. After repeating the above washing operation three times, 1000 g of methanol was further added and the mixture was left to wash at room temperature for 3 hours. Then, PVA obtained by centrifugal drainage was left in a dryer at 70 ° C. for 2 days to obtain dry PVA (PVA-1).

  The saponification degree of the obtained ethylene-modified PVA was 98.4 mol%. Further, after the modified PVA was incinerated, the content of sodium measured by an atomic absorption photometer using a material dissolved in an acid was 0.001 part with respect to 100 parts of the modified PVA. Subsequently, 20 g of absolutely dry PVA obtained by vacuum drying the modified PVA at 50 ° C. for 10 hours was subjected to methanol Soxhlet extraction using 100 mL of methanol for 3 days. The content of acetic acid measured by neutralization titration of 50 mL of the extract with 50 mL of distilled water and phenolphthalein and the acid in the extract with a 1/1000 N sodium hydroxide aqueous solution is based on 100 parts of modified PVA. The value α representing the ratio of acetic acid to sodium ion in PVA was 0.08.

  In addition, after removing the unreacted vinyl acetate monomer after the polymerization, a methanol solution of polyvinyl acetate obtained by precipitation in n-hexane and reprecipitation purification by dissolving with acetone was performed three times, followed by drying at 80 ° C. under reduced pressure for 3 days. To obtain purified polyvinyl acetate. When this purified polyvinyl acetate was dissolved in DMSO-d6 and measured at 80 ° C. using 500 MHz proton NMR (manufactured by JEOL Ltd., GX-500), the ethylene content was 10 mol%.

  The methanol solution of polyvinyl acetate was saponified at an alkali molar ratio of 0.5, and then the pulverized product was allowed to stand at 60 ° C. for 5 hours to proceed saponification, followed by methanol soxhlet for 3 days, and then at 80 ° C. And purified under reduced pressure for 3 days to obtain purified ethylene-modified PVA. It was 330 when the average degree of polymerization of this PVA was measured according to JIS K6726 of the usual method. Further, a 5% aqueous solution of the purified modified PVA was prepared to produce a cast film having a thickness of 10 microns. The film was dried under reduced pressure at 80 ° C. for 1 day, and then the melting point of PVA was measured by the above-described method using DSC (manufactured by METTLER, TA3000).

  The PVA obtained above was melt-extruded at a set temperature of 220 ° C. and a screw rotation speed of 100 rpm using a lab plast mill (manufactured by Toyo Seiki Co., Ltd., biaxial, 20 mmφ, L / D = 28). Manufactured. It shows in Table 1 about obtained PVA and its pellet.

Prepare the PVA (PVA-1) pellets obtained above and polyethylene terephthalate (PET) with an intrinsic viscosity of 0.7 and a melting point of 255 ° C., and then melt and knead each polymer by heating with a separate extruder. , Led to a sea-island type composite spinning pack of 280 ° C. so that the weight ratio of the composite long fibers constituting the nonwoven fabric is PET / PVA = 70/30, nozzle diameter 0.35 mmφ × 1008 holes, discharge amount 1050 g / min, The material was discharged from the spinneret at a shear rate of 2500 sec ⁻¹ . While the ejected spinning filament group is cooled with cooling air at 20 ° C, the ejected filament group is pulled and thinned at a take-up speed of 3000 m / min with high-speed air by an ejector located 80 cm from the nozzle, and the opened filament group is endless. A long fiber web was formed by collecting and depositing on a rotating collection conveyor device. In the spinning state, no breakage was observed, and the cross-sectional shape was extremely good. A cross-sectional view (cross-sectional view perpendicular to the length direction) of the obtained composite long fiber is shown in FIG. The cross-sectional structure of the fiber is a sea-island type consisting of phase 1 composed of water-soluble thermoplastic polyvinyl alcohol and phase 2 composed of thermoplastic polymer. The sea-island type composite fiber was guided so that the thermoplastic polymer was an island component and PVA was a sea component in the fiber cross section.

Subsequently, the web is passed between a concavo-convex pattern embossing roll heated to 60 ° C. and a flat roll under a linear pressure of 50 kgf / cm (490 N / cm), and the embossed portion is thermocompression bonded to thereby obtain a single fiber fineness. A sea-island type composite long-fiber nonwoven fabric having a basis weight of 83 g / m ² made of 3.5 dtex long fibers was obtained. The obtained non-woven fabric was homogeneous and very good.

About 50 m of the obtained composite long fiber nonwoven fabric, the composite long fiber is entangled by injecting a high-pressure water stream using a hydroentanglement machine (150 kgf / cm ² (14.7 MPa), nonwoven fabric passing speed 5 m / min). did. Subsequently, the PVA component was extracted using a circular dyeing machine (water bath 800 L, water bath ratio 350 times the weight of the nonwoven fabric, nonwoven fabric rotation speed about 50 m / min). After the composite long fiber nonwoven fabric was charged, the temperature was raised from room temperature to 95 ° C. at a rate of about 5 ° C./min, and further subjected to hot water treatment at 95 ° C. for 20 minutes. The PVA component in the composite long fiber nonwoven fabric was extracted and removed. The proportion of PVA in the nonwoven fabric after extraction and removal was 0.1%.

  Next, the web was dried with hot air at 80 ° C. for 3 minutes in a continuous process to obtain an ultra-thin fiber nonwoven fabric of polyethylene terephthalate. Table 2 shows the production conditions of the composite long fiber nonwoven fabric.

  Table 3 shows the PVA residual ratio, PVA coverage, fineness, basis weight, and various basic physical property evaluation results of the nonwoven fabric thus obtained.

  The obtained non-woven fabric was impregnated with different aqueous cleaning liquids for various uses to prepare wet sheets. Using this wet sheet, a face mask, makeup removal, and body cleaning performance were evaluated. The evaluation results are shown in Table 3.

  In any evaluation, good performance was shown.

Examples 2-9
Instead of the PVA used in Example 1, the PVA shown in Table 1 was used, the spinneret for composite spinning shown in Table 2 and the thermoplastic polymer were used, the spinning conditions shown in Table 2 were adopted, and the nozzle-ejector distance and After obtaining a nonwoven web composed of composite long fibers under the same conditions as in Example 1 except that the line net speed was adjusted, a composite long fiber nonwoven fabric was obtained by partial thermocompression bonding at the embossing treatment temperature shown in Table 2. . About the obtained composite long fiber nonwoven fabric, the PVA component was extracted using the circular dyeing machine similarly to Example 1, and the target ultrafine long fiber nonwoven fabric was obtained by drying with hot air at 80 degreeC for 3 minute (s). The weight ratio of the composite fiber component was adjusted by changing the amount of polymer introduced into the pack. Table 3 shows the PVA remaining rate, PVA coverage, fineness, basis weight, and various basic physical property evaluation results of the obtained nonwoven fabric. Table 3 also shows the evaluation results for various wet sheet performances.

In Example 2, the water entangling process was not performed, and in Example 4, the needle punching process was performed instead of the water entangling process. As needle punching conditions, a 1 barb needle was used, the needle depth was 8 mm, and the number of punches was 1000 punches / cm ² . Furthermore, a cross-sectional view (cross-sectional view perpendicular to the length direction) of the composite long fiber in Example 6 is shown in FIG. The cross-sectional structure of the fiber is a 16-segment type (mandarin orange type (1)) composed of phase 1 composed of water-soluble thermoplastic polyvinyl alcohol and phase 2 composed of a thermoplastic polymer.

Comparative Examples 1-3
A non-woven web composed of composite long fibers under exactly the same conditions as in Example 1 except that the water-insoluble thermoplastic resin and spinning conditions shown in Table 2 were applied and the nozzle-ejector distance and line net speed were adjusted as appropriate. After being obtained, it was partially thermocompression bonded at the embossing treatment temperature shown in Table 2 to obtain a composite long fiber nonwoven fabric. The weight ratio of the composite fiber component was adjusted by changing the amount of polymer introduced into the pack. The spinning state was good.

  About the obtained composite long fiber nonwoven fabric, the PVA component was extracted similarly to Example 1, and was dried, and the target ultrafine long fiber nonwoven fabric was obtained. The ratio of PVA in the nonwoven fabric was adjusted by appropriately changing the hot water temperature and the treatment time.

  Table 3 shows the evaluation results of the PVA residual ratio, coverage, fineness, basis weight, and various performances of the ultra-thin fiber nonwoven fabric.

  In addition, FIG. 3 shows a cross-sectional view (cross-sectional view perpendicular to the length direction) of the composite long fiber in Comparative Example 1. The cross-sectional structure of the fiber is an 8-split type (mandarin orange type (2)) composed of a phase 1 composed of a water-soluble thermoplastic polyvinyl alcohol and a phase 2 composed of a thermoplastic polymer.

  About the comparative example 1, the fineness of the long-fiber nonwoven fabric was large, as a result, the liquid absorbency of the nonwoven fabric fell and the characteristic of the wet sheet fell.

  In Comparative Example 2, the PVA was almost completely removed by the hot water treatment, so that the liquid absorbency of the nonwoven fabric was lowered and the properties of the wet sheet were lowered.

  In Comparative Example 3, the PVA remaining rate after the hot water treatment was increased, the flexibility was lowered, and the properties of the wet sheet were also lowered.

Comparative Example 4
Polyethylene terephthalate having an intrinsic viscosity of 0.7 and a melting point of 255 ° C. was prepared, heated and melt-kneaded in an extruder, led to a spinning pack at 280 ° C., nozzle diameter 0.35 mmφ × 1008 holes, discharge amount 620 g / min. The ejector is discharged from the spinneret at a shear rate of 3000 sec ⁻¹ , and the spinning filament group is cooled with a cooling air of 20 ° C., and the ejector at a distance of 80 cm from the nozzle is used with a high-speed air at a take-up speed of 4000 m / min. The filament group that had been pulled and thinned was collected and deposited on a collecting conveyor device that was rotating endlessly to form a long fiber web made of polyethylene terephthalate.

Subsequently, the web is passed between a concavo-convex pattern embossing roll heated to 180 ° C. and a flat roll under a linear pressure of 50 kgf / cm (490 N / cm), and the embossed part is thermocompression-bonded to obtain a single fiber fineness. A long-fiber nonwoven fabric having a basis weight of 54 g / m ² made of 1.56 dtex long fibers was obtained.

  Table 3 shows the evaluation results for the PVA residual rate, coverage, fineness, basis weight, and various performances of the obtained long fiber nonwoven fabric.

  With polyethylene terephthalate alone, the liquid absorbency was low and the properties of the wet sheet were also deteriorated.

Comparative Example 5
Polypropylene having a melt flow rate (MFR) of 400 g / 10 min was melt kneaded at 230 ° C. using a melt extruder, the molten polymer flow was guided to a melt blow die head, and measured with a gear pump, and a hole having a diameter of 0.3 mmΦ was 0 .Ejected from melt blown nozzles arranged in a row at a pitch of 75 mm, and simultaneously ejected hot air of 240 ° C. onto this resin to collect the discharged fibers on a molding conveyor to obtain a polypropylene-based ultrafine fiber nonwoven fabric with a basis weight of 50 g / m ² Obtained.

  Table 3 shows the evaluation results of the fineness, basis weight, and various performances of the obtained ultrafine fiber nonwoven fabric.

  The sheet strength was small, and the properties of the wet sheet were also deteriorated.

Reference example 1
Table 3 shows the evaluation results of the fineness, basis weight, and various performances of commercially available cotton (manufactured by Unitika Ltd., Cotton Ace).

  The sheet strength was small, and the properties of the wet sheet were also deteriorated.

FIG. 1 is a cross-sectional view showing an example of a cross-sectional structure of a composite long fiber used in the present invention. FIG. 2 is a cross-sectional view showing another example of the cross-sectional structure of the composite long fiber used in the present invention. FIG. 3 is a cross-sectional view showing another example of the cross-sectional structure of the composite long fiber used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Phase comprised with water-soluble thermoplastic polyvinyl alcohol 2 ... Phase comprised with thermoplastic resin

Claims (10)

  A sheet composed of a non-woven fabric that can be impregnated with a liquid compound, the non-woven fabric having an average fineness of 0.5 dtex or less, formed of ultrafine fibers composed of a water-insoluble thermoplastic resin, and water-soluble heat A skin care sheet comprising a plastic resin in a proportion of 0.001 to 10% by weight in the nonwoven fabric.   The skin care sheet according to claim 1, wherein 30% or more of the surface of the nonwoven fabric is coated with a water-soluble thermoplastic resin.   The skin care sheet according to claim 1, wherein the water-soluble thermoplastic resin is a water-soluble thermoplastic polyvinyl alcohol. The water-soluble thermoplastic polyvinyl alcohol is a modified polyvinyl alcohol containing 0.1 to 20 mol% of at least one unit selected from α-olefin units having 4 or less carbon atoms and C _1-4 alkyl-vinyl ether units. Item 4. A skin care sheet according to Item 3.   The skin care sheet according to claim 3, wherein the water-soluble thermoplastic polyvinyl alcohol is a modified polyvinyl alcohol containing 3 to 20 mol% of ethylene units.   The skin care sheet according to claim 1, wherein the proportion of the water-soluble thermoplastic resin is 0.001 to 4% by weight in the nonwoven fabric.   The water-insoluble thermoplastic resin is at least one selected from the group consisting of a polyester resin, a polyamide resin, a polyolefin resin, and a modified polyvinyl alcohol containing 25 to 70 mol% of ethylene units. Skin care sheet.   The skin care sheet according to claim 1, wherein the nonwoven fabric is a nonwoven fabric treated with at least one selected from hydroentanglement, heat embossing, and needle punching.   A wet sheet wherein the skin care sheet according to claim 1 is impregnated with a liquid compound.   The wet sheet according to claim 9, which is a skin care product selected from a face mask, a makeup removing sheet, and a body washing sheet.

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