JP2011089224A - Hydrophilic fiber, method for producing the same, and fiber aggregate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide fibers having more excellent durable hydrophilicity. <P>SOLUTION: In the hydrophilic fiber which is a fiber composed of a thermoplastic resin, at least the fiber surface is constituted of a thermoplastic resin containing 0.2-2.5 mass% of an ester compound expressed by formula (1): R<SP>1</SP>-COO-(-CH<SB>2</SB>-CHOH-CH<SB>2</SB>O-)<SB>n</SB>-H, and having a melting point of not higher than 30°C, and a polyether compound expressed by formula (2) R<SP>2</SP>-A-OH is attached to the fiber surface in an amount of 0.01-0.2 mass% based on the fiber mass. In the formula (1), R<SP>1</SP>is an 8-22C saturated or unsaturated aliphatic hydrocarbon group; and<SB>n</SB>is an integer of 2 to 10. In the formula (2), R<SP>2</SP>is a hydrogen atom, 1-60C aliphatic hydrocarbon group, or 1-60C aliphatic acyl group; and A is polyoxyalkylene group consisting of 5-300 oxyethylene units and/or oxypropylene units in total. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fiber having durable hydrophilicity, in which hydrophilicity is continuously exerted, and a fiber assembly using the same.

  As surface materials such as wipers, wet tissues, paper diapers and sanitary napkins, non-woven fabrics made of synthetic fibers are used, and in particular non-woven fabrics made of polyolefin fibers. This is because polyolefin fibers are excellent in mechanical properties and chemical resistance. One commonly used polyolefin fiber is a composite fiber composed of a low-melting polyolefin resin (particularly polyethylene) and a resin having a higher melting point than the polyolefin resin (for example, polypropylene or polyester). This composite fiber is used for utilizing a low melting point polyolefin-based resin as a thermal bonding component. Therefore, if this composite fiber is utilized, the nonwoven fabric which heat-bonded fibers is obtained, and such a nonwoven fabric is widely used in the said use.

  Synthetic fibers, particularly polyolefin-based fibers, are inferior in hydrophilicity and inherently hydrophobic compared to natural fibers such as cotton and rayon. Therefore, various methods have been proposed in order to improve the hydrophilicity. As a method for improving hydrophilicity, 1) a method in which a hydrophilizing agent is kneaded into a thermoplastic resin constituting the fiber surface, 2) a method in which a surfactant or other treating agent is attached to a fiber or non-woven fabric, and 3) corona Examples thereof include a method of introducing functional groups on the fiber surface by electric discharge, atmospheric pressure plasma treatment, treatment with ozone or ozone-added hydrogen peroxide, fluorine treatment, or sulfonation using concentrated sulfuric acid / anhydrous sulfuric acid gas.

  The method corresponding to the above 1) is proposed in, for example, Japanese Patent Application Laid-Open Nos. 2000-80522 and 2002-146630. The method corresponding to the above 2) is, for example, JP-A Nos. 2001-271272, 2003-201677, 2000-34672, 2004-250828, and 2003-239172. Proposed in the gazette.

JP 2000-80522 A JP 2002-146630 A JP 2001-271272 A JP 2003-201677 A JP 2000-34672 A JP 2004-250828 A JP 2003-239172 A

However, any fiber or non-woven fabric whose hydrophilicity has been improved by the method described in the above-mentioned patent document still has room for improvement in terms of hydrophilic durability (that is, durable hydrophilicity). In particular, when used as a top sheet of absorbent articles for humans and animals, further durable hydrophilicity is required.
This invention is made | formed in view of the said situation, and it aims at providing the fiber which has the more durable durable hydrophilic property.

  The present invention is a fiber composed of a thermoplastic resin, and is at least a thermoplastic resin containing 0.2 to 2.5 mass% of an ester compound represented by the following formula (1) and having a melting point of 30 ° C. or lower. The hydrophilic fiber which comprises the fiber surface and the polyether compound shown by following formula (2) adheres to the fiber surface with 0.01-0.2 mass% with respect to fiber mass is provided.

（式中、Ｒ^１は炭素数が８〜２２の飽和もしくは不飽和脂肪族炭化水素基であり、ｎは２〜１０の整数である。）

(In the formula, R ¹ is a saturated or unsaturated aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n is an integer of 2 to 10).

（式中、Ｒ^２は、水素原子、炭素数１〜６０の脂肪族炭化水素基または炭素数１〜６０の脂肪族アシル基であり、Ａは、合計５〜３００個のオキシエチレン単位および／またはオキシプロピレン単位で構成されたポリオキシアルキレン基である。）

(Wherein R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 60 carbon atoms or an aliphatic acyl group having 1 to 60 carbon atoms, and A is a total of 5 to 300 oxyethylene units and / or Or a polyoxyalkylene group composed of oxypropylene units.)

  In the hydrophilic fiber of the present invention, a thermoplastic resin containing 0.2 to 2.5 mass% of an ester compound represented by the above specific formula and having a melting point of 30 ° C. or lower constitutes at least the fiber surface. And a specific polyether compound is adhered to 0.01 to 0.2 mass% with respect to the fiber mass. Due to this feature, the hydrophilic fiber of the present invention is excellent in durability and hydrophilicity in which the hydrophilicity is continuously exhibited.

  In the method for producing hydrophilic fibers of the present invention, a thermoplastic resin containing 0.2 to 2.5 mass% of an ester compound represented by the above specific formula and having a melting point of 30 ° C. or lower constitutes at least the fiber surface. A treatment agent containing 5 to 50 mass% of the polyether compound represented by the formula (2) is attached to a fiber made of a thermoplastic resin in an amount of 0.1 to 0.6 mass% with respect to the fiber mass. Due to this feature, the hydrophilic fiber obtained by the method for producing a hydrophilic fiber of the present invention is excellent in durability and hydrophilicity in which the hydrophilicity is continuously exhibited.

  The present invention provides a fiber assembly containing 20 mass% or more of the hydrophilic fiber of the present invention. The fiber assembly of the present invention has durable hydrophilicity derived from the hydrophilic fiber of the present invention. The fiber assembly of the present invention is preferably provided in the form of a nonwoven fabric.

  The hydrophilic fiber of the present invention exhibits excellent durability hydrophilicity by using a thermoplastic resin containing a specific ester compound having a melting point of 30 ° C. or less, and exhibits good hydrophilicity even when liquid flow is repeated. Continue to demonstrate. Therefore, the hydrophilic fiber of the present invention includes a surface sheet of an absorbent article for humans and animals; various wiping sheets for humans, animals and objects such as wet tissues, wipers and disposable towels; and face masks. It is suitable for use as a material for a fiber assembly (particularly a nonwoven fabric) constituting a cosmetic-impregnated sheet and a cosmetic / medical patch.

  In the hydrophilic fiber of the present invention, a thermoplastic resin containing 0.2 to 2.5 mass% of an ester compound represented by the following formula (1) and having a melting point of 30 ° C. or lower constitutes at least the fiber surface. ing.

  In the present invention, an ester compound having a melting point of 30 ° C. or lower has a melting peak temperature (peak top temperature) measured by a differential scanning calorimetry (DSC) method measured using a differential scanning calorimeter of 30 ° C. or lower. This is an ester compound. The inventors have found that when such a ester compound is contained in the thermoplastic resin constituting the surface of the fiber, the durability hydrophilicity is greatly improved in combination with a treatment agent containing a specific polyether compound. I found it. As the reason, it is considered that when the ester compound represented by the formula (1) and having a melting point of 30 ° C. or less is added to the thermoplastic resin constituting the fiber, bleeding progresses appropriately on the fiber surface. Even in the case of the ester compound represented by formula (1), those having a high melting point, specifically those having a melting point higher than 30 ° C. are more hydrophilic than those having a melting point of 30 ° C. or lower. Inferior in that point. That is, the ester compound of the formula (1) having a melting point of 30 ° C. or less is moderately retained in the fiber after fiberization, and is moderately repelled from the resin and continuously exudes to the surface, thereby making it hydrophilic. It is thought that it will continue to demonstrate. The differential scanning calorimeter that can be used in the differential scanning calorimetry (DSC) method for measuring the melting point of the ester compound is not particularly limited, and a commercially available differential scanning calorimeter can be used. As an example of a differential scanning calorimeter that can be used, a differential scanning calorimeter (EXSTAR6000 / DSC6200) manufactured by Seiko Instruments Inc., or a differential scanning calorimeter (FP900 thermo system / FP90 control unit / FP84HT) manufactured by METTLER TOLEDO CO., LTD. ).

  In addition, when the melting point of the ester compound represented by the formula (1) is low, for example, 20 ° C. or lower, it is difficult to measure the melting peak temperature using a differential scanning calorimeter after making it solid. May be. Therefore, as a melting point measurement method instead of the DSC method, a method of observing whether the ester compound is liquid when solidified at 0 ° C. and then left in a constant temperature bath at 65% humidity and 20 ° C. for 1 hour is used. It's okay. In this method, when the compound after standing is a liquid, the compound may be regarded as having a melting point of 20 ° C. or lower.

  As far as the inventors have confirmed, the melting point of the ester compound of the formula (1) is not related to the hydrophilic / lipophilic balance (HLB) value. Therefore, even if it is an ester compound having an HLB value of less than 6, for example, and having a strong hydrophobicity such that a part thereof is dispersed in water, it can be used in the hydrophilic fiber of the present invention as long as the melting point is 30 ° C. or lower. it can.

The compound represented by the formula (1) is an ester compound of a saturated or unsaturated fatty acid and a polyglycerol having a polymerization degree of 2 to 10. Therefore, in Formula (1), R ¹ represents a saturated or unsaturated aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n represents the degree of polymerization of polyglycerol. When the carbon number of the saturated or unsaturated fatty acid is less than 8, it has volatility, and when the carbon number exceeds 22, it becomes difficult to obtain an ester compound having a melting point of 30 ° C. or lower. Examples of the saturated or unsaturated aliphatic hydrocarbon group include an alkyl group and an alkenyl group.

In the present invention, an ester compound represented by the formula (1) and having a melting point of 30 ° C. or lower is used. That is, even if R ¹ and n are within the above range, a compound having a melting point exceeding 30 ° C. is not used in the present invention. The ester compound represented by the formula (1) used in the present invention is preferably a melting peak temperature (peak top temperature) measured by a differential scanning calorimetry (DSC) method measured using a differential scanning calorimeter. ) Is an ester compound having a temperature of 25 ° C. or lower, more preferably a melting peak temperature (peak top temperature) measured by a differential scanning calorimetry (DSC) method measured using a differential scanning calorimeter is 20 ° C. or lower. It is an ester compound. The carbon number of R ¹ in the ester compound of the formula (1) is not particularly limited as long as the melting point of the ester compound of the formula (1) is 30 ° C. or less, but generally, as the carbon number of R ¹ increases, The melting point of the ester compound tends to be high. Therefore, when R ¹ is an unsaturated aliphatic hydrocarbon group, the carbon number thereof is preferably 8-18, more preferably 16-18, and particularly preferably 17. When R ¹ is a saturated aliphatic hydrocarbon group, the carbon number thereof is preferably 8-18, more preferably 16-18, and particularly preferably 17.

  Since the price of the ester compound tends to increase as the number of n in the ester compound of the formula (1) increases, the number of n is preferably smaller, and the number of n (degree of polymerization) is preferably 10 or less. Moreover, as long as it is ensured that melting | fusing point is 30 degrees C or less irrespective of the number of n, a difference does not arise in durable hydrophilicity. Therefore, n may be 2 to 4, 2 to 3, or 2.

As preferable examples of the ester compound of the formula (1), diglycerin monooleate (R ¹ is an unsaturated aliphatic hydrocarbon group having 17 carbon atoms, n = 2), tetraglycerin monooleate (R ¹ is carbon number) 17 unsaturated aliphatic hydrocarbon groups, n = 4), and decaglycerin monooleate (R ¹ is an unsaturated aliphatic hydrocarbon group having 17 carbon atoms, n = 10).

  The ester compound of the formula (1) is contained at least in the thermoplastic resin constituting the fiber surface. When the fiber is composed of a single component, the ester compound of the formula (1) is contained in the entire thermoplastic resin constituting the fiber. When the fiber is a composite fiber composed of a core component and a sheath component, the ester compound of the formula (1) is contained at least in the thermoplastic resin constituting the sheath component. In this case, the ester compound of the formula (1) may be contained in the thermoplastic resin constituting the core component. When it is also contained in the core component, bleeding of the ester compound is likely to occur in the fiber surface direction, and better durability hydrophilicity is exhibited. When the fiber has a structure in which two or more components are exposed on the fiber surface (for example, split type composite fiber, side-by-side type composite fiber), a thermoplastic resin that constitutes at least one of the components exposed on the fiber surface In addition, the ester compound of the formula (1) is contained.

  The content of the ester compound of formula (1) is such that when only one component (for example, the sheath component of the core-sheath type composite fiber) contains the ester compound, the thermoplastic compound constituting the one component Resin) (the total mass including the ester compound) is 0.2 to 2.5 mass%, a preferable content is 0.5 to 2.0 mass%, and a more preferable content is 0.6 to 1. mass%. 5 mass%. If the content is less than 0.2 mass%, the desired hydrophilicity cannot be sufficiently obtained, and if it exceeds 2.5 mass%, the spinnability may be lowered, and the fiber opening property may be reduced. May decrease.

  The thermoplastic resin is not particularly limited as long as it has fiber-forming properties. Specific examples of the thermoplastic resin include polyolefin resins such as polyethylene, polypropylene, polybutene, polybutylene, polymethylpentene resin and polybutadiene, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polylactic acid. Mention may be made of polyester resins such as butylene succinate, polycarbonate and copolymers thereof, polyamide resins such as nylon 66, nylon 12 and nylon 6, mixtures thereof, and elastomer resins thereof.

  When the fiber is a composite fiber having a core component and a sheath component (including those having an eccentric structure), the sheath component and the core component are adjusted so as to satisfy the melting point of the sheath component ≦ (melting point of the core component−10 ° C.). It is preferable to select a resin to constitute. By such a combination, it is possible to obtain a heat-adhesive conjugate fiber that can utilize the sheath component as a heat-adhesive component.

  Low melting point resin such as polyethylene (high density polyethylene, low density polyethylene, linear low density polyethylene), ethylene copolymer, propylene copolymer, and copolymer polyester as sheath component of core-sheath type synthetic fiber Can be used. Preferred combinations (core / sheath) of the core-sheath composite fiber include polypropylene / high density polyethylene, polypropylene / low density polyethylene, polypropylene / linear low density polyethylene, polyethylene terephthalate / high density polyethylene, polyethylene terephthalate / low density polyethylene, Examples thereof include polyethylene terephthalate / linear low density polyethylene, polypropylene / ethylene-propylene copolymer, and polyethylene terephthalate / ethylene-propylene copolymer. Since the present invention makes it possible to improve the durability and hydrophilicity by using a specific ester compound, the effect is effectively exhibited in a core-sheath type composite fiber having a hydrophobic resin as a sheath component. . In particular, when the sheath component is a polyolefin resin such as polyethylene, an ethylene copolymer, or a propylene copolymer, thermal processing is performed when a non-woven fabric is produced by bonding fibers using the sheath component as a thermal adhesive component. Is easy to implement.

  When the fiber of the present invention is obtained as a heat-bondable core-sheath type composite fiber, the composite ratio (volume ratio) of the core component / sheath component is 2/8 in consideration of fiber spinnability, adhesiveness, processability, and the like. It is preferably ˜8 / 2, and more preferably 3/7 to 7/3. When the composite ratio is less than 2/8, the fiber itself is not stiff and the card passing property is poor. When the composite ratio exceeds 8/2, the sheath component decreases, so that the thermal adhesiveness of the fiber tends to decrease.

  The fineness of the hydrophilic fiber of the present invention is preferably 0.3 to 20 dtex. For example, when used for a surface material of an absorbent article, the fineness is preferably 1 to 3 dtex, and when used for a wiper or wet tissue, the fineness is preferably 0.5 to 10 dtex. Further, when used for a cosmetic-impregnated sheet including a face mask and a base fabric for a cosmetic / medical patch, the fineness is preferably 0.3 to 5 dtex. When the fineness is less than 0.3 dtex, the fiber strength becomes weak, and problems may occur during the production of fibers or the production of nonwoven fabrics. When the fineness exceeds 20 dtex, the flexibility of the nonwoven fabric may be impaired when the nonwoven fabric is produced using this fiber.

  When the hydrophilic fiber of the present invention is provided as a short fiber or a staple fiber, the fiber length is not particularly limited, and may be 2 to 100 mm. The fiber length of the short fiber or staple fiber may be selected according to the form of the fiber aggregate containing the hydrophilic fiber of the present invention. For example, a spunlace nonwoven fabric, a needle punch using a fiber web produced by a card machine When manufacturing a nonwoven fabric or a thermal bond nonwoven fabric, fiber length becomes like this. Preferably it is 20-100 mm, More preferably, it is 35-75 mm. When manufacturing the air laid nonwoven fabric using the fiber web produced by the air lay method, the fiber length is preferably 2 to 20 mm. Alternatively, the hydrophilic fiber of the present invention may be provided as a continuous long fiber.

  In the hydrophilic fiber of the present invention, the polyether compound represented by the following formula (2) is attached to the fiber surface in an amount of 0.01 to 0.2 mass% with respect to the fiber mass. This treating agent, together with the ester compound of the formula (1), contributes to improving the durable hydrophilicity of the fiber.

（式中、Ｒ^２は、水素原子、炭素数１〜６０の脂肪族炭化水素基または炭素数１〜６０の脂肪族アシル基であり、Ａは、合計５〜３００個のオキシエチレン単位および／またはオキシプロピレン単位で構成されたポリオキシアルキレン基である。）

(Wherein R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 60 carbon atoms or an aliphatic acyl group having 1 to 60 carbon atoms, and A is a total of 5 to 300 oxyethylene units and / or Or a polyoxyalkylene group composed of oxypropylene units.)

In Formula (2), R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 60 carbon atoms, or an aliphatic acyl group having 1 to 60 carbon atoms. Examples of the aliphatic hydrocarbon group having 1 to 60 carbon atoms include the following.
1) Carbon number 1 to 1 such as methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, s-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, isohexyl group 6 alkyl groups,
2) C2-C6 alkenyl groups such as ethenyl group, propenyl group, isopropenyl group, 1-butenyl group, 2-butenyl group, isobutenyl group, t-butenyl group, pentenyl group, hexenyl group,
3) 1-isopropyl-1,2-dimethylpropyl group, heptyl group, octyl group, isooctyl group, 1-methylheptyl group, 5-methylheptyl group, 1-ethylhexyl group, 2-ethylhexyl group, 1-propylpentyl group 2-propylpentyl group, 1,1-dimethylhexyl group, 1,4-dimethylhexyl group, 1,5-dimethylhexyl group, 1-ethyl-1-methylpentyl group, 1-ethyl-4-methylpentyl group 1,1,4-trimethylpentyl group, 2,4,4-trimethylpentyl group, 2-ethyl-hexyl group, 2-propyl-heptyl group, nonyl group, 1-methyloctyl group, 6-methyloctyl group, 1-ethylheptyl group, 1- (n-butyl) pentyl group, 4-methyl-1- (n-propyl) pentyl group, 1,5,5-trimethyl Hexyl group, 1,1,5-trimethylhexyl group, decyl group, 1-methylnonyl group, 1-ethyloctyl group, 1- (n-butyl) hexyl group, 1,1-dimethyloctyl group, 3,7-dimethyl Octyl, undecyl, 1-methyldecyl, 1-ethylnonyl, dodecyl, 2-butyl-octyl, 1-methylundecyl, tridecyl, tetradecyl, 2-pentyl-nonyl, 1-methyltri Decyl group, pentadecyl group, hexadecyl group, 2-hexyl-decyl group, heptadecyl group, octadecyl group, 2-heptyl-undecyl group, nonadecyl group, icosyl group, henocosyl group, 2-octyl-tridecyl group, docosyl group, 2- Nonyl-tridecyl group, tricosyl group, 2-decyl-tetradecyl group, carbon such as tetracosyl group Alkyl group of from 7 to 25,
4) Heptenyl group, octenyl group, 3,7-dimethyl-6-octenyl group, 2,7-octadienyl group, 1,1-di (2-propenyl) ethyl group, nonenyl group, 2,6-nonadienyl group, decenyl Group, 3,7-dimethyl-2,6-octadienyl group, undecenyl group, 2,4-undecadienyl group, dodecenyl group, tetradecenyl group, 3,7,11-trimethyl-2,6,10-dodecatrienyl group, 1,5,9-trimethyl-1-vinyl-4,8-decadienyl group, 3,7,11,15-tetramethyl-2-hexadecenyl group, undecenyl group, octadecenyl group, 9c, 12c-octadecadienyl group 9c, 12c, 15c-octadecatrienyl group, icocenyl group, 5,8,11,14-icosatetraenyl group, dococenyl group, 3, , 11,15- tetramethyl -2,6,10,14- hex dodeca tetra-enyl group an alkenyl group having a carbon number of 7 to 25 such as,
5) C28-C60 alkyl groups such as octacosyl group, triacontyl group, dotriacontyl group, tetratriacontyl group, tetracontyl group, dotetracontyl group, hexatetracontyl group, pentacontyl group, hexacontyl group and the like.

Examples of the aliphatic acyl group having 1 to 60 carbon atoms include the following.
1) C 1-6 alkanoyl groups such as methanoyl group, ethanoyl group, propanoyl group, butanoyl group, pentanoyl group, hexanoyl group,
2) C 1-6 alkenoyl groups such as ethenoyl group, propenoyl group, isopropenoyl group, 1-butenoyl group, 2-butenoyl group, isobutenoyl group, t-butenoyl group, pentenoyl group, hexenoyl group,
3) Heptanoyl group, octanoyl group, nonanoyl group, decanoyl group, undecanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, pentadecanoyl group, hexadecanoyl group, heptadecanoyl group, octadecanoyl group, nonadecanoyl group, icosanoyl group An alkanoyl group having 7 to 25 carbon atoms such as a group, a heenicosanoyl group, a docosanoyl group, a tricosanoyl group and a tetracosanoyl group;
4) Heptenoyl group, octenoyl group, nonenoyl group, decenoyl group, undecenoyl group, dodecenoyl group, tridecenoyl group, tetradecenoyl group, pentadecenoyl group, hexadecenoyl group, heptadecenoyl group, octadecenoyl group, nondecenoyl group, icodecenoyl group, icodecenoyl group An alkenoyl group having 7 to 25 carbon atoms such as a tricosenoyl group and a tetracosenoyl group;
5) Octacosanoyl group, triacontanoyl group, dotriacontanoyl group, tetratriacontanoyl group, tetracontanoyl group, dotetracontanoyl group, hexatetracontanoyl group, pentacontanoyl group, hexacontanoyl group, etc. An alkanoyl group having 28 to 60 carbon atoms;

R ² is preferably an aliphatic hydrocarbon group or aliphatic acyl group having 28 to 60 carbon atoms, more preferably an aliphatic hydrocarbon group or aliphatic acyl group having 25 to 45 carbon atoms, It is still more preferable that it is a C25-45 alkyl group, and a C30-C40 alkyl group is especially preferable.

  In the formula (2), A is a polyoxyalkylene group composed of a total of 5 to 300 oxyethylene units and / or oxypropylene units. The polyoxyalkylene group is a homopolymerization system or copolymerization system of oxyethylene units and / or oxypropylene units. In the copolymerization system, the bonding mode may be a block type or a random type. Therefore, examples of A include residues obtained by removing all hydroxyl groups from polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polyethylene polypropylene glycol. In the formula (2), the polyoxyalkylene group represented by A is not particularly limited as long as it is composed of oxyethylene units and / or oxypropylene units, but the oxyalkylene units contain 50 mol% or more of oxyethylene units. More preferably, it contains 70 mol% or more, and particularly preferably contains 90 mol% or more of oxyethylene units. The number of repeating oxyalkylene units constituting the polyoxyalkylene group is preferably 5 to 100, more preferably 5 to 40, and particularly preferably 10 to 30.

  On the fiber surface of the hydrophilic fiber of the present invention, 0.01 to 0.2 mass% of the polyether compound of the formula (2) adheres to the fiber mass. If the adhesion amount of the polyether compound of the formula (2) is less than 0.01 mass% with respect to the mass of the fiber, the desired durable hydrophilicity cannot be obtained, that is, the thermoplastic resin constituting the fiber surface has the above formula. Even if the ester compound represented by (1) and having a melting point of 30 ° C. or less is contained in an amount of 0.2 to 2.5 mass%, the synergistic effect of the polyether compound and the ester compound is weak, and high durability hydrophilicity Is not demonstrated. When the adhesion amount of the polyether compound of the formula (2) is more than 0.2 mass% with respect to the fiber mass, the initial hydrophilicity (that is, the hydrophilicity when the liquid is first passed) of the obtained fiber and fiber aggregate is obtained. May be insufficient. The attached amount of the polyether compound of the formula (2) attached to the fiber surface of the hydrophilic fiber of the present invention is preferably 0.02 to 0.18 mass%, more preferably 0 to the fiber mass. 0.02 to 0.15 mass%, particularly preferably 0.03 to 0.12 mass%.

  A general component contained in the fiber treatment agent may adhere to the fiber surface of the hydrophilic fiber of the present invention as another component within a range in which the effect of the hydrophilic fiber of the present invention is not lost. In addition to the polyether compound of the formula (2), as other components that can adhere to the surface of the hydrophilic fiber of the present invention, polyglycerol fatty acid esters (including those represented by the formula (1)), known Examples include ionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants.

  The fatty acid ester of polyglycerin is obtained by esterifying a polyglycerin with a fatty acid and / or an ester-forming compound of a fatty acid. As polyglycerol, for example, those having a polymerization degree of 2 to 14 can be used. As the fatty acid, for example, an aliphatic monocarboxylic acid having 6 to 24 carbon atoms can be used, and as the fatty acid ester-forming compound, for example, an ester forming compound of an aliphatic monocarboxylic acid having 6 to 24 carbon atoms is used. be able to.

As nonionic surfactants, sugar ester type (also referred to as "polyhydric alcohol ester type") (e.g., sorbitan fatty acid ester (C _{12 to 18)),} fatty acid ester type (e.g., POE fatty acid esters (C _{12 to 18} )), Alcohol type (for example, POE alkyl ether), alkylphenol type (for example, POE alkyl ( _C8-12 ) phenyl ether), polyoxyethylene / polyoxypropylene block polymer type (for example, polyoxyethylene / polyoxypropylene block) Polymer), alkylamine type (for example, POE alkylamine (C _12-18 )), bisphenol type (POE fatty acid bisphenyl ether), polyaromatic ring type (POA benzylphenyl (or phenylphenyl) ether), silicone type, fluorine System and planting Oil type (e.g., POE castor oil, POE hydrogenated castor oil) is known.

Anionic surfactants include sulfate type (eg, alkyl sulfate), sulfonate type (eg, paraffin (alkane) sulfonate), carboxylic acid type (eg, fatty acid salt), and phosphate type (eg, POE alkyl (C _{12- 18} ) Phosphate, alkyl phosphate) are known. Cationic surfactants of the ammonium type (eg, alkyltrimethylammonium chloride (C _12-18 )) and benzalkonium type (eg, alkyldimethylbenzalkonium chloride (C _12-18 )) are known. Yes. As double-sided activators, betaine type (e.g. dialkyl ( _C8-12 ) diaminoethyl betaine, alkyl ( _C12-18 ) dimethylbenzyl betaine), and glycine type (e.g. dialkyl ( _C8-12 ) diaminoethylglycine, Alkyl ( _C12-18 ) dimethylbenzylglycine) is known.

In the fiber surface of the hydrophilic fiber of the present invention, as a component other than the polyether compound of the formula (2), for example, polyglycerin fatty acid ester, sugar ester, as long as the effect of the hydrophilic fiber of the present invention is not lost. Type ionic surfactant, sorbitan fatty acid ester, phosphate anionic surfactant, POE alkyl (C _12-18 ) phosphate or alkyl phosphate may be adhered, and the fiber of the hydrophilic fiber of the present invention On the surface, as a component other than the polyether compound of the formula (2), at least one phosphate selected from at least sorbitan fatty acid ester, alkyl phosphate and POE alkyl (C _12-18 ) phosphate (hereinafter referred to as at least 1). For convenience, the phosphate type surface activity Is preferably referred to as agent ") is attached. In this case, the attached amount of sorbitan fatty acid ester is 0.01 to 0.35 mass%, preferably 0.01 to 0.25 mass%, more preferably 0.02 to 0.25 mass%, and particularly preferably 0 to the fiber mass. 0.02 to 0.20 mass%, and the adhesion amount of the phosphate surfactant to the fiber surface is 0.03 to 0.35 mass%, preferably 0.04 to 0.30 mass%, more preferably, to the fiber mass. Is 0.05 to 0.25 mass%, particularly preferably 0.05 to 0.20 mass%.

In the sorbitan fatty acid ester, the fatty acid to be ester-bonded to sorbitan (sorbitol) is not particularly limited, and fatty acids such as stearic acid, oleic acid, lauric acid, myristic acid, palmitic acid are used, and sorbitan monoester which is an ester of sorbitan and stearic acid Stearate is preferably used. Further, the phosphate surfactant is preferably an alkali metal salt. As the phosphate interfacial agent, an alkyl phosphate having 5 to 15 carbon atoms and / or a POE alkyl (C _12-18 ) phosphate having 5 to 15 carbon atoms is preferably used.

  As a component other than the polyether compound of the formula (2), the effect of the hydrophilic fiber of the present invention is lost on the fiber surface of the hydrophilic fiber of the present invention in addition to or in place of the above component. In the absence, various functional agents suitable for applications in which the hydrophilic fiber of the present invention is used may be adhered. Specific examples of functional agents include fat-soluble antioxidants such as α-tocopherol, β-tocopherol, γ-tocopherol and δ-tocopherol, water-soluble antioxidants, aromatic functional agents, other deodorants, and antibacterial agents , Allergen deactivators, endothermic and exothermic agents, and far-infrared heat insulating agents.

  Of these various functional agents, fat-soluble antioxidants such as α-tocopherol, β-tocopherol, γ-tocopherol and δ-tocopherol, preferably a fat-soluble antioxidant containing α-tocopherol, are hydrophilic fibers of the present invention. If it adheres to the fiber surface of the skin, it can dilate the capillaries of the human body and promote blood circulation, and the roughening of the skin surface due to oxidation of lipids in the skin due to antioxidant action and suppression of lipid peroxide Can be prevented. Therefore, the hydrophilic fiber having a fat-soluble antioxidant substance attached to the fiber surface is a surface sheet of an absorbent article for humans; various wiping sheets for humans such as wet tissues and disposable towels; and a face mask. It is preferably used in applications such as cosmetic impregnated sheets and cosmetic / medical patches. When adhering to the fat-soluble antioxidant substance containing α-tocopherol on the fiber surface of the hydrophilic fiber of the present invention, 0.01 to 2.5 mass% of the fat-soluble antioxidant substance containing α-tocopherol with respect to the fiber mass, Preferably it is made to adhere to 0.03-1.0 mass%, more preferably 0.03-0.3 mass% fiber surface. When the adhesion amount is within this range, the above-described effects of promoting blood circulation and preventing rough skin are exhibited without losing the durable hydrophilic property of the hydrophilic fiber of the present invention.

  Next, the manufacturing method of the hydrophilic fiber of this invention is demonstrated. First, the thermoplastic compound which comprises the fiber surface is made to contain the ester compound of following formula (1). When obtaining the fiber of this invention as a single fiber, the ester compound of following formula (1) is contained in the thermoplastic resin which comprises a fiber. When the fiber of the present invention is obtained as a core-sheath composite fiber, at least a thermoplastic resin constituting the sheath component contains an ester compound of the following formula (1), and in some cases, a thermoplastic resin constituting the core component In addition, an ester compound of the following formula (1) is contained. When the fiber of the present invention is constituted as a split type composite fiber or side-by-side type composite fiber composed of two components, an ester compound of the following formula (1) is contained in one or both components.

  Including the ester compound of the formula (1) in the resin is a method of supplying the ester compound at a predetermined ratio to the extruder together with the constituent resin pellets at the time of melt spinning, and mixing using a known mixing apparatus. Examples thereof include a method of melt-mixing with a screw or twin screw extruder and making a master batch in advance. The latter method is preferably used because the ester compound is uniformly dispersed in the components.

  The resin containing the ester compound of the formula (1) is melt-spun using an appropriate spinning nozzle in a fiber form to be obtained using a known melt spinning machine. Next, the spun filament (undrawn yarn) is drawn as necessary. Stretching is performed in hot water, hot air, or a heat medium under conditions of a stretching temperature of 60 to 110 ° C. and a stretching ratio of 2.0 to 8.0. The stretching method is not particularly limited, and wet stretching is performed while heating in a high-temperature liquid such as warm water or hot water, dry stretching is performed while stretching in a high-temperature gas or a high-temperature metal roll, 100 ° C. A known stretching process such as steam stretching, in which stretching is performed while heating the fiber with the above steam at normal pressure or under pressure, can be performed. Among them, wet stretching using hot water is preferable because of excellent productivity and economy and easy and uniform heating of the whole unstretched fiber bundle.

  After drawing the filament, a treatment agent is attached to the filament. Specifically, a solution obtained by diluting the treatment agent with water or other solvent (hereinafter also referred to as “treatment liquid”) was attached to the surface of the obtained drawn filament, and then the filament was dried and attached. Water (or other solvent) is evaporated from the processing solution. By this operation, the treatment agent adheres to the dried filament. The method for attaching the treatment liquid to the fiber surface is not particularly limited, and for example, the treatment liquid can be attached by a known spray method, impregnation method, or roll touch method. The dried filament is cut into a predetermined length as necessary, and is provided as a short fiber or staple fiber having a fiber length of about 2 to 100 mm, or as a long fiber (continuous fiber).

  If necessary, the drawn filaments are crimped by a crimping device within a range of 12 to 16 crests / 25 mm of crimps and a crimp rate of about 8 to 15%. When applying crimp, it is preferable to attach the treatment liquid to the filament before crimping or simultaneously with crimping.

  The said processing agent used for the manufacturing method of the hydrophilic fiber of this invention contains 5-50 mass% of polyether compounds shown by following formula (2). In the method for producing hydrophilic fibers according to the present invention, this treatment agent, together with the ester compound of formula (1) contained in the thermoplastic resin constituting the fiber surface of the fiber, improves the durable hydrophilic property of the fiber. Contribute.

（式中、Ｒ^２は、水素原子、炭素数１〜６０の脂肪族炭化水素基または炭素数１〜６０の脂肪族アシル基であり、Ａは、合計５〜３００個のオキシエチレン単位および／またはオキシプロピレン単位で構成されたポリオキシアルキレン基である。）

(Wherein R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 60 carbon atoms or an aliphatic acyl group having 1 to 60 carbon atoms, and A is a total of 5 to 300 oxyethylene units and / or Or a polyoxyalkylene group composed of oxypropylene units.)

  The polyether compound of the formula (2) is contained in the treatment agent in an amount of 5 to 50 mass%, preferably 8 to 45 mass%, more preferably 10 to 40 mass%, and most preferably 15 to 40 mass%. ing. If the content of the polyether compound of the formula (2) is less than 5 mass%, it is not possible to obtain a fiber that exhibits the desired durability hydrophilicity. When the content of the polyether compound of formula (2) exceeds 50 mass%, the initial hydrophilicity (that is, the hydrophilicity when the liquid is first passed through) of the obtained fiber and fiber aggregate may be insufficient. Because there is.

  In the manufacturing method of the hydrophilic fiber of this invention, the said processing agent is made to adhere 0.1-0.6 mass% with respect to fiber mass. When the adhesion amount of the treatment agent is less than 0.1 mass%, good durable hydrophilicity may not be obtained, and when it exceeds 0.6 mass%, the fiber opening property may decrease, When manufacturing various fiber aggregates including the beginning, there is a risk of causing a decrease in productivity. In the method for producing a hydrophilic fiber of the present invention, the treatment agent is preferably attached to the surface of the fiber by 0.1 to 0.5 mass% with respect to the fiber mass, and more preferably 0.15 to 0 with respect to the fiber mass. .4 mass% is adhered, and particularly preferably 0.2 to 0.4 mass% is adhered to the fiber mass.

  In the method for producing a hydrophilic fiber of the present invention, the treatment agent is contained in the fiber treatment agent as a component other than the polyether compound of the formula (2) as long as the effect of the hydrophilic fiber of the present invention is not lost. Common ingredients may be included as other ingredients. Other components include polyglycerol fatty acid esters (including those represented by formula (1)), known nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants. Can be mentioned. The treating agent used in the method for producing hydrophilic fibers of the present invention is preferably a treating agent containing a sorbitan fatty acid ester and the phosphate surfactant as components other than the polyether compound of the formula (2). In that case, the total of the content of the sorbitan fatty acid ester in the treatment agent and the content of the phosphate surfactant is, for example, 40 to 95 mass%, and the content of the sorbitan fatty acid ester is 10 to 60 mass. %, The content of the phosphate surfactant is 30 to 60 mass%. In the said processing agent, the preferable content of sorbitan fatty acid ester is 10-50 mass%, and the preferable content of a phosphate type surfactant is 40-50 mass%. In the sorbitan fatty acid ester contained in the treatment agent used in the method for producing the hydrophilic fiber of the present invention, the fatty acid to be ester-bonded to sorbitan (sorbitol) is not particularly limited, and stearic acid, oleic acid, lauric acid, myristic acid Fatty acids such as palmitic acid are used. In the production method of the present invention, the treating agent preferably contains at least sorbitan monostearate, which is an ester of sorbitan and stearic acid, and more preferably contains only sorbitan monostearate as a sorbitan fatty acid ester. .

  In the method for producing the hydrophilic fiber of the present invention, the effect of the hydrophilic fiber of the present invention is lost as a component other than the polyether compound of the formula (2) in addition to or in place of the component. To the extent that it does not, it may include attaching various functional agents suitable for the application in which the hydrophilic fiber of the present invention is used to the filament surface. Fat-soluble antioxidants such as α-tocopherol, β-tocopherol, γ-tocopherol and δ-tocopherol, water-soluble antioxidants, aromatic functional agents, other deodorizing agents, antibacterial agents, etc. Examples include allergen inactive agents, endothermic agents, and far-infrared heat insulating agents.

  Among these various functional agents, a fat-soluble antioxidant substance containing various tocopherols such as α-tocopherol, β-tocopherol, γ-tocopherol and δ-tocopherol, preferably a fat-soluble antioxidant substance containing α-tocopherol When the obtained fiber product containing the hydrophilic fiber of the present invention is used, the capillaries of the human body are formed by the action of the fat-soluble antioxidant substance containing the various tocopherols attached to the fiber surface. It is possible to expand and promote blood circulation, and it is possible to promote prevention of roughening of the skin surface due to oxidation of lipids in the skin by antioxidant action and suppression of lipid peroxide. Therefore, the hydrophilic fiber obtained by the production method including attaching the fat-soluble antioxidant to the filament surface is a surface sheet of an absorbent article for humans; various wiping sheets for humans such as wet tissues and disposable towels; In addition, it is preferably used in applications such as a cosmetic-impregnated sheet such as a face mask and a cosmetic / medical patch.

  The method for attaching the various functional agents to the filament surface in the production stage is not particularly limited, as long as the functional agent can be uniformly adhered to the entire surface of the filament, a known spray method, impregnation method, or roll touch method. Can be used. When using these methods, the functional agent may be mixed with the treatment liquid and attached to the filament surface simultaneously with the polyether compound. Alternatively, after a solution diluted with a treatment agent containing 5 to 50 mass% of the polyether compound represented by the formula (2) is attached to the filament surface, it is passed through a crimper roll so as to have a moisture content described later. There is also a method in which the solution containing the functional agent is adhered to the filament surface by a spray method. According to this method, the functional agent can be efficiently and uniformly attached to the filament surface, and this method is more preferably used in the production method of the present invention.

  In the method for producing hydrophilic fibers of the present invention, the treatment liquid is preferably attached to the filament so that the moisture content measured as follows is 3 to 20%. This moisture content is measured with respect to the filament before drying, and when crimping is applied with a crimping apparatus, it is measured after drying after crimping, as described above. In the case where the functional agent is attached later, it is measured before the functional agent is attached. In any case, the moisture content of the filament to which the treatment liquid is adhered is determined by the operation of actively increasing or decreasing the adhesion amount of the treatment liquid in the manufacturing process (for example, crimp application by a crimp application device, treatment liquid between rolls). Squeezing, dehydration with a dehydrator, etc.) are no longer performed. When the moisture content of the filament before drying to which the treatment liquid is adhered is within the above range, a fiber having durable hydrophilicity can be easily obtained by adjusting the concentration of the treatment agent in the treatment liquid. When the moisture content of the filament before drying with the treatment liquid attached is less than 3%, there is little adhesion of the treatment agent, and the treatment agent may not adhere uniformly to the entire filament, and the resulting fiber has a durable hydrophilic property. May be insufficient. When the moisture content of the filament before drying to which the treatment liquid is attached exceeds 20%, a large amount of moisture is contained in the entire filament. As a result, the time required for drying becomes longer, resulting in a decrease in production efficiency, or the resulting fibers may not be sufficiently dried even after the drying step, resulting in inconvenient drying fibers. is there.

  The moisture content of the fiber is measured as follows. First, 2 m of the filament to which the treatment liquid before drying is attached is collected, and its mass (hereinafter referred to as mass before drying) is measured. The filament whose mass has been measured is dried at 110 ° C. for 15 minutes, and the moisture adhering to the filament is completely evaporated and dried. After the drying is completed, the mass (the mass after drying of the filament) is measured again. From the obtained mass before drying and mass after drying, the moisture content (%) in the filament before drying was determined by the following formula.

  In the manufacturing method of the hydrophilic fiber of this invention, it is more preferable that the moisture content shown by the said Formula (3) is 5 to 15%. It is particularly preferably 5 to 12%. Moreover, in the manufacturing method of the hydrophilic fiber of this invention, when the moisture content shown by the said Formula (3) is 3-20%, 5-50 mass% of polyether compounds shown by the said Formula (2) are contained. It is preferable that the density | concentration (namely, ratio of the processing agent contained in the solution which diluted the processing agent with water) of a processing liquid is 0.5-20 mass%, and it is more preferable that it is 1-15 mass%. By using a solution having such a concentration, a desired durable hydrophilic fiber can be efficiently produced.

  The hydrophilic fiber obtained by the above method is used after being processed into a known fiber aggregate, for example, a woven or knitted fabric, a net-like material, or a nonwoven fabric. The fiber assembly contains 20% by mass or more of the hydrophilic fiber of the present invention. If the content of the hydrophilic fiber of the present invention is less than 20 mass%, sufficient durability hydrophilicity cannot be obtained in the fiber assembly. The hydrophilic fiber of the present invention is particularly preferably used for producing a nonwoven fabric. The non-woven fabric is produced by making a fiber web and then bonding and / or entanglement of the fibers together. The form of the fiber web is not particularly limited, and may be any of parallel web made of staple fibers, semi-random web, and cross web, wet papermaking web made of short fibers, air laid web, and spunbond web made of long fibers. It's okay. When used for applications in which flexibility and texture are important, the nonwoven fabric is preferably produced using a web of staple fibers.

  In the production of the nonwoven fabric, the method for integrating the fibers of the fiber web is not particularly limited. For example, when the fiber of the present invention is a heat-adhesive core-sheath type composite fiber, or when the hydrophilic fiber of the present invention constitutes a nonwoven fabric together with a heat-adhesive fiber (single fiber or core-sheath type composite fiber) The fibers may be integrated by a thermal bond method such as a hot air spraying method or a hot embossing method. Alternatively, the fibers may be integrated by a mechanical entanglement method such as a needle punch method and a hydroentanglement method.

  When the hydrophilic fiber of the present invention is a heat-adhesive core-sheath type composite fiber, a nonwoven fabric is prepared using a fiber web containing 20 mass% or more of the fiber of the present invention, and after the thermal bonding, It is preferable that the fibers are thermally bonded by a sheath component. Specifically, it is preferable that the sheath component of the composite fiber is softened or melted to fix the fibers to each other. Thermal adhesion by softening or melting of the sheath component is achieved by heat treatment using a hot embossing roll or hot air having a temperature equal to or higher than the softening point of the sheath component of the composite fiber and less than the melting point of the core component.

  Moreover, in this invention, you may integrate a fiber by employ | adopting a hydroentanglement processing method. The hydroentanglement method may be combined with the thermal bond method. The conditions for the hydroentanglement treatment are set according to the basis weight, flexibility, and functionality of the nonwoven fabric to be finally obtained. In the case where an opening is formed in the nonwoven fabric, the conditions are set in consideration of that. In the hydroentanglement treatment, for example, a columnar water flow having a water pressure of 1 to 20 MPa is applied to one or both sides of the fiber web from a nozzle in which orifices having a hole diameter of 0.05 to 0.5 mm are provided at intervals of 0.5 to 1.5 mm. You may implement by injecting 1 to 8 times each.

  Even after the hydrophilic fiber of the present invention is subjected to hydroentanglement treatment under the above conditions, the ester compound of the formula (1) and / or the treatment agent on the fiber surface in the resin does not flow out instantaneously, and the hydrophilic performance. To maintain. In addition, while the water flow is jetted, the hydrophilic fiber of the present invention always maintains the state in which the fiber itself contains moisture and the fiber web is moistened. Therefore, the energy of the water stream efficiently contributes to the entanglement of the fiber web, and no turbulence of formation is generated, and a strong non-woven fabric is obtained.

  The fiber assembly containing the hydrophilic fiber of the present invention may contain other fibers. Other fibers are not particularly limited, and include, for example, natural fibers such as cotton, silk and wool, viscose rayon, cupra, and solvent-spun cellulose fibers (for example, lentung lyocell (registered trademark) and tencel (registered trademark)). Recycled fiber, polyethylene, polypropylene, polymethylpentene, ethylene-propylene copolymer, ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, or ethylene- (meta ) Polyolefin fiber made of methyl acrylate copolymer, etc., Polyester fiber made of polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, polyethylene naphthalate, polylactic acid, polybutylene succinate, nylon Or polyamide fibers made of nylon 66 or the like, consisting of acrylonitrile (poly) single fibers and polycarbonate acrylic, polyacetal, polystyrene, or a fiber or the like made of engineering plastic, such as cyclic polyolefin. Moreover, as other fibers, not only a single fiber composed of one kind of polymer component but also a composite fiber containing two or more kinds of polymer components can be used. Examples of the composite fiber include a composite fiber obtained by combining different types of resins such as polyester, polyolefin, polyamide, engineering plastic, or resins (for example, polyethylene terephthalate and polytrimethylene terephthalate) made of the same type of different polymer components. Is mentioned. In the above-mentioned composite fiber, the composite state is not particularly limited, and the cross-sectional shape in the fiber cross section is a core-sheath type composite fiber, an eccentric core-sheath type composite fiber, a parallel type composite fiber, and a citrus tufted resin component are alternately arranged. It may be a split type composite fiber or a sea-island type composite fiber. Only one type of these fibers may be used, or two or more types may be used.

  When the fiber assembly of the present invention is obtained in the form of a nonwoven fabric and used as the surface material of the absorbent article, the nonwoven fabric is preferably a heat-bonded nonwoven fabric. In other words, only the hydrophilic fiber of the present invention, or this and other fibers are mixed, and a fiber web having a desired basis weight is produced by the card method or air lay method, and then entangled as necessary. A heat-bonding nonwoven fabric obtained by applying and heat-bonding fibers to each other is preferably used as a surface material for absorbent articles. A nonwoven fabric may be a laminated structure of the fiber web which contains the fiber of this invention (or consists only of this), and the fiber web which consists of another fiber. Regardless of the structure, the hydrophilic fiber of the present invention is preferably contained in the surface material of the absorbent article in an amount of 50 mass% or more, so that human or animal body fluid can be quickly transferred from the body to the absorber. Can be moved to.

The basis weight of the fiber aggregate containing the hydrophilic fiber of the present invention is not particularly limited, and is appropriately selected depending on the application. For example, when the fiber assembly of the present invention is used as a nonwoven fabric as a surface material of an absorbent article, the basis weight is preferably 15 to 80 g / m ² . When the fiber assembly of the present invention is used as a nonwoven fabric for various wiping sheets for humans, animals, and objectives such as wet tissues, wipers, and disposable towels, the basis weight is preferably ²⁰ to 100 g / m ² . Moreover, when using the fiber assembly of the present invention as a nonwoven fabric for a cosmetic-impregnated sheet such as a face mask or a cosmetic / medical patch, the basis weight is preferably ²⁰ to 200 g / m ² .

(Ester compound)
The following are prepared as ester compounds represented by the formula (1). The melting point of the ester compound represented by the formula (1) is measured by a differential scanning calorimetry (DSC) method using a differential scanning calorimeter, and the measured melting peak temperature (peak top temperature) is expressed by the formula (1). It was set as melting | fusing point of the ester compound shown by these. More specifically, a differential scanning calorimeter (trade name EXSTAR6000 / DSC6200, manufactured by Seiko Instruments Inc.) was used, and the sample amount was 3 mg, held at 20 ° C. for 30 minutes, and then increased at 10 ° C./min. Melting was performed at a warm speed to obtain a heat of fusion curve, and the melting peak temperature was determined from the obtained heat of fusion curve. When obtaining the melting peak temperature by this method, the sample became liquid when it was held at 20 ° C. for 30 minutes, and the ester compound in which the melting peak temperature was not detected was solidified at 0 ° C., and then the humidity was 65%. And left in a constant temperature bath at 20 ° C. for 1 hour. The compound that was confirmed to be liquid after being allowed to stand was said to have a melting point of 20 ° C. or lower (≦ 20).

(1). Polyglycerin-1 (hereinafter also referred to as PG-1): diglycerin monooleate (trade name “DG series DG-MO”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ^{1 in} formula (1): 17 (unsaturated), n in formula (1), melting point: 20 ° C. or lower, HLB value: 5.3
(2). Polyglycerin-2 (hereinafter also referred to as PG-2): diglycerin monoisostearate (trade name “S-face IS-201P”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ^{1 in} formula (1) : 17 (saturated), n in formula (1), melting point: 20 ° C. or lower, HLB value: 4.7
(3). Polyglycerin-3 (hereinafter also referred to as PG-3): diglycerin laurate (trade name “DG series DG-ML”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ¹ in formula (1): 11 (Saturation), n in formula (1), melting point: 21 ° C., HLB value: 7.2
(4). Polyglycerin-4 (hereinafter also referred to as PG-4): Tetraglycerin monooleate (trade name “SY Glyster MO-3S”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ^{1 in} formula (1): 17 (unsaturated), n in formula (1): 4, melting point: 20 ° C. or lower, HLB value: 8.8
(5). Polyglycerin-5 (hereinafter also referred to as PG-5): Decaglycerin monooleate (trade name “SY Glyster MO-7S”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ¹ in the formula (1): 17 (unsaturated), n in formula (1), melting point: 20 ° C. or lower, HLB value: 12.9
(6). Polyglycerin-6 (hereinafter also referred to as PG-6): diglycerin monostearate (trade name “DG series DG-MS”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ^{1 in} formula (1): 17 (saturated), n in formula (1): 2, melting point: 59 ° C., HLB value: 5.5
(7). Polyglycerin-7 (hereinafter also referred to as PG-7): diglycerin myristate (trade name “DG series DG-MM”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ¹ in formula (1): 13 (Saturated), n in formula (1), melting point: 39 ° C., HLB value: 6.5
(8). Polyglycerin-8 (hereinafter also referred to as PG-8): Hexaglycerin monostearate (trade name “SY Glyster MS-5S”) manufactured by Sakamoto Pharmaceutical Co., Ltd., carbon number of R ¹ in the formula (1): 17 (saturated), n in formula (1): 6, melting point: 56 ° C., HLB value: 11.6
Table 1 shows the carbon number, n, melting point and HLB value of R ¹ of PG-1 to PG-8.

A treating agent containing the following components was prepared as a treating agent that adheres to the fiber surface of the thermoplastic fiber and contains 5 mass% or more of the polyether compound represented by the formula (2).
(1). Treatment agent 1
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 15 mass%
・ Tetraglycerin monostearate: 25 mass%
・ Sorbitan monostearate: 10 mass%
(2). Treatment agent 2
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 15 mass%
・ Tetraglycerin monostearate: 20 mass%
・ Sorbitan monostearate: 15 mass%
(3). Treatment agent 3
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 15 mass%
・ Sorbitan monostearate: 35 mass%
(4). Treatment agent 4
· C ₁₂ phosphate (K salt): 20mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 15 mass%
・ Sorbitan monostearate: 45 mass%
(5). Treatment agent 5
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 20 mass%
・ Sorbitan monostearate: 30mass%
(6). Treatment agent 6
· C ₁₂ phosphate (K salt): 20mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 10 mass%
・ Sorbitan monostearate: 50 mass%
(7). Treatment agent 7
· C ₁₂ phosphate (K salt): 30mass%
· _{C 8} phosphate (K salt): 25mass%,
・ Polyoxyalkylene alkyl ether: 9 mass%
・ Tetraglycerin monostearate: 11 mass%
・ Sorbitan monostearate: 20 mass%
・ Sorbitan monopalmitate: 5 mass%
(8). Treatment agent 8
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 7mass%
・ Sorbitan monostearate: 43 mass%
Table 2 shows the compositions of the processing agents 1-8.

なお、上記処理剤に含まれる、ポリオキシアルキレンアルキルエーテルと記載したポリエーテル化合物は、前記式（２）において、Ｒ^２が、炭素数３０（Ｃ＝３０）のトリアコンチル基、Ａはオキシエチレン単位のみで構成され、オキシエチレン単位が１０個繰り返されたポリオキシアルキレン基からなるポリエーテル化合物である。

Incidentally, contained in the treatment agent, polyether compounds described polyoxyalkylene alkyl ether, in the formula (2), R ² is, triacontyl of 30 carbon atoms (C = 30), A is oxyethylene units And a polyether compound composed of a polyoxyalkylene group in which 10 oxyethylene units are repeated.

Among the fiber treatment agents to be adhered to the fiber surface of the thermoplastic fiber, a treatment agent having a content of the polyether compound represented by the formula (2) of less than 5 mass%, or a polyether compound represented by the formula (2) The following treatment agents were prepared as treatment agents not contained.
(9). Treatment agent 9
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Polyoxyalkylene alkyl ether: 3 mass%
・ Sorbitan monostearate: 47 mass%
(10). Treatment agent 10
· C ₁₂ phosphate (K salt): 30mass%
-C ₈ phosphate (K salt): 20 mass%
・ Tetraglycerin monostearate: 25 mass%
・ Sorbitan monostearate: 25 mass%
(11). Treatment agent 11
· C ₁₂ phosphate (K salt): 35mass%
-C ₈ phosphate (K salt): 20 mass%
・ Tetraglycerin monostearate: 30mass%
・ Sorbitan monostearate: 15 mass%
(12). Treatment agent 12
· C ₁₂ phosphate (K salt): 25mass%
· _{C 8} phosphate (K salt): 30mass%,
・ Sorbitan monostearate: 35 mass%
・ Sorbitan monopalmitate: 10 mass%
(13). Treatment agent 13
· C ₁₂ phosphate (K salt): 65mass%
-C ₈ phosphate (K salt): 35 mass%
Table 3 shows the compositions of the treatment agents 9-13.

なお、上記処理剤に含まれる、ポリオキシアルキレンアルキルエーテルと記載したポリエーテル化合物は、前記式（２）において、Ｒ^２が、炭素数３０（Ｃ＝３０）のトリアコンチル基、Ａはオキシエチレン単位のみで構成され、オキシエチレン単位が１０個繰り返されたポリオキシアルキレン基からなるポリエーテル化合物である。

Incidentally, contained in the treatment agent, polyether compounds described polyoxyalkylene alkyl ether, in the formula (2), R ² is, triacontyl of 30 carbon atoms (C = 30), A is oxyethylene units And a polyether compound composed of a polyoxyalkylene group in which 10 oxyethylene units are repeated.

Example 1
Polypropylene resin (trade name: SA03, manufactured by Nippon Polypro Co., Ltd.) having a melting point of 160 ° C. and MFR of 30 before spinning, and polyethylene resin (trade name: HE490) having a melting point of 130 ° C. and MFR of 20 before spinning. , Manufactured by Nippon Polyethylene Co., Ltd.). 8 mass% of a master batch containing 10 mass% of the ester compound (PG-1) shown in Table 1 was mixed with the polyethylene resin. The composite ratio of polypropylene resin / polyethylene resin (core component / sheath component) is 50/50, melt-spun at a take-up speed of 600 m / min, and the ester compound is contained in an amount of 0.8 mass% with respect to the mass of the sheath component. A core-sheath type composite unstretched filament was obtained.

  Next, the unstretched filament was subjected to a wet stretching process using warm water at a stretching temperature of 80 ° C. and a stretching ratio of 2.5 times, and the treating agent 1 shown in Table 2 was applied to the stretched filament. The treatment liquid diluted with water so that the amount becomes 3.75 mass% was adhered by an impregnation method before passing through the crimper roll. The filament to which the treatment solution was attached was introduced into the crimper roll, and crimped by the crimper roll, and at the same time, excess treatment solution was squeezed out so that the moisture content of the entire filament was 8%. Thereafter, the moisture on the fiber surface was evaporated and dried through a drying process at 110 ° C. for 15 minutes, and then cut into a fiber length of 51 mm with a cutter. As a result, a core-sheath type composite fiber having a fineness of 2.2 dtex and a crimp rate of 12% was obtained.

In this invention, the adhesion amount of the processing agent to the fiber surface was measured by the rapid extraction method using the Tokai Keiki Co., Ltd. R-II type rapid residue extraction apparatus. First, 4 g of fibers cut to a predetermined length are put on a card machine to form a web, and the mass (W _f ) of the obtained web is measured. The web whose mass was measured was filled into a metal cylinder (inner diameter 16 mm, length 130 mm, bottom having a mortar shape with a 1 mm hole at the bottom), and 10 ml of methanol was added from the top. Methanol, which is dripped from the hole at the bottom and dissolved in the treatment agent attached to the fiber sample, is received while heating the aluminum dish (mass: W _tray ), and the methanol is evaporated. The mass (W _tray ) of the aluminum pan is measured after the aluminum pan is sufficiently dried with a dryer and before receiving methanol. After the methanol is completely evaporated, the mass (W _fat ) of the aluminum pan in which the fiber treatment agent remains is measured. After said measurement, the adhesion amount of the processing agent to the fiber surface with respect to fiber mass is calculated from the following formula.

  In the said Example 1, the processing agent adhesion amount measured based on the said measuring method was 0.30 mass%. From the adhesion amount of this treatment agent and the ratio of each component contained in the treatment agent, the adhesion amount of each component such as a polyether compound, a fatty acid ester of polyglycerin, and a phosphate surfactant contained in the oil agent to the fiber surface is determined. Calculated.

From the obtained fiber, a fiber web having a basis weight of 30 g / m ² is prepared using a parallel card, and the sheath component of the fiber is melted at a heat treatment temperature of 140 ° C. using a hot air spraying device, and the fibers of the fiber web are bonded to each other. A heat-bonded nonwoven fabric obtained by heat bonding was referred to as Example 1.

(Examples 2-5, Comparative Examples 1-3)
The fibers were processed in the same procedure as that employed when producing Example 1, except that a master batch containing each of the ester compounds (PG-2 to PG-5) shown in Table 1 was mixed with polyethylene. Further, a heat-bonded nonwoven fabric was prepared, and the obtained heat-bonded nonwoven fabrics were designated as Examples 2 to 5, respectively. Similarly, the procedure was the same as that employed when preparing Example 1 except that a master batch containing each of the ester compounds (PG-6 to PG-8) shown in Table 1 was mixed with polyethylene. Fibers were obtained by the procedure, heat-bonded nonwoven fabrics were produced, and the heat-bonded nonwoven fabrics obtained were designated as Comparative Examples 1 to 3, respectively.

  Further, the melting point of the resin before spinning is measured according to JIS-K-7122 (DSC method), MFR is the melt flow rate of the polymer measured according to JIS-K-7210, and MFR of polypropylene. Is measured at 230 ° C. and 21.18 N (2.16 kgf) according to JIS-K-7210, and the MFR of polyethylene is 190 ° C. and 21.18 N (2.16 kgf) according to JIS-K-7210. It was measured.

  Durability hydrophilicity of the nonwoven fabrics of Examples 1 to 5 and Comparative Examples 1 to 3 was evaluated by the following procedure with changes made to the method described in JP-A-9-322911.

  A non-woven fabric was cut into a size of 60 mm × 60 mm, and Toyo No. 2 Filter paper is put on the nonwoven fabric to make a sample, and the sample is sandwiched between a pair of glassware for liquid flow (cylindrical one having a height of 75 mm, an inner diameter of 36 mm, and a thickness of 3 mm) via a silicone packing. Fixed. Then, 40 ml of ion exchange water is poured into the upper glass apparatus for liquid passage, and when the amount of the ion exchange water reaches 20 ml, the nonwoven fabric is taken out and sandwiched between two filter papers. After placing a weight of 1 kg and letting it stand for 1 minute, it was naturally dried for 30 minutes under the conditions of an air temperature of 25 ° C. and a humidity of 60%. A nonwoven fabric that has been naturally dried for a predetermined time is placed on a new filter paper (Toyo No. 2) and used as a sample. From the top, 20 drops of ion-exchanged water are dropped on the nonwoven fabric using a dropper. The number of droplets that migrated and disappeared from the nonwoven fabric surface was counted.

Durability hydrophilicity was evaluated according to the following criteria.
A: The number of droplets transferred from the nonwoven fabric to the filter paper within 60 seconds is 15 or more.
A: The number of droplets transferred from the nonwoven fabric to the filter paper within 60 seconds is 10 to 14.
Δ: The number of droplets transferred from the nonwoven fabric to the filter paper within 60 seconds is 5 to 9.
X: The number of droplets transferred from the nonwoven fabric to the filter paper within 60 seconds is 4 or less.

  Tables 4 and 5 show the results of evaluating the durable hydrophilic properties of the nonwoven fabrics of Examples 1 to 5 and Comparative Examples 1 to 3.

As shown in Table 4, the fiber containing an ester compound having a melting point of 30 ° C. or lower showed excellent durable hydrophilicity. Even if n is the same value, it can be seen from the evaluation results shown in Table 4 that the melting point varies depending on the number of carbon atoms of R ¹ and that there is no relationship between HLB and durable hydrophilicity. Further, in Comparative Examples 1 to 3 shown in Table 5, even when the ester compound contained in the thermoplastic resin (polyethylene resin) constituting the fiber surface is represented by the formula (1), the melting point is 30 ° C. Therefore, it can be seen that the ester compound contained in the polyethylene resin has poor durability and hydrophilicity as compared with Examples 1 to 5 in which the melting point is 30 ° C. or lower.

  The durability hydrophilicity evaluation method employed here is the method described in JP-A-9-322911 (the cycle of injecting 40 ml of ion-exchanged water is repeated, and the 20 ml flow time T reaches 180 seconds (180 seconds). The number of cycles is counted as the number of passing times, and the higher the number of passing times, the higher the durability and hydrophilicity). This is because the durable hydrophilicity is measured over the entire surface of the nonwoven fabric in the method for evaluating durable hydrophilicity described in JP-A-9-322911. When evaluating by this method, even if the nonwoven fabric is in a state where it has lost hydrophilicity in the majority of its surface, if only a small part of the nonwoven fabric surface has hydrophilicity, the portion is Since ion-exchanged water passes, there is a possibility that the nonwoven fabric is highly durable and hydrophilic. In the durable hydrophilicity evaluation method employed in the present invention, durable hydrophilicity is measured at each portion where ion-exchanged water is dropped on the nonwoven fabric surface, and 5 or more, preferably 10 or more, more preferably 15 of 20 locations. It is because it is not evaluated that it has durable hydrophilicity, if it does not have hydrophilicity in the part or more.

(Examples 6-12, Comparative Examples 4-8)
A hydrophilic fiber was produced by changing the type of the treatment agent to be attached to the fiber surface, and its durable hydrophilic property was evaluated.
Specifically, a fiber containing diglycerin monooleate (PG-1) was prepared according to the same procedure adopted when Example 1 was prepared. Treatment agents (treatment agent 2 to treatment agent 13) having the compositions shown in Table 2 or Table 3 were attached thereto. Regardless of which treatment agent is used, a treatment solution is prepared by diluting with water so that the concentration of the treatment agent is 3.75 mass%, and the treatment solution is adhered to the fiber surface so that the moisture content is 8%. I let you. Furthermore, the nonwoven fabric was produced according to the same procedure employ | adopted when producing Example 1 using the obtained fiber, and durable hydrophilic property was evaluated. The evaluation results are shown in Tables 6 and 7. In addition, about the hydrophilic fiber of Examples 6-12 and the fiber of Comparative Examples 4-8, the process calculated | required from Formula (4) using said Tokai Keiki R-II type quick residue extraction apparatus. The adhesion amount of the agent was 0.30 mass% in any of the examples and comparative examples.

(Comparative Examples 9-13)
A core-sheath type composite fiber was produced using the same thermoplastic resin used when Example 1 was produced. At this time, without adding a masterbatch containing an ester compound to the polyethylene resin constituting the sheath component, melt spinning and stretching are performed under the same conditions as those used in Example 1, and the sheath component is represented by the formula (1). A core-sheath type composite fiber made of polypropylene resin / polyethylene resin not containing the ester compound shown was produced. The treating agents 1 to 5 in Table 2 were attached to this fiber. Regardless of which treatment agent is used, a treatment solution is prepared by diluting with water so that the concentration of the treatment agent is 3.75 mass%, and the treatment solution is adhered to the fiber surface so that the moisture content is 8%. I let you. Furthermore, the nonwoven fabric was produced according to the same procedure employ | adopted when producing Example 1 using the obtained fiber, and durable hydrophilic property was evaluated. The evaluation results are shown in Table 8. In addition, about the fiber of Comparative Examples 9-13, the adhesion amount of the processing agent calculated | required from Formula (4) using said Tokai Keiki Co., Ltd. R-II type quick residue extraction apparatus is in any comparative example. Was 0.30 mass%.

  As shown in Table 6, all the treatment agents containing polyoxyalkylene alkyl ether contributed to the improvement of the durability and hydrophilicity of the fiber containing diglycerin monooleate in the sheath component. Each of Comparative Examples 5 to 8 to which a treatment agent not containing polyoxyalkylene alkyl ether was attached showed lower durability hydrophilicity than other samples to which a treatment agent containing polyoxyalkylene alkyl ether was attached. The ratio of polyoxyalkylene alkyl ether contained therein is less than 5 mass%, that is, Comparative Example 4 in which the amount of polyoxyalkylene alkyl ether finally adhered to the fiber surface is less than 0.01 mass% is also polyoxyalkylene. Compared with the sample which used the processing agent containing 5 mass% or more of alkyl ethers, low durability hydrophilicity was shown.

  Even if it is the processing agent (processing agents 1-5) which showed high durable hydrophilic property in Table 4 or Table 5, when the ester compound whose melting | fusing point is 30 degrees C or less is not contained in the fiber surface, durable hydrophilic property should not be exhibited. Can be seen from the evaluation results of durable hydrophilic properties of Comparative Examples 9 to 13 shown in Table 8. From the comparison between Examples 1 and 6 to 9 and Comparative Examples 9 to 13, when an ester compound having a melting point of 30 ° C. or less is contained on the fiber surface, the treatment agent to be attached to the fiber surface contains polyoxyalkylene alkyl ether. In addition, it was found that when the amount of polyoxyalkylene alkyl ether attached to the fiber surface is 0.01 mass% or more, the durable hydrophilic property is improved by a synergistic effect. Moreover, it turned out that the synergistic effect is heightened more as the adhesion amount of polyoxyalkylene alkyl ether increases, from the comparison of Examples 6 to 9, Examples 10, 11 and Example 12. From the above results, in the fiber made of a thermoplastic resin containing an ester compound having a melting point of 30 ° C. or less on the fiber surface, a fiber treatment agent containing a specific polyether compound is used as the fiber treatment agent, and the polyoxyalkylene is applied to the fiber surface. By attaching 0.01 mass% or more of alkyl ether, a synergistic effect is exhibited by the ester compound contained in the thermoplastic resin constituting the fiber surface and the polyether compound contained in the treatment agent attached to the fiber surface, and the thermoplastic resin. It has been found that the durability and hydrophilicity of the fibers made of is dramatically improved. And in order to exhibit this synergistic effect, it turned out that the said specific polyether compound needs to be contained at least 5 mass% in a processing agent.

  The hydrophilic fiber of the present invention has a good durable hydrophilic property and needs to be maintained for a certain period of time, for example, absorbent articles (for example, disposable diapers, sanitary napkins, and urine leak pads). Suitable for constructing face sheets, various wipes for humans, animals and objectives such as wipers, wet tissues, and disposable towels, cosmetic-impregnated sheets such as face masks, and cosmetic / medical patches. ing.

Claims (9)

A fiber made of a thermoplastic resin, which is composed of 0.2 to 2.5 mass% of an ester compound represented by the following formula (1) and having a melting point of 30 ° C. or lower, constitutes at least the fiber surface. And the hydrophilic fiber with which the polyether compound shown by following formula (2) has adhered to the fiber surface 0.01-0.2 mass% with respect to fiber mass.

(In the formula, R ¹ is a saturated or unsaturated aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n is an integer of 2 to 10).

(Wherein R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 60 carbon atoms or an aliphatic acyl group having 1 to 60 carbon atoms, and A is a total of 5 to 300 oxyethylene units and / or Or a polyoxyalkylene group composed of oxypropylene units.) The compound represented by the formula (1) is R ¹ is a saturated aliphatic hydrocarbon group or unsaturated aliphatic hydrocarbon group having 16 to 18 carbon atoms, and n is 2. Hydrophilic fiber. In the compound represented by the formula (2), R ² is an alkyl group having 25 to 45 carbon atoms, and in the formula, A is an oxyethylene unit having a total of 5 to 40 oxyethylene units of 90 mol% or more. The hydrophilic fiber according to claim 1 or 2, which is a polyether compound composed of a polyoxyalkylene group composed of an ethylene unit and / or an oxypropylene unit. In addition to the polyether compound represented by the formula (2), at least one kind of phosphate selected from sorbitan fatty acid ester, alkyl phosphate and POE alkyl (C _12-18 ) phosphate is attached to the surface of the hydrophilic fiber. The polyether compound represented by the formula (2) is 0.01 to 0.2 mass% with respect to the fiber mass, and the sorbitan fatty acid ester is 0.01 to 0.35 mass% with respect to the fiber mass. The hydrophilic fiber according to any one of claims 1 to 3, wherein 0.03 to 0.35 mass% of the phosphate is attached to the fiber mass.   The hydrophilic fiber according to any one of claims 1 to 4, wherein the ester compound represented by the formula (1) has a melting point of 20 ° C or lower.   The hydrophilic according to any one of claims 1 to 5, wherein the thermoplastic resin comprising a core component and a sheath component and containing the ester compound represented by the formula (1) is a thermoplastic resin constituting the sheath component. Sex fibers. With respect to a fiber composed of a thermoplastic resin at least comprising a thermoplastic resin represented by the formula (1) and containing 0.2 to 2.5 mass% of an ester compound having a melting point of 30 ° C. or less, the formula (1) The manufacturing method of the hydrophilic fiber characterized by making the processing agent containing 5-50 mass% of polyether compounds shown by 2) adhere 0.1-0.6 mass% with respect to fiber mass.

(In the formula, R ¹ is a saturated or unsaturated aliphatic hydrocarbon group having 8 to 22 carbon atoms, and n is an integer of 2 to 10).

(Wherein R ² is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 60 carbon atoms or an aliphatic acyl group having 1 to 60 carbon atoms, and A is a total of 5 to 300 oxyethylene units and / or Or a polyoxyalkylene group composed of oxypropylene units.) The processing agent contains at least one kind of phosphate selected from sorbitan fatty acid ester and alkyl phosphate and POE alkyl (C _12-18 ) phosphate in addition to the polyether compound represented by the formula (2). 10 to 30 mass% of the polyether compound represented by the formula (2), and the total of the content of the sorbitan fatty acid ester in the treatment agent and the content of the at least one phosphate is 40 The manufacturing method of the hydrophilic fiber of Claim 7 which is -90 mass%, content of the said sorbitan fatty acid ester is 10-60 mass%, and content of the said at least 1 type of phosphate is 30-60 mass%.   A fiber assembly comprising the hydrophilic fiber according to any one of claims 1 to 6 in an amount of 20 mass% or more.