US20050086741A1

US20050086741A1 - Fiber treatment agent composition

Info

Publication number: US20050086741A1
Application number: US10/498,820
Authority: US
Inventors: Keiko Hasebe; Juri Sata
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2001-12-28
Filing date: 2002-12-20
Publication date: 2005-04-28
Also published as: WO2003057976A3; AU2002349788A1; KR100950879B1; EP1521881A2; CN1639410A; EP1521881B1; ES2380428T3; WO2003057976A2; AU2002349788A8; KR20040070273A; CN1323209C

Abstract

A fiber treatment agent composition comprising an amphipathic lipid having hydroxyl group(s) and amide group(s) in the molecule thereof, the lipid being solid particles having an average particle size of 1 to 100 μm. The fiber treated with the fiber treatment agent composition of the invention provides excellent feeling to the resultant textile and pleasant feel to the skin. When a consumer wears the fiber product produced from the thus-treated fiber, remarkable effects are attained, including pleasant feel to the skin with which the fiber product is brought into contact, skin protective effect, effect of enabling the people having sensitive skin to wear at ease, moisturizing effect, and effect of improving skin disease such as rough skin.

Description

TECHNICAL FIELD

The present invention relates to a fiber treatment agent composition imparting excellent feeling to fibers, and to a fiber which provides excellent sense of touch and excellent feel when a consumer wears an end product produced from the fiber. More particularly, the invention relates to a fiber treatment agent composition containing an amphipathic lipid in solid particulate form having a specific average particle size that is beneficial for treatment of fiber; to a fiber bearing the amphipathic lipid on a surface thereof; and to a method of treating the fiber.

BACKGROUND ART

In recent years, treated fibers designed to produce effects analogous to those of skincare cosmetics have found utility in textile products, particularly those worn by consumers in their everyday lives. Japanese Patent Application Laid-Open (kokai) No. 8-60547 discloses a skincare fiber product to which serine-containing protein is attached. Japanese Patent Application Laid-Open (kokai) No. 2001-146680 discloses a finishing composition for textiles containing a nonionic amphipathic substance. More specifically, the nonionic amphipathic substance is a ceramide, and preferably, the ceramide is present, along with other components, in the composition while in the form of emulsion particles having a particle size of not more than 1,000 nm. By virtue of these features, the composition disclosed therein is reported to exhibit excellent emulsion stability over time, preventing precipitation of ceramides, and excellent cohesion or adhesion of ceramides to fibers to be treated. Also, the treated textile products promote moisture-retaining ability of the skin when consumers wear the products. Thus, the ceramides disclosed in this publication are not present in solid form.
However, these techniques are not necessarily satisfactory, in that ceramides cannot be retained on the fiber in such amounts that can provide sufficient effects, laundry durability is low, and feeling of the fiber cannot be improved without sacrificing other features.
An object of the present invention is to provide a fiber treatment agent composition which is capable of causing an amphipathic lipid having skincare effect to be stably retained on the fiber; which imparts excellent feeling to the fiber; and which, when a consumer wears an end product producing from the fiber, exhibits moisturizing effect to the skin and imparts pleasant feel to the skin with which the fiber product comes into contact.

DISCLOSURE OF THE INVENTION

The present invention provides a fiber treatment agent composition comprising an amphipathic lipid having hydroxyl group(s) and amide group(s) in the molecule thereof, said lipid being solid particles having an average particle size of 1 to 100 μm.
The present invention also provides a fiber treatment agent composition further comprising, in addition to the above-mentioned fiber treatment agent compositions one or more species selected from the group consisting of surfactants and aqueous medium.
The present invention also provides a treated fiber which is obtained through bringing the above-mentioned fiber treatment agent composition into contact with fiber so that the above-mentioned amphipathic lipid is caused to be present continuously or discontinuously on a surface of the fiber.
The present invention also provides a fiber to which the above-mentioned amphipathic lipid has been affixed.
The present invention also provides a method of treating fiber comprising bringing the above-mentioned fiber treatment agent composition into contact with fiber.

BEST MODE FOR CARRYING OUT THE INVENTION

As used herein, the “amphipathic lipid having hydroxyl group(s) and amide group(s) in the molecule thereof” (hereinafter, may be referred to as component (a)) is defined as such a lipid that contains one or more hydroxyl groups and one or more amide groups in the molecule of the lipid; that falls within the class consisting of natural ceramides, synthetic ceramides, and analogs (pseudo-ceramides) prepared therefrom through, for example, synthesis; and that is solid at room temperature (25° C.) Examples of the amphipathic lipid include Ceramide H03 (Sederma), CeramideII (Sederma), Quesamide H (Quest), Ceramide TIC-001 (Takasago International Corporation), and SOFCARECERAMIDE SL-E (Kao Corporation). From the viewpoint of stability of the lipid incorporated in the fiber treatment agent composition, the lipid preferably has a melting point of not less than 30° C., more preferably not less than 40° C. Among synthesized ceramide analogs, particularly preferred ones are amide derivatives represented by the following formula (1) (including the above-mentioned SOFCARECERAMIDE SL-E:

wherein R¹and R²are the same or different and each independently represents a linear or branched, saturated or unsaturated C₇-C₃₉hydrocarbon group which may be substituted by one or more hydroxyl groups; and R³and R⁴are the same or different and each independently represents a hydrogen atom, a phosphate salt residue, a sulfate salt residue, or a saccharide residue; provided that one or more hydroxyl groups are contained in one molecule of the derivative.
In the formula (1), R¹is preferably a linear or branched, saturated or unsaturated C₉-C₂₅hydrocarbon group; R²is preferably a linear or branched, saturated or unsaturated C₁₀-C₂₆hydrocarbon group; and each of R³and R⁴is preferably a hydrogen atom.
Methods for producing the above-mentioned amide derivative (1) are described in detail in, for example, Japanese Patent Application Laid-Open (kokai) No. 62-228048 and No. 63-216852.
The amphipathic lipid is solid particles having an average particle size of 1 to 100 μm, preferably 2 to 100 μm, more preferably 5 to 100 μm, even more preferably 5 to 80 μm, most preferably 7 to 50 μm. Preferably, the solid particles are present in a crystalline state.
The above-mentioned amphipathic lipids, which may be employed alone or in combination of two or more species, are incorporated in the fiber treatment agent composition of the present invention in an amount of 0.005 to 40 wt. %, preferably 0.05 to 40 wt. %, more preferably 5 to 40 wt. %, most preferably 10 to 30 wt. %. When the fiber treatment agent composition is a thick solution, the amount of the amphipathic lipids in the fiber treatment agent composition is preferably 1 to 40 wt. %, more preferably 5 to 40 wt. %, most preferably 10 to 30 wt. %, whereas when the composition is a dilute solution, their amount in the fiber treatment agent composition is preferably 0.005 to 1 wt. %, more preferably 0.01 to 0.9 wt. %, most preferably 0.02 to 0.6 wt. %.
No particular limitations are imposed on the surfactant (hereinafter may be referred to as component (b)) which may be used for the preparation of the fiber treatment agent composition of the present invention, and one or more species of surfactants may be suitably selected from nonionic surfactants, anionic surfactants, amphoteric surfactants, and cationic surfactants.
In the case where the amphipathic lipid is first subjected to crystallization along with component (b) and then incorporated into the fiber treatment agent composition, the component (b) is preferably one or more species selected from those ordinarily employed for cosmetic use; for example, selected from nonionic surfactants, anionic surfactants, and amphoteric surfactants.
Examples of the nonionic surfactants include alkyl polyglycosides, polyoxyalkylene alkyl or alkenyl ethers, polyoxyalkylene sorbitan fatty acid esters, sorbitan fatty acid esters, polyoxyalkylene sorbitol fatty acid esters, polyoxyalkylene glycerin fatty acid esters, polyglycerin fatty acid esters, fatty acid monoglycerides, polyethylene glycol fatty acid esters, and fatty acid alkanol amides.
Examples of the anionic surfactants include polyoxyalkylene alkyl ether acetic acid or salts thereof, N-acylamino acid salts, polyoxyalkylene alkyl ether sulfate salts, polyoxyalkylene alkyl ether phosphate salts, alkylphosphate salts, N-acylmethyltaurine salts, alkylsulfosuccinate salts, polyoxyalkylene alkylsulfosuccinate salts, and fatty acid salts.
Examples of the amphoteric surfactants include alkylaminoacetate betaine, alkylamine oxide, alkylamide propyl betaine, alkylhydroxy sulfobetaine, and amido amino acid (imidazoline-type betaine).
Preferred surfactants are nonionic surfactants and polyoxyethylene alkyl ether acetic acid or salts thereof. Preferred nonionic surfactants are alkyl polyglycosides, polyoxyalkylene alkyl or alkenyl ethers, polyoxyalkylene sorbitan fatty acid esters, and sorbitan fatty acid esters.
Most preferred nonionic surfactants include alkyl polyglycosides (e.g., those in which the alkyl group has 8 to 14 carbon atoms and a glucose condensation degree is 1 to 2), polyoxyalkylene alkyl or alkenyl ethers (e.g., those in which the alkyl or alkenyl group has 8 to 18 carbon atoms and the average mol number of added ethylene oxide is 4 to 25, preferably 4 to 15), polyoxyalkylene sorbitan fatty acid esters (e.g., those in which the fatty acid has 8 to 20 carbon atoms and the average mol number of added ethylene oxide is 5 to 25), and sorbitan fatty acid esters (e.g., monoesters of fatty acid having 8 to 20 carbon atoms).
Examples of the polyoxyalkylene alkyl ether acetic acid or salts thereof include such acids per se having 8 to 20 carbon atoms and an average mol number of added ethylene oxide of 3 to 15; and alkali metal salts thereof. That is, the polyoxyalkylene alkyl ether acetic acid may be used as is (without neutralization) or after being neutralized.
When a cationic surfactant is further added, enhanced adsorption of the amphipathic lipid onto the fiber can be attained. Examples of the cationic surfactants include mono(long-chain alkyl)ammonium salts, di(long-chain alkyl)ammonium salts, benzalkonium salts, benzethonium salts, and pyridinium salts.
Any of the above-mentioned surfactants may be employed singly or in combination of two or more species. The surfactant(s) may be incorporated in the fiber treatment agent composition in an amount of 2 to 55 wt. %, preferably 5 to 40 wt. %. When a crystallization step is performed, it is particularly preferred that these ranges be met.
The ratio by weight of amphipathic lipid to surfactant; i.e., (a)/(b), is preferably 90/10 to 25/75, more preferably 80/20 to 30/70, most preferably 70/30 to 40/60. When a crystallization step is performed, it is particularly preferred that these ranges be met.
As used herein, the aqueous medium which may be employed for producing the fiber treatment agent composition of the present invention is water and/or a polar organic solvent which is soluble in water. Examples of water-soluble polar organic solvents include alcohols such as methanol, ethanol, and propanol; glycols such as ethylene glycol, propylene glycol, diethylene glycol, and polyethylene glycol; and acetone.
Preferred examples of the aqueous medium include water, ethanol, and glycols, with water being most preferred.
In treatment of fiber, the fiber treatment agent composition of the present invention may be used as is or after diluted with water and/or a water-soluble polar organic solvent, or alternatively diluted with a surfactant and an aqueous medium. When the fiber treatment agent composition of the present invention is a thick solution, the composition is preferably diluted before use.
The fiber treatment agent composition of the present invention can be produced by, for example, heating a mixture of an amphipathic lipid (component (a)), a surfactant (component (b)), and water to a temperature of not less than the melting point of the amphipathic lipid (from the melting point to about a temperature 10° C. higher than the melting point) under stirring, to thereby melt the mixture, and after the melt became a homogeneous state, cooling the melt under stirring, so as to cause crystallization of the component (a).
In this process, the particle size of component (a) can be regulated through control of the type and amount of the surfactant, cooling rate, and speed of stirring or the like. Preferably, component (a) has an average particle size of 1 to 100 μm, more preferably 2 to 100 μm, still more preferably 5 to 100 μm, even more preferably 5 to 80 μm, most preferably 7 to 50 μm, as measured by the method described hereinbelow. As used herein, the average particle size is an arithmetic mean value determined by photographing the particles under an optical microscope under transmission light, selecting arbitrary 30 particles on a photograph, and for each of the 30 particles, measuring the major axis of the particle.
The fiber treatment agent composition of the present invention may also contain a pH-regulator, a preservative, a softening agent, a hardening agent, an antistatic agent, an antimicrobial/deodorizing agent, a moisturizing agent and so on.
Examples of the moisturizing agent include plant extracts, sodium hyaluronate, collagen, animal oils, vegetable oils, paraffin, liquid paraffin, vaseline, ceresine, squalane and so on.
Plant extracts are extracts obtained through any of a variety of plants, and examples thereof include aloe, aloe vera, ginkgo, fennel, seaweed, pueraria root, chamomile, kiwi, cucumber, dishcloth gourd, gardenia, rice bran, peach, citron, adlay, mugwort, Saint-John's-wort, tea and so on.
Examples of vegetable oils include olive oil, camellia oil, macadamia nut oil, castor oil, carnauba wax, candelilla wax, jojoba oil, safflower oil, soybean oil, shea oil, sunflower oil, cacao oil, coconut oil, palm kernel oil, meadowfoam seed oil, rice germ oil, orange oil and so on.
Examples of animal oils include mink oil, beeswax, lanolin and so on.
Examples of fibers used in the present invention include natural fibers such as cotton, silk, hemp, and wool; regenerated fibers such as rayon, cuprammonium rayon, and tensel; semi-synthetic fibers such as acetate, diacetate, and triacetate; and synthetic fibers such as polyester, nylon, acrylic, vinylon, polypropylene, and polyurethane. No particular limitations are imposed on the form of the fiber, and examples of the fiber include a variety of fibrous materials such as staple fiber and yarn; semi-products such as nonwoven fabric, knit fabric, and woven fabric; and end products such as clothes and bedclothes.
Preferred examples of fiber products produced from the above-mentioned fibers include those which are used in direct contact with skin or hair; specifically, underwear such as panty hoses, tights, lingerie, petticoats, camisoles, shorts, undershirts, trunks, and briefs; foundations such as girdles, brassieres, and body suits; night wears such as night dresses, pajamas, and bathrobes; clothes such as leotards, socks, stomach bands, gloves, mufflers, masks, towels, and headgears; and bedclothes such as pillow covers and sheets.
According to one method of the present invention for treating fiber, fiber is brought into contact with the fiber treatment agent composition of the present invention.
Such a step of bringing fiber into contact with the fiber treatment agent composition may include immersion of fiber in the fiber treatment agent composition, followed by drying; and spraying the fiber treatment agent composition onto fiber, followed by drying. Such treatment yields fibers bearing the amphipatic lipid in a continuous fashion or discontinuous fashion oh a surface of the fiber. Drying may be performed through either naturally or with application of heat. Pressurized heat treatment may be performed by use of, for example, an iron or trousers presser.
Examples of specific treatment method include the pad drying method using a mangle and a dryer; the dip dyeing method employing a wince dyeing machine, a cheese dyeing machine, or a jet dyeing machine; the spray method; the coating method; the printing method; and the additive blending method applied for rayon or acrylic fibers.
When textile products are concerned, the fiber treatment agent composition of the present invention may be used in any step during laundry, e.g., in a washing step, a rinsing step, a softener-finishing step, or a sizing step. Alternatively, the fiber treatment agent composition of the present invention may be directly applied to clothing or bedclothes by the spray method and so on.
In the fiber treatment method of the present invention, the amphipathic lipid is preferably employed in an amount of 0.001 to 5 wt. %, more preferably 0.05 to 1 wt. %, most preferably 0.1 to 0.8 wt. %, with respect to the weight of the fiber.
In treating the fiber, a binder may optionally be used. Use of a binder is preferred from the viewpoint of laundry durability. Examples of the binder include silicone resins, acrylic resins, urethane resins, vinyl acetate resins and so on. In this case (i.e., when treatment of fiber is performed), in addition to a binder, there may also be used the following agents depending on purposes: softening agent, hardening agents, sewing facilitating agents, flame retardants, antistatic agents, soil repellents, antimicrobial/deodorizing agents, raising agents, slip-preventing agents, moisturizing agents, water repellants, water absorbers, fluorescent dyes, anti-shrinking agents such as glyoxal, fixing agents and so on.
From the viewpoints of good laundry durability and fiber treatment effect, the binder is preferably employed in an amount of 10 to 500 wt. %, more preferably 50 to 300 wt. %, with respect to the weight of the amphipathic lipid, wherein the calculation is on the basis of solid components of the binder.
It is believed that, the amphipathic lipid of the invention, due to its specific form (i.e., solid particles having an average particle size of 1 to 100 μm), does not tend to be incorporated into the inside of the treated fiber, but is effectively affixed onto the surface of fiber as compared with amphipathic lipids in solubilized form or emulsified form. Moreover, when the fiber treatment process includes a washing step or rinsing step, amphipathic lipids in solubilized form or emulsified form are easily removed through washing. According to the present invention, however, since the amphipathic lipid is solid particles having an appropriate size, it is not easily washed away, whereby attaining improved retention of the lipid in fiber. From these reasons, fiber that has undergone treatment with the fiber treatment agent composition of the invention is considered to exhibit excellent feeling of the resulting textile and pleasant feel to the skin.

EXAMPLES

Example Nos. 1 through 3 and Comparative Example 1

Preparation of Fiber Treatment Agent Composition

The amphipathic lipids, surfactants, and water shown in Table 1, in columns of Example Nos. 1 through 3 were heated to 80 to 90° C. Subsequently, each of the resultant mixtures was cooled under stirring, to thereby allow the amphipathic lipid to crystallize. Stirring was further performed and the mixture was cooled to room temperature, to thereby yield a fiber treatment agent composition. The amphipathic lipid contained in the resultant composition was found to be solid particles of needle-like to plate-like crystals having an average particle size of 11.8 μm (Example 1), 8.9 μm (Example 2), or 16.3 μm (Example 3). The crystalline state was confirmed through X-ray diffraction.

In Comparative Example 1, the procedure of Example 1 was repeated, except that the 32.0 parts by weight of MYDOL 10 was replaced by 23.0 parts by weight of RHEODOL TW-S120, to thereby obtain a composition in which the amphipathic lipid remains uncrystallized but is present as emulsion particles (confirmed through X-ray diffraction).

TABLE 1


(parts by weight)

		Comp.
		Exam-
	Examples	ple

	1	2	3	1

(a)	Formula (1)	20.0	23.0	15.0	20.0
Amphipathic	R¹= C₁₅H₃₁
lipid	R²= C₁₆H₃₃
	R³= H
	R⁴= H
	(m.p.:
	74-76° C.)
	Formula (1)			3.0
	R¹= C₁₇H₃₅
	R²= C₁₄H₂₉
	R³= H
	R⁴= H
	(m.p.:
	78-80° C.)
(b)	MYDOL 10*¹	32.0		25.0
Surfactant	EMULGEN 106*²		15.5
	KAO AKYPO			2.0
	RLM-100*³
	RHEODOL				23.0
	TW-S120*⁴

Water	balance	balance	balance	balance
Average particle size (μm)	11.8	8.9	16.3	1 or less
Particle form	Solid	Solid	Solid	Liquid
	particles	particles	particles	particles

*¹Kao, Decyl polyglycoside (Condensation degree: 1-1.35), Effective ingredient: 40 wt. %
*²Kao, Polyoxyethylene (5) lauryl ether
*³Kao, Polyoxyethylene (10) lauryl ether acetic acid, Effective ingredient: 89 wt. %
*⁴Kao, Polyoxyethylene (20) sorbitan monostearate

Test Example 1 and Comparative Test Examples 1 and 2

1 g of the fiber treatment agent composition obtained from Example 1 was dispersed in 2.0 L of water, and 25 g of a pair of panty hose, which had been washed five times with a commercially obtained detergent, was soaked therein. Subsequently, the panty hose were dewatered once, then rinsed in an equivolume of water, followed by dewatering again, natural drying, to thereby obtain a treated fiber product of the present invention. In the same manner, three pairs of panty hose were prepared, and were provided to a panelist. Then five women panelists, who have dry skin and often complain itchiness when they wear panty hose, carried out wearing test of the panty hose for 3 days in winter (Test 1).
For comparison, by use of the composition obtained from Comparative Example 1; i.e., the composition in which the amphipathic lipid remains uncrystallized but is present as emulsion particles, several pairs of panty hose were treated in a similar manner, and wearing test was carried out by the same five panelists as in Test Example 1 (Comparative Test 1). Also, wearing test of several pairs of panty hose that have undergone similar treatment, but undergone no treatment with fiber treatment agent composition, was carried out (Comparative Test 2).
The results are all shown in Table 2. The evaluation items and evaluation criteria are as follows. The results shown in the Table are average ratings from the 5 panelists.
Feeling of Fabric (Feel to Touch)

- 4: Very good
- 3: Good
- 2: Slightly poor
- 1: Poor
  Ease of Wearing (Smoothness)
- 4: Very good
- 3: Good
- 2: Slightly poor
- 1: Poor
  Change in Sensation Felt by the Skin by Wearing
- 4: Turned very good
- 3: Turned better
- 2: No change
- 1: Turned worse
  Moisturizing Effect by Wearing
- 4: Very effective
- 3: Effective
- 2: Somewhat effective
- 1: Not effective
  Itchiness of the Skin After Wearing
- 4: Itchiness was removed
- 3: Itchiness was removed to some extent
- 2: No change

1: Itchiness aggravated

TABLE 2


	Test 1	Comp. Test 1	Comp. Test 2

Feeling of fabric	3.6	1.8	1.6
Ease of wearing	4.0	2.2	2.0
Change in sensation	3.8	2.2	1.8
felt by the skin
Moisturizing effect	3.4	1.2	1.0
Itchiness of the skin	3.4	2.2	1.8

As is apparent from Table 2, the fiber which has been treated with the fiber treatment agent composition of the present invention imparts excellent feeling to the resultant fiber product, exhibits smoothness of the fiber product when a person wears the same, improves touch to the skin, enhance the moisturizing effect, and mitigates itchiness of the skin.

Test Example Nos. 2 through 4

Each 5 g of the fiber treatment agent compositions obtained from Examples 1, 2, and 3 (corresponding to Tests 2, 3, and 4, respectively) was dispersed in 10.0 L of water. 1.0 Kg of cotton fiber (cotton fabric) was soaked in the resultant dispersion. Thereafter, the cotton fiber was squeezed with a mangle, then dried at 55° C. for 30 minutes, to thereby yield a treated fiber of the present invention.
Ten panelists consisting of five men and five women touched the treated fiber and fiber that had undergone a similar treatment without use of the fiber treatment agent composition of the present invention, to compare them in terms of sensation by the blind method. The results are shown in Table 3. The evaluation criteria are shown below. The ratings shown in Table 3 are average values of the ratings given by the 10 panelists.
Sensation

- 5: The invention product is much better
- 4: The invention product is better
- 3: Comparable
- 2: Non-treated product is better

1: Non-treated product is much better

TABLE 3

Test 2 Test 3 Test 4

Sensation 4.4 4.1 3.8
As is apparent from Table 3, as compared with the fiber products that had undergone no treatment, those treated with the fiber treatment agent composition of the present invention provide excellent sensation to touch by hands.

Example 4

The fiber treatment agent composition of the present invention can be incorporated in a softening agent composition and can be used for imparting softness to fiber products.



	Fiber treatment agent composition (Ex. 1)	10.0%
	QUARTAMIN D86P*¹⁾	3.0%
	EMULGEN 123P*²⁾	0.5%
	Ethylene glycol	1.5%
	Water	balance
	Total	100.0%

	*¹⁾Distearyl dimethyl ammonium chloride (product of Kao Corporation, effective ingredient 75%)
	*²⁾Polyoxyethylene (23) lauryl ether (product of Kao Corporation)

Example 5



	Fiber treatment agent composition (Ex. 2)	2.5%
	Perfume	q.s.
	Water	balance
	Total	100.0%

The resultant composition is placed in a spray container, followed by shaking well, and spraying onto fiber products uniformly.

Industrial Applicability

The fiber treated with the fiber treatment agent composition of the present invention provides excellent feeling to the resultant textile and pleasant feel to the skin. When a consumer wears the fiber product produced from the thus-treated fiber, remarkable effects are attained, including pleasant feel to the skin with which the fiber product is brought into contact, skin protective effect, effect of enabling the people having sensitive skin to wear at ease, moisturizing effect, and effect of improving skin disease such as rough skin.

Claims

1. A fiber treatment agent composition comprising an amphipathic lipid having hydroxyl group(s) and amide group(s) in the molecule thereof, said lipid being solid particles having an average particle size of 1 to 100 μm.

2. The fiber treatment agent composition as claimed in claim 1, wherein the amphipathic lipid is obtained through heating a mixture of the amphipathic lipid, a surfactant, and/or an aqueous medium to a temperature not less than the melting point of the amphipathic lipid, and a subsequent crystallization step.

3. The fiber treatment agent composition as claimed in claim 1 or 2, wherein the amphipathic lipid is represented by the following formula (1):

wherein R¹and R²are the same or different and each independently represents a linear or branched, saturated or unsaturated C₇-C₃₉hydrocarbon group which may be substituted by one or more hydroxyl groups; and R³and R⁴are the same or different and each independently represents a hydrogen atom, a phosphate salt residue, a sulfate salt residue, or a saccharide residue; provided that one or more hydroxyl groups are contained in one molecule of the derivative.

4. The fiber treatment agent composition as claimed in any one of claims 1 through 3, wherein the amphipathic lipid is contained in an amount of 0.005 to 40% by weight of the fiber treatment agent composition.

5. The fiber treatment agent composition as claimed in any one of claims 1 through 4, further comprising one or more species selected from the groups consisting of surfactants and aqueous medium.

6. A treated fiber obtained through bringing a fiber treatment agent composition as recited in any one of claims 1 through 5 into contact with fiber so as to cause the amphipathic lipid to be present continuously or discontinuously on the surface of the fiber.

7. A fiber to which an amphipathic lipid has been affixed, the amphipathic lipid having hydroxyl group(s) and amide group(s) in the molecule thereof and being solid particles having an average particle size of 1 to 100 μm.

8. A method of treating fiber, comprising bringing the fiber treatment agent composition as recited in any one of claims 1 through 5 into contact with fiber.

9. The method of treating fiber according to claim 8, wherein the fiber is treated through dipping in the fiber treatment agent composition.

10. The method of treating fiber according to claim 8, wherein the fiber is treated through spraying of the fiber treatment agent composition to the fiber.

11. The method of treating fiber according to any one of claims 8 through 10, wherein, when the fiber is brought into contact with the fiber treatment agent composition, at least one species selected from the following group is co-used: binders, softening agents, hardening agents, sewing facilitating agents, flame retardants, antistatic agents, soil repellents, antimicrobial/deodorizing agents, raising agents, slip-preventing agents, moisturizing agents, water repellants, water absorbers, fluorescent dyes, anti-shrinking agents, and fixing agents.

12. Use, in a fiber treatment agent composition, of an amphipathic lipid having hydroxyl group(s) and amide group(s) in the molecule of the lipid and being solid particles having an average particle size of 1 to 100 μm.