JP2003105627A - Polyester based porous hollow fiber and method of producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lightweight porous hollow fiber with good color development, excellent in a dry feeling, a bulkyness, etc., and to provide a fiber structure using the fibers. SOLUTION: This porous hollow fiber is obtained by removing fine particles of an inactive substance and a water-soluble thermoplastic polyvinyl alcohol based polymer from a conjugated fiber by treating a fiber structure including a sea-island type conjugated fiber comprising the thermoplastic polymer including the fine particles of the inactive substance as a sea component and the water-soluble thermoplastic polyvinyl alcohol based polymer as an island component.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester-based porous hollow fiber and a fiber structure containing the same. In detail, a random surface is formed on the fiber surface by a concavo-convex structure having a non-uniform size, and further, there are ultrafine concavities and convexities in the concavo-convex forming the random surface, and lightness
The present invention relates to a hollow fiber having an excellent feeling of dryness and swelling, and particularly to a porous polyester hollow fiber and a fiber structure thereof.

[0002]

2. Description of the Related Art Synthetic fibers such as polyester and polyamide are widely used not only for clothing but also for industrial purposes due to their excellent physical and chemical properties, and have industrially important value. There is. However, these synthetic fibers have a monotonous distribution of single yarn fineness, and have a relatively large single yarn fineness and a simple cross-sectional shape, so that they can be used as natural fibers such as silk, cotton, and hemp. Compared to the texture and luster. Further, the above synthetic fibers were cold, had a slimy feel, and were inferior in quality to natural fibers. Therefore, in order to improve the above-mentioned drawbacks of the synthetic fiber, it is widely practiced to make the cross-sectional shape of the synthetic fiber irregular or hollow the fiber.

Usually, the modified cross-section fiber or hollow fiber produced by using a modified spinning nozzle or a hollow spinning nozzle has a surface tension of a resin in a molten state after spinning and before solidification and a take-up tension during spinning. There is a problem that the deformed cross section is collapsed by such as, or the hollow portion is easily crushed, and especially when trying to develop a porous hollow shape, even if the fiber is provided with a porous hollow structure immediately after spinning, the porous hollow portion Was crushed and disappeared, or the ratio of the hollow portion was easily reduced, and it was substantially impossible to obtain a fiber having a porous hollow portion by such a method.

On the other hand, JP-A-7-316977 discloses that an alkali-decomposable polymer is used as an island component, and a sea component is a polyamide or an ethylene-vinyl alcohol copolymer having a water absorption rate of 3% or more. A technique has been proposed in which a polymer is used to form a composite fiber, and then the easily degradable polymer is treated with a hot alkaline aqueous solution to decompose and remove the polymer to form a porous hollow fiber. However, wastewater treatment of alkali decomposition products is complicated, and there is a big problem from the environmental aspect. Moreover, in such a method, since it is necessary for the alkaline aqueous solution to permeate the sea component of the composite fiber to extract the island component, it is necessary to use a polymer having a water absorbing property as the sea component. There are restrictions on the type, and it is also difficult to use polylactic acid and polyester, which are weak against alkali, in the sea component. It was virtually impossible to produce a porous hollow fiber having In addition, hollow fibers cannot obtain a deep color even if they are dyed, and in particular, a dyed product of porous hollow fibers cannot obtain a good deep color.

[0005]

The object of the present invention is to solve the above-mentioned problems of the prior art and to provide a hollow fiber having excellent lightness, dry feeling, swelling feeling, repulsion feeling, etc. To provide a fiber structure containing. Another object of the present invention is to provide a composite fiber for rationally producing such a hollow fiber without causing wastewater treatment and environmental problems, and further to provide a method for producing a hollow fiber using the composite fiber. That is.

[0006]

That is, according to the present invention, the number of hollow parts (α1) and the hollow ratio (α2) are expressed by the following formulas (1) to (1).
A polyester-based porous hollow fiber satisfying (3),
A polyester porous hollow fiber characterized in that an irregularly shaped primary uneven structure is formed on the entire surface of the fiber, and a finer secondary uneven structure is formed in the primary uneven structure. ≧ 5 (1) 3 ≦ α2 ≦ 65 (2) 0.15 ≦ α1 × α2 / 100 ≦ 350 (3) Further, in the present invention, the fine particle inert material having an average particle size of 100 mμm or less is 0.5 to 0.5. A composite fiber comprising 10% by weight of polyester as a sea component and a water-soluble thermoplastic polyvinyl alcohol polymer as an island component, wherein the number of islands (β1) and the area ratio of islands when viewed in a fiber cross section ( β2) is a sea-island type composite fiber characterized by satisfying the following formulas (4) to (6): β1 ≧ 5 (4) 3 ≦ β2 ≦ 65 (5) 0.15 ≦ β1 × β2 / 100 ≦ 350 (6) Furthermore, the present invention provides the above composite fiber. As it is, or after being made into a fiber structure containing the composite fiber, treated with water,
The water-soluble thermoplastic polyvinyl alcohol-based polymer of the composite fiber is dissolved and removed, and at the same time as or after the dissolution and removal, the composite fiber is treated with a solvent having solubility or decomposability with respect to polyester to give the above-mentioned unevenness on the polyester fiber surface. A porous hollow fiber or a fiber structure containing a porous hollow fiber is produced by forming a structure.

The term "fibrous structure" as used in the present invention means, of course, multifilament yarns, spun yarns, woven and knitted fabrics, non-woven fabrics, papers, artificial leathers and filling materials composed of the composite fibers or hollow fibers of the present invention. Thing, natural fiber, semi-synthetic fiber,
Mixed yarns and blended yarns with other synthetic fibers, processed yarns such as plied yarns, entangled yarns and crimped yarns, mixed woven fabrics, knitted fabrics, fiber laminates, and clothing, living materials, industrial materials composed of these ,
It also includes various final products such as medical supplies.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION On the surface of the porous hollow fiber of the present invention, an irregularly shaped primary uneven structure is formed, and a finer secondary uneven structure is formed within the primary uneven structure. is important. Since the fine secondary uneven structure is formed in a multi-layer structure with the primary uneven structure, the light incident on such an uneven portion is repeatedly scattered and re-scattered one after another around the surrounding of the uneven portion, and the reflected light is It is considered that the color is reduced and deep color is realized.

Regarding the unevenness of the fiber surface, generally a regular surface is a surface cut with a blade having a constant shape such as a turning surface, but the surface of the fiber of the present invention is irregular. Random concavo-convex structure having a shape is formed, and the surface has a surface polished with irregular shaped abrasive grains such as a ground or lapping surface, or a structure similar to the surface of a casting. The term "irregularly-shaped primary uneven structure" used in the present invention means
It means a surface in which convex parts with irregular peaks and concave parts with irregular valley depths coexist, but the convex peaks have almost the same height and the concave valleys have irregular depths. A regular surface or, conversely, a surface in which the valleys of the depressions have almost the same depth and the height of the peaks of the projections is irregular is also meant to be included as a random surface. In addition, the secondary uneven structure formed in the primary uneven structure,
Although the irregularities have different sizes, they are basically formed by irregular irregularities similar to the primary irregularity structure.

In the present invention, each unevenness forming the primary uneven structure has a plane distance X between the lowest point of a concave portion existing in the outer peripheral direction perpendicular to the fiber axis and the lowest point of an adjacent concave portion.
_When it is set to ₁ , it is preferable that 0.2 μm ≦ X ₁ ≦ 0.7 μm is satisfied, and the distance between the recesses is substantially unequal. Furthermore, the unevenness that forms the secondary uneven structure is
When the plane distance between the lowest points of the adjacent recesses is X ₂ ,
It is preferable that 0.05 μm ≦ X ₂ <0.2 μm is satisfied, and that the distances between the recesses are substantially unequal. When X ₁ is less than 0.2 μm, the specular reflectance is less likely to decrease, and the depth of color after dyeing may not be sufficient. On the other hand, when it exceeds 0.7 μm, the reflectance of visible light becomes high, and the color may become dull and whitish. Further, also in the secondary uneven structure, when the plane distance between the lowest points of the adjacent concave portions is X ₂ less than 0.05 μm, the canceling effect due to the phase difference of the incident light is small and the depth of color after dyeing is insufficient. On the other hand, when it exceeds 0.2 μm, the distinction from the primary concavo-convex structure becomes unclear, and the function as the secondary concavo-convex structure may not be fulfilled.

Further, in the present invention, it is necessary that irregularities having different sizes within the above range exist on the entire fiber surface, and such an irregular random surface is
It can be formed by treating the surface of a fiber made of polyester containing specific inert fine particles with a solvent as described later.

Further, in the hollow fiber of the present invention, it is important that the hollow fiber has a specific concavo-convex structure and that the number of hollow portions (α1) and the hollow ratio (α2)% satisfy the following formulas (1) to (3). Is. α1 ≧ 5 (1) 3 ≦ α2 ≦ 65 (2) 0.15 ≦ α1 × α2 / 100 ≦ 350 (3) The relationship between the number of hollow parts (α1) and the hollow ratio (α2)% is α1
With <5,3> α2, 0.15> α1 × α2 / 100, lightweightness, a bulging feeling and a sufficient repulsion feeling cannot be obtained. Also,
When α2> 65 and α1 × α2 / 100> 350, it is not suitable because it becomes difficult to fibrillate and there is a problem in practical use because the fiber strength is low. Therefore, preferably α1 ≧ 8,
5 ≦ α2 ≦ 50, 0.4 ≦ α1 × α2 / 100 ≦ 100
Is desired.

The hollow fiber of the present invention as described above is produced by dissolving and removing an island component from a specific sea-island type composite fiber. If the island component is composed of a polyester containing 0.5 to 10% by weight of a particulate inert material having a diameter of 100 mm or less, and the island component is composed of a water-soluble thermoplastic polyvinyl alcohol-based polymer, The form is not particularly limited.

The concavo-convex structure possessed by the hollow fiber of the present invention is formed by utilizing fine particles which are atomized to the fine structure order inside the fiber, and elute and erode the surface of the fiber to which the fine particles are added. When the water-soluble thermoplastic polyvinyl alcohol-based polymer of the island component is eluted, extremely fine and complicated irregular shapes are developed on the entire fiber surface. The added fine particles exist in a single particle state or a so-called secondary particle state in which the single particles are aggregated. This is because the chip before spinning and the fiber after spinning are larger than the diameter of the single particle-shaped fine particles present in the chip or the fiber and within a thickness of several times the particle diameter, that is, tens of millimeters to 1 micrometer.
It can be observed by slicing with an ultramicrotome to a thickness of around 00 millimicrons and enlarging the sliced ultrathin section with a transmission electron microscope at high magnification. As the fine particles to be added, for example, silica sol, fine particle silica, alumina sol, fine particle alumina, ultrafine particle titanium oxide,
Calcium carbonate sol, calcium carbonate in the form of fine particles, modified silica sol having improved dispersion stability, or colloid of other fine particulate inert material having a refractive index close to that of polyester fiber is used. As a result of examining the addition amount of the fine particles, when it is less than 0.5% by weight, the unevenness after elution of the surface layer becomes insufficient, and the effect of improving the color depth cannot be recognized. If the fine particles are added in an amount of more than 10% by weight, the fiber forming processability becomes poor and it is not suitable.

Further, in the conjugate fiber for forming the hollow fiber of the present invention, the shape of each individual island component is not limited at all, and may be circular, elliptical or other irregular shape. Furthermore, the island component may be continuous or discontinuous in the fiber axis direction.

Typical examples of the conjugate fiber of the present invention are shown in cross-sectional views, for example, those shown in FIGS. 1 to 4. The composite fiber of FIG. 1 has a form in which a small island component 2 made of a water-soluble thermoplastic polyvinyl alcohol polymer is surrounded by a sea component 1 made of a polyester polymer, and FIG. In, the shape of many smaller island components 2 is an irregular shape that is not circular. 3 and 4, the fiber cross section has a triangular cross section.

In the present invention, the composite ratio of the island component and the sea component is not particularly limited, but the composite ratio is appropriately selected depending on the number of hollow portions and the hollow ratio of the finally obtained hollow fiber. Can be changed. Preferably island: sea
= 2: 98 to 65:35, and further 5:95 to 60: 4
It is preferably 0. Further, the cross-sectional form of the composite fiber is not particularly limited, and in addition to the circular cross-section shown in FIGS. 1 and 2, for example, a flat shape, an elliptical shape, a triangular shape (FIGS. 3 and 4) to an octagonal shape, a T-shape, It may have any shape such as a multi-leaf shape such as a 3 to 8 leaf shape. Further, the conjugate fiber of the present invention may contain optional additives such as a fluorescent whitening agent, a stabilizer, a flame retardant and a colorant, if necessary.

Next, the water-soluble thermoplastic polyvinyl alcohol polymer (hereinafter sometimes simply referred to as PVA) used as the island component of the composite fiber of the present invention will be described. The PVA used in the present invention includes not only a homopolymer of polyvinyl alcohol but also, for example, copolymerized, terminal modified, and modified polyvinyl alcohol having a functional group introduced by a post reaction.

The PVA used in the present invention has a viscosity average degree of polymerization (hereinafter, simply referred to as a degree of polymerization) of preferably 200 to 500, more preferably 230 to 470, and even more preferably 250 to 4
50 is particularly preferred. If the degree of polymerization is less than 200, sufficient spinnability may not be obtained during spinning, and fiber formation may be difficult. If the degree of polymerization exceeds 500, the melt viscosity will be too high,
In some cases, the polymer cannot be discharged from the spinning nozzle. In addition, a so-called low polymerization degree PV having a polymerization degree of 500 or less
By using A, not only the dissolution rate can be increased when the composite fiber is dissolved in the aqueous solution, but also the shrinkage when the composite fiber is dissolved can be reduced.

The degree of polymerization (P) of PVA is JIS-K67.
It is measured according to 26. That is, it is obtained by the following formula from the intrinsic viscosity [η] (dl / g) measured in water at 30 ° C. after re-saponifying PVA and purifying it. P = ([η] × 10 ³ /8.29) ^{(1 / 0.62) When the} degree of polymerization is within the above range, the object of the present invention can be more suitably achieved.

The PVA used in the present invention has a saponification degree of 9
It is preferably from 0 to 99.99 mol%. More preferably 93 to 99.98 mol%, and further 94 to 99.9.
7 mol% is preferable, and 96 to 99.96 mol% is particularly preferable. If the degree of saponification is less than 90 mol%, the thermal stability of PVA may be poor, and satisfactory melt spinning may not be possible due to thermal decomposition or gelation, and the water solubility of PVA may decrease depending on the type of copolymerization monomer described below. There is a case. On the other hand, PVA having a saponification degree of more than 99.99 mol% tends to have low solubility and cannot be stably produced, which makes stable fiber formation difficult.

Further preferred PVA for use in the present invention
Indicates that the molar fraction of the central hydroxyl group of the three-chain hydroxyl group by triad display to the vinyl alcohol unit is 70-
It is preferably 99.9 mol%, has a melting point of 160 ° C. to 230 ° C., and contains 0.0003 to 1 part by mass of alkali metal ion in terms of sodium ion based on 100 parts by mass of PVA.

In the present invention, the central hydroxyl group of the 3-chain hydroxyl group represented by the triad representation of polyvinyl alcohol means a 500 MHz proton NMR (JEOL GX-500) apparatus in PVA d6-DMSO solution at 65 ° C.
It means a peak (I) reflecting the tacticity of triad of hydroxyl protons measured. Peak (I)
Is the sum of isotacticity chain (4.54 ppm), heterotacticity chain (4.36 ppm) and syndiotacticity chain (4.13 ppm) in the triad of hydroxyl groups of PVA, and all vinyl alcohol units are represented. Since the peak (II) of the hydroxyl group in 4) appears in the region of chemical shift of 4.05 ppm to 4.70 ppm, the molar fraction of the central hydroxyl group of the 3-chain hydroxyl group by the triad display with respect to the vinyl alcohol unit of the present invention is 100 × (I ) / (II).

Hydroxyl group 3 by PVA triad display
When the content of the central hydroxyl group in the chain is less than 70 mol%, the crystallinity of the polymer is lowered and the fiber strength is lowered, and at the same time, the fibers are stuck to each other during melt spinning and unwinding after winding may occur. is there. Further, the water-soluble thermoplastic fiber intended by the present invention may not be obtained. When the content of the central hydroxyl group of the hydroxyl group 3 chain according to the triad representation of PVA is larger than 99.9 mol%, the melting point of the polymer is high, so that the melt spinning temperature needs to be increased. As a result,
The thermal stability of the polymer during melt spinning is poor, causing decomposition, gelation,
Polymer coloring is likely to occur.

Further, the PVA of the present invention is ethylene-modified P
In the case of VA, the effect of the present invention is further enhanced by satisfying the following formula. -1.5 × Et + 100 ≧ mol fraction ≧≧ -Et + 85 Here, the mole fraction (unit: mol%) represents the mole fraction of the central hydroxyl group of the hydroxyl group 3 chain by the triad notation to the vinyl alcohol unit, and Et is It represents the ethylene content (unit: mol%) contained in the vinyl alcohol polymer.

Therefore, the content of the central hydroxyl group of the 3-chain hydroxyl group by the triad display of PVA used in the present invention is more preferably 72 to 99 mol%, and 74 to 97 mol%.
Is more preferable, and 76 to 95 mol% is particularly preferable.

By controlling the amount of the central hydroxyl group of the 3-chain hydroxyl group of polyvinyl alcohol used in the present invention, various physical properties related to water such as water solubility and hygroscopicity of PVA, strength, elongation, elastic modulus, etc. It is possible to control various physical properties related to melt spinning properties such as melting point, melt viscosity and the like. It is considered that this is because the central hydroxyl group of the triad hydroxyl group 3 chain is rich in crystallinity and expresses the features of PVA.

Melting point (Tm) of PVA used in the present invention
Is preferably 160 to 230 ° C., 170 to 2
27 degreeC is more preferable, 175-224 degreeC is further more preferable, 180-220 degreeC is especially preferable. Melting point 160
When the temperature is lower than 0 ° C, the crystallinity of PVA is lowered, the fiber strength of the conjugate fiber is lowered, and at the same time, the thermal stability of the conjugate fiber is deteriorated, and the fiber cannot be formed. On the other hand, the melting point is 2
If it exceeds 30 ° C., the melt spinning temperature becomes high, and the spinning temperature and the decomposition temperature of PVA are close to each other, so that the sea-island type composite fiber composed of PVA and polyester may not be stably produced. The melting point of PVA was measured by using DSC in nitrogen after heating up to 250 ° C. at a heating rate of 10 ° C./min.
It means the temperature at the peak top of the endothermic peak showing the melting point of PVA when cooled to room temperature and heated again to the temperature rising rate of 10 ° C./250° C.

The PVA used in the present invention is obtained by saponifying a vinyl ester unit of a vinyl ester polymer. As the vinyl compound monomer for forming the vinyl ester unit, vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and Examples thereof include vinyl versatate, and of these, vinyl acetate is preferable from the viewpoint of obtaining PVA.

The PVA used in the present invention may be a homopolymer or a modified PVA in which a copolymerized unit is introduced, but from the viewpoint of melt spinning property, water solubility and fiber physical properties, the copolymerization is performed. It is preferable to use a modified polyvinyl alcohol in which a unit is introduced. Examples of the type of copolymerizable monomer include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, and n-acrylic acid. Acrylic esters such as propyl and i-propyl acrylate, methacrylic acid and salts thereof, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate and i-propyl methacrylate, acrylamide, N- Acrylamide derivatives such as methyl acrylamide and N-ethyl acrylamide, methacrylamide derivatives such as methacrylamide, N-methyl methacrylamide, N-ethyl methacrylamide, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl Vinyl ether, vinyl ethers such as n- butyl ether, ethylene glycol vinyl ether, 1,3
-Hydroxy group-containing vinyl ethers such as propanediol vinyl ether and 1,4-butanediol vinyl ether, allyl ethers such as allyl acetate, propyl allyl ether, butyl allyl ether, and hexyl allyl ether; monomers having an oxyalkylene group; Vinylsilyls such as vinyltrimethoxysilane, isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decene-1. -Ol, 3-methyl-3-buten-1-ol and other hydroxy group-containing α-olefins, fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride or itaconic anhydride A monomer having a carboxyl group derived from Nsuruhon acid, allylsulfonic acid, methallyl sulfonic acid, 2-acrylamido-2
Monomers having a sulfonic acid group derived from methylpropanesulfonic acid; vinyloxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamidomethyltrimethylammonium chloride, Examples include monomers having a cationic group derived from N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine and the like. The content of these monomers is usually 20 mol% or less.

Among these monomers, α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, Vinyl ethers such as i-propyl vinyl ether and n-butyl vinyl ether, hydroxy group-containing vinyl ethers such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether and 1,4-butanediol vinyl ether, allyl acetate, propyl allyl ether, butyl Allyl ether,
Allyl ethers such as hexyl allyl ether, monomers having an oxyalkylene group, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, Monomers derived from hydroxy group-containing α-olefins such as 9-decen-1-ol and 3-methyl-3-buten-1-ol are preferred.

In particular, ethylene, propylene, 1-butene, from the viewpoint of copolymerizability, melt spinnability and water solubility of fibers,
More preferred are α-olefins having 4 or less carbon atoms of isobutene, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether. The unit derived from α-olefins and / or vinyl ethers having 4 or less carbon atoms is 0.1 to 0.1% in PVA.
20 mol% is preferably present, more preferably 1 to 20 mol%, further preferably 4 to 15 mol%,
6 to 13 mol% is particularly preferable. Further, when the α-olefin is ethylene, the physical properties of the fiber become high, so it is preferable to use a modified PVA in which an ethylene unit is introduced in an amount of 4 to 15 mol%, more preferably 6 to 13 mol%.

Examples of PVA used in the present invention include known methods such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method and an emulsion polymerization method. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is carried out without solvent or in a solvent such as alcohol is usually adopted. Examples of the alcohol used as the solvent during the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol and propyl alcohol. As the initiator used for the copolymerization, α, α′-azobisisobutyronitrile, 2,2′-azobis (2,2
4-dimethyl-valeronitrile), benzoyl peroxide,
Known initiators such as azo-based initiators such as n-propyl peroxycarbonate or peroxide-based initiators may be mentioned. The polymerization temperature is not particularly limited, but is 0 ° C to 1
A range of 50 ° C is suitable.

The content ratio of the alkali metal ion in the PVA used in the present invention is preferably 0.0003 to 1 part by mass, and 0.0003 to 0.8 part by mass in terms of sodium ion based on 100 parts by mass of PVA. A part is more preferable, 0.0005 to 0.6 part by mass is further preferable, and 0.0005 to 0.5 part by mass is particularly preferable. When the content ratio of the alkali metal ion is less than 0.0003 parts by mass, sufficient water solubility may not be exhibited and undissolved matter may remain. Further, when the content of alkali metal ions is more than 1 part by mass, decomposition and gelation during melt spinning may be remarkable and fiber formation may not be possible. Examples of alkali metal ions include potassium ion and sodium ion.

In the present invention, the method of incorporating a specific amount of alkali metal ions into PVA is not particularly limited, and P
A method of adding an alkali metal ion-containing compound after polymerizing VA, and when saponifying a vinyl ester polymer in a solvent, by using an alkaline substance containing an alkali ion as a saponification catalyst, an alkali metal ion is added to PVA. PVA obtained by blending and saponifying
Examples of the method include controlling the content of alkali metal ions contained in PVA by washing the above with a washing liquid, but the latter is preferable. The content of alkali metal ions can be determined by the atomic absorption method.

Examples of the alkaline substance used as the saponification catalyst include potassium hydroxide and sodium hydroxide. The molar ratio of the alkaline substance used in the saponification catalyst is preferably 0.004 to 0.5, and particularly preferably 0.005 to 0.05, based on the vinyl acetate unit. The saponification catalyst may be added all at once at the beginning of the saponification reaction, or may be additionally added during the saponification reaction. As the solvent for the saponification reaction, methanol, methyl acetate, dimethyl sulfoxide,
Examples include dimethylformamide. Among these solvents, methanol is preferable, and the water content is 0.001 to
Methanol controlled to 1 mass% is more preferable, methanol whose water content is controlled to 0.003 to 0.9 mass% is more preferable, and methanol whose water content is controlled to 0.005 to 0.8 mass% is particularly preferable. . Examples of the washing liquid include methanol, acetone, methyl acetate, ethyl acetate, hexane, water and the like, and among these, methanol, methyl acetate, water alone or a mixed liquid is more preferable. The amount of the cleaning liquid is set so as to satisfy the content ratio of the alkali metal ions, but normally 300 to 10,000 parts by mass is preferable with respect to 100 parts by mass of PVA, and 500.
〜5000 parts by mass is more preferred. As the cleaning temperature,
5-80 degreeC is preferable and 20-70 degreeC is more preferable.
The washing time is preferably 20 minutes to 10 hours, more preferably 1 hour to 6 hours.

Further, in the present invention, P as described above is used.
Even if VA is used, PVA is generally inferior in melt fluidity at high temperature as compared with a general-purpose thermoplastic resin, and therefore, if necessary, polyethylene glycol, propylene glycol and its oligomer, butylene glycol and its Oligomer, polyglycerin derivative, glycerin derivative in which alkylene oxide such as ethylene oxide and propylene oxide is added to glycerin, derivative in which alkylene oxide such as ethylene oxide and propylene oxide is added to sorbitol, polyhydric alcohol such as pentaerythritol and its derivative , PO /
It is preferable to add a plasticizer such as an EO random copolymer to PVA at a ratio of 1 to 30% by mass, preferably 2 to 20% by mass, from the viewpoint of improving the spinnability. Then, in order to obtain good plasticization and spinnability, thermal decomposition hardly occurs in the fiberizing step, in order to obtain an alkylene oxide adduct of sorbitol,
Polyglycerin alkyl monocarboxylic acid ester, PO
It is preferable to add 1 to 30% by mass, preferably 2 to 20% by mass of a plasticizer such as / EO random copolymer, and particularly 1 to 30% of sorbitol ethylene oxide.
Compounds with a mole addition are preferred.

The polyester constituting the sea component of the sea-island type composite fiber of the present invention is not particularly limited, and examples thereof include aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polypropylene terephthalate, polylactic acid, polyethylene. Examples thereof include aliphatic polyester such as adipate, polyarylate, and polycarbonate. Further, these polymers may be copolymerized. In particular,
Copolymerization with isophthalic acid, 5-sodium sulfoisophthalic acid, sebacic acid, adipic acid or the like is a preferred direction from the viewpoint of easy removal of the island component PVA. Further, an additive may be contained in the thermoplastic polymer constituting the sea component.

The composite fiber of the present invention is a PVA as described above.
Is an island component, and is not particularly limited as long as it is a spinning technology capable of forming a cross-sectional morphology using a polyester as a sea component, and in a system of a combination of a polyester that does not gel with a PVA that reacts with the island component during heat melting. For example, a method using mixed spinning is possible, in which PVA as an island component and a thermoplastic polymer as a sea component are melt-kneaded by one extruder, and subsequently discharged from the same spinning nozzle and wound to form a fiber. Can be converted. In the method using composite spinning, PVA and polyester are melted and kneaded by different extruders, respectively, and then PVA becomes an island component and polyester becomes a sea component and is discharged from a sea-island type composite spinning nozzle and wound. , Can be made into fibers.

The fiberizing conditions need to be set according to the combination of polymers and the cross-sectional shape of the composite, but it is desirable to determine the fiberizing conditions mainly in consideration of the following points. (1) Generally, PVA is a polymer that is inferior in melt fluidity at high temperature and self-crosslinks in the presence of a retention part and easily gels. Therefore, as much as possible, an extrusion zone of a polymer and a jet pack (assembly of composite spinning parts) It is important to make it difficult for the retention part to occur in the polymer fluidized part inside the body. (2) The spinneret temperature is Mp to Mp + 80, where Mp is the melting point of the polymer having the highest melting point among the polymers constituting the composite fiber.
℃ is preferable, shear rate (γ) 1,000 to 25,000 sec ^-1 ,
It is preferable to carry out spinning with a draft V10 to 500. (3) From the viewpoint of the combination of the polymers to be composited, it is possible to improve the spinning stability by combining the polymers whose melt viscosities are close to each other when measured by the spinneret temperature during spinning and the shear rate when passing through the nozzle. It is preferable from the aspect.

The melting point Tm of PVA in the present invention is the peak temperature of the main endothermic peak observed with a differential scanning calorimeter (DSC: TA3000 manufactured by Mettler). The shear rate (γ) is calculated by γ = 4Q / πr ³ when the nozzle radius is r (cm) and the polymer discharge amount per single hole is Q (cm ³ / sec). Further, the draft V is calculated by V = 5A · πr ² / 3Q when the take-up speed is A (m / min).

In producing the conjugate fiber of the present invention, if the spinneret temperature is lower than the melting point Tm of PVA, the PV
A cannot be spun because A does not melt. On the other hand, when the temperature exceeds Tm + 80 ° C., PVA is apt to cause thermal decomposition or gelation due to self-crosslinking, resulting in deterioration of spinnability. If the shear rate is lower than 1,000 sec ^-1 , thread breakage will occur easily,
If it is higher than 00 sec ^-1, the back pressure of the nozzle becomes high and the spinnability deteriorates. When the draft is lower than 10, the fineness unevenness becomes large and it becomes difficult to spin stably, and when the draft is higher than 500, the yarn is easily broken.

The yarn discharged from the spinning nozzle is wound at a high speed as it is without being stretched or is stretched if necessary.
Stretching is performed at a temperature equal to or higher than the glass transition point (Tg) at a breaking elongation (HDmax) × 0.55 to 0.9 times. Draw ratio is HD
If it is less than max × 0.55, a composite fiber having sufficient strength cannot be obtained stably, and if it exceeds HDmax × 0.9, yarn breakage tends to occur. Stretching may be carried out after being once wound after being discharged from the spinning nozzle, or may be carried out subsequent to the stretching. In the present invention, either may be adopted. Stretching is usually hot stretching and may be performed using any of hot air, hot plate, hot roller, water bath and the like. In the drawing step, the larger the absolute value of the draw ratio, the more easily fluffing and fiber breakage occur. Therefore, it is preferable to use the high-speed spinning to low-draw ratio fiberization conditions or the known high-speed spinning / winding only method.

The stretching temperature is appropriately set according to the composite polymer of the composite, but since the polyvinyl alcohol used in the present invention has a high crystallization rate, the unstretched yarn is considerably crystallized, and the plastic part of the crystal part is around Tg. Does not easily deform. Therefore, for example, in the case of composite with PET, even when contact heating drawing such as hot roller drawing is performed, drawing is performed at a relatively high temperature (about 70 to 100 ° C.) as a guide. In addition, when heat drawing is performed using a non-contact type heater such as a heating furnace or a heating tube, the temperature is further increased to 150
It is preferable to set the temperature condition to about 200 ° C.

However, in the present invention, as fiberizing conditions, the spinneret temperature is Tm to Tm + 80 ° C., the shear rate (γ) is 1,000 to 25,000 sec ⁻¹ , and the draft is
(V) It is important to spin at 10 to 500.

Further, the cross-sectional shape of the composite fiber in the present invention is not particularly limited, and it may be a perfect circle shape, a hollow shape or an atypical cross section depending on the shape of the spinning nozzle. A perfect circle is preferable from the viewpoint of process passability in fiberizing and weaving.

The composite fiber of the present invention can control the shrinkage behavior of the composite fiber when the PVA, which is an island component, is dissolved in water, depending on the production conditions. When it is desired to keep the value low, it is desirable to subject the composite fiber to a heat treatment.
This heat treatment may be carried out at the same time as the drawing in the fiberizing step involving drawing, or may be carried out separately from the drawing. When the heat treatment temperature is increased, the maximum shrinkage ratio of the hollow fiber obtained by dissolving the island component PVA can be lowered, but conversely, the dissolution temperature of the island component PVA in water tends to be high. It is desirable to set the heat treatment conditions while looking at the balance with the maximum shrinkage ratio in the processing step of, and generally, the glass transition point of the island component PVA ~
It is preferable to set the conditions within the range of (Tm-10) ° C.

When the treatment temperature is lower than Tg, a sufficiently crystallized composite fiber cannot be obtained, and, for example, when the fabric is heat set, the shrinkage becomes large, and the texture of the fabric hardens, which is not preferable. . The processing temperature is (Tm-
When the temperature exceeds 10 ° C., the fibers are agglomerated, which is not preferable.

The heat treatment may be performed by adding shrinkage to the stretched composite fiber. PV in water when shrinkage is added to the composite fiber
The shrinkage rate of the composite fiber until A dissolution is small. The applied shrinkage is preferably 0.01 to 5%, more preferably 0.1 to 0.5%, and particularly preferably 1 to 4%. The applied contraction is 0.
If it is less than 01%, the effect of reducing the maximum shrinkage ratio of the composite fiber when PVA is dissolved is not substantially obtained, and if the added shrinkage exceeds 5%, the composite fiber sags during the shrinking treatment and becomes stable. Cannot add shrinkage.

In the present invention, the fact that PVA is “water-soluble” means that it dissolves at a temperature of 40 ° C. or higher, regardless of the length of time until dissolution. Then, by changing the type of PVA and the manufacturing conditions of the composite fiber, the melting temperature of the PVA island component in the present invention is 30 ° C to
Although it is possible to obtain a conjugate fiber having a temperature of 100 ° C., in order to balance all properties of practicality and water solubility,
It is preferable to use a composite fiber composed of a PVA island component having a melting temperature of 40 ° C. or higher.

The melting treatment temperature may be appropriately adjusted according to the melting temperature of PVA and the glass transition point of the polyester constituting the sea component of the composite fiber in the Wet state. Of course, the higher the treatment temperature, the shorter the treatment time. . When it is dissolved using hot water, if the glass transition point of the thermoplastic polymer serving as the sea component is 70 ° C. or higher, hot water treatment under high temperature and high pressure of 100 ° C. or higher is most preferable. Although soft water is usually used as the aqueous solution, it may be an alkaline aqueous solution, an acidic aqueous solution, or may contain a surfactant and the like. In particular, when an alkaline aqueous solution is used, it is possible to dissolve and remove the PVA component and simultaneously form an uneven structure on the fiber surface. However, it is difficult to perform the treatment so as to simultaneously satisfy the formation of the hollow portion and the formation of the desired concavo-convex structure unless the balance between the treatment conditions for dissolution and removal and the treatment conditions for the concavo-convex formation is taken into consideration. is there.

When the composite fiber of the present invention is treated with hot water to dissolve and remove the PVA component, a nonionic surfactant,
A scouring agent containing an anionic surfactant or the like as a component and other additives may be included. The dissolution and removal of PVA by the hot water treatment may be performed on the composite fiber alone, or may be performed after the fiber structure containing the composite fiber is formed. The temperature and the treatment time during the hot water treatment include various factors such as the fineness of the composite fiber, the ratio of the island component in the composite fiber, the distribution state of the island component, the ratio of the thermoplastic polymer of the sea component, the type, and the morphology of the fiber structure. It can be adjusted appropriately according to the requirements of. The hot water treatment temperature is 60 ° C or higher, preferably 80 ° C or higher. As a method of hot water treatment,
Examples thereof include a method of immersing the composite fiber and the fiber structure in a hot water solution, and a method of applying a hot water solution to them by a method such as a pad or spray.

In the present invention, PVA is removed from the composite fiber as an aqueous solution by the hot water treatment as described above.
Such PVA has biodegradability and is decomposed into water and carbon dioxide when treated with activated sludge or buried in soil. Further, the PVA dissolved and removed is in the state of an aqueous solution,
Continuous treatment with activated sludge almost completely decomposes within 2 days to 1 month. From the viewpoint of biodegradability, the saponification degree of the fiber is 90 to 9
9.99 mol% is preferable, 92-99.98 mol% is more preferable, 93-99.97 mol% is especially preferable. The 1,2-glycol bond content of the fiber is 1.
0 to 3.0 mol% is preferable, 1.2 to 2.5 mol% is more preferable, and 1.3 to 1.9 mol% is particularly preferable.
When the 1,2-glycol bond amount of PVA is less than 1.0 mol%, not only the biodegradability of PVA deteriorates, but also the melt viscosity is too high and the spinnability of the conjugate fiber deteriorates. is there. When the 1,2-glycol bond content of PVA is 3.0 mol% or more, the thermal stability of PVA may deteriorate and the spinnability may decrease.

In the present invention, PVA in the composite fiber is selectively removed by hot water treatment to produce a hollow fiber made of polyester having 5 or more hollow portions. The greatest feature is that the PVA island component, which is completely surrounded by the sea component composed of hydrophobic polyester which is considered to hardly swell in water, is beautifully dissolved and removed by hot water treatment to form a hollow fiber. That is. When the composite fiber has a cut surface such as a staple fiber, it is considered that the PVA will come out from the end surface of the fiber, but in the present invention, even in the state of a long fiber having substantially no cut surface. It is not an exaggeration to say that PVA is neatly dissolved and removed, and that this fact overturns the conventional wisdom. In particular, it is difficult to obtain a polyester fiber having a porous hollow structure, a foaming agent, or a very special method, but by using the conjugate fiber of the present invention, it is extremely rational and practical. It is possible to manufacture. Also, the island component P
Since VA is excellent in hygroscopicity and moisture retention, it is possible to apply this property to partially dissolve and remove PVA depending on the purpose (use) to form voids and at the same time leave the island component PVA.

The hollow fiber of the present invention has a hollow structure and at the same time has a specific uneven structure on the fiber surface.
Means for forming the uneven structure on the fiber surface is, for example,
Examples thereof include alkali treatment with caustic soda and the like, but are not limited thereto. However, it is preferable to select a common solvent for the polyester constituting the fiber and the added inert fine particles. Furthermore, it is preferable to use a common solvent which has a dissolution rate or decomposition rate of fine particles in a common solvent several times to several tens of times higher than that of polyester, because irregularities on the fiber surface can be more minutely complicated. In this respect, when the fine particles added are silica and the solvent is caustic soda, the dissolution rate of silica is 10 times or more faster than that of polyester, which is extremely desirable. In addition, the treatment conditions for forming the unevenness are as follows: when treating with an aqueous solution of caustic soda, the concentration of caustic soda is 2 to 8 mass.
%, The treatment temperature is 90 to 98 ° C., and the treatment is preferably performed so that the weight loss rate is 2 to 8%.

The hollow fiber of the present invention thus obtained is particularly taffeta, decin, georgette, crepe, because of its lightness, flexibility, opacity and swelling feeling.
It is suitable for woven fabrics such as textured yarns and twills, or knitted fabrics such as jersey, smooth and tricot. Furthermore, it can be used not only for clothing, but also for non-woven fabrics, medical applications, sanitary materials, and various living materials such as stuffing materials. It can also be used as an interior material for automobiles, a sound deadening material, and a vibration isolator as a fiber laminate. It is also possible to make paper.

[0057]

EXAMPLES The present invention will now be specifically described with reference to Examples.
The present invention is not limited to these examples. The parts and% in the examples relate to mass unless otherwise specified.

[PVA Analysis Method] PVA analysis method was in accordance with JIS-K6726 unless otherwise specified. The modification amount is 500 MHz proton NMR (JEOL GX-5) using modified polyvinyl ester or modified PVA.
00) Determined by measurement with a device. The content of alkali metal ions was determined by the atomic absorption method.

The 1,2-glycol bond content was measured by the method described above. The ratio of the amount of hydroxyl groups of 3 chains by the triad display of PVA of the present invention was determined by the following measurement. After saponifying PVA to a saponification degree of 99.5 mol% or more, it was sufficiently washed with methanol, and then dried at 90 ° C. under reduced pressure for 2 days, and then dissolved in d6-DMSO.
500 MHz Proton NMR (JEOL GX-50
0) 65 degreeC measurement was performed with the apparatus. The peak derived from the hydroxyl group of the vinyl alcohol unit in PVA appears in the region of chemical shift from 4.05 ppm to 4.70 ppm,
This integrated value is the vinyl alcohol unit amount (II). The central hydroxyl group of the 3-chain hydroxyl group according to the triad representation of PVA is 4.5 ppm for the isotacticity chain and 4.3 for the heterotacticity chain, respectively.
It appears at 6 ppm and 4.13 ppm for the syndiotacticity chain. The sum of the integrated values of the three is the amount of the central hydroxyl group (I) of the three-chain hydroxyl group by the triad display.
And The mole fraction of the central hydroxyl group of the 3-chain hydroxyl group in the triad notation with respect to the vinyl alcohol unit of the PVA of the present invention is represented by 100 × (I) / (II).

[Melting Point] The melting point of PVA was determined by using DSC (TA3000, manufactured by METTLER CORPORATION) in nitrogen and at a heating rate of 10
PVA when the temperature was raised to 250 ° C. at a rate of 10 ° C./min, cooled to room temperature, and then raised to 250 ° C. at a rate of 10 ° C./min again.
The temperature at the peak top of the endothermic peak indicating the melting point of

[Removal rate of PVA in hot water] Regarding the conjugate fiber of the present invention, when the melting temperature of PVA constituting the conjugate fiber in hot water is Tα (° C), (Tα + 40) ° C The mass reduction rate after treatment with hot water for 40 minutes, water washing for 5 minutes, and drying was taken as the PVA removal rate. It should be noted that Tα can be obtained, for example, as a temperature when a load of 2.2 mg / decitex is applied to the fiber made of the PVA alone, the fiber is hung in water, the water temperature is raised, and the fiber is cut.

[Measurement of hollow area ratio] SEM photographs of the cross section of the hollow fiber yarn were taken, and the area was calculated from the porous hollow area and the whole hollow fiber area in the cross section.

[Evaluation of Feeling (Lightness, Feeling)] The fabric was evaluated by 10 panelists and evaluated according to the following criteria. ◎: 9 or more people judged that the feeling of lightness, softness and swelling was excellent ○: 7-8 people judged that the feeling of lightness, softness and swelling were excellent △: 5-6 people feeling light , Judged to be excellent in both softness and bulge x: judged to be inferior in lightness, softness and bulge for 6 or more people

[Production of ethylene-modified PVA] 29.0 kg of vinyl acetate and 31.0 kg of methanol were charged into a 100-liter pressure reactor equipped with a stirrer, a nitrogen inlet, an ethylene inlet and an initiator inlet, and the temperature was raised to 60 ° C. After heating 3
The system was replaced with nitrogen by bubbling nitrogen for 0 minutes. Next, ethylene was introduced and charged so that the reactor pressure became 5.9 kg / cm ² (5.8 × 10 ⁵ Pa). 2, as an initiator
A 2.8 g / L solution of 2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol was prepared, and bubbling with nitrogen gas was performed to substitute nitrogen. After adjusting the temperature inside the polymerization tank to 60 ° C., 170 ml of the above initiator solution was injected to start polymerization. During the polymerization, ethylene was introduced to make the reactor pressure 5.9 kg / cm ² (5.8 × 10 ⁵ Pa) and the polymerization temperature 60 ° C.
Maintained at 610 ml / hr using the above initiator solution.
Then, AMV was continuously added to carry out polymerization. After 10 hours, the polymerization was stopped by cooling when the polymerization rate reached 70%. After removing the ethylene by opening the reaction tank, nitrogen gas was bubbled to completely remove the ethylene. Then, the unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. To 200 g of a methanol solution of polyvinyl acetate adjusted to have a concentration of 50% by adding methanol to the obtained polyvinyl acetate solution (100 g of polyvinyl acetate in the solution), 46.5 g (in polyvinyl acetate) was added. Molar ratio (MR) to vinyl acetate unit
Saponification was carried out by adding an alkaline solution of 0.10) (10% methanol solution of NaOH). About 2 after adding alkali
The gelled system was crushed with a crusher in minutes, and allowed to stand at 60 ° C. for 1 hour to allow saponification to proceed.
0 g was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration, and the mixture was left standing and washed at room temperature for 3 hours. After the above washing operation was repeated 3 times, the PVA obtained by centrifugal deliquoring was allowed to stand in a dryer at 70 ° C. for 2 days to obtain dried PVA. The degree of saponification of the obtained ethylene-modified PVA was 98.4 mol%.
The content of sodium measured by an atomic absorption spectrophotometer using the solution of the modified PVA dissolved in an acid after ashing was 0.01 parts by mass with respect to 100 parts by mass of the modified PVA. In addition, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer after polymerization is n-
Precipitation in hexane and reprecipitation by dissolving in acetone were repeated three times, and then dried under reduced pressure at 80 ° C. for 3 days to obtain purified polyvinyl acetate. The polyvinyl acetate was dissolved in DMSO-d6 and subjected to 500 MHz proton NMR (JEOL GX-
The content of ethylene was 8.4 mol% when measured at 80 ° C. using 500). The above methanol solution of polyvinyl acetate was saponified at an alkali molar ratio of 0.5, and the pulverized product was allowed to stand at 60 ° C. for 5 hours to proceed with saponification, followed by methanol soxhlet for 3 days, and then at 80 ° C. The product was dried under reduced pressure for 3 days to obtain a purified ethylene-modified PVA. The average degree of polymerization of the PVA was measured by the conventional method J
It was 330 when measured according to IS K6726. The 1,2-glycol bond content of the purified PVA and the content of hydroxyl groups in the 3-chain hydroxyl group were adjusted to 500 MHz proton N.
It was 1.50 mol% and 83%, respectively, when determined as described above from the measurement by the MR (JEOL GX-500) apparatus. Furthermore, 5 of the purified modified PVA
% Aqueous solution was prepared to form a cast film having a thickness of 10 μm. After the film was dried under reduced pressure at 80 ° C. for 1 day, the melting point of PVA was 208 ° C. as measured by the above-mentioned method using DSC (Mettler, TA3000).

Example 1 Using the modified PVA obtained above as an island component, 0.045 mass% of titanium oxide and 6 mol% of isophthalic acid modified polyethylene terephthalate ([η] = 0.68, hereinafter IPA)
6Abbreviated as PET) as a sea component,
The maximum temperature of the zone is 230 ° C., and the unspun yarn is spun at 83 ° C. after spinning at a spinning temperature of 260 ° C. and a spinning speed of 1800 m / min using a composite spinning component in which melt retention of PVA does not occur as much as possible.
This was contacted with a heat roller of No. 1 and a heat plate of 140 ° C., and drawn at a draw ratio of 2.3 times to obtain 83 dtex / 24f composite fiber having a fiber cross section and a composite ratio as shown in Table 1.

Then, a plain woven fabric was prepared by using the composite fiber as a warp and a weft. The machine density is 95/25.
It was 4 mm and weft 86 threads / 25.4 mm. 80 in an aqueous solution containing the greige fabric at a rate of 2 g / l sodium carbonate
After immersing at 37 ° C for 30 minutes to desizing, presetting was performed at 170 ° C for about 40 seconds. Next, hot water treatment was performed with an aqueous solution containing 1 g / liter of Intol MT Conc (anion activator, manufactured by Meisei Chemical Co., Ltd.) at a bath ratio of 50: 1, a temperature of 120 ° C., and a time of 40 minutes. Furthermore, caustic soda 40 g / liter, bath ratio 1:
Alkali weight loss treatment was carried out by immersing in 30 aqueous alkali solution of 95 ° C. for 40 minutes. After that, stain under the following conditions,
A dry finishing set was carried out by a conventional method. As a result, a plain woven fabric having the PVA removal rate and the hollow area rate shown in Table 1 was obtained. Table 2 shows various evaluation results of the woven fabric including a feeling of lightness.

[0067]   Dyeing method Dye: Dianix Red BN-SE (CI Disperse Red127) 5% owf             Dispersion aid; Disper TL (manufactured by Meisei Chemical Co., Ltd.) 1 g / liter             pH adjusting agent; ammonium sulfate 1 g / liter                         Acetic acid (48%) 1 g / liter             Bath ratio; 1:30 1g / l             Temperature: 120 ℃ x 60 minutes 1g / l   Reduction cleaning Hydrosulfide 1g / l               Amylazine (Daiichi Kogyo Seiyaku) 1 g / liter               NaOH 1g / l               Bath ratio; 1:30               Temperature; 80 ℃ x 20 minutes

[0068]

[Table 1]

[0069]

[Table 2]

From the results shown in Table 2 above, the woven fabric made of the porous hollow fibers defined by the present invention has an extremely light feeling,
It had an excellent soft and swelling texture.

Examples 2 to 5 Fiber formation was carried out in the same manner as in Example 1 except that the type and the particle size of the fine particles added to the sea component were as shown in Table 1.
Fabrication and evaluation were performed. All the fabrics were excellent in lightweight feeling, soft and swelling, and had an excellent texture.

Examples 6 to 7 As in Example 1, except that the fiber cross section, the number of islands, the composite ratio, the island component removal ratio, etc. were changed, fiberization, woven fabric preparation, and evaluation were carried out. It was All the fabrics were excellent in lightweight feeling, soft and swelling, and had an excellent texture.

Examples 8 to 11 As shown in Table 1, fiberization, woven fabric preparation and evaluation were performed in the same manner as in Example 1 except that the modified species and modified amount of the island component were changed. All the fabrics were excellent in lightweight feeling, soft and swelling, and had an excellent texture.

Examples 12 to 16 As shown in Table 1, as in Example 1, except that the type of the sea component polymer, the fiber cross section, the number of islands, the composite ratio, the island component removal ratio, etc. were changed, the fiberized and woven fabric was obtained. Was created and evaluated. All the fabrics were excellent in lightweight feeling, soft and swelling, and had an excellent texture.

[Brief description of drawings]

FIG. 1 is a fiber cross-sectional view showing an example of a cross-sectional shape of a conjugate fiber of the present invention.

FIG. 2 is a fiber cross-sectional view showing an example of the cross-sectional shape of the conjugate fiber of the present invention.

FIG. 3 is a fiber cross-sectional view showing an example of the cross-sectional shape of the conjugate fiber of the present invention.

FIG. 4 is a fiber cross-sectional view showing an example of the cross-sectional shape of the conjugate fiber of the present invention.

[Explanation of symbols]

1: Sea component 2: Island component

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) D06M 11/05 D06M 101: 32 // D06M 101: 32 5/22 (72) Inventor Ki Yamakawa 1621 Sakazu, Kurashiki, Okayama Prefecture Address Kuraray Co., Ltd. (72) Inventor Masao Kawamoto 1621 Sakata, Kurashiki-shi, Okayama F-Term inside Kuraray Co., Ltd. (reference) 4L031 AA18 BA08 CA06 CA16 CA17 CA00 DA00 4L035 BB31 DD03 DD07 DD20 FF07 4L041 BA04 BA05 BA11 BA17 BA41 BA43 BA57 BC01 BD12 CA05 CA41 DD11 EE14 EE15

Claims (10)

[Claims] 1. A polyester-based porous hollow fiber in which the number of hollow parts (α1) and the hollow ratio (α2) satisfy the following formulas (1) to (3), and the entire surface of the fiber has an irregular shape. A polyester porous hollow fiber, wherein a primary uneven structure is formed, and a finer secondary uneven structure is formed in the primary uneven structure. α1 ≧ 5 (1) 3 ≦ α2 ≦ 65 (2) 0.15 ≦ α1 × α2 / 100 ≦ 350 (3) 2. Each of the concavities and convexities forming the primary concavo-convex structure has a plane distance between the lowest point of a concave portion existing in the outer peripheral direction perpendicular to the fiber axis and the lowest point of an adjacent concave portion as X ₁ .
The unevenness that satisfies 0.2 μm ≦ X ₁ ≦ 0.7 μm and is formed at substantially non-uniform intervals and that forms the secondary uneven structure has the plane distance between the lowest points of the adjacent recesses as X ₂ . At this time, the polyester porous hollow fiber according to claim 1, wherein 0.05 μm ≦ X ₂ <0.2 μm is satisfied and the polyester porous hollow fibers are formed at substantially unequal intervals. 3. The polyester is polylactic acid.
Alternatively, the porous hollow fiber according to item 2. 4. A composite fiber comprising a polyester containing 0.5 to 10% by weight of a particulate inert material having an average particle diameter of 100 mμm or less as a sea component and a water-soluble thermoplastic polyvinyl alcohol polymer as an island component. The sea-island type composite fiber characterized in that the number of island portions (β1) and the island area ratio (β2) when viewed in the fiber cross section satisfy the following expressions (4) to (6). β1 ≧ 5 (4) 3 ≦ β2 ≦ 65 (5) 0.15 ≦ β1 × β2 / 100 ≦ 350 (6) 5. The sea-island type according to claim 4, wherein the water-soluble thermoplastic polyvinyl alcohol is a modified polyvinyl alcohol containing 0.1 to 20 mol% of an α-olefin unit having 4 or less carbon atoms and / or a vinyl ether unit. Composite fiber. 6. The sea-island type composite fiber according to claim 5, which contains 4 to 15 mol% of ethylene units and / or propylene units as α-olefin units. 7. The polyester is polylactic acid as claimed in claim 4.
7. The sea-island type composite fiber according to any one of items 6 to 6. 8. A fiber structure comprising at least a part of the porous hollow fiber according to any one of claims 1 to 3. 9. The sea-island type composite fiber according to claim 4 is treated with water to dissolve and remove at least a part of the water-soluble thermoplastic polyvinyl alcohol polymer from the composite fiber. Alternatively, the method for producing a polyester porous hollow fiber is characterized in that after removal by dissolution, it is treated with a solvent having solubility or decomposability of polyester to form the concavo-convex structure of claim 1 on the fiber surface. 10. The fiber structure according to claim 8 is treated with water to simultaneously dissolve and remove at least a part of the water-soluble thermoplastic polyvinyl alcohol polymer from the sea-island type composite fiber constituting the fiber structure. Or after dissolving and removing, treated with a solvent having solubility or degradability of polyester,
A method for treating a fiber structure, comprising forming the uneven structure according to claim 1 on the surface of a polyester fiber.