JP2003293224A - Highly hygroscopic/water-absorbing polyvinyl alcohol copolymer conjugate fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly hygroscopic/water-absorbing polyvinyl alcohol copolymer conjugate fiber exhibiting high swelling on being wetted with water. <P>SOLUTION: The conjugate fiber is made up of A-component consisting of a fiber-forming polymer ≥150°C in melting point and B-component consisting of a water-soluble and thermoplastic polyvinyl alcohol 200-500 in viscosity- average polymerization degree, 90-99.99 mol% in saponification degree, 70-99.9 mol% in the molar fraction of the central hydroxy groups in hydroxyl triple chains in terms of triad based on vinyl alcohol units, and 160-230°C in melting point containing 0.0003-1 pt.wt. of alkali metal ions on a sodium basis. The B-component contains 3-45 wt.% of a polyamide resin. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conjugate fiber containing a polyvinyl alcohol polymer having high hygroscopicity and water absorption as one component.

[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, since these synthetic fibers have low hygroscopicity and water absorption, their use has been limited to applications requiring hygroscopicity and water absorption such as underwear, inner garments, sheets, and towels.

As a method of imparting hygroscopicity or water absorption to synthetic fibers, for example, a method of post-treating polyester fiber with a hydrophilic treatment agent, or imparting hygroscopicity or water absorption by making the surface or inside of polyester fiber porous Methods for doing so have been proposed. However, these methods do not sufficiently improve the hygroscopicity and water absorption of the synthetic fiber, and in the case of the fiber to which hydrophilicity is imparted by the post-treatment, the hygroscopicity and water absorbing ability imparted by repeated washing decrease. There was a drawback to do. As a method of improving such a defect, it has been proposed in recent years to graft-polymerize a monomer such as acrylic acid or methacrylic acid on a polyester fiber, but it has not yet reached a practical level. This is because polyester mainly has a rigid structure, does not have a reactive functional group and is hydrophobic, so that the graft polymerization of the above-mentioned monomers is difficult to be carried out, and the texture when forcedly graft-polymerized. This is because the fiber becomes hard and the strength of the fiber is reduced.

On the other hand, as a fiber having excellent hydrophilicity, a wet type,
Although polyvinyl alcohol fibers produced by a dry method or a dry-wet spinning method or the like are known, conventional polyvinyl alcohol fibers are formed into formal in order to improve the heat resistance, or the oriented crystallization is progressing by stretching. Since it is treated, it has a problem that water absorbency is not sufficiently developed, and in order to solve such a problem, a method of crosslinking the low-stretched yarn under mild conditions is also proposed. (Japanese Patent Laid-Open No. 7-189023). However, the obtained liquid absorption rate is at most about 130%, and when manufacturing by the wet spinning method, equipment for collecting various solvents used in the spinning step is required,
It is undeniable that there are many restrictions such as difficulty in high-speed spinning as compared with the melt spinning method, and difficulty in making a fiber cross section into a complex irregular cross section with a large degree of irregularity.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned conventional problems and to provide a highly hygroscopic and highly water-absorbent polyvinyl alcohol system which exhibits a high swelling property when moistened with water. It is to provide a composite fiber having a polymer as one component by a melt spinning method.

[0006]

[Means for Solving the Problems] Component A comprising a fiber-forming polymer having a melting point of 150 ° C. or higher and a viscosity average degree of polymerization of 2
00 to 500, the saponification degree is 90 to 99.99 mol%, and the mole fraction of the central hydroxyl group of the three hydroxyl groups in the triad display with respect to the vinyl alcohol unit is 70 to 99.
B component consisting of polyvinyl alcohol having 9 mol% and a melting point of 160 ° C. to 230 ° C., and water-soluble thermoplastic polyvinyl alcohol containing 0.0003 to 1 part by weight of alkali metal ion in terms of sodium. Which is nylon 6 / 6,6,
3% by weight of at least one polyamide resin selected from the group consisting of nylon-6 / 12 and nylon-6
The present invention relates to an ethylene vinyl alcohol-based copolymer fiber having high hygroscopicity and water absorption, which is a composite fiber containing 45% by weight, and a fiber product such as a yarn and a cloth, and a method for producing them. More specifically, it is a method for producing a fiber product such as the above-mentioned fibers, yarns, and cloths, which have high hygroscopicity and high water-absorption property and exhibit high swelling property when wetted with water.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described. Not only a homopolymer of polyvinyl alcohol but also a modified polyvinyl alcohol having a functional group introduced by copolymerization, terminal modification, and post-reaction are included.

The PVA used in the present invention has a viscosity average degree of polymerization (hereinafter, simply referred to as a degree of polymerization) of 200 to 500, preferably 230 to 470, and more preferably 250 to 450. If the degree of polymerization is less than 200, sufficient spinnability cannot be obtained during spinning, and fibers cannot be formed. Polymerization degree is 500
If it exceeds, the melt viscosity is too high and the polymer cannot be discharged from the spinning nozzle. Further, by using PVA having a polymerization degree of 500 or less, that is, a so-called low polymerization degree, not only the dissolution rate becomes faster when the fibers are dissolved in the aqueous solution, but also the shrinkage rate when the fibers are dissolved can be made smaller.

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 in the above range, the object of the present invention can be more suitably achieved.

The degree of saponification of the PVA of the present invention is 90 to 99.9.
Must be 9 mol%. 93 to 99.98 mol%
Is preferable, 94 to 99.97 mol% is more preferable,
96 to 99.96 mol% is particularly preferable. Saponification degree is 90
When it is less than mol%, not only is the thermal stability of PVA poor and it is not possible to perform satisfactory melt spinning due to thermal decomposition or gelation, but also the water solubility of PVA decreases depending on the type of copolymerization monomer described below. In some cases, the fiber of the present invention cannot be obtained. On the other hand, PVA having a saponification degree of more than 99.99 mol% cannot be stably produced, and stable fiberization cannot be achieved.

In the present invention, the central hydroxyl group of the three-chain hydroxyl group represented by triad is the d6-DMS of PVA.
500MHz Proton NMR in O solution (JEOL G
X-500) apparatus, peak (I) reflecting the tacticity of triad of hydroxyl proton measured at 65 ° C
Means The peak (I) is an isotacticity chain (4.54 pp) of the triad display of the hydroxyl group of PVA.
m), the heterotacticity chain (4.36 ppm) and the syndiotacticity chain (4.13 ppm), and the peak (II) of the hydroxyl group in all vinyl alcohol units has a chemical shift of 4.05 pp.
Since it appears in the region of m · 4.70 ppm, the mole fraction of the central hydroxyl group of the hydroxyl group 3 chain by the triad display with respect to the vinyl alcohol unit of the present invention is 100 ×
It is represented by (I) / (II).

In the present invention, by controlling the amount of central hydroxyl groups of the three-chain hydroxyl group, various physical properties related to water such as water solubility and hygroscopicity of PVA, various physical properties related to fiber such as strength, elongation and elastic modulus, Various physical properties related to melt spinnability such as melting point and melt viscosity can be controlled. This is the central hydroxyl group of the 3-chain hydroxyl group according to the triad display, which is rich in crystallinity.
It seems that this is to express the features of.

In the fiber of the present invention, the content of the central hydroxyl group of the 3-chain hydroxyl group according to the triad notation of PVA is 70.
˜99.9 mol%, preferably 72 to 99 mol%, more preferably 74 to 97 mol%, further preferably 75 to 96 mol%, and particularly preferably 76 to 95 mol%. When the content of the central hydroxyl group of the hydroxyl group 3 chain by PVA triad is less than 70 mol%, the crystallinity of the polymer is lowered and the fiber strength is lowered, and at the same time, the fiber is stuck and wound during melt spinning. You may not be able to unwind later. In addition, the target fiber in 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 display of PVA is higher than 99.9 mol%, the melting point of the polymer is high, so that it is necessary to raise the melt spinning temperature. The thermal stability of the polymer is poor, causing decomposition, gelation, and coloring of the polymer.

When the PVA of the present invention is ethylene-modified PVA, 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 three-chain hydroxyl group by triad display with respect to the vinyl alcohol unit, and Et is vinyl alcohol. Content of ethylene in unit copolymers (unit: mol%)
Represents

Melting point (Tm) of PVA used in the present invention
Is 160 to 230 ° C., 170 to 227 ° C. is preferable, 175 to 224 ° C. is more preferable, and 180 to 220
C is especially preferred. PV when the melting point is less than 160 ° C
At the same time as the crystallinity of A decreases and the fiber strength decreases, PV
In some cases, the thermal stability of A deteriorates and the fiber cannot be formed.
On the other hand, if the melting point exceeds 230 ° C, the melt spinning temperature becomes high and the spinning temperature and the decomposition temperature of PVA come close to each other, so that the target fiber cannot be stably produced.

The melting point of PVA was raised to 250 ° C. in nitrogen using DSC at a heating rate of 10 ° C./minute, then cooled to room temperature, and again heated to 250 ° C. at a heating rate of 10 ° C./minute. It means the temperature of the peak top of the endothermic peak showing the melting point of PVA in the case.

PVA is obtained by saponifying vinyl ester units. 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,
Examples thereof include vinyl benzoate, vinyl pivalate, vinyl versatate, and the like. Among these, vinyl acetate is preferable from the viewpoint of obtaining PVA.

The PVA constituting the fiber of the present invention may be a homopolymer of polyvinyl alcohol or a modified PVA having a copolymerized unit introduced, but from the viewpoint of melt spinning property, water solubility and fiber physical properties. It is preferable to use a modified polyvinyl alcohol having a copolymerized unit introduced therein. Examples of the type of copolymerizable monomer include α-olefins such as ethylene, propylene, 1-butene, isobutene and 1-hexane, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, n-acrylic acid. Acrylic esters such as propyl and i-propyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-methacrylic acid
Methacrylic acid esters such as propyl, acrylamide, acrylamide derivatives such as N-methylacrylamide, N-ethylacrylamide, methacrylamide, N
-Methyl methacrylamide derivatives such as methyl methacrylamide and N-ethyl methacrylamide, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether, ethylene glycol vinyl ether, 1,3-propane Hydroxy group-containing vinyl ethers such as diol 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, vinyl tris Vinylsilyls such as methoxysilane, isopropenyl acetate, 3-butene-1
-Ol, 4-penten-1-ol, 5-hexene-
1-ol, 7-octen-1-ol, 9-decene-
Hydroxy group-containing α-olefins such as 1-ol and 3-methyl-3-buten-1-ol, fumaric acid, maleic acid, itaconic acid, maleic anhydride, phthalic anhydride, trimellitic anhydride or itacone anhydride Monomers having carboxylic acid groups derived from acids, etc .; Monomers having sulfonic acid groups derived from ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, etc .; Roxyethyltrimethylammonium chloride, vinyloxybutyltrimethylammonium chloride, vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-
Examples include monomers having a cationic group derived from acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, acryltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine and the like. . The content of these monomers is usually 20 mol% or less, more preferably 10 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, vinyl ethers containing hydroxy group 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.

Particularly, from the viewpoint of copolymerizability and melt spinning property, α-olefins having 4 or less carbon atoms such as ethylene, propylene, 1-butene and isobutene, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i
Vinyl ethers such as -propyl vinyl ether and n-butyl vinyl ether are more preferable. The units derived from α-olefins and / or vinyl ethers having 4 or less carbon atoms are preferably present in PVA in an amount of 0.1 to 20 mol%, more preferably 4 to 15 mol%, and 6 to 13 Mol% is particularly preferred. 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 the 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'-
Known azo initiators such as azobisisobutyronitrile, 2,2'-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, and n-propylperoxycarbonate, or peroxide initiators Initiators are listed. The polymerization temperature is not particularly limited, but is 0
A range of ℃ to 150 ℃ is suitable.

The content of the alkali metal ion in PVA in the fiber of the present invention is 0.0003 to 1 part by weight in terms of sodium ion, preferably 0.0003 to 0.8 part by weight, based on 100 parts by weight of PVA. , 0.00
05-0.6 weight part is more preferable, 0.0005-
0.5 parts by weight is particularly preferred. When the content ratio of the alkali metal ion is less than 0.0003 parts by weight, the obtained fiber may not show sufficient water solubility. On the other hand, when the content of alkali metal ions is more than 1 part by weight, decomposition and gelation at the time of melt spinning are remarkable, and fibers cannot be formed. As the alkali metal ion, potassium ion,
Examples include sodium ions.

In the present invention, the method for 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, diethyl sulfoxide,
Examples include dimethylformamide. Among these solvents, methanol is preferable, and the water content is 0.001 to
Methanol whose water content is controlled to 0.003 to 0.9% by weight is more preferable, and methanol whose water content is controlled to 0.005 to 0.8% by weight is particularly preferable. . Examples of the washing liquid include methanol, acetone, methyl acetate, acetic acid ester, hexane, water and the like, and among them, 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, it is preferably 300 to 10,000 parts by weight, and 500 to 100 parts by weight of PVA.
˜5000 parts by weight 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.

If necessary, a stabilizer such as a copper compound, a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a flame retardant, etc. may be used as long as the objects and effects of the present invention are not impaired.
A plasticizer, a lubricant and a crystallization rate retarder can be added during the polymerization reaction or in the subsequent step. In particular, the addition of organic stabilizers such as hindered phenols, copper halide compounds such as copper iodide, and alkali metal halide compounds such as potassium iodide as heat stabilizers improves melt retention stability during fiber formation. Therefore, it is preferable.

The PVA used in the present invention preferably contains a plasticizer for melt spinning without problems such as gelation. The plasticizer is a compound obtained by adding 1 to 30 mol of ethylene oxide to 1 mol of sorbitol, and is preferably contained in PVA in an amount of 1 to 30% by weight.

If necessary, the average particle size is 0.01 μm.
Fine particles of m or more and 5 μm or less can be added in an amount of 0.05% by weight or more and 10% by weight or less during the polymerization reaction or in the subsequent step. The type of fine particles is not particularly limited, and for example, inert fine particles such as silica, alumina, titanium oxide, calcium carbonate and barium sulfate may be added, and these may be used alone or in combination of two or more kinds. . In particular, inorganic fine particles having an average particle diameter of 0.02 μm or more and 1 μm or less are preferable, and spinnability and stretchability are improved. The use of the PVA described above is an important requirement of the present invention.

In the present invention, the fiber (X) is nylon-
A polymer having a hydroxyl group containing a predetermined amount of at least one polyamide resin selected from the group consisting of 6/6, 6, nylon-6 / 12, and nylon-6 may be fiberized alone. However, it may be spun with a composite or a mixture with other thermoplastic polymer depending on the purpose. As such another thermoplastic polymer, a crystalline thermoplastic polymer having a melting point of 150 ° C. or higher is preferable from the viewpoint of heat resistance, dimensional stability and the like, and for example, polyester,
Examples thereof include polyamide and polypropylene.
As polyester, terephthalic acid, isophthalic acid,
Naphthalene-2,6-dicarboxylic acid, phthalic acid, α, β
Aromatic dicarboxylic acids such as-(4-carboxyphenoxy) ethane, 4,4'-dicarboxydiphenyl, 5-sodium sulfoisophthalic acid or their esters, ethylene glycol, diethylene glycol, 1,
A polyester synthesized from a diol such as 4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, polyethylene glycol, polytetramethylene glycol or an ester-forming derivative thereof, Polyester such as polylactic acid can be mentioned.
A polyester having 0% or more of ethylene terephthalate units or butylene terephthalate units is preferable.
Further, such polyester may contain a small amount of additives, optical brighteners, stabilizers, and ultraviolet absorbers.

As the polyamide, nylon 4, nylon 6, nylon 7, nylon 11, nylon 12, nylon 66, nylon 6,10, polymetaxylene adipamide, polyparaxylene decanamide polybiscyclohexylmethane decanamide and those Examples thereof include aliphatic polyamides and semi-aromatic polyamides. Nylon 6 and polyamide containing nylon 6 as a main component are preferable. Alternatively, a polyamide containing a small amount of the third component may be used. The polyamide may contain a small amount of additives, optical brighteners, stabilizers, ultraviolet absorbers and the like.

Other crystalline thermoplastic polymers include polyolefin resins such as polyethylene, polypropylene and polymethylpentene, acrylic acid resins, vinyl acetate resins,
Diene resin, polyurethane resin, polycarbonate resin, polyarylate, polyphenylene sulfide,
Examples include polyether ester ketone, fluororesin, and semi-aromatic polyester amide. Further, within a range that does not impair the effects of the present invention, titanium oxide, silica, inorganic substances such as barium oxide, carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers, various additives such as light stabilizers. May be included.

Further, the composite ratio of the polymer having a hydroxyl group and the other thermoplastic polymer in the case of forming the composite fiber is the former: the latter (mass ratio) = 10: 90 to 90:10,
It is preferable in terms of spinnability. In addition, the composite form of the composite fiber obtained by spinning is not limited at all, and examples thereof include a sheath and core type and a sea-island type (sea) type.
/ Iland or matrix), side by side (side by side), split type (strip)
There is no particular limitation as long as it is a conventionally known composite form such as e), and the cross-sectional shape is not limited at all. For example, in addition to round cross-sections, modified cross-sections (eg hollow, flat, elliptical, polygonal 3 to 14 leaves, T-shape, H-shape, V-shape, dog-bone shape (I-shape, etc.) may be used. The hygroscopicity of the hydroxyl group-containing polymer, in order to develop water absorption, at least a part of the surface of the composite fiber,
Preferably, the polymer is present on 30% or more of the surface.

In the present invention, in order to introduce a cross-linking structure into the fiber made of the above-mentioned polymer having a hydroxyl group, nylon-6 / 6,6, nylon-6 / 12 and nylon-6 are used in the polymer. It is important that at least one polyamide resin selected from the group consisting of 3 to 45% by weight is contained.

As the resin (D) blended with PVA and effective in high hygroscopicity and water absorption, a polyamide resin is selected. For example, polycaprolamide (nylon-
6), poly-ω-aminoheptanoic acid (nylon-7),
Polyundecanamide (nylon-11), polylaurinlactam (nylon-12), polyethylenediamineadipamide (nylon-2,6) polytetramethyleneadipamide (nylon-4,6), polyhexamethyleneadipamide (Nylon-6,6), polyhexamethylene sebacamide (nylon-2,10), polyhexamethylene dodecamide (nylon-6,12), polyoctamethylene adipamide (nylon-8,6), poly Decanomethylene adipamide (nylon-10,6), polydodecamethylene sebacamide (nylon-10,8), or caprolactam / laurinlactam copolymer (nylon-
6/12), caprolactam / ω-aminononanoic acid copolymer (nylon-6 / 9), caprolactam / hexamethylene adipate copolymer (nylon-6 / 6,6),
Laurin lactam / hexamethylene diamine adipate copolymer (nylon-12 / 6,6), hexamethylene diamine adipate / hexamethylene diamine sebacate copolymer (nylon-6,6 / 6,10), ethylene diamine adipate / hexamethylene Diamine adipate copolymer (nylon-2,6 / 6,6), caprolactam / hexamethylenediamine adipate / hexamethylenediamine sebacate copolymer (nylon-6,6 /
6, 10) and the like.

Among these polyamides, nylon-6 / 6,6 and nylon-6 / 12 are most preferable for the present invention. Nylon-6 / 12
There are no particular restrictions on the composition of the 6 and 12 components in 1.
Two components 60 mol% or less, more preferably 50 mol
% Or less is preferable.

Polyamides having a polyether bond in the polymer chain may be prepared by adding polyether diamines and dicarboxylic acids (such as dimer acid) during the condensation polymerization of these polyamides, especially nylon-6 / 12. It is also preferable to add an aliphatic amine such as hexamethylenediamine or laurylamine or an aromatic amine such as metaxylenediamine or methylbenzylamine at the time of condensation to reduce the number of carboxyl end groups in the polyamide. Also, a metaxylylene group-containing polyamide resin is effective, and a mixed xylylenediamine containing metaxylylenediamine and 80% or less of the total amount of paraxylylenediamine, and an α, ω-aliphatic dicarboxylic acid having 6 to 10 carbon atoms. It is a polymer containing at least 70 mol% in the molecular chain of a constituent unit formed from an acid. Examples of these polymers include homopolymers such as polymeta-xylylene adipamide, polymeta-xylylene sebacamide, poly-meta-xylylene speramide, and meta-xylylene / para-xylylene adipamide copolymers, meta-xylylene. / Copolymers such as para-xylylene azamide copolymer, etc.,
And components of these homopolymers or copolymers with aliphatic diamines such as hexamethylenediamine, alicyclic diamines such as piperazine, aliphatic diamines such as para-bis- (2-aminoethyl) benzene, and terephthalic acid. Aliphatic dicarboxylic acids such as, lactams such as ε-caprolactam, ω-such as γ-aminoheptanoic acid
Examples thereof include a copolymer obtained by copolymerizing an aminocarboxylic acid and an aromatic aminocarboxylic acid such as para-aminomethylbenzoic acid. In the above copolymer, the content of para-xylylenediamine is 80% or less, preferably 75% or less, based on the total xylylenediamine. Further, the constituent unit formed from xylylenediamine and the aliphatic dicarboxylic acid is at least 70 mol% or more, preferably 75 mol% or more in the molecular chain. Further, these polymers include, for example, nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, nylon 6-
Polymers such as 12 and the like, antistatic agents, lubricants, antiblocking agents, stabilizers, dyes, pigments and the like may be contained.

Furthermore, amorphous polyamide, that is, DS
In C measurement, a polycondensate of an aliphatic diamine and an aromatic dicarboxylic acid, which has substantially no endothermic crystal melting peak, is mainly used. Examples of the aliphatic diamine include hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 2-methylpentamethylenediamine, and bis- (4-aminohexyl) -methane. ,
2,2-bis- (4-aminohexyl) -isopropyridine, 1,4- (1,3) -diaminocyclohexane,
1,5-diaminopentane, 1,4-diaminobutane,
1,3-diaminopropane, 2-ethyldiaminobutane and the like can be mentioned. One or more of these diamines can be used at the same time. Above all,
Hexamethylenediamine, 2-methylpentanemethylenediamine, 1,5-diaminopentane, 1,4-diaminobutane, and 1,3-diaminopropane are preferably used. Examples of the aromatic dicarboxylic acid include isophthalic acid, terephthalic acid, alkyl-substituted isophthalic acid, alkyl-substituted terephthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid and the like. One or more of these dicarboxylic acids can be used at the same time. Of these, isophthalic acid, terephthalic acid, naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid and the like are preferable in terms of thermoformability. And, as an example of the amorphous polyamide,
Hexamethylenediamine-isophthalic acid polycondensate,
Hexamethylenediamine-isophthalic acid / terephthalic acid polycondensate, 2,2,4-trimethylhexamethylenediamine and 2,4,4-trimethylhexamethylenediamine-terephthalic acid polycondensate, and the like can be mentioned. Among them, the molar ratio of isophthalic acid / terephthalic acid is 60/40 to 95/5, and further 65/35 to 90.
Hexamethylenediamine-isophthalic acid / terephthalic acid polycondensates in the range of / 10 are preferred.

The above resin (D) may be used alone or in combination of two or more. Among the above resin (D), preferred polyamide resins include nylon 6, nylon 6-12, nylon containing metaxylylenediamine, and Crystalline nylon and the like. The mixing ratio of (C) and (D) is PVA (C) 55
97% by weight and resin (D) 45 to 3% by weight, preferably PVA (C) 60 to 95% by weight, resin (D) 40
~ 5% by weight. In the present invention, it is important to use (C) and (D) together, and if any of them is omitted, the object of the present invention cannot be achieved.

Further, in the dispersed form of the polyamide resin in the component B of the composite fiber (X), the polyamide resin component has an island shape, and the size of the island is 5 nm to 1000 n.
It is important that m and the number of islands are 10/10 μm ² or more. If the size of the island exceeds 1000 nm, the processability of fiber formation becomes unstable, and if it is less than 5 nm, the hygroscopicity and water absorption which are the objects of the present invention cannot be obtained, which is unsuitable. Even when the number of islands is 10 / or less than 10 μm ² , the hygroscopicity and water absorption which are the objects of the present invention cannot be obtained, which is not suitable.

The insolubility of the component B of the present invention thus obtained is importantly 1% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more. When the insolubility is less than 1% by weight, the hygroscopicity and water absorption which are the objects of the present invention cannot be obtained.

In order to produce the conjugate fiber of the present invention, long fibers and short fibers can be produced using conventionally known spinning and drawing apparatuses and methods. As the component A, a molten polymer such as polyethylene, polypropylene, nylon or polyester is used, or a blend of these may be used. Polyvinyl alcohol copolymer has 260
Since it begins to decompose when it stays at a temperature of ℃ or more for a long time, it is necessary to keep the spinning head temperature at 260 to 300 ° C when performing composite spinning with a high melting point polymer such as polyester. However, since the zone temperature from the extruder to the head is different, it can be carried out at the proper temperature for each polymer. It is necessary to keep this in mind when compounding with a high-viscosity polymer such as high-polymerization degree polypropylene. In this respect, nylon is suitable as the component A polymer. The composite form can be a parallel type or a core-sheath type, and the composite ratio of the A component and the B component can be changed. That is, for applications where the characteristics of the polyvinyl alcohol component are desired to be utilized more, the polyvinyl alcohol component is increased, and conversely, for applications where the surface characteristics of the polyvinyl alcohol component are utilized by utilizing the characteristics of the hydrophobic component, the core-sheath type is used. It is possible to manufacture a product having a low polyvinyl alcohol component ratio. Also,
The shape of each composite form may be a multi-layer parallel type or a multi-core type. The stretching may be normal dry heat stretching or wet heat stretching, and appropriate conditions may be selected so that the component A can be stretched at a temperature at which the polyvinyl alcohol component used does not stick. It is also possible to use a mixture of a polyvinyl alcohol component and another polymer as the B component,
Those that reduce the properties of polyvinyl alcohol are not preferred for the purposes of the present invention. In addition, foaming agent, antifouling agent,
It may be effective to add an additional function by adding a repellent or the like.

[0041]

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In addition, the measured value in an Example is measured by the following method.

[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.

[Ratio of Three Chain Hydroxyl Groups by Triad Display of PVA] PVA was saponified to a saponification degree of 99.5 mol% or more, thoroughly washed with methanol, and then dried under reduced pressure at 90 ° C. for 2 days. , D6-DMSO, and then 500 MHz proton NMR (JEOL
GX-500) device was used to measure 65 ° C. PVA
The peak derived from the hydroxyl group of the vinyl alcohol unit therein appears in the region of chemical shift from 4.05 ppm to 4.70 ppm, and the integrated value is defined as the amount of vinyl alcohol unit (II). The central hydroxyl group of the hydroxyl group 3 chain by the triad representation of PVA appears at 4.54 ppm for the isotacticity chain, 4.36 ppm for the heterotacticity chain, and 4.13 ppm for the syndiotacticity chain. The sum of the three integrated values is defined as the central hydroxyl group amount (I) of the hydroxyl group 3 chain in the triad display. The mole fraction of the central hydroxyl group of the three-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

[Evaluation of fiberizing processability] The following evaluation was made depending on how many times the 100 kg of fiber was cut during spinning. ○: within 3 times / 100 kg △: 4 to 7 times / 100 kg ×: 8 times or more / 100 kg

[Fiber Strength] The fiber strength was measured according to JIS-L1013.

[Dispersion state of islands, number of islands] Observation was performed using a transmission electron microscope.

[Insolubility] The content of the sheath component is calculated by examining the cross section of the fiber. Then, 0.3 g of the fiber sample is added to DMS.
It is a value obtained by adding 50 ml of O solvent, heating and dissolving at 60 ° C. for 2 hours, and obtaining the weight of the sample before and after the treatment.

[Moisture absorption rate] The cloth was kept at 60 ° C. for about 7 hours at 0.1%.
After drying under reduced pressure suction of mmHg, it was taken out and its weight (M1) (g) was measured. Immediately thereafter, the cloth was placed under a saturated aqueous solution of sodium nitrite at a temperature of 2
It was allowed to stand in an atmosphere of 0 ° C. and a humidity of 65% for 1 week, its weight (M2) (g) was measured, and the moisture absorption rate was calculated from the following formula. Moisture absorption rate (%) = {(M2-M1) / M1} × 100

[Water absorption rate] The water absorption rate was measured according to the JIS-L-1096 method.

Example 1 [Production of ethylene-modified PVA] 29.0 kg of vinyl acetate and 3 parts of methanol were placed in a 100-liter pressure reactor equipped with a stirrer, a nitrogen inlet, an ethylene inlet and an initiator addition port.
1.0 kg was charged, the temperature was raised to 60 ° C., and then the system was replaced with nitrogen by nitrogen bubbling for 30 minutes. Then, ethylene was introduced and charged so that the reactor pressure became 5.9 kg / cm 2. 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) as an initiator was dissolved in methanol to prepare a 2.8 g / L concentration solution,
Bubbling with nitrogen gas was performed to replace 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 maintain the reactor pressure at 5.9 kg / cm @ 2 and the polymerization temperature at 60.degree.
Polymerization was carried out by continuously adding AMV at ml / hr. 1
After 0 hour, 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. 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
(Polyvinyl acetate molar ratio (MR) to vinyl acetate unit (MR) 0.10) alkaline solution (10% of NaOH
Methanol solution) was added to perform saponification. After about 2 minutes from the addition of alkali, the system gelled and crushed with a crusher,
After allowing to stand at 60 ° C. for 1 hour to proceed with saponification, 1000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of neutralization using a phenolphthalein indicator, 1000 g of methanol was added to white solid PVA obtained by filtration and the mixture was left standing and washed at room temperature for 3 hours. PV obtained by centrifugal deliquoring after repeating the above washing operation three times
A was left in a dryer at 70 ° C. for 2 days to obtain dry PVA.

The degree of saponification of the obtained ethylene-modified PVA is 9
It was 8.4 mol%. The content of sodium measured by an atomic absorption spectrophotometer after ashing the modified PVA and dissolving it in an acid was 0.03 part by weight based on 100 parts by weight of the modified PVA. Further, a methanol solution of polyvinyl acetate obtained by removing unreacted vinyl acetate monomer after polymerization is precipitated in n-hexane and dissolved by acetone. After re-precipitation purification is performed 3 times, it is dried under reduced pressure at 80 ° C. for 3 days. Then, purified polyvinyl acetate was obtained. The polyvinyl acetate was dissolved in DMSO-d6 to obtain 500 MHz proton N
When measured by MR (JEOLGX-500) at 80 ° C., the ethylene content was 10 mol%. 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 330 when measured according to the conventional method JISK6726. The purified PVA had a 1,2-glycol bond content and a hydroxyl group content of 3 hydroxyl groups of 5,000.
It was 1.50 mol% and 83%, respectively, when determined as described above from the measurement by a MHz proton NMR (JEOL GX-500) apparatus. Further, a 5% aqueous solution of the purified modified PVA was prepared to prepare a cast film having a thickness of 10 μm. The film at 80 ° C
After vacuum drying for 1 day, DSC (Mettler,
TA3000) was used to measure the melting point of PVA by the above-mentioned method and found to be 206 ° C. (Table 1).

Next, a blending ratio of 10% by weight of nylon 6 to the obtained ethylene-modified PVA and nylon-6 was set to a composite ratio of 1: 1, a polyvinyl alcohol copolymer polymer was used for the sheath portion, and nylon-6 was used for the core portion. Discharge from the nozzle under the condition that the die temperature is 250 ° C.
Spinning is carried out at a speed of a minute, and the spun raw yarn is drawn by a roller plate system under normal conditions to obtain 83 decitex / 24.
A core-sheath type composite fiber of filaments (Fig. 1) was obtained. Spinnability,
The stretchability was good and there was no problem. Next, a knitted fabric was prepared using the obtained composite fiber, and the hygroscopicity and water absorption were evaluated. As a result, a good one having a moisture absorption of 27% and a water absorption of 300% was obtained.

Examples 2 to 4 As shown in Table 1, the fiber cross section was changed as shown in FIGS.
Evaluations were made in the same manner as in Example 1 except that the compounding ratio, the polyamide component added with component B, and the addition amount were changed. In all cases, the polyvinyl alcohol fiber was good in hygroscopicity and water absorption without any problem.

Examples 5 to 8 Evaluations were made in the same manner as in Example 1 except that the polymer of the component A and the composite form were as shown in Table 1. In all cases, the polyvinyl alcohol fiber was good in hygroscopicity and water absorption without any problem.

[0056]

[Table 1]

[Brief description of drawings]

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

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

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

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

FIG. 5 is a fiber cross-sectional view showing another example of the cross-sectional form of the conjugate fiber of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masao Kawamoto             1621 Sakata, Kurashiki City, Okayama Prefecture Kura Co., Ltd.             Within (72) Inventor Ichiro Inoue             1621 Sakata, Kurashiki City, Okayama Prefecture Kura Co., Ltd.             Within F-term (reference) 4L041 AA07 BA04 BA05 BA06 BA09                       BA11 BA21 BA33 BC02 CA19                       CA55 DD14

Claims (7)

[Claims] 1. A viscosity-average degree of polymerization of 200 to 500, a degree of saponification of 90 to 99.99 mol%, and a mole fraction of central hydroxyl groups of three hydroxyl groups in triad notation to vinyl alcohol units of 70 to 99.9 mol. %, Polyvinyl alcohol having a melting point of 160 ° C. to 230 ° C., and the alkali metal ion is 0.0 in terms of sodium.
A mixture obtained by melt-kneading a water-soluble thermoplastic polyvinyl alcohol polymer (A) and a polyamide resin (B) contained in an amount of 003 to 1 part by weight, and at 60 ° C.
2. A composite fiber comprising a mixture component containing 5 to 75 mass% of a component insoluble in DMSO and a thermoplastic resin component (C) having a melting point of 150 ° C. or higher. 2. The fiber according to claim 1, wherein the polyvinyl alcohol polymer (A) is a modified polyvinyl alcohol containing 4 to 15 mol% of ethylene units. 3. The polyamide resin (B) is nylon-
The composite fiber according to claim 1 or 2, which is at least one polyamide resin selected from the group consisting of 6/6, 6, nylon-6 / 12, and nylon-6. 4. The polyamide resin (B) is dispersed in the mixture component in an island shape, and the size of the island is 5 nm to 1000 n.
m, and the number of islands is 10/10 μm ² or more.
The composite fiber according to any one of 1. 5. The mass composite ratio of the mixture component and the thermoplastic resin component (C) having a melting point of 150 ° C. or higher is 10: 90-9.
The composite fiber according to any one of claims 1 to 4, which is 0:10. 6. The composite fiber according to any one of claims 1 to 5, wherein the composite form is a core-sheath type composite fiber having a mixture component as a sheath component. 7. The composite fiber according to claim 1, wherein the thermoplastic resin component (C) having a melting point of 150 ° C. or higher is polyester, nylon or polyolefin.