JP2012219385A - Composite fiber and method for producing hollow fiber using the composite fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber including a non-water absorbing polymer, having a porous hollow part, and being excellent in light weight property, bulky feeling and soft feeling, a structure thereof, and a production method with which a hollow fiber structure can be produced from a composite fiber structure without causing a wastewater treatment problem and an environmental problem.SOLUTION: There is provided a composite fiber in which a polyester-based thermoplastic polymer is a sea component 1; the polyester-based polymer is a copolymerized polyester including a dicarboxylic acid component and a glycol component; 80 mol% or more of the dicarboxylic acid component is a terephthalic acid component, 4.0-12.0 mol% is a cyclohexane dicarboxylic acid component, and 2.0-8.0 mol% is an aliphatic carboxylic acid component; and the glycol component includes a polyester polymer comprising an ethylene glycol component as a main component; and a thermoplastic polyvinyl alcohol-based polymer containing a plasticizer and having an apparent melt viscosity of 40-400 Pa s at 240°C and a shear rate of 1000 secis an island component; and an island component 2 is water soluble.

Description

  The present invention relates to a composite fiber and a fiber structure including the same, a hollow fiber obtained from the composite fiber, and a fiber structure including the hollow fiber. More specifically, the present invention relates to a hollow fiber excellent in light weight and having a good texture with a feeling of swelling and softness, in particular, a porous hollow fiber and a fiber structure thereof.

Synthetic fibers such as polyester and polyamide are widely used not only for clothing but also for industrial use due to their excellent physical and chemical properties, and thus have industrially important value. However, these synthetic fibers have a single distribution in the single yarn fineness, are large in single yarn fineness, and have a simple cross-sectional shape, so that they can be used in natural fibers such as silk, cotton and hemp. The texture and gloss are monotonous compared. Further, the above synthetic fibers were inferior in water absorption, were cold, had a slimy feel, and had a low quality. Therefore, in order to improve the above-mentioned drawbacks of synthetic fibers, it is widely practiced to make the cross-sectional shape of the synthetic fibers irregular or to make the fibers hollow.
Normally, irregular cross-section fibers and hollow fibers produced using a variant spinning nozzle or hollow spinning nozzle are deformed depending on the surface tension of the resin in a molten state before spinning and solidification, the take-up tension during spinning, etc. There is a problem that the cross section collapses or the hollow part is easily crushed. Especially when trying to develop a porous hollow shape, even if a porous hollow structure is imparted to the fiber immediately after spinning, the porous hollow part is crushed. It disappeared or the ratio of the hollow portion was likely to decrease, and it was practically impossible to obtain a fiber having a porous hollow portion by such a method.

  On the other hand, an alkali-degradable polymer is used as an island component, and as a sea component, a composite fiber is formed using an alkali-resistant polymer having a water absorption rate of 3% or more, such as polyamide or ethylene vinyl alcohol copolymer. A technique has been proposed in which a polymer is decomposed and removed by treating with a hot alkaline aqueous solution to form a porous hollow fiber (for example, see Patent Document 1). However, these problems include the complexity of wastewater treatment of alkali decomposition products, leaving a major problem from an environmental point of view. In addition, in this method, since the aqueous alkali solution needs to penetrate the sea component of the composite fiber and extract the island component, a polymer having water absorption must be used as the sea component. There are restrictions on the types, and it is difficult to use polylactic acid and polyester that are weak against alkali in the sea component. From such a polyester, the sea component is composed mainly of polylactic acid, polyethylene terephthalate, and polybutylene terephthalate. It was virtually impossible to produce a porous hollow fiber.

JP-A-7-316977

  The problem of the present invention is to solve the above-mentioned problems of the prior art, have a hollow hollow portion composed of a polymer that hardly exhibits water absorption, and have hollow fibers excellent in lightness, swell, soft feeling, etc. It is to provide a fiber structure containing it. Another object of the present invention is to provide a composite fiber for producing such a hollow fiber without causing wastewater treatment or environmental problems, and to provide a method for producing a hollow fiber using such a composite fiber. .

That is, the present invention uses a polyester-based thermoplastic polymer as a sea component, and the polyester-based polymer is a copolyester composed of a dicarboxylic acid component and a glycol component, and 80 mol% or more of the dicarboxylic acid component is terephthalic. A polyester comprising 4.0 to 12.0 mol% of a cyclohexanedicarboxylic acid component, 2.0 to 8.0 mol% of an aliphatic carboxylic acid component, and the glycol component as a main component of an ethylene glycol component. A thermoplastic polyvinyl alcohol polymer made of a polymer and containing a plasticizer and having an apparent melt viscosity of 40 to 400 Pa · s at 240 ° C. and a shear rate of 1000 sec ⁻¹ is an island component, and the island component is water-soluble. It is a composite fiber characterized by being further represented by the following chemical formula (I) in the polyester polymer: Compound (A) is 0.5 mol% to 3.5 mol% copolymerized been said composite fibers.

  Further, the present invention is a method for producing a hollow fiber, characterized in that the composite fiber is treated with water, and the water-soluble thermoplastic polyvinyl alcohol polymer is dissolved and removed from the composite fiber. A method for treating a fiber structure comprising treating a fiber structure containing water with water and dissolving and removing a water-soluble thermoplastic polyvinyl alcohol polymer from the composite fiber.

  According to the present invention, a composite fiber having good dyeability can be obtained using a cationic dye and a disperse dye under normal pressure. In addition, by dissolving and removing the water-soluble thermoplastic polyvinyl alcohol polymer from the composite fiber obtained by the present invention, the hollow fiber having a good texture with excellent lightness and swell, soft feeling, in particular, A porous hollow fiber and its fiber structure are obtained.

In the composite fiber of the present invention, the sea component is composed of a dicarboxylic acid component and a glycol component, 80 mol% or more of the dicarboxylic acid component is a terephthalic acid component, and 4.0 to 12.0 mol% is a cyclohexanedicarboxylic acid component. 2.0 to 8.0 mol% is an aliphatic dicarboxylic acid component, and the glycol component is composed of a copolymerized polyester polymer whose main component is an ethylene glycol component, and the island component is water-soluble thermoplastic. It is important that it is composed of a polyvinyl alcohol polymer, and the form of the sea island of the composite fiber is not particularly limited as long as such a condition is satisfied. The number of islands can be set according to the application, but the present invention is exhibited when obtaining hollow fibers having a high hollow ratio or hollow fibers having a large number of hollow portions.
The value of the number of islands is not particularly limited, but a range of 3 to 10 is preferable, 4 to 9 is more preferable, and 5 to 8 is more preferable. When the number of islands is less than 3, the prevention of see-through is insufficient, and the hollow part may be easily crushed when the area of the hollow part is increased in order to increase the feeling of lightness. If the number of islands exceeds 10, fiberization becomes difficult.
Moreover, the shape of each island component is not limited at all, and may be circular, elliptical, or other irregular shapes. Furthermore, the island component may be continuous or discontinuously formed in the fiber axis direction.
If the representative example of the composite fiber of this invention is shown with the cross-sectional view, a thing like FIGS. 1-3 can be mentioned, for example. 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 the polyester polymer, and the composite fiber of FIG. A large island component 2 made of a water-soluble thermoplastic polyvinyl alcohol polymer at the center of the cross section and a small island component 2 surrounded by a sea component 1 made of the polyester polymer are shown in FIG. It 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 may be appropriately changed depending on the number of hollow portions and the hollow ratio of the hollow fiber finally obtained. Can do. However, if the ratio of the island component is too small, the effect of weight reduction as a hollow fiber is not sufficiently exhibited, while if the ratio of the hollow portion is too large, a hollow fiber having practical fiber properties is obtained. Therefore, it is preferable that island: sea = 2: 98 to 65:35, more preferably 5:95 to 60:40.
Moreover, the cross-sectional form of the composite fiber is not particularly limited. For example, in addition to the circular cross section shown in FIGS. 1 to 2, for example, a triangle as shown in FIG. An arbitrary shape such as an octagon or the like, a T-shape, or a multi-leaf shape such as a 3 to 8 leaf shape can be used. Furthermore, the composite fiber of the present invention can contain optional additives such as a fluorescent brightening agent, a stabilizer, a flame retardant, and a colorant as necessary.

Next, a water-soluble thermoplastic polyvinyl alcohol polymer (hereinafter sometimes simply referred to as PVA) used for 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 a modified polyvinyl alcohol having a functional group introduced by copolymerization, terminal modification, and post-reaction.

  200-600 are preferable, as for the viscosity average polymerization degree (henceforth abbreviated as polymerization degree) of PVA used for this invention, 230-470 are more preferable, and 250-450 are especially preferable. When the degree of polymerization is less than 200, sufficient spinnability cannot be obtained at the time of spinning, and fiber formation may be difficult. If the degree of polymerization exceeds 600, the melt viscosity may be too high to discharge the polymer from the spinning nozzle. Further, by using a so-called low polymerization degree PVA having a polymerization degree of 600 or less, not only the dissolution rate is increased when the composite fiber is dissolved in an aqueous solution, but also the shrinkage when the composite fiber is dissolved can be reduced.

The degree of polymerization (P) of PVA is measured according to JIS-K6726. That is, after re-saponifying and purifying PVA, the intrinsic viscosity [η] (dl / g) measured in water at 30 ° C. is obtained by the following equation.
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 achieved more suitably.

The PVA used in the present invention preferably has a saponification degree of 90 to 99.99 mol%. More preferably, it is 93 to 99.98 mol%, more preferably 94 to 99.97 mol%, and particularly preferably 96 to 99.96 mol%. 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 be reduced depending on the type of copolymerization monomer described below. There is a case.
On the other hand, PVA having a degree of saponification greater than 99.99 mol% is liable to decrease in solubility and cannot be stably produced, making it difficult to make stable fibers.

  Further, a preferred PVA used in the present invention is a trihydroxy group having a trihydroxy group hydroxyl group having a mole fraction of 70 to 99.9 mol%, a melting point of 160 ° C. to 230 ° C., and a PVA of 100 mass. It is preferable that alkali metal ions are contained in an amount of 0.0003 to 1 part by mass in terms of sodium ions with respect to parts.

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

When the content of the central hydroxyl group of the hydroxyl group in the triad represented by PVA triad is less than 70 mol%, the crystallinity of the polymer is lowered and the fiber strength is lowered. At the same time, the fiber is stuck and wound during melt spinning. Unwinding may not be possible after removal. Moreover, the water-soluble thermoplastic fiber intended in the present invention may not be obtained.
When the content of the central hydroxyl group of the three-hydroxyl group represented by PVA triad is greater than 99.9 mol%, it is necessary to increase the melt spinning temperature because of the high melting point of the polymer. The polymer has poor thermal stability, and is susceptible to decomposition, gelation, and polymer coloring.

Further, when the PVA of the present invention is an ethylene-modified PVA, the effect of the present invention is further enhanced by satisfying the following formula.
−1.5 × Et + 100 ≧ Molar fraction ≧ −Et + 85
Here, the mole fraction (unit: mole%) represents the mole fraction of the central hydroxyl group of the three-hydroxyl group by triad display with respect to the vinyl alcohol unit, and Et is the ethylene content (unit: mole%) contained in the vinyl alcohol polymer. ).

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

  By controlling the amount of the central hydroxyl group in the hydroxyl group of 3 chain of polyvinyl alcohol used in the present invention, various physical properties relating to water such as water solubility and hygroscopicity of PVA, various properties relating to fibers such as strength, elongation and elastic modulus. Various physical properties related to melt spinning properties such as physical properties, melting point and melt viscosity can be controlled. This is presumably because the central hydroxyl group of the three-hydroxyl group represented by triad is rich in crystallinity and exhibits the features of PVA.

  The melting point (Tm) of the PVA used in the present invention is preferably 160 to 230 ° C, more preferably 170 to 227 ° C, further preferably 175 to 224 ° C, and particularly preferably 180 to 220 ° C. When the melting point is less than 160 ° C., the crystallinity of PVA is lowered, the fiber strength of the composite fiber is lowered, and at the same time, the thermal stability of the composite fiber is deteriorated, and there is a case where the fiber cannot be formed. On the other hand, when the melting point exceeds 230 ° C., the melt spinning temperature becomes high, and the spinning temperature and the decomposition temperature of PVA are close to each other, so that a composite fiber composed of PVA and another thermoplastic polymer may not be stably produced. is there. The melting point of PVA is when the temperature is raised to 250 ° C. in DS using a DSC at a temperature rising rate of 10 ° C./min, cooled to room temperature, and then heated again to 250 ° C. at a temperature rising rate of 10 ° C./min. It means the temperature at the peak top of the endothermic peak indicating the melting point of PVA.

  The PVA used in the present invention can be obtained by saponifying the vinyl ester unit of the vinyl ester polymer. Vinyl compound monomers for forming vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valenate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and Examples thereof include vinyl versatate, and among these, vinyl acetate is preferable from the viewpoint of obtaining PVA.

  In addition, the PVA used in the present invention may be a homopolymer or a modified PVA into which copolymer units are introduced. However, from the viewpoint of melt spinnability, water solubility, and fiber properties, the copolymer units are introduced. It is preferable to use modified polyvinyl alcohol. Examples of the comonomer include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, and acrylic acid n- Acrylic acid esters such as propyl and i-propyl acrylate, methacrylic acid and salts thereof, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, methacrylic acid esters such as 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-propiyl Vinyl ethers such as vinyl ether, n-butyl vinyl ether, ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, hydroxy group-containing vinyl ethers such as 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, vinylsilyls such as vinyltrimethoxysilane, isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol, 5-hexene -1-ol, 7-octen-1-ol, 9-decene-1-ol, hydroxy group-containing α-olefins such as 3-methyl-3-buten-1-ol, fumaric acid, maleic acid, itacon Acid, maleic anhydride , Monomers having a carboxyl group derived from phthalic anhydride, trimellitic anhydride or itaconic anhydride; ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, etc. Monomer having sulfonic acid group derived from: vinyloxyethyl trimethylammonium chloride, vinyloxybutyl trimethylammonium chloride, vinyloxyethyl dimethylamine, vinyloxymethyl diethylamine, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium Chloride, N-acrylamide dimethylamine, allyltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, Monomers include having a cationic group derived from the drill ethyl amine. The content of these monomers is usually 20 mol% or less.

  Among these monomers, α-olefins such as ethylene, propylene, 1-butene, isobutene, 1-hexene, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl are available because of their availability. Vinyl ethers such as vinyl ether, n-butyl vinyl ether, ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, hydroxy group-containing vinyl ethers such as 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 9-decene-1-ol, a monomer derived from 3-methyl-3-buten-1-alpha-olefins hydroxy group-containing ol are preferred.

In particular, from the viewpoints of copolymerizability, melt spinnability, and water solubility of the fibers, α-olefins having 4 or less carbon atoms of 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 having 4 or less carbon atoms and / or vinyl ethers are preferably present in the PVA in an amount of 0.1 to 20 mol%, more preferably 1 to 20 mol%, and further 4 to 4 mol. 15 mol% is preferable and 6-13 mol% is especially preferable.
Furthermore, when the α-olefin is ethylene, the physical properties of the fiber are improved, and therefore it is preferable to use a modified PVA in which ethylene units are 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 bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is performed without solvent or in a solvent such as alcohol is usually employed. Examples of alcohol used as a solvent during solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. As initiators used for copolymerization, α, α′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, n-propyl peroxycarbonate And known initiators such as azo initiators or peroxide initiators. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of 0 to 150 degreeC is suitable.

  It is preferable that the content rate of the alkali metal ion in PVA used by this invention is 0.0003-1 mass part in conversion of sodium ion with respect to 100 mass parts of PVA, and 0.0003-0.8 mass part is more. Preferably, 0.0005 to 0.6 parts by mass is more preferable, and 0.0005 to 0.5 parts by mass is particularly preferable. When the content of alkali metal ions is less than 0.0003 parts by mass, sufficient water solubility may not be exhibited and undissolved substances may remain. Further, when the content of alkali metal ions is more than 1 part by mass, decomposition and gelation at the time of melt spinning may not be remarkably made into fibers. Examples of the alkali metal ion include potassium ion and sodium ion.

In the present invention, the method for containing a specific amount of alkali metal ions in PVA is not particularly limited, and a method of adding a compound containing alkali metal ions after polymerizing PVA, or saponifying a vinyl ester polymer in a solvent. In this case, by using an alkaline substance containing alkali ions as a saponification catalyst, alkali metal ions are blended in PVA, and the saponified PVA is washed with a washing solution, whereby alkali metal ions contained in PVA are obtained. Although the method of controlling content etc. is mentioned, the latter is more preferable.
The content of alkali metal ions can be determined by atomic absorption method.

Examples of the alkaline substance used as the saponification catalyst include potassium hydroxide and sodium hydroxide. The molar ratio of the alkaline substance used for the saponification catalyst is preferably from 0.004 to 0.5, particularly preferably from 0.005 to 0.05, based on the vinyl acetate unit. The saponification catalyst may be added all at the beginning of the saponification reaction, or may be added in the middle of the saponification reaction.
Examples of the solvent for the saponification reaction include methanol, methyl acetate, dimethyl sulfoxide, dimethylformamide and the like. Among these solvents, methanol is preferable, methanol whose water content is controlled to 0.001 to 1% by mass is more preferable, methanol whose water content is controlled to 0.003 to 0.9% by mass is more preferable, and water content is Methanol controlled to 0.005 to 0.8% by mass is particularly preferable. Examples of the cleaning liquid include methanol, acetone, methyl acetate, ethyl acetate, hexane, water, and the like. Among these, methanol, methyl acetate, water alone or a mixed liquid is more preferable.
Although it sets so that the content rate of an alkali metal ion may be satisfied as a quantity of a washing | cleaning liquid, 300-10000 mass parts is preferable with respect to 100 mass parts of PVA normally, and 500-5000 mass parts is more preferable. As washing | cleaning temperature, 5-80 degreeC is preferable and 20-70 degreeC is more preferable. The washing time is preferably 20 minutes to 10 hours, and more preferably 1 hour to 6 hours.

In the present invention, it is necessary to contain an appropriate plasticizer in the PVA used from the viewpoint of fiber physical properties and fiberizing process properties. The apparent melt viscosity of the plasticizer-containing PVA at 240 ° C. and a shear rate of 1000 sec ⁻¹ is 40 to 400 Pa · s or more preferably 50 to 350 Pa · s. If the apparent melt viscosity is less than 40 Pa · s, the melt viscosity is too low, and it becomes difficult to match the viscosity balance with the composite polymer. Furthermore, if the degree of polymerization of the composite polymer is lowered to lower the melt viscosity and match the viscosity balance, the fiber strength is reduced.
On the other hand, when the apparent melt viscosity exceeds 400 Pa · s, the melt fluidity is deteriorated, so that the polymer is likely to be thermally deteriorated such as gelation and decomposition.

The type of plasticizer to be contained in PVA is not particularly limited, but the effect of reducing the apparent melt viscosity at 240 ° C. and a shear rate of 1000 sec ⁻¹ is 10 to 200 Pa · s, preferably 20 to 180 Pa · s. Don't be. If the viscosity reducing effect is less than 10 Pa · s, since there is almost no plasticizing effect, the melt fluidity of PVA is deteriorated and the polymer is likely to be thermally deteriorated. On the other hand, when the viscosity reducing effect exceeds 200 Pa · s, the melt viscosity is too low, so that the viscosity balance with the composite polymer is lost and spinning becomes impossible.
Examples of the plasticizer having a viscosity reducing effect on melt viscosity at 240 ° C. and a shear rate of 1000 sec ⁻¹ of 10 to 200 Pa · s include, for example, polyethylene glycol, propylene glycol and its oligomer, butylene glycol and its oligomer, polyglycerin derivative, Glycerin derivatives in which alkylene oxides such as ethylene oxide and propylene oxide are added to glycerin, etc., derivatives in which alkylene oxides such as ethylene oxide and propylene oxide are added to sorbitol, polyhydric alcohols such as pentaerythritol and their derivatives, PO / EO random co Polymers etc. are mentioned, and the spinnability improves by mix | blending said plasticizer with PVA in the ratio of 1-30 mass%, Preferably 2-20 mass%.
Among them, thermal decomposition hardly occurs in the fiberizing process, and in order to obtain good plasticity and spinnability, sorbitol alkylene oxide adduct, polyglycerin alkyl monocarboxylic acid ester, PO / EO random copolymer, etc. 1 to 30% by mass, preferably 2 to 20% by mass, and particularly preferably a compound obtained by adding 1 to 30 mol of ethylene oxide to 1 mol of sorbitol.
A compound obtained by adding 1 to 30 moles of ethylene oxide to 1 mole of sorbitol will be described below. When the average number of added moles of ethylene oxide is less than 1, there is no problem with compatibility with PVA, but since the molecular weight is low, there is difficulty in thermal stability. On the other hand, if the average added mole number of ethylene oxide exceeds 30, the SP value is lowered, so the compatibility with PVA is deteriorated and the fiber forming processability is adversely affected. The number of added moles is an average, and there may be a distribution in the number of added moles, but it is not preferable that 30 moles or more of adduct is mixed in at 50% by weight or more.
Moreover, although it is content with respect to PVA, it is preferable to mix | blend 1-30 mass%, Preferably 2-20 mass%. When the content is less than 1% by mass, the plasticizing property is insufficient, and when it exceeds 30% by mass, the viscosity balance with the composite polymer is lost, and the fiber forming processability is deteriorated.
Moreover, it is preferable that the average molecular weight of this compound is about 200-1500.
Although there is no restriction | limiting in particular as a method of adding this compound which is a plasticizer to PVA, The method of forming into a master chip using a twin-screw extruder is preferable at the point which disperse | distributes a plasticizer uniformly.

  The polyester polymer constituting the sea component of the composite fiber of the present invention is a polyester having ethylene terephthalate units as main repeating units, and 80 mol% or more of the repeating units are terephthalic acid and / or ester-forming derivatives thereof (hereinafter referred to as “polyester”). In some cases, cyclohexanedicarboxylic acid and / or its ester-forming derivative is 4.0 to 12.0 mol% of the dicarboxylic acid component, and aliphatic dicarboxylic acid and its ester are formed. The functional derivative must be copolymerized in an amount of 2.0 to 8.0 mol%.

When cyclohexanedicarboxylic acid or an ester-forming derivative thereof (hereinafter sometimes referred to as cyclohexanedicarboxylic acid component) and aliphatic dicarboxylic acid or an ester-forming derivative thereof are copolymerized with polyethylene terephthalate, crystals are produced in comparison with aromatic dicarboxylic acid. Since the structural disorder is small, a fiber excellent in light fastness can be obtained while ensuring a high dyeing rate.
By copolymerizing the cyclohexanedicarboxylic acid component, the crystal structure of the polyester fiber is disturbed, and the orientation of the amorphous part is lowered. Therefore, it becomes easy for the disperse dye to penetrate into the fiber, and the atmospheric dyeability of the disperse dye can be improved. Furthermore, since the cyclohexane dicarboxylic acid component is less disturbed in crystal structure than the aromatic dicarboxylic acid, it is excellent in light fastness.
If the copolymerization amount of the cyclohexanedicarboxylic acid component is less than 4.0 mol% in the dicarboxylic acid component, the degree of orientation of the amorphous part inside the fiber is high, so that the dyeability for disperse dyes under normal pressure environment is insufficient, The target dyeing rate cannot be obtained. If the dicarboxylic acid component exceeds 12.0 mol%, it is possible to ensure good quality in terms of dyeability such as dyeing rate, fastness to washing, fastness to light, etc., but spinning by a high-speed spinning method without stretching. In this case, the glass transition temperature of the resin is low and the degree of orientation of the amorphous part in the fiber is low, so that spontaneous elongation occurs during high-speed winding, and stable high-speed spinnability cannot be obtained. Preferably it is 5.0-10.0 mol%.
The cyclohexanedicarboxylic acid used in the present invention includes three positional isomers of 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid. From the point obtained, any positional isomer may be copolymerized, or a plurality of positional isomers may be copolymerized. Further, although there are cis / trans isomers for each positional isomer, any stereoisomer may be copolymerized, or both cis / trans positional isomers may be copolymerized. The same applies to the cyclohexanedicarboxylic acid derivative.

As with the cyclohexanedicarboxylic acid component, the aliphatic dicarboxylic acid and its ester-forming derivative component are disturbed in the crystal structure of the polyester fiber, and the orientation of the amorphous part is lowered, so that the disperse dye can penetrate into the fiber. It becomes easy and it becomes possible to improve the normal-pressure dyeability of a disperse dye.
Copolymerization of an aliphatic dicarboxylic acid component with polyethylene terephthalate also has an effect on low temperature setting properties, and when heat setting is performed for shape stabilization after making the fiber obtained by the present invention into a woven or knitted fabric, the heat setting temperature is lowered. It becomes possible to do. Low-temperature setability is a desirable physical property for knit applications, and when it is combined with materials other than polyester, such as wool, cotton, acrylic, and polyurethane, the temperature required for heat setting should be kept to a level that does not degrade the properties of materials other than polyester. Is possible. In addition, even when polyester fibers are used alone, it is possible to cope with general existing knit equipment, and the use can be expected to expand.
When the copolymerization amount of the aliphatic dicarboxylic acid component in the dicarboxylic acid component is less than 2.0 mol%, the dyeability with respect to the disperse dye under the normal pressure environment is insufficient, and the desired dyeing rate cannot be obtained. In addition, when the copolymerization amount of the aliphatic dicarboxylic acid component in the dicarboxylic acid component exceeds 8.0 mol%, the dyeing rate increases, but when the yarn is produced by a high-speed spinning method without stretching. The degree of orientation of the amorphous part inside the fiber becomes low, and spontaneous elongation during high-speed winding becomes prominent, and stable high-speed spinnability cannot be obtained. Preferably it is 3.0-6.0 mol%. Preferred examples of the aliphatic dicarboxylic acid component of the present invention include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and decanedicarboxylic acid from the viewpoints of color developability and spinning processability. These may be used alone or in combination of two or more.

  The polyester polymer constituting the sea component of the composite fiber of the present invention may be further copolymerized with a compound (A) represented by the following chemical formula (I) in an amount of 0.5 to 3.5 mol%.

Examples of the metal salt (A) of sulfoisophthalic acid represented by the above formula (I) include 5-sodium sulfoisophthalic acid, or sulfonic acid alkali metal bases such as 5-potassium sulfoisophthalic acid and 5-lithium sulfoisophthalic acid. And dicarboxylic acid component having 5-tetraalkylphosphonium sulfoisophthalic acid such as 5-tetrabutylphosphonium sulfoisophthalic acid and 5-ethyltributylphosphonium sulfoisophthalic acid. Only one type of the metal salt (A) of sulfoisophthalic acid represented by the above formula (I) may be copolymerized in the polyester, or two or more types may be copolymerized.
By copolymerizing the metal salt (A) of sulfoisophthalic acid represented by the above formula (I), the amorphous structure can be retained in the fiber internal structure as compared with the conventional polyester fiber, and as a result, the dispersion A polyester fiber which can be dyed at normal pressure with respect to dyes and cationic dyes and has excellent fastness can be obtained.
When the copolymerization amount of the metal salt (A) of sulfoisophthalic acid represented by the above formula (I) is less than 1.0 mol%, a cationic dyeable dye which becomes clear and has a good color tone when dyed with a cationic dye. Can not be obtained. On the other hand, when the copolymerization amount of (A) exceeds 3.5 mol%, the viscosity of the polyester is remarkably increased and spinning becomes difficult. The amount becomes excessive and the clarity of the color tone is rather lost. From the viewpoint of the sharpness and spinnability of the dyed product, the copolymerization amount of (A) is preferably 1.2 to 3.0 mol%, more preferably 1.5 to 2.5 mol%. preferable.

The composite fiber of the present invention is not particularly limited as long as it is a spinning technique capable of forming a cross-sectional form using the above PVA as an island component and the polyester polymer as a sea component. In a system of a combination of polymers that do not react with PVA and do not gel, for example, a method by mixed spinning is possible, and PVA as an island component and the polyester polymer as a sea component are melt-kneaded with one extruder. Then, it can be discharged from the same spinning nozzle, wound up, and fiberized.
In the composite spinning method, PVA and the polyester polymer are melted and kneaded by separate extruders, and then PVA becomes an island component, and the polyester polymer becomes a sea component. It can be discharged from and wound up and made into a fiber.

The fiberizing conditions need to be set according to the combination of the polymers and the composite cross-sectional form, but it is desirable to determine the fiberizing conditions mainly with the following points in mind.
(1) Generally, PVA is inferior in melt fluidity at high temperature, and is a polymer that easily crosslinks and gels in the presence of a stagnant part. Therefore, an extrusion zone of a polymer and a jet pack (a set of composite spinning parts) It is important to make it difficult for the stagnant part to occur in the polymer flow part inside the body.
(2) The spinneret temperature is preferably Mp to Mp + 80 ° C. when the melting point of a polymer having a high melting point among the polymers constituting the composite fiber is Mp, and the shear rate (γ) is 1,000 to 25,000 sec ^{−. 1} , It is preferable to spin with draft V10-500.
(3) From the viewpoint of the combination of the polymers to be combined, it is possible to perform the composite spinning by combining the polymers having close melt viscosities as measured by the die temperature at the time of spinning and the shear rate when passing through the nozzle. From the aspect, it is preferable.

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: for example, “TA3000” manufactured by Mettler). The shear rate (γ) is calculated as γ = 4Q / πr ³ where r (cm) is the nozzle radius and Q (cm ³ / sec) is the amount of polymer discharged per single hole. The draft V is calculated as V = 5 A · πr ² / 3Q when the take-up speed is A (m / min).

When the composite fiber of the present invention is produced, spinning cannot be performed at a spinneret temperature lower than the melting point Tm of PVA because the PVA does not melt. On the other hand, if it exceeds Tm + 80 ° C., PVA tends to be gelled by thermal decomposition or self-crosslinking, so that spinnability is lowered. Further, if the shear rate is lower than 1,000 sec ⁻¹ , the yarn is easily broken, and if it is higher than 25,000 sec ⁻¹ , the back pressure of the nozzle is increased and the spinnability is degraded. When the draft is lower than 10, the unevenness of fineness becomes large and it becomes difficult to stably spin, 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 without being stretched, or is stretched as 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.
If the draw ratio is less than HDmax × 0.55, a composite fiber having sufficient strength cannot be stably obtained, and if it exceeds HDmax × 0.9, the yarn tends to be broken. Stretching may be performed after winding and then stretching after being discharged from the spinning nozzle, or in some cases in the present invention. Stretching is usually performed by hot stretching, and may be performed using any of hot air, a hot plate, a hot roller, a water bath, and the like.
In the drawing process, the higher the absolute value of the draw ratio, the easier the generation of fluff and the yarn breakage. Therefore, the fiber forming conditions from high speed spinning to low draw ratio or the known high speed spinning / winding method is preferred.

  The drawing temperature is appropriately set according to the composite polymer, but since the PVA used in the present invention has a high crystallization speed, the crystallization of the undrawn yarn proceeds considerably, and plastic deformation of the crystal part hardly occurs before and after Tg. . For this reason, in the composite with the polyester polymer of the present invention, even when contact heating stretching such as hot roller stretching is performed, stretching is performed with a relatively high temperature (about 70 to 100 ° C.) as a guide. Moreover, when heat-extending using non-contact type heaters, such as a heating furnace and a heating tube, it is preferable to set it as temperature conditions of about 150-200 degreeC further at high temperature.

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

  In addition, the cross-sectional shape of the composite fiber in the present invention is not particularly limited, and can be a perfect circle, a hollow shape, or a different shape depending on the shape of the spinning nozzle. A perfect circle is preferable from the viewpoint of process passability in fiberization and weaving.

  The composite fiber of the present invention can control the shrinkage behavior of the composite fiber when PVA, which is an island component, is dissolved in water depending on the production conditions, and the composite fiber does not shrink or the amount of shrinkage is suppressed when PVA is dissolved. When trying to do so, it is desirable to heat-treat the composite fiber. This heat treatment may be performed at the same time as stretching in the fiberizing step accompanying stretching, or may be performed separately from stretching. When the heat treatment temperature is increased, the maximum shrinkage of the hollow fiber obtained by dissolving the island component PVA can be lowered, but conversely, the melting temperature of the island component PVA in water tends to increase. It is desirable to set the heat treatment conditions while observing the balance with the maximum shrinkage in the processing step, and it is generally preferable to set the conditions within the range of the glass transition point of the island component PVA to (Tm-10) ° C.

  When the treatment temperature is lower than Tg, a sufficiently crystallized conjugate fiber cannot be obtained. For example, the shrinkage when the fabric is heat set is increased, and the fabric texture is hardened. On the other hand, when the treatment temperature exceeds (Tm-10) ° C., the fiber is stuck, which is not preferable.

  The heat treatment may be performed by shrinking the drawn composite fiber. When shrinkage is applied to the composite fiber, the shrinkage rate of the composite fiber until dissolution of PVA in water decreases. The shrinkage to be added is preferably 0.01 to 5%, more preferably 0.1 to 0.5%, and particularly preferably 1 to 4%. If the applied shrinkage is 0.01% or less, the effect of reducing the maximum shrinkage rate of the composite fiber when dissolving PVA is not substantially obtained. If the applied shrinkage exceeds 5%, the composite fiber is in the process of shrinking. The slack is not stable and cannot be shrunk stably.

  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. And by changing the kind of PVA and the production conditions of the composite fiber, in the present invention, it is possible to obtain a composite fiber in which the melting temperature of the PVA island component is 30 ° C to 100 ° C. In order to balance these characteristics, it is preferable to use a composite fiber made 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 in the wet state of the polyester polymer of the present invention constituting the sea component of the composite fiber. Of course, the higher the treatment temperature, the longer the treatment time. Shorter. When melt | dissolving using a hot water, if the glass transition point of the polyester polymer of this invention used as a sea component is 70 degreeC or more, the hot water process under the high temperature high pressure of 100 degreeC or more is the most preferable. In addition, although soft water is normally used for aqueous solution, alkaline aqueous solution, acidic aqueous solution may be sufficient, and surfactant etc. may be included.

  In the present invention, it is preferable from the viewpoint of quality stability that fine particles are added to the thermoplastic polymer of the sea component. It contains 0.2 to 10% by weight of a particulate inert substance having an average particle size of 0.1 to 1.2 μm. Examples of the fine particles to be added include silica sol, fine particle silica, alumina sol, fine particle alumina, ultrafine particle titanium oxide, calcium carbonate sol, fine particle calcium carbonate, modified silica sol with improved dispersion stability, and other polyester fibers. A colloid or the like of a particulate inert substance having a refractive index close to that of the refractive index is used. When the fine particles are added in an amount exceeding 10% by weight, the fiber forming processability becomes poor and is not suitable.

When the composite fiber of the present invention is treated with hot water to dissolve and remove the PVA component, it contains a scouring agent composed of a nonionic surfactant, an anionic surfactant, etc., and other additives. May be.
Further, the PVA dissolution and removal by the above hot water treatment may be performed on the composite fiber alone, or after the fiber structure including the composite fiber is formed, the hot water treatment may be performed.
The temperature and treatment time during the hydrothermal treatment vary depending on the fineness of the composite fiber, the ratio of the island component in the composite fiber, the distribution of the island component, the ratio of the thermoplastic polymer of the sea component, the type, the form of the fiber structure, etc. It can be adjusted as needed according to The hydrothermal treatment temperature is 60 ° C or higher, preferably 80 ° C or higher.
Examples of the hot water treatment method include a method of immersing the composite fiber or the fiber structure in the hot water liquid, or a method of applying the hot water liquid to the hot water liquid by a system such as a pad or a spray.

In the present invention, PVA is removed from the composite fiber as an aqueous solution by the hydrothermal treatment as described above. However, such PVA has biodegradability, and is decomposed when activated sludge treatment or soil is buried and water is removed. And carbon dioxide. The dissolved and removed PVA is almost completely decomposed in 2 days to 1 month when continuously treated with activated sludge in the form of an aqueous solution. From the viewpoint of biodegradability, the saponification degree of the fiber is preferably 90 to 99.99 mol%, more preferably 92 to 99.98 mol%, and particularly preferably 93 to 99.97 mol%. The 1,2-glycol bond content of the fiber is preferably 1.0 to 3.0 mol%, more preferably 1.2 to 2.5 mol%, and particularly preferably 1.3 to 1.9 mol%. .
When the 1,2-glycol bond amount of PVA is less than 1.0 mol%, not only the biodegradability of PVA is deteriorated, but also the melt viscosity is too high and the spinnability of the composite fiber may be deteriorated. is there. When the 1,2-glycol bond content of PVA is 3.0 mol% or more, the thermal stability of PVA is deteriorated and spinnability may be lowered.

  In the present invention, PVA in the composite fiber is selectively removed by hot water treatment to produce a hollow fiber having a plurality of hollow portions. The PVA island component completely surrounded by the sea component composed of the polyester polymer of the present invention, which is considered not to be formed, is dissolved and removed by hot water treatment to form hollow fibers. When the composite fiber has a cut surface such as a staple fiber, it is conceivable that PVA may come off from the end surface of the fiber. However, in the present invention, even in a state of a long fiber having substantially no cut surface. PVA is dissolved and removed neatly, and it is no exaggeration to say that this fact overturns conventional common sense.

Furthermore, the greatest feature of the present invention is that the use of a specific modified component in the polyester polymer of the sea component enables dyeing at a low temperature, and the hollow portion formed after dissolving and removing the PVA island component is the dyeing step. Therefore, the hollow fiber can be kept lightweight and bulky.

The area ratio (hollow rate) of the hollow part in the hollow fiber of the present invention is preferably 2% or more, and if it is lower than 2%, lightness, bulkiness, heat retention, swell, etc. may not be sufficiently exhibited. is there.
Therefore, the area ratio of the hollow portion is preferably 5% or more. If the area ratio of the hollow portion is too large, the fiber strength becomes insufficient. Therefore, the area ratio is preferably 70% or less, more preferably 50% or less.

  The hollow fibers of the present invention thus obtained are particularly taffeta, decyne, georgette, crepe, processed yarn, twill from the viewpoint of water absorption, heat retention, lightness, flexibility, opacity, swell feeling, etc. It is suitable for making woven fabrics such as knitted fabrics such as tengu, smooth and tricot. Furthermore, it can be used not only for apparel but also for various living materials such as non-woven fabrics, medical uses, sanitary materials, and stuffing materials, and it can be used as interior materials for automobiles, silencers and vibration-proof materials as fiber laminates. It is also possible to make paper.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the examples, “part” and “%” relate to mass unless otherwise specified.

[Analysis method of PVA]
The analysis method of PVA followed JIS-K6726 unless otherwise specified.
The amount of modification was determined by measurement with a 500 MHz proton NMR (JEOL GX-500) apparatus using modified polyvinyl ester or modified PVA.
The content of alkali metal ions was determined by atomic absorption method.

The 1,2-glycol bond content was measured by the method described above.
The ratio of the amount of hydroxyl groups in three chains according to the triad display of the PVA of the present invention was determined by the following measurement.
PVA was saponified to a saponification degree of 99.5 mol% or more, thoroughly washed with methanol, then dissolved in d6-DMSO using PVA that had been dried at 90 ° C. under reduced pressure for 2 days, and then 500 MHz proton NMR (JEOL GX- 500) Measurement at 65 ° C. was performed with an apparatus. The peak derived from the hydroxyl group of the vinyl alcohol unit in PVA appears in the region of a chemical shift of 4.05 ppm to 4.70 ppm, and this integrated value is taken as the amount of vinyl alcohol unit (II). The central hydroxyl group of the three hydroxyl groups by triad display of PVA appears at 4.5 ppm in the case of isotacticity linkage, 4.36 ppm in the case of heterotacticity linkage, and 4.13 ppm in the case of syndiotacticity linkage, respectively. The sum of these three integral values is defined as the central hydroxyl group amount (I) of the three hydroxyl groups represented by triad display.
The molar fraction of the central hydroxyl group of three hydroxyl groups by triad display 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 DSC ("TA3000" manufactured by Mettler), heated in nitrogen at a heating rate of 10 ° C / min to 250 ° C, cooled to room temperature, and again at a heating rate of 10 ° C / min. The temperature was expressed as the peak top temperature of the endothermic peak indicating the melting point of PVA when the temperature was raised to 250 ° C.
[Apparent melt viscosity and thinning effect]
The apparent melt viscosity of PVA polymer (with plasticizer and without plasticizer) at 240 ° C. is measured using Capillograph 1C PMD-C manufactured by Toyo Seiki Seisakusho. Then, the apparent melt viscosity at a shear rate of 1000 sec ⁻¹ is obtained and calculated from the following equation.
Thickening effect (Pa · s)
= (Apparent melt viscosity without plasticizer)-(apparent melt viscosity with plasticizer)

[PVA removal rate in hot water]
About the composite fiber of this invention, when the melt | dissolution temperature in the hot water of PVA which comprises this composite fiber is set to T (alpha) (degreeC), it processes for 40 minutes with the hot water of (Talpha + 40) degreeC, 5 minutes of water washing, and after drying The mass reduction rate was defined as the PVA removal rate. In addition, Tα can be obtained, for example, as a temperature when a fiber made of PVA alone is subjected to a load of 2.2 mg / dtex, suspended in water, the water temperature is raised, and cutting is performed.

[Measurement of hollow area ratio]
The cross section of the hollow fiber yarn was photographed with SEM and calculated from the porous hollow area and the entire area of the hollow fiber in the cross section.

[Evaluation of fiber processability]
Depending on how many times the fiber was cut when spinning 100 kg of fiber, the evaluation was as follows.
◎: Within 1 time / 100kg
○: 2 to 3 times / 100 kg
Δ: 4-7 times / 100 kg
×: 8 times / 100kg

[Texture evaluation of fabrics]
Lightness ○: Rich in lightness ×: Lack of lightness

[Evaluation of color development after dyeing of fabric]
The fabric dyed under certain dyeing conditions was subjected to sensory evaluation by 10 panelists. The result was 2 points for excellent, 1 point for excellent, and 0 for inferior.
○: Total score of 15 points or more △: Total score of 8-14 points ×: Total score of 7 points or less

[Production of ethylene-modified PVA]
A 100-liter pressurized reactor equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 29.0 kg of vinyl acetate and 31.0 kg of methanol, heated to 60 ° C., and then bubbled for 30 minutes with nitrogen bubbling. Was replaced with nitrogen. Next, ethylene was introduced and charged so that the reactor pressure was 5.2 kg / cm ² (5.8 × 10 ⁵ Pa). Prepare a 2.8 g / L solution of 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol as an initiator, and perform nitrogen replacement by bubbling with nitrogen gas. did. After adjusting the temperature inside the polymerization tank to 60 ° C., 170 ml of the initiator solution was injected to start polymerization. During the polymerization, ethylene was introduced to maintain the reaction vessel pressure at 5.9 kg / cm ² (5.8 × 10 ⁵ Pa), the polymerization temperature at 60 ° C., and the above initiator solution at 610 ml / hr. Polymerization was carried out with continuous addition of AMV. After 10 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. 46.5 g (in polyvinyl acetate) was added to 200 g of polyvinyl acetate in methanol (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 50% by adding methanol to the obtained polyvinyl acetate solution. Saponification was performed by adding an alkaline solution (NaOH in 10% methanol) having a molar ratio (MR) of 0.10 to the vinyl acetate unit. About 2 minutes after the addition of the alkali, the gelled system was pulverized with a pulverizer and allowed to stand at 60 ° C. for 1 hour to allow saponification to proceed, and then 1000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the end 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 to wash at room temperature for 3 hours. After repeating the above washing operation three times, the PVA obtained by centrifugal drainage was left in a dryer at 70 ° C. for 2 days to obtain dry PVA.
The saponification degree of the obtained ethylene-modified PVA was 98.5 mol%. Further, after the modified PVA was incinerated, the content of sodium measured by an atomic absorption photometer using a material dissolved in an acid was 0.01 part by mass with respect to 100 parts by mass of the modified PVA.
In addition, after removing the unreacted vinyl acetate monomer after polymerization, a methanol solution of polyvinyl acetate obtained by precipitation in n-hexane and reprecipitation purification by dissolving with acetone was performed three times, and then dried under reduced pressure at 80 ° C. for 3 days. To obtain purified polyvinyl acetate. When the polyvinyl acetate was dissolved in DMSO-d6 and measured at 80 ° C. using 500 MHz proton NMR (JEOL GX-500), the ethylene content was 8.4 mol%. After saponifying the above methanol solution of polyvinyl acetate at an alkali molar ratio of 0.5, the pulverized product was allowed to stand at 60 ° C. for 5 hours to proceed saponification, followed by methanol soxhlet for 3 days, and then at 80 ° C. And purified under reduced pressure for 3 days to obtain purified ethylene-modified PVA. When the average degree of polymerization of the PVA was measured according to a conventional method JIS K6726, it was 330. The amount of 1,2-glycol bond and the content of hydroxyl group of three-chain hydroxyl group of the purified PVA were determined as described above from the measurement with a 500 MHz proton NMR (JEOL GX-500) apparatus. As a result, they were 1.7 mol% and 83%, respectively. It was hot.
Further, a cast film having a thickness of 10 microns was prepared by preparing a 5% aqueous solution of the purified modified PVA. After the film was dried under reduced pressure at 80 ° C. for 1 day, the melting point of PVA was measured by the above-described method using DSC (“TA3000” manufactured by METTLER) and found to be 212 ° C.
Next, a plasticizer-added modified PVA was prepared by adding 10% by mass of a compound obtained by adding 2 moles of ethylene oxide to 1 mole of sorbitol to the modified PVA obtained above using a twin screw extruder. This plasticizer-added modified PVA had an apparent melt viscosity of 130 Pa · s at 240 ° C. and a shear rate of 1000 sec ⁻¹ , and a viscosity reducing effect of 70 Pa · s.

Example 1
The modified PVA obtained above is an island component, and the sea component polyester polymer is 90 mol% of dicarboxylic acid component, terephthalic acid, 5.0 mol% of 1,4-cyclohexanedicarboxylic acid, adipic acid Is produced by a transesterification reaction and a polycondensation reaction with all carboxylic acid components containing 5.0 mol% of each carboxylic acid component, ethylene glycol, and 0.5% by mass of titanium dioxide having an average particle size of 0.3 μm. After spinning at 230 ° C. using a composite spinning part that does not cause PVA melt residence, the undrawn yarn was spun at a spinning temperature of 260 ° C. and a spinning speed of 1800 m / min. By contacting and drawing at a draw ratio of 2.3 times, a composite fiber of 83 dtex / 24f having a fiber cross section and a composite ratio as shown in Table 1 is obtained. .

Next, a plain woven fabric was prepared using the conjugate fiber as warp and weft. The green machine density was 95 / 25.4 mm and 86 wefts / 25.4 mm. The raw fabric was dipped in an aqueous solution containing sodium carbonate at a rate of 2 g / liter at 80 ° C. for 30 minutes to remove the paste, and then preset at 170 ° C. for about 40 seconds. Next, hydrothermal treatment was performed with an aqueous solution containing 1 g / liter of Intol MT concrete (an anion activator, Meisei Chemical Co., Ltd.) at a bath ratio of 50: 1, a temperature of 100 ° C., and a time of 40 minutes. The plain woven fabric having the PVA removal rate and the hollow area rate shown in Table 2 was obtained by thoroughly washing with water. Table 2 shows the evaluation results of the fabric including the feeling of lightness. Furthermore, the staining conditions were as follows.
(Dyeing conditions)
Dye: Dianix NavyBlue SPH conc 5.0% omf
Auxiliary agent: Disper TL: 1.0 cc / l, ULTRA MT-N2: 1.0 cc / l
Bath ratio: 1/50
Dyeing temperature x time: 95-100 ° C x 40 minutes

Example 1
As can be seen from Table 2, the woven fabric comprising the hollow fibers of the present invention had a very light weight, and had an excellent soft and swelled texture.

Examples 2-8
Fiberization, production of fabrics, and evaluation were performed in the same manner as in Example 1 except that the seam copolymerization species, copolymerization amount, and sea-island composite ratio were changed as shown in Table 1. All the fabrics were excellent in lightness and color development, and had a soft and swelled texture (see Table 2).

Examples 9-10
As shown in Table 1, fiberization, fabric preparation and evaluation were performed in the same manner as in Example 1 except that the modified species and amount of the island component were changed. The obtained fabric had a light feeling and good color developability, and had a soft and swelled excellent texture (see Table 2).

Examples 11-13
As shown in Table 1, fiberization, creation of a woven fabric, and evaluation were performed in the same manner as in Example 1 except that the fiber cross section, the number of islands, the composite ratio, and the like were changed. All the fabrics were excellent in lightness and color development, swelled, and had a very soft and tight feeling (see Table 2).

Comparative Examples 1-2
Except for changing the copolymerization amount of the sea component and the sea-island composite ratio as shown in Table 1, fiberization, creation of a woven fabric, and evaluation were performed in the same manner as in Example 1. All the fabrics were inferior in color developability (see Table 2).

Comparative Examples 3-4
Except for changing the copolymerization amount of the sea component as shown in Table 1, fiberization, production of a woven fabric, and evaluation were performed in the same manner as in Example 1. In either case, the fiber forming process was poor, and the fabric and the color development were inferior (see Table 2).

Comparative Example 5
As shown in Table 1, fiberization, production of woven fabric, and evaluation were performed in the same manner as in Example 1 except that the amount of modification of the island component was changed. The fiber forming processability was inferior (see Table 2).

According to the present invention, it is possible to provide a hollow fiber excellent in lightness, dry feeling, bulging feeling, and the like and a fiber structure including the fiber.
Specifically, the hollow fiber of the present invention and the fiber structure containing the fiber are effectively used in a wide variety of general clothing such as formal or casual fashion clothing for men and women, sports use, uniform use, etc. be able to. Further, it can be effectively used for general material applications, for example, interior material applications such as automobiles and airplanes, living material applications such as shoes and bags, and industrial material applications such as curtains and carpets.

Fiber cross-sectional view showing an example of the cross-sectional shape of the conjugate fiber of the present invention Fiber cross-sectional view showing an example of the cross-sectional shape of the conjugate fiber of the present invention Fiber cross-sectional view showing an example of the cross-sectional shape of the conjugate fiber of the present invention

1: Sea component 2: Island component

Claims (9)

A polyester-based thermoplastic polymer is used as a sea component, and the polyester-based polymer is a copolyester composed of a dicarboxylic acid component and a glycol component, and 80 mol% or more of the dicarboxylic acid component is a terephthalic acid component. Polyester polymer in which 1.0 to 12.0 mol% is a cyclohexanedicarboxylic acid component, 2.0 to 8.0 mol% is an aliphatic carboxylic acid component, and the glycol component is mainly composed of an ethylene glycol component A thermoplastic polyvinyl alcohol polymer containing a plasticizer and having an apparent melt viscosity of 40 to 400 Pa · s at 240 ° C. and a shear rate of 1000 sec ⁻¹ is an island component, and the island component is water-soluble. A composite fiber characterized by that. The composite fiber according to claim 1, wherein the polyester polymer according to claim 1 is copolymerized with 0.5 mol% to 3.5 mol% of a compound (A) represented by the following chemical formula (I).

  The composite according to claim 1 or 2, wherein the water-soluble thermoplastic polyvinyl alcohol according to claim 1 is a modified polyvinyl alcohol containing 0.1 to 20 mol% of α-olefin units and / or vinyl ether units having 4 or less carbon atoms. fiber.   The composite fiber according to claim 3, comprising 4 to 15 mol% of ethylene units and / or propylene units as α-olefin units.   The composite fiber according to any one of claims 1 to 4, wherein the content of 1,2-glycol bonds in the water-soluble thermoplastic polyvinyl alcohol is 1.0 to 3.0 mol%.   The plasticizer according to claim 1 is a compound obtained by adding 1 to 30 mol of ethylene oxide to 1 mol of sorbitol, and the content of the compound in the island component is 1 to 30% by mass. The composite fiber of any one of Claims.   The composite fiber according to any one of claims 1 to 6, wherein the occupied area of the island component is 5 to 60% and the number of islands is 3 to 8.   The composite fiber according to claim 7, wherein the composite fiber contains 0.2 to 10% by mass of 0.1 to 1.2 µm fine particles.   A hollow fiber structure characterized by treating a fiber structure containing the conjugate fiber according to any one of claims 1 to 8 with water and dissolving and removing the water-soluble thermoplastic polyvinyl alcohol polymer from the conjugate fiber. Manufacturing method.

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