JP2000328368A - Composite fibers with fibrillation properties - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester fiber with a soft feeling similar to natural silk, a cross-sectional shape, and random natural spots on single fiber denier without performing an alkali treatment. I do. SOLUTION: The degree of polymerization is 200 to 500, and the degree of saponification is 90 to 90.
99.99 mol%, the molar fraction of the center hydroxyl group of three hydroxyl groups in a triad display with respect to the vinyl alcohol unit is 70 to 99.9 mol%, and the melting point is 160 to 230 ° C.
A water-soluble thermoplastic polyvinyl alcohol (A) containing 0.0003 to 1 part by weight of sodium ion and a thermoplastic polyester (B), and a composite shape of component A and component B Is a conjugate fiber having substantially the same shape in the length direction of the fiber, but randomly varying between single fibers, and having the ability to be fibrillated by post-processing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester fiber and a cloth having the property of exhibiting a soft feeling and surface appearance similar to natural silk fibers without alkali reduction.

[0002]

2. Description of the Related Art Conventionally, synthetic fibers such as polyester,
Fiber structures such as woven fabrics, knitted fabrics and non-woven fabrics made of polyamide filaments have a higher texture and luster than natural fibers such as cotton and hemp because the single filament denier and cross-sectional shape of the constituent filaments are monotonous. It was monotonous and cold, and the quality as a fiber structure was low. In recent years, various attempts have been made to improve these drawbacks, such as deforming the fiber cross section, crimping, and composite fibers, but the present situation still does not sufficiently achieve the purpose. For example, JP-A-56-
165015, JP-A-57-5921, JP-A-58-98425, JP-A-61-23901
No. 0, etc. to form a conjugate fiber of an easily soluble polymer and polyester, and then, by post-processing, to give a woven or knitted fabric with a dry touch feel or a unique luster, Or JP-B-51-7207, JP-A-58-70711, JP-A-62-1.
No. 33118, a method of improving the feel by imparting spots in the fiber length direction, or JP-B-53-35633, JP-B-56-16231.
No. 45-1807, a method of improving the feeling by fibrillating synthetic fibers as disclosed in
No. 2, Japanese Patent Application Laid-Open No. 63-6123 discloses a method for producing false twisted and fused yarns to give a hemp-like crispness, or a mixed fiber fused yarn as disclosed in JP-A-63-6123. Various methods have been proposed, such as a method or a method of fibrillation as disclosed in JP-A-63-6161.

[0003] However, many proposals often provide a desired product by an alkali weight reduction method in post-processing of fiber or fabric. The present major problem with the alkali weight reduction method is that there is a concern about adverse effects on the environment due to problems such as wastewater treatment and pollution. In addition, without performing alkali weight loss processing, there is also a proposal to use a water-soluble polyester or the like for one of the conjugate fiber components and exert the same effect as the alkali weight loss processing by performing a hot water extraction treatment in a post-processing step. There has been a problem that the biodegradability of the polymer component extracted into water is insufficient and the polymer component flows to wastewater as it is.

[0004]

SUMMARY OF THE INVENTION The inventors of the present invention have developed a feeling of softness similar to natural silk fiber and a random natural spot on the cross-sectional shape and single fiber denier of polyester synthetic fiber. As a result of intensive studies for the purpose of imparting without performing alkali weight reduction processing in the processing step, the present invention has been achieved. That is, the present invention has clarified what kind of material should be used and what kind of configuration and condition should be used in order to obtain the above fiber.

[0005]

That is, the present invention has a viscosity average degree of polymerization of 200 to 500 and a saponification degree of 90 to 99.9.
9 mol%, the molar fraction of the center hydroxyl group of three hydroxyl groups in the triad notation with respect to the vinyl alcohol unit is 70 to 99.9 mol%, and the melting point is 160 ° C. to 230 ° C.
Water-soluble thermoplastic polyvinyl alcohol (A) which is a polyvinyl alcohol having a temperature of 0 ° C. and containing 0.0003 to 1 part by weight of an alkali metal ion in terms of sodium ion.
And a composite fiber composed of thermoplastic polyester (B), wherein the weight ratio of component A to component B is 5:95 to 80:20.
And the composite shape of the component A and the component B is substantially the same in the longitudinal direction of the fiber, but varies randomly between the single fibers, and retains the ability to fibrillate by post-processing. It is. More specifically, by selectively removing water-soluble thermoplastic polyvinyl alcohol (A) by hot water treatment, ultrafine fibril-like fibers are randomly formed into a branch from the surface of the single fiber, and the fiber cross-sectional shape is reduced. Each single fiber has a different random surface irregularity irregular shape and large cracks randomly from the fiber surface to the inside of the fiber, and some cracks split the single fiber and randomly partially denier in the fiber length direction It is a conjugate fiber that retains the ability to form a mick state.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Water-soluble thermoplastic polyvinyl alcohol A (hereinafter abbreviated as PVA) used in the present invention.
The term includes not only a homopolymer of polyvinyl alcohol but also, for example, a modified polyvinyl alcohol into which a functional group is introduced by copolymerization, terminal modification, and post-reaction.

The viscosity-average degree of polymerization (hereinafter simply referred to as degree of polymerization) of PVA used in the present invention is from 200 to 500, preferably from 230 to 470, particularly preferably from 250 to 450. If the degree of polymerization is less than 200, sufficient spinnability cannot be obtained at the time of spinning, and fiberization cannot be performed. Polymerization degree 50
If it exceeds 0, the melt viscosity is too high and the polymer cannot be discharged from the spinning nozzle. Further, by using PVA having a degree of polymerization of 500 or less, that is, a so-called low degree of polymerization, not only the dissolution rate is increased when dissolving the fiber in the aqueous solution, but also the shrinkage rate when dissolving the fiber can be reduced.

The degree of polymerization (P) of PVA is determined according to JIS-K67.
26 is measured. That is, PVA is re-saponified
And purified, then the intrinsic viscosity measured in water at 30 ° C
[Η] (dl / g) is obtained from the following equation. P = ([η] × 10³/8.29)^{(1 / 0.62)}  When the degree of polymerization is in the above range, the object of the present invention is more suitably
Can be reached.

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

In the present invention, the central hydroxyl group of the triad of the triad is defined as d6-DMS of PVA.
500 MHz proton NMR in O solution (JEOL
GX-500) means a peak (I) reflecting the triad tacticity of hydroxyl protons measured at 65 ° C. Peak (I) is a triad-represented isotacticity sequence of the hydroxyl group of PVA (4.54).
ppm), heterotacticity linkage (4.36 pp)
m) and syndiotacticity linkage (4.13 pp
m), and the peak (II) of the hydroxyl group in all vinyl alcohol units has a chemical shift of 4.0.
Since it appears in the range of 5 ppm to 4.70 ppm, the molar fraction of the central hydroxyl group of three hydroxyl groups in the triad representation with respect to the vinyl alcohol unit of the present invention is 1
It is represented by 00 × (I) / (II).

In the present invention, by controlling the amount of the central hydroxyl group of the three hydroxyl groups, various physical properties relating to water such as water solubility and hygroscopicity of PVA, various physical properties relating to fiber such as strength, elongation, and elastic modulus are obtained. Various properties related to melt spinnability such as melting point and melt viscosity can be controlled. This is because the central hydroxyl group of the triad of the triad is rich in crystallinity and PVA.
It seems that the features of the above are exhibited.

In the fiber of the present invention, the content of the central hydroxyl group of three hydroxyl groups in the triad representation of PVA is 70.
９９99.9% by mole, preferably 72-99% by mole, more preferably 74-97% by mole, further preferably 75-96% by mole, particularly preferably 76-95% by mole. When the content of the central hydroxyl group of three hydroxyl groups in the triad display of PVA is less than 70 mol%, the crystallinity of the polymer is reduced, the fiber strength is reduced, and at the same time, the fibers are stuck together during melt spinning and wound up. It may not be possible to unwind later. In some cases, the composite fiber having the fibrillating ability intended in the present invention cannot be obtained. PVA
When the content of the central hydroxyl group of the three hydroxyl groups in the triad notation is more than 99.9 mol%, the melting point of the polymer is high and the melt spinning temperature must be increased. Has poor thermal stability, causing decomposition, gelling, and coloring of the polymer.

Further, the PVA of the present invention is an ethylene-modified P
In the case of VA, the effects of the present invention are further enhanced by satisfying the following expression. −1.5 × Et + 100 ≧ molar fraction ≧ −Et + 85 Here, the molar fraction (unit: mol%) represents the molar fraction of the center hydroxyl group of three hydroxyl groups in triad notation with respect to the vinyl alcohol unit, and Et is vinyl alcohol. Ethylene content (unit: mol%) contained in the copolymer
Represents

[0014] Melting point (Tm) of PVA used in the present invention
Is 160 to 230 ° C, preferably 170 to 227 ° C, more preferably 175 to 224 ° C, and 180 to 220 ° C.
C is particularly preferred. If the melting point is less than 160 ° C, PV
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 fiberization may not be possible.
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 become close to each other, so that it is impossible to stably produce the target conjugate fiber.

The melting point of PVA is raised to 250 ° C. at a rate of 10 ° C./min in nitrogen, cooled to room temperature, and then raised to 250 ° C. again at a rate of 10 ° C./min. Means the temperature at the peak top of the endothermic peak indicating the melting point of PVA in this case.

[0016] PVA is obtained by saponifying vinyl ester units. Vinyl compound monomers for forming vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl caprate, vinyl laurate, vinyl stearate,
Examples thereof include vinyl benzoate, vinyl pivalate, and vinyl versatate. Among them, vinyl acetate is preferred from the viewpoint of obtaining PVA.

The PV of the component A constituting the conjugate fiber of the present invention
The polymer A may be a homopolymer of polyvinyl alcohol or a modified PVA into which a copolymerized unit is introduced. From the viewpoint of melt spinnability, water solubility, and fiber properties, the polymer A is modified with a copolymerized unit. It is preferable to use polyvinyl alcohol. As the type of the copolymer monomer, for example,
Ethylene, propylene, 1-butene, isobutene, 1-
Α-olefins such as hexane, acrylic acid and salts thereof, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylates such as i-propyl acrylate, methacrylic acid and salts thereof, methyl methacrylate, Methacrylic esters such as ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, acrylamide, N-methylacrylamide, N
Acrylamide derivatives such as -ethylacrylamide, methacrylamide, N-methylmethacrylamide, methacrylamide derivatives such as N-ethylmethacrylamide, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n
Hydroxy ethers such as vinyl ethers such as -butyl vinyl ether, ethylene glycol vinyl ether, 1,3-propanediol vinyl ether and 1,4-butanediol vinyl ether, allyl acetate, propyl allyl ether, butyl allyl ether, hexyl allyl ether Such as allyl ethers, monomers having an oxyalkylene group, vinylsilyls such as vinyltrimethoxysilane, isopropenyl acetate, 3-buten-1-ol, 4-penten-1-ol, and 5-hexene-1-. Hydroxy-containing α-olefins such as all, 7-octen-1-ol, 9-decene-1-ol, 3-methyl-3-buten-1-ol, fumaric acid, maleic acid, itaconic acid, anhydride Maleic acid, phthalic anhydride, A monomer having a carboxyl group derived from the water trimellitic anhydride or itaconic acid, and the like;
Monomers having a sulfonic acid group derived from ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, etc .; vinyloxyethyl trimethyl ammonium chloride, vinyloxy butyl trimethyl ammonium chloride, Vinyloxyethyldimethylamine, vinyloxymethyldiethylamine, N-acrylamidomethyltrimethylammonium chloride, N-acrylamidoethyltrimethylammonium chloride, N-acrylamidodimethylamine, acryltrimethylammonium chloride, methallyltrimethylammonium chloride, dimethylallylamine, allylethylamine, etc. And a monomer having a cationic group derived from The content of these monomers is usually at most 20 mol%, more preferably at most 10 mol%.

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 having a hydroxy group such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether and 1,4-butanediol vinyl ether; allyl acetate, propyl allyl ether and 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-decene-1-ol and 3-methyl-3-buten-1-ol are preferred.

In particular, from the viewpoints of copolymerizability, melt spinnability and fibrillating ability of composite fibers, ethylene, propylene, 1-butene and isobutene having α or less carbon atoms of 4 or less, methyl vinyl ether, ethyl vinyl ether, Vinyl ethers such as n-propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether are more preferred. Units derived from α-olefins having 4 or less carbon atoms and / or vinyl ethers are
Preferably, 0.1 to 20 mol% is present in PVA, more preferably 4 to 15 mol%, and particularly preferably 6 to 13 mol%. Furthermore, in the case where the α-olefin is ethylene, the fiber physical properties increase, so that the ethylene unit is particularly preferably 4 to 15 mol%, more preferably 6 to 15 mol%.
It is preferable to use a modified PVA in which 13 mol% has been introduced.

The PVA used in the present invention includes 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 a solvent or in a solvent such as an alcohol is usually employed. Examples of the alcohol used as a 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-based initiators such as azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, and n-propylperoxycarbonate, and peroxide-based initiators Of the initiator. The polymerization temperature is not particularly limited.
A range of from 150C to 150C is suitable.

The PVA of the component A in the composite fiber of the present invention
The content of alkali metal ions in PVA (A) 1
0.000 parts by weight of sodium ion
3 to 1 part by weight, preferably 0.0003 to 0.8 part by weight, more preferably 0.0005 to 0.6 part by weight,
0.0005 to 0.5 part by weight is particularly preferred. When the content ratio of the alkali metal ion is less than 0.0003 parts by weight, the A component in the obtained fiber may not show sufficient water solubility. On the other hand, when the content of the alkali metal ion is more than 1 part by weight, decomposition and gelation during melt spinning are remarkable, and fibers cannot be formed. Examples of the alkali metal ion include a potassium ion and a sodium ion.

In the present invention, the method for incorporating a specific amount of alkali metal ions into PVA is not particularly limited.
A method of adding a compound containing an alkali metal ion after polymerizing VA, and a method of saponifying a polymer of a vinyl ester in a solvent, using an alkali substance containing an alkali ion as a saponification catalyst to thereby form an alkali metal ion in PVA. And PVA obtained by saponification
Is washed with a washing liquid to control the content of alkali metal ions contained in PVA. The latter is more preferable. The content of the alkali metal ion can be determined by an atomic absorption method.

Examples of the alkaline substance used as the saponification catalyst include potassium hydroxide or sodium hydroxide. The molar ratio of the alkaline substance used in the saponification catalyst is preferably from 0.004 to 0.5, more preferably from 0.005 to 0.05, based on the vinyl acetate unit. The saponification catalyst may be added all at once in the early stage 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,
Dimethylformamide and the like. Among these solvents, methanol is preferable, and the water content is 0.001 to 0.001.
Methanol controlled at 1% by weight is more preferable, methanol controlled at a water content of 0.003 to 0.9% by weight is more preferable, and methanol controlled at a water content of 0.005 to 0.8% by weight is particularly preferable. . Examples of the washing liquid include methanol, acetone, methyl acetate, acetate, hexane, and water. Among them, a single or mixed liquid of methanol, methyl acetate, and water is more preferable. The amount of the washing liquid is set so as to satisfy the content ratio of the alkali metal ion, but usually 300 to 10000 parts by weight with respect to 100 parts by weight of PVA, preferably 500 to 500 parts by weight.
-5000 parts by weight is more preferred. As the washing temperature,
5-80 degreeC is preferable and 20-70 degreeC is more preferable.
The washing time is preferably from 20 minutes to 10 hours, more preferably from 1 hour to 6 hours.

In addition, stabilizers such as copper compounds, coloring agents, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, flame retardants, and the like, as long as the objects and effects of the present invention are not impaired.
Plasticizers, lubricants and crystallization rate retarders can be added during the polymerization reaction or in a subsequent step. In particular, when organic stabilizers such as hindered phenol, copper halides such as copper iodide, and alkali metal halides such as potassium iodide are added as heat stabilizers, the melt retention stability during fiberization is improved. Is preferred.

If necessary, the average particle size is 0.01 μm.
Fine particles having a particle size of m to 5 μm can be added at 0.05 to 10% by weight during the polymerization reaction or in a subsequent step. The type of the fine particles is not particularly limited, and for example, inert fine particles such as silica, alumina, titanium oxide, calcium carbonate, and barium sulfate can be added. These may be used alone or in combination of two or more. . 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.

It is an important requirement of the present invention to use the PVA described above with the A component polymer. On the other hand, the thermoplastic polyester used as the B component polymer includes, for example, terephthalic acid, isophthalic acid, naphthalene-2,6-
Aromatic dicarboxylic acids such as dicarboxylic acid, phthalic acid, α, β- (4-carboxyphenoxy) ethane, 4,4′-dicarboxydiphenyl, 5-sodium sulfoisophthalic acid or adipic acid, sebacic acid, etc. Aliphatic dicarboxylic acids or their esters and ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, cyclohexane-1,4-dimethanol, polyethylene glycol, polytetramethylene glycol And a diol compound, such as a polyester, wherein at least 80 mol% of the constituent units are polyethylene terephthalate units, polybutylene terephthalate units or polyhexamethylene terephthalate units. There. The polyester may contain a small amount of additives, for example, a matting agent such as titanium oxide, an antioxidant, a fluorescent whitening agent, a stabilizer or an ultraviolet absorber.

As a method for forming the desired composite fiber structure, a form in which the two components of the A component polymer and the B component polymer are mixed in a non-uniform state to the extent that the two-component polymer remains aggregated is maintained. The most important point is that the fibers are formed while the fibers are formed. FIG. 1 shows an example of a composite fiber cross-sectional shape. This is an example in which fibers are formed into a round cross-sectional shape at a composite weight ratio of the A component polymer and the B component polymer of 50:50.

Next, a production example of the polyester fiber of the present invention will be described. In order to develop the composite fiber structure of the present invention, two kinds of the A component polymer and the B
It is important that the polymer of the component remains in a state in which the respective polymers are aggregated to some extent, that is, while maintaining a non-uniformly mixed state, it is important that such a spinning method be used.
For example, spinning may be performed using a mixed spinneret as shown in FIG. The melt flows of the A component polymer and the B component polymer respectively extruded from the separate melt extruders are separately weighed by a measuring device in a predetermined amount, and then introduced from the introduction holes 2 and 3 of the introduction plate 1, respectively. 4 and 5 are mixed under predetermined conditions by a static mixer 11, are filtered by a filtration unit 12 of a sandbox 7 through an intermediate plate 6, and then are filtered through a filter 8 and a rectifying plate 9 to form a die plate 1.
Spun from zero.

Here, the two-component polymer is in a heterogeneous mixed state.
In order to make the number of mixing elements of the static mixer 11 appropriate,
It is very important to choose. Quiz currently in practical use
There are several types of static mixers, for example, Noritake 180
° n elements with blades twisted to the left and right
2 ⁿStatic type of layer division
When a mixer is used, the number of elements is in the range of 3 to 15.
Must be enclosed. More preferably, the range of 4 to 8 is the most preferable.
Suitable. When the number of elements is 16 or more, A component polymer
-Mixing property of B-component polymer is too good and uniform
The mixture becomes close to the mixture and becomes a fiber.
It becomes difficult to develop a fiber structure. Also, anti-polyester
As the reaction progresses, gelation occurs and yarn breakage frequently occurs.

A present in a non-uniformly dispersed state in post-processing
By removing the component polymer as selectively as possible, the ultrafine fibril-like fibers are formed in a branch shape at random from the surface layer of the single fiber, and the fiber cross-sectional shape varies randomly between the single fibers, and the irregular surface irregular shape has a large size. It can be said that cracks are randomly formed from the fiber surface to the inside of the fiber, and that a part of the crack divides the single fiber to form a partially denier mixed state at random in the fiber length direction.

When the number of elements is large, the A component polymer and the B component polymer are close to the molecular mixture, and it is difficult to elute and remove the A component polymer as an aggregate, so that it is difficult to obtain a desired fiber structure. On the other hand, if the number of elements is too small, mixing becomes insufficient and not only a fiber having a desired good texture cannot be obtained, but also the spinning processability becomes unstable, which is not preferable. When a static mixer other than Noritake is used, it is needless to say that it is necessary to use a mixer set to the number of elements corresponding to ²ⁿ layer division or more. Toray High Mixer (Hi-Mix
er) and Charles and Ross (Charles)
& Ross) Ross ISG mixer etc.
Since the number of layers divided when passing through the elements is ⁴ⁿ layers, it is preferable that the number of elements be 2 or more and 8 or less.

The composite ratio of the component A polymer and the component B polymer must be in the range of 5:95 to 80: 20% by weight. The composite ratio of PVA as the component A polymer is 5% by weight
If it is less than this, a desired composite fiber having sufficient fibrillation performance cannot be obtained, which is not preferable. Also 80
Exceeding the weight percentage is undesirable because the spinning processability and the stretching processability decrease. In the range of 5 to 80% by weight, it is desirable to comprehensively judge the target conjugate fiber, processability, cost increase, and the like, and select an optimum conjugate ratio.

The melting point Tm of the PVA of the component A polymer in the present invention is determined by a differential scanning calorimeter (DSC; for example, Mett).
(Ler, TA3000). Further, PVA used in the present invention has biodegradability, and is decomposed into water and carbon dioxide when treated with activated sludge or buried in soil. When PVA is continuously treated with activated sludge in the form of an aqueous solution, it is almost completely decomposed in 2 days to 1 month. From the viewpoint of biodegradability, the saponification degree of the PVA is preferably 90 to 99.99 mol%, and 92 to 9 mol%.
9.98 mol% is more preferable, and 93 to 99.97 mol% is particularly preferable. The 1,2-glycol bond content of the PVA is preferably 1.2 to 2.0 mol%,
5 to 1.95 mol% is more preferable, and 1.3 to 1.9 mol% is particularly preferable. When the 1,2-glycol bond amount of PVA is less than 1.2 mol%, not only the biodegradability of PVA is deteriorated, but also the melt viscosity is too high, and the spinnability may be deteriorated. When the 1,2-glycol bond content of PVA is 2.0 mol% or more, the thermal stability of PVA may be deteriorated and spinnability may be reduced. 1,2 of PVA
The glycol bond content can be determined from the NMR peak. After saponification to a degree of saponification of 99.9 mol% or more, the sample was thoroughly washed with methanol, dried at 90 ° C. under reduced pressure for 2 days, dissolved in DMSO-D6, and added with a few drops of trifluoroacetic acid. NMR
(JEOL GX-500) at 80 ° C. The peak derived from methine in the vinyl alcohol unit is 3.2.
ピ ー ク 4.0 ppm (integral value A), a peak derived from one methine of 1,2-glycol bond is attributed to 3.25 ppm (integral value B), and the 1,2-glycol bond content can be calculated by the following equation. . Here, Δ represents the amount of modification (mol%). 1,2-glycol bond content (mol%) = B (100
-Δ) / A The yarn discharged from the spinning nozzle is wound up at high speed without stretching or stretched as needed. Stretching is performed at a temperature equal to or higher than the glass transition point (Tg) at a stretching ratio of elongation at break (HDmax) × 0.55 to 0.9 times. If the draw ratio is less than HDmax × 0.55, a fiber having sufficient strength cannot be obtained stably, and if the draw ratio exceeds HDmax × 0.9, thread breakage tends to occur. The stretching may be carried out once after being wound up after being discharged from the spinning nozzle, or may be carried out subsequent to the stretching. In the present invention, any method may be used. The 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.

An oil agent is usually applied to the spun fibers. However, since the component A polymer of the present invention is water-soluble and has high hygroscopicity, it is preferable to apply a water-free straight oil agent. The oil agent component is composed of an electrostatic agent component and a leveling agent component that do not contain water. For example, polyoxyethylene lauryl phosphate diethanolamine salt, polyoxyethylene cetyl phosphate diethanolamine salt,
Alkyl imidazolium ethosulfate, polyoxyethylene lauryl amino ether cationized product, sorbitan monostearate, sorbitan tristearate,
Polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, glyceride stearate, polyoxyethylene stearyl ether, polyethylene glycol stearate, polyethylene glycol alkyl ester, polyoxyethylene caster wax, propion oxide / ethylene oxide (PO / EO) random ether, PO / EO
It is possible to use a compound selected from block ether, PO / EO-modified silicone, coconut fatty acid diethanolamide, polymer amide, butyl cellosolve, mineral oil and neutral oil. The method of applying the oil agent may be a usual method using a roller touch or a bird mouth.

The take-up speed differs depending on whether the film is wound and then stretched once, when it is spun and wound in one step of direct spinning and wound, or when it is wound at high speed without stretching. , Approximately 500m / min to 7000m
/ Minute can be fiberized. Spinning at less than 500 m / min is not impossible, but has little significance in terms of productivity. On the other hand, at an ultra-high speed exceeding 7000 m / min, fiber breakage is likely to occur.

The cross-sectional shape of the conjugate fiber of the present invention (FIG. 1) after heat treatment (boil × 60 minutes) in the post-processing step is, for example, as shown in FIG. Have different random irregularities on the surface and randomly have large cracks from the fiber surface to the inside of the fiber, and partially crack the single fiber to form a kind of denier mixed state You can see that.
In addition, it has been confirmed by detailed observation that the denier mix state occurs randomly in the fiber length direction instead of the same state. A fiber aggregate having such a structure is not a synthetic fiber obtained by conventional melt spinning at all only by heat treatment, and is provided for the first time by the present invention. As a result, it has become possible to obtain natural fibers, which have been insufficient with conventional synthetic fibers produced by melt spinning, and in particular, a feeling similar to natural silk fibers. In particular, it is the first time that it is possible to impart a natural fiber surface appearance that is not seen in conventional polyester fibers and to maintain random natural inhomogeneity. It can be said that polyester fibers very similar to the above were made.

FIG. 4 shows an enlarged photograph of a cross section of the plain woven fabric comprising the composite fiber of the present invention after the plain woven fabric is subjected to hot water treatment in post-processing.
It can be seen that countless ultrafine yarns are floated on the surface of the woven fabric and are three-dimensionally formed, and it can be understood that the woven fabric has a fiber structure that could not be seen in a conventional polyester plain woven fabric. As an example, a woven fabric using long fibers has been described, but it is needless to say that the same effect can be expected with short fibers. Similarly, the surface of the knitted fabric after the hot water treatment of the knitted fabric composed of the conjugate fiber of the present invention is shown in FIG. 5, and it can be confirmed that the fiber surface is fibrillated similarly to the woven fabric.

In the present invention, the fiber cross-section becomes similar to a pentagonal or hexagonal shape by higher-order processing such as false twist crimping, or a three-leaf, T-shaped or
The shape of the present invention can be improved as long as the above-described composite form is expressed as a multi-lobe or various cross-sectional shapes such as a four-lobe, a five-lobe, a six-lobe, a seven-lobe, and an eight-lobe. It can be a polyester fiber having a good feeling.

In the conjugate fiber of the present invention produced as described above, the water-soluble thermoplastic polyvinyl alcohol is easily and selectively removed by hot water treatment, and the ultrafine fibril-like fibers are randomly branched from the surface of the single fiber. And random cross-sectional shapes of the fibers differing between the single fibers, and random irregular shapes and large cracks are randomly generated from the fiber surface to the inside of the fiber. Since it is possible to form a partially denier state at random in the direction of the fabric, for various types of clothing, woven or knitted fabric for non-clothing, when used as a fabric such as a nonwoven fabric, a soft texture similar to natural silk or A natural plaque can be developed.

[0040]

EXAMPLES Next, the present invention will be described specifically with reference to Examples.
The present invention is not limited to these examples. In the examples, parts and percentages relate to weight unless otherwise specified.

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

[Proportion of Three-Hydroxy Group in Triad Representation of PVA] After saponification of PVA to a saponification degree of 99.5 mol% or more, it was thoroughly washed with methanol, and then dried at 90 ° C. under reduced pressure for 2 days using PVA. , D6-DMSO and then 500 MHz proton NMR (JEO
(LGX-500) device. P
The peak derived from the hydroxyl group of the vinyl alcohol unit in VA has a chemical shift of 4.05 ppm to 4.70 ppm.
And the integral value is defined as the vinyl alcohol unit amount (II). The center hydroxyl group of the three hydroxyl groups in the triad representation of PVA appears at 4.54 ppm in the case of the isotacticity chain, 4.36 ppm in the case of the heterotacticity chain, and 4.13 ppm in the case of the syndiotacticity chain. The sum of the three integrated values is defined as the central hydroxyl group amount (I) of three hydroxyl groups in triad display. The molar fraction of the central hydroxyl group of the triad of the hydroxyl group with respect to the vinyl alcohol unit of the PVA of the present invention is expressed by 100 × (I) / (II).

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

Example 1 [Production of ethylene-modified PVA] 29.0 kg of vinyl acetate and methanol 3 were placed in a 100-L pressure reactor equipped with a stirrer, a nitrogen inlet, an ethylene inlet and an initiator inlet.
After 1.0 kg was charged and the temperature was raised to 60 ° C., the inside of the system was replaced with nitrogen by bubbling nitrogen for 30 minutes. Then, ethylene was introduced and charged so that the reaction tank pressure became 5.9 kg / cm ² . A 2.8 g / L solution of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol was prepared as an initiator,
Nitrogen was replaced by bubbling with nitrogen gas. After adjusting the internal temperature of 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 reactor pressure at 5.9 kg / cm ² and the polymerization temperature at 60 ° C.
The polymerization was carried out by continuously adding AMV at a rate of ml / hr. 1
After 0 hour, when the degree of polymerization reached 70%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled through to completely remove ethylene. Next, 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 a concentration of 50% by adding methanol to the obtained polyvinyl acetate solution.
(100 g of polyvinyl acetate in solution) to 46.5 g
(Molar ratio (MR) 0.10 to polyvinyl acetate unit of polyvinyl acetate) (10% of NaOH)
(Methanol solution) for saponification. In about 2 minutes after the addition of the alkali, the gelled system was crushed with a crusher,
After being left at 60 ° C. for 1 hour to progress saponification, 1000 g of methyl acetate was added to neutralize the remaining alkali. After confirming the completion of the neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration and washed at room temperature for 3 hours. After repeating the above washing operation three times, the PV obtained by centrifugal drainage was obtained.
A was left in a dryer at 70 ° C. for 2 days to obtain dried PVA.

The resulting ethylene-modified PVA had a degree of saponification of 9
It was 8.4 mol%. After the modified PVA was incinerated, the content of sodium measured by an atomic absorption spectrophotometer using a substance dissolved in an acid was 0.03 parts 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 reprecipitated by dissolving with acetone three times, and then dried under reduced pressure at 80 ° C. for 3 days. To obtain purified polyvinyl acetate. The polyvinyl acetate was dissolved in DMSO-d6, and 500 MHz proton N was dissolved.
When measured at 80 ° C. using MR (JEOL GX-500), the ethylene content was 10 mol%.
After saponifying the above methanol solution of polyvinyl acetate at an alkali molar ratio of 0.5, the pulverized product was left at 60 ° C. for 5 hours to progress saponification, and then methanol soxhlet was carried out for 3 days, and then 80 ° C. And dried under reduced pressure for 3 days to obtain a purified ethylene-modified PVA. The average degree of polymerization of the PVA was 330 as measured according to the conventional method of JIS K6726. The amount of 1,2-glycol bond and the content of hydroxyl groups of three hydroxyl groups of the purified PVA were 50
00 MHz proton NMR (JEOL GX-500)
It was 1.50 mol% and 83%, respectively, as determined from the measurement by the apparatus as described above. Further, a 5% aqueous solution of the purified modified PVA was adjusted to prepare a cast film having a thickness of 10 μm. 80
After drying under reduced pressure at 1 ° C. for 1 day, PVA was obtained by the above-described method using DSC (Mettler, TA3000).
Was 206 ° C. (Table 1).

[0046]

[Table 1]

The modified PVA obtained above was melt-kneaded at 240 ° C. using a melt extruder, the molten polymer stream was guided to a spinning head, weighed with a gear pump, and used as a composite nozzle jet as a component A polymer of the composite polymer stream. Introduced into the pack. On the other hand, as a B-component polymer, a 10 mol% modified isophthalic acid-modified polyethylene terephthalate polymer was prepared by a conventional method, melt-extruded at 260 ° C. using another melt extruder, and introduced into a composite nozzle jet pack.
After weighing each so that the composite ratio of A to B becomes 30 to 70% by weight, the mixture is supplied to a spinning pack, and then, in a spinning pack according to the method shown in FIG. 2, an 8-element static mixer manufactured by Noritake Co., Ltd. With each B polymer,
The kneaded mixture was non-uniformly kneaded to such an extent that the aggregation state of the A polymer was recognized (the cross-sectional structure shown in FIG. 2), and then discharged from a round hole nozzle and spun. The spun yarn was drawn by a roller plate method under ordinary conditions to obtain a 75dr-36f multifilament. The spinnability and stretchability were good and there was no problem at all.
The obtained multifilament was used as a warp and a weft to fabricate a 1/1 plain woven fabric. The weaving process could be performed without any problem. After the scouring relaxation treatment of the obtained plain fabric, the boil treatment was performed for 60 minutes. As a result, the A component polymer was selectively eluted, and the fiber cross-sectional structure as shown in FIG. 3 was obtained.
A fabric having a very good feeling was obtained, and a fabric similar to natural silk fibers having a soft feeling not seen with conventional polyester fabrics was obtained. When the fibers constituting the woven fabric were observed with a microscope and a scanning electron microscope, the ultrafine fibril-like fibers were randomly formed in a branch shape from the surface of the single fiber, and the fiber cross-sectional shape was as shown in FIG.
Each fiber has a different random surface irregularity and irregular shape, large cracks from the fiber surface to the inside of the fiber randomly, and partially cracks the single fiber to randomize partially in the fiber length direction in a denier mixed state Was formed.

Examples 2-5 In place of the A-component polymer PVA used in Example 1, Table 1
The composite fiber was obtained by the same method as in Example 1 under the same conditions as in Example 1 except for using PVA shown in (1) above, and a plain fabric was prepared by the same method, followed by hot water treatment. A woven fabric having a woven fabric surface and having a good feeling was obtained.

Examples 6 to 8 In Example 6, polybutylene terephthalate was used as the component B polymer, in Example 7, polyhexamethylene terephthalate was used, and in Example 8, polyethylene terephthalate was used. A composite fiber was obtained in the same manner as in Example 1 except that the spinneret temperature was changed, and a plain woven fabric was prepared in the same manner. Then, hot water treatment was performed. A woven fabric having a woven fabric surface and having a good feeling was obtained.

Examples 9 to 12 Using the same polymer as in Example 1, Examples 9 and 10
The compound ratio of the component and the component B is 10/90, 70 /
As Example 30, conjugate fibers were obtained in the same manner as in Example 1 except that the number of static mixer elements was changed to 12, 4 in Examples 11 and 12, respectively. In each case, the processability was good and the fabric after the hot water treatment had a characteristic and good texture.

Comparative Examples 1 to 5 Composite PVA was carried out in the same manner as in Example 1 except that PVA shown in Table 1 was used instead of PVA used in Example 1. In Comparative Examples 1 and 4, the melt viscosity of PVA as the component A polymer was too high, the formation of a composite stream with the component B polymer became unstable, and stable spinning yarn could not be collected. Spinning temperature 2
When the temperature was further raised from 60 ° C., thermal decomposition and gelation of PVA occurred, and it was not possible to wind the spun yarn for a long time. Comparative Example 2
For PVA, the melt viscosity of PVA was too low, and the spinnability was poor, and single yarn breakage occurred frequently. In Comparative Example 3, the PVA was thermally decomposed and gelled, and the spinnability was poor and could not be wound. Comparative Example 5 is PV
It is presumed that the crystallinity of A was lowered. Part of the spun yarn was stuck due to heat or moisture absorption and the yarn could not be stably unwound, resulting in poor stretchability.

Comparative Examples 6 to 9 In Comparative Examples 6 and 7, the same polymer combination as in Example 1 was used, and the compounding ratio was 3/97, 85/15, respectively, and fiberization was carried out under the same other conditions. did. Comparative Example 6
Although the processability was good and there was no problem, the texture of the obtained woven fabric after the hot water treatment had few characteristics, and a favorable one was not obtained. In Comparative Example 7, the spinning properties were unstable, the single yarn breakage due to screw drop was large, and a good spun yarn was not obtained. Therefore, there were many troubles in both stretchability and weaving properties, and a woven fabric capable of evaluating the hand could not be obtained. Comparative Example 8,
Reference numeral 9 denotes a polymer combination similar to that of Example 1 and a similar compounding ratio. The number of elements of the static mixer was 25 and 3, respectively, and fiberization was performed under the same other conditions. In Comparative Example 8, the A polymer and the B polymer were mixed too uniformly, the reaction proceeded partially between both components, gelation occurred, and single yarn breakage during spinning frequently occurred. The texture of the obtained fabric was a fabric texture with less features compared to Example 1 because the A polymer was not easily removed during the hot water treatment. In Comparative Example 9, contrary to Comparative Example 8, the mixing was insufficient, so that the balance of the composite flow of the A polymer and the B polymer became unstable, the spinnability was poor, and a single yarn break occurred. Therefore, stretchability and weaving properties were slightly poor. The feeling of the obtained woven fabric was slightly inferior to that of Example 1, and when the fiber surface was observed with a scanning electron microscope, the state of formation of the branch-like ultrafine fibril fibers generated from the surface of the single fiber was very small, We were not at a satisfactory level.

Comparative Example 10 The same polymer as in Example 1 was used, and the ratio of the A polymer to the B polymer was 50:50. . The obtained yarn was similarly subjected to woven fabric evaluation, but the feeling was not at a satisfactory level.

[0054]

According to the present invention, two types of polymers, polyvinyl alcohol and polyester, satisfying a specific condition are subjected to composite spinning by a method satisfying a predetermined condition, so that the composite shape is substantially in the longitudinal direction of the fiber. It is possible to obtain special conjugate fibers that are randomly different between single fibers even though they have the same shape, and to develop natural spots and soft soft feeling similar to natural fibers by treating the fibers with hot water. Can be.

[Brief description of the drawings]

FIG. 1 is a photograph showing an example of a composite form in a fiber cross section of the composite fiber of the present invention.

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

FIG. 3 is a photograph showing an example of a fiber cross section after subjecting the conjugate fiber of the present invention to hot water treatment.

FIG. 4 is a photograph showing an example of a woven fabric surface after a hot water treatment of a plain woven fabric made of the conjugate fiber of the present invention.

FIG. 5 is a photograph showing an example of the surface of a knitted fabric made of the composite fiber of the present invention after hot water treatment.

[Explanation of symbols]

 1: Introducing plate 2, 3: Polymer introducing hole 4, 5: Mixing plate 6: Intermediate plate 7: Sandbox 8: Filter 9: Rectifying plate 10: Base plate 11: Static mixer 12: Filtration unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4L041 AA07 BA04 BA05 BA18 BC13 BC20 BD14 CA08 CA44 CA55 CA61 DD01 DD06 DD14 EE02 EE05 EE08 EE14 EE20

Claims (3)

[Claims] 1. A viscosity-average degree of polymerization of 200 to 500, a saponification degree of 90 to 99.99 mol%, and a molar fraction of three hydroxyl group-centered hydroxyl groups in a triad display with respect to a vinyl alcohol unit of 70 to 99.9 mol. %, And a melting point of 160 to 230 ° C. in polyvinyl alcohol,
And the alkali metal ion is 0.1 in terms of sodium ion.
Water-soluble thermoplastic polyvinyl alcohol (A) and thermoplastic polyester (B) contained in 0003 to 1 part by weight
Wherein the weight ratio of the A component and the B component is in the range of 5:95 to 80:20, and the composite shape of the A component and the B component is substantially the same in the longitudinal direction of the fiber. A conjugate fiber that varies randomly between single fibers but retains the ability to fibrillate by post-processing. 2. The conjugate fiber according to claim 1, wherein the polyvinyl alcohol is a modified polyvinyl alcohol containing 0.1 to 20 mol% of α-olefin units and / or vinyl ether units having 4 or more carbon atoms. 3. The conjugate fiber according to claim 2, wherein the polyvinyl alcohol is a modified polyvinyl alcohol containing 4 to 15 mol% of ethylene units.