JP2006299474A - Extra fine melt anisotropic aromatic polyester fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a texture by ultrafinening to a single yarn fineness of 1.0 dtex or less in a melt-anisotropic aromatic polyester fiber having high strength and high elasticity, which has been difficult until now, especially in apparel applications. Disclosed is a melt-anisotropic aromatic polyester fiber that can be used for protective clothing such as a bulletproof clothing, blade-proof clothing, and ice pick clothing.
SOLUTION: A sea-island type in which a melt anisotropic aromatic polyester is an island component, an easily alkali-reducible polyester is a sea component, and a mass ratio of the sea component to the island component is sea: island = 10: 90 to 50:50. A melt anisotropic aromatic polyester fiber obtained by subjecting a composite fiber to an alkali weight loss treatment, a single yarn fineness after the alkali weight loss treatment of 0.1 to 1.0 dtex, and a fiber strength after heat treatment of 20 cN / dtex or more.
[Selection figure] None

Description

  The present invention relates to a sea-island type composite fiber comprising a melt-anisotropic aromatic polyester as a component, and is characterized by high strength and high elastic modulus regardless of fineness. The present invention relates to a melt-anisotropic aromatic polyester fiber that can be used as a protective material such as ice-pick clothes and has a good texture when made into clothes and the like, and a method for producing the same.

  It is known that the melt anisotropic aromatic polyester fiber has a molecular chain highly oriented in the fiber axis direction and has a high strength and a high elastic modulus (for example, see Patent Document 1). Melt anisotropic aromatic polyester fibers are highly oriented in the spinning process and are composed of rigid molecules, so that subsequent stretching is almost impossible. Therefore, in order to reduce the fineness of the fiber, the target fiber was obtained by reducing the nozzle hole diameter at the time of spinning. However, in this method of reducing the nozzle hole diameter, the nozzle hole processability and cleanability, and From the viewpoint of the stability of the spinning process, the pore diameter is limited to about 0.06 mm, and the fineness of the obtained fiber is limited to 2 to 5 dtex.

  In addition, a method is known in which a melt anisotropic aromatic polyester fiber is used as a core, and the texture is improved by coating the periphery of the fiber with an extremely fine melt anisotropic aromatic polyester fiber (for example, Patent Document 2). reference.). However, even if the tactile sensation can be improved by the method of Patent Document 2, the fineness of the core yarn itself remains thick, so that the sensation of knitting is not completely eliminated.

JP 61-174408 A JP 7-316926 A

  The object of the present invention is to make the single yarn fineness to 1.0 dtex or less in a high-strength and high-modulus melt-anisotropic aromatic polyester fiber, which has been difficult to make ultra-fine until now, and has been particularly restricted in clothing applications. The object is to obtain a melt-anisotropic aromatic polyester fiber having a good texture and capable of being used in protective clothing applications such as bulletproof clothing, blade-proof clothing, and ice pick clothing.

As a result of intensive studies by the inventors to achieve the above object, a sea-island composite fiber having an easily alkali-reducible polyester as a sea component and a melt-anisotropic aromatic polyester as an island component is wound around cheese, and its cheese form It was found that a melt anisotropic aromatic polyester fiber having a single yarn fineness of 0.1 to 1.0 dtex and a strength after heat treatment of 20 cN / dtex or more can be obtained by carrying out the alkali weight loss treatment.
That is, the present invention relates to a sea island in which the melt anisotropic aromatic polyester is an island component, the easily alkali-reducible polyester is a sea component, and the mass ratio of the sea component to the island component is sea: island = 10: 90 to 50:50. A melt-anisotropic aromatic polyester fiber having a single fiber fineness of 0.1 to 1.0 dtex after alkali weight reduction treatment and a fiber strength after heat treatment of 20 cN / dtex or more. There is a method for producing a melt-anisotropic aromatic polyester fiber, characterized in that the sea-island type composite fiber is wound around cheese, subjected to alkali weight loss treatment in the form of cheese, and the easy alkali weight loss polyester is dissolved and removed. .

  The fiber obtained in the present invention has a high strength, a high elastic modulus, excellent chemical resistance, and a fineness of single yarn fineness of 1.0 dtex or less. Widely used in clothing.

  The melt anisotropic aromatic polyester used for the island component in the present invention is an aromatic polyester exhibiting optical anisotropy (liquid crystallinity) in the melt phase. For example, a sample is placed on a hot stage and raised in a nitrogen atmosphere. It can be recognized by heating and observing the transmitted light of the sample. The melt anisotropic polyester used in the present invention is composed mainly of repeating structural units of aromatic diol, aromatic dicarboxylic acid, and aromatic hydroxycarboxylic acid. The thing which becomes.

  Particularly preferred is a polymer comprising a combination of repeating constitutional units shown in the following chemical formula 2, and further preferred is a polymer in which the portion comprising the repeating constitutional units (A) and (B) is 65% or more. It is preferable that it is an aromatic polyester (11) whose component of B) is 4-45 mol%.

  It is preferable that melting | fusing point (MP) of the melt anisotropic aromatic polyester used suitably by this invention is 260-380 degreeC, More preferably, it is 270-350 degreeC. The melting point here is the main absorption peak temperature measured and observed with a differential scanning calorimeter (DSC; “TA3000” manufactured by METTLER) according to JIS K7121 test method. Specifically, when measuring with a DSC apparatus, 10 to 20 mg of a measurement sample is taken and sealed in an aluminum pan, then nitrogen is supplied as a carrier gas at a flow rate of 100 cc / min, and the temperature is increased at 20 ° C./min. The absorption peak of is measured. If a clear absorption peak does not appear in the above-mentioned 1st run depending on the type of polymer, the temperature is raised to a temperature 50 ° C. higher than the expected flow temperature at a temperature increase rate of 50 ° C./min, and at that temperature for 3 minutes or more. After being held and completely dissolved, it is cooled to 50 ° C. at a rate of 80 ° C./min, and then an endothermic peak is measured at a rate of temperature increase of 20 ° C./min.

  The polymer used for the sea component is not particularly limited as long as it is an easily alkali-reducing polyester, but has a high alkali decomposition rate, that is, 1000 times or more of the melt anisotropic aromatic polyester used, more preferably 3000. A polyester having a double alkali decomposition rate is preferred. Specific examples include polyesters containing structural units (I) to (III) represented by the following chemical formula 3.

  The copolymer polyester containing the structural units (I) to (III) has good spinnability with the melt-anisotropic aromatic polyester and is excellent in alkali weight loss. The alkali decomposition rate of the copolymerized polyester is 3000 times or more larger than that of the melt-anisotropic aromatic polyester, and the weight reduction treatment with an alkali solution can be performed in a short time. For this reason, the melt-anisotropic aromatic polyester is hardly subject to deterioration or erosion by alkali, and a fiber excellent in strength and texture can be obtained.

  From the viewpoint of alkali decomposability and spinnability, 0.5 to 10 mol% of the total acid component constituting the polyester is the structural unit (I), and the total content of the structural units (II) and (III) is 2 of the polyester. It is more preferable to use a copolyester of ˜50% by mass. Furthermore, 1 to 7 mol% of the total acid component constituting the polyester is used as a copolymer polyester in which the total content of the structural units (I) and the structural units (II) and (III) is 5 to 30% by mass. Is preferred. It is also possible to improve heat resistance by adding a commercially available oxidative decomposition inhibitor (for example, “Irganox 1010” manufactured by Ciba-Gaykey, Inc., “Sianox 1790” manufactured by American Cyanamid).

  Examples of the trivalent aromatic group (Ar) in the dicarboxylic acid unit (I) include a benzenetriyl group and a naphthalenetriyl group, and the metal atom (M) is an alkali metal atom such as sodium, potassium or lithium. It is preferable that The copolyester may have a plurality of dicarboxylic acid components (I). Other carboxylic acid units constituting the copolyester include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, 6-hydroxyethoxybenzoic acid, p-oxybenzoic acid. An aromatic hydroxycarboxylic acid such as aliphatic dicarboxylic acid, alicyclic carboxylic acid, tricarboxylic acid and the like may be used, and a plurality of these carboxylic acid units may be used. In particular, 70 mol% or more of all acid component units constituting the copolymer polyester are preferably aromatic dicarboxylic acid units, particularly terephthalic acid units.

R ¹ in the diol unit (II) is preferably an alkylene group having 1 to 4 carbon atoms, specifically an ethylene group and / or a propylene group, and particularly an ethylene group from the viewpoint of alkali solubility. It is preferable. The average degree of polymerization m is preferably 10 to 100, more preferably 20 to 80. If m is less than 10, the alkali solubility is low, and if it exceeds 100, the alkali solubility does not improve so much, but rather a problem of coloring tends to occur. Specifically, the diol unit (II) is preferably a unit derived from polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene / polyoxypropylene glycol, etc., and these diol units (I) are added to the copolyester. A plurality of may be included. Moreover, it is preferable that the copolyester further has other diol units, and examples thereof include aliphatic diols and alicyclic diols, and a plurality of these diol units may be included. In particular, a unit derived from a linear alkylene glycol having 2 to 6 carbon atoms is preferable from the viewpoint of fiber formation.

R ² in the side chain unit (III) is preferably an alkylene group having 1 to 4 carbon atoms, specifically an ethylene group and / or a propylene group, particularly preferably an ethylene group.
Further, as ^{R 3} can be increased to a straight-chain or branched alkyl group, a cycloalkyl group having 3 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms having 1 to 15 carbon atoms. The degree of polymerization n is preferably in the range of 10 to 100, more preferably 20 to 80. If n is less than 10, the alkali solubility is lowered, and if it exceeds 100, the alkali solubility is not improved so much, but rather causes coloring. Specifically, the side chain unit (III) is polyoxyethylene glycol-alkyl-glycidyl ether, polyoxyethylene glycol-alkyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-phenyl-glycidyl ether, polyoxyethylene glycol. -Phenyl-2,3-dihydroxypropyl ether, polyoxyethylene glycol-cyclohexyl-glycidyl ether, polyoxyethylene glycol-cyclohexyl-2,3-dihydroxypropyl ether and the like, and these units are included in the copolyester (A). A plurality of may be included.

  The sea component easy alkali weight loss polyester and the island component melt anisotropic aromatic polyester are polyethylene naphthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene as long as the effects of the present invention are not impaired. Sulfide, polyether ether ketone, fluororesin, etc. may be added. Further, it may contain various additives such as inorganic substances such as titanium oxide, silica and barium sulfate, carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers and light stabilizers.

The sea-island fiber referred to in the present invention has several to several tens of islands in the sea component serving as a matrix in the cross section of the fiber, and this sea-island structure is continuous endlessly in the fiber axis direction. State.
On the other hand, since the ratio of the easily degradable polyester constituting the sea component is finally decomposed and removed, the mass ratio of the sea component to the island component is set to sea: island = 10 for complete division. : 90-50: 50 is required. If the mass ratio of the island exceeds 90, the structure of the composite nozzle for spinning the island becomes complicated, and the cost increases, which is not preferable. When the mass ratio of the sea exceeds 50, the island component cannot be sufficiently divided. Preferably it is 20: 80-40: 60, More preferably, it is 25: 75-35: 65. The number of islands made of melt-anisotropic aromatic polyester can be freely set according to the intended single yarn fineness and yarn fineness.

  The composite fiber of the present invention already has sufficient strength and elastic modulus only by spinning, but the performance can be further improved by relaxation heat treatment or tension heat treatment. The heat treatment can be performed in an inert gas atmosphere such as nitrogen, an active gas atmosphere containing oxygen such as air, or under reduced pressure. The heat treatment atmosphere is preferably a low humidity gas having a dew point of −80 ° C. or lower. Preferable heat treatment conditions include a temperature pattern in which the temperature is gradually increased from the melting point of the island component to −40 ° C. or less. The processing time is several minutes to several tens of hours depending on the purpose. The supply of heat includes a method using a medium such as a gas, a method using radiation by a heating plate, an infrared heater, etc., a method in contact with a heating roller, a heating plate, etc., an internal heating method using a high frequency, etc. . The processing is performed under tension or no tension depending on the purpose. The processing shape may be a casserole shape, a tow shape, or a continuous treatment between rollers. The tension heat treatment is preferably performed by applying a tension of 1 to 10% of the cutting temperature at a melting point of the island component of −80 ° C. or less, and this treatment particularly improves the elastic modulus.

  As a method for obtaining ultrafine fibers, it is common practice to dissolve / decompose and remove sea components of sea-island composite fibers, leaving only the island components. The melt anisotropic aromatic polyester fiber of the present invention is almost impossible to stretch after spinning due to its liquid crystallinity, and heat treatment is required to obtain high strength. Is essential. The heat treatment is usually performed in the yarn state, but the weight reduction process must be performed before the heat treatment, so the weight reduction process must be performed in the yarn state. Although it is possible to carry out a weight reduction treatment and a heat treatment after weaving and knitting first, it is necessary to weave and knitting as densely as possible when the fibers of the present invention are used particularly for protective clothing. . If a woven or knitted fabric is made first and then reduced in weight, the texture is improved, but it is difficult to obtain a high density. Therefore, it is necessary to perform weight reduction and heat treatment in the yarn state.

When the alkali weight loss treatment is performed in a yarn state, the weight loss treatment is preferably performed in a shape wound around cheese. It is possible to keep the yarn in the alkaline liquid for a certain period of time while running with a roller, and to treat it continuously, but if it has a certain length of residence time, the equipment will be long and the weight will be reduced. Due to its thinness, the fibers that are extremely fine are likely to be wound around a roller or the like, and are prone to process trouble. For these reasons, the alkali weight loss treatment is preferably performed in a cheese winding shape.
The alkali weight loss treatment in the present invention is a treatment with a strong alkali solution mainly composed of sodium hydroxide, potassium hydroxide or the like, and 2 to 60 g / l in terms of alkali solubility and fiber erosion, Preferably, the alkali treatment is performed in an alkaline solution of 3 to 20 g / l. When a weak alkaline substance such as sodium carbonate, sodium silicate, or sodium dihydrogen phosphate is used, the alkali substance concentration in the treatment liquid is 5 to 200 g / l, preferably 5 to 60 g / l. Further, the processing solution may contain a decomposition accelerator. Further, it is preferable to add a cationic surfactant because the alkali permeation of the fiber is promoted. The alkali treatment temperature is preferably in the range of 70 to 130 ° C. If the treatment temperature is less than 70 ° C., it takes a long time for the alkali treatment, and if it exceeds 130 ° C., the melt-anisotropic aromatic polyester tends to be eroded and deteriorated. It is preferable to carry out neutralization and water-washing drying treatment after dividing the fiber by alkali treatment.

In the present invention, as described above, a sea-island type composite fiber having an easily alkali-reducing polyester as a sea component and a melt-anisotropic aromatic polyester as an island component is wound around cheese in the alkali-reducing step, and the cheese form is alkalinized as it is. By performing the weight loss treatment, a melt anisotropic aromatic polyester fiber having a single yarn fineness of 0.1 to 1.0 dtex, preferably 0.3 to 0.7 dtex, and a strength after heat treatment of 20 cN / dtex or more is obtained. It is done.
The fiber obtained by the present invention has high strength, high elasticity and excellent chemical resistance, and the single yarn fineness is 1.0 dtex or less, so that the texture and the like are good. When the single yarn fineness is larger than 1.0 dtex, the feeling of tingling when the knitted fabric is made cannot be eliminated.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this Example. In the following Examples, melt viscosity, logarithmic viscosity, and fiber strength are those measured by the following methods.

[Melt viscosity MV poison]
Measurement was performed using a Capillograph Type 1B manufactured by Toyo Seiki under the conditions of a temperature of 300 ° C. and a shear rate of r = 1000 sec ⁻¹ .

[Logarithmic viscosity η _inh dl / g]
The sample was dissolved in pentafluorophenol at 0.1% by mass under conditions of 60 to 80 ° C., and the relative viscosity (η _rel ) was measured using a Upperode viscometer in a constant temperature bath at 60 ° C. Calculated.
η _inh = ln (η _rel ) / c where c is the polymer concentration (g / dl)

[Fiber strength cN / dex]
Based on JIS-L1013, the breaking strength and elongation were determined under the conditions of a test length of 20 cm, an initial load of 0.1 g / d, and a tensile speed of 10 cm / min, and an average value of 5 or more points was adopted.

[Example 1]
(1) The polymer of the island component includes a melt anisotropic fragrance in which the ratio of the structural units (A) and (B) shown in Chemical Formula 2 is (A) / (B) = 73/27 (molar ratio) Group polyester (MP = 281 ° C., MV = 420 poise, η _inh = 4.34 dl / g) was used.
In the sea component polymer, dimethyl (I) 5-sodium sulfoisophthalate is 2.5 mol% of the total acid component constituting the copolyester, polyethylene glycol (II) having a molecular weight of 2000, and A copolymer polyester (inherent viscosity 0.58 dl / g) in which oxyethylene glycidyl ether (III) accounted for 10% by weight of the total copolymer polyester and the remainder was terephthalic acid and ethylene glycol was used. The copolyester contains 5% by weight of an oxidative degradation inhibitor (“Sianox 1790” manufactured by American Siamid) based on the total amount of the polyethylene glycol and polyoxyethylene glycidyl ether. The decomposition rate ratio between the island component polymer and the sea component polymer is 5800.

(2) Each polymer is melted from two extruders, and is guided from the gear pump to the spinning head at a mass ratio of melt anisotropic polyester: easily alkali-reducible polyester = 70: 30, and has the hole cross-sectional shape of FIG. Spinning was performed from a die composed of a diameter of 0.15 mmφ and 24 holes at a spinning temperature of 315 ° C. and a winding speed of 1000 mm / min to produce a sea-island type composite fiber of 274 dtex / 24 f. This fiber was wound around a perforated stainless steel bobbin and immersed in a 3% sodium hydroxide solution at 95 ° C. for 30 minutes. The mass loss by this treatment was 31%, and the easily alkali-reducing polymer was almost completely removed. The strength of the fiber after the sodium hydroxide solution treatment was 9.1 cN / dtex, and the single yarn fineness was 0.5 dtex. This spinning yarn was heat-treated in a nitrogen gas atmosphere at 260 ° C. for 2 hours, 270 ° C. for 4 hours, and further at 280 ° C. for 4 hours. The fiber strength of the obtained heat treated yarn was 23.5 cN / dtex.

[Comparative Example 1]
A melt anisotropic aromatic polyester in which the ratio of the structural units (A) and (B) shown in Chemical Formula 2 as in Example 1 is (A) / (B) = 73/27 (molar ratio) is used. Melting from an extruder alone without using an alkali-reducible polyester, guided to a spinning head with a gear pump, and spinning from a die having a hole diameter of 0.075 mm and 50 holes at a spinning temperature of 315 ° C. and a winding speed of 700 m / min. As a result, 107 dtex / 50f multifilament was obtained. The average fineness of the multifilament single yarn was 2.1 dtex. At this time, the winding speed was further increased to attempt to make the finer, but single yarn breakage occurred frequently and it was impossible to wind the yarn.

[Comparative Example 2]
In Comparative Example 1, it was possible to obtain a fiber having a fineness of 95 dtex / 50f by spinning at a winding speed of 700 m / min and lowering the polymer discharge amount. Occurred and the yarn could not be wound up.

  The melt-anisotropic aromatic polyester fiber of the present invention has high strength, high elasticity and excellent chemical resistance, and its single fiber fineness is 1.0 dtex or less. Widely used in Specifically, as clothing, for example, various work clothes, sports clothing, protective clothing, etc., and as industrial materials, rope, rubber reinforcement, geotextile, FRC, computer ribbon, printed circuit board base, air bag, bag Examples include filters and screen jars. The fiber of the present invention is particularly suitable for protective clothing such as gloves and aprons, sports clothing, filter materials, and particularly for bulletproof clothing, blade-proof clothing, and ice-proof pick clothing.

The specific example of the hole cross-sectional shape in the nozzle die used for spinning of the sea-island type composite fiber of the present invention. In the figure, the filled circle indicates the island component polymer, and the surrounding white portion indicates the sea component polymer.

Claims (2)

  A sea-island type composite fiber having an island component of melt-anisotropic aromatic polyester and a sea component of easily alkali-reducible polyester and a mass ratio of sea component to island component of sea: island = 10: 90 to 50:50 is alkali. A melt-anisotropic aromatic polyester fiber having a single yarn fineness of 0.1 to 1.0 dtex after weight reduction treatment and alkali weight reduction treatment, and a fiber strength after heat treatment of 20 cN / dtex or more. A method for producing a melt-anisotropic aromatic polyester fiber, wherein the sea-island type composite fiber according to claim 1 is wound around cheese and subjected to an alkali weight-reducing treatment in the form of cheese to dissolve and remove the easily alkali-weightable polyester.

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