JP4896433B2 - Extra fine melt anisotropic aromatic polyester fiber - Google Patents

Description

  The present invention relates to a melt-anisotropic aromatic polyester fiber, particularly a melt-anisotropic aromatic polyester fiber having a high strength and a high elastic modulus in spite of an ultrafine fineness having a single yarn fineness of 0.01 to 1.5 dtex. The present invention relates to a melt-anisotropic aromatic polyester fiber that can be used as a protective material such as a bulletproof garment, a blade-proof garment, and an ice-proof garment, and also has a good texture when made into a garment or the like, and a production method thereof.

  As a technique for imparting inorganic fine particles to melt-anisotropic aromatic polyester fibers, inorganic fine particles having an average particle diameter of 0.01 to 15 μm, which are mainly composed of silicic acid having a Mohs hardness of 4 or less and magnesium, are used as a single yarn. A melt-anisotropic aromatic polyester fiber is known which is adhered to a fiber surface having a fineness of 2 to 10 dtex (see, for example, Patent Document 1). Patent Document 1 is effective in improving the bending fatigue resistance and wear resistance due to the rigidity of the melt-anisotropic aromatic polyester fiber, and is also effective in avoiding yarn sticking after heat treatment.

  In general, melt anisotropic aromatic polyester fibers cannot provide sufficient strength at the raw yarn stage immediately after spinning. By heat-treating this in an inert gas atmosphere such as nitrogen, the solid-phase polymerization reaction proceeds and high strength is obtained, but at the same time, the single fibers tend to stick together and the yarn becomes hard. ing. The technique of Patent Document 1 that imparts inorganic fine particles has the effect of preventing mutual sticking by allowing fine particles to exist between the single fibers, and further, if the single yarn has good fineness, the yarn is simply softened. In addition, physical properties such as nodule strength are improved.

  However, most conventional melt anisotropic aromatic polyester fibers have a single yarn fineness of 2 to 10 dtex, and inorganic fine particles having a particle size as described in Patent Document 1 have a finer single yarn fineness. For fine fibers with a fineness of less than 2.0 dtex, the particle size is too large, and even if applied by roller touch or crow mouth, the particles are present only on the surface of the yarn and can enter between the yarns. There was a problem that it was not possible to avoid sticking during heat treatment.

JP 2004-107826 A

  The object of the present invention is to obtain a melt anisotropic aromatic polyester fiber having excellent ultrafineness and high knot strength compared to the prior art, which is excellent in single yarn splitting properties without sticking to each other even after heat treatment. It is in.

  As a result of intensive investigations by the inventors of the present invention to achieve the above object, the single yarn does not stick to each other even after heat treatment by applying inorganic fine particles having an average particle size of 0.001 to 1 μm to the fiber surface. It has been found that an extremely fine melt-anisotropic aromatic polyester fiber is obtained that has excellent fiber separation properties, is very flexible, and has a higher knot strength than conventional ones.

That is, the present invention spins a sea-island composite fiber containing a water-soluble polymer or an easily alkali-soluble polymer as a sea component and a melt-anisotropic aromatic polyester as an island component, and the average particle size of the fiber after hot water or alkali weight reduction treatment 0.001 to 1 μm of a swellable layered clay mineral is adhered to the surface of a single fiber in an amount of 0.05 to 2% by mass, the single yarn fineness is 0.01 to 1.5 dtex, and the strength after heat treatment is 15 cN / dtex or more. Ru is melted anisotropic aromatic polyester fiber der.

  Since the melt anisotropic aromatic polyester fiber having the inorganic fine particles of the present invention attached to the fiber surface is high in strength and thin, and has no sticking between single yarns, it has excellent knot strength and flex fatigue, It can be used for a wide range of applications such as ropes, cables, tension members, FRP, bulletproof vests.

  The melt anisotropic aromatic polyester referred to in the present invention is an aromatic polyester that exhibits optical anisotropy (liquid crystallinity) in the melt phase. For example, a sample is placed on a hot stage and heated at a high temperature in a nitrogen atmosphere. It can be identified by 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. Is preferred.

  Particularly preferred is a polymer comprising a combination of repeating constitutional units represented by the following chemical formula 2, and more preferred is a polymer having a portion comprising (A) and (B) repeating constitutional units of 65% or more, particularly (B ) Is preferably an aromatic polyester having a content of 4 to 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.

  Addition of polyethylene naphthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyphenylene sulfide, polyetheretherketone, fluororesin, etc. to the melt anisotropic aromatic polyester within the range that does not impair the effects of the present invention May be. 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.

Next, regarding the method for obtaining a melt anisotropic aromatic polyester fiber having ultrafineness according to the present invention, a sea-island composite fiber having a water-soluble polymer or an easily alkali-soluble polymer as a sea component and a melt anisotropic aromatic polyester as an island component. Is used to obtain 0.01 to 1.5 dtex fine fiber by hot water or alkali weight loss treatment.

The spinning yarn can be further improved in strength and elastic modulus by heat treatment. The heat treatment is preferably performed under a temperature condition ranging from (MP-80 ° C.) to MP. Since the melting point of the melt-anisotropic aromatic polyester fiber of the present invention increases as the heat treatment temperature is raised, it is preferable that the heat treatment is carried out while raising the temperature stepwise. As the heat treatment atmosphere, an inert gas such as nitrogen or argon, an active gas such as air, or a combination thereof is preferably used.
Moreover, there is no problem even if the heat treatment is performed under reduced pressure.

An important point in the present invention is to adhere inorganic fine particles to the surface of the melt-anisotropic aromatic polyester fiber, but particularly important is a melt anisotropy having a fineness of 0.01 to 1.5 dtex. The purpose is to attach inorganic fine particles having an average particle diameter of 0.001 to 1 μm to the surface of the aromatic polyester fiber.
Conventional melt anisotropic aromatic polyester fibers usually have a single yarn fineness of 2 to 10 dtex. However, when the single yarn fineness is reduced to 0.01 to 1.5 dtex, the packing density when a multifilament yarn is used is high. Become. Then, even if it tries to adhere the fine particles to the surface of the single fiber, if the particle diameter is not reduced, even if the fine particles are present only on the surface of the yarn, they cannot enter between the single fibers, and the single yarns at the time of heat treatment The effect of preventing the sticking of the film cannot be obtained. The particle diameter of the fine particles of the present invention is required to be 0.001 to 1 μm, and preferably 0.01 to 0.1 μm.

  In the present invention, more important is the amount of fine particles attached to the yarn. In particular, when the fine particles are a swellable lamellar clay mineral such as smectite, when dispersed in water, the particles are cleaved in a scaly shape and become a uniform solution without settling. When this is adhered to the fiber, the scaly fine particles come to cover the surface. Here, if the adhesion amount is too large, the fine particles coated on the fiber surface during the heat treatment suppress the generation of by-products accompanying the solid-phase polymerization reaction, so that the solid-phase polymerization reaction does not proceed sufficiently. Even if the single yarn is finely divided, the fiber strength may not be sufficiently improved. As a result of intensive studies on the relationship between the adhesion amount of the swellable layered clay mineral, the single-fiber separation property, and the fiber strength, the present inventors have found that the adhesion amount needs to be 0.05 to 2% by mass. . If the adhesion amount is less than 0.05% by mass, the single fibers are strongly stuck, while if more than 2% by mass, the fiber strength is remarkably lowered. Preferably it is 0.07-1.5 mass%, More preferably, it is 0.1-1 mass%.

The method for attaching the inorganic fine particles to the fiber surface of the present invention is not particularly limited, and is not particularly limited as long as it is a method capable of uniformly attaching to the fiber. However, since inorganic fine particles mainly have the purpose of preventing sticking of single yarns by heat treatment, it is preferable that they be adhered to the fiber surface before heat treatment.
For example, when attaching at the spinning stage, a method in which inorganic fine particles are dispersed in water while the yarn is wound after the polymer is discharged from the nozzle is easy to attach using a roller touch or a crow mouth. preferable. In addition, after spinning the sea-island composite fiber, if the sea component is reduced in weight to obtain ultrafine yarn, a method of attaching it using a roller touch or a crow mouth in a step of winding the yarn is also conceivable. Further, the aqueous solution in which the inorganic fine particles are dispersed may contain a surfactant component used in a normal spinning oil.

  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]
The measurement was performed using a Capillograph Type 1B manufactured by Toyo Seiki under the conditions of 300 ° C. and shear rate 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) For the polymer of the sea component, dimethyl (I) 5-sodium sulfoisophthalate is 2.5 mol% of the total acid component constituting the copolymer polyester, polyethylene glycol (II) having a molecular weight of 2000, and The polyoxyethylene glycidyl ether (III) represented represents 10% by weight of the total copolymer polyester, and the remainder is terephthalic acid and ethylene glycol copolymer polyester (inherent viscosity 0.58 dl / g), island component polymer The melt anisotropic aromatic polyester (MP = 281 ° C., MV) in which the structural units (A) and (B) shown in the chemical formula 2 are (A) / (B) = 73/27 (molar ratio). = 420 poise, η _inh = 4.34 dl / g). The sea component copolymer polyester contains 5% by mass 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 of the polymer of the island component and the polymer of the sea component was 5800.

(2) Each polymer is melted from two extruders, and is guided from the gear pump to the spinning head with melt anisotropic aromatic polyester: easy alkali weight loss polyester = 70: 30 (mass ratio). Spinning was performed from a nozzle having a nozzle diameter of 0.15 mmφ and 24 holes at a spinning temperature of 315 ° C. and a winding speed of 1000 mm / min to obtain 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 sodium hydroxide solution at 95 ° C. for 30 minutes. The mass loss due to this treatment was 31%, and the easily-reducible polymer was completely removed. The fiber strength of the island component after the treatment was 9.1 cN / dtex, and the single yarn fineness was 0.5 dtex.
(3) Swellable layered clay mineral fine particles (synthetic smectite “SWN” manufactured by Coop Chemical Co., Ltd.) in the fiber obtained in (2) above are added to a spinning oil mainly composed of polyethylene glycol laurate at a concentration of 2% by mass. Was dispersed. SWN swelled and cleaved, and the average particle size became 0.01 to 0.1 μm. This was made to adhere 0.5 mass% of SWN to the yarn at the crow mouth. The obtained fiber was heat-treated at 260 ° C. for 2 hours in a dry nitrogen atmosphere, then heat-treated at 280 ° C. for 12 hours, and then a finishing oil mainly composed of coconut oil was adhered to the yarn to obtain a heat-treated yarn. Table 1 shows the measurement results of the physical properties of the obtained heat-treated yarn.

[ Reference Example 1 ]
A heat treated yarn was produced in the same manner as in Example 1 except that the amount of SWN deposited was 3% by mass. Table 1 shows the measurement results of the physical properties of the obtained heat-treated yarn.

[Example 2 ]
A heat treated yarn was produced in the same manner as in Example 1 except that the amount of SWN deposited was 0.1% by mass. Table 1 shows the measurement results of the physical properties of the obtained heat-treated yarn.

[Comparative Example 1]
A heat treated yarn was prepared in the same manner as in Example 1 except that the fine particles of the swellable layered clay mineral were not added to the spinning oil. Table 1 shows the measurement results of the physical properties of the obtained heat-treated yarn.

[Comparative Example 2]
A heat treated yarn was produced in the same manner as in Example 1 except that 0.5 mass% of the fine particles were attached to the inorganic fine particles using synthetic mica “Somasif ME-100” manufactured by Co-op Chemical. This synthetic mica also swelled and cleaved with water, and the average particle size was 1 to 10 μm. Table 1 shows the measurement results of the physical properties of the obtained heat-treated yarn.

As shown in Table 1, a melt anisotropic fragrance in which 0.1 to 0.5 mass% of fine particles of a swellable layered clay mineral having an average particle diameter of 0.01 to 0.1 μm of Examples 1 and 2 was imparted to a yarn The group polyester fiber had less or less sticking between single yarns than Comparative Example 1, and the knot strength was also improved. On the other hand, even with the same swellable fine particles, when the average particle size was as large as 1 to 10 μm, the sticking between single yarns was not improved even if the knot strength was slightly improved.

  The melt-anisotropic aromatic polyester fiber of the present invention has high strength, high elasticity and excellent chemical resistance, its single fiber fineness is 1.5 dtex or less, and has a good single yarn splitting property, so its texture is Because it is good, it is widely used in general industrial materials and clothing. 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 figure which shows an example of the cross-sectional shape of the nozzle cap used for spinning of the fiber of this invention.

Claims (1)

A sea-island composite fiber containing a water-soluble polymer or an easily alkali-soluble polymer as a sea component and a melt anisotropic aromatic polyester as an island component is spun, and the average particle size is 0.001 to 1 μm in the hot water or the fiber after alkali weight loss treatment. Swellable layered clay mineral of 0.05 to 2% by mass is attached to the surface of the single fiber, the single yarn fineness is 0.01 to 1.5 dtex, and the strength after heat treatment is 15 cN / dtex or more. Aromatic polyester fiber.

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