JPH07316926A - Core-sheath type composite fiber, coated yarn, and method for producing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a coated yarn made of a melt-anisotropic aromatic polyester having excellent properties such as high strength and high elastic modulus, chemical resistance, and heat resistance, and having a good feeling. [Structure] The core component (A polymer) is a melt-anisotropic aromatic polyester, and the sheath component is a sea-soluble component (B polymer) composed of an alkali-dissolvable polyester or alkali-decomposable polyester, and a melt-anisotropic aroma. A core-sheath type composite fiber composed of an island component (C polymer) composed of a group polyester is dissolved or decomposed to remove the B polymer by alkali treatment, and the surface of the core yarn is substantially 0.1 denier. A coated yarn covered with a fibrous material composed of the following melt anisotropic aromatic polyester is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core-sheath type composite fiber using a melt anisotropic aromatic polyester, a coated yarn and a method for producing the same.

[0002]

2. Description of the Related Art Melt anisotropic aromatic polyester fibers are
For example, as disclosed in Japanese Patent Laid-Open No. 61-174408,
It is known that the molecular chains are highly oriented in the fiber axis direction and have high strength and high elastic modulus.

[0003]

However, since the melt-anisotropic aromatic polyester is composed of highly oriented and rigid molecules in the spinning process, subsequent stretching is almost impossible. Therefore, a product having a small fineness cannot be obtained, which causes various problems. When it is processed into a woven or knitted fabric, it has a large fineness and becomes a stiff and unsatisfactory texture.When it is used as a bulletproof garment, the strength of the fiber itself is high, but the bullets and blades may come off. The original performance such as high strength could not be exhibited. Also, when used as a filter, although the heat resistance and chemical resistance of the fiber are excellent, there is a problem that the filtration efficiency is low because only a large denier can be obtained. In order to solve such a problem, the present invention has found an excellent coated yarn made of a melt anisotropic aromatic polyester.

[0004]

According to the present invention, the core component (A polymer) is a melt-anisotropic aromatic polyester, and the sheath component is an alkali-dissolvable polyester or an alkali-decomposable polyester. Island component (C polymer) consisting of polymer) and melt anisotropic aromatic polyester
1 to 3 by dissolving or decomposing and removing the B polymer by alkali treatment of the core-sheath type composite fiber constituted by
The surface of the core yarn made of 0 denier melt anisotropic aromatic polyester is covered with a fibrous substance made of 0.1 denier or less melt anisotropic aromatic polyester. There is an attempt to obtain an excellent coated yarn.

The melt anisotropy referred to in the present invention means that the melt phase exhibits optical anisotropy (liquid crystallinity). For example, the sample can be certified by placing it on a hot stage, heating it up in a nitrogen atmosphere, and observing the transmitted light of the sample. The melt anisotropic aromatic polyester used as the A polymer and the C polymer in the present invention is composed of repeating constitutional units such as aromatic diol, aromatic dicarboxylic acid and aromatic hydroxycarboxylic acid. As the aromatic aromatic polyester, there may be mentioned those comprising a combination of repeating constitutional units shown in the following chemical formula 1.

[0006]

[Chemical 1]

Particularly preferably, a polymer comprising a combination of repeating constitutional units shown in the following chemical formula 2 is preferable. It is more preferable to use a polymer in which the proportion of the repeating constitutional units (A) and (B) is 65% by weight or more, and particularly an aromatic polyester in which the component (B) is 4 to 45% by weight.

[0008]

[Chemical 2]

Melting point of melt anisotropic aromatic polyester (M
P) is preferably 260 to 380 ° C, particularly preferably 270 to 350 ° C.
The melting point referred to here is the differential scanning calorific value (DSC: eg me
Peak temperature of the main endothermic peak observed with TAttler, TA3000) (JIS K7121). Specifically, DS
In a C (for example, TA3000 manufactured by Mettler Co.) device, 10 to 20 mg of the sample was placed and sealed in an aluminum pan, and then nitrogen was passed as a carrier gas at 100 cc / min and the endothermic peak when the temperature was raised at 20 ° C./min. Measure When a clear endothermic peak does not appear in the above 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 heating rate of 50 ° C / min, and at that temperature, 3 After completely melting for a minute, the temperature is cooled to 50 ° C. at a rate of 80 ° C./minute, and then the endothermic peak may be measured at a temperature rising rate of 20 ° C./minute. The A polymer and the C polymer may be the same or different.

The sea component (B polymer) is not particularly limited as long as it is an alkali easily decomposable polyester or an alkali easily soluble polyester, but a substance having a high alkali decomposition rate, that is, a melt anisotropic aromatic to be used. 1000 times or more of polyester, more preferably 3000
Polyester that is at least twice as large is preferable. Specific examples thereof include polyesters containing the structural units I to III shown in Chemical formula 3.

[0011]

[Chemical 3]

The copolymerized polyester containing the structural units I to III has good spinnability with the melt anisotropic aromatic polyester and excellent alkali decomposability. The alkali decomposition rate of the copolyester is 3000 times or more higher than that of the melt anisotropic aromatic polyester, and the treatment with the alkali solution can be performed in a short time. Therefore, the melt-anisotropic aromatic polyester (A polymer, C polymer) is less likely to be deteriorated or eroded by an alkali, and a fiber having excellent strength and texture can be obtained. Further, since the copolyester can be almost completely removed by the treatment with the alkaline solution, no trouble such as fusion will occur in the subsequent heat treatment step or the like. The alkali decomposition rate referred to in the present invention means that the sample fiber is cylindrically knitted, immersed in a sodium hydroxide aqueous solution of 98 ° C. and 20 g / l at a bath ratio of 1: 500, and the sample is dissolved with stirring. It is represented by the dissolution rate constant K obtained by the following equation.

[0013]

[Equation 1]

From the viewpoint of alkali decomposability and spinnability, the structural unit I is 0.5 to 10 of all the acid components constituting the polyester.
It is more preferable to use a copolymerized polyester containing mol% and structural units II and III in an amount of 1% by weight or more of each polyester, and the total content of the structural units II and III is 2 to 50% by weight of the polyester. More preferably, a copolymerized polyester is used in which the structural unit I is 1 to 7 mol% of all the acid components constituting the polyester, and the total content of the structural units II and III is 5 to 30% by weight of the polyester. It is also possible to improve heat resistance by adding a commercially available oxidative decomposition inhibitor (for example, Irganox 1010 manufactured by Ciba-Gaiki Co., Ltd., and Syanox 1790 manufactured by American Cyanamid Co., Ltd.).

Examples of the trivalent aromatic group (Ar) in the dicarboxylic acid unit I include a benzenetriyl group and a naphthalenetriyl group. The metal atom M is an alkali metal atom such as sodium, potassium or lithium. Is preferred.
The copolymerized polyester (B polymer) may have a plurality of dicarboxylic acid components I. Other carboxylic acid units constituting the copolyester (B polymer) include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, and β-hydroxyethoxy. Examples thereof include aromatic hydroxycarboxylic acids such as benzoic acid and p-oxybenzoic acid, and aliphatic dicarboxylic acids, alicyclic carboxylic acids, tricarboxylic acids, and the like.
Plural kinds of these carboxylic acid units may be used. 70 mol% of all acid component units constituting the copolyester (A)
The above are preferably aromatic dicarboxylic acid units, particularly terephthalic acid units.

Further, R ¹ in the diol unit II is preferably an alkylene group having 1 to 4 carbon atoms, ethylene group and / or propylene group, particularly ethylene group from the viewpoint of alkali solubility. . The average degree of polymerization m is 10
It is necessary to be -100, but 20-80 is more preferable. When m is less than 10, the alkali solubility is low, and when it exceeds 100, the alkali solubility is not improved so much, and a coloring problem is likely to occur. A unit derived from polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene / polyoxypropylene glycol or the like is preferable, and a plurality of these diol units I are contained in the copolyester (B polymer). May be included. Further, the copolyester preferably further has other diol units, and examples thereof include aliphatic diols and alicyclic diols. It may contain a plurality of these diol units. A unit derived from a linear alkylene glycol having 2 to 6 carbon atoms is preferable from the viewpoint of fiber forming property.

R ² in the side chain unit III is preferably an alkylene group having 1 to 4 carbon atoms, and is preferably an ethylene group and / or a propylene group, particularly an ethylene group. R ₃ is a linear or branched alkyl group having 1 to 15 carbon atoms,
Examples thereof include a cycloalkyl group having 3 to 18 carbon atoms and an aryl group having 6 to 18 carbon atoms. The degree of polymerization n is 10 to 1
The range is 00, but 20 to 80 is more preferable. When n is less than 10, the alkali solubility decreases,
On the other hand, when it exceeds 100, the alkali solubility is not improved so much and causes coloring. Specifically, 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 a plurality of these units may be contained in the copolyester (A).

The A polymer and / or the B polymer and / or the C polymer may be polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, or polycarbonate as long as the effects of the present invention are not impaired. Bonnet,
Polyacrylate, polyamide, polyphenylene sulfide, polyester ether ketone, and fluororesin thermoplastic polymer may be added. It may also contain various additives such as inorganic substances such as titanium oxide, kaolin, silica and barium oxide, carbon black, colorants such as dyes and pigments, antioxidants, ultraviolet absorbers and light stabilizers.

The core yarn made of the melt anisotropic aromatic polyester used in the present invention has a denier of 1 to 30. 1 denier
If it is less than 1, the spinning is difficult and the commercial scale production is difficult.
If it exceeds 30 denier, the rigidity becomes high and the softness is impaired, which is not suitable for the purpose of the present invention. More preferably 2 to 1
It will be 5 denier. The fibrous material that coats the core yarn is
When the density is 0.1 denier or less, a preferable feeling is obtained. Further, it is processed into a knitted woven fabric or the like to obtain a protective garment having high strength and high elastic modulus, which does not easily cause bullets, blades and the like to pass through, and a filter which has excellent chemical resistance, heat resistance and filtration efficiency. You can 0.1 deniers to the extent that the effects of the present invention are not impaired
Fibrous material may be included.

The sea-island structure referred to in the present invention means a state in which several tens to several hundreds of islands are present in the sea component serving as a matrix in the cross section of the fiber. The number of islands in Umishima Textile is 40 to 10
About 00 pieces, particularly 70 to 300 pieces are preferable. The number of such islands is
It can be changed by adjusting the kneading ratio and melt viscosity of the components A and B. For example, the number of islands can be decreased by increasing the kneading ratio of the aromatic polyester (B) or increasing the difference in melt viscosity between the two components. It can be obtained by chip blending the sea component (B polymer) and the island component (C polymer), or by mixing the melt of both components with a static mixer or the like. The preferred ratio of the B polymer and the C polymer is 0.8 to 0.8 in the cross-sectional area ratio B / C of the produced sheath-type composite fiber.
5, more preferably 1-3. If the B / C is less than 0.8, the sea component and the island component may be reversed, whereas if the B / C is more than 5, the removal component becomes large and the alkali treatment time becomes long, which is not economically preferable.

The conjugate fiber used in the present invention can be prepared by a known method,
For example, spinning can be performed using the nozzle shown in FIG. The cross-sectional shape of the obtained fiber is not particularly limited, but for example, the shape shown in FIG. 2 is a preferable example. Further, when the core-sheath ratio, that is, the area ratio A / (B + C) in the cross section of the conjugate fiber is 0.5 to 8, a good effect is exhibited. It may have any core-sheath ratio, but when an extremely excellent feeling is required, it is preferable that the core-sheath ratio is 8 or less in order to sufficiently cover with the fibrous material. The core-sheath ratio is preferably 0.5 or more when the strength and elastic modulus is required to some extent. More preferably, a core-sheath type composite fiber having a core-sheath ratio of 1 to 3 is used. The cross-sectional area ratio is obtained from a micrograph of the fiber cross-section, but it can also be obtained from the volume ratio of the discharge amounts of the core component and the sheath component during production.

The fiber length of the fibrous material covering the core yarn can be appropriately adjusted depending on the purpose. In particular, the melt anisotropic aromatic polyester is more likely to be oriented in the fiber axis direction as compared with a non-liquid crystalline polyester such as polyethylene terephthalate, so that a longer fibrous material can be formed, and twisting etc. By applying, the fibrous material can be tightly wound around the core yarn. Since the fiber length of each fibrous substance is long, the strength of the whole coated yarn is high, and further, the coated yarn is obtained in which the core yarn and the fibrous substance group are not easily separated by friction or the like. Therefore, it can exhibit excellent performance not only for clothing but also for industrial materials. The melt anisotropic aromatic polyester is more than 5 times more excellent in alkali resistance than the polyester such as polyethylene terephthalate which is generally used, and even if alkali reduction treatment is performed, the strength and texture are substantially the same. It is a polymer suitable for alkali treatment without being damaged. The B polymer may be dissolved and / or decomposed and removed by any method such as a dipping method, a dip nip method, and a roller pad method. The alkaline solution used is preferably a strong alkaline solution such as sodium hydroxide, calcium hydroxide, trisodium phosphate, etc. From the viewpoint of alkali solubility and fiber erosion, 2 to 60 g / l, and more preferably 3 Perform alkali treatment in a treatment solution of about 20g / l.
When using a weakly alkaline substance such as sodium carbonate, sodium silicate, sodium dihydrogen phosphate, etc., the concentration of the alkaline substance in the treatment liquid is 5-200 g / l, preferably 5-60 g / l.
d. It is also possible to use a strong alkaline substance and a weak alkaline substance together, and the treatment liquid may contain a decomposition accelerator or the like. In addition, addition of a cationic surfactant is preferable because it promotes alkali permeation of the fiber. The alkali treatment temperature is preferably 70 to 130 ° C. If the temperature is lower than 70 ° C., the alkali treatment takes a long time, and if it exceeds 130 ° C., the melt anisotropic aromatic polyester is likely to be corroded and deteriorated. The alkali treatment may be performed in the form of core-sheath type composite fibers, or may be performed after processing into a woven fabric, a knitted fabric, a non-woven fabric or the like. After dividing the fibers by alkali treatment, it is preferable to carry out neutralization and water washing and drying treatment.

The conjugate fiber of the present invention already has sufficient strength and elastic modulus just 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 atmosphere of an inert gas such as nitrogen, in an atmosphere of an oxygen-containing active gas such as air, or under reduced pressure. The heat treatment atmosphere is preferably a low humidity body having a dew point of -80 ° C or lower. A preferable heat treatment condition is a temperature pattern in which the temperature is sequentially raised from the melting point of the core component of −40 ° C. or lower to the melting point of the sheath component polymer or lower. The processing time is several minutes to several tens of hours depending on the purpose.

Heat is supplied by a method using a medium such as gas,
Method of utilizing radiation by heating plate, infrared heater, etc.,
There are a method of contacting with a heat roller, a heat plate and the like, an internal heating method using high frequency and the like. The treatment is performed under tension or without tension depending on the purpose. The treatment shape may be a mould-like shape, a tow-like shape (for example, placed on a metal net or the like), or continuous treatment between rollers. The tension heat treatment is preferably performed at a temperature not higher than the melting point of the core component of −80 ° C. with a tension of 1 to 10% of the cutting strength, and this treatment further improves various performances, particularly the elastic modulus.

The coated yarn obtained in the present invention has high strength, high elasticity, and excellent chemical resistance, and since it is coated with a fibrous material having a density of 0.1 denier or less, it has a good feeling. The field of application is widely used in general industrial materials, clothing, and the like. Specifically, it is used for various clothing such as work clothes, sports clothing, protective clothing, and industrial materials such as ropes, rubber reinforcement, geotextiles, FRC applications, computer ribbons, and printed circuit boards. Examples include base cloth, air bags, bag filters, screen gauze, and the like.
The fiber of the present invention is particularly suitable for protective clothing such as gloves and aprons, protective materials, sports clothing, filtration materials, bulletproof clothing and the like.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. [Melt viscosity MV] It was measured using a Toyo Seiki Capillograph 1B type under the conditions of 300 ° C. and a shear rate r = 1000 sec ⁻¹ . [Logarithmic viscosity ηinh] Sample was converted to pentafluorophenol
Dissolve 0.1% by weight (60-80 ° C) and measure the relative viscosity (ηrel) using an Upperode-type viscometer in a constant temperature bath at 60 ° C.
It was calculated by ηinh = ln (ηrel) / c. Note that c is the polymer concentration (g / dl). [Strength] In accordance with JIS L 1013, 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. [Denier] Take a photograph of the cross section of the obtained coated yarn,
The average denier of 20 randomly selected fibrillar fibers is determined. The average denier was similarly obtained for the other four arbitrary cross sections, and the value obtained by further averaging the average denier of the five points was used.

Example 1 In the A polymer, a melt anisotropic aromatic polyester (MP = 281 ° C., MV =) in which the structural units (A) and (B) shown in Chemical formula 2 are 73/27 mol% 420poise, ηinh = 4.34dl
/ g) was used. In the B polymer, dimethyl 5- (sodium sulfoisophthalate) (I) is 2.5 mol% of all the acid components constituting the copolyester, polyethylene glycol (II) having a molecular weight of 2000, and the polyoxy group represented by Chemical Formula 6 A copolymerized polyester (intrinsic viscosity 0.58 dl / g) in which ethylene glycidyl ether (III) accounts for 10% by weight of the total copolymerized polyester and the balance is terephthalic acid and ethylene glycol was used. The copolymerized polyester contains 5% by weight of an antioxidant and antioxidant (Syanox 1790, manufactured by American Siamid) based on the total amount of the polyethylene glycol and polyoxyethylene glycidyl ether. The decomposition rate ratio of A polymer and B polymer is 5800.

[0028]

[Chemical 4]

As the C polymer, a polymer obtained by mixing a melt anisotropic aromatic polyester similar to the above A polymer is used.
Was used. The fibers were blended in a chip shape so that the cross-sectional area B / C was 1. Using such a polymer, spinning was performed at a spinning temperature of 315 ° C. and a winding speed of 1000 mm / min from a spinneret having a nozzle diameter of 0.125 mm φ and 50 holes having the structure of FIG. 1, and the core-sheath ratio A / (B + C). Of 1,500 d / 50 f was obtained. Wrap this fiber around a perforated stainless bobbin and
It was immersed in a 3% sodium hydroxide solution at 0 ° C. for 5 minutes.
The fiber obtained was 381 d / 50f and the B polymer was almost completely removed. The obtained fiber has a good feel of span-like in which the core fiber (5 denier) is covered with a fibrous material having an average fineness of 0.02 denier or less, and has the following performance. Was there. Tensile strength (DT): 9.1 g / d Tensile elongation (DE): 2.3% This spun raw yarn was heated at 260 ° C. for 2 hours, and 270 ° C. for 4 hours.
Further, heat treatment was performed at 280 ° C. for 4 hours in a nitrogen gas atmosphere.
The heat treated yarn obtained had almost no sticking and had the following properties. Tensile strength (DT): 22.5g / d Tensile elongation (DE): 3.5%

Example 2 As the A polymer, the structural unit (C) of the above chemical formula 2,
Consists of (D), (E), and (F), (C) / (D) / (E) / (F) = 60
/ 20/15/5 Melt anisotropic aromatic polyester (MP =
348 ° C., MV = 120 poise, ηinh = 3.24 dl / g) were used. MV is a value when the shear rate is 1000 sec ⁻¹ at a temperature of 360 ° C. For the sea component (B polymer), Example 1 was used.
The same copolyester is used, and the island component (C polymer) is the same as the A polymer of this example.
The fibers were blended in a chip shape so that the cross-sectional area B / C was 1. The decomposition rate ratio of A polymer and B polymer is 340.
It is 0. Using such a polymer, a spinning temperature of 36 from a spinneret having a nozzle diameter of 0.15 mm and a 50-hole structure as shown in FIG.
Spinning at 0 ℃, winding speed 500mm / min, core-sheath ratio A / (B +
C) A core-sheath type composite fiber of 2,458d / 50f was obtained. Further, the B polymer was removed by the same method as in Example 1. The fiber obtained was 378d / 50f and the B polymer was almost completely removed. The core fiber (5 denier) has an average fineness of 0.01 denier.
It had a good feel of a spanklike covered with fibrous materials of the following grades, and had the following performance. Tensile strength (DT): 7.0 g / d Tensile elongation (DE): 1.8% This spun raw yarn was heated at 280 ° C. for 2 hours and 310 ° C. for 8 hours,
Further, heat treatment was performed at 330 ° C. for 2 hours in a nitrogen gas atmosphere.
The heat treated yarn obtained had the following properties without sticking. Tensile strength (DT): 18.8 g / d Tensile elongation (DE): 3.6%

[0031]

Industrial Applicability According to the present invention, a coated yarn having excellent properties such as high strength and high elastic modulus, heat resistance, and chemical resistance, and having a span-like texture whose surface is covered with a fibrous material can be obtained.

[Brief description of drawings]

FIG. 1 is a specific example of a spinneret used in the present invention.

FIG. 2 is a specific example of the cross-sectional shape of the core-sheath type composite fiber used in the present invention. In the figure, A is an A polymer, B is a B polymer, and C is a C polymer.

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[Procedure amendment]

[Submission date] March 30, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction content]

[0008]

[Chemical 2]

Claims (3)

[Claims] 1. A sea component (B polymer) in which the core component (A polymer) is a melt anisotropic aromatic polyester, and the sheath component is an alkali easily soluble polyester or an easily alkali decomposable polyester, and a melt anisotropic substance. Core-sheath type composite fiber composed of an island component (C polymer) composed of a hydrophilic aromatic polyester. 2. A sea component (B polymer) in which the core component (A polymer) is a melt anisotropic aromatic polyester and the sheath component is a readily alkali-soluble polyester or a readily alkali-decomposable polyester and a melted anisotropic substance. A method for producing a coated yarn, which comprises dissolving or decomposing and removing a B polymer by alkali treatment of a core-sheath type composite fiber composed of an island component (C polymer) made of a hydrophilic aromatic polyester. 3. A fibrous substance made of a melt anisotropic aromatic polyester having a surface density of 0.1 denier or less on the surface of a core yarn made of a melt anisotropic aromatic polyester having a denier of 1 to 30. A covered yarn characterized by being covered.