JP2002317334A - High-strength conjugated fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remarkably improve disadvantages possessed by a high-strength and high-modulus fiber composed of a molten liquid crystal-forming polyester in that the high-strength and high-modulus fiber is readily fibrillated by friction and the fatigue resistance is low, etc., and supply a fiber having excellent operating performances. SOLUTION: In this high-strength conjugated fiber a core component is composed of a molten liquid crystal-forming polyester and a sheath component is composed of >=80 mol% of polycyclohexanedimethanol terephthalate in (90/10) to (50/50) conjugated ratio of the fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite fiber having a high strength and a high elastic modulus which is excellent in abrasion resistance and fatigue resistance, and is used in general industrial materials, particularly ropes and rubber reinforcements. , Geotextiles, FRC applications, computer ribbons, printed circuit board fabric, airbags,
It is widely used for bag filters, screen gauze, etc.

[0002]

2. Description of the Related Art As described in, for example, JP-A-61-174408, a molten liquid crystal-forming polyester fiber has a high strength and a high elastic modulus because its molecular chains are highly oriented in the fiber axis direction. It is known. However,
Since only a weak intermolecular force acts in the direction perpendicular to the fiber axis, fibrils are easily generated due to friction, causing a decrease in tension and causing damage, such as breakage. In addition, a kink band due to buckling is easily generated and tends to be localized, so that it has low fatigue resistance. For the purpose of remedying these drawbacks, a composite fiber comprising a core component comprising a molten liquid crystal forming polyester and a sheath component comprising polyphenylene sulfide has been disclosed in JP-A-1-22981.
No. 5 proposes this. Further, Japanese Unexamined Patent Application Publication No.
Japanese Patent Publication No. 22 proposes a method for producing a composite fiber in which interfacial peeling is less likely to occur by performing acid washing after polymerization of a polyphenylene sulfide resin and composite spinning with a main chain type liquid crystal resin.

[0003]

As mentioned above,
It is a fact that the core-sheath structure improves fibrillation resistance and abrasion resistance.However, the polyphenylene sulfide resin of the sheath component tends to gel, causing problems such as complex abnormalities due to aging and clogging of discharge holes. It was found that it was likely to occur and become a problem in operation. In addition, the polyphenylene sulfide resin, which is a flexible polymer of the sheath component, has a poor affinity for the liquid crystal polyester even after various modifications, and remains in an unstretched state. Problems often occurred. As a result of intensive studies, the present invention has been found to improve the occurrence of sheath peeling, fibrillation resistance, fatigue resistance, complex abnormalities during spinning, and clogging of discharge holes.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal-forming polyester having a core component of 80 mol% and a sheath component of 80 mol%.
The above is achieved by a high-strength composite fiber made of polycyclohexanedimethanol terephthalate.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The molten liquid crystal forming polyester as a core component of the present invention refers to a polyester which exhibits optical anisotropy when melted by heating. This characteristic can be recognized, for example, by placing the sample on a hot stage, heating the sample in a nitrogen atmosphere, and observing the transmitted light of the sample with a polarizing microscope.

As the molten liquid crystal forming polyester, for example, A.I. A polymer of an aromatic oxycarboxylic acid; A polymer of an aromatic dicarboxylic acid and an aromatic diol or an aliphatic diol; And a copolymer of A and B. Also,
For the polymerization of the molten liquid crystal-forming polyester, a conventionally known method can be used.

Here, the aromatic oxycarboxylic acid includes hydroxybenzoic acid, hydroxynaphthoic acid and the like.
Alternatively, alkyl, alkoxy, halogen-substituted products of the above aromatic oxycarboxylic acids and the like can be mentioned. As the aromatic dicarboxylic acid, terephthalic acid, isophthalic acid, diphenyldicarboxylic acid, naphthalenedicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylethanedicarboxylic acid, or the like, or alkyl, alkoxy, or halogen of the aromatic dicarboxylic acid Substitutes and the like.

Examples of the aromatic diol include hydroquinone, resorcin, dioxydiphenyl, naphthalene diol and the like, or the above-mentioned aromatic alkyl, alkoxy,
And halogen-substituted products. Examples of the aliphatic diol include ethylene glycol, propylene glycol, butanediol, and neopentyl glycol.

In the present invention, polyesters obtained by polymerizing the above monomers and the like can be widely used. Preferred examples thereof include those in which a p-hydroxybenzoic acid component and an ethylene terephthalate component are copolymerized, those in which a p-hydroxybenzoic acid component, 4,4-dihydroxybiphenyl and terephthalic acid or isophthalic acid are copolymerized, p-hydroxybenzoic acid component and 6-hydroxy-2
Those obtained by copolymerizing a -naphthoic acid component, those obtained by copolymerizing a p-hydroxybenzoic acid component, a 6-hydroxy-2-naphthoic acid component, hydroquinone, and terephthalic acid can be used.

The melting liquid crystal forming polyester preferably has a melting point (MP) in the range of 260 to 360 ° C.
More preferably, MP is 270-350 degreeC. MP was measured by measuring a temperature at which a main endothermic peak observed by a differential scanning calorimeter (DSC manufactured by Perkin Elmer) appears.

The polycyclohexane dimethanol terephthalate as the sheath component of the present invention is a polyester obtained by using terephthalic acid as a main acid component and 1,4-cyclohexane dimethanol as a main glycol component. However, it may contain another copolymer component capable of forming an ester bond at a ratio of 20 mol%, more preferably 10 mol% or less. Compounds that can be copolymerized include:
Dicarboxylic acids such as isophthalic acid, succinic acid, cyclohexanedicarboxylic acid, adipic acid, dimeric acid, and sebacic acid as acidic components, and glycol components such as ethylene glycol, diethylene glycol, butanediol, neopentyl glycol, cyclohexanedimethanol, and polyethylene as glycol components Glycol, polypropylene glycol, and the like can be used, but are not limited thereto.

[0012] The core component polymer and the sheath component polymer used in the present invention are added within a range that does not impair the effects of the present invention.
Polyethylene terephthalate, modified polyethylene terephthalate, polyolefin, polycarbonate, polyarylate, polyamide, polyester ether ketone,
A thermoplastic polymer such as a fluorine resin may be added. In addition, various additives such as inorganic substances such as titanium oxide, kaolin, silica, and barium oxide, carbon black, coloring agents such as dyes and pigments, antioxidants, ultraviolet absorbers, and light stabilizers may be added.

The composite fiber of the present invention can be obtained by a known core-sheath composite spinneret. The cross-sectional shape of the obtained fiber includes not only a round core component but also a composite shape having an irregular cross section or a multi-core structure, for example, the one shown in FIG.

The composite fiber of the present invention has a core / sheath ratio of 90/10.
It is preferably in the range of 50/50 to 50/50, and more preferably in the range of 80/20 to 70/30. The sheath component ratio is preferably 10% or more in order to sufficiently cover the core component and prevent fibrillation due to friction and wear. In order to obtain a high-strength and high-modulus fiber, the content is preferably 50% or less.

Although the conjugate fiber of the present invention already has sufficient strength and elastic modulus only by spinning, its performance can be further improved by relaxation heat treatment or strain heat treatment.

The heat treatment can be performed in an atmosphere of an inert gas such as nitrogen, an atmosphere of an active gas containing oxygen such as air, or under reduced pressure. Heat treatment atmosphere has a dew point of -4
A low humidity gas of 0 ° C. or lower is preferred. As heat treatment conditions,
It is preferable that the temperature is gradually increased from the melting point of the core component minus 40 ° C. or less to the melting point of the sheath component or less. Further, the processing time is several minutes to several tens hours depending on the target performance.

Heat is supplied at the time of heat treatment by a method using a medium such as a gas, a method using radiation from a heating plate or an infrared heater, a method using a medium in contact with a heat roller, a heat plate, or the like, a high frequency or the like. An internal heating method or the like can be used. The heat treatment may be performed under tension or non-tension depending on the purpose, and the shape may be a scallop shape, a tow shape (for example, placed on a metal net or the like), or a continuous treatment between rollers. Further, the form of the fiber may be either a filament form or a cut fiber form. The tension heat treatment is preferably performed at a temperature not higher than the melting point of the core component minus 60 ° C. and under a tension of 5 to 50% of the cutting strength, and this treatment further improves the elastic modulus.

As described above, the fiber produced by the present invention retains the characteristics of high strength and high elastic modulus, and has remarkably improved fibrillation resistance, fatigue resistance, flame retardancy, and friction and fusion resistance. It can be dyed and can be used for general industrial materials, civil engineering and construction materials, sports applications, protective clothing, rubber reinforcement materials, electrical materials (especially as tension members),
It is widely used in the field of acoustic materials and the like, but is particularly suitable for use in the form of a woven fabric. Particularly effective applications are screen gauze, computer ribbon, base fabric for printed board, canvas for gauze, air bag, airship, dome, etc., rider suit, fishing line, various lines (yacht, paraglider, balloon , Kite yarns), PET chain substitute yarns, blind cords, screen door support cords, various cords in automobiles and aircraft, power transmission cords for electric appliances and robots, and the like.

[0019]

The present invention will be described in more detail with reference to the following examples. In addition, the strong elongation and elastic modulus in the examples are based on JIS L101.
Orientec Tensilon UCT-100 according to 3
It measured using.

Example 1 Structural unit (1) formed from p-acetoxybenzoic acid, structural unit (2) formed from 4,4-dihydroxybiphenyl and terephthalic acid, and ethylene glycol were used as the core liquid crystal-forming polyester. It is composed of the structural unit (3) of the polyester formed from terephthalic acid. The structural unit (1) occupies 80 mol% of the whole, and the total of the structural unit (2) and the structural unit (3) occupies 20 mol%. 2) / (3) molar ratio is 3/5
Was used. .

As the sheath component, substantially polycyclohexane terephthalate (Theman manufactured by Eastman Chemical Co., Ltd.) is used.
rmx part number 3879).

Using a molten liquid crystal forming polyester resin as a core and a polycyclohexane terephthalate resin as a sheath, a core / sheath composite ratio of 65/35, a spinning temperature of 320 ° C., and a nozzle diameter of 0.1 mm.
13mmφ, discharge from 10 holes, spinning speed 1
Spinning was performed at 000 m / min to obtain a 50 dtex filament. At this time, a good wound yarn could be obtained without clogging of the discharge hole and bending of the discharge. The properties of the obtained spun yarn were as follows: strength 5.6 cN / dtex, elongation 2.1.
% And an elastic modulus of 450 cN / dtex. The spun yarn was heat-treated in a nitrogen gas atmosphere at 250 ° C. for 2 hours, 260 ° C. for 2 hours and 270 ° C. for 6 hours. The heat-treated yarn obtained had almost no sticking between fibers and had the following performance. Strength 18.2 cN / dtex, elongation 3.2%, elasticity 545 cN / dtex Example 2 As a molten liquid crystal forming polyester as a core component, 60 mol% of p-hydroxybenzoic acid and 20 mol% of 4,4-dihydroxybiphenyl A 70 dtex filament was obtained in the same manner as in Example 1 except that a molten liquid crystal-forming polyester containing 10 mol% of terephthalic acid and 10 mol% of isophthalic acid was used. At this time, a good wound yarn could be obtained without clogging of the discharge hole and bending of the discharge. The performance of the obtained spun yarn has a strength of 3.6 cN / dte.
x, elongation 1.9%, elastic modulus 420 cN / dtex. The spun yarn was heat-treated in a nitrogen gas atmosphere at 250 ° C. for 2 hours, 260 ° C. for 2 hours and 270 ° C. for 6 hours.
The obtained heat-treated yarn had almost no sticking between fibers, and had the following performance. Strength: 16.2 cN / dtex, elongation: 2.8%, elasticity: 593 cN / dtex
50 dtex in the same manner as in Example 1 except that a molten liquid crystal-forming polyester resin of
Was obtained. At this time, it was possible to obtain a good wound yarn without clogging of the discharge hole and bending of the discharge.
The performance of the obtained spun yarn has a strength of 8.6 cN / dte.
x, elongation 2.2%, elastic modulus 45 cN / dtex. The spun yarn was heat-treated in a nitrogen gas atmosphere at 250 ° C. for 2 hours, 260 ° C. for 2 hours and 270 ° C. for 6 hours.
The obtained heat-treated yarn had almost no sticking between fibers, and had the following performance. Strength 17.4 cN / dtex, elongation 2.4%, modulus 530 cN / dtex

[0023]

According to the present invention, there is provided a polyester having a high strength and a high modulus of elasticity of a molten liquid crystal-forming polyester, having no surface fibrillation, and having excellent wear resistance and fatigue resistance. Successful.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a typical conjugate fiber of the present invention.

Continued on the front page F term (reference) 4L041 AA07 AA25 BA02 BA04 BA05 BA13 BA24 BC18 BC20 BD01 BD02 BD06 CA05 CA10 DD01 DD15

Claims (2)

[Claims] 1. A high-strength conjugate fiber comprising a molten liquid crystal-forming polyester as a core component and a polycyclohexane dimethanol terephthalate as a sheath component of at least 80 mol%. 2. The core-sheath composite fiber has a core-sheath composite ratio of 90/10.
The high-strength conjugate fiber according to claim 1, wherein the ratio is from 50 to 50/50.