JP3266712B2 - Composite fiber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conjugate fiber having high strength and high elastic modulus, which is excellent in wear resistance and fatigue resistance, and is used in general industrial materials, particularly ropes,
It is widely used for rubber reinforcement, geotextiles, FRC applications, computer ribbons, print base fabrics, air bags, bag filters, screen gauze, and the like.

[0002]

2. Description of the Related Art An aromatic polyester fiber capable of forming an anisotropic molten phase is, for example, as disclosed in JP-A-61-174408, because its molecular chains are highly oriented in the fiber axis direction. It is known to have high strength and high elastic modulus. However, since only a weak intermolecular force acts in a direction perpendicular to the fiber axis, fibrils are easily generated by friction, causing trouble. In addition, since a kink band and a buckling phenomenon are liable to occur, and they tend to be concentrated in extreme places, fatigue resistance is low. For the purpose of remedying these drawbacks, a composite fiber composed of an aromatic polyester whose core component can form an anisotropic molten phase and a polyphenylene sulfide sheath component has been proposed by the present inventors in JP-A-1-229815. Have been.

[0003]

Problems to be Solved by the Invention
As described in Japanese Patent Publication No. 5 (1999) -2005, it is true that the formation of a core-sheath structure improves fibrillation resistance and abrasion resistance. However, polyphenylene sulfide, which is a flexible polymer having a sheath component, is not yet available. Because of the stretched state, problems such as peeling of the sheath often occurred. Furthermore, the softening point of polyphenylene sulfide is low, and when heat treatment is performed at a temperature higher than the softening point, sticking between filaments occurs. Therefore, it has been difficult to employ heat treatment conditions sufficient for increasing the strength. As a result of intensive studies, the present invention has found a high-strength high-modulus fiber having significantly improved sheath peeling, fibrillation resistance and fatigue resistance.

[0004]

According to the present invention, there is provided an aromatic polyester in which a core component A can form an anisotropic molten phase, a sheath component B
Is a semi-aromatic polyamide, wherein the area ratio R = B / (A + B) of the B component in the cross section of the fiber is 0.1 to 0.5. Things.

[0005] The term "melt anisotropy" as used in the present invention means to show optical anisotropy in a molten phase. This characteristic can be recognized, for example, by placing the sample on a hot stage, heating and heating the sample in a nitrogen atmosphere, and observing the transmitted light of the sample. As the melt anisotropic polymer used in the present invention,
For example, a polymer composed of a combination of repeating structural units shown in the following (1) to (10) is exemplified.

[0006]

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[0007] A preferred melt anisotropic polymer has a melting point (MP) in the range of 260 to 360 ° C, and more preferably has a MP of 270 to 350 ° C. M
The measurement of P was performed by measuring the temperature at which the main endothermic peak observed by a differential scanning calorimeter (DSC manufactured by Mettler) appeared. The most preferred example of the melt anisotropic polymer used in the present invention is a polymer comprising a repeating structural unit represented by the following chemical formula 2.

[0008]

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A wholly aromatic polyester in which the portion composed of the repeating structural units (E) and (F) is at least 80 mol% is particularly preferred. Among them, a wholly aromatic polyester in which the component (F) accounts for 3 to 45 mol% is most preferable.

[0010] The semi-aromatic polyamide according to the present invention is a polyamide obtained from an aliphatic diamine and a dicarboxylic acid mainly containing an aromatic component. The aliphatic diamine is represented by the following formula, and preferably has n = 4 to 12, more preferably n = 6 and n = 9. n = 9 is particularly preferred. NH ₂ - (CH ₂₎ and the n-NH ₂ (G) a dicarboxylic acid mainly containing an aromatic component, at least 6
0 mol% or more is an aromatic dicarboxylic acid.
Preferred examples include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid and the like. Examples of the combination of an aliphatic diamine and an aromatic dicarboxylic acid include n =
Preferred is a combination of 9 aliphatic diamines and terephthalic acid.

Further, the sheath component polymer is prepared at 30 ° C., 0.2
g / dl, logarithmic viscosity η _inh measured in concentrated sulfuric acid is 0.5
To 3 dl / g, preferably 0.7 to 2 dl / g.
g is more preferred. Further, the melting point is preferably higher than the melting point of the core polymer.

[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, polyphenylene sulfide,
A thermoplastic polymer such as a polyether ether ketone or 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 conjugate fiber of the present invention can be obtained by a known method, for example, by a nozzle structure shown in FIG. The cross-sectional shape of the obtained fiber includes, for example, that shown in FIG. In the figure, A is a core component polymer, and B is a sheath component polymer. The effect of the present invention is that the sectional area ratio (R) is 0.1 to 0.5.
It is demonstrated when The cross-sectional area ratio referred to in the present invention means that when the cross-sectional area of the core component is A and the cross-sectional area of the sheath component is B, R = B /
It is represented by (A + B). The cross-sectional area ratio can be obtained from a micrograph of the cross section of the fiber, but can also be obtained from the volume ratio of the discharge amount of the core and the sheath at the time of production.

When the area ratio is less than 0.1, the sheath component is not sufficiently covered, and a part of the core may be exposed or peeled off due to friction or wear. Conversely, if it exceeds 0.5, the core component becomes relatively small, and the fiber has low strength and low elastic modulus.

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. The heat treatment atmosphere is preferably a low humidity gas having a dew point of −40 ° C. or less. The heat treatment is preferably performed in a temperature pattern in which the temperature is sequentially increased from the melting point of the core component minus 40 ° C. or less to the melting point of the sheath component or less. The processing time is from several minutes to several tens of hours depending on the target performance.

The heat is supplied by a method using a medium such as a gas,
A method using radiation from a heating plate, an infrared heater, etc.,
There are a method of contacting with a heat roller, a heat plate, or the like, and an internal heating method using high frequency or the like. The heat treatment may be performed under tension or non-tension depending on the purpose, and may be in the form of a scab, a tow (for example, placed on a metal net or the like), or a continuous treatment between rollers. The fiber may be in the form of a filament or a cut fiber. The tension heat treatment is advantageously carried out at a temperature below the melting point of the core component minus 60 ° C. and under a tension of 5 to 50% of the cutting strength, whereby the elastic modulus is further improved.

The sheath component polymer used in the present invention has a very high crystallization rate and is easy to be oriented. Therefore, even when spun at a relatively low speed and a low draft, sufficient oriented crystallization occurs. In addition, it can exhibit sufficient fiber performance without a stretching step, and is extremely excellent in operation. As described above, the fiber of the present invention retains the characteristics of high strength and high elastic modulus, and has significantly improved fibrillation resistance, fatigue resistance, flame retardancy, friction fusibility, and dyeing. It is widely used in the fields of general industrial materials, civil engineering and construction materials, sports applications, protective clothing, rubber reinforcing materials, electrical materials (especially as tension members), and acoustic materials. Suitable for use in form. Particularly effective applications are screen gauze, computer ribbon, base cloth for print base, airbag, airship, base cloth for dome, rider suit,
There are fishing lines, various lines (yachts, paragliders, balloons, kite lines), substitute chains for PET, blind cords, support cords for screen doors, various codes in automobiles and aircraft, and power transmission codes for electric products and robots.

[0018]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. Example 1 As the core component A, the structural units (E) and (F) were 72/2
An aromatic polyester polymer forming an anisotropic molten phase of 8 mol% was used. The physical properties of this polymer were as follows: MP = 279 ° C., MV = 390 poise, η _inh = 4.43
dl / g. Melting point MP is TA-3000 manufactured by Mettler.
It is an endothermic peak temperature determined by DSC. Melt viscosity MV
Is a value at a temperature of 300 ° C. and a shear rate γ = 1000 sec ⁻¹ using Toyo Seiki Cabilograph Model 1B. The logarithmic viscosity η _inh is a value obtained by dissolving a sample in pentafluorophenol at 0.1% by weight (60 to 80 ° C.) and measuring with an Ubbelohde capillary viscometer in a thermostat at 60 ° C. . η _inh = 1n (η _rel ) / C As the sheath component B, [G] η _inh = 0.92 dl / g composed of a diamine of formula n = 9 and terephthalic acid, MP = 317 ° C.
Was used.

With an area ratio R = 0.33, a nozzle diameter of 0.15 mmφ of the structure shown in FIG.
Spinning was performed at 0 ° C. and a spinning speed of 1000 m / min to obtain a filament of 250 denier. The performance of the obtained spun yarn was strength (DT): 9.7 g / d elongation (DE): 2.2% and elastic modulus (IM): 547 g / d. Also, when the DSC measurement of the spun yarn was performed, since the sheath component of the spun yarn had already been oriented and crystallized, the crystallization hardly proceeded even if heating was performed for the DSC measurement. Almost no exothermic peak due to crystallization was observed. This spun yarn is 26
Heat treatment was performed at 0 ° C. for 2 hours and at 277 ° C. for 10 hours in a nitrogen gas atmosphere. The heat-treated yarn obtained had almost no sticking between fibers and had the following performance. Strength (DT): 22.6 g / d Elongation (DE): 3.5% Modulus (IM): 595 g / d

Example 2 The aromatic component polymer forming the anisotropic melt phase of Example 1 was used as the core component polymer, and the diamine of the formula [G] n = 6 and adipic acid as the dicarboxylic acid component were used as the sheath component polymer. / Isophthalic acid / terephthalic acid = 10/20 /
Η _inh consisting of 70 = 0.98 dl / g, MP = 310
A semi-aromatic polyamide polymer at ℃ was used. Except that the spinning temperature was set to 340 ° C., 25
A 0 denier filament was obtained. The performance of the obtained spun yarn was strength (DT): 8.0 g / d, elongation (DE): 1.9%, and elastic modulus (IM): 530 g / d. Heat treatment was performed in the same manner as in Example 1, and the obtained fiber showed almost no sticking between yarns, and the performance was as follows: strength (DT): 20.7 g / d elongation (DE): 3.4% elasticity Rate (IM): 567 g / d 2.

Comparative Example 1 An aliphatic polyamide nylon 66 was used as a sheath component.
A 250 denier filament was obtained in the same manner as in Example 2, except that the fiber was spun at a temperature of 307 ° C. The performance of the obtained spun yarn was strength (DT): 7.2 g / d elongation (DE): 1.8% and elastic modulus (IM): 507 g / d. In addition, when the DSC measurement of the spun yarn was performed, since the sheath component of the spun yarn was hardly oriented and crystallized, the crystallization proceeded by heating during the DSC measurement, and the exothermic peak based on the crystallization of the polyamide became clear. Appeared. The spun yarn was heat-treated in a nitrogen gas atmosphere at 240 ° C. for 2 hours and at 250 ° C. for 10 hours. The obtained heat-treated yarn had severe agglomeration between yarns and fibers, and fluff occurred frequently during rewinding. The performance was strength (DT): 13.1 g / d, elongation (DE): 2.0%, and elastic modulus (IM): 510 g / d. Since the heat treatment temperature was low, the performance was slightly improved. When the temperature was further raised and the same heat treatment as in Example 1 was performed, it was impossible to rewind the yarn because the sticking was extremely severe. Comparative Example 2 Using only the core component polymer of Example 1 with a nozzle diameter of 0.13 mm
Spinning was performed at a spinning temperature of 315 ° C. and a spinning speed of 1000 m / min using a φ, 50-hole die to obtain a filament of 250 denier. The performance of the obtained spun yarn was strength (DT): 12.1 g / d elongation (DE): 2.0% and elastic modulus (IM): 570 g / d. This was heat-treated in the same manner as in Example 1. The performance of the obtained heat-treated yarn was as follows: strength (DT): 26.0 g / d elongation (DE): 3.7%, elastic modulus (IM): 612 g / d. Table 1 shows comparison results of the fibers of Examples 1 and 2 and Comparative Examples 1 and 2 with respect to fibrillation resistance, inter-fiber wear and fatigue resistance.
Shown in

[0022]

[Table 1]

The term "fibrillation resistance" as used in the present invention means that the yarn is passed through a three-point chrome mirror guide rod forming an angle of 90 degrees under a tension of 100 g and adhered to a guide when the yarn is run at 100 m / min for 1 hour. Depending on the amount of fibrils to be evaluated, a large sample was evaluated as x, a sample with almost no sample was evaluated as 、, and a sample with no sample was evaluated as ◎. The inter-fiber abrasion referred to in the present invention refers to a method in which 250 denier filaments are drawn together, twisted 80 t / m to make a twisted yarn, twisted three times, and a load of 2 kg is applied to the yarn. Is abraded between fibers by reciprocating motion, and the number of reciprocating motions until cutting is obtained. The term "fatigue resistance" as used in the present invention refers to a belt bending test method in which 250 denier filaments are drawn and aligned to form a 315 t / m upper-twisted and lower-twisted twin yarn, a cord is embedded in rubber to form a belt, and a belt bending test is performed. With 45mmφ pulley diameter
The evaluation was made based on the strength retention after bending for 10,000 times.

In Examples 1 and 2, since the sheath component was sufficiently oriented and crystallized, both the strength and the elastic modulus were high, and the fibrillation resistance and the fatigue resistance were excellent. On the other hand, in Comparative Example 1, oriented crystallization did not progress because the aliphatic polyamide was used as the sheath component polymer, and therefore the strength was necessarily low. Moreover, since the strength of the sheath fiber is low, the sheath fiber is easily loosened by friction and the sheath fiber peels off, and the fatigue resistance is extremely low. Comparative Example 2
Has only excellent strength and elastic modulus because it uses only the melt-anisotropic aromatic polyester, but does not improve the drawback that it is easily fibrillated.

Further, using the fibers of Example 1 and Comparative Example 2,
A taffeta with a warp yarn density of 48 yarns / inch and a weft yarn density of 48 yarns / inch was woven. When weaving using the fiber of Example 1,
Almost no fibrillation and no trouble 100
Weaving of 0 m was possible. On the other hand, in the case of Comparative Example 1, poor opening of the warp yarn due to fibrillation frequently occurred, frequent stoppage occurred, and weaving over 200 m was impossible.

[0026]

According to the present invention, even when spun at a relatively low speed and a low draft, the sheath component has a high strength and a high elastic modulus by sufficiently proceeding the oriented crystallization of the sheath component, and It has succeeded in providing a fiber which does not undergo surface fibrillation and has excellent wear resistance and fatigue resistance.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a spinning device used for producing a conjugate fiber of the present invention.

FIG. 2 is a cross-sectional view of a typical conjugate fiber of the present invention.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-272226 (JP, A) JP-A-5-214694 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) D01F 8/12-8/14 D01F 6/80

Claims (1)

(57) [Claims] An area ratio of a B component occupying a cross section of the fiber, wherein the core component A is an aromatic polyester capable of forming an anisotropic molten phase, and the sheath component B is a semi-aromatic polyamide. R = B / (A + B) is 0.1-0.5.