JP2593908B2 - High strength high modulus fiber with improved fatigue resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a high-strength, high-modulus fiber having improved fatigue resistance. The fibers obtained by the method of the present invention are also suitable for such uses.

1. Valve-shaped materials 1) Wear materials (mixed use with other fibers, reinforcement of resin) Brake lining, clutch facing, bearings 2) Other packing materials, gaskets, filtration materials, abrasive materials 2. Cut fibers Used in the form of chopped yarn paper (insulating paper, heat-resistant paper), vibrating material for speakers, cement reinforcing material, resin reinforcing material 3. Filament, spun yarn, used in yarn shape Tension member (optical fiber, etc.) ), Rope, cord, lifeline, fishing line, longline 4. What is used in the form of woven or knitted fabric, lining of automobiles, trains, ships, airplanes, etc. Heat and flame resistant clothing, muffler, apron), artificial tendon 5. Rubber, used for resin reinforcement 1) Rubber tires, belts, various timing belts Hose rubber reinforcement materials 2) Resin-related (carbon and glass fiber hybrid skis, golf clubs and gateball heads and shafts, helmets, butts, tennis and badminton rackets, eyeglass frames, print bases, motor rotation Child slot, insulation, pipe, high pressure vessel,
Examples include primary or secondary structures such as automobiles, trains, ships, and airplanes.

[Conventional technology]

A technique for producing a high-strength high-modulus fiber by spinning an aromatic polyester polymer capable of forming an anisotropic melt under appropriate conditions (heat treatment and / or stretching if necessary) is disclosed in JP-B-55-2008. And JP-A-60-239600.

[Problems to be solved by the present invention]

Fibers obtained from an aromatic polyester capable of forming an anisotropic molten phase have a high degree of molecular orientation, high strength and high elastic modulus. In particular, 6-hydroxy-2-naphthoic acid and p-
Hydroxybenzoic acid polyester has very good fiber-forming ability, high strength and high elastic modulus, and has excellent performance such as heat resistance and chemical resistance. It is an excellent high-performance fiber (JP-A-54-77691).
No.).

However, since these fibers have a highly oriented fibril structure, they tend to buckle or generate kink bands when subjected to fatigue, especially compression fatigue. for that reason,
Improvements have been desired in applications such as tires and belts that undergo compression fatigue in rubber.

Further, since the surface is fibrillated and easily peeled off, fuzz is formed by the guide, the strength is reduced, and the peeling strength of rubber or resin is reduced.

The present inventors have conducted intensive studies, and as a result, provided a high-strength, high-modulus fiber having no surface fibrillation at all and significantly improved fatigue resistance.

[Means for solving the problem]

According to the present invention, the core component A is an aromatic polyester capable of forming an anisotropic molten phase, and the sheath component B is a composite spun fiber comprising at least 80% by weight of polyphenylene san sulfide. Area ratio of B component in the cross section of fiber B /
(A + B) is 0.05 to 0.5, and is a high-strength high-modulus fiber with improved fatigue resistance, which is characterized by being subjected to heat treatment.

The aromatic polyester capable of forming an anisotropic melt phase referred to in the present invention is a polymer containing an aromatic diol, an aromatic dicarboxylic acid, an aromatic hydroxycarboxylic acid, or the like as a main component, and has an optical anisotropic property in the melt phase. It shows the nature.
Such characteristics can be easily identified by heating the sample placed on the hot stage under a nitrogen atmosphere and observing the transmitted light.

Preferred examples of the anisotropic melt used in the present invention include a combination of the following repeating components.

The effect of the present invention is most remarkably exhibited, The polymer according to the present invention is essentially a polymer in which the portion composed of the following repeating units [I] and [II] is 80% by weight or more, particularly an aromatic polyester in which the component [II] is 5 to 45%.

In the present invention, 80% by weight or more of the B component mainly composed of polyphenylene sulfide is used. And may contain less than 20% by weight of other polymers, copolymers and additives. A preferred example is a blend of less than 20% polyester.

The conjugate fiber referred to in the present invention has a core component composed of the component A and a sheath component composed of the component B, and has an area ratio R = B / (A + B) of the sheath component (component B) in the cross section.
(However, A and B are the areas of the core and the sheath determined from the micrograph of the fiber cross section) are 0.05 to 0.5, preferably 0.1 to 0.5.
It is in the range of 0.3. Here, if R is less than 0.05, the sheath component is not sufficiently coated, and a part of the core is exposed,
It comes off easily due to wear. Conversely, if it exceeds 0.5, the ratio of the core component decreases, and as a result, the strength and the elastic modulus decrease, which is not suitable for the purpose of the present invention.

In order to obtain a conjugate fiber, the fiber is spun by a known method, for example, the apparatus shown in FIG. Preferred conditions for the core component are as follows: the spinning temperature is at least 10 ° C. higher than the higher melting point of each of the components A and B, and the core component should have a shear rate () at the time of discharge in order to obtain a high degree of orientation. It is preferred to be 10 ³ sec ^-1 or more.

The shear rate () referred to in the present invention means that the nozzle diameter is r (c
m), when the discharge amount of polymer per single hole is Q (cm ³ / sec) Is calculated.

The cross-sectional shape of the conjugate fiber can be various types as shown in FIG. 2 in addition to the simple core-sheath type.

In the present invention, the raw yarn obtained by melt-spinning is further heat-treated to further improve various properties of the fiber. The heat treatment can be performed in an inert atmosphere such as nitrogen, an active atmosphere containing oxygen such as air, or in a vacuum. Preferred temperature conditions are A
Assuming that the melting point of the component is MP, a pattern in which the temperature is sequentially increased from MP-40 ° C or lower in the range of MP-60 ° C to MP + 20 ° C is more preferable. The processing time can be from several seconds to tens of hours depending on the desired performance.

When a medium such as a gas is supplied, there are a method using radiation from a heating plate, an infrared heater, etc., a method using contact with a heat roller, a 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 shape of the treatment is a scallop, cheese, tow (for example, placed on a wire mesh) or a continuous treatment between rollers. The form of fiber is filament,
Any cut fiber is possible.

The stretching is conveniently carried out at a temperature lower than the melting point of the component A by at least 60 ° C. and 10 to 60% of the elongation at break. This treatment improves the elastic modulus.

The present invention provides a surface fibril, which is the most significant feature of fibers composed of a molten liquid crystal polymer as a core component, while maintaining high strength, a high elastic modulus, dimensional stability, heat resistance, and chemical resistance as it is, and the greatest defect. It is a material that has significantly improved compression fatigue resistance.

The fibrillation referred to in the present invention means that the yarn is passed through a three-point titanium guide under a tension of 100 g and run at 100 m / min for 1 hour, and the larger the amount, the more the fiber is attached. Those that did not come out were evaluated as ○, and the middle was evaluated as Δ.

The abrasion referred to in the present invention means that ten sample yarns are aligned,
Twist 1.5 times between the reversing rotator and the pulley at the other end, set in figure 8 and apply a load of 36kg to the pulley. And a 1/10 g / d load, and a grindstone abrasion test showing the number of cuts using a 10 cm diameter round whetstone (rotation speed: 100 times / min, contact angle: 100 degrees).

The evaluation of fatigue resistance is based on a belt bending test method in which a 1500dr (500dr x 3) yarn is used as a twin yarn of 280T / m and 280T / m, and a cord is made and embedded in rubber. After 250,000 treatments, the test was performed with a strong retention rate.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited thereto.

Example 1 As the component A, a wholly aromatic polyester polymer in which the structural units [I] and [II] had a ratio of 7/3 mol% was used.
The physical properties of this polymer are ηinh = 6.0 dl / g MP = 278 ° C.

 The intrinsic viscosity (ηinh) was determined as follows.

A sample is dissolved in pentafluorophenol at 0.1% by weight (60 to 80 ° C.), and the sample is measured in a thermostat at 60 ° C. with an Upperod viscometer.

The melting point (MP) is an endothermic peak temperature determined by DSC.

As the component B, a polymer substantially consisting of polyphenylene sulfide and having a melt viscosity at 300 ° C. and = 1000 sec ⁻¹ of 400 vise was used.

The composite ratio (weight ratio) of component A and component B is 7.5 / 2.5
The spinning temperature is 320 ° C from the 100-hole die shown in Fig. 1.
Was discharged. The winding speed was 830m / min, and a filament of 500dr / 100f was obtained.

 Yarn denier (DR): 503dr Strength (DT): 9.02 g / d Elongation (DE): 2.80% Initial elastic modulus (IM): 510 g / d B component area ratio (R): It was 0.31.

This spun yarn is wound around a perforated aluminum bobbin with a density of 0.62 g /
It was wound with CC and heat-treated at 260 ° C for 1 hour, from 270 ° C to 280 ° C for 4 hours, and from 280 ° C to 285 ° C for 12 hours. The performance of the heat-treated yarn obtained was DR: 501dr DT: 22.8 g / d DE: 4.72% IM: 573 g / d.

Examples 2 to 6, Comparative Examples 1 and 2 Except that various changes were made to the composite ratio of the A and B polymers in Example 1, and that yarn denier was changed, various methods were carried out in substantially the same manner as in Example 1. A heat-treated yarn was obtained. The results are summarized in Table 1.

Comparative Example 2 is low in strength and initial elastic modulus.

In Examples 5 and 6, the denier of the core was made substantially the same as that of Comparative Example 1.

 Table 2 shows the results of each evaluation.

In any of the examples of the present invention, fibrillation did not occur at all, and in Examples 1 to 4 in which the yarn denier was the same, the improvement between the inter-fiber abrasion and the grinder abrasion was slightly improved, but the core component denier was the same. In comparison, the values are almost twice as large.

The most remarkable effect of the present invention is fatigue resistance, which is a remarkable improvement. This is because the presence of the sheath component softens the compression of the core component and the good chemical resistance of polyphenylene sulfide covers chemical damage such as amine decomposition in rubber. It is estimated to be.

[Brief description of the drawings]

FIG. 1 is a sectional view of an essential part showing an example of a spinneret for obtaining the conjugate fiber of the present invention, and FIG. 2 is an example showing a cross-sectional shape of the conjugate fiber of the present invention.

 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-204920 (JP, A) JP-A-54-77691 (JP, A)

Claims (2)

(57) [Claims] 1. A composite spun fiber in which the core component A is an aromatic polyester capable of forming an anisotropic molten phase, and the sheath component B is a composite spun fiber comprising at least 80% by weight of polyphenylene sulfide. Area ratio B / (A +
B) is 0.05 to 0.5, and is a heat-treated high-strength high-modulus fiber with improved fatigue resistance. 2. The core component A is a melt-anisotropic aromatic polyester in which a component consisting essentially of the following repeating units [I] and [II] is at least 80% by weight. 2. A high-strength, high-modulus fiber having improved fatigue resistance according to 1.