JPH03279418A - Conjugate fiber for reinforcing rubber - Google Patents

Abstract

PURPOSE:To obtain the subject high-modulus fiber having polyethylene terephthalate as a core component and a copolyamide, based on nylon 66 and containing specific aromatic amide units as a sheath component at a specific ratio of the core to the sheath parts. CONSTITUTION:The objective fiber having polyethylene terephthalate as a core component and a copolyamide, based on nylon 66 and containing 1-20mol.% aromatic amide units expressed by the formula {X and Y are 1, 4-phenylene, 2,6-naththylene, 4,4'-biphenylene or -phi-Z-phi- [phi is 1,4-phenylene; Z is -O-, -S-, -SO2-, -CO-, -NH-, -CH2- or -C(CH3)2-]} at (50/50)-(90/10), preferably (70/30)-(80/20) weight ratio of the core to the sheath parts.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a composite fiber for rubber reinforcement made of polyester and polyamide.

(Prior art) Fibers made of polyamides such as nylon 6 and nylon 66 and polyesters such as polyethylene terephthalate are widely used as fibers for reinforcing rubber such as tire cords, but these fibers have advantages and disadvantages. There is. In other words, polyamide fibers have excellent fatigue resistance and impact resistance.

High shrinkage rate and tends to cause flat spots.

It also has the drawbacks of high water absorption and low modulus. On the other hand, polyester fibers do not have the problem of generating flat spots and have a high modulus, but they have the drawbacks of being easily hydrolyzed in rubber and having poor adhesion to rubber.

Therefore, in order to take advantage of the advantages of polyamide and polyester, it has been proposed to make composite fibers with polyester as a core component and polyamide as a sheath component (for example,
No. 9-85315, No. 56-140128, etc.). However, such composite fibers made of components with completely different molecular structures have a problem in that phase separation occurs and the two components peel off, resulting in fluff during the twisting process.

In order to solve this problem of peeling between the image components and provide a high-strength conjugate fiber, Japanese Patent Application Laid-Open No. 1-97211 discloses nylon 66/6T, which is made by copolymerizing nylon 66 with a terephthalic acid component, as a polyamide. Composite fibers have been proposed. but.

Polyamides copolymerized with only the terephthalic acid component do not have sufficient modulus, resulting in a problem that the modulus of composite fibers becomes low.

(Problems to be Solved by the Invention) The present invention aims to improve the modulus of the polyamide in a rubber reinforcing composite fiber containing polyester as a core component and polyamide as a sheath component, and to produce a rubber reinforcing composite fiber having a high modulus as a composite fiber. This is what we are trying to provide.

(Means for Solving the Problems) In order to solve the above problems, the present inventors, as a result of various studies, copolymerized a unit containing a rigid aromatic ring in one molecular chain based on nylon 66 as a polyamide. The present invention was achieved by discovering that it is advantageous to use a copolyamide prepared by the following methods.

That is, the gist of the present invention is as follows.

A composite fiber whose core component is polyethylene terephthalate, and whose sheath component is a copolyamide based on nylon 66 and containing 1 to 20 mol% of aromatic amide units represented by the following general formula. Weight ratio is 50150~9
Composite fiber for rubber reinforcement characterized by a ratio of 0/10.

-HN-X-NH-OC-Y-CO- [In the formula, x and y are 1.4-7 enylene groups.

2.6-naphthylene group, 4.4'-biphenylene group or -φ-2-φ- [φ is 1,4-phenylene group.

Z is -o-, -s-, -so, -, -co-.

-NH-, -CH2- or -C(CH3)2 ].

The present invention will be explained in detail below.

First, in the present invention, polyethylene terephthalate (including what is essentially recognized as polyethylene terephthalate, hereinafter referred to as PET) is used as the polyester of the core component.

As the sheath component, a copolyamide based on nylon 66 (polyxamethylene adipamide) and containing an aromatic amide unit represented by the above-mentioned formula is used.

Specific examples of aromatic diamines for constituting aromatic amide units include 1,4-phenylenediamine, 2,6-
naphthalenediamine, 4,4'-diaminobiphenyl,
4.4'-diaminodiphenylmethane.

4,4'-diaminodiphenylsulfone, 1,2-bis-p-aminophenylethane, etc., and specific examples of aromatic dicarboxylic acids include terephthalic acid.

Examples include 2.6-naphthalene dicarboxylic acid, 4.4'-diphenyldicarboxylic acid, 4.4'-dicarboxydiphenyl ether, 1.2-bis-p-carboxyphenylmethane, and the like.

Such copolyamides can be produced by the method disclosed in Japanese Patent Publication No. 63-66851.

And the proportion of aromatic amide units in the copolyamide should be in the range of 1 to 20 mol%.

If the ratio is lower than this, the modulus will not be improved sufficiently, and if it is higher than this ratio, the difference in melting point from the core component PET will become large, resulting in poor melt spinnability.

PET and copolyamides with a high degree of polymerization are used to make high-strength fibers for rubber reinforcement.

PET uses an equal weight mixture of phenol and tetrachloroethane as a solvent, with a concentration of 0.5 g/c&, and a relative viscosity of 1.5 or more when measured at a temperature of 20°C. Polyamide uses 96% sulfuric acid as a solvent, and a concentration of 1. ．． Those having a relative viscosity of 2.0 or more as measured in Og/J at a temperature of 25° C. are preferably used.

In the composite fiber of the present invention, the ratio of the core component to the sheath component is a weight ratio of 50/50 to 90/10, preferably 70
The weight ratio is between /30 and 80/20. If the proportion of the core component is less than this, the characteristics of PET will not be fully utilized.

On the other hand, if the proportion of the core component is higher than this, the properties of the polyamide cannot be fully utilized, and a portion of the core component tends to be exposed on the fiber surface, resulting in a fiber with poor adhesion to rubber, which is not preferable.

The conjugate fiber of the present invention can be produced by subjecting the above-mentioned core component and sheath component to conjugate spinning and drawing in a conventional manner. Stretching may be carried out after the undrawn yarn is wound once, or may be carried out continuously after spinning. In order to produce the fiber of the present invention with good productivity, a method is preferably employed in which highly oriented undrawn yarn is obtained by a direct spinning drawing method or a high speed spinning method and then drawn.

The physical properties of the composite fiber of the present invention vary depending on the composite ratio and spinning conditions, but the single strength is 5 g/d or more, preferably 6 g/d.
It is desirable to have C1 or more, elongation of 10 to 30%, and modulus of 80 g/d or more, preferably 90 g/d or more.

(Example) The present invention will be explained in more detail below using examples.

Note that 9 strength and modulus are based on JIS L 251.
1, using Autograph DSS-500 manufactured by Takasugi Seisakusho.

The measurement was performed under the conditions of a sample length of 30 cm and a tensile speed of 30 cm/min.

Example 1 Aromatic amide units (1,4-phenylene terephthalamide units) were prepared from nylon 66 salt and 1,4-phenylene diamine/terephthalic acid by a method according to Example 1 of Japanese Patent Publication No. 63-66851. ) and a relative viscosity of 2.4 was obtained.

This copolyamide is used as a sheath component, and P with a relative viscosity of 1.60
Using ET as a core component, concentric core-sheath composite fibers shown in Table 1 were produced in the following manner.

The spinning temperature was 305°C, and 3 spinning holes with a diameter of 0.3 mm were formed.
After spinning using six spinnerets, cooling and solidifying, and oiling, the material is taken up by a take-up roller at a speed of 500 m/min, and superheated steam at 450°C is blown between the take-up roller and a stretching roller at a temperature of 150°C. It was stretched at a stretching ratio of 5.0 and wound up at a speed of 2.500 m/min.

Next, this drawn yarn was reheat-stretched at a draw ratio of 1.13 between a supply roller at a temperature of 100°C and a stretching roller at a temperature of 180°C while contacting a hot plate at a temperature of 200°C, and was relaxed by 4% and wound. A composite yarn of 250d/36f was obtained.

Table 1 shows the strength, modulus, operability during spinning, etc. of the obtained composite yarn.

No. table Nos. 2.3 and 4 are examples, and the others are comparative examples.

In fibers No. 5, part of the core component was exposed on the fiber surface.

In addition, the above composite yarn was made into a dip cord in the following manner, and the twisting workability during production of the raw cord, the strength of the dip cord, the strength retention rate of the dip cord to the raw yarn, and the adhesive force with rubber were measured.

Four of the above composite yarns were combined to make a raw yarn of 1000d/144f, and twisted 49 times/10c in the Z direction using a ring twister.
First twist of m, double the two yarns and 49 times/10c in the S direction
A raw cord was made by applying m0 ply twist.

Next, using a Ritzler dipping machine, 3.5 to 4.0% of RFL liquid with a solid content of 15% was deposited, and the drying zone was 120°C for 120 seconds, and the heat treatment zone was 230°C.
It was processed for 36 seconds and normal zone at 230° C. for 36 seconds to form a dip cord.

The adhesive strength with rubber is based on JIS L 1017.

The dip cord is embedded in rubber and the temperature is 155℃.

The cord was vulcanized for 30 minutes at a pressure of 100 kg/cnf, and the force required to pull the cord out of the rubber was measured.

The results are shown in Table 2.

Table 2 Example 2 Aromatic amide units in the amounts shown in Table 3 were prepared from nylon 66 salt and 1,4-phenylenediamine/terephthalic acid by a method according to Example 1 of Japanese Patent Publication No. 63-66851. A copolyamide containing was obtained.

Using this copolyamide as a sheath component and PET as a core component, a composite yarn having a core/sheath weight ratio of 80/20 was produced in the same manner as in Example 1.

The strength, modulus, etc. of the obtained composite yarn are shown in Table 3.

In addition, in No. 9, there was a large difference in the melting points of both polymers, so yarn breakage occurred frequently during spinning.

A dip cord was made in the same manner as in Example 1.

The adhesive strength with rubber was measured. The results are also shown in Table 3.

Table 3 (Effects of the Invention) According to the present invention, it is possible to produce a high modulus composite fiber for rubber reinforcement that takes advantage of the characteristics of polyamide and polyester.

Claims (1)

[Claims] (1) Composite fiber whose core component is polyethylene terephthalate, whose sheath component is a copolyamide based on nylon 66 and containing 1 to 20 mol% of aromatic amide units represented by the following general formula; Weight ratio of sheath part is 50/5
Composite fiber for rubber reinforcement, characterized in that it has a ratio of 0 to 90/10. -HN-X-NH-OC-Y-CO- [In the formula, X and Y are 1,4-phenylene group, 2,6
-naphthylene group, 4,4'-biphenylene group or -φ-
Z-φ- [φ is 1,4-phenylene group, Z is -O-, -
S-, -SO_2-, -CO-, -NH-, -CH_2
- or -C(CH_3)_2-]. ]