JPH0465524A - Conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain the title conjugate fiber for rubber reinforcement improved in spinnability etc. by providing at a specific ratio the sheath component consisting of a polyamide and the core component consisting of a composition comprising an epoxy-modified polystyrene-based graft copolymer and a blend of polyester and polyamide. CONSTITUTION:The objective fiber pref. with a tenacity of >= 6 g/d, breaking elongation of 10-30% ad modulus of >= 70 g/d, can be obtained by providing (A) as the core component, a composition comprising (1) a blend of (a) a polyester (pref. polythylene terephthalate and (b) a polyamide (e.g. a copolymer from nylon 6 as the chief component and e.g. terephthalic acid, 200 - 330 in melting point) at the weight ratio (1)/(2) = (90:10) - (70:30) [pref. (85:15) - (75:25)] and (2) 2 - 8 (pref. 3 - 6) wt.% of an apoxy-modified polystyrene-based graft copolymer and (B) as the sheath component, polyamide at the weight ratio A/B = (40:60) - (90:10).

Description

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

(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. be. In other words, polyamide fibers have excellent fatigue resistance and impact resistance.

It has a 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 create composite fibers with polyester as the core component and polyamide as the sheath component (for example,
JP-A-49-85315, JP-A-56-140128, etc.). However, such composite fibers made of components with completely different molecular structures have a problem in that phase separation occurs, causing separation between the two components, resulting in fluff during the twisting process.

In order to solve this problem of peeling between 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.

The problem of peeling cannot be satisfactorily solved simply by using such a polyamide, and since it is not a general-purpose polymer, it has the problem of high cost.

Also, JP-A-2-74810 and JP-A-2-7461
Publication No. 1 proposes a composite fiber having polyester as a core component and polyamide as a sheath component, in which polyamide is mixed with polyester as the core component, or polyester is mixed with polyamide as the sheath component. However, the former has the problem of poor spinnability due to the mixing of incompatible polyamides, while the latter, like the former, has poor spinnability and is resistant due to the presence of polyester in the sheath component. There was a problem that hydrolyzability, amine decomposition resistance, and adhesion to rubber became poor.

(Problems to be Solved by the Invention) The present invention eliminates the problem of peeling of one component in a composite fiber made of polyester and polyamide.

In addition, the present invention aims to provide a composite fiber that takes advantage of the features of polyester and polyamide, which can be manufactured with good operability.

(Means for solving problems) The present invention solves the above problems.

The gist is that the weight ratio of polyester and polyamide is 90
A composite fiber whose core component is a composition in which 2 to 8% by weight of an epoxy-modified polystyrene graft copolymer is added to a 10 to 70/30 mixture, and a sheath component of polyamide. The weight ratio is 40/60 to 90/
The composite fiber has a rating of 10.

The present invention will be explained in detail below.

First, according to the present invention, the polyester is polyethylene terephthalate (including what is essentially recognized as polyethylene terephthalate, and other components may be copolymerized or mixed in an amount of up to about 10 mol%). is used.

In addition, polyamides include nylon 6 and nylon 46.
．． Aliphatic polyamides such as nylon 66 and copolymerized products containing these as main components and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid and/or aromatic diamine components such as p-phenylenediamine and m-phenylenediamine, or A mixture of aromatic polyamide such as polymethaxylylene adipamide is used, and it has a melting point of 200 to 33, which can be melt-spun with polyester.
Any temperature of about 0°C is sufficient.

Polyester and polyamide with a high degree of polymerization are used to make high-strength composite fibers for rubber reinforcement.
The polyester was prepared using an equal weight mixture of phenol and tetrachloroethane as a solvent, at a concentration of 0.5 g/di, and at a temperature of 20
Polyamides with a relative viscosity of 1.5 or more measured at °C, using 96% sulfuric acid as a solvent, at a concentration of lOg/d1. temperature 25
Those having a relative viscosity of 2.2 or more as measured at °C are preferably used.

The most important point of the present invention is that a composition in which an epoxy-modified polystyrene-based graft copolymer is added to a mixture of polyester and polyamide is used as the core component.

The weight ratio of polyester to polyamide in the core component is 90/10 to 70/30. Preferably 85/15
~75/20. If the proportion of polyester is small, the high modulus property of polyester will be lost.

High strength fibers cannot be obtained and, in extreme cases, the spun yarn breaks. On the other hand, if the proportion of polyamide is small, the effect of preventing peeling between the core component and the sheath component is poor.

Furthermore, as the epoxy-modified polystyrene-based graft copolymer to be added to the core component, a graft copolymer having an epoxy-modified polystyrene as a trunk and polystyrene or polymethyl methacrylate as branches is preferably used. The amount of the epoxy-modified polystyrene graft copolymer added is suitably 2 to 8% by weight, preferably 3 to 6% by weight of the core component. If the amount added is less than 2% by weight, the effect of improving the compatibility between polyester and polyamide will be poor, and if it exceeds 8% by weight, the viscosity of the polymer will decrease significantly and yarn breakage will occur frequently during spinning.

In the composite fiber of the present invention, the weight ratio of the core component to the sheath component is 40/60 to 90/10. If the proportion of the core component is less than this, the properties of polyester will not be fully utilized, resulting in a fiber with low modulus and poor mechanical properties.On the other hand, if the proportion of the core component is greater than this, the properties of polyamide will not be fully utilized, and the core will not be fully utilized. Some of the components tend to be exposed on the fiber surface, resulting in fibers with poor hydrolyzability and poor adhesion to rubber.

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 performed after the undrawn yarn is once wound up, or may be performed 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.
Above, elongation 10-30%, modulus 60 g/d or above,
Preferably, it is 70 g/d or more.

(Function) In the present invention, since a mixture of polyester and polyamide is used as the core component and polyamide is used as the sheath component, peeling of one stroke component is suppressed.

In addition, by blending the epoxy-modified polystyrene-based graft copolymer into the core component polyester and polyamide mixture, the reactive groups such as epoxy groups of the graft copolymer react with the end groups of the polyester and polyamide, and the polyester and polyamide react with each other. It is recognized that the compatibility with the polyamide is improved by micro-dispersion, and the spinnability is improved.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Strength and elongation and modulus are in accordance with JIS L 2511.

The measurement was carried out using Autograph DSS-500 manufactured by Ryotsu Seisakusho under conditions of a sample length of 30 cm and a tensile speed of 30 cm/min.

Example 1 Polyethylene terephthalate (PB) with a relative viscosity of 1.60
T), a copolymer of nylon 6 (N6) with a relative viscosity of 2.50 and polystyrene grafted to epoxy-modified polystyrene: Reseda GP-500 manufactured by Toagosei Chemical Industry Co., Ltd.
A concentric core-sheath composite fiber having the composition shown in Table 1 was produced using the following method.

The spinning temperature was set to 300°C, and the material was spun using a spinneret having 36 spinning holes with a diameter of 0.3 InI11, and solidified by cooling.

After oiling, it is taken up by a take-up roller at a speed of 500 m/min, and the stretching ratio is 5.
0 and wound up at a speed of 2500 m/min.

Next, this drawn yarn was reheat-stretched at a draw ratio of 1.13 while contacting a hot plate at 200°C between a supply roller at 100°C and a stretching roller at 180°C.

The yarn was relaxed by 4% and wound to obtain a composite yarn of 250 d/36 f.

Table 1 shows the strength and elongation, modulus, and operability during spinning of the composite system obtained.

Table 1 Nα2. 5. 6. Examples 7 and 9 are examples, and the others are comparative examples, and in the fiber of Nα8, the core component was partially exposed on the fiber surface.

Also, regarding the composite yarns obtained with the above Nα4 to Nα9.

A dip cord was formed in the following manner, and the strength of the dip cord, such as the operability of twisting during the preparation of the raw cord, the strength retention of the dip cord to the raw yarn, and the adhesive force with rubber were measured.

Combine 4 of the above composite yarns to make 1000 cl/14
The raw yarn is 4 f, and is twisted 49 times in the Z direction by a ring twister.
First twist 10cm, then second
The yarn was doubled and twisted 49 times/10 cm in the S direction to obtain a raw cord.

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 200tx.
It was processed for 36 seconds in a normal zone at 200° 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/cut, and the force required to pull the cord out of the rubber was measured.

The results are shown in Table 2.

Example 2 In Nα6 of Example 1, N6 was replaced with nylon 66.6P-500 with a relative viscosity of 2.60, and epoxy-modified polystyrene was grafted with polymethyl methacrylate. Zeda GP
-300 was used to produce a composite yarn.

The obtained composite yarn has a strength of 7.6 g/d and an elongation of 16.2%.
, the modulus was 74 g/d, and no fuzz was observed during spinning.

A dip cord was prepared in the same manner as in Example 1, except that the temperature of the heat treatment zone and normal zone during dip treatment was 230°C, and the adhesive strength with rubber was measured.
It was 16.3 kg/crn.

(Effects of the Invention) According to the present invention, there is provided a composite fiber that takes advantage of the properties of polyamide and polyester, is free from peeling problems, and can be manufactured with good operability.

Claims (1)

[Claims] (1) Weight ratio of polyester and polyamide 90/10
A composite fiber whose core component is a composition obtained by adding 2 to 8% by weight of an epoxy-modified polystyrene-based graft copolymer to a 70/30 mixture, and whose sheath component is polyamide, the weight of the core component and sheath component. A composite fiber having a ratio of 40/60 to 90/10.