JP2971211B2 - High strength 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 high-strength conjugate fiber composed of polyester and polyamide suitable for reinforcing rubber.

[0002]

2. Description of the Related Art Fibers made of polyamides such as nylon 6 and nylon 66 and polyesters such as polyethylene terephthalate are widely used as rubber reinforcing fibers such as tire cords. There is. That is, polyamide fibers are excellent in fatigue resistance and impact resistance, but have the disadvantages of high shrinkage, easy generation of flat spots, high water absorption, and low modulus. On the other hand, polyester fiber has no problem of flat spot generation and high modulus, but is easily hydrolyzed in rubber,
It has the disadvantage of poor adhesion to rubber.

In order to take advantage of the advantages of polyamide and polyester, it has been proposed to use a composite fiber having polyester as a core component and polyamide as a sheath component. (For example, JP-A-49-85315 and JP-A-56-140128) However, such a conjugate fiber has a problem that phase separation occurs, separation occurs between both components, and fluff is generated in a twisting process. Was.

To solve the problem of peeling between the two components, Japanese Patent Application Laid-Open No. 1-97211 discloses a conjugate fiber using nylon 66 / 6T obtained by copolymerizing nylon 66 with a terephthalic acid component as a polyamide. Proposed.
Japanese Patent Application Laid-Open Nos. 1-97212 and 2-74612 propose conjugate fibers having a high orientation and a high crystal structure by a high-speed spinning method. However, all of these have the drawback that, since the polyamide is highly crystallized, the stretchability does not match with that of the polyester at the core, and high draw ratio cannot be performed. Has not become.

[0005]

SUMMARY OF THE INVENTION The present invention aims to provide a conjugate fiber having a polyester as a core component and a polyamide as a sheath component, which has no problem of peeling of both components and has a high strength. Is what you do.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises polyethylene terephthalate as a core component, and a weight ratio of polyhexamethylene adipamide to polytetramethylene adipamide of 95/5 to 5/5. The gist is a composite fiber obtained by melt-spinning a 60/40 mixture as a sheath component, wherein the weight ratio between the core and the sheath is 50/50 to 80/20.

Hereinafter, the present invention will be described in detail. First, in the present invention, polyethylene terephthalate (including a substance substantially recognized as polyethylene terephthalate; hereinafter, referred to as PET) is used as the polyester of the core component.

As the sheath component, a mixture of polyhexamethylene adipamide (hereinafter, referred to as N66) and polytetramethylene adipamide (hereinafter, referred to as N46) is used. When N66 and PET are used as a composite fiber, there is a problem that the stretchability does not match with PET due to the high crystallization of N66 as described above, and there is a problem that the film is peeled off at the core-sheath interface when stretched at a high magnification. By melt-spinning using a mixture of N66 and N46, crystallization is appropriately suppressed, and it becomes possible to perform high-stretching similarly to PET. (This is recognized because N66 and N46 react during melt spinning to partially form a copolymer.)

[0009] The mixture of N66 and N46 hardly loses the impact resistance and adhesiveness which are inherent properties of polyamide, and the strength is somewhat affected by the suppression of crystallization.
Since it can be drawn at a high magnification, it is possible to increase the strength of the composite fiber.

A mixture of N66 and N46 in a weight ratio of 95/5 to 60/40, preferably in a weight ratio of 90/10 to 70/30 is used. If the ratio of N46 is less than this, the effect of suppressing crystallization is small, the stretchability is poor, and the film is easily peeled. On the other hand, if the proportion of N46 is higher than this, the copolymerization effect is too large, and the inherent high strength of N66 is lost, which is not preferable.

For PET, N66 and N46, those having a high degree of polymerization are used in order to obtain high-strength fibers, and PET uses an equal weight mixture of phenol and ethane tetrachloride as a solvent,
Concentration: 0.5 g / dl, relative viscosity measured at a temperature of 20 ° C. of 1.5 or more.
Those having a relative viscosity of 2.5 or more measured at 1.0 g / dl and a temperature of 25 ° C. are preferably used.

In the composite fiber of the present invention, the weight ratio between the core and the sheath needs to be 50/50 to 80/20. If the ratio of the core component is less than this, the properties of PET are not sufficiently utilized, and only fibers with low modulus and low mechanical properties are obtained. Conversely, if the ratio of the core component is higher than this, the properties of the polyamide are sufficient. The fibers are not utilized, and a part of the core component is likely to be exposed on the fiber surface, resulting in fibers having 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 composite melt-spinning according to a conventional method and stretching the resultant. Melt spinning is usually performed using an extruder-type composite spinning machine, and N66 and N46 are used.
Is melt-mixed in an extruder. N66 and N
In order to react moderately with 46, the melting temperature is 290-315 ° C
It is desirable that the residence time be 5 to 12 minutes.

The drawing may be performed after the undrawn yarn is once wound up, or may be performed continuously with the spinning. Conventional polyester and polyamide conjugate fibers, when drawn at a high speed, such as the one-step method of continuous drawing during spinning, tend to cut single yarns and have poor drawability compared to the two-step method. However, in the present invention, since the stretchability is good as described above, the stretch can be performed without any problem even by the one-step method, which is a great advantage in productivity.

The spinning speed and the draw ratio at the time of producing the conjugate fiber of the present invention vary depending on the intrinsic viscosity of the polymer and the like, but in order to obtain a high-strength fiber, it is taken up at a speed of 500 to 1500 m / min and 4.5 times or more. It is desirable to stretch at a magnification of.

The physical properties of the composite fiber of the present invention vary depending on the composite ratio and the production conditions, but the strength is 7 g / d or more, preferably 8.
It is desirable that the elongation is 5 g / d or more, the elongation is 10 to 30%, and the modulus is 70 g / d or more.

[0017]

Next, the present invention will be described in detail with reference to examples. The elongation and modulus were measured using a Shimadzu Autograph DSS-500 with a sample length of 30 cm and a tensile speed of 30 cm /
It was measured under the condition of minutes.

Example 1 Using PET having a relative viscosity of 1.60, N66 having a relative viscosity of 3.10, and N46 having a relative viscosity of 3.30, the core component was PET, and the sheath component was a mixture of N66 and N46 in the weight ratio shown in Table 1. A concentric core / sheath composite fiber having a core / sheath weight ratio of 60/40 was produced as follows. Using an extruder-type composite spinning machine, the spinning temperature is 300 ° C., the residence time is 6.1 to 7.7 minutes, the spinning is performed using a spinneret having 36 spinning holes of 0.5 mm in diameter, and after cooling and solidifying, 1000 m / min. The take-up roller is pulled at a speed of 195 ° C.
, A fourth roller at 180 ° C. and a fifth roller at 160 ° C. performed multi-stage stretching. At that time, heated steam at 450 ° C. was sprayed between the second roller and the third roller, and the total draw ratio was set to 92% of the maximum draw ratio at which yarn breakage occurred. Table 1 shows the draw ratio and the strength, elongation, and initial modulus of the obtained composite yarn.

[0019]

[Table 1]

In Nos. 2 to 4 in which N46 was mixed with the sheath component, the stretching ratio was dramatically increased as compared with No. 1 in which only N66 was used, and the higher the mixing ratio of N46, the higher the stretching ratio. In addition, although fuzzing occurred during stretching in No. 1, stretchability was good in Nos. 2 to 4.

In Nos. 2 and 3 of the present invention, the increase in the draw ratio contributed to the strength, and a high-strength conjugate fiber was obtained.
On the other hand, the mixing ratio of N46 is larger than the range of the present invention.
In No. 4, only the same strength as No. 1 was obtained.

Example 2 A concentric conjugate fiber was prepared in the same manner as in Example 1, wherein the weight ratio of the sheath components N66 and N46 was 85/15 and the weight ratio of the core and the sheath was as shown in Table 2. . Strength of the obtained composite yarn,
Table 2 shows the elongation and the initial modulus.

[0023]

[Table 2]

In Examples 6 and 7 of the present invention, conjugate fibers having high strength and high elastic modulus were obtained, and the drawing operability was good. On the other hand, in the case of No. 5 in which the ratio of the core component is smaller than the range of the present invention, only fibers having a low modulus are obtained, and in the case of No. 8 in which the ratio of the sheath component is smaller than the range of the present invention, fluff is likely to be generated during stretching. The core component was partially exposed on the fiber surface.

The composite yarns obtained in Nos. 6 to 8 were dip-coded as follows, and the strength of the dip cord, the retention of the dip cord to the original yarn, and the adhesion to rubber were measured. . Four of the above composite yarns are plied into a 1000d / 144f raw yarn, and Z is produced by a ring twisting machine.
Twist 49 times / 10cm in the direction and twist the two yarns in the S direction
A raw cord was obtained by twisting the wire 49 times / 10 cm. Then, using a dipping machine manufactured by Ritzler, an RFL solution having a solid content of 15% was adhered to 3.5 to 4.0%, and a drying zone of 120 ° C. × 120
Seconds, heat treatment zone 200 ° C × 36 seconds, normal zone 200 ° C ×
Processing was performed under the conditions of 36 seconds, and a dip code was obtained. In addition, the adhesive strength with rubber was measured at a temperature of 155 ° C and a pressure of 100 kg / cm ² by embedding a dip cord in rubber according to JIS L1017.
After vulcanization for a minute, the force required to pull the cord from the rubber was measured. Table 3 shows the results.

[0026]

[Table 3]

In Examples 6 and 7 of the present invention, both the strength retention and the adhesive strength were good, but in the case of No. 8, the strength was significantly reduced during twisting and dipping, and the adhesive strength was low.

[0028]

According to the present invention, it is possible to obtain a high-strength composite fiber utilizing the characteristics of polyamide and polyester suitable for rubber reinforcement.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-97212 (JP, A) JP-A-3-146715 (JP, A) JP-A-1-239112 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) D01F 8/12-8/14 D02G 3/48

Claims (1)

(57) [Claims] 1. A core component comprising polyethylene terephthalate,
A composite fiber melt-spun using a mixture of polyhexamethylene adipamide and polytetramethylene adipamide in a weight ratio of 95/5 to 60/40 as a sheath component, wherein the weight ratio of the core to the sheath is 50/50. High-strength conjugate fiber of 50-80 / 20.