JPH0571016A - High-strength conjugate fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber free from separation of the core component and the sheath component, excellent in high-temperature durability and suitably for reinforcement of rubber by using polyethylene terephthalate and a polyamide mixture having a specified composition respectively as the core component and the sheath component. CONSTITUTION:An objective fiber obtained by using (A) polyethylene terephthalate as the core component and (B) a mixture composed of nylon 46 and nylon 66 in a weight ratio of (90/10)-(60/40) as the sheath component and controlling the weight ratio of the core part to the sheath part to (50/50)-(80/20). The above-mentioned fiber is produced by using a conventional extruder-type conjugate spinning machine, carrying out conjugate melt spinning according to the conventional method and subsequently stretching the spun yarn. In addition, the melt temperature and the residence time are respectively controlled preferably to 290-315 deg.C and 5-12min so that nylon 46 may suitably be reacted with nylon 66. In order to obtain a high-strength fiber, draw out at 500-1500m/min and stretching at >=4.5 time draw ratio are recommendable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high strength composite fiber composed of polyester and polyamide suitable for rubber reinforcement.

[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, but these fibers have advantages and disadvantages. There is. That is, although polyamide fibers have excellent fatigue resistance and impact resistance, they have the drawbacks of high shrinkage, easy occurrence of flat spots, high water absorption, and low modulus. On the other hand, polyester fiber does not have the problem of flat spots and has a high modulus, but it is easily hydrolyzed in rubber, and
It has the drawback 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). No.). But,
Such a composite fiber has a problem that phase separation occurs, separation occurs between both components, and fluff is generated in the drawing process and the twisting process.

In order to improve the durability at high temperature, Japanese Patent Laid-Open No. 1-239112 discloses nylon 4 as a sheath component.
A composite fiber using 6 has been proposed. However, this fiber has a drawback that the crystallization rate of nylon 46 is high and it is difficult to control the crystallization during spinning, so that the fiber does not match the drawability with the polyester of the core component and cannot be drawn at a high draw ratio. It has been difficult to obtain high strength fibers.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a composite fiber containing a polyester as a core component and a polyamide as a sheath component, which has no problem of peeling between the two components and is excellent in durability at high temperature. It is intended to provide a strong composite fiber.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems by using polyethylene terephthalate as a core component and a weight ratio of nylon 46 to nylon 66 of 90/10 to.
A high-strength composite fiber, which is a composite fiber obtained by melt-spinning a mixture of 60/40 as a sheath component and has a weight ratio of a core portion and a sheath portion of 50/50 to 80/20.

The present invention will be described in detail below. First, in the present invention, polyethylene terephthalate (including those substantially recognized as polyethylene terephthalate) is used as the core component polyester.

As the sheath component, nylon 46 (polytetramethylene adipamide) (substantially nylon 46
Including those recognized as ) And nylon 66 (polyhexamethylene adipamide) (including those substantially recognized as nylon 66) are used.
When nylon 46 and polyethylene terephthalate are used as the composite fiber, there is a problem that the stretchability does not match with polyethylene terephthalate due to the high crystallization of nylon 46 as described above, and it is not possible to stretch at a high ratio. By mixing nylon 66 and melt-spinning, crystallization is appropriately suppressed, and it becomes possible to perform high-magnification stretching like polyethylene terephthalate. (This is nylon 46 and nylon 6 during melt spinning.
It is recognized that 6 reacts with 6 to partially form a copolymer. )

When a mixture of nylon 46 and nylon 66 is melt-spun, it hardly loses the impact resistance and the adhesiveness which are the original properties of polyamide, and the crystallization is suppressed but the strength is somewhat affected. Because it can be stretched at a magnification,
Rather, the composite fiber can have a higher strength.

Nylon 46 and nylon 66 are 90 / 10-
Used in a weight ratio of 60/40. When the proportion of nylon 66 is less than this range, the effect of suppressing crystallization is small, the drawability is poor, and peeling easily occurs, so that the operability is deteriorated and the yarn strength is reduced, which is not preferable. On the other hand, if the proportion of nylon 46 is less than this range, the original strength of nylon 46 and the durability at high temperature are lost, which is not preferable.

Polyethylene terephthalate, nylon 4
Since 6 and nylon 66 are high strength fibers, those having a high degree of polymerization are used, and polyethylene terephthalate is used as a solvent in an equal weight mixture of phenol and ethane tetrachloride at a concentration of 0.5 g / dl and a temperature of 20 ° C. The measured relative viscosity is 1.5
The above materials, nylon 46 and nylon 66, are preferably used with 96% sulfuric acid as a solvent and having a relative viscosity of 2.5 or more measured at a concentration of 1.0 g / dl and a temperature of 25 ° C.

In the conjugate fiber of the present invention, the weight ratio of the core portion to the sheath portion must be 50/50 to 80/20. If the proportion of the core component is less than this, the properties of polyethylene terephthalate are not fully utilized, and only fibers with low mechanical properties with low modulus can be obtained. Conversely, if the proportion of the core component is higher than this, the properties of polyamide are It is not preferable because the core component is not fully utilized and a part of the core component is easily exposed on the fiber surface, resulting in a fiber having poor adhesion with rubber.

The composite fiber of the present invention is subjected to composite melt spinning by a conventional method using a usual extruder type composite spinning machine,
It is manufactured by stretching. Melt spinning is usually carried out using an extruder type composite spinning machine, and nylon 46 and nylon 66 are melt-mixed in the extruder. In order to allow nylon 46 and nylon 66 to react appropriately, it is preferable that the melting temperature is 290 to 315 ° C. and the residence time is about 5 to 12.

The stretching may be carried out after once winding the undrawn yarn, or may be carried out continuously to the spinning. The conventional polyester and polyamide composite fibers, when drawn at a high speed such as a one-step method in which continuous drawing is performed during spinning, breakage of a single yarn is likely to occur, and the drawability is higher than that in the two-step method. Although it was poor, in the present invention, since the stretchability is good as described above, it is possible to perform stretching without a problem even in the one-step method,
It is also a great advantage in productivity.

The spinning speed and draw ratio in the production of the conjugate fiber of the present invention differ depending on the intrinsic viscosity of the polymer, etc., but in order to obtain a high strength fiber, the fiber is drawn at a take-up speed of 500 to 1500 m / min and 4.5 times. It is desirable to stretch at the above stretching ratio.

The physical properties of the composite fiber of the present invention vary depending on the composite ratio and manufacturing conditions, but the strength is 7 g / d or more, preferably 8.
It is preferable 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]

EXAMPLES The present invention will be specifically described below with reference to examples. For the strength and elongation and initial modulus, use Autograph DSS-500 manufactured by Shimadzu Corporation, using a sample length of 30 cm and a tensile speed of 30.
It was measured under the condition of cm / min.

Example 1 Polyethylene terephthalate (PE having a relative viscosity of 1.60)
T), nylon 46 (N46) having a relative viscosity of 3.30 and nylon 66 (N66) having a relative viscosity of 3.10 are used, the core component is PET, and the sheath component is a mixture of N46 and N66 in a weight ratio shown in Table 1, A concentric core / sheath composite yarn having a weight ratio of the sheath and the sheath of 60/40 was manufactured as follows. Using an extruder type composite spinning machine, spinning temperature is 300 ° C and residence time is
The spinning time was 6.1 to 7.7 minutes, and spinning was performed using a spinneret having 36 spinning holes with a diameter of 0.5 mm, and after cooling and solidification, it was drawn by a take-up roller at a speed of 1000 m / min. ℃ 3rd roller, 180 ℃ 4th roller and 160
Multi-stage stretching was performed at a total stretching ratio shown in Table 1 by a fifth roller at a temperature of ° C. At that time, heated steam of 450 ° C. was blown to the yarn 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 cutting occurred. Table 1 shows the strength, elongation and initial modulus of the obtained composite yarn.

[0019]

[Table 1]

In Nos. 2 to 4 in which N66 was mixed in the sheath component, the stretching ratio was remarkably increased as compared with No. 1 in which only N46 was mixed, and the larger the mixing ratio of N66, the larger the stretching ratio. In No. 1, fluff was generated during stretching, but in Nos. 2 to 4, the stretchability was good. No. of the invention example
In Nos. 2 and 3, the increase in draw ratio contributed to the strength, and high-strength composite fibers were obtained. On the other hand, in No. 4 in which the mixing ratio of N66 is larger than the range of the present invention, only the same strength as No. 1 was obtained.

Example 2 A concentric conjugate fiber was produced in the same manner as in Example 1 in which the weight ratio of N46 and N66 of the sheath component was 85/15 and the weight ratio of the core to the sheath was as shown in Table 2. .. The strength of the obtained composite yarn,
The elongation and the initial modulus are shown in Table 2.

[0022]

[Table 2]

In Nos. 6 and 7 of the examples of the present invention, the composite fibers having high strength and high elastic modulus were obtained, and the drawing operability was good. On the other hand, the ratio of the core component is less than the range of the present invention No.
In No. 5, only a fiber having a low modulus was obtained, and in No. 8 in which the ratio of the sheath component was less than the range of the present invention, fluff was likely to occur during stretching, and the core component was partially exposed on the fiber surface. Further, the composite yarns obtained in Nos. 6 to 8 were dip-coded as follows, and the dip cord strength, the strength retention ratio of the dip cord to the original yarn, the heat-resistant strength retention ratio after vulcanization, and the rubber were used. Was measured. The above-mentioned four composite yarns are combined into a 1000d / 144f original yarn,
Using a ring twister, ply 49 times / 10 cm in the Z direction,
The two cords were combined and twisted 49 times / 10 cm in the S direction to obtain a raw cord. Then, using a dipping machine manufactured by Ritzler Co., 3.5 to 4.0% of RFL liquid having a solid content of 15% is deposited,
Drying zone 120 ℃ × 120 seconds, heat treatment zone 200 ℃ × 36 seconds,
A normal zone was treated at 200 ° C for 36 seconds to obtain a dip code. Heat-resistant strength retention rate and adhesive strength with rubber are
According to JIS L 1017, the dip cord was embedded in rubber and vulcanized at a temperature of 155 ° C. and a pressure of 100 kg / cm ² for 30 minutes, and the strength of the cord taken out and the force required to pull the cord out of the rubber were measured. The results are shown in Table 3.

[0024]

[Table 3]

In Nos. 6 and 7 of the examples of the present invention, the strength retention of the dip cord, the heat-resistant strength retention after vulcanization, and the adhesive strength were good. On the other hand, in Comparative Example No. 8, the strength reduction during twisting and dipping was remarkable, and the heat resistance strength and adhesive strength were also low.

[0026]

EFFECTS OF THE INVENTION According to the present invention, in a composite fiber containing polyester as a core component and polyamide as a sheath component, there is no problem of peeling between the two components, and the characteristics of polyamide and polyester are utilized at high temperature. Provided is a high-strength composite fiber which is excellent in durability against time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaru Sugawa 23 Kouji Sakura, Uji City, Kyoto Prefecture Unitika Ltd. Central Research Institute

Claims (1)

[Claims] 1. A polyethylene terephthalate core component,
Nylon 46 and nylon 66 weight ratio 90 / 10-60 / 40
Which is a composite fiber obtained by melt-spinning the mixture as a sheath component, wherein the weight ratio of the core portion to the sheath portion is 50/50 to 80/20.