JPH07252725A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To obtain in high productivity in an industrially stable way polyester fibers suitable for industrial material applications, esp. for rubber reinforcement, having a combination of good dimensional stability and high heat resistance. CONSTITUTION:Polyethylene terephthalate 0.8-1.1 in intrinsic viscosity or a polyester predominant therein is incorporated with 0.05-1.0wt.% silicon tetrafluoride-based mica particles <=5mum in diameter followed by melt spinning into filament yarns, which are then taken up at a speed of 2000-3500m/min followed by orientation by a factor of 1.5-3.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester fiber which is suitable for industrial materials, especially for rubber-reinforcing fiber, and which has excellent dimensional stability against heat and heat resistance.

[0002]

2. Description of the Related Art Polyester fibers represented by polyethylene terephthalate fibers are widely used as fibers for industrial materials, and particularly have excellent performance as fibers for rubber reinforcement. Along with the increasing demand for the fiber, there is a demand for a fiber that simultaneously satisfies the dimensional stability and heat resistance in a high heat environment.

As a method of increasing the dimensional stability, there is known a method in which an undrawn yarn having a high degree of molecular orientation is taken in by increasing the spinning speed and subjected to hot drawing (Japanese Patent Publication No. 63-528).
No. 63-529). Further, in recent years, due to the demand for higher performance, a method has been proposed in which the spinning speed further increases, and oriented crystallization is carried out in a spinning draft zone (Japanese Patent Laid-Open No. 60-259620, Japanese Patent Publication No. 3-259620). No. 21647).
However, the fibers produced by these methods have a low degree of orientation of the amorphous portion of the molecule and are excellent in dimensional stability, but the strength is inferior to the conventional fibers for industrial materials, and the degree of orientation is Since the low amorphous part is easily deteriorated in the rubber, it has a major drawback that the heat resistance does not reach a level satisfactory as a rubber-reinforcing fiber.

As a method of preventing deterioration in rubber, there has been proposed a method of imparting a component for protecting the cord from a deteriorated component at the time of dip treatment after the fiber is coded (Japanese Patent Laid-Open No. 99667/1990). 2-127562, 3-59168, etc.). However, all of these only protect the surface of the fiber, and have not yet improved the internal structure, and a large effect cannot be expected for the fiber obtained by high-speed spinning accompanied by oriented crystallization.

As a method for improving the internal structure of fibers,
A method of adopting a novel stretching method such as a plasma stretching method (Japanese Patent Laid-Open No. 3-137219) and a stretching method in a discharge part (Japanese Patent Laid-Open No. 5-148712) has also been proposed, but these require large-scale equipment. And is not suitable for industrial scale production, such as not suitable for high-speed drawing.

As described above, the development of polyester fibers having both dimensional stability against heat and heat resistance in rubber on an industrial scale has not been achieved yet.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a polyester fiber having good dimensional stability and heat resistance, which is suitable for industrial materials, particularly for rubber reinforcement, and is industrially stable with high productivity. The present invention is intended to provide a method for producing a polyester fiber that can be manufactured.

[0008]

Means for Solving the Problems The present invention is to solve the above-mentioned problems, and its gist is to provide a polyethylene terephthalate having an intrinsic viscosity of 0.8 to 1.1 or a polyester mainly composed of polyethylene terephthalate having a particle size of 5 μm or less. Twenty percent of the melt spun yarn was added with 0.05 to 1.0% by weight of tetrafluorosilicon mica particles.
It is a method for producing a polyester fiber, which is characterized in that it is drawn at a drawing speed of 00 to 3500 m / min, and is continuously drawn to a draw ratio of 1.5 to 3.0 times.

The present invention will be described in detail below. The polyester fiber in the present invention is substantially composed of polyethylene terephthalate (PET), and contains a third component such as a heat-resistant agent, a flame retardant, and a matting agent to the extent that the original properties of polyester are not impaired. Good. The intrinsic viscosity is a value measured at 20 ° C using an equal weight mixed solvent of phenol and tetrachloroethane, and is 0.8 to 1.
Must be in the 1 range. When the intrinsic viscosity is lower than this range, the strength and heat resistance are inferior, and when it is higher than this range, the spinning stress is high and it is difficult to control the oriented crystallization, which is not preferable.

A feature of the present invention is to melt-spin PET in which fluorine tetrasilicon mica particles are added when PET is melted. This additive is extremely stable in a high temperature environment and has excellent heat resistance of itself, and at the same time, when added to PET, it is dispersed in the amorphous part of PET to improve the heat resistance of the entire fiber. It becomes possible.

As the tetrafluorosilicon mica particles, those commercially available from Corp Chemical Co., Ltd. as synthetic mica "ME series" are preferably used.

The particle size of the tetrafluorosilicon mica particles is 5 μm.
It is necessary to make it below, and it is particularly preferable that it is 2 μm or less. Within this range, the dispersibility in PET is excellent,
Since it induces appropriate crystallization, it does not hinder the crystal structure of PET, and addition of a small amount does not cause a decrease in strength or degree of polymerization. If the particle size is larger than this range, the dispersibility in PET is poor, the stress is not evenly applied during spinning due to the extremely existing particles, and the molecular orientation is uneven.
Dimensional stability deteriorates. Further, in extreme cases, stress may be concentrated in the vicinity of the particles, leading to cutting.

The amount of tetrafluorosilicon mica particles added is required to be 0.05 to 1.0% by weight based on the polyester.
If it is less than this range, the effect is small, and if it is more than this range, the degree of polymerization of the polyester is deteriorated and strength properties are affected.

In the present invention, first, PET to which fluorine tetrasilicon mica particles are added is melt-spun at a spinning temperature of 290 to 310 ° C., a spun yarn is arranged in a heating cylinder, etc.
It is preferable to cool after passing through a region where the atmospheric temperature in the range of -15 cm is 250-350 ° C. If the spinning temperature and the ambient temperature are lower than this range, the initial stress is too high, and high-speed take-up becomes difficult, and if the spinning temperature and the ambient temperature are higher than this range, the subsequent cooling is incomplete. As a cooling method, it is desirable to blow cooling air of 10 to 30 ° C. at a wind speed of 40 m / min or more over a length of 20 cm or more.

The take-up speed must be 2000-3500 m / min. If the take-up speed is lower than this range, the spinning stress is low, oriented crystallization does not occur, and the dimensional stability becomes poor. If it is higher than this range, the maximum draw ratio becomes low and the heat resistance becomes poor.

The drawn yarn is heat-drawn by the spin draw method in which the yarn is continuously drawn. In the case of the present invention, it is possible to sufficiently cope with high-speed drawing such as the spin draw method, which is advantageous in terms of productivity. The hot stretching is preferably a multi-stage stretching of two or more stages, and the heating method includes a method using a heating roller, heated steam, a heat plate, a heat box, etc., and is not particularly limited. The total draw ratio must be 1.5 to 3.0 times. If the total draw ratio is lower than this range, the strength and heat resistance will be poor, and if it is higher than this range, good dimensional stability cannot be maintained.

In the present invention, the strength is increased by the above manufacturing method.
A polyester fiber with a dry heat shrinkage of 7.0 g / d or more and a dry heat shrinkage of 4.0% or less at 180 ° C can be produced, and the dry heat shrinkage of 177 ° C at the time of dip cord is 1.5% or less, 160 ° C in rubber.
The tenacity retention after 3 hours can be 70% or more.

[0018]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition, the measuring method of the characteristic value in this invention is as follows. (a) Tensile strength Using Autograph S-100 manufactured by Shimadzu Corporation, sample length 25c
The measurement was performed under the conditions of m and a pulling speed of 30 cm / min. (b) Dry heat shrinkage The raw yarn is heat treated at 180 ° C for 30 minutes under no tension,
The dip code was measured by heat treatment at 177 ° C. with a load of 0.015 g / d. (c) Heat resistance in rubber Dip cord is embedded in rubber, temperature is 160 ℃, pressure
It was vulcanized at 25 kg / cm ² for 3 hours, the strength of the taken out cord was measured, and the strength retention ratio to the strength before embedding was calculated.

Example 1 A PET chip having an intrinsic viscosity of 0.9 has an average particle size of 2 μm.
m Fluorine tetrasilicon mica particles (“M
E-100 ") was added in the amount shown in Table 1, and the mixture was fed to an extruder type melt spinning machine to give a diameter of 0.5.
Spinning temperature 305 ℃ from spinneret with 500 mm spinning holes
After passing through a heating cylinder with a length of 13 cm and a temperature of 325 ° C arranged just below the spinneret, a cooling air with a wind speed of 60 m / min and a temperature of 18 ° C was formed into a thread from a cylindrical cooling device with a length of 30 cm. Spraying and drawing with a heating take-up roller of 70 ° C, stretching 1.5 times between the take-up roller and the first drawing roller of 140 ° C, and then between the first drawing roller and the second drawing roller of 200 ° C. After being stretched at 1, a relaxation heat treatment of 0.97 times was performed between the second stretching roller and the heat treatment roller at 230 ° C., and then wound up to obtain 1500 d / 500 f polyester fiber. At that time, the take-up speed and the total draw ratio between the take-off roller and the second draw roller were set to the values shown in Table 1 to obtain Nos. 1 to 6 fibers. Table 1 shows the measured values of the physical properties of the obtained fiber. Nos. 1 and 2 are examples of the present invention, and Nos. 3 to 6 are comparative examples.

[0020]

[Table 1]

Further, the No. 1 to 6 raw yarns are twisted 39 times in the Z direction by a ring twisting machine / 10 cm, and two twisted yarns are twisted into 39 times in the S direction. A 10 cm twist was made into 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, and a drying zone is 160 ° C for 60 seconds and a heat treatment zone is 240 ° C.
It was processed under the condition of × 50 seconds × 2 times to obtain a dip code.
Table 2 shows the results of measuring the strength of the dip cord, the dry heat shrinkage ratio, and the heat resistance in rubber.

[0022]

[Table 2]

In No. 1 and No. 2 of the present invention, the dry heat shrinkage of the dip cord was 1.5% or less, and the heat resistance in rubber was 70% or more. On the other hand, in No. 3, since the amount of fluorine tetrasilicon mica particles added was large, the spinning condition was poor, the draw ratio was low, and the cord strength, dry heat shrinkage,
The heat resistance was unsatisfactory. In No. 4, the heat resistance is poor and the dry heat shrinkage is high because no fluorine tetrasilicon mica particles are added. In No. 5, the draw ratio is high because the take-up speed is low, and the dry heat shrinkage is high. It was In No. 6, since the take-up speed was high, the draw ratio was low, and the strength and heat resistance were low.

[0024]

INDUSTRIAL APPLICABILITY According to the present invention, industrial material applications, particularly,
A polyester fiber suitable for rubber reinforcement and having both good dimensional stability and heat resistance can be industrially produced stably with high productivity.

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Claims (1)

[Claims] 1. A fluorine tetrasilicon mica particle having a particle size of 5 μm or less is added to polyethylene terephthalate having an intrinsic viscosity of 0.8 to 1.1 or a polyester mainly composed of polyethylene terephthalate.
~ 1.0% by weight, melt spun yarn 2000 ~ 3500m
/ 3 min./min.
A method for producing a polyester fiber, which comprises stretching the fiber 0 times.