JPH07292522A - Production of polyester fiber - Google Patents

Abstract

PURPOSE:To perform the manufacturing of polyester fibers having a combination of excellent dimensional stability and high heat resistance desired for industrial materials, particularly suitable for rubber-reinforcing purposes stably in an industrial scale in high productivity. CONSTITUTION:Polyethylene terephthalate of 0.8-1.1 intrinsic viscosity or a polyester mainly comprising the same is combined with 0.05 to 0.5wt.% of a diaryl terephthalate and melt-extruded into fibers, taken up at a speed of 1,700 to 3,500m/min, then subjected to heat-drawing so that the elongation of the drawn yarn attains 10 to 20% at break.

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). 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 performed in the spinning draft zone (Japanese Patent Laid-Open No. 60-259620, Japanese Patent Publication No. 3-21647). Etc.). 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 are inferior in strength to conventional fibers for industrial materials, and have a low degree of orientation. Since the amorphous part is easily deteriorated in rubber, it has a major drawback that the heat resistance does not reach a level satisfying 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 new stretching method such as a plasma stretching method (Japanese Patent Laid-Open No. 3-137219) or a drawing method in a discharge part (Japanese Patent Laid-Open No. 5-148712) has been proposed, but these require large-scale equipment. However, it is not suitable for industrial scale production because it is 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 yet been achieved.

[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 problems, and the gist thereof is to add 0.05 to 0.5 weight of diaryl terephthalate to polyethylene terephthalate having an intrinsic viscosity of 0.8 to 1.1 or a polyester mainly composed of polyethylene terephthalate. % And melt-spun, the spun yarn is drawn at a take-up speed of 1700 to 3500 m / min, and continuously drawn, and hot drawn so that the cutting elongation of the drawn yarn is 10 to 20%. It is a feature of the polyester fiber manufacturing method.

The present invention will be described in detail below. The polyester in the present invention is substantially composed of polyethylene terephthalate (PET), and may contain a copolymerization component in a range that does not impair the original properties of PET, such as a heat-resistant agent, a flame retardant, and a matting agent. The additive may be included. And, as the polyester to be used for spinning, the intrinsic viscosity (measured at 20 ° C. using an equal weight mixed solvent of phenol and tetrachloroethane) is 0.8 to 1.1.
It is necessary to use the one in the range of. If the intrinsic viscosity is lower than this range, the strength and heat resistance of the fiber will be poor. On the other hand, if the intrinsic viscosity is higher than this range, the spinning stress will be high and it will be difficult to control the oriented crystallization, which is not preferable.

A feature of the present invention is that melt-spinning is performed by adding diaryl terephthalate to PET. Diaryl terephthalate is compatible with PET, has excellent dispersibility in fibers, promotes the flow of molecular chains, enables low-tension yarn production, and causes thermal degradation due to non-uniform orientation of the amorphous part. And suppresses an increase in shrinkage. Further, since this compound induces appropriate crystallization, it does not hinder the crystal structure of PET, and if added in a small amount, it does not affect the strength or the degree of polymerization. Furthermore, the addition of diaryl terephthalate improves the drawability, can sufficiently cope with the high speed drawing such as the spin draw method, and improves the productivity.

The diaryl terephthalate in the present invention preferably has an aryl group having 14 or less carbon atoms, and may have an alkyl group, a valogen atom or the like as a substituent. Specific examples of the aryl group of diaryl terephthalate include phenyl group, o-, p- or m-tolyl group, o-chlorophenyl group, α- or β-naphthyl group, o- or p-phenylphenyl group, 2,4 -Diethylphenyl group, 2-methyl-4-chlorophenyl group and the like. (The two aryl groups may be the same or different.)

The amount of diaryl terephthalate added is required to be 0.05 to 0.5% 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 decreases. This is not preferable because it affects the strength and elongation characteristics.

In the present invention, first, PET to which diaryl terephthalate has been added is melt-spun at a spinning temperature of 290 to 310 ° C., and a spun yarn is arranged in a heating cylinder or the like, and the range of 5 to 20 cm below the spinneret. It is preferable to cool after passing through a region where the ambient temperature is 250 to 350 ° C. When the spinning temperature and the ambient temperature are lower than this range, the initial stress is high,
High-speed collection becomes difficult, and if it is higher than this range,
Subsequent cooling is incomplete. Cooling is preferably performed by a method of blowing 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 1700-3500 m / min. If the take-up speed is lower than this range, the spinning stress will be low and the oriented crystallinity will be low, resulting in poor dimensional stability. If it is higher than this range, the maximum draw ratio will be low and the heat resistance will be poor.

The taken-up yarn is heat-drawn by a spin draw method in which the yarn is continuously drawn. The hot stretching is preferably performed in multiple stages of two or more stages, and heating can be performed by an appropriate heating means such as a heating roller, heating steam, a heat plate, and a heat box. Stretching has a cutting elongation of the drawn yarn.
It is necessary to carry out so as to be 10 to 20%. In order to achieve a cutting elongation of less than 10%, the draw ratio must be close to the cut draw ratio, so that the drawability is poor and the dry heat shrinkage ratio when the dip cord is used is high. On the other hand, when the breaking elongation exceeds 20%, the stretching is insufficient and the strength is low, and at the same time, the high elongation affects the heat resistance in the rubber. Cutting elongation of drawn yarn is 10 ~ 20
In order to achieve the value of 0.1%, the stretching ratio may be appropriately selected and the stretching may be performed. Usually, the stretching ratio is set in the range of 3.5 to 1.7 according to the take-up speed.

According to the method of the present invention, the strength is 7.0 g / d.
Above, polyester fibers with a dry heat shrinkage ratio of 180% or less at 180 ° C can be manufactured, and 177 ° C when the dip cord is used.
The dry heat shrinkage at 1.5% or less and the tenacity retention after holding at 160 ° C in rubber for 3 hours can be 70% or more.

[0017]

EXAMPLES The present invention will be specifically described below with reference to examples. The measuring method of the characteristic value 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 and evaluated.

Example 1 To a PET chip having an intrinsic viscosity of 1.0, diphenyl terephthalate (DPT) was added at the addition amount shown in Table 1, and the mixture was supplied to an escutruder type melt spinning machine,
Using a spinneret with 500 spinning holes with a diameter of 0.5 mm,
Spinning at a spinning temperature of 305 ° C and a length of 13c placed directly under the spinneret
After passing through a heating cylinder having a temperature of 325 ° C. and a temperature of 325 ° C., a cooling air having a wind speed of 60 m / min and a temperature of 18 ° C. was blown onto the yarn from a cylindrical cooling device having a length of 30 cm to cool the yarn. The cooled yarn was taken up by a heating take-up roller of 70 ° C at a take-up speed shown in Table 1, and drawn 1.5 times between the taking-up roller and the first drawing roller of 140 ° C.
Then, stretching was performed between the first stretching roller and the second stretching roller at 200 ° C. so that the total stretching ratio shown in Table 1 was obtained,
A relaxation heat treatment of 0.97 times was performed between the roller and the heat treatment roller at 230 ° C., and then wound up to obtain 1500 d / 500 f polyester fiber. The results of measuring the physical properties of the obtained fibers are shown in Table 1. No. 1 and 2 are examples of the present invention,
No. 3 to 8 are comparative examples.

[0019]

[Table 1]

Next, the No. 1 to 8 raw yarns are twisted 39 times / 10 cm in the Z direction by a ring twisting machine, and two twisted yarns are combined and twisted in the S direction 39 times. / 10 cm top twist was applied to make a raw cord. Using a dipping machine manufactured by Ritzler, an RFL liquid having a solid content of 15% by weight was added to the raw cord to 3.5
Approximately 4.0% by weight was adhered, and treated under the conditions of a drying zone of 160 ° C x 60 seconds and a heat treatment zone of 240 ° C x 50 seconds x 2 times to obtain a dip code. Table 2 shows the results of measuring the strength of the dip cord, the tenacity retention ratio (relative to the tenacity of the raw yarn), the dry heat shrinkage ratio, and the heat resistance in rubber.

[0021]

[Table 2]

In Nos. 1 and 2 which are the embodiments of the present invention,
The dry heat shrinkage of the dip cords was 1.5% or less, and the heat resistance in the rubber was 70% or more. On the other hand, in Comparative Example No. 3, since the amount of diphenyl terephthalate added was large, the viscosity was lowered, the spinning condition was also poor, and the strength and heat resistance of the cord were unsatisfactory. In addition, in No. 4, since diphenyl terephthalate was not added, both heat resistance and dry heat shrinkage were inferior. Furthermore, N
In o. 5, the take-up speed is low, so the draw ratio must be high, and the dry heat shrinkage rate is high. In No. 6, the take-up speed is high, so the draw ratio must be low, and the strength and heat resistance are high. The sex was low. Further, in No. 7, the stretching was insufficient (the cutting elongation was large), and the strength and heat resistance in rubber were poor,
In No. 8, the stretchability was poor due to overstretching (the cutting elongation was small), and the dry heat shrinkage with the dip cord was high.

[0023]

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

Claims (1)

[Claims] 1. A polyethylene terephthalate having an intrinsic viscosity of 0.8 to 1.1, or a polyester mainly composed of polyethylene terephthalate, is added with 0.05 to 0.5% by weight of diaryl terephthalate and melt-spun, and a spun yarn is produced at 1700 to 3500 m / min. Taken at the take-up speed, continuous to the spinning, the cutting elongation of the drawn yarn is 10
A method for producing a polyester fiber, which comprises heat-drawing so that the content is about 20%.