JPH0368127B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for producing a high-strength polyester molded product by treating an unstretched molded product made of high molecular weight polyester in a solvent vapor atmosphere and then performing two-stage stretching at a high magnification. BACKGROUND ART Polyester molded products have various excellent properties and are therefore widely used not only for clothing but also for industrial purposes. In particular, high-strength polyester fibers are useful in industrial applications, and are increasingly being used not only for tires but also for various industrial material applications. Polyester can be melt-molded, and the economically advantageous melt-molding method is usually used. In order to develop the high strength required for industrial molded products, high-polymerization degree polyester is used. It is common to melt and mold using a polyester resin, followed by stretching at a high magnification. Problems to be solved by the invention In the conventional methods of melt molding and high-magnification stretching,
There is a limit to the strength of the molded product obtained, and the strength is 10g/
It has been impossible to industrially produce fibers with a strength of 50 Kg/mm ² or higher or films with a strength of 50 Kg/mm 2 or higher. The purpose of the present invention is to break through the wall of strength of molded products in the prior art by combining treatment in a solvent vapor atmosphere of unstretched molded products and high-strength two-stage stretching, and to achieve high strength molding that has never been seen before. The goal is to provide a method for manufacturing things. Means for Solving the Problems The present invention provides an unoriented molded product made of a polyester having an intrinsic viscosity of 0.9 or more in an atmosphere of a solvent vapor having a solubility for the polyester at room temperature to 90%
After processing for 5 to 24 hours at a temperature of ℃, Tg or above Tg+
Production of a high-strength polyester molded product characterized by netting stretching at a temperature of 20°C or lower, followed by second-stage stretching at a temperature higher than the α _c dispersion temperature and lower than the melting point, so that the total stretching ratio is 7 times or higher. It is the law. The polyester targeted in the present invention has an aromatic dicarboxylic acid as a main component and ethylene glycol as a main glycol component. Here, "mainly" means more than 50 mol%. Therefore, less than 50 mol% of other components may be contained. Further, the aromatic dicarboxylic acid refers to a compound in which a carboxylic acid is directly bonded to an aromatic ring, such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, etc., and terephthalic acid is particularly preferred. Furthermore, as the third component that can be copolymerized with the polyester in the present invention, aromatic dicarboxylic acids other than the main constituent components of the polyester, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, decanedicarboxylic acid, etc. Aliphatic dicarboxylic acids; alicyclic dicarboxylic acids such as hexahydroterephthalic acid, decalin dicarboxylic acid, and tetralin dicarboxylic acid;
Glycolic acid, p-oxybenzoic acid; aliphatic diols other than the main constituent components of the polyester such as trimethylene glycol, propylene glycol, 1,4 butanediol, 1,3 butanediol, neopentyl glycol, 1,6 hexanediol;
Examples include alicyclic diols such as cyclohexane dimethylol and tricyclodecane dimethylol; aromatic diols such as bisphenol A, bisphenol S, bishydroxyethoxybisphenol A, and tetrabromobisphenol A. These polyesters may also contain up to 10% by weight of other polymers, as well as stabilizers,
It may contain additives such as colorants. The molded product in the present invention is a general term for fibers, films, and other molded products, and particularly in the case of fibers, remarkable effects can be achieved. The polyester used in the present invention is 0-
Intrinsic viscosity determined from chlorophenol solution is 0.9
It is necessary that it is above. If the intrinsic viscosity is less than 0.9, the desired high-strength polyester molded product cannot be obtained. The intrinsic viscosity is preferably 0.9 to 1.5. High molecular weight polyesters with high intrinsic viscosity can also be obtained by the conventionally well-known solid-phase polymerization method, but in the solution polymerization method, when the intrinsic viscosity reaches 0.8 or more, gaseous polyester is produced under the polymerization conditions. It is efficiently produced by continuing the polymerization reaction in the presence of a substance that does not substantially reduce the molecular weight of polyester, such as an ester compound consisting of an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and ethylene glycol. Is possible. This high molecular weight polyester is molded by any method to obtain a non-oriented polyester molded product. This unoriented polyester molded product is treated in an atmosphere of solvent vapor that is soluble in the polyester. Examples of solvents that are soluble in the polyester constituting the unoriented molded product include 0-chlorophenol, benzyl alcohol, nitrobenzene, m-cresol, phenol-tetrachloroethane mixture, phenol-xylene mixture, dichloroacetic acid, Examples include acetic acid chloride-ethane tetrachloride mixture, acetic acid trichloride-chloroform mixture, and the like. Among these, acetic acid dichloride is preferably used. Particular attention should be paid here to the fact that the unoriented polyester molded product is treated in an atmosphere of solvent vapor. If immersion treatment is performed in a solvent solution, crystallization of the unoriented polyester molded product progresses, making it impossible to perform high-strength stretching, and therefore, it is impossible to obtain a molded product with high strength, which is the object of the present invention. Can not. The treatment in the dissolving atmosphere is preferably carried out at a temperature of room temperature to 90°C for 5 to 24 hours. If excessive treatment is performed, crystallization occurs and the drawability decreases, making it impossible to increase the draw ratio and making it impossible to obtain a molded product with high strength. If the solvent vapor treatment is insufficient, the mobility of molecules will not increase, so high-strength stretching cannot be performed and a molded product with high strength cannot be obtained. Then, the unoriented polyester molding thus treated in a solvent vapor atmosphere is heated to a temperature of T _g or higher, T _g +20.
Netting stretching is carried out at a temperature of ℃ or lower, and then α _c or higher than the dispersion temperature, so that the total stretching ratio is 7 times or higher.
Second stage stretching is performed at a temperature below the melting point. here,
T _g is the second-order transition point of the polyester constituting the unoriented polyester molded product, and α _c is the dispersion temperature measured using a spectrometer VES-F manufactured by Iwamoto Seisakusho. Frequency 10Hz, heating rate 1.6 with 0.17% amplitude under load
It is measured under the conditions of °C/min, and means the peak temperature of the main dispersion of the crystal side that appears in the temperature dispersion of the mechanical loss modulus. If the netting stretching temperature and the second stage stretching temperature are outside the above ranges, stretching cannot be carried out smoothly, yarn breakage occurs frequently during stretching, and the strength of the molded product after stretching decreases. In the first stage of netting stretching, stretching is carried out at a speed of several hundred percent per minute, at a ratio around the natural stretch ratio, and in the second stage, stretching is performed at a speed of several hundred percent per minute to several times the natural stretching ratio. , is desirable for smooth stretching at high magnification. In particular, it is preferable that netting stretching be performed at a speed of around 300%/min and at a magnification of 3.75 times or more.
Further, it is particularly preferable that the second stage stretching is carried out at a speed of about 5%/min and at a magnification of 1.87 times or more. The molded product after stretching can be heat-treated under contraction, constant length, or expansion, as required. Effect: Unoriented polyester molded products treated in a solvent vapor atmosphere have less molecular chain entanglement due to the action of the solvent vapor, and can be easily stretched at high magnifications. internal structural defects are reduced. Moreover, the first stage of net stretching is carried out at a temperature near T _g , which is suitable for stretching unstretched lamellae, and the second stage is carried out at a temperature near crystal softening temperature, which is suitable for disentangling molecular chains. No defects occur in the process, and a high degree of molecular orientation is achieved.Therefore, compared to the conventional method of simply stretching an unoriented molded product at a high magnification, a molded product with high strength can be obtained. Examples Hereinafter, the present invention will be explained in detail with reference to Examples. Example A polyester made of polyethylene terephthalate was melted and discharged from a spinneret having 250 holes by a conventional method, and after cooling, an oil was applied and the material was spun for 800 m/s.
I wound it up in minutes. Thereafter, the undrawn fibers were treated in an atmosphere of dichloroacetic acid solvent vapor, and after preliminary drawing with a heated roll having a diameter of 9 cm, the first drawing was performed at a speed of 300%/min and wound up. Next, a second stage of stretching was performed at a rate of 5%/min through a heating plate with a length of 1 m. At this time, T _g (secondary transition temperature) of the polyester fiber
is 70℃, the a _c dispersion temperature is 210℃, and the melting point is 258℃. In this example, the intrinsic viscosity of polyester,
Table 1 shows the performance of the drawn fibers obtained when the processing conditions in the solvent vapor atmosphere, the first-stage stretching conditions, the second-stage stretching conditions, and the total stretching ratio were changed as shown in Table 1.

【table】

[Table] × marks indicate conditions outside the scope of the present invention.
Effects of the Invention According to the present invention, fibers with a strength of 10 g/de or more, which could not be industrially produced using conventional methods,
It becomes possible to produce highly strong polyester molded products with a weight of 50 kg/mm ² or more (film) extremely smoothly.

Claims (1)

[Claims] 1. An unoriented molded product made of polyester having an intrinsic viscosity of 0.9 or more is treated in an atmosphere of solvent vapor that is soluble in the polyester at a temperature of room temperature to 90°C for 5 to 24 hours. After that, netting stretching is performed at a temperature of T _g or more and T _g +20°C or less, and then a second stage of stretching is performed at a temperature that is not less than the αc dispersion temperature and not more than the melting point, so that the total stretching ratio is 7 times or more. A method for manufacturing strong polyester moldings. 2. The manufacturing method according to claim 1, wherein the molded product is a fiber. 3. The manufacturing method according to claim 1 or 2, wherein the polyester is polyethylene terephthalate.