JPS61207616A - Production of formed polyester having high strength - Google Patents

Abstract

PURPOSE:To obtain a formed polyester article having high strength, by dissolving a specific polyester in a solvent, extruding through a nozzle, etc., desolvating in a coagulation bath and subjecting to neck-drawing and second drawing under specific condition. CONSTITUTION:A polyester having an intrinsic viscosity of >=1.5 is dissolved in a solvent such as o-chlorophenol to obtain a solution of 3-10wt% concentation, and is extruded through a nozzle, die, etc. The extruded solution is immersed in a coagulation bath such as isobutyl alcohol to obtain a desolvated unoriented formed polyester article. The article is subjected to neck- drawing at Tg-Tg+20 deg.C, and then to second drawing at a temperature above the alphac dispersion temperature and below the melting point at a total draw ratio of >=15 to obtain the objective formed article (preferably fiber).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a high-strength polyester molded product by wet-molding a high-molecular-weight polyester and then carrying out double-stage stretching at a high magnification.

Conventional technology Since polyester molded products have various characteristics,
It is 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.

Usually, the economically advantageous melt forming method is used, and in order to develop the high strength required for industrial molded products, K is
It is common to melt-form a polyester with a high degree of polymerization and then stretch it at a high magnification.

On the other hand, as mentioned above, wet molding of polyester has not been studied at all because melt molding is more economically advantageous. Only some study results have been reported in Vol. 28, No. 1, pp. 15-22 (1972). Moreover, there is no teaching at all about obtaining a high-strength molded product by stretching a wet-molded, unoriented molded product at a high magnification.
.

Conventional melt molding and high-magnification stretching methods have limitations on the strength of the resulting molded products, and it is impossible to industrially produce fibers with a strength of 109/da or more or films with a strength of 50:9/- or more. It was possible.

The purpose of the present invention is to provide a method for manufacturing a molded product with high strength by combining wet molding and high-magnification two-stage stretching to break down the strength barrier of molded products in the prior art. There is a particular thing.

In the present invention, after dissolving polyester having an intrinsic viscosity of 1.5 or more in a solvent and discharging it as a solution of 3 to 10 weight,
The unoriented polyester molded product obtained by removing the solvent was neck-stretched at a temperature of Tg or higher and Ty + 20°C or lower, and then a second stage stretching was performed at a temperature higher than the dispersion temperature and lower than the melting point, and the total stretching ratio was 15. This is a method for producing a high-strength polyester molded product, which is characterized by making the molded product more than twice as strong.

The polyester targeted in the present invention has an aromatic dicarbonate as a main component and ethylene glycol as a main glyfur component. Here K “main”
means more than 50 molti. Therefore, other ingredients may be included without 50 ml.

Aromatic dicarboxylic acids are compounds in which a carboxylic acid is directly bonded to an aromatic group, such as terephthalic acid, inphthalic acid, diphenyl dicarboxylic acid, and phenyl ether dicarboxylic acid. preferable.

is preferred.

Furthermore, the third component to be copolymerized with the polyester in the present invention includes aromatic dicarboxylic acids other than the main constituent components of the polyester, oxalic acid, mapric acid, succinic acid, adipic acid, sebacic acid, and decanedicarboxylic acid. Aliphatic dicarboxylic acids such as hexahydroterephthalic acid, decalindicarboxylic acid, tetralindicarboxylic acid; glycol #up-oxybenzoic acid; trimethylene glycol, propylene glycol, 1,4 butanediol, l , 3-butanediol, neopentyl glycol, 1,6-hexanediol, and other aliphatic diols other than the main constituent components of the polyester; cyclohexanedimethylol, tricycloofcandimethylol, and other alicyclic diols;
Aromatic diols such as bisphenol A, bisphenol S, bishydroxyethoxybisphenol A, and tetrabromobisphenol A are exemplified.

These polyesters may also contain up to 10% by weight of other polymers, and may also contain additives such as stabilizers, colorants, and the like.

The molded product in the present invention is a fiber or a film.

Although it is a general term for other molded products, it can particularly produce remarkable effects in the case of fibers.

The polyester used in the present invention needs to have an intrinsic viscosity of 1.5 or more as determined from an O-coulophenol solution at 25°C. If the intrinsic viscosity is less than 1.5, the desired high-strength polyester molded product cannot be obtained. The intrinsic viscosity is preferably 1.5 to 5.0. 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, gas is added under the polymerization conditions. It can be efficiently produced by continuing the polymerization reaction in the presence of a substance that does not substantially reduce the molecular weight of the polyester, such as an ester compound consisting of an aliphatic dicarboxylic acid having 6 to 20 carbon atoms and ethylene glycol. It is possible to do so.

After such high molecular weight polyester is dissolved in a solvent,
It is discharged through a nozzle, slit, die, etc., and then
The solvent is removed in a coagulation bath, resulting in an unoriented polyester molded product.

Solvents used to dissolve high molecular weight polyesters include 0-chlorophenol, benzyl alcohol, nitrobenzene, m-cresol, and phenol-tetrachloroethane i compound.

Phenol-xylene mixture, acetic acid dichloride.

Examples include a trichloroacetic acid-tetrachloroethane mixture, a trichloroacetic acid-chloroform mixture, and the like.

Among these, acetic acid dichloride is preferably used.

In this case, it is necessary to set the solution concentration Ik of PoI)z stell to 3 to 10% by weight. If the solution concentration is less than 3% by weight, the stringiness will be poor and furthermore, it will not be possible to obtain molecular hooking points for continuously inducing and advancing the stretching.
It is not possible to perform uniform stretching and it is not possible to obtain sufficient strength (・.

On the other hand, if the solution concentration exceeds 10% by weight, there will be too much entanglement of molecules, making it impossible to stretch at a high magnification and making it impossible to obtain high strength.

The coagulation bath for removing solvent from extrusion moldings includes ethanol, 7setone, ethanol-water mixture, acetone-water mixture, imbutyl alcohol, isopropyl alcohol,
n-butylfluor, n-7'ρyl alcohol, p-pyrene glycol, n-hexane, petroleum ether 9-ethylene chlorohydrin, etc. are used. Among these, isobutyl alcohol is preferably used. When removing the solvent, it is preferable to set the residual rate of solvent in the molded product to 5 to 15 cm in the high-magnification stretching process (row 55).

The thus obtained unoriented polyester molded product is neck-stretched at a temperature of Tg or higher and T,@+20°C or lower,
Next, a second stage of stretching is carried out at a temperature above the αC dispersion temperature and below the melting point so that the total stretching ratio becomes 15 times or more. here.

Tli is the second-order transition point of the polyester constituting the unoriented polyester molded product, and mc dispersion temperature was determined using a spectrometer YES-F model manufactured by Himoto Seisakusho. /do static load, 0.17% amplitude, frequency 10Hz v heating rate 1
．． Measured at 6° C./min, which means the peak temperature of the main dispersion of the crystal side that appears in the temperature dispersion of the mechanical loss modulus.

When the necking 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 necking stretching, stretching is carried out at a speed of several hundred and seventeen minutes at a ratio around the natural stretching ratio, and in the second stage stretching, stretching is performed at a speed of several %/minute to several times the natural stretching ratio. This is desirable for smooth stretching at different magnifications.

In particular, necking stretching is preferably carried out at a speed of around 300%/min at a magnification of 4 times or more, and the second stage stretching is performed at 5%/min.
It is particularly preferable to perform the test at a speed of around 3.75 minutes or more at a magnification of 3.75 times or more.

Wet molded unoriented polyester molded product.

After being wound once, it may be subjected to stretching, or it may be continuously subjected to stretching without being wound once.

The molded product after stretching is shrunk as necessary.

It can be heat treated under constant length or extension.

Function: The unoriented polyester molded product obtained by wet molding has less entanglement of single molecular chains and can be easily stretched at high magnification, resulting in fewer internal structural defects in the molded product after stretching.

Moreover, the first stage of neck stretching is carried out at a humidity near Tp, which is suitable for stretching unstretched lamellae (・, because the second stage of stretching is carried out near crystal softened mineral deposits, which is suitable for disentangling molecular chains, There are no defects in the internal structure and a high degree of molecular orientation, compared to the method of stretching unoriented moldings obtained by conventional melt-molding methods.

A significantly higher (and stronger) product can be obtained.

Example Hereinafter, the present invention will be explained in detail with reference to Examples.

〔Example〕

Q. Preparation of solution The solution was dissolved in a chipped acetic acid dichloride solvent consisting of polyethylene terephthalate at 110'c for 40 minutes, and then cooled to obtain a spinning solution.

Creation of O-undrawn fiber While maintaining the spinning solution at 110°C.

It was discharged from an o, f5 mm spinneret under a N2 pressure of 1K9/cId, passed through an ingtyl alcohol coagulation bath just below the spinneret, and was wound up at 1Om/al.

Preparation of O-drawn fibers The undrawn fibers were left at room temperature for 2 days, then preheated with a heating roll of diameter 91, and then subjected to the first drawing at a speed of 30 (11/min) and wound up. A second stage of stretching was carried out at a speed of 5%/min using a tm heating plate.At this time,
The polyester fiber had a T9 (secondary transition temperature) of 70°C, an αC dispersion temperature of 210°C, and a melting point of 258°C.

In this example, the intrinsic viscosity of polyester.

Table 1 shows the performance of the drawn fibers obtained when the solution concentration, first-stage stretching conditions, second-stage stretching conditions, and total stretching ratio were changed as shown in Table 1.

In addition, A4 polyethylene terephthalate (intrinsic viscosity 1
．． 6) Normal melt spinning was carried out using F, but it was not possible to obtain undrawn fibers with a high viscosity (discharged from the spinneret and connected at ℃).

Effects of the Invention According to the present invention, 15 to 50 g/de (fiber), which could not be industrially produced by conventional methods.

It becomes possible to produce highly strong polyester molded products of 60 to 100 Kg/t4 (film) extremely smoothly.

\+/

Claims (1)

[Scope of Claims] 1. A polyester having an intrinsic viscosity of 1.5 or more is dissolved in a solvent to make a solution of 3 to 10% by weight, which is discharged, and then the unoriented polyester molded product obtained by removing the solvent is Above, Tg
Netting stretching at a temperature below +20°C, then α_c
Performing the second stage stretching at a temperature above the dispersion temperature and below the melting point,
A method for producing a high-strength polyester molded product, characterized in that the total stretching ratio is 15 times or more. 2. The method according to claim 1, wherein the molded product is a fiber. 3. The method according to claim 1 or 2, wherein the polyester is polyethylene terephthalate.