JPS5884821A - Copolyester fiber or film and preparation thereof - Google Patents

Abstract

PURPOSE:To obtain the titled tough and strong fibers having improved dimensional stability at high temperatures, by extruding a copolyester prepared by copolymerizing an aromatic oxycarboxylic acid component, aliphatic diol component, etc. in a specific proportion in a molten liquid crystal state. CONSTITUTION:A copolyester, obtained by copolymerizing p-acetoxybenzoic acid with polyethylene terephthalate, 2-methylhydroquinone diacetate and terephthalic acid, containing units expressed by formulasI, II and III (R1, R2, R3 and R4 are p-phenylene, 2,6-naphthalene, etc.), and consisting of 5-80mol% units of formulaI, 10-30mol% units of formula II and 5-65mol% units of formula III is heated to form a molten liquis state, and the resultant molten liquid crystal is extruded to give the aimed fibers or films. EFFECT:Improved fatigue resistance and stability to chemicals.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel copolyester fiber or film and a method for producing the same. The present invention relates to a method for providing a fiber or film that is tough and has excellent Young's modulus and dimensional stability at high temperatures, and products thereof.

Polyesters that form molten liquid crystals are known.

For example, JP-A-50-43225, JP-A-55-
200 (Large polyester described in Publication No. 1 etc. has fluidity and optical anisotropy above a certain temperature,
Indicates liquid crystal characteristics. These prior documents describe forming fibers etc. from molten liquid crystals by a normal melt molding method. For example, in the case of fibers, it is described that
It is also known that the fibers have a highly oriented, high Young's modulus in the unprocessed state, and that the fibers can be strengthened by heat treatment. In addition, JP-A-55-106220 and JP-A-1855-104221 disclose liquid crystalline polyesters that are easy to melt and mold due to their low melting point (fluidization temperature) and low melt viscosity. ing.

Furthermore, JP-A-49-72595, JP-A-51-
In Publication No. 8395 and Japanese Unexamined Patent Publication No. 54-69199,
Liquid crystalline copolyesters partially containing ethylene terephthalate units are disclosed.

It has been found that these known liquid crystalline copolyesters and molded products thereof each have their own specific defects. Listing them is as follows.

11+ Materials that are difficult or impossible to mold because of their high melting point or melting temperature (temperature at which fluidization begins, hereinafter referred to as "-"). For example, the polymers disclosed in JP-A-50-43223 and JP-A-55-20008, and the polymers disclosed in JP-A-49-72393 and JP-A-54-6919.
These include copolyesters with a low content of ethylene terephthalate units as disclosed in Publication No. 9.

(2) Large thermal shrinkage at high temperatures, ie, lack of dimensional stability. Examples include copolyesters disclosed in JP-A No. 51-83956 and copolyesters containing a considerable amount of ethylene terephthalate units as disclosed in JP-A-49-72393 and JP-A-54-69199.

(31) Although it is highly oriented in the extrusion direction during molding and has excellent mechanical properties in that direction, it lacks toughness because the mechanical properties in the direction perpendicular to it are extremely poor. This is a common defect in molded products made from polyester, but for example,
This tendency is greater in the copolyesters disclosed in Publication No. 8, JP-A-55-106220, and JP-A-55-106221.

(4) Copolyester has a high melt viscosity compared to its degree of polymerization and is difficult to mold. For example,
Copolyesters disclosed in JP-A No. 008 and JP-A-50-43225 are applicable.

(5) Infusible particles are contained in the polymer after polymerization,
A book with poor formability. For example, JP-A-55-104220
There are copolyesters disclosed in Japanese Patent Publication No. 55-104221.

The present inventors conducted a multifaceted study on a copolyester that does not have or has the above drawbacks reduced, and that maintains the advantageous characteristics inherent to molten liquid crystalline polyester, such as having a high strength and high Young's modulus in its molded products. As a result of repeated research, we discovered that a copolyester made by copolymerizing an aromatic oxycarboxylic acid component, an aliphatic diol component, an aromatic diol component, and an aromatic dicarboxylic acid component in a special ratio satisfies these objectives. Furthermore, the present invention was completed by conducting research while taking into account the ease of obtaining raw materials for industrial implementation, the ease of carrying out polymerization reactions, etc.

That is, the present invention provides units (I) to (III); -0
-R, -C-(I) 1 0 0 (wherein Rt~- is a paraphenylene group, a 2.6-naphthalene group, a 1.5-naphthalene group, a 4.4'-biphenylene group, and a 1.2 A divalent group selected from -ethyleneoxy-4,4'-diphenylene group; R1- may be the same or different from each other; It may be substituted with lower alkyl, )~rogen, nitro, cyano, alkoxy, etc. ), and the unit (I) is 5 to 80 mol, the unit (■) is 10 to 30 mol, and the unit (m) is 5 to 65 mol. , the present invention also provides unit (I) ~ plate); -0-R1-
C-(I) 1 9- (wherein R1-R4 is a paraphenylene group, a 2,6-naphthalene group, a 1.5-naphthalene group, a 4.4'-biphenylene group, and a 1,2-ethyleneoxy- A divalent group selected from 4,4'-diphenylene groups, R+~R
1 may be the same or different, and some of the hydrogen atoms on the aromatic ring are lower alkyl, ), rogene,
It may be substituted with nitro, cyano, alkoxy, etc. ) and having a unit (I) of 5 to 80 molt, a unit tune of 10 to SO molt, and a unit (IID of 5 to 65 molt) is heated to a bath melt liquid crystal state, and the molten liquid crystal is It is a method for producing a fiber or film characterized by extruding a fiber or film, and furthermore, the present invention is a method for producing a fiber or film characterized by extruding a unit (Il~(R; -1R-00) (wherein R4 is paraphenylene ts, 2. A divalent group selected from 6-naphthalene group, 1.5-naphthalene group, 4.4'-biphenylene group and 1.2-ethyleneoxy-4,4'-diphenylene group, n* to R,
Fi may be the same or different, and some of the hydrogen atoms on the aromatic ring may be substituted with lower alkyl, halogen, nitro, cyano, alkoxy, etc.), and A copolyester containing 5 to 80 mol of units (I) and 10 to 50 mol of units (up to 1 unit) (5 to 65 mol of units) is heated to form a molten liquid crystal, and the molten liquid crystal is extruded. This is a method for producing a fiber film, which is characterized in that the fiber is then heat treated at a temperature of about 150° C. or higher under tension or relaxation.

The copolyester used in the present invention basically has the following units (I) to (curve; -0-R, -C-(1) 1 (wherein R2 to R*Fi, paraphenylene group, 2 ,6-
Naphthalene group, 1,5-naphthalene group, 4,4'-biphenylene group and 1,2-ethyleneoxy-4,4'
-1Lnt~ with an fCZ-valent group selected from diphenylene groups
R4t:I may be the same or different,
Further, some of the hydrogen atoms on the aromatic ring may be substituted with lower alkyl, halokene, nitro, cyano, alkoxy, or the like. and the unit (1) is 5 to 80 molar predominant unit I is 1
0-30 molti, unit (the dish is 5-65 molti).

The copolyester of the present invention consisting of such special units and their content can have t of about 35%, depending on its degree of polymerization.
(Hereinafter, the temperature at which fluidization begins will be referred to as the "flow temperature".)
, it forms a nematic liquid crystal at temperatures above the flow temperature, and therefore has optical anisotropy despite its fluidity.

The copolyesters of the present invention also have flow temperatures of about 200:111:1 and above. The fact that the copolyester used in the present invention has such flow temperature characteristics means that it can be easily melt-molded.
This means that melt molding equipment can be used. In this respect, it can be said that it has much better spinnability and moldability than the liquid crystalline polyesters disclosed in JP-A-50-43223 and JP-B-55-20008. Mumou, Japanese Patent Application Laid-Open No. 49-72595 and % Open Route 54-
Among the liquid crystalline polyesters disclosed in Japanese Patent No. 49199, the same thing can be pointed out for -13- as compared to the polyesters having a lower content of ethylene terephthalate units.

In addition, since molten liquid crystals are formed at temperatures above the so-called flow temperature, the unique characteristics of liquid crystalline copolyesters, such as excellent strength and elongation properties of as-spun fibers and as-formed films, still remain. Moreover, surprisingly, the fibers and films of the present invention were found to be tougher and stronger than fibers and films formed from known liquid crystalline polyesters. In the case of fibers, for example, the nodules Ij
It can be compared with M degree.

The copolyester used in the present invention is
It has the following advantages over the polyesters disclosed in JP-A No. 220 and JP-A-55-186221.

Firstly, as mentioned above, the molded product must be tough.
Second, the copolymer composition has small variations and the copolymer has excellent homogeneity, resulting in excellent moldability. Third, when paraphenylene groups are selected as R1-R4, seven - is inexpensive and easily available -14-.

The copolyester fiber and top film of the present invention are disclosed in Japanese Patent Publication No. 4
The liquid crystal copolyester molded products disclosed in Publication No. 9-72593, Publication No. 69199/1982, and Japanese Patent Application Laid-open No. 8595/1982 are exposed to high temperatures (e.g. 150-200°C).
It has a low thermal shrinkage rate at temperatures (°C) and therefore has excellent elongation and properties and dimensional stability at high temperatures. In addition, it has the advantage that the strength and elongation characteristics of a molded article can be easily improved by heat treatment, since the orientation relaxation does not easily occur at high temperatures and polymerization is inhibited.

In the copolyester used in the present invention, any acid component can be introduced by joining the corresponding aromatic hydroxycarboxylic acid or any derivative thereof during polymerization of this unit Fi mycopolyester. R1 is
Para-phenylene group, 2,6-su7thale group, 1,5-naphthalene group, 4,4'-biphenylene group and (jl, 2
-Ethyleneoxy-4,4'-diphenylene group, but paraphenylene group and 2,6-naphthalene group are more preferably used from the viewpoint of ease of obtaining raw materials.

Note that a part of the hydrogen atoms on the aromatic group of R1 may be substituted with lower alkyl, halokene, nitro, cyano, alkoxy, or the like.

The unit (I) should be present in an amount of 5 to 80 moles (5 to 80 moles).If the amount of Il is small, the flow temperature of the polyester will become high and it will be difficult to melt and mold it, and if the unit (I) exceeds 80 moles, , the melt viscosity tends to increase and the homogeneity of the polyester becomes poor, which is undesirable.The desirable content of the unit (I) is 10-700-7
The amount is preferably 0 mol, more preferably 20 to 60 mol.

It is represented by the formula, - is a para-2enylene group, 2.6-naphthalene M, 1.5-naphthalene group, 4,4'-biphenylene group, and 1,2-ethyleneoxy-4,4'-diphenylene group. A divalent group selected from: i, some of the hydrogen atoms of the aromatic loam of n* are lower alkyl, haa) tfi
It may be substituted with nitro, cyano, alkoxy, etc. This unit is conveniently introduced during the polymerization of the copolyester by joining the polyester corresponding to the unit (2). However, this method is not limited to this method.

From the viewpoint of ease of obtaining raw materials and ease of molding the copolyester, it is most desirable to select a paraphenylene group as the bird and use an ethylene terephthalate unit as the unit.

The unit (■) should be in the range of 10 to 300 to 30 moles, and if the unit (■) is less than 10 mole, the flow temperature of the copolyester will become high, and the so-called melt viscosity will become high, making spinning and molding difficult. Not only is it extremely difficult to mold, but it also loses its toughness when formed into fibers or films. On the other hand, if the unit 0 exceeds 50 moles, the copolyester maintains its property of being easy to mold, but the molded fibers and films shrink considerably when placed in a warm environment. , the -17- strength and elongation properties at high temperatures become significantly inferior to the strength and elongation properties at room temperature, or it becomes impossible to increase the degree of polymerization or improve the strength and elongation properties by heat treatment.

The units should more desirably be present in an amount of no less than 15 to 25 moles.

Represented by the formula, R, and R4#i, paraphenylene group, 2.6-naphthalene group, 1.5-naphthalene &, 4.
4'-biphenylene group and 1,2-ethyleneoxy-
It is a divalent group selected from 4,4'-diphenylene groups, and Rt to R1 may be the same or different from each other, and some of the hydrogen atoms on the aromatic group are lower alkyl, halogen, nitro. , cyan, alkoxy, etc. g. from the viewpoint of ease of assembly, ease of molding, ease of obtaining raw materials, etc.

Paraphenylene group, 2-methylparaphenylene group, 2-chloroparaphenylene group, 2-ethylhalapenylene group, 2-methoxyparaphenylene group, and 2-butylparaphenylene group are preferably used as % R4, and paraphenylene group is used as R4. is preferably used. The units (plates) can be introduced during the polymerization of the copolyester by participation of the corresponding aromatic diols and aromatic dicarboxylic acids or derivatives thereof.

Unit (III) should be present in 5 to 65 mol units (if g is less, the remaining units (I)
Depending on the abundance ratio of I and I, molding may become virtually impossible (due to an abnormal increase in flow temperature fct1/ and melt viscosity), or the dimensional stability of the molded product at high temperatures may deteriorate. So I don't like it.

Also, when the unit (m) exceeds 65 moles, molding becomes difficult and only non-uniform copolyester is obtained, resulting in extremely poor strength and elongation properties of the molded product. I don't like it. It is highly desirable that the unit (In) be present in an amount of 10 to 55 moles.

To clarify the composition of the copolyester used in the present invention,
In order to clarify the difference from liquid crystalline polyesters described in known documents, the following will be explained using drawings. In the drawing, the area surrounded by dots B, C, D, and g is the copolyester used in the present invention, and the area above line segments AB and BC, to the left of line segment AE, and below line segment DE Compositions outside the present invention have the general characteristic that flow temperatures and melt viscosities of 1-1/1 are still very difficult to form. On the other hand, the composition to the right of line segment CD is
This is not preferred because it gives a molded product with a large shrinkage rate at high temperatures. A typical example of such polyester is JP-A-51-8
Liquid crystal polyurethane disclosed in No. 395/(f k (R,=
R,=R,=4=paraphenylene group],
This polyester composition, when converted to the mole fraction of the present invention, is represented by point X in the drawing.

This corresponds to the range surrounded by y, z, and w.

In addition, the polyester that is composed of only the unit (1) and the unit (■) (that is, located on the right-hand oblique side of the drawing) is described in JP-A-49-72595 as a polyester that is composed of only the unit I and the unit (m). In Japanese Patent Application Laid-Open No. 54-69199, the polyester (located at the bottom of the drawing) has the unit (I)
The polyester (located on the left hypotenuse of the drawing) is made up of only the unit (m) and
Although each of these polyesters is disclosed in Japanese Patent No. 223, these polyesters have inherent defects as described above. Further, Japanese Patent Publication No. 55-20008 does not describe the copolyester of the present invention at all, and the polyesters disclosed in the examples generally have a high flow temperature and the molded products thereof lack toughness.

The copolyester of the present invention has units (1) to (nD) as essential constituent units, and since the units (I) to (encircled) are copolymerized in a specific ratio, various defects of known liquid crystal polyesters can be avoided. An excellent copolyester was provided which solved the problem.The method of copolymerization of units (I) to (I[D) is not particularly regulated; ) to (11) may be present in a specified molar fraction.For example, the unit (2)i or (1) is present in the copolyester in the form of a reverse unit or in a bonding manner. There is no need, especially −〇 −
11-C-0-CM, cH, -01 - 21- - R1-C-0-R, -0-, etc., i.e.
1 The units (I) and (Ill) or the units (Il and (Ill) may exist in a so-called sum-mutualized form, and even in such cases, there is no need to worry because the copolyester is a molded hJ cage. Due to the condition of having a polymerization degree of more than one foot, the number of moles of the diol component and the dicarboxylic acid component of the instep of the entire copolyester become equal, so that units (1) to ( A copolynisder composition can be defined in the form 110.

In addition, the copolyester is a blend having each of the units (11 to (lit) as repeating units), or/and the units (I) to (III) are co-located in block form in a considerably long repeat. This is excluded in the case of polymerized copolyesters, since in such cases the units (I
) or unit (110) as a repeating unit has a melting point exceeding about 400° C., and cannot be stably molded.

-22- The copolyester used in the present invention can contain a small amount of components other than the above three units as long as its characteristics are not lost. Such components include, for example, meta-oxybenzoyl, inphthaloyl, 2,2-bis(
p-oxyphenyl)propane, 1,2-dioxyethane, 1,4-dioxy-n-butane, and the like.

The copolyester used in the present invention is generally 2, -o -C
It has a terminal group of 0CH or -COOHO type.

However, this terminal group may optionally be omitted.

Further, if necessary, the material may be oxidatively crosslinked to some extent by heat treatment in an oxygen-containing atmosphere (for example, in air) after molding.

When heated, the copolyester used in the present invention has a liquid crystalline state of 11t-
show. The polymer molecules in the fiber or film are highly oriented as they are spun or formed.

The fibers or #i films of the present invention and their manufacturing method are listed as follows, and these characteristics are derived from the fact that the polyester used in the present invention has a special chemical composition. It should be noted that

■Compared to conventionally known liquid crystalline polyesters, it has excellent spinnability and moldability even with high molecular weight polyesters.

(2) Fibers or films spun or formed from known liquid crystalline polyesters are tougher, thicker, less brittle, and have strength and Young's modulus equal to or greater than them. Obtained in the as-molded state or after heat treatment.

(Higher molecular weight polyesters can be easily obtained by melt polymerization or subsequent in-phase polymerization.

0) Good dimensional stability at high temperatures (e.g. 150 to 20 oC).

■Excellent stability against chemicals.

The copolyester ti used in the present invention can be prepared by various ester-forming methods in which organic monomeric compounds having a functional group to form the necessary repeating units and, if necessary, a polymer are reacted. For example, the functional groups of organic monomer compounds include carboxylic acid groups, human tetraxyl groups,
It may be an ester group, an acyloxy group, a Q-genide to an acid, etc., and the polymer may be polyethylene terephthalate, polyethylene-2,6-naphthalate, etc. Organic monomer compounds are prepared by known methods such as melt polymerization, heated solution polymerization, heated suspension polymerization, low-temperature solution polymerization, and interfacial polymerization.
Can be converted to copolyester. The degree of polymerization can be further increased by the so-called in-phase polymerization method, either before molding or at any stage after molding.

In the present invention, if the copolyester having the chemical composition described above is heated to a temperature above the so-called flow temperature to form a molten liquid crystalline path, it can be easily molded into fibers, films, KM yarns, or the like. The extrusion orifice for producing fibers or films can be selected from those commonly used when melt extruding them. For example, in the case of film production, the extruded orifice may be a rectangular slit (slit die). When spinning into fibers, polyethylene-25
- about 0.05 to 2, commonly used for spinning terephthalate
．． A standard spinneret with a circular hole of diameter θ 1 is used. At this time, there is no limit to the number of holes in the spinneret. Also, if desired, spinnerets with holes in shapes other than circular, such as oval, L-shaped, T-shaped, C-shaped, etc., can be used. In addition, polymers other than the above-mentioned copolyesters (for example, polyethylene terephthalate, polybutylene terephthalate, nylon 6
It is effective to mix a small amount of nylon 6"6) or ordinary additives with the polyester of the present invention for spinning and molding, as long as the characteristics of the present invention are not lost.

The fibrous or film material extruded from the orifice is passed through an assimilation or cooling zone where it is converted into fibers or films. At this time, the temperature distribution and atmosphere from the orifice to the cooling area may be freely modified using hot air, cold air, cylinders, heaters, inert gas, etc. If desired, cooling may be performed with a liquid such as water instead of air. In the case of fibers, they are drawn between the spinneret and the cooling zone, usually at a draft of 1 to 100 or more, and the spun fibers are usually drawn at a draft of 0 to 100 or more.
．． It has a single fiber denier of 5 to 50.

The fiber or film of the present invention is characterized by high strength and high Young's modulus because the polymer chains are highly oriented when it is extruded from an orifice and cooled until +t.

However, if desired, the as-extruded fiber or film can be heat treated to further improve its mechanical properties. That is, the strength of the fiber or film is increased by heat treatment. This is believed to be because the heat treatment increases the degree of polymerization without causing relaxation of the orientation of the polymer chains. The heat treatment can be performed at a temperature below the flow temperature of the fiber or film, with or without stress, under an inert atmosphere (eg, nitrogen, argon, helium) or vacuum. When stress is applied and heat treatment is performed in the 9-state state, the King 5 ratio generally increases.

The heat treatment temperature may be kept constant or may be increased stepwise or continuously as the polyester flow temperature increases. The heat treatment time is usually selected from several minutes to several tens of hours. In order to prevent adjacent fibers and films from fusing together during heat treatment, one preferred embodiment is to perform heat treatment after treatment with talc, silica, etc.

The fibers of the present invention have high strength, a high Young's modulus, and are tough, so bamboo is useful for industrial material applications where these characteristics can be utilized. Specifically, it is very useful for rubber reinforcing materials for tire cords, conveyor belts, hoses, etc., lobes, cables, and even resin reinforcing materials. For such uses, the toughness of the fibers of the present invention is fully exerted and the fibers have excellent fatigue resistance, and the fibers W of the present invention, for example, have good dimensional stability at high temperatures, It is also widely used for its good chemical resistance.

The film of the present invention can be used for packaging strings, cable wrapping materials, magnetic tapes, motor dielectric films, etc., and exhibits its characteristics to the fullest.

Example 1 As a copolyester exhibiting molten liquid crystal, a polymer having the following composition was mixed with 4.5 mol parts of 1-para-acetoxybenzoate, v@p
/ C'I'' 0.15 (0.5 at 60℃ in a mixed solvent of 50:50 volume ratio of phenol and tetrafluorethane
2.0 mol parts of polyethylene terephthalate (measured by a conventional method at f/100), 2-methylnoid CI-? It was prepared by acetic acid removal melt polymerization method from 3.6 mol parts of nondiacetate (0.1 mol part was added in excess) and 5.5 mol parts of terephthalic acid. That is, put the above raw materials into a polymerization container,
After purging with nitrogen, the temperature was raised from room temperature to 315° C. over about 50 minutes. Next, the acetic acid was distilled off at 315°C for 1 hour, and finally, the product was placed at 320°C for 1 hour under a reduced pressure of about 0.40 Hg.The yield was 99g! In the above manner, a copolyester having a composition of -29= was obtained.

ηsp/c #i1.5-(
611) under the same conditions as above, and the flow temperature was about 280°C. Furthermore, when observed under a polarizing microscope at 295 to 300°C, it was found that optical anisotropy was exhibited under static conditions.

After sufficiently drying the fibrous monolithic polyester, it is fed to an extruder type melt spinning machine and the melting temperature is 305.
While melting at ℃, it was extruded through a nozzle with a hole diameter of 0.1 mφ and 28 holes, and taken out at a speed of 450 ml/min.

The filament as wound has an ηsp/c (
Measured under the above conditions), 7,4 f/d (7) Intensity, 2
．． 9% elongation, Young's modulus of 4309/d, 1,49/d
It had a knot strength of d, and the shrinkage rate when held at 200°C for 38 minutes was 0.1%.

Next, this filament was heat treated at 240 to 240° C. under a nitrogen stream for about 15 hours without applying tension. The filament after heat treatment had ηsp/c which was rarely measurable under the above conditions, but had a strength of 17.3 f/d-30-, an elongation of 3.8%, a Young's f-modulus of 4 o s f/dtD, and 3 It has a knot strength of .7 t/d and a knot strength of 200
The shrinkage rate when held at ℃ for 30 minutes was low.

On the other hand, for comparison, a copolyester other than the present invention was prepared according to Example 1 of JP-A-51-8395. That is, 1.5 mole parts of paraacetoxybenzoic acid, ηsp
/c = 0.15 (measured under the above conditions), 2.0 mol parts of polyethylene terephthalate, 1.6 mol parts of noihydroquinone diacetate (0.1 mol part was added in excess),
From 1.5 mol parts of terephthalic acid, unit (I) t3o mol%, unit Ql) t-411 l*, unit (111) is 30
A copolyester with a molar content of η sp/c = 1.4 (measured under the conditions described above) was obtained. The flow temperature of this copolyester was about 260 DEG C., and polarization microscopic observation revealed that above this temperature it was an optically anisotropic fluid, that is, a free product. Melt spinning was carried out under exactly the same conditions as for the polyester described above, except that the melt temperature was set at 295°C.

The as-collected filament has a da sp/c (measured under the above conditions) of 1.4, a strength of 7.0 t/d, and an elongation of 2.
8 inches, Young's modulus 580 f/d, knot strength 1.6 f/
d, and when held at 200℃ for 30 minutes, rice & cLWi
The shrinkage rate reached approximately 2%.

When this filament was heat treated under the same conditions as above except that the temperature was 220-240°C, the strength was 2.
1? /d, elongation decreased to 4.3%, and Young's modulus decreased to 55 f/d. Then, when the same heat treatment was applied with a tension of about 0.5 t/d, the strength was 1'1.5 f/d, the elongation was 3°6 inches, the Young's modulus was 360 f/d, and the knot strength was f4.1 f/d.
d, but the shrinkage rate at 200°C was as large as 1.1 inches.

The copolyester fiber of the present invention is disclosed in Japanese Patent Application Laid-Open No. 51-8395.
Compared to the fiber prepared by melt-spinning the copolyester disclosed in the publication, the strength and elongation in the as-spun state is Oka or higher, and the dimensional stability at 200°C is significantly improved. Therefore, there are significant restrictions on strength and Young's modulus due to thermal processing.

Example 2 Copolyesters with various compositions were prepared in the same manner as in Example 1. The results are shown in Table 1.

These copolyesters all exhibit optical anisotropy at rest at temperatures above the flow temperature fc.

Also - strong films were obtained from all copolyesters with dies prepared at 290-350°C, and 230-27°C
The toughness was further increased by vacuum heat treatment under tension at 0°C.

-3s- Example 6 The superior characteristics of the copolyester fibers of the present invention are illustrated in comparison with fibers from known liquid crystalline copolyesters.

Common raw materials include paraacetoxybenzoic acid, ηsp/
Polyethylene terephthalate, 2-methylhydroquinone diacetate, and terephthalic acid with c = 0.52 (measured under the same conditions as Example 1) were prepared, and polymerization was carried out in the same manner as in Example 1 while changing the charging ratio of these. As a result, a copolyester with a smooth polymer composition was obtained. The polymerization conditions and results are shown in Table 2-1, of which numbers 5-4 and 3
For -5, the temperature in the final stage of polymerization was 350°C. The resulting copolyesters formed liquid crystals above their respective flow temperatures.

Second, the copolyester was heated to about 40°C below its respective flow temperature.
The material was melted at a temperature higher than 50° C., melt-spun from a spinneret with 6 holes of 0.25111φ, and wound in sOOm 7 minutes. The area under the spinneret was kept warm with a tsutsuki cloth, and the area underneath was kept cool at room temperature.

-35- However, since the copolyesters No. 3-4 and 3-5 needed to be melted at high temperatures, they were severely decomposed and could not be spun satisfactorily.

The properties of the filament obtained by spinning are shown in Table 2-2.

Next, the as-spun fibers were wound around a stainless steel bobbin with holes, and the temperature was raised stepwise from 200°C by 10°C every 1.5 hours, for a total of 7.5 hours under vacuum. heat treated. At this time, talc was applied next to prevent fusion between the filaments.

The properties of the filament after heat treatment are shown in Table 2-2.

From this example, the excellent dimensional stability and high temperature mechanical properties of the fibers of the present invention can be understood.

-56- -37-

[Brief explanation of drawings]

The drawing is an explanatory diagram showing the composition of the copolyester used in the present invention. -39-

Claims (1)

[Scope of Claims] ...Units (I) to (song; - A divalent group selected from a naphthalene group, a 4,4'-biphenylene group, and a 1,2-ethyleneoxy-4,4'-diphenylene group. (Some of the hydrogen atoms on the aromatic ring may be substituted with lower alkyl, norogen, nitro, cyan, alkoxy, etc.)
and containing 5 to 80 moles of units (I) - 10 to 30 moles of unit 0, and 5 to 65 moles of units (plates). (2) R1- The fiber or film according to claim 1, wherein all of R4 are paraphenylene groups. (3; R and R are paraphenylene groups), R
Claims in which s is a group selected from the group consisting of 2-methylparaphenylene group, 2-chloroba2phenylene group, 2-ethylparaphenylene group, 2-methoxyparaphenylene group, and 2-butylparaphenylene group The fiber or film according to scope 1. (4) Unit (Il~ (knock; -0-R, -C-(I) 1 0 0 0 (wherein, R1- is a paraphenylene group, 2.6-su7
A divalent group selected from a talene group, a 1,5-naphthalene group, a 4,4'-biphenylene group, and a 1,2-ethyleneoxy-4,4'-diphenylene group.
They may be the same or different, and the hydrogen atom O-s on the aromatic group may be substituted with lower alkyl, halogen, nitro, cyano, alkoxy, or the like. ) and the unit <I) is 5 to 80 mol - 1 unit A method for producing a fiber or film characterized by extruding a molten liquid crystal. (5) Units (I) to (concave; -0-R, -C-(I) I 0 0 (in the formula, R1 to R, t ;i, paraphenylene group, 2,6
-naphthalene group, 1,5-naphthalene group, 4,4'-biphenylene group and 1,2-ethyleneoxy-4,4'
- It is a divalent group selected from diphenylene groups, and it is a divalent group -
may be the same or different, and some of the hydrogen atoms on the aromatic product may be substituted with lower alkyl, halogen, nitro, cyano, alkoxy, etc. ) Contains 5 to 80 mol of unit (I), unit (2
) is 10 to 30 mol, and the unit (m) is 5 to 65 mol. The copolyester is heated to a molten liquid crystal state, the molten liquid crystal is extruded, and then the molten liquid crystal is extruded at a temperature of about 150° C. or higher under tension or relaxation. A method for producing fibers or films characterized by: