JPH0625250B2 - Method for producing high-modulus aromatic polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a method for producing a high-rigidity polyester capable of being melt-molded at 450 ° C. or lower and having excellent mechanical properties and optical anisotropy.

<Prior art> In recent years, the demand for higher performance of plastics has increased more and more, and many polymers having various new properties have been developed and put on the market. In particular, optics characterized by parallel arrangement of molecular chains Attention has been paid to the fact that anisotropic liquid crystal polyester has excellent mechanical properties.

Among these liquid crystal polyesters, a polyester containing 4,4'-diphenyldicarboxylic acid as a main component of an aromatic dicarboxylic acid is known to be a particularly high elastic modulus polyester (Japanese Patent Laid-Open No. 192724/1985). Kaisho 6
0-192725).

On the other hand, Japanese Patent Publication No. 55-482 discloses a polyester fiber composed of a divalent phenol represented by chloridroquinone and methylhydroquinone and an aromatic dicarboxylic acid represented by terephthalic acid.

<Problems to be Solved by the Invention> However, according to the studies by the present inventors, the above Japanese Patent Publication No.
According to the method disclosed as a method for producing a polyester in JP-A 5-482, that is, a method of initiating polymerization under stirring at 300 ° C. or less, a polymer is crystallized during polymerization,
It was found that a homogeneous polymer could not be obtained.

In addition, 4,4'-diphenyldicarboxylic acid is difficult to form a uniform slurry with a diacylated aromatic dihydroxy compound at a temperature of 300 ° C or less, and since the bulk density of 4,4'-diphenyldicarboxylic acid is low, stirring is difficult. It was very difficult.

As a method of solving such a point, a high temperature of 300 ° C. or higher,
For example, it is possible to obtain a uniform slurry by carrying out heat polymerization to 330 to 340 ° C. without stirring and then starting stirring. However, there is a problem that the polymer that is initially polymerized without stirring has a poor color tone.

Further, in order to complete the polycondensation reaction, it is effective to reduce the pressure in the system at the end of the polymerization reaction and distill off acetic acid.
JP-A-60-192724, JP-A-60-192
According to the manufacturing method described in Japanese Patent No. 725, 31
When depressurization is started from a temperature lower than 5 ° C, when 4,4'-diphenyldicarboxylic acid is more than 90 mol% of the total dicarboxylic acid component, it also crystallizes at the time of polymerization and a homogeneous polymer cannot be obtained. It has been found that even if the amount is less than 100%, in many cases, it is not possible to obtain a homogeneous polymer which is crystallized during the polymerization.

It was also found that when the system was depressurized, if the system was gradually depressurized, acetic acid reflexed for a long time, the polymer was cooled and crystallized, and a homogeneous polymer could not be obtained.

Therefore, the present invention provides a polyester using 4,4'-diphenyldicarboxylic acid having a low bulk density as a main component of all dicarboxylic acid components, which suppresses crystallization of a polymer at the time of polymerization and is homogeneous with little coloring. The task is to establish a method by which polymers can be produced.

<Means for Solving the Problems> That is, the present invention provides (1) 30 to 100 mol% of an aromatic dihydroxy compound and acetic anhydride or all dicarboxylic acid components.
In a polycondensation reaction with a dicarboxylic acid (which does not include terephthalic acid) in which is 4,4'-diphenyldicarboxylic acid, the stirring speed is 100 rpm / min at a temperature of 120 ° C or higher and 330 ° C or lower in an inert gas atmosphere. A method for producing a high-modulus aromatic polyester, which comprises a process of performing an acetylation reaction and an initial polycondensation reaction while stirring at a low speed below, (2) a diacylated aromatic dihydroxy compound and a total dicarboxylic acid component 30-100 mol% of
In a polycondensation reaction with a dicarboxylic acid (which does not include terephthalic acid) which is 4′-diphenyldicarboxylic acid, under an inert gas atmosphere at a temperature of 120 ° C. or higher and 330 ° C. or lower,
A process for producing an aromatic polyester having a high elastic modulus, which comprises a process of carrying out an initial polycondensation reaction while stirring at a low stirring speed of 100 rpm or less, and (3).
After performing the acetylation reaction and the initial polycondensation reaction according to claim 2 or the initial polycondensation reaction according to claim (2), further 3
A method for producing a high-modulus aromatic polyester comprising a process of performing a polycondensation under reduced pressure at a temperature of 30 ° C. or higher.

Examples of the aromatic dihydroxy compound used in the present invention include methylhydroquinone, chlorohydroquinone, phenylhydroquinone, t-butylhydroquinone, hydroquinone, 4,4'-dihydroxybiphenyl,
4,4'-dihydroxydiphenyl ether, 2,6-
Preferable are one or more dihydroxy compounds selected from dihydroxynaphthalene and 2,7-dihydroxynaphthalene. Among them, methylhydroquinone,
Chlorhydroquinone, phenylhydroquinone, t-
Butyl hydroquinone, hydroquinone, 4,4'-dihydroxybiphenyl and the like are particularly preferable.

In the method for producing a polyester of the present invention, an aromatic dihydroxy compound is provided for production together with acetic anhydride.

Examples of the diacylated aromatic dihydroxy compound include an ester of an aromatic dihydroxy compound and an aliphatic carboxylic acid such as acetic acid or propionic acid, and an acetylated product is particularly preferable.

The dicarboxylic acid (not including terephthalic acid) used in the method for producing an aromatic polyester of the present invention is 30 to 100 mol% of the total dicarboxylic acid component, preferably 50 to 10 mol%.
It is necessary that 0 mol% is 4,4'-diphenyldicarboxylic acid.

Other preferable examples of the dicarboxylic acid (not containing terephthalic acid) component are 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid and 1,2-bis (phenoxy) ethane-4,4. '-Dicarboxylic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'
-Dicarboxyphenyl ether, isophthalic acid, 2,
Examples thereof include 2'-diphenyldicarboxylic acid, 3,3'-diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, and particularly 1,2-bis- (2-chlorophenoxy) ethane-4,4. ′ -Dicarboxylic acid,
2,6-naphthalenedicarboxylic acid is preferred.

In the method for producing a polyester of the present invention, aromatic hydroxycarboxylic acid, p-aminobenzoic acid, p-phenylenediamine, or an acylated product thereof may be further copolymerized in addition to the diol component and the dicarboxylic acid component. It is possible. Preferable examples of such aromatic hydroxycarboxylic acid include p-hydroxybenzoic acid, m-hydroxybenzoic acid, 2,6-hydroxynaphthoic acid and 3-chloro-4-hydroxybenzoic acid. Examples of the compound include an ester of an aliphatic carboxylic acid such as acetic acid or propionic acid of the aromatic hydroxycarboxylic acid and a hydroxy group,
Among them, p-hydroxybenzoic acid, 3-chloro-4-hydroxybenzoic acid and acylated products thereof are particularly preferable.

According to the production method of the present invention, the following structural units (I), (I) and (II), (I) and (II
A polyester having I) or (I), (II) and (III) is obtained.

(Wherein Ar ₁ is a residue obtained by removing a hydroxyl group or an acyloxy group from an aromatic dihydroxy compound or its diacyl compound, X is a residue obtained by removing a carboxyl group from a dicarboxylic acid, and Ar ₂ is an aromatic group. Group represents a residue obtained by removing a hydroxyl group or an acyloxy group from a group hydroxycarboxylic acid or an acylated product thereof.) The structural unit (I) / [(II) + (II)] is 30 to 1
The amount is 00 mol%, preferably 50 to 100 mol%, more preferably 70 to 100 mol%. If it is less than 30 mol%, the effect of the present invention is small.

The above structural unit (I) / [(I) + (II) + (II
I)] is preferably 20 to 100 mol%, and 3
0 to 100 mol% is more preferable.

The molar ratio of the aromatic dioxy compound constituting the structural unit (I) or (II) to the dicarboxylic acid is usually 1 to 1.2, preferably 1 to 1.1.

The feature of the method for producing a high-modulus aromatic polyester of the present invention is that, as an initial step, the raw material is stirred in an inert gas atmosphere at a temperature of 120 ° C. or higher and 330 ° C. or lower at a stirring speed of 10
The acetylation reaction and the initial polycondensation reaction or the initial polycondensation reaction can be performed by stirring at a low speed of 0 rotations / minute or less, preferably at a low speed of 40 rotations / minute or less, and more preferably at a low speed of 20 rotations / minute or less. It is to include the process of performing, and preferably the process of performing the reduced pressure polycondensation reaction at a temperature of 330 ° C. or higher.

In the production method of the present invention, when an aromatic dihydroxy compound and acetic anhydride and dicarboxylic acid (not containing terephthalic acid) components are used as the starting materials, the initial reaction is mainly the acetylation reaction of the aromatic dihydroxy compound and the starting material. When further using an aromatic hydroxycarboxylic acid,
It is mainly an acetylation reaction of an aromatic dihydroxy compound and an aromatic hydroxycarboxylic acid. Then, after the acetylation reaction, the initial polycondensation reaction is performed.

The acetylation reaction and the initial polycondensation reaction are performed under an inert gas atmosphere at a temperature of 120 ° C. or higher and 330 ° C. or lower at 100 ° C.
There is no particular limitation except that the stirring speed is not more than rotation / minute, and a usual method can be used.

Among them, the acetylation reaction is preferably carried out at a relatively low temperature of 120 to 180 ° C, particularly preferably in the range of 130 to 150 ° C, in order to prevent the initial distillation of acetic anhydride.

In addition, after the acetylation is completed, the temperature is raised to 18
It is preferable to carry out the initial polycondensation reaction at a temperature of 0 to 250 ° C and then at a temperature of 250 to 330 ° C.

When a diacylated aromatic dihydroxy compound and a dicarboxylic acid (free of terephthalic acid) component are used as starting materials, or when an acylated aromatic hydroxycarboxylic acid is further used, an initial polycondensation reaction is carried out. This initial polycondensation reaction is performed under an inert gas atmosphere at 120
There is no particular limitation except that the stirring is carried out at a temperature of not less than 0 ° C. and not more than 330 ° C. and a stirring speed of not more than 100 revolutions / minute, and a usual method can be used. Preferably, the initial polycondensation reaction is from 250 to
It is preferably carried out in the range of 330 ° C.

In either case, the important point is 120 ° C or higher 330
It is to include a process of performing the reaction at a temperature of not more than 0 ° C. under low speed stirring at a stirring speed of 100 rpm or less. If the stirring speed is faster than that, it becomes difficult to make a uniform slurry of 4,4′-diphenyldicarboxylic acid, and some unreacted 4,
The 4'-diphenyldicarboxylic acid remains, which promotes the crystallization of the low polymer produced and is not preferable because a homogeneous polymer having a high degree of polymerization cannot be obtained.

The reaction time for obtaining a uniform slurry is usually 0 to sufficiently slurry 4,4'-diphenyldicarboxylic acid.
It takes about 25 hours or more, and since the slurry formation progresses within 5 hours, it is not always necessary to make it longer than 5 hours.

The reaction for obtaining this uniform slurry is preferably carried out under an atmosphere of an inert gas and at atmospheric pressure. When carried out under reduced pressure, the aromatic dihydroxy compound, aromatic hydroxycarboxylic acid or its acylated product becomes 4,4'-diphenyl. It is not preferable because it sublimates before it reacts with the enyldicarboxylic acid or distills into a distilling circuit.

The uniform slurry thus obtained is subjected to an ordinary polycondensation reaction to form a homogeneous molten polymer having a high degree of polymerization.

This uniform slurry is further heated to 330 ° C. under reduced pressure.
By polymerizing as described above, a homogeneous molten polymer having a higher degree of polymerization is obtained. In this case, the stirring speed is preferably 20 rotations / minute or more. Furthermore, when decompressing the system, low boiling point substances such as acetic acid reflux for a long time,
From the viewpoint of preventing crystallization of the polymer caused by the polymer being cooled significantly, it is preferable to rapidly reduce the pressure from normal pressure to 20 mmHg or less within 15 minutes.

The manufacturing conditions are such that 4,4'-diphenyldicarboxylic acid has a melting point of 400 ° C or higher and an apparent density of 0.35 to 0.
50, which is smaller than 0.70 to 0.80 of terephthalic acid, and is due to the high crystallinity of a polymer mainly composed of 4,4'-diphenyldicarboxylic acid. It seems that it is completely unpredictable from the conventional knowledge that, for example, 4,4′-diphenyldicarboxylic acid is added to 90 mol% of all dicarboxylic acid components by the production method of the present invention.
It is also possible to produce a polyester containing the above.

The present invention will be further described below with reference to examples.

Example 1 229 parts by weight of methylhydroquinone diacetate (1.1
0 mol), 4,4'-diphenyldicarboxylic acid 230 parts by weight (0.95 mol), 2,6-naphthalenedicarboxylic acid 11 parts by weight (0.05 mol) equipped with a helical stirring blade and a distillation pipe. It was charged in a vertical reaction vessel to carry out deacetic acid polymerization.

First, in a nitrogen gas atmosphere, the temperature was raised to 250 ° C., the reaction was started while stirring the monomer at a low stirring speed of 5 revolutions / minute, and the temperature was raised stepwise to 330 ° C. over 1 hour. As a result of continuing the reaction at 330 ° C. for 45 minutes as it was, a homogeneous melt polymer was formed in the system. Thereafter, the temperature was maintained at 330 ° C. and the stirring speed was gradually increased to 22 rpm, and the reaction was continued at this stirring speed for 1.5 hours. After that, 380 ℃
After the temperature was raised stepwise to 380 ° C., the pressure in the system was reduced from atmospheric pressure to 3 mmHg in 15 minutes, and the reaction was continued for another 40 minutes at this vacuum degree to complete polycondensation. As a result, a tough polymer oriented in the form of a cream plate having the following theoretical structural formula was obtained.

When this polymer was placed on a sample stage of a polarizing microscope and the temperature was raised to check the optical anisotropy, good optical anisotropy was shown at 320 ° C. or higher. The melting point of this polymer was measured by DSC-II type manufactured by Perkin Elmer Co., Ltd. and found to be 367 ° C. The melt viscosity of this polymer at 377 ° C. was 980 poise at a shear rate of 1,000 (1 / sec), and a very strong gut was obtained.

Comparative Example 1 The same amount of monomer as in Example 1 was used in the same apparatus,
Deacetic acid polymerization was performed under the following conditions. That is, under a nitrogen gas atmosphere, the temperature was raised to 250 ° C. without stirring and then 33 hours were taken in 1 hour.
The temperature was raised stepwise to 0 ° C. The reaction was continued for another 45 minutes at this temperature without stirring to form a uniform melt in the system, and then stirring was started, after which polycondensation was completed by the same method as in Example 1. As a result, a polymer having the structural formula shown in Example 1 was obtained, but it was strongly colored and brown and colored.

Example 2 229 parts by weight of methylhydroquinone diacetate (1.1
0 mol), 4,4'-diphenyldicarboxylic acid 230 parts by weight (0.95 mol), 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid 19 parts by weight. The same equipment as in No. 1 was charged, and deacetic acid polymerization was carried out under the following conditions.

First, in a nitrogen gas atmosphere, the temperature was raised to 250 ° C., the reaction was started while stirring the monomer at a low stirring speed of 5 revolutions / minute, and the temperature was raised stepwise to 330 ° C. over 1 hour. As a result of continuing the reaction at 330 ° C. for 45 minutes as it was, a homogeneous melt polymer was formed in the system. Then, the temperature was maintained at 330 ° C., the stirring speed was gradually increased to 22 rpm, the reaction was continued for 1.5 hours at this stirring speed, and the temperature was gradually raised to 380 ° C. in a nitrogen gas atmosphere. The reaction was continued for 0 hours. As a result, almost theoretical amount of acetic acid was distilled out, and a polymer having the following theoretical structural formula was obtained.

This polymer was crushed, and solid phase polymerization was performed at 310 ° C. for 10 hours in an inert oven in which nitrogen gas was passed.

When this polymer was placed on a sample stage of a polarization microscope and the temperature was raised to check the optical anisotropy, good optical anisotropy was shown at 321 ° C. or higher. The melting point of this polymer was measured by DSC-II type manufactured by Perkin Elmer Co., Ltd. and found to be 360 ° C. The melt viscosity of this polymer at 370 ° C. was 1800 poise at a shear rate of 1,000 (1 / sec), and a strong gut was obtained.

<Effects of the Invention> By the production method of the present invention, it is possible to stably produce a polyester having excellent fluidity and mechanical properties, which contains 4,4'-diphenyldicarboxylic acid as a main dicarboxylic acid component.

Claims (3)

[Claims] 1. A polycondensation reaction of an aromatic dihydroxy compound, acetic anhydride and a dicarboxylic acid (not including terephthalic acid) in which 30 to 100 mol% of all dicarboxylic acid components are 4,4′-diphenyldicarboxylic acid, A high elastic modulus characterized by including a process of performing an acetylation reaction and an initial polycondensation reaction at a temperature of 120 ° C. or higher and 330 ° C. or lower in an inert gas atmosphere while stirring at a low stirring speed of 100 revolutions / minute or less. Method for producing aromatic polyester. 2. A diacylated aromatic dihydroxy compound and 30 to 100 mol% of all dicarboxylic acid components are 4,4 '.
In a polycondensation reaction with dicarboxylic acid (not including terephthalic acid) which is diphenyldicarboxylic acid, stirring is carried out in an inert gas atmosphere at a temperature of 120 ° C. or higher and 330 ° C. or lower at a low stirring speed of 100 revolutions / minute or less. A process for producing an aromatic polyester having a high elastic modulus, which comprises a process of performing an initial polycondensation reaction. 3. An acetylation reaction and an initial polycondensation reaction according to claim (1) or an initial polycondensation reaction according to claim (2), and then a reduced pressure polycondensation reaction at a temperature of 330 ° C. or higher. A method for producing a high-modulus aromatic polyester, comprising: