JPH0816153B2 - Method for producing copolyester - Google Patents

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention can be synthesized only by melt polymerization to form a thermotropic liquid crystal, is easy to mold,
In addition, the present invention relates to a method for producing a copolyester which gives a molded article having good heat resistance.

[0002]

2. Description of the Related Art In recent years, demands for higher performance of plastics have been increasing, and many polymers having various new properties have been developed. Among them, optically anisotropic liquid crystal polymers have excellent mechanical properties. Is attracting attention.

As this liquid crystal polymer, a liquid crystal polymer obtained by copolymerizing para-hydroxybenzoic acid with polyethylene terephthalate is known (Japanese Patent Laid-Open No. 723939/49). However, this polymer has drawbacks such as insufficient heat resistance and poor mechanical properties, and it has been found that a molded product satisfying both properties cannot be obtained from this polymer.

[0004]

However, in the conventional production method, the randomness of the structural units in the polymer chain is insufficient, resulting in insufficient homogeneity of the obtained molded article, and sufficient heat resistance. There wasn't.

That is, the ethylene terephthalate units do not randomly copolymerize with the oxybenzoyl units, but the ethylene terephthalate units are blocked and polymerized, resulting in poor homogeneity of the molded article and heat resistance. It is considered to have decreased.

Accordingly, it is an object of the present invention to provide a method for producing a homogenous and excellent heat resistant copolymerized polyester in which oxybenzoyl units are randomly copolymerized with the polyester.

[0007]

Means for Solving the Problems That is, the present invention is (1)
In the method for producing a copolyester comprising the following structural units (I), (II) and (III), (a) para-hydroxybenzoic acid and acetic anhydride or (b) para-acetoxybenzoic acid are continuously or dividedly added. A method for producing a copolyester characterized by:

Embedded image (In the formula, R ₁ represents an alkylene group, R ₂ represents a divalent aromatic group, and the copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II)] (molar ratio)) is 0.6 to 0.9, and the structural units (II) and (III) are substantially equimolar. (2) In the method for producing a copolymerized polyester comprising the following structural units (I), (II) and (III), the copolymerization ratio of the structural unit (I) ((I) / [(I) + (II )]
(Molar ratio)) is 0 <(I) / [(I) + (II)] <0.
A method for producing a copolyester, comprising adding (a) parahydroxybenzoic acid and acetic anhydride or (b) paraacetoxybenzoic acid to a polymer having a copolymerization ratio of 6.

[0008]

[Chemical 4] (Wherein R ₁ and R ₂ represent a divalent aromatic group and / or an alkylene group, and the copolymerization ratio of the structural unit (I) ((I) / [(I) + (II)] (molar ratio )) Is from 0.6
0.9, and the structural units (II) and (III) are substantially equimolar. ) The copolyester produced in the present invention has the structural units (I) and (II).

R ₁ is an alkylene group, R ₂ is a divalent aromatic group, and R ₁ is, for example,

Embedded image And R ₂ is, for example,

[Chemical 6] (Wherein X represents a hydrogen atom or a chlorine atom). It is also possible to use two or more of these in combination.

Above all, as R ₁

[Chemical 7] Is preferred.

As R ₂ ,

Embedded image Are preferred (however, X represents a hydrogen atom or a chlorine atom in the formula).

The copolyester produced by the present invention is
A paraoxybenzoyl unit (structural unit (I)) having the above structure, a unit consisting of an aliphatic diol (structural unit (II)) and a unit consisting of an aromatic dicarboxylic acid (structural unit (III)), The copolymerization ratio ((I) / [(I) + (II)] (molar ratio)) of the unit (I) is 0.6 to
The copolymer is 0.9, preferably 0.7 to 0.85.

The greatest feature of the present invention is that in the polymer chain of a polymer produced by continuously or dividedly adding parahydroxybenzoic acid and acetic anhydride, which are raw materials of a paraoxybenzoyl unit, when producing the above-mentioned copolyester. To increase the randomness of the structural unit. As a result, the homogeneity of the molded product can be increased and the heat resistance can be improved.

The method of polycondensing the copolyester comprising the structural units (I), (II) and (III) in the present invention is not particularly limited, except that parahydroxybenzoic acid and acetic anhydride are added continuously or in divided portions. Conventional methods can be used.

The continuous addition is carried out by mixing para-hydroxybenzoic acid and acetic anhydride to form a slurry and continuously adding them at a constant rate with a kneader, or by continuously adding para-acetoxybenzoic acid by a powder or a melt feeder. How to do it.

In continuous addition, the time required for addition is usually 15 minutes to 8 hours. It is preferable to continuously add at a constant rate for 30 minutes to 5 hours.

The divided addition is usually carried out by preliminarily reacting the charged components at the start of the reaction at 240 ° C. to 330 ° C., and then adding 100 to 150 when adding parahydroxybenzoic acid and acetic anhydride.
The temperature is lowered to ℃ and added through a charging port provided on the upper part of the reaction vessel. If paraacetoxybenzoic acid is added, it is 24
Add in powder or melt feeder at 0-330 ° C. There is no limitation on the number of divided additions, but it is usually sufficient to divide into two. 20-80% of the total amount of addition is usually appropriate.

The total amount of para-hydroxybenzoic acid and para-acetoxybenzoic acid to be added continuously or dividedly is 0.6 to 0.9 (mole) based on the total amount of para-hydroxybenzoic acid and para-acetoxybenzoic acid and dicarboxylic acid. Ratio), and 0.7 to 0.85 (molar ratio) is preferable.

In the present invention, the structural units (I) and (I
I) and (III) and the copolymerization ratio (molar ratio) of the structural unit (I) is 0 <(I) / [(I) + (II)] <0.
The effect of the present invention can also be obtained by adding (a) parahydroxybenzoic acid and acetic anhydride or (b) paraacetoxybenzoic acid to the polymer of No. 6. Among them, the polymer is preferably a polymer produced by using parahydroxybenzoic acid and acetic anhydride, and (b) paraacetoxybenzoic acid is preferably added. In this case, the amount of (a) parahydroxybenzoic acid or (b) paraacetoxybenzoic acid added is such that the total amount of paraoxybenzoyl units and parahydroxybenzoic acid in the polymer as the starting material produces paraoxybenzoyl units and dicarboxylic acid in the polymer. The amount added is 0.6 to 0.9 (molar ratio), preferably 0.7 to 0.85 (molar ratio), based on the total amount of the acid.

In addition, in the method of adding (a) or (b) to this polymer, the method of adding para-hydroxybenzoic acid and acetic anhydride may be continuous or divided addition.

When para-hydroxybenzoic acid and acetic anhydride are used, the total number of moles of acetic anhydride added is 1.0 to 1.5 times the total number of moles of para-hydroxybenzoic acid used.
05 to 1.20 times is preferable.

The reaction in the production method of the present invention is
Although it proceeds without catalyst, stannous acetate, zinc acetate, antimony acetate, tetrabutyl titanate, sodium acetate,
In some cases, it may be preferable to add a metal compound such as potassium acetate or metal magnesium.

The melt viscosity of the copolyester of the present invention is preferably 10 to 15,000 poise, and particularly 20.
˜5,000 poise is more preferred.

The melt viscosity is (liquid crystal starting temperature +4
It is a value measured by a Koka type flow tester under the condition of a shear rate of 1,000 (1 / sec) at 0 ° C.

The production method of the present invention is to obtain a polymer having a high degree of polymerization only by the melt polymerization method, and the polymer produced thereby exhibits good optical anisotropy, mechanical properties and heat resistance, It can be subjected to usual melt molding such as extrusion molding, injection molding and blow molding, and can be processed into fibers, films, three-dimensional molded products, containers, hoses and the like.

The molded product thus obtained is
The heat treatment can increase the strength and, in some cases, the elastic modulus. This heat treatment
It can be carried out by heat-treating the molded article in an inert atmosphere (for example, nitrogen, argon, helium, or steam) or an oxygen atmosphere (for example, air) at a temperature below the melting point of the polymer. This heat treatment may or may not be under tension and can take place in tens of minutes to several days.

With respect to the copolyester produced in the present invention, a reinforcing agent such as glass fiber, carbon fiber or asbestos,
Additives such as fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, release agents and flame retardants and other thermoplastic resins can be added to impart desired properties. .

[0028]

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

EXAMPLE 1 Parahydroxybenzoic acid (I), 16.57 g (0.120 mol), and ground polyethylene terephthalate having an intrinsic viscosity of about 0.60 were placed in a polymerization test tube equipped with a stirrer and a motor. (II) 15.37 g (0.080 mol) and acetic anhydride (III) 13.48 g (0.132 mol) were charged, and the temperature was raised from 130 ° C. to 260 ° C. over 3 hours under a nitrogen gas atmosphere. During this period, 13.0 ml of acetic acid was distilled off. Then, the temperature was lowered to 130 ° C. over 30 minutes, and at this temperature, 27.62 g (0.
200 mol), 22.46 g (0.22) of acetic anhydride (III)
0 mol) was added (the charge and the split addition were combined (I)).
/ (II) = 80/20).

Next, from 130 ° C to 310 ° C for 4 hours 30
The temperature is raised over a minute, and the pressure is reduced to 0.5 mmHg in the next hour.
Polymerization was carried out for 45 minutes to complete the reaction.

The polyester was placed on a sample stand of a polarizing microscope and the temperature was raised to confirm the optical anisotropy. As a result, the liquid crystal starting temperature was 278 ° C., indicating good optical anisotropy.

This polyester is manufactured by Sumitomo Nestal injection molding machine Promat 40/25 (Sumitomo Heavy Industries, Ltd.)
Manufactured), cylinder temperature 330 ℃, mold temperature 30 ℃
Under the conditions, a test piece of 1/8 "thickness x 1/2" width x 5 "length was prepared.

The surface smoothness of this molded product was good, and the heat distortion temperature was measured using a heat distortion temperature device manufactured by Toyo Seiki Co., Ltd. and found to be 150 ° C. (18.50 kg / cm ² ).
The melt viscosity of this polymer is (liquid crystal start temperature +40
℃), shear rate 1,000 (1 / sec), measured 770
Poise and fluidity were very good.

The logarithmic viscosity of this polymer (0.1 g /
dl concentration, measured in pentafluorophenol at 60 ° C)
Was 1.32 dl / g.

On the other hand, in the system in which the split addition was not performed (Comparative Example 1), the surface smoothness of the molded product was poor, the fluidity of the molded product when melted at 145 ° C. was poor, and the heat distortion temperature was low. .

Comparative Example 1 Parahydroxybenzoic acid (I) 44.2 was added to a polymerization test tube.
0g (0.320 mol), 15.37 g (0.0) of ground polyethylene terephthalate (II) with an intrinsic viscosity of about 0.6
80 mol), 35.94 g of acetic anhydride (III) (0.352
Mole) and charge from 130 ° C to 310 ° C for 4 hours 30
The temperature is raised over a minute, and the pressure is reduced to 0.5 mmHg in the next hour.
It was polymerized for 45 minutes.

The liquid crystal starting temperature of this polymer was 287 ° C., the surface smoothness of the molded product obtained by injection molding in the same manner as in Example 1 was poor, and the heat distortion temperature was 145 ° C. The melt viscosity of this polymer is 1,000 poise,
The logarithmic viscosity was 1.210 dl / g.

Example 2 Paraacetoxybenzoic acid (I-2) 2 was added to a test tube for polymerization.
1.62 g (0.120 mol), pulverized polyethylene terephthalate (II-1) 15.37 with an intrinsic viscosity of about 0.6
g (0.080 mol), and under a nitrogen gas atmosphere, 2
The temperature was maintained at 50 ° C for 1 hour, 36.03 g (0.200 mol) of paraacetoxybenzoic acid (I-2) was added at this temperature, and the temperature was raised from 250 ° C to 310 ° C over 2 hours and 30 minutes. The pressure was reduced to 0.5 mmHg in 1 hour, and polymerization was performed for 70 minutes to obtain a polyester having a liquid crystal starting temperature of 280 ° C.

This polyester was molded under the same molding conditions as in Example 1 to obtain a molded product having a smooth surface. The heat distortion temperature of the obtained molded product was measured and found to be 152 ° C.
The melt viscosity of this polymer was 690 poise. Also,
The logarithmic viscosity of this polymer was 1.28 dl / g.

Comparative Example 2 Paraacetoxybenzoic acid (I-2) 5 was added to a polymerization test tube.
7.65 g (0.320 mol), ground polyethylene terephthalate (II-1) 15.37 with an intrinsic viscosity of about 0.6
g (0.080 mol) was charged, the temperature was raised from 250 ° C to 310 ° C over 2 hours and 30 minutes, and then 0.5 mmHg in the next 1 hour.
The pressure was reduced to 70 minutes, and polymerization was performed for 70 minutes. The surface smoothness of the molded product obtained by injection molding was poor, the liquid crystal starting temperature of this polymer was 290 ° C., and the heat distortion temperature measured in the same manner as in Example 1 was 146 ° C. The melt viscosity of this polymer is 81
It was 0 poise and the logarithmic viscosity was 1.15 dl / g.

Example 3 Parahydroxybenzoic acid (I), 16.
57 g (0.120 mol), 15.37 g of ground polyethylene terephthalate (II) with an intrinsic viscosity of about 0.60
(0.080 mol) and acetic anhydride (III) 13.48 g
(0.132 mol) was charged, and 13
The temperature was raised from 0 ° C to 260 ° C over 3 hours. During this time 1
3.0 ml of acetic acid was distilled off. After that, it takes 13 minutes for 13
The temperature was lowered to 0 ° C., and at this temperature, 27.62 g (0.200 mol) of parahydroxybenzoic acid (I) and acetic anhydride (II
I. 22.46 g (0.220 mol of slurry was added continuously from the powder addition device attached to the upper part of the polymerization test tube at a constant speed over about 1 hour (mixing and split addition (I ) / (II) = 80/20).

Next, from 130 ° C. to 310 ° C. for 4 hours 30
The temperature is raised over a minute, and the pressure is reduced to 0.5 mmHg in the next hour. 4
Polymerization was carried out for 0 minutes to obtain a polyester having a liquid crystal starting temperature of 278 ° C.

This polyester was molded under the same molding conditions as in Example 1 to obtain a molded product having a smooth surface. The heat distortion temperature of the obtained molded product was measured and found to be 152 ° C.
The melt viscosity of this polymer was 700 poise. Also,
The logarithmic viscosity of this polymer was 1.35 dl / g.

Reference Example 1 Paraacetoxybenzoic acid (I-2) 2 was added to a polymerization tester.
1.62 g (0.120 mol), pulverized polyethylene terephthalate (II-1) 15.37 with an intrinsic viscosity of about 0.6
g (0.080 mol) was charged, the temperature was raised to 250 to 275 ° C. over 2 hours, the pressure was reduced to 0.5 mmHg in the next 1 hour, and polymerization was performed for 60 minutes. The liquid crystal starting temperature of the obtained polymer was 170 ° C., and the heat distortion temperature of the molded product obtained by performing injection molding in the same manner as in Example 1 was 72 ° C.

This polyester was crushed with a crusher manufactured by Toho Co., Ltd. and used in Example 4.

Example 4 In a polymerization test tube, 34.17 g of the pulverized polymer of Reference Example 1 was kept at 250 ° C. for 30 minutes to be melted, and then 7.62 g (0.200 mol) of p-acetoxybenzoic acid was added. Then 2
The temperature was raised from 50 ° C. to 300 ° C. over 2 hours and 30 minutes, the pressure was reduced to 0.5 mmHg in the next 1 hour, and polymerization was performed for 100 minutes.

The liquid crystal starting temperature of this polymer was 275 ° C., and the heat distortion temperature of the molded product obtained by injection molding as in Example 1 was 148 ° C. The melt viscosity is 98
It was 0 poise, both heat resistance and fluidity were excellent, and the surface smoothness of the molded product was good, which was superior to Comparative Example 1.

Example 5 Parahydroxybenzoic acid (I-1), 1 was added to a polymerization test tube.
6.57 g (0.120 mol), intrinsic viscosity about 0.60
Crushed polyethylene terephthalate (II-1) 15.3
7 g (0.080 mol) and acetic anhydride (IV) 13.4
8 g (0.132 mol) was charged and the temperature was raised from 130 ° C. to 260 ° C. over 3 hours under a nitrogen gas atmosphere. During this period, 13.0 m 2 of acetic acid was distilled out. Then, the temperature was lowered to 130 ° C. over 30 minutes, and at this temperature, 27.62 g (0.200 mol) of parahydroxybenzoic acid (I-1) and 22.46 g (0.220 mol) of acetic anhydride (IV) were slurried. Then, the powder was continuously added at a constant rate for about 1 hour from a powder addition device attached to the upper part of the polymerization test tube ((I) / (II) = 80/20 for both charging and divided addition).

Next, from 130 ° C. to 310 ° C. for 4 hours 30
The temperature is raised over a minute, and the pressure is reduced to 0.5 mmHg in the next hour.
Polymerization was carried out for 40 minutes to obtain polyester having a liquid crystal starting temperature of 278 ° C.

This polyester was molded under the same molding conditions as in Example 1 to obtain a molded product having a smooth surface. The heat distortion temperature of the obtained molded product was measured and found to be 152 ° C.
The melt viscosity of this polymer was 700 poise. Also,
The logarithmic viscosity of this polymer was 1.35 dl / g.

[0051]

By the production method of the present invention, it is possible to produce a copolyester having improved heat resistance, fluidity and surface smoothness.

Claims (2)

[Claims] 1. The following structural units (I), (II) and (III)
In the method for producing a copolyester consisting of
(A) Parahydroxybenzoic acid and acetic anhydride or (b)
A method for producing a copolyester, which comprises adding paraacetoxybenzoic acid continuously or in portions. Embedded image (In the formula, R ₁ represents an alkylene group, R ₂ represents a divalent aromatic group, and the copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II)] (molar ratio)) is 0.6 to 0.9, and the structural units (II) and (III) are substantially equimolar. ) 2. The following structural units (I), (II) and (III)
In the method for producing a copolyester consisting of
Copolymerization ratio of structural unit (I) ((I) / [(I) + (I
I)] (molar ratio)) is 0 <(I) / [(I) + (II)]
A method for producing a copolyester, comprising adding (a) parahydroxybenzoic acid and acetic anhydride or (b) paraacetoxybenzoic acid to a polymer having a copolymerization ratio satisfying <0.6. Embedded image (In the formula, R ₁ represents an alkylene group, R ₂ represents a divalent aromatic group, and the copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II)] (molar ratio)) is 0.6 to 0.9, and the structural units (II) and (III) are substantially equimolar. )