JPH0813884B2 - Method for producing copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is a copolymerization that can be synthesized only by melt polymerization to form a thermotropic liquid crystal, which is easy to mold and has good heat resistance. The present invention relates to a method for producing polyester.

<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. Among them, optically anisotropic liquid crystal polymers have excellent mechanical properties. Is attracting attention.

As this liquid crystal polymer, a liquid crystal polymer in which polyethylene terephthalate is copolymerized with parahydroxybenzoic acid is known (Japanese Patent Laid-Open No. 723939/1974). 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.

<Problems to be Solved by the Invention> However, in the conventional manufacturing method, the homogeneity and heat resistance of the molded product were not always sufficient.

That is, it is considered that the paraoxybenzoyl units are not copolymerized at random but are polymerized in a blocked state, resulting in poor homogeneity of the molded article and reduced heat resistance.

Therefore, it is an object of the present invention to provide a method for producing a homogeneous and heat-resistant copolymerized polyester in which paraoxybenzoyl units are randomly copolymerized.

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

O—R ₁ —O (II) O—R ₂ —O (III) OC—R ₃ —CO (IV) (wherein R ₁ and R ₃ are divalent aromatic groups, R ₂ is an alkylene group) The copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II) + (III)] (molar ratio)) is 0.6 to 0.9
Is. In addition, structural units [(II) + (III)] and (IV)
Are substantially equimolar. (2) The following structural units (I), (II), (III) and (I
In the method for producing a copolymerized polyester comprising V), the copolymerization ratio of the structural unit (I) ((I) / [(I) + (I
I) + (III)] (molar ratio)) is 0 <(I) / [(I) +
(II) + (III)] <0.6 to a polymer having a copolymerization ratio of (a) parahydroxybenzoic acid and acetic anhydride, or (b) paraacetoxybenzoic acid. It is a manufacturing method.

O—R ₁ —O (II) O—R ₂ —O (III) OC—R ₃ —CO (IV) (wherein R ₁ and R ₃ are divalent aromatic groups, R ₂ is an alkylene group) The copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II) + (III)] (molar ratio)) is 0.6 to 0.9
Is. In addition, structural units [(II) + (III)] and (IV)
Are substantially equimolar. ) The copolyester produced by the present invention has the above (I) to
It has a structural unit of (IV).

R ₁ and R ₃ are divalent aromatic groups, and R ₁ is, for example, However, examples of R ₂ include CH ₂ n (2 ≦ n ≦ 6). On the other hand, as R ₃ Is mentioned.

Above all, preferred as R ₁ is And especially R ₂ is CH _{2 2} , R ₁ is The combination with is preferred.

Especially as R ₃ Is preferred.

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

Further, in the present invention, the ratio of the structural units (II) and (III) is not particularly limited, but [(I) / (II)] (molar ratio) is 78/22 to 93/7 and [(III) / [ (I) + (II)
+ (III)] (molar ratio) is preferably 2/8 to 0.5 / 9.5.

The greatest feature of the present invention is that parahydroxybenzoic acid or paraacetoxybenzoic acid, which is a raw material of the paraoxybenzoyl unit in the production of the above-mentioned copolyester, is continuously or dividedly added to the polymer chain of the polymer. To increase the randomness of structural units. As a result, the homogeneity of the molded product can be increased and the heat resistance can be improved. However, when parahydroxybenzoic acid is used as the raw material for the paraoxybenzoyl unit, it is necessary to use it together with acetic anhydride.

The method of polycondensing the copolyester comprising the structural units (I) to (IV) in the present invention is carried out by adding (a) parahydroxybenzoic acid and acetic anhydride or (b) paraacetoxybenzoic acid continuously or in divided addition. There is no particular limitation, and a usual method can be used.

In the present invention, (a) para-hydroxybenzoic acid and acetic anhydride or (b) para-acetoxybenzoic acid must be added continuously or in portions.

The continuous addition is usually performed as follows. (A) Paraacetoxybenzoic acid and acetic anhydride are mixed to form a slurry, which is continuously added by a kneader at a constant rate. For (b) paraacetoxybenzoic acid, 240 ° C to 330 ° C
In the above, the powder or the melt supply device provided in the reaction vessel is continuously added at a constant rate.

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.

Split addition is usually done by adding the ingredients at the start of the reaction at 240 ° C.
After pre-reacting at ~ 330 ° C, (a) para-hydroxybenzoic acid and acetic anhydride were cooled to 100-150 ° C, and (b) para-acetoxybenzoic acid was prepared at 240-330 ° C at the top of the reaction vessel. Add from the charging port. 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.

For continuous or divided addition, (a) para-hydroxybenzoic acid and acetic anhydride are added, or (b) para-acetoxybenzoic acid is added, but (a) and (b) are used together during the addition. Also has the same effect. For example, in the case of divided addition, even if (a), then (b), or further (a) is added in a divided manner, the homogeneity of the molded article,
A great effect can be obtained in improving heat resistance.

The total amount of parahydroxybenzoic acid or paraacetoxybenzoic acid to be added continuously or dividedly is 0.6 to 0.9 (molar ratio) with respect to the total of parahydroxybenzoic acid, paraacetoxybenzoic acid and dicarboxylic acid, and 0.7 to 0.85 (molar ratio) is preferable.

In the present invention, the structural units (I) to (IV) are included, and the copolymerization ratio (molar ratio) of the structural units (I) is 0 <
The present invention can also be achieved by adding (a) parahydroxybenzoic acid and acetic anhydride or (b) paraacetoxybenzoic acid to a polymer having (I) / [(I) + (II) + (III)] <0.6. The effect of is obtained. In this case, the total amount of (a) parahydroxybenzoic acid or (b) paraacetoxybenzoic acid added is the total amount of paraoxybenzoyl units and parahydroxybenzoic acid or paraacetoxybenzoic acid added in the polymer as the starting material. Based on the total amount of paraoxybenzoyl units and dicarboxylic acid in the polymer, 0.6 to 0.9 (molar ratio), preferably 0.7 to 0.85
(Molar ratio).

In addition, in this divided addition method, the addition method of adding (a) para-hydroxybenzoic acid and acetic anhydride or (b) para-acetoxybenzoic acid may be added all at once, or may be added continuously or in addition. Good. In order to enhance the randomness of the polymer, it is preferable to add the polymer continuously or in portions.

When (a) para-hydroxybenzoic acid and acetic anhydride are used, the total number of moles of acetic anhydride added is 1.0 to 1.5 times, preferably 1.05 to 1.20 times the total number of moles of structural unit (I).

Further, the reaction in the production method of the present invention proceeds without catalyst, but stannous acetate, zinc acetate, antimony acetate,
In some cases, it may be preferable to add metal compounds such as tetrabutyl titanate, sodium acetate, potassium acetate, and magnesium metal.

Further, the melt viscosity of the copolyester of the present invention is 10 ~
15,000 poise is preferable, and 20 to 5,000 poise is particularly preferable.

The melt viscosity is a value measured by a Koka type flow tester under the condition of (liquid crystal starting temperature + 40 ° C) and shear rate of 1,000 (1 / sec).

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, and extrusion molding, It can be subjected to ordinary melt molding such as 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 can be increased in strength and also in elastic modulus by heat treatment. This heat treatment can be performed 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,
It can be done in a few tens of minutes to a few days.

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

<Examples> Hereinafter, the present invention will be further described with reference to Examples.

Example 1 Test tube for polymerization equipped with a stirrer and a motor Parahydroxybenzoic acid (I-1) 27.62 g (0.200 mol), 4,
4'-diacetoxybiphenyl (II-2) 10.81 g (0.040
Mol), 6.65 g (0.40 mol) of terephthalic acid (III) and polyethylene terephthalate (II-
1) 11.53 g (0.060 mol), acetic anhydride (IV) 22.46 g (0.2
(20 mol), and under a nitrogen gas atmosphere from 130 ° C to 260 ° C
Up to 3 hours. After that, 130 ℃ over 30 minutes
The temperature was lowered to, and parahydroxybenzoic acid (I-
1) 13.81 g (0.100 mol), acetic anhydride (III) 11.23 g (0.
110 mol) was added.

Next, the temperature was raised from 130 ° C. to 300 ° C. over 4 hours and 30 minutes, the pressure was reduced to 0.5 mmHg in the next 1 hour, and polymerization was performed for 60 minutes to complete the reaction.

The polyester was placed on the sample stage of a polarizing microscope and the temperature was raised to check the optical anisotropy.
The temperature was 278 ° C., indicating good optical anisotropy.

This polyester is used for Sumitomo Nestal injection molding machine, Promat 40/25 (Sumitomo Heavy Industries, Ltd.), 1/8 "thickness x 1/2" under the conditions of cylinder temperature 330 ° C and mold temperature 30 ° C.
A width x 5 "long test piece was created.

The surface smoothness of this molded product is good, and when the heat distortion temperature was measured using a Toyo Seiki heat distortion temperature device,
It was 210 ° C. (18.50 kg / cm ² ). The melt viscosity of this polymer is (liquid crystal starting temperature + 40 ° C) and the shear rate is 1,000 (1 /
The porosity was 330 poises and the fluidity was extremely good.

In addition, the logarithmic viscosity of this polymer (0.1 g / dl concentration, measured in pentafluorophenol at 60 ° C.) was 1.82 dl / g.

Example 2 Paraacetoxybenzoic acid (I-2) 3 was added to a polymerization test tube.
6.03 g (0.200 mol), 4,4'-diacetoxybiphenyl (II-2) 10.81 g (0.040 mol), terephthalic acid (III)
6.65 g (0.040 mol) and 11.53 g (0.060 mol) of polyethylene terephthalate (II-1) having an intrinsic viscosity of about 0.6 were charged, and deacetic acid polymerization was carried out under the following conditions.

First, keep it in a nitrogen gas atmosphere at 250 ° C. for 1 hour, add 18.01 g (0.100 mol) of paraacetoxybenzoic acid at this temperature, raise the temperature from 250 ° C. to 300 ° C. in 2 hours and 30 minutes, and then
The pressure was reduced to 0.5 mmHg over time, and polymerization was performed for 90 minutes to complete the reaction.

The liquid crystal starting temperature of the obtained polymer was 279 ° C., injection molding was carried out in the same manner as in Example 1, the surface smoothness of the obtained molded product was good, and the heat distortion temperature was 211 ° C. The melt viscosity of the polymer is 220 poise, and the logarithmic viscosity is
It was 1.75 dl / g.

Comparative Example 1 Parahydroxybenzoic acid (I-1) 4 was added to a polymerization test tube.
1.4g (0.300mol), 4,4'-diacetoxybiphenyl (II-2) 10.81g (0.040mol), terephthalic acid (III)
6.65 g (0.040 mol) Polyethylene terephthalate (II-1) with an intrinsic viscosity of about 0.61 11.53 g (0.060 mol) and acetic anhydride (IV) 33.69 g (0.330 mol) were charged, and 130 ° C to 330
The temperature is raised to ℃ over 5 hours and 30 minutes, then 0.5mmHg in the next 1 hour.
The pressure was reduced to 60 minutes, and polymerization was performed for 60 minutes. The liquid crystal starting temperature of the obtained polymer was 273 ° C., and the heat distortion temperature of the molded product obtained by performing injection molding in the same manner as in Example 1 was 205 ° C. The melt viscosity is 430 poise and the logarithmic viscosity is 1.7.
It was 5 dl / g.

Reference Example 1 A polymerization test tube was charged with paraacetoxybenzoic acid (I-2) 3.
6.03 g (0.200 mol), 4,4'-diacetoxybiphenyl (II-2) 10.81 g (0.04 mol), terephthalic acid (III)
Charge 6.65 g (0.04 mol) and pulverized polyethylene terephthalate (II-1) 11.53 g (0.060 mol) with an intrinsic viscosity of about 0.6 and raise the temperature from 250 ° C to 275 ° C over 2 hours.
The pressure was reduced to 0.5 mmHg per hour, and the polymerization was performed for 60 minutes. The liquid crystal starting temperature of the obtained polymer was 238 ° C. This polyester was crushed with a crusher manufactured by Toho Co., Ltd. and used in Example 3.

Example 3 In a test tube for polymerization, 250.34.17 g of the ground polymer of Reference Example 1 was added.
After being kept at ℃ for 30 minutes and melted, 18.02 g (0.100 mol) of paraacetoxybenzoic acid (I-2) was added, and from 250 ℃
The temperature is raised to 300 ° C over 2 hours and 30 minutes, then 0.5 mm in the next 1 hour.
The pressure was reduced to Hg, and polymerization was performed for 100 minutes. The liquid crystal starting temperature of this polymer was 278 ° C., and the heat distortion temperature of the molded product obtained by injection molding as in Example 1 was 210 ° C. The melt viscosity is 300 poise and the logarithmic viscosity is 1.81 dl / g.
Both heat resistance and fluidity were excellent, and the surface smoothness of the molded product was good.

EXAMPLE 4 Parahydroxybenzoic acid (I-1) 2 was added to a polymerization tester.
7.50 g (0.200 mol), 4,4'-diacetoxybiphenyl (II-2) 10.81 g (0.040 mol), terephthalic acid (III)
Charge 6.65 g (0.040 mol), pulverized polyethylene terephthalate (II-1) 11.53 g (0.060 mol) with an intrinsic viscosity of about 0.60 and 22.47 g (0.220 mol) acetic anhydride (IV) from 130 ° C under nitrogen gas atmosphere. The temperature was raised to 260 ° C. over 3 hours. During this period, 13.0 ml of acetic acid was distilled off. Then, the temperature was raised to 130 ° C. over 30 minutes, and at this temperature, 13.81 g (0.100 mol) of parahydroxybenzoic acid (I-1) and acetic anhydride (IV) 1
1.23 g (0.110 mol) was made into a slurry and continuously added from a powder addition device attached to the upper part of the polymerization test tube to a constant speed over about 1 hour.

Next, the temperature was raised from 130 ° C. to 310 ° C. over 4 hours, the pressure was reduced to 0.5 mmHg in the next 1 hour, and polymerization was performed for 40 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 to be 210 ° C. The melt viscosity of this polymer was 320 poise. The logarithmic viscosity of this polymer was 1.80 dl / g.

<Effects of the Invention> By the production method of the present invention, a uniform copolyester having excellent heat resistance can be produced.

Claims (2)

[Claims] 1. A method for producing a copolyester comprising the following structural units (I), (II), (III) and (IV), wherein (a) parahydroxybenzoic acid and acetic anhydride:
Alternatively, (b) a method for producing a copolyester, which comprises adding paraacetoxybenzoic acid continuously or in portions. O—R ₁ —O (II) O—R ₂ —O (III) OC—R ₃ —CO (IV) (wherein R ₁ and R ₃ are divalent aromatic groups, R ₂ is an alkylene group) The copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II) + (III)] (molar ratio)) is 0.6 to 0.9
Is. The structural units [(II) + (III)] and (IV) are substantially equimolar. ) 2. A method for producing a copolymerized polyester comprising the following structural units (I), (II), (III) and (IV), wherein the copolymerization ratio of the structural unit (I) ((I) / [( I) + (I
I) + (III)] (molar ratio)) is 0 <(I) / [(I) +
(II) + (III)] <0.6 to a polymer having a copolymerization ratio of (a) parahydroxybenzoic acid and acetic anhydride, or (b) paraacetoxybenzoic acid. Production method. O—R ₁ —O (II) O—R ₂ —O (III) OC—R ₃ —CO (IV) (wherein R ₁ and R ₃ are divalent aromatic groups, R ₂ is an alkylene group) The copolymerization ratio of the structural unit (I) ((I) /
[(I) + (II) + (III)] (molar ratio)) is 0.6 to 0.9
Is. In addition, structural units [(II) + (III)] and (IV)
Are substantially equimolar. )