JP3024142B2 - Method for producing copolyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention provides a polymer having a high degree of polymerization only by melt polymerization, and is optically anisotropic, heat-resistant and rigid, and impact-resistant which can be molded by a usual molding machine. And a method for producing a copolymerized polyester having excellent mechanical properties.

<Prior art> In recent years, there has been an increasing demand for higher performance of plastics, and a number of polymers having various new properties have been developed. Among them, optically anisotropic liquid crystal polymers have excellent mechanical properties. (JP-A-51-
8395, JP-A-49-72393).

<Problems to be Solved by the Invention> As the above liquid crystal polymer, for example, a liquid crystal polymer obtained by copolymerizing p-hydroxybenzoic acid with polyethylene terephthalate is known (JP-A-49-72393).

However, the injection-molded product of this polymer has a drawback that heat resistance is insufficient or mechanical properties are poor, and an injection-molded product that satisfies both heat resistance and mechanical properties is obtained from this polymer. Can not do. Moreover,
In order to improve heat resistance, the amount of p-hydroxybenzoic acid to be copolymerized must be 80 mol% or more. In this case, solidification occurs during polymerization, and solid-phase polymerization is required.

On the other hand, as a means for improving the flowability of such a polymer to improve the melt moldability and further improve the mechanical properties, for example, as described in JP-A-51-8395, polyethylene terephthalate A method of copolymerizing p-acyloxyoxybenzoic acid with a dicarboxylic acid and an aromatic diol has been proposed. In this method as well, the mechanical properties of the injection molded article obtained are improved, but the heat resistance is insufficient. There was a disadvantage.

Further, as described in JP-B-47-474870, a method of copolymerizing p-hydroxybenzoic acid with 4,4'-dihydroxybiphenyl and terephthalic acid is also known, and obtained by this method. Injection molded products of wholly aromatic polyesters have good heat resistance, but have a softening temperature of 400 ° C. or higher, so that melt polymerization is difficult, and their mechanical properties are not sufficiently satisfactory.

In addition, Japanese Patent Application Laid-Open Nos.
In the method described in JP-B-8395, it is necessary to acetylate the hydroxyl group in the starting compound in a separate step in advance, and thus it has been difficult to obtain the polymer at low cost.

Further, a method for synthesizing a polyester using a non-acetylated raw material is disclosed in JP-A-62-41220 and JP-A-62-277.
No. 427 and Japanese Patent Application Laid-Open No. 62-285916, but these methods do not substantially add an aromatic dicarboxylic acid or an aromatic diol, so that any of these methods has low heat resistance. You can only get polymers.

The present invention has been made in view of the above-described circumstances, and uses a non-acetylated monomer as a raw material, and has a good heat resistance, and particularly provides a molded article having excellent uniformity and excellent smoothness in appearance. It is an object to obtain a polyester.

<Means for Solving the Problems> The present inventors have studied to achieve the above objects, and as a result,
The present invention has been reached.

That is, the present invention relates to (A) p-hydroxybenzoic acid, (B) 4,4'-dihydroxydiphenyl, hydroquinone, 2,6-dihydroxynaphthalene, t-butylhydroquinone, 3,3 ', 5,5'- Tetramethyl-4,4'-dihydroxybiphenyl, phenylhydroquinone, 2,2
At least one aromatic dihydroxy compound selected from -bis (4-hydroxyphenyl) propane and bis (4-hydroxyphenyl) sulfone, (C) terephthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6- Naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4 '
One or more aromatic dicarboxylic acids selected from dicarboxylic acids and 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acids, (D) terephthalic acid, 4,4 '
-Diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid and 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid Acetic anhydride is added to a copolyester raw material comprising a polyester powder having a logarithmic viscosity of 0.8 d / g or less and a particle size of 4760 μm or less formed by condensing one or more aromatic dicarboxylic acids selected from acids with an alkylene glycol. By being present, the hydroxyl group of the raw material is acylated and deacetic acid polymerization is performed,
Structural unit (I) consisting of the following structural units (I) to (IV)
And the total of (II) is 60 to 95 mol% based on the total of the structural units (I), (II) and (III), and the structural unit (III)
Is 40 to 5 mol% based on the total of the structural units (I), (II) and (III), and the molar ratio of the structural units (I) and (II) is 75/25 to 95/5. The present invention provides a method for constructing a polymerized polyester.

(However, R ₁ in the formula is R ₂ represents one or more groups selected from And X represents a hydrogen atom or a chlorine atom, and n represents a natural number of 2 to 6. The total of the structural units (II) and (III) and the structural unit (IV) are substantially equimolar. The structural unit (I) is a structural unit generated from (A) p-hydroxybenzoic acid, and the structural unit (II)
Is (B) 4,4'-dihydroxybiphenyl, hydroquinone, 2,6-dihydroxynaphthalene, t-butylhydroquinone, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl, phenylhydroquinone , 2,2
-A structural unit formed from one or more aromatic dihydroxy compounds selected from bis (4-hydroxyphenyl) propane and bis (4-hydroxyphenyl) sulfone.

Further, the structural unit (III) comprises (C) and (D)
Terephthalic acid, which is an aromatic dicarboxylic acid in 4,
4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid and 1,2-bis (2-chlorophenoxy) ethane-4,4 ' -A structural unit formed from one or more aromatic dicarboxylic acids selected from dicarboxylic acids. Of these, R ₁ Is most preferred.

 n is most preferably 2.

On the other hand, among the structural units (I) to (IV), the total of the structural units (I) and (II) is the sum of the structural units (I) and (II).
It is 60 to 95 mol%, preferably 80 to 92 mol%, based on the total of (III) and (III).

In addition, the structural unit (III) includes structural units (I) and (II)
And (III) is 40 to 5 mol%, preferably 20 to 8 mol%.

The total of the structural units (I) and (II) is 95 mol% based on the total of the structural units (I), (II) and (III).
If it exceeds, the melt fluidity decreases and solidifies during polymerization,
If the amount is less than mol%, the obtained copolyester is not preferable because the heat resistance becomes poor.

Furthermore, the molar ratio of the structural units (I) and (II) [(I) /
(II)] is 75/25 to 95/5, preferably 78/22 to 92
/ 8. When the molar ratio of the structural units (I) and (II) is smaller than 75/25 or larger than 95/5, the heat resistance becomes poor or the fluidity becomes poor, so that it is practical. is not.

The particle size of the polyester powder obtained by condensing the aromatic dicarboxylic acid and the alkylene glycol (D) is 4760.
μm or less, preferably 4000 μm or less, more preferably
It is 1680 μm or less and 250 μm or more.

Here, the particle size means a nominal size (μ) of a Japanese Industrial Standard mesh sieve. That is, the polyester powder having a particle size of 4760 μm means a particle passing through a nominal size of 4760 μm of Japanese Industrial Standard mesh sieve.

When the particle size of the ester powder is larger than 4760 μm, the polymerization rate is low, the mechanical properties of the obtained copolyester are insufficient, and the smoothness of the appearance of a molded article made of this copolyester is impaired. Is not preferred.

The amount of these starting materials to be charged may be such that the structural formula of the obtained polymer is in the above-mentioned (I), (II), (III) and (IV) and the copolymerization ratio described above. is necessary.

Theoretically, p-hydroxybenzoic acid and the aromatic dihydroxy compound are charged so that the molar ratio is 75/25 to 95 / 5.However, depending on the reaction conditions, p-hydroxybenzoic acid sublimates, so that aromatic dihydroxy The molar amount is preferably 1.0 to 1.1 times the theoretical amount of the compound.

The molar ratio of the aromatic dicarboxylic acid to be reacted with the aromatic dihydroxy compound forming the structural unit (II) is theoretically equimolar, but depending on the reaction conditions, the aromatic dihydroxy compound sublimates. 1.0 to 1.1 times the molar amount of the aromatic dicarboxylic acid is preferred.

(D) As the polyester powder, a polyester obtained by previously polycondensing an aromatic dicarboxylic acid and an alkylene glycol is used, and the logarithmic viscosity of the polyester is 0.8 d / g or less, preferably 0.5 to 0.8 d / g.

Here, when a polyester exceeding 0.8 d / g is used,
It is difficult to obtain a polymer that gives a molded article having excellent homogeneity and smoothness in appearance, which is an object of the present invention.

The amount of acetic anhydride is based on the hydroxyl group of the starting material.
It is preferably 1.0 to 1.5 times the molar amount, particularly 1.05 to 1.
Preferably it is twice the molar amount.

These starting materials are charged to the reaction system, and are usually maintained at room temperature to 34.
After performing the acetylation reaction and the initial polymerization under normal pressure at a temperature of 0 ° C., preferably 330 ° C. or less, by performing deacetic acid polycondensation at 250 to 340 ° C., preferably 260 to 330 ° C., further under reduced pressure, The copolymerized polyester of the present invention can be obtained. In addition, the reaction under normal pressure is preferably performed in an atmosphere of an inert gas such as nitrogen to suppress the oxidative decomposition reaction.

Although these polycondensation reactions proceed without a catalyst, it is sometimes preferable to add a metal compound such as stannous acetate, tetrabutyl titanate, sodium acetate and potassium acetate, antimony trioxide, and metal magnesium.

Further, the melt viscosity of the copolymerized polyester produced in the present invention is preferably 10 to 15,000 poise, especially 20
More preferably, it is in the range of ~ 5,000 poise.

The melt viscosity produced in the present invention is a value measured by a Koka flow tester at a temperature of (liquid crystal onset temperature + 40 ° C.) at a shear rate of 1,000 (1 / second).

On the other hand, the logarithmic viscosity of this aromatic polyester is 0.1 g / d
The concentration can be measured in pentafluorophenol at 60 ° C., preferably 0.5 to 5.0 d / g, and 1.0 to 3.
It is particularly preferred that it is in the range of 0 d / g.

When the polycondensation of the copolymerized polyester is carried out, in addition to the components constituting the structural units (I) to (IV), isophthalic acid, 3,3'-diphenyldicarboxylic acid, and 2,2'-diphenyldicarboxylic acid Such as aromatic dicarboxylic acids, adipic acid, azelaic acid, sebacic acid, aliphatic dicarboxylic acids such as dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone, methylhydroquinone, 4,4'-dihydroxy Diphenyl sulfone, 4,4'-dihydroxydiphenylpropane, 4,
Aromatic diols such as 4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxybenzophenone, 4,4 'dihydroxydiphenyl ether, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexane Diols, aliphatic and alicyclic diols such as 1,4-cyclohexanedimethanol and m
Aromatic hydroxycarboxylic acids such as -hydroxybenzoic acid and 2,6-hydroxynaphthoic acid can be further copolymerized in a small proportion within the range not to impair the object of the present invention.

The copolymerized polyester of the present invention thus obtained has a high polymerization degree polymer obtained only by melt polymerization, and has a good optical anisotropy,
It exhibits mechanical properties and heat resistance, can be used for ordinary injection molding, and can be injection molded into a three-dimensional molded product.

In addition, glass fiber, carbon fiber, reinforcing materials such as asbestos, fillers, nucleating agents, pigments, antioxidants, stabilizers, plasticizers, lubricants, release agents for the copolymerized polyester obtained by the method of the present invention. , And additives such as flame retardants and other thermoplastic resins can be added to impart desired properties.

In addition, the strength of the injection-molded article thus obtained can be increased by heat treatment, and in many cases, the elastic modulus can also be increased.

This heat treatment causes the molded article to be placed in an inert atmosphere (eg, nitrogen,
The heat treatment can be carried out at a temperature lower than the melting point of the polymer in an atmosphere containing argon, helium or water vapor or an atmosphere containing oxygen (for example, air). This heat treatment may or may not be under tension and can take place in tens of minutes to several days.

The effect in the present invention is that the polymerization degree of the aromatic dicarboxylic acid and the alkylene glycol as the starting materials is low, and since the aromatic dihydroxy compound and the aromatic dicarboxylic acid are added together with p-hydroxybenzoic acid, the block in the resulting polymer It is considered that the expression is caused by the decrease in the property.

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

Example 1 To a test tube for polymerization, 46.62 g of p-hydroxybenzoic acid (3
3.75 × 10 ^-2 mol), 4,4'-dihydroxybiphenyl 8.3
8 g (4.5 × 10 ^-2 mol), acetic anhydride 48.01 g (47.03 × 10 ^-2 mol), terephthalic acid 7.47 g (4.5 × 10 ^-2 mol) and polyethylene terephthalate having an intrinsic viscosity of about 0.60 and a particle system of 710 to 1000 μm 12.97 g (6.75 × 10 ^-2 mol) of the granular material was added to [Structural units (I) and (I)
85 mol% with respect to the total of I) and (III), the molar ratio of the structural units (I) and (II) was 88/12], and deacetic acid polycondensation was carried out under the following conditions. .

First, under nitrogen atmosphere at 100-250 ° C for 5 hours,
After reacting at ~ 330 ° C for 1.5 hours, 0.5mm at 300 ° C for 1 hour
The pressure was reduced to Hg, and the polycondensation reaction was further performed for 2.25 hours to complete the polycondensation. As a result, almost the theoretical amount of acetic acid was distilled out, and a beige polymer was obtained.

Further, 5 batches of polycondensation were carried out under the same conditions as described above, and the polymer was recovered and the polymer was pulverized by a pulverizer manufactured by Hora Co., Ltd.

The theoretical structural formula of this polymer is as follows, and the elemental analysis results of the aromatic polyester showed good agreement with the theoretical values.

Further, this copolymerized polyester was placed on a sample stage of a polarizing microscope, and the temperature was raised to confirm the optical anisotropy. As a result, the liquid crystal onset temperature was 264 ° C., indicating good optical anisotropy.

This copolymerized polyester was supplied to Sumitomo Nestal injection molding machine, Promat 40/25 (manufactured by Sumitomo Heavy Industries, Ltd.), and the cylinder temperature was 300 ° C and the mold temperature was 30 ° C.
Test pieces 8 "thick x 1/2" wide x 5 "long and 1/8" thick x 2 1/2 "long mold notch impact test pieces were prepared.

Using a test piece made of Toyo Baldwin's Tensilon UTM-100, strain rate 1 mm / min, span distance
When the flexural modulus was measured under the condition of 50 mm, it was 10.4 GPa. Izod impact value (mold notch) is 38kg
The value was as high as cm / cm.

Also, using a thermal deformation measuring device manufactured by Toyo Seiki Co., Ltd.
When the heat distortion temperature of an 8 ″ thick specimen was measured, it was 209 ° C.
(18.50 kg / cm ² ).

The logarithmic viscosity of the copolymerized polyester was measured in pentafluorophenol (0.1 g / d concentration, 60 ° C.) to be 1.96 d / g, the melt viscosity was 304 ° C., and the shear rate was 10
The fluidity was extremely good at 910 poises at 00 (1 / second).

Furthermore, using a die having a hole with a diameter of 0.3 mm and a length of 1.0 mm, spinning was performed at 310 ° C, and a fiber having a uniform diameter was obtained, and the tensile strength was extremely good at 8.9 g / d. Met. As a result of observing the obtained fiber under a polarizing microscope, the surface was extremely smooth.

Examples 2 to 4 Polycondensation was carried out by varying the particle size of polyethylene terephthalate used as a raw material as shown in Table 1 and evaluated in the same manner as in Example 1.

All of these showed good results as shown in Table 1.

Comparative Example 1 Deacetic acid polycondensation was carried out under the same conditions as in Example 1, except that the particle size of polyethylene terephthalate used as a raw material was larger than 4760 μm.

The results are as shown in Table 1. Since the time required for homogeneously melting polyethylene terephthalate becomes longer,
250-300 ° C., polymerization time in the above examples of the present invention 4.
75 hours, compared to 1.96 d / g logarithmic viscosity, polymerization time 5.75
Time, logarithmic viscosity 1.38 d / g, polymerization rate is quite slow,
The logarithmic viscosity was also found to be low.

In addition, the molded article of this polymer was poor in luster due to having irregularities on the surface, and was inferior in smoothness as compared with the above-mentioned example, but also had low heat resistance.

Furthermore, when spinning was performed using this polymer in the same manner as in Example 1, only a spun yarn having a non-uniform yarn diameter could be obtained. The tensile strength of this yarn was as low as 6.0 g / d, and it was found that the yarn was broken at a thin portion. When this yarn was observed under a polarizing microscope, many foreign substances were observed.

Comparative Example 2 Deacetic acid polycondensation was performed under the same conditions as in Example 1 except that the logarithmic viscosity of polyethylene terephthalate used as a raw material was changed to 0.85 d / g, and the same evaluation as in Example 1 was performed. It is shown in the table.

The molded article of this polymer was inferior in gloss due to having irregularities on the surface, and was not only inferior in smoothness than that in the above-mentioned embodiment, but also had low heat resistance.

Furthermore, when spinning was performed using this polymer in the same manner as in Example 1, only a spun yarn having a non-uniform yarn diameter could be obtained. The tensile strength of this yarn was as low as 5.7 g / d, and it was found that the yarn was broken at a thin portion. Further, when this yarn was observed under a polarizing microscope, granular foreign matters were observed.

Comparative Example 3 In a test tube for polymerization, 41.43 g of p-hydroxybenzoic acid (0.4%) was added.
30mol), logarithmic viscosity is about 0.6d / g, particle size 710 ~ 1000μm
38.43 g (0.20 mol) of polyethylene terephthalate powder and 33.68 g (0.33 mol) of acetic anhydride were subjected to polycondensation in the same manner as in Example 1, followed by injection molding.

As shown in Table 1, this molded article had remarkably poor surface gloss and smoothness, and had a significantly lower heat deformation temperature than that of the above examples.

Furthermore, when spinning was performed using this polymer in the same manner as in Example 1, only a spun yarn having a non-uniform yarn diameter could be obtained. In addition, when this yarn was observed under a polarizing microscope, a large number of granular foreign substances were observed, and the tensile strength of the yarn was also 1.
The value was less than 0 g / d, which was extremely low as compared with the above example.

Examples 5 to 15 In a test tube for polymerization, p-hydroxybenzoic acid (A), 4,
4'-dihydroxybiphenyl (B-1), hydroquinone (B-2), 2,6-dihydroxynaphthalene (B-
3), t-butylhydroquinone (B-4), phenylhydroquinone (B-5), 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl (B-6), 2,2 −
Bis (4-hydroxyphenyl) propane (B-7),
Bis (4-hydroxyphenyl) sulfone (B-8),
Terephthalic acid (C-1), 4,4'-diphenyldicarboxylic acid (C-2), 1,2-bis (phenoxy) ethane-4,
4'-diphenyldicarboxylic acid, (C-3), 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid (C-4), 2,6-naphthalenedicarboxylic acid (C-
5) [However, the components (B-1) to (B-8) and the components (C-1) to (C-5) are charged with the same mole number], and the logarithmic viscosity is 0.60 d /. g, polyethylene terephthalate powder (D) having a particle size of 1000 μm or less and acetic anhydride were charged into a polymerization test tube at a molar ratio shown in Table 2 and polycondensation was carried out under the same conditions as in Example 1. The sum of the structural units (I) and (II) derived from the components (A) to (C) in each of the obtained polymers accounts for the total of the structural units (I), (II) and (III). The ratio was 80 mol%, and the molar ratio of the structural units (I) / (II) was 90/10.

Table 2 shows the results of measuring the liquid crystal onset temperature of each of the obtained polymers and the results of measuring the tensile strength of the yarn obtained by spinning in the same manner as in Example 1.

As is clear from the results in Table 2, a spun yarn having a uniform diameter is obtained from the copolymerized polyester obtained by the method of the present invention, and the spun yarn has a high tensile strength.

<Effects of the Invention> As described above, according to the method for producing a copolymerized polyester of the present invention, it is possible to obtain a molded article having excellent surface gloss and smoothness, and a yarn having a uniform diameter. A copolyester having heat resistance can be produced.

Claims (1)

(57) [Claims] (A) p-hydroxybenzoic acid, (B) 4,4'-dihydroxybiphenyl, hydroquinone, 2,6-dihydroxynaphthalene, t-butylhydroquinone, 3,3 ', 5,5'-tetra Methyl-4,4'-dihydroxybiphenyl, phenylhydroquinone, 2,2-bis (4-hydroxyphenyl) propane and bis (4
(C) terephthalic acid, 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane At least one aromatic dicarboxylic acid selected from -4,4'-dicarboxylic acid and 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid; and (D) terephthalic acid, 4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'-dicarboxylic acid and 1,2-bis (2-chlorophenoxy) ethane-4,4 ' -Logarithmic viscosity 0.8 d / g or less formed by condensation of one or more aromatic dicarboxylic acids selected from dicarboxylic acids and alkylene glycol,
In addition, the presence of acetic anhydride in a copolymerized polyester raw material comprising a polyester powder having a particle size of 4760 μm or less causes acylation of a hydroxyl group of the raw material and polymerization by deacetic acid. ) To (IV), wherein the structural units (I) and (I)
The total of I) is 60 to 95 mol% based on the total of structural units (I), (II) and (III), and the structural unit (III) is the total of structural units (I), (II) and (III). And the molar ratio of the structural units (I) and (II) is 75/25
The structural method of the copolymerized polyester which is about 95/5. (However, R ₁ in the formula is R ₂ represents one or more groups selected from And X represents a hydrogen atom or a chlorine atom, and n represents a natural number of 2 to 6. The total of the structural units (II) and (III) and the structural unit (IV) are substantially equimolar. )