JP2578581B2 - Aromatic polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to mechanical strength, heat resistance,
The present invention relates to a novel aromatic polyester having excellent moldability.

[0002]

2. Description of the Related Art In recent years, polymer materials having excellent mechanical properties such as tensile strength and elastic modulus, heat resistance, and chemical resistance have been demanded. As a polymer material that meets these requirements,
Liquid crystal polyesters and liquid crystal polyesteramides, which are easy to mold and have excellent mechanical properties due to their highly oriented molecules, have attracted attention.

[1] As a liquid crystal polyester, a wholly aromatic polyester is widely known. For example, p-hydroxybenzoic acid homopolymers and copolymers have been produced and are already commercially available. However, these wholly aromatic polyesters have melting points that are too high to be melt-molded, or have high melt viscosities and are difficult to mold.
Therefore, an aromatic polyester in which various components are copolymerized with p-hydroxybenzoic acid to lower its melting point has been proposed, but has the following disadvantages.

(1) JP-A-54-139798 A copolymer of p-hydroxybenzoic acid, hydroquinone and isophthalic acid has a high melting point. (2) U.S. Pat. No. 3,637,595 Copolymers of aromatic dihydroxy compounds such as p-hydroxybenzoic acid, terephthalic acid, isophthalic acid and hydroquinone. Although heat resistance is high and the strength of the molded product is high, the melt molding temperature is very high. There are also the following examples. (3) U.S. Pat. No. 4,067,852 An aromatic polyester obtained by copolymerizing p-hydroxybenzoic acid, 2,6-naphthalenedicarboxylic acid and an aromatic dihydroxy compound. (4) U.S. Pat. No. 4,169,933;
No. 0290) An aromatic polyester obtained by copolymerizing p-hydroxybenzoic acid, 2,6-naphthalenedicarboxylic acid, terephthalic acid, and hydroquinone. (5) US Pat. No. 4,083,829 An aromatic polyester obtained by copolymerizing p-hydroxybenzoic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid or resorcinol, and an aromatic dihydroxy compound. (6) U.S. Pat. No. 4,130,545 An aromatic polyester obtained by copolymerizing p-hydroxybenzoic acid, 2,6-naphthalenedicarboxylic acid, m-hydroxybenzoic acid, and an aromatic dihydroxy compound.

[0005] These aromatic polyesters have a relatively low melting point, can be melt-molded, and have a spun yarn strength of 6 to 10 g.
/ Denier, but has the drawback that the heat resistance temperature is not so high. As described above, the polyester copolymer obtained by the conventional method has high heat resistance and at the same time is difficult or impossible to mold due to high melting point or high flow temperature. Some had a high melt viscosity and were difficult to mold, and others had insoluble particles in the polymer after polymerization and had poor moldability.

[0006] On the other hand, there are those having a low melting point or flow temperature and good moldability, but insufficient heat resistance. The melting temperature of the resin is preferably low from the viewpoint of ease of molding, but when the melting temperature of the resin is lowered, the heat resistance tends to decrease. In addition, the liquid crystal polyester has a property (anisotropic) in which the strength in the resin orientation direction (MD direction) and the direction perpendicular thereto (TD direction) greatly differ in melt processing.
With. Destruction of an injection molded product due to external force generally occurs at the weakest point. In the case of liquid crystal polyester, cracks occur in the TD direction of the molded product.

Therefore, in order to improve the practical strength of the liquid crystal polyester, it is necessary to improve the anisotropy, that is, to increase the strength in the TD direction.

[0008]

The object of the present invention is to provide excellent heat resistance, moldability, mechanical strength, flame retardancy, chemical resistance, solvent resistance, appearance, low linear expansion coefficient, and low molding shrinkage. Another object of the present invention is to provide a novel aromatic polyester which can be easily injection molded.

[0009]

An embodiment of the present invention consists essentially of units represented by the following formulas I, II, III, IV and V:

Embedded image (Where X in the formula is H, a C ₁ -C ₄ alkyl group, C
_A C ₁ -C ₄ alkoxy group, a C ₈ -C ₁₀ aryl group or a halogen, and —O—Ar—O— in the formula is a symmetric having at least one monocyclic or condensed aromatic ring. Is a sex dioxy unit, and Y is -O- or

Embedded image Is). Unit I 40 to 70 mol% Unit II 1 to 8 mol% Unit III + unit IV 6 to 36 mol% Unit V 10 to 40 mol%, and the molar ratio of unit III / (unit III + unit IV) is 0. Nozzle φ used with flow tester
0.5mm × 1.0mm, pressure 10kg / cm ² , heating rate 6 ℃ /
The relationship between the temperature and the viscosity of the resin was measured under the conditions of
An aromatic polyester characterized by having a temperature at which the viscosity of poise reaches 271 to 350 ° C.

Hereinafter, the present invention will be described in detail. First, each unit (I) substantially constituting the aromatic polyester of the present invention
(V) will be described. (1) The p-hydroxybenzoic acid of the unit (I) has a benzene nucleus whose C ₁ -C ₄ -alkyl, C ₁ -C ₄ -alkoxy, C ₆ -C ₁₀ -aryl or halogen (preferably chlorine) , Bromine) substituted p-hydroxybenzoic acid. Preferably, unsubstituted p-hydroxybenzoic acid is exemplified by ester-forming derivatives such as acetate, propionate, benzoate, methyl, ethyl and phenyl. Unit (I) is about 40-7
0 mol%, preferably about 45 to 65 mol% is contained. When the unit (I) is less than 40 mol% and more than 70 mol%, the mechanical strength of the formed polyester decreases.

(2) The unit (II) comprises an isophthaloyl moiety represented by the following formula (II-i) and / or a unit represented by the following formula (II-i):
m-hydroxybenzoic acid moiety shown in ii).

Embedded image The benzene nucleus of (II-i) and (II-ii) is C ₁ -C
₄ - alkyl, C ₁ -C ₄ - alkoxy, C ₆ -C ₁₀ -
It may be substituted with aryl or halogen (preferably chlorine or bromine). The unit (II-i) is an isophthaloyl moiety, and representatively includes isophthalic acid and / or mono- or diester derivatives of methyl, ethyl and phenyl of isophthalic acid. Unit (II-ii)
Is an m-hydroxybenzoic acid moiety, and typically includes mono- or diester derivatives of m-hydroxybenzoic acid and / or its acetate, propionate, benzoatemethyl, ethyl, and phenyl.
The unit (II) represented by (II-i) and / or (II-ii) is about 1 to 8 mol%, preferably 2 to 5 mol%. When the unit (II) is less than 1 mol%, the flow temperature of the polyester becomes high and molding is difficult, and when the unit (II) exceeds 8 mol%, the heat resistance of the polyester is reduced.

(3) The unit (III) and the unit (IV) are typically terephthalic acid and 2,6-naphthalenedicarboxylic acid, and their mono- or diester derivatives of methyl, ethyl and phenyl. Unit (III) + unit (IV) is 6 to 36 mol%, preferably 1 to 36 mol%.
2 to 27 mol%. The molar ratio of the unit (III) to the unit (IV) [(III) / {(III) + (IV)}] is 0.1 to
0.8, preferably about 0.3-0.7. If the molar ratio is less than 0.1, the flow temperature of the polyester becomes high and molding becomes difficult, and the heat resistance is low. If it exceeds 0.8, the flow temperature becomes high and molding becomes difficult.
As will be described in detail later in the examples, the unit of the following composition (II-i
) Is synthesized to obtain the unit (III)
) / {Unit (III) + unit (IV)}, ie, m /
The injection molding temperature and the heat distortion temperature were measured while changing (m + n), and are shown in FIG.

Embedded image

Next, as described in detail in Examples, an aromatic polyester having a unit (II-ii) having the following composition was synthesized, and the unit (III) / {unit (III) + unit (IV)}, That is, the injection molding temperature and the heat deformation temperature were measured while changing p / (p + q), and the results are shown in FIG.

Embedded image

From the results shown in FIGS. 1 and 2, the unit (II
If (I) / {unit (III) + unit (IV)} is less than 0.1, the heat deformation temperature decreases, and the injection molding temperature increases.
When it exceeds 0.8, although the heat deformation temperature becomes high, the injection molding temperature becomes extremely high, and it can be seen that the moldability deteriorates. Unit (III) / {Unit (III) + Unit (IV)}
Is in the range of 0.3 to 0.7, the heat deformation temperature is high despite the low injection molding temperature, the temperature fluctuation due to the composition change is small, and the characteristics of the aromatic polyester of the present invention are remarkably exhibited. . If the amount of the unit (III) + the unit (IV) is less than 6 mol%, the flow temperature of the polyester becomes high and it is difficult to mold, and if the unit (III) + the unit (IV) exceeds 36 mol%, the copolyester is colored. And the mechanical strength is reduced.

(4) The unit (V) is a symmetric dihydroxy compound, represented by HO-Ar-OH, and Ar means a divalent group comprising at least one aromatic ring. Unit (V)
Is contained in an amount of 10 to 40 mol%, preferably 17.5 to 27.5 mol%. Examples of the symmetric dihydroxy aromatic compound of the wholly aromatic polyester included in the present invention include those which form the following units in the copolyester.

Embedded image

In particular, hydroquinone, bisphenol A,
4,4'-dihydroxybiphenyl, dihydroxybiphenyl ether, 2,6-dihydroxynaphthalene, etc.
Or, there are mono- or diester derivatives such as acetate, propionate and benzoate. Particularly preferred compounds are 4,4'-dihydroxybiphenyl and 2,6-dihydroxynaphthalene. If the unit (V) is less than 10 mol%, the flow temperature of the polyester becomes high and molding is difficult, and if the unit (V) exceeds 40 mol%, the heat resistance of the polyester is undesirably lowered.

The resin of the present invention comprises the above essential components (I) to
In addition to (V), other components may be contained as long as the object of the present invention is not impaired. Further, a copolymer or a mixture of the aromatic polyester of the present invention and an aromatic polyester amide obtained by introducing an amide component into the polyester may be used.

The aromatic polyester of the present invention comprises other resin components, an antioxidant; a coloring inhibitor; a stabilizer; an ultraviolet absorber; a plasticizer; a lubricant such as molybdenum disulfide, silicone oil, a fluororesin, and graphite. A flame retardant such as tetrabromobisphenol A or antimony trioxide may be added.

[0019]

The present invention will be described more specifically with reference to the following examples.
First, evaluation methods of the examples and the comparative examples will be described. (1) Molding temperature Using a flow tester (manufactured by Shimadzu Corporation), use the nozzle φ0.
The temperature-viscosity relationship of the resin was measured under the conditions of 5 mm × 1.0 mm, a pressure of 10 kg / cm ² , and a heating rate of 6 ° C./min, and evaluated at a temperature at which the viscosity reached 10,000 poise. The polyester of the present invention has a temperature of about 271 ° C. (see Example 4, Table 3) to 350 ° C. (see FIG. 1). This temperature substantially coincides with the cylinder temperature during injection molding. That is, the temperature at which the viscosity of the resin reaches 10,000 poise represents the molding temperature of the resin.

(2) Heat distortion temperature (HDT) Heat distortion temperature (HDT) according to the method of ASTM-D648.
6 kg / cm ² ).

(3) Injection molding temperature The obtained polymer is pulverized and then pulverized by an injection molding machine (Yamashiro Seiki Seisakusho SAV-60-52) at a mold temperature of 120 ° C., an injection pressure of 250 kg / cm ² , and a cylinder. The temperature is the temperature at which the resin is completely filled in the mold, and
A 1/8 × 5 inch rod was formed. The cylinder temperature during the injection molding was defined as the injection molding temperature, and the lower the temperature, the better the moldability.

(4) Bending strength and anisotropy test The test plate prepared as described above was cut out in a resin flow direction (TD direction) and a direction perpendicular thereto (MD direction) with a width of 14 mm to obtain a bending test piece. Was. The bending test is ASTM-D
790. The anisotropy test is performed using the MD of the test piece.
The magnitude of the mechanical strength anisotropy was determined from the ratio of the bending strength in the TD direction to the bending strength in the TD direction. (The greater the MD / TD, the greater the anisotropy.) Examples and comparative examples of the aromatic polyester of the present invention are shown.

Example 1 In a 500 ml separable flask equipped with a sealed stirrer, a gas inlet tube and a distillation head equipped with a condenser, 60 g of p-acetoxybenzoic acid (0.
333 mol), 3 g of m-acetoxybenzoic acid (0.01 g)
67 mol), 8.52 g (0.0513 mol) of terephthalic acid, 11.1 g of 2,6-naphthalenedicarboxylic acid
(0.0514 mol) and 27.75 g (0.1028 mol) of 4,4'-diacetoxybiphenyl were charged. The flask was evacuated and air was purged twice with dry argon. The flask and contents were then heated to 250 ° C. with stirring while gently passing argon through.

As soon as the mixture had melted, acetic acid began to distill. After maintaining the temperature at 250 ° C. for about 2 hours, the flask and contents temperature was increased to 280 ° C. 280 ° C
After about 1 hour, 30.6 g of acetic acid was collected. Next, the content was heated to 320 ° C. and kept for 15 minutes, and then 340
C. and kept for 15 minutes. At this time, the amount of acetic acid distilled and condensed was 32 g.

Next, a pressure reduction operation is performed, and the pressure is reduced to 90 mm at 350 ° C.
Hg and keep for 5 minutes, then 30mmHg for 5 minutes and 3mm
The polymerization was continued for 10 minutes as Hg and finally for about 15 minutes under a vacuum of 0.3 mmHg. At this point, the contents of the flask were opaque yellow-white and quite viscous. Subsequently, the mixture was cooled under an argon stream to take out an aromatic polyester.

The polymer showed a melting point at 294 ° C. in differential thermal analysis. This polyester was placed on a sample stage of a polarizing microscope, and the temperature was raised to confirm the optical anisotropy. As a result, good optical anisotropy was shown. This polyester is subjected to an elevated flow tester (load 10 kg · f, nozzle diameter 0.5 ×
1.0 mm) It was 10,000 poise at 293 ° C.

Further, 1/2 × 成形 ×
A 5-inch bar was molded, and the Vicat softening point and heat resistance temperature (heat distortion temperature HDT) were measured. Vicat softening point 246 ℃ Heat deformation temperature 196 ℃

This polyester is made into a spinneret having a diameter of 0.3 mm.
It was melt spun by a spinning machine having a single capillary of 0.9 mm length. The resulting fiber showed high toughness and other mechanical properties were as follows. Strength 10.0 (g / d) Tensile modulus 60.0 (GPa) Elongation 1.87 (%) Table 1 shows the composition and physical property evaluation results.

Example 2 In the same manner as in Example 1, copolyesters having various compositions were prepared. Table 1 shows the results
Shown in All of these polyesters exhibited optical anisotropy at rest at temperatures higher than the flow temperature.

(Comparative Examples 1 to 6) As a comparison, the heat resistance temperature of fibers and molded articles from other known liquid crystalline copolyesters was measured and the results are shown in Table 2. The conditions of the polymerization are also shown in Table 2. The temperature at the final stage of the polymerization was 350 ° C. for Comparative Examples 1 to 3, and 320 ° C. for Comparative Examples 4 to 6. The resulting polymer formed liquid crystals above each flow temperature.

[0031]

[Table 1]

[0032]

[Table 2]

Example 3 In a 500 ml separable flask equipped with a sealed stirrer, a gas inlet tube and a distillation head equipped with a condenser, 60 g of p-acetoxybenzoic acid (0.
333 mol), 2.77 g (0.0167 g) of isophthalic acid
Mol), 6.45 g (0.0389 mol) of terephthalic acid, 12.0 g of 2,6-naphthalenedicarboxylic acid
(0.0556 mol) and 30 g (0.111 mol) of 4,4′-diacetoxybiphenyl were charged. The flask was evacuated and air was purged twice with dry argon. The flask and contents were then heated to 250 ° C. with stirring while gently passing argon through. As soon as the mixture melted, acetic acid began to distill. After maintaining the temperature at 250 ° C. for about 2 hours, the temperature of the flask and contents was raised to 280
° C. After about 1 hour at 280 ° C., 30.7 g of acetic acid was collected. Next, the content was heated to 320 ° C. and kept for 15 minutes, and then further heated to 340 ° C. and kept for 15 minutes. At this time, the amount of acetic acid distilled and condensed was 32.3 g.

Next, a pressure reduction operation was performed, and the pressure was reduced to 90 mm at 350 ° C.
Hg and keep for 5 minutes, then 30mmHg for 5 minutes and 3mm
The polymerization was continued for 10 minutes as Hg and finally for about 15 minutes under a vacuum of 0.3 mmHg. At this point, the contents of the flask were opaque yellow-white and quite viscous. Then, the mixture was cooled under an argon stream to take out an aromatic polyester. The polymer showed a melting point at 285 ° C. in differential thermal analysis. This polyester was placed on a sample stage of a polarizing microscope, and the temperature was raised to confirm the optical anisotropy. As a result, good optical anisotropy was shown. This polyester was subjected to an elevated flow tester (with a load of 10
kg · f, nozzle diameter 0.5 × 1.0mm)
000 poise. Further, the Vicat softening point and the heat resistance temperature (heat distortion temperature HDT) were measured on the molded sample. Vicat softening point 250 ° C Heat distortion temperature 198 ° C This polyester is spinneret diameter 0.3mm and length 0.9mm
Was melt-spun by a spinning machine having a single capillary. The resulting fiber showed high toughness and other mechanical properties were as follows. Strength 5.0 (g / d) Tensile modulus 90 (GPa) Elongation 1.78 (%) The results are shown in Table 3.

Example 4 In the same manner as in Example 3, aromatic polyesters having various compositions were prepared. Table 3 shows the results. All of these polyesters exhibited optical anisotropy at rest at temperatures higher than the flow temperature.

(Comparative Examples 7 and 8) As a comparison, Table 4 shows the heat resistance temperatures of fibers and molded articles from other known liquid crystalline copolyesters. The polymerization conditions are also shown in Table 4, and the temperature at the final stage of the polymerization was set at 35 for Comparative Example 7.
The temperature was set to 0 ° C. and to 360 ° C. for Comparative Example 8. The resulting aromatic polyester formed liquid crystals above each flow temperature.

[0037]

[Table 3]

[0038]

[Table 4]

Example 5 An aromatic polyester having a unit (II-i) having the following composition was synthesized in the same manner as in Example 1, and the unit (III) / {unit (III) + unit (IV)} was used. ,
That is, the injection molding temperature and the heat deformation temperature were measured while changing m / (m + n), and the results are shown in FIG.

[0040]

Embedded image

Example 6 An aromatic polyester having a unit (II-ii) having the following composition was synthesized in the same manner as in Example 1, and the unit (III) / {unit (III) + unit (IV)} was used. ,
That is, the injection molding temperature and the heat deformation temperature were measured while changing p / (p + q), and the results are shown in FIG.

[0042]

Embedded image

[0043]

The aromatic polyester of the present invention has a low melting point of 330 ° C. or less, is optically anisotropic, and has particularly excellent heat resistance and mechanical properties, such as injection molding, extrusion molding, compression molding, and blow molding. Can be subjected to ordinary melt molding. Further, it can be processed into molded articles other than fibers, films and containers, hoses and the like. Specifically, the molded article can be widely used for connector IC sockets, sealing molded articles such as ICs and transistors, optical fiber-related parts such as coating materials and reinforcing materials, and automobile parts. Further, at the time of molding, fillers such as glass fiber, carbon fiber, and asbestos, other additives, and other thermoplastic resins can be added to impart desired properties to the molded product.

[Brief description of the drawings]

FIG. 1 is a graph showing measurement results of Examples and Comparative Examples.

FIG. 2 is a graph showing measurement results of Examples and Comparative Examples.

(72) Inventor Yumiko Kumazawa 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Prefecture

Claims (1)

(57) [Claims] (1) It consists essentially of units represented by the following formulas (I), (II), (III), (IV) and (V): (Where X in the formula is H, a C ₁ -C ₄ alkyl group, C
A C ₄ to C ₄ alkoxy group, a C _{6 to} C ₁₀ aryl group or a halogen, and —O—Ar—O— in the formula is a symmetric having at least one monocyclic or condensed aromatic ring. A dioxy unit, and Y is —O— or Is). Unit I 40 to 70 mol% Unit II 1 to 8 mol% Unit III + unit IV 6 to 36 mol% Unit V 10 to 40 mol%, and the molar ratio of unit III / (unit III + unit IV) is 0. 1 to 0.8, using a flow tester, nozzle 0.5 mm x 1.0 mm, pressure 10 kg / cm ² , heating rate 6 ° C
The relationship between temperature and viscosity of the resin was measured under the conditions of
Aromatic polyester, wherein the temperature at which the viscosity becomes 0 poise is 271 to 350 ° C.