AROMATIC LIQUID CRYSTAL POLYESTER, AROMATIC LIQUID CRYSTAL POLYESTER COMPOSITION, AND MOLDED ARTICLE

Abstract

An aromatic liquid crystal polyester containing repeating structural units represented by formulas (A1), (B), (C) and (D) shown below.

OAr1CO(A1)

COAr2CO(B)

OAr3O(C)

OAr4O(D)

(In the formulas, Ar1 represents a 2,6-naphthalene group, Art represents at least one group selected from the group consisting of a 2,6-naphthalenediyl group, 1,4-phe vlene group, 1,3-phenvIene group and 4,4-biphenylene group, Ar3 represents at least one group selected from the group consisting of a 2, mphthalenediyl group, 1,6-naphthalenediyl group and 1,5-naphthalenediyl group, Ar4 represents at least one group selected from the group consisting of a 2,6-naphthalenediyl group, 1,4-phenylene group, 1,3-phenylene group and 4,4-hiphenylene group, and each of the groups represented by Ar1, Ar3 or Ar4 may have a halogen atom, an alkyl group of 1 to 10 carbon atoms Of alt aryl group of 6 to 20 carbon atoms as a substituent.)

Claims

1. An aromatic liquid crystal polyester containing repeating structural units represented by formulas (A1), (B), (C) and (D) shown below:
OAr1CO(A1)
COAr2CO(B)
OAr3O(C)
OAr4O(D) wherein Ar1 represents a 2,6-naphthalenediyl group, Ar2 represents at least one group selected from the group consisting of a 2,6-naphthalenediyl group, 1,4-phenylene group, 1,3-phenylene group and 4,4-biphenylene group, Ar3 represents at least one group selected from the group consisting of a 2,7-naphthalenediyl group, 1,6-naphthalenediyl group and 1,5-naphthalenediyl group, Ar4 represents at least one group selected from the group consisting of a 2,6-naphthalenediyl group, 1,4-phenylene group, 1,3-phenylene group and 4,4-biphenylene group, and each group represented by Ar1, Ar2, Ar3 or Ar4 may have a halogen atom, an alkyl group of 1 to 10 carbon atoms or an aryl group of 6 to 20 carbon atoms as a substituent.

2. The aromatic liquid crystal polyester according to claim 1, composed solely of repeating structural units represented by formulas (A1), (B), (C) and (D).

3. The aromatic liquid crystal polyester according to claim 1, wherein a molar fraction of the repeating structural unit represented by formula (A1) is at least 30 mol % but not more than 80 mol % relative to a total molar amount of all repeating units, a molar fraction of the repeating structural unit represented by formula (B) is at least 10 mol % but not more than 35 mol % relative to a total molar amount of all repeating units, a molar fraction of the repeating structural unit represented by formula (C) is at least 0.1 mol % but not more than 20 mol % relative to a total molar amount of all repeating units, and a molar fraction of the repeating structural unit represented by formula (D) is at least 9.9 mol % but not more than 34.9 mol % relative to a total molar amount of all repeating units.

4. The aromatic liquid crystal polyester according to claim 1, further containing a repeating structural unit represented by formula (A2) shown below:
OAr1CO(A2) wherein Ar10 represents a 1,4-phenylene group, and the group represented by Ar10 may have a halogen atom, an alkyl group of 1 to 10 carbon atoms or an aryl group of 6 to 20 carbon atoms as a substituent.

5. The aromatic liquid crystal polyester according to claim 1, having a weight average molecular weight of at least 20,000, and a flow start temperature of at least 200 C. but not more than 370 C.

6. The aromatic liquid crystal polyester according to claim 1, wherein the repeating structural unit represented by formula (D) is one or both of a repeating structural unit derived from 4,4-biphenol and a repeating structural unit derived from hydroquinone.

7. An aromatic liquid crystal polyester composition comprising the aromatic liquid crystal polyester according to claim 1 and glass fiber, wherein an amount of the glass fiber, relative to a total mass of the aromatic liquid crystal polyester composition, is at least 5% by mass but not more than 60% by mass.

8. A molded article obtained by injection molding of the aromatic liquid crystal polyester according to claim 1.

9. A molded article obtained by injection molding of the aromatic liquid crystal polyester composition according to claim 7.

Description

EXAMPLES

[0076] Next, the present invention is described in further detail using a series of examples.

Example 1

[0077] A reactor fitted with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 1,129.1 g (6.0 mol) of 2-hydroxy-6-naphthoic acid, 353.8 g (1.9 mol) of 4,4-biphenol, 16.0 g (0.1 mol) of 2,7-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 310 C. over a period of 10 hours and 15 minutes, and then held at 310 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Example 2

[0078] A reactor fitted with a stirrer, a torque eter, a nitrogen gas inlet tube, a. thermometer and a reflux condenser was charged with 1,129.1 g (6.0 mol) of 2-hydroxy-6-naphthoic acid, 335.2 g (1.8 mol) of 4,4-biphenol, 32.0 g (0.2 mol) of 2,7-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 310 C. over a period of 10 hours and 15 minutes, and then held at 310 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Example 3

[0079] A reactor fitted with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 1,129.1 g (6.0 mol) of 2-hydroxy-6-naphthoic acid, 279.3 g (1.5 mol) of 4,4-biphenol, 80.1 g (0.5 mol) of 2,7-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 310 C. over a period of 10 hours and 15 minutes, and then held at 310 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Comparative Example 1

[0080] A reactor fitted with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 828.7 g (6.0 mol) of 4-hydroxybenzoic acid, 372.4 g (2.0 mol) of 4,4-biphenol, 249.2 g (1.5 mol) of terephthalic acid, 83.1 g (0.5 mol) of isophthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 285 C. over a. period of 7 hours, and then held at 285 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Comparative Example 2

[0081] A reactor fitted with a stirrer, o meter, a nitrogen gas inlet tube, a thermometer and ux condenser was charged with 828.7 g (6.0 mol) of 4-hydroxybenzoic acid 335.2 g (1.8 mol) of 4,4-biphenol, 32.0 g (0.2 mol) of 2,7-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 290 C. over a period of 7 hours and 40 minutes, and then held at 290 C. for 5 hours,thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Comparative Example 3

[0082] A reactor fitted with a stirrer, a torque meter, nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 828.7 g (6.0 mol) of 4-hydroxybenzoic acid. 219.3 g (1.5 mol) of 4,4-biphenol, 80.1 g (0.5 mol) of 2,7-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 290 C. over a period of 7 hours and 40 minutes, and then held at 290 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Comparative Example 4

[0083] A reactor fitted with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 1,129.1 g (6.0 mol) of 2-hydroxy-6-naphthoic acid, 372.4 g (2.0 mol) of 4,4-biphenol, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 230 C. over a period of 1.5 hours and then from 230 C. to 310 C. over a period of 10 hours and 15 minutes, and then held at 310 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Example 4

[0084] A reactor fitted with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 1,129.1 g (6.0 mol) of 2-hydroxy-6-naphthoic acid, 353.8 g (1.9 mol) of 4,4-biphenol, 16.0 g (0.1 mol) of 1,6-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 250 C. over a period of 1.5 hours and then from 250 C. to 300 C. over a period of 6 hours and 30 minutes, and then held at 300 C. for 5 hours, thereby causing a polymerization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

Example 5

[0085] A reactor fitted with a stirrer, torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser was charged with 1,129.1 g (6.0 mol) of 2-hydroxy-6-naphthoic acid, 335.2 g (1.8 mol) of 4,4-biphenol, 32.0 g (0.2 mol) of 1,6-dihydroxynaphthakne, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse cinder, and was then heated, under a nitrogen atmosphere, from room temperature to 250 C. over a period of 1.5 hours and then from 250 C. to 300 C. over a period of 6 hours and 30 minutes, and then held at 300 C. for 5 hours, thereby causing a polymerization reaction to proceed in the olid phase to obtain a powdered aromatic liquid crystal polyester.

Example 6

[0086] A reactor fitted ith a stirrer, torque meter, a nitrogen gas inlet tube, a 6-naphthoic acid, 279.3 g (1.5 mol) of 4,4-biphenol, 80.1 g (0.5 mol) of 1,6-dihydroxynaphthalene, 332.3 g (2.0 mol) of terephthalic acid, 1,123.0 g (11 mol) of acetic anhydride and 0.06 g of N-methylimidazole. Following thorough flushing of the inside of the reactor with nitrogen gas, the temperature was increased to 142 C. over a period of 60 minutes under a stream of nitrogen gas, and the contents were then refluxed for 1 hour with the temperature maintained. Subsequently, the temperature was increased to 305 C. over a period of 4 hours and 30 minutes, while the distilled by-product acetic acid and unreacted acetic anhydride were removed by distillation, and deeming the point where an increase in torque was noticed as the end of the reaction, the contents were then extracted. The obtained solid fraction was cooled to room temperature (23 C.), ground in a coarse grinder, and was then heated, under a nitrogen atmosphere, from room temperature to 250 C. over a period of 1.5 hours and then from 250 C. to 300 C. over a period of 6 hours and 30 minutes, and then held at 300 C. for 5 hours, thereby causing a pc y erization reaction to proceed in the solid phase to obtain a powdered aromatic liquid crystal polyester.

<Measurement of Flow Start Temperature of Aromatic Liquid Crystal Polyester>

[0087] Using a flow tester (model: CFT-500 manufactured by Shimadzu Corporation) about 2 g of the aromatic liquid crystal polyester was packed in a cylinder equipped with a die having a nozzle with an internal diameter of 1 mm and a length of 10 mm, the aromatic liquid crystal polyester was melted and extruded from the nozzle while the temperature was increased at a rate of 4 C./minute under a loading of 9.8 MPa (100 kg/cm.sup.2), and the temperature that yielded a viscosity of 4,800 Pa.Math.s (48,000 poise) was measured.

<Measurement of Tensile Strength>

[0088] Forty parts by mass of milled glass fiber (average fiber length: 75 m, fiber diameter: 11 m) was mixed with 60 parts by mass of the powdered aromatic liquid crystal polyester, and the resultant mixture was melt kneaded using a unidirectional twin-screw extruder (PCM-30HS, manufactured by Ikegai, Ltd.), extruded in a strand-like form, cooled, and then cut to obtain a pelletized liquid crystal polyester composition.

[0089] The thus obtained liquid crystal polyester composition was molded into an ASTM No. 4 dumbbell shape using an injection molding machine (model: PS40E5ASE, manufactured by Nissei Plastic Industrial Co., Ltd.), and the tensile strength was measured in accordance with ASTM D638.

<Measurement of Flexural Strength>

[0090] Forty parts by mass of milled glass fiber (average fiber length: 75 m, fiber diameter: 11 m) was mixed with 60 parts by mass of the powdered aromatic liquid crystal polyester, and the resultant mixture was melt kneaded using a unidirectional twin-screw extruder (PCM-30HS, manufactured by Ikegai, Ltd.), extruded in a strand-like form, cooled, and then cut to obtain a pelletized liquid crystal polyester composition.

[0091] The thus obtained liquid crystal polyester composition was molded into a test piece having a length of 127 mm, a width of 12.7 mm and a thickness of 6.4 mm using an injection molding machine (model: PS40E5ASE, manufactured by Nissei Plastic Industrial Co., Ltd.), and the flexural strength was measured in accordance with ASTM D790.

<Measurement of Deflection Temperature Under Load>

[0092] Forty parts by mass of milled glass fiber (average fiber length: 75 m, fiber diameter: 11 m) was mixed with 60 parts by mass of the powdered aromatic liquid crystal polyester, and the resultant mixture was melt kneaded using a unidirectional twin-screw extruder (PCM-3OHS, manufactured by Ikegai, Ltd.), extruded in a strand-like form, cooled, and then cut to obtain a pelletized liquid crystal polyester composition.

[0093] The thus obtained liquid crystal polyester composition was molded into a test piece having a length of 127 mm, a width of 12.7 mm and a thickness of 6.4 mm using an injection molding machine (model: PS40E5ASE, manufactured by Nissei Plastic Industrial Co., Ltd.), and the deflection temperature under load for the test piece was measured under a load of 1.82 MPa in accordance with ASTM D648.

<Measurement of Molding Shrinkage Factors>

[0094] Forty parts by mass of milled glass fiber was mixed with 60 parts by mass of the powdered aromatic liquid crystal polyester, and the resultant mixture was melt kneaded using a unidirectional twin-screw extruder (PCM-30HS, manufactured by Ikegai, Ltd.), extruded in a strand-like form, cooled, and then cut to obtain a pelletized liquid crystal polyester composition.

[0095] Using a flat test piece (hereinafter also referred to as a molded body) of 64 mm (MD)64 mm (TD)3 mmt produced from the thus obtained liquid crystal polyester composition using an injection molding machine (model: PS40E5ASE, manufactured by Nissei Plastic Industrial Co., Ltd.), the lengths of the two MD sides were measured, the average value of the two values was determined, and by using this average value and the MD length of the mold cavity, the MD shrinkage was calculated from the formula shown below. Further, for the produced molded body, the lengths of the two TD sides were measured, the average value of the two values was determined, and by using this average value and the TD length of the mold cavity, the TD shrinkage was calculated from the formula shown below.

[MD Shrinkage (%)]=([MD length of mold cavity (m)][average value of two MD sides of molded body (m)])/[MD length of mold cavity (m)]100

[TD Shrinkage (%)]=([TD length of mold cavity (m)][average value of two TD sides of molded body (m)])/[TD length of mold cavity (m)]100

TABLE-US-00001 TABLE 1 Compar- Compar- Compar- Compar- ative ative ative ative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 Monomer 4-hydroxybenzoic acid 60 60 60 compo- 2-hydroxy-6-naphthoic acid 60 60 60 60 60 60 60 sition 4,4-biphenol 20 18 15 20 19 18 15 19 18 15 (mol %) 2,7-dihydroxynaphthalene 2 5 1 2 5 1,6-dihydroxynaphthalene 1 2 5 terephthalic acid 15 20 20 20 20 20 20 20 20 20 isophthalic acid 5 Flow start temperature C. 330 332 320 337 333 322 297 330 324 323 Tensile strength MPa 142 138 150 97 161 182 173 137 146 143 Flexural strength MPa 133 150 166 152 206 199 192 182 185 176 Deflection temperature under load C. 273 272 204 340 325 289 209 311 282 211 Molding shrinkage MD % 0.22 0.12 0.20 0.15 0.19 0.15 0.11 0.09 0.16 0.17 factors TD % 1.40 1.29 1.00 1.27 1.38 1.08 0.87 1.45 1.35 0.99

[0096] As is evident from the results shown above in Table 1 compared with Comparitive Examples 1 to 4 that did not apply the present invention, Examples that applied the present invention exhibited superior dimensional stability and had higher strength for the molded articles.

INDUSTRIAL APPLICABILITY

[0097] The present invention can provide an aromatic iquid crystal polyester and an aromatic crystal polyester composition that uses the aromatic liquid crystal polyester which are capable of molding molded articles having excellent dimensional stability and high strength, and is therefore extremely useful industrially.