LIQUID CRYSTAL POLYESTER COMPOSITION AND RESIN MOLDED BODY

Abstract

A liquid crystal polyester composition including a liquid crystal polyester and fibrous fillers, wherein in the fibrous fillers, the number of long fibers having a fiber length of 80 m or more contained in the fibrous fillers is 30% or less with respect to the number of the fibrous fillers, and a number average fiber diameter of the fibrous fillers is 12 m or less.

Claims

1. A liquid crystal polyester composition comprising a liquid crystal polyester and fibrous fillers, wherein in the fibrous fillers, the number of long fibers having a fiber length of 80 m or more contained in the fibrous fillers is 30% or less with respect to the number of the fibrous fillers, and a number average fiber diameter of the fibrous fillers is 12 m or less.

2. A liquid crystal polyester composition comprising a liquid crystal polyester and fibrous fillers, wherein a number average fiber length of the fibrous fillers is 15 m or more and 60 m or less, and a number average fiber diameter of the fibrous fillers is 12 m or less.

3. The liquid crystal polyester composition according to claim 1, wherein the number average fiber diameter of the fibrous fillers is 6 m or less.

4. The liquid crystal polyester composition according to claim 1, wherein a content of the fibrous fillers is 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

5. A resin molded body formed from the liquid crystal polyester composition according to claim 1.

6. The liquid crystal polyester composition according to claim 2, wherein the number average fiber diameter of the fibrous fillers is 6 m or less.

7. The liquid crystal polyester composition according to claim 2, wherein a content of the fibrous fillers is 10 parts by mass or more and 150 parts by mass or less with respect to 100 parts by mass of the liquid crystal polyester.

8. A resin molded body formed from the liquid crystal polyester composition according to claim 2.

Description

EXAMPLES

[0124] The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

<Measurement of Flow Starting Temperature of Liquid Crystal Polyester>

[0125] Using a Flowtester (CFT-500 model manufactured by Shimadzu Corporation), a cylinder equipped with a die including a nozzle having an inner diameter of 1 mm and a length of 10 mm was filled with about 2 g of a liquid crystal polyester, the liquid crystal polyester was melted and extruded from the nozzle while raising the temperature at a rate of 4 C./min under a load of 9.8 MPa (100 kg/cm2), and a temperature at which a viscosity of 4,800 Pa.Math.s (48,000 poise) was exhibited was measured.

<Production of Liquid Crystal Polyester>

Production Example 1

[0126] 994.5 g (7.2 mol) of parahydroxybenzoic acid, 446.9 g (2.4 mol) of 4,4-dihydroxybiphenyl, 299.0 g (1.8 mol) of terephthalic acid, 99.7 g (0.6 mol) of isophthalic acid and 1,347.6 g (13.2 mol) of acetic anhydride, and 0.194 g of 1-methylimidazole as a catalyst were added to a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser. The resulting mixture was stirred at room temperature for 15 minutes and the inside of the reactor was thoroughly replaced with nitrogen gas, and then the temperature was raised while stirring. When the internal temperature reached 145 C., the resulting mixture was stirred for 1 hour while maintaining the same temperature.

[0127] Thereafter, the temperature was raised to 320 C. over 2 hours and 50 minutes while distilling off acetic acid produced as a byproduct and unreacted acetic anhydride, and the reaction was terminated at a time point where an increase in torque was observed to obtain a prepolymer.

[0128] The obtained prepolymer was cooled to room temperature and pulverized by a coarse grinder to obtain a liquid crystal polyester powder (particle diameter: about 0.1 mm to about 1 mm), and then under a nitrogen atmosphere, the temperature was raised from room temperature to 250 C. over a period of 1 hour, the temperature was raised from 250 C. to 285 C. over a period of 5 hours, and the temperature was maintained at 285 C. for 3 hours to allow a polymerization reaction to proceed in a solid layer. The flow starting temperature of the obtained liquid crystal polyester (1) was 327 C.

Production Example 2

[0129] 1,034.99 g (5.5 mol) of 6-hydroxy-2-naphthoic acid, 378.33 g (1.75 mol) of 2,6-naphthalenedicarboxilic acid, 83.07 g (0.5 mol) of terephthalic acid, 272.52 g (2.475 mol: 0.225 mol in excess with respect to the total amount of 2,6-naphthalenedicarboxylic acid and terephthalic acid) of hydroquinone, 1,226.87 g (12 mol) of acetic anhydride and 0.17 g of 1-methylimidazole as a catalyst were placed in a reactor equipped with a stirrer, a torque meter, a nitrogen gas inlet tube, a thermometer and a reflux condenser. After replacing the gas in the reactor with nitrogen gas, the resulting mixture was heated from room temperature to 145 C. over 30 minutes while stirring in a nitrogen gas stream and refluxed at 145 C. for 1 hour.

[0130] Subsequently, the temperature was raised from 145 C. to 310 C. over 3 hours and 30 minutes while distilling off acetic acid as a byproduct and unreacted acetic anhydride, and after maintaining the temperature at 310 C. for 3 hours, the contents were taken out from the reactor and cooled to room temperature.

[0131] The obtained solid was pulverized with a grinder to obtain a powdery prepolymer. The prepolymer was heated from room temperature to 250 C. over 1 hour in a nitrogen gas atmosphere, heated from 250 C. to 293 C. over 5 hours, and held at 293 C. for 5 hours to perform solid phase polymerization, followed by cooling, whereby a powdery liquid crystal polyester (2) was obtained. The flow starting temperature of the obtained liquid crystal polyester (2) was 319 C.

<Production of Liquid Crystal Polyester Composition>

Examples 1 to 6, Comparative Examples 1 to 11

[0132] The liquid crystal polyesters obtained in Production Examples 1 and 2 and the following components (fibrous fillers) were granulated at a cylinder temperature of 340 C. using a twin screw extruder (PCM-30 manufactured by Ikegai Ironworks Corp.) with the compositions shown in Tables 1 to 3 to obtain pelletized compositions. It should be noted that the average fiber lengths and the number average fiber diameters of the fibrous fillers are nominal values provided by the fibrous filler manufacturers.

(Fibrous Filler)

[0133] Filler (1): BS20/99 (manufactured by ITM Co., Ltd., alkaline earth silicate fiber alkaline earth silicate fiber, average fiber length: 20 m, number average fiber diameter: 3 m)

[0134] Filler (2): BS50/99 (manufactured by ITM Co., Ltd., alkaline earth silicate fiber, average fiber length: 50 m, number average fiber diameter: 3 m)

[0135] Filler (3): BS100/99 (manufactured by ITM Co., Ltd., alkaline earth silicate fiber, average fiber length: 100 m, number average fiber diameter: 3 m)

[0136] Filler (4): PF20E-001 (manufactured by Nitto Bosch Co., Ltd., glass fiber, average fiber length: 20 m, number average fiber diameter: 11 m)

[0137] Filler (5): EFH75-01 (manufactured by Central Glass Fiber Co., Ltd., glass fiber, average fiber length: 75 m, number average fiber diameter: 11 m)

[0138] Filler (6): PF40E-001 (manufactured by Nitto Bosch Co., Ltd., glass fiber, average fiber length: 40 m, number average fiber diameter: 11 m)

[0139] Filler (7): EFDE50-01 (manufactured by Central Glass Fiber Co., Ltd., glass fiber, average fiber length: 50 m, number average fiber diameter: 6 m)

[0140] Filler (8): EFH50-01 (manufactured by Central Glass Fiber Co., Ltd., glass fiber, average fiber length: 50 m, number average fiber diameter: 11 m)

[0141] Filler (9): EFK80-31 (manufactured by Central Glass Fiber Co., Ltd., glass fiber, average fiber length: 80 m, number average fiber diameter: 13 m)

[0142] In this example, it was confirmed that the number average fiber diameter of each filler did not change before and after kneading using the above extruder.

<Analysis of Fibrous Filler in Liquid Crystal Polyester Composition>

[0143] A portion of the composition obtained by the above method was used for the analysis of the fibrous fillers contained in the pellet. It should be noted that in the following analysis, the number of observations made (the number of fibrous fillers) in a micrograph was 400.

[Number Average Fiber Length of Fibrous Filler]

[0144] First, 1 g of the pellet was placed in a crucible and treated at 600 C. for 6 hours in an electric furnace to incinerate.

[0145] Next, the obtained residue was dispersed in methanol, and while being spread on a slide glass, a micrograph was taken at a magnification of 100 times. The lengths of the fibrous fillers were read from the obtained photograph, and the average value for the number of fibrous fillers (400) was calculated.

[Content of Long Fiber Having a Fiber Length of 80 m or More]

[0146] Using the measured value of the fiber length obtained in the above measurement, the content was calculated by dividing the number of long fibers having a fiber length of 80 m or more by the number of fibrous fillers (400).

<Surface Tape Peeling Test (Evaluation 1)>

[0147] After drying the composition obtained by the above method, injection molding was performed using an injection molding machine (model PS40E-SASE manufactured by Nissei Plastic Industrial Co., Ltd.) under the molding conditions of a cylinder temperature of 350 C., a mold temperature of 130 C., and an injection speed of 60% to obtain a test piece (resin molded body) having a length of 64 mm, a width of 64 mm, and a thickness of 1 mm. It should be noted that a 64 mm1 mm film gate was provided at an end of a cavity of the mold used.

[0148] An operation was carried out in which a tape (Cellotape (registered trademark) No. 405, manufactured by Nichiban Co., Ltd.) was adhered to the upper surface portion of the test piece along the flow direction of the liquid crystal polyester in the test piece over the entire length of the test piece, and was then quickly peeled off from one end of the tape towards the other end along the flow direction. This operation was defined as one cycle, and a tape peeling test was carried out in which a total of 20 cycles was repeated.

[0149] Next, the surface roughness Sa of a place in the test piece where the above test was performed was measured using a 3D shape measuring machine (VR3000 manufactured by Keyence Corporation). The results are shown in Tables 1 to 3.

<Izod Impact Strength (Evaluation 2)>

[0150] After drying the composition obtained by the above method, injection molding was performed using an injection molding machine (model PS40E-SASE manufactured by Nissei Plastic Industrial Co., Ltd.) under the molding conditions of a cylinder temperature of 350 C., a mold temperature of 130 C., and an injection speed of 60% to obtain a test piece having a length of 64 mm, a width of 12.7 mm, and a thickness of 6.4 mm.

[0151] The Izod impact strength of the obtained test piece was measured in accordance with ASTM D256. The results are shown in Tables 1 to 3.

TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Liquid crystal polyester (1) 100 100 100 100 Fibrous Filler (1) 42.9 filler Filler (2) 42.9 Filler (3) 42.9 Filler (4) 66.7 Number average fiber length 26 39 49 42 of fibrous fillers (m) Number average fiber diameter 3 3 3 11 of fibrous fillers (m) Content of long fibers (%) 1 5 9 7 Izod impact strength (J/m) 780 735 814 628 Surface roughness Sa after 0.44 0.48 0.44 0.40 tape peeling test (m)

TABLE-US-00002 TABLE 2 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex. 5 Liquid crystal polyester (1) 100 100 100 100 Fibrous filler Filler (5) 66.7 42.9 Filler (6) 66.7 Filler (7) 42.9 Filler (8) 42.9 Number average fiber length of 103 95 84 69 75 fibrous fillers (m) Number average fiber diameter 11 11 11 6 11 of fibrous fillers (m) Content of long fibers (%) 65 59 42 32 35 Izod impact strength (J/m) 511 578 544 656 581 Surface roughness Sa after tape 0.74 0.79 0.64 0.75 0.56 peeling test (m)

TABLE-US-00003 TABLE 3 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Comp. Ex. 6 Liquid cristal polyester (1) 100 100 100 100 100 100 Liquid crystal polyester (2) 100 Fibrous Filler (4) 23.2 66.7 106.2 133.3 66.7 filler Filler (7) 66.7 Filler (9) 66.7 Number average fiber length of 59 32 27 29 27 28 58 fibrous fillers (m) Number average fiber diameter 6 11 11 11 11 11 13 of fibrous fillers (m) Content of long fibers (%) 22 0 0 0 0 0 18 Izod impact strength (J/m) 469 1030 617 612 483 276 449 Surface roughness Sa after 0.55 0.54 0.49 0.47 0.51 0.50 0.68 tape peeling test (m)

[0152] As shown in Tables 1 and 3, the resin molded bodies obtained by molding the liquid crystal polyester compositions of Examples 1 to 10 to which the present invention was applied had smaller values of the surface roughness Sa after the tape peeling test, as compared with the resin molded bodies obtained by molding the liquid crystal polyester compositions of Comparative Examples 1 to 6. Therefore, in the resin molded bodies of Examples 1 to 10, it is presumed that the fibrous fillers hardly fall off and the generation of foreign substances is suppressed. Further, among the examples to which the present invention was applied, the resin molded bodies of Examples 1 to 3 in which the number average fiber diameters of the fibrous fillers were 5 m or less had higher Izod strength values than those of Comparative Examples 2, Comparative Example 4 and Comparative Example 5 in which the filling amount of the fibrous fillers was the same.

[0153] From the above results, it was shown that the present invention is useful.

INDUSTRIAL APPLICABILITY

[0154] According to the present invention, since a liquid crystal polyester composition and a resin molded body in which the generation of foreign substances is suppressed can be provided, the present invention is extremely useful industrially.