LIQUID CRYSTAL POLYMER COMPOSITION, LIQUID CRYSTAL POLYMER MOLDED BODY, AND CAMERA MODULE

Abstract

Provided is a liquid crystal polymer composition having a low coefficient of static friction and a low coefficient of kinetic friction both during sliding between a liquid crystal polymer molded body and a metallic material and during sliding between liquid crystal polymer molded bodies. The liquid crystal polymer composition contains a liquid crystal polymer (A), a polytetrafluoroethylene resin (B), and barium sulfate (C).

Claims

1. A liquid crystal polymer composition containing a liquid crystal polymer (A), a polytetrafluoroethylene resin (B), and barium sulfate (C).

2. The liquid crystal polymer composition according to claim 1, wherein the liquid crystal polymer (A) is liquid crystal polyester.

3. The liquid crystal polymer composition according to claim 1, wherein the polytetrafluoroethylene resin (B) has an average particle diameter of 0.1 μm to 100 μm.

4. The liquid crystal polymer composition according to claim 1, wherein the barium sulfate (C) has an average particle diameter of 0.1 μm to 50 μm.

5. The liquid crystal polymer composition according to claim 1, wherein a content of the polytetrafluoroethylene resin (B) is 1% by mass to 30% by mass in a total amount of 100% by mass of the liquid crystal polymer composition.

6. The liquid crystal polymer composition according to claim 1, wherein a content of the barium sulfate (C) is 1% by mass to 30% by mass in a total amount of 100% by mass of the liquid crystal polymer composition.

7. The liquid crystal polymer composition according to claim 1, wherein a mass ratio ((B):(C)) between the polytetrafluoroethylene resin (B) and the barium sulfate (C) is 20:80 to 80:20.

8. The liquid crystal polymer composition according to claim 1, further containing reinforcing fibers (D).

9. The liquid crystal polymer composition according to claim 1, being a resin composition for a camera module.

10. A liquid crystal polymer molded body being a molded body of the liquid crystal polymer composition according to claim 1.

11. The liquid crystal polymer molded body according to claim 10, being a sliding member.

12. A camera module comprising the liquid crystal polymer molded body according to claim 10.

Description

EXAMPLES

[0102] Hereinafter, a detailed description will be given of the present invention with reference to working examples and comparative examples, but the present invention is not at all limited to these examples. Specific raw materials used in the working examples and comparative examples are as follows.

[0103] Liquid crystal polymer: melt viscosity of 2.0×10.sup.3 Pa.Math.s, trade name “LAPEROS C950RX” manufactured by Polyplastics Co., Ltd.

[0104] Polytetrafluoroethylene resin (PTFE): average particle diameter of 8 μm, MFR value of 50 g/10 min or more, melting point of 324° C., trade name “TF 9205” manufactured by 3M

[0105] Barium sulfate: average particle diameter of 1 μm, trade name “Precipitated Barium Sulfate 300” manufactured by Sakai Chemical Industry Co., Ltd.

[0106] Calcium carbonate: average particle diameter of 3 μm, trade name “SS#80” manufactured by Nitto Funka Kogyo K.K.

[0107] Potassium titanate fibers: average fiber length of 15 μm, average fiber diameter of 0.5 μm, trade name “TISMO N102” manufactured by Otsuka Chemical Co., Ltd.

[0108] Glass fibers: average fiber diameter of 7 μm, average fiber length of 3 mm, trade name “ECS 03 T-289DE” manufactured by Nippon Electric Glass Co., Ltd.

[0109] The melt viscosity of the liquid crystal polymer was measured with a melt viscosity measurement device (trade name “Capilograph 1D” manufactured by Toyo Seiki Seisaku-sho, Ltd.) using a capillary rheometer with 1.0 mm in diameter and 10 mm in length under conditions at a temperature of 300° C. and a shear rate of 1.0×10.sup.3 sec.sup.−1.

[0110] The MFR value of PTFE was measured under conditions at a temperature of 372° C. and a load of 5 kg for a residence time of five minutes in conformity with JIS K 7210.

[0111] The melting point of PTFE was measured with a differential calorimeter (trade name “DSC7000X” manufactured by Hitachi High-Tech Science Corporation) by putting 10 mg of sample into a measurement aluminum cell, increasing the temperature from room temperature to 50° C. at a rate of temperature increase of 10° C./min under conditions at a nitrogen flow rate of 100 ml/min, holding the temperature at 50° C. for five minutes, and then increasing the temperature to 400° C. at a rate of temperature increase of 10° C./min.

[0112] The average particle diameter was measured with a laser diffraction particle size distribution measurement device (trade name “SALD-2100” manufactured by Shimadzu Corporation).

Example 1 to Example 2 and Comparative Example 1 to Comparative Example 4

[0113] Materials were melt-kneaded in each composition ratio shown in Table 1 using a biaxial extruder, thus producing pellets. The cylinder temperature of the biaxial extruder was 345° C.

[0114] The obtained pellets were molded, with an injection molder, into a molded body A (with 90 mm in height, 50 mm in width, and 3 mm in thickness), a molded body B (with 3 mm in height, 10 mm in width, and 3 mm in thickness), a molded body C (with 9 mm in height, 9 mm in width, and 1 mm in thickness), and a JIS test piece, thus obtaining evaluation samples. The cylinder temperature of the injection molder was 320° C. and the mold temperature thereof was 120° C.

[0115] <Evaluations>

[0116] (Coefficient of Friction)

[0117] The evaluation sample was measured in terms of coefficient of static friction (μs) and coefficient of kinetic friction (μk) at a load of 50 g and a load of 300 g with a static friction tester TRIBOSTAR TS501 (manufactured by Kyowa Interface Science Co., Ltd.) under conditions at a velocity of 0.2 mm/sec for a travel distance of 10 mm. The sliding test between the same materials (liquid crystal polymer molded bodies) was conducted in the manner of sliding the molded body A and the molded body B (sliding area: 3 mm in height by 10 mm in width). The sliding test between the evaluation sample and the hard metal was conducted in the manner of sliding the molded body A and a stainless steel ball (SUS304 with a diameter of 3 mm). The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Composition liquid crystal polymer 65 65 65 75 75 75 (parts by mass) PTFE 10 10 10 10 barium sulfate 10 10 10 calcium carbonate 10 10 potassium titanate fibers 15 15 15 15 15 glass fibers 15 Evalu- Coefficient of Load Counter material: 0.128 0.134 0.149 0.169 0.171 0.152 ations Static Friction 50 g Same material (μ s) Counter material: SUS 0.098 0.102 0.125 0.113 0.113 0.159 Load Counter material: 0.105 0.113 0.151 0.135 0.132 0.151 300 g Same material Counter material: SUS 0.080 0.084 0.085 0.086 0.100 0.137 Coefficient of Load Counter material: 0.096 0.108 0.113 0.117 0.103 0.120 Kinetic Friction 50 g Same material (μ k) Counter material: SUS 0.070 0.074 0.093 0.083 0.094 0.113 Load Counter material: 0.076 0.078 0.086 0.101 0.090 0.120 300 g Same material Counter material: SUS 0.067 0.060 0.074 0.072 0.087 0.114

[0118] As is obvious from Table 1, it can be seen that, in Examples 1 and 2 each containing all of the liquid crystal polymer, polytetrafluoroethylene resin, and barium sulfate, the coefficient of static friction and the coefficient of kinetic friction were lowered in both the cases of sliding between the liquid crystal polymer molded body and the metallic material and sliding between the liquid crystal polymer molded bodies. In contrast, it can be seen that, in Comparative Examples 1 to 4 not containing at least one of the polytetrafluoroethylene resin and barium sulfate, the coefficient of static friction and the coefficient of kinetic friction could not sufficient be lowered in both the cases of sliding between the liquid crystal polymer molded body and the metallic material and sliding between the liquid crystal polymer molded bodies. Furthermore, it can be seen that, in Examples 1 and 2, the coefficient of static friction could significantly be lowered as compared with Comparative Examples 1 to 4.

[0119] Comparative Example 2 contains the liquid crystal polymer and the polytetrafluoroethylene resin. Comparative Example 3 contains the liquid crystal polymer and barium sulfate. In other words, Comparative Examples 2 and 3 contain, in addition to the liquid crystal polymer, one of the polytetrafluoroethylene resin and barium sulfate. However, the coefficient of static friction and the coefficient of kinetic friction could not sufficiently be lowered in both the cases of sliding between the liquid crystal polymer molded body and the metallic material and sliding between the liquid crystal polymer molded bodies.

[0120] Unlike the above, Example 1 contains, in addition to the liquid crystal polymer, both of the polytetrafluoroethylene resin and barium sulfate and, thus, the coefficient of static friction and the coefficient of kinetic friction could sufficiently be lowered in both the cases of sliding between the liquid crystal polymer molded body and the metallic material and sliding between the liquid crystal polymer molded bodies. This shows that when a liquid crystal polymer composition contains, in addition to the liquid crystal polymer, both of the polytetrafluoroethylene resin and barium sulfate, an unexpected effect that would not be obtained when it contains, in addition to the liquid crystal polymer, one of the polytetrafluoroethylene resin and barium sulfate can be obtained.

[0121] (Amount of Dust Produced)

[0122] Twenty molded bodies C were measured in terms of weight and then loaded into a container (made of SUS) having a width of 50 mm and the container was placed in a vibrator and vibrated therein at 60 Hz for five minutes. After the end of the vibration, the twenty molded bodies C were picked up from the container and measured in terms of weight. The difference in weight of the molded bodies between before and after the vibration test was calculated as an amount of dust produced. The results are shown in Table 2.

[0123] (Bending Strength and Bending Modulus of Elasticity)

[0124] The samples were subjected to a 60 mm-span three-point bending test with a tester Autograph AG-5000 (manufactured by Shimadzu Corporation) in conformity with JIS K 7271 to measure their bending strengths and bending moduli of elasticity. The results are shown in Table 2.

[0125] (Notched IZOD Impact Value)

[0126] The No. 1 test pieces as the evaluation samples were measured in conformity with JIS K 7110. The results are shown in Table 2.

TABLE-US-00002 TABLE 2 Comp. Ex. 1 Ex. 2 Ex. 1 Evaluations Amount of Weight 0.60 0.78 0.70 Dust Produced Reduction Rate % Bending Strength (MPa) 164 163 161 Bending Modulus of 9.3 9.4 9.5 Elasticity (GPa) IZOD (J/m) 30 41 28

[0127] It can be seen from Table 2 that the molded bodies obtained in Examples 1 and 2 exhibited good results in terms of amount of dust produced, bending strength, bending modulus of elasticity, and impact resistance. Therefore, the molded body of the liquid crystal polymer composition according to the present invention can be suitably used in, for example, electronic optical components being constituents of a camera module.