Resin molded article and method for producing the same

• US 7,740,770 B2
• Filed: 02/21/2008
• Issued: 06/22/2010
• Est. Priority Date: 02/26/2007
• Status: Active Grant

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Mizumoto, Koichi, Harada, Hiroshi
• Primary Examiner(s): Visconti; Geraldina
• Application Number:
  US12/071,494
• Publication Number:
  US 20080203358A1
• Time in Patent Office: 852 Days
• Field of Search: 252/299.01, 252/299.1, 428/299.1, 428/1.1, 264/500, 524/296, 430/20
• US Class Current: 252/299.01
• CPC Class Codes: B29C 45/0001 characterised by the choice of material
• CPC Class Codes: B29C 45/0005 using fibre reinforcements
• CPC Class Codes: B29K 2105/0079 Liquid crystals
• CPC Class Codes: B29K 2105/12 of short lengths, e.g. chopped filaments, staple fibres or bristles
• CPC Class Codes: C08K 7/02 Fibres or whiskers
• CPC Class Codes: C09K 2323/00 Functional layers of liquid crystal optical display excluding electroactive liquid crystal layer characterised by chemical composition

Abstract

The present invention provides for a resin molded article comprising a liquid crystalline polymer and a fibrous filler, the article having a surface with difference of 0.4 μm or smaller in a surface roughness expressed by Ra value measured before and after repeating 30 times the operation of pasting and peeling a tape having an adhesive power of 4.0 N/mm. The resin molded article is excellent in mechanical strength when used in an electric/electronic component or in an optical apparatus.

Claims

1. A resin molded article comprising a liquid crystalline polymer and a fibrous filler having a number-average fiber length of 30 to 200 μ

m, the article having a surface with difference of 0.4 μ

m or smaller in a surface roughness expressed by Ra value measured before and after repeating 30 times the operation of pasting and peeling a tape having an adhesive power of 4.0 N/mm.

2. The resin molded article according to claim 1 comprising 5 to 250 parts by weight of the fibrous filler on the basis of 100 parts by weight of the liquid crystalline polymer.

3. The resin molded article according to claim 1, wherein the liquid crystalline polymer comprises a liquid crystalline polymer selected from group (a), (b) and (c) below:

(a) polyester, polyesteramide and polyamide having a Structural Unit (I) below and/or a Structural Unit (II) below;

(b) polyester and polyesteramide having a Structural Unit (III) below, and a Structural Unit (IV) below and a structural unit selected from the Structural Units (I) and (II); and

(c) polyester and polyesteramide having the Structural Unit (III);

a structural unit selected from the Structural Units (D and (II); and

a structural unit selected from the Structural Unit (IV), a Structural Unit (V) and a Structural Unit (VI),

4. The resin molded article according to claim 3, wherein the liquid crystalline polymer comprises a liquid crystalline polymer selected from the group (a).

5. The resin molded article according to claim 3, wherein the liquid crystalline polymer comprises a liquid crystalline polymer selected from the group (b) in which the total amount of the bivalent aromatic group of the polymer is 60% by mole or more on the basis of the total amount of Ar¹, Ar², Ar³ and Ar⁴ of the polymer.

6. The resin molded article according to claim 3, wherein the liquid crystalline polymer comprises a liquid crystalline polymer selected from the group (c) in which the total amount of the bivalent aromatic group of the polymer is 60% by mole or more on the basis of the total amount of Ar¹, Ar², Ar³, Ar⁴, Ar⁵ and Ar⁶ of the polymer.

7. The resin molded article according to claim 1, wherein the liquid crystalline polymer is a liquid crystalline polyester having:

a structural unit derived from aromatic hydroxy carboxylic acid (I-1) and/or (I-2) below,

a structural unit derived from aromatic dicarboxylic acid selected from aromatic dicarboxylic acids (III-1), (III-2) and (III-3) below, and

a structural unit derived from aromatic diol selected from aromatic diols (IV-1), (IV-2), (IV-3) and (IV-4) below,

8. The resin molded article according to claim 1, wherein the fibrous filler is a fibrous filler which has not been treated with a coupling agent.

9. A method for producing the resin molded article of claim 1, the method comprising the step of molding a resin composition pellet which contains a liquid crystalline polymer and a fibrous filler having a fiber diameter of 5 to 15 μ

m and a number-average fiber length of 30 to 200 μ

m.

10. A method for producing the resin molded article of claim 1, the method comprising the steps of:

mixing and pelletizing a liquid crystalline polymer and a fibrous filler to obtain a resin composition pellet comprising the liquid crystalline polymer and the fibrous filler;

melting the resin composition pellet at a temperature of from a temperature higher than the flow starting temperature of the resin composition by 30°

C. to a temperature higher than the flow starting temperature by 80°

C. to obtain a melted resin composition; and

injecting the melted resin composition into a mold having a set temperature of 80°

C. or higher to mold the composition so as to obtain a resin molded article.

11. A component for a camera module, the component comprising the resin molded article of claim 1.