Liquid-crystalline polyester resin composition and connector using the same

• US 8,202,448 B2
• Filed: 12/23/2009
• Issued: 06/19/2012
• Est. Priority Date: 12/25/2008
• Status: Active Grant

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Fukuhara, Yoshiyuki, Yamauchi, Hiroyasu
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US12/646,380
• Publication Number:
  US 20100163796A1
• Time in Patent Office: 909 Days
• Field of Search: 252/299.01, 252/299.66, 252/299.67, 252/299.5, 524/449, 524/599
• US Class Current: 252/299.66
• CPC Class Codes: C09K 19/3809 Polyesters; Polyester derivatives, e.g. polyamides

Abstract

A liquid-crystalline polyester resin composition is provided including a liquid-crystalline polyester obtained by polymerizing monomers of an aromatic hydroxycarboxylic acid in the presence of an imidazole compound. The composition also includes a mica which is a muscovite and has a volume average particle diameter of 40 μm or less and a specific surface area of 6 m²/g or less, the amount of the mica being 15 to 100 parts by weight based on 100 parts by weight of the liquid-crystalline polyester. The liquid-crystalline polyester resin composition has melt fluidity sufficient to be molded into a connector having an ultra-thin wall thickness portion. The resulting connector has sufficiently suppressed warp and sufficient soldering resistance.

Claims

1. A liquid-crystalline polyester resin composition comprising a liquid-crystalline polyester obtained by polymerizing monomers comprising an aromatic hydroxycarboxylic acid in the presence of an imidazole compound, and a mica which comprises a muscovite and has a volume average particle diameter of 40 μ

m or less and a specific surface area of 6 m²/g or less, the amount of the mica being 15 to 100 parts by weight based on 100 pats by weight of the liquid-crystalline polyester.

2. The liquid-crystalline polyester resin composition according to claim 1, wherein the imidazole compound is a compound represented by the following formula (1):

3. The liquid-crystalline polyester resin composition according to claim 1, wherein the liquid-crystalline polyester is a liquid-crystalline polyester obtained by a method comprising the steps of:

acylating a phenolic hydroxyl group of an aromatic hydroxycarboxylic acid and a phenolic hydroxyl group of an aromatic diol with a fatty acid anhydride to obtain an acylated aromatic hydroxycarboxylic acid and an acylated aromatic diol; and

polymerizing the acylated aromatic hydroxycarboxylic acid, an aromatic dicarboxylic acid and the acylated aromatic diol in the presence of an imidazole compound thorough transesterification to obtain a liquid-crystalline polyester.

4. The liquid-crystalline polyester resin composition according to claim 3, wherein the aromatic hydroxycarboxylic acid is parahydroxybenzoic acid;

the aromatic dicarboxylic acid is terephthalic acid and/or isophthalic acid; and

the aromatic diol is 4,4′

-dihydroxybiphenyl.

5. The liquid-crystalline polyester resin composition according to claim 1, wherein the liquid-crystalline polyester has a flow initiation temperature of from 270 to 400°

C.

6. The liquid-crystalline polyester resin composition according to claim 1, wherein the liquid-crystalline polyester is a liquid-crystalline polyester mixture containing a plurality of liquid-crystalline polyesters, the flow initiation temperature of a first liquid-crystalline polyester having the highest flow initiation temperature among the plurality of liquid-crystalline polyesters is within a range of from 300 to 400°

C., the flow initiation temperature of a second liquid-crystalline polyester having the lowest flow initiation temperature among the plurality of liquid-crystalline polyesters is within a range of from 260 to 350°

C., and the liquid-crystalline polyester mixture contains the second liquid-crystalline polyester in an amount of from 10 to 150 parts by weight based on 100 parts by weight of the first liquid-crystalline polyester.

7. The liquid-crystalline polyester resin composition according to claim 6, wherein the value obtained by subtracting the flow initiation temperature of the second liquid-crystalline polyester from the flow initiation temperature of the first liquid-crystalline polyester is within a range of from 20 to 60°

C.

8. A connector obtained by molding the liquid-crystalline polyester resin composition according to claim 1.

9. The connector according to claim 8, which has a thin-wall portion having a wall thickness of 0.1 mm or less.

13. The liquid-crystalline polyester resin composition according to claim 1, wherein the mica is a mica consisting essentially of a muscovite.

10. A method for producing a liquid-crystalline polyester resin composition, which comprises the steps of:

polymerizing monomers comprising an aromatic hydroxycarboxylic acid in the presence of an imidazole compound to prepare a liquid-crystalline polyester; and

melt-mixing the liquid-crystalline polyester with a mica which comprises a muscovite and has a volume average particle diameter of 40 μ

m or less and a specific surface area of 6 m²/g or less, the amount of the mica being 15 to 100 parts by weight based on 100 pats by weight of the liquid-crystalline polyester.

11. The method according to claim 10, wherein the imidazole compound is a compound represented by the following formula (1):

12. The method according to claim 10, wherein the mica contains adherent water in the amount of 0.3% by weight or less based on the mica.