Thermoplastic resin composition, injection molding method thereof, and injection molded article

• US 6,010,760 A
• Filed: 06/17/1997
• Issued: 01/04/2000
• Est. Priority Date: 10/18/1994
• Status: Expired due to Term

• Current Assignee: Polyplastics Co., Ltd. (Daicel Corporation)
• Original Assignee: Polyplastics Co., Ltd. (Daicel Corporation)
• Inventors: Migita, Ayako, Aketa, Tomoyuki, Ishikawa, Takayuki, Miyazaki, Hirotaka, Kobayashi, Kazuhito, Murakami, Haruji
• Primary Examiner(s): Short, Patricia A.
• Application Number:
  US08/817,346
• Time in Patent Office: 931 Days
• Field of Search: 428/35.7, 428/36.92, 428/339, 428/297.4, 264/328.1, 264/328.14, 525/67, 525/132, 525/400, 525/425, 525/437, 525/439, 525/444, 525/450, 524/128, 524/150, 524/151, 524/153
• US Class Current: 428/36.92
• CPC Class Codes: B29C 45/0001 characterised by the choice of material
• CPC Class Codes: B29C 45/2708 Gates B29C45/2703 takes precedence
• CPC Class Codes: B29K 2105/0079 Liquid crystals
• CPC Class Codes: C08G 2261/312 Non-condensed aromatic systems, e.g. benzene
• CPC Class Codes: C08L 101/00 Compositions of unspecified macromolecular compounds
• CPC Class Codes: C08L 2205/12 containing additives being liquid crystalline or anisotropic in the melt
• CPC Class Codes: C08L 23/10 Homopolymers or copolymers of propene
• CPC Class Codes: C08L 25/06 Polystyrene
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/14 Macromolecular compounds according to C08L59/00 - C08L87/00; Derivatives thereof
• CPC Class Codes: C08L 2666/18 Polyesters or polycarbonates according to C08L67/00 - C08L69/00; Derivatives thereof
• CPC Class Codes: C08L 33/06 of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
• CPC Class Codes: C08L 55/02 ABS [Acrylonitrile-Butadiene-Styrene] polymers
• CPC Class Codes: C08L 59/00 Compositions of polyacetals; Compositions of derivatives of polyacetals of polyvinyl acetals C08L29/14
• CPC Class Codes: C08L 65/02 Polyphenylenes
• CPC Class Codes: C08L 67/00 Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain of polyester-amides C08L77/12; of polyester-imides C08L79/08; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 67/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds C08L67/06 takes precedence
• CPC Class Codes: C08L 67/03 the dicarboxylic acids and dihydroxy compounds having the carboxyl- and the hydroxy groups directly linked to aromatic rings
• CPC Class Codes: C08L 67/04 Polyesters derived from hydroxycarboxylic acids, e.g. lactones C08L67/06 takes precedence
• CPC Class Codes: C08L 69/00 Compositions of polycarbonates; Compositions of derivatives of polycarbonates
• CPC Class Codes: C08L 77/00 : Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain of polyhydrazides C08L79/06; of polyamideimides or polyamide acids C08L79/08; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 81/02 : Polythioethers; Polythioether-ethers
• CPC Class Codes: Y10T 428/1352 : Polymer or resin containing [i.e., natural or synthetic]
• CPC Class Codes: Y10T 428/1397 : Single layer [continuous layer]
• CPC Class Codes: Y10T 428/24994 : Fiber embedded in or on the surface of a polymeric matrix
• CPC Class Codes: Y10T 428/269 : including synthetic resin or polymer layer or component

Abstract

A thermoplastic resin composition comprising a thermoplastic resin (A) not forming an anisotropic melt phase and a liquid crystal polymer (B) capable of forming an anisotropic melt phase, an injection molding method thereof and an injection molded article capable of providing a thin molded article having excellent mechanical strength. A thermoplastic resin composition (C) comprises 99 to 50 wt. % of the thermoplastic resin (A) and 1 to 50 wt. % of the liquid crystal polymer (B). The liquid crystal polymer (B) is microscopically dispersed in an island form in the matrix phase of the thermoplastic resin (A) so that when the composition (C) is heat-treated at a temperature not lower than the melting point of the liquid crystal polymer (B) under a non-load state and is then cooled, the liquid crystal polymer (B) has a weight average particle diameter within the range of 10 to 40 micrometers and at least 80 wt. % thereof has a particle diameter within the range of 0.5 to 60 micrometers. The injection molding method comprises carrying out injection molding of the thermoplastic resin composition (C) at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B) and at a gate passage rate of the molten resin of at least 500 m/min, and an injection molded article characterized in that the liquid crystal polymer (B) is dispersed in a fibrous form in the matrix phase of the thermoplastic resin (A) at a mean aspect ratio of at least 6.

Claims

1. An injection molding method which comprises the steps of:

a) blending 99 to 50 wt % of a thermoplastic resin (A) not forming an anisotropic melt phase, 1 to 50 wt % of a liquid crystal polymer (B) capable of forming an anisotropic melt phase (the total of the two accounting for 100 wt %) and 0.01 to 0.5 parts by weight of a phosphorus-containing compound with respect to 100 parts by weight in total of the thermoplastic resin (A) and the liquid crystal polymer (B), and kneading the blend to obtain a thermoplastic resin composition, wherein the thermoplastic resin composition is characterized in that the liquid crystal polymer (B) is microscopically dispersed in the form of islands in the matrix phase of the thermoplastic resin (A) so that when the thermoplastic resin composition is heat-treated at a temperature not lower than the melting point of the liquid crystal polymer (B) under a non-load state and is then cooled, the liquid crystal polymer (B) has a weight average particle diameter within the range of 10 to 40 micrometers and at least 80 wt. % thereof has a particle diameter within the range of 0.5 to 60 micrometers; and

b) injection molding said thermoplastic resin composition, at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B) and at a gate passage rate of the molten resin of at least 500 m/min to obtain an injection molded article.

3. An injection molding method as described in claim 1 or 2, characterized in that said injection molding is performed at a processing temperature greater than or equal to the melting point of the liquid crystal polymer (B) and at a gate passage rate of the molten resin of at least 500 m/min.

4. An injection molding method as described in claim 1 or 2, characterized in that said injection molding is performed at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B) and below the melting point thereof and at a gate passage rate of the molten resin of at least 500 m/min.

5. An injection molding method as described in claim 1 or 2, characterized in that said injection molding is performed through use of a mold for injection molding having a ratio S_R /S_G of between 3 and 150, wherein S_G and S_R represent the cross sectional area of a gate of the mold and the cross sectional area of a runner of the mold, respectively.

2. An injection molding method characterized in that a thermoplastic resin composition comprising 99 to 50 wt. % of a thermoplastic resin (A) not forming an anisotropic melt phase and 1 to 50 wt. % of a liquid crystal polymer (B) capable of forming an anisotropic melt phase (the total of the two accounting for 100 wt. %) and 0.01 to 0.5 parts by weight of a phosphorus-containing compound with respect to 100 parts by weight in total of the thermoplastic resin (A) and the liquid crystal polymer (B) is injection-molded at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B) and at a gate passage rate of the molten resin of at least 500 m/min.

6. An injection molded article formed of a thermoplastic resin composition comprising 99 to 50 wt. % of a thermoplastic resin (A) not forming an anisotropic melt phase, 1 to 50 wt. % of a liquid crystal polymer (B) capable of forming an anisotropic melt phase (the total of the two accounting for 100 wt. %) and 0.01 to 0.5 parts by weight of a phosphorus-containing compound with respect to 100 parts by weight in total of the thermoplastic resin (A) and the liquid crystal polymer (B), wherein the liquid crystal polymer (B) is dispersed in a fibrous form in the matrix phase of the thermoplastic resin (A) at a mean aspect ratio of at least 6, and the liquid crystal polymer (B) is microscopically dispersed in the form of islands in the matrix phase of the thermoplastic resin (A) so that when the injection-molded article is heat-treated at a temperature not lower than the melting point of the liquid crystal polymer (B) under a non-load state and is then cooled, the liquid crystal polymer (B) has a weight average particle diameter within the range of 10 to 40 micrometers and at least 80 wt. % thereof has a particle diameter within the range of 0.5 to 60 micrometers and said injection molded article is molded at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B).

7. An injection molded article as described in claim 6, wherein the viscosity ratio (Aη

/Bη

) of thermoplastic resin (A) to liquid crystal polymer (B) is at least 0.1 when measured at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B) and at a shear rate of 1,200 sec^-1.

8. An injection molded article as described in claim 7, wherein the viscosity ratio (Aη

/Bη

) is at least 0.1 and not more than 6.

9. An injection molded article as described in claim 6, wherein the thermoplastic resin (A) is polyester resin.

10. An injection molded article as described in claim 9, wherein the polyester resin is polycarbonate resin.

11. An injection molded article as described in claim 6, wherein the thermoplastic resin (A) is a mixture of polycarbonate resin and ABS resin.

12. An injection molded article as described in claim 6, wherein the thermoplastic resin (A) is a mixture of polycarbonate resin, and polyalkylene terephthalate resin and/or amorphous polyarylate resin.

13. An injection molded article as described in claim 6, wherein the thermoplastic resin (A) is polyarylene sulfide resin.

14. An injection molded article formed of a thermoplastic resin composition comprising 99 to 50 wt. % of a thermoplastic resin (A) not forming an anisotropic melt phase, 1 to 50 wt. % of a liquid crystal polymer (B) capable of forming an anisotropic melt phase (the total of the two accounting for 100 wt. %) and 0.01 to 0.5 parts by weight of a phosphorus-containing compound with respect to 100 parts by weight in total of the thermoplastic resin (A) and the liquid crystal polymer (B), wherein the liquid crystal polymer (B) is dispersed in a fibrous form in the matrix phase of the thermoplastic resin (A) at a mean aspect ratio of at least 6;

the liquid crystal polymer (B) is microscopically dispersed in the form of islands in the matrix phase of the thermoplastic resin (A) so that when the injection-molded article is heat-treated at a temperature not lower than the melting point of the liquid crystal polymer (B) under a non-load state and is then cooled, the liquid crystal polymer (B) has a weight average particle diameter within the range of 10 to 40 micrometers and at least 80 wt. % thereof has a particle diameter within the range of 0.5 to 60 micrometers;

the flexural modulus of the injection molded article is at least 40,000 kg/cm² as measured in accordance with ASTM D790; and

the melt viscosity of a melt obtained through remelting the injection molded article is within the range from 400 to 2,500 poise when measured at a temperature 20°

C. higher than the melting point of the liquid crystal polymer (B) and at a shear rate of 1,200 sec^-1.

15. An injection molded article as described in claim 14, wherein the thermoplastic resin (A) is polyester resin.

16. An injection molded article as described in claim 15, which is a thin wall article in which 50% or more of the walls of the molded article have a thickness of 1 mm or less.

17. An injection molded article as described in claim 16, which is a housing of an electronic device.

18. An injection molded article as described in claim 14, wherein the thermoplastic resin (A) is polycarbonate resin.

19. An injection molded article as described in claim 14, which is a thin wall article in which 50% or more of the walls of the molded article have a thickness of 1 mm or less.

20. An injection molded article as described in claim 18, which is a housing of an electronic device.

21. An injection molded article as described in claim 20, wherein the electronic device is a personal computer, a cellular phone, a connector, a CD pickup component, a hard disk, or their peripheral components.

22. An injection molding method of a thermoplastic resin composition which comprises the steps of:

(a) blending 99 to 50 wt. % of a thermoplastic resin (A'"'"') having a melting point or a softening point of not higher than 210°

C. and being formed of one or more members selected from among polyolefin (co)polymers, styrene (co)polymers, polyamide (co)polymers, polyacrylate, and polyacetal (co)polymers, 1 to 50 wt. % of a liquid crystal polymer (B'"'"') having a flow beginning temperature of 80-120°

C. and being capable of forming an anisotropic melt phase (the total of the two accounting for 100 wt. % and 0.01 to 0.5 parts by weight of a phosphorus-containing compound with respect to 100 parts by weight in total of the thermoplastic resin (A'"'"') and the liquid crystal polymer (B'"'"'), and kneading the blend to obtain a thermoplastic resin composition; and

(b) injection-molding said thermoplastic resin composition at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B'"'"') and at a gate passage rate of the molten resin of at least 500 m/min.

23. An injection molding method of a thermoplastic resin composition as described in claim 22, wherein the viscosity ratio (A'"'"'η

/B'"'"'η

) of thermoplastic resin (A'"'"') to liquid crystal polymer (B'"'"') is at least 0.1 when measured at a processing temperature greater than or equal to the flow beginning temperature of the liquid crystal polymer (B'"'"') and at a shear rate of 1,200 sec^-1.

24. An injection molding method of a thermoplastic resin composition as described in claim 22, wherein the liquid crystal polymer (B'"'"') is formed of a structural unit of aromatic hydroxycarboxylic acid/aliphatic diol/aromatic dicarboxylic acid.

25. An injection molding method of a thermoplastic resin composition as described in claim 22, wherein the liquid crystal polymer (B'"'"') is formed of a structural unit of aromatic hydroxycarboxylic acid/ethylene glycol/terephthalic acid, and the aromatic hydroxycarboxylic acid content is between 30 and 70 mole % based on the entirety of the structural monomers.

26. An injection molding method of a thermoplastic resin composition as described in claim 25, wherein the aromatic hydroxycarboxylic acid is p-hydroxybenzoic acid.

27. An injection molding method of a thermoplastic resin composition as described in claim 25, wherein the aromatic hydroxycarboxylic acid comprises p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.

28. An injection molding method of a thermoplastic resin composition as described in claim 22, characterized in that a mold for injection molding having a ratio S_R /S_G of between 3 and 150, wherein S_G and S_R represent the cross sectional area of a gate of the mold and the cross sectional area of a runner of the mold, respectively, is used.

29. An injection molded article formed of a thermoplastic resin composition comprising 99 to 50 wt. % of a thermoplastic resin (A'"'"') having a melting point or a softening point of not higher than 210°

C. and being formed of one or more members selected from polyolefin (co)polymers, styrene (co)polymers, polyamide (co)polymers, polyacrylate, and polyacetal (co)polymers, 1 to 50 wt. % of a liquid crystal polymer (B'"'"') having a flow beginning temperature of 80-210°

C. and being capable of forming an anisotropic melt phase (the total of the two accounting for 100 wt. %) and 0.01 to 0.5 parts by weight of a phosphorus-containing compound with respect to 100 parts by weight in total of the thermoplastic resin (A'"'"') and the liquid crystal polymer (B'"'"'), wherein the liquid crystal polymer (B'"'"') is dispersed in a fibrous form in the matrix phase of the thermoplastic resin (A'"'"') at a mean aspect ratio of at least 6, and that the liquid crystal polymer (B'"'"') is microscopically dispersed in the form of islands in the matrix phase of the thermoplastic resin (A'"'"') so that when the injection-molded article is heat-treated at a temperature not lower than the melting point of the liquid crystal polymer (B'"'"') under a non-load state and is then cooled, the liquid crystal polymer (B'"'"') has a weight average particle diameter within the range of 10 to 40 micrometers and at least 80 wt. % thereof has a particle diameter within the range of 0.5 to 60 micrometers.