Thermoplastic elastomer powder for powder molding, powder molding method using the same and molded article thereof

• US 5,308,700 A
• Filed: 10/02/1991
• Issued: 05/03/1994
• Est. Priority Date: 10/03/1990
• Status: Expired due to Fees

• Current Assignee: Sumitomo Chemical Company Limited
• Original Assignee: Sumitomo Chemical Company Limited
• Inventors: Hikasa, Tadashi, Igarashi, Toshio, Hamanaka, Tatsuo, Mendori, Hiroaki, Shida, Yuu
• Primary Examiner(s): Seccuro, Jr., Carman J.
• Application Number:
  US07/769,734
• Time in Patent Office: 944 Days
• Field of Search: 525/193, 525/194, 525/240, 428/402
• US Class Current: 428/402
• CPC Class Codes: C08L 23/10 Homopolymers or copolymers of propene
• CPC Class Codes: C08L 23/14 Copolymers of propene C08L23/16 takes precedence
• CPC Class Codes: C08L 23/142 at least partially crystalline copolymers of propene with other olefins
• CPC Class Codes: C08L 23/16 Elastomeric ethene-propene or ethene-propene-diene copolymers, e.g. EPR and EPDM rubbers
• CPC Class Codes: C08L 2312/00 Crosslinking
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof
• CPC Class Codes: C08L 2666/06 Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof
• CPC Class Codes: C08L 83/00 Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 83/04 Polysiloxanes
• CPC Class Codes: Y10T 428/2982 Particulate matter [e.g., sphere, flake, etc.]

Abstract

A thermoplastic elastomer powder for powder molding, comprising an elastomer composition of an ethylene-α-olefin copolymer rubber and a polyolefin resin, wherein said elastomer composition has a complex dynamic viscosity η*(1) as measured at frequency of 1 radian/sec. in dynamic viscoelasticity measurement at 250° C., of 1.5×10⁵ poise or less, a Newtonian viscosity index n calculated from the following formula by using the complex dynamic viscosity η*(1) at a frequency of 1 radian/sec. and the complex dynamic viscosity η*(100) at a frequency of 100 radian/sec. of 0.67 or less, and a hardness (shore D) of 45 or less:

n={logη*(1)-logη*(100)}/2.

Claims

1. A thermoplastic elastomer powder for powder molding, comprising a partially crosslinked type elastomer composition comprising a mixture of an ethylene-α

-olefin copolymer rubber and a polyolefin ethylene resin dynamically crosslinked in the presence of a crosslinking agent, wherein said elastomer composition has a complex dynamic viscosity η

*(1) as measured at frequency of 1 radian/sec. in dynamic viscoelasticity measurement at 250°

C., of 1.5×

10⁵ poise or less, a Newtonian viscosity index n calculated from the following formula by using the complex dynamic viscosity η

*(1) at a frequency of 1 radian/sec. and the complex dynamic viscosity η

*(100) at a frequency of 100 radian/sec. of 0.67 or less, and a hardness (shore D) of 45 or less;

space="preserve" listing-type="equation">n={logη

*(1)-logη

*(100)}/2.

2. A thermoplastic elastomer powder as claimed in claim 1, wherein the ethylene-a-olefin copolymer rubber is an ethylene-propylene-nonconjugated diene copolymer rubber.

3. A thermoplastic elastomer powder as claimed in claim 1, wherein the ethylene-a-olefin copolymer rubber is an oil-extended olefin copolymer rubber comprising 30 to 120 parts by weight of a mineral oil type softener formulated per 100 parts by weight of an ethylene-α

-olefin copolymer rubber having a Mooney viscosity (ML₁₊₄ 100°

C.) of 130 to 350 as measured at 100°

C. according to ASTM D-927-57T.

4. A thermoplastic elastomer powder as claimed in claim 1, wherein the polyolefin resin is a polypropylene or a copolymer of propylene and an α

-olefin.

5. A thermoplastic elastomer powder as claimed in claim 1, wherein the polyolefin resin is a polyolefin resin having a melt flow rate (MFR) of 20 g/10 min. or more as measured at 230°

C. under a load of 2.16 kg according to JIS K-7210.

6. A thermoplastic elastomer powder as claimed in claim 1, wherein a crosslinking coagent is used in combination in a dynamic crosslinking.

7. A thermoplastic elastomer powder as claimed in claim 1, wherein the crosslinking agent is an organic peroxide.

8. A thermoplastic elastomer powder as claimed in claim 1, wherein the crosslinking agent is a dialkyl peroxide.

9. A thermoplastic elastomer powder as claimed in claim 6, wherein the crosslinking coagent is a bismaleimide compound.

10. A thermoplastic elastomer powder, comprising 0.2 to 20 parts by weight of a polyolefin resin powder added as a mutual adhesion preventive agent based on 100 parts by weight of the elastomer powder according to claim 1.

11. A thermoplastic elastomer powder, comprising 50 parts by weight or less of an ethylene-α

-olefin copolymer rubber and/or a polyolefin resin blended based on 100 parts by weight of the elastomer composition according to claim 1.

12. A thermoplastic elastomer powder, comprising 2 parts by weight or less of a methylpolysiloxane compound added based on 100 parts by weight of the elastomer composition or the elastomer powder according to claim 1.

13. A thermoplastic elastomer powder as claimed in claim 12, wherein the methylpolysiloxane compound is a methylpolysiloxane compound having a viscosity at 25°

C. of 20 centistokes or more.

14. A thermoplastic elastomer powder as claimed in claim 12, wherein the methylpolysiloxane compound is dimethylpolysiloxane.

15. A thermoplastic elastomer powder as claimed in claim 1, which is pulverized until 95% by weight or more thereof passes through a 32 mesh Tyler standard sieve.