Method for injection expansion molding of thermoplastic resin

(54) METHOD FOR INJECTION EXPANSION MOLDING OF THERMOPLASTIC RESIN

(75) Inventors: Akio Okamoto, Sanyouonoda (JP);

Kazuaki Miyamoto, Ube (JP)

(73) Assignee: Ube Machinery Corporation, Ltd.,

Ube-shi (JP)

( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 542 days.

(21) Appl.No.: 11/579,414

(22) PCT Filed: Jul. 21, 2005

(56) References Cited

U.S. PATENT DOCUMENTS

4,144,297 A * 3/1979 Tomar 264/45.5

4,596,832 A * 6/1986 Arigaetal 521/58

4,889,669 A * 12/1989 Suzuki 264/45.9

5,034,171 A * 7/1991 Kiczeketal 264/51

5,823,889 A * 10/1998 Aoyama 473/374

(Continued)
FOREIGN PATENT DOCUMENTS
EP 1166991 A2 * 1/2002

(86) PCT No.: PCT/JP2005/013415

§ 371 (c)(1),

(2), (4) Date: Nov. 2, 2006

(87) PCT Pub. No.: WO2006/011415 PCT Pub. Date: Feb. 2, 2006

(65) Prior Publication Data

US 2008/0290543 Al Nov. 27, 2008

(30) Foreign Application Priority Data

Jul. 26,2004 (JP) 2004-217333

(51) Int. CI.

B29C 45/00 (2006.01)
B29C 45/70 (2006.01)

(52) U.S. CI 264/55; 264/50; 264/56;

264/328.7; 264/45.1; 264/45.3

(58) Field of Classification Search 264/36.11,

264/41, 42, 45.1, 45.3, 45.7, 45.8, 45.9, 317, 264/318, 319, 328.7 See application file for complete search history.

(Continued)

Primary Examiner—Khanh Nguyen
Assistant Examiner—Keith T Aziz

(74) Attorney, Agent, or Firm—Edwards Angell Palmer & Dodge LLP

(57) ABSTRACT

An injection-foaming method for a thermoplastic resin comprising using an injection unit 30 provided with a hopper 35, a plasticizing cylinder 31 and a screw 32, and a mold 10 having a mold cavity 10a of changeable capacity; filling the mold cavity 10a with a foaming-agent-containing melted resin injected from the injection unit 30; and then enlarging the mold cavity 10a for allowing the foaming-agent-containing melted resin to expand, wherein inclusion of a foaming agent into a thermoplastic resin is done by using a mixture of a foam nucleating agent and a foaming gas as foaming agent, feeding the mixture to hopper 35 or plasticizing cylinder 31 and screw 32 of injection unit 30 at a pressure of 0.1 MPa or more and less than 1.0 MPa, and contacting the mixture with a pre- or post-plasticized thermoplastic resin present in hopper 35 or plasticizing cylinder 31 and screw 32.

10 Claims, 2 Drawing Sheets