In-mold foaming article of polypropylene resin composition

• US 6,326,409 B1
• Filed: 10/24/2000
• Issued: 12/04/2001
• Est. Priority Date: 11/05/1999
• Status: Active Grant

• Current Assignee: Kaneka Corporation
• Original Assignee: Kaneka Corporation
• Inventors: Mihayashi, Tsuyoshi, Yanagihara, Yutaka, Goda, Takayuki
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US09/694,264
• Time in Patent Office: 406 Days
• Field of Search: 521/58, 521/59, 521/134
• US Class Current: 521/58
• CPC Class Codes: C08J 2323/10 Homopolymers or copolymers of propene
• CPC Class Codes: C08J 9/0061 characterized by the use of several polymeric components
• CPC Class Codes: C08J 9/18 by impregnating polymer particles with the blowing agent
• CPC Class Codes: C08J 9/228 Forming foamed products
• CPC Class Codes: C08L 2203/14 used for foams
• CPC Class Codes: C08L 23/0876 Neutralised polymers, i.e. ionomers
• CPC Class Codes: C08L 23/10 Homopolymers or copolymers of propene
• CPC Class Codes: C08L 2666/04 Macromolecular compounds according to groups C08L7/00 - C08L49/00, or C08L55/00 - C08L57/00; Derivatives thereof

Abstract

The object of the present invention is to provide an in-mold foaming article of a propylene resin composition having improved productivity and stable quality in internal molding, and simultaneously a compressive strength and a tensile strength thereof at high density range are improved at the same time. The in-mold foaming article is obtained by using a pre-foamed particle having a density of 90 to 300 g/L and an open cell ratio of at most 12%, wherein the pre-foamed particle comprises a resin composition having (A) 100 parts by weight of a polypropylene resin and (B) 0.01 to 20 parts by weight of a hydrophilic polymer as a base material resin, and water as a foaming agent, the pre-foamed particle having at least two endothermic peaks in a DSC curve obtained in differential scanning calorimetry.

Claims

1. An in-mold foaming article of propylene resin composition having a density of 90 to 300 g/L and an open cell ratio of at most 12% obtained by molding a pre-foamed particle, wherein the pre-foamed particle comprises a resin composition containing (A) 100 parts by weight of polypropylene resin and (B) 0.01 to 20 parts by weight of a hydrophilic polymer as a base material resin, and water as a foaming agent, and the pre-foamed particle has at least two endothermic peaks in a DSC curve obtained in differential scanning calorimetry.

2. The in-mold foaming article of claim 1, wherein a fusion ratio is 10 to 70%.

3. The in-mold foaming article of claim 1, wherein a tensile strength is 0.6 to 3.0 Mpa, and a density x and a comprehensive strength y satisfy the following condition formula (1):

4. The in-mold foaming article of claim 2, wherein a tensile strength is 0.6 to 3.0 Mpa, and a density x and a compressive strength y satisfy the following condition formula (1):