Blow-molded foam and process for producing the same

Patent metadata

Field	Value
Publication number	US-11833723-B2
Application number	US-202117326645-A
Country	US
Kind code	B2
Filing date	May 21, 2021
Priority date	Mar 31, 2008
Publication date	Dec 5, 2023
Grant date	Dec 5, 2023

Abstract

The present invention provides a process for producing a blow-molded foam including foamed cells, the process including:kneading a polyolefin-based resin containing a foaming agent mixed therewith in an extruder, andextruding a parison formed of the polyolefin-based resin between split mold blocks from a die slit at an extrusion rate of 700 kg/h or more.

First claim

The invention claimed is:

1. A process for producing a blow-molded foam including foamed cells, the process comprising:
kneading a polyolefin-based resin containing a foaming agent mixed therewith in an extruder, and
extruding a parison formed of the polyolefin-based resin between split mold blocks from a die slit at an extrusion rate of 700 kg/h or more,
wherein the polyolefin-based resin is a propylene homopolymer having a long-chain branched structure.

2. The process of claim 1 , wherein the blow-molded foam is a climate control duct for vehicles.

3. The process of claim 1 , wherein the polyolefin-based resin has a melt flow rate of 1 to 10 g/10 min at 230° C.

4. The process of claim 1 , wherein carrying out blow molding after clamping by blowing air on the parison at a pressure of 0.05 to 0.15 MPa.

5. The process of claim 1 , wherein a standard deviation of a cell diameter of the foamed cells in the thickness direction of a wall defining the blow-molded foam is less than 40 μm.

6. The process of claim 1 , wherein an average cell diameter of the foamed cells in a thickness direction of a wall defining the blow-molded foam is less than 300 μm.

7. The process of claim 1 , wherein center-line average surface roughness Ra of an outer face of a wall defining the blow-molded foam is less than 9.0 μm.

8. The process of claim 1 , wherein the parison is extruded by retaining the polyolefin-based resin at a space, and extruding the polyolefin-based resin by use of a piston after a predetermined amount of the resin is retained at the space.

9. The process of claim 1 , wherein a supercritical fluid is used as the foaming agent.

Assignees

• Kyoraku Co Ltd

Inventors

• Onodera Masaaki
• Sumi Takehiko
• Tamada Teruo
• Igarashi Yu
• Ohno Yoshinori

Classifications

• B29C49/04114

  for keeping constant thickness · CPC title

• B29C49/0005

  characterised by the material · CPC title

• B29C44/02 Primary

  for articles of definite length, i.e. discrete articles · CPC title

• B29C44/3442

  Mixing, kneading or conveying the foamable material (mixing plastics B29B7/00; mixing in general B01F) · CPC title

• B29C44/3469

  Cell or pore nucleation · CPC title