Process for preparing biodegradable resin foam

• US 5,308,879 A
• Filed: 08/13/1993
• Issued: 05/03/1994
• Est. Priority Date: 09/07/1992
• Status: Expired due to Term

• Current Assignee: Nippon Gohsei Kagaku Kogyo Kabushiki Kaisha
• Original Assignee: Nippon Gohsei Kagaku Kogyo Kabushiki Kaisha
• Inventors: Akamatu, Yoshimi, Tomori, Masahiro
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US08/105,681
• Time in Patent Office: 263 Days
• Field of Search: 521/84.1, 521/109.1, 521/141, 521/79, 106/122, 264/53
• US Class Current: 521/84.1
• CPC Class Codes: B29K 2311/00 Use of natural products or their composites, not provided for in groups B29K2201/00 - B29K2309/00, as reinforcement
• CPC Class Codes: C08J 2303/02 Starch; Degradation products thereof, e.g. dextrin
• CPC Class Codes: C08J 9/0085 Use of fibrous compounding ingredients C08J9/0076 takes precedence
• CPC Class Codes: C08J 9/125 Water, e.g. hydrated salts
• CPC Class Codes: C08L 2201/06 Biodegradable
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 29/04 Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• CPC Class Codes: C08L 3/02 Starch; Degradation products thereof, e.g. dextrin
• CPC Class Codes: C08L 97/02 Lignocellulosic material, e.g. wood, straw or bagasse manufacture of articles made from lignocellulosic material by dry processes B27N

Abstract

A process for producing a biodegradable resin foam, having the steps of mixing a starch polymer containing from 5% by weight to 30% by weight of water, a vinyl alcohol resin containing from 5% by weight to 30% by weight of water, a nonionic surfactant, an inorganic or organic filler, and optionally a thickening agent; optionally adjusting the water content of the mixture, to prepare a composition having from 5% by weight to 30% by weight of water on the whole, based on total weight of the composition; melting and expanding it to prepare a foam, which has a low density and fine closed cells, and shows a good surface condition in a molded body.

Claims

1. A process for producing a biodegradable resin foam, comprising the steps of mixing a starch polymer containing from 5% by weight to 30% by weight of water, a vinyl alcohol resin containing from 5% by weight to 30% by weight of water, a nonionic surfactant and an inorganic or organic filler;

optionally adjusting the water content of the mixture, to prepare a composition having from 5% by weight to 30% by weight of water on the whole, based on the total weight of the composition;

melting and expanding it to prepare a foam.

2. A process as claimed in claim 1, wherein the organic filler is a vegetable fibrous material.

3. A process as claimed in claim 1, wherein the inorganic filler is talc.

4. A process as claimed in claim 1, wherein said composition further comprises a thickening agent, and a water content of said composition if from 5% by weight to 30% by weight.

5. A process as claimed in claim 4, wherein said composition is melted at a temperature of from 130°

C. to 200°

C., and a shear rate of the melt which is passing through a nozzle of a molding machine is at least 10³ sec^-1.