Starch-based, biodegradable packing filler and method of preparing same

• US 5,185,382 A
• Filed: 08/21/1992
• Issued: 02/09/1993
• Est. Priority Date: 01/21/1992
• Status: Expired due to Fees

• Current Assignee: Kansas State University Research Foundation
• Original Assignee: Kansas State University Research Foundation
• Inventors: Neumann, Paul E., Seib, Paul A.
• Primary Examiner(s): Foelak, Morton
• Application Number:
  US07/932,938
• Time in Patent Office: 172 Days
• Field of Search: 521/84.1, 521/79, 521/82, 521/88, 264/53, 264/186, 106/122, 106/210, 106/213
• US Class Current: 521/84.1
• CPC Class Codes: B29C 48/03 characterised by the shape of the extruded material at extrusion
• CPC Class Codes: B29C 48/405 Intermeshing co-rotating screws
• CPC Class Codes: B29C 48/67 having incorporated mixing devices not provided for in groups B29C48/52 - B29C48/66
• CPC Class Codes: B65D 65/466 Bio- or photodegradable packaging materials
• CPC Class Codes: B65D 81/09 using flowable discrete elements of shock-absorbing material, e.g. pellets or popcorn
• CPC Class Codes: C08J 2303/00 Characterised by the use of starch, amylose or amylopectin or of their derivatives or degradation products
• CPC Class Codes: C08J 2471/00 Characterised by the use of polyethers obtained by reactions forming an ether link in the main chain of polyacetals C08J2459/00; of epoxy resins C08J2463/00; of polythioether-ethers C08J2481/02; of polyethersulfones C08J2481/06; Derivatives of such polymers
• CPC Class Codes: C08J 9/0061 characterized by the use of several polymeric components
• 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 3/00 Compositions of starch, amylose or amylopectin or of their derivatives or degradation products
• CPC Class Codes: C08L 71/02 Polyalkylene oxides
• CPC Class Codes: Y02W 90/10 Bio-packaging, e.g. packing containers made from renewable resources or bio-plastics

Abstract

Starch-based biodegradable packaging fillers are provided which have high volumes, low weights, and excellent compressibility and resiliency properties. The products of the invention are fabricted by extrusion of a starch substrate, most preferably normal wheat starch, in the presence of minor amounts of a polyalkylene glycol or derivative thereof and/or a particulate bubble-nucleating agent. Effective biodegradable packaging fillers can thus be fabricated without the use of expensive modified starch substrates; however, such substrates can also be employed if desired, and the additives of the invention improve these products as well. In preferred production procedures, the additives are mixed with the starch substrate, and the mixture is preconditioned and then extruded through a twin screw extruder.

Claims

1. A starch product adapted for use as a packaging filler or the like, said product comprising an expanded, cellular, compressible and resilient body having a matrix principally comprising starch supplemented with a polyalkylene glycol or derivative thereof.

2. The starch product of claim 1, said polyalkylene glycol or derivative thereof having an average molecular weight of at least about 1,000.

3. The starch product of claim 1, said starch being selected from the group consisting of modified and unmodified wheat and corn starches.

4. The starch product of claim 3, said starch being selected from the group consisting of wheat and high amylose corn starches.

5. The starch product of claim 1, said polyalkylene glyol or derivative thereof being selected from the group consisting of polyethylene glycol, polypropylene glycol, polyalkylene-acrylate copolymers, adducts of polyalkylene glycols with epoxide derivatives, and mixtures thereof.

6. The starch product of claim 5, said polyalkylene glycol or derivative thereof being selected from the group consisting of polyethylene glycol having an average molecular weight of at least about 5,000, and polyethylene glycol adducts of bis-oxirane-bisphenol A.

7. The starch product of claim 1, said polyalkylene glycol or derivative thereof being present at a level of up to about 10% by weight.

8. The starch product of claim 7, said level being from about 1-6% by weight.

9. The starch product of claim 8 said level being about 3% by weight.

10. The starch product of claim 1, said starch matrix also being supplemented with a minor amount of a bubble-nucleating agent.

11. The starch product of claim 10, said agent being selected from the group consisting of silicon dioxide and amorphous silicas and mixtures thereof.

12. The starch product of claim 10, said agent being in particulate form and having a particle size of from about 5-100 microns and a surface area of from about 190-450 m² /g.

13. The starch product of claim 10, said agent being present at a level of from about 0.1-1% by weight.

14. The starch product of claim 13, said level being about 0.5% by weight.

15. The starch product of claim 1, said product being annular.

16. The starch product of claim 1, said product being generally C-shaped in cross-section.

17. The starch product of claim 1, said product having a bulk density of from about 0.6-2 lb/ft³.

18. The starch product of claim 17, said bulk density being from about 1.2-1.6 lb/ft³.

19. The starch product of claim 1, said product having a bulk compressibility of from about 0.04 to 0.4 kilo-newtons.

20. The starch product of claim 19, said compressibility being from about 0.13-0.36 kilo-newtons.

21. The starch product of claim 1, said product having a bulk resiliency of from about 40-75%.

22. The starch product of claim 21, said resiliency being from about 45-70%.

23. The starch product of claim 1, said product presenting cells having an average diameter of from about 0.5 to 5 mm.