Biodegradable starch based articles

• US 5,512,378 A
• Filed: 01/23/1995
• Issued: 04/30/1996
• Est. Priority Date: 12/12/1991
• Status: Expired due to Term

• Current Assignee: Novamont S.p.a.
• Original Assignee: Novamont S.p.a.
• Inventors: Scarati, Mario, Romano, Giancarlo, Bastioli, Catia, Tosin, Maurizio
• Primary Examiner(s): Sluby, P. C.
• Application Number:
  US08/376,303
• Time in Patent Office: 463 Days
• Field of Search: 428/484, 428/497, 428/498, 428/485, 428/532, 428/533, 428/913
• US Class Current: 428/484.1
• 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 2491/00 Characterised by the use of oils, fats or waxes; Derivatives thereof
• CPC Class Codes: C08J 7/0427 with only one layer of a composition containing a polymer binder with more layers C08J7/042
• CPC Class Codes: C08J 7/048 Forming gas barrier coatings
• CPC Class Codes: Y10S 428/913 Material designed to be responsive to temperature, light, moisture
• CPC Class Codes: Y10T 428/31801 Of wax or waxy material
• CPC Class Codes: Y10T 428/31804 Next to cellulosic
• CPC Class Codes: Y10T 428/31844 Of natural gum, rosin, natural oil or lac
• CPC Class Codes: Y10T 428/31848 Next to cellulosic
• CPC Class Codes: Y10T 428/31971 Of carbohydrate
• CPC Class Codes: Y10T 428/31975 Of cellulosic next to another carbohydrate

Abstract

Thin-walled biodegradable starch-based articles, particularly sheets of film including at least one first layer of polymeric material including starch and at least one second layer of hydrophobic material, are characterized in that the second layer includes a natural or synthetic wax or mixture of waxes.

Claims

1. A biodegradable laminated film comprising two layers:

(a) a first layer comprising a starch; and

(b) a hydrophobic layer adjacent to, and in contact with, the first layer, comprising

(i) from 10 to 100% by weight of a wax selected from the group consisting of natural waxes, synthetic waxes and mixtures thereof; and

(ii) from 0 to 90% by weight of a synthetic polymer.

2. A biodegradable laminated film according to claim 1, wherein the wax is a petroleum wax selected from the group consisting of paraffin waxes having n-alkane contents of from 75% to 100% and average molecular weights of from 280 to 560 and microcrystalline waxes composed of isoparaffinic and naphthenic hydrocarbons saturated with n-alkanes and having molecular weights of from 450 to 800 and melting points of from 50°

to 90°

C.

3. A biodegradable laminated film according to claim 1, wherein the wax is an animal wax selected from beeswax and spermaceti wax.

4. A biodegradable laminated film according to claim 1, wherein the wax is a vegetable wax selected from the group consisting of candelilla wax, carnauba wax, Japan wax, ouricury wax, bayberry wax, jojoba wax and mixtures thereof.

5. A biodegradable laminated film according to claim 1, wherein the wax is a mineral wax.

6. A biodegradable laminated film according to claim 1, wherein the wax is a synthetic wax selected from the group consisting of Fischer-Tropsch wax, polyethylene wax, fatty acids and amides of fatty acids.

7. A biodegradable laminated film according to claim 1, wherein the synthetic polymer comprises a material selected from the group consisting of poly-ethylene-vinyl alcohol, poly-ethylene-acrylic acid, poly-ethylene-acrylic acid-alkyl acrylate, polyvinyl acetate, ethylene-vinyl acetate copolymers, rosin and derivatives thereof, alkyd resins, natural gum and thermoplastic gum.

8. A biodegradable laminated film according to claim 7 wherein the synthetic polymer is present in an amount by weight up to 25% by weight of the wax.

9. A biodegradable laminated film according to claim 7, wherein the synthetic polymer comprises a derivative of rosin selected from abietic acid, levopimaric acid and palustric acid, esters thereof selected from methyl, ethyl, hexadecyl, oxypyranylmethyl, 2-hydroxyethyl and 3-hydroxyphenyl esters, and esters of 1,2,3-propantriol.

10. A laminated film according to claim 7, wherein the synthetic polymer comprises a derivative of rosin selected from the addition products of abietic acid, levopimaric acid or palustric acid formed with maleic anhydride and polymers of those acids with glycols and phthalic acids.

11. A laminated film according to claim 1, wherein the hydrophobic layer is obtained from an emulsion comprising surfactants and stabilizers selected from the group consisting of alkyl sulphates, aryl sulphates, alkyl sulphonates, aryl sulphonates, derivatives of ethylene oxide, fatty acids, alkylamine salts, quaternary ammonium salts, starch, dextrin, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose (sodium salt), methyl cellulose and polyvinyl alcohol.

12. A biodegradable laminated film according to claim 11, wherein the hydrophobic layer further comprises an alcohol selected from the group consisting of methyl, ethyl, propyl, isopropyl, butyl and isobutyl alcohols.

13. A biodegradable laminated film according to claim 11, wherein the hydrophobic layer further comprises a glycol selected from the group consisting of 2-methoxyethanol, 2-butoxyethanol, 2-ethoxyethanol, polyethylene glycol and polypropylene glycol.

14. A biodegradable laminated film according to claim 11, wherein the emulsion further comprises a thickener selected from the group consisting of starch, methyl cellulose, hydroxyethyl cellulose, alginates, casein and polylurethanes.

15. A laminated film according to claim 1, wherein the hydrophobic layer is obtained from an emulsion comprising a plasticizer selected from the group consisting of dibutyl phthalate, n-heptyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl maleate, 2-ethylhexyl fumarate, dibutyl sebacate, polyglycol adipate, tricresyl phosphate, dioctyl phthalate and tributoxyethyl phosphate.

16. A biodegradable laminated film according to claim 1, wherein the hydrophobic layer further comprises fillers and pigments, the fillers and pigments being selected from the group consisting of titanium dioxide, talc, calcium carbonate and silica.

17. A laminated film according to claim 1, wherein the synthetic polymer comprises a material selected from the group consisting of ethylene-vinyl alcohol copolymers, ethylene-acrylic acid copolymers, ethylene-acrylic acid-alkyl acrylate copolymers, polyvinyl acetate, ethylene-vinyl acetate copolymers, rosin and derivatives of rosin, alkyd resins and natural gum.

18. A laminated film according to claim 1, wherein the synthetic polymer comprises a material selected from the group consisting of ethylene-vinyl acetate copolymers, ethylene-acrylic acid, ethylene-acrylic acid-alkyl acrylate, polyethylene-vinyl alcohol copolymers, polyhydroxyalkanoate, homopolymers of lactic acid, poly-epsilon-caprolactone, lactic acid copolymerized with glycolic acids and/or epsilon-caprolactone and fatty acids, the hydrophobic layer being deposited on the starchy layer by coextrusion, casting, or a hot-melt technique.

19. A laminated film according to claim 1, wherein the first layer further comprises a synthetic thermoplastic polymer selected from the group consisting of polyvinyl alcohols, ethylene-vinyl alcohol copolymers, ethylene acrylic acid copolymers, ethylene-vinyl acetate copolymers, and mixtures thereof.

20. A biodegradable laminated film according to claim 1 wherein the hydrophobic layer consists essentially of a wax selected from the group consisting of natural waxes, synthetic waxes, and mixtures thereof.

21. Articles produced by co-injection or co-blowing and which have walls with a composite structure comprising

(a) a first layer comprising a starch;

and

(b) a hydrophobic layer adjacent to, and in contact with, the first layer, comprising

(i) from 10 to 100% by weight of a wax selected from the group consisting of natural waxes, synthetic waxes and mixtures thereof; and

(ii) from 0 to 90% by weight of a synthetic polymer.