Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1993-01-11
1995-01-24
Seidleck, James J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
428461, 428500, 428507, 428511, 428514, 428515, 428516, 428520, 524 47, 524 48, 525 56, B32B 2706, B32B 2718, C08L 300, C08L 2904
Patent
active
053841875
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a biodegradable resin composition comprising a saponified ethylenevinyl acetate copolymer and a starch-based macromolecular substance and to a laminate utilizing the same.
BACKGROUND ART
Prior art
Molded plastic products such as plastic packaging films and containers, agricultural plastic films, binding tapes and so on are sometimes disposed of in ways other than legitimate routes of disposal. Because these products retain their shapes for years, they present serious environmental problems when discarded as they are. Therefore, it is highly desirable that any shaped products that are liable to be discarded in the open field, farmlands, rivers, etc. be those which will be rapidly decomposed by microorganisms in the soil or water.
Against this background, much development work has been undertaken to develop biodegradable compositions for the fabrication of such biodegradable shaped products. Referring to research and development along this line, the following patent applications have been filed in the technical field of bio-degradable or disintegratable compositions each comprising a saponified ethylene-vinyl acetate copolymer (i.e. ethylenevinyl alcohol copolymer) and a starch-based macromolecular substance.
Japanese Patent Kokai Publication No. 3-31333
The official gazette of Japanese Patent Kokai Publication No. 3-31333 discloses a polymer composition for the manufacture of shaped biodegradable plastic products which comprises an ethylene-vinyl alcohol copolymer and a modified starch wherein the ethylene content of said ethylene-vinyl alcohol copolymer is 10 to 90 weight % and the melt flow index thereof is 2 to 50. The melt flow index here is the value determined at 230.degree. C. under a load of 2.16 kg. The same gazette states that the preferred parameters of the ethylenevinyl alcohol copolymer are as follows. 0.5-0.9, preferably 0.60-0.80
The same gazette states that, as the plasticizer, a polyol such as polyethylene glycol having a molecular weight of 200 to 4000, ethylene glycol, propylene glycol, sorbitol, or preferably glycerin can be employed.
Japanese Patent Kokai Publication No. 2-14228
The official gazette of Japanese Patent Kokai Publication No. 2-14228 discloses a polymer blend obtainable from a melt comprising a water-containing starch hydrolyzate and at least one substantially water-insoluble synthetic thermoplastic polymer. Claim 4 in the Scope of Demand for Patent of this gazette is directed to the use, as the thermoplastic polymer, of ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-acrylic acid copolymer, ethylene-ethyl acrylate copolymer, ethylene-methyl acrylate copolymer, ABS copolymer, styrene-acrylonitrile copolymer or polyacetal, thus referring to ethylene-vinyl alcohol copolymer, but there is no description about its ethylene content, nor does the specification include an example employing an ethylene-vinyl alcohol copolymer.
This gazette mentions, as the plasticizer, a variety of plasticizers such as low molecular weight polyalkylene oxides, e.g. polyethylene glycol, polypropylene glycol, polyethylenepropylene glycol, etc., low molecular weight organic plasticizers such as glycerol, glycerol monoacetate, diacetate or triacetate, etc., as well as propylene glycol, sorbitol, sodium diethylsulfosuccinate, triethyl citrate, tributyl citrate and so on.
Japanese Patent Kokai Publication No. 3-24101
The official gazette of Japanese Patent Kokai Publication No. 3-24101 discloses a method of producing a modified starch composition for the manufacture of shaped biodegradable plastic products which comprises blending starch with a high boiling plasticizer and a modifying agent selected from among urea, alkaline earth or alkali metal hydroxides and mixtures thereof at a temperature of 120.degree. to 170.degree. C. which is lower than the boiling point of the plasticizer for a sufficient time to modify the starch. Claim 5 in the Scope of Demand for Patent of this gazette states that the blending is
REFERENCES:
patent: 5091262 (1992-02-01), Knott et al.
patent: 5108807 (1992-04-01), Tucker
patent: 5158810 (1992-10-01), Oishi et al.
patent: 5217803 (1993-06-01), McBride et al.
patent: 5334634 (1994-08-01), Bastioli et al.
Akamatsu Yoshimi
Moriwaki Yoshikazu
Uemura Tomoyoshi
Yoshida Yuichi
Nippon Gohsei Kagaku Kogyo Kabushiki Kaisha
Seidleck James J.
Warzel M. L.
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