Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1991-03-27
1993-11-02
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
524 53, 523128, 525 61, 525344, 525345, 5253284, 525385, C08L 302, C08F 834
Patent
active
052584305
DESCRIPTION:
BRIEF SUMMARY
The invention relates to polymer compositions useful for the production of articles of biodegradable plastics material and to methods for their preparation.
In particular, the invention constitutes an improvement within the scope of the invention described in unpublished Italian Patent Application No. IT 67413-A/89 and the corresponding EP 90110070.1 whose contents should be understood as being incorporated herein by way of reference.
Application No. IT 67415-A/89 and the corresponding EP 90110071.9 which constitutes prior art only for the purpose of A 54(5) EPC, describe polymer compositions including a destructured starch and an ethylene-vinyl alcohol copolymer for the production of articles of biodegradable plastics material. These compositions may include further polymeric additives such as, in particular polyvinyl alcohol and an ethylene-acrylic acid copolymer The particular object of the invention which is the subject of the above mentioned applications is to provide compositions which can be formed into films or into moulded articles with improved mechanical strength. The biodegradability of the composition is ensured, in particular, by the completely biodegradable starch component.
The object of the present invention is to improve the biodegradability of polymer compositions of the type mentioned above.
With regard to this object, the subject of the invention is constituted by a composition including a destructured starch and a synthetic polymer selected from the group consisting of ethylene-vinyl alcohol, polyvinyl alcohol and mixtures thereof, wherein at least a portion of said polymers is modified by the substitution of from 0.1 to 5 molar % of the functional alcohol groups in the polymeric chain by X groups in which X is an oxo (0=) or an alkyl carbonyl group ##STR1## in which the alkyl group contains from 1 to 4 carbon atoms.
It has been found that, when the aforesaid groups are substituted for the alcohol groups within the limits defined above, the compatibility of the polymers with the starch remains substantially unchanged so that, although the capacity to form films and the mechanical properties of the films and moulded articles produced from the compositions are substantially unchanged, the biodegradability upon exposure to atmospheric agents of the moulded articles and films thus produced is improved, particularly as regards photodegradability.
The amount of modified polymers within the composition may range from 5 to 100% wt, preferably from 10 to 50% wt referred to the total amount of synthetic polymer.
The modified polymers used within the scope of the invention can be produced by known methods from commercially available ethylene-vinyl alcohol polymers and polyvinyl alcohol polymers.
In particular, as regards the oxo groups, the structural modification can be introduced by the reaction of previously-prepared polymers with hydrogen peroxide and persulfuric acid, by the reaction of such polymers with hypochlorite and acetic acid, or by other methods of oxidizing secondary alcohols described in the literatures.
Modified copolymers including alkyl carbonyl groups can be obtained from ethylene vinyl acetate (EVA) polymer systems with a low ethylene content, that is, with an ethylene content of from 10 to 50%, preferably from 20 to 40%, by weight, by free-radical polymerization in the presence of monomers of the ##STR2## type in which R is an alkyl group with from 1 to 4 carbon atoms, together with ethylene and vinyl alcohol.
The EVAs thus obtained are then converted into modified ethylene-vinyl alcohol copolymers by basic hydrolysis.
Ethylene/vinyl alcohol copolymers usable within the scope of the present invention after structural modification typically have an ethylene content of from 10 to 90% by weight, preferably from 10 to 40% by weight, with a melt index of between 2 and 50, preferably between 6 and 20 (210.degree. C., 2.16 Kg).
Further preferred features for the ethylene/vinyl alcohol copolymer are as follows:
______________________________________ Intrinsic viscosity, [.eta.] 0
REFERENCES:
patent: 3652542 (1972-03-01), Hjermstad
patent: 3949145 (1976-04-01), Otey et al.
patent: 4008116 (1977-02-01), Sebel
patent: 4673438 (1987-06-01), Wittwer
patent: 4863655 (1989-09-01), Lacourse et al.
patent: 4900361 (1990-02-01), Sachetto et al.
patent: 5035930 (1991-07-01), Lacourse et al.
patent: 5043196 (1991-08-01), Lacourse et al.
patent: 5095054 (1992-03-01), Lay et al.
Polyvinyl Alcohol Properties and Applications, C. A. Finch, 1973, p. 194 and Table 9.8.
Chemical Abstracts, vol. 7, No. 8, p. 47, Abstract No. 60151n, F. H. Otey et al., "Starch-based blown films" (Aug. 24, 1987).
Otey, F. H. et al., Ind. Eng. Chem. Res. 26(8):1659-63 (1987), "Starch-Based Blown Films".
Bastioli Catia
Bellotti Vittorio
Del Guidice Luciano
Lombi Roberto
Barnhard Elizabeth M.
Cave Bryan
DeWitt LaVonda
Michl Paul R.
Novamont S.p.A.
LandOfFree
Polymer compositions for the production of articles of biodegrad does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polymer compositions for the production of articles of biodegrad, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polymer compositions for the production of articles of biodegrad will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1757995