Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1996-07-17
1998-05-12
Jagannathan, Vasu
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
523102, 524442, 524444, 524445, 524447, 524448, C08J 510, C08K 334, C08L 2304
Patent
active
057506116
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to the field of thermoplastic compositions suitable for extrusion into films and moulding into shaped articles, more particularly to such compositions containing adsorbents adapted to inhibit offensive odours and flavours of such films and shaped articles.
BACKGROUND OF THE INVENTION
Many films and shaped articles adapted for packaging applications have the unwanted characteristic of possessing undesirable odours and flavours. Such odours and flavours may make the packaging unsuitable for various applications, e.g. in the area of food or hygienic packaging or, in general, any packaging with which man comes into contact. Typically, these undesirable odours and flavours are generated during production of the film or shaped article, e.g. during the extrusion or moulding process.
Various solutions have been proposed for eliminating or inhibiting odours and flavours in thermoplastic films. Adsorbents such as zeolites, diatomaceous earth, clays, activated carbons and the like have been incorporated into certain polymer or copolymers with varying results (cf. e.g. WO 92/13029, WO 92/13899, JP 62032-144, JP 63151-451 and JP 02208-346).
It has now been found that various adsorbents will not only inhibit odours and flavours in particular thermoplastics, but also, that such adsorbents will have a surprising, beneficial effect on various performance characteristics, such as adhesion, heat seal strength, hot tack strength and coefficient of friction of the films produced from thermoplastic compositions containing the adsorbents.
SUMMARY OF THE INVENTION
The instant invention relates particularly to a thermoplastic composition comprising (a) a thermoplastic selected from the group consisting of ethylene/acid copolymers and corresponding ionomers; and ethylene/acid/acrylate terpolymers and corresponding ionomers; and (b) an adsorption agent; to thermoplastic films and shaped articles obtainable from this composition; and the use of adsorbents in in adsorbing odours and flavours in the aforementioned thermoplastics.
As used herein, terms used have the following meanings.
Ethylene/acid copolymer and their corresponding ionomers are well known in the art to be copolymers of ethylene with an olefinically unsaturated organic mono- or di-acid such as acrylic or methacrylic acid, or maleic acid or fumaric acid or their anhydrides, the acid (or anhydride) comprising about 0.5 to 50 mole percent of the total polymeric material. The ethylene/acid copolymers and their methods of preparation are well known in the art and are disclosed in, for example U.S. Pat. Nos. 3,264,272, 3,404,134, 3,355,319 and 4,321,337. The copolymers are termed ionomers when the acid is neutralized in whole or in part to produce a salt. The cation for said salts are usually an alkali metals such as sodium or potassium or is zinc or the like.
Ethylene/acid/acrylate terpolymers and corresponding ionomers are well known in the art to be copolymers of ethylene, an olefinically unsaturated organic acid such as acrylic or methacrylic acid and an alkyl acrylate or methacrylate termonomer (e.g. n-butyl acrylate or methacrylate or isobutylacrylate).
Preferred thermoplastics are ionomers that are copolymers of ethylene and 2 to 50%, more preferably 5 to 25%, by weight acrylic or methacrylic acid neutralized up to about 90%, preferably from 5 to 60% with an alkali metal ion or a divalent or trivalent metal ion, the melt index of the copolymer, whether neutralized or unneutralized, being about 0.1 to 30, preferably 0.5 to 20, dg/min. according to ASTM Standard D1238 (condition E).
Suitable acid copolymers and ionomers are available from the DuPont Company under the trade names Nucrel.RTM. and Surlyn.RTM., respectively.
Adsorption agents are known per se. Suitable such agents include powders of diatomaceous earth, clay, kaolin, talc, bentonite, activated carbon and zeolites. Preferred adsorption agents are zeolites, and in particular siliceous molecular sieves.
Suitable siliceous molecular sieves are known
REFERENCES:
patent: 4095031 (1978-06-01), Engle
patent: 4761437 (1988-08-01), Christie
patent: 4795482 (1989-01-01), Gioffre et al.
patent: 5013335 (1991-05-01), Marcus
patent: 5211870 (1993-05-01), Gilbert et al.
patent: 5254337 (1993-10-01), Marcus et al.
E. I. Du Pont de Nemours and Company
Jagannathan Vasu
Rajguru U. K.
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