Method for the production of substantially open-cell polystyrene sheet

Abstract

A method of producing a substantially open-cell, expanded polystyrene sheet, comprising the steps of:forming a mixture comprising from 30 to 95% of polystyrene incorporating an aliphatic hydrocarbon with 4-6 carbon atoms, from 0 to 65% of polystyrene, and from 0.2 to 10% of a nucleating agent,mixing the mixture obtained and melting it by heating inside an extruder,bringing the mixture to a temperature of 130-150° C. in the final portion of the extruder,extruding the mixture in a lower-pressure atmosphere to produce an expanded sheet, which has a low density and a high capacity to absorb aqueous liquids, particularly if a surfactant is added to the starting mixture, and which, when coupled with two films of plastics material gives rise to a laminate suitable for the production, by thermoforming, of trays of foods which may release aqueous liquids.

Description

TECHNICAL FIELDIn general, the present invention relates to the packaging of food products, particularly foods such as, for example, meat or fish, which may release blood or other liquids.In particular, the invention relates to a tray comprising a sheet of substantially open-cell, low-density polystyrene having the capacity to absorb liquids, particularly aqueous liquids, and to a method of producing it.BACKGROUND OF THE INVENTIONIn the packaging of foods which may release blood, such as meat or fish, there is a problem in providing packages which can isolate and hide the blood released by the food, since it has been found that is presence and visibility inside the package renders the latter unattractive to the purchaser.Amongst the solutions proposed for this problem in the prior art, the simplest consists of the provision of a tray provided with a pad or layer of absorbent material, generally paper. Solutions of this type are described, for example, in patent applications EP-A-O 1...

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