GB1431469A - Packaging for perishable foods - Google Patents

Abstract

1431469 Packaging elements IDEMITSU KOSAN KK 27 Nov 1973 [28 Nov 1972] 55035/73 Heading B8P [Also in Division C3] Perishable foodstuffs, such as fruit, eggs, &c., are packaged between first and second sheets 11 and 15 of a foamed polyolefinic resin composition containing 30 to 60% by weight of calcium carbonate, calcium sulphite, calcium sulphate, calcium hydroxide, calcium silicate or mixtures thereof, the second sheet being a physicallyfoamed sheet and the first sheet being either a physically- or chemically-foamed sheet and provided with article-receiving recesses 12. The resin may comprise polyethylene, polypropylene, polybutadiene, polyisoprene, ethylene/ vinyl acetate copolymers, and mixtures of polyethylene and polybutadiene. The particle size of the calcium compound is less than 10 Á. The second sheet 15 may be formed by heating a mixture of resin pellets and the calcium compound to form granules which are heated in an extruder. A physical blowing agent, liquid butane or butylene, is introduced into the extruder and the resin mix extruded either directly into sheet form which may subsequently be perforated or into a 2 mm. rope which is processed to provide a fused network sheet form, Fig. 2 (not shown). The first sheet may be formed as described above but in which the mixture is directly extruded into sheet form, the sheet then being vacuum-moulded to form recesses 12. Alternatively, the first sheet 1, Fig. 1 (not shown), may be formed by kneading a heated mixture of resin, calcium compound, a foaming agent (e.g. azodicarboxylamide), and a cross-linking agent (e.g. 1,3-bis-(t-butyl peroxyisopropyl)benzene), charging the mixture into a die of a compression moulding machine to form a plate. The plate is subsequently cut to form sheets which are pattern stamped to provide the recesses. A package is formed by building-up layers of filled first sheets each overlain with a second sheet within a carton-board-lined case.