| 摘要 |
<p>1528661 Laminates W R GRACE & CO 13 Feb 1976 [14 Feb 1975] 05798/76 Headings B5N and B5B A self-supporting extensible laminar film suitable for use in stretch-wrap packaging comprises at least two layers, a first layer of elastomeric polymeric material which can be stretched to at least 1À5 times its original length and will return, with or, without the application of force, to its original length and an extensible heat-sealable surface layer of the laminate of an interpolymer of ethylene and one or more alkenoic acids, the carboxylic acid groups of which have been wholly or partly neutralized by inorganic cations, preferably of alkali or alkaline earth metals or zinc. The first elastomeric layer may be disposed intermediate two of the heat-sealable surface layers. The first elastomeric layer may comprise an interpolymer of ethylene with anα-monoolefin having 3-8 carbon atoms or vinyl ester of a carboxylic acid having 2-5 carbon atoms, a styrene/conjugated diene interpolymer or polyurethane, a polyester or a polyether, or mixture thereof. Alternatively the first elastomeric layer may comprise a blend of (I) an ethylene/propylene interpolymer and (II) polyethylene having a density of 0À91-0À925 g./c.c. or ethylene/vinyl acetate interpolymer. The outer layers may contain strip additives, antiblocking agents and anti-fogging adjuvants. The laminar film may be produced by hot blown co-extrusion of the layers, extrusion of the elastomeric core between the preformed heatsealable layers or by application of heat and pressure to preformed layers.</p> |
