Laminated film with good oxygen-barrier properties - comprises 2 multilayer poly:olefin films laminated together, with interlayer of specified silica, as barrier layer

摘要

Transparent, sealable, laminated polyolefin film (I) contains 2 laminated films (A) and (B). (A) is a biaxially oriented, multilayer polyolefin film consisting of a base layer of peroxide-degraded isotactic polypropylene with outer layer(s) of ethylene-propylene copolymer or a blend of ethylene-propylene butylene (EPB) terpolymer and propylene-butylene copolymer or a blend of these co/ter-polymers and polypropylene, (B) is unoriented or mono- or bi-axially oriented multilayer polyolefin film, a layer of SiOx, (C) is interposed between (A) and (B), and at least one of the two facing surfaces of (A) and (B) is corona treated so that the intensity of treatment directly after producing the corresp. film is above 36 mN/m. Pref. (A) is corona treated and coated with SiOx on a side with an outer layer, pref. by corona-treating the SiOx-coated surface, the polypropylene base layer in (A) has MFI 21.6/230 = 2-6 g/10 mins. and degradation factor 3-10 and the outer layers comprise ethylene-propylene copolymer with 2-8 wt.% ethylene, a blend of EPB terpolymer and propylene-butylene copolymer contg. 0.1-7 wt.% R, 53-89.9 wt.% P and 10-40 wt.% B or a blend of PP and EPB and/or PB ter/co-polymer with MFI = 5-20 g/10 mins., the outer layers of (A) are above 0.3 micron thick and are peroxide-degraded with degradation factor 3-15, film (B) consists of isostatic polypropylene, polyethylene. statistical or block ethylene propylene copolymer contg. mainly polypropylene, polypropylene/polyethylene polymer blend, EPB terpolymer, a blend of EPB terpolymer and ethylene-propylene copolymer or a blend of polypropylene and ethylenepropylene copolymer and/or EPB terpolymer, pref. with peroxide degradation factor 2-15, (B) is a biaxially oriented multilayer film, pref. with corona treated sealing layer(s) and pref. with the same make-up as (A), films (A) and (C) are each 10-100 microns thick and layer (C) is 20-100 nm. thick, with x in SiOx = 1.2-1.9, (I) has oxygen permeability = 10-20 cm3/m2/d/bar, and the base and/or outer layers of (A) and/or (B) contain antistatics, antiblocking additives, lubricants, stabilisers and/or low-mol. wt. resins. USE/ADVANTAGE - (I) is useful as packaging film and for the prodn. of containers, bags, wrappings, packets, cans and shaped objects. (I) has a transparent, sealable film with good oxygen-barrier and aroma-barrier properties. Film contains a chlorine-free, environmentally harmless barrier layer which is unaffected by folding and can be used on high-speed packaging machines.