EP0470760A2
Expired / Lapsed
EP
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Composite plastics film or sheet
Assignee: BXL Plastics Ltd
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Filing: 1991-07-31
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Granted: —
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Expires: 2011-07-31
Abstract
Abstract This invention relates to a composite film comprising three coextruded layers including a core layer sandwiched between two outer layers, the core layer having been stretch-voided. At least one of the outer layers has an external printable surface and comprises at least three thermoplastic polymeric materials of which one is a rubbery polymer and at least a further two of the materials have a degree of mutual incompatibility, said external printable surface being substantially free of particle-induced voids. The films are suitable for use as synthetic paper.
Inventors
- 👤 Leonard Leese
- 👤 Vijay Yadav
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 01:01
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/06; B32B27/08; B29; B29C; B29C55/00; B29C55/02; B29C55/023; B32B27/18; B32B27/20; B32B27/32; B29K; B29K2105/00; B29K2105/04; B32B38/00; B32B38/0012; B32B2038/0028; B32B2307/00; B32B2307/40; B32B2307/41; B32B2307/414; B32B2307/70; B32B2307/75; B32B2323/00; B32B2323/04; B32B2323/043
Claims Analysis
Total Claims: 39
Claim 1
Independent Claim
90 words
A composite film or sheet for use as synthetic paper comprising three coextruded layers including a core layer situated between two outer layers, the core layer having been stretch-voided, characterised in that at least one of the outer layers provides an external printable surface, optionally after further treatment, and comprises at least three thermoplastics polymeric materials of which one is a rubbery polymer and at least a further two of the materials have at least a degree of mutual incompatibility, said external surface being substantially free of particle-induced open voids.
Claim 2
Dependent Claim
34 words
A composite as claimed in Claim 1 wherein the thermoplastics material on which the compositions of the outer layers are principally based are at least similar to that which predominates in the core layer.
Claim 3
Dependent Claim
26 words
A composite as claimed in Claim 1 or 2 wherein the core layer is derived from a composition selected from those described in GB-A-1470372 and GB-A-1492771.
Claim 4
Dependent Claim
73 words
A composite as claimed in Claim 3 wherein the core layer is derived from a composition comprising a blend of an orientable thermoplastics olefin polymer and from 2 to 50% by weight calculated on the blend of at least one metal resinate which at least in part comprises a separate phase uniformly distributed within the olefin polymer and which composition is extrudable to form a layer and stretchable to produce a voided structure.
Claim 5
Dependent Claim
31 words
A composite as claimed in Claim 4 wherein the core layer is derived from a composition comprising a blend of high density polyethylene (as herein before defined) and a calcium-zinc resinate.
Claim 6
Dependent Claim
22 words
A composite as claimed in any one of the preceding Claims wherein voids in the core layer are solely due to stretch-voiding.
Claim 7
Dependent Claim
21 words
A composite according to any one of the preceding Claims wherein the outer layers are bonded directly to the core layer.
Claim 8
Dependent Claim
49 words
A composite according to any one of the preceding Claims wherein at least one layer providing an external printable surface is based on a thermoplastics material that is not water-vapour absorbent and is free of particulate or microfibrous hygroscopic solid polymeric additive capable of rendering the layer water-vapour absorbent.
Claim 9
Dependent Claim
25 words
A composite according to any one of the preceding Claims wherein at least the outer layer providing an external printable surface is translucent or opaque.
Claim 10
Dependent Claim
27 words
A composite according to Claim 5 wherein at least the outer layer providing the external printable surface is based on high density polyethylene as herein before defined.
Claim 11
Dependent Claim
42 words
A composite according to any one of the preceding Claims wherein at least one of the outer layers is based on a thermoplastics composition comprising at least high density polyethylene, polystyrene and a rubbery polymer with or without linear low density polyethylene.
Claim 12
Dependent Claim
42 words
A composite according to any one of Claims 1 to 10 wherein at least one of the outer layers is based on a thermoplastics composition comprising high density polyethylene and linear low density polyethylene or a propylene (co)polymer and a rubbery polymer.
Claim 13
Dependent Claim
33 words
A composite according to any one of Claims 10, 11 or 12 wherein the high density polyethylene has a Melt Flow Index in the range 0.001 to 2.0, preferably 0.15 to 0.5 decigrams/minute.
Claim 14
Dependent Claim
36 words
A composite according to any one of the preceding Claims wherein the rubbery polymer is selected from thermoplastics copolymers of butadiene and styrene, copolymers of isobutylene and isoprene, and terpolymers of ethylene, propylene and a diene.
Claim 15
Dependent Claim
59 words
A composite according to any one of the preceding Claims wherein the amount of rubbery polymer present in the outer layer destined to provide an external printable surface is in the range of 0.5 to 20, preferably 1 to 10 parts by weight, based on 100 parts by weight of the principal thermoplastics polymer component of the outer layer.
Claim 16
Dependent Claim
40 words
A composite according to any one of the preceding Claims wherein the outer layers contain an amount of antistatic agent effective in reducing static decay half-life of the composite after ageing for one day to no more than 60 secs.
Claim 17
Dependent Claim
39 words
A composite according to Claim 16 wherein the antistatic agent is present in the outer layers at from 0.5 to 1.5 parts by weight per 100 parts of the principal polymer component of the composition comprising each outer layer.
Claim 18
Dependent Claim
41 words
A composite according to any one of the preceding Claims wherein the outer layers have a pigment/filler content in the range 10 - 30%, preferably 15 - 25% by weight, based on the weight of the composition of each outer layer.
Claim 19
Dependent Claim
37 words
A composite according to any one of the preceding Claims wherein the core layer is stretch-voided at a temperature within the normal orientation temperature range of the principal thermoplastics polymer on which the core layer is based.
Claim 20
Dependent Claim
88 words
A composite according to Claim 19 wherein the temperature of stretching is selected from: a) temperatures below the melting point or softening point of the void inducing component of the core layer when said component is a non-polymeric organic compound, a metal salt of an organic acid, a metal resinate or a modified or unmodified rosin ester; b) temperatures below the glass transition temperature of the void inducing component of the core layer when said component is a polymer; such that voids are formed in the core layer.
Claim 21
Dependent Claim
42 words
A composite according to any one of the preceding Claims wherein the core layer is stretch-voided at a temperature within the normal orientation temperature range of the principal thermoplastics polymer on which the outer layer providing an external printable surface is based.
Claim 22
Dependent Claim
19 words
A composite according to any one of the preceding Claims wherein the core layer is stretch-voided by biaxial stretching.
Claim 23
Dependent Claim
14 words
A composite according to Claim 22 wherein the biaxial stretching is simultaneous biaxial stretching.
Claim 24
Dependent Claim
22 words
A composite according to any one of the preceding Claims wherein the core layer is stretch-voided by use of a flat-bed stretcher.
Claim 25
Dependent Claim
20 words
A composite according to any one of the preceding Claims wherein the core layer incorporates reworked, reclaimed scrap composite material.
Claim 26
Dependent Claim
35 words
A composite according to any one of the preceding Claims wherein the thickness of at least one layer providing an external printable surface is no more than 25% of the thickness of the core layer.
Claim 27
Dependent Claim
15 words
A composite according to any one of the preceding Claims which is corona discharge treated.
Claim 28
Dependent Claim
19 words
A composite according to any one of the preceding Claims which is further coated on at least one side.
Claim 29
Dependent Claim
16 words
A composite according to Claim 28 wherein the coating is selected from those described in GB-A-2177413.
Claim 30
Dependent Claim
15 words
A composite according to any one of the preceding Claims which comprises a synthetic paper.
Claim 31
Independent Claim
91 words
A method for producing a composite plastics film or sheet as claimed in any one of the preceding Claims which comprises coextruding three thermoplastics layers comprising a core layer situated between two outer layers wherein the composition of the core-layer is stretch-voidable and wherein the composition of at least one of the outer layers is stretchable at a temperature at which the core layer is stretch-voidable, stretch-voiding the core layer and stretching the outer layers to produce an external printable surface, optionally after further treatment, and optionally coating the stretched product.
Claim 32
Dependent Claim
22 words
A method as claimed in Claim 31 wherein the stretch-voiding of the core layer and stretching of the outer layers occur simultaneously.
Claim 33
Independent Claim
33 words
A method as claimed in Claims 31 or 32 wherein the temperature of stretching is within the normal orientation temperature range of the principal thermoplastics polymer on which the core layer is based.
Claim 34
Dependent Claim
89 words
A method as claimed in Claim 33 wherein the temperature of stretching is selected from: a) temperatures below the melting point or softening point of the void inducing component of the core layer when said component is a non-polymeric organic compound, a metal salt of an organic acid, a metal resinate or a modified or unmodified rosin ester; b) temperatures below the glass transition temperature of the void inducing component of the core layer when said component is a polymer; such that voids are formed in the core layer.
Claim 35
Independent Claim
46 words
A method as claimed in any one of Claims 31 to 34 wherein the core layer is stretch-voided at a temperature within the normal orientation temperature range of the principal thermoplastics polymer on which the outer layer destined to provide an external printable surface is based.
Claim 36
Independent Claim
42 words
A method as claimed in any one of the Claims 31 to 35 wherein the stretch-voiding of the core layer and the stretching of the outer layers are achieved by stretching the coextrudate simultaneously biaxially in the machine and in transverse directions.
Claim 37
Independent Claim
27 words
A method as claimed in any one of Claims 31 to 36 wherein reworked, reclaimed scrap composite material is incorporated into the composition of the core layer.
Claim 38
Dependent Claim
24 words
A composite according to any one of Claims 1 to 30 used as an article of stationery or in printing, book binding or labelling.
Claim 39
Dependent Claim
16 words
A composite according to Claim 38 when used in the in-mould labelling of a plastics container.
References Cited (Backward Citations)
GB1374574A
Cited
GB1470372A
Cited
GB1492771A
Cited
GB1442113A
Cited
GB1490512A
Cited
GB2099754A
Cited
US4377616A
Cited
US4438175A
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US4663216A
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GB2177049A
Cited
GB2177413A
Cited
US4582753A
Cited
US4702954A
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US4632869A
Cited
US4701370A
Cited
EP0258020A2
Cited
GB2224973A
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