EP0345884A2
Expired / Lapsed
EP
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Coextruded synthetic resin structures and a process for their manufacture
Assignee: Dow Chemical Co
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Filing: 1989-06-05
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Granted: —
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Expires: 2009-06-05
Abstract
Abstract Extruded multilayer synthetic resin sheets are prepared wherein at least one coextruded removable layer is employed to maintain the concentration of exudable additive(s) (e.g., UV absorbant) at the sheet surface (after removal of said protective layer) and protect the production equipment from exuded amounts of such additives. A further advantage of the present invention is the avoidance of a secondary lamination step wherein such a protective layer would be provided solely for the purpose of protecting the sheet surface during handling, shipping, and installation.
Inventors
- 👤 Paul D.M. Haemhouts
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 04:00
CPC Classifications
B; B32; B32B; B32B27/00; B32B27/06; B32B27/08; B29; B29C; B29C48/00; B29C48/03; B29C48/07; B29C48/09; B29C48/11; B29C48/16; B29C48/18; B29C48/21; B29C48/25; B29C48/30; B29C48/305; B29C48/307; B32B27/18; B32B27/32; B32B27/36; B32B27/365; B32B3/00; B32B3/10; B32B3/18; B32B3/20; B32B7/00; B32B7/04; B32B7/06; E; E04; E04C; E04C2/00; E04C2/54; E04C2/543; B29C48/001; B29C48/0017; B29C48/0022; B29C48/08; B29C48/12; B32B2369/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
63 words
A synthetic resin sheet structure having (a) a base layer comprising (a.1) a layer containing at least one exudable additive and (a.2) at least one additional layer not containing exudable additive(s), the resin sheet structure characterized by having (b) a coextruded removable, protective synthetic resin film layer adjacent layer (a.1) and preventing release or loss of exudable additive until removal of layer (b).
Claim 2
Dependent Claim
63 words
A synthetic resin sheet structure having (a) a base layer comprising (a.1) a layer containing at least one exudable additive and (a.2) at least one additional layer not containing exudable additive(s), the resin sheet structure characterized by having (b) a coextruded removable, protective synthetic resin film layer adjacent layer (a.1) and preventing release or loss of exudable additive until removal of layer (b).
Claim 3
Dependent Claim
31 words
The sheet structure according to Claim 1 wherein the exudable additive concentration in layer (a.1) is greater than 0.5 weight percent and in layer (a.2) is less than 0.5 weight percent.
Claim 4
Dependent Claim
39 words
The sheet structure according to Claim 1 wherein the base layer (a) comprises at least one exudable UV absorbant-containing layer (a.1) and at least one additional layer (a.2) and layers (a.1) and (a.2) are both prepared from polycarbonate resin.
Claim 5
Dependent Claim
16 words
The sheet structure according to Claim 3 wherein the protective layer (b) is LLDPE or HDPE.
Claim 6
Dependent Claim
22 words
The sheet structure according to Claim 4 wherein the thickness of the removable protective layer (b) is from 50 to 150 micrometers.
Claim 7
Dependent Claim
22 words
The sheet structure according to Claim 2 wherein the exudable additive is at least 0.5 weight percent of a benzotriazole-derivative UV absorbant.
Claim 8
Dependent Claim
38 words
The sheet structure according to Claim 6 consisting essentially of an innermost base layer (a.2), additive-containing layers (a.1) adjacent to both major surfaces of (a.2) and removable protective layers (b) adjacent to the outer surfaces of layers (a.1).
Claim 9
Dependent Claim
17 words
The sheet structure according to Claim 1 wherein at least one additional layer (a.2) comprises hollow chambers.
Claim 10
Dependent Claim
101 words
A process for preparing a synthetic resin sheet structure having (a) a base layer comprising (a.1) a layer containing at least one exudable additive and (a.2) at least one additional layer, comprising the step of (i) coextruding at least one layer containing exudable additive(s) with at least one additional layer, characterized in that at least one removable protective synthetic resin film layer is coextruded with the base layer adjacent to the exudable additive-containing layer (a.1) such that, in combination with the additional layer (a.2), the additive(s) concentration in such layer (a.1) is maintained and the production equipment protected from exudable additive(s).
Claim 11
Dependent Claim
101 words
A process for preparing a synthetic resin sheet structure having (a) a base layer comprising (a.1) a layer containing at least one exudable additive and (a.2) at least one additional layer, comprising the step of (i) coextruding at least one layer containing exudable additive(s) with at least one additional layer, characterized in that at least one removable protective synthetic resin film layer is coextruded with the base layer adjacent to the exudable additive-containing layer (a.1) such that, in combination with the additional layer (a.2), the additive(s) concentration in such layer (a.1) is maintained and the production equipment protected from exudable additive(s).
Claim 12
Dependent Claim
71 words
The process according to Claim 9 comprising the further steps of (ii) providing the extruded resin base layer (a) with one or more longitudinal hollow chambers and (iii) maintaining the size and shape of the hollow chambers during the resin cooling and hardening time by the use of a vacuum chamber with small vacuum orifices wherein the vacuum orifices are protected by the removable layer from becoming plugged with the additive(s).
Claim 13
Dependent Claim
46 words
The process according to Claim 10 wherein the hollow chambers are provided in a polycarbonate core layer (a.2), two exudable additive-containing layers (a.1) are coextruded on either side of the core layer, and removable protective layers are coextruded on both remaining surfaces of the additive-containing layers.
Claim 14
Dependent Claim
22 words
The process according to Claim 11 wherein the layers are coextruded from a feed block and supplied to a sheet extrusion die.
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