Method for making transparent reflective films
First Claim
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1. A method for coating polymer film with zinc sulfide, comprising the steps of:
- (a) placing a crucible containing zinc sulfide solids in a vacuum deposition chamber having a supply roll of the polymer film and a take-up roll for the polymer film;
(b) evacuating the vacuum deposition chamber;
(c) heating the crucible containing said zinc sulfide solids by induction to sublimate the zinc sulfide into a zinc sulfide vapor;
(d) transferring the polymer film from the supply roll to the take-up roll at a rate of at least 60 ft./min. and passing the polymer film in proximity to the crucible, and depositing the zinc sulfide vapor onto the polymer film to form a layer of zinc sulfide on the polymer film, wherein the thickness of the layer of zinc sulfide formed is at least 1000 Angstroms;
(e) passing the polymer film containing the zinc sulfide layer past a source of visible white light at a location between the location of the crucible containing the zinc sulfide and the take-up roll;
(f) monitoring the zinc sulfide layer that is deposited on the polymer film by visually observing the presence or absence of color generated from the surface of the zinc sulfide layer as the polymer film passes the source of visible white light; and
(g) adjusting the rate of transfer of the polymer film from the supply roll to the take-up roll in response to said monitoring step to thereby control the thickness of the zinc sulfide layer on the polymer film.
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Abstract
A method for making transparent, reflective films includes coating a polymer film with ZnS by charging a set of carbon crucibles with ZnS cubes or pellets. The crucibles are heated by induction in a vacuum deposition chamber having a supply roll of the polymer film and a take-up roll. The ZnS cubes sublimate at a rate matched to web advance to insure a coating thickness for colorless films of at least 1,000 angstroms. The thickness of the ZnS layer on the film is monitored by visual observation of color by a source of visible white light and the rate of transfer of the film is adjusted to control the thickness of the ZnS layer.
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17 Claims
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1. A method for coating polymer film with zinc sulfide, comprising the steps of:
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(a) placing a crucible containing zinc sulfide solids in a vacuum deposition chamber having a supply roll of the polymer film and a take-up roll for the polymer film; (b) evacuating the vacuum deposition chamber; (c) heating the crucible containing said zinc sulfide solids by induction to sublimate the zinc sulfide into a zinc sulfide vapor; (d) transferring the polymer film from the supply roll to the take-up roll at a rate of at least 60 ft./min. and passing the polymer film in proximity to the crucible, and depositing the zinc sulfide vapor onto the polymer film to form a layer of zinc sulfide on the polymer film, wherein the thickness of the layer of zinc sulfide formed is at least 1000 Angstroms; (e) passing the polymer film containing the zinc sulfide layer past a source of visible white light at a location between the location of the crucible containing the zinc sulfide and the take-up roll; (f) monitoring the zinc sulfide layer that is deposited on the polymer film by visually observing the presence or absence of color generated from the surface of the zinc sulfide layer as the polymer film passes the source of visible white light; and (g) adjusting the rate of transfer of the polymer film from the supply roll to the take-up roll in response to said monitoring step to thereby control the thickness of the zinc sulfide layer on the polymer film. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification