Method for producing textured thermoplastic film

• US 20020114923A1
• Filed: 11/01/2001
• Published: 08/22/2002
• Est. Priority Date: 11/14/1997
• Status: Active Grant

• Current Assignee: Sabic Innovative Plastics IP BV (Government of Saudi Arabia)
• Original Assignee: General Electric Company
• Inventors: Lilly, Kenneth Lee
• Granted Patent: US 6,855,415 B2
• Time in Patent Office: Days
• US Class Current: 428/141
• CPC Class Codes: B05D 1/42 by non-rotary members
• CPC Class Codes: B05D 3/067 Curing or cross-linking the coating
• CPC Class Codes: B29C 39/148 characterised by the shape of the surface
• CPC Class Codes: B29C 43/222 characterised by the shape of the surface
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 48/91 Heating, e.g. for cross linking
• CPC Class Codes: B29C 48/914 cooling drums
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/263 Coating layer not in excess of 5 mils thick or equivalent
• CPC Class Codes: Y10T 428/266 of base or substrate
• CPC Class Codes: Y10T 428/31 Surface property or characteristic of web, sheet or block
• CPC Class Codes: Y10T 428/31507 Of polycarbonate
• CPC Class Codes: Y10T 428/31511 Of epoxy ether
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane
• CPC Class Codes: Y10T 428/31935 Ester, halide or nitrile of addition polymer

Abstract

A product and a method for producing a product consisting of a thermoplastic substrate having a cured coating thereon. The coating consists of the ultra-violet radiation cured product of a brominated epoxy acrylate oligomer, a polyfunctional acrylate monomer, a silicone hard coat and a photoinitiator. The coated thermoplastic substrate has a low birefringence (<25 nm), and a low delta refractive index between the coating and thermoplastic substrate and a smooth upper surface having a gloss of at least 90% and a surface roughness of about 10.0 μm or less. In order to obtain such a product, the thermoplastic substrate must be prepared by first producing a substrate having a smooth lower surface and a textured upper surface to which is applied the curable coating. A thermoplastic substrate, particularly an aromatic polycarbonate substrate, is prepared by passing a heated substrate between a pair of rolls wherein the upper roll has a textured surface and the lower roll has a smooth polished surface.

The coated thermoplastic substrate has utility and optical media applications such as CD'"'"'s or CD-ROM discs because the coated thermoplastic substrate has excellent properties of low stress, low birefringence, virtually matching index of refraction of the coating and substrate and a smooth upper surface having minimal roughness. These properties allow transmission rather than reflection of light thus making the coated substrate acceptable for optical applications.

The thermoplastic substrate is preferably an aromatic polycarbonate.

Claims

1. A thermoplastic film substrate having low residual stress and having an upper and lower surface wherein said upper surface is textured, has a gloss of at least 85%, and a surface roughness of 20 to about 40 micrometers, and said lower surface is polished.

2. The film substrate of claim 1 wherein the upper surface has a gloss of at least 90%.

3. The film substrate of claim 1 wherein the film substrate is an aromatic polycarbonate.

4. A method of producing the thermoplastic film substrate of claim 1 comprising passing a thermoplastic film through a nip between an upper and a lower roll wherein the upper roll has a low friction surface which textures the upper surface of the thermoplastic film and the lower roll imparts a polished surface to the lower surface of the thermoplastic film substrate.

5. The method of claim 4 wherein the upper roll has a rubber surface.

6. The method of claim 4 wherein the roll has a polytetrafluoroethylene surface.

7. The method of claim 4 wherein the lower roll is a chrome-plated steel roll.

8. A coated thermoplastic film comprising the thermoplastic substrate of claim 1 and having an ultraviolet radiation cured acrylic coating layer on the upper surface of the thermoplastic film of claim 1 wherein said coated upper surface has (1) a surface gloss of at least 90%, (2) a birefringence of less than 25 nanometers, (3) a surface roughness of about 3.0 to about 10.0 micrometers and (4) a delta refractive index of less than about 0.1 between the coating and thermoplastic substrate;

said cured acrylic coating comprising the ultraviolet radiation reaction product of a brominated epoxy acrylic oligomer, a functional acrylate monomer, an organopolysiloxane hardcoat composition and a photoinitiator; and

wherein said cured coating is directly adhered to said thermoplastic substrate by heating the curable coating composition to a temperature between about 90°

F. and about 150°

F. and a ultraviolet radiation curing the heated applied coating composition whereby an interlocking bond between the substrate and cured coating is formed.

9. The coated thermoplastic film of claim 8 wherein the cured coating layer has a thickness of from 0.5 to about 5 mils.

10. The cured coated thermoplastic film of claim 8 has a thickness of about 5 to about 20 mils.

11. The coated thermoplastic film of claim 8 wherein the functional acrylate monomer is a mono-functional acrylate monomer.

12. The coated thermoplastic film of claim 8 wherein the delta refractive index is less than about 0.08.

13. The coated thermoplastic film of claim 8 wherein the delta refractive index is less than about 0.05.

14. The coated thermoplastic film of claim 8 wherein the thermoplastic film is an aromatic polycarbonate.

15. The coated thermoplastic film of claim 8 wherein the cured acrylic coating is the ultraviolet radiation reaction product of a coating composition comprising (a) more than 75 weight % of a brominated epoxy acrylate in combination with an acrylate monomer, b) less than 5 weight % of a photoinitator and c) less than 20 weight % of an organopolysiloxane hard coat composition said weight % being based on the total weight of the coating composition.