Coated plastic substrate

• US 5,718,967 A
• Filed: 10/11/1996
• Issued: 02/17/1998
• Est. Priority Date: 10/13/1995
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: O'Connor, Paul J., Tou, James C., Sedon, James H., Hu, Ing-Feng, Bales, Stephen E., Perettie, Donald J.
• Primary Examiner(s): NAKARANI, DHIRAJLAL S
• Application Number:
  US08/729,101
• Time in Patent Office: 494 Days
• Field of Search: 428/212, 428/213, 428/214, 428/215, 428/216, 428/412, 428/447, 428/448, 427/488, 427/489, 427/492, 427/493, 427/495, 427/579
• US Class Current: 428/216
• CPC Class Codes: B05D 1/62 Plasma-deposition of organic layers plasma deposition in general C23C14/00, C23C16/00
• CPC Class Codes: B05D 2201/00 Polymeric substrate or laminate
• CPC Class Codes: B05D 7/54 No clear coat specified
• CPC Class Codes: C08J 7/123 Treatment by wave energy or particle radiation C08J7/18 takes precedence
• CPC Class Codes: C23C 16/515 using pulsed discharges
• CPC Class Codes: G02F 1/133305 Flexible substrates, e.g. plastics, organic film
• CPC Class Codes: G02F 1/133345 Insulating layers G02F1/1335, G02F1/1337, G02F1/135, G02F1/136 take precedence
• CPC Class Codes: Y10T 428/24967 Absolute thicknesses specified
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/31507 Of polycarbonate
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

The present invention is a laminate which comprises:

a) a plastic substrate having a surface;

b) an adhesion promoter layer which is a first plasma polymerized organosilicon compound deposited on the surface of the substrate in the substantial absence of oxygen; and

c) a protective coating layer which is a second plasma polymerized organosilicon compound deposited on the surface of the adhesion layer at a power density from about 10⁶ J/kg to about 10⁸ J/kg, and in the presence of a sufficient stoichiometric excess of oxygen to form a silicon polymer of SiO₁.8-2.4 C₀.3-1.0 and H₀.7-4.0.

The coating layer provides abrasion and solvent resistance for the substrate, and the adhesion promoter prevents the coating layer from peeling off the substrate. The coated plastic substrate can be used in liquid crystal display devices as an alternative to glass.

Claims

1. A laminate which comprises:

a) a plastic substrate having a surface;

b) an adhesion promoter layer which is a first plasma polymerized organosilicon compound deposited on the surface of the substrate at a power level in the range of about 5×

10⁷ J/kg to about 5×

10⁹ J/kg, and in the substantial absence of oxygen; and

c) a protective coating layer which is a second plasma polymerized organosilicon compound deposited on the surface of the adhesion layer at a power density from about 10⁶ J/kg to about 10⁸ J/kg, and in the presence of a higher level of oxygen than used in step (b).

2. The laminate of claim 1 which further comprises an SiO_x layer which is a plasma polymerized third organosilicon compound deposited on the surface of the layer of the protective coating layer, in the presence of a stoichiometric excess of oxygen, and at a power density of at least about twice the power density used to form the protective coating layer.

3. The laminate of claim 2 which further comprises alternating layers of the protective coating layer and the SiO_x layer.

4. The laminate of claim 2 wherein the first, the second, and the third organosilicon polymers that are plasma polymerized are each independently selected from the group consisting of dimethoxydimethylsilane, methyltrimethoxysilane, tetramethoxysilane, methyltriethoxysilane, diethoxydimethylsilane, methyltriethoxysilane, triethoxyvinylsilane, tetraethoxysilane, dimethoxymethylphenylsilane, phenyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, diethoxymethylphenylsilane, tris(2-methoxyethoxy)vinylsilane, phenyltriethoxysilane, dimethoxydiphenylsilane, tetramethyldisiloxane, hexamethyldisiloxane, hexamethylsilazane, and tetramethylsilazane.

5. The laminate of claim 4 wherein the first, the second, and the third organosilicon polymers that are plasma polymerized are tetramethyldisiloxane.

6. The laminate of claim 2 wherein the substrate is a carbonate polymer which comprises repeat units of a reaction product of a carbonate precursor with an aromatic diol.

7. The laminate of claim 6 wherein the aromatic diol comprises resorcinol, catechol, hydroquinone, a dihydroxynaphthalene, a dihydroxyanthracene, a bis(hydroxyaryl) fluorene, a dihydroxyphenanthrene, a dihydroxybiphenyl, or a bis(hydroxyphenyl) propane.

8. The laminate of claim 7 wherein the carbonate polymer comprises repeat units of 9,9-bis(4-hydroxyphenyl)fluorene and bisphenol A.

9. The laminate of claim 8 wherein the ratio of the repeat units of 9,9-bis(4-hydroxyphenyl)fluorene and bisphenol A is from about 40:

60 to about 70;

30.

10. The laminate of claim 1 wherein the T_g of the substrate is in the range of from about 180°

C. to about 240°

C., and the SOC of the laminate is in the range of from about -1000 to about 1000 Brewsters, which laminate is optically clear.

11. A laminate which comprises:

a) a plastic substrate having a surface and a thickness of not less than about 0.1 mm and not more than about 10 mm;

b) an adhesion promoter layer which is a plasma polymerized tetramethyldisiloxane deposited on the surface of the substrate at a power level in the range of about 5×

10⁷ J/kg to about 5×

10⁹ J/kg and in the substantial absence of oxygen, which adhesion promoter has a thickness of not less than about 1000 Å and

not more than 2000 Å

;

c) a protective coating layer which is a plasma polymerized tetramethyldisiloxane deposited on the surface of the adhesion promoter layer at a power density from about 10⁶ J/kg to about 10⁸ J/kg in the presence of a sufficient stoichiometric excess of oxygen with respect to tetramethyldisiloxane to form an organosilicon compound having the formula SiO₁.8-2.4 C₀.3-1.0 and H₀.7-4.0 that contains trapped water and at least one of the following functional groups;

--Si--O--Si--, --Si--CH₂ --, --Si--H, or --Si--OH;

wherein the thickness of the protective coating layer is not less than about 0.1 micron and not greater than about 2 microns; and

d) an SiO_x layer which is a layer of a plasma polymerized tetramethyldisiloxane deposited on the surface of the protective coating layer, in the presence of a stoichiometric excess of oxygen, and at a power density of at least four times the power density used to form the protective coating layer, wherein the SiO_x layer has a thickness of not less than about 0.05 micron and not more than about 1 micron.

12. A laminate which comprises:

a) a plastic substrate having a surface; and

b) an adhesion promoter layer which is a plasma polymerized organosilicon compound deposited on the surface of the substrate at a power level in the range of about 5×

10⁷ J/kg to about 5×

10⁹ J/kg, and in the substantial absence of oxygen.