Process for coating a synthetic polymer sheet material with a durable abrasion-resistant vitreous composition

• US 4,052,520 A
• Filed: 08/12/1976
• Issued: 10/04/1977
• Est. Priority Date: 09/30/1974
• Status: Expired due to Term

• Current Assignee: American Optical Corporation
• Original Assignee: American Optical Corporation
• Inventors: Chang, Leei, Verburg, John A.
• Primary Examiner(s): Smith, Ronald H.
• Assistant Examiner(s): Lawrence, Evan K.
• Application Number:
  US05/713,934
• Time in Patent Office: 418 Days
• Field of Search: 350/175 NG, 351/166, 427/163, 427/164, 427/248 C, 427/248 J, 427/322, 427/399, 427/299, 428/412
• US Class Current: 427/164
• CPC Class Codes: C03C 2217/78 Coatings specially designed to be durable, e.g. scratch-resistant
• CPC Class Codes: C23C 14/10 Glass or silica
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings
• CPC Class Codes: G02C 7/02 Lenses; Lens systems ; Methods of designing lenses
• CPC Class Codes: Y02T 50/60 Efficient propulsion technologies, e.g. for aircraft
• CPC Class Codes: Y10T 428/31507 Of polycarbonate

Abstract

There is disclosed a process for improving the adhesion of an evaporable glass coating on a synthetic polymer sheet material by the application of a base vitreous coating of a mixture of silicon dioxide and silicon monoxide by evaporating silicon monoxide under vacuum in an oxygen atmosphere so that in addition to silicon monoxide, a silicon dioxide condensate is condensed on the outer surface of the sheet. An outer vitreous coating is subsequently applied over said base coating. The evaporative glass outer coating can be formed essentially from boron oxide and silicon dioxide containing less than 5% by weight of sodium oxide. The evaporative glass coating can also be of fused silica, or a boro-silicate glass sold under the trademark "Pyrex".

Claims

1. The method of coating a sheet of material of diallyl glycol carbonate polymer comprising the steps of:

1. first step -- hydroxylating the sheet surface to be coated;

2. second step -- applying to the hydroxylated surface of the sheet by vacuum deposition a base coating of a material selected from the group consisting of silicon monoxide and a mixture of silicon dioxide and silicon monoxide, by evaporation of silicon monoxide in an oxygen atmosphere under a vacuum lower than 1 ×

10^-4 torr, said base coating being at least one molecule in thickness; and

3. third step -- applying to the coated surface of the sheet of the second step by vacuum deposition an outer coating of evaporable glass, said evaporable glass being in a thickness of about one micrometer or higher, said glass coating being applied at a pressure lower than 5 ×

10^-4 torr.

2. A method according to claim 1 wherein said process includes as the first step the hydroxylating of the surface of said sheet by alkali treatment.

3. A method according to claim 2 wherein said alkali is selected from the group consisting of sodium hydroxide and potassium hydroxide.

4. A method according to claim 3 wherein said alkali is utilized as an aqueous solution.

5. A method according to claim 2 wherein said vacuum deposition of the evaporable glass is effected in a vacuum lower than 5 ×

10^-4 torr.

6. A method according to claim 2 wherein said evaporable glass is selected from the group consisting of (1) a glass consisting essentially of boron oxide and silicon dioxide containing less than 5% by weight of Na₂ O (2) fused silica, and (3) a borosilicate glass of the following weight percentage composition:

SiO₂ -- 80.2

B₂ o₃ -- 13.5

al₂ O₃ -- 2.2

Na₂ O -- 4.0

CaO -- 0.1

7. A method according to claim 2 wherein said vacuum deposition of said base coating is effected in a vacuum lower than 1 ×

10^-4 torr.

8. A method according to claim 2 wherein said alkali is utilized as an aqueous solution of sodium hydroxide and wherein said evaporable glass is a glass comprising boron oxide and silicon dioxide and up to 5% by weight of Na₂ O and is applied in a thickness of about 4 micrometers.

9. The method of coating a sheet of material of an aromatic polycarbonate comprising the steps of:

1. first step -- applying to the sheet by vacuum deposition a base coating of a material selected from the group consisting of silicon monoxide and a mixture of silicon dioxide and silicon monoxide, by evaporation of silicon monoxide in an oxygen atmosphere under a vacuum lower than 1 ×

10^-4 torr, said base coating being at least one molecule in thickness; and

2. second step -- applying to the coated surface of the sheet of the first step by vacuum deposition an outer coating of evaporable glass under vacuum, said evaporable glass being in a thickness of about one micrometer or higher, said glass coating being applied at a pressure lower than 5 ×

10^-4 torr.