Optical film

• US 4,735,869 A
• Filed: 09/18/1986
• Issued: 04/05/1988
• Est. Priority Date: 01/18/1985
• Status: Expired due to Fees

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Morita, Yoshio
• Primary Examiner(s): Lusignan, Michael R.
• Application Number:
  US06/925,637
• Time in Patent Office: 565 Days
• Field of Search: 427/164, 427/165, 427/169, 427/299, 427/307, 427/309, 428/689, 428/702, 350/166
• US Class Current: 428/702
• CPC Class Codes: C03C 17/256 Coating containing TiO2
• CPC Class Codes: C03C 2217/212 TiO2
• CPC Class Codes: C03C 2217/72 Decorative coatings
• CPC Class Codes: C03C 2218/111 by dipping, immersion
• 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: Y10S 359/90 Methods

Abstract

Process of forming a titanium dioxide film with controlled optical thickness on a surface comprising a pretreating step, at least one film-forming step and optionally a nucleation step between the pretreating and film-forming step, and articles coated with such a film.

Claims

1. A process of forming a titanium dioxide film with controlled optical thickness on a surface comprising:

(a) pretreating said surface by soaking in an aqueous solution containing an effective amount of a ferrous, ferric, stannous or stannic salt, or a mixture thereof; and

(b) at least one film-forming step comprising, soaking said deposit obtained in step (a) in an acidic aqueous solution containing at least 0.3 millimole Ti/l.

2. Process according to claim 1 wherein the pretreating step is performed in a solution containing ferric or ferrous chloride together with a polyol.

3. A process of claim 1 wherein step (a) further comprises heating said surface in an acidic aqueous solution of a water soluble titanium ester or titanium salt.

4. Process according to claim 1 wherein the film-forming step is performed more than once.

5. Process according to claim 1 whereby the titanium dioxide film is formed on the surface of mica flakes.

6. Process according to claim 1 wherein the baking is performed optionally before and/or after the film-forming step.

7. A process of claim 1 wherein said solution of step (a) further comprising a polyol.

8. A process of claim 1 further comprising,

(c) between steps (a), and (b) a nucleation step comprising soaking said pretreated surface in an acidic aqueous solution of a titanium ester and/or titanium salt containing at least 0.1 millimole/l, followed by baking at at least 300°

C.

9. An article coated with thin titanium dioxide films according to the process of claim 1.

10. A process of forming a substantially uniform titanium dioxide film with controlled optical thickness on a surface comprising:

(a) pretreating said surface by heating in an acidid aqueous solution of an effective amount of a water-soluble titanium ester or titanium salt, thereby forming a deposit on said surface; and

(b) at least one film-forming step comprising, after removal of said surface from said solution, soaking said deposit obtained in step (a) in an acidic aqueous solution containing at least 0.3 millimole Ti/l.

11. A process of claim 10 further comprising between steps (a), and (b):

(c) a nucleation step comprising soaking said pretreated surface in an acidic aqueous solution of a titanium ester and/or titanium salt containing at least 0.1 millimole/l, followed by baking at at least 300°

C.

12. A process of claim 10 wherein said film-forming step is performed more than once.

13. A process of claim 10 wherein said titanium dioxide film is formed on the surface of mica flakes.

14. A process of claim 10 wherein said baking is performed before, and/or after said film-forming step.

15. A process of claim 10 wherein said film-forming step is conducted more than once.