Process for depositing an anti-reflective layer on a substrate

Patent metadata

Field	Value
Publication number	US-9561525-B2
Application number	US-201213982339-A
Country	US
Kind code	B2
Filing date	Feb 6, 2012
Priority date	Feb 11, 2011
Publication date	Feb 7, 2017
Grant date	Feb 7, 2017

Abstract

The present invention relates to a process for depositing an anti-reflective layer on a transparent flat substrate comprising the steps of providing a liquid coating composition comprising at least one solvent, at least one inorganic oxide precursor, and at least one pore forming agent; applying the coating composition to the substrate; drying the applied coating layer, and curing the coating layer; wherein during drying a gas flow is provided to the substrate at a flow rate of between 0.2 and 6 m/s. The advantage of this process is that defects visible in edge areas of the coated substrate can be significantly reduced.

First claim

The invention claimed is:

1. A process for depositing an anti-reflective layer on a transparent flat substrate comprising the steps of:
a) providing a liquid coating composition having a solids content of up to about 10 mass % and comprising at least one solvent, at least one inorganic oxide precursor, and a core-shell nano-particle with a silica shell and an organic core as a pore forming agent;
b) applying the coating composition onto a transparent flat glass plate or sheet as a substrate to thereby form a coating layer on the substrate between edges thereof;
c) drying the applied coating layer on the substrate at a drying temperature of ambient conditions or up to 80° C. by providing a flow of gas at a gas flow rate range of between 0.5 and 6 m/s to the coating layer at least along the edges of the substrate and an area adjacent the edges of the substrate; and
d) curing the coating layer on the substrate at a curing temperature of from 350° C. to 900° C.

2. The process according to claim 1 , wherein the flow of gas is provided as a laminar flow of gas.

3. The process according to claim 1 , wherein the gas flow rate is between 1 and 3 m/s.

4. The process according to claim 1 , wherein the flow of gas flows at least over an area of about 25 mm from the edges of the substrate.

5. The process according to claim 1 , wherein the gas is air with a relative humidity of at most 50%.

6. The process according to claim 1 , wherein the gas has a temperature of at most 25° C. higher than the substrate.

7. The process according to claim 1 , wherein the solvent is an alcohol.

8. The process according to claim 1 , wherein the inorganic oxide precursor comprises a metal alkoxide.

9. The process according to claim 1 , wherein step b) is practiced by applying the coating composition to the substrate with a dip-coating, roll-coating or slot die-coating method.

10. The process according to claim 1 , wherein step (c) is practiced by providing a local flow of gas at the edges of the substrate combined with a flow of gas covering a full width of the substrate to thereby establish a gas flow gradient with increased flow rate at the edges of the substrate but within the gas flow rate range of 0.5 and 6 m/s.

11. The process according to claim 10 , wherein step b) comprises dip-coating the substrate by submersing the substrate into a coating bath comprising the coating composition, and thereafter withdrawing the substrate from the coating bath while drying the applied coating layer applied to the substrate according to step c).

12. A process for depositing an anti-reflective layer on a transparent flat glass plate or sheet comprising the steps of:
(a) providing a flat glass plate or sheet as a substrate for coating having opposed lateral edges and opposed top and bottom edges;
(b) providing a coating bath comprising a liquid coating composition having a solids content of up to about 10 mass % and comprising at least one solvent, at least one inorganic oxide precursor, and a core-shell nano-particle with a silica shell and an organic core as a pore forming agent;
(c) dip-coating the substrate with the coating composition by submersing the substrate into the coating bath, and withdrawing the substrate from the coating composition at a substantially constant withdrawal speed to thereby coat the coating composition onto the substrate to thereby form a coating layer on the substrate between the lateral, top and bottom edges thereof;
(d) drying the applied coating layer on the substrate while withdrawing the substrate from the coating bath at a drying temperature of ambient conditions or up to 80° C. by:
(d1) providing a non-turbulent streamline flow of gas in parallel layers with a relatively steady velocity of a gas flow rate range of between 0.5 and 6 m/s to the coating layer at an area locally along at least the lateral edges of the substrate;
(d2) providing a flow of gas covering a full width of the substrate between the lateral edges of the substrate to thereby establish a gas flow gradient across the full width of the substrate such that an increased flow rate of the gas is locally provided at the lateral edges of the substrate within the gas flow rate range of 0.5 and 6 m/s; and
(d3) providing a flow of gas at a flow rate higher than the gas flow rate range of 0.5 and 6 m/s locally along the bottom edge of the substrate when the bottom edge of the substrate is withdrawn from the coating bath; and thereafter

(e) curing the coating layer on the substrate at a curing temperature of from 350° C. to 900° C.

13. The process according to claim 12 , wherein step (d3) comprises providing a gas flow at an increased flow rate along the bottom edge of the substrate or locally applying an additional gas flow along the bottom edge of the substrate for a predetermined time period.

Assignees

• Aben Gerardus
• De Rijk Ronnie Bernardus Maria
• Vrijaldenhoven Patrick Wilhelmus Antonius
• Dsm Ip Assets Bv

Inventors

• Aben Gerardus
• De Rijk Ronnie Bernardus Maria
• Vrijaldenhoven Patrick Wilhelmus Antonius

Classifications

• B05D5/061 Primary

  Special surface effect · CPC title

• C03C2217/425

  consisting of a porous layer · CPC title

• C03C17/007 Primary

  containing a dispersed phase, e.g. particles, fibres or flakes, in a continuous phase · CPC title

• B05D3/04

  by exposure to gases · CPC title

• C03C2217/732

  made of a single layer · CPC title