LOW REFRACTIVE INDEX COMPOSITION, ABRASION RESISTANT ANTI-REFLECTIVE COATING, AND METHOD FOR FORMING ABRASION RESISTANT ANTI-REFLECTIVE COATING

• US 20100311868A1
• Filed: 11/24/2008
• Published: 12/09/2010
• Est. Priority Date: 11/30/2007
• Status: Abandoned Application

• Current Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Original Assignee: E. I. du Pont de Nemours and Company (Corteva, Inc.)
• Inventors: Bekiarian, Paul Gregory, Kourtakis, Kostantinos
• Application Number:
  US12/744,694
• Publication Number:
  US 20100311868A1
• Time in Patent Office: Days
• US Class Current: 523/218
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C08K 5/5425 containing at least one C=C bond
• CPC Class Codes: C08L 27/12 containing fluorine atoms
• CPC Class Codes: C09D 127/16 Homopolymers or copolymers of vinylidene fluoride
• CPC Class Codes: G02B 1/105 Protective coatings
• CPC Class Codes: G02B 1/111 using layers comprising organic materials
• CPC Class Codes: G02B 1/14 Protective coatings, e.g. hard coatings

Abstract

A low refractive index composition is provided comprising the reaction product of: (i) a fluoroelastomer having at least one cure site; (ii) a multiolefinic crosslinker; (iii) a free radical polymerization initiator; (iv) a nanosilica composite comprising: (iv-a) a plurality of nanosilica particles, and (iv-b) at least one of a hydrolysis and condensation product of an oxysilane having a carbon-carbon double bond, wherein the at least one of a hydrolysis and condensation product is formed by contacting, in the presence of an organic acid and a lower alkyl alcohol, the oxysilane with from about 3 to about 9 moles of water per mole of hydrolyzable functional group bonded to the silicon of the oxysilane. The present invention further provides abrasion resistant anti-reflective coatings formed from these low refractive index compositions and methods for forming abrasion resistant anti-reflective coatings for optical display substrates from these low refractive index compositions.

Claims

1. A low refractive index composition comprising a reaction product of:

(i) a fluoroelastomer having at least one cure site;

(ii) a multiolefinic crosslinker;

(iii) a free radical polymerization initiator;

(iv) a nanosilica composite comprising;

(iv-a) a plurality of nanosilica particles, and

(iv-b) at least one of a hydrolysis and condensation product of an oxysilane having a carbon-carbon double bond, wherein said at least one of a hydrolysis and condensation product is formed by contacting, in the presence of an organic acid and a lower alkyl alcohol, said oxysilane with from about 3 to about 9 moles of water per mole of hydrolyzable functional group bonded to the silicon of said oxysilane.

2. The low refractive index composition of claim 1, wherein said plurality of nanosilica particles comprises a plurality of solid nanosilica particles, and wherein said plurality of solid nanosilica particles comprises at least about 10 volume % of said low refractive index composition.

3. The low refractive index composition of claim 2 wherein said plurality of solid nanosilica particles have at least about 50% but less than 100% of reactive silanols functionalized with an unreactive substituent.

4. The low refractive index composition of claim 1, wherein said nanosilica composite is aged for at least about 1 hour at a temperature of at least about 25°

C. prior to formation of said reaction product.

5. The low refractive index composition of claim 1, wherein said organic acid has a pK_a in water at 25°

C. of at least about 4.7.

6. The low refractive index composition of claim 1, wherein said plurality of nanosilica particles comprises a plurality of solid nanosilica particles, and wherein the amount of said oxysilane used to form said at least one of a hydrolysis and condensation product and the amount of said plurality of solid nanosilica particles is from about 0.8 g to about 110 g of said oxysilane per 100 g of said plurality of solid nanosilica particles.

7. The low refractive index composition of claim 1, wherein said plurality of nanosilica particles comprises a plurality of porous nanosilica particles, and wherein the amount of said oxysilane used to form said at least one of a hydrolysis and condensation product and the amount of said plurality of porous nanosilica particles is from about 0.8 g to about 120 g of said oxysilane per 100 g of said plurality of porous nanosilica particles.

8. An article comprising a substrate having an abrasion resistant anti-reflective coating having a scratched percent of about 10 or less as determined by Method 4 after abrasion by Method 1, said abrasion resistant anti-reflective coating comprising a reaction product of:

(i) a fluoroelastomer having at least one cure site;

(ii) a multiolefinic crosslinker;

(iii) a free radical polymerization initiator; and

(iv) a nanosilica composite, comprising;

(iv-a) a plurality of solid nanosilica particles comprising at least about 10 volume percent of said abrasion resistant anti-reflective coating; and

(iv-b) at least one of a hydrolysis and condensation product of an oxysilane having a carbon-carbon double bond, and wherein said at least one of a hydrolysis and condensation product is formed by contacting, in the presence of an organic acid and a lower alkyl alcohol, said oxysilane with from about 3 to about 9 moles of water per mole of hydrolyzable functional group bonded to the silicon of said oxysilane; and

wherein said nanosilica composite is aged for at least about 1 hour at a temperature of at least about 25°

C. prior to formation of said reaction product.

9. The article of claim 8, wherein said plurality of solid nanosilica particles has at least about 50% but less than 100% of reactive silanols functionalized with an unreactive substituent.

10. The article of claim 8, wherein said organic acid has a pK_a in water at 25°

C. of at least about 4.7.

11. The article of claim 8, wherein the amount of said oxysilane used to form said at least one of a hydrolysis and condensation product and the amount of said plurality of solid nanosilica particles is from about 0.8 g to about 110 g of said oxysilane per 100 g of said plurality of solid nanosilica particles.

12. The article of claim 8, wherein said plurality of solid nanosilica particles further comprises a plurality of porous nanosilica particles, and wherein the amount of said oxysilane used to form said at least one of a hydrolysis and condensation product and the amount of said plurality of porous nanosilica particles is from about 0.8 g to about 120 g of said oxysilane per 100 g of said plurality of porous nanosilica particles.

13. A method for forming an abrasion resistant anti-reflective coating on a substrate, said abrasion resistant anti-reflective coating having a scratched percent of about 10 or less as determined by Method 4 after abrasion by Method 1, comprising:

(i) combining;

(i-a) at least one of a hydrolysis and condensation product of an oxysilane having a carbon-carbon double bond, wherein said at least one of a hydrolysis and condensation product is formed by contacting, in the presence of an organic acid and a lower alkyl alcohol, said oxysilane with from about 3 to about 9 moles of water per mole of hydrolyzable functional group bonded to the silicon of said oxysilane, and

(i-b) a plurality of solid nanosilica particles to form a nanosilica composite precursor, said plurality of solid nanosilica particles comprising at least about 10 volume percent of said abrasion resistant anti-reflective coating;

(ii) ageing said nanosilica composite precursor for at least about 1 hour at a temperature of at least about 25°

C. to form a nanosilica composite;

(iii) combining said nanosilica composite, a fluoroelastomer having at least one cure site, a multiolefinic crosslinker, and a free radical polymerization initiator to form an uncured composition;

(iv) applying a coating of said uncured composition on said substrate to form an uncured composition coating on said substrate; and

(v) curing said uncured composition coating and thereby forming said abrasion resistant anti-reflective coating on said substrate.

14. The method of claim 13, wherein said plurality of solid nanosilica particles has at least about 50% but less than 100% of reactive silanols functionalized with an unreactive substituent.

15. The method of claim 13, wherein said organic acid has a pK_a in water at 25°

C. of at least about 4.7.

16. The method of claim 13, wherein the amount of said oxysilane used to form said at least one of a hydrolysis and condensation product and the amount of said plurality of solid nanosilica particles is from about 0.8 g to about 110 g of said oxysilane per 100 g of said plurality of solid nanosilica particles.

17. The method of claim 13, wherein said nanosilica composite precursor further comprises a plurality of porous nanosilica particles, and wherein the amount of said oxysilane used to form said at least one of a hydrolysis and condensation product and the amount of said plurality of porous nanosilica particles is from about 0.8 g to about 120 g of said oxysilane per 100 g of said plurality of porous nanosilica particles.