Abrasion and/or scratch resistant article comprising an impact resistant photochromic polyurethane coating, and process of preparation thereof

1. A process for obtaining an impact resistant, abrasion and/or scratch resistant photochromic article comprising a substrate having two main faces comprising:

preparing a curable coating composition comprising at least one unblocked polyisocyanate terminated polyurethane pre-polymer, at least one polyol, and at least one photochromic agent; wherein the polyurethane pre-polymer has a number average molecular weight of from 1,000 to 6,000 g/mol

depositing the prepared curable coating composition onto at least part of a main face of the substrate;

curing said curable coating composition for 10 minutes or less, at a temperature lower than or equal to 100° C. so as to form an impact resistant photochromic coating; and

forming an abrasion and/or scratch resistant coating on the impact resistant photochromic coating or forming a protective coating on the impact resistant photochromic coating and then forming an abrasion and/or scratch resistant coating on said protective coating.

2. The process of claim 1 , wherein the substrate is made of mineral glass or organic glass.

3. The process of claim 2 , wherein the substrate is an organic glass comprising at least one thermoplastic material or thermosetting (cross-linked) material.

4. The process of claim 1 , wherein the curable coating composition is cured for 5 minutes or less.

5. The process of claim 1 , wherein the curable coating composition is cured at a temperature lower than or equal to 95° C.

6. The process of claim 1 , wherein the impact resistant photochromic coating presents a tacky surface at 20-25° C. after curing.

7. The process of claim 1 , wherein the abrasion and/or scratch resistant coating is made from a thermally curable composition.

8. The process of claim 7 , wherein the abrasion and/or scratch resistant coating is cured at a temperature lower than or equal to 100° C.

9. The process of claim 1 , wherein the abrasion and/or scratch resistant coating is made from a composition comprising a hydrolyzate of an epoxytrialkoxysilane and dialkyldialkoxysilane, colloidal mineral fillers and a catalytic amount of an aluminum-based curing catalyst.

10. The process of claim 1 , wherein a protective coating is interleaved between said impact resistant photochromic coating and said abrasion and/or scratch resistant coating.

11. The process of claim 10 , wherein the protective coating is made from a composition comprising at least one multifunctional (meth)acrylate.

12. The process of claim 1 , wherein an anti-reflection coating is applied on the abrasion- and/or scratch-resistant coating.

13. The process of claim 1 , wherein the curable coating composition further comprises at least one solvent.

14. The process of claim 13 , wherein the solvent is N-methylpyrrolidone, tetrahydrofuran, acetonitrile, dioxane, or a mixture thereof.

15. The process of claim 1 , wherein the polyol is a polyol with a number average molecular weight less than 400, a polyester polyol, a polyether polyol, a polyol containing an amide group, a polyacrylic polyol, an epoxypolyol, a polyvinyl polyol, or a urethane polyol.

16. The process of claim 15 , wherein the polyol is a polyester polyol.

17. The process of claim 16 , wherein the polyol has a number average molecular weight ranging from 400 to 10,000 g/mol.

18. The process of claim 17 , wherein the polyol has a number average molecular weight ranging from 500 to 6,000 g/mol.

19. The process of claim 16 , wherein the polyester polyol is prepared by the reaction of a polyol and a lactone.

20. The process of claim 19 , wherein the lactone is ε-caprolactone, propiolactone or butyrolactone.

21. The process of claim 19 , wherein the polyol is neopentyl glycol, trimethylol propane, diethylene glycol, or glycerol.

22. The process of claim 1 , wherein the polyol has at least three hydroxyl groups.

23. The process of claim 22 , wherein the polyol is a polycaprolactone triol.

24. The process of claim 1 , wherein the polyurethane pre-polymer is obtained by the reaction of an excess of at least one polyisocyanate with at least one polyol.

25. The process of claim 24 , wherein the polyisocyanate and polyol for obtaining the polyurethane pre-polymer are used in an amount such that the molar ratio of NCO to OH groups is from 2:1 to 8:1.

26. The process of claim 24 , wherein the polyisocyanate is a diisocyanate.

27. The process of claim 24 , wherein the polyisocyanate is an aliphatic diisocyanate further defined as hexamethylene-1,6-diisocyanate, isophorone diisocyanate, ethylene diisocyanate, dodecane-1,12-diisocyanate, cyclohexane-1,3-diisocyanate, or bis-(4-isocyanato-cyclohexyl)-methane.

28. The process of claim 1 , wherein the polyol and the unblocked polyisocyanate terminated polyurethane pre-polymer are used in an amount such that the molar ratio of NCO to OH groups is from 0.8 to 1.2.

29. The process of claim 1 , wherein the photochromic agent is an organic compound further defined as an oxazine derivative, a chromene, photochromic derivative of chromene, fulgide, fulgimide, or organometallic derivative of dithizonate.

30. The process of claim 1 , wherein the photochromic agent is a spirooxazine, further defined as a spiro[indolino] benzoxazine, a spiro[indolino] naphtoxazine, or a spiro[indolino] pyridobenzoxazine.

31. The process of claim 1 , wherein the curable coating composition further comprises at least one catalyst further defined as a tin catalyst or amine catalyst.