Methods for making polymeric substrates comprising a haze-free, self-healing coating and coated substrates made thereby

1. A method for making a haze-free coated polymeric substrate at least partially coated with a self-healing coating, comprising:

(a) depositing upon at least a portion of the polymeric substrate a self-healing coating composition comprising:

(i) a polycarbonate comprising at least two isocyanate reactive groups per molecule; and

(ii) a blocked polyisocyanate curing agent, wherein the blocking agent deblocks at a temperature no higher than 130° C., and wherein the blocked polyisocyanate curing agent comprises a tricarbamoyl triazine compound having the formula C 3 N 3 (NHCOXR) 3 , wherein X is nitrogen, oxygen, sulfur, phosphorus, or carbon, and R is a lower alkyl group having 1 to 12 carbon atoms or a mixture of lower alkyl groups having 1 to 12 carbon atoms; and

(b) curing the coating composition by heating the composition to a temperature at or above the temperature at which the blocking agent deblocks, wherein

the method produces a haze-free coated polymeric substrate having thereon a self-healing coating having a dry film thickness of at least 1 mil.

2. The method of claim 1 , wherein the substrate comprises a polycarbonate substrate.

3. The method of claim 1 , wherein the polycarbonate comprises a polycarbonate polyol.

4. The method of claim 3 , wherein the polycarbonate polyol comprises a polycarbonate diol.

5. The method of claim 4 , wherein the polycarbonate diol has a molecular weight of from 500 to 5,000.

6. The method of claim 4 , wherein the polycarbonate diol is the reaction product of reactants comprising a dialkyl carbonate and an aliphatic diol.

7. The method of claim 6 , wherein the aliphatic diol comprises 1,2-propane diol, 1,6-hexane diol, or a mixture thereof.

8. The method of claim 1 , wherein X is oxygen.

9. The method of claim 1 , wherein R has 1 to 8 carbon atoms.

10. The method of claim 9 , wherein R is methyl, butyl, or a mixture thereof.

11. The method of claim 1 , wherein the coating composition further comprises:

a polysiloxane comprising at least one structural unit represented by the general formula R 1 n R 2 m SiO (4-n-m)/2 , wherein each R 1 , which may be the same or different, represents H, OH, a monovalent hydrocarbon group, or a monovalent siloxane group; each R 2 , which may be the same or different, represents an isocyanate reactive group, wherein m and n fulfill the requirements of 0<n<4, 0<m<4 and 2≦(m+n)<4.

12. The method of claim 11 , wherein each R 2 represents a hydroxyl group.

13. The method of claim 11 , wherein the polysiloxane has a structure represented by

the formula

wherein:

m has a value of at least 1;

m′ ranges from 0 to 75;

n ranges from 0 to 75;

n′ ranges from 0 to 75;

each R, which may be the same or different, is selected from H, OH, a monovalent hydrocarbon group, a monovalent siloxane group, and mixtures thereof;

and —R a comprises the structure —R 3 —X, wherein

—R 3 is selected from an alkylene group, an oxyalkylene group, an alkylene aryl group, an alkenylene group, an oxyalkenylene group, and an alkenylene aryl group; and

X represents an isocyanate reactive group.