Asymmetric multi-layer composites and processes for producing the same

1. A multi-layer composite comprising:

(a) a first scratch-resistant coating layer;

(b) a thermoplastic layer; and

(c) a second scratch-resistant coating layer;

wherein the first scratch-resistant coating layer and the second scratch-resistant coating layer are disposed on opposing sides of the thermoplastic layer;

wherein the first scratch-resistant coating and the second scratch-resistant coating each comprise a top coat layer having a thickness, and wherein the first coating and the second coating differ only in the thicknesses of their top coat layers;

and wherein the first scratch-resistant coating layer and the second scratch-resistant coating layer are selected such that a multi-layer composite having the first scratch-resistant layer disposed on both sides of the thermoplastic layer has a lower critical impact speed for tough/brittle transition at −30 ° C. according to DIN EN ISO 6603-1 than a multi-layer composite having the second scratch-resistant layer disposed on both sides of the thermoplastic layer.

2. The multi-layer composite according to claim 1 , wherein the second scratch-resistant coating layer has an impact speed for tough/brittle transition at −30 ° C. according to DIN EN ISO 6603-1 of greater than 2.5 m/s when the multi-layer composite has a thickness of 5 mm and the second scratch-resistant coating layer is disposed on the side of the thermoplastic layer which is subject to tensile forces during the DIN EN ISO 6603-1 testing.

3. The multi-layer composite according to claim 1 , wherein the first coating comprises: one or more compounds selected from the group consisting of organosilicon compounds of the general formula R′ n Si(OR) 4-n , and partial condensates thereof; an inorganic finely divided compound; an UV absorber; and an alcohol-based solvent.

4. The multi-layer composite according to claim 1 , wherein the second coating comprises: one or more compounds selected from the group consisting organosilicon compounds of the general formula R′ n Si(OR) 4-n , and partial condensates thereof; inorganic nanoparticles; an alcohol-based solvent; an acrylate-based organic adhesion promoter; and, optionally, a UV absorber.

5. The multi-layer composite according to claim 1 , further comprising a primer layer disposed between the thermoplastic layer and one or both of the first scratch-resistant coating layer and the second scratch-resistant coating layer.

6. The multi-layer composite according to claim 5 , wherein the primer layer or layers comprise polymethyl methacrylate, 1-methoxy-2-propanol, diacetone alcohol and UV absorber.

7. The multi-layer composite according to claim 1 , wherein the thermoplastic layer comprises one or more selected from the group consisting of polycarbonates, polyester carbonates, polyesters, polyphenylene ethers, graft copolymers thereof, and mixtures thereof.

8. The multi-layer composite according to claim 1 , wherein the thermoplastic layer is injection-molded.

9. A process for producing a multi-layer composite according to claim 1 , the process comprising: (i) positioning the thermoplastic layer such that one edge is lower than a higher edge; (ii) flow coating the thermoplastic layer on an upper side of the higher edge with the first coating to form the first scratch-resistant coating layer; (iii) flow coating the thermoplastic layer on an under-side of the higher edge with the second coating to form the second scratch-resistant coating layer; and (iv) drying the first and second scratch-resistant coating layers.

10. The process according to claim 9 , wherein the flow coating of the upper side of the higher edge and the flow coating of the under-side of the higher edge are carried out substantially at the same time.

11. The process according to claim 9 , wherein the flow coating of the upper side of the higher edge and the flow coating of the under-side of the higher edge are carried out at an interval of from 1 to 30 min.

12. The process according to claim 9 , wherein the flow coating of the upper side of the higher edge and the flow coating of the under-side of the higher edge are carried out at an interval of from 1 to 10 min.

13. The process according to claim 9 , wherein the flow coating of the upper side of the higher edge and the flow coating of the under-side of the higher edge are carried out at an interval of from 2 to 5 min

14. A glazing component comprising a multi-layer composite according to claim 1 .

15. An automotive windshield comprising a multi-layer composite according to claim 1 .

16. A multi-layer composite comprising:

(a) a first scratch-resistant coating layer;

(b) a thermoplastic layer; and

(c) a second scratch-resistant coating layer;

wherein the first scratch-resistant coating layer and the second scratch-resistant coating layer are disposed on opposing sides of the thermoplastic layer;

wherein the first scratch-resistant coating and the second scratch-resistant coating each comprise a primer layer having a thickness, and wherein the first coating and the second coating differ only in the thicknesses of their primer layers;

and wherein the first scratch-resistant coating layer and the second scratch-resistant coating layer are selected such that a multi-layer composite having the first scratch-resistant layer disposed on both sides of the thermoplastic layer has a lower critical impact speed for tough/brittle transition at −30° C. according to DIN EN ISO 6603-1 than a multi-layer composite having the second scratch-resistant layer disposed on both sides of the thermoplastic layer.

17. The multi-layer composite according to claim 16 , wherein the second scratch-resistant coating layer has an impact speed for tough/brittle transition at −30° C. according to DIN EN ISO 6603-1 of greater than 2.5 m/s when the multi-layer composite has a thickness of 5 mm and the second scratch-resistant coating layer is disposed on the side of the thermoplastic layer which is subject to tensile forces during the DIN EN ISO 6603-1 testing.

18. The multi-layer composite according to claim 16 , wherein the first coating comprises: one or more compounds selected from the group consisting of organosilicon compounds of the general formula R′ n Si(OR) 4−n , and partial condensates thereof; an inorganic finely divided compound; an UV absorber; and an alcohol-based solvent.

19. The multi-layer composite according to claim 16 , wherein the second coating comprises; one or more compounds selected from the group consisting organosilicon compounds of the general formula R′ n Si(OR) 4−n , and partial condensates thereof; inorganic nanoparticles; an alcohol-based solvent; an acrylate-based organic adhesion promoter; and, optionally, a UV absorber.

20. The multi-layer composite according to claim 16 , wherein the primer layer or layers comprise polymethyl methacrylate, 1-methoxy-2-propanol, diacetone alcohol and UV absorber.

21. The multi-layer composite according to claim 16 , wherein the thermoplastic layer comprises one or more selected from the group consisting of polycarbonates, polyester carbonates, polyesters, polyphenylene ethers, graft copolymers thereof, and mixtures thereof.

22. The multi-layer composite according to claim 16 , wherein the thermoplastic layer is injection-molded.

23. A glazing component comprising a multi-layer composite according to claim 16 .

24. An automotive windshield comprising a multi-layer composite according to claim 16 .

25. A multi-layer composite comprising:

(a) a first scratch-resistant coating layer;

(b) a thermoplastic layer; and

(c) a second scratch-resistant coating layer;

wherein the first scratch-resistant coating layer and the second scratch-resistant coating layer are disposed on opposing sides of the thermoplastic layer;

wherein the first scratch-resistant coating and the second scratch-resistant coating are not the same;

wherein the first coating comprises: one or more compounds selected from the group consisting of UV curing coating systems based on acrylate, urethane acrylate or acrylosilane; photoinitiator; UV absorber; solvent; and optionally an inorganic finely divided compound;

and wherein the first scratch-resistant coating layer and the second scratch-resistant coating layer axe selected such that a multi-layer composite having the first scratch-resistant layer disposed on both sides of the thermoplastic layer has a lower critical impact speed for tough/brittle transition at −30° C. according to DIN EN ISO 6603-1 than a multi-layer composite having the second scratch-resistant layer disposed on both sides of the thermoplastic layer.

26. The multi-layer composite according to claim 25 , wherein the second coating comprises: one or more compounds selected from the group consisting organosilicon compounds of the general formula R′ n Si(OR) 4−n , and partial condensates thereof; inorganic nanoparticles; an alcohol-based solvent; and an acrylate-based organic adhesion promoter; and, optionally, a UV absorber.

27. A glazing component comprising a multi-layer composite according to claim 25 .

28. An automotive windshield comprising a multi-layer composite according to claim 25 .