Method For Producing An Aqueous Composition Comprising A Condensate Based On Silicon Compounds For Producing Antireflective Coatings

Abstract

A method for producing an aqueous composition comprising a condensate based on silicon compounds, involving the steps of i) introducing at least one polymeric rheology control agent into water; ii) adding at least one acidic catalyst; iii) adding at least one silicon compound of general formula (I) RnSiX4-n in which the radicals X are the same or different and stand for hydrolysable groups or hydroxyl groups, the radicals R are the same or different and stand for non-hydrolysable groups, and n is 0, 1, 2, or 3; and iv) performing a hydrolysis reaction of at least part of the silicon compounds of general formula (I) added in step iii). The present invention further relates to a composition that can be obtained by means of the method according to the invention.

Claims

1-10 (canceled)

11. A method for producing an aqueous composition comprising a condensate based on silicon compounds, comprising the following steps: i) introducing at least one polymeric rheology control agent into water; ii) adding at least one acidic catalyst; iii) adding at least one silicon compound of formula (I):
R.sub.nSiX.sub.4-n(I), in which the residues X are the same or different and stand for hydrolyzable groups or hydroxyl groups, the residues R are the same or different and stand for non-hydrolyzable groups, and n is 0, 1, 2 or 3; and iv) performing a hydrolysis reaction of at least a portion of the silicon compounds of formula (I) added in step iii).

12. The method according to claim 11, characterized in that steps i), ii), iii) and iv) are carried out in the sequence i), i), iii) and iv).

13. The method according to claim 11, characterized in that the rheology control agent has a molecular weight M.sub.w, within the range of 1000 to 2000000 g/mol.

14. The method according to claim 11, characterized in that 0.1 wt % to 40 wt % rheology control agent based on the weight of the mixture obtained in step i) is used to produce the composition in step i).

15. The method according to claim 11, characterized in that the rheology control agent is a polyacrylamide, a cellulose or a cellulose derivative.

16. The method according to claim 11, characterized in that at least one silicon compound of the formula SiX.sub.4 is used, in which the residues X are the same or different and stand for hydrolyzable groups or hydroxyl groups.

17. The method according to claim 11, characterized in that the proportion of the silicon compound according to the formula SiX.sub.4 is within the range of 80 wt % to 100 wt %, based on the total quantity of silicon compounds of formula (I).

18. The method according to claim 11, characterized in that the proportion of organic compounds having a molecular weight of no more than 400 g/mol is no more than 10 wt % based on the total weight of the composition.

19. The method according to claim 11, characterized in that after step iv) has been performed, a surface active substance is added to the composition.

20. The method according to claim 11, characterized in that the at least one silicon compound of formula (I) is selected from the group consisting of SiCl.sub.4, HSiCl.sub.3, Si(OCH.sub.3).sub.4, Si(OOCCH.sub.3).sub.4, Si(OC.sub.2H.sub.5).sub.4 and Si(OC.sub.3H.sub.7).sub.4, tetraalkoxysilanes, Si(OCH.sub.3).sub.4Si(OCH.sub.2CH.sub.3).sub.4, Si(OC.sub.3H.sub.7).sub.4, and combinations thereof.

21. The method according to claim 12, characterized in that the at least one silicon compound of formula (I) is selected from the group consisting of SiCl.sub.4, HSiCl.sub.3, Si(OCH.sub.3).sub.4, Si(OOCCH.sub.3).sub.4, Si(OC.sub.2H.sub.5).sub.4 and Si(OC.sub.3H.sub.7).sub.4, tetraalkoxysilanes, Si(OCH.sub.3).sub.4Si(OCH.sub.2CH.sub.3).sub.4, Si(OC.sub.3H.sub.7).sub.4, and combinations thereof.

22. The method according to claim 11, characterized in that no more than 80 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of Cl.sub.3SiCH.sub.3, Si(CH.sub.3)(OC.sub.2H.sub.5).sub.3, Cl.sub.3Si(C.sub.2H.sub.5), Si(C.sub.2H.sub.5)(OC.sub.2H.sub.5).sub.3, Si(OC.sub.2H.sub.5).sub.3(CH.sub.2-CH=CH.sub.2), Si(OOCCH.sub.3).sub.3(CH.sub.2-CH=CH.sub.2), Cl.sub.3Si(CH=CH.sub.2), Si(CH=CH.sub.2)(OC.sub.2H.sub.5).sub.3, Si(CH=CH.sub.2)(OC.sub.2H.sub.4OCH.sub.3).sub.3 and Si(CH=CH.sub.2)(OOCCH.sub.3).sub.3 and combinations thereof.

23. The method according to claim 22, characterized in that no more than 80 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of Cl.sub.3SiCH.sub.3, Si(CH.sub.3)(OC.sub.2H.sub.5).sub.3, Cl.sub.3Si(C.sub.2H.sub.5), Si(C.sub.2H.sub.5)(OC.sub.2H.sub.5).sub.3, Si(OC.sub.2H.sub.5).sub.3(CH.sub.2-CH=CH.sub.2), Si(OOCCH.sub.3).sub.3(CH.sub.2-CH=CH.sub.2), Cl.sub.3Si(CH=CH.sub.2), Si(CH=CH.sub.2)(OC.sub.2H.sub.5).sub.3, Si(CH=CH.sub.2)(OC.sub.2H.sub.4OCH.sub.3).sub.3 and Si(CH=CH.sub.2)(OOCCH.sub.3).sub.3 and combinations thereof.

24. The method according to claim 11, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of Cl.sub.2Si(CH.sub.3).sub.2, Si(CH.sub.3).sub.2(OC.sub.2H.sub.5).sub.2, Si(C.sub.2H.sub.5).sub.2(OC.sub.2H.sub.5).sub.2, Cl.sub.2Si(CH=CH.sub.2)(CH.sub.3), Si(CH.sub.3).sub.2(OCH.sub.3).sub.2, Cl.sub.2Si(C.sub.6H.sub.5).sub.2, and Si(C.sub.6H.sub.5).sub.2(OC.sub.2H.sub.5).sub.2 and combinations thereof.

25. The method according to claim 23, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of (C.sub.6H.sub.5).sub.3SiOH, Si(CH.sub.3).sub.3(OC.sub.2H.sub.5) and Si(CH.sub.2CH.sub.3).sub.3(OC.sub.2H.sub.5) and combinations thereof.

26. A substrate coated with a composition comprising the hydrolysis product of i) at least one polymeric rheology control agent and ii) least one silicon compound of formula (I):
R.sub.nSiX.sub.4-n(I), in which the residues X are the same or different and stand for hydrolyzable groups or hydroxyl groups, the residues R are the same or different and stand for non-hydrolyzable groups, and n is 0, 1, 2 or 3.

27. The substrate of claim 26 wherein at least one silicon compound of the formula SiX.sub.4 is used, in which the residues X are the same or different and stand for hydrolyzable groups or hydroxyl groups.

28. The substrate of claim 26, characterized in that no more than 80 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of Cl.sub.3SiCH.sub.3, Si(CH.sub.3)(OC.sub.2H.sub.5).sub.3, Cl.sub.3Si(C.sub.2H.sub.5), Si(C.sub.2H.sub.5)(OC.sub.2H.sub.5).sub.3, Si(OC.sub.2H.sub.5).sub.3(CH.sub.2-CH=CH.sub.2), Si(OOCCH.sub.3).sub.3(CH.sub.2-CH=CH.sub.2), Cl.sub.3Si(CH=CH.sub.2), Si(CH=CH.sub.2)(OC.sub.2H.sub.5).sub.3, Si(CH=CH.sub.2)(OC.sub.2H.sub.4OCH.sub.3).sub.3 and Si(CH=CH.sub.2)(OOCCH.sub.3).sub.3 and combinations thereof.

29. The substrate of claim 26, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of Cl.sub.2Si(CH.sub.3).sub.2, Si(CH.sub.3).sub.2(OC.sub.2H.sub.5).sub.2, Si(C.sub.2H.sub.5).sub.2(OC.sub.2H.sub.5)2, Cl.sub.2Si(CH=CH.sub.2)(CH.sub.3), Si(CH.sub.3).sub.2(OCH.sub.3).sub.2, Cl.sub.2Si(C.sub.6H.sub.5).sub.2, and Si(C.sub.6H.sub.5).sub.2(OC.sub.2H.sub.5).sub.2 and combinations thereof.

30. The substrate of claim 28, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of Cl.sub.2Si(CH.sub.3).sub.2, Si(CH.sub.3).sub.2(OC.sub.2H.sub.5).sub.2, Si(C.sub.2H.sub.5).sub.2(OC.sub.2H.sub.5)2, Cl.sub.2Si(CH=CH.sub.2)(CH.sub.3), Si(CH.sub.3).sub.2(OCH.sub.3).sub.2, Cl.sub.2Si(C.sub.6H.sub.5).sub.2, and Si(C.sub.6H.sub.5).sub.2(OC.sub.2H.sub.5).sub.2 and combinations thereof.

31. The method according to claim 26, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of (C.sub.6H.sub.5).sub.3SiOH, Si(CH.sub.3).sub.3(OC.sub.2H.sub.5) and Si(CH.sub.2CH.sub.3).sub.3(OC.sub.2H.sub.5) and combinations thereof.

32. The method according to claim 30, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of (C.sub.6H.sub.5).sub.3SiOH, Si(CH.sub.3).sub.3(OC.sub.2H.sub.5) and Si(CH.sub.2CH.sub.3).sub.3(OC.sub.2H.sub.5) and combinations thereof.

33. The method according to claim 31, characterized in that no more than 20 wt % of the at least one silicon compound of formula (I) is substituted by at least one selected from the group consisting of (C.sub.6H.sub.5).sub.3SiOH, Si(CH.sub.3).sub.3(OC.sub.2H.sub.5) and Si(CH.sub.2CH.sub.3).sub.3(OC.sub.2H.sub.5) and combinations thereof.

34. A composition obtained by the method according claim 11.

Description

[0074] In the following, the present invention will be specified in greater detail with the aid of examples, without a limitation of the invention being intended as a result.

Example 1

[0075] Production of a coating composition comprising a polycondensate from tetraethoxysilane (TEOS).

[0076] 1.25 g hydroxypropyl cellulose (Nisso M, available from Nisso Chemical Europe GmbH, viscosity of an aqueous solution with 2 wt/% Nisso M is approximately 150 to 400 mPa*s, measured at 20 C., molecular weight is approximately 620000 g/mol) was added to 46.766 g water and stirred for 30 minutes at 30 C. to obtain a clear solution, to which 0.25 g HNO.sub.3 was added in a second step, 1.734 g tetraethoxysilane was stirred into the resulting mixture, and after 18 hours at 30 C. a clear composition was obtained, which was applied to a glass substrate. The coating composition had a viscosity of 1.5 Pa*s at a shear rate of 0.2s-1. Following application, the coating was dried for 10 minutes at 120 C. and baked for 5 minutes at 600 C. The result was an antireflective coating giving a dark blue reflection with slight spotting.

Example 2

[0077] Example 1 was essentially repeated, however 0.1 wt/% of a surface active substance (polyether modified siloxane Byk 348, available from Byk Chemicals Japan) was added after the hydrolysis step.

[0078] An antireflective coating giving a dark blue reflection was obtained, which had fewer optical defects than the layer of Example 1.

Example 3

[0079] Example 1 was essentially repeated, however 0.1 wt/% of a surface active substance (Byk 348, available from Byk Chemicals Japan) was added prior to the hydrolysis step.

[0080] An antireflective coating giving a dark blue reflection was obtained, which had considerably more optical defects than the layer of Example 1, with clearly visible spots developing.

Comparative Example 1

[0081] Three drops TEOS were added to 10 ml water, wherein the silicon compound could not be dispersed in the water by stirring. The addition of 2 drops HNO3 led to the formation of opaque white floccules, with no development of a useful composition being observed.

Example 4

[0082] 2.2 g hydroxypropyl cellulose (Klucel L, available from Hercules, molecular weight approximately 95000 g/mol) was added to 95.5 g water that contained 0.263 g 50% H.sub.2SO.sub.4, and this was stirred for 60 minutes at 30 C. to obtain a clear solution. 1.363 g tetraethoxysilane was stirred into the resulting mixture which was hydrolyzed for 60 minutes. 0.661 g Koestrosol 3550 was stirred into the resulting mixture. The resulting composition was applied to sheet glass by screen printing (mesh 100T), producing a smooth layer. Following application, the coating was baked at 690 C. The result was an antireflective layer giving a blue to violet reflection.