Curable silicon-containing compositions possessing high translucency

1. A moisture curable silicon-containing resin composition which is curable to form a translucent cured composition said moisture curable composition comprising:

a) at least one silicon-containing resin selected from the group consisting of a diorganopolysiloxane wherein the silicon atom at each polymer chain end of said diorganopolysiloxane is silanol terminated and a silylated resin;

b) at least one hydrophobic functionalized sol gel silica obtained by the process comprising:

i) mixing an aqueous alcoholic solution and a functionalized silica-preparing catalyst with a first portion of a first organosilicon functionalizing agent to form a first reaction mixture;

ii) reacting said first reaction mixture with a tetraalkoxysilane at a controlled rate to form a second reaction mixture comprising a sol gel silica, wherein the relative mole ratio of tetralkoxysilane to the first portion of first organosilicon functionalizing agent is from about 1:0.2 to about 1:0.6; and

iii) further reacting said second reaction mixture with a mixture of a second portion of said first organosilicon functionalizing agent, wherein the relative mole ratio of the first portion of the first organosilicon functionalizing agent to the second portion of the first organosilicon functionalizing agent is from about 1:0.5 to about 1:1, and a second organosilicon functionalizing agent to functionalize the sol gel silica to form said functionalized sol gel silica,

wherein the functionalized silica results in a lower viscosity of the combined silicon-containing resin and functionalized sol gel silica than the viscosity of a silicon-containing resin which is combined with a treated fumed silica;

c) at least one condensation and/or crosslinking-facilitating catalyst;

d) at least one crosslinker; and, optionally,

e) at least one additional component selected from the group consisting of alkyl-terminated diorganopolysiloxane, filler, UV stabilizer, antioxidant, adhesion promoter, cure accelerator, thixotropic agent, plasticizer, polymer endcapping catalyst, moisture scavenger, pigment, dye, surfactant, solvent and biocide.

2. The silicon-containing resin composition of claim 1 wherein the silylated resin is a silylated polyether.

3. The silicon-containing resin composition of claim 1 wherein the silylated resin is a silylated polyether diol.

4. The silicon-containing resin composition of claim 1 wherein the silylated resin is a silylated polyurethane.

5. The silicon-containing resin composition of claim 1 wherein the silylated resin is a silylated polyurethane obtained from a polyether diol and a diisocyanate.

6. The silicon-containing resin composition of claim 1 wherein the silylated resin is a silylated polyurethane obtained from the reaction of hydroxyl-terminated polyether polyol and isocyanatosilane.

7. The silicon-containing resin composition of claim 1 wherein the silylated resin is a silylated polyurethane obtained from the reaction of an isocyanato-terminated polyether polyol and aminosilane.

8. The silicon-containing resin composition of claim 1 wherein the diorganopolysiloxane has the general formula:

M a D b D′ c

wherein subscript a=2 and b is equal to or greater than 1 and subscript c is zero or positive;

M=(HO) 3-x-y R 7 x R 8 y SiO 1/2 ;

wherein x equals 0, 1 or 2, y is either 0 or 1, with the proviso that x+y is less than or equal to 2, R 7 and R 8 are independent monovalent hydrocarbon radicals containing from 1 to about 60 carbon atoms;

D=R 9 R 10 SiO 1/2 ;

R 9 and R 10 are independent monovalent hydrocarbon radicals containing from 1 to about 60 carbon atoms; and,

D′=R 11 R 12 SiO 2/2 ;

R 11 and R 12 are independent monovalent hydrocarbon radicals containing from 1 to about 60 carbon atoms.

9. The silicon-containing composition of claim 1 wherein the condensation and/or crosslinking-facilitating catalyst is at least one selected from the group consisting of metal condensation catalysts and non-metal condensation catalysts.

10. The silicon-containing composition of claim 9 wherein the metal condensation catalyst is at least one selected from the group consisting of tin, titanium, zirconium, lead, iron, cobalt, antimony, manganese, bismuth and zinc compounds.

11. The silicon-containing resin composition of claim 1 wherein the process of obtaining functionalized silica further comprises after step (iii) adding a solvent, thereby forming a suspension comprising said functionalized silica.

12. The silicon-containing resin composition of claim 1 wherein said first organosilicon functionalizing agent comprises an organosilazane, and said functionalized silica-preparing catalyst comprises a base catalyst or a neutral catalyst.

13. The silicon-containing resin composition of claim 12 wherein said organosilazane comprises a hexaalkyldisilazane.

14. The silicon-containing resin composition of claim 12 wherein said functionalized silica-preparing catalyst comprises a base catalyst.

15. The silicon-containing resin composition of claim 13 wherein said hexaalkyldisilazane comprises hexamethyldisilazane.

16. The silicon-containing resin composition of claim 1 wherein said first organosilicon functionalizing agent comprises a halosilane, and said functionalized silica-preparing catalyst is an acid catalyst or a neutral catalyst.

17. The silicon-containing resin composition of claim 1 wherein said second organosilicon functionalizing agent comprises at least one alkenyl group.

18. The silicon-containing resin composition of claim 17 wherein said second organosilicon functionalizing agent comprises a (dialkenyl)disilazane.

19. The silicon-containing resin composition of claim 18 wherein said (dialkenyl)disilazane comprises a dialkenyl(tetraalkyl)disilazane.

20. The silicon-containing resin composition of claim 19 wherein said dialkenyl(tetraalkyl)disilazane comprises divinyl(tetramethyl)disilazane.

21. The silicon-containing resin composition of claim 1 wherein said second organosilicon functionalizing agent comprises a (alkenyl)halosilane, and said functionalized silica-preparing catalyst is an acid catalyst or a neutral catalyst.

22. The silicon-containing resin composition of claim 1 wherein the diorganopolysiloxane is present in an amount ranges from about 5 weight percent to about 95 weight percent of the total composition.

23. The silicon-containing resin composition of claim 1 wherein the diorganopolysiloxane is present in an amount that ranges from about 35 weight percent to about 85 weight percent of the total composition.

24. The silicon-containing resin composition of claim 1 wherein the diorganopolysiloxane is present in an amount that ranges from about 50 weight percent to about 70 weight percent of the total composition.

25. The silicon-containing resin composition of claim 1 wherein the silylated resin is present in an amount that ranges from about 5 weight percent to about 95 weight percent of the total composition.

26. The silicon-containing resin composition of claim 1 wherein the silylated resin is present in an amount that ranges from about 35 weight percent to about 85 weight percent of the total composition.

27. The silicon-containing resin composition of claim 1 wherein the functionalized silica is present in an amount that ranges from about 5 to about 80 parts by weight per 100 parts by weight of the total silicon-containing resin composition.

28. The silicon-containing resin composition of claim 1 wherein the functionalized silica is present in an amount that ranges from about 10 to about 30 parts by weight per 100 parts by weight of the total silicon-containing resin composition.

29. The cured composition of claim 1 .

30. The cured composition of claim 29 wherein the transmittance of a sheet of the cured composition made as per ASTM test D412 is greater than 40 percent.

31. The cured composition of claim 29 wherein the transmittance of a sheet of the cured composition made as per ASTM test D412 is greater than 60 percent.

32. A sealant comprising the silicon-containing resin composition of claim 1 .

33. An adhesive comprising the silicon-containing resin composition of claim 1 .

34. A cured composition resulting from the curing of the moisture curable silicon-containing resin composition of claim 1 , which moisture curable silicon-containing resin composition is made by the process comprising combining the functionalized sol gel silica with at least one silicon-containing resin selected from the group consisting of a diorganopolysiloxane wherein the silicon atom at each polymer chain end of said diorganopolysiloxane is silanol terminated, and a silylated resin.

35. A sealant comprising the cured composition of claim 33 , wherein a sheet of said sealant has a primerless adhesive lap shear strength of at least about 77 psi and a cohesive failure of 100% as measured by WPSTM Test C-1221 on vinyl-glass test panels.

36. An adhesive comprising the cured composition of claim 33 .

37. The silicon-containing resin composition of claim 1 wherein the functionalized sol gel silica has a mean particle size of from about 80 nm to about 120 nm and a BET surface area of from about 100 m 2 /g to about 1,000 m 2 /g.