Silane mixtures and processes for preparation thereof

1. A silane mixture comprising a silane of formula I

(R 1 ) y (R 2 ) 3-y Si—R 3 —(S—R 4 ) n —S x —(R 4 —S) n —R 3 —Si(R 1 ) y (R 2 ) 3-y   (I)

and a silane of formula II

(R 1 ) y (R 2 ) 3-y Si—R 3 —(S—R 4 ) z —S—R 3 —Si(R 1 ) y (R 2 ) 3-y   (II)

wherein R 1 are each independently C1-C10-alkoxy groups, phenoxy groups, C4-C10-cycloalkoxy groups or alkyl polyether groups —O—(R 5 —O) r —R 6 where R 5 are each independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group, r is an integer from 1 to 30, and R 6 is an unsubstituted or substituted, branched or unbranched monovalent alkyl, alkenyl, aryl or aralkyl group,

R 2 are each independently C6-C20-aryl groups, C1-C10 alkyl groups, C2-C20 alkenyl groups, C7-C20-aralkyl groups or halogen,

R 3 are each independently branched or unbranched, saturated or unsaturated, aliphatic, aromatic or

mixed aliphatic/aromatic divalent C1-C30 hydrocarbon groups,

R 4 are each independently branched or unbranched, saturated or unsaturated, aliphatic, aromatic or

mixed aliphatic/aromatic divalent C1-C30 hydrocarbon groups, and x is a number from 2 to 10,

n are the same and are 0, 1, 2 or 3, y are each independently 1, 2 or 3, z is 1, 2 or 3, and the molar ratio of silane of the formula I to silane of the formula II is 19:81-81:19.

2. The silane mixture according to claim 1 , wherein n is 0 or 1 and z=1.

3. The silane mixture according to claim 1 , wherein n=1 and z=1.

4. The silane mixture according to claim 1 , wherein x=2.

5. The silane mixture according to claim 3 , wherein the silane of formula I is (EtO) 3 Si—(CH2) 3 —S—(CH 2 ) 6 —S 2 —(CH2) 6 —S—(CH 2 ) 3 —Si(OEt) and the silane of formula is (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 )—S—(CH 2 ) 3 —Si(OEt) 3 .

6. The silane mixture according to claim 2 , wherein the silane of formula I is

(EtO) 3 Si—(CH 2 ) 3 —S 2 —(CH2) 3 —Si(OEt) 3

and the silane of formula II is

(EtO) 3 Si—(CH 2 ) 3 —S—(CH2) 6 —S—(CH 2 ) 3 —Si(OEt) 3 .

7. The silane mixture according to claim 1 , wherein the silane of the molar ratio of silane of formula I to the silane of formula II is 20:80-65:35.

8. A process for preparing the silane mixture according to claim 1 , comprising:

mixing the silane of formula I

(R 1 ) y (R 2 ) 3-y Si—R 3 —(S—R 4 ) n —Sc(R 4 —S)—R 3 —Si(R 1 ) y (R 2 ) 3-y   (I)

with the silane of formula II

(R 1 ) y (R 2 ) 3-y Si—R 3 —(S—R 4 ) z —S—R 3 —Si(R) y (R 2 ) 3-y   (II)

in a molar ratio of 81:19-19:81.

9. The process for preparing the silane mixture according to claim 8 , wherein n is 0 or 1 and z=1.

10. The process for preparing the silane mixture according to claim 8 , wherein n=1 and z=1.

11. The process for preparing the silane mixture according to claim 8 , wherein the molar ratio of the silane of formula I to the silane of formula II is 50:50-70:30.

12. The process for preparing the silane mixture according to claim 9 , that wherein the silane of formula I is

(EtO) 3 Si—(CH2) 3 —S—(CH 2 )6-S 2 —(CH2) 6 —S—(CH 2 ) 3 —Si(OEt) 3 or (EtO) 3 Si—(CH 2 ) 3 —S 2 —(CH2) 3 —Si(OEt) 3

and the silane of formula II is

(EtO) 3 Si—(CH 2 ) 3 —S—(CH2) 6 —S—(CH 2 ) 3 —Si(OEt) 3 .

13. The process for preparing the silane mixture according to claim 3 , reacting a mercaptosilane of formula III

(R 1 ) y (R 2 ) 3-y Si—R 3 —SH  (III)

with a halogen compound of formula IV

Hal-R 4 -Hal  (IV)

Hal is F, CL Br or I in a molar ratio of the mercaptosilane of formula (III) to the halogen compound of formula (IV) of from 34:86-64:36 to obtain a product;

and reacting the product with sodium polysulfide of the formula (V)

Na 2 S x   (V)

where x is as defined above.

14. The process for preparing the silane mixture according to claim 13 , wherein the mercaptosilane of formula III is

(EtO) 3 Si—(CH 2 ) 3 —SH

the halogen compound of formula IV is C—(CH 2 ) 6 —Cl

and the sodium polysulfide of formula V is Na 2 S 2 .