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—R 5   (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 group, C4-C10-cycloalkoxy groups or alkyl polyether group —O—(R 6 —O) r —R 7

wherein R 6 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 7 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 group, C7-C20-aralkyl group or halogen,

R 3 are each independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group,

R 4 are each independently a branched or unbranched, saturated or unsaturated, aliphatic, aromatic or mixed aliphatic/aromatic divalent C1-C30 hydrocarbon group,

R 5 is a —C(═O)—R 8 group wherein R 8 is hydrogen, a C1-C20-alkyl group, a C6-C20-aryl groups, a C2-C20-alkenyl group, a C7-C20-aralkyl group,

and n is 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 from 20:80 to 90:10.

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

3. A process for preparing the silane mixture according to claim 2 , comprising:

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)

wherein 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 34:66 to 76:24 to obtain a product;

and

reacting the product with a salt of a thiocarboxylic acid of formula (V)

NaS—C(═O)—R 5   (V)

or,

reacting the product with NaSH and then an acid chloride of formula (VI)

Cl—C(═O)—R 5   (VI).

4. The process for preparing the silane mixture according to claim 3 , wherein the mercaptosilane of formula III is

(EtO) 3 Si—(CH 2 ) 3 —SH,

the halogen compound of formula IV is

Cl—(CH 2 ) 6 —Cl,

and the thiocarboxylic acid of formula V is

NaS—C(═O)—CH 3 , NaS—C(═O)—C 7 H 15 or NaS—C(═O)—C 17 H 35 .

5. The process for preparing the silane mixture according to claim 3 , wherein the mercaptosilane of formula III is

(EtO) 3 Si—(CH 2 ) 3 —SH

the halogen compound of formula IV is

Cl—(CH 2 ) 6 —Cl,

and the acid chloride of formula VI is

Cl—C(═O)—CH 3 , Cl—C(═O)—C 7 H 15 or Cl—C(═O)—C 17 H 35 .

6. The silane mixture according to claim 1 , wherein the silane of formula I is (EtO) 3 Si—(CH 2 ) 3 —(S—(CH 2 ) 6 ) n —S—C(═O)—R 8 and the silane of formula II is (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—(CH 2 ) 3 —Si(OEt) 3 , where n is 1.

7. The silane mixture according to claim 1 , wherein the silane of formula I is (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—C(═O)—CH 3 , (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—C(═O)—C 7 H 15 or (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—C(═O)—C 17 H 35 and the silane of formula II is (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—(CH 2 ) 3 —Si(OEt) 3 .

8. The silane mixture according to claim 1 , wherein the molar ratio of the silane of formula I to the silane of formula II is from 30:70 to 75:25.

9. 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 —S—R 5   (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 1 ) y (R 2 ) 3-y   (II)

in a molar ratio of 20:80-90:10.

10. The process for preparing the silane mixture according to claim 9 , wherein n is 1 and z is 1.

11. The process for preparing the silane mixture according to claim 10 , wherein the silane of formula I is

(EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—C(═O)—CH 3 , (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—C(═O)—C 7 H 15 or (EtO) 3 Si—(CH 2 ) 3 —S—(CH 2 ) 6 —S—C(═O)—C 17 H 35 and the silane of formula II is

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

12. The process for preparing the silane mixture according to claim 9 , wherein the molar ratio of the silane of formula I to the silane of formula II is from 30:70 to 75:25.