Improving the rolling resistance of diene rubber tires by means of silane-modified polybutadienes

1. A rubber comprising silane-modified polybutadiene, wherein the polybutadiene comprises the 1,3-butadiene-derived monomer units

and wherein the proportion of A in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 10 to 60 mol %, and wherein the sum of the proportions of B and C in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 40 to 90 mol % wherein the silane-modified polybutadienes are obtainable by reacting hydroxyl-terminated polybutadienes produced by free-radical polymerization with one or more organosilane compounds, wherein the silane-modified polybutadiene has an average functionality of from 0.1 to 4.

2. The rubber according to claim 1 , wherein the proportion of A) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 15 to 30 mol %, the proportion of B) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 50 to 70 mol % and the proportion of C) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 15 to 30 mol, wherein the silane-modified polybutadiene has an average functionality of from 0.7 to 2.6.

3. The rubber according to claim 1 , wherein the organosilane compound is selected from the group comprising compounds of formula I

OCN—R—Si(OR 1 ) x (R 2 ) 3-x   I

where R represents linear or branched alkylene chains having 1-4 carbon atoms and R 1 and R 2 simultaneously or independently of one another represent linear or branched alkyl chains having from 1 to 5 carbon atoms x=1, 2 or 3, wherein the silane-modified polybutadiene has an average functionality of from 1.2 to 2.5.

4. A rubber mixture comprising silane-modified polybutadienes, wherein the polybutadiene comprises the 1,3-butadiene-derived monomer units

and wherein the proportion of A in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 10 to 60 mol %, and wherein the sum of the proportions of B and C in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 40 to 90 mol % wherein the silane-modified polybutadienes are obtainable by reacting hydroxyl-terminated polybutadienes produced by free-radical polymerization with one or more organosilane compounds, wherein the silane-modified polybutadiene has an average functionality of from 0.1 to 4.

5. The rubber mixture according to claim 4 , wherein the silane-modified polybutadiene is employed in an amount of from 0.5 to 25 parts by wt based on 100 parts by wt of rubber, wherein the silane-modified polybutadiene has an average functionality of from 0.7 to 2.6.

6. The rubber mixture according to claim 4 , wherein said mixture comprise 10 to 150 parts by wt of precipitated silica, 0 to 100 parts by wt of carbon black and 0.5 to 15 parts by wt of silane-modified polybutadiene according to claim 1 , in each case based on 100 parts by weight of rubber %, wherein the silane-modified polybutadiene has an average functionality of from 1.2 to 2.5.

7. The rubber mixture according to claim 4 , wherein said mixture comprise an organosilane and wherein the silane-modified polybutadiene has a viscosity of from 8.2 to 27.8 Pa*sec at 20° C.

8. The rubber mixture according to claim 7 , wherein said mixture comprise 0.5 to 20 parts by wt of organosilane based on 100 parts by wt of rubber.

9. The rubber mixture according to claim 7 , wherein said mixture comprise natural rubber or mixtures of natural rubber and diene rubber, 10 to 150 parts by wt of precipitated silica, 0 to 100 parts by wt of carbon black, 0.5 to 20 parts by wt of organosilane and 0.5 to 25 parts by wt of the silane-modified polybutadiene, in each case based on 100 parts by weight of rubber.

10. A product comprising the rubber mixture according to claim 4 wherein the product is selected from the group consisting of tires, profiles, cable sheaths, hoses, drive belts, conveyor belts, tire treads, shoe soles, sealing rings and damping elements.

11. A process of making a silane-modified polybutadiene, the process comprising the steps of

a) providing a polybutadiene produced by free-radical polymerization and having hydroxyl groups, and

b) reacting the polybutadiene having hydroxyl groups from step a) with an organosilane compound, wherein the polybutadiene comprises the 1,3-butadiene-derived monomer units

 and wherein the proportion of A in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 10 to 60 mol %, and wherein the sum of the proportions of B and C in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 40 to 90 mol % wherein the silane-modified polybutadienes are obtainable by reacting hydroxyl-terminated polybutadienes produced by free-radical polymerization with one or more organosilane compounds, wherein the silane-modified polybutadiene has an average functionality of from 0.1 to 4.

12. The process of claim 11 wherein the silane-modified polybutadienes are obtainable by reacting hydroxyl-terminated polybutadienes produced by free-radical polymerization with one or more organosilane compounds and wherein the silane-modified polybutadiene has a viscosity of from 8.2 to 27.8 Pa*sec at 20° C.

13. The process of claim 11 wherein the proportion of A) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 15 to 30 mol %, the proportion of B) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 50 to 70 mol % and the proportion of C) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 15 to 30 mol %.

14. The process of claim 11 wherein the organosilane compound is selected from the group comprising compounds of formula I

OCN—R—Si(OR 1 ) x (R 2 ) 3-x   I

where R represents linear or branched alkylene chains having 1-4 carbon atoms and R 1 and R 2 simultaneously or independently of one another represent linear or branched alkyl chains having from 1 to 5 carbon atoms x=1, 2 or 3.

15. The rubber according to claim 3 , wherein the proportion of A) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 15 to 30 mol %, the proportion of B) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 50 to 70 mol % and the proportion of C) in the entirety of the 1,3-butadiene-derived monomer units present in the polybutadiene is from 15 to 30 mol %.

16. The rubber according to claim 2 , wherein the organosilane compound is selected from the group comprising compounds of formula I

OCN—R—Si(OR 1 ) x (R 2 ) 3-x   I

where R represents linear or branched alkylene chains having 1-4 carbon atoms and R 1 and R 2 simultaneously or independently of one another represent linear or branched alkyl chains having from 1 to 5 carbon atoms x=1, 2 or 3.

17. The rubber mixture according to claim 5 , wherein said mixtures comprise an organosilane and wherein the silane-modified polybutadiene has a viscosity of from 8.2 to 27.8 Pa*sec at 20° C.

18. The rubber mixture according to claim 17 , wherein said mixtures comprise 0.5 to 20 parts by wt of organosilane based on 100 parts by wt of rubber and wherein the silane-modified polybutadiene has a viscosity of from 8.2 to 27.8 Pa*sec at 20° C.

19. The rubber mixture according to claim 17 , wherein said mixtures comprise natural rubber or mixtures of natural rubber and diene rubber, 10 to 150 parts by wt of precipitated silica, 0 to 100 parts by wt of carbon black, 0.5 to 20 parts by wt of organosilane and 0.5 to 25 parts by wt of the silane-modified polybutadiene, in each case based on 100 parts by weight of rubber.

20. The rubber according to claim 1 , wherein the silane-modified polybutadiene has a viscosity of from 8.2 to 27.8 Pa*sec at 20° C.