Rubber mixtures with functionalized diene rubbers and with microgels, a production process, and use of the mixtures

1. A rubber mixture, comprising:

(A) at least one functionalized diene rubber having a polymer chain comprising repeat units based on 1,3-butadiene and styrene and functionalized using hydroxyl groups, carboxy groups, and/or salts thereof, wherein the 1,3-butadiene is present in an amount of from 40 to 100% by weight, the styrene is present in an amount of from 1 to 60%, and the proportion of bonded functional groups and/or salts thereof are from 0.02 to 5% by weight, all aforementioned weight based on the diene rubber, and

(B) at least one XSBR-styrene/butadiene rubber gel comprising hydroxy groups in an amount of from 20 to 50 mg KOH/g and having a swelling index in toluene of from 1 to 25 and having a particle size of from 5 to 1000 nm; and

(C) optionally, further rubbers, fillers and rubber auxiliaries.

2. The rubber mixture according to claim 1 , wherein the proportion of the XSBR-styrene/butadiene rubber gel is from 5 to 75 parts by weight based on 100 parts by weight of the total amount of rubber of components (A), (B) and (C).

3. The rubber mixture according to claim 2 , wherein the styrene/butadiene rubber gel is an XSBR-styrene/butadiene copolymer and graft polymer, comprising hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and/or pentaerythritol tetramethacrylate.

4. A process for the production of the rubber mixture according to claim 1 , comprising:

mixing the at least one functionalized diene rubber with the at least one XSBR-styrene/butadiene rubber gel in a mixing apparatus at temperatures of from 20 to 220° C.

5. The process according to claim 4 , further comprising:

mixing the at least one functionalized diene rubber with the one or more further rubbers, fillers, and rubber auxiliaries.