Silica gel-containing rubber compounds with organosilicon compounds as compounding agent

A process for the production of a network comprising esters of one or more unsaturated aromatic or aliphatic hydroxycarboxylic acids and one or more aromatic or aliphatic polyols, crosslinked with sulfur bridges comprising the following steps in the order of

• a) reacting an ester with 0.5 to 25 wt. % sulfur in the presence of one or more primary amines at 120 to 180° C. to form a mixture,
• b) reacting the mixture with 0.1 to 1.0 mol of a diisocyanate relative to the OH content of the sulfurized ester to form a further mixture, and
• c) reacting the further mixture with a silane according to formula (IIa),
• R1R2R3Si-X-Q (IIa)
• wherein
• X stands for linear, branched or cyclic, optionally unsaturated C1-C2 alkylene radicals and
• Q stands for SH, NH2, N═C═O or N═C═S.

Rubber compounds comprising

• a) at least one network comprising esters of one or more unsaturated aromatic or aliphatic hydroxycarboxylic acids and one or more aromatic or aliphatic polyols, crosslinked with sulfur bridges, wherein said network comprises a sulfur content in the range from 0.2 wt. % to 17%, and wherein
• i) the hydroxycarboxylic acid(s) each comprise 1, 2 or 3 olefinic double bonds and hydroxyl groups or hydroxyl and isocyanate groups,
• ii) the polyol component(s) each comprise 1 to 6 carbon atoms and 1 to 6 hydroxyl groups and optionally isocyanate groups,
• iii) the network comprises (thio)urethane or urea substituents, which in turn have one or more terminal silane substituents according to formula (I)
• R1R2R3Si-X-(thio)urethane/urea group (I)
• wherein in formula (I)
• R1, R2, R3 are the same or different and denote C1-C18 alkyl or C1-C18 alkoxy and
• X represents linear, branched or cyclic, optionally unsaturated C1-C12 alkylene radicals.
• b) at least one double bond-containing rubber and
• c) at least one silicon-containing filler,
• and optionally additional rubber additives and other fillers.

A compounding process for rubber compounds comprising the step of compounding rubber compounds in a mixing device at temperatures above 155° C., wherein the rubber compound comprises:

• a) at least one network comprising esters of one or more unsaturated aromatic or aliphatic hydroxycarboxylic acids and one or more aromatic or aliphatic polyols, crosslinked with sulfur bridges, wherein said network comprises a sulfur content in the range from 0.2 wt. % to 17%, and wherein
• i) the hydroxycarboxylic acid(s) each comprise 1, 2 or 3 olefinic double bonds and hydroxyl groups or hydroxyl and isocyanate groups,
• ii) the polyol component(s) each comprise 1 to 6 carbon atoms and 1 to 6 hydroxyl groups and optionally isocyanate groups,
• iii) the network comprises (thio)urethane or urea substituents, which in turn have one or more terminal silane substituents according to formula (I)
• R1R2R3Si-X-(thio)urethane/urea group (I)
• wherein in formula (I)
• R1, R2, R3 are the same or different and denote C1-C18 alkyl or C1-C18 alkoxy and
• X represents linear, branched or cyclic, optionally unsaturated C1-C12 alkylene radicals.
• b) at least one double bond-containing rubber and
• c) at least one silicon-containing filler,
• and optionally additional rubber additives and other fillers.

A molded article comprising a rubber compounds comprising

• a) at least one network comprising esters of one or more unsaturated aromatic or aliphatic hydroxycarboxylic acids and one or more aromatic or aliphatic polyols, crosslinked with sulfur bridges, wherein said network comprises a sulfur content in the range from 0.2 wt. % to 17%, and wherein
• i) the hydroxycarboxylic acid(s) each comprise 1, 2 or 3 olefinic double bonds and hydroxyl groups or hydroxyl and isocyanate groups,
• ii) the polyol component(s) each comprise 1 to 6 carbon atoms and 1 to 6 hydroxyl groups and optionally isocyanate groups,
• iii) the network comprises (thio)urethane or urea substituents, which in turn have one or more terminal silane substituents according to formula (I)
• R1R2R3Si-X-(thio)urethane/urea group (I)
• wherein in formula (I)
• R1, R2, R3 are the same or different and denote C1-C18 alkyl or C1-C18 alkoxy and
• X represents linear, branched or cyclic, optionally unsaturated C1-C12 alkylene radicals.
• b) at least one double bond-containing rubber and
• c) at least one silicon-containing filler,
• and optionally additional rubber additives and other fillers.