Silalkylene oligosiloxane surface treating agent and process for preparation

A process for the preparation of a silalkylene oligosiloxane described by general formula

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• where R1 is a monovalent hydrocarbon group having at least 2 carbon atoms that does not have aliphatic unsaturated bonds, each R2 is an independently selected monovalent hydrocarbon group having 1 to 10 carbon atoms that do not have aliphatic unsaturated bonds, R3 is an alkylene group having at least 2 carbon atoms, R4 is an alkyl group, a is an integer of 0 to 2 and b is an integer of 1 to 3, with the proviso that a+b is an integer of 1 to 3, c is an integer of 1 to 3, and n is an integer of 0 or 1;
• the process comprising reacting a mixture comprising
• (A) a silalkylene oligosiloxane containing silicon-bonded hydrogen atoms described by general formula
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• where each R2 is an independently selected monovalent hydrocarbon groups having 1 to 10 carbon that that do not have aliphatic unsaturated bonds, R3 is an alkylene group having at least 2 carbon atoms, R4 is an alkyl group, a is an integer of 0 to 2 and b is an integer of 1 to 3, with the proviso that a+b is an integer of 1 to 3, c is an integer of 1 to 3, and n is an integer of 0 or 1;
• (B) a hydrocarbon compound having one aliphatic double bond per molecule;
• and
• (C) a hydrosilation reaction catalyst.