Process for producing diorganopolysiloxane
AssigneeChisso Corporation
InventorsTakaharu Nakano, Katsuyoshi Tsuchiya, Shunji Yoshimatsu, Takeru Fuchigami
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Abstract
A process is disclosed for producing a diorganopolysiloxane by polymerizing a cyclic siloxane expressed by the following general formula (2) ##STR1## wherein R.sup.3 represents methyl group, ethyl group, or phenyl group, and p is an integer of 3 or 4, by an anion living polymerization using a lithium trialkylsilonolate or an alkyl lithium as a polymerization initiator and then terminating the anion living polymerization with an acid or a chlorosilane derivative, the improvement comprising treating a diorganopolysiloxane which is modified with a silanol at both its terminals and included in the cyclic siloxane as impurities, with an acetylating agent.
Claims4
In a process for producing a diorganopolysiloxane, which comprises subjecting a cyclic siloxane expressed by formula (2) ##STR4## wherein R.sup.3 represents methyl, ethyl or phenyl, and p is an integer of 3 or 4, containing as impurity a diorganopolysiloxane modified with a silanol group at both its terminals, to an anion living polymerization using an initiator expressed by formula (1)
- R.sup.1 Li (1)
- wherein R.sup.1 represents an alkyl group having 1 to 4 carbon atoms or a group expressed by the formula ##STR5## in which R.sup.2 represents an alkyl group having 1 to 4 carbon atoms, and terminating the anion living polymerization with an acid or a chlorosilane expressed by formula (3)
- R.sup.4 R.sup.3.sub.n SiX.sub.3-n ( 3)
- wherein R.sup.3 is as defined above, R.sup.4 represents a hydrogen atom or an organic functional group, X represents a halogen atom, and n is an integer of 0 to 2,
- the improvement which comprises acetylating the diorganopolysiloxane modified with a silanol at both its terminals with an acetylating agent prior to initiation of the polymerization.
Dependencies are inferred from the claim text.