Preparation of triorganosiloxy end-capped organopolysiloxane

• US 8,110,646 B2
• Filed: 08/06/2010
• Issued: 02/07/2012
• Est. Priority Date: 08/14/2009
• Status: Active Grant

• Current Assignee: Shin-Etsu Chemical Company Limited
• Original Assignee: Shin-Etsu Chemical Company Limited
• Inventors: Yamazaki, Toshio, Oishi, Kazuhiro
• Primary Examiner(s): LOEWE, ROBERT S
• Application Number:
  US12/851,898
• Publication Number:
  US 20110040063A1
• Time in Patent Office: 550 Days
• Field of Search: 528/14, 528/15
• US Class Current: 528/14
• CPC Class Codes: C08G 77/12 containing silicon bound to hydrogen C08G77/045 takes precedence
• CPC Class Codes: C08G 77/20 containing silicon bound to unsaturated aliphatic groups C08G77/045 takes precedence
• CPC Class Codes: C08G 77/24 halogen-containing groups

Abstract

A triorganosiloxy end-capped organopolysiloxane, i.e., organopolysiloxane having a backbone consisting essentially of repeating (3,3,3-trifluoropropyl)methylsiloxane units and end-capped with triorganosiloxy groups is prepared by copolymerizing tris(3,3,3-trifluoropropyl)trimethylcyclo-trisiloxane with a silanol end-capped organopolysiloxane in the presence of an alkyllithium or lithium silanolate catalyst to form a silanol end-capped copolymer, and adding a trialkylsilyl triflate or strong acid in excess relative to the catalyst and a hexaorganodisilazane for effecting end-capping and neutralization.

Claims

1. A process for preparing a triorganosiloxy end-capped organopolysiloxane, comprising the steps of:

copolymerizing tris(3,3,3-trifluoropropyl)trimethyl-cyclotrisiloxane which is a cyclic trimer of the formula (1);

2. The process of claim 1 wherein said alkyllithium catalyst or lithium silanolate catalyst is a lithium silanolate catalyst of the general formula (5):

3. The process of claim 1 wherein the hexaorganodisilazane is hexamethyldisilazane, 1,3-divinyltetramethyldisilazane or both.

4. The process of claim 1 wherein the trialkylsilyl triflate is trimethylsilyl triflate, dimethylvinylsilyl triflate or both.

5. The process of claim 1 wherein the strong acid is at least one member selected from the group consisting of trifluoromethanesulfonic acid, methanesulfonic acid, conc. sulfuric acid, p-toluenesulfonic acid, hydrochloric acid, aluminum chloride, and boron trifluoride-diethyl ether complex.

6. The process of claim 1 wherein the trialkylsilyl triflate is dimethylvinylsilyl triflate, the hexaorganodisilazane is 1,3-divinyltetramethyldisilazane, and the organopolysiloxane of formula (3) has the general formula (4):

7. The process of claim 1 wherein the step of heating the reaction product in vacuum to remove any vulcanization inhibitors is at a temperature of at least 150°

C.

8. A process for preparing a triorganosiloxy end-capped organopolysiloxane, comprising the steps of:

copolymerizing tris(3,3,3-trifluoropropyl)trimethyl-cyclotrisiloxane which is a cyclic trimer of the formula (1);