METHOD OF PRODUCING LOW-MOLECULAR POLYDIMETHYL METHYL PHENYL SILOXANE RUBBER WITH HYDROXYL END GROUPS Russian patent published in 2020 - IPC C08G77/06 C08G77/16 C08G77/08 

FIELD: manufacturing technology.

SUBSTANCE: invention relates to the technology of producing organosilicon low-molecular rubber, which can be used in production of thermo-, frost-resistant composite materials (coatings, sealants, adhesives, etc.). Disclosed is a method of producing low-molecular weight siloxane rubber of formula (I), where m⋅x=11–21, n⋅x=271–344, with viscosity of 0.7 Pa⋅s (700 cP) to 1.2 Pa⋅s (1200 cP), characterized by the fact that copolymerisation of cyclosiloxanes, which are trimethyltrypthenyl cyclotrisiloxane and decamethylcyclopentasiloxane, taken in molar ratio of 1:10 to 1:15, are carried out under the action of a catalyst which is a strongly acidic cation-exchange resin, which is a sulphonated copolymer of styrene with divinylbenzene with water content of 45–55 %, moisture of which is a chain transfer agent, taken in amount of 8–12 % of the weight of the initial reagents, and the process is carried out at atmospheric pressure and temperature of 95–105 °C with intense stirring for 40–90 minutes. (HO)(CH₃)₂SiO-{[(CH₃)₂SiO]_m[(CH₃)(C₆H₅)SiO]_n}_x- Si(CH₃)₂(OH) (I).

EFFECT: disclosed is an efficient method of producing low-molecular polydimethyl methyl phenyl-siloxane rubber with terminal hydroxyl groups with viscosity of 0,7–1,2 Pa·s.

1 cl, 4 ex