CS223931B1 - Method of preparation of liquid silicon rubbers with non-saturated groups - Google Patents

Description

The invention relates to a process for the preparation of liquid unsaturated silicone rubbers.

The present process for the preparation of these polydiorganosiloxanes consists in ionic copolymerization of cyclic diorganosiloxanes containing unsaturated groups, optionally in the presence of unsaturated group-containing carriers. The resulting polydiorganosiloxanes have randomly distributed unsaturated groups on macromolecular chains.

The process for preparing liquid unsaturated silicone rubbers is based on the substitution of the hydrogen -OH groups of polydiorganosiloxanes, e.g. alpha, omega-dihydroxypolydiorganosiloxanů unsaturated groups using silyl amine of the formula R ^ rgr ^ Shihri ^ Rg, wherein if, R> ^{H +} 31 K) * ^»R 2 ^brand ~ as alkyl or alkenyl of 1 to 8 carbon atoms per molecule, with at least one of R ,, R ₂ or R must be alkenyl, preferably vinyl group. Silylamine reacts with the -OH groups of the polydiorganosiloxanes according to the equation

R ^ RGR SiNRýRg + HO-Si = -> R, R ₂ R.jSi-O-Si = + RptjNH.

The reaction is carried out at temperatures of 10 to 200 ° C, optionally in an environment of non-polar solvents, the silylamine being added in an amount of 0.1 to 10 wt. parts per 100 wt. parts of polydiorganosiloxanes.

An advantage of the process for the preparation of liquid unsaturated silicone rubbers according to the invention is the quantitative efficiency of substitution, and thus polydiorganosiloxanes with unsaturated groups at different chain viscosity and unsaturated group concentrations can be prepared according to the -OH group concentration in the starting alpha, omega-dihydroxypolydiorganosiloxanes. Substitution of the -OH groups with silylamine can be carried out on the alpha, omega-dihydroxypolydiorgsnosiloxanes produced or during their production.

The unsaturated group polymers thus prepared are suitable for vulcanizing with organic peroxides which are selective for unsaturated groups or for addition (hydrosilylation) crosslinking. The physico-mechanical properties of the vulcanisates are dependent on the viscosity and concentration of unsaturated groups of the polymers thus prepared.

The following examples illustrate the invention in more detail.

Example 1

80 kg of octamethylcyclotetrasiloxane are introduced into the polymerization boiler, 0.4 kg of montmorillonite clay bleach, 0.8 kg of filter diatomaceous earth and 100 ml of water are added. The polymerization is carried out under nitrogen at 30C kPa at 150C for 2 hours. After the polymerization is complete, the polymer is filtered and 4 wt. % dimethylvinyl-N, N-diethylaminosilane. After 30 minutes at 150 ° C, the volatiles were distilled off at 180 ° G / 1.33 kPe for 3 hours. The demonomerized alpha, omega-divinylpolydimethylsiloxane polymer was designated A and had a viscosity of 1246 mPas and 0.85 wt. % (CH ^) 2θΗ2 = 0Η31Ο groups bound at the ends of the polymer chains.

Example 2

4 wt.% Of alpha, omega-dihydroxypolydimethylsiloxane having a viscosity of 1246 mPas were added. percent dimethylvinyl-N, N-diethylaminosilane. After stirring at 150 ° C for 30 min, excess silylemin and the resulting diethylemin were distilled off at 180 ° C / 1.33 kPa to give polymer B alpha, omega-divinylpolydimethylsiloxane having a viscosity of 1246 mPas and 0.85 wt. % (GH 2) ₂ CH ₂ = CHSiO groups weighted at the ends of the polymer chains.

Example 3

5.6 g of rhodium acetylacetonate as a 1% solution in isopropanol and 10 g of polymethylhydrogensiloxane having a viscosity of 460 mPas and a content of 0.6 wt. After 30 minutes of vulcanization at 150 ° C, vulcanizates A and B are obtained having a mesh density v = 3.18.10 -4 mol / enP.

Example 4

1 g of dimethylvinyl-N, N-di-n-butylaminosilene is stirred into 100 g of alpha, omega-dihydroxypolydimethylsiloxane having a viscosity of 33,600 mPas, and after stirring for 30 minutes at 450 DEG C. excess silylamine and the resulting di-n-butylamine are distilled off at 180 DEG. ° C / 1.33 kPa. The resulting alpha, omega-divinylpolydimethylsiloxane having a viscosity of 33,600 mPas containing 0.17 wt% (CH3) of the 2CH2 = CHSiO groups is mixed with 5.6.10 < -1 > g of rhodium acetylacetonate as a 1% solution in isopropanol and 10 g of polymethylhydrogensiloxane. with a viscosity of 460 mPas and a content of 0.6 wt. After 30 min of vulcanization at 150 ° C, a vulcanizate is obtained having a mesh density of 4.68 x 10 6 mol / cnP.

Claims (1)

Process for the preparation of liquid silicone rubbers with unsaturated groups, wherein the polydiorganosiloxane containing OH groups, e.g. alfa.omega-dihydroxypolydimethylsiloxane acts silylamine of the formula R ^ Rg SINR / R ^{'where R} 1 ^»K 2' ^R 3 ' ^R * 1 ^R 2 ^{0 ing} ® ^on her or elkenyly alkyls having 1 to 8 carbon atoms, wherein at least one R _1, ί? ₂ or it must be alkenyl, preferably vinyl.