Method for the preparation of an organohydrogenpolysiloxane as a product of a partial addition reaction

Claim 1

A method for the preparation of an organohydrogenpolysiloxane comprising the steps of: A. partial addition reaction between a. a cyclic or non-cyclic organic unsaturated compound with an aliphatic double bond in the molecule selected from the group consisting of ethylene, propylene, cyclohexene, styrene, α-methylstyrene, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, allyl acetate, allyl acrylate, allyl methacrylate, allyl glycidyl ether, vinyl cyclohexene monoepoxide and 4-vinyl styreneoxide, and b. starting organohydrogenpolysiloxane represented by the average formula (R) a (H) b SiO.sub.( 4-a-b)/2 where R is methyl or phenyl, a and b are each positive numbers expressed as 1 ≦ a ≦ 2 and b ≦ 1, respectively, with the proviso that 2 ≦ (a + b) ≦ 3, and having at least two hydrogen atoms directly bonded to the silicon atoms through Si--H linkages in one molecule, in an amount such that the amount of said hydrogen atoms in said starting organohydrogenpolysiloxane is in excess over equimolar to said aliphatic double bond, in the presence of a platinum catalyst, by which part of said Si--H linkages are subjected to addition reaction with said aliphatic double bonds and the remaining of said Si--H linkages are left unreacted, B. addition of a compound selected from the group consisting of benzothiazole, 2,2'-dithiobisbenzothiazole, 2-(morpholinothio)benzothiazole, and 2-(morpholinodithio) benzothiazole to the reaction mixture obtained by said partial addition reaction in an amount larger than equimolar to said platinum catalyst, and C. recovery of an organohydrogenpolysiloxane as the finished product by distillation.

Claim 2

A method for the preparation of an organohydrogenpolysiloxane comprising the steps of: A. partial addition reaction between a. a cyclic or non-cyclic organic unsaturated compound with an aliphatic double bond in the molecule selected from the group consisting of ethylene, propylene, cyclohexene, styrene, α-methylstyrene, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, allyl acetate, allyl acrylate, allyl methacrylate, allyl glycidyl ether, vinyl cyclohexene monoepoxide and 4-vinyl styreneoxide, and b. starting organohydrogenpolysiloxane represented by the average formula (R) a (H) b SiO.sub.( 4-a-b)/2 where R is methyl or phenyl, a and b are each positive numbers expressed as 1 ≦ a ≦ 2 and b ≦ 1, respectively, with the proviso that 2 ≦ (a + b) ≦ 3, and having at least two hydrogen atoms directly bonded to the silicon atoms through Si--H linkages in one molecule, in an amount such that the amount of said hydrogen atoms in said starting organohydrogenpolysiloxane is in excess over equimolar to said aliphatic double bond, in the presence of a platinum catalyst, by which part of said Si--H linkages are subjected to addition reaction with said aliphatic double bonds and the remaining of said Si--H linkages are left unreacted, B. addition of a compound selected from the group consisting of benzothiazole, 2,2'-dithiobisbenzothiazole, 2-(morpholinothio)benzothiazole, and 2-(morpholinodithio) benzothiazole to the reaction mixture obtained by said partial addition reaction in an amount larger than equimolar to said platinum catalyst, and C. recovery of an organohydrogenpolysiloxane as the finished product by distillation.