High purity hydroxy-terminated phenyl ladder polysiloxane and method for producing the same

A high purity hydroxy-terminated phenyl and alkenyl substituted ladder siloxane prepolymer which contains therein 1 ppm or below of each of sodium, potassium, iron, copper, lead and chlorine, and 1 ppb or below of each of uranium and thorium, and is represented by the following formula (I):

• ##STR13## where:
• R.sub.1 is phenyl and R.sub.2 is an alkenyl group;
• n is an integer of from 7 to 16;
• m and l are natural numbers satisfying relationships of 2n=m+l and l/m+l.gtoreq.0.02.

A method for producing a high purity hydroxy-terminated phenyl and alkenyl substituted ladder siloxane prepolymer which contains therein 1 ppm or below of each of sodium, potassium, iron, copper, lead and chlorine, and 1 ppb or below of each of uranium and thorium, and is represented by the formula (I) ##STR14## where R.sub.1 is phenyl and R.sub.2 is an alkenyl group;

• n is an integer of from 7 to 16;
• m and l are natural numbers satisfying relationships of 2n=m+l and l/m+l.gtoreq.0.02, said method comprising the steps of:
• preparing a solution by dissolving into an organic solvent a mixture prepared by mixing phenyl trichlorosilane with 2 mol % or above of a compound of the formula (II) ##STR15## where X is a hydrogen atom, methyl group, ethyl group or phenyl group;
• p is an integer of from 0 to 10, the concentration of said mixture in said organic solvent being from 0.05 to 0.45 g/ml;
• then hydrolyzing the solution by adding 3 to 30 mol parts of super-demineralized water to 1 mol par in total of said phenyl trichlorosilane and said compound of the formula (II), at room temperature or below;
• and thereafter rinsing said hydrolyzed product with super-demineralized water.

A method for producing a high purity hydroxy-terminated phenyl and alkenyl substituted ladder polysiloxane which contains therein 1 ppm or below of each of sodium, potassium, iron, copper, lead and chlorine, and 1 ppb or below of each of uranium and thorium, and is represented by the formula (I) ##STR16## where R.sub.1 is phenyl and R.sub.2 is an alkenyl group;

• n is an integer of rom 7 to 1600;
• m and l are natural number satisfying relationships of 2n=m+l and l/m+l.gtoreq.0.02, said method comprising the steps of:
• preparing a solution by dissolving into an organic solvent a mixture prepared by mixing phenyl trichlorosilane with 2 mol % or above of a compound of the formula (II) ##STR17## where:
• X in a hydrogen atom, methyl group, ethyl group or phenyl group;
• p is an integer of from 0 to 10, the concentration of said mixture in said organic solvent being from 0.05 to 0.45 g/ml;
• then hydrolyzing the solution by adding 3 to 30 mol parts of super-demineralized water to 1 mol par in total of said phenyl trichlorosilane and said compound of the formula (II), at room temperature or below;
• thereafter rinsing said hydrolyzed product with super-demineralized water;
• adding nucleophilic reagent to the layer of said organic solvent in a quantity in the range of from 0.005 to 0.5% by weight with respect to said prepolymer;
• then heating said mixture solution to subject said hydrolyzed product to dehydration and condensation, thereby obtaining a high molecular weight substance;
• and refining said high molecular weight substance by dissolving it in a solvent at a concentration of from 2 to 8% by weight an reprecipitating it.