Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Patent
1980-08-14
1982-07-27
Marquis, Melvyn I.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
528 18, 528 21, 528 22, 528 23, 528 33, 528 37, C08G 7706
Patent
active
043418880
ABSTRACT:
Diorganopolysiloxane copolymers having a viscosity from 50 to 200,000,000 centipoise at 25.degree. C., are produced by reacting a mixture of (i) a cyclic tetrasiloxane having at least one silicon-bonded organo substituent of three to eight carbon atoms, with (ii) a cyclic siloxane having 3 to 6 siloxane units, (i) being present in an amount of 30 to 98 mol % of the mixture of (i) and (ii), at a temperature in the range of 0.degree. to 90.degree. C. and in the presence of 5 to 300 parts per million of a catalyst comprising cesium hydroxide, a silanolate thereof, or a compound of the formula, ##STR1## wherein R.sup.3 is alkyl of 1 to 8 carbon atoms, cycloalkyl of 4 to 8 carbon atoms or phenyl, B is nitrogen or phosphorous, R.sup.4 is alkyl of 1 to 8 carbon atoms, cycloalkyl of 4 to 8 carbon atoms, phenyl, a siloxane chain of unit formula R.sub.a.sup.5 SiO.sub.(4-a)/2 and mixtures thereof, wherein R.sup.5 is monovalent hydrocarbon or halogenated monovalent hydrocarbon, and a is from 1.5 to 2.5. Especially useful products of the process are copolymers having (i) siloxane chain units of the formula (i) R R.sup.1 SiO and (ii) R.sub.2.sup.2 SiO, (i) being present in an amount of 30 to 85 mol % of the copolymer units, and wherein R.sup.1 is alkyl, halogenated alkyl or cycloalkyl, and preferably, perfluoroalkyl, R is the same as R.sup.1 and, in addition, methyl, ethyl, vinyl or phenyl; and R.sup.2 is, independently, methyl, ethyl, vinyl or phenyl.
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General Electric Company
Marquis Melvyn I.
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