EP0503825A1
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Method of making siloxane compositions
Assignee: Dow Silicones Belgium SPRL
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Filing: 1992-03-04
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Granted: —
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Expires: 2012-03-04
Abstract
Abstract A method of making a dispersion of a high viscosity siloxane in a volatile, especially cyclic siloxane, comprises first dispersing organopolysiloxanes having at least 2 Si-OR groups, wherein R is H or alkyl in a volatile siloxane, and adding a catalyst which is either a phosphonitrile halide having the general formula [X(PX₂=N) n PX₃]⁺[MX (v-t+1) R t ]⁻ , or a heterogeneous catalyst, selected from Li, Mg, Ca, Sr or Ba hydroxide, Na or K borate or phosphate, Rb or Cs carbonate, or carboxylates of Rb or Cs, wherein M is an element having an electronegativity of from 1.0 to 2.0, R is alkyl, X is halide, n is 1 to 6, v is the valence of M and t is from 0 to ( v -1).
Inventors
- 👤 Jean De La Croi Habimana
- 👤 Stephen Westall
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 18:23
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/02; C08J3/09; C08J3/091; C08J3/098; C08G; C08G77/00; C08G77/04; C08G77/06; C08G77/08; C08J2383/00; C08J2383/04
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
209 words
A method of making a dispersion of a high viscosity siloxane in a volatile siloxane, which comprises making a first dispersion of organopolysiloxanes having at least 2 silicon-bonded groups -OR, wherein R denotes a hydrogen atom or an alkyl group having up to 6 carbon atoms in a volatile siloxane, followed by contacting said first dispersion with a catalyst which is either (A) a phosphonitrile halide having the general formula [X(PX₂=N) n PX₃]⁺[MX (v-t+1) R t ]⁻ , or (B) a heterogeneous catalyst, selected from lithium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, sodium borate, sodium phosphate, potassium borate, potassium phosphate, rubidium carbonate, caesium carbonate and carboxylates of rubidium or caesium of the general formula Q.CO.OZ, wherein M is an element having an electronegativity of from 1.0 to 2.0 according to Pauling's scale, Q represents an alkyl group having from 1 to 6 carbon atoms or an alkenyl group having from 2 to 5 carbon atoms, R is an alkyl group having up to 12 carbon atoms, X denotes a halide atom, Z represents Cs or Rb, n has a value of from 1 to 6, v is the valence or oxidation state of M and t has a value of from 0 to ( v -1).
Claim 2
Dependent Claim
49 words
A method according to Claim 1, wherein the volatile siloxane is a cyclic siloxane of the general formula (R′₂SiO) p wherein R′ denotes hydrogen or an alkyl, alkenyl or aryl group having up to 8 carbon atoms, p is an integer with a value of from 3 to 12.
Claim 3
Dependent Claim
18 words
A method according to Claim 1 or 2, wherein substantially all groups R′ and R² are methyl groups.
Claim 4
Independent Claim
29 words
A method according to any one of the preceding claims, wherein the organopolysiloxane is a substantially linear siloxane polymer, having on each terminal siloxane unit a silicon-bonded group OH.
Claim 5
Independent Claim
22 words
A method according to any one of the preceding claims, wherein the viscosity of the organopolysiloxane used is from 50 to 500mm²/s.
Claim 6
Independent Claim
29 words
A method according to any one of the preceding claims, wherein the weight ratio of organopolysiloxane to volatile siloxane used in the first dispersion is from 1/20 to 1/2.
Claim 7
Independent Claim
25 words
A method according to any one of the preceding claims, wherein the catalyst is neutralised when the high viscosity siloxane has reached the desired viscosity.
Claim 8
Independent Claim
32 words
A method according to any one of the preceding claims, wherein catalyst (A) is used in an amount of from 5 to 50ppm by weight based on the weight of the organopolysiloxane.
Claim 9
Independent Claim
21 words
A method according to any one of the preceding claims wherein M denotes Sb and n has a value of 2.
Claim 10
Independent Claim
38 words
A method according to any one of Claims 1 to 7, wherein catalyst (B) is used in the form of a catalyst bed in an amount of from 0.1-5% by weight based on the weight of the organopolysiloxane.
References Cited (Backward Citations)
EP0206525A2
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EP0382366A2
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