Scavengers for ammonia in RTV compositions
AssigneeGeneral Electric Company
InventorJohn J. Dziark
Life of this patent
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Abstract
A stable, one-package, silicone RTV composition convertible to a tack-free elastomer comprising: (1) a polydiorganosiloxane base polymer, (2) an effective amount of condensation catalyst, (3) a stabilizing amount of a silicon-nitrogen compound for scavenging hydroxy radicals which releases ammonia as a by-product of the scavenging reaction, and (4) an effective amount of scavenger for said ammonia by-product selected from the group consisting of molecular sieves, acids and mixtures thereof.
Claims40
A stable, one-package, substantially anhydrous and substantially acid-free, room temperature vulcanizable organopolysiloxane composition stable under ambient conditions in the substantial absence of moisture over an extended period of time and convertible to a tack-free elastomer, comprising:
- (A) an organopolysiloxane wherein the silicon atom at each chain end is terminated with at least two alkoxy radicals;
- (B) an effective amount of condensation catalyst;
- (C) a stabilizing amount of a silicon-nitrogen compound for scavenging hydroxy radicals, said silicon-nitrogen compound releasing ammonia as a by-product of the hydroxy-scavenging reaction;
- and
- (D) an effective amount of a scavenger for said ammonia by-product selected from the group consisting of molecular sieves and acids and mixtues thereof.
A method of making a one-package and substantially acid-free room temperature vulcanizable composition curable to the solid elastomeric state, which method comprises agitating under substantially anhydrous conditions at a temperature in the range of from about 0.degree. C. to about 180.degree. C., a room temperature vulcanizable material selected from
- (i) a mixture comprising:
- (A) 100 parts of a silanol terminated polydiorganosiloxane;
- (B) a stabilizing amount of a silicon-nitrogen compound for scavenging hydroxy radicals, said silicon-nitrogen compound releasing ammonia as a by-product of the hydroxy-scavenging reaction;
- (C) 0 to 10 parts of a crosslinking silane of the formula ##STR19## (D) an effective amount of a condensation catalyst;
- and (E) an effective amount of a scavenger for said ammonia by-product of the hydroxy-scavenging reaction selected from the group consisting of molecular sieves and acids and mixtures thereof;
- and
- (ii) a mixture comprising
- (A) 100 parts of a polyalkoxy-terminated polydiorganosiloxane base polymer;
- (B) 0 to 10 parts of a crosslinking silane of the formula ##STR20## (C) an effective amount of a condensation catalyst;
- (D) a stabilizing amount of a silicon-nitrogen compound for scavenging hydroxy radicals, said silicon-nitrogen compound releasing ammonia as a by-product of the hydroxy-scavenging reaction;
- and
- (E) an effective amount of a scavenger for said ammonia by-product of the hydroxy-scavenging reaction selected from the group consisting of molecular sieves and acids and mixtures thereof;
- where R.sup.1 is a C.sub.1-8 aliphatic organic radical selected from the group consisting of alkyl, alkylether, alkylester, alkylketone, and alkylcyano or a C.sub.7-13 monovalent substituted or unsubstituted hydrocarbon radial, R.sup.2 is a C.sub.1-13 monovalent substituted or unsubstituted hydrocarbon radical, and e equals 0 or 1.
In a method for making a one-package and substantially acid free room temperature vulcanizable composition curable to the solid elastomeric state, which method comprises agitating under substantially anhydrous conditions at a temperature in the range of from about 0.degree. C. to about 180.degree. C., a room temperature vulcanizable material comprising a mixture of:
- (A) 100 parts of a silanol-terminated or polyalkoxy-terminated polydiorganosiloxane;
- (B) a stabilizing amount of a silicon-nitrogen compound for scavenging hydroxy radicals, said silicon-nitrogen compound releasing ammonia as a by-product of the hydroxy-scavenging reaction;
- (C) 0 to 10 parts of a crosslinking silane of the formula ##STR26## (D) an effective amount of a condensation catalyst;
- and (E) 0 to 5 parts of a curing accelerator selected from the group consisting of substituted guanidines, amines and mixtures thereof;
- where R.sup.1 is a C.sub.1-8 aliphatic organic radical selected from the group consisting of alkyl, alkylether, alkylester, alkylketone, and alkylcyano or a C.sub.7-13 monovalent substituted or unsubstituted hydrocarbon radical, R.sup.2 is a C.sub.1-13 monovalent substituted or unsubstituted hydrocarbon radical, and e equals 0 or 1;
- the improvement comprising adding to the composition or placing in the airspace of a container having said composition therein an effective amount of a scavenger for said ammonia by-product of the hydroxy-scavenging reaction selected from the group consisting of molecular sieves and acids, and mixtures thereof.
In a stable, one-package, substantially anhydrous and substantially acid-free room temperature vulcanizable organopolysiloxane composition stable under ambient conditions in the substantial absence of moisture over an extended period of time and convertible to a tack-free elastomer, having an organopolysiloxane, a condensation catalyst and a compound which releases ammonia, the improvement which comprises having present in said composition an effective amount of scavenger for ammonia selected from the group consisting of molecular sieves, acids and mixtures thereof.
In a method for eliminating ammonia in stable, one-package, substantially anhydrous and substantially acid-free room temperature vulcanizable organopolysiloxane compositions stable under ambient conditions in the substantial absence of moisture over an extended period of time and convertible to a tack-free elastomer, having an organopolysiloxane, a condensation catalyst and a compound which releases ammonia, the improvement which comprises adding an effective amount of scavenger for ammonia selected from the group consisting of molecular sieve, acids and mixtures thereof.
Dependencies are inferred from the claim text.