Claims
- 1. A continuous process for preparing a stable, one package, substantially anhydrous, 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 passing through a devolatilizing extruder:
- (a) an organopolysiloxane wherein the silicon atom at each polymer chain end is hydroxy terminated;
- (b) a polyalkoxy crosslinking agent; and
- (c) an end-capping catalyst system which is a mixture of an acidifying agent and an amine where the acidifying agent is a Lewis acid and wherein the amine is selected from primary, secondary and tertiary amines;
- so as to produce polyalkoxy-terminated organopolysiloxanes wherein when a condensation catalyst is mixed in the polyalkoxy-terminated organopolysiloxane there is formed an RTV composition.
- 2. The process of claim 1 wherein (a), (b) and (c) are mixed in a static mixer to produce polyalkoxy-terminated organopolysiloxanes, further comprising mixing additional ingredients into the polyalkoxy-terminated organopolysiloxane in a devolatilizing extruder.
- 3. The process of claim 2 wherein in the initial mixing chamber of the devolatilizing extruder, there is mixed the polyalkoxy-terminated organopolysiloxane, fumed silica, a triorganosiloxy end-stopped diorganopolysiloxane plasticizer polymer of 10 to 20,000 centipoise viscosity at 25.degree. C. and a polyether as a sag control agent.
- 4. The process of claim 3 wherein there is present from 1 to 50 parts by weight of the fumed silica, from 10 to 50 parts by weight of the triorganosiloxy end-stopped diorganopolysiloxane plasticizer polymer where the organo is a monovalent hydrocarbon radical and 0.1 to 2.0 parts by weight of the polyether per 100 parts by weight of the polyalkoxy-terminated organopolysiloxane.
- 5. The process of claim 3 wherein in a subsequent mixing chamber in the devolatilizing extruder there is further added amounts of a scavenger effective for tying up hydroxyl groups.
- 6. The process of claim 5 wherein in a subsequent mixing chamber after additional amounts of the scavenger have been added, there is added a mixture of a condensation catalyst, adhesion promoter, and optionally, excess amounts of the polyalkoxy silane cross-linking agent.
- 7. The process of claim 2 wherein the static mixer is operated at a temperature of 40.degree. C. to 100.degree. C.
- 8. The process of claim 7 wherein the devolatilizing extruder is operated at a temperature in the range of 40.degree. to 100.degree. C. and at a vacuum that is less than 20 inches Hg.
- 9. The process of claim 2 wherein the devolatilizing extruder is a single screw devolatilizing extruder.
- 10. The process of claim 2 wherein the devolatilizing extruder is a twin-screw devolatilizing extruder.
- 11. The process of claim 2 which produces a room temperature vulcanizable silicone rubber composition that has an application rate in the uncured state above 50 to 100 grams per minute or higher.
- 12. The process of claim 2 wherein in the initial mixing chamber of the devolatilizing extruder, there is mixed the polyalkoxy-terminated organopolysiloxane, fumed silica, calcium carbonate, a sag control polyether, atriorganosiloxy end-stopped diorganopolysiloxane where the organo is a monovalent hydrocarbon radical, having a viscosity of 10 to 20,000 centipoise at 25.degree. C. and a MTD plasticizer having from (i) 5 to 60 mole percent of monoalkylsiloxy, siloxy units or a mixture of such units; (ii) from 1 to 6 mole percent of trialkylsiloxy units; (iii) from 34 to 94 mole percent of dialkylsiloxy units; said plasticizer having from about 0.1 to 2.0 by weight of silicon-bonded hydroxyl groups.
- 13. The process of claim 12 wherein the fumed silica is treated with cyclic polysiloxanes and the calcium carbonate is treated with stearic acid.
- 14. The process of claim 13 wherein there is present from 1 to 50 parts by weight of fumed silica, from 100 to 300 parts by weight of calcium carbonate, from 0.1 to 2.0 parts by weight of the polyether, from 10 to 50 parts by weight of the triorganosiloxy end-stopped diorganopolysiloxane and from 2 to 20 parts by weight of the MTD plasticizer per 100 parts by weight of the polyalkoxy-terminated organopolysiloxane.
- 15. The process of claim 12 wherein in a subsequent mixing chamber in the devolatilizing extruder there is added a scavenger.
- 16. The process of claim 15 wherein in a subsequent mixing chamber, after the scavenger has been added, there is added a mixture of condensation catalyst, adhesion promoter and optionally, excess amounts of polyalkoxy silane cross-linking agent.
- 17. The process of claim 12 wherein the static mixer is operated at a temperature of 40.degree. to 100.degree. C.
- 18. The process of claim 17 wherein the devolatilizing extruder is operated at a temperature in the range of 40.degree. to 100.degree. C. and at a vacuum less than 20 inches of Hg.
- 19. The process of claim 12 wherein the devolatilizing extruder is a twin-screw devolatilizing extruder.
- 20. The process of claim 12 which produces a room temperature vulcanizable silicone rubber composition that can be applied to a substrate in the uncured state at the rate of 50 to 100 grams per minute.
- 21. The process of claim 2 wherein in the devolatilizing extruder there is added a stabilizing amount of a scavenger for hydroxy functional groups selected from the group consisting of non-cyclic silyl nitrogen compounds of the formula ##STR31## and cyclic silyl nitrogen compounds having at least one or all of the units of the formula ##STR32## and the rest of the units, if any, having the formula ##STR33## where R.sup.10 is a C.sub.1-8 aliphatic organic radical selected from the group consisting of alkyl, alkylether, alkylester, alkylketone, alkylcyano and aryl, R.sup.11 is a C.sub.1-8 monovalent substituted or unsubstituted hydrocarbon radical, Q is selected from hydrogen, C.sub.1-8 monovalent substituted or unsubstituted hydrocarbon radicals and radicals of the formula ##STR34## where R.sup.10 and R.sup.11 are as previously defined, where a varies from 0 to 2, f varies from 0 to 3, h is 0 or 1, where s is a whole number that varies from 1 to 25, d is a whole number that varies from 1 to 25, R.sup.22 is selected from hydrogen and C.sub.1-8 monovalent hydrocarbon radicals and R.sup.23 is independently selected from C.sub.1-8 monovalent hydrocarbon and hydrocarbonoxy radicals, A is selected from the group consisting of hydrogen and C.sub.1-8 monovalent substituted or unsubstituted hydrocarbon radicals and radicals of the formula ##STR35## where R.sup.10 and R.sup.11 are as previously defined, g varies from 0 to 3 and in the above scavengers there is at least one hydrocarbonoxy group in the molecule, R.sup.12 is defined the same as R.sup.10, R.sup.13 is defined the same as R.sup.11 and R.sup.14 is defined the same as R.sup.11.
- 22. The process of claim 2, having an effective amount of a cross-linking silane of the formula ##STR36## 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 radicals, or a C.sub.7-13 aralkyl radical, R.sup.2 is a C.sub.1-13 monovalent substituted or unsubstituted hydrocarbon radical, and b is a whole number equal to 0 or 1.
- 23. The process of claim 21 wherein the scavenger and cross-linking agent has the formula ##STR37##
- 24. The process of claim 21 wherein the cross-linking agent and scavenger is a cyclic silazane where R.sup.12, R.sup.13 are methyl.
- 25. The process of claim 1 wherein the acid is a Lowry-Bronsted acid selected from acid anhydrides.
- 26. The process of claim 1 wherein the acid is Lowry-Bronsted acid of the formula ##STR38## where R.sup.30, R.sup.31 are C.sub.(1-20) monovalent hydrocarbon radicals, j is a whole number that varies from 0 to 3.
- 27. The process of claim 1 wherein the acid is a Lowry-Bronsted acid of the formula ##STR39## where R.sup.32 is a C.sub.(1-20) monovalent hydrocarbon radical.
- 28. The process of claim 1 wherein the acid is a Lowry-Bronsted inorganic acid.
- 29. The process of claim 28 wherein inorganic acid is selected from the class consisting of HCl, H.sub.3 PO.sub.4, H.sub.2 SO.sub.4 and polyphosphoric.
- 30. The process of claim 1 wherein the acid anhydrides have the formula ##STR40## where R.sup.33, R.sup.34 are C.sub.(1-20) monovalent hydrocarbon radicals.
- 31. The process of claim 1 wherein the acid is a Lewis acid selected from the class consisting of
- BF.sub.3, (CH.sub.3 CH.sub.2).sub.2 O, and AlCl.sub.3.
- 32. The process of claim 2 wherein there is added in the devolatilizing extruder a stabilizing amount of scavenger for hydroxy functional groups which is a silicon-nitrogen compound selected from the group consisting of:
- (A) a silicone-nitrogen compound having the formula ##STR41## where Y is selected from R" and R'".sub.2 N-- and (B) a silicon-nitrogen polymer comprising
- (i) from 3 to 100 mole percent chemically combined structural units having the formula ##STR42## (2) from 0 to 97 mole percent chemically combined structural units represented by the formula ##STR43## where the silicon atoms of said silicon-nitrogen polymer are joined to each other by a member selected from an SiOSi linkage and an SiNR"Si linkage, the free valences of said silicon atoms other than those joined to oxygen to form a siloxy unit and nitrogen to form a silazy unit are joined to a member selected from an (R").sub.2 N radical and an R'" radical and where the ratio of the sum of said R'" radicals and said (R").sub.2 N radicals to the silicon atoms of said silicon-nitrogen polymer has a value of 1.5 to 3 inclusive, R" is a member selected from the group consisting of hydrogen, monovalent hydrocarbon radicals, and fluoroalkyl radicals, R'" is a member selected from hydrogen, monovalent hydrocarbon radicals and fluoroalkyl radicals, and c is a whole number equal to 0 to 3 inclusive.
- 33. The process of claim 32 wherein the silazane polymers are cyclic silazanes of chemically combined ##STR44## units where R", R'" are as previously defined to provide for a ratio of 1.5 to 3.0 of the sum of the R'" and (R").sub.2 N radicals per silicon atom in said silazane polymer.
- 34. The process of claim 32 wherein the silazane polymer comprises linear polymers having at least one unit selected from the class consisting of ##STR45## units, and ##STR46## units where R", R'" are as previously defined to provide for a ratio of 1.5 to 3 of the sum of the R'" and (R").sub.2 N radicals per silicon atom in said silazane polymer.
- 35. The process of claim 32 wherein the silazane polymers comprise linear polymers consisting essentially of ##STR47## units where R" and R'" are as defined to provide for a ratio of 1.5 to 3.0 of the sum of the R'" and (R").sub.2 N radicals per silicon atom in said silazane polymer.
- 36. The composition of claim 32 wherein the silazane polymers comprise having at least one unit selected from the class consisting of ##STR48## units and ##STR49## units where R" and R'" are as previously defined to provide for a ratio of 1.5 to 3 of the sum of the R'" and (R").sub.2 N radicals per silicon atom in said silazane polymer.
- 37. The composition of claim 32 wherein the silazane-siloxane compounds are copolymers with up to 97 mole percent of ##STR50## units wherein the silazane units are selected from the group consisting of, ##STR51## where R" and R'" and c are as previously defined to provide for a ratio of the sum of R'" and (R").sub.2 N radicals per silicon atom of said silazane-siloxane copolymer of from 1.5 to 3.
- 38. The composition of claim 32 wherein the silazane-siloxane compounds are cyclic consisting of chemically combined (R'").sub.2 SiO units and ##STR52## units where R" and R'" are as previously defined.
- 39. The composition of claim 32 wherein the silazane compound is a polysiloxane having the formula ##STR53## where R", R'" and n are as defined previously and Z is a member selected from R" and Si(R"').sub.3.
- 40. The process of claim 2 further comprising adding in the devolatilizing extruder a stabilizing amount of silane scavenger for hydroxy functional groups which is a silyl amine of the formula ##STR54## where R" is a radical selected from the group consisting of hydrogen and C.sub.(1-8) monovalent hydrocarbon radicals, R.sup.20 is selected from C.sub.(1-8) monovalent hydrocarbon radicals, C.sub.(1-8) alkoxy radicals and fluoroalkyl radicals, and g is a whole number that varies from 1 to 3, h is a whole number that varies from 0 to 2 and the sum of h+g does not exceed 3.
- 41. A method of continuously preparing 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 continuously mixing in a devolatilizing extruder
- (a) an organopolysiloxane wherein the silicon atom at each polymer chain end is hydroxy terminated;
- (b) a polyalkoxy crosslinking agent;
- (c) an endcapping catalyst system comprising a Lewis acid and an amine selected from primary, secondary and tertiary amines;
- (d) an effective amount of a condensation catalyst and,
- (e) an amount of a scavenger effective for tying up hydroxyl groups.
- 42. The method of claim 41 wherein the scavenger for hydroxy functional groups is selected from the class consisting of a non-cyclic silyl nitrogen scavenger of the formula ##STR55## and cyclic silyl nitrogen scavengers having at least one or all of the units of the formula, ##STR56## and the rest of the units, if any, having the formula ##STR57## where R.sup.10 is a C.sub.1-8 aliphatic organic radical selected from the group consisting of alkyl, alkylether, alkylester, alkylketone, alkylcyano, and aryl, R.sup.11 is a C.sub.1-8 monovalent substituted or unsubstituted hydrocarbon radical, Q is selected from hydrogen, C.sub.1-8 monovalent substituted or unsubstituted hydrocarbon radicals and radicals of the formula ##STR58## where R.sup.10, R.sup.11 are as previously defined, where a varies from 0 to 2, f varies from 0 to 3, h is 0 or 1, where s is a whole number that varies from 1 to 25, d is a whole number that varies from 1 to 25, R.sup.22 is selected from hydrogen and C.sub.1-8 monovalent hydrocarbon radicals and R.sup.23 is independently selected from monovalent hydrocarbons and hydrocarbonoxy radicals, A is selected from the class consisting of hydrogen and C.sub.1-8 monovalent substituted or unsubstituted hydrocarbon radicals and radicals of the formula ##STR59## where R.sup.10, R.sup.11 are as previously defined, g varies from 0 to 3 and in the above scavengers there is at least one hydrocarbonoxy group in the molecule, R.sup.12 is defined the same as R.sup.10, and R.sup.13 is defined the same as R.sup.11, and R.sup.14 is defined the same as R.sup.11.
- 43. The method of claim 41 having an effective amount of a cross-linking silane of the formula ##STR60## 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 radicals, or a C.sub.7-13 aralkyl radical, R.sup.2 is a C.sub.1-13 monovalent substituted or unsubstituted hydrocarbon radicals, and b is a whole number equal to 0 or 1.
- 44. The method of claim 41 wherein the acid is a Lowry-Bronsted acid selected from acid anhydrides.
- 45. The method of claim 41 wherein the acid is a Lowry-Bronsted acid of the formula ##STR61## where R.sup.30, R.sup.31 are C.sub.(1-20) monovalent hydrocarbon radicals, j is a whole number that varies from 0 to 3.
- 46. The method of claim 41 wherein the acid is a Lowry-Bronsted acid of the formula ##STR62## where R.sup.32 is a C.sub.(1-20) monovalent hydrocarbon radical.
- 47. The method of claim 41 wherein the acid is a Lowry-Bronsted inorganic acid.
- 48. The method of claim 41 wherein inorganic acid is selected from the class consisting of HCl, H.sub.3 PO.sub.4, H.sub.2 SO.sub.4, and polyphosphoric.
- 49. The method of claim 44 wherein the acid anhydrides have the formula ##STR63## where R.sup.33, R.sup.34 are C.sub.(1-20) monovalent hydrocarbon radicals.
- 50. The method of claim 41 wherein the acid is a Lewis acid selected from the class consisting of
- BF.sub.3 (CH.sub.3 CH.sub.2).sub.2 O, and AlCl.sub.3.
- 51. The method of claim 41 wherein the stabilizing amount of scavenger for hydroxy functional groups is a silicon-nitrogen compound selected from the group consisting of:
- (a) a silicon-nitrogen compound having the formula ##STR64## where Y is selected from R" and R'".sub.2 N-- and (b) a silicon-nitrogen polymer comprising
- (i) from 3 to 100 mole percent chemically combined structural units selected from the group consisting of units having the formula ##STR65## (2) from 0 to 97 mole percent chemically combined structural units represented by the formula ##STR66## where the silicon atoms of said silicon-nitrogen polymer are joined to each other by a member selected from an SiOSi linkage and a SiNR"Si linkage, the free valences of said silicon atoms other than those joined to oxygen to form a siloxy unit and nitrogen to form a silazy unit are joined to a member selected from an (R").sub.2 N radical and an R'" radical, and where the ratio of the sum of said R'" radicals and said (R").sub.2 N radicals to the silicon atoms of said silicon-nitrogen polymer has a value of 1.5 to 3, inclusive, R" is a member selected from the group consisting of hydrogen, monovalent hydrocarbon radicals and fluoroalkyl radicals, R'" is a member selected from the group consisting of hydrogen, monovalent hydrocarbon radicals and fluoroalkyl radicals, and c is a whole number equal to 0 to 3, inclusive.
- 52. The process of claim 42 wherein the stabilizing amount of scavenger for hydroxy functional groups is a silyl amine of the formula ##STR67## where R" is a radical selected from the group consisting of hydrogen and C.sub.(1-8) monovalent hydrocarbon radicals, R.sup.20 is selected from C.sub.(1-8) monovalent hydrocarbon radicals, C.sub.(1-8) alkoxy radicals and fluoroalkyl radicals, and g is a whole number that varies from 1 to 3, h is a whole number that varies from 0 to 2 and the sum of h+g does not exceed 3.
- 53. The composition of claim 32 wherein the silazane compound has the formula ##STR68## where R" and R'" are selected from the group consisting of hydrogen, monovalent hydrocarbon radicals and fluoroalkyl radicals an n is a whole number from 0 to 20.
- 54. The composition of claim 32 wherein the silazane compound is a cyclic silazane having the formula ##STR69## where R" and R'" are selected from the group consisting of hydrogen, monovalent hydrocarbon radicals and fluoroalkyl radicals and n is a whole number from 0 to 20.
- 55. A continuous process for preparing a stable, one package, substantially anhydrous 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:
- (1) passing through a static mixer
- (a) an organopolysiloxane wherein the silicon atom at each polymer chain end is hydroxy terminated;
- (b) a polyalkoxy crosslinking agent or an integrated cross-linker scavenger; and
- (c) an effective amount of an endcapping catalyst system comprising a Lewis acid and an amine selected from primary, secondary and tertiary amines;
- to produce a polyalkoxy terminated diorganopolysiloxane and
- (2) transmitting the polyalkoxy terminated diorganopolysiloxane through a devolatilizing extruder and mixing therein a condensation catalyst.
- 56. The process of claim 1 wherein the polyalkoxy crosslinking agent is also a scavenger for hydroxyl groups.
- 57. The process of claim 41 wherein the polyalkoxy crosslinking agent is also a scavenger for hydroxyl groups.
Parent Case Info
This application is a continuation of application Ser. No. 437,895, filed 11/01/82 now abandoned.
US Referenced Citations (10)
Continuations (1)
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Number |
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437895 |
Nov 1982 |
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