CA1136311A - Curable compositions and process - Google Patents
Curable compositions and processInfo
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- CA1136311A CA1136311A CA000330424A CA330424A CA1136311A CA 1136311 A CA1136311 A CA 1136311A CA 000330424 A CA000330424 A CA 000330424A CA 330424 A CA330424 A CA 330424A CA 1136311 A CA1136311 A CA 1136311A
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-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
- C08L83/04—Polysiloxanes
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
- C08G77/16—Polysiloxanes containing silicon bound to oxygen-containing groups to hydroxyl groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/22—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
- C08G77/24—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen halogen-containing groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/04—Polysiloxanes
- C08G77/22—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen
- C08G77/26—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen and oxygen nitrogen-containing groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
- C08G77/70—Siloxanes defined by use of the MDTQ nomenclature
Abstract
ABSTRACT OF THE DISCLOSURE
Self-bonding one-package room temperature vulcanizing silicone compositions, curable in the presence of moisture to rubbery materials, comprise (a) a silanol chain-stopped polydiorganopolysiloxane;
(b) a fluid polysiloxane having a high degree of tri- and/or tetrafunctionality;
(c) a silica filler;
(d) a cross-linking silane evolving relatively low volatility carboxylic acid fragments on hydrolysis; and (e) a highly reactive tin-containing silanol condensation catalyst.
Such compositions can be applied to a variety of difficulty bondable substrates. They are especially useful when subjected to hot oil environments, as in automobile engines. High temperature performance is markedly improved with the addition of an iron oxide thermal stabilizer.
Gasketed constructions and methods for forming them are also disclosed.
Self-bonding one-package room temperature vulcanizing silicone compositions, curable in the presence of moisture to rubbery materials, comprise (a) a silanol chain-stopped polydiorganopolysiloxane;
(b) a fluid polysiloxane having a high degree of tri- and/or tetrafunctionality;
(c) a silica filler;
(d) a cross-linking silane evolving relatively low volatility carboxylic acid fragments on hydrolysis; and (e) a highly reactive tin-containing silanol condensation catalyst.
Such compositions can be applied to a variety of difficulty bondable substrates. They are especially useful when subjected to hot oil environments, as in automobile engines. High temperature performance is markedly improved with the addition of an iron oxide thermal stabilizer.
Gasketed constructions and methods for forming them are also disclosed.
Description
~3~ r~ ~ 60-9I-184 Thls invention relates to curable silicone rubber compositions. More particularly, it relates to self-bonding, one-package room temperature ~ulcanizing (R'~V) compositions of a diorganosiloxane polymer, a highly functional polysiloxane, a filler, a cross-linking agent and a cross-linking catalyst. Thermal stab.ilizers can also be included.
U.S. Patent No. 3,065,194 - dated November 20, 1962 -Nitzsche et al disclose a family of silicone rubber compositions comprising an essentially anhydrous mixture of (1) a linear organosiloxane polymer having hydroxyl terminal groups, (2~ a polyfunctional organosilicone cross-linking agent, and 13) a metal salt, chelate, organometallic eompound, acid or base, which serves as a cross-linking catalyst. Such compositions vulcanize or cure to rubbery solids when exposed to moisture and this makes them uniquely useful, in that they can be amintained over a long period of time in a single container, e.g., sealed in caulking tubes, ready for use, but then the user can apply the material and bring it into contact with water or water vapor to cure it. Such compositions are useful in sealants, electrical insulation, eoatings, dental cement, caulking compounds, expansion joints, gaskets, shock absorbers, adhesives, and in many other forms.
Additional background teachings relating to one-paekage room temperature vuleanizing silieone compositions are to be found in U.S. Patent 3,035,016 - dated l~ay 15, 1962 - Bruner and in U.S. Patent No. 3,133,891 - dated May 19, 1964 - Ceyzeriat, who deal with one-package, moisture curable compositions eomprising the reaction products of aeyloxy-substituted silanes and hydroxylated siloxanes, the compositions curing with the liberation of acid fragments and and the curing being promoted with various agents, such as organic derivatives of tin. Also of interest is U.S. Patent ~3~ 60-SI-184 No. 3,161,614 - dated December 15, 1964 - Brown et al, who show a pre-reacted silanol end-stopped diorganopolysiloxane and cross-linker in combination with a cross-linking catalyst;
U.S. Patent No. 3,383,355 - dated May 14, 1968 - Cooper, who deals with the preparation of an alkoxy-terminated linear siloxane polymer using a neutral, finely divided solid catalyst, e.g., ~uller's earth; U.S. Patent No. 3,499,859 -dated March 10, 1970 - Matherly, who uses a hydrocarbonoxy end-blocked dioorganopolysiloxane and a metal-containing curing catalyst along with boron nitride; and U.S. Patent No.
3,542,901 - dated November 24, 1970 Cooper et al, who use a mixture of a linear siloxane having di- or tri-functional end-blocking units with a linear siloxane having chemically nonfunctional inert and end-blocking units on one end and di- or tri-functional end-blocking units on the other, and include a catalyst and a cross-linker. Additionally of interest are U.S A Patent No. 3,122,522 - dated February 25, 1964 - Brown et al, who combine organopolysiloxane intermediates containiny condensable cellosolvoxyl groups with 2Q a catalyst; U.S. Patent No. 3,170,894 - dated February 23, 1965 - Brown et al, who combine organopolysiloxzne intermediates containing condensable polyhydrocarbonoxy type radicals With a catalyst; and U.S. Patent No. 3,175~993 -dated March 30, 1965 - Weyenberg, who combines organopolysiloxane intermediate$ end-blocked with alkoxylated silcarbane groups with a catalyst. U.S. Patent No. 3,689,454 - dated September 5, 1972 - Smith et al and U.S. Patent No. 3,779,986 - dated December 18, 1973 - Smith et al, U.S. Patent No. 3,294,739 - dated December 27, 1966 -Weyenberg and U.S. Patent No. 3,334,067 - dated August 1, 1967 - ~eyenberg, and U.S. Patent No. 3,719,635 - dated March 6, 1973 - Clark et al also disclose one-package compositions.
~ !
U.S. Patent No. 3,065,194 - dated November 20, 1962 -Nitzsche et al disclose a family of silicone rubber compositions comprising an essentially anhydrous mixture of (1) a linear organosiloxane polymer having hydroxyl terminal groups, (2~ a polyfunctional organosilicone cross-linking agent, and 13) a metal salt, chelate, organometallic eompound, acid or base, which serves as a cross-linking catalyst. Such compositions vulcanize or cure to rubbery solids when exposed to moisture and this makes them uniquely useful, in that they can be amintained over a long period of time in a single container, e.g., sealed in caulking tubes, ready for use, but then the user can apply the material and bring it into contact with water or water vapor to cure it. Such compositions are useful in sealants, electrical insulation, eoatings, dental cement, caulking compounds, expansion joints, gaskets, shock absorbers, adhesives, and in many other forms.
Additional background teachings relating to one-paekage room temperature vuleanizing silieone compositions are to be found in U.S. Patent 3,035,016 - dated l~ay 15, 1962 - Bruner and in U.S. Patent No. 3,133,891 - dated May 19, 1964 - Ceyzeriat, who deal with one-package, moisture curable compositions eomprising the reaction products of aeyloxy-substituted silanes and hydroxylated siloxanes, the compositions curing with the liberation of acid fragments and and the curing being promoted with various agents, such as organic derivatives of tin. Also of interest is U.S. Patent ~3~ 60-SI-184 No. 3,161,614 - dated December 15, 1964 - Brown et al, who show a pre-reacted silanol end-stopped diorganopolysiloxane and cross-linker in combination with a cross-linking catalyst;
U.S. Patent No. 3,383,355 - dated May 14, 1968 - Cooper, who deals with the preparation of an alkoxy-terminated linear siloxane polymer using a neutral, finely divided solid catalyst, e.g., ~uller's earth; U.S. Patent No. 3,499,859 -dated March 10, 1970 - Matherly, who uses a hydrocarbonoxy end-blocked dioorganopolysiloxane and a metal-containing curing catalyst along with boron nitride; and U.S. Patent No.
3,542,901 - dated November 24, 1970 Cooper et al, who use a mixture of a linear siloxane having di- or tri-functional end-blocking units with a linear siloxane having chemically nonfunctional inert and end-blocking units on one end and di- or tri-functional end-blocking units on the other, and include a catalyst and a cross-linker. Additionally of interest are U.S A Patent No. 3,122,522 - dated February 25, 1964 - Brown et al, who combine organopolysiloxane intermediates containiny condensable cellosolvoxyl groups with 2Q a catalyst; U.S. Patent No. 3,170,894 - dated February 23, 1965 - Brown et al, who combine organopolysiloxzne intermediates containing condensable polyhydrocarbonoxy type radicals With a catalyst; and U.S. Patent No. 3,175~993 -dated March 30, 1965 - Weyenberg, who combines organopolysiloxane intermediate$ end-blocked with alkoxylated silcarbane groups with a catalyst. U.S. Patent No. 3,689,454 - dated September 5, 1972 - Smith et al and U.S. Patent No. 3,779,986 - dated December 18, 1973 - Smith et al, U.S. Patent No. 3,294,739 - dated December 27, 1966 -Weyenberg and U.S. Patent No. 3,334,067 - dated August 1, 1967 - ~eyenberg, and U.S. Patent No. 3,719,635 - dated March 6, 1973 - Clark et al also disclose one-package compositions.
~ !
- 2 -~L3~i3~.~l 6 o -SI-18 4 Applicant's U.S. Patent No. 3,382,205 - dated May 7, 1968 - Beers is also of intexest because it discloses one package systems, which are rnoisture curable and which further contain mono-, di- and trialkylpolysiloxanes, the latter fluids functioning as adhesion promoters and processing aids.
A special family of compositions is known to provide sealants with fairly high temperature resistance, but these are of limited utility as gasketing materials in the automotive industry in those instances where odor and corrosion can cause problems. By way of illustration, a composition comprising a silanol-terminated polydimethylsiloxane, methyltriacetoxysilane funed silica filler and dibutyltindilaurate, is presently used in most applications but is not entirely satisfactory in some areas because it eliminates acetic acid upon curing. This cure by-product is responsible for the objectionable odor and corrosion referred to above. The presently used compositions also tend to have a relatively high degree of adhesion at low temperatures so that, for example, if a new automobile engine has to be disassembled before being put in place and operated, it is difficult to repair without damaging such things as oil pans and valve coversO
It has now been found possible to provide a low-odor, non~corrosive fast curing one-component RTV composition which exhibits, after curing by moisture, excellent oil resistance and, especially with a thermal stabilizer, high temperature resistance properties. The composition also has a low degree of adhesion at room temperature, but this 3Q improves at high temperature, thereby accomplishing a good seal, e.g., when an automobile engine is started with gasket-ing produced from the instant composition. They are useful ~3~ 60-SI-184 in a variety of conventional applications, and particularly as gasket layers between metal surfaced parts.
According to the invention, there are provided fluid compositions stable under substantially anhydrous conditions and cuxable in the presence of moisture to a self-bonding thermally stable elastic solids resistant to hot hydrocarbon oils, said compositions comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
lo , 7 HO t---' Si-- tH
\ Rl ~ n wherein R and Rl are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about lO to 15,000;
(b) from 2 to 20 parts by weight of a fluid poly-siloxane containing a high degree of trifunctionality, tetrafunctionality or a mixture of tri- and tetrafunction-ality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from l to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2%
; by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely diyided silica filler;
(d~ from 3 to 10 parts by weight of a cross-linking silane of the formula:
_ 4 . . .
~ 60-SI-184 Rm Si (OR )4-m wherein R2 has the values defined from R and Rl hereinabove, R is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocaroyl and m has a value of 0 or l; and (e) from 0.01 to 10 parts by weight of a curing catalyst comprising an organic tin salt of an organic acid or a tin salt of an organic acid, said organic acid containing from 2 to 6 carbon atoms.
According to a preferred aspect of the invention, the composition will also include from 1 to 10 parts by weight of (f) a finely divided iron oxide thermal stabilizer.
These embodiments are especially useful at operating temperatures of 140C. and above.
According to another preferred aspect of this invention, there is provided a method of preparing a rubbery material which comprises preparing a composition as above defined under substantially anhydrous conditions and thereafter exposing the composition to moisture until it cures to a rubbery material. According to other aspects of the invention there are provided articles of manufacture comprising a plurality of metal surfaced pieces, each piece having at least a part of a surface portion in close proximity to another and a gasket layer therebetween, said gasket a composition as above defined;
as well as a method for producing such gasketed articles of manufacture. In preferred embodiments of this aspect, 3Q the compositions will also include an iron oxide thermal stabilizer.
The room temperature vulcanizing (RT~) compositions ~ 3~ 60-SI~184 of the present invention are prepared by simply admixing one or more of the silanol chain-stopped polyorganosiloxanes of the above formula, the highly trifunctional fluid , the iron oxide, the silica filler, the cross-linking silane compound and the silanol reactive tine salt. The base compound (excluding cross-linker, adhesion promoter, if present, and catalyst) are ordinarily compounded at elevated temperature to remove moisture and facilitate the wetting in of the ~iller.
Since the silanes tend to hydrolyze upon contact with moisture, care should be exercised to exclude moisture during the addition of the silane to the silanol chain-stopped polydiorganopolysiloxane. Likewise, care should be taken that the mixture of the silane, the silanol reactive tin salt catalyst, the silanol chain-stopped polydiorganosiloxane and the highly trifunctional siloxane fluid is maintained under substantially anhydrous conditions if it is desired to store the admixture for an extended period to time prior to conversion of the composition to the cured, solid, elastic silicone rubber state. On the other hand, if it is desired to permit the mixture to cure immediately, then no special precautions are necessary and the components can be mixed and placed in the form or shape in which it is desired for the composition to be cured.
So long as the specified ratios of ingredients are employed, a wide choice of components is available from which to prepare the compositions of this invention. These are described in many places, such as U.S. Patent 3,779,986 - dated December 18, 1973 - Smith et al, U.S. Patent 3,065,194 - dated November 20, 1962 -Nitzsche et al; U.S. Patent 3,294,739 - dated December 27, 1966 - Weyenberg; IJ.S. Patent No. 3,334,067 - dated ~3~r~ 60-SI-184 August 1, 1967 - Weyenberg; U.S. Patent No~ 3,3g2,205 -dated May 7, 1968 - Beers and U.S. Patent 3,708,467 dated January 2, 1973 Smith et alv With respect to the silanol chain-stopped polyorganosiloxane component (a~, these can b~ selected from those represented hy the formula:
R
~O - ~ ~'o ) ~ H
R
Wherei~n R and Rl are each organic radicals of up to 2Q, and prefexably, up to 8 carbon atoms seIected ,from hydrocarbyl, halohydxocarbyl and cyano lower alkyl,,and n is a number that yaries genexally from ~bout 10 to 15,0Q0, pxe.f,erably,,from 100 to about 3,0Q0, and, more preferably,.from 3~0 to 1,50Ø.
The silanol ch~in-stopped polydior~anosi~loxa,nes axe well kno~n in the art and include compositions containing dif,ferent R and Rl groups. For example, the R groups can be methyl~ while the. Rl gr~ups can be pheny~l and~or beta~cyano~
ethyl~ i~u~thermore, w~thin the scope of the defin~tion o~
polydiorganosiloxanes us~eful in this invention are copolymers of various types of diorganosiloxane units, such as silanol chain-stopped copolymers of dimethylsiloxane un~.ts,,diphenyl~
. siloxane units and methylphenylsiloxane units or, for example, copolymers of dimethylsiloxane units, methylphenylsiloxane units and methylvinylsiloxane units. Preferably, at least 50%
,~ of -the R and Rl groups of th.e silanol chain-stoppe~
polydiorganosiloxanes are alkyl, e.g., methyl groups.
In the aboye formula, R and R can be, for example, 3Q any groups illustrated in the foregoing patents.
The sil~nol chai~n~stopped polyd~organosiloxanes employed in the practice'of the present invention may vary ~36~ 9. 60SI-184 from low viscosity thin fluid to viscous gums, depending upon the value of n and the nature of the particular organic groups represcnted by R and R .
The viscosity of component (a) can vary broadly, e.g., in the range of 30 to 10,000,000 cps. at 25C.
Preferably, it will be in the range of 1,000 to 200,000 cps, and most preferably, from about 2,000 to 30,000 cps. at 25C.
The highly trifunctional polysiloxane component (b) can be made by means known to those skilled in this art.
For example, a mixture of (i) monoalkyl trichlorosilane;
(ii) dialkyldichlorosilane and (iii) alkyltrichlorosilane, silicone tetrachloride or a mixture thereof, at the appropriate mole ratio can be run into toluene and water to co-hydrolyæe them. Then the mixture can be heated, e.g., at about 60C. for a time, e.g., 3 hours sufficient to insure completion of the reaction. The oil phase is separated and neutralized, e.g., by washing with an aqueous solution of sodium carbonate or bicarbonate. After filtration to remove insolubles and devolatilization, e.g., by heating at about 140C. under a vacuum, e.g., about 2 mm, of mercury, the component (b) remains as the residue. Preferred for economy's sake is to keep the silicon-bonded hydroxyl content to less than 0.6~ by weight to minimize the viscosity of the final composition and to keep the cross-linker level to a minimum.
This is done by heating the product at 110C. in the presence of approximately one percent of sodium carbonate.
The water from the silanol condensation can conveniently be removed by azeotropic distillation, e.g., with toluene.
After removal of the toluene by distillation the product is filtered before use. U.S. Patent No. 3,382,205 - dated May 7, 1968 - Beers, is illustrative in this regard.
i ~ 60SI-184 Component (b) will generally comprise from 2 to 20 parts by weight per 100 parts of component (a) and preferably from about 5 to 15 parts per 100 parts by weight of the compos.ition .
Preferably, component (b) will have a viscosity in the range of 50 to 300 cps. at 25C. Preferably, also, in component (b) at least 50 percent of the alkyl substituents are methyl and the fluid comprises from 0.2 to 0.6 percent by weight of silanol. Especially preferably, the ; 10 monoalkylsiloxy units, siloxy units or mixed such units ; comprise about 35 to 45 mole percent, the trialkylsiloxy units comprise from 3 to 5 mole percent, the dialkylsiloxy units comprise from 45 to 67 mole percent, and the silanol content is about 0.2 to 0.5 percent by weight.
The silica component (c) is known in this art as a filler for silicone compositions. It is finely divided in form and preferably is of the type known as fumed silica.
Preferably, it should have a surface area of about 200 sq.
meters/gram. A preferred form will be an organosilicone --or silazane -- treated silica such as dimethylcyclic siloxane-treated silica and as described in U.S. patent No. 3,004,859 -dated October 17, 1961 - Lichtenwalner; U.S. patent
A special family of compositions is known to provide sealants with fairly high temperature resistance, but these are of limited utility as gasketing materials in the automotive industry in those instances where odor and corrosion can cause problems. By way of illustration, a composition comprising a silanol-terminated polydimethylsiloxane, methyltriacetoxysilane funed silica filler and dibutyltindilaurate, is presently used in most applications but is not entirely satisfactory in some areas because it eliminates acetic acid upon curing. This cure by-product is responsible for the objectionable odor and corrosion referred to above. The presently used compositions also tend to have a relatively high degree of adhesion at low temperatures so that, for example, if a new automobile engine has to be disassembled before being put in place and operated, it is difficult to repair without damaging such things as oil pans and valve coversO
It has now been found possible to provide a low-odor, non~corrosive fast curing one-component RTV composition which exhibits, after curing by moisture, excellent oil resistance and, especially with a thermal stabilizer, high temperature resistance properties. The composition also has a low degree of adhesion at room temperature, but this 3Q improves at high temperature, thereby accomplishing a good seal, e.g., when an automobile engine is started with gasket-ing produced from the instant composition. They are useful ~3~ 60-SI-184 in a variety of conventional applications, and particularly as gasket layers between metal surfaced parts.
According to the invention, there are provided fluid compositions stable under substantially anhydrous conditions and cuxable in the presence of moisture to a self-bonding thermally stable elastic solids resistant to hot hydrocarbon oils, said compositions comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
lo , 7 HO t---' Si-- tH
\ Rl ~ n wherein R and Rl are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about lO to 15,000;
(b) from 2 to 20 parts by weight of a fluid poly-siloxane containing a high degree of trifunctionality, tetrafunctionality or a mixture of tri- and tetrafunction-ality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from l to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2%
; by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely diyided silica filler;
(d~ from 3 to 10 parts by weight of a cross-linking silane of the formula:
_ 4 . . .
~ 60-SI-184 Rm Si (OR )4-m wherein R2 has the values defined from R and Rl hereinabove, R is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocaroyl and m has a value of 0 or l; and (e) from 0.01 to 10 parts by weight of a curing catalyst comprising an organic tin salt of an organic acid or a tin salt of an organic acid, said organic acid containing from 2 to 6 carbon atoms.
According to a preferred aspect of the invention, the composition will also include from 1 to 10 parts by weight of (f) a finely divided iron oxide thermal stabilizer.
These embodiments are especially useful at operating temperatures of 140C. and above.
According to another preferred aspect of this invention, there is provided a method of preparing a rubbery material which comprises preparing a composition as above defined under substantially anhydrous conditions and thereafter exposing the composition to moisture until it cures to a rubbery material. According to other aspects of the invention there are provided articles of manufacture comprising a plurality of metal surfaced pieces, each piece having at least a part of a surface portion in close proximity to another and a gasket layer therebetween, said gasket a composition as above defined;
as well as a method for producing such gasketed articles of manufacture. In preferred embodiments of this aspect, 3Q the compositions will also include an iron oxide thermal stabilizer.
The room temperature vulcanizing (RT~) compositions ~ 3~ 60-SI~184 of the present invention are prepared by simply admixing one or more of the silanol chain-stopped polyorganosiloxanes of the above formula, the highly trifunctional fluid , the iron oxide, the silica filler, the cross-linking silane compound and the silanol reactive tine salt. The base compound (excluding cross-linker, adhesion promoter, if present, and catalyst) are ordinarily compounded at elevated temperature to remove moisture and facilitate the wetting in of the ~iller.
Since the silanes tend to hydrolyze upon contact with moisture, care should be exercised to exclude moisture during the addition of the silane to the silanol chain-stopped polydiorganopolysiloxane. Likewise, care should be taken that the mixture of the silane, the silanol reactive tin salt catalyst, the silanol chain-stopped polydiorganosiloxane and the highly trifunctional siloxane fluid is maintained under substantially anhydrous conditions if it is desired to store the admixture for an extended period to time prior to conversion of the composition to the cured, solid, elastic silicone rubber state. On the other hand, if it is desired to permit the mixture to cure immediately, then no special precautions are necessary and the components can be mixed and placed in the form or shape in which it is desired for the composition to be cured.
So long as the specified ratios of ingredients are employed, a wide choice of components is available from which to prepare the compositions of this invention. These are described in many places, such as U.S. Patent 3,779,986 - dated December 18, 1973 - Smith et al, U.S. Patent 3,065,194 - dated November 20, 1962 -Nitzsche et al; U.S. Patent 3,294,739 - dated December 27, 1966 - Weyenberg; IJ.S. Patent No. 3,334,067 - dated ~3~r~ 60-SI-184 August 1, 1967 - Weyenberg; U.S. Patent No~ 3,3g2,205 -dated May 7, 1968 - Beers and U.S. Patent 3,708,467 dated January 2, 1973 Smith et alv With respect to the silanol chain-stopped polyorganosiloxane component (a~, these can b~ selected from those represented hy the formula:
R
~O - ~ ~'o ) ~ H
R
Wherei~n R and Rl are each organic radicals of up to 2Q, and prefexably, up to 8 carbon atoms seIected ,from hydrocarbyl, halohydxocarbyl and cyano lower alkyl,,and n is a number that yaries genexally from ~bout 10 to 15,0Q0, pxe.f,erably,,from 100 to about 3,0Q0, and, more preferably,.from 3~0 to 1,50Ø.
The silanol ch~in-stopped polydior~anosi~loxa,nes axe well kno~n in the art and include compositions containing dif,ferent R and Rl groups. For example, the R groups can be methyl~ while the. Rl gr~ups can be pheny~l and~or beta~cyano~
ethyl~ i~u~thermore, w~thin the scope of the defin~tion o~
polydiorganosiloxanes us~eful in this invention are copolymers of various types of diorganosiloxane units, such as silanol chain-stopped copolymers of dimethylsiloxane un~.ts,,diphenyl~
. siloxane units and methylphenylsiloxane units or, for example, copolymers of dimethylsiloxane units, methylphenylsiloxane units and methylvinylsiloxane units. Preferably, at least 50%
,~ of -the R and Rl groups of th.e silanol chain-stoppe~
polydiorganosiloxanes are alkyl, e.g., methyl groups.
In the aboye formula, R and R can be, for example, 3Q any groups illustrated in the foregoing patents.
The sil~nol chai~n~stopped polyd~organosiloxanes employed in the practice'of the present invention may vary ~36~ 9. 60SI-184 from low viscosity thin fluid to viscous gums, depending upon the value of n and the nature of the particular organic groups represcnted by R and R .
The viscosity of component (a) can vary broadly, e.g., in the range of 30 to 10,000,000 cps. at 25C.
Preferably, it will be in the range of 1,000 to 200,000 cps, and most preferably, from about 2,000 to 30,000 cps. at 25C.
The highly trifunctional polysiloxane component (b) can be made by means known to those skilled in this art.
For example, a mixture of (i) monoalkyl trichlorosilane;
(ii) dialkyldichlorosilane and (iii) alkyltrichlorosilane, silicone tetrachloride or a mixture thereof, at the appropriate mole ratio can be run into toluene and water to co-hydrolyæe them. Then the mixture can be heated, e.g., at about 60C. for a time, e.g., 3 hours sufficient to insure completion of the reaction. The oil phase is separated and neutralized, e.g., by washing with an aqueous solution of sodium carbonate or bicarbonate. After filtration to remove insolubles and devolatilization, e.g., by heating at about 140C. under a vacuum, e.g., about 2 mm, of mercury, the component (b) remains as the residue. Preferred for economy's sake is to keep the silicon-bonded hydroxyl content to less than 0.6~ by weight to minimize the viscosity of the final composition and to keep the cross-linker level to a minimum.
This is done by heating the product at 110C. in the presence of approximately one percent of sodium carbonate.
The water from the silanol condensation can conveniently be removed by azeotropic distillation, e.g., with toluene.
After removal of the toluene by distillation the product is filtered before use. U.S. Patent No. 3,382,205 - dated May 7, 1968 - Beers, is illustrative in this regard.
i ~ 60SI-184 Component (b) will generally comprise from 2 to 20 parts by weight per 100 parts of component (a) and preferably from about 5 to 15 parts per 100 parts by weight of the compos.ition .
Preferably, component (b) will have a viscosity in the range of 50 to 300 cps. at 25C. Preferably, also, in component (b) at least 50 percent of the alkyl substituents are methyl and the fluid comprises from 0.2 to 0.6 percent by weight of silanol. Especially preferably, the ; 10 monoalkylsiloxy units, siloxy units or mixed such units ; comprise about 35 to 45 mole percent, the trialkylsiloxy units comprise from 3 to 5 mole percent, the dialkylsiloxy units comprise from 45 to 67 mole percent, and the silanol content is about 0.2 to 0.5 percent by weight.
The silica component (c) is known in this art as a filler for silicone compositions. It is finely divided in form and preferably is of the type known as fumed silica.
Preferably, it should have a surface area of about 200 sq.
meters/gram. A preferred form will be an organosilicone --or silazane -- treated silica such as dimethylcyclic siloxane-treated silica and as described in U.S. patent No. 3,004,859 -dated October 17, 1961 - Lichtenwalner; U.S. patent
3,635,743 - dated January 18, 1972 - Smith. The silica filler (c) is generally employed in amounts of from 10 to 100, preferably from 15 to about 40 parts by weight per 100 parts by weight of component (a), and preferably from 20 to 30 parts by weight per 100 parts by weight of the composition.
The silane cross-linking agent (d) of the formula:
Rm Si (OR )4 m _ g _ ~
3~ 6 o - s I -1~3 4 is one which has values for R which are, independently, the same as those defined for R and Rl above. R3 should contain between 6 and 30 carbon atoms to preclude ~ormation of odorous, corrosive by-products during the curing reaction.
Illustrative of such silanes useful in the RTV
compositions of this invention are the following:
CH3Si(oCo(CH2)~CH3)3 Si(oCo(CH2)4CH3)~
1^ ~ Si(OCO(CH2)4CH3)3 CH3(CH2)6CH2Si(oCo(CH2)4CH3)3 CF3(CH2)3Si(C(CH2)4CH3)3 NCCH2CH2Si(oCo(CH2)4CH3)3 CH3si(OCOCH(C2H5)(CH2)CH3)3 ~) , The silanes are well known in the art and can be made by techniques disclosed, for example, in U.S. Patent No.
3,382,205 - dated May 7, 1968 - Beers.
Pre~erably in cross-linking agent (d), m has a value of 1 and the preferred silanes are methyl trist2-ethylhexanoxy)-silane and methyl tris(benzoxy) silane. The silane is generally used in amounts of from 3 to 10 parts by weight, based on 100 parts by weight of component (a) and preferably from 5 to 7 parts by weight, same basis.
With respect to silanol reactive tin catalyst component (e), in general either an organic tin salt of an organic acid or a tin salt of an organic acid can be used, although the rormer is preferred. An organic acid carbon content of between 2 and 6 provides the best combination of ~3~ 60-SI-184 cure ra-te and ultimate properties. The organic element of the organo tin salt can be one or two alkyl radicals, e.g., of from 2 to 6 carbon atoms, e.g., monobutyl or dibutyl and the organic acid radical can have from 2 to 6 carbon atoms. Examples are tin hexanoate, dibutyltin hexanoate, dibutyltin diacetate, dibutyltin adipate, dibutyltin dipropionate, dibutyLtin dibutyrate, monobutyltin triacetate, and the like. These are either commercially available or can be made by those skilled in this art.
Preferred is dibutyltin diacetate.
The catalyst is generally present in amounts between 0.01 and lO.0 parts by weight per lO0 parts by weight of component (a), and preferably between 0.02 and 5.0 parts by weight. Expecially preferably, from about 0.05 to about 0.15 parts by weight of catalyst will be used for each lO0 parts by weight of total composition.
The optional iron oxide thermal stabilizer component (f) is an item of commerce, conventionally used and widely available in finely divided form for use as a filler in plastic compositions. Preferably, the iron oxide has a p~I
in the range of 6.0 to 7.5, to achieve maximum thexmal and shelf-aging stability. The amount used will be in the range of l to lO parts by weight, based on lO0 parts by weight of component (a) and, preferably, from 3 to 6 parts by weight based on lO0 parts by weight of the total composition.
In preferred embodiments, the present compositions can also optionally include an adhesion promoter, e.g., from 0.2 to 2 parts of such promoter per lO0 parts of component (a~. These will generally be nitrogen-containing compounds, e.g., a class of promoters of the formula:
~13~ 60-S~-184 \ G
(R O)3_bR b - Si R - ~ N
~C ~C
wherein G is a (RllO)3 b-RlOb--Si --R9 radical, styryl, vinyl, allyl, chloroallyl or cyclohexenyl radical or a R10 radical, as hexeinafter defined; R9 is a divalent radical selected from alkylenearylene, alkylene, cycloxyene and halosubstituted such divalent radicals; R10 is a radical of up to 8 carbon atoms selected from hydrocarbyl or halohydrocarbyl and R 1 is a radical of the type defined for R and also cyano lower alkyl; and b is 0 to 3.
Such adhesion promoters are disclosed in U.S.
Patent 3,517,001 - dated June 23, 1970 - Berger. The preferred such promoters are 1,3,5-tris-trimethoxysily-lpropylisocyanate and bis-l, 3-trimethoxysilypropylisocy-anurate, the former being most preferred.
Although any conventional adhesion promotion can be used, special mention is also made of an adhesion promoter known as glycidoxypropyltrimethoxysilane.
Additional conventional ingxedients can also be included, such as flame retardants, stabilizing agents, pigments, and the like.
The compositions of this invention are stable in the absence of moisture~ Consequently, they can be stored for prolonged periods of time without deleterious effect.
; During this period of storage, no significant change occurs ~ 60-SI-184 in the physical properties of the room temperature vulcanizing compositions. This is especially advantageous commercially because it insures that once the composition is prepared with a given consistency and cure time, neither change significantly on storage. Storaye stability is one of the characteristics which makes the present compositions valuable in one-package systems.
The compositions prepared by mixing the catalyst and the silane with the silanol chian-stopped polydiorganosiloxane and other ingredients under anhydrous conditions can be used without further modification in many sealing, caulking and coating applications merely by placing the compositions in the desired location and permitting them to cure upon exposure to the moisture present in the atmosphere. Upon such exposure, even after previous storage for many months, a "skin" will form on the present compositions within a relatively short time, e.g., from 10 minutes to about 8 hours, and they will cure to a rubbery state within from a few hours to several days, at room temperature, e.g., from 18 to 25 C.
Where the compositions of the present invention contain ingredients other than the silanol-terminated polydiorganosiloxane, the tri- and/or tetrafunctional siloxane fluid, the silane cross-linker and the tin catalyst, these additional ingredients can be added in any desired ; manner. However, for ease in manufacturing, it is often most convenient to form a "base" blend of all of the components except the silane, the tin catalyst and, if present, the adhesion promoter, then to remove moisture from the base 3Q blend, e.g., by maintaining it under vacuum at elevated temperature, e.g., 50-100c., and thereafter to add the silane, the tin catalyst and, optionally, the adhesion 3~ 60-SI-184 promoter, just prior to packaging in containers protected from moisture.
The compositions of this invention are particularly suitable for caulking and sealing applications where excellent adhesion to a variety oE substrates is important. For example, the compositions are useful in household and industrial caulking and sealing in buildings, factories, automobiles, and the like, and with suhstrates such as masonry, glass, plastic, metal, wood, and the like.
There is little or no tendency for the present compositions to corrode sensitive substrates, e.g., metals, such as copper and brass. They are also advantageous in having excellent rates of application, making them readily suitable for application from conventional caulkers under standard conditions.
The following examples are illustrative only and should not be construed as limiting the invention. The terms M, D, t and Q are art-recognized designations for, respectively, M = monofunctional organosiloxane unit, R3SiOl/2;
D = difunctional organosiloxane unit, R2SiO2/2;
T = trifunctional organosiloxane unit 3/2; and Q = tetrafunctional organosiloxane unit, sio4/2 A base compound is prepared comprising the following (by weight):
6000 cps. viscosity (25C.) silanol-terminated polydimethylsiloxane 100 parts ~ 60-SI-184 a M, D, T, OH silicone oil containing approximately 4 mole % trimethyl-siloxy, 56 mole % dimethylsiloxy;
40 mole % methylsiloxy groups and 0.5 weight % OH 10 parts Iron oxide, pH 6.0 - 7.5 6 parts Dimethylsiloxane-treated fumed silica having a surface area of approxi-mately 200 sq. meters/g. 25 parts A catalyst mixture is prepared comprising the following (by weight):
Methyl tris-2-ethylhexanoxy silane (cross-linker) 6 parts Glycidoxypropyltrimethoxysilane tadhesion promoter) 0.25 parts Dibutyltindiacetate 0.06 parts One hundred parts of the base compound is mixed together with the catalyst mixture in the absence of air ; and atmospheric moisture and packaged in 3 oz. metal containers. Test sheets are then prepared and allowed to cure at 77 + 2F. and 50 + 5% relative humidity ~or 3 days.
The following test results are obtained:
Shore A hardness 42 Tensile strength, psi 500 Elongation % 380 ; COMPARATIVE EXAMPLE A
A base compound is prepared comprising the following (by weight~:
6,000 cps. viscosity, silanol terminated polydimethylsiloxane 100 parts Octamethyltetrasiloxane-treated fumed silica having a surface :
~1 ~3~
area of approximately 200m2/gm.
(filler) 25 parts IrQn oxide 6 parts A catalyst mixture is prepared comprising the following (by weight):
Methyltrist2-ethylhex.oxy)silane 6 parts Dibutyltin diacetate (catalyst) 0.06 parts Glycidoxypropyltrimethoxysilane 0.25 parts (adhesion promoter) On hundred parts of the base compound is mixed together with the catalyst mixture in the absence of air and atmospheric moisture. The anhydrous material is cured and tested as described in Example 1. The following test results are obtained:
Shore A hardness 43 Tensile strength, psi 630 ' Elongation, ~ 370 To determine the relative resistances to hot hydro-carbon oil, cured specimens of Example 1 and Comparative Example A were suspended in 5W-30 motor oil at 300 F. for various periods of time, and the hardness tensile strength, elongation and volume swells were measured. The results are set forth in the following Table:
Table. Oil Immersion Resistance Properties ~ Properties (after immersion) :~ 5~-30 Oil at 300F. 72 hours_ Example 1 Comparison Example A
Shore A, hardness 16 18 Tensile, psi 100 140 Elongation, % 300 320 Volume swelll % 37 42 ~3G~ 60-SI-184 168 hours Example 1 Comparison Examplë A
Shore A, hardness 19 18 Tensile, psi 190 190 Elongation, % 320 320 Volume swell, % 37 43 336 hours Example 1 Comparison Example A
Shore A, hardness 17 12 Tensile, psi 200 70 Elongation, % 330 240 Volume swell, % 36 40 504 hours Example l Comparison Example A
Shore A, hardness 17 9 Tensile, psi 175 40 Elongation, % 300 250 Volume swell, % 36 40 It can be seen that the composition of Example 1 is more resistant to reversion than the composition of the comparative example. This illustrates the superiority of the highly trifunctional (T-containing) component of the compositions of this invention.
The procedure of Example 1 is repeated, substituting 1.5 parts by weight of 1,3,5-tris-trimethoxysi:Lylpropylisocyanurate as the adhesion promoter.
The cured product had the following properties:
Shore A hardness 46 Tensile strength, psi 620 Elongation,% 400 ~ 60~SI-18~
other modifications can be made. For example, the iron oxide thermal stabilizer can be omitted. Inst~ad of methyl tris(2-ethylhexoxy)silane, methyl tris (benzoxy) silane can be used as a cross-linker. However, it irlstead of the M,D,T fluid employed in Example 1, there is used a M,D,T fluid containing a substantially lower T level, the oil resistance de-teriorates:
COMPARATI~E EXAMPLE B
A base compound is prepared comprising the following composition:
6,000 cps. viscosity (25C) silanol terminated polydimethyl siloxane 100 parts A M,D,T,OH silicone oil containing approximately 5 mole % trimethylsiloxy, 20 mole % monomethylsiloxy,75 mole % di-methylsiloxy and approximately 0.5 weight % OH 10 parts Iron oxide, pH 6.0 - 7.5 6 parts Dimethylsiloxane-treated fumed silica 2Q having a surface area of 200 m2/g 25 parts The same catalyst mixture as that utilized in Example 1 ~as incorporated in the above base compound in the absence of moisture at the exact same percentage composition.
The following room temperature test results were obtained:
Shore hardness 35 Tensile, psi 600 Elongation, % 420 To determine its relative resistance to hot hydrocarbon oil cured specimens wer:e suspended in 5W-30 oil at 300F. After 72 hours under these environmental 1~3~ 60-SI-18~
conditions the hardness, tensil strength, elongation and volume swell were measured. The -tensile strength was so low that the test was discontinued. The data shown below obviously illustrate the advantages of the high T
containing oil used in Example 1. The results are set forth below:
72 hrs./300 F in 5W-30 -Shore A, Hardness 9 Tensile, psi 40 Elongation, % 2~0 Swell, % 36 A gasket is formed between two corrosion-susceptible metal workpieces by spreading a coating of the composition of Example 1 on a surface of the first piece and bringing the surface of the second piece into close proximity thereto, thereby forming a sandwich with the composition therebetween. The composition is cured to a rubbery state without releasing any substantial amount of corrosive materials and odorous materials by exposing the structure to a moist atmosphere at about 75F. until a strong bond is formed.
Obviously, other modifications and variations of ; the present invention are possible in the light of the above teachings. It is, therefore, to be understood that changes may be made in the particular embodiments of this invention which are within the full intended scope of the invention as defined by the appended claims.
7~ ~ 60SI-184 SUPPLEMENTAR~ DISCLOSURE
It has further been discovered that an organic acid carbon content of between 2 and 12 provides the best combination of cure rate and ultimate properties. Also, the organic element of the organo tin salt can be one or two alkyl radicals, e.g.
from 1 or 2 to 6 carbon atoms, e.g.~ dimethyl~ and the organic acid radical can have from 2 to 6 or even 12 carbon atoms.
Reactivity is enhanced with higher acid radicals if the shortest alkyl radicals are present. In addition to those examples disclosed in the principal disclosure, dimethyltin bisneodecanoate may be used. Of these, dibutyltin diacetate and dimethyltin bisneodecanoate are preferred.
The following example is illustrative onl~, and should not be construed as limiting the invention.
Example 4 The procedure of Example 1, of the principal disclosure, is repeated, substituting for the dibutyltin diacetate catalyst, 0.1 parts of dimethyltin bis-neodecanoate (Witco UL-28). A
composition according to this invention is obtained.
,
The silane cross-linking agent (d) of the formula:
Rm Si (OR )4 m _ g _ ~
3~ 6 o - s I -1~3 4 is one which has values for R which are, independently, the same as those defined for R and Rl above. R3 should contain between 6 and 30 carbon atoms to preclude ~ormation of odorous, corrosive by-products during the curing reaction.
Illustrative of such silanes useful in the RTV
compositions of this invention are the following:
CH3Si(oCo(CH2)~CH3)3 Si(oCo(CH2)4CH3)~
1^ ~ Si(OCO(CH2)4CH3)3 CH3(CH2)6CH2Si(oCo(CH2)4CH3)3 CF3(CH2)3Si(C(CH2)4CH3)3 NCCH2CH2Si(oCo(CH2)4CH3)3 CH3si(OCOCH(C2H5)(CH2)CH3)3 ~) , The silanes are well known in the art and can be made by techniques disclosed, for example, in U.S. Patent No.
3,382,205 - dated May 7, 1968 - Beers.
Pre~erably in cross-linking agent (d), m has a value of 1 and the preferred silanes are methyl trist2-ethylhexanoxy)-silane and methyl tris(benzoxy) silane. The silane is generally used in amounts of from 3 to 10 parts by weight, based on 100 parts by weight of component (a) and preferably from 5 to 7 parts by weight, same basis.
With respect to silanol reactive tin catalyst component (e), in general either an organic tin salt of an organic acid or a tin salt of an organic acid can be used, although the rormer is preferred. An organic acid carbon content of between 2 and 6 provides the best combination of ~3~ 60-SI-184 cure ra-te and ultimate properties. The organic element of the organo tin salt can be one or two alkyl radicals, e.g., of from 2 to 6 carbon atoms, e.g., monobutyl or dibutyl and the organic acid radical can have from 2 to 6 carbon atoms. Examples are tin hexanoate, dibutyltin hexanoate, dibutyltin diacetate, dibutyltin adipate, dibutyltin dipropionate, dibutyLtin dibutyrate, monobutyltin triacetate, and the like. These are either commercially available or can be made by those skilled in this art.
Preferred is dibutyltin diacetate.
The catalyst is generally present in amounts between 0.01 and lO.0 parts by weight per lO0 parts by weight of component (a), and preferably between 0.02 and 5.0 parts by weight. Expecially preferably, from about 0.05 to about 0.15 parts by weight of catalyst will be used for each lO0 parts by weight of total composition.
The optional iron oxide thermal stabilizer component (f) is an item of commerce, conventionally used and widely available in finely divided form for use as a filler in plastic compositions. Preferably, the iron oxide has a p~I
in the range of 6.0 to 7.5, to achieve maximum thexmal and shelf-aging stability. The amount used will be in the range of l to lO parts by weight, based on lO0 parts by weight of component (a) and, preferably, from 3 to 6 parts by weight based on lO0 parts by weight of the total composition.
In preferred embodiments, the present compositions can also optionally include an adhesion promoter, e.g., from 0.2 to 2 parts of such promoter per lO0 parts of component (a~. These will generally be nitrogen-containing compounds, e.g., a class of promoters of the formula:
~13~ 60-S~-184 \ G
(R O)3_bR b - Si R - ~ N
~C ~C
wherein G is a (RllO)3 b-RlOb--Si --R9 radical, styryl, vinyl, allyl, chloroallyl or cyclohexenyl radical or a R10 radical, as hexeinafter defined; R9 is a divalent radical selected from alkylenearylene, alkylene, cycloxyene and halosubstituted such divalent radicals; R10 is a radical of up to 8 carbon atoms selected from hydrocarbyl or halohydrocarbyl and R 1 is a radical of the type defined for R and also cyano lower alkyl; and b is 0 to 3.
Such adhesion promoters are disclosed in U.S.
Patent 3,517,001 - dated June 23, 1970 - Berger. The preferred such promoters are 1,3,5-tris-trimethoxysily-lpropylisocyanate and bis-l, 3-trimethoxysilypropylisocy-anurate, the former being most preferred.
Although any conventional adhesion promotion can be used, special mention is also made of an adhesion promoter known as glycidoxypropyltrimethoxysilane.
Additional conventional ingxedients can also be included, such as flame retardants, stabilizing agents, pigments, and the like.
The compositions of this invention are stable in the absence of moisture~ Consequently, they can be stored for prolonged periods of time without deleterious effect.
; During this period of storage, no significant change occurs ~ 60-SI-184 in the physical properties of the room temperature vulcanizing compositions. This is especially advantageous commercially because it insures that once the composition is prepared with a given consistency and cure time, neither change significantly on storage. Storaye stability is one of the characteristics which makes the present compositions valuable in one-package systems.
The compositions prepared by mixing the catalyst and the silane with the silanol chian-stopped polydiorganosiloxane and other ingredients under anhydrous conditions can be used without further modification in many sealing, caulking and coating applications merely by placing the compositions in the desired location and permitting them to cure upon exposure to the moisture present in the atmosphere. Upon such exposure, even after previous storage for many months, a "skin" will form on the present compositions within a relatively short time, e.g., from 10 minutes to about 8 hours, and they will cure to a rubbery state within from a few hours to several days, at room temperature, e.g., from 18 to 25 C.
Where the compositions of the present invention contain ingredients other than the silanol-terminated polydiorganosiloxane, the tri- and/or tetrafunctional siloxane fluid, the silane cross-linker and the tin catalyst, these additional ingredients can be added in any desired ; manner. However, for ease in manufacturing, it is often most convenient to form a "base" blend of all of the components except the silane, the tin catalyst and, if present, the adhesion promoter, then to remove moisture from the base 3Q blend, e.g., by maintaining it under vacuum at elevated temperature, e.g., 50-100c., and thereafter to add the silane, the tin catalyst and, optionally, the adhesion 3~ 60-SI-184 promoter, just prior to packaging in containers protected from moisture.
The compositions of this invention are particularly suitable for caulking and sealing applications where excellent adhesion to a variety oE substrates is important. For example, the compositions are useful in household and industrial caulking and sealing in buildings, factories, automobiles, and the like, and with suhstrates such as masonry, glass, plastic, metal, wood, and the like.
There is little or no tendency for the present compositions to corrode sensitive substrates, e.g., metals, such as copper and brass. They are also advantageous in having excellent rates of application, making them readily suitable for application from conventional caulkers under standard conditions.
The following examples are illustrative only and should not be construed as limiting the invention. The terms M, D, t and Q are art-recognized designations for, respectively, M = monofunctional organosiloxane unit, R3SiOl/2;
D = difunctional organosiloxane unit, R2SiO2/2;
T = trifunctional organosiloxane unit 3/2; and Q = tetrafunctional organosiloxane unit, sio4/2 A base compound is prepared comprising the following (by weight):
6000 cps. viscosity (25C.) silanol-terminated polydimethylsiloxane 100 parts ~ 60-SI-184 a M, D, T, OH silicone oil containing approximately 4 mole % trimethyl-siloxy, 56 mole % dimethylsiloxy;
40 mole % methylsiloxy groups and 0.5 weight % OH 10 parts Iron oxide, pH 6.0 - 7.5 6 parts Dimethylsiloxane-treated fumed silica having a surface area of approxi-mately 200 sq. meters/g. 25 parts A catalyst mixture is prepared comprising the following (by weight):
Methyl tris-2-ethylhexanoxy silane (cross-linker) 6 parts Glycidoxypropyltrimethoxysilane tadhesion promoter) 0.25 parts Dibutyltindiacetate 0.06 parts One hundred parts of the base compound is mixed together with the catalyst mixture in the absence of air ; and atmospheric moisture and packaged in 3 oz. metal containers. Test sheets are then prepared and allowed to cure at 77 + 2F. and 50 + 5% relative humidity ~or 3 days.
The following test results are obtained:
Shore A hardness 42 Tensile strength, psi 500 Elongation % 380 ; COMPARATIVE EXAMPLE A
A base compound is prepared comprising the following (by weight~:
6,000 cps. viscosity, silanol terminated polydimethylsiloxane 100 parts Octamethyltetrasiloxane-treated fumed silica having a surface :
~1 ~3~
area of approximately 200m2/gm.
(filler) 25 parts IrQn oxide 6 parts A catalyst mixture is prepared comprising the following (by weight):
Methyltrist2-ethylhex.oxy)silane 6 parts Dibutyltin diacetate (catalyst) 0.06 parts Glycidoxypropyltrimethoxysilane 0.25 parts (adhesion promoter) On hundred parts of the base compound is mixed together with the catalyst mixture in the absence of air and atmospheric moisture. The anhydrous material is cured and tested as described in Example 1. The following test results are obtained:
Shore A hardness 43 Tensile strength, psi 630 ' Elongation, ~ 370 To determine the relative resistances to hot hydro-carbon oil, cured specimens of Example 1 and Comparative Example A were suspended in 5W-30 motor oil at 300 F. for various periods of time, and the hardness tensile strength, elongation and volume swells were measured. The results are set forth in the following Table:
Table. Oil Immersion Resistance Properties ~ Properties (after immersion) :~ 5~-30 Oil at 300F. 72 hours_ Example 1 Comparison Example A
Shore A, hardness 16 18 Tensile, psi 100 140 Elongation, % 300 320 Volume swelll % 37 42 ~3G~ 60-SI-184 168 hours Example 1 Comparison Examplë A
Shore A, hardness 19 18 Tensile, psi 190 190 Elongation, % 320 320 Volume swell, % 37 43 336 hours Example 1 Comparison Example A
Shore A, hardness 17 12 Tensile, psi 200 70 Elongation, % 330 240 Volume swell, % 36 40 504 hours Example l Comparison Example A
Shore A, hardness 17 9 Tensile, psi 175 40 Elongation, % 300 250 Volume swell, % 36 40 It can be seen that the composition of Example 1 is more resistant to reversion than the composition of the comparative example. This illustrates the superiority of the highly trifunctional (T-containing) component of the compositions of this invention.
The procedure of Example 1 is repeated, substituting 1.5 parts by weight of 1,3,5-tris-trimethoxysi:Lylpropylisocyanurate as the adhesion promoter.
The cured product had the following properties:
Shore A hardness 46 Tensile strength, psi 620 Elongation,% 400 ~ 60~SI-18~
other modifications can be made. For example, the iron oxide thermal stabilizer can be omitted. Inst~ad of methyl tris(2-ethylhexoxy)silane, methyl tris (benzoxy) silane can be used as a cross-linker. However, it irlstead of the M,D,T fluid employed in Example 1, there is used a M,D,T fluid containing a substantially lower T level, the oil resistance de-teriorates:
COMPARATI~E EXAMPLE B
A base compound is prepared comprising the following composition:
6,000 cps. viscosity (25C) silanol terminated polydimethyl siloxane 100 parts A M,D,T,OH silicone oil containing approximately 5 mole % trimethylsiloxy, 20 mole % monomethylsiloxy,75 mole % di-methylsiloxy and approximately 0.5 weight % OH 10 parts Iron oxide, pH 6.0 - 7.5 6 parts Dimethylsiloxane-treated fumed silica 2Q having a surface area of 200 m2/g 25 parts The same catalyst mixture as that utilized in Example 1 ~as incorporated in the above base compound in the absence of moisture at the exact same percentage composition.
The following room temperature test results were obtained:
Shore hardness 35 Tensile, psi 600 Elongation, % 420 To determine its relative resistance to hot hydrocarbon oil cured specimens wer:e suspended in 5W-30 oil at 300F. After 72 hours under these environmental 1~3~ 60-SI-18~
conditions the hardness, tensil strength, elongation and volume swell were measured. The -tensile strength was so low that the test was discontinued. The data shown below obviously illustrate the advantages of the high T
containing oil used in Example 1. The results are set forth below:
72 hrs./300 F in 5W-30 -Shore A, Hardness 9 Tensile, psi 40 Elongation, % 2~0 Swell, % 36 A gasket is formed between two corrosion-susceptible metal workpieces by spreading a coating of the composition of Example 1 on a surface of the first piece and bringing the surface of the second piece into close proximity thereto, thereby forming a sandwich with the composition therebetween. The composition is cured to a rubbery state without releasing any substantial amount of corrosive materials and odorous materials by exposing the structure to a moist atmosphere at about 75F. until a strong bond is formed.
Obviously, other modifications and variations of ; the present invention are possible in the light of the above teachings. It is, therefore, to be understood that changes may be made in the particular embodiments of this invention which are within the full intended scope of the invention as defined by the appended claims.
7~ ~ 60SI-184 SUPPLEMENTAR~ DISCLOSURE
It has further been discovered that an organic acid carbon content of between 2 and 12 provides the best combination of cure rate and ultimate properties. Also, the organic element of the organo tin salt can be one or two alkyl radicals, e.g.
from 1 or 2 to 6 carbon atoms, e.g.~ dimethyl~ and the organic acid radical can have from 2 to 6 or even 12 carbon atoms.
Reactivity is enhanced with higher acid radicals if the shortest alkyl radicals are present. In addition to those examples disclosed in the principal disclosure, dimethyltin bisneodecanoate may be used. Of these, dibutyltin diacetate and dimethyltin bisneodecanoate are preferred.
The following example is illustrative onl~, and should not be construed as limiting the invention.
Example 4 The procedure of Example 1, of the principal disclosure, is repeated, substituting for the dibutyltin diacetate catalyst, 0.1 parts of dimethyltin bis-neodecanoate (Witco UL-28). A
composition according to this invention is obtained.
,
Claims (36)
1. A fluid composition stable under substantially anhydrous conditions and curable in the presence of moisture to a self-bonding highly thermally stable elastic solid resistant to hot hydrocarbon oils, said composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunctionality, tetrafunctionality or a mixture of tri-and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2%
by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or l;
and (e) from 0.01 to 10 parts by weight of a curing catalyst of the group consisting of an organic tin salt of an organic acid and a tin salt of an organic acid, said organic acid containing from 2 to 6 carbon atoms.
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunctionality, tetrafunctionality or a mixture of tri-and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2%
by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or l;
and (e) from 0.01 to 10 parts by weight of a curing catalyst of the group consisting of an organic tin salt of an organic acid and a tin salt of an organic acid, said organic acid containing from 2 to 6 carbon atoms.
2. A composition as defined in claim 1 which also includes from 1 to 10 parts by weight of (f) a finely divided iron oxide thermal stabilizer.
3. A composition as defined in claim 1 wherein the viscosity of component (a) is within the range of 2,000 to 200,000 cps. at 25°C.
4. A composition as defined in claim 3 wherein the viscosity of component (a) is within the range of 2,000 to 30,000 cps. at 25°C.
5. A composition as defined in claim 1 wherein, in component (a), at least 50% of the total number of R and R1 groups are alkyl radicals and any remaining groups are aryl radicals.
6. A composition as defined in claim 5 wherein the alkyl radicals are methyl radicals and any remaining aryl radicals are phenyl radicals.
7. A composition as defined in claim 1 wherein the viscosity of component (b) is in the range of 50 to 300 cps. at 25°C.
8. A composition as defined in claim 1 wherein, in component (b), at least 50 percent of the alkyl substituents are methyl radicals and the fluid comprises from 0.2 to 0.6 percent by weight of silicon-bonded hydroxyl groups.
9. A composition as defined in claim 8 wherein, in component (b), the monoalkylsiloxy units, siloxy units or mixed such units comprise about 35 to 45 mole percent, the trialkylsiloxy units comprise from 3 to 5 mole percent the dialkylsiloxy units comprise from 45 to 67 mole percent, and the silicon-bonded hydroxyl content is about 0.2 to 0.5% by weight.
10. A composition as defined in claim 1 wherein the finely divided silica component (c) has been treated with dimethylcyclic siloxanes, has a surface area of about 200 square meters/gram and comprises about 20 to 30 parts by weight per 100 parts by weight of the total composition.
11. A composition as defined in claim 1 wherein in component (d), at least 50% of the total number of R2 groups are alkyl radicals and any remaining groups are aryl radicals and m is 1.
12. A composition as defined in claim 11 wherein the alkyl radicals are methyl radicals and any remaining aryl radicals are phenyl radicals.
13. A composition as defined in claim 11 wherein the R3 groups are 2-ethylhexanoxy radicals.
14. A composition as defined in claim 11 wherein the R3 groups are benzoxy radicals.
15. A composition as defined in claim 1 wherein catalyst component (e), is an organic tin salt of an organic acid containing from 2 to 6 carbon atoms.
16. A composition as defined in claim 15 wherein said catalyst is dibutyltindiacetate.
17. A composition as defined in claim 2 wherein iron oxide component (f) has a pH range of 6.0 to 7.5 and comprises about 3 to 6 parts by weight per 100 parts by weight of the total composition.
18. A fluid composition highly thermally stable and stable under substantially anhydrous conditions and curable in the presence of moisture to a self-bonding elastic solid resistant to hot hydrocarbon oils, said composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein n is 100 to 3,000;
(b) from 5 to 15 parts by weight of a fluid poly-methylsiloxane containing a high degree of trifunctionality, and comprising:
(i) from 35 to 45 mole percent of methylsiloxy units;
(ii) from 3 to 5 mole percent of trimethylsiloxy units; and (iii) from 45 to 67 mole percent of dimethylsiloxy units, and from about 0.2 to about 0.6 percent by weight of silicon-bonded hydroxyl groups;
(c) from 20 to 30 parts by weight of a finely divided fumed silica filler having a surface area of about 200 square meters per gram;
(d) from 5 to 7 parts of a cross-linking silane of the formula (CH3)m Si (OR3)4-m wherein R3 is hydrocarboyl of from 6 to 10 carbon atoms and m is 0 or 1; and (e) from 0.02 to 5 parts by weight of an organotin salt of an organic acid of from 2 to 6 carbon atoms.
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein n is 100 to 3,000;
(b) from 5 to 15 parts by weight of a fluid poly-methylsiloxane containing a high degree of trifunctionality, and comprising:
(i) from 35 to 45 mole percent of methylsiloxy units;
(ii) from 3 to 5 mole percent of trimethylsiloxy units; and (iii) from 45 to 67 mole percent of dimethylsiloxy units, and from about 0.2 to about 0.6 percent by weight of silicon-bonded hydroxyl groups;
(c) from 20 to 30 parts by weight of a finely divided fumed silica filler having a surface area of about 200 square meters per gram;
(d) from 5 to 7 parts of a cross-linking silane of the formula (CH3)m Si (OR3)4-m wherein R3 is hydrocarboyl of from 6 to 10 carbon atoms and m is 0 or 1; and (e) from 0.02 to 5 parts by weight of an organotin salt of an organic acid of from 2 to 6 carbon atoms.
19. A composition as defined in claim 18 which also includes (f) from 3 to 7 parts by weight of a finely divided iron oxide stabilizer having a pH in the range of 6.0 to 7.5.
20. A composition as defined in claim 2 wherein, in component (a), R and R1 are each methyl; in component (d), R3 is 2-ethylhexanoyl; and component (e) comprises dibutyltindiacetate.
21. A composition as defined in claim 1 wherein from 0.2 to 2 parts of an adhesion promoter per 100 parts total composition is also included.
22. A composition as defined in claim 21 wherein said adhesion promoter is glycidoxypropyltrimethoxysilane.
23. A composition as defined in claim 21 wherein said adhesion promoter is 1,3,5-tris-trimethoxysilyl-propylisocyanurate.
24. An article of manufacture comprising a plurality of metal surfaced pieces, each piece having at least a part of a surface portion in close proximity to another and a gasket layer therebetween, said gasket comprising a rubbery, moisture-cured composition which is highly thermally stable comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunctionality, tetrafunctionality or a mixture of tri- and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2% by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3) 4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or 1;
and (e) from 0.01 to 10 parts by weight of a curing catalyst of the group consisting of an organic tin salt of an organic acid and a tin salt of an organic acid, said organic acid containing from 2 to 6 carbon atoms.
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunctionality, tetrafunctionality or a mixture of tri- and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2% by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3) 4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or 1;
and (e) from 0.01 to 10 parts by weight of a curing catalyst of the group consisting of an organic tin salt of an organic acid and a tin salt of an organic acid, said organic acid containing from 2 to 6 carbon atoms.
25. An article of manufacture as defined in claim 24 wherein said composition also includes from 1 to 10 parts by weight of a finely divided iron oxide thermal stabilizer.
26. A method comprising:
(i) providing a plurality of metal surfaced pieces;
(ii) applying a layer of a moisture-curable gasket-forming composition to at least a portion of at least one of the metal surfaces;
26. A method comprising:
(i) providing a plurality of metal surfaced pieces;
(ii) applying a layer of a moisture-curable gasket-forming composition to at least a portion of at least one of the metal surfaces;
Claim 26 continued:
(iii) bringing at least two metal surfaced pieces into proximity so as to complete the formation of a moisture-curable gasketing layer therebetween; and (iv) exposing the article of step (iii) to moisture until the gasketing layer has cured to a rubbery material, said moisture gasketing composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of tri-functionality, tetrafunctionality or a mixture of tri-and tetrafunctionality and comprising:
(i) from 25 to 60 mole percent of monoalkylsiloxy, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of tri-alkylsiloxy units; and (iii) from 34 to 74 mole percent of di-alkylsiloxy units;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydro-carboyl and m has a value of 0 or 1; and (e) from 0.01 to 10 parts by weight of a curing catalyst of the group consisting of an organic tin salt of a fatty acid and a tin salt of a fatty acid, said fatty acids containing from 2 to 6 carbon atoms.
(iii) bringing at least two metal surfaced pieces into proximity so as to complete the formation of a moisture-curable gasketing layer therebetween; and (iv) exposing the article of step (iii) to moisture until the gasketing layer has cured to a rubbery material, said moisture gasketing composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of tri-functionality, tetrafunctionality or a mixture of tri-and tetrafunctionality and comprising:
(i) from 25 to 60 mole percent of monoalkylsiloxy, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of tri-alkylsiloxy units; and (iii) from 34 to 74 mole percent of di-alkylsiloxy units;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydro-carboyl and m has a value of 0 or 1; and (e) from 0.01 to 10 parts by weight of a curing catalyst of the group consisting of an organic tin salt of a fatty acid and a tin salt of a fatty acid, said fatty acids containing from 2 to 6 carbon atoms.
27. A method as defined in claim 26 wherein said composition also includes from 1 to 10 parts by weight of a finely divided iron oxide thermal stabilizer.
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE
28. A fluid composition stable under substantially anhydrous conditions and curable in the presence of moisture to a self-bonding high thermally stable elastic solid resistant to hot hydrocarbon oils, said composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid poly-siloxane containing a high degree of trifunctionality, tetra-funcationality or a mixture of tri- and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2% by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or l;
and (e) from 0.1 to 10 parts by weight of a highly reactive curing catalyst of the group consisting of an organic tin salt of an organic acid or a tin salt of an organic acid, said organic acid containing from 2 to 12 carbon atoms.
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid poly-siloxane containing a high degree of trifunctionality, tetra-funcationality or a mixture of tri- and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2% by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R2m Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or l;
and (e) from 0.1 to 10 parts by weight of a highly reactive curing catalyst of the group consisting of an organic tin salt of an organic acid or a tin salt of an organic acid, said organic acid containing from 2 to 12 carbon atoms.
29. A composition as defined in claim 28 which also includes from l to 10 parts by weight of (f) a finely divided iron oxide thermal stabilizer.
30. A composition as defined in claim 29 wherein said catalyst is dimethyltin bis-neodecanoate.
31. A fluid composition highly thermally stable and stable under substantially anhydrous conditions and curable in the presence of moisture to a self-bonding elastic solid resistant to hot hydrocarbon oils, said composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein n is 100 to 3,000;
(b) from 5 to 15 parts by weight of a fluid poly-methylsiloxane containing a high degree of trifunctionality, and comprising:
(i) from 35 to 45 mole percent of methylsiloxy units;
(ii) from 3 to 5 mole percent of trimethylsiloxy units; and (iii) from 45 to 67 mole percent of dimethylsiloxy units, and from about 0.2 to about 0.6 percent by weight of silicon-bonded hydroxyl groups;
(c) from 20 to 30 parts by weight of a finely divided fumed silica filler having a surface area of about 200 square meters per gram;
(d) from 5 to 7 parts of a cross-linking silane of the formula (CH3)m Si (OR3)4-m wherein R3 is hydrocarboyl of from 6 to 10 carbon atoms and m is 0 or 1; and (e) from 0.02 to 5 parts by weight of a highly reactive organotin salt of an organic acid of from 2 to 12 carbon atoms.
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein n is 100 to 3,000;
(b) from 5 to 15 parts by weight of a fluid poly-methylsiloxane containing a high degree of trifunctionality, and comprising:
(i) from 35 to 45 mole percent of methylsiloxy units;
(ii) from 3 to 5 mole percent of trimethylsiloxy units; and (iii) from 45 to 67 mole percent of dimethylsiloxy units, and from about 0.2 to about 0.6 percent by weight of silicon-bonded hydroxyl groups;
(c) from 20 to 30 parts by weight of a finely divided fumed silica filler having a surface area of about 200 square meters per gram;
(d) from 5 to 7 parts of a cross-linking silane of the formula (CH3)m Si (OR3)4-m wherein R3 is hydrocarboyl of from 6 to 10 carbon atoms and m is 0 or 1; and (e) from 0.02 to 5 parts by weight of a highly reactive organotin salt of an organic acid of from 2 to 12 carbon atoms.
32. A composition as defined in claim 28 which also includes (f) from 3 to 7 parts by weight of a finely divided iron oxide stabilizer having a pH in the range of 6.0 to 7.5.
33. An article of manufacture comprising a plurality of metal surfaced pieces, each piece having at least a part of a surface portion in close proximity to another and a gasket layer therebetween, said gasket comprising a rubbery, moisture-cured composition which is highly thermally stable comprising (a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
33. An article of manufacture comprising a plurality of metal surfaced pieces, each piece having at least a part of a surface portion in close proximity to another and a gasket layer therebetween, said gasket comprising a rubbery, moisture-cured composition which is highly thermally stable comprising (a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
Claim 33 continued:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid poly-siloxane containing a high degree of trifunctionality, tetra-functionality or a mixture of tri- and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2% by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R? Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or l;
and (e) from 0.01 to 10 parts by weight of a highly reactive curing catalyst of the group consisting of an organic tin salt of an organic acid or a tin salt of an organic acid, said organic acid containing from 2 to 12 carbon atoms.
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydrocarbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid poly-siloxane containing a high degree of trifunctionality, tetra-functionality or a mixture of tri- and tetrafunctionality and comprising (i) from 25 to 60 mole percent of monoalkylsiloxy units, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkylsiloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units, said polysiloxane containing from about 0.1 to about 2% by weight of silicon-bonded hydroxyl groups;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R? Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or l;
and (e) from 0.01 to 10 parts by weight of a highly reactive curing catalyst of the group consisting of an organic tin salt of an organic acid or a tin salt of an organic acid, said organic acid containing from 2 to 12 carbon atoms.
34. An article of manufacture as defined in claim 33 wherein said composition also includes from 1 to 10 parts by weight of a finely divided iron oxide thermal stabilizer.
35. A method comprising:
(i) providing a plurality of metal surfaced pieces;
(ii) applying a layer of a moisture-curable gasket-forming composition to at least a portion of at least one of the metal surfaces;
(iii) bringing at least two metal surfaced pieces into proximity so as to complete the formation of a moisture-curable gasketing layer therebetween; and (iv) exposing the article o-f step (iii) to moisture until the gasketing layer has cured to a rubbery material, said moisture-curable gasketing composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydro-carbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunction-ality, tetrafunctionality or a mixture of tri- and tetrafunctionality and comprising:
(i) from 25 to 60 mole percent of monoalkylsiloxy, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkyl-siloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R? Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or 1; and (e) from 0.01 to 10 parts by weight of a highly reactive curing catalyst of the group consisting of an organic tin salt of a fatty acid or a tin salt of a fatty acid containing from 2 to 12 carbon atoms.
(i) providing a plurality of metal surfaced pieces;
(ii) applying a layer of a moisture-curable gasket-forming composition to at least a portion of at least one of the metal surfaces;
(iii) bringing at least two metal surfaced pieces into proximity so as to complete the formation of a moisture-curable gasketing layer therebetween; and (iv) exposing the article o-f step (iii) to moisture until the gasketing layer has cured to a rubbery material, said moisture-curable gasketing composition comprising:
(a) 100 parts by weight of a silanol chain-stopped polydiorganosiloxane of the formula:
wherein R and R1 are each, independently, organic radicals of up to 8 carbon atoms selected from hydro-carbyl, halohydrocarbyl and cyano lower alkyl and n is an average number of from about 10 to 15,000;
(b) from 2 to 20 parts by weight of a fluid polysiloxane containing a high degree of trifunction-ality, tetrafunctionality or a mixture of tri- and tetrafunctionality and comprising:
(i) from 25 to 60 mole percent of monoalkylsiloxy, siloxy units or a mixture of such units;
(ii) from 1 to 6 mole percent of trialkyl-siloxy units; and (iii) from 34 to 74 mole percent of dialkylsiloxy units;
(c) from 10 to 100 parts by weight of a finely divided silica filler;
(d) from 3 to 10 parts by weight of a cross-linking silane of the formula:
R? Si (OR3)4-m wherein R2 has the values defined from R and R1 hereinabove, R3 is an organic radical of 6 to 30 carbon atoms selected from hydrocarboyl and halohydrocarboyl and m has a value of 0 or 1; and (e) from 0.01 to 10 parts by weight of a highly reactive curing catalyst of the group consisting of an organic tin salt of a fatty acid or a tin salt of a fatty acid containing from 2 to 12 carbon atoms.
36. A method as defined in claim 35 wherein said composition also includes from 1 to 10 parts by weight of a finely divided iron oxide thermal stabilizer.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US91954478A | 1978-06-27 | 1978-06-27 | |
| US919,544 | 1978-06-27 | ||
| US70,435 | 1979-08-28 | ||
| US06/070,435 US4257932A (en) | 1978-06-27 | 1979-08-28 | Curable compositions and process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1136311A true CA1136311A (en) | 1982-11-23 |
Family
ID=26751123
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000330424A Expired CA1136311A (en) | 1978-06-27 | 1979-06-22 | Curable compositions and process |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1136311A (en) |
-
1979
- 1979-06-22 CA CA000330424A patent/CA1136311A/en not_active Expired
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