CA1139479A - Low modulus room temperature vulcanizable silicone rubber compositions - Google Patents
Low modulus room temperature vulcanizable silicone rubber compositionsInfo
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- CA1139479A CA1139479A CA000330880A CA330880A CA1139479A CA 1139479 A CA1139479 A CA 1139479A CA 000330880 A CA000330880 A CA 000330880A CA 330880 A CA330880 A CA 330880A CA 1139479 A CA1139479 A CA 1139479A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K13/00—Use of mixtures of ingredients not covered by one single of the preceding main groups, each of these compounds being essential
- C08K13/02—Organic and inorganic ingredients
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/34—Silicon-containing compounds
- C08K3/36—Silica
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/04—Oxygen-containing compounds
- C08K5/09—Carboxylic acids; Metal salts thereof; Anhydrides thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/54—Silicon-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K5/00—Use of organic ingredients
- C08K5/56—Organo-metallic compounds, i.e. organic compounds containing a metal-to-carbon bond
- C08K5/57—Organo-tin compounds
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- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Sealing Material Composition (AREA)
Abstract
Abstract of the Disclosure A low modulus room temperature vulcanizable silicone rubber compo-sition with a good shelf life comprising a silanol containing polysiloxane a filler, an acyloxy functional silane as the cross-linked agent and as the catalyst a compound which is selected from the class consist-ing of zinc salts and zirconium salts or a co-catalyst system compris-ing as one co-catalyst a tin salt of carboxylic acid and as the other co-catalyst either a zinc salt or a zirconium salt of a carboxylic acid.
Description
'79 60 SI l78 Background of the Invention The present invention reldtes to a room temperature vulcanizable silicone rubber composition and more particularly the present in- `-velltion relates to a low modulus room tempesature vulcanizable silicone rubber composition with a good shelf life which results from the use of certain specific catalyst systems.
Sealants are well_known. A sealant and specifically a sealant that is utilized in high rise constructîon must adhere to the substracte to which it is applied and preferably has elastomeric properties.
The use of such sealants in high rise construction is well~known in that such sealants are applied where the window pane meets the building so as to seal the glass to the metal frame providing a weathertight seal. In addition and especially in high rise construc-tion there are ma~y areas in which the sealant is desirable for seLling the materials a.~ainst the elements of weathering so as to prevent moisture and dirt from entering the building once the sealant is used to seal the window pane to the metal frame Many sealants are used for such an application and speci~ically polysulfides.
Further, it is especially desirable that the sealant be an elastomer in its cured form, that is, it can be compresssed and expanded, that is,it has elasticity and an elastic mernory. It is desirable that the sealant be in the form of a true elastomer since it then will expand a~d contract in the joint in which it is located and, thus, will :~
~ ~' I - 1 ~
'7~
continue to seal aga~nst the elements of weathering.
It sould be noted that in some such sealant applications there is a preferred a sealant of high tensile strength and good adhesion to the substrate. This is the application where toughness of the sealant is of primary importance and the lack of elasticity of the sealant is not that important. Such sealant applications which are small necessarily apply to the sealing of joints in which there is a small joint moyement. Where the sealant is to accommodate fairly large relatiye expansion and contraction of a joint opening, then it is preferable to utilize a low modulus sealant. ~ low modulus sealant means a sealant which has a moderate tensile stxength, but a hi~h per cent elongation. Such sealants may be made tougher by the incorporation in them of a treated filler. Howeyer, the important property in the sealant is its per cent eIongation and, thus, it is desirable that the sealant will be able to compress or expand at least 25~ pf the distance of the thickness of the joint or more preferably be able to expand and compress by 50C6 of the thickness of the joint.
The ~ore the sealant can expand and compress in terms of the thickness of the joint, or of its own thickness, the more desi`rable it i~s~, as long as the sealant has some adhesi~on to the substrate, that is, it does not ~ithdraw or release from the substrate when it expands or contracts.
One class of such sealants use~ul in h~gh rise construction are one component room termperature vulcanizable si~licone rubber sealants~. An example of such a sealant is ~or instance to be found disclosed in U.S. Patent No. 3,2~6,161 - dated January 3, 1~67 - Kulpa. This patent discloses the use of a dialkoxydiacyloxysilane additive to improve the bond strengths OI a one component room temperature vulcanizable silicone rubber acyloxy system.
Another patent which discloses such a sealant is for instance that of U,S. Patent No. 3,382,205 - dated May 7, 1968 -Beer~ which discloses a room temperature ~ulcani7.able silicone rubber composition comprising as an additive for improying the adhesion and/or lowering the modulus of a composition, a fluid which is composed of R2SiO units R SiO3/2 units and R3SiQ1~2 units where R is a monoyalent hydrocarbon radical.
It should be noted that the above are additives to one component room temperature vulcanizable silicone rubber compositions. Such a one part RTV composition (RTV shall be used hereinafter to refer to room temperature vulcanizable silicone rubber compositions) comprise a silanol terminated diorganopolysiloxane polymer where the organo groups are monoyalent hydroca:rbon radi.cals, a filler which is selected from reinforcing or extending fillers (which fillers can be treated and untreated - an example of a reinforcing filler being fumed silica) and a cross-linking agent which is preferably methyltriacetoxy silane although it can be any alkyl triacyloxy silane. There is preferably utilized a catalyst with such systems to expedit the cure and such a catalyst is preferably the metal salt of a monocarboxylic acid where the metal varies from lead to manganese in the Periodic Table.
11;~1'79 60 sI-178 The basic ingredients of the silanol polymer, the filler, the acyloxy crosslinking agent and the metal salt of carboxylic acid are simply .-mixed under anhydrous conditions. When it is desired to cure the system, the mixture is simply applied and exposed to atmospheric ~noisture whereupon it cures to a silicone elastomer with a release of acetic acid. In the case where the cross-linking agent is methyl-triacetoxy silane, there are many additives that can be added to such a composition to change its properties. The foregoing patents that were disclosed above of Beers '205 Patent and the Kulpa '161 Patent disclosed two additives which may be added to such a system to improve its properties in the case of Kulpa being the adhesion promo-ter and in the case of the additive of Beers, it being an enhancement of adhesion promotion, as well as lowering the modulus of the sy stem.
In the case of such sealant compositions without major modification of the ingredients, there results a silicone sealant which has plus or minus 257~o extension and compression in the joint in which it is placed, of a joint 1/16 to 1 inches wide. Accordingly, it is highly desirable to modify such a traditional sealant of the composition disclosed pre~riously and specifically silicone sealant of the composition disclosed pre~riously, such that it has a plus or minus 50% compression and extension in joints whose w;dth varies from 1/ 16 to 1 inch.
There are many ways for lowering the modulus of an acyloxy functional silicone sealant, or other silicone sealants for that matter.
11;39~t~7~ 6051-178 One modification that may be made to the silicone sealant i8 to --increase the viscosity or molecular weight or polymer chain length of the base silanol terminated diorganopolysiloxane polymer. It should be noted that the increasing of the viscosity, increasing the molecular weight and increasing the polymer chain length all mean the same thing; that is, by increasing the viscosity, the molecular weight of the polymer is increased which makes the final silicone -elastomer more elastic and thus it has a lower modulus. The longer polymer chains will not be as highly cross-linlced as shorter polymer chains and as such the silicone elastomer that is formed from the longer polymer chains will be more elastic or have a lower modulus.
Another way of decreasing the modulus is to use an extending oil in +he composition that is a diorganopolysiloxane polymer which is unreactive to the system and which simply acts as a plasticizer.
This again will make the composition more elastic and lower the modulus of the cured system. Another way of lowering the modulus of the system is to add the fluid of the Beers USP 3, 382, 205, such a fluid acts as a chainstopping fluid, thus, lowering the amount of cross-linking that is carried out by the acyloxy functional silane crosslinking agent. The lower crosslinking makes the cured compo-sition more elastic and thus allows it to have a lower modulus.
Finally, fumed silica or precipitated silica that is a reinforcing filler may be added to the composition and preferably such reinforcing filler is treated so as to increase the tensile product of the composition, i. e., the toughness of the composition. Accordingly, all of the above modifications may be made to one component acyloxy functional RTV
60 SI~17~
systen~ such that it has the plus or minus 50% desired compression and expansion in the joints.
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Accordingly, it is highly desirable to formulate an acyloxy functional silicone sealant which has the foregoing low modulus so as to meet the specific compression and expansion requirement set forth above.
HoweYer, it has been found that when such is done or ca~ried out that the shelf life of the compositions suffer, that is, the composition will have a shelf life of anywhere from 6 months to 9 months, and after that time may c~re very slowly or not cure at all. It is also noted that when the sixth or ninth month period i8 passed, the compo-sition will have a tack-free time that is e~ceedingly long which is unde sirable .
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Accordingly, it is one object of the present invention to provide for a low modulus, one package RTV acyloxy functional sealant, which has a good shelf life, that is a shelf life of one year or more.
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It is another object of the present invention to provide for a low m odulu s a cyloxy ~ ln ct i on a 1 one c o mp o n e nt R T V s e ala nt whi ch ha s a shelf life of 18 to 27 months.
It i9 an additional object of the present invention to provide for a composition of a one component acyloxy functional RTV composition which when applied to a joint width of a specified size will ha~e plus or minue 50% compression and expansion, that is, it is a low modulus silicone sealant which has a short tack-free time and a lon~ shelf life.
~l;l't~'7~ 6051-178 It is stil~ an additional object of the present invention to provide for the process of producing a low modulus one component acyloxy functional RTV sealant which will have a short takc-free time and a long shelf life. These and other objects of the present invention are accomplishe . 5 by means of the disclosure set forth hereinbelow.
In accordance with the above object, there is provided by the present invention a low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (A) a first mixture of (l) lOO parts by weight of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50, 000 -350, 000 centipoise at Z5 C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to lOO parts by weight of a fiLler;
and (B) a second mixture where there is utilized from 1 to 20 parts by weight of the second rmixture per lOO parts of the first mixture of t3) from 60 to lOO parts by weight of an acyloxy functional silane of the f o rmul a, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) from O. l to 5 parts by weight of a catalyst selected from the class consistin of zinc salts of carboxylic acid, zirconium salts of carboxylic acid and mi~tures thereof~
Such compositions while having a good cure and a good shelf life.
for extended periods of time such as 18 months to 27 months after they are prepared, nevertheless have an extended tack-free time, such 11;~9~79 60 SI-178 as 40 to 60 minutes. If it is desired to have a low modulus compo-sition with a good shelf life and a good cure after a period of time of 18 months to 27 months, there is utilized in the mixture (B) in the composition above in addition to the acyloxy functional silane a co_ catalyst system. Such a co-catalyst system contains from . 5 to 5 parts by weight of a tin salt of ~ carboxylic acid and from . 001 to . 4 -parts by weight of a co-catalyst selected from the class consisting of a z;nc salt of a carboxylic acid and zirconium salt of a carboxylic acid. As pointed out previously, such a co-catalyst system unlike the first catalyst system has a good shelf life, that is the composition will cure after 18 - Z7 months after it has been prepared and will have a short tack~-free time of 20 minutes or less; unlike the extended tack-free time of the composition of the first catalyst system. One type of tin salt that can be utilized in the co-catalyst system is dibutyltin-dilaurate. A much more preferred tin salt which give the advantageous tack~free time in the instant compositions is dimethyl tin neo-decanoate The preferred zirconium salt is ~irconium octoate while the preferred zinc salt is zinc octoate. Other zinc salts and zirconium salts would operate just as effectively in the instant invention. The above compo- -sitions may contain any of a number of well-known additives as will be described below.
Descriptioll of the Preferred Embodiment The base polymer of the one component room temperature vulcanizable silicone rubber composition of the instant case comprises a silanol terminated diorganopolysiloxane polymer having the viscosity varying from 50, 000 to 350, 000 centipoise at 25 C and more preferably has a 94';r9 6051_~78 viscosity tkat varies lO0, 000 to Z50, 000 centipoise at 25 C.
It should be r~oted of course that the higher the viscosity of the base polymer, the lower the modulus of the resulting composition. The organo groups of said diorganopolysiloxane polymer can be selected from any monovalent hydrocarbon radical and halogenated monovalent hydrocarbon radical. Examples of substituent groups whic~ the or"ano radical can stand for, for instance a~cyl radicals, such as methyl, ethyl, propyl of 1 to 8 carbon atoms; cycloallcyl radicals such as cyclohexyl, cycloheptyL etc. of 4 to 8 carbon atoms; mono_ nuclear aryl radicals such as phenyl, rnethylphenyl, ethylphenyl, etc.;
and alkenyl radicals such as vinyi allyl, etc.
In additioD, the organo groups in such diorganopolysiloxane polymer ca stand for halogenated monovalent hydrocarbon radicals such fluoro-alkyl radicals are for instance 3, 3, 3 trifluoropropyl. Such diorgano-polysiloxane polyrner is preferably lOO(~o a linear diorganopolysiloxane polymer. However, up to 0. 1 by weight of combined monofunctional siloxy units and trifunctional siloxy units can be tolerated in the polymer. This is, the combined monofunctionality and trifunctionality of siloxy units cannot exceed 0.1% by weight. Preferably the linear diorganopolysiloxane polyrner has the formula, where R is selected from mono~alent hydrocarbon radicals and 4~9 60 SI-178 halogenated rnonovalent hydroca.rbon radicals, which are the same as -the radicals given as examples for the organo radicals above and .
where t varies such that the polymer has a ~riscosity varying from 50, 000 to 350l 000 centipoise at 25 C and more preferably has a , -viscosity varying from lO0, 000 to 250, 000 centipoise at 25~C.
The production of such silanol terminated diorganopolysiloxane polyme s --is well-known in the art. Briefly, there istaken diorganodichloro_ silanes with up to lO~lo by weight of monofunctionality or trifunctionality -and the chlorosilanes are hydrolyæed in water. The resulting hydrolyz te ---is then taken and the water separated from it and there is added to it, anywhere from 1 to ~% by weight of potassium hydroxide The hydrolyzate is heated at temperatures of over 100 and preferably 150C for a period of time varying any~rhere from l to 8 hours so as to preferentially form cyclopolysiloxanes.
lt should ~e noted that the hydxolyzate mixture as obtained from the water hydrolysîs contains in it low molecular weight cyclopolysiloxane as well as low molecular weight silanol terminated diorganopolysiloxan polymers. By cracking such a hydrolyzate with potassium hydroxide at elevated temperatures most of the contents of the silicone hydrolyza e is predominately converted to the cyclotetrasiloxanes. The foregoing cyclotetrasiloxanes are then taken and they are mixed together and -there is added to such cyclotetrasiloxanes anywhere from 50 to 500 parts per million of potassium hydroxide and the desired amount of water as a chainstopper. The resulting mixture is then heated at elevated temperatures so as to preferentially form at above 100 and 4'79 ~ ~
more preferably above 150C in an equilibration reaction that desired -silanol terminated diorganopolysiloxane polymer. The final viscosity -of the polymer that is formed -~,vill depend on the amount of water that is added as a chainstopper. The more water that i~ present as a S chainstopper then the lower the moleculare weight of tne silanol terminated diorganopolysiloxane polymer that will be formed. The less water that is added, the higher the molecular weight of the silanol terminated diorganopolysiloxane polymer that will be formed.
In addition to the water there n~ay be utilized as a chainstopper, low molecular weight silanol terminated diorganopolysiloxane polymers, that is the polymers that are obtained when the diorganodichlorosilanes are hydrolyzed in water, may also be used as chainstoppers. When the desired amount of silanol terminated diorganopolysiloxane polymer ha3 been formed in the equilibration reaction, then the alkali metal hydroxide catalyst, that is the potassium hydro~cide is neutralized, and the unrea¢ted cyclics are stripped off to yield the desired base -polymer. , .
It should be noted that the process for forming the silanol terminated diorganopolysiloxane polymer having fluoroalkyl substituted groups Z0 differs from the process or producing the diorganopolysiloxane polyrners having non-halogenated substituent groups in that the fluoro-alkyl substituted polyn~er can be produced both from cyclotrisiloxanes as well as from cyclotetrasilo~sanes. The process of the production of the polymer from the cyclotrisiloxanes is preferred since that results in a maximum conversion of the cyclic trisiloxanes to the desired polymex. S
i4~79 6051-178 ~ ~
In accordance with the present invention there is utiliæed per l00 parts by weight of the base silanol terrninated polymer of from 5 to -l00 parts by weight of a filler and more preferably from 10 to 30 parts -by weight of a filler. Such a filler can be selected from reinforcing fillers or from extending fillers. The reinforcing fillers as is tivell .-knowD, are furlled silica and precipitated silica. The reinforcing ~
the fillers are preferred in/composition, if it is desired to increase the tensile strength of the cured silicone elastomer. The disadvantage of t'~: e reinforcing fillers, however, is that they unduly increase the v;scosity of the uncured composition and decrease its elongation properties.
Such effects can be alleviated by treating the filler as will be --e~plained hereinbelow.
If it is desired to increase the tensile strength of the composition to .-some extent, without unduly increasing the viscosity of the uncured composition and without unduly decreasing the elongation,there may be incorporated an extending filler into the composition in the above con- -centrations. Examples of extending filler s are for instancè titanium dioxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, glass fibers, polyvinyl chloride, ground quartz. Other examples of extending fillers that can be utilized are lithopone, zinc :~
oxide, calcium carbonate, magnesium oxide, chromic oxide, zirconium oxide! aluminum oxide, alpha quartz, calcined clay, carbon, graphite, quartz, cotton s~ thetic fibers, etc.
In accordance with the instant case, it is preferred that the filler that ZS l ~ bt oti zed be of a reinforcing type and ;pecifica11y of fumed ;ilica, ~13947~ 60 SI-178 ' since even a small quantity of such fumed silLca ~ill ; increase the tensile strength.and toughness of the final elastomer sealant.
Further if such fumed silica is utilized i:n small enough quantities, it will not duly decrease the per cent elongation of the cured elastomer to prevent the fi~ller from decreasin~ the per cent elongation of the cured composition and als.o to preyent the fi~ller from increa$~ing the viSCQSity of the uncured compos~tion to undesirable lQ levels~ the filler is preferably treated. Thus, the silica filler may be treated as for example as disclosed in U.S.
Patent No. 2,9,38,009 - dated MaY 24, 1~60 - Lucas with cylicpolysiloxanes. Another method for treating fillers that can be utilized in the invention of the Lnstant case ,is that disclosed in U.S. Patent No. 3,024,126' ~ dated March 6, 1962 Brown.
In add~tion silazane treated fillexs i,n accordance with the disclosure of S~ith`U.S. Patent 3,3,65,743 - dated January 18, 1972 and V.S. Patent No. 3,837,878 - dated September 24, 1974 - Beers are preferred as treated fillers in the inStant inyention However, the most preferred treated filler in the instant i`nyention i.s fumed s-~licR txeated with cyclopoly~siloxanes and more specifically~ with cyclotetrapoly-siloxanes: such as octamethylcyclotetrasiloxane.
The above mixture of filler and silanol terminated diorganopolysiloxane polymer forms the base mixture of the instant composit~on. To anywhere of 100 parts of the base mixture there is added in accordance with the instant inYenti:on from 1 to 20 parts by weight of a cataly~st 3Q mixtuxe wherein the catalys:t mixture is generally composed of a crosslinking ~ 13 -l ~
60 SI~17~
agent, the adhesion promoter and the true catalyst that accelerates the reaction. There is used from l to 20 parts by weight of the catalyst mixture per 100 parts of the base mixture. The mixture of the s;lanol terminated diorganopolysiloxane polymer and filler can -be cousidered to be the first mixture or base rnixture, and preferably there is utilized 1 to 10 parts by weight of the catalyst mixh~re or second mixture per hundred parts by weight of the first mixture and in such catalyst mixture there will be anywhere from 60 to lOO parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 Where R and R' are monovalent hydrocarbon radicals and are preferabl alkyl radicals of 1 to 8 carbon atoms, phenyl radicals and most preferably methyl radicals. The above acyloxy functional silane is the crosslinking agent in the instant composition. The most preferred and most common of such crosslinking agents is, of course, methyltriacetoxy silane. There is no need to explain the workings of such ;~ crosslinking agent or how it is obtained since such is well-know~ to a worker skilled in the art. The catalyst that may be utilized with such acyloxy functional silane crosslinking agent is a tin salt of carboxylic acid such as for instance dibutyl tin dilaurate or tin neodecanoate. However, as stated previously when the compo-sition is desired to be low modulus and there is utili2ed the above tin catalyst, the composition had an imperrnissible shelf life, that is a shelf life of 6 - 9 months and after that time the composition will not cure .
11~ 79 60 SI-178 Accordingly, it was highly unexpected to find a composition that would have an acceptable shelf life by combining in said second mixture with the acyloxy functional silane instead of the tin salt from .1 to 5 parts by weight of a catalyst selected from a class consistirg of .-zinc salts of carboxylic acid and zirconium salts of carboxylic acid and mixtures thereof. Preferably there is used from . 5 to 3 parts by weight of such salts. The preferred catalysts are of course zinc octoates or zirconium octoate.
The only disadvantage with such a composition was that while it had a good shelf life that is, it had a shelf life that would vary any~here from 18 months _ 27 months, nevertheless it had a tack-free time that was long. Thus, the composition could have a tack-free time of anywhere from 30 minutes to 60 minute~ with the foregoing use of the zirconium salt or the zinc salt in place of the tin salt in the composition.
If this i9 acceptable, then the zirconium salt and the zinc salt or mixtures thereof can be utilized as catalysts in the instant composition in place of the traditional tin salts the composition will have a good shelf life although longer than normal tack-free time.
It should be pointed out that the compositions of the prior art, that is the low modul~ls compositions o:f the prior art containing a tin salt therein had a lengthening of tack-free time after the 6 - 9 months of storage to the point where permanent residual surface tack was present after several days cure, that i9 the composition would not become tack-free except after a very long period of time. This is not the case Z 5 ~ With th ns t8nt c ~mpo siti on ~i~ing zir conium s alt s or zinc salts .
11;~9'~'751 6 o Sl- 1 713 After 30 minutes, 60 minutes or at the rnost 2 hours, the cornpositions do becor~e tack-free and the compositions do cure and do have a --shel~ stability in the range of 18 months - 27 months.
It should also be noted that the prior art composition using the low modulus composition, that is the low modulus prior art composition utilizing tin salts as a catalyst would after storage beyond the 9 month --period would have a decrease of total cure so that the material e~ren after a 24 hour cure had a putty like consistency and pressure applied to the material caused permanent deformation. Initially, this e~ect was the notice of loss Shore A Hardness. In the latter stages of aging, the putty-like consistency would remain even after a one month time --at ambient conditions, that is the composit;on was curing 30 slowly that it appeared it wou ld never cure. -The low rnodulus compositiolls of the instant case with zirconium and zinc salts in them in the above concentrations will cure within 24 hours even after a 9 month period in spite of the fact that the tack-free tirne may be as long as 1 hour.
',''.'.-It should be noted that in the second mixture of the catalyst there is preferably used anywhere rom 60 to 100 parts by weight of the cross-linking agent and more preferably from 80 to 100 parts by weight of the ~
crosslinking agent with from generally .1 to 5 parts and more prefer-ably . 5 to 3 parts by weight of the catalyst which is selected frorn zinc salts and the zirconium salts of carboxylic acid.
11;~ 79 60 SI-178 ~urther, in a more preferred embodiment of the instant case, there .
i9 utilized a co-catalyst system with the cross-linking agent, where in the co-catalyst system contains fro.m . 1 to 5 parts by weight of an alkyl tin salt of a carboxylic acid and fro~n . 001 to . 4 pa~ts by weight of a co-catalyst selected from the class consisting of a zinc salt of a carboxylic acid and a zirconium saIt of a carboxylic acid. More preferably, there is utilized as a co-catalys in the system from 0. 01 to 0. 2 parts by weight of the zirlc salt or the zirconium salt of carboxylic acid with from 0.1 to l parts by weight of a dialkyl tin salt of carboxylic acid with the al~cyl group having 1 to 2 carbon atoms . The co- catalyst system of the tim salt with the zirconium or zinc salt is preferred over single catalyst system of the zirconium salt or the zinc salt since the co-catalyst system results in a composition which has good cure after storage varying from 18 months to 27 months with a tack-free time of 15 to 20 minutes. The composition without the combination or co- catalyst system of both the zinc or zirconium salt in combination with a dialkyl tin salt re sults in a composition with a good shelf lie that will produce a good cure after storage fo .
a period of time of 18 - 27 months, but will have a prolonged tack-free time of 30 minutes to 60 minutes or more. The COlnpO-sition with a co- catalyst system of the tin salt in combination with the zirconium salt or zinc salt will have a good shelf life, that is, it will have a good cure at periods of storage of as much as 18 months or as much as 27 months and will also have a short ~ -17_ 11;3~1~'7g 60 51-178 ,ack-free time of 15 minute~ to 30 minutes.
A less preferred tin salt that can be utilized in cornbination with the zinc salt or zirconium salt is for instance dibutyltindialurate.
However, the tin salt that is preferred in the instant compositions is one which has a diallcyl group which is a dial~yl tin soap of a carboxylic acid in which the dailkyl group is selected from dimethyl and the carboxylic acid portion contains anywhere from 2 to 22 carbon atoms and is most preferably neodecanoate.
Accordingly, the most preferred tin salt is dimethyl tin neodecanoat l 0 as the tin salt in combination with the ~inc salt or the zirconium salt in the co-catalyst system oi the instant invention.
Accordingly, to pxepare the compositions of the instant case, the co-catalyst system or the catalyst system is mixed with the acyloxy functional silane and the second mixture is then mixed at a concentration of anywhere from 1 to 20 parts by weight per lO0 parts by weight of the first mixture and the entire mixture is then packed in a moisture-proo~ container. Such a composition is maintained in the anhydrous state until it is desired to cure the composition. Then the composition is appl ied as a sealant in whatever rnanner it is desired and exposed to atmospheric moisture to cure to form an elastomeric silicone sealant.
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It should be noted that even though the composition is disclosed and -claimed in the form of mixing two mixtures, the claims in the disclosuxe of the instant case are directed to a one-componerlt RTV~
,~ -18-1 ~ 9~7~3 60 SI~178 system. All of the ingredients are mixed together into a single mixture and stored as such. When it is desired to utilize the --:
composition or convert it to a silicone elastomer, it is simply taken and exposed to atmospheric moisture either by squeezing frorr~
a tube or being pushed put of a caulking tube, such that it is exposed to atmospheric ~noistur~ whereupon the acyloxy functional -silane wil~ hydrolyze and crosslink to a silicone elastomer. -It should be noted that the clain~ language in the specification dis-cioses the formation of two mixtures which are mixed together to form the single component of the instant composition, since this is how the composition is prepared in practice and also to acilitate the description and recitation of the concentrations thereof of the -ingredients. There are additional ingredierts to the instant composition ancl specifically in the instant composition there are additional ingredients which are pre sent to make the composition a low modulus composition.
As pointed out previously, there is desirably utilized a high viscosit silanol terminated diorganopolysiloxane base polymer in the instant composition so as to lower the modulus of the composition or increase the per cent elongation. In the above cornposition and specifically to decxease the modulus of the composition, there is present int he first mixture of the one component composition of the instant case per 100 parts of the silanol terminated diorgano-polysiloxane polymer of from 0 to 50 parts by weight of a plasticize -which is a diorganopolysiloxane polyrner of a viscosity varying from 1~ 4~79 60 SI-178 10 to 5, 000 centipoise at 25'C where the organo groups are monovalent hydrocarborL radicals.
It should also be noted that the organo groups of such diorgano-polysiloxane polymer are the same as the organo groups of the silanol base polymer.
It should al~o be noted that such diorganopolysiloxane polymer i8 triorganosilylendstopped. It is preferred that the diorganopolysiloxa ~e polymer be strictly linear. However, up to 1% of tri~unctionality and monofunctionality combined is permitted. Generally, there may be utilized f~om 1 to 50 parts by weight of the plasticizer diorganopolysiloxane polymer and more preferably there is utilized anywhere from 20 to 30 p~ rts by weight of diorganopolysilcxane polymer per 100 parts of the silanol terminated diorganopolysiloxane polymer. Further, although the viscos*y of the polymer can vary from 10 to 5, 000 centipoise, it preferably varies anywhere from 10 to 500 centipoise at 25C. The diorganopolysiloxane polym r of which the most preferably type for use in the present invention is a dimethylpolysiloxane polymer of a viscosity varying from 10 to .
500 centipoise at 25 C which is trimethylsiloxy endstopped and whic~
is substantially a linear polymer can be produced by methods well known in the art. Thus, the polymer can be produced by simply hydrolyzing diorganodichlorosilanes with triorganochlorosilanes and separating the resulting fluid that is formed. It can be appreci ted that such a fluid will not be completely linear and may have up to 11;1~'17~ 60 51-178 l % of monofunctional siloxy units and trifunctional siloxy units.
However, such units will not detract from the plasticizing effect -. of the diorganopolysiloxane polymer.
Accordingly, the use of the plasticizer, that is the diorganopolysilo~ ~ne-fluid, having triorganosiloxy endstopped units will decrease the modulus of the composition if utilized i~ the foregoing quantities.
To further decrease the modulus of the composition there may be utilized in the base or first mixt~re per 100 parts by weight of the silanol terminated diorganopolysiloxane polyme r of anywhere from l - 25 parts by weight more preferably 5 - 15 parts by weight of a chainstopping fluid having in it monofunctional siloxy units, difunctional siloxy units and trifunctional siloxy units. Thus, preferably the 1uid is composed of R2 SiO units R33 SiOo 5 units and R3 SiOl 5 units where the ratio of organosiloxy units and diorganosiloxy units varies frorn 0. ll to l. 4, inclusive and the ratio of the triorganosiloxy units and diorganosiloxy units varies from 0. 02 to about l. 0, inclusive and R3 is a monovalent hydro_ carbon radical. It should be noted the term R3 being a Inonovalent hydrocarbon radical intended to include both mono~ralent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals such as 3, 3, 3 trifluoropropyl. The groups for which R3 radical may stand for is much the same as given before in the definition of the organo groups and the R2 groups for the silanol termi~ated diorganc -polysiloxane polymer which is the base polymer in the instant ~`1 ~ 79? 6 0 SI- 17 8 compositions. Such a polymer cornposed of monofunctional, difunctional and trifunctional siloxy lmits will contain anywhere fxom .1 to 8% by weight of nydroxy radicals. Such silicone fluid or chainstopped fluid has two advantages.
. . ,.-}D another aspect, it acts as an adhesion promoter and allows the cured composition to adhere to various types of substrates with better adhesion than would be the case if it was not utilized.
The production of such fluid is also well-known ir~ the art and generally comprises hydrolyzing the appropriate quantities of diorgar~ o-dichlorosilanes with m~noorganotrichlorosilanes and triorganochloro_ silanes in water and then separating and purifying the resulting fluid that is formed. An example of the foregoing f}uid composed o~
the rr,onofunctional siloxy units and difunctional siloxy units and trifunctional siloxy units for use in one part RTV Compositions is disclosed in Beers USP 3, 382, 205.
Use of such fluid to improve the shelf life of one component acylo~y funcL.ional silane RTV compositio ns is disclosed in this patent. However, the use of such lluid in ¦
combination with the other fluids and modifications of the instant case to both lower the modulus of the composition and increase the shelf life is not disclosed in the above Beers Patent.
However, this increase in tensile strength and decrease in modulus is more than offset by the other ingredients and modifications disclosed above to result in a low modulus one component RTV
Sealants are well_known. A sealant and specifically a sealant that is utilized in high rise constructîon must adhere to the substracte to which it is applied and preferably has elastomeric properties.
The use of such sealants in high rise construction is well~known in that such sealants are applied where the window pane meets the building so as to seal the glass to the metal frame providing a weathertight seal. In addition and especially in high rise construc-tion there are ma~y areas in which the sealant is desirable for seLling the materials a.~ainst the elements of weathering so as to prevent moisture and dirt from entering the building once the sealant is used to seal the window pane to the metal frame Many sealants are used for such an application and speci~ically polysulfides.
Further, it is especially desirable that the sealant be an elastomer in its cured form, that is, it can be compresssed and expanded, that is,it has elasticity and an elastic mernory. It is desirable that the sealant be in the form of a true elastomer since it then will expand a~d contract in the joint in which it is located and, thus, will :~
~ ~' I - 1 ~
'7~
continue to seal aga~nst the elements of weathering.
It sould be noted that in some such sealant applications there is a preferred a sealant of high tensile strength and good adhesion to the substrate. This is the application where toughness of the sealant is of primary importance and the lack of elasticity of the sealant is not that important. Such sealant applications which are small necessarily apply to the sealing of joints in which there is a small joint moyement. Where the sealant is to accommodate fairly large relatiye expansion and contraction of a joint opening, then it is preferable to utilize a low modulus sealant. ~ low modulus sealant means a sealant which has a moderate tensile stxength, but a hi~h per cent elongation. Such sealants may be made tougher by the incorporation in them of a treated filler. Howeyer, the important property in the sealant is its per cent eIongation and, thus, it is desirable that the sealant will be able to compress or expand at least 25~ pf the distance of the thickness of the joint or more preferably be able to expand and compress by 50C6 of the thickness of the joint.
The ~ore the sealant can expand and compress in terms of the thickness of the joint, or of its own thickness, the more desi`rable it i~s~, as long as the sealant has some adhesi~on to the substrate, that is, it does not ~ithdraw or release from the substrate when it expands or contracts.
One class of such sealants use~ul in h~gh rise construction are one component room termperature vulcanizable si~licone rubber sealants~. An example of such a sealant is ~or instance to be found disclosed in U.S. Patent No. 3,2~6,161 - dated January 3, 1~67 - Kulpa. This patent discloses the use of a dialkoxydiacyloxysilane additive to improve the bond strengths OI a one component room temperature vulcanizable silicone rubber acyloxy system.
Another patent which discloses such a sealant is for instance that of U,S. Patent No. 3,382,205 - dated May 7, 1968 -Beer~ which discloses a room temperature ~ulcani7.able silicone rubber composition comprising as an additive for improying the adhesion and/or lowering the modulus of a composition, a fluid which is composed of R2SiO units R SiO3/2 units and R3SiQ1~2 units where R is a monoyalent hydrocarbon radical.
It should be noted that the above are additives to one component room temperature vulcanizable silicone rubber compositions. Such a one part RTV composition (RTV shall be used hereinafter to refer to room temperature vulcanizable silicone rubber compositions) comprise a silanol terminated diorganopolysiloxane polymer where the organo groups are monoyalent hydroca:rbon radi.cals, a filler which is selected from reinforcing or extending fillers (which fillers can be treated and untreated - an example of a reinforcing filler being fumed silica) and a cross-linking agent which is preferably methyltriacetoxy silane although it can be any alkyl triacyloxy silane. There is preferably utilized a catalyst with such systems to expedit the cure and such a catalyst is preferably the metal salt of a monocarboxylic acid where the metal varies from lead to manganese in the Periodic Table.
11;~1'79 60 sI-178 The basic ingredients of the silanol polymer, the filler, the acyloxy crosslinking agent and the metal salt of carboxylic acid are simply .-mixed under anhydrous conditions. When it is desired to cure the system, the mixture is simply applied and exposed to atmospheric ~noisture whereupon it cures to a silicone elastomer with a release of acetic acid. In the case where the cross-linking agent is methyl-triacetoxy silane, there are many additives that can be added to such a composition to change its properties. The foregoing patents that were disclosed above of Beers '205 Patent and the Kulpa '161 Patent disclosed two additives which may be added to such a system to improve its properties in the case of Kulpa being the adhesion promo-ter and in the case of the additive of Beers, it being an enhancement of adhesion promotion, as well as lowering the modulus of the sy stem.
In the case of such sealant compositions without major modification of the ingredients, there results a silicone sealant which has plus or minus 257~o extension and compression in the joint in which it is placed, of a joint 1/16 to 1 inches wide. Accordingly, it is highly desirable to modify such a traditional sealant of the composition disclosed pre~riously and specifically silicone sealant of the composition disclosed pre~riously, such that it has a plus or minus 50% compression and extension in joints whose w;dth varies from 1/ 16 to 1 inch.
There are many ways for lowering the modulus of an acyloxy functional silicone sealant, or other silicone sealants for that matter.
11;39~t~7~ 6051-178 One modification that may be made to the silicone sealant i8 to --increase the viscosity or molecular weight or polymer chain length of the base silanol terminated diorganopolysiloxane polymer. It should be noted that the increasing of the viscosity, increasing the molecular weight and increasing the polymer chain length all mean the same thing; that is, by increasing the viscosity, the molecular weight of the polymer is increased which makes the final silicone -elastomer more elastic and thus it has a lower modulus. The longer polymer chains will not be as highly cross-linlced as shorter polymer chains and as such the silicone elastomer that is formed from the longer polymer chains will be more elastic or have a lower modulus.
Another way of decreasing the modulus is to use an extending oil in +he composition that is a diorganopolysiloxane polymer which is unreactive to the system and which simply acts as a plasticizer.
This again will make the composition more elastic and lower the modulus of the cured system. Another way of lowering the modulus of the system is to add the fluid of the Beers USP 3, 382, 205, such a fluid acts as a chainstopping fluid, thus, lowering the amount of cross-linking that is carried out by the acyloxy functional silane crosslinking agent. The lower crosslinking makes the cured compo-sition more elastic and thus allows it to have a lower modulus.
Finally, fumed silica or precipitated silica that is a reinforcing filler may be added to the composition and preferably such reinforcing filler is treated so as to increase the tensile product of the composition, i. e., the toughness of the composition. Accordingly, all of the above modifications may be made to one component acyloxy functional RTV
60 SI~17~
systen~ such that it has the plus or minus 50% desired compression and expansion in the joints.
.
Accordingly, it is highly desirable to formulate an acyloxy functional silicone sealant which has the foregoing low modulus so as to meet the specific compression and expansion requirement set forth above.
HoweYer, it has been found that when such is done or ca~ried out that the shelf life of the compositions suffer, that is, the composition will have a shelf life of anywhere from 6 months to 9 months, and after that time may c~re very slowly or not cure at all. It is also noted that when the sixth or ninth month period i8 passed, the compo-sition will have a tack-free time that is e~ceedingly long which is unde sirable .
. :
Accordingly, it is one object of the present invention to provide for a low modulus, one package RTV acyloxy functional sealant, which has a good shelf life, that is a shelf life of one year or more.
.
It is another object of the present invention to provide for a low m odulu s a cyloxy ~ ln ct i on a 1 one c o mp o n e nt R T V s e ala nt whi ch ha s a shelf life of 18 to 27 months.
It i9 an additional object of the present invention to provide for a composition of a one component acyloxy functional RTV composition which when applied to a joint width of a specified size will ha~e plus or minue 50% compression and expansion, that is, it is a low modulus silicone sealant which has a short tack-free time and a lon~ shelf life.
~l;l't~'7~ 6051-178 It is stil~ an additional object of the present invention to provide for the process of producing a low modulus one component acyloxy functional RTV sealant which will have a short takc-free time and a long shelf life. These and other objects of the present invention are accomplishe . 5 by means of the disclosure set forth hereinbelow.
In accordance with the above object, there is provided by the present invention a low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (A) a first mixture of (l) lOO parts by weight of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50, 000 -350, 000 centipoise at Z5 C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to lOO parts by weight of a fiLler;
and (B) a second mixture where there is utilized from 1 to 20 parts by weight of the second rmixture per lOO parts of the first mixture of t3) from 60 to lOO parts by weight of an acyloxy functional silane of the f o rmul a, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) from O. l to 5 parts by weight of a catalyst selected from the class consistin of zinc salts of carboxylic acid, zirconium salts of carboxylic acid and mi~tures thereof~
Such compositions while having a good cure and a good shelf life.
for extended periods of time such as 18 months to 27 months after they are prepared, nevertheless have an extended tack-free time, such 11;~9~79 60 SI-178 as 40 to 60 minutes. If it is desired to have a low modulus compo-sition with a good shelf life and a good cure after a period of time of 18 months to 27 months, there is utilized in the mixture (B) in the composition above in addition to the acyloxy functional silane a co_ catalyst system. Such a co-catalyst system contains from . 5 to 5 parts by weight of a tin salt of ~ carboxylic acid and from . 001 to . 4 -parts by weight of a co-catalyst selected from the class consisting of a z;nc salt of a carboxylic acid and zirconium salt of a carboxylic acid. As pointed out previously, such a co-catalyst system unlike the first catalyst system has a good shelf life, that is the composition will cure after 18 - Z7 months after it has been prepared and will have a short tack~-free time of 20 minutes or less; unlike the extended tack-free time of the composition of the first catalyst system. One type of tin salt that can be utilized in the co-catalyst system is dibutyltin-dilaurate. A much more preferred tin salt which give the advantageous tack~free time in the instant compositions is dimethyl tin neo-decanoate The preferred zirconium salt is ~irconium octoate while the preferred zinc salt is zinc octoate. Other zinc salts and zirconium salts would operate just as effectively in the instant invention. The above compo- -sitions may contain any of a number of well-known additives as will be described below.
Descriptioll of the Preferred Embodiment The base polymer of the one component room temperature vulcanizable silicone rubber composition of the instant case comprises a silanol terminated diorganopolysiloxane polymer having the viscosity varying from 50, 000 to 350, 000 centipoise at 25 C and more preferably has a 94';r9 6051_~78 viscosity tkat varies lO0, 000 to Z50, 000 centipoise at 25 C.
It should be r~oted of course that the higher the viscosity of the base polymer, the lower the modulus of the resulting composition. The organo groups of said diorganopolysiloxane polymer can be selected from any monovalent hydrocarbon radical and halogenated monovalent hydrocarbon radical. Examples of substituent groups whic~ the or"ano radical can stand for, for instance a~cyl radicals, such as methyl, ethyl, propyl of 1 to 8 carbon atoms; cycloallcyl radicals such as cyclohexyl, cycloheptyL etc. of 4 to 8 carbon atoms; mono_ nuclear aryl radicals such as phenyl, rnethylphenyl, ethylphenyl, etc.;
and alkenyl radicals such as vinyi allyl, etc.
In additioD, the organo groups in such diorganopolysiloxane polymer ca stand for halogenated monovalent hydrocarbon radicals such fluoro-alkyl radicals are for instance 3, 3, 3 trifluoropropyl. Such diorgano-polysiloxane polyrner is preferably lOO(~o a linear diorganopolysiloxane polymer. However, up to 0. 1 by weight of combined monofunctional siloxy units and trifunctional siloxy units can be tolerated in the polymer. This is, the combined monofunctionality and trifunctionality of siloxy units cannot exceed 0.1% by weight. Preferably the linear diorganopolysiloxane polyrner has the formula, where R is selected from mono~alent hydrocarbon radicals and 4~9 60 SI-178 halogenated rnonovalent hydroca.rbon radicals, which are the same as -the radicals given as examples for the organo radicals above and .
where t varies such that the polymer has a ~riscosity varying from 50, 000 to 350l 000 centipoise at 25 C and more preferably has a , -viscosity varying from lO0, 000 to 250, 000 centipoise at 25~C.
The production of such silanol terminated diorganopolysiloxane polyme s --is well-known in the art. Briefly, there istaken diorganodichloro_ silanes with up to lO~lo by weight of monofunctionality or trifunctionality -and the chlorosilanes are hydrolyæed in water. The resulting hydrolyz te ---is then taken and the water separated from it and there is added to it, anywhere from 1 to ~% by weight of potassium hydroxide The hydrolyzate is heated at temperatures of over 100 and preferably 150C for a period of time varying any~rhere from l to 8 hours so as to preferentially form cyclopolysiloxanes.
lt should ~e noted that the hydxolyzate mixture as obtained from the water hydrolysîs contains in it low molecular weight cyclopolysiloxane as well as low molecular weight silanol terminated diorganopolysiloxan polymers. By cracking such a hydrolyzate with potassium hydroxide at elevated temperatures most of the contents of the silicone hydrolyza e is predominately converted to the cyclotetrasiloxanes. The foregoing cyclotetrasiloxanes are then taken and they are mixed together and -there is added to such cyclotetrasiloxanes anywhere from 50 to 500 parts per million of potassium hydroxide and the desired amount of water as a chainstopper. The resulting mixture is then heated at elevated temperatures so as to preferentially form at above 100 and 4'79 ~ ~
more preferably above 150C in an equilibration reaction that desired -silanol terminated diorganopolysiloxane polymer. The final viscosity -of the polymer that is formed -~,vill depend on the amount of water that is added as a chainstopper. The more water that i~ present as a S chainstopper then the lower the moleculare weight of tne silanol terminated diorganopolysiloxane polymer that will be formed. The less water that is added, the higher the molecular weight of the silanol terminated diorganopolysiloxane polymer that will be formed.
In addition to the water there n~ay be utilized as a chainstopper, low molecular weight silanol terminated diorganopolysiloxane polymers, that is the polymers that are obtained when the diorganodichlorosilanes are hydrolyzed in water, may also be used as chainstoppers. When the desired amount of silanol terminated diorganopolysiloxane polymer ha3 been formed in the equilibration reaction, then the alkali metal hydroxide catalyst, that is the potassium hydro~cide is neutralized, and the unrea¢ted cyclics are stripped off to yield the desired base -polymer. , .
It should be noted that the process for forming the silanol terminated diorganopolysiloxane polymer having fluoroalkyl substituted groups Z0 differs from the process or producing the diorganopolysiloxane polyrners having non-halogenated substituent groups in that the fluoro-alkyl substituted polyn~er can be produced both from cyclotrisiloxanes as well as from cyclotetrasilo~sanes. The process of the production of the polymer from the cyclotrisiloxanes is preferred since that results in a maximum conversion of the cyclic trisiloxanes to the desired polymex. S
i4~79 6051-178 ~ ~
In accordance with the present invention there is utiliæed per l00 parts by weight of the base silanol terrninated polymer of from 5 to -l00 parts by weight of a filler and more preferably from 10 to 30 parts -by weight of a filler. Such a filler can be selected from reinforcing fillers or from extending fillers. The reinforcing fillers as is tivell .-knowD, are furlled silica and precipitated silica. The reinforcing ~
the fillers are preferred in/composition, if it is desired to increase the tensile strength of the cured silicone elastomer. The disadvantage of t'~: e reinforcing fillers, however, is that they unduly increase the v;scosity of the uncured composition and decrease its elongation properties.
Such effects can be alleviated by treating the filler as will be --e~plained hereinbelow.
If it is desired to increase the tensile strength of the composition to .-some extent, without unduly increasing the viscosity of the uncured composition and without unduly decreasing the elongation,there may be incorporated an extending filler into the composition in the above con- -centrations. Examples of extending filler s are for instancè titanium dioxide, zirconium silicate, silica aerogel, iron oxide, diatomaceous earth, glass fibers, polyvinyl chloride, ground quartz. Other examples of extending fillers that can be utilized are lithopone, zinc :~
oxide, calcium carbonate, magnesium oxide, chromic oxide, zirconium oxide! aluminum oxide, alpha quartz, calcined clay, carbon, graphite, quartz, cotton s~ thetic fibers, etc.
In accordance with the instant case, it is preferred that the filler that ZS l ~ bt oti zed be of a reinforcing type and ;pecifica11y of fumed ;ilica, ~13947~ 60 SI-178 ' since even a small quantity of such fumed silLca ~ill ; increase the tensile strength.and toughness of the final elastomer sealant.
Further if such fumed silica is utilized i:n small enough quantities, it will not duly decrease the per cent elongation of the cured elastomer to prevent the fi~ller from decreasin~ the per cent elongation of the cured composition and als.o to preyent the fi~ller from increa$~ing the viSCQSity of the uncured compos~tion to undesirable lQ levels~ the filler is preferably treated. Thus, the silica filler may be treated as for example as disclosed in U.S.
Patent No. 2,9,38,009 - dated MaY 24, 1~60 - Lucas with cylicpolysiloxanes. Another method for treating fillers that can be utilized in the invention of the Lnstant case ,is that disclosed in U.S. Patent No. 3,024,126' ~ dated March 6, 1962 Brown.
In add~tion silazane treated fillexs i,n accordance with the disclosure of S~ith`U.S. Patent 3,3,65,743 - dated January 18, 1972 and V.S. Patent No. 3,837,878 - dated September 24, 1974 - Beers are preferred as treated fillers in the inStant inyention However, the most preferred treated filler in the instant i`nyention i.s fumed s-~licR txeated with cyclopoly~siloxanes and more specifically~ with cyclotetrapoly-siloxanes: such as octamethylcyclotetrasiloxane.
The above mixture of filler and silanol terminated diorganopolysiloxane polymer forms the base mixture of the instant composit~on. To anywhere of 100 parts of the base mixture there is added in accordance with the instant inYenti:on from 1 to 20 parts by weight of a cataly~st 3Q mixtuxe wherein the catalys:t mixture is generally composed of a crosslinking ~ 13 -l ~
60 SI~17~
agent, the adhesion promoter and the true catalyst that accelerates the reaction. There is used from l to 20 parts by weight of the catalyst mixture per 100 parts of the base mixture. The mixture of the s;lanol terminated diorganopolysiloxane polymer and filler can -be cousidered to be the first mixture or base rnixture, and preferably there is utilized 1 to 10 parts by weight of the catalyst mixh~re or second mixture per hundred parts by weight of the first mixture and in such catalyst mixture there will be anywhere from 60 to lOO parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 Where R and R' are monovalent hydrocarbon radicals and are preferabl alkyl radicals of 1 to 8 carbon atoms, phenyl radicals and most preferably methyl radicals. The above acyloxy functional silane is the crosslinking agent in the instant composition. The most preferred and most common of such crosslinking agents is, of course, methyltriacetoxy silane. There is no need to explain the workings of such ;~ crosslinking agent or how it is obtained since such is well-know~ to a worker skilled in the art. The catalyst that may be utilized with such acyloxy functional silane crosslinking agent is a tin salt of carboxylic acid such as for instance dibutyl tin dilaurate or tin neodecanoate. However, as stated previously when the compo-sition is desired to be low modulus and there is utili2ed the above tin catalyst, the composition had an imperrnissible shelf life, that is a shelf life of 6 - 9 months and after that time the composition will not cure .
11~ 79 60 SI-178 Accordingly, it was highly unexpected to find a composition that would have an acceptable shelf life by combining in said second mixture with the acyloxy functional silane instead of the tin salt from .1 to 5 parts by weight of a catalyst selected from a class consistirg of .-zinc salts of carboxylic acid and zirconium salts of carboxylic acid and mixtures thereof. Preferably there is used from . 5 to 3 parts by weight of such salts. The preferred catalysts are of course zinc octoates or zirconium octoate.
The only disadvantage with such a composition was that while it had a good shelf life that is, it had a shelf life that would vary any~here from 18 months _ 27 months, nevertheless it had a tack-free time that was long. Thus, the composition could have a tack-free time of anywhere from 30 minutes to 60 minute~ with the foregoing use of the zirconium salt or the zinc salt in place of the tin salt in the composition.
If this i9 acceptable, then the zirconium salt and the zinc salt or mixtures thereof can be utilized as catalysts in the instant composition in place of the traditional tin salts the composition will have a good shelf life although longer than normal tack-free time.
It should be pointed out that the compositions of the prior art, that is the low modul~ls compositions o:f the prior art containing a tin salt therein had a lengthening of tack-free time after the 6 - 9 months of storage to the point where permanent residual surface tack was present after several days cure, that i9 the composition would not become tack-free except after a very long period of time. This is not the case Z 5 ~ With th ns t8nt c ~mpo siti on ~i~ing zir conium s alt s or zinc salts .
11;~9'~'751 6 o Sl- 1 713 After 30 minutes, 60 minutes or at the rnost 2 hours, the cornpositions do becor~e tack-free and the compositions do cure and do have a --shel~ stability in the range of 18 months - 27 months.
It should also be noted that the prior art composition using the low modulus composition, that is the low modulus prior art composition utilizing tin salts as a catalyst would after storage beyond the 9 month --period would have a decrease of total cure so that the material e~ren after a 24 hour cure had a putty like consistency and pressure applied to the material caused permanent deformation. Initially, this e~ect was the notice of loss Shore A Hardness. In the latter stages of aging, the putty-like consistency would remain even after a one month time --at ambient conditions, that is the composit;on was curing 30 slowly that it appeared it wou ld never cure. -The low rnodulus compositiolls of the instant case with zirconium and zinc salts in them in the above concentrations will cure within 24 hours even after a 9 month period in spite of the fact that the tack-free tirne may be as long as 1 hour.
',''.'.-It should be noted that in the second mixture of the catalyst there is preferably used anywhere rom 60 to 100 parts by weight of the cross-linking agent and more preferably from 80 to 100 parts by weight of the ~
crosslinking agent with from generally .1 to 5 parts and more prefer-ably . 5 to 3 parts by weight of the catalyst which is selected frorn zinc salts and the zirconium salts of carboxylic acid.
11;~ 79 60 SI-178 ~urther, in a more preferred embodiment of the instant case, there .
i9 utilized a co-catalyst system with the cross-linking agent, where in the co-catalyst system contains fro.m . 1 to 5 parts by weight of an alkyl tin salt of a carboxylic acid and fro~n . 001 to . 4 pa~ts by weight of a co-catalyst selected from the class consisting of a zinc salt of a carboxylic acid and a zirconium saIt of a carboxylic acid. More preferably, there is utilized as a co-catalys in the system from 0. 01 to 0. 2 parts by weight of the zirlc salt or the zirconium salt of carboxylic acid with from 0.1 to l parts by weight of a dialkyl tin salt of carboxylic acid with the al~cyl group having 1 to 2 carbon atoms . The co- catalyst system of the tim salt with the zirconium or zinc salt is preferred over single catalyst system of the zirconium salt or the zinc salt since the co-catalyst system results in a composition which has good cure after storage varying from 18 months to 27 months with a tack-free time of 15 to 20 minutes. The composition without the combination or co- catalyst system of both the zinc or zirconium salt in combination with a dialkyl tin salt re sults in a composition with a good shelf lie that will produce a good cure after storage fo .
a period of time of 18 - 27 months, but will have a prolonged tack-free time of 30 minutes to 60 minutes or more. The COlnpO-sition with a co- catalyst system of the tin salt in combination with the zirconium salt or zinc salt will have a good shelf life, that is, it will have a good cure at periods of storage of as much as 18 months or as much as 27 months and will also have a short ~ -17_ 11;3~1~'7g 60 51-178 ,ack-free time of 15 minute~ to 30 minutes.
A less preferred tin salt that can be utilized in cornbination with the zinc salt or zirconium salt is for instance dibutyltindialurate.
However, the tin salt that is preferred in the instant compositions is one which has a diallcyl group which is a dial~yl tin soap of a carboxylic acid in which the dailkyl group is selected from dimethyl and the carboxylic acid portion contains anywhere from 2 to 22 carbon atoms and is most preferably neodecanoate.
Accordingly, the most preferred tin salt is dimethyl tin neodecanoat l 0 as the tin salt in combination with the ~inc salt or the zirconium salt in the co-catalyst system oi the instant invention.
Accordingly, to pxepare the compositions of the instant case, the co-catalyst system or the catalyst system is mixed with the acyloxy functional silane and the second mixture is then mixed at a concentration of anywhere from 1 to 20 parts by weight per lO0 parts by weight of the first mixture and the entire mixture is then packed in a moisture-proo~ container. Such a composition is maintained in the anhydrous state until it is desired to cure the composition. Then the composition is appl ied as a sealant in whatever rnanner it is desired and exposed to atmospheric moisture to cure to form an elastomeric silicone sealant.
~ .
It should be noted that even though the composition is disclosed and -claimed in the form of mixing two mixtures, the claims in the disclosuxe of the instant case are directed to a one-componerlt RTV~
,~ -18-1 ~ 9~7~3 60 SI~178 system. All of the ingredients are mixed together into a single mixture and stored as such. When it is desired to utilize the --:
composition or convert it to a silicone elastomer, it is simply taken and exposed to atmospheric moisture either by squeezing frorr~
a tube or being pushed put of a caulking tube, such that it is exposed to atmospheric ~noistur~ whereupon the acyloxy functional -silane wil~ hydrolyze and crosslink to a silicone elastomer. -It should be noted that the clain~ language in the specification dis-cioses the formation of two mixtures which are mixed together to form the single component of the instant composition, since this is how the composition is prepared in practice and also to acilitate the description and recitation of the concentrations thereof of the -ingredients. There are additional ingredierts to the instant composition ancl specifically in the instant composition there are additional ingredients which are pre sent to make the composition a low modulus composition.
As pointed out previously, there is desirably utilized a high viscosit silanol terminated diorganopolysiloxane base polymer in the instant composition so as to lower the modulus of the composition or increase the per cent elongation. In the above cornposition and specifically to decxease the modulus of the composition, there is present int he first mixture of the one component composition of the instant case per 100 parts of the silanol terminated diorgano-polysiloxane polymer of from 0 to 50 parts by weight of a plasticize -which is a diorganopolysiloxane polyrner of a viscosity varying from 1~ 4~79 60 SI-178 10 to 5, 000 centipoise at 25'C where the organo groups are monovalent hydrocarborL radicals.
It should also be noted that the organo groups of such diorgano-polysiloxane polymer are the same as the organo groups of the silanol base polymer.
It should al~o be noted that such diorganopolysiloxane polymer i8 triorganosilylendstopped. It is preferred that the diorganopolysiloxa ~e polymer be strictly linear. However, up to 1% of tri~unctionality and monofunctionality combined is permitted. Generally, there may be utilized f~om 1 to 50 parts by weight of the plasticizer diorganopolysiloxane polymer and more preferably there is utilized anywhere from 20 to 30 p~ rts by weight of diorganopolysilcxane polymer per 100 parts of the silanol terminated diorganopolysiloxane polymer. Further, although the viscos*y of the polymer can vary from 10 to 5, 000 centipoise, it preferably varies anywhere from 10 to 500 centipoise at 25C. The diorganopolysiloxane polym r of which the most preferably type for use in the present invention is a dimethylpolysiloxane polymer of a viscosity varying from 10 to .
500 centipoise at 25 C which is trimethylsiloxy endstopped and whic~
is substantially a linear polymer can be produced by methods well known in the art. Thus, the polymer can be produced by simply hydrolyzing diorganodichlorosilanes with triorganochlorosilanes and separating the resulting fluid that is formed. It can be appreci ted that such a fluid will not be completely linear and may have up to 11;1~'17~ 60 51-178 l % of monofunctional siloxy units and trifunctional siloxy units.
However, such units will not detract from the plasticizing effect -. of the diorganopolysiloxane polymer.
Accordingly, the use of the plasticizer, that is the diorganopolysilo~ ~ne-fluid, having triorganosiloxy endstopped units will decrease the modulus of the composition if utilized i~ the foregoing quantities.
To further decrease the modulus of the composition there may be utilized in the base or first mixt~re per 100 parts by weight of the silanol terminated diorganopolysiloxane polyme r of anywhere from l - 25 parts by weight more preferably 5 - 15 parts by weight of a chainstopping fluid having in it monofunctional siloxy units, difunctional siloxy units and trifunctional siloxy units. Thus, preferably the 1uid is composed of R2 SiO units R33 SiOo 5 units and R3 SiOl 5 units where the ratio of organosiloxy units and diorganosiloxy units varies frorn 0. ll to l. 4, inclusive and the ratio of the triorganosiloxy units and diorganosiloxy units varies from 0. 02 to about l. 0, inclusive and R3 is a monovalent hydro_ carbon radical. It should be noted the term R3 being a Inonovalent hydrocarbon radical intended to include both mono~ralent hydrocarbon radicals and halogenated monovalent hydrocarbon radicals such as 3, 3, 3 trifluoropropyl. The groups for which R3 radical may stand for is much the same as given before in the definition of the organo groups and the R2 groups for the silanol termi~ated diorganc -polysiloxane polymer which is the base polymer in the instant ~`1 ~ 79? 6 0 SI- 17 8 compositions. Such a polymer cornposed of monofunctional, difunctional and trifunctional siloxy lmits will contain anywhere fxom .1 to 8% by weight of nydroxy radicals. Such silicone fluid or chainstopped fluid has two advantages.
. . ,.-}D another aspect, it acts as an adhesion promoter and allows the cured composition to adhere to various types of substrates with better adhesion than would be the case if it was not utilized.
The production of such fluid is also well-known ir~ the art and generally comprises hydrolyzing the appropriate quantities of diorgar~ o-dichlorosilanes with m~noorganotrichlorosilanes and triorganochloro_ silanes in water and then separating and purifying the resulting fluid that is formed. An example of the foregoing f}uid composed o~
the rr,onofunctional siloxy units and difunctional siloxy units and trifunctional siloxy units for use in one part RTV Compositions is disclosed in Beers USP 3, 382, 205.
Use of such fluid to improve the shelf life of one component acylo~y funcL.ional silane RTV compositio ns is disclosed in this patent. However, the use of such lluid in ¦
combination with the other fluids and modifications of the instant case to both lower the modulus of the composition and increase the shelf life is not disclosed in the above Beers Patent.
However, this increase in tensile strength and decrease in modulus is more than offset by the other ingredients and modifications disclosed above to result in a low modulus one component RTV
2~ cornposition with the desired modulus and the desired shelf life.
1 l~i7~ 60 SI-178 , 1,' Finally, there is utilized an adhesion prornoter or an ingredient ~:
which serves primarly as an adhesion promoter ilL the instant ~--cornposition.
..,-,'.
Accordingly, in the seconal mixture or the catalyst mixture there is present arlywhere from 5 to 40 parts by weight of an adhesion promoter which is preferably a ditertiaryalkoxydiacyloxy functional :
silane. More preferably, there is utilized anywhere from 10 to 30 parts by weight of the ditertiaryalkoxydiacyloxy functional -silane. More broadly, there may be utilized a dialkoxydiacyio,~
functional silane as the adhesion promoter. However, it has been found that the ditertiaryalkoxydiacyloxy functional silane s are more effective as adhesion promoters in the instant compositions than is the case with the plain dialkoxysilane ingredients or additive s.
.
Preferably, there is utili~ed ditertiarybutoxydiacytoxysilane as the adhesion promoter in the instant composition which is utilized in the concentration of anywhere from 10 to 30 parts by weight based on 60 - 100 parts by weight of the acyloxy functional silane cross-linking agent whose formula was given previously. This adhesion promoter is disclosed in Kulpa USP 3, 296, 161~ - dated January 3, 1967.
The instant disclosure particularly exemplifies and illustrates the use of such an adhesion promoter in one component acyloxy function Ll RT~J Composition and the instant case is not limited to sush adhesic 39~'7 promoter~. There cas~ be u~ od other adhesion p~osnoters in the ~ I
instant composition. It can be appreciated also there can be -utilized other plasticizers other than the triorganosilylendstopped -diorganopolysiloxane polymers which are utilized as plasticizers ---in the instant case. In additio4 there can ~e util~7.ed other chainstopping fluids other than the fluid composed of monofunctional siloxy units and difunctional siloxy units and trifunctional siloxy unit~, as disclosed in the above specification. The above ingredienl s and additives have been specified since that resul ts in a composi- ~::
tion with competitive low modulus properties, which has a good shelf life that has a good cure after periods of time of storage of as long as 18 months or as long as Z7 months and in which l, the foregoing catalyst, that is zinc salt or zirconium salt catalyts f-are utilized by themselves or more pre~erably the tin catalyst -is used in combination with the zirconiurn salt and zinc salt in the co-catalyst system which is the preferred system of the instant -ca se .
It should be noted that while variations may be made in the above compositiQn, it i9 the above composition with the ingredients define above both in the broad sense and in the more limiting sense that discloses a one component RTV low modulus composition with acceptable sheLf life in pe2iods of time varying frorn 18 months -Z7 months of storage.
60S~-178 Accordingly, even though a good many of the additives of the instant case are disclosed for utilization in one component RTV
compositions by the prior art, it was not disclosed by the prior art the optinaum combination of ingredients of the instant case for producing a composition both of low modulus and good tensile strength properties and a cornposition having good shelf Iife after a period of storage of l 8 months - 27 months ater manufacture and ha~ing a ~ood cure after that time.
The Examples below are given for the purpose of illustrating the present invention and are not given for any purpose or reason to set limits or definitions as to the extent of the instant invention or the extent of the instant claims. All parts in the examples are by weight unless specified otherwise. ;.-EXAMP LE I
There was prepared base compounds X, ZX and 3X comprising ¦ taking a dimethylpolysiloxane polymer which was silanol stopped and which had the viscosity shown in the table below (Table I) and there was mixed with it the stated quantities of fumed silica treated with octamethylcyclotetrasiloxane, the dimethyl polysiloxane oil7 which is trimethylsiloxy endstopped of 100 centipoise viscosity at 25 C. There was added to the mixture the stated quantities of such an oil and in addition there was added to the mixture thë
silicone oil composed of trimethylsiloxymonofunctional siloxy units, difunctlonal siloxy units and methyltrifunctional silo y units li;~9'~ Y 60 5~- 1 7~
which silicone fluid had a . 5 weight per cerlt hydroxy content as indicated in Table I below. The foregoing type s of ingredients were combined i~ the quantities set forth in Table I below. To the base compou~d there was added the amount of the catalyst S a~d the concent2ation of the catalyst in the second mixture of the crosslinking agent, adhesion promoter a:nd catalyst ingredients as set forth in Table I below. The compositions had the following properties as set forth in Table I below, TABLE
Achievement o Low Modulus Characteristics, and Improved Toughne s Factor (Tensile Product). Parts by Wei ht ( bw) ~ P . _ A. Base ComPound __ A dimethyl silanol stopped 15 polymer viscosity at 25 C 10, 000 100, 000 100, 000 pbw level 100. pbw 100, pbw 100. pbw Fumed si7 i ca t. eated wit h octz--methylcyclotetrzsiloxane 20,pbw 18. 5pbw 18. 5pbw Dimethylpolysiloxane oil o 100 20 centipoise at 25c C - - - 25. pbw 25. pbw Silicone oil co;~posed of (CH3)3 sioo 5 units 15, pbw 8. pbw 8. pbw (CH3)2SiO units and CH3SiO1 5 units with 0. 2 wt. % hydroxy groups 2 5 B, Cataly st Amount of catalyst mixture per 4. 2 3. 9 4. 2 100 pts of base - Level (pbw on base) F o ;: mula Methyltriacetoxysilane 80. pbw 80. pbw 80~ pbw Ditertiarybutoxydiaceto~ysilane 20. pbw 20. pbw 20. pbw Dibutyl tin dilaurate 0. 60pbw 0, 60pbw _ _ _ l)imethyl tin neodecanoate - - - - - - 0. 525pb Zirconium octoate (12% Zr) - _ 0. 120pb; J
9'17~ ~
TABLE I - continued -C . P ropertie s App}ication Rate, gm,l min.270. 74. 100.
Taclc-free Time, minutes 15. 35. 20.
Cure Condition 24 hrs. / RTGood Good Good ASTM Sheet Physicals . -Shore A 34 17 20 -Tensile, psi 350 300 360 -Elongatio~, % 400 930 860 --Tensile Product (x10-3) 144. 279. 310.
S e cant Modulu s, p si 0.25 in.tin. 232. - - ~ 136. -1. 00 in.lin. 122. - - - 60. :-
1 l~i7~ 60 SI-178 , 1,' Finally, there is utilized an adhesion prornoter or an ingredient ~:
which serves primarly as an adhesion promoter ilL the instant ~--cornposition.
..,-,'.
Accordingly, in the seconal mixture or the catalyst mixture there is present arlywhere from 5 to 40 parts by weight of an adhesion promoter which is preferably a ditertiaryalkoxydiacyloxy functional :
silane. More preferably, there is utilized anywhere from 10 to 30 parts by weight of the ditertiaryalkoxydiacyloxy functional -silane. More broadly, there may be utilized a dialkoxydiacyio,~
functional silane as the adhesion promoter. However, it has been found that the ditertiaryalkoxydiacyloxy functional silane s are more effective as adhesion promoters in the instant compositions than is the case with the plain dialkoxysilane ingredients or additive s.
.
Preferably, there is utili~ed ditertiarybutoxydiacytoxysilane as the adhesion promoter in the instant composition which is utilized in the concentration of anywhere from 10 to 30 parts by weight based on 60 - 100 parts by weight of the acyloxy functional silane cross-linking agent whose formula was given previously. This adhesion promoter is disclosed in Kulpa USP 3, 296, 161~ - dated January 3, 1967.
The instant disclosure particularly exemplifies and illustrates the use of such an adhesion promoter in one component acyloxy function Ll RT~J Composition and the instant case is not limited to sush adhesic 39~'7 promoter~. There cas~ be u~ od other adhesion p~osnoters in the ~ I
instant composition. It can be appreciated also there can be -utilized other plasticizers other than the triorganosilylendstopped -diorganopolysiloxane polymers which are utilized as plasticizers ---in the instant case. In additio4 there can ~e util~7.ed other chainstopping fluids other than the fluid composed of monofunctional siloxy units and difunctional siloxy units and trifunctional siloxy unit~, as disclosed in the above specification. The above ingredienl s and additives have been specified since that resul ts in a composi- ~::
tion with competitive low modulus properties, which has a good shelf life that has a good cure after periods of time of storage of as long as 18 months or as long as Z7 months and in which l, the foregoing catalyst, that is zinc salt or zirconium salt catalyts f-are utilized by themselves or more pre~erably the tin catalyst -is used in combination with the zirconiurn salt and zinc salt in the co-catalyst system which is the preferred system of the instant -ca se .
It should be noted that while variations may be made in the above compositiQn, it i9 the above composition with the ingredients define above both in the broad sense and in the more limiting sense that discloses a one component RTV low modulus composition with acceptable sheLf life in pe2iods of time varying frorn 18 months -Z7 months of storage.
60S~-178 Accordingly, even though a good many of the additives of the instant case are disclosed for utilization in one component RTV
compositions by the prior art, it was not disclosed by the prior art the optinaum combination of ingredients of the instant case for producing a composition both of low modulus and good tensile strength properties and a cornposition having good shelf Iife after a period of storage of l 8 months - 27 months ater manufacture and ha~ing a ~ood cure after that time.
The Examples below are given for the purpose of illustrating the present invention and are not given for any purpose or reason to set limits or definitions as to the extent of the instant invention or the extent of the instant claims. All parts in the examples are by weight unless specified otherwise. ;.-EXAMP LE I
There was prepared base compounds X, ZX and 3X comprising ¦ taking a dimethylpolysiloxane polymer which was silanol stopped and which had the viscosity shown in the table below (Table I) and there was mixed with it the stated quantities of fumed silica treated with octamethylcyclotetrasiloxane, the dimethyl polysiloxane oil7 which is trimethylsiloxy endstopped of 100 centipoise viscosity at 25 C. There was added to the mixture the stated quantities of such an oil and in addition there was added to the mixture thë
silicone oil composed of trimethylsiloxymonofunctional siloxy units, difunctlonal siloxy units and methyltrifunctional silo y units li;~9'~ Y 60 5~- 1 7~
which silicone fluid had a . 5 weight per cerlt hydroxy content as indicated in Table I below. The foregoing type s of ingredients were combined i~ the quantities set forth in Table I below. To the base compou~d there was added the amount of the catalyst S a~d the concent2ation of the catalyst in the second mixture of the crosslinking agent, adhesion promoter a:nd catalyst ingredients as set forth in Table I below. The compositions had the following properties as set forth in Table I below, TABLE
Achievement o Low Modulus Characteristics, and Improved Toughne s Factor (Tensile Product). Parts by Wei ht ( bw) ~ P . _ A. Base ComPound __ A dimethyl silanol stopped 15 polymer viscosity at 25 C 10, 000 100, 000 100, 000 pbw level 100. pbw 100, pbw 100. pbw Fumed si7 i ca t. eated wit h octz--methylcyclotetrzsiloxane 20,pbw 18. 5pbw 18. 5pbw Dimethylpolysiloxane oil o 100 20 centipoise at 25c C - - - 25. pbw 25. pbw Silicone oil co;~posed of (CH3)3 sioo 5 units 15, pbw 8. pbw 8. pbw (CH3)2SiO units and CH3SiO1 5 units with 0. 2 wt. % hydroxy groups 2 5 B, Cataly st Amount of catalyst mixture per 4. 2 3. 9 4. 2 100 pts of base - Level (pbw on base) F o ;: mula Methyltriacetoxysilane 80. pbw 80. pbw 80~ pbw Ditertiarybutoxydiaceto~ysilane 20. pbw 20. pbw 20. pbw Dibutyl tin dilaurate 0. 60pbw 0, 60pbw _ _ _ l)imethyl tin neodecanoate - - - - - - 0. 525pb Zirconium octoate (12% Zr) - _ 0. 120pb; J
9'17~ ~
TABLE I - continued -C . P ropertie s App}ication Rate, gm,l min.270. 74. 100.
Taclc-free Time, minutes 15. 35. 20.
Cure Condition 24 hrs. / RTGood Good Good ASTM Sheet Physicals . -Shore A 34 17 20 -Tensile, psi 350 300 360 -Elongatio~, % 400 930 860 --Tensile Product (x10-3) 144. 279. 310.
S e cant Modulu s, p si 0.25 in.tin. 232. - - ~ 136. -1. 00 in.lin. 122. - - - 60. :-
3.00 in./in. _ _ _ _ _ _ 39 D. 180 Peel Adhesion - 10 day Room Temperature Cure .. ...
Note: - All values - (lb./ in. )/ (% Cohesive Failure) -Substrate X 2X 3X
Anodized Aluminum 17/ ~ 5% 45/ 15% 75! 85%
304 Stainless Steel 71/ 100% 70/ 60% 72/ 100% --E. 180 Peel Ad~lesion - 10 day/ E~oom Temperature Cure plus 7 day/ l~oom Temperature/ H20 immersior Note: - All values (lb. per inch) / (% Cohesive Failure) Sub strate X 2X 3X
___ .
25Anodized Aluminum <2/ 0% 6/ 0% ~30/ 100%
304 Stainless Steel ~2/ 0% 60/ 60% ~30/ 100%
F. Accelerated A~in~ Data Note - All Values: Tack-free Time/ Cure Condition at 24 hrs 100 C Accelerated Aging 30Time (hours) X 2X 3X
_ 24 15 min/ g ood - - - - _ - -32 _ _ _ ~60 min/poor 20'/good -~
48 - / g ood - - _ _ _ _ 30 min/ good ~ _ _ 27_ 9':~'79 60 51-178 The ~alues in Table I above indicate the co~nposition with the ~owest modulus and a good shelf life or a good rate of cure after accelerat d '-aging only when the catalyst system of the instant case was utilized.
There wa3 obtained a system with low modulus, good tensile -properties and good curing after aging only with the irgredients and the catalyst system of the insta~t case was utilized in the compo-sition. There was prepared a performance comparison of Composition 3X with a prior art sealant. The results are as follows:
l 0 TAB LE TT
Co arison with High Performance Competitive Material rnp, , ~~ :
Property Prior Art Sealant 3 X
A. Application Properties Application Rate, grn,/ min. 146 lOZ
l 5 Tack-free Time, min. 25 20 B Initial Physieals .
Shore A ~ardness 25 20 Tensile, psi 190 360 Elongation, % 810 860 Tensile Product (x10-3) 154 310 C. Heat Aged Physicals (24 hr./480F) Shore A Hardness 51 43 Tensile, psi 100 170 Elongation, % 50 93 Tensile Product (x10-3) 5 o 16. 0 Weight Loss, %, stability of 4. 1 4. 6 material addition of 2 did not destabiliæe system -D. Adhesion, l 80 Peel F ailur e .Failur Subst~ate Lb. / in. (% Cohesive) Lb. / in. ~% Coh s ..
Anodized Aluminum 66 lO0 75 85 '7~ 60 51-178 The results above indicate the Composition 3X, the composition of .
the instant case has superior low modulus and cured properties .", with re spe ct to the prior art sealant.
EXAMP LE II
There was prepared the base Compositions 4X, 5X, 6X, 7X and 8X .,.
as indicated in Table III beIow, comprisirlg forming the ba se -.
compound by mixing 100 parts by weight of silanol terminated di-methylpolysiloxane which was a blend of dimethylpolysiloxanes such ,., that the blend had an end viscosity of 80, 000 centipoise at 25C
and such that the Composition 8X was a blend of silanol terminated .,, dimethylpolysiloxanes that had an end viscosity of 95, 000 centipoise .
at 25C. To such silanol polymers there was added 15. 5 parts ., by weight of fDed silica treated with octamethylcyclotetrasiloxane 22, 0 parts by weight of a trimethylsiloxy endstopped dimethylpoly- .,.
siloxane oil of 100 centipoise viscosity at 25D5 and 6. 5 parts of a silicone oil fluid composed of trimethylmonofunct ional siloxy units, -dimethyldifunctional siloxy units and monomethyltrifunctional siloxy units in which the polynaer contained . 5 weight per cent of hydroxy groups. To the above base compounds there was added the amount .
of catalyst mixture as well as ingredients of the catalyst mixture -shown in Table III below. The results of initial cure and .-accelerated aging cure to determine shelf life of the compositi,ons is indicated in Table III below.
~ 9 ~ 7~ 6 0 SI - 17 8 o~ 1.
a~l 3 O ~ \ ~ ~ o ' , u~ ~ , o~~ I C2~ O ~
~ . , ~1 ~ 3 3O ' ' ' o o ~
~ o~,,, ` o , 3 l 3 ;) ~
~1 u~ I o i , ~ , , , , u- ~ ,,' _ h ~ O
3 o 1 3 ~ ) _ ~3 33 a~ .
~1 ~3 ~ ~ ~ ~ C ~ ~ O ~
v O ~ . U~ O U~ O O I ~ I ~D O :~ :' rC ~ O U~ ~ ~O O O I I I O U~ ~ .' 3 O r~ ~ x (~ ~
r~ .~ ~ , O
a ~ o L~ ~ ~
_30- .
11391'7~ 60 sl-17a xl e _ 31.- . ' ~ :113~'}79 The results of Table III indicate that Compositions which were cataly~ed only with tin soaps had good initial cure and good initial tack-free time, but had very poor cure upon accelerzted aging while compositions cured solely with zirconiurn octoate, that is 7X or ~inc octoate, that is 8X had long initial tack-free time, but good initial cures and had upon accelerated aging long tack-free -time that is 40 minutes or so, but good cures after such accelerated aging. The results of Table III substantiate the zinc octoate and zirconium octoate, that is zinc salts and zirconiurn salts or carboxylic acid were good catalyst for the low modulus compositions of the instant case and provided good shelf life to the composition.
EXAMP LE III
There was prepared a base compound comprlsing 100 parts by weight of a silanol terminated dimethylpolysiloxane oil fluid o~ -112, 000 centipoise viscosity at 25'C, 18 5 parts by weight of a -fumed silica treal:ed with octamethylcyclotetrasiloxane, 25 parts by weight of a trimethyl siloxy endstopped dimethylpolysiloxane oil r of 100 centipoise viscosity at 25 C and 8 parts by weight of a silicone oil composed of trimethylmonofunctional siloxy units, dimethyldifunctional siloxy units and rnonomethyltrifunctional siloxy units with . 5 weight percent of hydroxy groups. To the resulting mi~cture there was added the amount of catalyst mixture and types of ingredients and amounts of i~gredients in the catalyst mixture shown in Table IV below. The compositions, one of which is the X Composition of Exampl~ s compared with the s dghtly differen~
~ 3~4~7~
composition, ga~re the following tack-free time and cure rates and cures upon initially being cured and upon being cured after accelerated aging as indicated in Table IV below.
TABLE IV
Ffect of Co~nbinations of Dimethyl Tin Neodecanoate and Zinc or_Zirconium Soap - Parts by Weight_(pbw) __ 1, Formulation A. Base Compound (All Formulatiorls) Silanol terminated dimethylpolysiloxane 112, 000 cps. viscosity at 25~C 100pbw Fumed silica treated octamethylcyclotetra-siloxane 18. 5pbw Dimethylpolysiloxane oil of 100 centipoise viscosity at 25C 25. ~pbw - 15 Silicone oil composed (CH3)3SiOo 5 units, (CH3)2Si0 units and (CH3)Si01 5 units O. 5 weight % of hydroxy groups 8. Opbw B. Catalyst 1. Formula 9X 3X
Methyltriacetoxysilane 80. 80.
Ditertiarybutoxy~<diacetoxysilane 20. 20.
Zirconium Octoate (12% Zr) - - 0.120 Zinc Octoate 0. 075 _ _ _ Dimethyl tin neodecanoate 0, 525 0. 525 2. LeYel Wt. % of catalyst mixtures 5. 0 5. 0 per 100 pts of Base Compound 2. Properties - Accelerated Age Initial Tack-free time, minutes 15 Z0 Cure Condition good cure good cure Accelerated Age, 32 hrs/ 100 C
_ Tack-free time, minutes 14 20 Cure Condition good cure good cure l I li;~9~1'79 ~o 5~-178 The above re sults in Table I~l show that the low modulus compo-sitions of the instant case which were cured with the combinatiou o zinc octoate and dimethyl tin neodecanoate or zirconium octoate or a combination of zirconium octoate and dimethyl tin neodecanoate resulted in compositions with good tack-free times, that is tack-free times in the neighborhood of 15 - 20 minutes and good cure s both on being cured initia~ly upon being prepared or upon being cured after accelexated aging indicating that both compositions had good shelf life. The above results indicate that there is ~.
obtained good low modulus compositions having good tensile properties as well as compositions having good acceptable tack-free time s and long shelf life .
Note: - All values - (lb./ in. )/ (% Cohesive Failure) -Substrate X 2X 3X
Anodized Aluminum 17/ ~ 5% 45/ 15% 75! 85%
304 Stainless Steel 71/ 100% 70/ 60% 72/ 100% --E. 180 Peel Ad~lesion - 10 day/ E~oom Temperature Cure plus 7 day/ l~oom Temperature/ H20 immersior Note: - All values (lb. per inch) / (% Cohesive Failure) Sub strate X 2X 3X
___ .
25Anodized Aluminum <2/ 0% 6/ 0% ~30/ 100%
304 Stainless Steel ~2/ 0% 60/ 60% ~30/ 100%
F. Accelerated A~in~ Data Note - All Values: Tack-free Time/ Cure Condition at 24 hrs 100 C Accelerated Aging 30Time (hours) X 2X 3X
_ 24 15 min/ g ood - - - - _ - -32 _ _ _ ~60 min/poor 20'/good -~
48 - / g ood - - _ _ _ _ 30 min/ good ~ _ _ 27_ 9':~'79 60 51-178 The ~alues in Table I above indicate the co~nposition with the ~owest modulus and a good shelf life or a good rate of cure after accelerat d '-aging only when the catalyst system of the instant case was utilized.
There wa3 obtained a system with low modulus, good tensile -properties and good curing after aging only with the irgredients and the catalyst system of the insta~t case was utilized in the compo-sition. There was prepared a performance comparison of Composition 3X with a prior art sealant. The results are as follows:
l 0 TAB LE TT
Co arison with High Performance Competitive Material rnp, , ~~ :
Property Prior Art Sealant 3 X
A. Application Properties Application Rate, grn,/ min. 146 lOZ
l 5 Tack-free Time, min. 25 20 B Initial Physieals .
Shore A ~ardness 25 20 Tensile, psi 190 360 Elongation, % 810 860 Tensile Product (x10-3) 154 310 C. Heat Aged Physicals (24 hr./480F) Shore A Hardness 51 43 Tensile, psi 100 170 Elongation, % 50 93 Tensile Product (x10-3) 5 o 16. 0 Weight Loss, %, stability of 4. 1 4. 6 material addition of 2 did not destabiliæe system -D. Adhesion, l 80 Peel F ailur e .Failur Subst~ate Lb. / in. (% Cohesive) Lb. / in. ~% Coh s ..
Anodized Aluminum 66 lO0 75 85 '7~ 60 51-178 The results above indicate the Composition 3X, the composition of .
the instant case has superior low modulus and cured properties .", with re spe ct to the prior art sealant.
EXAMP LE II
There was prepared the base Compositions 4X, 5X, 6X, 7X and 8X .,.
as indicated in Table III beIow, comprisirlg forming the ba se -.
compound by mixing 100 parts by weight of silanol terminated di-methylpolysiloxane which was a blend of dimethylpolysiloxanes such ,., that the blend had an end viscosity of 80, 000 centipoise at 25C
and such that the Composition 8X was a blend of silanol terminated .,, dimethylpolysiloxanes that had an end viscosity of 95, 000 centipoise .
at 25C. To such silanol polymers there was added 15. 5 parts ., by weight of fDed silica treated with octamethylcyclotetrasiloxane 22, 0 parts by weight of a trimethylsiloxy endstopped dimethylpoly- .,.
siloxane oil of 100 centipoise viscosity at 25D5 and 6. 5 parts of a silicone oil fluid composed of trimethylmonofunct ional siloxy units, -dimethyldifunctional siloxy units and monomethyltrifunctional siloxy units in which the polynaer contained . 5 weight per cent of hydroxy groups. To the above base compounds there was added the amount .
of catalyst mixture as well as ingredients of the catalyst mixture -shown in Table III below. The results of initial cure and .-accelerated aging cure to determine shelf life of the compositi,ons is indicated in Table III below.
~ 9 ~ 7~ 6 0 SI - 17 8 o~ 1.
a~l 3 O ~ \ ~ ~ o ' , u~ ~ , o~~ I C2~ O ~
~ . , ~1 ~ 3 3O ' ' ' o o ~
~ o~,,, ` o , 3 l 3 ;) ~
~1 u~ I o i , ~ , , , , u- ~ ,,' _ h ~ O
3 o 1 3 ~ ) _ ~3 33 a~ .
~1 ~3 ~ ~ ~ ~ C ~ ~ O ~
v O ~ . U~ O U~ O O I ~ I ~D O :~ :' rC ~ O U~ ~ ~O O O I I I O U~ ~ .' 3 O r~ ~ x (~ ~
r~ .~ ~ , O
a ~ o L~ ~ ~
_30- .
11391'7~ 60 sl-17a xl e _ 31.- . ' ~ :113~'}79 The results of Table III indicate that Compositions which were cataly~ed only with tin soaps had good initial cure and good initial tack-free time, but had very poor cure upon accelerzted aging while compositions cured solely with zirconiurn octoate, that is 7X or ~inc octoate, that is 8X had long initial tack-free time, but good initial cures and had upon accelerated aging long tack-free -time that is 40 minutes or so, but good cures after such accelerated aging. The results of Table III substantiate the zinc octoate and zirconium octoate, that is zinc salts and zirconiurn salts or carboxylic acid were good catalyst for the low modulus compositions of the instant case and provided good shelf life to the composition.
EXAMP LE III
There was prepared a base compound comprlsing 100 parts by weight of a silanol terminated dimethylpolysiloxane oil fluid o~ -112, 000 centipoise viscosity at 25'C, 18 5 parts by weight of a -fumed silica treal:ed with octamethylcyclotetrasiloxane, 25 parts by weight of a trimethyl siloxy endstopped dimethylpolysiloxane oil r of 100 centipoise viscosity at 25 C and 8 parts by weight of a silicone oil composed of trimethylmonofunctional siloxy units, dimethyldifunctional siloxy units and rnonomethyltrifunctional siloxy units with . 5 weight percent of hydroxy groups. To the resulting mi~cture there was added the amount of catalyst mixture and types of ingredients and amounts of i~gredients in the catalyst mixture shown in Table IV below. The compositions, one of which is the X Composition of Exampl~ s compared with the s dghtly differen~
~ 3~4~7~
composition, ga~re the following tack-free time and cure rates and cures upon initially being cured and upon being cured after accelerated aging as indicated in Table IV below.
TABLE IV
Ffect of Co~nbinations of Dimethyl Tin Neodecanoate and Zinc or_Zirconium Soap - Parts by Weight_(pbw) __ 1, Formulation A. Base Compound (All Formulatiorls) Silanol terminated dimethylpolysiloxane 112, 000 cps. viscosity at 25~C 100pbw Fumed silica treated octamethylcyclotetra-siloxane 18. 5pbw Dimethylpolysiloxane oil of 100 centipoise viscosity at 25C 25. ~pbw - 15 Silicone oil composed (CH3)3SiOo 5 units, (CH3)2Si0 units and (CH3)Si01 5 units O. 5 weight % of hydroxy groups 8. Opbw B. Catalyst 1. Formula 9X 3X
Methyltriacetoxysilane 80. 80.
Ditertiarybutoxy~<diacetoxysilane 20. 20.
Zirconium Octoate (12% Zr) - - 0.120 Zinc Octoate 0. 075 _ _ _ Dimethyl tin neodecanoate 0, 525 0. 525 2. LeYel Wt. % of catalyst mixtures 5. 0 5. 0 per 100 pts of Base Compound 2. Properties - Accelerated Age Initial Tack-free time, minutes 15 Z0 Cure Condition good cure good cure Accelerated Age, 32 hrs/ 100 C
_ Tack-free time, minutes 14 20 Cure Condition good cure good cure l I li;~9~1'79 ~o 5~-178 The above re sults in Table I~l show that the low modulus compo-sitions of the instant case which were cured with the combinatiou o zinc octoate and dimethyl tin neodecanoate or zirconium octoate or a combination of zirconium octoate and dimethyl tin neodecanoate resulted in compositions with good tack-free times, that is tack-free times in the neighborhood of 15 - 20 minutes and good cure s both on being cured initia~ly upon being prepared or upon being cured after accelexated aging indicating that both compositions had good shelf life. The above results indicate that there is ~.
obtained good low modulus compositions having good tensile properties as well as compositions having good acceptable tack-free time s and long shelf life .
Claims (34)
1. A low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (A) a first mixture of (1) 100 parts by weight of a silanol terminated diorgano-polysiloxane polymer with a viscosity varying from 50,000 to 350,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to 100 parts by weight of a filler; and (B) a second mixture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts of the first mixture of (3) from 60 to 100 parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) from 0.1 to 5 parts by weight of a catalyst selected from the class consisting of zinc salt of carboxylic acid and zirconium salt of carboxylic acid and mixtures thereof.
2. The composition of Claim 1 wherein the filler is selected from the class consisting of fumed silica and precipitated silica.
3. The composition of Claim 1 wherein the filler is treated with a cyclotetrapolysiloxane.
4. The composition of Claim 1 wherein there is utilized in the first mixture from 1 to 50 parts by weight of a plasticizer which is diorganopolysiloxane polymer of a viscosity varying from 10 to 5,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals.
5. The composition of Claim 4 wherein the diorganopolysiloxane polymer is dimethylpolysiloxane.
6. The composition of Claim 1 wherein there is present from 1 to 15 parts by weight in the second mixture of chainstopping fluid having (R3)2SiO units, R3SiO0.5 units and R3SiO1.5 units where the ratio of organosiloxy units to diorganosiloxy units varies from about 0.11 to 1. 4, inclusive and the ratio of the triorgano-siloxy units to diorganosiloxy units varies from 0. 02 to about 1. 0, inclusive and R3 is a monovalent hydrocarbon radical.
7. The composition of Claim 1 wherein in the second mixture there is present from 5 to 40 parts by weight of an adhesion promoter which is a ditertiaryalkoxydiacyloxy functional silanes.
8. The composition of Claim 7 wherein the ditertiaryalkoxy-diacyloxy functional silane is ditertiarybutoxydiacytoxysilane.
9. The composition of Claim 1 wherein in the second mixture the zinc salt is zinc octoate and is utilized at a concentration of 0.5 to 3 parts by weight.
10. The composition of Claim 1 wherein in the second mixture the zirconium salt is zirconium octoate and is used at a concentration of 0.5 to 3 parts by weight.
11. A process for forming a low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (a) mixing (A) a first mixture of (1) 100 parts by weight.
of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50,000 to 350,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (23 from 5 to 100 parts by weight of a filler with a (B) second mix-ture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts of the first mixture of (3) from 60 to 100 parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) from 0.1 to 5 parts by weight of a catalyst selected from the class consisting of zinc salt or carboxylic acid and zirconium salt of carboxylic acid and mixtures thereof and (6) allowing the first mixture to cure in the presence of atmospheric moisture.
of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50,000 to 350,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (23 from 5 to 100 parts by weight of a filler with a (B) second mix-ture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts of the first mixture of (3) from 60 to 100 parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) from 0.1 to 5 parts by weight of a catalyst selected from the class consisting of zinc salt or carboxylic acid and zirconium salt of carboxylic acid and mixtures thereof and (6) allowing the first mixture to cure in the presence of atmospheric moisture.
12. The process of Claim 11 wherein the filler is selected from the class consisting of fumed silica and precipitated silica.
13. The process of Claim 11 wherein the filler is treated with a cyclotetrapolysiloxane.
14. The process of Claim 11 wherein there is utilized in (A) from 1 to 50 parts by weight of a plasticizer which is a diorgano-polysiloxane polymer of a viscosity varying from 10 to 5,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals.
60 Si-178
60 Si-178
15. The process of Claim 14 wherein the diorganopolysiloxane polymer is dimethylpolysiloxane.
16. The process of Claim 11 where there is present from 1 to 25 parts by weight in the first mixture (A) of a chainstopping fluid having (R3) SiO units, R? SiO0.5 units and R3SiO1.5 units where the ratio of organosiloxy units to diorganosiloxy units varies from 0.11 to 1.4, inclusive and the ratio of the triorganosiloxy units to diorganosiloxy units varies from 0. 02 to about 1.0, inclusive, and R3 is a monovalent hydrocarbon radical.
17. The process of Claim 11 wherein in the second mixture (b) there is present from 5 to 40 parts by weight of an adhesion promoter is ditertiaryalkoxydiacyloxy functional silane.
18. The process of Claim 17 wherein the ditertiaryalkoxydiacyloxy functional silane is ditertiarybutoxydiacytoxysilane.
19. The process of Claim 11 wherein in the second mixture the zinc salt is zinc octoate and is utilized at a concentration of 0. 5 to 3 parts by weight.
20. The process of Claim 11 wherein in mixture (B) the zirconium salt is zirconium octoate and is cured at a concentration of 0. 5 to 3 parts by weight.
21. A low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (a) a first mixture of (1) 100 parts by weight of a silanol terminated diorgano-polysiloxane polymer with a viscosity varying from 50,000 to 350, 000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to 100 parts by weight of a filler; and (B) a second mixture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts of the first mixture of (3) from 60 to 100 parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) a co-catalyst system containing from 0.1 to 5 parts by weight of a dialkyl tin salt of a carboxylic acid with the alkyl group having 1 to 2 carbon atoms and from 0. 001 to 0. 4 parts by weight of a co-catalyst selected from the class consisting of a zinc salt of a carboxylic acid and zirconium salt of a carboxylic acid.
22. The composition of Claim 21 wherein the filler is selected from the class consisting of fumed silica and precipitated silica.
23. The composition of Claim 21 wherein the filler is treated wit a cyclotetrapolysiloxane.
24. The composition of Claim 21 wherein there is utilized in (A) from 1 to 50 parts by weight of a plasticizer which is a diorganopolysiloxane of a viscosity varying from 10 to 5,000 centipoise at 25°C where the organo groups are monovalent hydro-carbon radicals.
25. The composition of Claim 24 wherein the diorganopolysiloxane polymer is dimethylpolysiloxane.
26. The composition of Claim 21 wherein there is present from 1 to 25 parts by weight in the second mixture of a chainstopping fluid having (R3)2SiO units, R3SiO0.5 units, and R3SiO1.5 units where the ratio of organosiloxy units to diorganosiloxy units varies from about 0.11 to 1.4, inclusive and the ratio of the triorgano-siloxy units to diorganosiloxy units varies from 0.02 to about 1.0, inclusive and R3 is a monovalent hydrocarbon radical.
27. The composition of Claim 21 wherein in the second mixture there is present from 5 to 40 parts by weight of an adhesion promoter which is a ditertiaryalkoxydiacyloxy functional silane.
28. The composition of Claim 27 wherein the ditertiaryalkoxy-diacyloxy functional silane is ditertiaryhutoxydiacytoxy silane.
29. The composition of Claim 21 wherein in the second mixture the zinc salt is zinc octoate and is utilized at a concentration of 0.01 to 0.2 parts by weight.
30. The composition of Claim 21 wherein in the second mixture the zirconium salt is zirconium octoate and is utilized at a concen-tration of 0.01 to 0.2 parts by weight.
31. The composition of Claim 21 wherein in the second mixture, he tin salt is dibutyl tin dilaurate and is utilized at a concentration of 0.1 to 1.0 parts by weight.
32. The composition of claim 21 wherein in the second mixture the tin salt is dimethyl tin neodecanoate and it utilized at a concentration of 0.1 to 1.0 parts by weight.
33. A process for forming a low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprised of mixing (A) a first mixture of (1) 100 parts by weight of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50,000 to 350,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to 100 parts by weight of a filler; with (B) second mixture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts by weight of an acyloxy functional silane of the formula, R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) a co-catalyst system containing from 0.1 to 5 parts by weight of a dialkyl tin salt of a carboxylic acid where the alkyl group has 1 to 2 carbon atoms and from 0.001 to 0.4 parts by weight of a co-catalyst selected from the class consisting of a zinc salt of carboxylic acid and a zirconium salt of a carboxylic acid and (5) allowing the final mixture to cure in the presence of atmospheric moisture.
34. A low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (A) a first mixture of (1) 100 parts by weight of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50,000 to 350,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to 100 parts by weight of a filler; and (B) a second mixture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts of the first mixture of (3) from 60 to 100 parts by weight of an acyloxy functional silane of the formula,
34. A low modulus room temperature vulcanizable silicone rubber composition with a good shelf life comprising (A) a first mixture of (1) 100 parts by weight of a silanol terminated diorganopolysiloxane polymer with a viscosity varying from 50,000 to 350,000 centipoise at 25°C where the organo groups are monovalent hydrocarbon radicals; (2) from 5 to 100 parts by weight of a filler; and (B) a second mixture where there is utilized from 1 to 20 parts by weight of the second mixture per 100 parts of the first mixture of (3) from 60 to 100 parts by weight of an acyloxy functional silane of the formula,
Claim 34 continued:
R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) one of the group selected from:
(i) a catalytic system containing from 0.1 to 5 parts by weight of a catalyst selected from the class consisting of zinc salt of carboxylic acid and zirconium salt of carboxylic acid and mixtures thereof; and, (ii) a co-catalyst system containing from 0.1 to 5 parts by weight of a dialkyl tin salt of a carboxylic acid, with the alkyl group having 1 to 2 carbon atoms, and from 0.001 to 0.4 parts by weight of a co-catalyst selected from the class consisting of a zinc salt of a carboxylic acid and zirconium salt of a carboxylic acid.
R Si (OCOR')3 where R and R' are monovalent hydrocarbon radicals and (4) one of the group selected from:
(i) a catalytic system containing from 0.1 to 5 parts by weight of a catalyst selected from the class consisting of zinc salt of carboxylic acid and zirconium salt of carboxylic acid and mixtures thereof; and, (ii) a co-catalyst system containing from 0.1 to 5 parts by weight of a dialkyl tin salt of a carboxylic acid, with the alkyl group having 1 to 2 carbon atoms, and from 0.001 to 0.4 parts by weight of a co-catalyst selected from the class consisting of a zinc salt of a carboxylic acid and zirconium salt of a carboxylic acid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US92778778A | 1978-07-25 | 1978-07-25 | |
| US927,787 | 1978-07-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1139479A true CA1139479A (en) | 1983-01-11 |
Family
ID=25455255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000330880A Expired CA1139479A (en) | 1978-07-25 | 1979-06-29 | Low modulus room temperature vulcanizable silicone rubber compositions |
Country Status (15)
| Country | Link |
|---|---|
| JP (1) | JPS5527388A (en) |
| AR (1) | AR227378A1 (en) |
| AU (1) | AU532773B2 (en) |
| BE (1) | BE877845A (en) |
| CA (1) | CA1139479A (en) |
| CH (1) | CH648336A5 (en) |
| DE (1) | DE2928171A1 (en) |
| DK (1) | DK314379A (en) |
| ES (1) | ES482772A1 (en) |
| FR (1) | FR2433558A1 (en) |
| GB (1) | GB2026512B (en) |
| IT (1) | IT1122257B (en) |
| NL (1) | NL7905719A (en) |
| SE (1) | SE7906256L (en) |
| ZA (1) | ZA792758B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2531095B1 (en) * | 1982-07-30 | 1987-08-14 | Rhone Poulenc Spec Chim | SINGLE-COMPONENT ORGANOPOLYSILOXANIC COMPOSITIONS COMPRISING AS CROSSLINKERS OF SILANES WITH ACYLOXYL OR KETONIMINOXYL GROUPS AND CATALYZED BY ORGANIC TITANIUM DERIVATIVES |
| FR2539423A1 (en) * | 1983-01-13 | 1984-07-20 | Rhone Poulenc Spec Chim | Single-component organopolysiloxane compositions containing, as crosslinking agents, silanes containing acyloxy or ketiminoxy groups and catalysed by organic zirconium derivatives. |
| FR2540129B1 (en) * | 1983-01-27 | 1985-06-21 | Rhone Poulenc Spec Chim | ORGANOPOLYSILOXANIC COMPOSITIONS CONTAINING POLYACYLOXYSILANES AND CURING VERY FAST IN ELASTOMERS IN THE PRESENCE OF A PHOSPHATE ACCELERATOR |
| DE3524452A1 (en) * | 1985-07-09 | 1987-01-15 | Bayer Ag | RTV SILICONE PASTE WITH SHORTENED CURING TIME |
| EP2774673A1 (en) * | 2013-03-04 | 2014-09-10 | Nitrochemie Aschau GmbH | Catalyst for the cross-linking of silicon rubbers |
| EP2774672A1 (en) * | 2013-03-04 | 2014-09-10 | Nitrochemie Aschau GmbH | Catalyst for the cross-linking of silicon rubbers |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL290275A (en) * | 1962-03-26 | 1900-01-01 | ||
| US3840492A (en) * | 1972-02-10 | 1974-10-08 | Gen Electric | Flame retardant organopolysiloxane composition |
| JPS5125069B2 (en) * | 1972-04-22 | 1976-07-28 | ||
| DE2644193A1 (en) * | 1976-09-30 | 1978-04-06 | Bayer Ag | PASTOESE COMPONENTS CONTAINING CROSSLINKERS AND CURING CATALYSTS AS COMPONENTS FOR POLYSILOXANE ELASTOMERS VULCANIZED AT ROOM TEMPERATURE |
-
1979
- 1979-06-04 ZA ZA792758A patent/ZA792758B/en unknown
- 1979-06-26 GB GB7922235A patent/GB2026512B/en not_active Expired
- 1979-06-29 CA CA000330880A patent/CA1139479A/en not_active Expired
- 1979-07-09 AU AU48756/79A patent/AU532773B2/en not_active Ceased
- 1979-07-12 DE DE19792928171 patent/DE2928171A1/en not_active Withdrawn
- 1979-07-16 AR AR277318A patent/AR227378A1/en active
- 1979-07-18 JP JP9047679A patent/JPS5527388A/en active Granted
- 1979-07-20 SE SE7906256A patent/SE7906256L/en not_active Application Discontinuation
- 1979-07-23 ES ES482772A patent/ES482772A1/en not_active Expired
- 1979-07-23 BE BE0/196417A patent/BE877845A/en not_active IP Right Cessation
- 1979-07-23 CH CH6825/79A patent/CH648336A5/en not_active IP Right Cessation
- 1979-07-23 IT IT24550/79A patent/IT1122257B/en active
- 1979-07-24 FR FR7919016A patent/FR2433558A1/en not_active Withdrawn
- 1979-07-24 NL NL7905719A patent/NL7905719A/en not_active Application Discontinuation
- 1979-07-25 DK DK314379A patent/DK314379A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| NL7905719A (en) | 1980-01-29 |
| FR2433558A1 (en) | 1980-03-14 |
| DK314379A (en) | 1980-01-26 |
| GB2026512A (en) | 1980-02-06 |
| GB2026512B (en) | 1983-05-18 |
| AU4875679A (en) | 1980-01-31 |
| IT7924550A0 (en) | 1979-07-23 |
| DE2928171A1 (en) | 1980-02-14 |
| JPS5527388A (en) | 1980-02-27 |
| CH648336A5 (en) | 1985-03-15 |
| AR227378A1 (en) | 1982-10-29 |
| SE7906256L (en) | 1980-01-27 |
| ES482772A1 (en) | 1980-04-16 |
| IT1122257B (en) | 1986-04-23 |
| ZA792758B (en) | 1981-02-25 |
| JPS638147B2 (en) | 1988-02-20 |
| AU532773B2 (en) | 1983-10-13 |
| BE877845A (en) | 1979-11-16 |
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