CA1211589A - Multi-component solventless silicone release coating system - Google Patents
Multi-component solventless silicone release coating systemInfo
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Abstract
NOVEL MULTI-COMPONENT SOLVENTLESS
SILICONE RELEASE COATING SYSTEM
Abstract of the Invention The present invention provides a method for preparing a precious metal catalyzed, heat curable silicone release coating compositon. Also, there is provided an article of manufacture for packaging the ingredients necessary to practice the method of the invention.
SILICONE RELEASE COATING SYSTEM
Abstract of the Invention The present invention provides a method for preparing a precious metal catalyzed, heat curable silicone release coating compositon. Also, there is provided an article of manufacture for packaging the ingredients necessary to practice the method of the invention.
Description
NOVEL ~ULTI-COMPONENT SOLYENTLESS
SILICONE RELEASE COATING SYSTEM
Background of the Invention The present invention relates to a method for providing heat cured, precious metal catalyzed, solvent less silicone release coating compositions which have improved shelf-life and bath-life, require utilization of smaller quantities of precious metal catalyst and provide the end-user greater flexibility in formulate in and preparing release coating baths which meet his specific needs. In addition the present invention provides an article of manufacture useful for providing the ingredients necessary to practice the foregoing method.
An important advance in the art of silicone release coating compositions is the solvent less release coating composition of Grenoble, described in So Patent 4,071,644. This composition includes a low viscosity vinyl chain-stopped polysiloxane or a low viscosity sullenly terminated polysiloxane with an organohydrogen-selection and a curing catalyst. Among the advantages of such a solvent less release coating composition are that the need for expensive pollution control equipment is eliminated and the amount of energy required to effect curing is substantially reduced.
However, a problem relating to premature curing or gelatin must be overcome in order to provide a commercially more desirable solvent less release coating composition. A typical coating composition is provided as a two component system, one component containing a base polymer and catalyst and the other I.
SUE
1 a cross-linking agent. When the two components are mixed together to provide & rules coating bath, premature curing may result in 8 catalyzed back having a pot-life insufficient to enable the end-user to curry out the coating applic~tio~.
One way of ameliorating these problems is to include an inhibitor in the component containing the base polymer and catalyst which is effective for retarding the cure reaction it ambient temperature but not at elevated temperatures.
One example of such an inhibitor containing release coating composition is disclosed in Eckberg, So Patent No.
49256,870. This release coating composition comprises a base polymer such as a vinyl chain-stopped polydialkyl-alkylvinyl copolymer and a methyl hydrogen cross linking fluid. A platinum or platinum metal complex is provided to initiate an addition cure or hydrosilation reaction. An inhibitor selected from organic esters of malefic acid is added to the composition in order to selectively retard the cure reaction so as to provide adequate shelf-life and a workable pot-life for the coating composition.
20 ` Eckberg in Skye Patent Jo, 4,262,107 discloses a silicone rubber composition with a good shélf-life and fast curing at elevated temperatures comprising a sullenly end-stopped diorgan-opolysiloxane polymer, a silicone hydrides and a rhodium complex catalyst in combination with an inhibitor compound selected from low molecular weight sullenly end stopped diorganopoly-selections, certain scetylenic compounds, olefinic carboxylic acid esters of aliphatic alcohols such as vinyl acetate, alkenyl isocyanurates and mixtures of such inhibitor compounds.
SUE
1 In US. Patent Jo. 4,347,346 Eckberg discloses a solvent-less plan or rhodium catalyzed addition curable polyorgano-selection release coating composition Containing a di~lkyl-acetylenedicarboxylate inhibitor for preventing premature gel-lion at ambient temperatures but which will cure at elevated temperatures via a hydIosilation reaction to form a coating capable of releasing material from substrates which would normally adhere thereto.
A solvent less silicone release coating composition containing a blend of a dialkylcarboxylic ester naming carbon to carbon unsaturation and an olefinic carboxylic acid ester of an aliphatic alcohol which it effective for retarding 2 precious metal catalyzed addition cure hydrosilstion reaction at room temperature, but which does not interfere with curing lo at elevated temperatures, is provided by Eckberg in Can. Ser.
I No- YO-YO filed December 62/, kiwi - Generally such `~` release coating composition Comprises on oleinorganopolysi-loxane or sullenly terminated polysilox3ne base polymer, an organohydrogenpolysiloxane cross-linking agent, 2 catalytic amount of a precious metal catalyst and an effective mount of a blend of a dialkylcarboxylic ester having carbon to carbon unsaturation end an olefinic carboxylic acid ester of an aliphatic alcohol for inhibiting an addition cure hydrosilation reaction between said base polymer and said cro66-linking agent it root temperature, but which is not present in an amount sufficient to prevent curing of said costing composition it elevated temperatures. The ratio of dialkyl carboxylic ester to olefinic carboxylic acid ester of on aliphatic alcohol of the inhibitor blend ranges from approximately 1:24 to 1:1, but 33 preferably is blended in a 1:3 ratio. The most preferred dialkyl carboxylic ester containing carbon -to carbon unsaturation is diallylmaleate; however, other preferred compounds include butylallylmaleate, dia]lylsuccinate, dimethylmaleate, diethylmaleate and silylmaleates such as bus - propyltris (methoxy) silylmaleate. The most preferred olefinic carboxylic acid ester of an aliphatic alcohol is vinyl acetate; however, any compound derived from an aliphatic alcohol having 1 to 4 carbon atoms and an olefinic carboxylic acid having 2 to 10 carbon atoms is also effective.
Ordinarily an effective amount of inhibitor ranges from approximately 0.05% to approximately 2% by weight and preferably from 0.1% to 1.5% by weight.
Although compositions such as the foregoing have improved shelf-life and pot-life, it is desirable to provide compositions and methods which still further improve such compositions' shelf-life and pot-life.
Additionally, it is desirable to provide compositions and methods which utilize even smaller amounts of precious metal catalyst, further reduce the amount of energy required to effect a cure, and provide the end-user with greater flexibility in formulating and preparing release coating compositions which meet his specific needs. One such composition is provided by Eckberg in US. Pat. No. 4,340,~47, which comprises a vinyl or sullenly functional base polymer, a cross-linking agent containing silanic hydrogen a precious metal catalyst such as platinum or rhodium, a carboxylic ester inhibitor, and a silicone vinyl gum cure accelerator effective for allowing thermal curing to SUE
Normal procedure for providing the end-user with a solvent less release coating composition is to package the base polymer, catalyst and inhibitor in one package and to provide a second package containing the methyl hydrogen cross-linking agent. The end-user produces a release coating composition bath by mixing the two packages according to specified proper-lions, whereupon such mixture is applied to a substrate such as paper and allowed to cure at elevated temperatures in a relatively short period of time.
Fabricators and formulators in the silicone industry have quickly recognized the significance of the foregoing silicone release coating compositions. It has become an industry standard to utilize such compositions in a two-package format at about a 100:5 mixture ratio. This system works quite well as evidenced by the success of the products in the market, but possesses certain disadvantages which are substantially overcome by the present invention The present invention provides a system for packaging and formulating silicone release coating compositions and an article of manufacture useful in such system. As a result, the shelf-life and pot-life are increased, energy and precious metal catalyst consumption are reduced, and flexibility in formulating baths to meet specific needs is provided. The -two package prior art system effectively fixes the ratio of catalyst and inhibitor and thereby limits the end-user's flex-ability. No-t only does the three or more package system of the present invention provide such flexibility through the selective use of catalyst and inhibitor, it does so at effective catalyst levels which are lower and therefore more economical than those previously provided by the art.
A system similar to that O r the present invention is described by Caprino in US. Pat. No. 4,322,320.
Caprino provides a process for formulating an addition cured silicone rubber composition comprising mixing 95 to 99.5 parts of Component A with 0.5 to 5.0 parts of Component B and 0.5 to 5.0 parts of Component C and curing said mixture. Component A is a silicone base compound consisting essentially of 100 parts by weight of vinyl-containing linear polysiloxane and 0.5 to 50.0 parts by weight of a hydrogen-containing polysiloxane. Component B is a cure agent consisting essentially of 100 parts of said vinyl-containing polysiloxane containing therein at least 0.40 parts of an inhibitor compound having at least one radical of the formula -KIWI, and a-t least 0.001 parts platinum per 100 parts vinyl polymer in Component B. Component C is a cure modifying agent consisting essentially of 100 parts of said vinyl-containing polysiloxane containing at least 0.10 parts of said inhibitor compound.
The present inventors are the first to recognize that by keeping each ingredient in a separate package improved results are obtained.
That is, only the present inventors have recognized the need to keep the catalyst separate from the inhibitor and the base polymer, as well as the need to keep separate the base polymer and cross-linking agent in order to provide a release coating having improved shelflike extended workable pot-1.ife and which utilizes substantially less precious metal catalyst than requited in the prior art.
It is -therefore an object of the present invention to provide a method for increasing the shelf-life and workable pot life of a silicone release coating composition.
It is also an object of the present invention to provide a method for reducing the amount of precious metal catalyst utilized to initiate curing of a silicone release coating composition without sacrificing performance.
Another object of the present invention is to provide a method for enabling an end-user of a silicone release coating composition to more easily formulate and prepare a composition specific to his needs Still another object of the present invention is to provide an article of manufacture comprising a plurality of components which are mixed together to form a silicone release coating composition.
These and other objects will become apparent to those skilled in the art upon careful consideration of the following specification, examples and claims.
Summary of the I've Zion The process of the present invention provides a system for formulating an addition cured silicone release coating compost-I
lion wherein specific proportions of each of three or more packages are mixed together, applied -to a suitable substrate such as paper, and cured at elevated temperatures to provide a release coating such that materials do not adhere -to -the substrate which normally would adhere thereto. Component A
is an olefinorganopolysiloxane or sullenly chain-stopped polysiloxane base polymer. Component A
can include any of inhibitor compounds provided lo for in the prior art; however inhibitor blend disclosed by Eckberg, Canadian Patent Application Serial No. 463,891 filed December 21, 1983 is preferred. It is even more preferable that such inhibitor be provided as a separate component or package so as to provide greater flexibility to the end-user in formulating a release composition which meets his specific needs. Component B is a precious metal catalyst in a suitable silicone fluid with sufficient catalyst present so as to afford approximately 25 Pam to 500 Pam in the blend. Component C is a polyorganohydrogen selection fluid, preferably polymethylhydrogen selection, cross-linking agent Component D can be an inhibitor as described above, a vinyl gum cure accelerator, or other additive which further benefits the end-user. Of course, it is contemplated that any number of packages can be provided, for example component D
can be an inhibitor and Component E can be a vinyl gum cure accelerator.
The article of manufacture of the present invention comprises the individual packages or components which contain the ingredients utilized in practicing the process of -the present invention.
That is, the article of manufacture comprises the combination of, for example, Component A, Component B, and Component C which are provided the end-user for mixing in specific proportions.
'I.
Description oft Invention In accordance with -the present invention there is provided a method for providing heat cured precious metal catalyzed solvent less silicone release coating compositions which have improved shelf-life and bath-life, require utilization of smaller quantities of precious metal catalyst and provide -the end-user greater flexibility in formulating and preparing release coating baths which meet his specific needs. Additionally, the present invention provides an article of manufacture useful for providing the ingredients necessary to practice the method of the present invention As discussed hereinabove, existing solvent less silicone release coating compositions are provided to the end-user in a two part package. One part consists of an olefinorganopolysiloxane or a sullenly end-stopped polysiloxane base polymer having therein a precious metal hydrosilation catalyst such as platinum or rhodium, and most often, an inhibitor compound for retarding curing at ambient temperature but which does not interfere with curing at elevated temperatures. The second package contains an organohydrogenpolysiloxane cross-linking agent, for example, trime-thylsiloxy chain-stopped polymethylhydrogensiloxane. The end-user combines the two packages to form a release coating bath which is utilized to coat a suitable substrate.
After thermally curing the coated substrate, there is provided a coating capable of releasing materials from -the substrate which would normally adhere thereto.
This system is useful for unsophisticated end-users, but most formulators now have a high degree of -technical expertise and utilize very sophisticated equipment in preparing lo - lo - SUE 727 products for the marketplace. Accordingly, the present inventors developed a system which would provide end-users with greater flexibility in formulating release coating baths to meet their specific needs. Surprisingly, however, it was found that by providing the ingredients required for preparing a silicone release coating composition bath in separate packages, that in addition to obtaining flexibility there was also obtained increased shelf-life and bath-life, reduction of -the amount of precious metal catalyst required to effect curing at relatively low temperatures, and reduction of the amount of energy consumed during curing.
I've process of the present invention provides these benefits and overcomes many of the disadvantages of the prior art two-package system through utilization of a three or more package system.
In the process of the present invention it is preferable that each component or package contain only one of the ingredients necessary to provide a silicone release coating composition; however, as described more fully hereinbelow, certain of the ingredients can be mixed together without adversely affecting shelf-life, bath-life, or the amount of precious metal catalyst required.
Package or Component A contains a base polymer which can be either an olefinorganopolysiloxane having structural units of the formula:
a b (Ahab) (I) or a sullenly end-stopped organopolysiloxane having the general formula:
i HO So - H (IA) I I
R x wherein R is an organic radical selected from alkyd radicals such as methyl, ethyl, propel, isopropyl, bottle, octal, dodecyl and the like; cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl and the like, aureole radicals such as phenol, naphthyl, toll, xylyl and the like, aralkyl radicals such as phenylethyl, phenylpropyl and the like; halogenated derivatives of the aforesaid radicals including chloromethyl, -trifluoromethyl, chloropropyl, chlorophenyl, dibromophenyl~ tetrach7orophenyl, difluorophenyl and the like, and cyanoalkyl radicals such as beta-cyanoethyl, gamma-cyanopropyl, beta-eyanopropyl and the like. Preferably R is methyl; however, the above formulas are intended to cover any of the foregoing radicals or mixtures thereof. Among the radicals represented by Al are included alkenyl radicals such as vinyl, ally, methallyl, buttonhole, pentynyl and the like. Preferably Al is vinyl or ally and most preferably is vinyl.
Although the base polymer of Component A can be either an olefinorganopolysiloxane or a sullenly end-stopped polysiloxane, it is most preferable that an olefinorganopolysiloxane be utilized. The olefinorganopolysiloxanes encompassed within the scope of Formula I are well known in the art, for example, as disclosed in US. Patent No.
3t344,111 to Chalk and US. Patent No. 3,436,366 to Moxie. Similarly, their preparation and commercial availability are also well known. The olefinorganopolysiloxanes of Formula I can be characterized as copolymers of (1) selection units having the formula:
I' RcRdSI(4-c-d) (TV) __ __ ___ where R and R1 are as defined above and c has a value of from 0 -to 2 inclusive and -the average sum of c and d is equal to from 0.8 to 3.0 inclusive, end
SILICONE RELEASE COATING SYSTEM
Background of the Invention The present invention relates to a method for providing heat cured, precious metal catalyzed, solvent less silicone release coating compositions which have improved shelf-life and bath-life, require utilization of smaller quantities of precious metal catalyst and provide the end-user greater flexibility in formulate in and preparing release coating baths which meet his specific needs. In addition the present invention provides an article of manufacture useful for providing the ingredients necessary to practice the foregoing method.
An important advance in the art of silicone release coating compositions is the solvent less release coating composition of Grenoble, described in So Patent 4,071,644. This composition includes a low viscosity vinyl chain-stopped polysiloxane or a low viscosity sullenly terminated polysiloxane with an organohydrogen-selection and a curing catalyst. Among the advantages of such a solvent less release coating composition are that the need for expensive pollution control equipment is eliminated and the amount of energy required to effect curing is substantially reduced.
However, a problem relating to premature curing or gelatin must be overcome in order to provide a commercially more desirable solvent less release coating composition. A typical coating composition is provided as a two component system, one component containing a base polymer and catalyst and the other I.
SUE
1 a cross-linking agent. When the two components are mixed together to provide & rules coating bath, premature curing may result in 8 catalyzed back having a pot-life insufficient to enable the end-user to curry out the coating applic~tio~.
One way of ameliorating these problems is to include an inhibitor in the component containing the base polymer and catalyst which is effective for retarding the cure reaction it ambient temperature but not at elevated temperatures.
One example of such an inhibitor containing release coating composition is disclosed in Eckberg, So Patent No.
49256,870. This release coating composition comprises a base polymer such as a vinyl chain-stopped polydialkyl-alkylvinyl copolymer and a methyl hydrogen cross linking fluid. A platinum or platinum metal complex is provided to initiate an addition cure or hydrosilation reaction. An inhibitor selected from organic esters of malefic acid is added to the composition in order to selectively retard the cure reaction so as to provide adequate shelf-life and a workable pot-life for the coating composition.
20 ` Eckberg in Skye Patent Jo, 4,262,107 discloses a silicone rubber composition with a good shélf-life and fast curing at elevated temperatures comprising a sullenly end-stopped diorgan-opolysiloxane polymer, a silicone hydrides and a rhodium complex catalyst in combination with an inhibitor compound selected from low molecular weight sullenly end stopped diorganopoly-selections, certain scetylenic compounds, olefinic carboxylic acid esters of aliphatic alcohols such as vinyl acetate, alkenyl isocyanurates and mixtures of such inhibitor compounds.
SUE
1 In US. Patent Jo. 4,347,346 Eckberg discloses a solvent-less plan or rhodium catalyzed addition curable polyorgano-selection release coating composition Containing a di~lkyl-acetylenedicarboxylate inhibitor for preventing premature gel-lion at ambient temperatures but which will cure at elevated temperatures via a hydIosilation reaction to form a coating capable of releasing material from substrates which would normally adhere thereto.
A solvent less silicone release coating composition containing a blend of a dialkylcarboxylic ester naming carbon to carbon unsaturation and an olefinic carboxylic acid ester of an aliphatic alcohol which it effective for retarding 2 precious metal catalyzed addition cure hydrosilstion reaction at room temperature, but which does not interfere with curing lo at elevated temperatures, is provided by Eckberg in Can. Ser.
I No- YO-YO filed December 62/, kiwi - Generally such `~` release coating composition Comprises on oleinorganopolysi-loxane or sullenly terminated polysilox3ne base polymer, an organohydrogenpolysiloxane cross-linking agent, 2 catalytic amount of a precious metal catalyst and an effective mount of a blend of a dialkylcarboxylic ester having carbon to carbon unsaturation end an olefinic carboxylic acid ester of an aliphatic alcohol for inhibiting an addition cure hydrosilation reaction between said base polymer and said cro66-linking agent it root temperature, but which is not present in an amount sufficient to prevent curing of said costing composition it elevated temperatures. The ratio of dialkyl carboxylic ester to olefinic carboxylic acid ester of on aliphatic alcohol of the inhibitor blend ranges from approximately 1:24 to 1:1, but 33 preferably is blended in a 1:3 ratio. The most preferred dialkyl carboxylic ester containing carbon -to carbon unsaturation is diallylmaleate; however, other preferred compounds include butylallylmaleate, dia]lylsuccinate, dimethylmaleate, diethylmaleate and silylmaleates such as bus - propyltris (methoxy) silylmaleate. The most preferred olefinic carboxylic acid ester of an aliphatic alcohol is vinyl acetate; however, any compound derived from an aliphatic alcohol having 1 to 4 carbon atoms and an olefinic carboxylic acid having 2 to 10 carbon atoms is also effective.
Ordinarily an effective amount of inhibitor ranges from approximately 0.05% to approximately 2% by weight and preferably from 0.1% to 1.5% by weight.
Although compositions such as the foregoing have improved shelf-life and pot-life, it is desirable to provide compositions and methods which still further improve such compositions' shelf-life and pot-life.
Additionally, it is desirable to provide compositions and methods which utilize even smaller amounts of precious metal catalyst, further reduce the amount of energy required to effect a cure, and provide the end-user with greater flexibility in formulating and preparing release coating compositions which meet his specific needs. One such composition is provided by Eckberg in US. Pat. No. 4,340,~47, which comprises a vinyl or sullenly functional base polymer, a cross-linking agent containing silanic hydrogen a precious metal catalyst such as platinum or rhodium, a carboxylic ester inhibitor, and a silicone vinyl gum cure accelerator effective for allowing thermal curing to SUE
Normal procedure for providing the end-user with a solvent less release coating composition is to package the base polymer, catalyst and inhibitor in one package and to provide a second package containing the methyl hydrogen cross-linking agent. The end-user produces a release coating composition bath by mixing the two packages according to specified proper-lions, whereupon such mixture is applied to a substrate such as paper and allowed to cure at elevated temperatures in a relatively short period of time.
Fabricators and formulators in the silicone industry have quickly recognized the significance of the foregoing silicone release coating compositions. It has become an industry standard to utilize such compositions in a two-package format at about a 100:5 mixture ratio. This system works quite well as evidenced by the success of the products in the market, but possesses certain disadvantages which are substantially overcome by the present invention The present invention provides a system for packaging and formulating silicone release coating compositions and an article of manufacture useful in such system. As a result, the shelf-life and pot-life are increased, energy and precious metal catalyst consumption are reduced, and flexibility in formulating baths to meet specific needs is provided. The -two package prior art system effectively fixes the ratio of catalyst and inhibitor and thereby limits the end-user's flex-ability. No-t only does the three or more package system of the present invention provide such flexibility through the selective use of catalyst and inhibitor, it does so at effective catalyst levels which are lower and therefore more economical than those previously provided by the art.
A system similar to that O r the present invention is described by Caprino in US. Pat. No. 4,322,320.
Caprino provides a process for formulating an addition cured silicone rubber composition comprising mixing 95 to 99.5 parts of Component A with 0.5 to 5.0 parts of Component B and 0.5 to 5.0 parts of Component C and curing said mixture. Component A is a silicone base compound consisting essentially of 100 parts by weight of vinyl-containing linear polysiloxane and 0.5 to 50.0 parts by weight of a hydrogen-containing polysiloxane. Component B is a cure agent consisting essentially of 100 parts of said vinyl-containing polysiloxane containing therein at least 0.40 parts of an inhibitor compound having at least one radical of the formula -KIWI, and a-t least 0.001 parts platinum per 100 parts vinyl polymer in Component B. Component C is a cure modifying agent consisting essentially of 100 parts of said vinyl-containing polysiloxane containing at least 0.10 parts of said inhibitor compound.
The present inventors are the first to recognize that by keeping each ingredient in a separate package improved results are obtained.
That is, only the present inventors have recognized the need to keep the catalyst separate from the inhibitor and the base polymer, as well as the need to keep separate the base polymer and cross-linking agent in order to provide a release coating having improved shelflike extended workable pot-1.ife and which utilizes substantially less precious metal catalyst than requited in the prior art.
It is -therefore an object of the present invention to provide a method for increasing the shelf-life and workable pot life of a silicone release coating composition.
It is also an object of the present invention to provide a method for reducing the amount of precious metal catalyst utilized to initiate curing of a silicone release coating composition without sacrificing performance.
Another object of the present invention is to provide a method for enabling an end-user of a silicone release coating composition to more easily formulate and prepare a composition specific to his needs Still another object of the present invention is to provide an article of manufacture comprising a plurality of components which are mixed together to form a silicone release coating composition.
These and other objects will become apparent to those skilled in the art upon careful consideration of the following specification, examples and claims.
Summary of the I've Zion The process of the present invention provides a system for formulating an addition cured silicone release coating compost-I
lion wherein specific proportions of each of three or more packages are mixed together, applied -to a suitable substrate such as paper, and cured at elevated temperatures to provide a release coating such that materials do not adhere -to -the substrate which normally would adhere thereto. Component A
is an olefinorganopolysiloxane or sullenly chain-stopped polysiloxane base polymer. Component A
can include any of inhibitor compounds provided lo for in the prior art; however inhibitor blend disclosed by Eckberg, Canadian Patent Application Serial No. 463,891 filed December 21, 1983 is preferred. It is even more preferable that such inhibitor be provided as a separate component or package so as to provide greater flexibility to the end-user in formulating a release composition which meets his specific needs. Component B is a precious metal catalyst in a suitable silicone fluid with sufficient catalyst present so as to afford approximately 25 Pam to 500 Pam in the blend. Component C is a polyorganohydrogen selection fluid, preferably polymethylhydrogen selection, cross-linking agent Component D can be an inhibitor as described above, a vinyl gum cure accelerator, or other additive which further benefits the end-user. Of course, it is contemplated that any number of packages can be provided, for example component D
can be an inhibitor and Component E can be a vinyl gum cure accelerator.
The article of manufacture of the present invention comprises the individual packages or components which contain the ingredients utilized in practicing the process of -the present invention.
That is, the article of manufacture comprises the combination of, for example, Component A, Component B, and Component C which are provided the end-user for mixing in specific proportions.
'I.
Description oft Invention In accordance with -the present invention there is provided a method for providing heat cured precious metal catalyzed solvent less silicone release coating compositions which have improved shelf-life and bath-life, require utilization of smaller quantities of precious metal catalyst and provide -the end-user greater flexibility in formulating and preparing release coating baths which meet his specific needs. Additionally, the present invention provides an article of manufacture useful for providing the ingredients necessary to practice the method of the present invention As discussed hereinabove, existing solvent less silicone release coating compositions are provided to the end-user in a two part package. One part consists of an olefinorganopolysiloxane or a sullenly end-stopped polysiloxane base polymer having therein a precious metal hydrosilation catalyst such as platinum or rhodium, and most often, an inhibitor compound for retarding curing at ambient temperature but which does not interfere with curing at elevated temperatures. The second package contains an organohydrogenpolysiloxane cross-linking agent, for example, trime-thylsiloxy chain-stopped polymethylhydrogensiloxane. The end-user combines the two packages to form a release coating bath which is utilized to coat a suitable substrate.
After thermally curing the coated substrate, there is provided a coating capable of releasing materials from -the substrate which would normally adhere thereto.
This system is useful for unsophisticated end-users, but most formulators now have a high degree of -technical expertise and utilize very sophisticated equipment in preparing lo - lo - SUE 727 products for the marketplace. Accordingly, the present inventors developed a system which would provide end-users with greater flexibility in formulating release coating baths to meet their specific needs. Surprisingly, however, it was found that by providing the ingredients required for preparing a silicone release coating composition bath in separate packages, that in addition to obtaining flexibility there was also obtained increased shelf-life and bath-life, reduction of -the amount of precious metal catalyst required to effect curing at relatively low temperatures, and reduction of the amount of energy consumed during curing.
I've process of the present invention provides these benefits and overcomes many of the disadvantages of the prior art two-package system through utilization of a three or more package system.
In the process of the present invention it is preferable that each component or package contain only one of the ingredients necessary to provide a silicone release coating composition; however, as described more fully hereinbelow, certain of the ingredients can be mixed together without adversely affecting shelf-life, bath-life, or the amount of precious metal catalyst required.
Package or Component A contains a base polymer which can be either an olefinorganopolysiloxane having structural units of the formula:
a b (Ahab) (I) or a sullenly end-stopped organopolysiloxane having the general formula:
i HO So - H (IA) I I
R x wherein R is an organic radical selected from alkyd radicals such as methyl, ethyl, propel, isopropyl, bottle, octal, dodecyl and the like; cycloalkyl radicals such as cyclopentyl, cyclohexyl, cycloheptyl and the like, aureole radicals such as phenol, naphthyl, toll, xylyl and the like, aralkyl radicals such as phenylethyl, phenylpropyl and the like; halogenated derivatives of the aforesaid radicals including chloromethyl, -trifluoromethyl, chloropropyl, chlorophenyl, dibromophenyl~ tetrach7orophenyl, difluorophenyl and the like, and cyanoalkyl radicals such as beta-cyanoethyl, gamma-cyanopropyl, beta-eyanopropyl and the like. Preferably R is methyl; however, the above formulas are intended to cover any of the foregoing radicals or mixtures thereof. Among the radicals represented by Al are included alkenyl radicals such as vinyl, ally, methallyl, buttonhole, pentynyl and the like. Preferably Al is vinyl or ally and most preferably is vinyl.
Although the base polymer of Component A can be either an olefinorganopolysiloxane or a sullenly end-stopped polysiloxane, it is most preferable that an olefinorganopolysiloxane be utilized. The olefinorganopolysiloxanes encompassed within the scope of Formula I are well known in the art, for example, as disclosed in US. Patent No.
3t344,111 to Chalk and US. Patent No. 3,436,366 to Moxie. Similarly, their preparation and commercial availability are also well known. The olefinorganopolysiloxanes of Formula I can be characterized as copolymers of (1) selection units having the formula:
I' RcRdSI(4-c-d) (TV) __ __ ___ where R and R1 are as defined above and c has a value of from 0 -to 2 inclusive and -the average sum of c and d is equal to from 0.8 to 3.0 inclusive, end
(2) organopolysiloxane units having the structural formula:
(R)nS-~o~-n (V) --where R is as defined above and n has a value of from 0.8 to 2.5 inclusive. Thus, where -the olefin-organopolysiloxane employed herein is a copolymerof units within the scope of Formula IV and an organopolysiloxane having an average formula within the scope of Formula V, the copolymer generally contains from 0.5 to 99.5 mole percent of the units of Formula IV and from 0.5 to 99.5 mole percent of units within the scope of Formula V. The preparation of these copolymers is well known to those skilled in the art.
A major proportion of -the composition is typically a vinyl chain-s-topped polysiloxane having the general formula:
R R f R R
R t R So - So - OH C 2 wherein R is a monovalent hydrocarbon radical free of unsaturation. Suitable radicals for R include, for example, methyl, ethyl, propel, bottle and other similar unsaturated hydrocarbons, but ordinarily would not include phenol groups for paper release purposes. Al is a hydrocarbon radical having alkenyl unsa-turation. Typically R represents vinyl groups but may also represent allylic or cycloalkenyl unsaturated groups; x and y are positive integers such that -the vinyl chain-stopped polysiloxane has up to approximately 20~ by weight of Al groups.
The viscosity of such a polysiloxane ranges from approximately 50 to approximately 100,000 centipoise at 25C. Preferably the vinyl chain-stopped polysiloxane has up to approximately 20% by weight of vinyl groups and the viscosity ranges from approximately 300 to approximately 550 centipoise at 25C. The preferred vinyl chain-stopped polysiloxane has -the general formula:
Ho SHEA = OH So So So t So OH C 2 SHEA SHEA SHEA y SHEA
wherein x and y are as described above.
The sullenly end-s-topped polysiloxanes of Formula It are prepared by the equilibration of cyclic polysiloxanes with an alkali metal hydroxide catalyst. The desired viscosity is obtained by controlling the amount of water added to the reaction. These procedures are described in the literature and are well known to those skilled in the art.
Component B contains a precious metal catalyst effective for initiating a hydrosilation cure reaction.
The precious metal catalyst component utilized in compositions of the present invention includes all of the well known platinum and rhodium catalysts which are effective for catalyzing the reaction between silicon-bonded hydrogen atoms end silicon-bonded olefinic groups, and which are freely miscible in solvent-free silicone polymers. These materials especially include the platinum hydrocarbon complexes described in US. Patent No. 3,159,601 and U S. Patent No. 3,159,662 to Ashy, and the platinum alcohol ate catalysts described in US. Patent No. 3,220,970 to Limericks, as well as the platinum catalysts of US. Patent Jo. 3,814,730 to Karstedt. Additionally, the platinum chloride-olefin complexes described in US. Patent No. 3,516,946 to Medic are also useful herein.
A particularly useful catalyst for facilitating the hydrosilation reaction is the Karstedt catalyst described in US. Patent No. 3,814,730. Other platinum metal catalysts can be utilized in -the practice of the present invention; however, their selection depends upon such factors as the required reaction rate, expense, useful pot-life and the temperature at which the cure reaction is to take place. Other metal catalysts useful in the present invention include those which are silicone soluble complexes of the metals rhodium, ruthenium, palladium, osmium, iridium and platinum.
or coating compositions of the present invention, the amount of catalyst ranges from approximately 10 to approximately 500 Pam (as weight of metal atoms), again depending on such factors as speed of reaction and cost requirements. Preferably, the amount of catalyst is approximately 10 to 150 Pam of the precious metal.
Component or Package C is a methyl hydrogen fluid utilized by those skilled in the art as a cross-linking agent for Jo addition cure silicone systems. Particularly useful as a cross-linking agent for -the present invention is a trim ethyl chain-stopped polyme-thylhydrogen selection fluid having from approximately 10% to approximately 100 Six groups, any remaining groups being dim ethyl-sulks units, and having a viscosity in the range of from approximately 10 to 1000 centipoise at 25C.
However, any organohydrogenpolysiloxane having -the general formula:
RaHbSio(4-a-b) (II) is within the scope of the present invention.
The organohydrogenpolysiloxanes having structural units represented by Formula II hereinabove are intended to broadly cover fluid organopolysiloxane which are preferably, but not necessarily, free of olefinic unsaturation, but which do contain silanic hydrogen. The organohydrogenpolysiloxanes represented by Formula II are also well known in the art, for example, as described in US. Patent No. 3,344,111 and US. Patent No. 3,436,366.
Among -the radicals included within R of Formula II
are alkyd, such as methyl, ethyl, propel, isopropyl, bottle, octal and the like; cycloalkyl, such as cyclopentyl, cyclohexyl, cycloheptyl and the like;
aureole, such as phenol, naphthyl, toll, xylyl and the like; aralkyl, such as phenylethyl, phenylpropyl and the Lowe; halogenated derivates of the above radicals, including chlorome-thyl, trifluoromethyl, chloropropyl, chlorophenyl, I dibromophenyl, tetrachlorophenyl, deflower-phenol and the like; and cyanoalkyl, such as boatswain-ethyl, gamma-cyanopropyl, beta-cyanopropyl and the like. Also intended to be included within the scope of Formula II are those materials where R is a mixture of -the aforesaid radicals Preferably the R group of Formula II is methyl.
Materials specifically encompassed within Formula II hereinabove include 1,3-dimethyldisiloxane and 1,1,3,3-tetrame-thyldisiloxane, as well as higher polymers containing up to 100,000 or more silicon atoms per molecule. Also included within the scope of Formula II are cyclic materials such as cyclic polymers of methyl hydrogen selection having the general formula:
OH
_ _ so t Jo H / x wherein x is a whole number equal to from 3 to 10 or more. Particularly included is sym-tetramethyl-cyclotetrasiloxane.
The organohydrogenpolysiloxanes employed in the practice of the present invention can also be characterized as copolymers containing at least one unit per molecule having the formula:
c d (4-c-d~ (VI) with the remaining selection units of the organopoly-selection being within the scope of Formula V hereinabove, where R, c, d, and n are as defined above.
Jo Within -the scope of Formula VI are selection units such as hydrogen selection units (HSiO)l 5, methyl hydrogen selection units (HSiCH30), dim ethyl hydrogen selection units (HSi[CH3]20)o 5, and dihydrogen selection units (l~2SiO). In these copolymers, the selection units of Formulae V and VI are present in proportions so as to form a hydrogenpolysiloxane within the scope of Formula II hereinabove. In general such copolymers contain from 0.5 to 99.5 mole percent of selection units of Formula V
and from 0.5 -to 99.5 mole percent of selection units of Formula VI.
Ordinarily for release coating purposes it is preferred that the organohydrogenpolysiloxane cross-linker be essentially a -trim ethyl chain-stopped methylhydrogenpolysiloxane fluid having a viscosity of approximately 10 to 500 centipoise at 25C and a hydrogen content of from approximately 0.1 to 1.67 percent by weight.
Each of Component A, Component B and Component C
are essential for practicing the method of the present invention, and basically comprise the ingredients disclosed by Grenoble in US. Pa-tent No. 4,071,644 for a solvent less silicone release coating composition. In the present invention, however, the respective components are provided the end-user in the form of an article of manufacture having each of the components separately packaged.
Such separate packaging provides the surprising benefits of the present invention such as increased shelf-life, increased workable pot-life and reduction in the amount of precious metal catalyst required to initiate curing. I-t it -to be emphasized that to come within the scope of the present invention, Components, B, and C must be separately Jo packaged. However, additional ingredients such as an inhibitor or cure accelerator may be provided either as a separate component or as a part of another component and still come within the scope of the present invention.
Preferably there is also included a Component D which contains an inhibitor effective for retarding curing or cross-linking at ambient temperatures, but which does not interfere with curing at elevated temperatures. Although it is preferred that the inhibitor be provided as a separate component, it is within the scope of -the present invention if such inhibitor is included with either the base polymer or cross-linking agent. However, the inhibitor should not be packaged with the precious metal catalyst as it is believed that when the inhibitor and catalyst are mixed; the inhibitor forms a complex with the metal atoms of the catalyst which becomes more s-table and less reactive the longer the storage period before use. Accordingly, such packaging would result in substantial lessening of the benefits obtained by the present invention.
Eckberg in US. Patent Nos. 4,256,870, 4,262,107 and 4,347,346 and in Canadian Patent Application Serial Number 463,891 filed December 21, 1983 discloses a variety of inhibitors which have been found useful in silicone release coating compositions. US. Patent No. 4,256,870 discloses that an amount of dialkyl carboxylic ester containing carbon to carbon unsaturation is effective to inhibit the precious metal catalyzed hydrosilation cure reaction at temperatures below the heat cure temperature of the release coating composition. Most preferably such dialkyl carboxylic ester is diallylmaleate which has the formulcl:
~.~
C = C /
SHEA = CHCH2 - O - C C - O -- CH2CH = SHEA
O O
and ordinarily is utilized in a range of from approximately I to approximately 0.5~ by weight. Other preferred diallylic carboxylic esters which are preferred include diallylphthalate and diallylsuccinate. Also, saturated dialkyl esters of malefic acid, such as deathly and dim ethyl Malta, and mixed esters such as butylallylmaleate or methyle-thylmaleate are useful as hydrosilation inhibitors for solvent less release coating compositions.
The use of an olefinic carboxylic acid ester of an aliphatic alcohol is disclosed by Eckberg as an inhibitor for rhodium catalyzed silicone rubber compositions in US. Patent No. 4,262,107. Therein it is taught that such compositions can be utilized at low concentrations, such as from 0.1 to 2 parts per 100 parts of the sullenly base polymer, but preferably should be utilized in a concentration of 0.5 to 5 parts per 100 parts of the sullenly base polymer. The preferred inhibitor compound is vinyl acetate; however, those olefinic carboxylic acid esters of an aliphatic alcohol wherein the alcohol has from 1 to 4 carbon atom and the olefinic carboxylic acid has from 2 to 10 carbon atoms are within the scope of the disclosure.
US. Patent No. 4,347,346 discloses that dialkyl-acetylenedicarboxylates are effective inhibitors for preventing premature gelatin at ambient temperatures and which do not interfere with curing at elevated temperatures.
The most preferred inhibitor is that: disclosed in Can. Ser. No. 463,891 filed December 21, 19~3 and assigned -to the same assignee as the present invention.
Generally, -the invention of Canadian Serial No. 463,891 is based on -the surprising discovery -that a blend of a dialkyl carboxylic ester containing carbon to carbon unsaturation and an olefinic carboxylic acid ester of an aliphatic alcohol results in a blend which is a more effective inhibitor than utilizing similar amounts of the individual compounds, that is, a synergistic effect is obtained by such a blend of inhibitors.
The most preferred dialkyl carboxylic ester containing carbon to carbon unsaturation is Delilah-Malta; however, any of the inhibitor compositions within the scope of US. Patent No. 4,256,~70 can also be utilized. Among the preferred inhibitor compositions which also can be utilized are butylallylmaleate, Delilah-succinate, dimethylmaleate, diethylmaleate and sill-Maltese such as bus -propyltris (methoxy) silylmaleate which has the formula:
H H
OH O C = C O OH
/ 2 / / \ / \ 2 SHEA SHEA C C OH OH
Swish O O Swish The most preferred olefinic carboxylic acid ester of an aliphatic alcohol is vinyl acetate; however, any inhibitor compound within the scope of So Patent No.
4,262,107 may also be utilized. More particularly, such compounds are those derived from an aliphatic alcohol having 1 to 4 carbon atoms and an olefinic carboxylic acid having from 2 to 10 carbon atoms.
so it I
The Delco] carboxylic ester having carbon to carbon unsaturation, preferably diallylmaleate or bottle-allylmaleate, is blended with the olefinic carboxylic acid ester of an aliphatic alcohol, preferably vinyl acetate, in a ratio ranging from approximately 1:24 to 1:1, but most preferably is blended in approximately a 1:3 ratio. Accordingly, -the most preferred inhibitor for -the release coating composition is a blend comprising 1 part diallylmaleate and 3 parts vinyl acetate.
I Can. Ser. No. 463,~91 teaches that small amounts of such a two-part inhibitor permit exceptionally long catalyzed pot-life without sacrifice of cure performance, especially in compositions having a high platinum content.
Ordinarily the effective amount of inhibitor ranges from approximately 0.05 to approximately 2% by weight, and preferably from 0.1 to 0.5~ by weight. Use of such two-part inhibitor results in improved pot life yet the composition rapidly cures to a smear-free and migration-free non adherent surface when thermally cured.
Another optional ingredient is a vinyl gum cure accelerator of the type disclosed by Eckberg in United States Patent Number 4,340,647, which is assigned to the same assignee as the present invention.
Therein it is disclosed that a dimethylvinyl chain-stopped polydimethylmethylvinylsiloxane polymer gum will accelerate the hydrosilation cure reaction at a relatively low temperature without sacrificing performance.
Such vinyl gum cure accelerator may be provided as Component E of the article of manufacture of the present invention. However, it is preferable that such cure accelerator be provided in -the same package as the base polymer.
I' .~, What is disclosed and claimed by the present invention is a basic system for producing a silicone release coating composition and an article of manufacture for providing the ingredients necessary to formulate such release coating composition. The article of manufacture includes at least three components or packages, but may contain more, depending on whether optional ingredients are provided in a separate package or mixed with the ingredients of another lo package.
IJse of the article of manufacture of -the present invention for providing the ingredients utilized in the method of the present invention results in improved shelf-life, bath-life, reduction in the amount of precious metal catalyst required to initiate curing, and greater flexibility in formulating a bath to meet specific end-user requirements.
In order that those skilled in the art might be better able to practice the present invention, the following examples are given by way of illustration and not by way of limitation.
Examples l Tao In the following examples, release coating compositions were prepared from the following ingredients:
(A) a mixture consisting of lo parts of a linear dimethylvinyl chain-stopped polydimethyl-selection fluid having a viscosity of 120 cups at 25 DC and 5 parts of a dimethylvinyl chain-stopped linear polydimethylmethylvinyl-selection copolymer glum having a molecular weight of approximately 300,000 and containing 0.2 mole percent methyl vinyl selection units, such mixture having a viscosity of approximately 40t) cups at 25C;
(B) a solution of a platinum catalyst in a dimethylvinyl end stopped polydimethyl-selection fluid having a viscosity of 300 cups at 25C, there being sufficient catalyst present to afford 1800 Pam platinum (as metal) in the solution;
(C) a trimethylsiloxy chain-stopped linear polymethylhydrogensiloxane fluid having a viscosity of approximately 15 to 40 cups at 25C as a cross-linking agent; and (D) a blend of 3 parts vinyl acetate to 1 part of diallylmaleate.
Silicone release coating composition baths were prepared by mixing the four components as described in Table I. It should be noted that the inhibitor is provided as Component D and the vinyl gum cure accelerator is included with the base polymer in Component A. All parts are by weight.
TABLE I
Coating Bath Parts parts B Parts C Parts D
Example 1 100 8.4 4.4 1.2 Example 2 100 6.1 4.3 0.87 Example 3 100 3.7 4.2 0.53 Example 4 100 1.4 4.1 0.2 - ,4 - SUE 727 It can be seen that the relative ratio of catalyst (par-t B) to inhibitor (part D) was maintained a-t approximately 7:1 in all, four baths. The silicone release coating compositions of Examples 1 to 4 were coated onto 40 pound super calendered Croft (SUCK) substrate on an 18 inch three roll offset Grover pilot coaler equipped with forced air ovens.
Depositions of 0.5 to 0.7 pounds per 3000 square feet were measured. The oven dwell time required for cure to smear and migration-free adhesive surface was determined for each coating bath as a function of oven temperature.
No significant increase in viscosity (that is, the coating characteristics were not altered) over an eight hour period was observed for any of the formulations. Cure performance for the four new coating baths is shown in Table II along with previously determined results of prior art, high and low catalyst concentration two component compositions (Examples 5 and 6).
__ \
. \
Jo 605I~?27 TABLE II
Oven Dwell Time_fo~ Cure, Seconds Coating BathppmPt200CF250~F300DF 350F 400F 450F
Example 1 151 26 9 3 2 1.5 Example 2 110 26 9 3 2 lo 5 Example 3 67 NC 18 9 4 2.0 Example 4 25 NC NC 18 5 2.0 --Example 5 150 26 S 3 2 1.5 Example 6 25 NC NC 18 10 5.0 3 vote: NC = Jo Cure The results shown in Table If illustrate -the versatility of the multi-component system of -the present invention and -the improvemeirlt over the prior art. Premium performance solvent less products of the -type utilized in Example 5 rely on high concentrations of platinum catalyst to allow cure at oven temperatures as low as 200F (93C). Lo can be seen that the cure performance of Example 2 was indistinguishable from that of Example 1 and Example 5 despite the fact that it contained only 73% as such platinum catalyst. Thus, the instant invention offers the same low temperature cure performance as prior art two component compositions but a-t a substantially reduced cost because of more efficient use of the precious metal catalyst.
Additionally, a comparison of the cure time versus temperature for Example 4 and Example 6, both of which contain similar low concentrations of catalyst, reveals enhanced performance even with platinum catalyst levels of 25 Pam. This is most clear at 350F where the composition made according to the method of the present invention cured in 5 seconds whereas a substantially identical two part prior art composition required 10 seconds to cure.
Such faster cure translates into higher line speed and thus lower per unit cost for end-users.
I
(R)nS-~o~-n (V) --where R is as defined above and n has a value of from 0.8 to 2.5 inclusive. Thus, where -the olefin-organopolysiloxane employed herein is a copolymerof units within the scope of Formula IV and an organopolysiloxane having an average formula within the scope of Formula V, the copolymer generally contains from 0.5 to 99.5 mole percent of the units of Formula IV and from 0.5 to 99.5 mole percent of units within the scope of Formula V. The preparation of these copolymers is well known to those skilled in the art.
A major proportion of -the composition is typically a vinyl chain-s-topped polysiloxane having the general formula:
R R f R R
R t R So - So - OH C 2 wherein R is a monovalent hydrocarbon radical free of unsaturation. Suitable radicals for R include, for example, methyl, ethyl, propel, bottle and other similar unsaturated hydrocarbons, but ordinarily would not include phenol groups for paper release purposes. Al is a hydrocarbon radical having alkenyl unsa-turation. Typically R represents vinyl groups but may also represent allylic or cycloalkenyl unsaturated groups; x and y are positive integers such that -the vinyl chain-stopped polysiloxane has up to approximately 20~ by weight of Al groups.
The viscosity of such a polysiloxane ranges from approximately 50 to approximately 100,000 centipoise at 25C. Preferably the vinyl chain-stopped polysiloxane has up to approximately 20% by weight of vinyl groups and the viscosity ranges from approximately 300 to approximately 550 centipoise at 25C. The preferred vinyl chain-stopped polysiloxane has -the general formula:
Ho SHEA = OH So So So t So OH C 2 SHEA SHEA SHEA y SHEA
wherein x and y are as described above.
The sullenly end-s-topped polysiloxanes of Formula It are prepared by the equilibration of cyclic polysiloxanes with an alkali metal hydroxide catalyst. The desired viscosity is obtained by controlling the amount of water added to the reaction. These procedures are described in the literature and are well known to those skilled in the art.
Component B contains a precious metal catalyst effective for initiating a hydrosilation cure reaction.
The precious metal catalyst component utilized in compositions of the present invention includes all of the well known platinum and rhodium catalysts which are effective for catalyzing the reaction between silicon-bonded hydrogen atoms end silicon-bonded olefinic groups, and which are freely miscible in solvent-free silicone polymers. These materials especially include the platinum hydrocarbon complexes described in US. Patent No. 3,159,601 and U S. Patent No. 3,159,662 to Ashy, and the platinum alcohol ate catalysts described in US. Patent No. 3,220,970 to Limericks, as well as the platinum catalysts of US. Patent Jo. 3,814,730 to Karstedt. Additionally, the platinum chloride-olefin complexes described in US. Patent No. 3,516,946 to Medic are also useful herein.
A particularly useful catalyst for facilitating the hydrosilation reaction is the Karstedt catalyst described in US. Patent No. 3,814,730. Other platinum metal catalysts can be utilized in -the practice of the present invention; however, their selection depends upon such factors as the required reaction rate, expense, useful pot-life and the temperature at which the cure reaction is to take place. Other metal catalysts useful in the present invention include those which are silicone soluble complexes of the metals rhodium, ruthenium, palladium, osmium, iridium and platinum.
or coating compositions of the present invention, the amount of catalyst ranges from approximately 10 to approximately 500 Pam (as weight of metal atoms), again depending on such factors as speed of reaction and cost requirements. Preferably, the amount of catalyst is approximately 10 to 150 Pam of the precious metal.
Component or Package C is a methyl hydrogen fluid utilized by those skilled in the art as a cross-linking agent for Jo addition cure silicone systems. Particularly useful as a cross-linking agent for -the present invention is a trim ethyl chain-stopped polyme-thylhydrogen selection fluid having from approximately 10% to approximately 100 Six groups, any remaining groups being dim ethyl-sulks units, and having a viscosity in the range of from approximately 10 to 1000 centipoise at 25C.
However, any organohydrogenpolysiloxane having -the general formula:
RaHbSio(4-a-b) (II) is within the scope of the present invention.
The organohydrogenpolysiloxanes having structural units represented by Formula II hereinabove are intended to broadly cover fluid organopolysiloxane which are preferably, but not necessarily, free of olefinic unsaturation, but which do contain silanic hydrogen. The organohydrogenpolysiloxanes represented by Formula II are also well known in the art, for example, as described in US. Patent No. 3,344,111 and US. Patent No. 3,436,366.
Among -the radicals included within R of Formula II
are alkyd, such as methyl, ethyl, propel, isopropyl, bottle, octal and the like; cycloalkyl, such as cyclopentyl, cyclohexyl, cycloheptyl and the like;
aureole, such as phenol, naphthyl, toll, xylyl and the like; aralkyl, such as phenylethyl, phenylpropyl and the Lowe; halogenated derivates of the above radicals, including chlorome-thyl, trifluoromethyl, chloropropyl, chlorophenyl, I dibromophenyl, tetrachlorophenyl, deflower-phenol and the like; and cyanoalkyl, such as boatswain-ethyl, gamma-cyanopropyl, beta-cyanopropyl and the like. Also intended to be included within the scope of Formula II are those materials where R is a mixture of -the aforesaid radicals Preferably the R group of Formula II is methyl.
Materials specifically encompassed within Formula II hereinabove include 1,3-dimethyldisiloxane and 1,1,3,3-tetrame-thyldisiloxane, as well as higher polymers containing up to 100,000 or more silicon atoms per molecule. Also included within the scope of Formula II are cyclic materials such as cyclic polymers of methyl hydrogen selection having the general formula:
OH
_ _ so t Jo H / x wherein x is a whole number equal to from 3 to 10 or more. Particularly included is sym-tetramethyl-cyclotetrasiloxane.
The organohydrogenpolysiloxanes employed in the practice of the present invention can also be characterized as copolymers containing at least one unit per molecule having the formula:
c d (4-c-d~ (VI) with the remaining selection units of the organopoly-selection being within the scope of Formula V hereinabove, where R, c, d, and n are as defined above.
Jo Within -the scope of Formula VI are selection units such as hydrogen selection units (HSiO)l 5, methyl hydrogen selection units (HSiCH30), dim ethyl hydrogen selection units (HSi[CH3]20)o 5, and dihydrogen selection units (l~2SiO). In these copolymers, the selection units of Formulae V and VI are present in proportions so as to form a hydrogenpolysiloxane within the scope of Formula II hereinabove. In general such copolymers contain from 0.5 to 99.5 mole percent of selection units of Formula V
and from 0.5 -to 99.5 mole percent of selection units of Formula VI.
Ordinarily for release coating purposes it is preferred that the organohydrogenpolysiloxane cross-linker be essentially a -trim ethyl chain-stopped methylhydrogenpolysiloxane fluid having a viscosity of approximately 10 to 500 centipoise at 25C and a hydrogen content of from approximately 0.1 to 1.67 percent by weight.
Each of Component A, Component B and Component C
are essential for practicing the method of the present invention, and basically comprise the ingredients disclosed by Grenoble in US. Pa-tent No. 4,071,644 for a solvent less silicone release coating composition. In the present invention, however, the respective components are provided the end-user in the form of an article of manufacture having each of the components separately packaged.
Such separate packaging provides the surprising benefits of the present invention such as increased shelf-life, increased workable pot-life and reduction in the amount of precious metal catalyst required to initiate curing. I-t it -to be emphasized that to come within the scope of the present invention, Components, B, and C must be separately Jo packaged. However, additional ingredients such as an inhibitor or cure accelerator may be provided either as a separate component or as a part of another component and still come within the scope of the present invention.
Preferably there is also included a Component D which contains an inhibitor effective for retarding curing or cross-linking at ambient temperatures, but which does not interfere with curing at elevated temperatures. Although it is preferred that the inhibitor be provided as a separate component, it is within the scope of -the present invention if such inhibitor is included with either the base polymer or cross-linking agent. However, the inhibitor should not be packaged with the precious metal catalyst as it is believed that when the inhibitor and catalyst are mixed; the inhibitor forms a complex with the metal atoms of the catalyst which becomes more s-table and less reactive the longer the storage period before use. Accordingly, such packaging would result in substantial lessening of the benefits obtained by the present invention.
Eckberg in US. Patent Nos. 4,256,870, 4,262,107 and 4,347,346 and in Canadian Patent Application Serial Number 463,891 filed December 21, 1983 discloses a variety of inhibitors which have been found useful in silicone release coating compositions. US. Patent No. 4,256,870 discloses that an amount of dialkyl carboxylic ester containing carbon to carbon unsaturation is effective to inhibit the precious metal catalyzed hydrosilation cure reaction at temperatures below the heat cure temperature of the release coating composition. Most preferably such dialkyl carboxylic ester is diallylmaleate which has the formulcl:
~.~
C = C /
SHEA = CHCH2 - O - C C - O -- CH2CH = SHEA
O O
and ordinarily is utilized in a range of from approximately I to approximately 0.5~ by weight. Other preferred diallylic carboxylic esters which are preferred include diallylphthalate and diallylsuccinate. Also, saturated dialkyl esters of malefic acid, such as deathly and dim ethyl Malta, and mixed esters such as butylallylmaleate or methyle-thylmaleate are useful as hydrosilation inhibitors for solvent less release coating compositions.
The use of an olefinic carboxylic acid ester of an aliphatic alcohol is disclosed by Eckberg as an inhibitor for rhodium catalyzed silicone rubber compositions in US. Patent No. 4,262,107. Therein it is taught that such compositions can be utilized at low concentrations, such as from 0.1 to 2 parts per 100 parts of the sullenly base polymer, but preferably should be utilized in a concentration of 0.5 to 5 parts per 100 parts of the sullenly base polymer. The preferred inhibitor compound is vinyl acetate; however, those olefinic carboxylic acid esters of an aliphatic alcohol wherein the alcohol has from 1 to 4 carbon atom and the olefinic carboxylic acid has from 2 to 10 carbon atoms are within the scope of the disclosure.
US. Patent No. 4,347,346 discloses that dialkyl-acetylenedicarboxylates are effective inhibitors for preventing premature gelatin at ambient temperatures and which do not interfere with curing at elevated temperatures.
The most preferred inhibitor is that: disclosed in Can. Ser. No. 463,891 filed December 21, 19~3 and assigned -to the same assignee as the present invention.
Generally, -the invention of Canadian Serial No. 463,891 is based on -the surprising discovery -that a blend of a dialkyl carboxylic ester containing carbon to carbon unsaturation and an olefinic carboxylic acid ester of an aliphatic alcohol results in a blend which is a more effective inhibitor than utilizing similar amounts of the individual compounds, that is, a synergistic effect is obtained by such a blend of inhibitors.
The most preferred dialkyl carboxylic ester containing carbon to carbon unsaturation is Delilah-Malta; however, any of the inhibitor compositions within the scope of US. Patent No. 4,256,~70 can also be utilized. Among the preferred inhibitor compositions which also can be utilized are butylallylmaleate, Delilah-succinate, dimethylmaleate, diethylmaleate and sill-Maltese such as bus -propyltris (methoxy) silylmaleate which has the formula:
H H
OH O C = C O OH
/ 2 / / \ / \ 2 SHEA SHEA C C OH OH
Swish O O Swish The most preferred olefinic carboxylic acid ester of an aliphatic alcohol is vinyl acetate; however, any inhibitor compound within the scope of So Patent No.
4,262,107 may also be utilized. More particularly, such compounds are those derived from an aliphatic alcohol having 1 to 4 carbon atoms and an olefinic carboxylic acid having from 2 to 10 carbon atoms.
so it I
The Delco] carboxylic ester having carbon to carbon unsaturation, preferably diallylmaleate or bottle-allylmaleate, is blended with the olefinic carboxylic acid ester of an aliphatic alcohol, preferably vinyl acetate, in a ratio ranging from approximately 1:24 to 1:1, but most preferably is blended in approximately a 1:3 ratio. Accordingly, -the most preferred inhibitor for -the release coating composition is a blend comprising 1 part diallylmaleate and 3 parts vinyl acetate.
I Can. Ser. No. 463,~91 teaches that small amounts of such a two-part inhibitor permit exceptionally long catalyzed pot-life without sacrifice of cure performance, especially in compositions having a high platinum content.
Ordinarily the effective amount of inhibitor ranges from approximately 0.05 to approximately 2% by weight, and preferably from 0.1 to 0.5~ by weight. Use of such two-part inhibitor results in improved pot life yet the composition rapidly cures to a smear-free and migration-free non adherent surface when thermally cured.
Another optional ingredient is a vinyl gum cure accelerator of the type disclosed by Eckberg in United States Patent Number 4,340,647, which is assigned to the same assignee as the present invention.
Therein it is disclosed that a dimethylvinyl chain-stopped polydimethylmethylvinylsiloxane polymer gum will accelerate the hydrosilation cure reaction at a relatively low temperature without sacrificing performance.
Such vinyl gum cure accelerator may be provided as Component E of the article of manufacture of the present invention. However, it is preferable that such cure accelerator be provided in -the same package as the base polymer.
I' .~, What is disclosed and claimed by the present invention is a basic system for producing a silicone release coating composition and an article of manufacture for providing the ingredients necessary to formulate such release coating composition. The article of manufacture includes at least three components or packages, but may contain more, depending on whether optional ingredients are provided in a separate package or mixed with the ingredients of another lo package.
IJse of the article of manufacture of -the present invention for providing the ingredients utilized in the method of the present invention results in improved shelf-life, bath-life, reduction in the amount of precious metal catalyst required to initiate curing, and greater flexibility in formulating a bath to meet specific end-user requirements.
In order that those skilled in the art might be better able to practice the present invention, the following examples are given by way of illustration and not by way of limitation.
Examples l Tao In the following examples, release coating compositions were prepared from the following ingredients:
(A) a mixture consisting of lo parts of a linear dimethylvinyl chain-stopped polydimethyl-selection fluid having a viscosity of 120 cups at 25 DC and 5 parts of a dimethylvinyl chain-stopped linear polydimethylmethylvinyl-selection copolymer glum having a molecular weight of approximately 300,000 and containing 0.2 mole percent methyl vinyl selection units, such mixture having a viscosity of approximately 40t) cups at 25C;
(B) a solution of a platinum catalyst in a dimethylvinyl end stopped polydimethyl-selection fluid having a viscosity of 300 cups at 25C, there being sufficient catalyst present to afford 1800 Pam platinum (as metal) in the solution;
(C) a trimethylsiloxy chain-stopped linear polymethylhydrogensiloxane fluid having a viscosity of approximately 15 to 40 cups at 25C as a cross-linking agent; and (D) a blend of 3 parts vinyl acetate to 1 part of diallylmaleate.
Silicone release coating composition baths were prepared by mixing the four components as described in Table I. It should be noted that the inhibitor is provided as Component D and the vinyl gum cure accelerator is included with the base polymer in Component A. All parts are by weight.
TABLE I
Coating Bath Parts parts B Parts C Parts D
Example 1 100 8.4 4.4 1.2 Example 2 100 6.1 4.3 0.87 Example 3 100 3.7 4.2 0.53 Example 4 100 1.4 4.1 0.2 - ,4 - SUE 727 It can be seen that the relative ratio of catalyst (par-t B) to inhibitor (part D) was maintained a-t approximately 7:1 in all, four baths. The silicone release coating compositions of Examples 1 to 4 were coated onto 40 pound super calendered Croft (SUCK) substrate on an 18 inch three roll offset Grover pilot coaler equipped with forced air ovens.
Depositions of 0.5 to 0.7 pounds per 3000 square feet were measured. The oven dwell time required for cure to smear and migration-free adhesive surface was determined for each coating bath as a function of oven temperature.
No significant increase in viscosity (that is, the coating characteristics were not altered) over an eight hour period was observed for any of the formulations. Cure performance for the four new coating baths is shown in Table II along with previously determined results of prior art, high and low catalyst concentration two component compositions (Examples 5 and 6).
__ \
. \
Jo 605I~?27 TABLE II
Oven Dwell Time_fo~ Cure, Seconds Coating BathppmPt200CF250~F300DF 350F 400F 450F
Example 1 151 26 9 3 2 1.5 Example 2 110 26 9 3 2 lo 5 Example 3 67 NC 18 9 4 2.0 Example 4 25 NC NC 18 5 2.0 --Example 5 150 26 S 3 2 1.5 Example 6 25 NC NC 18 10 5.0 3 vote: NC = Jo Cure The results shown in Table If illustrate -the versatility of the multi-component system of -the present invention and -the improvemeirlt over the prior art. Premium performance solvent less products of the -type utilized in Example 5 rely on high concentrations of platinum catalyst to allow cure at oven temperatures as low as 200F (93C). Lo can be seen that the cure performance of Example 2 was indistinguishable from that of Example 1 and Example 5 despite the fact that it contained only 73% as such platinum catalyst. Thus, the instant invention offers the same low temperature cure performance as prior art two component compositions but a-t a substantially reduced cost because of more efficient use of the precious metal catalyst.
Additionally, a comparison of the cure time versus temperature for Example 4 and Example 6, both of which contain similar low concentrations of catalyst, reveals enhanced performance even with platinum catalyst levels of 25 Pam. This is most clear at 350F where the composition made according to the method of the present invention cured in 5 seconds whereas a substantially identical two part prior art composition required 10 seconds to cure.
Such faster cure translates into higher line speed and thus lower per unit cost for end-users.
I
Claims (42)
1. A process for providing a substrate having a silicone release coating composition cured thereon comprising the steps of:
(a) mixing 100 parts by weight of Component A
with 5 to 100 parts of Component B and 3 to 10 parts of Component C, wherein Component A is an olefinorgano-polysiloxane or a silanol end-stopped organopolysiloxane base polymer, Component B is a precious metal or precious metal complex catalyst dispersed in a vinyl silicone fluid; and Component C is an organohydrogenpolysiloxane cross-linking agent, wherein Component A and/or Component C
further includes an amount of inhibitor effective for retarding a hydrosilation cure reaction at ambient temperature but which does not interfere with such reaction at elevated temperatures and wherein prior to use Component A, Component B and Component C are stored in separate containers;
(b) applying a coating of the mixture comprising Component A, Component B and Component C to a suitable substrate; and (c) curing said coating to said substrate.
(a) mixing 100 parts by weight of Component A
with 5 to 100 parts of Component B and 3 to 10 parts of Component C, wherein Component A is an olefinorgano-polysiloxane or a silanol end-stopped organopolysiloxane base polymer, Component B is a precious metal or precious metal complex catalyst dispersed in a vinyl silicone fluid; and Component C is an organohydrogenpolysiloxane cross-linking agent, wherein Component A and/or Component C
further includes an amount of inhibitor effective for retarding a hydrosilation cure reaction at ambient temperature but which does not interfere with such reaction at elevated temperatures and wherein prior to use Component A, Component B and Component C are stored in separate containers;
(b) applying a coating of the mixture comprising Component A, Component B and Component C to a suitable substrate; and (c) curing said coating to said substrate.
2. The process of claim 1 wherein the base polymer is an olefinorganopolysiloxane having structural units of the formula.
or is a silanol end-stopped organosiloxane having the general formula:
wherein R is an organic radical attached to silicon by a C-Si linkage and is selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals, and cyanoalkyl radicals and mixtures thereof, and which has from 1 to 30 carbon atoms; R1 is an olefinic hydrocarbon radical having from 1 to 20 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive, and the sum of a and b equals 0.8 to 3 inclusive, and the olefinorganosiloxane has a viscosity ranging from approximately 10 centipoise to approximately 5000 centipoise at 25°C, and x is such that the viscosity of the silanol end-stopped polysiloxane has a viscosity between approximately 10 centipoise and approximately 5000 centipose at 25°C.
or is a silanol end-stopped organosiloxane having the general formula:
wherein R is an organic radical attached to silicon by a C-Si linkage and is selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals, and cyanoalkyl radicals and mixtures thereof, and which has from 1 to 30 carbon atoms; R1 is an olefinic hydrocarbon radical having from 1 to 20 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive, and the sum of a and b equals 0.8 to 3 inclusive, and the olefinorganosiloxane has a viscosity ranging from approximately 10 centipoise to approximately 5000 centipoise at 25°C, and x is such that the viscosity of the silanol end-stopped polysiloxane has a viscosity between approximately 10 centipoise and approximately 5000 centipose at 25°C.
3. The process of claim 1 wherein the organo-hydrogenpolysiloxane cross-linking agent has structural units of the formula:
wherein R is an organic radical selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals and cyanoalkyl radicals and mixtures thereof and which has from 1 to 30 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive, and the sum of a and b equals 0.8 to 3 inclusive, and wherein the viscosity ranges from approximately 10 to 5000 centipoise at 25°C.
wherein R is an organic radical selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals and cyanoalkyl radicals and mixtures thereof and which has from 1 to 30 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive, and the sum of a and b equals 0.8 to 3 inclusive, and wherein the viscosity ranges from approximately 10 to 5000 centipoise at 25°C.
4. The process of claim 2 wherein R is methyl.
5. The process of claim 3 wherein R is methyl.
6. The process of claim 2 wherein R1 is vinyl or allyl.
7. The process of claim 1 wherein the olefin-organopolysiloxane is a dimethylvinyl chain-stopped dimethylmethylvinylpolysiloxane copolymer fluid having a viscosity of approximately 100 to 1000 centipoise at 25°C and a vinyl content of up to 2.5 weight percent.
8. The process of claim 1 wherein the organohydrogenpolysiloxane is a trimethyl chain-stopped methylhydrogenpolysiloxane fluid having a viscosity of approximately 10 to 500 centipoise at 25°C and a hydrogen content of approximately 0.1 to 1.67 percent by weight.
9. The process of claim 1 wherein the precious metal catalyst is selected from the group consisting of platinum metal, rhodium metal, complexes of platinum metal and complexes of rhodium metal.
10. The process of claim 9 wherein the precious metal catalyst is present in an amount sufficient to provide approximately 5 to 500 parts of platinum or rhodium metal per million parts of base polymer.
11. The process of claim 1 wherein the inhibitor is provided as Component D, further comprising mixing 0.1 to 5 parts of Component D with 100 parts of a mixture of Component A, Component B and Component C.
12. The process of claim 11 wherein the inhibitor is selected from the class consisting of dialkyl carboxylic esters containing carbon to carbon unsaturation, compounds containing an acetylenic group, olefinic carboxylic acid esters of aliphatic alcohols where the aliphatic alcohol contains from 1 to 4 carbon atoms and the olefinic carboxylic acid contains from 2 to 10 carbon atoms, alkenyl isocyanurates wherein the alkenyl group contains from 3 to 8 carbon atoms, dialkylacetylene-dicarboxylates, and a blend of a dialkylcarboxylic ester having carbon to carbon unsaturation with an olefinic carboxylic acid ester of an aliphatic alcohol where the aliphatic alcohol contains from 1 to 4 carbon atoms and the olefinic carboxylic acid contains from 2 to 10 carbon atoms.
13. The process of claim 11 wherein the inhibitor is a blend of a dialkylcarboxylic ester having carbon to carbon unsaturation and an olefinic carboxylic acid ester of an aliphatic alcohol, where the aliphatic alcohol contains from 1 to 4 carbon atoms and the olefinic carboxylic acid contains from 2 to 10 carbon atoms.
14. The process of claim 13 wherein the dialkylcarboxylic ester is selected from the group consisting of diallylmaleate, butylallylmaleate, diallylsuccinate and dialkyl esters of maleic acid selected from the group consisting of dimethylmaleate, diethylmaleate and silylmaleate.
15. The process of claim 13 wherein the olefinic carboxylic acid ester of an aliphatic alcohol is vinyl acetate.
16. The process of claim 13 wherein the dialkyl carboxylic ester is blended with the olefinic carboxylic acid ester of an aliphatic alcohol in a ratio of from approximately 1:24 to approximately 1:1.
17. The process of claim 13 wherein the dialkyl carboxylic ester is blended with the olefinic carboxylic acid ester of an aliphatic alcohol in a ratio of approximately 1 to 3.
18. The process of claim 13 wherein diallylmaleate is blended with vinyl acetate in a ratio of approximately 1 to 3.
19. The process of claim 11 wherein there is sufficient inhibitor present in Component D so as to be present in the mixture in an amount ranging from approximately 0.05 to 2 percent by weight.
20. The process of claim 1 further comprising mixing 0.1 to 10 parts of Component E with 100 parts of a mixture of Component A, Component B and Component C, wherein Component E is a vinyl gum cure accelerator effective for accelerating the cure of said addition curable release coating composition and wherein said gum has an average molecular weight of approximately 200,000 to 400,000.
21. The process of claim 20 wherein said gum is present in the mixture in the amount of at least 0.5 weight percent of said addition curable release coating compositions.
22. An article of manufacture comprising:
(a) 100 parts by weight of Component A, (b) 5 to 100 parts by weight of Component B, and (c) 3 to 10 parts by weight of Component C, wherein Component A is an olefinorganopolysiloxane or a silanol end-stopped organopolysiloxane base polymer, Component B is a precious metal or precious metal complex catalyst dispersed in a vinyl silicone fluid, and Component C is an organohydrogenpolysiloxane cross-linking agent; wherein Component A and/or Component C further includes an amount of inhibitor effective for retarding a hydrosilation cure reaction at ambient temperature but does not interfere with such reaction at elevated temperatures and wherein Component A, Component B and Component C are contained separate from one another.
(a) 100 parts by weight of Component A, (b) 5 to 100 parts by weight of Component B, and (c) 3 to 10 parts by weight of Component C, wherein Component A is an olefinorganopolysiloxane or a silanol end-stopped organopolysiloxane base polymer, Component B is a precious metal or precious metal complex catalyst dispersed in a vinyl silicone fluid, and Component C is an organohydrogenpolysiloxane cross-linking agent; wherein Component A and/or Component C further includes an amount of inhibitor effective for retarding a hydrosilation cure reaction at ambient temperature but does not interfere with such reaction at elevated temperatures and wherein Component A, Component B and Component C are contained separate from one another.
23. The article of manufacture of claim 22 wherein the base polymer is an olefinorganopolysiloxane having structural units of the formula:
or is a silanol end-stopped organosiloxane having the general formula:
wherein R is an organic radical attached to silicon by a C-Si linkage and is selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals, and cyanoalkyl radicals and mixtures thereof, and which has from 1 to 30 carbon atoms, R1 is an olefinic hydrocarbon radical having from 1 to 20 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive, and the sum of a and b equals 0.8 to 3 inclusive, and the olefinorganopolysiloxane has a viscosity ranging from approximately 10 centipoise to approximately 5000 centipoise at 25°C, and x is such that the viscosity of the silanol end-stopped polysiloxane has a viscosity between approximately 10 centipoise and approximately 5000 centipoise at 25°C.
or is a silanol end-stopped organosiloxane having the general formula:
wherein R is an organic radical attached to silicon by a C-Si linkage and is selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals, and cyanoalkyl radicals and mixtures thereof, and which has from 1 to 30 carbon atoms, R1 is an olefinic hydrocarbon radical having from 1 to 20 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive, and the sum of a and b equals 0.8 to 3 inclusive, and the olefinorganopolysiloxane has a viscosity ranging from approximately 10 centipoise to approximately 5000 centipoise at 25°C, and x is such that the viscosity of the silanol end-stopped polysiloxane has a viscosity between approximately 10 centipoise and approximately 5000 centipoise at 25°C.
24. The article of manufacture of claim 22 wherein the organohydrogenpolysiloxane cross-linking agent has structural units of the formula:
wherein R is an organic radical selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals and cyanoalkyl radicals and mixtures thereof and which has from 1 to 30 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive and the sum of a and b equals 0.8 to 3 inclusive and wherein the viscosity ranges from approximately 10 to 5000 centipoise at 25°C.
wherein R is an organic radical selected from the group consisting of monovalent hydrocarbon radicals, halogenated monovalent hydrocarbon radicals and cyanoalkyl radicals and mixtures thereof and which has from 1 to 30 carbon atoms, a has a value ranging from 0 to 3 inclusive, b has a value ranging from about 0.005 to about 2.0 inclusive and the sum of a and b equals 0.8 to 3 inclusive and wherein the viscosity ranges from approximately 10 to 5000 centipoise at 25°C.
25. The article of manufacture of claim 23 wherein R is methyl.
26. The article of manufacture of claim 24 wherein R is methyl.
27. The article of manufacture of claim 23 wherein R1 is vinyl or allyl.
28. The article of manufacture of claim 22 wherein the olefinorganopolysiloxane is a dimethylvinyl chain-stopped dimethylmethylvinylpolysiloxane copolymer fluid having a viscosity of approximately 100 to 1000 centipoise at 25°C and a vinyl content of up to 2.5 weight percent.
29. The article of manufacture of claim 22 wherein the organohydrogenpolysiloxane is a trimethyl chain-stopped methylhydrogenpolysiloxane fluid having a viscosity of approximately 10 to 500 centipoise at 25°C and a hydrogen content of approximately 0.1 to 1.67 percent by weight.
30. The article of manufacture of claim 22 wherein the precious metal catalyst is selected from the group consisting of platinum metal, rhodium metal, complexes of platinum metal and complexes of rhodium metal.
31. The article of manufacture of claim 30 wherein the precious metal catalyst is present in an amount sufficient to provide approximately 5 to 500 parts of platinum or rhodium metal per million parts of base polymer.
32. The article of manufacture of claim 22 wherein the inhibitor is provided as 0.1 to 5 parts by weight Component D.
33. The article of manufacture of claim 32 wherein the inhibitor is selected from the class consisting of dialkyl carboxylic esters containing carbon to carbon unsaturation, compounds containing an acetylenic group, olefinic carboxylic acid esters of aliphatic alcohols where the aliphatic alcohol contains from 1 to 4 carbon atoms and the olefinic carboxylic acid contains from 2 to 10 carbon atoms, alkenyl isocyanurates wherein the alkenyl group contains from 3 to 8 carbon atoms, dialkylacetylenedicarboxylates, and a blend of a dialkylcarboxylic ester having carbon to carbon unsaturation with an olefinic carboxylic acid ester of an aliphatic alcohol where the aliphatic alcohol contains from 1 to 4 carbon atoms and the olefinic carboxylic acid contains from 2 to 10 carbon atoms.
34. The article of manufacture of claim 32 wherein the inhibitor is a blend of a dialkylcarboxylic ester having carbon to carbon unsaturation and an olefinic carboxylic acid ester of an aliphatic alcohol, where the aliphatic alcohol contains from 1 to 4 carbon atoms and the olefinic carboxylic acid contains from 2 to 10 carbon atoms.
35. The article of manufacture of claim 34 wherein the dialkylcarboxylic ester is selected from the group consisting of diallylmaleate, butylallylmaleate, diallylsuccinate and dialkyl esters of maleic acid selected from the group consisting of dimethylmaleate, diethylmaleate and silylmaleate.
36. The article of manufacture of claim 34 wherein the olefinic carboxylic acid ester of an aliphatic alcohol is vinyl acetate.
37. The article of manufacture of claim 34 wherein the dialkyl carboxylic ester is blended with the olefinic carboxylic acid ester of an aliphatic alcohol in a ratio of from approximately 1:24 to approximately 1:1.
38. The article of manufacture of claim 34 wherein the dialkyl carboxylic ester is blended with the olefinic carboxylic acid ester of an aliphatic alcohol in a ratio of approximately 1 to 3.
39. The article of manufacture of claim 34 wherein diallylmaleate is blended with vinyl acetate in a ratio of approximately 1 to 3.
40. The article of manufacture of claim 32 wherein there is sufficient inhibitor present in Component D so as to be present in a mixture of the components in an amount ranging from approximately 0.005 to 2 percent by weight.
41. The article of manufacture of claim 22 further comprising 0.1 to 10 parts of Component E, wherein Component E is a vinyl gum cure accelerator effective for accelerating the cure of said addition curable release coating composition and wherein said gum has an average molecular weight of approximately 200,000 to 400,000.
42. The article of manufacture of claim 41 wherein said gum is present in Component E in an amount sufficient to provide at least 0.5 weight percent gum in a mixture of the components.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000447719A CA1211589A (en) | 1984-02-17 | 1984-02-17 | Multi-component solventless silicone release coating system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000447719A CA1211589A (en) | 1984-02-17 | 1984-02-17 | Multi-component solventless silicone release coating system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1211589A true CA1211589A (en) | 1986-09-16 |
Family
ID=4127227
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000447719A Expired CA1211589A (en) | 1984-02-17 | 1984-02-17 | Multi-component solventless silicone release coating system |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1211589A (en) |
-
1984
- 1984-02-17 CA CA000447719A patent/CA1211589A/en not_active Expired
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