Curable silicone rubber composition

Abstract

The present disclosure relates to curable silicone rubber compositions suitable for use in the manufacture of cured-in-place gaskets (CIPGs), silicone elastomers resulting from the curing of such compositions, and methods for making cured-in-place gaskets from such curable silicone rubber compositions, comprising a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule, (i)(R 10 ) z (R 11 ) 3-z Si-(W)-Si(R 11 ) 3-z (R 10 ) z [In the formula, each R 11 are the same or different and are alkoxy groups having 1 to 6 carbon atoms; 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, z is 0 or 1, and W is a linear or branched alkylene group having 1 to 12 carbon atoms; or (ii) 1,3,5-tris[3-((R 10 ) z (R 11 ) 3-z Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [In the formula, R 11 , R 10 and z is as defined above, and D is an alkylene group having 1 to 6 carbon atoms, provides a CIPG that exhibits both good adhesion to aluminum and good compression set.

Description

[Technical Field]

[0001] The present disclosure relates to curable silicone rubber compositions suitable for use in making cure-in-place gaskets (CIPGs), silicone elastomers obtained from the curing of such compositions, and methods for making cure-in-place gaskets from such curable silicone rubber compositions.

[0002] Curable silicone rubber compositions, often referred to as hydrosilylation- or addition-curable liquid silicone rubber compositions, which comprise a polydiorganosiloxane polymer having an average of two or more unsaturated groups selected from alkenyl and / or alkynyl groups, an organohydrogensiloxane containing silicon-bonded hydrogen (Si-H) groups, and a platinum-group-containing catalyst, are well known and used in a wide variety of applications. However, it is also well known that such compositions exhibit poor adhesion to / onto the substrate on which they are cured. Many additives have been developed in an attempt to improve adhesion of such compositions to substrates. However, when many of these additives are used to improve adhesion, the compression set (i.e., the permanent deformation remaining after removal of an applied force at a specific temperature for a specific time) of the resulting elastomer increases significantly, which is clearly problematic for applications requiring low compression set. For example, cured-in-place gaskets are a preferred means of sealing a wide variety of automotive and industrial applications. For cured-in-place gaskets, the silicone rubber composition is typically applied as a bead or thread of silicone rubber composition onto the target surface from a suitable applicator that effectively creates a mold for the desired gasket. The applicator used may be a robotic applicator that is preprogrammed to control the application of the thread of silicone rubber composition to provide a gasket with the desired shape and minimal waste. Once the silicone rubber composition is fully applied, it is cured in place.

[0003] Silicone rubber compositions in the preparation of cure-in-place gasket (CIPG) materials are typically stored as two-component compositions to prevent premature curing, but when the two components are mixed together, it is important that the reactive mixture, applied in liquid form, remain in a liquid state long enough to prevent applicator contamination and / or blocking. Furthermore, following cure, the resulting CIPG must form an unprimed bond to the substrate to which it is applied while also possessing good thermal stability, low compression set, and optionally low durometer (e.g., 30-40 Shore A) product properties.

[0004] Cured-in-place gaskets (CIPGs) are used in a wide variety of automotive and industrial sealing applications and may be required to adhere to a wide variety of metallic substrates, such as aluminum (one of the primary substrates in electric vehicle (EV) motor control unit (MCU) devices), coated metallic substrates, and / or plastic substrates. CIPGs may be utilized for sealing engine components, such as valve covers, rocker covers, timing chain covers, and oil pans in automotive engines, as well as housing seals and coolant area seals in the aforementioned motor control unit (MCU) devices for electric vehicles (EVs), as well as a variety of other industrial sealing applications.

[0005] Low compression set is required because gaskets are used to prevent leaks at joints formed between different components. Low compression set is considered up to 40% compression set after 22 hours at 177°C according to ASTM D395 Method B, which is the maximum acceptable result. The ability to identify CIPGs with both good adhesion to aluminum substrates and low compression set as defined above has been a long-standing problem for the industry, given that existing CIPG silicone rubber compositions can exhibit one or the other, but not both. While low compression set, non-slump, and fast-cure silicone rubber compositions are known, their adhesion to aluminum substrates is not stable, especially in low Shore A (e.g., 30-40) CIPG products. While stable adhesion with aluminum substrates can be achieved using adhesion promoter packages such as zirconium(IV) acetylacetonate / γ-glycidoxypropyltrimethoxysilane, aluminum acetylacetonate and its solvent—toluene, tetra n-butyl titanate, glycidyloxypropyltrimethoxysilane, methyl methacrylate, and / or tetrapropyl orthosilicate—for unprimed adhesion to various metal and plastic substrates, the use of such adhesion promoters results in unacceptably high values ​​of compression set, in the range of 48% or greater, after 22 hours at 177° C. according to ASTM D395 Method B. In view of the above, an opportunity remains to provide a curable silicone composition that, upon cure, provides a low compression set of 40% or less, alternatively 39% or less, after 22 hours at 177° C. according to ASTM D395 Method B, and good adhesion to aluminum substrates.

[0006] Provided herein is a curable silicone rubber composition comprising the following components: a) a polydiorganosiloxane having per molecule at least two unsaturated groups selected from alkenyl or alkynyl groups; b) an organosilicon compound having at least two, alternatively at least three, Si—H groups per molecule; c) at least one silica reinforcing filler or one or more non-reinforcing fillers selected from quartz, diatomaceous earth and calcium carbonate, or a mixture of both, wherein each filler present has been hydrophobized; d) a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof; e) a tetraalkyl titanate, wherein each alkyl group may be the same or different and has 1 to 20 carbon atoms, and is present in an amount of 0.01 to 0.15 weight percent of the composition; f) an alkyl polysilicate, wherein the alkyl groups may be the same or different and may contain up to 6 carbon atoms per group, present in an amount of 0 to 2.5% by weight of the composition; g) a suitable (meth)acrylate compound present in an amount of 0.1 to 2.5% by weight of the composition; h) a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule, (i)(R 10 ) z (R 11 ) 3-z Si-(W)-Si(R 11 ) 3-z (R 10 ) z [In the formula, each R 11 are the same or different and are alkoxy groups having 1 to 6 carbon atoms; 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, z is 0 or 1, and W is a linear or branched alkylene group having 1 to 12 carbon atoms; or (ii) 1,3,5-tris[3-((R 10 ) z (R 11 ) 3-z Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [In the formula, R 11 , R 10 and z is as defined above, and D is an alkylene group having 1 to 6 carbon atoms.

[0007] The present invention also provides a cured silicone rubber obtained by curing the above curable silicone rubber composition.

[0008] The present invention also relates to a cured silicone rubber obtained or obtainable by mixing and curing the above-described curable silicone rubber composition, and / or a cured-in-place gasket (CIPG) obtained or obtainable by mixing and curing the above-described curable silicone rubber composition. Also provided is a cured silicone rubber or a cured-in-place gasket (CIPG) comprising the cured product of the above-described curable silicone rubber composition.

[0009] A method for producing cured silicone rubber and / or cure-in-place gaskets (CIPG) is provided by mixing and curing a curable silicone rubber composition comprising the following components: a) a polydiorganosiloxane having at least two unsaturated groups selected from alkenyl or alkynyl groups per molecule; b) an organosilicon compound having at least two, alternatively at least three, Si—H groups per molecule; c) at least one silica reinforcing filler or one or more non-reinforcing fillers selected from quartz, diatomaceous earth and calcium carbonate, or a mixture of both, wherein each filler present has been hydrophobized; d) a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof; e) a tetraalkyl titanate, wherein each alkyl group may be the same or different and has 1 to 20 carbon atoms, and is present in an amount of 0.01 to 0.15 weight percent of the composition; f) an alkyl polysilicate, wherein the alkyl groups may be the same or different and may contain up to 6 carbon atoms per group, present in an amount of 0 to 2.5% by weight of the composition; g) a suitable (meth)acrylate compound present in an amount of 0.1 to 2.5% by weight of the composition; and h) a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule, (i)(R 10 ) z (R 11 ) 3-z Si-(W)-Si(R 11 ) 3-z (R 10 ) z [In the formula, each R 11 are the same or different and are alkoxy groups having 1 to 6 carbon atoms; 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, z is 0 or 1, and W is a linear or branched alkylene group having 1 to 12 carbon atoms; or (ii) 1,3,5-tris[3-((R 10 ) z (R 11 ) 3-z Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [In the formula, R 11 , R 10 and z is as defined above, and D is an alkylene group having 1 to 6 carbon atoms.

[0010] Also provided is the use of the curable silicone rubber composition to make a cured silicone rubber and / or cure-in-place gasket (CIPG) that adheres to an aluminum substrate while retaining a compression set of 40% or less, alternatively 39% or less, after being tested at 177°C for 22 hours according to ASTM D395 Method B.

[0011] Surprisingly, it has been found that the incorporation of component (h) into the composition surprisingly improves the adhesion of the composition to an aluminum substrate. Adhesion to the substrate, i.e., the ability to achieve good / stable adhesion of a CIPG to an aluminum substrate (i.e., a lap shear of greater than 1.5 MPa as measured in accordance with ASTM D 816-82 (reapproved in 2001) using a Type I lap specimen shown in Figure 1 thereof, while retaining a compression set of 40% or less, alternatively 39%, after 22 hours at 177°C according to ASTM D395 Method B), has long been a challenge. Typically, the addition of an adhesion promoter results in good / stable adhesion but causes a significant increase in compression set of more than 40%, e.g., 48% or more, after 22 hours at 177°C according to ASTM D395 Method B.

[0012] All viscosity measurements referred to herein were taken at 25°C unless otherwise indicated.

[0013] "Hydrocarbyl" means a monovalent hydrocarbon group which may be substituted or unsubstituted. Specific examples of hydrocarbyl groups include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, aralkyl groups, and the like.

[0014] "Alkyl" means an acyclic, branched or unbranched saturated monovalent hydrocarbon group. "Aryl" means a fully unsaturated cyclic hydrocarbon group. "Aralkyl" means an alkyl group having pendant and / or terminal aryl groups, or an aryl group having a pendant alkyl group.

[0015] "Alkenylene" means an acyclic, branched or unbranched divalent hydrocarbon group having one or more carbon-carbon double bonds. "Alkylene" means an acyclic, branched or unbranched saturated divalent hydrocarbon group. "Alkynylene" means an acyclic, branched or unbranched divalent hydrocarbon group having one or more carbon-carbon triple bonds. "Arylene" means a cyclic, fully unsaturated divalent hydrocarbon group.

[0016] The term "substituted" when used in connection with another group, for example, a hydrocarbyl group, means that one or more hydrogen atoms are replaced with another substituent in the hydrocarbyl group, unless otherwise specified. Examples of such substituents include, for example, halogen atoms, such as chlorine, fluorine, bromine, and iodine, halogen-containing groups such as chloromethyl, perfluorobutyl, trifluoroethyl, and nonafluorohexyl groups; oxygen atoms; oxygen-containing groups such as (meth)acrylic groups and carboxyl groups.

[0017] The M, D, T and Q units are generally represented by R u SiO( 4-u) / 2 where u is 3, 2, 1, and 0 for M, D, T, and Q, respectively, and R is an independently selected hydrocarbyl group. M, D, T, and Q designate one (mono), two (di), three (tri), or four (quad) oxygen atoms covalently bonded to the silicon atom connecting them to the rest of the molecular structure.

[0018] Component (a) Component (a) is a polydiorganosiloxane having at least two unsaturated groups selected from alkenyl or alkynyl groups per molecule. Alternatively, component (a) has at least three unsaturated groups per molecule.

[0019] The unsaturated groups in component (a) may be at the terminal, pendant, or both positions of component (a). For example, the unsaturated groups may be alkenyl and / or alkynyl groups. Alkenyl is exemplified by, but is not limited to, vinyl, allyl, methallyl, propenyl, and hexenyl groups. The alkenyl groups may have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, or alternatively 2 to 6 carbon atoms. Alkynyl may be exemplified by, but is not limited to, ethynyl, propynyl, and butynyl groups. The alkynyl groups may have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, or alternatively 2 to 6 carbon atoms.

[0020] Component (a) is a compound of formula (I): R a SiO (4-a) / 2 (I) wherein each R is independently selected from aliphatic hydrocarbyl groups, aromatic hydrocarbyl groups, or organyl groups (i.e., any organic substituent having one free valence at a carbon atom, regardless of the type of functional group). Saturated aliphatic hydrocarbyls are exemplified by, but not limited to, alkyl groups such as methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl, and cycloalkyl groups such as cyclohexyl. Unsaturated aliphatic hydrocarbyls are exemplified by, but not limited to, the alkenyl and alkynyl groups listed above. Aromatic hydrocarbon groups are exemplified by, but not limited to, phenyl, tolyl, xylyl, benzyl, styryl, and 2-phenylethyl. Organyl groups are exemplified by, but not limited to, halogenated alkyl groups (excluding fluoro-containing groups) such as chloromethyl and 3-chloropropyl, nitrogen-containing groups such as amino, amido, imino, and imido groups, oxygen-containing groups such as polyoxyalkylene groups, carbonyl groups, alkoxy groups, and hydroxyl groups. Further organyl groups may include sulfur-, phosphorus-, and boron-containing groups. The subscript "a" is 0, 1, 2, or 3.

[0021] Siloxy units may be described by the abbreviated nomenclature, i.e., "M," "D," "T," and "Q," as discussed above (further teachings on silicone nomenclature may be found in Walter Noll, Chemistry and Technology of Silicones, dated 1962, Chapter I, pages 1-9). M units are siloxy units where a=3, i.e., RSiO 1 / 2 and the D units are siloxy units where a=2, i.e., RSiO 2 / 2 where T units are siloxy units where a=1, i.e., RSiO 3 / 2 and the Q units are siloxy units where a=0, i.e., SiO 4 / 2 The polydiorganosiloxanes of component (a) are substantially linear, but may contain a proportion, although some branching may occur due to the presence of T units (as described above) within the molecule, so that the average value of a in structure (I) is about 2.

[0022] Typical examples of R groups on component (a) include primarily alkenyl, alkynyl, alkyl, and / or aryl groups, alternatively alkenyl, alkyl, and / or aryl groups, which may be in pendant positions (on D or T siloxy units) or terminal (on M siloxy units).

[0023] The silicon-bonded organic groups bonded to component (a), other than the at least two unsaturated groups per molecule selected from alkenyl or alkynyl groups, are typically selected from monovalent saturated hydrocarbon groups containing 1 to 10 carbon atoms and monovalent aromatic hydrocarbon groups typically containing 6 to 12 carbon atoms, and are unsubstituted or substituted with groups that do not interfere with the curing of the compositions of the present invention, such as halogen atoms. Preferred species of silicon-bonded organic groups are, for example, alkyl groups such as methyl, ethyl, and propyl, and aryl groups such as phenyl.

[0024] Component (a) may be selected from, for example, polydimethylsiloxanes, alkylmethylpolysiloxanes, alkylarylpolysiloxanes, or copolymers thereof containing alkenyl and / or alkynyl groups (reference to alkyl means an alkyl group having two or more carbons), and may have any suitable end groups, which may be, for example, trialkyl-terminated, alkenyldialkyl-terminated, alkynyldialkyl-terminated, or terminated with any other suitable combination of end groups, provided that each polymer contains at least two unsaturated groups selected from alkenyl and alkynyl groups per molecule. In one embodiment, the end groups of such polymers are free of silanol end groups.

[0025] Thus, component (a) may be, for example: Dialkylalkenyl-terminated polydimethylsiloxanes, such as dimethylvinyl-terminated polydimethylsiloxanes, dialkylalkenyl-terminated dimethylmethylphenylsiloxanes, such as dimethylvinyl-terminated dimethylmethylphenylsiloxanes, trialkyl-terminated dimethylmethylvinylpolysiloxanes, dialkylvinyl-terminated dimethylmethylvinylpolysiloxane copolymers, dialkylvinyl-terminated methylphenylpolysiloxanes, dialkylalkenyl-terminated methylvinylmethylphenylsiloxanes, dialkylalkenyl-terminated methylvinyldiphenylsiloxanes, dialkylalkenyl-terminated methylvinylmethylphenyldimethylsiloxanes, trimethyl-terminated methylvinylmethylphenylsiloxanes, trimethyl-terminated methylvinyldiphenylsiloxanes, or trimethyl-terminated methylvinylmethylphenyldimethylsiloxanes.

[0026] In these embodiments, at a temperature of 25° C., the generally substantially linear organopolysiloxane of component (a) is typically a flowable liquid. Generally, the substantially linear organopolysiloxane has a viscosity of 100 to 1,000,000 mPa·s, alternatively 100 to 100,000 mPa·s, at 25° C. Viscosity may be measured using either a Brookfield® rotational viscometer with spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa·s) or, for viscosities below 1000 mPa·s, a Brookfield® rotational viscometer with spindle LV-1 (designed for viscosities in the range of 15 to 20,000 mPa·s), adapting the shear rate according to the polymer viscosity.

[0027] Ingredient (b) Component (b) is an organosilicon compound having at least two, alternatively at least three, Si-H groups per molecule. Organosilicon compound (b) acts as a crosslinker to cure component (a) through the addition reaction of silicon-bonded hydrogen atoms with the unsaturated groups in component (a), catalyzed by component (d) described below. Typically, component (b) contains three or more silicon-bonded hydrogen atoms so that its hydrogen atoms can react sufficiently with the unsaturated groups in component (a) to form a network structure, thereby curing the composition. Alternatively, when component (a) has more than two unsaturated groups per molecule, alternatively alkenyl groups, some or all of component (b) may have two silicon-bonded hydrogen atoms per molecule.

[0028] Component (b) may be a siloxane, such as an organohydrogensiloxane, or a silane, such as a monosilane, disilane, trisilane, or polysilane, provided that each molecule has at least two, alternatively at least three, Si—H groups per molecule. In acyclic polysilanes and polysiloxanes, the silicon-bonded hydrogen atoms may be located at terminal, pendant, or both terminal and pendant positions. Cyclosilanes and cyclosiloxanes typically have 3 to 12 silicon atoms, alternatively 3 to 10 silicon atoms, alternatively 3 to 4 silicon atoms.

[0029] When component (b) is a siloxane, it may comprise an organohydrogensiloxane, which may be a disiloxane, trisiloxane, or polysiloxane. The organohydrogensiloxane may contain any combination of M, D, T, and / or Q siloxy units, so long as component (b) contains at least two silicon-bonded hydrogen atoms. These siloxy units may be combined in various ways to form cyclic, linear, branched, and / or resinous (three-dimensional network) structures. Component (b) may be monomeric, polymeric, oligomeric, linear, branched, cyclic, and / or resinous, depending on the selection of M, D, T, and / or Q units.

[0030] Examples of component (b) include: (i) trimethylsiloxy-terminated methylhydrogenpolysiloxane, (ii) trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane; (iii) dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymer; (iv) dimethylsiloxane-methylhydrogensiloxane cyclic copolymer; (v)(CH3)2HSiO 1 / 2 Units and SiO 4 / 2 a copolymer consisting of units, (vi)(CH3)3SiO 1 / 2 Units: (CH3)2HSiO1 / 2 units, and SiO 4 / 2 copolymers consisting of units, and (vii) (CH3)2HSiO above 1 / 2 Units and (R 2 Z) d (R 3 ) e SiO (4-d-e) / 2 Examples of copolymers include, but are not limited to, copolymers containing:

[0031] The viscosity of this component is not particularly limited, but the viscosity can typically be 0.001 to 50 Pa·s at 25°C using either a Brookfield® rotational viscometer with spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa·s) or, for viscosities below 1000 mPa·s, a Brookfield® rotational viscometer with spindle LV-1 (designed for viscosities in the range of 15 to 20,000 mPa·s), adapting the shear rate according to the polymer viscosity.

[0032] Component (b) is typically added in an amount such that the molar ratio of silicon-bonded hydrogen atoms in component (b) to the total unsaturated groups in the composition is 0.5:1 to 20:1, alternatively 0.5:1 to 5:1, alternatively 0.6:1 to 3:1. If this ratio is less than 0.5:1, a sufficiently cured composition will not be obtained. If this ratio exceeds 20:1, the hardness of the cured composition tends to increase when heated. The amount of each group described in the above ratio, for example, the silicon-bonded hydrogen (Si—H) content of organohydrogenpolysiloxane (b), can be determined, if desired, using quantitative infrared analysis according to ASTM E168.

[0033] Typically, component (b) is present in the composition in an amount of 0.5 to 10 weight percent of the total composition, this amount being determined according to the required molar ratio of the total number of silicon-bonded hydrogen atoms in component (b) to the total number of all alkenyl and alkynyl groups in component (a).

[0034] Ingredient (c) Component (c) is at least one silica reinforcing filler or one or more non-reinforcing fillers selected from quartz, diatomaceous earth, and calcium carbonate, or a mixture of both. Alternatively, component (c) is one or more finely divided silica reinforcing fillers and one or more non-reinforcing fillers selected from quartz, diatomaceous earth, and calcium carbonate; alternatively, component (c) is one or more finely divided silica reinforcing fillers and quartz. In each of the above alternatives, each filler present has been hydrophobized.

[0035] When component (c) includes one or more reinforcing fillers, the reinforcing fillers may be exemplified by finely divided fumed silica, colloidal silica and / or finely divided precipitated silica.

[0036] Precipitated silica, fumed silica and / or colloidal silica are typically at least 50 ml 2 / g (BET method according to ISO9277:2010), alternatively 50-450m 2 / g (BET method according to ISO 9277:2010), alternatively between 50 and 300 m 2 These silicas are particularly preferred and typically used due to their relatively high surface area, with a surface area of ​​0.15 to 0.25g / g (BET method according to ISO 9277:2010). All of these types of silica are commercially available.

[0037] The silica reinforcing filler(s) of component (c) are hydrophilic in nature and are treated with a treating agent to render them hydrophobic. These surface-modified reinforcing fillers of component (c) do not agglomerate and can be homogeneously incorporated into the polydiorganosiloxane polymer (a) described below, because the surface treatment allows the fillers to be easily wetted by the polydiorganosiloxane polymer (a).

[0038] The reinforcing filler(s) may be surface treated with any suitable low molecular weight organosilicon compound disclosed in the art that is applicable to prevent creping of the LSR composition during processing. For example, organosilanes, polydiorganosiloxanes, or organosilazanes such as hexaalkyldisilazanes and short-chain siloxanediols. Specific examples include, but are not limited to, silanol-terminated trifluoropropylmethylsiloxane, silanol-terminated vinylmethyl (ViMe) siloxane, silanol-terminated methylphenyl (methylphenyl)siloxane, and the like. hydroxyldimethyl-terminated polydiorganosiloxanes containing an average of 2 to 20 diorganosiloxane repeating units in each molecule, hydroxyldimethyl-terminated phenylmethylsiloxanes, hexaorganodisiloxanes such as hexamethyldisiloxane, divinyltetramethyldisiloxanes; hexaorganodisilazanes such as hexamethyldisilazane (hexamethyldisilazane, HMDZ), divinyltetramethyldisilazane, and tetramethyldi(trifluoropropyl)disilazane; hydroxyldimethyl-terminated polydimethylmethylvinylsiloxanes, octamethylcyclotetrasiloxanes, and silanes including, but not limited to, methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, chlorotrimethylsilane, dichlorodimethylsilane, and trichloromethylsilane.

[0039] In one embodiment, the treating agent may be selected from silanol-terminated vinylmethyl (ViMe) siloxanes, liquid hydroxyldimethyl-terminated polydiorganosiloxanes containing an average of 2 to 20 diorganosiloxane repeating units per molecule, hexaorganodisiloxanes such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane; and hydroxyldimethyl-terminated polydimethylmethylvinylsiloxanes, octamethylcyclotetrasiloxane, and methyltriethoxysilane, dimethyldiethoxysilane, and / or vinyltriethoxysilane. A small amount of water may be added with the silica treating agent as a processing aid.

[0040] The surface treatment of the untreated reinforcing filler of component (c) can be carried out either prior to its introduction into the composition or in situ (i.e., by blending the other ingredients of the compositions herein together at room temperature or above until the filler is fully treated, in the presence of at least a portion of these ingredients. Typically, the untreated reinforcing filler (c) is treated with a treating agent in situ in the presence of the polydiorganosiloxane polymer (a), thereby preparing a silicone rubber base material that can then be mixed with the other ingredients.

[0041] As indicated above, component (c) may also alternatively or additionally contain one or more non-reinforcing fillers selected from quartz, diatomaceous earth, and calcium carbonate, each of which, if present, is also hydrophobically treated with a treating agent such as those described above for the reinforcing fillers.

[0042] Component (c) is optionally present in an amount of up to 40% by weight of the composition, alternatively from 1.0 to 40% by weight of the composition, alternatively from 5.0 to 35% by weight of the composition, alternatively from 10.0 to 35% by weight of the composition.

[0043] Ingredient (d) Component (d) of the curable silicone rubber composition is a platinum group metal-based hydrosilylation cure catalyst. These are typically selected from catalysts of platinum group metals (platinum, ruthenium, osmium, rhodium, iridium, and palladium) or compounds of one or more of these metals. For example, catalyst (d) can be a platinum group metal, a platinum group metal deposited on a support, such as activated carbon, a metal oxide such as aluminum oxide or silicon dioxide, silica gel, or powdered charcoal, or a platinum group metal compound or complex. Preferably, the platinum group metal contained in the catalyst is platinum or rhodium due to the high activity level of these catalysts in hydrosilylation reactions, with platinum being most preferred. In the hydrosilylation (or addition) reaction, hydrosilylation catalysts such as component (d) herein catalyze the reaction between unsaturated groups, usually alkenyl groups, such as vinyl, and Si-H groups.

[0044] Examples of preferred hydrosilylation catalysts (d) are platinum-based catalysts such as platinum black, platinum oxide (Adams' catalyst), platinum on various solid supports, chloroplatinic acid such as hexachloroplatinic acid (Pt oxidation state IV) (Speier's catalyst), chloroplatinic acid in solution in an alcohol such as isooctanol or amyl alcohol (Lamoreaux's catalyst), and complexes of chloroplatinic acid with ethylenically unsaturated compounds such as olefins and organosiloxanes containing ethylenically unsaturated silicon-bonded hydrocarbon groups, such as tetra-vinyl-tetramethylcyclotetrasiloxane-platinum complex (Ashby's catalyst). Usable soluble platinum compounds include, for example, platinum-olefin complexes of the formula (PtCl2(olefin)2 and H(PtCl3.olefin), in which the use of alkenes having 2 to 8 carbon atoms, such as ethylene, propylene, isomers of butene and isomers of octene, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene and cycloheptene, is preferred. Other soluble platinum catalysts are, for example, platinum-cyclopropane complexes of the formula (PtCl2C3H6)2, The reaction products of hexachloroplatinic acid with alcohols, ethers, and aldehydes, or mixtures thereof, or the reaction products of hexachloroplatinic acid and / or its conversion products with vinyl-containing siloxanes, such as methylvinylcyclotetrasiloxane, in the presence of sodium bicarbonate in an ethanolic solution. Platinum catalysts with phosphorus, sulfur, and amine ligands, for example (Ph3P)2PtCl2, and platinum complexes with vinyl siloxanes, such as sym-divinyltetramethyldisiloxane, can also be used.

[0045] Therefore, specific examples of suitable platinum-based catalysts include: (i) Complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups, as described in U.S. Pat. No. 3,419,593; (d) chloroplatinic acid in either the hexahydrate or anhydrous form; (iii) platinum-containing catalysts obtained by a process comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound such as divinyltetramethyldisiloxane; (iv) alkene-platinum-silyl complexes described in U.S. Pat. No. 6,605,734, such as (COD)Pt(SiMeCl) (where “COD” is 1,5-cyclooctadiene), and / or (v) Karstedt's catalyst, which is a platinum divinyltetramethyldisiloxane complex, typically containing about 1% by weight of platinum in a vinylsiloxane polymer. While organic solvents such as toluene have historically been used as alternatives, the use of vinylsiloxane polymers is by far the preferred choice. These are described in U.S. Pat. Nos. 3,715,334 and 3,814,730. In a preferred embodiment, component (d) can be selected from platinum coordination compounds. In one embodiment, hexachloroplatinic acid and its conversion products with vinyl-containing siloxanes, Karstedt's catalyst, and Speier's catalyst are preferred.

[0046] The catalyst may be added as a single species or as a mixture of two or more different species. Typically, depending on the form / concentration in which the catalyst is provided, the amount of platinum group metal present, alternatively the amount of platinum metal present, will be in the range of 0.1 to 1.5 wt. % of the composition, alternatively 0.1 to 1.0 wt. %, alternatively 0.1 to 0.5 wt. % of the composition.

[0047] Components (e) and (g) are required, but component (f) is optional.

[0048] Ingredient (e) Component (e) is a tetraalkyl titanate. Each alkyl group in the tetraalkyl titanate (e) can be the same or different, but is typically the same and is selected from alkyl groups having up to 20 carbon atoms. Useful tetraalkyl titanates include tetraisopropyl titanate, tetrabutyl titanate, and tetraoctyl titanate. The tetraalkyl titanate of component (e) is typically used in an amount of 0.01 to 0.15% by weight of the composition, alternatively in an amount of 0.01 to 0.1% by weight of the composition, alternatively in an amount of 0.02 to 0.075% by weight of the composition.

[0049] Component (f) Optionally, the composition may include component (f), an alkyl polysilicate. The alkyl polysilicate may be a partially hydrolyzed tetraalkyl silicate, where the alkyl groups may be the same or different and may contain up to 6 carbon atoms per group, alternatively up to 4 carbon atoms per group. Examples of component (f), when present, include, but are not limited to, ethyl polysilicate and butyl polysilicate. The alkyl polysilicate (f) may be present in an amount of up to 2.5% by weight of the composition, alternatively in an amount of 0 (zero) to 2.0% by weight of the composition. When present, the alkyl polysilicate (f) may be present in an amount of 0.5 to 2% by weight of the composition.

[0050] Ingredients (g) Suitable (meth)acrylate compounds for component (g) are also provided, such as alkyl, alkenyl, and aryl esters of acrylic or methacrylic acid, i.e., acrylates or methacrylates, referred to herein as (meth)acrylates. Each alkyl group, if present, contains 1 to 10 carbon atoms per alkyl group, alternatively 1 to 6 carbon atoms per alkyl group. Specific examples include, but are not limited to, methyl, ethyl, butyl, and octyl. Each alkenyl group typically contains 2 to 10 carbon atoms per alkenyl group, alternatively 2 to 6 carbon atoms per alkenyl group. Examples include vinyl, allyl, and / or butenyl groups. The aryl group typically contains 6 to 10 carbon atoms in the ester. The aryl group may be phenyl or naphthyl. The (meth)acrylate compound may be selected from alkyl (meth)acrylates such as, but not limited to, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, ureido (meth)acrylate, 2-ethylhexyl (meth)acrylate, 2-propylheptyl (meth)acrylate, and decyl (meth)acrylate; alkenyl (meth)acrylates include vinyl (meth)acrylate, allyl (meth)acrylate, and butenyl (meth)acrylate; aryl (meth)acrylates include phenyl (meth)acrylate, naphthyl (meth)acrylate, and tolyl (meth)acrylate; aralkyl (meth)acrylates include phenylethyl (meth)acrylate; cycloalkyl (meth)acrylates include cyclohexyl (meth)acrylate; preferably, the (meth)acrylate compound is an alkyl (meth)acrylate. The (meth)acrylate compound is typically present in an amount from 0.1 to 2.5% by weight of the composition, alternatively from 0.1 to 2.0% by weight of the composition, alternatively from 0.5 to 2.0% by weight.

[0051] Ingredients (h) Component (h) of the curable silicone rubber composition is a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule, (i)(R 10 ) z (R 11 ) 3-z Si-(W)-Si(R 11 ) 3-z (R 10 ) z [In the formula, each R 11 are the same or different and are alkoxy groups having 1 to 6 carbon atoms; 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, z is 0 or 1, and W is a linear or branched alkylene group having 1 to 12 carbon atoms; or (ii) 1,3,5-tris[3-((R 10 ) z (R 11 ) 3-z Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [In the formula, R 11 , R 10 and z are as defined above, and D is an alkylene group having 1 to 6 carbon atoms.

[0052] In one alternative, component (h) of the curable silicone rubber composition may be a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule of the formula: (i)(R 10 ) z (R 11 ) 3-z Si-(W)-Si(R 11 ) 3-z (R 10 ) z In the formula, each R 11are the same or different and are alkoxy groups having 1 to 6 carbons, alternatively 1 to 4 carbons, alternatively selected from methoxy, ethoxy, or propoxy, alternatively methoxy; each R 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, alternatively R 11 or an alkyl group having 1 to 4 carbon atoms, alternatively R 11 or a methyl, ethyl, or propyl group; the subscript z is 0 or 1, preferably the subscript z is 0. W is a straight or branched chain alkylene having 1 to 12 carbons, alternatively a straight or branched chain alkylene having 1 to 6 carbons, alternatively a straight or branched chain alkylene having 1 to 4 carbons, alternatively W is straight chain. Thus, in one embodiment, when z is 0, component (h)(i) has the formula: (R 11 )3-Si-(W)-Si(R 11 )3 Furthermore, in another embodiment, each R 11 is a methoxy group or an ethoxy group, then (h)(i) has the formula: (MeO)3Si-(W)-Si(OMe)3 or (EtO)3Si-(W)-Si(OEt)3 wherein Me is methyl and Et is ethyl, in which case component (h)(i) may be, for example, bis(trimethoxysilyl)ethane, bis(trimethoxysilyl)propane, bis(trimethoxysilyl)butane, bis(trimethoxysilyl)pentane, bis(trimethoxysilyl)hexane, or bis(triethoxysilyl)ethane, bis(triethoxysilyl)propane, bis(triethoxysilyl)butane, bis(triethoxysilyl)pentane, or bis(triethoxysilyl)hexane, respectively.

[0053] Alternatively, component (h) of the curable silicone rubber composition may be a compound of the following formula: at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule: (ii) 1,3,5-tris[3-((R 10 ) z (R 11 ) 3-z Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione In the formula, each R 11 are the same or different and are alkoxy groups having 1 to 6 carbons, alternatively 1 to 4 carbons, alternatively selected from methoxy, ethoxy, or propoxy, alternatively methoxy; each R 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, alternatively R 11 or an alkyl group having 1 to 4 carbon atoms, alternatively R 11 or a methyl, ethyl, or propyl group; the subscript z is 0 or 1, preferably the subscript z is 0. D is a straight or branched chain alkylene having 1 to 12 carbons, alternatively a straight or branched chain alkylene having 1 to 6 carbons, alternatively a straight or branched chain alkylene having 1 to 4 carbons, alternatively D is straight chain. Thus, in one embodiment, when z is 0, component (h)(ii) has the formula: 1,3,5-Tris[3-((R 11 )3Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione Furthermore, in an alternative embodiment, each R 11 is a methoxy group, then (h)(ii) has the formula: 1,3,5-Tris[3-((MeO)3Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione The content of component (h) in the composition is about 0.2 to about 5 weight percent of the composition, alternatively 0.2 to 2.5 weight percent of the composition, alternatively 0.2 to 1.5 weight percent of the composition. An important aspect is that the incorporation of component (h) enables the cured silicone rubber to adhere to aluminum substrates without a significant increase in compression set.

[0054] Optional Additive(s) The composition may optionally further comprise additional ingredients, hereinafter referred to as "optional additives," that provide benefits to the composition or the material to be subsequently cured and that do not interfere with the curing of the curable silicone rubber composition.

[0055] Examples of additional components include, but are not limited to, cure inhibitors, surfactants, colorants including dyes and pigments, antioxidants, carrier media, heat stabilizers, flame retardants, metal deactivators, flow control agents, lubricants, oil-bleed agents, adhesion promoters, stabilizers such as heat stabilizers, conductivity stabilizers, foam stabilizers and / or UV stabilizers, dispersants, slip agents, toughening agents, antioxidants, and thixotropic agents.

[0056] One or more of the additives can be present in any suitable weight percent (wt%) of the composition, such as about 0.1% to about 15%, about 0.5% to about 5%, or about 0.1% or less, about 1%, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or about 15% or more by weight of the composition. In the case of pigments and / or colorants, the amount present may be as high as 20% by weight of the composition, if deemed necessary. One of ordinary skill in the art can readily determine the appropriate amount of additive, depending, for example, on the type of additive and the desired result. Certain optional additives are described in more detail below.

[0057] The compositions described herein may further comprise a hydrosilylation reaction inhibitor to inhibit the curing of the composition. The hydrosilylation reaction inhibitor is optionally used to prevent or delay the hydrosilylation reaction curing process, especially during storage. Optional hydrosilylation reaction inhibitors for platinum-based catalysts are well known in the art and include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, fumarates, ethylenically or aromatic unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, unsaturated hydrocarbon monoesters and diesters, conjugated ene-ynes such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne, hydroperoxides, nitriles, and diaziridines. Alkenyl-substituted siloxanes such as those described in U.S. Pat. No. 3,989,667 can be used, of which cyclic methylvinylsiloxanes such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane are preferred.

[0058] One class of known hydrosilylation reaction inhibitors includes the acetylenic compounds disclosed in U.S. Patent No. 3,445,420. Acetylenic alcohols, such as 2-methyl-3-butyn-2-ol, constitute a preferred class of inhibitors, which suppress the activity of platinum-containing catalysts at 25° C. Typically, compositions containing these inhibitors must be heated to temperatures above 70° C. in order to cure at a practical rate.

[0059] Examples of acetylene alcohols and their derivatives include 3-methyl-1-butyn-3-ol, 1-ethynyl-1-cyclohexanol (ETCH), 2-methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-butyn-2-ol, propargyl alcohol, 1-phenyl-2-propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-phenyl-1-butyn-3-ol, 1-ethynylcyclopentanol, 3-methyl-1-penten-4-yn-3-ol, and mixtures thereof.Derivatives of acetylene alcohols may include these compounds that have at least one silicon atom.

[0060] In some cases, inhibitor concentrations as low as 1 mole of inhibitor per mole of catalyst metal, when present, will provide satisfactory storage stability and cure speed. In other cases, inhibitor concentrations of up to 500 moles of inhibitor per mole of catalyst metal are required. The optimum concentration for a given inhibitor in a given composition is readily determined by routine experimentation. When present in the composition, inhibitors are typically present in amounts of 0.0125 to 10 weight percent of the composition, depending on the concentration and form in which the selected inhibitor is provided / commercially available.

[0061] The compositions described herein may further comprise one or more pigments and / or colorants that may be added as needed. The pigments and / or colorants may be colored, white, black, metallic effect, and luminescent, such as fluorescent and phosphorescent.

[0062] Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, lithopone, zirconium oxide, and antimony oxide.

[0063] Suitable non-white inorganic pigments and / or colorants include, but are not limited to, goethite, lepidocrocite, hematite, maghemite, and magnetite; iron oxide pigments such as black iron oxide, yellow iron oxide, brown iron oxide, and red iron oxide; blue iron pigments; chromium oxide pigments; cadmium pigments such as cadmium yellow, cadmium red, cadmium cinnabar; bismuth pigments such as bismuth vanadate and bismuth vanadate molybdate; mixed metal oxide pigments such as cobalt titanate green; chromate and molybdate pigments such as chrome yellow, molybdate red, and molybdate orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanate; lead chromium; carbon black; lamp black; and metallic effect pigments such as aluminum, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass.

[0064] Suitable organic non-white pigments and / or colorants include phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green, monoarylide yellow, diarylide yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments such as quinacridone magenta and quinacridone violet, organic reds including metallized and non-metallized azo reds and other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensed pigments, isoindolinone and isoindoline pigments, polycyclic pigments, perylene and perinone pigments, thioindigo pigments, anthrapyrimidone pigments, flavanthrone pigments, anthanthrone pigments, dioxazine pigments, triarylcarbonium pigments, quinophthalone pigments, and diketopyrrolopyrrole pigments.

[0065] Typically, the pigment and / or colorant, when particulate, has an average particle size in the range of from 10 nm to 50 μm, preferably in the range of from 40 nm to 2 μm. When present, the pigment and / or colorant is present in an amount of from 2% by weight of the composition, alternatively from 3% by weight, alternatively from 5% by weight to 20% by weight of the composition, alternatively from 15% by weight, alternatively from 10% by weight.

[0066] Another optional additive herein is a metal deactivator, i.e., a fuel and oil additive used to stabilize the fluid by deactivating (usually by sequestering) metal ions introduced by oxidation processes with the metal parts of the system, primarily through the action of naturally occurring acids in the fuel and acids generated in the lubricant, e.g., dodecanedioic acid, bis[2-(2-hydroxybenzoyl)hydrazide].

[0067] The composition may also include one or more oil-resistant agents, such as magnesium hydroxide (Mg(OH)2).

[0068] The curable silicone rubber compositions described herein are typically stored in two parts to avoid premature curing. The two parts are generally referred to as Part A and Part B. Two-component compositions are prepared so that components (b) the crosslinker and (d) the catalyst are not stored together in the same part to avoid premature curing. For example, Part A may contain components (a) the polymer, (c) the filler, and (d) the catalyst, while Part B contains at least components (a) the polymer and (b) the crosslinker and usually (c) the filler, with Part A being free of component (b) the crosslinker and Part B being free of component (d) the catalyst. Typically, component (e) may be present in Part A, and components (f), (g), and (h) are added to the Part B composition.

[0069] Preferably, if present, the cure inhibitor is present in Part A along with component (d). Other optional components of the composition can be present in either or both Parts A and B, or, if desired, can be introduced into one or more additional parts separate from the two parts (thereby making the system a three or more part system). The two-component composition can be designed to be mixed together in any suitable ratio depending on the content and concentration of the components present in each part; for example, the two-component composition can be mixed in a weight ratio of Part A:Part B of 5:1 to 1:5.

[0070] Any suitable method can be utilized to manufacture a cured-in-place gasket (CIPG) using the compositions described herein, for example, a method can include, for example, the following steps: (i) mixing a part A composition with a part B composition in a predetermined weight ratio; (ii) transporting the mixture prepared in step (i) to a suitable applicator; (iii) dispensing the resulting mixture from the applicator onto a substrate surface; (iv) allowing the mixture to cure to provide a silicone cure-in-place gasket.

[0071] Prior to step (i) of the above process, the raw ingredients of the Part A composition are blended together and separately the raw ingredients of the Part B composition are blended together to form the respective Part A and Part B compositions.

[0072] Typically, the Part A and Part B compositions are stored for a period of time before use. In step (i), the Part A composition and the Part B composition are mixed to form a curable mixture of the silicone rubber composition. Any suitable mixer may be used, for example, a static mixer or a stirred tank suitable for thoroughly mixing the respective blend compositions. Optionally, the mixing vessel can be temperature-controlled so that the mixed Part A and Part B compositions can be maintained within a desired temperature range.

[0073] In step (ii), the composition produced in step (i) is transported to a suitable applicator. This may be via a pump. Considering that the composition is used to produce a cured-in-place gasket (CIPG), the applicator is preferably a pre-programmed or programmable robotic applicator that can be used to apply the composition to a target substrate surface, which may be flat but likely has grooves intended to receive the composition. The composition should be applied in an amount that minimizes waste while providing a fully functional gasket. Typically, the applicator is programmed to apply an optimized amount of composition at a predetermined dispensing flow rate so that the gasket is formed as needed and in the required location, and then cured in place. Because the compositions herein are hydrosilylation / addition cured, the curing step is typically performed at elevated temperatures; therefore, in a continuous process, target substrates can be placed in predetermined locations on a conveyor belt that transports each substrate to a location where the composition is intended to be applied using a robotic applicator. The applicator applies the composition in a preprogrammed pattern, and the substrate is then transported on a conveyor belt through a heated zone of the conveyor oven for a desired time, such as a few minutes, e.g., 2 to 20 minutes, alternatively 5 to 20 minutes, alternatively 5 to 15 minutes, at a desired temperature, e.g., 120°C to 180°C, alternatively 130°C to 160°C, alternatively 145°C to 160°C. If desired, the substrate may be passed through a preheated oven before applying the composition to produce the CIPG.

[0074] The compositions described herein are cured at elevated temperatures. After curing, the gasket may optionally be subjected to a post-cure step. Post-cure can be used to stabilize the performance of the cured gasket for a short period of time, e.g., 30 minutes to 3 hours, e.g., 1 hour.

[0075] After curing, and optionally after post-curing, adequate flexibility, compression set, and potentially high gasket height-to-width ratios are required. Property tailoring in the uncured and cured states is a function of the reactants' relative stoichiometry.

[0076] The balance of properties will vary depending on the specific requirements of a given application of the form-in-place gasket, and custom formulation will be a significant challenge to satisfy many applications for the gasket formulations described herein.

[0077] For the present disclosure, the substrate to which the beads of the curable silicone rubber composition described herein are applied to form the uncured CIPG is preferably made at least in part from aluminum, or alternatively is an aluminum substrate, prior to curing, which can enable an unexpected benefit identified when using the compositions herein to make CIPGs: improved adhesion to aluminum while maintaining a low compression set of 40% or less, alternatively 39% or less, after testing at 177°C for 22 hours according to ASTM D395 Method B.

[0078] For optimal performance, CIPGs preferably require a balance of properties. Uncured CIPG compositions, such as those herein, are liquids with sufficiently low viscosity to dispense easily through an applicator (and avoid clogging within the applicator), yet non-slumping to maintain the intended gasket shape and dimensions after dispensing and until cured in place. Thus, when initially formed, each blend / composition of Part A, Part B, and their resulting combinations can have a wide viscosity range, depending on the components used. In various embodiments, the compositions have a viscosity of about 1,000 to about 100,000 mPa·s, alternatively about 1,000 to about 50,000 mPa·s, alternatively about 1,000 to about 25,000 mPa·s, alternatively about 1,000 to about 10,000 mPa·s, alternatively about 1,000 to about 7,500 mPa·s, or alternatively about 2,500 to about 5,000 mPa·s. Viscosity may be determined using any suitable method understood in the art, for example, using a Brookfield® rotational viscometer with spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa·s) or, for viscosities below 1000 mPa·s, with spindle LV-1 (designed for viscosities in the range of 15 to 20,000 mPa·s), adapting the shear rate according to the polymer viscosity.

[0079] The CIPGs, compositions, and methods herein are useful in applications such as acting as barriers to prevent the absorption or penetration of air, dust, noise, liquids, gaseous substances, or dirt. Gaskets are ideal for sound damping, vibration damping, shock absorption, moisture protection, chemical protection, and air sealing. Examples of suitable automotive applications include automotive gasket applications, such as gaskets for electric vehicle (EV) battery packs, EV batteries, and control units in EVs, such as housing seals and coolant area seals in motor control unit (MCU) devices, lamp housings, fuse boxes, air filters, oil pan gaskets, oil seal case gaskets, oil screen gaskets, timing belt cover upper gaskets, and timing rocker cover lower gaskets; and gaskets for electrical equipment, such as waterproof connectors, air conditioners, lighting devices, electronic components, and housings, preferably control cabinets, lamps, drums (packaging), or filter housings, that are attached to a substrate in situ by foaming, as described herein. Other applications include external waterproofing applications.

[0080] The following examples illustrating compositions, CIPGs, and methods are intended to illustrate, but not limit, the present disclosure herein. [Example]

[0081] Compositions were produced utilizing different types and amounts of ingredients, which are described in detail below. All amounts are in weight percent unless otherwise specified. As noted above, all viscosities are measured at 25°C. The viscosity of individual raw ingredients can be determined by any suitable method, for example, using a Brookfield® rotational viscometer with spindle LV-4 (designed for viscosities in the range of 1,000 to 2,000,000 mPa·s) or, for viscosities below 1000 mPa·s, with spindle LV-1 (designed for viscosities in the range of 15 to 20,000 mPa·s), adapting the shear rate according to the polymer viscosity. The alkenyl and / or alkynyl content of the polymer and the silicon-bonded hydrogen (Si—H) content and / or silanol content of the raw ingredients were determined using quantitative infrared analysis according to ASTM E168.

[0082] In the following Examples and Comparative Examples, two different masterbatches (MB) were prepared for the purpose of treating fillers (fumed silica and quartz) in situ, the compositions of which are shown in Table 1 below.

[0083] [Table 1]

[0084] The BET value was measured according to ISO 9277.

[0085] Methylvinyldiol is a dimethylhydroxy-terminated polydimethylmethylvinylsiloxane having a viscosity of about 30 mPa·s at 25°C and a vinyl content of about 12.0 wt%.

[0086] Mixtures of examples and comparative examples were prepared. Considering that all examples were hydrosilylation-curable compositions, the compositions were prepared in two parts. As noted above, the Part A composition contains a catalyst, and the Part B composition contains a crosslinker. The Part A compositions for Examples 1-10 are shown in Table 2a, where it will be seen that the Part A compositions for Examples 1-8 are the same.

[0087] [Table 2]

[0088] The aluminum acetonate is supplied as a solution in toluene.

[0089] The part B compositions of Examples 1-5 are shown in Table 2b, and the part B compositions of Examples 6-10 are shown in Table 2c.

[0090] [Table 3]

[0091] In the above table, The Si-H crosslinker is a Si-H dimethyl-terminated resinous Si-H polysiloxane having a viscosity of 25 mPa·s at 25°C and a silicon-bonded hydrogen content of approximately 9,600 ppm; Component (h)1 (Comp. (h)1) is bis(trimethoxysilyl)hexane, Component (h)2 (Comp. (h)2) is 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; Adhesion promoter 1 was glycidoxypropyltrimethoxysilane.

[0092] [Table 4]

[0093] The above component (h)3 is bis(trimethoxysilyl)ethane. For laboratory testing, the Part A and Part B compositions of each Example and Comparative Example were independently mixed to homogeneity, and then the respective Parts A and B were combined in a 1:1 weight ratio. The combined mixture was also homogeneously mixed for 12 seconds and degassed using a speed mixer. The walls of the mixer were then scraped down, and the mixture was mixed again for an additional 12 seconds.

[0094] Samples of the resulting compositions were tested for slump / flow, measured (mm) according to ASTM D2202. A slump jig was filled with the mixture resulting from 2 x 12 second cycles of mixing Part A with Part B. The excess was removed and the fixture was moved vertically. Slump / flow readings of the compositions were taken after 10 minutes and are shown in Tables 3a and 3b of the physical properties below.

[0095] The resulting degassed mixture was introduced into a mold cavity and cured by press-curing at 150°C for 5 minutes to produce suitable test sheets 2.0 mm thick for preparing specimens for hardness (Shore A), tensile strength, and elongation at break testing. When preparing specimens for compression set testing, specimens (small disks) 12.0-13.0 mm thick were press-cured at 150°C for 10 minutes. Regardless of the test performed, all specimens were stored at room temperature for 16-24 hours before physical property testing.

[0096] The different examples were then subjected to physical property testing using the following methodology.

[0097] Shore A hardness Shore A hardness was measured according to ASTM D2240-97.

[0098] Tensile strength and elongation at break Tensile strength and elongation at break results were obtained per ASTM D412-98A.

[0099] Compression set (%) Compression set results were obtained according to ASTM D395 Method B after 22 hours at 177°C.

[0100] Lap shear adhesive strength Lap shear adhesive strength (MPa) for both aluminum / aluminum (AL / AL) and polyamide (nylon) 66 / polyamide 66 (PA66 / PA66) was measured in accordance with ASTM D816-82 (Reapproved 2001) using Type I lap specimens from Figure 1 therein. The aluminum panels in the lap shear tests were ALCLAD 2024T3 panels manufactured by Q-Lab Corporation and were 2.54 cm wide. The PA66 panels in the examples were PA66 GF30 type manufactured by Shanghai Qiyao Chemical Co. Ltd. and were also 2.54 cm wide.

[0101] Each aluminum and polyamide 66 substrate panel was first cleaned with isopropyl alcohol (IPA) solvent and then allowed to dry at room temperature for at least 30 minutes. Testing was performed by first applying the respective uncured composition between the top and bottom panels, with a 1 cm overlap. The resulting test specimens were then allowed to stand at room temperature for 10 minutes, then cured in an oven at 150°C for 15 minutes, and finally cooled for 24 hours before testing. Results for Examples 1-5 are shown in Table 3a, and results for Examples 6-10 are shown in Table 3b.

[0102] [Table 5]

[0103] [Table 6]

[0104] It was found that all Examples 1-11 had compression set values ​​less than 40; in fact, all except Example 11 had compression set values ​​less than 35. It is particularly noteworthy, however, that not only did they have such excellent compression set values, but they also had excellent lap shear results of over 2.25 MPa on the challenging substrate aluminum. In Example 11, both compression set and lap shear results were acceptable, but the absence of quartz appears to be detrimental to performance. However, it can be seen that even in the absence of quartz, the compression set was still less than 40% when component (h)1 was present. While both compression set and lap shear results were acceptable, the absence of quartz produced poorer results. This demonstrates that the addition of component (h)1 in addition to a standard adhesion promoter provides excellent compression set without the known problem of compression set being compromised by increasing the presence of adhesion promoter to enhance the level of adhesion to aluminum. It can also be seen that the compositions used were effectively non-slumpable, and all maintained excellent physical properties after curing.

[0105] A series of comparative examples (C.1 to C.6) were also carried out using exactly the same methodology. The compositions used are shown in Table 4a (Part A composition) and Table 4b (Part B composition).

[0106] [Table 7]

[0107] In the above, Zirconium(IV) AcAc is a masterbatch of 50 wt. % zirconium(IV) acetylacetonate in a vinyldimethyl-terminated polydimethylsiloxane polymer having a viscosity of about 450 mPa·s.

[0108] [Table 8]

[0109] In Table 4b above Adhesion promoter 2 is the reaction product of glycidoxypropyltrimethoxysilane and dimethylhydroxy terminated dimethylmethylvinylsiloxane.

[0110] Adhesion promoter 3 is bis(trimethoxysilylpropyl)amine.

[0111] Similar tests were performed using the same test methods and the results for the comparative examples are shown below in Table 5. However, results are only provided for C.1-C.5 because C.6 did not cure.

[0112] [Table 9]

[0113] For aluminum substrates, Comparative Example C.1 provides excellent compression set, however, the results of lap shear between aluminum substrates are found to be undesirable and are found to be poor.

[0114] Comparative Example C.2 produces undesirable slump / flow (mm) results, but C.2 also exhibits poor lap shear results for aluminum substrates. (Without wishing to be bound by current theory, we believe the poor slump / flow results are due to the fact that quartz non-reinforcing filler was present in the C.2 composition but was untreated. Therefore, if quartz is present in the composition, it appears that it needs to be hydrophobized. Comparative Examples 3 and 4 contain increased levels of standard adhesion promoters and, as a result, show improved adhesion in the aluminum lap shear test. However, they produce poor compression set results, unlike the compositions of Examples 1-11, which all contain component (h) in the composition. We also found that by replacing component (h) with Adhesion Promoter 3, the presence of amine groups in Adhesion Promoter 3 appears to be the cause of C.6 not curing.

[0115] Thus, while the comparative examples were found to result in products with either good lap shear adhesion to aluminum or good compression set, but not both, it has been discovered herein that the use of component (h) described herein unexpectedly overcomes this problem, providing both good compression set, i.e., less than 40%, while maintaining good adhesion to aluminum substrates, as evidenced by the lap shear results. This means that the enclosed composition is suitable for applications involving the need for aluminum substrate adhesion along with good compression set. The present specification includes the following aspects. Section 1. 1. A curable silicone rubber composition comprising the following components: a) a polydiorganosiloxane having per molecule at least two unsaturated groups selected from alkenyl or alkynyl groups; b) an organosilicon compound having at least two, alternatively at least three, Si—H groups per molecule; c) at least one silica reinforcing filler or one or more non-reinforcing fillers selected from quartz, diatomaceous earth and calcium carbonate, or a mixture of both, wherein each filler present has been hydrophobized; d) a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof; e) a tetraalkyl titanate, wherein each alkyl group may be the same or different and has 1 to 20 carbon atoms, and wherein the tetraalkyl titanate is present in an amount of 0.01 to 0.15 weight percent of the composition; f) an alkyl polysilicate, wherein the alkyl groups may be the same or different and may contain up to 6 carbon atoms per group, present in an amount of 0 to 2.5% by weight of the composition; g) a suitable (meth)acrylate compound present in an amount of 0.1 to 2.5% by weight of the composition; h) a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule, (i)(R 10 ) z (R 11 ) 3-z Si-(W)-Si(R 11 ) 3-z (R 10 ) z [In the formula, each R 11 are the same or different and are alkoxy groups having 1 to 6 carbon atoms; 10 are the same or different, and R 11 or an alkyl group having 1 to 6 carbon atoms, z is 0 or 1, and W is a linear or branched alkylene group having 1 to 12 carbon atoms; or (ii) 1,3,5-tris[3-((R 10 ) z (R 11 ) 3-z Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [In the formula, R 11 , R 10 and z is as defined above, and D is an alkylene group having 1 to 6 carbon atoms. Section 2. Item 2. The curable silicone rubber composition according to Item 1, wherein component (h) is selected from bis(trimethoxysilyl)ethane, bis(trimethoxysilyl)propane, bis(trimethoxysilyl)butane, bis(trimethoxysilyl)pentane, bis(trimethoxysilyl)hexane, bis(triethoxysilyl)ethane, bis(triethoxysilyl)propane, bis(triethoxysilyl)butane, bis(triethoxysilyl)pentane, bis(triethoxysilyl)hexane, and / or 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6-(1H,3H,5H)trione. Section 3. Item 3. The curable silicone rubber composition according to item 1 or 2, wherein the composition further comprises one or more cure inhibitors, metal deactivators, and / or oil-resistant agents. Section 4. Item 4. The curable silicone rubber composition according to Item 3, wherein the metal deactivator is dodecanedioic acid, bis[2-(2-hydroxybenzoyl)hydrazide], and / or the oil-resistant agent is magnesium hydroxide. Section 5. 5. The curable silicone rubber composition according to any one of items 1 to 4, wherein component c) comprises at least one of a silica reinforcing filler and quartz. Section 6. A cured silicone rubber is obtained by curing the above curable silicone rubber composition. Section 7. Item 6. A cured-in-place gasket comprising or consisting of a cured product of the curable silicone rubber composition according to any one of items 1 to 5. Section 8. 8. The cured-in-place gasket of claim 7 bonded to an aluminum substrate. Section 9. A method for producing a cured silicone rubber and / or a cure-in-place gasket (CIPG) by mixing and curing the curable silicone rubber composition according to any one of items 1 to 5. Section 10. Item 10. A method for producing a cured silicone rubber and / or cured-in-place gasket (CIPG) according to item 9, wherein the silicone rubber composition is applied onto a substrate as beads or threads of the silicone rubber composition from a suitable applicator onto the target surface. Section 11. Item 11. The method for producing cured silicone rubber and / or cured-in-place gaskets (CIPG) according to item 10, wherein the applicator is a robotic applicator pre-programmed to control the introduction of the silicone rubber composition threads to provide a gasket having a desired shape and minimizing waste. Section 12. Item 12. A method for producing a cured silicone rubber and / or a cure-in-place gasket (CIPG) according to any one of Items 9 to 11, wherein the method is continuous, such that target substrates are placed at predefined positions on a conveyor belt that transports each substrate to a position designed to apply the composition using a robotic applicator, the applicator applies the composition in a preprogrammed pattern, and the substrates are then transported on the conveyor belt through a heating zone of a conveyor oven at a desired temperature of 120°C to 180°C for 2 to 20 minutes. Section 13. A cured silicone rubber obtained or obtainable by mixing and curing the curable silicone rubber composition according to any one of items 1 to 5, and / or a cured-in-place gasket (CIPG) obtained or obtainable by mixing and curing the curable silicone rubber composition according to any one of items 1 to 5 on a suitable substrate. Section 14. 6. Use of the curable silicone rubber composition according to any one of paragraphs 1 to 5 to produce a cured silicone rubber and / or cured-in-place gasket (CIPG) that adheres to an aluminum substrate such that the lap shear measured in accordance with ASTM D816-82 (reapproved in 2001) is greater than (>) 1.5 MPa while retaining a compression set of 40% or less after 22 hours at 177°C in accordance with ASTM D395 Method B. Section 15. Use of the curable silicone rubber composition according to any one of items 1 to 5 to produce cured silicone rubber and / or cured-in-place gaskets (CIPG) for use as a barrier to prevent absorption or penetration of air, dust, noise, liquids, gaseous substances, or dirt; as sound dampening, vibration dampening, shock absorbing elements, moisture barriers, chemical protection, and air seals, and / or as air filters, oil pan gaskets, oil seal case gaskets, oil screen gaskets, timing belt cover upper gaskets, and timing rocker cover lower gaskets for automotive applications; and as gaskets for electrical equipment such as waterproof connectors, air conditioners, lighting devices, and electronic components. Section 16. Item 16. Use of the curable silicone rubber composition according to item 15, wherein the automotive application comprises an automotive gasket application selected from the group consisting of gaskets for electric vehicle (EV) battery packs, gaskets for EV batteries, gaskets for motor control units in EVs, housing seals, and coolant area seals.

Claims

1. A curable-in-place silicone rubber composition comprising the following components: a) a polydiorganosiloxane having at least two unsaturated groups selected from alkenyl or alkynyl groups per molecule; b) an organosilicon compound having at least two, alternatively at least three, Si—H groups per molecule; c) a mixture of a silica reinforcing filler and a non-reinforcing filler selected from quartz, each filler present having been hydrophobized; and d) a hydrosilylation catalyst comprising or consisting of a platinum group metal or a compound thereof; e) a tetraalkyl titanate, wherein each alkyl group may be the same or different and has from 1 to 20 carbon atoms, and wherein the tetraalkyl titanate is present in an amount of from 0.01 to 0.15 weight percent of the composition; f) an alkyl polysilicate, wherein the alkyl groups may be the same or different and may contain up to 6 carbon atoms per group, present in an amount of 0 to 2.5% by weight of the composition; g) a suitable (meth)acrylate compound present in an amount of 0.1 to 2.5% by weight of the composition; h) a compound having at least two trialkoxysilyl groups, at least two dialkoxyalkylsilyl groups, or a mixture of two or more trialkoxysilyl and dialkoxyalkylsilyl groups per molecule, (i)(R １０ ) ｚ (R １１ ) ３－ｚ Si-(W)-Si(R １１ ) ３－ｚ (R １０ ) ｚ [In the formula, each R １１ are the same or different and are alkoxy groups having 1 to 6 carbon atoms; １０ are the same or different, and R １１ or an alkyl group having 1 to 6 carbon atoms, z is 0 or 1, and W is a linear or branched alkylene group having 1 to 12 carbon atoms; or (ii) 1,3,5-tris[3-((R １０ ) ｚ (R １１ ) ３－ｚ Si)-D]-1,3,5-triazine-2,4,6(1H,3H,5H)-trione [In the formula, R １１ , R １０ and z is as defined above, and D is an alkylene group having 1 to 6 carbon atoms.

2. 2. The in situ curable silicone rubber composition of claim 1, wherein component (h) is selected from bis(trimethoxysilyl)ethane, bis(trimethoxysilyl)propane, bis(trimethoxysilyl)butane, bis(trimethoxysilyl)pentane, bis(trimethoxysilyl)hexane, bis(triethoxysilyl)ethane, bis(triethoxysilyl)propane, bis(triethoxysilyl)butane, bis(triethoxysilyl)pentane, bis(triethoxysilyl)hexane, and / or 1,3,5-tris[3-(trimethoxysilyl)propyl]-1,3,5-triazine-2,4,6-(1H,3H,5H)trione.

3. 10. The curable in place silicone rubber composition of claim 1, further comprising one or more cure inhibitors, metal deactivators, and / or oil-resistant agents.

4. 4. The in-place curable silicone rubber composition of claim 3, wherein the metal deactivator is dodecanedioic acid, bis[2-(2-hydroxybenzoyl)hydrazide], and / or the oil-resistant agent is magnesium hydroxide.

5. A cured silicone rubber obtained by curing the in-situ curable silicone rubber composition described in any one of claims 1 to 4.

6. A cured-in-place gasket comprising or consisting of the cured product of the cured-in-place silicone rubber composition of claim 1.

7. 7. The cured-in-place gasket of claim 6 bonded to an aluminum substrate.

8. 10. A method for producing a cured silicone rubber and / or a cured-in-place gasket (CIPG) by mixing and curing the cured-in-place silicone rubber composition of claim 1.

9. 10. The method of making a cured silicone rubber and / or cured-in-place gasket (CIPG) according to claim 8, wherein the cured-in-place silicone rubber composition is applied onto a substrate as beads or threads of the cured-in-place silicone rubber composition from a suitable applicator onto a target surface.

10. 10. The method of producing a cured silicone rubber and / or cured-in-place gasket (CIPG) according to claim 9, wherein the applicator is a robotic applicator pre-programmed to control the introduction of the thread of the cured-in-place silicone rubber composition to provide a gasket having a desired shape and minimizing waste.

11. 11. The method for producing cured silicone rubber and / or cured-in-place gaskets (CIPG) according to any one of claims 8 to 10, wherein the method is continuous, such that target substrates are placed at predefined locations on a conveyor belt which transports each substrate to a location designed to apply the cured-in-place silicone rubber composition using a robotic applicator, the applicator applies the cured-in-place silicone rubber composition in a preprogrammed pattern, and the substrates are then transported on the conveyor belt through a heated zone of a conveyor oven at a desired temperature of 120°C to 180°C for 2 to 20 minutes.

12. A cured silicone rubber obtained or obtainable by mixing and curing the curable in place silicone rubber composition according to any one of claims 1 to 4, and / or a cured in place gasket (CIPG) obtained or obtainable by mixing and curing the curable in place silicone rubber composition according to any one of claims 1 to 4 on a suitable substrate.

13. 5. Use of the in-place curable silicone rubber composition according to any one of claims 1 to 4 to make a cured silicone rubber and / or cured-in-place gasket (CIPG) that adheres to an aluminum substrate with a lap shear of greater than (>) 1.5 MPa as measured according to ASTM D816-82 (Reapproved 2001) while retaining a compression set of 40% or less after testing at 177°C for 22 hours according to ASTM D395 Method B.

14. 10. Use of the in-place curable silicone rubber composition of claim 1 to manufacture cured silicone rubber and / or cured-in-place gaskets (CIPG) for use as a barrier to prevent absorption or penetration of air, dust, noise, liquids, gaseous substances, or dirt; as sound dampening, vibration dampening, shock absorbing elements, moisture barriers, chemical protection, and air seals, and / or as air filters, oil pan gaskets, oil seal case gaskets, oil screen gaskets, timing belt cover upper gaskets, timing rocker cover lower gaskets for automotive applications; and as gaskets for electrical equipment such as waterproof connectors, air conditioners, lighting devices, electronic components, etc.

15. 15. The use of claim 14, wherein the automotive application comprises an automotive gasket application selected from an electric vehicle (EV) battery pack gasket, an EV battery gasket, a gasket for a motor control unit in an EV, a housing seal, and a coolant area seal.

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