Silicone elastomer compositions

Abstract

The present disclosure relates to curable silicone elastomer compositions which cure by hydrosilylation and which comprise an organopolysiloxane based adhesion promoter which, upon cure, provides enhanced adhesive properties for the resulting silicone elastomeric materials with respect to thermoplastic materials, organic resin based materials or both thermoplastic materials and organic resin based materials with which they are placed in direct contact prior to or during the cure process.

Description

[0001] SILICONE ELASTOMER COMPOSITIONS The present disclosure relates to curable silicone elastomer compositions comprising an organopolysiloxane based adhesion promoter which, upon cure, provides enhanced adhesive properties for the resulting silicone elastomeric materials with respect to a wide variety of substrates. Curable silicone elastomer compositions cure to provide silicone elastomeric materials (silicone rubbers) via several cure mechanisms, in particular by way of an addition (hydrosilylation) cure mechanism with a platinum group catalyst or a peroxide free-radical cure mechanism. Curable silicone elastomer compositions may be able to adhere during cure to substrates made from thermoplastic materials, organic resin based materials or both thermoplastic materials and organic resin based materials with which they are placed in direct contact prior to or during the cure process. In some cases, said curable silicone elastomer compositions may be considered to have what is referred to in the industry as “selective adhesion” towards certain substrates. For the avoidance of doubt, the term “selective adhesion” herein is intended to mean that, a curable silicone elastomer composition, upon cure, provides a silicone elastomer material which is able to provide an adhesive bond in direct contact with a thermoplastic or resin substrate without the need of e.g., primers or the like being previously applied onto the substrate surface, whilst being non- / oradhesive towards metallic substrates, such as molds. “Selective adhesion” is sometimes alternatively referred to as “self-adhesion” or “self-bonding”. The term “direct contact” is intended to mean that the adhesive properties of the curable silicone elastomer compositions are such that no primers are required to be applied to the surface of the substrates made from thermoplastic materials, organic resin based materials or both thermoplastic materials and organic resin based materials in order to generate adhesion. By the time the silicone elastomer has cured on the substrate surface there is adhesion between the interfaces of the silicone elastomer and the organic substrate. Liquid silicone rubber (LSR) elastomers are used in a wide variety of applications including, for the sake of example, in consumer applications such as kitchenware; electric and electronic, healthcare, and automotive applications not least because they have highly reliable properties with respect to heat resistance, weatherability and electrical insulation. Selective adhesion LSR elastomers are used in many of these applications to produce hard-soft (plastic-LSR) composites in injection molding processes. For example, in automotive connector seal applications, selective adhesion (sometimes otherwise known as self-adhesion) silicone elastomers can provide reliable sealing performance compared with many plastics particularly in harsh environments. They provide reliable seals for the safe running of automotive electronic control systems, enhancing the safety and comfort experience for both drivers and passengers. Silicone seals are also important for the waterproofing and sealing of parts made from silicone elastomer in smart phone and wearable devices. However, in certain applications their use has been limited due to their inability to form sufficiently strong adhesive bonds with plastic and thermoplastic substrates. Silicone elastomer compositions are also used in textile coatings such as those used in garments, automotive airbag coatings and parachutes, where adhesion to substrates is critical to enhance performance. Selective adhesion silicone elastomers are also useful as adhesives,gaskets, sealsand coatings for a variety of advanced assembly applications, such as lid seals for electronic modules, encapsulants, potting gels and coatings for consumer and automotive electronics, cure-in-place gaskets, headlamps, and appliances. Additionally, silicone elastomers with selective adhesion to thermoplastic filmic substrates are also useful as release liners and release coatings. For example, it may be desired for a curable silicone elastomer composition to be overmolded, coated, printed, dispensed or otherwise applied onto other parts (or substrates) made of different or the same materials. In many cases, these substrates comprise organic polymer-based thermoplastics such as polyesters, polyamides, polyimides, acrylics, styrenics, polyphthalamides and polycarbonates. In other cases, the substrates comprise thermosetting resins such as epoxy or urethane or urea-based polymers or composites such as FR-4 substrates (FR-4 is a composite material of woven fiberglass cloth with an epoxy resin binder that is flame resistant). For example, a silicone gasket can be moulded onto a thermoplastic housing, made from a polyamide or polyester. In another example a wearable electronic device can be obtained by overmolding a hard thermoplastic with a soft layer or part made of liquid silicone rubber. Further examples include airbag fabrics such as polyamides or polyesters coated with a silicone elastomer. Organic substrates onto which selective adhesion silicone rubber compositions may be cured include, for the sake of example, acrylonitrile-butadiene-styrene, polyphenylene / styrene blends, polystyrenes, polycarbonates (PC), polyurethane, styrene resin, polyethylene, polypropylene, acrylic, polyacrylates, polymethacrylates, polyacrylamides, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT); polyphenylene oxide, polyphenylene sulfide, polysulfone, polyamide (PA), such as nylon 6 (PA 6) nylon 6,6 (PA 6,6) and nylon 6,10; blends of polyamide resins with syndiotactic polystyrene, polyimide, fluoropolymers, and liquid crystal resin, non-resin containing polyetherimides; phenolic resins, epoxy resins, epoxy mold compounds urea resins, melamine resins, alkyd resins, acrylonitrile-butadiene- styrenes, styrene-modified poly(phenylene oxides), poly(phenylene sulfides), vinyl esters or polyphthalamides and combinations thereof, while enabling good release from metal mold during injection molding. In other embodiments, the curable silicone composition may be applied onto an inorganic substrate such as glass or ceramics, onto cellulosic substrates such as paper, wood, as well as onto previously mentioned organic substrates described above or any combination thereof as composites represented in a single substrate, or between multiple substrates in any combination to form a bonded article. However, in several instances such as bonding to polyamide or polyester fabrics, even selective adhesion silicone compositions typically require that the fabric be plasma or corona treated to exhibit good adhesion and scrub-resistance. The application of primers onto the substrate surfaces was initially utilized to overcome poor adhesive properties of such elastomers towards a multitude of substrates. However, several problems have arisen using methods requiring primers. Primer methods, for example, are cumbersome not least because they can result in unreliable productivity, quality control issues and indeed reliability issues for parts / articles being made. The selection, storage, use and processing of primers can also greatly influence the adhesion level resulting in a need to take great care of them not least during storage before use. So, the use of primers needs to be well controlled in order to achieve good adhesion and such processes are often time consuming and may result in low productivity and seals of variable quality. There is therefore a desire to avoid the use of primers if possible and this has latterly been achieved by using selective adhesion silicone elastomeric materials which have satisfactory adhesion without the need for primed surfaces. Similarly, high energy surface pre-treatments, such as irradiation by exposure to plasma, corona, flame, UV, or UV-ozone sources to activate the surface for adhesion can be problematic. While high energy treatments can eliminate the need for curing a wet chemical primer, they typically require special capital equipment and assembly processes to safely carry out the pre-treatments. In the case of addition (hydrosilylation) cure compositions it has been suggested to incorporate hydrosilylation curable silicone elastomer cross-linkers, e.g., organohydrogenpolysiloxanes in the plastic or thermoplastic substrate. However, such a process has been found to have a negative effect on the physical properties of the thermoplastic material itself preventing the resin from exerting its own properties. Physical engagement methods, not requiring an adhesive effect, may also be used, but leave a possibility that the two segments may be disengaged by physical forces. The use of selective adhesion silicone elastomers is a preferred alternative as it can give better productivity, quality control and reliability of the parts / articles at least partially due to the removal of the need to use the primer or surface pre-treatments. A variety of chemistries have been proposed for adhesion promotion in selective adhesion situations. The use of alkoxysilanes e.g., alkoxysilanes containing glycidoxy and acryloxy groups are effective but are not preferred because they tend to negatively affect shelf stability e.g., due to viscosity increase, loss of adhesion, during shelf storage due to their inherent reactivity to moisture, and hydrolytic instability. They can have the further disadvantage of generally being reactive to metal surfaces, posing a challenge for injection molding processes in which they are most commonly used. Adhesion promoters containing phenylene / bisphenol A structural units are widely known and tend to be designed for adhesion to plastics containing aromatic counterparts (e.g., polybutylene terephthalate (PBT), however lack of compatibility and shelf life are disadvantages and they may not be suitable for use in sensitive medical / consumer applications. Mixtures / reaction products of standard adhesion promoters with other ingredients e.g., co-cross- linkers and condensation catalysts have also been used but have several drawbacks including discoloration issues, formulation complexity i.e., being difficult to formulate into a shelf-stable 2- part system due the inherent reactive interactions of the various adhesion components, as well as the Platinum group hydrosilylation catalysts and crosslinkers of the addition curable composition often resulting in good for adhesion but having a poor shelf-life and being far too expensive for many applications. The durability of adhesion between the selective adhesion silicone elastomeric material and the thermoplastic substrates, organic resin substrates or thermoplastic and organic resin substrates is of great importance for the use of such combinations as composites to be a success but the provision of composites with good adhesion to untreated thermoplastics remains a technical challenge. The present disclosure relates to a curable silicone elastomer composition that can achieve adhesion on plastic / thermoplastic / resin material substrates, comprising: (A) one or more organopolysiloxanes containing at least 2 alkenyl and / or alkynyl groups per molecule and having a viscosity in a range of 1000mPa.s to 750,000mPa.s at 25oC; (B) a hydrosilylation cure catalyst package comprising: (i) an organosilicon compound having at least 2, alternatively at least 3 Si-H groups per molecule; and (ii) hydrosilylation catalyst; (C) one or more reinforcing fillers, one or more non-reinforcing fillers or a mixture thereof; and (D) an organosiloxane adhesion promoter having the structure: n an average from 2 to 18, each R1is an independently selected monovalent hydrocarbyl group, (alternatively an alkyl group) and each R2is independently selected from the group consisting of hydrogen (H), an organic moiety comprising an epoxy group and an organic moiety comprising an anhydride group; with the proviso that each R2per molecule is H or each molecule contains a mixture of R2groups consisting of one or more organic moieties comprising an epoxy group and one or more hydrogens (H); or each molecule contains a mixture of R2groups consisting of one or more organic moieties comprising an anhydride group and one or more hydrogens (H). Hence, at least one of the R2groups per molecule is a hydrogen thereby providing each molecule with one or more Si-H groups. It was unexpectedly found that the addition of component (D) herein containing a diphenyl siloxane group where each R2is H provides for adhesion of silicone elastomers to engineering plastics such as polyester or nylon. Furthermore, the replacement of some of the R2hydrogens with organic moieties containing epoxy groups or anhydride groups further enhances the adhesion performance. There is also provided a process for preparing an article or a composite part of an article comprising a) forming a mixture of the curable silicone elastomer composition according to any preceding claim, and b) applying the mixture onto a surface of a thermoplastic substrate, an organic resin substrate or a thermoplastic and organic resin substrate; c) curing the mixture at a temperature of from 80 to 200°C. There is further provided an article comprising a silicone elastomeric material cured from curable silicone elastomer composition described herein. Furthermore, there is provided a use of a curable silicone elastomer composition described herein in the making of an article comprising a cured elastomeric material made from said composition adhered to a thermoplastic substrates, organic resin substrates or thermoplastic and organic resin substrate. The different components of the composition described herein are discussed below. Component (A) Component (A) of the curable silicone elastomer composition comprises one or more organopolysiloxanes containing at least two alkenyl groups, at least two alkynyl groups or a mixture thereof per molecule and having a viscosity in a range of 1000mPa.s to 750,000mPa.s at 25oC. The organopolysiloxane (A) may be either a single polymer, or a combination of two or more different polymers. Each organopolysiloxane polymer of component (A) comprises multiple siloxy units, of formula (I): R’aSiO(4-a) / 2 (I) The subscript “a” is 0, 1, 2 or 3. Siloxy units may be described by a shorthand (abbreviated) nomenclature, namely - "M," "D," "T," and "Q", when R’ is a monovalent hydrocarbyl group. The M unit corresponds to a siloxy unit where a = 3, that is R’3SiO1 / 2; the D unit corresponds to a siloxy unit where a = 2, namely R’2SiO2 / 2; the T unit corresponds to a siloxy unit where a = 1, namely R’1SiO3 / 2; the Q unit corresponds to a siloxy unit where a = 0, namely SiO4 / 2. The organopolysiloxane polymer of component (A) is substantially linear but may contain a proportion of branching due to the presence of T units (as previously described) within the molecule, hence the average value of a in structure (I) is about 2. The unsaturated groups of component (A) may be positioned either terminally or pendently on the organopolysiloxane polymer, or in both locations. The unsaturated groups of component (A) may be alkenyl groups or alkynyl groups as described above but are preferably alkenyl groups. Each alkenyl group, when present, may comprise for example from 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, and alternatively 2 to 6 carbon atoms. When present the alkenyl groups may be exemplified by, but not limited to, vinyl, allyl, methallyl, propenyl, and hexenyl and cyclohexenyl groups. Each alkynyl group, when present, may also have 2 to 30, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 12, alternatively 2 to 10, and alternatively 2 to 6 carbon atoms. Examples of alkynyl groups may be exemplified by, but not limited to, ethynyl, propynyl, and butynyl groups. Preferred examples of the unsaturated groups of component (A) include vinyl, propenyl, isopropenyl, butenyl, allyl, and 5-hexenyl. In formula (I), each R’, other than the unsaturated groups described above, is a monovalent hydrocarbyl group, independently selected from an aliphatic hydrocarbyl group, a substituted aliphatic hydrocarbyl group, an aromatic group or a substituted aromatic group. Each aliphatic hydrocarbyl group may be exemplified by, but not limited to, alkyl groups having from 1 to 20 carbons per group, alternatively 1 to 15 carbons per group, alternatively 1 to 12 carbons per group, alternatively 1 to 10 carbons per group, alternatively 1 to 6 carbons per group or cycloalkyl groups such as cyclohexyl. Specific examples of alkyl groups having from 1 to 20 carbons may include methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl groups, alternatively methyl and ethyl groups. For the purpose of this application “Substituted” means one or more hydrogen atoms in a hydrocarbon group has been replaced with another substituent. Examples of such substituents include, but are not limited to, halogen atoms such as chlorine, fluorine, bromine, and iodine; halogen atom containing groups such as chloromethyl, perfluorobutyl, trifluoroethyl, trifluoropropyl and nonafluorohexyl; oxygen atoms; oxygen atom containing groups such as (meth)acrylic and carboxyl; nitrogen atoms; nitrogen atom containing groups such as amino-functional groups, amido- functional groups, and cyano-functional groups; sulphur atoms; and sulphur atom containing groups such as mercapto groups. Substituted aliphatic hydrocarbyl group are preferably non-halogenated substituted alkyl groups. The aliphatic non-halogenated organyl groups are exemplified by, but not limited to alkyl groups as described above with a substituted group such as suitable nitrogen containing groups such as amido groups, imido groups; oxygen containing groups such as polyoxyalkylene groups, carbonyl groups, alkoxy groups and hydroxyl groups. Further organyl groups may include sulfur containing groups, phosphorus containing groups, boron containing groups. Examples of aromatic groups or substituted aromatic groups are phenyl groups and substituted phenyl groups with substituted groups as described above. Component (A) of the curable silicone elastomer composition may, for example, be selected from polydimethylsiloxanes, alkylmethylpolysiloxanes, alkylarylpolysiloxanes or copolymers thereof (where reference to alkyl means any suitable alkyl group, alternatively an alkyl group having two or more carbons) providing each polymer has a viscosity of organopolysiloxane polymer (a) should be between 1000 and 750,000mPa.s inclusive at 25 ºC, Hence component (A) may, for the sake of example, be: a dialkylalkenyl terminated polydimethylsiloxane, e.g., dimethylvinyl terminated polydimethylsiloxane; a dialkylalkenyl terminated dimethylmethylphenylsiloxane, e.g., dimethylvinyl terminated dimethylmethylphenylsiloxane; a trialkyl terminated dimethylmethylvinyl polysiloxane; a dialkylvinyl terminated dimethylmethylvinyl polysiloxane copolymer; a dialkylvinyl terminated methylphenylpolysiloxane, a dialkylalkenyl terminated methylvinylmethylphenylsiloxane; a dialkylalkenyl terminated methylvinyldiphenylsiloxane; a dialkylalkenyl terminated methylvinyl methylphenyl dimethylsiloxane; a trimethyl terminated methylvinyl methylphenylsiloxane; a trimethyl terminated methylvinyl diphenylsiloxane; or a trimethyl terminated methylvinyl methylphenyl dimethylsiloxane. The viscosity of the or each organopolysiloxane polymer (A) is from 1000 to 750,000mPa.s inclusive at 25 ºC, alternatively from 1000 to 650,000mPa.s at 25 ºC, alternatively from 1000 to 500,000mPa.s at 25 ºC, alternatively from 1000 to 300,000mPa.s at 25 ºC, alternatively from 1000 to 250,000mPa.s at 25 ºC, alternatively, from 1000mPa.s to 150,000mPa.s, alternatively from 1000mPa.s to 100,000mPa.s at 25 ºC. Unless otherwise indicated all viscosity measurement given are provided using a BrookfieldTMRVF viscometer with the spindle selected based on viscosity range and operated at a preferred rpm. An alternative is using cup / spindle method of ASTM D 1084 Method B, using the most appropriate spindle from the BrookfieldTMRV or LV range for the viscosity range. Typically, the alkenyl and / or alkynyl content, e.g., vinyl content of the polymer is from 0.01 to 3 wt. % for each organopolysiloxane polymer containing at least two silicon-bonded alkenyl groups per molecule of component (A), alternatively from 0.01 to 2.5 wt. % of component (A), alternatively from 0.001 to 2.0 wt. %, alternatively from 0.01 to 1.5 wt. % of component (A) of the or each organopolysiloxane polymer containing at least two unsaturated groups per molecule, which unsaturated groups are selected from alkenyl or alkynyl groups per molecule of component (A). The alkenyl / alkynyl content of component (A) is determined using quantitative infra-red analysis with reference to ASTM E168-16(2023). The organopolysiloxane (A) is present in the curable silicone elastomer composition at a level of from 10 to 85 weight (wt.) % of the composition, alternatively 20 to 80 wt. % of the composition, alternatively 20 to 75 wt. % of the composition, alternatively from 25 to 75 wt. % of the composition, alternatively from 30 to 75 wt. % of the composition, alternatively from 30 to 60 wt. % of the composition. Typically, component (A) is present in an amount which is the difference between 100 wt. % and the cumulative wt. % of the other components / ingredients of the composition. Hydrosilylation cure catalyst package (B) Hydrosilylation cure catalyst package (B) of the curable silicone elastomer composition comprises (i) an organosilicon compound having at least 2, alternatively at least 3 Si-H groups per molecule; and (ii) hydrosilylation catalyst. Component (B)(i) Component (B)(i) is a an organosilicon compound which functions as a cross-linker. Component (B)(i) is in the form of an organosilicon compound containing at least two or at least three silicon- bonded hydrogen atoms per molecule. Component (B)(i) normally contains three or more silicon- bonded hydrogen atoms so that the hydrogen atoms can react with the unsaturated alkenyl or alkynyl groups of polymer (A) to form a network structure therewith and thereby cure the composition. Some or all of Component (B)(i) may alternatively have two silicon bonded hydrogen atoms per molecule when polymer (A) has greater than (>) 2 alkenyl or alkynyl groups per molecule. The structure of the organosilicon compound can be linear, branched, cyclic, or resinous. Cyclosilanes and cyclosiloxanes can have from 3 to 12 silicon atoms, alternatively from 3 to 10 silicon atoms, alternatively from 3 to 4 silicon atoms. In acyclic polysilanes and polysiloxanes, the silicon-bonded hydrogen atoms can be located at terminal, pendant, or at both terminal and pendant positions. Examples of suitable organosilanes can include diphenylsilane, 2-chloroethylsilane, bis[(p- dimethylsilyl)phenyl]ether, 1,4-dimethyldisilylethane, 1,3,5-tris(dimethylsilyl)benzene, 1,3,5- trimethyl-1,3,5-trisilane, poly(methylsilylene)phenylene, and poly(methylsilylene)methylene. In some examples, the organohydrogensilane can have the formula HR52Si-R6-SiR52H, wherein R5is C1 to C10hydrocarbyl or C1to C10halogen-substituted hydrocarbyl, both free of aliphatic unsaturation, and R6is a hydrocarbylene group free of aliphatic unsaturation having a formula selected from 1,4- or 1,3-disubstituted phenyl, 4,4’- or 3,3’-disubstituted-1,1’-biphenyl, or para- or meta-disubstituted Ph(CgH2g)Ph. The molecular configuration of the organopolysiloxane containing at least 2 or 3 silicon-bonded hydrogen atoms per molecule (B)(i) is not specifically restricted, and it can be a straight chain, a straight chain with some branching, cyclic or silicone resin based. Given their very low viscosities cross-linker viscosities are determined by capillary measurement in accordance with ASTM D-445. Silicon-bonded organic groups used in component (B)(i) maybe exemplified by methyl, ethyl, propyl, butenyl, pentenyl, hexyl, or similar alkyl groups; phenyl, tolyl, xylyl, or similar aryl groups; 3-chloropropyl, 3,3,3-trifluoropropyl, or similar halogenated alkyl group, preferable of which are methyl and phenyl groups. The organopolysiloxane containing at least 2 or 3 silicon-bonded hydrogen atoms per molecule (B)(i) is typically added in an amount such that the molar ratio of the total number of the silicon- bonded hydrogen atoms in component (B)(i) to the total number of alkenyl and / or alkynyl groups in polymer (A) is from 0.5:1 to 20:1. When this ratio is less than 0.5:1, a well-cured composition will not be obtained. When the ratio exceeds 20:1, there is a tendency for the hardness of the cured composition to increase when heated. Examples of the organopolysiloxane containing at least 2 or 3 silicon-bonded hydrogen atoms per molecule (B)(i) include but are not limited to: (a’) trimethylsiloxy-terminated methylhydrogenpolysiloxane, (b’) trimethylsiloxy-terminated polydimethylsiloxane-methylhydrogensiloxane, (c’) dimethylhydrogensiloxy-terminated dimethylsiloxane-methylhydrogensiloxane copolymers, (d’) dimethylsiloxane-methylhydrogensiloxane cyclic copolymers, (e’) copolymers and / or silicon resins consisting of (CH3)2HSiO1 / 2 units, (CH3)3SiO1 / 2 units and SiO4 / 2 units, (f’) copolymers and / or silicone resins consisting of (CH3)2HSiO1 / 2 units and SiO4 / 2 units, (g’) copolymers and / or silicone resins consisting of (CH3)2HSiO1 / 2 units, SiO4 / 2 units and (C6H5)3SiO1 / 2 units, and alternatives in which methyl is replaced by phenyl groups or other alkyl groups. Alternatively, component (B)(i) the cross-linker, may be a filler, e.g., silica treated with one of the above. Component (B)(i) can be exemplified by the following compounds: a methylhydrogenpolysiloxane capped at both molecular terminals with trimethylsiloxy groups; a copolymer of a methylhydrogensiloxane and a dimethylsiloxane capped at both molecular terminals with trimethylsiloxy groups; dimethylsiloxane capped at both molecular terminals with dimethylhydrogensiloxy groups; a copolymer of a methylhydrogensiloxane and a dimethylsiloxane capped at both molecular terminals with dimethylhydrogensiloxy groups; a copolymer of a methylhydrogensiloxane and a methylphenylsiloxane capped at both molecular terminals with dimethylphenylsiloxy groups; a cyclic methylhydrogenpolysiloxane; a copolymer consisting of (CH3)2HSiO1 / 2 siloxane units and SiO4 / 2 units; a copolymer consisting of (CH3)2HSiO1 / 2 siloxane units, (CH3)3SiO1 / 2 siloxane units, and SiO4 / 2 units, the aforementioned organopolysiloxanes in which a part or all methyl groups are substituted with ethyl, propyl, or similar alkyl groups; phenyl, tolyl, or similar aryl groups; 3,3,3-trifluoropropyl, or similar halogenated alkyl groups; or a mixture of two or more of the aforementioned organopolysiloxanes. The organosilicon compound cross-linker (B)(i) is generally present in the curable silicone elastomer composition in an amount such that the ratio of the mole number of silicon-bonded hydrogen atoms of component (B)(i) to the mole number of unsaturated groups e.g., alkenyl groups of component (A) ranges from (0.7 : 1.0) to (5.0 : 1.0), preferably from (0.9 : 1.0) to (2.5 : 1.0), and most preferably from (0.9 : 1.0) to (2.0 : 1.0). The silicon-bonded hydrogen (Si-H) content of component (B)(i) is determined using quantitative infra-red analysis with reference to ASTM E168-16(2023). In the present instance the silicon- bonded hydrogen to alkenyl (vinyl) and / or alkynyl ratio is important when relying on a hydrosilylation cure process. Generally, this is determined by calculating the total weight % of alkenyl groups in the composition, e.g., vinyl [V] and the total weight % of silicon bonded hydrogen [H] in the composition and given the molecular weight of hydrogen is 1 and of vinyl is 27 the molar ratio of silicon bonded hydrogen to vinyl is 27[H] / [V]. Typically dependent on the number of unsaturated groups in component (A) and the number of Si-H groups in component (B)(i), component (B)(i) will be present in an amount of from 0.1 to 40% by weight of the total composition, alternatively from 0.5 to 20%, by weight of the total composition alternatively 0.5 to 10% by weight of the total composition, further alternatively from 1% to 5% by weight of the total composition. Component (B)(ii) Component (B)(ii) of the curable silicone elastomer composition is at least one hydrosilylation (addition) reaction catalyst. These are usually selected from catalysts of the platinum metal group (platinum, ruthenium, osmium, rhodium, iridium and palladium), or a compound of one or more of such metals. Platinum and rhodium compounds are preferred due to the high activity level of these catalysts in hydrosilylation reactions. Component (B)(ii) catalyses the reaction between the alkenyl e.g., vinyl groups of component (A) and the Si-H groups of component (B)(i) resulting in a cross- linked network when the curable silicone elastomer compositions are cured to their respective elastomers. The catalyst (B)(ii) can be a platinum group metal, a platinum group metal deposited on a carrier, such as activated carbon, metal oxides, such as aluminium oxide or silicon dioxide, silica gel or powdered charcoal, or a compound or complex of a platinum group metal. Examples of preferred hydrosilylation catalysts (B)(ii) are platinum based catalysts, for example, platinum black, platinum oxide (Adams catalyst), platinum on various solid supports, chloroplatinic acids, e.g., hexachloroplatinic acid (Pt oxidation state IV) (Speier catalyst), chloroplatinic acid in solutions of alcohols e.g., isooctanol or amyl alcohol (Lamoreaux catalyst), and complexes of chloroplatinic acid with ethylenically unsaturated compounds such as olefins and organosiloxanes containing ethylenically unsaturated silicon-bonded hydrocarbon groups, e.g., tetra-vinyl- tetramethylcyclotetrasiloxane-platinum complex (Ashby catalyst). Soluble platinum compounds that can be used include, for example, the platinum-olefin complexes of the formulae (PtCl2.(olefin)2and H(PtCl3.olefin), preference being given in this context to the use of alkenes having 2 to 8 carbon atoms, such as ethylene, propylene, isomers of butene and of octene, or cycloalkanes having 5 to 7 carbon atoms, such as cyclopentene, cyclohexene, and cycloheptene. Other soluble platinum catalysts are, for the sake of example a platinum-cyclopropane complex of the formula (PtCl2C3H6)2, the reaction products of hexachloroplatinic acid with alcohols, ethers, and aldehydes or mixtures thereof, or the reaction product of hexachloroplatinic acid and / or its conversion products with vinyl- containing siloxanes such as methylvinylcyclotetrasiloxane in the presence of sodium bicarbonate in ethanolic solution –. Platinum catalysts with phosphorus and amine ligands can be used as well, e.g., (Ph3P)2PtCl2; and complexes of platinum with vinylsiloxanes, such as sym- divinyltetramethyldisiloxane. Hence, specific examples of suitable platinum-based catalysts include: (i) complexes of chloroplatinic acid with organosiloxanes containing ethylenically unsaturated hydrocarbon groups are described in US 3,419,593; (ii) chloroplatinic acid, either in hexahydrate form or anhydrous form; (iii) a platinum-containing catalyst which is obtained by a method comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound, such as divinyltetramethyldisiloxane; (iv) alkene-platinum-silyl complexes as described in US Pat. No.6,605,734 such as (COD)Pt(SiMeCl2)2 where “COD” is 1,5-cyclooctadiene; and / or (v) Karstedt’s catalyst is Pt2(divinyl tetramethyl disiloxane)3 complex typically containing from 30 to 50 wt. % platinum metal in the complex. It is typically introduced into a silicone rubber composition in premix with a vinyl siloxane polymer. The combination being from about from 0.25 to 2.0 wt. % of the catalyst complex in 99.75 wt. % to 98 wt. % of the vinyl siloxane polymer which usually has a viscosity of from about 200 to 750 mPa.s at 25oC using the test methodology as described for component (a). Solvents such as toluene and the like organic solvents have been used historically as alternatives but the use of vinyl siloxane polymers by far the preferred choice. These are described in US3,715,334 and US3,814,730. The hydrosilylation catalyst (B)(ii) of the hydrosilylation curable silicone elastomer composition is present in the total composition in a catalytic amount, i.e., an amount or quantity sufficient to catalyse the addition / hydrosilylation reaction and cure the composition to a silicone elastomeric material under the desired conditions. Varying levels of the hydrosilylation catalyst (B)(ii) can be used to tailor reaction rate and cure kinetics. The catalytic amount of the hydrosilylation catalyst (B)(ii) is generally between 0.01 ppm, and 10,000 parts by weight of platinum-group metal, per million parts (ppm), based on the weight of the composition alternatively, between 0.01 and 5000ppm; alternatively, between 0.01 and 3,000 ppm, and alternatively between 0.01 and 1,000 ppm. In specific embodiments, the catalytic amount of the catalyst may range from 0.01 to 1,000 ppm, alternatively 0.01 to 750 ppm, alternatively 0.01 to 500 ppm and alternatively 0.01 to 100 ppm of metal based on the weight of the composition. The ranges may relate solely to the metal content within the catalyst or to the catalyst altogether (including its ligands) as specified, but typically these ranges relate solely to the metal content within the catalyst. The catalyst may be added as a single species or as a mixture of two or more different species. Typically, dependent on the form / concentration in which the catalyst package is provided the amount of catalyst present will be within the range of from 0.001 to 3.0wt. % of the composition. Component (C) Component (C) a of the curable silicone elastomer composition is one or more reinforcing fillers, one or more non-reinforcing fillers or a mixture thereof. The reinforcing fillers of component (C) may be exemplified by fumed silica, precipitated silica, and / or colloidal silicas. Typically these are provided in a finely divided form (i.e., they do not clump / stick together). Precipitated silica fumed silica and / or colloidal silicas are particularly preferred because of their relatively high surface area, which is typically at least 50 m² / g (BET method in accordance with ISO 9277: 2010). Fillers having surface areas of from 50 to 450 m² / g (BET method in accordance with ISO 9277: 2010), alternatively of from 50 to 300 m² / g (BET method in accordance with ISO 9277: 2010), are typically used. All these types of silica are commercially available. Such reinforcing fillers (e.g., untreated silica fillers), are generally naturally hydrophilic and therefore are difficult to mix with silicone polymers which are substantially hydrophobic. Hence, such fillers are typically treated with a treating agent to render them hydrophobic. Once hydrophobically modified such reinforcing fillers (C) do not clump and can be homogeneously incorporated into polydiorganosiloxane polymer (A). The surface treatment makes the fillers easily wetted by polydiorganosiloxane polymer (A). Typically the surface treatment is achieved using low molecular weight organosilicon compounds which are known in the art. These may include organosilanes, polydiorganosiloxanes and / or organosilazanes e.g., hexaalkyl disilazane and short chain siloxane diols which can coat the fillers and render them hydrophobic and therefore easier to handle and obtain a homogeneous mixture with the other ingredients (components), particularly component (A). Specific examples include, but are not restricted to, silanol terminated trifluoropropylmethyl siloxane, silanol terminated vinyl methyl (ViMe) siloxane, silanol terminated methylphenyl (MePh) siloxane, liquid hydroxyldimethyl- terminated polydiorganosiloxane containing an average from 2 to 20 repeating units of diorganosiloxane in each molecule, hexaorganodisiloxanes, such as hexamethyldisiloxane, divinyltetramethyldisiloxane; hexaorganodisilazanes, such as hexamethyldisilazane (HMDZ), divinyltetramethyldisilazane and tetramethyldi(trifluoropropyl)disilazane; hydroxyldimethyl terminated polydimethylmethylvinyl siloxane, octamethyl cyclotetrasiloxane, and silanes including but not limited to methyltrimethoxysilane, dimethyldimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, chlrotrimethyl silane, dichlrodimethyl silane, trichloromethyl silane. A small amount of water can be added together with the silica treating agent(s) as processing aid. The surface treatment may be undertaken prior to introduction in the composition or in situ (i.e., in the presence of at least a portion of the other ingredients (components) of the composition herein by blending these ingredients (components) together at room temperature or above until the filler is completely treated. Typically, untreated reinforcing filler (C) is treated in situ with a treating agent in the presence of polydiorganosiloxane polymer (A) which results in the preparation of a silicone elastomer base material which can subsequently be mixed with other ingredients (components). Reinforcing filler (C) is present in an amount of from 5.0 to 40wt. % of the composition, alternatively of from 7.5 to 35wt. % of the composition, alternatively of from 10.0 to 30wt. % based on the weight % of the composition. Alternatively and / or additionally component (C) may comprise non-reinforcing fillers. These may include, for the sake of example, crushed quartz, precipitated calcium carbonate, ground calcium carbonate, diatomaceous earths, barium sulphate, iron oxide, titanium dioxide and carbon black, talc, wollastonite, aluminite, calcium sulphate (anhydrite), gypsum, calcium sulphate, magnesium carbonate, clays such as kaolin, aluminium trihydroxide, magnesium hydroxide (brucite), graphite, copper carbonate, e.g., malachite, nickel carbonate, e.g., zarachite, barium carbonate, e.g., witherite and / or strontium carbonate e.g.,strontianite. Other non-reinforcing fillers may include, aluminum oxide, silicates from the group consisting of olivine group; garnet group; aluminosilicates; ring silicates; chain silicates; and sheet silicates. The olivine group comprises silicate minerals, such as but not limited to, forsterite and Mg2SiO4. The garnet group comprises ground silicate minerals, such as but not limited to, pyrope; Mg3Al2Si3O12; grossular; and Ca2Al2Si3O12. Aluminosilicates comprise ground silicate minerals, such as but not limited to, sillimanite; Al2SiO5; mullite; 3Al2O3.2SiO2; kyanite; and Al2SiO5. Ring silicates may be utilised as non-reinforcing fillers, these include silicate minerals, such as but not limited to, cordierite and Al3(Mg,Fe)2[Si4AlO18]. The chain silicates group comprises ground silicate minerals, such as but not limited to, wollastonite and Ca[SiO3]. Sheet silicates may alternatively or additionally be used as non-reinforcing fillers where appropriate group comprises silicate minerals, such as but not limited to, mica; K2AI14[Si6Al2O20](OH)4; pyrophyllite; Al4[Si8O20](OH)4; talc; Mg6[Si8O20](OH)4; serpentine for example, asbestos; Kaolinite; Al4[Si4O10](OH)8; and vermiculite. In one alternative the fillers will be selected from one or more of fumed silica, precipitated silica, calcium carbonate, talc, mica, quartz and aluminum oxide. If desired any non-reinforcing fillers may also be treated with the aforementioned treating agents to render them hydrophobic. Component (D) As previously indicated component (D) of the curable silicone elastomer composition as hereinbefore described is an organopolysiloxane adhesion promoter having the structure: wherein each subscript n independently has an average value of from 2 to 18, alternatively an average value of from 2 to 15, alternatively an average value of from 2 to 12, alternatively an average value of from 2 to 10, alternatively an average value of from 2 to 6, alternatively an average value of from 2 to 4. As will be seen from the structure above, each R2group is linked to a silicon which forms part of a siloxane ring and is not linked to a silicon in a linear chain. In the case when R2is H and consequently forms an Si-H bond, such a bond is sometimes referred to as a DHtype Si-H linkage. Each R1is an independently selected monovalent hydrocarbyl group, independently selected from an aliphatic hydrocarbyl group, a substituted aliphatic hydrocarbyl group, an aromatic group or a substituted aromatic group with the term substituted having the same definition as provided previously. Each aliphatic hydrocarbyl group may be exemplified by, but not limited to, alkyl groups having from 1 to 20 carbons per group, alternatively 1 to 15 carbons per group, alternatively 1 to 12 carbons per group, alternatively 1 to 10 carbons per group, alternatively 1 to 6 carbons per group or cycloalkyl groups such as cyclohexyl. Specific examples of alkyl groups may include methyl, ethyl, propyl, pentyl, octyl, undecyl, and octadecyl groups, alternatively methyl and ethyl groups. Examples of aromatic groups or substituted aromatic groups are phenyl groups and substituted phenyl groups with substituted groups as described above. Each R2is independently selected from the group consisting of hydrogen (H), an organic moiety comprising an epoxy group and an organic moiety comprising an anhydride group; When an R2is an organic moiety comprising an epoxy group it may comprise an alkyl epoxide group or an alkyl glycidyl ether of the structures below: and branched is different and is from 2 to 30, t is from 2 to 15, alternatively, subscript t is from 2 to 10. By the term anhydride functionality it is meant that each organic moiety comprising an anhydride group contains a group with the following structure: -C(=O)-O-C(=O)- which may or may not be cyclic. The anhydride functionality may be introduced onto the ring of component D by undertaking a hydrosilylation reaction between an alkenyl group of a compound which contains both an anhydride group and an alkenyl group (e.g., a vinyl group) such as for the sake of example, a linear or branched unsaturated anhydride e.g.,anhydride – Z1– vinyl where the Z1group is a linear or branched alkylene chain having from 1 to 20 carbons, with an Si-H group of the cyclic siloxane described above. Unsaturated anhydrides include maleic anhydride, succinic anhydride, alkenyl succinic anhydrides such as allyl succinic anhydride and polyisobutylene succinic anhydride (PIBSA); citraconic anhydride, oxalic anhydride, and phthalic anhydride groups crotonic anhydride, diphenic anhydride, isatoic anhydride, itaconic anhydride, phenylmaleic anhydride, nadic anhydride, 3-(but-3-enyl)- 1,2,3,6-tetrahydrophthalic anhydride, and cis-1,2,3,6- tetrahydrophthalic anhydride and phenylsuccinic anhydride. In one embodiment the unsaturated anhydrides are selected from maleic anhydride, succinic anhydride, allyl succinic anhydride, oxalic anhydride, and phthalic anhydride. For example, when R2is an organic moiety comprising an anhydride group. The anhydride functionality can be, and desirably is, a cyclic anhydride i.e., in a five-membered or six membered ring, where the single bonded oxygen and carbonyl carbon are part of a ring of bonded atoms such as for example a maleic anhydride group of the following structure: and branched t is as described above. Each Component (D) molecule contains several R2groups. The actual number is dependent on the size of the siloxane rings but typically there is an average of four or more R2groups per molecule. As previously indicated, there is a proviso in respect to the adhesion promoter (D) structure. The proviso being that: each R2per molecule is H or each molecule contains a mixture of R2groups consisting of one or more organic moieties comprising an epoxy group and one or more H groups; or each molecule contains a mixture of R2groups consisting of one or more organic moieties comprising an anhydride group and one or more H groups. Hence, for example when each molecule of component (D) contains a mixture of R2groups consisting of one or more organic moieties comprising an epoxy group and one or more H groups, (forming an Si-H bond with a silicon) such that there the total number of R2groups in a molecule is Z where: Z = [total number of R2organic moieties comprising an epoxy group] + [total number of R2groups which are hydrogen (H) groups] Hence, if Z = 4, i.e., a component (D) molecule contains four R2groups it may comprise any combination of the two types of groups i.e., one organic moiety comprising an epoxy group and three H groups and consequently three Si-H bonds, two organic moieties comprising an epoxy group and two H groups, or three organic moieties comprising an epoxy group and H group. Similarly, if for example when each molecule of component (D) contains a mixture of R2groups consisting of one or more organic moieties comprising an anhydride group and one or more H groups, when there is a total of five R2groups in the molecule i.e., a component (D) molecule contains five R2groups, it may comprise any combination of the two types of groups i.e., one organic moiety comprising an anhydride group and four H groups, two organic moieties comprising an anhydride group and three H groups, or three organic moieties comprising an anhydride group and two H groups, or four organic moieties comprising an anhydride group and one H group. In each of the above alternatives it will be appreciated that in accordance with the proviso when each molecule of component (D) contains a mixture of R2groups consisting of one or more organic moieties comprising an epoxy group and one or more H groups (forming Si-H bonds), only organic moieties comprising an epoxy group and one or more H groups are present as R2groups and when each molecule of component (D) contains a mixture of R2groups consisting of one or more organic moieties comprising an anhydride group and one or more H groups, only organic moieties comprising an anhydride group and one or more H groups are present as R2. In each instance above in a preferred embodiment at least two H groups (forming Si-H bonds) are present as R2groups. In another alternative a maximum of four organic moieties comprising an epoxy group or a maximum of four organic moieties comprising an anhydride group are present as a proportion of the R2groups per molecule of component (D). Alternatively, a maximum of three organic moieties comprising an epoxy group or a maximum of three organic moieties comprising an anhydride group are present as a proportion of the R2groups per molecule of component (D). Alternatively, a maximum of two organic moieties comprising an epoxy group or a maximum of two organic moieties comprising an anhydride group are present as a proportion of the R2groups per molecule of component (D). In one preferred embodiment each siloxane ring in component (D) has one or two organic moieties comprising an epoxy group or one or two organic moieties comprising an anhydride group are present as a proportion of the R2groups per molecule of component (D), alternatively one organic moiety comprising an epoxy group or a maximum of one organic moiety comprising an anhydride group are present per molecule of component (D). In each of the above the remaining R2groups are hydrogen (H). Three examples of adhesion promoter (D) are depicted below in which each n is 2 and Z is 6. result in the presence of -Si-H bonds O H O one per an epoxy group and the remaining R2groups are H. In the above there is one organic moiety per siloxane ring comprising an anhydride group and the remaining R2groups are H. Component (D) the adhesion promoter is typically present in the composition in an amount of from about 0.1 to 6wt. % of the composition; alternatively, 0.1 to 4 wt. % of the composition. Additional optional ingredients Additional optional ingredients may be present in the curable silicone elastomer composition as hereinbefore described depending on the intended final use thereof. Examples of such optional ingredients include cure inhibitors, pot life extenders, flame retardants, lubricants, MQ resins, such as vinylated MQ resins or non-vinylated MQ resins; pigments and / or colouring agents, bactericides, wetting agents, heat stabilizers and compression set additives and mixtures thereof. Cure inhibitors When the curable silicone elastomer composition as hereinbefore described is being cured via an addition / hydrosilylation reaction a cure inhibitor may be utilized to inhibit the cure of the composition. These cure inhibitors are utilized to prevent premature cure in storage and / or to obtain a longer working time or pot life of a hydrosilylation cured composition by retarding or suppressing the activity of the catalyst. Cure inhibitors of hydrosilylation catalysts (B)(ii), e.g., platinum metal-based catalysts are well known in the art and may include hydrazines, triazoles, phosphines, mercaptans, organic nitrogen compounds, acetylenic alcohols, silylated acetylenic alcohols, maleates, such as dibutyl maleate; fumarates, ethylenically or aromatically unsaturated amides, ethylenically unsaturated isocyanates, olefinic siloxanes, such as tetramethyltetravinylcyclotetrasiloxane; unsaturated hydrocarbon monoesters and diesters, conjugated ene-ynes, hydroperoxides, nitriles, and diaziridines. Alkenyl- substituted siloxanes as described in US 3,989,667 may be used, of which cyclic methylvinylsiloxanes are preferred. One class of known cure inhibitors of hydrosilylation catalysts, e.g., platinum catalysts (B)(ii) include the acetylenic compounds disclosed in US 3,445,420. Acetylenic alcohols such as 2-methyl-3-butyn-2-ol constitute a preferred class of cure inhibitors that will suppress the activity of a platinum-containing catalyst at 25 ºC. Compositions containing these cure inhibitors typically require heating at temperature of 70 ºC or above to cure at a practical rate. Examples of acetylenic alcohols and their derivatives include 1-ethynyl-1-cyclohexanol (ETCH), 2- methyl-3-butyn-2-ol, 3-butyn-1-ol, 3-methyl butynol 3-butyn-2-ol, propargyl alcohol, 2-phenyl-2- propyn-1-ol, 3,5-dimethyl-1-hexyn-3-ol, 1-ethynylcyclopentanol, 1-phenyl-2-propynol, 3-methyl-1- penten-4-yn-3-ol, and mixtures thereof. In one alternative the cure inhibitor is selected from one or more of 1-ethynyl-1-cyclohexanol (ETCH), tetramethyltetravinylcyclotetrasiloxane, 3-methyl butynol and / or dibutyl maleate. When present, cure inhibitor concentrations as low as 1 mole of cure inhibitor per mole of the metal of catalyst (B)(ii) will in some instances impart satisfactory storage stability and cure rate. In other instances, cure inhibitor concentrations of up to 500 moles of cure inhibitor per mole of the metal of catalyst (B)(ii) are required. Mixtures of the above may also be used. Dependent on the concentration and form in which the cure inhibitor selected is provided / available commercially, when present in the composition, the cure inhibitor is typically present in an amount of from 0.0001-10wt. %, alternatively 0.001-5%, cure inhibitor, alternatively 0.0125 to 5wt. % of the composition and the higher levels are cure inhibitor masterbatches comprising the cure inhibitor and e.g., an organopolysiloxane containing at least two alkenyl groups as defined in component (A) above or a saturated equivalent. Pot life extenders, such as triazole, may be used, but are not considered necessary in the scope of the present invention. The curable silicone elastomer composition may thus be free of pot life extenders unless deemed necessary for a specific use. Examples of flame retardants chlorinated paraffins, hexabromocyclododecane, triphenyl phosphate, dimethyl methylphosphonate, tris(2,3-dibromopropyl) phosphate (brominated tris), and mixtures or derivatives thereof. When present in composition, if required the flame retardant may be present in an amount of from 5 to 50 wt. % of the composition. Examples of lubricants include tetrafluoroethylene, resin powder, graphite, fluorinated graphite, talc, boron nitride, fluorine oil, silicone oil, molybdenum disulfide, and mixtures or derivatives thereof. MQ resins The composition may also include one or more MQ silicone resins which can be synthesized through the hydrolysis and condensation of alkoxysilanes and chlorosilanes. Alternatively, MQ resins can be synthesized through the polymerization of aqueous alkali silicates in the presence of acid followed by reaction with triorgano alkoxysilanes, triorgano chlorosilanes, hexaorganodisiloxanes or mixtures thereof. Typically, the MQ resins, when present, comprise SiO4 / 2 (Q) siloxane units and R4₃SiO1 / 2 (M) siloxane units wherein each R4may be the same or different and denotes a monovalent group selected from hydrocarbon groups, having from 1 to 20 carbon atoms and, alternatively from 1 to 12 carbon atoms. Examples of suitable R4groups include alkyl groups, such as methyl, ethyl, propyl, pentyl, octyl, undecyl and octadecyl; cycloaliphatic groups, such as cyclohexyl; alkenyl groups, having from 2 to 12 carbons, such as vinyl, propenyl, butenyl, pentenyl, hexenyl, and the like; alkynyl groups selected from ethynyl, propynyl, butynyl, pentynyl or hexynyl and the like; aryl groups such as phenyl, tolyl, xylyl, benzyl, alpha-methyl styryl and 2-phenylethyl; alternatively R4groups are vinyl, methyl, ethyl or phenyl groups, e.g., examples of preferred R2₃SiO1 / 2 (M) siloxane units include Me₃SiO1 / 2, PhMe₂SiO1 / 2, ViMe₂SiO1 / 2 and Ph₂MeSiO1 / 2, where Me hereinafter denotes methyl, Vi is vinyl and Ph hereinafter denotes phenyl. The silicone resin can be a single silicone resin or a mixture comprising two or more different silicone resins, each as described above. Typically, they are MQ resins comprising ViMe₂SiO1 / 2units, in combination with Me₃SiO1 / 2, and / or PhMe₂SiO1 / 2 groups. Additionally, the MQ resin may contain residual OZ5, where Z5can represent hydrogen or alkyl groups. OZ5groups remain on the Q components after synthesis of silicone MQ resins indicative of incomplete condensation during the reaction to produce the MQ resin providing the OZ5content meets the above hydroxyl per mole Si requirements. Residual OZ5is inherent to the processes and reactions utilized to make MQ resins. The MQ resin may also undergo a subsequent silylation reaction to further minimize residual OZ5. The MQ resin when present, is typically delivered in a hydrocarbon or silicone solvent, free from solvent the silicone resin is typically a solid but preferably herein the optional MQ resin is delivered in a silicone solvent such as a non-functional polydimethylsiloxane or a polydimethylsiloxane comprising two or more alkenyl groups per molecule, such as for example component (a) herein. For example, molar ratio of M siloxane units to Q siloxane units has a value of from 0.5:1 to 1.2:1, alternatively 0.6:1 to 1.1:1, alternatively 0.8:1 to 1.1:1, alternatively 0.9:1 to 1.1:1. In one embodiment MQ resin includes a resinous portion wherein the M units are bonded to SiO4 / 2 siloxane units (i.e., Q units) and each of the Q units is bonded to at least one other SiO4 / 2 (Q) siloxane unit. The molar ratio of M units to Q units is from 0.3 : 1 to 1.2 : 1, alternatively 0.4:1 to 1.1:1, alternatively 0.5:1 to 1:1, alternatively 0.6:1 to 0.9:1. Such an MQ resin suitable as component may have a number-average molecular weight (Mn) of from 2000 to 50,000g / mol, alternatively from 3,000 to 30,000 g / mol. In one embodiment the silicone resin may be described in the terms of a molar fraction as an MQ silicone resin having the formula: (R43SiO1 / 2)u(SiO4 / 2)v wherein each R4may be the same or is different is a hydrocarbon group, alternatively a C1 to C10 alkyl group, a C2 to C10 unsaturated group selected from an alkenyl or alkynyl group or a mixture thereof. Typically, MQ resins, of the structure (R43SiO1 / 2)u(SiO4 / 2)vwill have at least some M groups with at least one R4group being an unsaturated group, alternatively one R4group being an alkenyl group comprising from 2 to 6 carbons, alternatively a vinyl group. In one alternative at least one R4per M group is an alkenyl group, typically a vinyl group in which case the M groups may be referred to as MVigroups. Furthermore, u and v are mole fractions with the value of u + v is 1.0. In one embodiment, when present, u is from 0.3 to 0.6, alternatively 0.37 to 0.52, v is from 0.4 to 0.7, alternatively 0.48 to 0.63, and the value of u + v is 1.0. Examples of pigments and other colorants which may be utilized in the curable silicone elastomer composition include pigments, vat dyes, reactive dyes, acid dyes, chrome dyes, disperse dyes, cationic dyes and mixtures thereof. The curable silicone elastomer composition as described herein may further comprise one or more pigments and / or colorants which may be added if desired. The pigments and / or colorants may be coloured, white, black, metal effect, and luminescent e.g., fluorescent and phosphorescent. Pigments are utilized to colour the composition as required. Any suitable pigment may be utilized providing it is compatible with the composition herein. Suitable white pigments and / or colorants include titanium dioxide, zinc oxide, lead oxide, zinc sulfide, lithophone, zirconium oxide, and antimony oxide. Suitable non-white inorganic pigments and / or colorants include, but are not limited to, iron oxide pigments such as goethite, lepidocrocite, hematite, maghemite, and magnetite 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, and 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 chromium yellow, molybdate red, and molybdate orange; ultramarine pigments; cobalt oxide pigments; nickel antimony titanates; lead chrome; carbon black; lampblack, and metal effect pigments such as aluminium, copper, copper oxide, bronze, stainless steel, nickel, zinc, and brass. Suitable organic non-white pigments and / or colorants include phthalocyanine pigments, e.g., phthalocyanine blue and phthalocyanine green; monoarylide yellow, diarylide yellow, benzimidazolone yellow, heterocyclic yellow, DAN orange, quinacridone pigments, e.g., quinacridone magenta and quinacridone violet; organic reds, including metallized azo reds and nonmetallized azo reds and other azo pigments, monoazo pigments, diazo pigments, azo pigment lakes, β-naphthol pigments, naphthol AS pigments, benzimidazolone pigments, diazo condensation pigment, 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 diketopyrrolo pyrrole pigments. Typically, the pigments and / or colorants, when particulates, have average particle diameters in the range of from 10 nm to 50 µm, preferably in the range of from 40 nm to 2 µm. The pigments and dyes may be used in form of pigment masterbatch composed of them dispersed in component (a) at the ratio of 25:75 to 70:30. The curable silicone elastomer compositions may be heat stabilised. Examples of heat stabilizers may include metal compounds such as red iron oxide, yellow iron oxide, ferric hydroxide, cerium oxide, cerium hydroxide, lanthanum oxide, copper phthalocyanine, fumed titanium dioxide, iron naphthenate, cerium naphthenate, cerium dimethylpolysilanolate and acetylacetone salts of a metal chosen from copper, zinc, aluminum, iron, cerium, zirconium, titanium and the like. Other examples of heat stabilizers may include suitable antioxidants or metal scavengers such as salicyloylaminotriazole, 1,2-bis(3,5-di-tert-butyl-4-hydroxylhydrocinnamoyl)hydrazine, 2-Hydroxy- N-1H-1,2,4-triazol-3-ylbenzamide, and N’1,N’12-Bis(2-hydroxybenzoyl)dodecanedihydrazide. The amount of heat stabilizer when present in the curable silicone elastomer compositions may range from 0.01 to 1.0 % weight of the curable silicone elastomer compositions. Unless the composition is to be used immediately after preparation, it is stored in two Parts, typically referred to as Part A and Part B to keep component (B)(i), the organosilicon compound having at least two or at least three Si-H groups per molecule, which functions as a cross-linker (cross-linker) and component (B)(ii) the hydrosilylation cure catalyst apart to avoid premature cure. Typically, a Part A composition will comprise components: (A) polymer, (C) one or more optional fillers as hereinbefore defined and (B)(ii), the hydrosilylation cure catalyst and Part B will comprise: (A) polymer, (C) one or more optional fillers as hereinbefore defined, (B)(i) the organosilicon compound having at least two or at least three Si-H groups per molecule which functions as a cross-linker and Cure inhibitor when present. Component (D) the adhesion promoter is typically stored in the part B composition because of its Si- H content. Other optional additives when present may be added to either Part A or Part B, providing they do not negatively affect the properties of any other components present (by e.g., catalyst inactivation). Part A and part B of the hydrosilylation curable silicone elastomeric composition described herein are mixed together shortly prior to use to initiate cure of the full composition into a silicone elastomeric material. The Part A and Part B compositions can be designed to be mixed in any suitable ratio, e.g., a weight ratio. For example, Part A and Part B may be mixed together in Part A : Part B weight ratios of from 100:1 to 1:100, alternatively from 10:1 to 1:10, alternatively from 5:1 to 1:5, but most preferred is a weight ratio of 1:1. Ingredients in each of Part A and Part B are mixed into their respective Part composition either individually or in pre-prepared combinations for, e.g., ease of mixing the final composition. For example, components (A) and (C) are often mixed together to form a liquid silicone rubber (LSR) base prior to the introduction of the other ingredients. These may then be mixed with the other ingredients of the Part being made directly or may be used to make pre-prepared concentrates commonly referred to in the industry as masterbatches. For example, component (D) may also be premixed with some of the component (A) in the Part B composition to form a “masterbatch”, if desired, prior to mixing with the other Part B ingredients. In this instance, for ease of mixing ingredients, one or more masterbatches may be utilized to successfully mix the ingredients to form Part A and / or Part B compositions. Parts A and B of the hydrosilylation curable silicone rubber elastomeric composition may be prepared by combining all of their respective components at ambient temperature. Any mixing techniques and devices described in the prior art can be used for this purpose. The particular device to be used will be determined by the viscosities of components and the final composition. Suitable mixers include but are not limited to a kneader mixer, a Z-blade mixer, a two roll mill (open mill), a three roll mill, a Haake® Rheomix OS Lab mixer, a screw extruder or a twin-screw extruder or the like. Speed mixers as sold by e.g., Hauschild and as DC 150.1 FV, DAC 400 FVZ or DAC 600 FVZ, may alternatively be used. Cooling during mixing may be desirable to avoid premature curing of the composition. There is provided herein a method of preparing an article with the curable silicone elastomer composition described herein comprising the steps of 1) disposing the curable silicone elastomer composition on a substrate; and 2) curing the curable silicone elastomer composition on the substrate. As previously mentioned, when the curable silicone elastomer composition is a hydrosilylation curable silicone elastomer composition, unless the composition is to be used immediately the composition is stored in two parts, Part A and Part B and these are mixed together in a desired weight ratio (unless otherwise indicated) prior to step (1) above. The curable silicone elastomer compositions may be processed (or cured) by injection moulding, press moulding, extrusion moulding, transfer moulding, press vulcanization, calendaring. Curing can for example take place in a mold to form a moulded silicone article adhered to an e.g., thermoplastic substrate. The curable silicone elastomer composition may for example be injection moulded to form an article adhered to the thermoplastic material, or the composition can be overmolded by injection moulding around thermoplastic substrates, organic resin substrates or thermoplastic and organic resin substrates or articles or over a thermoplastic substrate, organic resin substrate or thermoplastic and organic resin substrate. When cured in presence of a heat sensitive substrate, the curable silicone elastomer compositions as hereinbefore described is cured under such conditions enabling development of mechanical adhesion with the heat sensitive substrate and the like, and more specifically, by using a temperature and curing time at which the heat sensitive substrate is not deformed, melted, or denatured. Specific examples of suitable substrates include acrylonitrile-butadiene-styrene, polyphenylene / styrene blends, polystyrenes, polyoxymethylenes (POM); polyurethane, styrene resin, polyolefins such as polyethylene, polypropylene, and polybutylenes, polyacrylics such as polyacrylates, polymethacrylates such as polymethylenemethacrylates (PMMA); polyacrylamides, polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT) polytrimethylene terephthalates (PTT), polyethylene naphthalates (PEN); copolyesters, polyphenylene oxide, polyphenylene sulfide, polysulfone;, polyamides (PA), such as nylon 6 (PA 6), nylon 6,6 (PA 6,6) and nylon 6,10; blends of polyamide resins with syndiotactic polystyrene, polyimide, polyvinyl chlorides (PVC); polyphenylene sulfides (PPS); polyphenylene ethers (PPE); polyimides (PI); polyamideimides (PAI); polyetherimides (PEI); polysulfones (PSU); polyethersulfones; polyketones (PK); polyetherketones; polyvinyl alcohols (PVA); polyetheretherketones (PEEK); polyetherketoneketones (PEKK); polyarylates (PAR); polyethernitriles (PEN); phenolic resins; phenoxy resins; fluoropolymers, and liquid crystal resin, non-resin containing polyetherimides; phenolic resins, epoxy resins, epoxy mold compounds urea resins, melamine resins, alkyd resins, acrylonitrile-butadiene-styrenes, styrene-modified poly(phenylene oxides), poly(phenylene sulfides), vinyl esters or polyphthalamides. Any of the above may, if suited be reinforced with e.g., glass fibres or the like. In one embodiment the substrate may be a polyester optionally reinforced with glass fibres, e.g., polybutylene terephthalate (PBT) optionally reinforced with glass fibres, or a polyamide optionally reinforced with glass fibres e.g., nylon 6 (PA 6), nylon 6,6 (PA 6,6) and nylon 6,10 in each case optionally reinforced with glass fibres. Curing may be performed by any convenient means. For example, the curable silicone elastomer composition may cure by heating at an elevated temperature, e.g., from 50 °C to 200 °C, alternatively from 50 °C to 180 °C, alternatively, 50 °C to 160 °C, alternatively, 50 °C to 150 °C, alternatively, 75 °C to 150 °C, and alternatively, 90 °C to 150 °C, to give the composite article, which comprises a cured silicone elastomeric material (prepared by curing the curable silicone elastomer composition) adhered to the substrate. The cure temperature used will need to be below the melting point and / or softening point of the substrate to retain the required structure of the composite. Hence, one skilled in the art would be able to select an appropriate temperature depending on various factors including the selection of optional starting materials in the curable silicone elastomer composition and the substrate material of construction. The curable silicone elastomer composition may be cured at the elevated temperature for a period of time. The period of time is typically sufficient to effect curing, i.e., cross-linking, of the curable silicone elastomer composition. The period of time may be greater than 0 to 8 hours, alternatively greater than 0 to 2 hours, alternatively greater than 0 to 1 hour, alternatively greater than 0 to 30 minutes, alternatively greater than 0 to 15 minutes, alternatively greater than 0 to 10 minutes, alternatively greater than 0 to 5 minutes, alternatively greater than 0 to 2 minutes. The period of time depends on various factors including on the elevated temperature is utilized, the temperature selected, desired thickness of the cured silicone, and the presence of absence of any solvent in the curable silicone elastomer composition. The curable silicone elastomer compositions are designed to achieve, upon cure, significant adhesion on a thermoplastic substrate, on an organic resin substrate or on a thermoplastic and organic resin substrate surface and is preferably not adhesive to metal surfaces thereby forming articles and / or composite parts with the substrates listed above. Such articles can be utilised in various industries including, but not limited to, automotive applications, medical applications, consumer and industrial applications, electronic applications and may include for example, tubes, strips, solid cord or custom profiles according to the size specifications of the manufacturer. In automotive applications, this may include housings with a silicone seal or gaskets for plugs e.g., spark plugs and other connector seals, components of various sensors, membranes, diaphragms, airbags, climate venting components, and the like; spark plug caps, components of various sensors, and other automobile components. Electronic applications may include mobile phone cover seals, mobile phone accessories, precision electronic equipment, electrical switches and switch covers, toothbrushes, watches and wristbands, wearable apparatus, e.g., facemasks, wearable electronic devices, and the like. A composite part may also be selected from parts of mobile telecommunications equipment, e.g., mobile phones; gaming machines, clocks and image receivers; media playing devices such as DVD equipmentand CD equipment; as well as in TVs e.g., in thin displays of liquid crystal TVs and plasma TVs, and other precision electronic equipment. They may also be used in consumer goods such as microwave ovens, refrigerators, electric rice cookers, vacuum cleaners, hand dryers and office automation (OA) equipment such as copying machines, printers, facsimile machines. In one embodiment the silicone elastomeric compositions as hereinbefore described may be utilised as a coating for coating airbags and the like. In such an embodiment the silicone elastomeric composition as hereinbefore described may be applied on to a fabric substrate, typically a one-piece woven or flat fabric airbag substrate by any suitable known technique. These include spraying, gravure coating, bar coating, knife coating, e.g., coating by knife-over-roller, coating by knife-over- air; padding, dipping and screen-printing. The hydrosilylation curable silicone elastomeric composition can be applied, in the form of a coating, onto one or both sides of a textile or fabric material substrate, e.g., an airbag fabric which is to be cut into pieces and sewn to assemble an airbag or may be applied onto a one-piece woven airbag. Curing of such an airbag coating composition once applied onto the woven fabric is typically conducted by heating the composition at a temperature of from 150 to 200°C for 45 seconds to 2 minutes which can be accomplished using a suitable oven or through drying tunnel of circulating hot-air ovens. Although it is not preferred, it is possible to apply the composition via an iterative process i.e., by applying multiple layers of the coating composition, which together have a pre-determined mean dry coat weight which can be measured in accordance with ISO 3801. It is also possible to apply onto the coating composition a further compatible coating, e.g., of a material providing e.g., low friction, if deemed necessary. Any suitable desired coat weight may be applied on the textile or fabric material such as an airbag, e.g., from 15 to 150 g / m2, alternatively from 15 to 100 g / m2, alternatively from 20 to 75 g / m2determined in accordance with ISO 3801. The thickness of coating layer ranges from of 20 to 80μm depending on the coating weight. In another embodiment the curable silicone elastomer composition as hereinbefore described may be applied to the surface of the substrate be processed using a 3D printing method. The 3D printer may be selected from a fused filament fabrication printer, a selective laser sintering printer, a selective laser melting printer, a stereolithography printer, a powder bed (binder jet) printer, a material jet printer, a direct metal laser sintering printer, an electron beam melting printer, a laminated object manufacturing deposition printer, a directed energy deposition printer, a laser powder forming printer, a polyjet printer, an ink-jetting printer, a material jetting printer, and a syringe extrusion printer. A typical method of forming a three-dimensional (3D) article may comprise multiple steps. For example, the method may comprise (i) providing a thermoplastic substrate, organic resin substrate or thermoplastic and organic resin substrate. The method may further comprise (ii) heating the substrate. In addition, the method may comprise (iii) printing a curable silicone elastomer composition as hereinbefore described on the substrate with a 3D printer to form a subsequent layer. Optionally, the latter step may be repeated if required to apply one or more further layers. Examples A series of examples were conducted to assess the functionality of the proposed new adhesion promoters. All component (A) viscosity measurements were determined using Brookfield RVF viscometer may be utilised with the spindle selected based on viscosity range and operated at a preferred rpm as indicated below. The component (B)(i) viscosity measurements were made using capillary measurement in accordance with ASTM D-445. In a first series of examples, reference example Ref.1, Ex.1, 2 and 3 and comparative C.1 were prepared using the compositions depicted in Table 1a.

[0002] Table.1a: Compositions of Ref.1, Ex.1-3, C.1 (wt. %) Ref.1 Ex.1 Ex.2 Ex.3 C.1 MB1 17.30 17.30 17.30 17.30 17.30 MB 1 is Masterbatch 1 contains 70.8 parts by weight of a dimethylvinylsiloxy terminated polydimethylsiloxane having a viscosity of about 53,000 mPa.s at 25oC, and 22.4 parts by weight of a fumed silica filler having a surface area of approximately 300m2 / g. The silica is hydrophobized and contains no vinyl functionalization. MB 2 is Masterbatch 2 contains 66.6 parts by weight of a dimethylvinylsiloxy terminated polydimethylsiloxane having a viscosity of about 55 Pa.s at 25°C, and 25.8 parts by weight of a fumed silica filler having a surface area of approximately 300m2 / g. The silica is hydrophobized and has a vinyl functionalization of approximately 0.178 mmol / g; Polymer 1 is vinyldimethyl terminated polydimethylsiloxane having a viscosity of 53,000mPa.s at 25°C determined using a BrookfieldTMRVF viscometer with spindle 5 at 4rpm; Polymer 2 is Vinyl terminal poly(dimethylsiloxane-co-methylvinylsiloxane) having a viscosity of 370 mPa.s at 25°C determined using a BrookfieldTMRVF viscometer with RVF, Spindle 2 at 20rpm. X-linker 1 is trimethyl-terminated polymethylhydrogen dimethylsiloxane (viscosity = 30 mPa.s at 25 °C, Pt Cat. was a is Karstedt catalyst which is aPt2(divinyl tetramethyl disiloxane)3 complex; Inhib. Was 1-Ethynyl-1-cyclohexanol (commonly referred to as ETCH); The adhesion promoters used in the above compositions were as follows: AP 1 had the following structure: AP O O H C H H C H O Si O O Si O O AP 3 had the AP 4 It will be noted that AP4 does not comprises any cyclic siloxanes. As previously indicated, normally the liquid silicone rubber compositions are prepared in two parts to prevent premature curing during storage. For the enclosed laboratory examples the composition was made fresh and used immediately and as such for practical purposes did not involve preparing the composition in two parts and then immediately mixing them together. The results obtained were envisaged to be the same as if the two-part composition had been prepared and mixed together given the immediate use as no premature curing takes place. In a first series of examples to assess adhesion of the silicone compositions in Table 1a silicone compositions above were first prepared and then were assessed for their adhesion capabilities to (1) a commercially available polybutylene terephthalate (PBT) substrate reinforced with 20% glass fiber sold under the tradename UltradurTMB 4300 G4 by BASF SE; and (2) a glass fibre reinforced (30 wt. %) polyamide 6,6 (PA 6,6) substrate sold by BASF SE under the tradename UltramidTMA3EG6 UNCOLORED. In each case 25-mm x 100-mm substrates with a thickness of 3 mm were cleaned with isopropanol and dried for 18 h at 120 °C. The thermoplastic substrates were preheated at 150 °C for 5 min prior to overmolding with one of the silicone compositions depicted in Table 1a above. The thermoplastic substrates were overmolded with a 3-mm thick layer of the respective silicone composition and compression molded for 5 min at 150 °C at a pressure of 30 MPa (300 bar) using a TP400 heating press commercially available from Fontijne Presses BV of Delft, Netherlands. In order to assess the level of adhesion between the silicone and the respective thermoplastic substrate, adhesion was tested using a 90° peel test using a floating roller device in accordance with DIN EN ISO 22631 (“Adhesives - Test method for adhesives for floor and wall coverings”). A H10TMC tensile tester commercially available from Richard Hess MBV GmbH of Sonsbeck Germany was used at a pulling speed of 100 mm / min. The peel strength was calculated as the average peel force, divided by the sample width (25 mm), and reported in N / mm. The results are provided in Table 1b below. Table 1b: Peel Strength results on PBT and PA 6,6 substrates using the compositions depicted in Table 1a. Ref.1 Ex.1 Ex.2 Ex.3 C.1 0 0 It will be noted that adhesion failed completely in the case of the Reference example in which no adhesion promoter was included in the silicone composition. It was surprisingly found that APs 1 to 3 gave acceptable / good levels of adhesion and was probably more surprising that AP 4 did not. The main difference between the structure of AP1 and AP 4 was the fact the AP 1 was cyclic whilst AP 4 contained branched groups which were not cyclics and it would seem that the cyclic groups were required to provide adhesion promotion. In a further series of examples an assessment of the level of adhesion was undertaken using a variety of cross-linkers to identify if the cross-linker used for the hydrosilylation cure was significant. The compositions utilised were compared with the compositions in Ex.1 and Ex.2 depicted in Table 1a. Table 2a: Compositions of Ex.1, 2 and 4 – 8 (wt. %) with various cross-linkers present with the same S-H content. Ex.1 Ex.4 Ex.5 Ex.7 Ex.8 Ex.2 Ex.6 MB1 17.30 17.30 17.30 17.30 17.30 17.30 17.30 4 25 , , , , , . , ., AP1 and AP2 were all the same as defined above X-linker 2 trimethylsilyl terminated poly(dimethyl-co-methylhydrogen)siloxane having 0.70 wt. % H as Si-H and a viscosity of ~48 mm2 / s (cSt) at 25°C. H content in the form of Si-H determined using quantitative infra-red analysis with reference to ASTM E168-16(2023). X-linker 3 was an HMe2SiO0.5terminated MHQ resin having 0.97 wt. % H as Si-H and a viscosity of 22 mm2 / s (cSt) H content in the form of Si-H determined using quantitative infra-red analysis with reference to ASTM E168-16(2023). X-linker 4 was a phenyltris(dimethylsiloxy)silane having the following structure: H H3C Si CH3H X-linker 5 was an HMe2SiO0.5 terminated (45-50% n-ethylhydrosiloxane) phenylmethylsiloxane copolymer having a viscosity of between 75-110 mm2 / s (cSt) The amount of each cross-linker used was slightly different so that each composition had the same Si-H content when combining the respective cross-linker Si-H content and the Si-H content of the adhesion promoters present in the formulation concerned. Each composition prepared underwent the same cure process and the same adhesion test as described above and the results are provided in Table 2b below. Table 2b: Peel Strength results PBT and PA 6,6 substrates using the compositions depicted in Table 2a. Ex.1 Ex.4 Ex.5 Ex.7 Ex.8 Ex.2 Ex.6 Peel Strength (PBT) (N / mm) 1.93 1.79 4.43 3.31 1.12 2.53 1.18 2 cross- linker used in the composition. In a third series of tests, Ref.1, Ex.1 and C.1 compositions as described above as well as a second reference composition with no adhesion promoter present and a third comparative containing a standard adhesion promoter, glycidoxypropyl trimethoxysilane, identified as AP 5 in Table 3a were prepared, cured and compared for their physical properties. The compositions prepared are depicted in Table 3a. Table 3a: Compositions of Ref.1, Ex.1, C.1, Ref.2 and C.2 (wt. %) Ref.1 Ex.1 C.1 Ref.2 C.2 0 5 e press-cured for 10min at 120°C using TP400 heating press described above. No post-curing was undertaken. Shore A durometer was evaluated in accordance with ASTM D 2240. Tensile strength was assessed using the using S2 type test specimen in accordance with DIN 53504. Tear Strength results were obtained in accordance with ASTM D 624 B. Compression Set results were obtained in accordance with ISO 815-1:2019 method B (6 mm). The compression set buttons (thickness of 6 mm) were obtained by press-curing the LSR compositions for 10 minutes at 175°C in a suitable mold. No post curing was applied. Compression set was evaluated after 22 hours at 125°C. Curing kinetics were evaluated with a Moving Die Rheometer (MDR, Premier MDR from Alpha Technologies) in accordance with ISO 3417. The measurements were taken during a 10-minute press-cure process at 120°C. Tc2 and Tc60 indicate the time to reach 2% and 60% of the maximum torque respectively. The results are depicted in Table 3b below: Table 3b: Physical properties of the compositions depicted in Table 3a. Ref.1 Ex.1 C.1 Ref.2 C.2 Peel Stren th (PBT) (N / mm) 000 193 000 047 069 / A / A / A / A 3 As compared to the alternatives shown, Ex.1 the composition containing the inventive adhesion promoter gave, upon cure, a unique combination of fast cure, good physical properties, and low compression set. C.1 had fast cure, good physical properties, low compression set, but no adhesion; Ref.2 had poor adhesion, low tensile, and a very high compression set and C.2 had poor adhesion and very slow cure.

Claims

CLAIMS 1. A curable silicone elastomer composition that can achieve adhesion on plastic / thermoplastic / resin material substrates, comprising: (A) one or more organopolysiloxanes containing at least 2 alkenyl and / or alkynyl groups per molecule and having a viscosity in a range of 1000mPa.s to 750,000mPa.s at 25oC; (B) a hydrosilylation cure catalyst package comprising: (i) an organosilicon compound having at least 2, alternatively at least 3 Si-H groups per molecule; and (ii) hydrosilylation catalyst; (C) one or more reinforcing fillers, one or more non-reinforcing fillers or a mixture thereof; and (D) an organosiloxane adhesion promoter having the structure:from 2 to 18, each R1is an independently selected monovalent hydrocarbyl group, (alternatively an alkyl group) and each R2is independently selected from the group consisting of hydrogen (H), an organic moiety comprising an epoxy group and an organic moiety comprising an anhydride group; with the proviso that each R2per molecule is H or each molecule contains a mixture of R2groups consisting of one or more organic moieties comprising an epoxy group and one or more hydrogens (H) groups; or each molecule contains a mixture of R2groups consisting of one or more organic moieties comprising an anhydride group and one or more hydrogens (H).

2. A curable silicone elastomer composition in accordance with claim 1 wherein R2comprises at least one an organic moiety comprising an alkyl epoxide group or an alkyl glycidyl ether of the structures below:and branched isomers thereof, where each subscript t may be the same or is different and is from 2 to 30.

3. A curable silicone elastomer composition in accordance with claim 1 wherein R2comprises at least one an organic moiety comprising an anhydride group contains a group with the following structure: -C(=O)-O-C(=O)- which may be cyclic.

4. A curable silicone elastomer composition in accordance with claim 3 wherein R2comprises at least one an organic moiety comprising an anhydride group comprises a maleic anhydride group of the following structure: and branched subscript t may be the same or is different and is from 2to 30.

5. A curable silicone elastomer composition in accordance with any preceding claim wherein each subscript n in component D an average value of from 2 to 6.

6. A curable silicone elastomer composition in accordance with any preceding claim wherein each subscript n in component D an average value of from 2 to 4.

7. A curable silicone elastomer composition in accordance with any preceding claim wherein component (D) is added to said composition in an amount of from 0.5 to 5% by weight of the total composition of the other components.

8. A curable silicone elastomer composition of any of the preceding claims stored before use at least two separate parts.

9. A process for preparing an article or a composite part of an article comprising a) forming a mixture of the curable silicone elastomer composition according to any preceding claim, and b) applying the mixture onto a surface of a thermoplastic substrate, an organic resin substrate or a thermoplastic and organic resin substrate; c) curing the mixture at a temperature of from 80 to 200°C.

10. A process in accordance with claim 9 wherein the substrate is an optionally glass fibre reinforced polyamide or an optionally glass fibre reinforced polyester.

11. An article comprising a silicone elastomeric material cured from curable silicone elastomer composition according to any of claims 1 to 8.

12. An article in accordance with claim 11 which is a composite part containing silicone elastomer cured from curable silicone elastomer composition in accordance with claims 1 to 8 adhered to a thermoplastic substrate, an organic resin substrate or a thermoplastic and organic resin substrate.

13. An article in accordance with claim 11 or 12 which is a composite part containing silicone elastomer cured from curable silicone elastomer composition in accordance with claims 1 to 8 adhered to an optionally glass fibre reinforced polyamide or an optionally glass fibre reinforced polyester.

14. Use of a curable silicone elastomer composition in accordance with claims 1 to 8 in the making of an article comprising a cured elastomeric material made from said composition adhered to a thermoplastic substrates, organic resin substrates or thermoplastic and organic resin substrate.

15. Use of a composition in accordance with claim 14 in the making of an article comprising a cured elastomeric material made from said composition adhered to an optionally glass fibre reinforced polyamide or an optionally glass fibre reinforced polyester.

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