Curable compositions and methods for forming cured products

Abstract

The cured product comprises (A) an organopolysiloxane having an average of at least two silicon-bonded aliphatic unsaturated groups per molecule, (B) an organopolysiloxane that is free of aliphatic unsaturation and has an average of at least two mercapto groups per molecule, (C) a photoinitiator, (D) an acryloxy-functional silane, and (E) a tetraorthosilicate.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to and all benefits of U.S. Provisional Patent Application No. 63 / 393,964, filed July 31, 2022, the contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION The present disclosure relates generally to curable compositions, and more particularly to curable silicone compositions that can be cured by exposure to radiation to provide a cured product that has excellent adhesion to substrates, and related methods and articles. [Background technology]

[0003] Curable organopolysiloxane compositions are known in the art and are utilized in numerous industries. Curable organopolysiloxane compositions can be cured using different curing conditions depending on the functional groups present in or on the components of such curable organopolysiloxane compositions. Typical curing conditions include exposure to heat, moisture, radiation, and the like. Different end-use applications often dictate the specific curing conditions utilized; for example, certain curable organopolysiloxane compositions are utilized in end-use applications where exposure to heat is undesirable. This is particularly the case in certain electronics applications where exposing electronic components to high temperatures is undesirable.

[0004] UV curing of curable organopolysiloxane compositions is often utilized to prepare cured products that are desirable to cure in the absence of heat. Furthermore, certain substrates on which the cured products are formed may have complex geometries or surface characteristics, resulting in shadow areas that are difficult to cure with UV radiation. Therefore, it is often desirable to utilize a dual-cure system that can be cured with both UV radiation and moisture (or another curing mechanism that does not require high temperatures).

[0005] Certain functional groups, including certain epoxy-functional organopolysiloxane compositions, acrylate-functional organopolysiloxane compositions, and thiol-ene-functional organopolysiloxane compositions, are known to be UV-curable upon exposure to radiation. Thiol-ene-functional organopolysiloxane compositions are known to cure very rapidly compared to other functional groups known to be UV-curable. In addition, unlike acrylate-functional organopolysiloxane compositions, thiol-ene-functional organopolysiloxane compositions are not inhibited by ambient oxygen, which further accelerates their cure speed under ambient conditions. However, while conventional thiol-ene-functional organopolysiloxane compositions can cure very rapidly, they often exhibit insufficient or undesirable adhesion to substrates when cured to form a cured product, and often suffer from adhesive failure when removed from the substrate, which limits their use. Summary of the Invention

[0006] A curable composition is disclosed. The curable composition includes (A) an organopolysiloxane having an average of at least two silicon-bonded aliphatically unsaturated groups per molecule. The composition further includes (B) an organopolysiloxane having no aliphatically unsaturated groups and having an average of at least two mercapto groups per molecule. The composition also includes (C) a photoinitiator. Furthermore, the composition includes (D) an acryloxy-functional silane represented by the following formula:

[0007] [ka] wherein X is a divalent hydrocarbon group, each R is independently a hydrocarbyl group, and each R 1 are independently alkyl groups having 1 to 8 carbon atoms, the subscript x is 2 or 3, and R 2 is H or R 1 Finally, the composition has the formula (E) Si(OR 3 ) 4 tetraorthosilicates, wherein each R 3are independently alkyl groups having 1 to 10 carbon atoms.

[0008] Also disclosed is a method of forming a cured product. The method includes applying the composition to a surface of a substrate. The method further includes irradiating the composition on the substrate to obtain a cured product. Also disclosed is a cured product disposed on a substrate formed according to this method. DETAILED DESCRIPTION OF THE INVENTION

[0009] A curable composition ("composition"), a method of using the composition to form a cured product on a substrate, and the cured product formed thereby are disclosed and described in detail below. The composition forms a cured product that has excellent adhesion to the substrate and can be utilized in a myriad of end-use applications.

[0010] The composition comprises an organopolysiloxane (A) having an average of at least two silicon-bonded aliphatic unsaturated groups per molecule. As will be understood by those skilled in the art, organopolysiloxanes contain inorganic silicon-oxygen-silicon groups (i.e., -Si-O-Si-) and have organosilicon and / or organic side chains bonded to the silicon atoms of the M, D, and / or T siloxy units. Organopolysiloxanes are typically characterized by the number, type, and / or proportion of [M], [D], [T], and / or [Q] units / siloxy groups, each unit / siloxy group representing a structural unit of an individual functional group present in the organopolysiloxane resin. Specifically, [M] is a group of the general formula R"3SiO 1 / 2 [D] represents a monofunctional unit of the general formula R''SiO 2 / 2 [T] represents a difunctional unit of the general formula R''SiO 3 / 2 [Q] represents a trifunctional unit of the general formula SiO 4 / 2 and is represented by the following general structural moiety:

[0011] [ka]

[0012] In these general structural moieties, each R" is independently a monovalent or polyvalent substituent. As is understood in the art, the specific substituents suitable for each R" are not particularly limited (e.g., they can be monoatomic or polyatomic, organic or inorganic, straight-chain or branched, substituted or unsubstituted, aromatic, aliphatic, saturated or unsaturated, etc., and various combinations thereof).

[0013] Those skilled in the art understand how the [M], [D], [T], and [Q] units and their relative proportions (i.e., mole fractions) influence and control the structure of a siloxane, and polysiloxanes can generally be monomeric, polymeric, oligomeric, linear, branched, partially branched, hyperbranched, cyclic, dendritic, and / or resinous, depending on the selection of [M], [D], [T], and / or [Q] units therein. For example, [T] and / or [Q] units are present in organopolysiloxane resins, but linear organopolysiloxanes typically do not contain such [T] and / or [Q] units.

[0014] As mentioned above, (A) organopolysiloxane has an average of at least two silicon-bonded aliphatic unsaturated groups per molecule. The silicon-bonded aliphatic unsaturated groups may independently be alkenyl and / or alkynyl groups. "Alkenyl" refers to an acyclic, branched, or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. Specific examples include vinyl, allyl, hexenyl, and octenyl groups. "Alkynyl" refers to an acyclic, branched, or unbranched monovalent hydrocarbon group having one or more carbon-carbon triple bonds. Specific examples include ethynyl, propynyl, and butynyl groups. Various examples of aliphatic unsaturated groups suitable for (A) organopolysiloxane include:

[0015]

number

[0016] (A) The organopolysiloxane is not limited and may be any organopolysiloxane containing an average of at least two silicon-bonded aliphatic unsaturated groups per molecule. For example, (A) the organopolysiloxane may be linear, branched, partially branched, cyclic, resinous (i.e., having a three-dimensional network), or may include a combination of different structures.

[0017] In certain embodiments, (A) the organopolysiloxane has the following average formula. R q’ SiO (4-q’) / 2 In the formula, each R is an independently selected substituted or unsubstituted hydrocarbyl group, provided that in each molecule, on average, at least two R groups are independently selected aliphatic unsaturated groups, and q' is selected such that 0 < a' ≤ 3.2.

[0018] In certain embodiments, (A) the organopolysiloxane is represented by the following average formula. (R 4 3-m R 5 m SiO 1 / 2 ) a (R 4 2-n R 5 n SiO 2 / 2 ) b (R 5 SiO 3 / 2 ) c (SiO 4 / 2 ) d (ZO 1 / 2 ) e In the formula, each R 4 is an independently selected substituted or unsubstituted hydrocarbyl group that does not contain aliphatic unsaturation, and each R 5 is independently R 4or an aliphatic unsaturated group having 1 to 10 carbon atoms, each subscript m in each unit designated by subscript a is independently an integer from 0 to 3, and each subscript n in each unit designated by subscript b is an integer from 0 to 2, with the proviso that R 5 at least two of the M, D, T, and Q units are aliphatic unsaturated groups, each Z is independently H or an alkyl group, and a, b, c, d, and e are mole fractions such that a>0, b>0, c≧0, d≧0, 0≦e≦0.05, and a+b+c+d+e=1. Those skilled in the art will understand how such M, D, T, and Q units and their mole fractions affect the subscript f in the above average formula. T and Q units, denoted by subscripts c and d, respectively, are typically present in silicone resins, while D units, denoted by subscript b, are typically present in silicone polymers (and may be present in silicone resins).

[0019] Generally speaking, R 4 The hydrocarbyl groups suitable for R may independently be linear, branched, cyclic, or a combination thereof. 4 does not contain aliphatic unsaturation, i.e., each R 4is not an alkenyl or alkynyl group. Cyclic hydrocarbyl groups include aryl groups and saturated or non-conjugated cyclic groups. Cyclic hydrocarbyl groups may independently be monocyclic or polycyclic. An example of a combination of linear and cyclic hydrocarbyl groups is an aralkyl group. Typical examples of hydrocarbyl groups include alkyl groups, aryl groups, halocarbon groups, etc., as well as derivatives, variants, and combinations thereof. Examples of suitable alkyl groups include methyl, ethyl, propyl (e.g., isopropyl and / or n-propyl), butyl (e.g., isobutyl, n-butyl, tert-butyl, and / or sec-butyl), pentyl (e.g., isopentyl, neopentyl, and / or tert-pentyl), hexyl, hexadecyl, octadecyl, and branched saturated hydrocarbon groups having 6 to 18 carbon atoms. Examples of suitable non-conjugated cyclic groups include cyclobutyl, cyclohexyl, and cycloheptyl groups. Examples of suitable aryl groups include phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. Examples of suitable monovalent halogenated hydrocarbon groups (i.e., halocarbon groups or substituted hydrocarbon groups) include halogenated alkyl groups, aryl groups, and combinations thereof. Examples of halogenated alkyl groups include the above-mentioned alkyl groups in which one or more hydrogen atoms have been replaced with halogen atoms such as F or Cl. Illustrative examples of halogenated alkyl groups include fluoromethyl, 2-fluoropropyl, 3,3,3-trifluoropropyl, 4,4,4-trifluorobutyl, 4,4,4,3,3-pentafluorobutyl, 5,5,5,4,4,3,3-heptafluoropentyl, 6,6,6,5,5,4,4,3,3-nonafluorohexyl, and 8,8,8,7,7-pentafluorooctyl, 2,2-difluorocyclopropyl, 2,3-difluorocyclobutyl, 3,4-difluorocyclohexyl, and 3,4-difluoro-5-methylcycloheptyl, chloromethyl, chloropropyl, 2-dichlorocyclopropyl, and 2,3-dichlorocyclopentyl groups, and derivatives thereof.Examples of halogenated aryl groups include the above-mentioned aryl groups in which one or more hydrogen atoms have been replaced with a halogen atom, such as F or Cl. Specific examples of halogenated aryl groups include chlorobenzyl and fluorobenzyl groups. In certain embodiments, each R. 4 are independently an alkyl group having 1 to 10 carbon atoms, alternatively 1 to 8 carbon atoms, alternatively 1 to 6 carbon atoms, alternatively 1 to 4 carbon atoms, or alternatively 1 to 2 carbon atoms, or each R 4 is a methyl group.

[0020] Each R 5 are independent, R 4 or an aliphatically unsaturated group having 1 to 10 carbon atoms. Suitable examples of aliphatically unsaturated groups are described above. Each subscript m is independently an integer from 0 to 3 in each unit designated by the subscript a. The subscript a indicates an M siloxy unit, and thus each M siloxy unit is independently selected. For example, (A) organopolysiloxane may contain trimethylsiloxy units (i.e., subscript m is 0 and each R 4 is methyl), M units are dimethylvinylsiloxy units (i.e., when the subscript m is 1 and each R 4 is methyl and R 5 is vinyl), M units are methyldivinylsiloxy units (i.e., when the subscript m is 2 and R 4 is methyl, and each R 5 is vinyl), and / or trivinylsiloxy units as M units (i.e., when the subscript m is 3 and each R 5 is vinyl).

[0021] Similarly, in each unit designated by subscript b, each subscript n is an integer from 0 to 2. Subscript b denotes a D siloxy unit, and thus each D siloxy unit is independently selected. For example, (A) organopolysiloxane may contain dimethylsiloxy units (i.e., subscript n is 0 and each R 4is methyl), a phenylmethylsiloxy unit as the D unit (i.e., when the subscript n is 0 and one R 4 is methyl, and the other R 4 is phenyl), and the D units are methylvinylsiloxy units (i.e., when the subscript n is 1 and R 4 is methyl and R 5 is vinyl), and / or divinylsiloxy units as D units (i.e., when the subscript n is 2 and each R 5 is vinyl). Those skilled in the art will understand how each methyl group can be replaced with another hydrocarbyl group (optionally substituted), and how each vinyl group can be replaced with another aliphatically unsaturated group.

[0022] The subscript e indicates the SiOZ content of (A) organopolysiloxane. The SiOZ content can be SiOH (or silanol groups, where Z is H), or silicon-bonded alkoxy (Z is alkyl). In other words, each Z is independently H or an alkyl group. For example, "(SiO 4 / 2 )(ZO 1 / 2 )" refers to a Q3 type group in which the silicon atom is linked to the "Z" group through a single oxygen. In NMR nomenclature, such "(SiO 4 / 2 )(ZO 1 / 2 )" moieties are still considered Q siloxy units. When Z is an alkyl group, the alkyl group is typically a C1-C8, alternatively a C1-C6, alternatively a C1-C4, alternatively a C1-C2, or alternatively a C1 (i.e., methyl) alkyl group. In the (A) organopolysiloxane, 0≦e≦0.05, alternatively 0≦e≦0.04, alternatively 0≦e≦0.03, alternatively 0≦e≦0.02, alternatively 0≦e≦0.01, or alternatively e is 0. The subscript e is typically 0 when the (A) organopolysiloxane is linear or branched, but may be >0 when the (A) organopolysiloxane is resinous. Such SiOZ moieties are often inherently present in silicone resins prepared by silane hydrolysis and condensation.

[0023] In certain embodiments, the (A) organopolysiloxane is resinous. When the (A) organopolysiloxane is resinous, subscript c>0 and / or subscript d>0, such that the (A) organopolysiloxane contains at least some T and / or Q siloxy units, respectively. In one embodiment, c>0 and d>0. In another embodiment, c=0 and d>0. In yet another embodiment, c and d are each >0. In these embodiments, the (A) organopolysiloxane has a branched or three-dimensional network molecular structure. At 25°C, the (A) organopolysiloxane can be in liquid or solid form. Alternatively, the (A) organopolysiloxane can be exemplified by polyorganosiloxanes containing only T units, polyorganosiloxanes containing T units in combination with other siloxy units (e.g., M, D, and / or Q siloxy units), or polyorganosiloxanes containing Q units in combination with other siloxy units (i.e., M, D, and / or T siloxy units). Specific examples of resinous organopolysiloxanes suitable for the (A) organopolysiloxane include vinyl-terminated silsesquioxanes (i.e., T resins) and vinyl-terminated MDQ resins. Alternatively, the (A) organopolysiloxane can contain branched siloxanes, silsesquioxanes, or both branched siloxanes and silsesquioxanes.

[0024] When the (A) organopolysiloxane is branched, the (A) organopolysiloxane has the unit formula: (R 4 3-m R 5 m SiO 1 / 2 ) a (R 4 2-n R 5 n SiO 2 / 2 ) b (SiO 4 / 2 ) d (ZO 1 / 2 ) e、 wherein each R 4 are independently selected and defined above, and each R 5are independently selected and defined above, where subscript a is >0, subscript b is >0, subscript d is >0, and subscript e is ≦0.05. (A) The organopolysiloxane may comprise a single Q siloxy unit, or two or more Q siloxy units, which may optionally be clustered or bonded together.

[0025] When the (A) organopolysiloxane is branched, the (A) organopolysiloxane is represented by the formula (R 4 2SiO 2 / 2 ) m wherein each subscript m is independently 2 to 5,000. Alternatively, when the (A) organopolysiloxane is branched, the (A) organopolysiloxane may comprise at least two polydiorganosiloxane chains of the formula (R 4 2SiO 2 / 2 ) attached to four polydiorganosiloxane chains of the formula (SiO ) 4 / 2 ) may contain at least one unit.

[0026] However, the (A) organopolysiloxane typically does not contain such T and Q siloxy units. By "at least some," we mean that the (A) organopolysiloxane may contain up to 5 mol%, alternatively up to 4 mol%, alternatively up to 3 mol%, alternatively up to 2 mol%, alternatively up to 1 mol%, or even 0 mol% of T and Q siloxy units, based on all siloxy units present in the (A) organopolysiloxane. Typically, in view of the desired viscosity, the (A) organopolysiloxane is not a rubber or resin, but a flowable liquid at room temperature, including in the absence of a solvent or carrier vehicle. While a rubber or resin may be liquid at room temperature when dissolved or dispersed in a solvent or carrier fluid, such a solvent may be undesirable in certain end-use applications because the solvent typically volatilizes or is otherwise removed during the curing process.

[0027] In certain embodiments, (A) the organopolysiloxane is substantially linear. By substantially linear, it is meant that component (A) comprises, consists essentially of, or consists only of M and D siloxy units. As is readily understood in the art, M siloxy units are those having the formula (R 4 3-m R 5 m SiO 1 / 2 ) and the D siloxy units are of the formula (R 4 2-n R 5 n SiO 2 / 2 ) wherein the subscripts m and n, and R 4 and R 5 is defined above. Conventionally, the M and D siloxy nomenclature is utilized in conjunction with methyl substitution only. However, for purposes of this disclosure, in the above M and D siloxy units, each R 4 and R 5 is as defined above and need not be a methyl group. When the M siloxy unit contains at least one silicon-bonded aliphatic unsaturated group, the silicon-bonded aliphatic unsaturated group is terminal. When the D siloxy unit contains at least one silicon-bonded aliphatic unsaturated group, the silicon-bonded aliphatic unsaturated group is pendant.

[0028] In specific embodiments in which the (A) organopolysiloxane is substantially linear, the (A) organopolysiloxane is represented by the following average formula: (R 4 3-m R 5 m SiO 1 / 2 )2(R 4 2-n R 5 n SiO 2 / 2 ) y where the subscript y is an integer between 10 and 10,000, and R 4 , R 5and the subscripts m and n are independently selected and defined above. The value of the subscript y is from 10 to 10,000. In one embodiment, the subscript y is from 10 to 10,000, alternatively from 10 to 9,000, alternatively from 10 to 8,000, alternatively from 10 to 7,000, alternatively from 10 to 6,000, alternatively from 10 to 5,000, alternatively from 10 to 4,000, alternatively from 10 to 3,000, alternatively from 10 to 2,000, alternatively from 10 to 1,000, alternatively from 50 to 900. When the (A) organopolysiloxane is substantially linear, the value of the subscript y may be referred to as the degree of polymerization (DP) of the (A) organopolysiloxane.

[0029] (A) The organopolysiloxane may be substantially linear, or if linear, the at least two aliphatically unsaturated groups may be bonded to the silicon atom at pendant positions, terminal positions, or both pendant and terminal positions.

[0030] In one embodiment, when the (A) organopolysiloxane is substantially linear, the (A) organopolysiloxane has the average formula: (R 4 2nd Round 5 SiO 1 / 2 )2(R 4 2SiO 2 / 2 ) y. where each subscript m is 1 and each subscript n is 0. For example, as a specific example of an (A) organopolysiloxane having an average of at least two silicon-bonded aliphatic unsaturated groups per molecule, the (A) organopolysiloxane may have the average formula Vi(CH3)2SiO[(CH3)2SiO] y Si(CH)Vi, where the subscripts y and Vi are defined above. With respect to this average formula, any methyl group may be replaced with a different monovalent hydrocarbon group, and any vinyl group may be replaced with any terminal aliphatically unsaturated monovalent hydrocarbon group.

[0031] As a specific example of the (A) organopolysiloxane having pendant silicon-bonded aliphatic unsaturated groups, the (A) organopolysiloxane can have the following average unit formula: [(CH3)3SiO 1 / 2 ]2[(CH3)2SiO 2 / 2 ] cc [(CH3)ViSiO 2 / 2 ] bb , where the subscript bb is 2 to 20, alternatively 2 to 10, the subscript cc is 8 to 9,980, and Vi represents a vinyl group. With respect to this average formula, any methyl group may be replaced with a different monovalent hydrocarbon group (such as an alkyl or aryl), and any vinyl group may be replaced with a different aliphatically unsaturated monovalent hydrocarbon group (such as an allyl or hexenyl).

[0032] Since the at least two silicon-bonded aliphatic unsaturated groups can be both pendant and terminal, the (A) organopolysiloxane can alternatively have the following average unit formula: [Vi(CH3)2SiO 1 / 2 ]2[(CH3)2SiO 2 / 2 ] cc [(CH3)ViSiO 2 / 2 ] bb , or [Vi(CH3)2SiO 1 / 2 ][(CH3)3SiO 1 / 2 ][(CH3)2SiO 2 / 2 ] cc [(CH3)ViSiO 2 / 2 ] bb、 where the subscripts bb and cc and Vi are defined above.

[0033] When the organopolysiloxane (A) is a substantially linear polyorganosiloxane, the organopolysiloxane (A) may be selected from the group consisting of dimethylpolysiloxanes capped at both molecular ends with dimethylvinylsiloxy groups, methylphenylpolysiloxanes capped at both molecular ends with dimethylvinylsiloxy groups, copolymers of methylphenylsiloxanes and dimethylsiloxanes capped at both molecular ends with dimethylvinylsiloxy groups, copolymers of methylvinylsiloxanes and methylphenylsiloxanes capped at both molecular ends with dimethylvinylsiloxy groups, and methylvinylsiloxanes capped at both molecular ends with dimethylvinylsiloxy groups. copolymers of methylvinylsiloxane, methylphenylsiloxane, and dimethylsiloxane, both of which are end-capped with dimethylvinylsiloxy groups; copolymers of methylvinylsiloxane and methylphenylsiloxane, both of which are end-capped with trimethylsiloxy groups; copolymers of methylvinylsiloxane and diphenylsiloxane, both of which are end-capped with trimethylsiloxy groups; and copolymers of methylvinylsiloxane, methylphenylsiloxane, and dimethylsiloxane, both of which are end-capped with trimethylsiloxy groups.

[0034] Alternatively, (A) the organopolysiloxane may comprise a substantially linear, or linear, polyorganosiloxane selected from the group consisting of: i) dimethylvinylsiloxy-terminated polydimethylsiloxane; ii) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane); iii) dimethylvinylsiloxy-terminated polymethylvinylsiloxane; iv) trimethylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane); v) trimethylsiloxy-terminated polymethylvinylsiloxane; vi) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylvinylsiloxane), vii) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylphenylsiloxane); viii) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / diphenylsiloxane); ix) phenyl, methyl, vinyl-siloxy terminated polydimethylsiloxanes; x) dimethylhexenylsiloxy-terminated polydimethylsiloxane, xi) dimethylhexenylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane); xii) dimethylhexenylsiloxy-terminated polymethylhexenylsiloxane; xiii) trimethylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane); xiv) trimethylsiloxy-terminated polymethylhexenylsiloxane; xv) dimethylhexenylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane), xvi) dimethylvinylsiloxy-terminated poly(dimethylsiloxane / methylhexenylsiloxane), xvii) dimethylvinylsiloxy-terminated polymethylphenylsiloxanes; xviii) dimethylvinylsiloxy-terminated polydimethylsiloxane / methylphenylsiloxane, and xix) Combinations of these.

[0035] (A) The organopolysiloxane may comprise a combination of polyorganosiloxanes or two or more different polyorganosiloxanes that differ in at least one property, such as structure, molecular weight, degree of polymerization, monovalent groups bonded to silicon atoms, and / or content of aliphatic unsaturated groups.

[0036] For example, in one embodiment, the organopolysiloxane (A) may include a first organopolysiloxane (A1) and a second organopolysiloxane (A2). The first organopolysiloxane (A1) and the second organopolysiloxane (A2) are different from each other. In one embodiment, the first organopolysiloxane (A1) is linear, and the second organopolysiloxane (A2) is not linear. In another embodiment, both the first organopolysiloxane (A1) and the second organopolysiloxane (A2) are linear.

[0037] Generally, the (A1) first organopolysiloxane and the (A2) second organopolysiloxane each have an average of at least two silicon-bonded aliphatic unsaturated groups per molecule. In some embodiments, the (A1) first organopolysiloxane and the (A2) second organopolysiloxane have the same general formula, but differ only in terms of their degree of polymerization. The (A1) first organopolysiloxane and the (A2) second organopolysiloxane may each independently be linear, substantially linear, branched, substantially branched, resinous, or substantially resinous.

[0038] In embodiments in which the (A1) first organopolysiloxane is linear, the (A1) first organopolysiloxane may have a degree of polymerization from 10 to 10,000, alternatively from 10 to 9000, alternatively from 10 to 8,000, alternatively from 10 to 7,000, alternatively from 10 to 6000, alternatively from 10 to 5,000, alternatively from 10 to 4,000, alternatively from 10 to 3,000, alternatively from 10 to 2,000, alternatively from 250 to 1,500, alternatively from 500 to 1,000, alternatively from 600 to 900, alternatively from 700 to 800. In these or other embodiments, when the (A2) second organopolysiloxane is linear, the (A2) second organopolysiloxane has a degree of polymerization from 10 to 10,000, alternatively from 10 to 7,500, alternatively from 10 to 5,000, alternatively from 10 to 2,500, alternatively from 10 to 1,000, alternatively from 10 to 750, alternatively from 50 to 500, alternatively from 50 to 300, alternatively from 100 to 200.

[0039] The (A1) first organopolysiloxane and the (A2) second organopolysiloxane can independently have terminal and / or pendant silicon-bonded aliphatic unsaturated groups. In some embodiments, the (A1) first organopolysiloxane and the (A2) second organopolysiloxane do not have pendant silicon-bonded aliphatic unsaturated groups.

[0040] When the organopolysiloxane (A) comprises a first organopolysiloxane (A1) and a second organopolysiloxane (A2), the weight ratio of the first organopolysiloxane (A1) to the second organopolysiloxane (A2) is not limited. In some embodiments, the weight ratio of the (A1) first organopolysiloxane to the (A2) second organopolysiloxane is from 100:1 to 1:100, alternatively from 50:1 to 1:50, alternatively from 25:1 to 1:25, alternatively from 10:1 to 1:10, alternatively from 5:1 to 1:5, alternatively from 3:1 to 1:3, alternatively from 2:1 to 1:2, alternatively from 1.5:1 to 1:1.5, alternatively from 1.2:1 to 1:1.2, alternatively from 1.1:1 to 1:1.1, alternatively from 1.15:1 to 1:1.15. In certain embodiments in which the (A) organopolysiloxane comprises an (A1) first organopolysiloxane and an (A2) second organopolysiloxane, the (A1) first organopolysiloxane is present in the composition in an amount of 1 to 89 wt%, alternatively 10 to 80 wt%, alternatively 20 to 60 wt%, alternatively 20 to 40 wt%, alternatively 25 to 35 wt%, alternatively 28 to 32 wt%, based on the total weight of the composition. In these or other embodiments, the (A2) second organopolysiloxane is present in the composition in an amount of 1 to 89 wt%, alternatively 10 to 80 wt%, alternatively 20 to 60 wt%, alternatively 20 to 40 wt%, alternatively 25 to 35 wt%, alternatively 30 to 35 wt%, based on the total weight of the composition.

[0041] (A) Regardless of the selection of the organopolysiloxane, the (A) organopolysiloxane is typically present in the composition in an amount of 5 to 95, or 10 to 90, or 20 to 90, or 30 to 90, or 50 to 90% by weight, based on the total weight of the composition. In certain embodiments, the (A) organopolysiloxane is present in the composition in an amount of 10 to 80, or 20 to 70, or 20 to 80, or 30 to 70, or 40 to 70, or 50 to 70, or 55 to 65% by weight, based on the total weight of the composition.

[0042] The composition further comprises a (B) organopolysiloxane that does not contain an aliphatic unsaturated group and has an average of at least two mercapto groups per molecule.

[0043] (B) The organopolysiloxane is not limited and can be any organopolysiloxane that contains an average of at least two mercapto groups per molecule. For example, the (B) organopolysiloxane may be linear, branched, partially branched, hyperbranched, cyclic, dendritic, resinous (i.e., having a three-dimensional network), or may contain a combination of different structures. At least two mercapto groups of component (B) are reactive with the silicon-bonded aliphatic unsaturated groups of component (A). References herein to mercapto groups include any group having mercapto functionality. For example, references to mercapto groups include references to mercaptoalkyl groups and not just -SH groups.

[0044] In certain embodiments, the (B) organopolysiloxane has the following average formula. R’ q’’ SiO (4-q’’) / 2 In the formula, each R’ is an independently selected substituted or unsubstituted hydrocarbyl group that does not contain aliphatic unsaturation, provided that in each molecule, on average, at least two R’ groups are independently selected mercapto-functional groups, and q’’ is selected such that 0 < q’’ ≦ 3.2.

[0045] In some embodiments, the (B) organopolysiloxane is represented by the following average formula: (R 4 3-o R 6 o SiO 1 / 2 ) f (R 4 2-p R 6 p SiO 2 / 2 ) g (R 6 SiO 3 / 2 ) h (SiO 4 / 2 ) i (ZO 1 / 2 ) j In the formula, each R 4 are independently selected substituted or unsubstituted hydrocarbyl groups free of aliphatic unsaturation, and each R 6 is independently R 4 or contains a mercapto group, wherein the subscript o is independently an integer from 0 to 3 in each unit denoted by the subscript f, and each p is independently an integer from 0 to 2 in each unit denoted by the subscript f, with the proviso that R 6 at least two of independently comprise a mercapto group, and each Z is independently H or an alkyl group, where f, g, h, i, and j are mole fractions that satisfy f>0, g>0, h≧0, i≧0, 0≦j≦0.05, and f+g+h+i+j=1.

[0046] R 4 Suitable examples of are described above for component (A).

[0047] Each R 6 is independently R 4 or contains a mercapto group. 6 Each mercapto group in R may be any group containing a mercapto (SH) functionality. 6 each mercapto group independently represents a group of formula -X 1 -SH, wherein X 1 is a divalent hydrocarbon group. In these embodiments, X 1is present between the silicon atom of component (B) and the sulfur atom of the mercapto group. Typically, X 1 is R 6 In these embodiments, each mercapto group in R is selected to be a mercaptoalkyl group. 6 Each mercapto group is (CH2) t SH, where the subscript t is independently 1 to 10, alternatively 1 to 9, alternatively 1 to 8, alternatively 1 to 7, alternatively 2 to 6. Examples of divalent hydrocarbon groups when the subscript t is 1 to 8 include alkylene groups having 1 to 8 carbon atoms, such as methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, and octylene. Those skilled in the art will recognize that X 1 The corresponding mercapto group is understood based on the selection of . For example, if the subscript t is 3, the corresponding mercapto group is a 3-mercaptopropyl group; if the subscript t is 4, the corresponding mercapto group is a 4-mercaptobutyl group; and if the subscript t is 6, the corresponding mercapto group is a 6-mercaptohexyl group. Each mercapto group does not have to be a primary mercapto group. For example, each mercapto group can independently be primary, secondary, or tertiary. In certain embodiments, each mercapto group is primary.

[0048] Each subscript o is independently an integer from 0 to 3 in each unit designated by subscript f. Subscript f denotes an M siloxy unit, and thus each M siloxy unit is independently selected. For example, (B) organopolysiloxane may contain trimethylsiloxy units (i.e., subscript o is 0 and each R 4 is methyl), M units are dimethylmercaptosiloxy units (i.e., the subscript o is 1 and each R 4 is methyl, and each R 6 is a mercapto group), M units are methyldimercaptosiloxy units (i.e., when the subscript o is 2 and each R 4 is methyl, and each R 6is a mercapto group), and / or trimercaptosiloxy units as M units (i.e., when the subscript o is 3 and each R 6 is a mercapto group).

[0049] Similarly, in each unit designated by subscript g, each subscript p is an integer from 0 to 2. Subscript p indicates a D siloxy unit, and thus each D siloxy unit is independently selected. For example, (B) organopolysiloxane may contain dimethylsiloxy units (i.e., subscript p is 0 and each R 4 is methyl), and the D unit is a methylmercaptosiloxy unit (i.e., when the subscript p is 1 and R 4 is methyl and R 6 is a mercapto group), and / or dimercaptosiloxy units as D units (i.e., when the subscript p is 2 and each R 6 is a mercapto group). Those skilled in the art will understand how each methyl group can be replaced with another hydrocarbyl group (optionally substituted), and how each mercapto group can be replaced with another mercapto group.

[0050] The subscript j indicates the SiOZ content of (B) organopolysiloxane. The SiOZ content can be SiOH (where Z is H or a silanol group) or silicon-bonded alkoxy (where Z is alkyl). In other words, each Z is independently H or an alkyl group. For example, "(SiO 4 / 2 )(ZO 1 / 2 )" refers to a Q-type group with a silicon atom attached to a "Z" group through a single oxygen. In NMR nomenclature, such "(SiO 4 / 2 )(ZO 1 / 2)" moieties are still considered Q siloxy units. When Z is an alkyl group, the alkyl group is typically a C1-C8, alternatively a C1-C6, alternatively a C1-C4, alternatively a C1-C2, or alternatively a C1 (i.e., methyl) alkyl group. In the (B) organopolysiloxane, 0≦j≦0.05, alternatively 0≦j≦0.04, alternatively 0≦j≦0.03, alternatively 0≦j≦0.02, alternatively 0≦j≦0.01, or alternatively j is 0. The subscript j is typically 0 when the (B) organopolysiloxane is linear or branched, but may be >0 when the (B) organopolysiloxane is resinous. Such SiOZ moieties are often inherently present in silicone resins prepared by silane hydrolysis and condensation.

[0051] In certain embodiments, the (B) organopolysiloxane is resinous. When the (B) organopolysiloxane is resinous, subscript h>0 and / or subscript i>0, such that the (B) organopolysiloxane contains at least some T and / or Q siloxy units, respectively. In one embodiment, h>0 and i>0. In another embodiment, h=0 and i>0. In yet other embodiments, h and i are each >0. In these embodiments, the (B) organopolysiloxane has a branched or three-dimensional network molecular structure. At 25°C, the (B) organopolysiloxane can be in liquid or solid form. Alternatively, the (B) organopolysiloxane can be exemplified by a polyorganosiloxane containing only T units, a polyorganosiloxane containing T units in combination with other siloxy units (e.g., M, D, and / or Q siloxy units), or a polyorganosiloxane containing Q units in combination with other siloxy units (i.e., M, D, and / or T siloxy units). Specific examples of resinous organopolysiloxanes suitable for the (B) organopolysiloxane include mercapto-terminated silsesquioxanes (i.e., T resins) and mercapto-terminated MDQ resins. Alternatively, the (B) organopolysiloxane can contain branched siloxanes, silsesquioxanes, or both branched siloxanes and silsesquioxanes.

[0052] However, the (B) organopolysiloxane typically does not contain such T and Q siloxy units. By "at least some," we mean that the (B) organopolysiloxane may contain up to 5 mol%, alternatively up to 4 mol%, alternatively up to 3 mol%, alternatively up to 2 mol%, alternatively up to 1 mol%, or even 0 mol% of T and Q siloxy units, based on all siloxy units present in the (B) organopolysiloxane. Typically, in view of the desired viscosity, the (B) organopolysiloxane is not a rubber or resin, but a flowable liquid at room temperature, including in the absence of a solvent or carrier vehicle. While a rubber or resin may be liquid at room temperature when dissolved or dispersed in a solvent or carrier fluid, such a solvent may be undesirable in certain end-use applications because the solvent typically volatilizes or is otherwise removed during the curing process.

[0053] In certain embodiments, the (B) organopolysiloxane is substantially linear. By substantially linear, it is meant that component (B) comprises, consists essentially of, or consists only of M and D siloxy units. As is readily understood in the art, M siloxy units are those having the formula (R 4 3-o R 6 o SiO 1 / 2 ) and the D siloxy units are of the formula (R 4 2-p R 6 p SiO 2 / 2 ) wherein the subscripts o and p and R 4 and R 6 is defined above. Conventionally, the M and D siloxy nomenclature is utilized in conjunction with methyl substitution only. However, for purposes of this disclosure, in the above M and D siloxy units, each R 4 and R 6is as defined above and need not be a methyl group. When the M siloxy unit contains at least one mercapto group, the mercapto group is terminal. When the D siloxy unit contains at least one mercapto group, the mercapto group is pendant.

[0054] In certain embodiments where the (B) organopolysiloxane is substantially linear, the (B) organopolysiloxane is represented by the following average formula: (R 4 3-o R 6 o SiO 1 / 2 )2(R 4 2-p R 6 p SiO 2 / 2 ) z where the subscript z is an integer between 10 and 10,000, and R 4 , R 6 and the subscripts o and p are independently selected and defined above. The value of subscript z is from 10 to 10,000. In one embodiment, subscript z is from 10 to 10,000, alternatively from 10 to 9,000, alternatively from 10 to 8,000, alternatively from 10 to 7,000, alternatively from 10 to 6,000, alternatively from 10 to 5,000, alternatively from 10 to 4,000, alternatively from 10 to 3,000, alternatively from 10 to 2,000, alternatively from 10 to 1,000, alternatively from 10 to 500, alternatively from 10 to 250, alternatively from 10 to 100, alternatively from 20 to 80, alternatively from 30 to 60. When the (B) organopolysiloxane is substantially linear, the value of subscript z may be referred to as the degree of polymerization (DP) of the (B) organopolysiloxane.

[0055] (B) If the organopolysiloxane is substantially linear, or if linear, the at least two mercapto groups may be located at pendant positions, terminal positions, or both pendant and terminal positions.

[0056] In one embodiment, when the (B) organopolysiloxane is substantially linear and has pendant mercapto groups, the subscript o is 0 and the (B) organopolysiloxane has the average unit formula: (R 4 3SiO 1 / 2 )2(R 4 R 6 SiO 2 / 2 ) z’ (R 4 2SiO 2 / 2 ) z’’ In the formula, z' is an integer from 2 to 100, and the subscript z'' is an integer from 8 to 9998, with the proviso that 10≦z'+z''≦10,000. Typically, z' is 2 to 80, alternatively 2 to 60, alternatively 2 to 40, alternatively 2 to 20, or alternatively 2 to 10, and z'' is 8 to 9,000, alternatively 8 to 7,000, alternatively 8 to 5,000, alternatively 8 to 3,000, alternatively 8 to 1,000, alternatively 10 to 500, or alternatively 10 to 100. For example, as a specific example of (A) organopolysiloxane having pendant mercapto groups, (B) organopolysiloxane may have the following average formula: [(CH3)3SiO 1 / 2 ]2[(CH3)R 6 SiO 2 / 2 ] z’ [(CH3)2SiO 2 / 2 ] z’’。

[0057] With respect to this average formula, any methyl group may be replaced with a different monovalent hydrocarbon group (such as alkyl or aryl).

[0058] Alternatively, as a specific example of the organopolysiloxane (B) having at least two mercapto groups at terminal positions per molecule on average, the organopolysiloxane (B) is an organopolysiloxane having an average formula R 6 (CH3)2SiO[(CH3)2SiO] z Si(CH3)2R 6 where the subscripts z and R 6is defined above. With respect to this average formula, any methyl group may be replaced with a different monovalent hydrocarbon group.

[0059] Since the at least two mercapto groups may be both pendant and terminal groups, (B) the organopolysiloxane may alternatively have an average unit formula: [R 6 (CH3)2SiO 1 / 2 ]2[(CH3)R 6 SiO 2 / 2 ] z’ [(CH3)2SiO 2 / 2 ] z’’、 or [R 6 (CH3)2SiO 1 / 2 ][(CH3)3SiO 1 / 2 ][(CH3R 6 SiO 2 / 2 ] z’ [(CH3)2SiO 2 / 2 ] z’’。

[0060] When the organopolysiloxane (B) is a substantially linear polyorganosiloxane, the organopolysiloxane (B) may be selected from the group consisting of dimethylpolysiloxanes capped at both molecular ends with dimethylmercaptosiloxy groups, methylphenylpolysiloxanes capped at both molecular ends with dimethylmercaptosiloxy groups, copolymers of methylphenylsiloxanes capped at both molecular ends with dimethylmercaptosiloxy groups and dimethylsiloxanes, copolymers of methylmercaptosiloxanes capped at both molecular ends with dimethylmercaptosiloxy groups and methylphenylsiloxanes, copolymers of methylmercaptosiloxanes capped at both molecular ends with dimethylmercaptosiloxy groups and di ... Examples include copolymers of methylmercaptosiloxane, methylphenylsiloxane, and dimethylsiloxane end-capped with dimethylmercaptosiloxy groups, copolymers of methylmercaptosiloxane and methylphenylsiloxane end-capped with trimethylsiloxy groups at both molecular ends, copolymers of methylmercaptosiloxane and diphenylsiloxane end-capped with trimethylsiloxy groups at both molecular ends, copolymers of dimethylsiloxane and methylmercaptosiloxane end-capped with trimethylsiloxy groups at both molecular ends, and copolymers of methylmercaptosiloxane, methylphenylsiloxane, and dimethylsiloxane end-capped with trimethylsiloxy groups at both molecular ends.

[0061] Alternatively, (B) the organopolysiloxane may comprise a substantially linear or linear polyorganosiloxane selected from the group consisting of: i) dimethylmercaptosiloxy-terminated polydimethylsiloxane; ii) dimethylmercaptosiloxy-terminated poly(dimethylsiloxane / methylmercaptosiloxane); iii) dimethylmercaptosiloxy-terminated polymethylmercaptosiloxane; iv) trimethylsiloxy-terminated poly(dimethylsiloxane / methylmercaptosiloxane); v) trimethylsiloxy-terminated polymethylmercaptosiloxane; vi) dimethylmercaptosiloxy-terminated poly(dimethylsiloxane / methylmercaptosiloxane); vii) dimethylmercaptosiloxy-terminated poly(dimethylsiloxane / methylphenylsiloxane); viii) dimethylmercaptosiloxy-terminated poly(dimethylsiloxane / diphenylsiloxane); ix) phenyl, methyl, mercaptosiloxy terminated polydimethylsiloxanes, and (x) Combinations of these.

[0062] (B) The organopolysiloxane may comprise a combination of polyorganosiloxanes or two or more different polyorganosiloxanes that differ in at least one property, such as structure, molecular weight, degree of polymerization, monovalent groups bonded to silicon atoms, and / or content of aliphatic unsaturated groups.

[0063] In some embodiments, (B) the organopolysiloxane is present in the composition in an amount from 0.5 to 40, alternatively from 0.5 to 30, alternatively from 0.5 to 20, alternatively from 1 to 15, alternatively from 5 to 15, alternatively from 7 to 12 weight percent, based on the total weight of the composition.

[0064] In these or other embodiments, the amount of component (B) is selected so that the weight ratio of (A) organopolysiloxane to (B) organopolysiloxane is from 100:1 to 1:100, alternatively from 50:1 to 1:50, alternatively from 25:1 to 1:25, alternatively from 15:1 to 1:15, alternatively from 15:1 to 1:1, alternatively from 12:1 to 3:1 (wt / wt (A):(B)).

[0065] The composition further comprises (C) a photoinitiator. The (C) photoinitiator is selected to enhance cure of the composition upon exposure to radiation. The (C) photoinitiator can be selected from any known free radical photoinitiator effective in promoting the crosslinking reaction between mercapto (or thiol) groups and aliphatic unsaturated groups. Such crosslinking is commonly referred to as "thiol-ene" cure. Examples of component (C) include diethoxyacetophenone (DEAP), benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, diethoxyxanthone, chlorothioxanthone, azobisisobutyronitrile, N-methyldiethanolamine benzophenone, 4,4'-bis(dimethylamino)benzophenone, diethoxyacetophenone, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxycyclohexyl-phenyl-ketone, Examples of suitable photoinitiators include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphinate, and combinations thereof. In certain embodiments, the (C) photoinitiator includes or is 2-hydroxy-2-methylpropiophenone.

[0066] The (C) photoinitiator is present in the composition in a catalytically effective amount to cure the composition, which can be readily determined by one of ordinary skill in the art. In some embodiments, the (C) photoinitiator is present in the composition in an amount of 0.001 to 20 wt %, alternatively 0.01 to 10 wt %, alternatively 0.01 to 8 wt %, alternatively 0.01 to 5 wt %, alternatively 0.1 to 3 wt %, alternatively 0.5 to 1.5 wt %, alternatively 0.9 to 1 wt %, based on the total weight of the composition.

[0067] The composition further comprises (D) an acryloxy-functional silane. The acryloxy-functional silane of component (D) is represented by the formula:

[0068] [ka] wherein X is a divalent hydrocarbon group, each R is independently a hydrocarbyl group, and each R 1 are independently alkyl groups having 1 to 8 carbon atoms, the subscript x is 2 or 3, and R 2 is H or R 1 is.

[0069] In certain embodiments, X is —(CH) t -, where the subscript t is 1 to 10, alternatively 1 to 9, alternatively 1 to 8, alternatively 1 to 7, alternatively 2 to 6. Examples of divalent hydrocarbon groups X when the subscript t is 1 to 8 include alkylene groups having 1 to 8 carbon atoms, such as methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, and octylene.

[0070] Suitable hydrocarbyl groups for R are R 4 Each R 1 are independently an alkyl group having 1 to 8, alternatively 1 to 7, alternatively 1 to 6, alternatively 1 to 5, alternatively 1 to 4, alternatively 1 to 3, alternatively 1 or 2, or alternatively 1 carbon atom. 1 are independent, so that component (D) can contain different silicon-bonded alkoxy groups, i.e., component (D) can contain trimethoxysilyl moieties, trimethoxyethoxysilyl moieties, methoxydiethoxysilyl moieties, triethoxysilyl moieties, methoxyethoxypropoxysilyl moieties, etc. In one embodiment, each R 1 is the same.

[0071] R 2 is H or R 1 R 2When R is H, component (D) contains acrylate functionality. 2 When is methyl, component (D) contains methacrylate functionality.

[0072] The subscript x is 2 or 3. When the subscript x is 2, component (D) has the formula:

[0073] [ka]

[0074] When the subscript x is 3, component (D) has the formula:

[0075] [ka]

[0076] In certain embodiments, R 2 is methyl, X is propylene, the subscript x is 3, and each R 1 is methyl, and therefore component (D) comprises, consists essentially of, or consists of 3-methacryloxypropyltrimethoxysilane. Other specific examples of component (D) include acryloxypropyltrimethoxysilane, acryloxypropyldimethoxymethylsilane, methacryloxybutyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropyldiethoxyethylsilane, methacryloxypropyldimethoxyethoxysilane, acryloxybutyltriethoxysilane, and the like.

[0077] (D) The acryloxy-functional silane is present in the composition in an amount of from greater than 0 to 10 wt%, alternatively from 0.01 to 10 wt%, alternatively from 0.01 to 7 wt%, alternatively from 0.05 to 5 wt%, alternatively from 0.1 to 3 wt%, alternatively from 0.1 to 2 wt%, based on the total weight of the composition.

[0078] The composition may further comprise a compound of the formula Si(OR 3) 4, wherein each R 3 are independently alkyl groups having 1 to 10 carbon atoms.

[0079] Each R 3 are independently an alkyl group having 1 to 10, alternatively 1 to 9, alternatively 1 to 8, alternatively 1 to 7, alternatively 1 to 6, alternatively 1 to 5, alternatively 1 to 4, alternatively 1 to 3, alternatively 1 or 2, or alternatively 1 carbon atom. 3 are independent, so that component (E) may contain different silicon-bonded alkoxy groups. In one embodiment, each R 3 is the same.

[0080] In certain embodiments, the tetraorthosilicate of component (E) includes or is tetraethyl orthosilicate (TEOS) and / or tetrapropyl orthosilicate (TPOS). Other examples of suitable tetraorthosilicates for component (E) include dimethoxydiethoxysilane, trimethoxyethoxysilane, tetramethoxysilane, tetrabutoxysilane, methoxydiethoxybutoxysilane, dipropoxydibutoxysilane, and the like.

[0081] (E) The tetraorthosilicate is present in the composition in an amount from 0.01 to 20 wt%, alternatively from 0.01 to 10 wt%, alternatively from 0.01 to 7.5 wt%, alternatively from 0.5 to 5 wt%, alternatively from 0.1 to 3 wt%, alternatively from 0.5 to 2.5 wt%, based on the total weight of the composition.

[0082] The total molar ratio of mercapto groups in component (B) to silicon-bonded aliphatic unsaturated groups in components (A) and (D) varies based on the selection of the (A) organopolysiloxane, (B) organopolysiloxane, and (D) acryloxy-functional silane in the composition. In certain embodiments, the total molar ratio of mercapto groups in component (B) to silicon-bonded aliphatic unsaturated groups in components (A) and (D) is from 10:1 to 1:10, alternatively from 0.1:1 to 5:1, alternatively from 0.1:1 to 3:1, alternatively from 0.3:1 to 2:1 (mercapto groups in (B) to silicon-bonded aliphatic unsaturated groups in (A) and (D)).

[0083] The composition may further comprise (F) a filler. The (F) filler may be, for example, but not limited to, a reinforcing filler, an extending filler, a thermally conductive filler, an electrically conductive filler, a flame retardant filler, a heat stable filler, an acid-accepting filler, a rheology-modifying filler, a phosphor, a coloring filler, a mineral filler, a glass filler, a carbon filler, or a combination thereof. The selection of the (F) filler is typically a function of the cured product to be formed, depending on the composition and end-use application of the cured product.

[0084] The (F) filler may be untreated, pretreated, or added in combination with any filler treating agent described below, which, when so added, may treat the (F) filler in situ or prior to incorporation of the (F) filler into the composition. The (F) filler may be a single filler or a combination of two or more fillers that differ in at least one property, such as filler type, preparation method, treatment or surface chemistry, filler composition, filler shape, filler surface area, average particle size, and / or particle size distribution.

[0085] The shape and size of the (F) filler and / or (I) pigment are also not particularly limited. For example, the (F) filler can be spherical, oblong, oval, or irregular, and can be in the form of, for example, powder, dust, fiber, flake, chip, shavings, strand, scrim, wafer, wool, straw, particles, and combinations thereof. The size and shape are typically selected based on the type of (F) filler utilized, the selection of other ingredients included in the composition, and the end-use application of the cured product formed therefrom.

[0086] Non-limiting examples of fillers that can function as reinforcing fillers include reinforcing silica fillers such as fumed silica, silica aerogel, silica xerogel, and precipitated silica. Fumed silica is known in the art, for example, fumed silica is commercially available fumed silica sold under the name CAB-O-SIL by Cabot Corporation (Massachusetts, USA).

[0087] Non-limiting examples of fillers that may function as extending or reinforcing fillers include quartz and / or crushed quartz, aluminum oxide, magnesium oxide, silica (e.g., fumed silica, ground silica, precipitated silica), hydrated magnesium silicate, magnesium carbonate, dolomite, silicone resin, wollastonite, soapstone, kaolinite, kaolin, mica, muscovite, phlogopite, halloysite (hydrated alumina silicate), aluminum silicate, sodium aluminosilicate, glass (e.g., wind turbine), and the like. Fibers, beads or particles, including recycled glass from bottles or other sources), clay, magnetite, hematite, calcium carbonate, e.g., precipitated calcium carbonate, fumed calcium carbonate, and / or ground calcium carbonate, calcium sulfate, barium sulfate, calcium metasilicate, zinc oxide, talc, diatomaceous earth, iron oxide, clay, mica, chalk, titanium dioxide (titania), zirconia, sand, carbon black, graphite, anthracite, coal, lignite, charcoal, activated carbon, non-functional silicone resins, alumina, silver, metal powders, magnesium oxide, magnesium hydroxide, magnesium oxysulfate fiber, aluminum trihydrate, aluminum oxide, coated fillers, carbon fiber (including, for example, recycled carbon fiber from the aircraft and / or automotive industries), polyaramids such as chopped KEVLAR™ or Twaron™, nylon fiber, mineral fillers or pigments (e.g., titanium dioxide, non-hydrated, partially hydrated, or hydrated fluorides, chlorides, bromides, iodides, chromates, carbonates, hydroxides, phosphates, hydrogen phosphates, nitrates, oxides, and sulfates of sodium, potassium, magnesium, calcium, and barium; zinc oxide, antimony pentoxide, antimony trioxide, beryllium oxide, chromium oxide, cerium oxide, lithopone, boric acid or borates, such as zinc borate, barium metaborate, or aluminum borate, mixed metal oxides, such as vermiculite, bentonite, pumice, perlite, fly ash, clay, and silica gel;Examples of suitable fillers include rice husk ash, ceramics and zeolites, metals such as aluminum flakes or powders, bronze powders, copper, gold, molybdenum, nickel, silver powders or flakes, stainless steel powders, tungsten, barium titanate, silica-carbon black composites, functionalized carbon nanotubes, cement, slate powders, pyrophyllite, sepiolite, zinc stannate, zinc sulfide, and combinations thereof. Alternatively, the extending or reinforcing filler may be selected from the group consisting of calcium carbonate, talc, and combinations thereof.

[0088] As is known in the art, certain fillers can act as pigments. For example, white pigments can include metal oxides such as titanium oxide, aluminum oxide, zinc oxide, zirconium oxide, magnesium oxide, etc.; hollow fillers such as glass balloons and glass beads; and additionally, barium sulfate, zinc sulfate, barium titanate, aluminum nitride, boron nitride, and antimony oxide. Such components can be considered as fillers and / or pigments.

[0089] Extending fillers are known in the art and are commercially available, such as crushed silica sold under the name MIN-U-SIL by US Silica (Berkeley Springs, WV). Suitable precipitated calcium carbonates include Solvay's Winnofil™ SPM, and SMI's Ultra-pflex™ and Ultra-pflex™ 100.

[0090] When the (F) filler includes a thermally conductive filler, the (F) filler may be both thermally conductive and electrically conductive. Alternatively, the (F) filler may be thermally conductive and electrically insulating. The thermally conductive filler may also have other beneficial properties, such as, but not limited to, reinforcing filler, extending filler, or another property as described above. The thermally conductive filler may be selected from the group consisting of, but not limited to, aluminum nitride, aluminum oxide, aluminum trihydrate, aluminum oxyhydrate, barium titanate, barium sulfate, beryllium oxide, carbon fiber, diamond, graphite, magnesium hydroxide, magnesium oxide, magnesium oxysulfate fiber, metal particles, onyx, silicon carbide, tungsten carbide, zinc oxide, coated fillers, and combinations thereof.

[0091] (F) When the filler includes a thermally conductive filler, the thermally conductive filler may include a metal filler, an inorganic filler, a meltable filler, or a combination thereof. Metal fillers include metal particles, metal powders, and metal particles having a layer on their surface. These layers may be, for example, a metal nitride layer or a metal oxide layer. Suitable metal fillers are exemplified by particles of a metal selected from the group consisting of aluminum, copper, gold, nickel, silver, and combinations thereof, alternatively aluminum. Suitable metal fillers are further exemplified by particles of the above-listed metals having a layer on their surface selected from the group consisting of aluminum nitride, aluminum oxide, copper oxide, nickel oxide, silver oxide, and combinations thereof. For example, the metal filler may include aluminum particles having an aluminum oxide layer on their surface. Inorganic fillers are exemplified by onyx; aluminum trihydrate, aluminum oxyhydrate; metal oxides, such as aluminum oxide, beryllium oxide, magnesium oxide, and zinc oxide; nitrides such as aluminum nitride; carbides such as silicon carbide and tungsten carbide, and combinations thereof. Alternatively, inorganic fillers are exemplified by aluminum oxide, zinc oxide, and combinations thereof. The meltable filler may include Bi, Ga, In, Sn, or alloys thereof. Optionally, the meltable filler may further include Ag, Au, Cd, Cu, Pb, Sb, Zn, or combinations thereof. Examples of suitable meltable fillers include Ga, In-Bi-Sn alloy, Sn-In-Zn alloy, Sn-In-Ag alloy, Sn-Ag-Bi alloy, Sn-Bi-Cu-Ag alloy, Sn-Ag-Cu-Sb alloy, Sn-Ag-Cu alloy, Sn-Ag alloy, Sn-Ag-Cu-Zn alloy, and combinations thereof. The meltable filler may have a melting point between 50°C and 250°C. The meltable filler may be a eutectic alloy, a non-eutectic alloy, or a pure metal. Many suitable meltable fillers are commercially available.

[0092] Alternatively or additionally, the (F) filler may comprise a non-reactive silicone resin. For example, the (F) filler may comprise a T resin, a TD resin, a TDM resin, a TDMQ resin, or any other non-reactive silicone resin. Typically, such non-reactive silicone resins contain at least 30 mole percent T siloxy and / or Q siloxy units. As is known in the art, the D siloxy units are not necessarily R siloxy units. 0 2SiO 2 / 2 and the T siloxy unit is represented by R 0 SiO 3 / 2 where R 0 are independently selected substituents.

[0093] Weight average molecular weight M of non-reactive silicone resin w As used herein, M depends at least in part on the molecular weight of the silicone resin and the types of substituents (e.g., hydrocarbyl groups) present in the non-reactive silicone resin. w represents the weight average molecular weight measured using conventional gel permeation chromatography (GPC) with narrow molecular weight distribution polystyrene (PS) standard calibration when the peak representing neopentamer is excluded from the measurement. The PS equivalent weight M of the non-reactive silicone resin w The viscosity of the non-reactive silicone resin may be 12,000 to 30,000 g / mol, typically 17,000 to 22,000 g / mol. The non-reactive silicone resin may be prepared by any suitable method. This type of silicone resin has been prepared by the hydrolysis of the corresponding silane or by the silica hydrosol capping method, which are generally known in the art.

[0094] A phosphor is a type of filler that can convert the wavelength of light emitted from a light source (optical semiconductor device) when the cured product of the composition is used as a wavelength conversion material. There are no specific limitations on the phosphor, and examples of the phosphor include yellow light, red light, green light, and blue light phosphors. These phosphors include oxide phosphors, oxynitride phosphors, nitride phosphors, sulfide phosphors, and oxysulfide phosphors, which are widely used in light emitting diodes (LEDs).

[0095] In certain embodiments, the (F) filler may include an acid acceptor. The acid acceptor may include a metal oxide such as magnesium oxide. Acid acceptors are generally known in the art and are commercially available under trade names including Rhenofit F, Star Mag CX-50, Star Mag CX-150, BLP-3, and MaxOx98LR. Rhenofit F was calcium oxide manufactured by Rhein Chemie Corporation (Chardon, Ohio, USA). Star Mag CX-50 was magnesium oxide manufactured by Merrand International Corp. (Portsmouth, NH, USA). MagOX 98LR was magnesium oxide manufactured by Premier Chemicals LLC (W. Conshohocken, Pa., USA). BLP-3 was calcium carbonate manufactured by Omya Americas (Cincinnati, Ohio, USA).

[0096] Regardless of the selection of the (F) filler, the (F) filler may be added to form the composition untreated, pretreated, or in combination with an optional filler treating agent, which, when so added, may treat the (F) filler in situ in the composition.

[0097] Filler treating agents may include, for example, silanes such as alkoxysilanes, alkoxy-functional oligosiloxanes, cyclic polyorganosiloxanes, hydroxyl-functional oligosiloxanes such as dimethylsiloxane or methylphenylsiloxane, alkene-functionalized diols, organosilicon compounds, stearic acid, or fatty acids. The filler treating agent may include a single filler treating agent or a combination of two or more filler treating agents selected from similar or different types of molecules.

[0098] The filler treating agent may comprise an alkoxysilane, which may be a monoalkoxysilane, a di-alkoxysilane, a tri-alkoxysilane, or a tetraalkoxysilane. Examples of alkoxysilane filler treating agents include hexyltrimethoxysilane, octyltriethoxysilane, decyltrimethoxysilane, dodecyltrimethoxysilane, tetradecyltrimethoxysilane, phenyltrimethoxysilane, phenylethyltrimethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane, and combinations thereof. In certain embodiments, the alkoxysilane may be used in combination with a silazane, which catalyzes the reaction of the less reactive alkoxysilane with the surface hydroxyl. Such reactions are typically carried out at temperatures above 100°C, under high shear, and with the removal of volatile by-products such as ammonia, methanol, and water.

[0099] Suitable filler treating agents also include alkoxysilyl-functional alkylmethylpolysiloxanes or similar materials in which the hydrolyzable groups can include, for example, silazane, acyloxy, or oximo. In one embodiment, the filler treating agent is a silazane, which can be functionalized with, for example, an alkenyl group. One such example is a silazane of the formula ((CH)ViSi)NH, where Vi is vinyl.

[0100] Alkoxy-functional oligosiloxanes can also be used as filler treating agents. Alkoxy-functional oligosiloxanes and their preparation methods are generally known in the art. Other filler treating agents include mono-end-capped alkoxy-functional polydiorganosiloxanes, i.e., polyorganosiloxanes having an alkoxy functionality at one end.

[0101] Alternatively, filler treating agent can be any of the organosilicon compounds that are typically used to treat silica filler.The example of organosilicon compound includes organochlorosilane such as methyltrichlorosilane, dimethyldichlorosilane and trimethylmonochlorosilane; organosiloxane such as hydroxyl end-blocked dimethylsiloxane oligomer, silicon hydride functional siloxane, hexamethyldisiloxane and tetramethyldivinyldisiloxane; organosilazane such as hexamethyldisilazane and hexamethylcyclotrisilazane; and organoalkoxysilane such as alkylalkoxysilane with methyl, propyl, n-butyl, i-butyl, n-hexyl, n-octyl, i-octyl, n-decyl, dodecyl, tetradecyl, hexadecyl or octadecyl substituent. The organic reactive alkoxysilane may contain amino, methacryloxy, vinyl, glycidoxy, epoxycyclohexyl, isocyanurate, isocyanato, mercapto, sulfide, vinyl-benzyl-amino, benzyl-amino, or phenyl-amino substituents. Alternatively, the filler treating agent may include an organopolysiloxane. The use of such filler treating agents to treat the surface of the (F) filler may utilize multiple hydrogen bonds, either clustered or dispersed, or both, as a method of bonding the organosiloxane to the surface of the (F) filler. The hydrogen-bondable organosiloxane has, on average, at least one silicon-bonded group capable of hydrogen bonding per molecule. The group may be selected from monovalent organic groups with multiple hydroxyl functionalities or monovalent organic groups with at least one amino functional group. Hydrogen bonding may be the primary form of bonding of the organosiloxane to the (F) filler. The organosiloxane may not be able to form covalent bonds with the (F) filler. The hydrogen-bonding capable organosiloxane may be selected from the group consisting of a saccharide-siloxane polymer, an amino-functional organosiloxane, and combinations thereof. Alternatively, the hydrogen-bonding capable polyorganosiloxane may be a saccharide-siloxane polymer.

[0102] Alternatively, filler treating agents may include alkyl thiols such as octadecyl mercaptan, and fatty acids, e.g., oleic acid, stearic acid, titanates, titanate coupling agents, zirconate coupling agents, and combinations thereof. One skilled in the art would be able to optimize the filler treating agent to aid in the dispersion of the (F) filler without undue experimentation.

[0103] If utilized, the relative amounts of filler treating agent and (F) filler are selected based on the particular filler utilized and filler treating agent and their desired effects or properties.

[0104] In some embodiments, the (F) filler is present in the composition in an amount from 1 to 70 wt%, alternatively from 5 to 60 wt%, alternatively from 10 to 50 wt%, alternatively from 10 to 35 wt%, alternatively from 20 to 30 wt%, alternatively from 25 to 27 wt%, based on the total weight of the composition.

[0105] In certain embodiments, the composition further comprises (G) a condensation catalyst. Generally speaking, a condensation catalyst is not required for the use of adhesion promoters containing hydrolyzable and / or condensable groups that can hydrolyze with ambient moisture, e.g., relative humidity, and condense with hydroxyl groups present on certain substrates. However, without intending to be limited by theory, it is believed that the incorporation of (G) a condensation catalyst renders the composition dual-cure, such that the composition can cure both through condensation and exposure to radiation. For example, the mercapto groups of component (B) can bond to the acryloxy functional groups of component (D), thus allowing both condensation cure and thiol-ene cure to occur simultaneously. Dual cure is particularly advantageous in certain end uses of the composition because condensation cure can promote better cure in areas that are difficult to irradiate, for example, when shadows due to surface characteristics exist on the substrate on which the composition is cured.

[0106] (G) Condensation catalysts, if utilized, are not limited and in some embodiments are exemplified by tin catalysts, titanium catalysts, zirconic acid catalysts, and zirconium catalysts. Common examples of suitable tin catalysts include organic compounds in which the tin valency is either +4 or +2 (e.g., tin(IV) compounds and / or tin(II) compounds). Specific examples of tin(IV) compounds include stannic salts of carboxylic acids, such as dibutyltin dilaurate, dimethyltin dilaurate, di-(n-butyl)tin bis-ketonate, dibutyltin diacetate, dibutyltin maleate, dibutyltin diacetylacetonate, dibutyltin dimethoxide, carbomethoxyphenyltin tris-uberate, dibutyltin dioctanoate, dibutyltin diformate, isobutyltin triceroate, dimethyltin dibutyrate, dimethyltin di-neodeconoate, dibutyltin di-neodeconoate, triethyltin tartrate, dibutyltin dibenzoate, butyltin tri-2-ethylhexanoate, dioctyltin diacetate, tin octoate, tin oleate, tin butyrate, tin naphthenate, dimethyltin dichloride, and the like, combinations thereof, and / or partial hydrolysis products thereof. Specific examples of tin(II) compounds include tin(II) salts of organic carboxylic acids, such as tin(II) diacetate, tin(II) dioctanoate, tin(II) diethylhexanoate, tin(II) dilaurate, stannous salts of carboxylic acids, such as tin octoate, tin oleate, tin acetate, tin laurate, tin stearate, tin naphthenate, tin hexanoate, tin succinate, tin caprylate, and combinations thereof. Examples of suitable titanium catalysts include titanium esters such as tetra-n-butyl titanate, tetraisopropyl titanate, tetra-2-ethylhexyl titanate, tetraphenyl titanate, triethanolamine titanate, organosiloxytitanium compounds, and dicarbonyltitanium compounds such as titanium ethylacetoacetate, diisopropoxydi(ethoxyacetoacetyl)titanium, and bis(acetoacetonyl)-diisopropoxytitanium(IV). In certain embodiments, (G) the condensation catalyst is a titanium ethylacetoacetate complex mixed with methyl-trimethoxysilane.

[0107] In certain embodiments, (G) a condensation catalyst is utilized. In certain embodiments, (G) the condensation catalyst is present in the composition in an amount of 0.001 to 5 wt %, alternatively 0.01 to 3 wt %, alternatively 0.01 to 1 wt %, alternatively 0.01 to 0.5 wt %, alternatively 0.01 to 0.2 wt %, based on the total weight of the composition.

[0108] In certain embodiments, the composition is solvent-free, that is, the composition does not contain organic solvent.Examples of organic solvent include: alcohol such as methanol, ethanol, isopropanol, butanol and n-propanol; ketone such as acetone, methyl ethyl ketone and methyl isobutyl ketone; aromatic hydrocarbon such as benzene, toluene and xylene; aliphatic hydrocarbon such as heptane, hexane and octane; glycol ether such as propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether and ethylene glycol n-butyl ether; halogenated hydrocarbon such as dichloromethane, 1,1,1-trichloroethane and methylene chloride; chloroform; dimethyl sulfoxide; dimethylformamide, acetonitrile; tetrahydrofuran, white spirit; mineral spirit; naphtha; n-methylpyrrolidone etc., and their derivatives, variants and combinations.

[0109] In some embodiments, the composition further comprises one or more additives. Examples of suitable additives that may be present in the composition include fillers, treatment agents (e.g., filler treatment agents), crosslinkers, adhesion promoters, surface conditioners, driers, extenders, biocides, flame retardants, plasticizers, end-capping agents, binders, anti-aging additives, water release agents, pigments, dyes, rheology modifiers, carriers, tackifiers, corrosion inhibitors, catalyst inhibitors, viscosity modifiers, UV absorbers, antioxidants, light stabilizers, and the like, and combinations thereof. In certain embodiments, the composition does not comprise any organopolysiloxanes, siloxanes, or silanes other than components (A) to (E).

[0110] As introduced above, a method for forming a cured product ("method") is disclosed. The method includes applying a composition to a surface of a substrate. The method further includes irradiating the composition on the substrate to obtain a cured product. If the composition includes (G) a condensation catalyst, the method may further include moisture-curing the composition. However, moisture curing typically begins upon exposure to atmospheric moisture, and no active step is required to initiate moisture curing.

[0111] The composition can be applied (i.e., placed or dispensed) onto a substrate by any suitable method. Typically, the composition is applied in wet form by a wet coating technique. The composition can be applied by i) spin coating, ii) brush coating, iii) drop coating, iv) spray coating, v) dip coating, vi) roll coating, vii) flow coating, viii) slot coating, ix) gravure coating, x) Mayer bar coating, or xi) a combination of any two or more of i)-x). Typically, disposing the composition on the substrate results in a wet deposit or uncured layer on the substrate, which is subsequently cured to provide a cured product on the substrate.

[0112] The substrate is not limited and may be any substrate. The cured product may be physically and / or chemically bonded to the substrate, depending on the selection. The substrate may optionally have continuous or non-continuous shapes, sizes, dimensions, surface roughness, and other properties.

[0113] The substrate may be an electronic article or component. In other embodiments, the substrate may comprise glass. Alternatively, the substrate may comprise a plastic, which may be thermoset and / or thermoplastic. However, the substrate may alternatively be or comprise a metal, ceramic, fiberglass, cellulose (e.g., paper), wood, cardboard, paperboard, silicone, or polymeric material, or a combination thereof.

[0114] Specific examples of suitable substrates include paper substrates such as kraft paper, polyethylene-coated kraft paper (PEK-coated paper), thermal paper, and plain paper; polymer substrates such as polyamide (PA); polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), polyethylene naphthalate (PEN), and liquid crystal polyester; polyolefins such as polyethylene (PE), polypropylene (PP), and polybutylene; styrene resins; polyoxymethylene (POM); polycarbonate (PC); polymethylene methacrylate (PMMA); polyvinyl chloride (PVC); polyphenylene sulfide (PPS); polyphenylene ether (polyphenylene ether (PPE); polyimide (PI); polyamideimide (PAI); polyetherimide (PEI); polysulfone (PSU); polyethersulfone; polyketone (PK); polyetherketone; polyvinyl alcohol (PVA); polyetheretherketone (PEEK); polyetherketoneketone (PEKK); polyarylate (PAR); polyethernitrile (PEN); phenolic resins; phenoxy resins; celluloses such as triacetyl cellulose, diacetyl cellulose, and cellophane; fluorinated resins such as polytetrafluoroethylene;Thermoplastic elastomers such as polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, and fluoro-type elastomers; and copolymers and combinations thereof.

[0115] The wet deposit or uncured layer is cured through exposure to irradiation, typically UV radiation. Useful UV radiation sources include conventional mercury vapor lamps, LED curing lamps, and the like, designed to emit ultraviolet energy in various ultraviolet wavelength bands. For example, a useful radiation wavelength range includes 200-400 nm. UV curing generally involves exposure to 40 milliwatts / cm². 2 ("mW / cm 2 ) ~ approx. 30,000mW / cm 2 in the range of, for example, about 70 mW / cm 2 ~about 600mW / cm 2 In certain embodiments, irradiation is carried out in an inert atmosphere, for example under nitrogen. In certain embodiments, UV curing is generally carried out in the range of 300 mW / cm of UVA and UVB. 2 strength and 4J / cm 2 This is brought about by a dose of

[0116] If desired, the cured product formed by irradiating the uncured layer can be patterned. For example, in these embodiments, a photomask is typically utilized to selectively cure target portions of the uncured layer. The photomask generally has a defined pattern for transmitting UV radiation and a complementary pattern for blocking the transmission of UV radiation. For example, the photomask includes portions that allow the transmission of UV radiation and portions that block the transmission of UV radiation, so that the defined pattern can be transferred or copied via selective curing. The portions of the photomask that allow the transmission of UV radiation are aligned with the target portions of the uncured layer, and the complementary portions of the photomask that block the transmission of UV radiation are aligned with the non-target portions of the uncured layer. Such a method may be referred to as photolithography. The target portions of the uncured layer are cured to provide cured regions, and the non-target portions of the uncured layer are not cured to provide uncured regions.

[0117] The uncured areas of the cured product remaining from the use of a photomask can be etched using wet methods, such as organic solvents or aqueous bases, or dry methods (e.g., using plasma or reactive ions). Typically, the uncured areas are etched or removed using solvents such as butyl acetate, alcohols, ketones, aromatic hydrocarbons, alkanes, ethers, esters, and combinations thereof. Etching or removing the uncured areas leaves only the cured areas, which can have 100% pattern retention.

[0118] When the composition includes (G) a condensation catalyst and the method further includes moisture-curing the composition (and / or the cured product formed from irradiation), moisture curing can be achieved without any prior step. The composition (and / or the cured product formed from irradiation) can be moisture-cured before, during, or after curing by irradiation. In one embodiment, moisture curing is achieved after curing by irradiation by removing the inert atmosphere and exposing the cured product formed from irradiation to moisture, e.g., relative humidity. When irradiation is performed in an inert atmosphere, a continuous curing step is typically utilized, and the inert atmosphere often does not contain ambient moisture to effect moisture curing.

[0119] In certain embodiments, the cured product may be subjected to a post-bake, for example, by exposure to elevated temperatures, typically 80-140°C, or alternatively 100-120°C, for a period of time.

[0120] As introduced above, a cured product disposed on a substrate is also disclosed. The substrate is not limited and may be any substrate. The cured product may be physically and / or chemically bonded to the substrate as selected. The substrate may optionally have a continuous or discontinuous shape, size, dimension, surface roughness, and other properties.

[0121] The following examples are intended to illustrate the present invention and should not be construed as limiting the scope of the invention in any way.

[0122] The specific ingredients utilized in the examples are set forth in Table 1 below.

[0123] [Table 1]

[0124] General Procedure 1: Compositions of Examples 1-7 and Comparative Examples 1-5 The compositions of Examples 1-7 and Comparative Examples 1-5 were prepared according to General Procedure 1. In General Procedure 1, a preliminary organopolysiloxane mixture was formed by placing organopolysiloxane (A-1), organopolysiloxane (A-2), organopolysiloxane (B-1), and fumed silica filler (F-1) (in the amounts specified below) in a 100 mL dental cup. The preliminary organopolysiloxane mixture was then blended at 1,000 revolutions per minute (rpm) for 20 seconds and then at 2,000 rpm for 45 seconds. Next, the photoinitiator (C-1) and the specific silane (D) and tetraorthosilicate (E) used (shown in Table 2 below) were added to each preliminary organopolysiloxane mixture to obtain a blend. Each blend was mixed at 2,000 rpm for 30 seconds. Where utilized (i.e., in Examples 2-7 and Comparative Example 5), a condensation catalyst (G-1) was added to the blend to obtain a composition, which was then mixed at 2,000 rpm for 30 seconds. Each blend or composition was loaded into three 30 mL syringes, degassed, and placed in an Al bag. Table 2 below lists the specific silane (D) and tetraorthosilicate (E) utilized in the compositions of Examples 1-7 and Comparative Examples 1-5. Tables 3 and 4 list the amounts of each component utilized in each composition of Examples 1-7 and Comparative Examples 1-5.

[0125] [Table 2]

[0126] [Table 3]

[0127] [Table 4]

[0128] Cured products were prepared on substrates using each of the compositions of Examples 1 to 7 and Comparative Examples 1 to 5. The adhesive properties of each cured product were then analyzed. The methods for preparing the cured products and the related test methods for adhesive properties are described below.

[0129] Adhesion Test Procedure A 2024 T3 Alclad aluminum substrate (7.5 cm x 2.5 cm x 1 mm) was cleaned using acetone and isopropanol and air-dried. A 1 cm wide polytetrafluoroethylene (PTFE) tape was placed on the bottom of the substrate. Then, the compositions of Examples 1 to 7 and Comparative Examples 1 to 5 were each cast onto the substrate to obtain a wet deposit having a thickness of 2.5 ± 0.2 mm and a width of 5 ± 1 mm. Each wet deposit was then exposed to UVA and UVB radiation (300 mW / cm 2 ). 2 strength and 4J / cm 2 Each wet deposit was cured by exposure to radiation (via a Colight UV unit with a mercury lamp at a dose of 1000 ppm) and then held at room temperature (22°C) with a relative humidity (RH) of 35-42%. Each wet deposit was further cured at room temperature for 48 hours after exposure to radiation to yield a cured product disposed on a substrate.

[0130] The adhesion of each cured product was then tested by peeling it from the PTFE tape-covered side of the substrate. If the cured product peeled off the substrate without leaving any residue, the cured product was deemed to have adhesive failure (AF). If the cured product adhered to the substrate while peeling and failed, thus leaving residue on the substrate, the sample was deemed to have cohesive failure (CF). Surprisingly, all of the cured products formed from the compositions of Examples 1-7 exhibited cohesive failure, whereas all of the cured products formed from the compositions of Comparative Examples 1-5 exhibited adhesive failure. Cohesive failure, rather than adhesive failure, is desirable for a cured product with desirable adhesion to a substrate. Thus, the compositions of Examples 1-7 were demonstrated to form cured products with excellent adhesion to substrates, particularly compared to the cured products formed from the compositions of Comparative Examples 1-5.

[0131] It is understood that the scope of the appended claims is not limited to the explicit and specific compounds, compositions, or methods described in the detailed description, which may vary among the specific embodiments falling within the scope of the appended claims.

Claims

1. 1. A curable composition comprising: (A) an organopolysiloxane having an average of at least two silicon-bonded aliphatic unsaturated groups per molecule; (B) an organopolysiloxane that is free of aliphatic unsaturated groups and has an average of at least two mercapto groups per molecule; (C) a photoinitiator; and (D) an acryloxy-functional silane represented by the formula: 【Chemical 1】 wherein X is a divalent hydrocarbon group, each R is independently a hydrocarbyl group, and each R １ are independently alkyl groups having 1 to 8 carbon atoms, the subscript x is 2 or 3, and R ２ is H or R １ an acryloxy-functional silane, (E) Formula: Si(OR ３ ) ４ wherein each R ３ and a tetraorthosilicate, wherein is independently an alkyl group having 1 to 10 carbon atoms.

2. The composition of claim 1 , wherein the composition further comprises (F) a filler, or (G) a condensation catalyst, or both.

3. the (A) organopolysiloxane is present in an amount of 5 to 95% by weight, the (C) photoinitiator is present in an amount of 0.01 to 10 wt. %; the (D) acryloxy-functional silane is present in an amount of 0.05 to 5 weight percent; and The (E) tetraorthosilicate is present in an amount of 0.05 to 5% by weight, 3. The composition of claim 1 or 2, each based on the total weight of the composition.

4. The composition of any one of claims 1 to 3, wherein the total molar ratio of mercapto groups in component (B) to silicon-bonded aliphatic unsaturated groups in components (A) and (D) is from 0.1:1 to 3:

1.

5. The organopolysiloxane (A) is represented by the following average formula: (R ４ ３－ｍ R ５ ｍ SiO １／２ ) ａ (R ４ ２－ｎ R ５ ｎ SiO ２／２ ) ｂ (R ５ SiO ３／２ ) ｃ (SiO ４／２ ) ｄ (ZO １／２ ) ｅ In the formula, each R ４ is an independently selected substituted or unsubstituted hydrocarbyl group free of aliphatic unsaturation, and each R ５ are independently R ４ or an aliphatic unsaturated group having 1 to 10 carbon atoms, each subscript m is independently an integer from 0 to 3 in each unit designated by subscript a, and each subscript n is independently an integer from 0 to 2 in each unit designated by subscript b, provided that R ５ at least two of the above are aliphatic unsaturated groups, each Z is independently H or an alkyl group, and a, b, c, d, and e are mole fractions that satisfy a>0, b>0, c≧0, d≧0, 0≦e≦0.05, and a+b+c+d+e=1.

6. 6. The composition of claim 5, wherein c>0 and / or d>0, such that the (A) organopolysiloxane is branched or resinous.

7. The organopolysiloxane (A) has the following average formula: (R ４ ３－ｍ R ５ ｍ SiO １／２ ) ２ (R ４ ２－ｎ R ５ ｎ SiO ２／２ ) ｙ where y is an integer from 10 to 10,000, and each R ４ is an independently selected substituted or unsubstituted hydrocarbyl group free of aliphatic unsaturation, and each R ５ are independently R ４ or an aliphatic unsaturated group having 1 to 10 carbon atoms, each subscript m is independently an integer from 0 to 3, and each subscript n is an integer from 0 to 2 in each unit designated by the subscript y, provided that R ５ The composition according to any one of claims 1 to 4, wherein at least two of the groups are aliphatically unsaturated groups.

8. The organopolysiloxane (A) has the following average formula: (R ４ ２ R ５ SiO １／２ ) ２ (R ４ ２ SiO ２／２ ) ｙ 8. The composition of claim 7, wherein each subscript m is 1 and each subscript n is 0, as represented by:

9. The organopolysiloxane (A) is (A1) a first linear organopolysiloxane having a degree of polymerization of 550 to 2000; (A2) a second organopolysiloxane having a degree of polymerization of 50 to 500. The composition according to any one of claims 1 to 4 and 7 to 8.

10. The organopolysiloxane (B) is represented by the following average formula: (R ４ ３－ｏ R ６ ｏ SiO １／２ ) ｆ (R ４ ２－ｐ R ６ ｐ SiO ２／２ ) ｇ (R ６ SiO ３／２ ) ｈ (SiO ４／２ ) ｉ (ZO １／２ ) ｊ In the formula, each R ４ is an independently selected substituted or unsubstituted hydrocarbyl group free of aliphatic unsaturation, and each R ６ are independently R ４ or contains a mercapto group, each subscript o is independently an integer from 0 to 3 in each unit designated by subscript f, and each p is independently an integer from 0 to 2 in each unit designated by subscript g, with the proviso that R ６ wherein at least two of the groups independently comprise a mercapto group, and each Z is independently H or an alkyl group, and wherein f, g, h, i, and j are mole fractions that satisfy f>0, g>0, h≧0, i≧0, 0≦j≦0.05, and f+g+h+i+j=1.

11. 11. The composition of claim 10, wherein h>0 and / or i>0 such that the (B) organopolysiloxane is branched or resinous.

12. The organopolysiloxane (B) is represented by the following average formula: (R ４ ３－ｏ R ６ ｏ SiO １／２ ) ２ (R ４ ２－ｐ R ６ ｐ SiO ２／２ ) ｚ In the formula, z is an integer from 10 to 10,000, and each R ４ is an independently selected substituted or unsubstituted hydrocarbyl group free of aliphatic unsaturation, and each R ６ are independently R ４ or contains a mercapto group, each subscript o is independently an integer from 0 to 3, and each p is independently an integer from 0 to 2 in each unit designated by the subscript z, with the proviso that R ６ The composition of any one of claims 1 to 9, wherein at least two of the groups independently comprise a mercapto group.

13. The subscript o is 0, and the (B) organopolysiloxane is represented by the following average formula: (R ４ ３ SiO １／２ ) ２ (R ４ R ６ SiO ２／２ ) ｚ’ (R ４ ２ SiO ２／２ ) ｚ’’ 13. The composition of claim 12, wherein z' is an integer from 2 to 100 and the subscript z'' is an integer from 8 to 9998, with the proviso that 10≦z'+z''≦10,000.

14. 14. The composition of any one of claims 1 to 13, wherein (i) the (e) tetraorthosilicate comprises tetraethyl orthosilicate (TEOS) and / or tetrapropyl orthosilicate (TPOS), or (ii) the (D) acryloxy-functional silane comprises 3-methacryloxypropyltrimethoxysilane, or (iii) both (i) and (ii).

15. 1. A method of forming a cured product, comprising: applying a composition according to any one of claims 14 to 11 to the surface of a substrate; and irradiating the composition on the substrate to obtain the cured product.

16. 16. A cured product disposed on a substrate formed according to the method of claim 15.

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