Pressure-sensitive adhesive composition

Abstract

The pressure-sensitive adhesive (PSA) composition comprises (A) a silicate resin that is liquid at 25°C in the absence of any solvent. The (A) silicate resin contains an average of at least one silicon-bonded ethylenically unsaturated group per molecule. The PSA composition further comprises (B) an organosilicon compound having at least two silicon-bonded hydrogen atoms per molecule. In addition, the PSA composition comprises (C) a hydrosilylation reaction catalyst. The (A) silicate resin is miscible in the PSA composition in the absence of any solvent. The PSA composition can be at least partially cured to provide a PSA.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to and all benefits of U.S. Provisional Patent Application No. 62 / 955,126, filed December 30, 2019, the contents of which are incorporated herein by reference.

[0002] FIELD OF THE INVENTION FIELD OF THE DISCLOSURE The present disclosure relates generally to adhesives, and more specifically to pressure-sensitive adhesive compositions comprising silicate resins, and related methods. [Background technology]

[0003] Silicone compositions are known in the art and are utilized in numerous industries and end uses. One such end use is as an adhesive. For example, silicone compositions can be utilized as pressure-sensitive adhesives.

[0004] Conventional silicone-based pressure-sensitive adhesives are often addition curable.In addition, conventional pressure-sensitive adhesives typically contain a tackifier, which is often a solid MQ resin in the case of silicone-based pressure-sensitive adhesives.To formulate such silicone-based pressure-sensitive adhesives, a solid, for example, a solid MQ resin, is dissolved in a solvent and combined with other components of the silicone-based pressure-sensitive adhesive, and the solvent is subsequently removed.Therefore, even if the silicone-based pressure-sensitive adhesive is solvent-free, such solvent-free silicone-based pressure-sensitive adhesives are still typically formed with a solvent. Summary of the Invention

[0005] A pressure-sensitive adhesive (PSA) composition is disclosed. The PSA composition comprises (A) a silicate resin that is liquid at 25°C in the absence of any solvent. The (A) silicate resin contains an average of at least one silicon-bonded ethylenically unsaturated group per molecule. The PSA composition further comprises (B) an organosilicon compound having at least two silicon-bonded hydrogen atoms per molecule. In addition, the PSA composition comprises (C) a hydrosilylation reaction catalyst. The (A) silicate resin is miscible in the PSA composition in the absence of any solvent. The PSA composition can be at least partially cured to yield a PSA.

[0006] A method for preparing a coated substrate comprising a coating disposed on a substrate, as well as a coated substrate formed according to the method, is disclosed. DETAILED DESCRIPTION OF THE INVENTION

[0007] A pressure-sensitive adhesive (PSA) composition is disclosed. The PSA composition includes (A) a silicate resin that is liquid at 25°C in the absence of any solvent. Alternatively, the (A) silicate resin may be referred to as a silicone resin, but the (A) silicate resin is not limited to the Q siloxy or SiO units. 4 / 2The silicate resin is a resin that takes into account the presence of. Generally, silicone resins, and especially silicate resins, are solid at 25°C due to their three-dimensional network structure. Considering the difficulty of processing solid silicone resins, silicone resins are typically dissolved in a solvent and utilized as silicone resin compositions that contain or consist of a solid silicone resin dissolved in a solvent, such as an aliphatic or aromatic hydrocarbon solvent. In this way, the silicone resin composition is liquid at 25°C or room temperature, which allows for easier processing of the silicone resin composition. For example, the silicone resin composition can be combined in liquid form with other components or compositions for various end uses. Similarly, conventional silicone resins that are solid at 25°C in the absence of any solvent are not easily miscible with liquid silicones. This means that when preparing a silicone composition, conventional silicone resins that are solid at 25°C cannot be easily mixed or solubilized with liquid silicones, such as liquid organopolysiloxanes, in the presence of an organic solvent. Thus, when conventional silicone resins are utilized in silicone compositions, an organic solvent is typically required to form the silicone composition, and then volatilizes, either in the form of the composition or upon curing.

[0008] However, one drawback of silicone composition is that solvent is typically removed in final use.For example, when silicone composition is used to form film, coating or article, solvent is typically removed when forming such film or article.This requires additional processing steps, and energy and related costs to remove solvent, for example, through volatilization.

[0009] In contrast, (A) silicate resin is liquid at 25°C in the absence of any solvent. Thus, the (A) silicate resin that is liquid at 25°C is not due to the presence of any solvent, such as an organic solvent, unlike conventional silicone resins. The (A) silicate resin consists of a silicate resin that does not contain any solvent or carrier vehicle. Furthermore, not only is the (A) silicate resin liquid at 25°C in the absence of any solvent, but the (A) silicate resin is miscible with PSA compositions that typically include those in which any organopolysiloxane is utilized therein. This enables the easy formation of PSA compositions without the need for any solvent or related processing steps for removing the solvent from the PSA composition.

[0010] "Liquid" means that the (A) silicate resin is fluid at 25°C and / or has a viscosity that is measurable at 25°C in the absence of any solvent. Typically, the viscosity of the (A) silicate resin can be measured at 25°C via a Brookfield LV DV-E viscometer equipped with a spindle appropriately selected for the viscosity of the (A) silicate resin. The viscosity of the (A) silicate resin can vary, particularly based on the content of M, D, T, and / or Q siloxy units present therein, as described below. However, for the purposes of the present disclosure, the (A) silicate resin can be in the form of a gum even if the gum does not have a viscosity that can be easily measured at 25°C because the gum still has fluidity characteristics.

[0011] In certain embodiments, the (A) silicate resin has the average formula: [W] a [X] b [Y] c [Z] d [where 0 < a < 1, 0 < b < 1, 0 ≤ c < 1, and 0 < d < 1, provided that a + b + c + d = 1]. The subscript letters a, b, c, and d are the mole fractions of the W, X, Y, and Z units in the (A) silicate resin.

[0012] In the above average formula for the (A) silicate resin, [W], [X], [Y], and [Z] are utilized in place of the more common nomenclature [M], [D], [T], and [Q]. As understood in the art, an M siloxy unit contains one siloxane bond (i.e., —O—Si—), a D siloxy unit contains two siloxane bonds, a T siloxy unit contains three siloxane bonds, and a Q siloxy unit contains four siloxane bonds.

[0013] However, for purposes of this disclosure, [W] represents a siloxy unit containing one -Si-O- bond, which may be a siloxane bond or a precursor thereof. A precursor of a siloxane bond is a -Si-OZ bond, where Z is independently H, an alkyl group, or K. + Or Na + or H or an alkyl group. Silanol and alkoxy groups can hydrolyze and / or condense to form siloxane bonds and are typically present intrinsically in most silicone resins. Such precursors of siloxane bonds can be minimized by bodying the silicone resin, which further condenses them with water and / or alcohol by-products. Therefore, for the purposes of this disclosure, [W] is defined as [RSiO 1 / 2 wherein each R is an independently selected hydrocarbyl group.

[0014] Furthermore, for purposes of this disclosure, [X] independently represents a siloxy unit containing two -Si-O- bonds, which may be a siloxane bond or a precursor thereof. Thus, for purposes of this disclosure, [X] represents a siloxy unit containing two -Si-O- bonds, which may be a siloxane bond or a precursor thereof. 1 / 2 (OZ)] b’ [R2SiO 2 / 2 ] b’’where each R is independently selected and defined above, 0≦b′≦b, 0≦b″≦b, with the proviso that b′+b″=b, and each Z is independently H, an alkyl group, or a cation. The subscripts b′ and b″ indicate the relative mole fractions of the [X] siloxy units designated by subscript b′ and the [X] siloxy units designated by subscript b″, respectively, with respect to the overall average formula of (A) silicate resin, and the sum of b′ and b″ equals b. In the [X] siloxy units designated by b′ there is one siloxane bond and one Si-OZ bond, and in the [X] siloxy units designated by subscript b″ there are two siloxane bonds.

[0015] Furthermore, for purposes of this disclosure, [Y] independently represents a siloxy unit containing three -Si-O- bonds, which may be a siloxane bond or a precursor thereof. Thus, for purposes of this disclosure, [Y] represents [RSi(OZ) c’ O 3-c’ / 2 [wherein each R is independently selected and defined above, and c' is an integer from 0 to 2, and is independently selected for each Y siloxy unit denoted by subscript c in (A) the silicate resin]. Thus, [Y] is a siloxy unit of the following: [RSiO 3 / 2 ], [RSi(OZ)1O 2 / 2 ], and / or [RSi(OZ)2O 1 / 2 ] may represent any combination of

[0016] Furthermore, for purposes of this disclosure, [Z] represents a siloxy unit containing four -Si-O- bonds, which may independently be siloxane bonds or precursors thereof. Thus, for purposes of this disclosure, [Z] represents [Si(OZ) d’ O 4-d’ / 2[where each Z is independently selected, as defined above, the subscript d’ is an integer from 0 to 3, and (A) is independently selected for each siloxy unit represented by the subscript d in the silicate resin]. (A) The silicate resin may contain a siloxy unit represented by the subscript d, where d’ is 0, d’ is 1, d’ is 2, and d’ is 3. The siloxy unit represented by [Z] may have one, two, three, or four siloxane bonds, and the rest is Si-OZ. Thus, [Z] is the following siloxy unit: [SiO 4 / 2 , [Si(OZ)O 3 / 2 , [Si(OZ)2O 2 / 2 [[ID= 6]]], and / or any combination of [Si(OZ)3O 1 / 2 may be shown.

[0017] In certain embodiments, the subscript a is greater than zero to 0.9, or greater than 0 to 0.8, or greater than 0 to 0.7, or greater than 0 to 0.6, or greater than 0 to 0.5. In certain embodiments, the subscript a is 0.10 to 0.50, or 0.15 to 0.40, or 0.2 to 0.4, or 0.25 to 0.35.

[0018] In these or other embodiments, the subscript b is greater than zero to 0.9, or greater than 0 to 0.8, or greater than 0 to 0.7, or greater than 0 to 0.6, or greater than 0 to 0.5, or greater than 0 to 0.4. In certain embodiments, the subscript b is 0.10 to 0.30, or 0.15 to 0.30, or 0.15 to 0.25. The subscripts b’ and b’’ define the relative amounts of the specific siloxy units represented by [X]. As described above, 0 ≤ b’ ≤ b, 0 ≤ b’’ ≤ b, provided that b’ + b’’ = b. While the subscript b’ can be 0, the subscript b’’ can be b, or while the subscript b’ can be b, the subscript b’’ can be 0. When both siloxy units represented by b’ and b’’ are present in the (A) silicate resin, 0 < b’ < 1 and 0 < b’’ < 1, provided that b’ + b’’ = b.

[0019] In these or other embodiments, the subscript c is 0. However, in alternative embodiments, the subscript c is greater than 0, such as greater than zero to 0.9, alternatively greater than 0 to 0.8, alternatively greater than 0 to 0.7, alternatively greater than 0 to 0.6, alternatively greater than 0 to 0.5, alternatively greater than 0 to 0.4, alternatively greater than 0 to 0.3, alternatively greater than 0 to 0.2, alternatively greater than 0 to 0.10, or alternatively greater than 0 to 0.08.

[0020] In these or other embodiments, the subscript d is greater than zero to 0.9, alternatively greater than 0 to 0.8, alternatively greater than 0 to 0.7, or alternatively greater than 0 to 0.6. Alternatively, in these or other embodiments, d is between 0.1 and 0.9, alternatively between 0.2 and 0.9, alternatively between 0.3 and 0.9, or alternatively between 0.4 and 0.9. In certain embodiments, the subscript d is between 0.35 and 0.60, alternatively between 0.40 and 0.60, alternatively between 0.40 and 0.55, or alternatively between 0.45 and 0.55.

[0021] R is an independently selected hydrocarbyl group, and at least one, or an average of at least two, of the Rs is independently an ethylenically unsaturated group in each molecule of the (A) silicate resin. Generally, hydrocarbyl groups suitable for R can be independently linear, branched, cyclic, or a combination thereof. Cyclic hydrocarbyl groups include aryl groups and saturated or non-conjugated cyclic groups. Cyclic hydrocarbyl groups can independently be monocyclic or polycyclic. Linear and branched hydrocarbyl groups can independently be saturated or unsaturated. An example of a combination of linear and cyclic hydrocarbyl groups is an aralkyl group. General examples of hydrocarbyl groups include alkyl groups, aryl groups, alkenyl 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. Examples of suitable aryl groups include phenyl, tolyl, xylyl, naphthyl, benzyl, and dimethylphenyl. Examples of suitable alkenyl groups include vinyl, allyl, propenyl, isopropenyl, butenyl, isobutenyl, pentenyl, heptenyl, hexenyl, hexadecenyl, octadecenyl, and cyclohexenyl. Examples of suitable monovalent halogenated hydrocarbon groups (i.e., halocarbon groups) include halogenated alkyl groups, aryl groups, and combinations thereof. Examples of halogenated alkyl groups include the alkyl groups described above in which one or more hydrogen atoms have been replaced with a halogen atom, such as F or Cl.Specific 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 are replaced with halogen atoms such as F or Cl. Specific examples of halogenated aryl groups include chlorobenzyl and fluorobenzyl groups.

[0022] In certain embodiments, each R is independently selected from alkyl groups having 1 to 32, alternatively 1 to 28, alternatively 1 to 24, alternatively 1 to 20, alternatively 1 to 16, alternatively 1 to 12, alternatively 1 to 8, alternatively 1 to 4, or alternatively 1 carbon atom; and ethylenically unsaturated groups (i.e., alkenyl and / or alkynyl groups) having 2 to 32, alternatively 2 to 28, alternatively 2 to 24, alternatively 2 to 20, alternatively 2 to 16, alternatively 2 to 12, alternatively 2 to 8, alternatively 2 to 4, or alternatively 2 carbon atoms. "Alkenyl" refers to an acyclic, branched or unbranched monovalent hydrocarbon group having one or more carbon-carbon double bonds. Specific examples include vinyl, allyl, and hexenyl. "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 ethylenically unsaturated groups include CH2=CH-, CH2=CHCH2-, CH2=CH(CH2)4-, CH2=CH(CH2)6-, CH2=C(CH3)CH2-, HC=C(CH3)-, HC=C(CH3)-, HC=C(CH3)CH2-, HC=CHCH2CH2-, HC=CHCH2CH2-, HC≡C-, HC≡CCH2-, HC≡CCH(CH3)-, HC≡CC(CH3)2-, and HC≡CC(CH3)2CH2-. Typically, when R is an ethylenically unsaturated group, the ethylenic unsaturation is at the terminal of R. As is understood in the art, ethylenically unsaturated groups may be referred to as aliphatic unsaturation.

[0023] In certain embodiments, only the siloxy units designated by subscript b contain R groups with ethylenic unsaturation. In these embodiments, the R groups of the siloxy units designated by subscripts a and c do not contain ethylenic unsaturation, a specific example being methyl. In certain embodiments, the (A) silicate resin contains both dimethylsiloxy units and methylvinylsiloxy units as the siloxy units designated by subscript b. In other embodiments, the (A) silicate resin contains methylvinylsiloxy units but no dimethylsiloxy units as the siloxy units designated by subscript b. The relative amount of such siloxy units can be selectively controlled during the preparation of the (A) silicate resin. As understood in the art, the siloxy units described above are exemplary only, and methyl may be replaced with other hydrocarbyl groups, and vinyl may be replaced with other ethylenically unsaturated groups.

[0024] In certain embodiments, (A) the silicone resin has a SiOZ moiety content of 12 to 80, alternatively 15 to 70, alternatively 15 to 60, alternatively 15 to 50, alternatively 15 to 40, alternatively 15 to 30 mole percent, based on the total number of moles of Si in each molecule. 29 It can be calculated via Si-NMR. In particular, the molar content of the following siloxy units in the (A) silicate resin is determined: W=R3SiO 1 / 2 X1=R2(OZ)SiO 1 / 2 X2=R2SiO 2 / 2 Y1=R(OZ)2SiO 1 / 2 Y2 = R(OZ)SiO 2 / 2 Y3=RSiO 3 / 2 Z1=(OZ)3SiO 1 / 2 Z2=(OZ)2SiO 1 / 2 Z3=(OZ)SiO 3 / 2 Z4=SiO4 / 2 The OZ content relative to silicon atoms as mole % can be calculated with the following formula using the label for each peak in the formula corresponding to the integrated area under the peak corresponding to the label:

number

[0025] In these or other embodiments, the (A) silicate resin has a weight percent of silicon-bonded ethylenically unsaturated groups greater than 0 to 10, or based on the total weight of the (A) silicate resin. The weight percent of silicon-bonded ethylenically unsaturated groups is independent of the viscosity of the (A) silicate resin, which differs from the weight percent of silicon-bonded ethylenically unsaturated groups of conventional solid silicone resins, which is a function of their viscosity after dispersion in a liquid organopolysiloxane polymer or vehicle. Thus, for example, the weight percent of silicon-bonded ethylenically unsaturated groups can be increased without affecting the viscosity of the (A) silicate resin. The weight percent of silicon-bonded ethylenically unsaturated groups can be selectively controlled during the preparation of the (A) silicate resin, as described below.

[0026] In these or other embodiments, the weight percent of silicon-bonded ethylenically unsaturated groups in the (A) silicate resin can be selectively controlled regardless of the viscosity of the (A) silicate resin. In contrast, in conventional silicone resins containing silicon-bonded ethylenically unsaturated groups, the content is a function of viscosity, which limits the ability to selectively control the content of silicon-bonded ethylenically unsaturated groups at a particular viscosity, essentially limiting the use of certain end-use applications. In various embodiments, the (A) silicate resin has a weight average molecular weight of 1,000 to 100,000, alternatively 1,000 to 50,000, or alternatively 1,000 to 10,000. Molecular weight can be measured via gel permeation chromatography (GPC) against polystyrene standards. In these or other embodiments, the (A) silicate resin has a viscosity at 25°C of 10 to 500,000, alternatively 10 to 250,000, alternatively 10 to 100,000 cP. Viscosity can be measured at 25°C via a Brookfield LV DV-E viscometer with a spindle appropriately selected for the viscosity of the (A) silicate resin, as understood in the art. The viscosity and molecular weight of the (A) silicate resin can be controlled during preparation of the (A) silicate resin. In other embodiments, the (A) silicate resin is a gum at 25°C, in which case the (A) silicate resin does not have an easily measurable viscosity at 25°C, but still possesses flowable properties and is considered a liquid for purposes of this disclosure.

[0027] In various embodiments, the silicate resin is prepared from an MQ resin, where M is (R 0 SiO 3 / 2 ) siloxy unit, and Q is (SiO 4 / 2 ) siloxy unit, wherein R 0indicates a silicon-bonded substituent. Such MQ resins are known in the art and are often in solid (e.g., powder or flake) form unless placed in a solvent. However, typically, in the nomenclature utilized in the art, the M siloxy units are trimethylsiloxy units, while MQ resins may contain hydrocarbyl groups other than methyl groups. However, typically, the M siloxy units of MQ resins are trimethylsiloxy units.

[0028] MQ resins have the formula M n The formula may have a Q, where the subscript n refers to the molar ratio of M siloxy units to Q siloxy units when the number of moles of Q siloxy units is normalized to 1. The higher the value of n, the lower the crosslink density of the MQ resin. The converse is also true, because as the value of n decreases, the number of M siloxy units decreases, and therefore more Q siloxy units are networked without terminating through an M siloxy unit. The fact that the formula for an MQ resin normalizes the Q siloxy unit content to 1 does not mean that the MQ resin contains only one Q unit. Typically, an MQ resin contains multiple Q siloxy units clustered or bonded together. MQ resins may contain up to 4 weight percent, alternatively up to 3 weight percent, or alternatively up to 2 weight percent hydroxyl groups in certain embodiments.

[0029] In certain embodiments, the subscript n is <1, e.g., the subscript n is 0.05 to 0.99, alternatively 0.10 to 0.95, alternatively 0.15 to 0.90, alternatively 0.25 to 0.85, alternatively 0.40 to 0.80. In these embodiments, on a molar basis, there are more Q siloxy units than M siloxy units in the MQ resin. However, n can be >1, and in other embodiments, for example, >1 to 6, alternatively >1 to 5, alternatively >1 to 4, alternatively >1 to 3, alternatively >1 to 2.

[0030] In certain embodiments, to prepare (A) silicate resin from an MQ resin, the MQ resin is reacted with a silane compound in the presence of a base catalyst. The silane compound typically contains a silicon-bonded ethylenically unsaturated group and two silicon-bonded alkoxy groups. The silicon-bonded alkoxy groups can be independently selected and typically have 1 to 10, alternatively 1 to 8, alternatively 1 to 6, alternatively 1 to 4, alternatively 1 or 2, or alternatively 1 carbon atom. For example, the silicon-bonded alkoxy group can be methoxy, ethoxy, propoxy, butoxy, etc. For example, the silane compound can have the formula RSi(OR), where each R is independently selected and at least one R that is not part of an alkoxy group is an ethylenically unsaturated group.

[0031] In the method for preparing the (A) silicate resin, a base catalyst typically cleaves the siloxane bond of the MQ resin, typically between the M siloxy unit and the Q siloxy unit, to give an SiOZ group, where Z is defined above. The silane compound can hydrolyze and condense with the SiOZ group incorporated therein. Both the cleavage of the siloxy bond and the inclusion of linear siloxy units resulting from the silane compound result in the (A) silicate resin being a liquid at 25°C in the absence of any solvent.

[0032] Because the silane compound is incorporated into the (A) silicate resin as a D siloxy unit, i.e., as indicated by [X] and the subscript b, the silane compound can be selected based on the desired D siloxy unit. For example, if the (A) silicate resin contains methylvinylsiloxy units, the silane compound can be a methylvinyldialkoxysilane, such as methylvinyldimethoxysilane. If the (A) silicate resin contains dimethylsiloxy units and methylvinylsiloxy units, the silane compound can include methylvinyldimethoxysilane in combination with dimethyldimethoxysilane. Thus, the silane compound can simultaneously contain two or more different silane compounds.

[0033] In certain embodiments where the subscript c in the (A) silicate resin is greater than 0, the method further includes a second silane compound having three independently selected silicon-bonded alkoxy groups. The second silane compound is incorporated into the (A) silicate resin as a siloxy unit, denoted by the subscript c. The second silane compound can be functional, e.g., containing a silicon-bonded ethylenically unsaturated group, or non-functional, e.g., an alkyl group combined with three independently selected silicon-bonded alkoxy groups.

[0034] The relative amount of silane compound (and optionally second silane compound) utilized compared to the MQ resin is a function of the desired subscript b (and optionally subscript c) in the (A) silicate resin. If more D siloxy units are desired, more silane compound is utilized, and vice versa. Those skilled in the art will understand how to selectively control such content in light of the description herein, including this Detailed Description.

[0035] The MQ resin and the silane compound react in the presence of a catalyst. Typically, the catalyst is an acid or a base, such that the reaction between the MQ resin and the silane compound is either an acid-catalyzed reaction or a base-catalyzed reaction. Typically, the reaction is a base-catalyzed reaction. Thus, in certain embodiments, the catalyst can be selected from the group consisting of a strong acid catalyst, a strong base catalyst, and a combination thereof. The strong acid catalyst can be trifluoromethanesulfonic acid or the like. The catalyst is typically a strong base catalyst. Typically, the strong base catalyst is KOH, although other base catalysts, such as phosphazene base catalysts, can be utilized.

[0036] Phosphazene catalysts generally contain at least one -(N=P<)- unit (i.e., a phosphazene unit) and are usually oligomers having up to 10 such phosphazene units, for example, an average of 1.5 to a maximum of 5 phosphazene units. The phosphazene catalyst may be, for example, a halophosphazene such as a chlorophosphazene (phosphonitrile chloride), an oxygen-containing halophosphazene, an ionic derivative of a phosphazene such as a phosphazenium salt, particularly an ionic derivative of a phosphonitrile halide such as a perchlorooligophosphazenium salt, or a partially hydrolyzed form thereof.

[0037] In certain embodiments, the catalyst comprises a phosphazene base catalyst. The phosphazene base catalyst may be any known in the art, but typically has the following chemical formula: (R 3 2N)3P=N) t (R 3 2N) 3-t P=NR 3 [In the formula, each R 3 are independently selected from the group consisting of a hydrogen atom, R, and combinations thereof, and t is an integer from 1 to 3. 3 If is R, then R 3 is typically an alkyl group having 1 to 20, alternatively 1 to 10, alternatively 1 to 4 carbon atoms. 3 2N) two R 3 The groups can be attached to the same nitrogen (N) atom and linked to complete a heterocyclic ring, preferably having 5 or 6 ring members.

[0038] Alternatively, the phosphazene base catalyst can be a salt, and can be represented by the following alternative chemical formula: [((R 3 2N)3P=N) t (R 3 2N) 3-t P=N(H)R 3 ] + [A - ], or [((R 3 2N)3P=N) s (R3 2N) 4-s P] + [A - ] [In the formula, each R 3 are independently selected and defined above, the subscript t is defined above, the subscript s is an integer from 1 to 4, and [A] is an anion, typically selected from the group of fluoride, hydroxide, silanolate, alkoxide, carbonate, and bicarbonate. In one embodiment, the phosphazene base is an aminophosphazenium hydroxide.

[0039] In certain embodiments, the MQ resin and silane compound are reacted in the presence of a solvent at elevated temperatures, e.g., 75-125°C. A suitable solvent may be a hydrocarbon. Suitable hydrocarbons include aromatic hydrocarbons such as benzene, toluene, or xylene, and / or aliphatic hydrocarbons such as heptane, hexane, or octane. Alternatively, the solvent may be a halogenated hydrocarbon such as dichloromethane, 1,1,1-trichloroethane, or methylene chloride. A neutralizing agent such as acetic acid may be utilized to neutralize the catalyst after the reaction. Those skilled in the art can readily determine the catalytic amount of the catalyst utilized, which is a function of its selection and reaction conditions. The resulting (A) silicate resin can be isolated or recovered from the reaction product via conventional techniques, such as stripping or other volatilization techniques.

[0040] The PSA composition further comprises (B) an organosilicon compound having an average of at least two silicon-bonded hydrogen atoms per molecule. The (B) organosilicon compound may be linear, branched, partially branched, cyclic, resinous (i.e., having a three-dimensional network), or may comprise a combination of different structures. The (B) organosilicon compound is typically a crosslinker and / or chain extender, and reacts with the ethylenically unsaturated groups of the (A) silicate resin. Typically, the (B) organosilicon compound comprises an organohydrogensiloxane.

[0041] The (B) organosilicon compound may contain any combination of M, D, T, and / or Q siloxy units, so long as the (B) organosilicon compound contains at least two silicon-bonded hydrogen atoms per molecule. These siloxy units may be combined in various ways to form cyclic, linear, branched, and / or resinous (three-dimensional network) structures. The (B) organosilicon compound may be monomeric, polymeric, oligomeric, linear, branched, cyclic, and / or resinous, depending on the selection of M, D, T, and / or Q units.

[0042] Since the (B) organosilicon compound contains, on average, at least two silicon-bonded hydrogen atoms per molecule for the siloxy units described above, the (B) organosilicon compound contains the following siloxy units containing silicon-bonded hydrogen atoms: (R2H2SiO3), optionally in combination with siloxy units containing no silicon-bonded hydrogen atoms at all: 1 / 2 ), (RH2SiO 1 / 2 ), (HSiO 1 / 2 ), (RHSiO 2 / 2 ), (H2SiO 2 / 2 ) and / or (HSiO 3 / 2 ) wherein R is independently selected and defined above.

[0043] In certain embodiments, the (B) organosilicon compound is a substantially linear or linear polyorganohydrogensiloxane. The substantially linear or linear polyorganohydrogensiloxane has the unit formula: (HR 10 2SiO 1 / 2 ) v’ (HR 10 SiO 2 / 2 ) w’ (R 10 2SiO 2 / 2 ) x’ (R 10 3SiO 1 / 2 ) y’ [In the formula, each R 10are independently selected monovalent hydrocarbon radicals, the subscript v' is 0, 1, or 2, the subscript w' is 0 or 1 or more, the subscript x' is 0 or more, and the subscript y' is 0, 1, or 2, with the proviso that the quantity (v'+y')=2 and the quantity (v'+w')≧2. 10 The monovalent hydrocarbon group of may be as described above for the monovalent hydrocarbon group of R. The quantity (v'+w'+x'+y') may be 2 to 1,000. The polyorganohydrogensiloxane may be i) dimethylhydrogensiloxy-terminated poly(dimethyl / methylhydrogen)siloxane copolymer; ii) dimethylhydrogensiloxy-terminated polymethylhydrogensiloxane; iii) trimethylsiloxy-terminated poly(dimethyl / methylhydrogen)siloxane copolymer; iv) trimethylsiloxy-terminated polymethylhydrogensiloxane, and / or v) is exemplified by a combination of two or more of i), ii), iii), iv), and v). Suitable polyorganohydrogensiloxanes are commercially available from Dow Silicones Corporation (Midland, Michigan, USA).

[0044] In one particular embodiment, the (B) organosilicon compound is linear and contains pendant silicon-bonded hydrogen atoms. In these embodiments, the (B) organosilicon compound can be a dimethyl, methylhydrogen polysiloxane having the average formula: (CH3)3SiO[(CH3)2SiO] x’ [(CH3)HSiO] w’ Si(CH3)3

[0023] The polysiloxane may be a dimethyl,methyl-hydrogenpolysiloxane having the formula:

[0024] where x' and w' are defined above. Those skilled in the art will appreciate that in the above exemplary formula, the dimethylsiloxy and methylhydrogensiloxy units may be present in random or block form, and any methyl group may be replaced with any other hydrocarbon group that does not contain aliphatic unsaturation.

[0045] In another specific embodiment, the (B) organosilicon compound is linear and contains terminal silicon-bonded hydrogen atoms. In these embodiments, the (B) organosilicon compound can be a SiH-terminated dimethylpolysiloxane having the average formula: H(CH3)2SiO[(CH3)2SiO] x’ Si(CH3)2H The organohydrogensiloxane may be a SiH-terminated dimethylpolysiloxane having the formula: [wherein x' is as defined above]. The SiH-terminated dimethylpolysiloxane may be used alone or in combination with the dimethyl, methylhydrogenpolysiloxane disclosed above. When a mixture is used, the relative amount of each organohydrogensiloxane in the mixture may vary. Those skilled in the art will understand that any methyl group in the above exemplary formula may be replaced with any other hydrocarbon group that does not contain aliphatic unsaturation.

[0046] Alternatively, (B) the organosilicon compound may contain both pendant and terminal silicon-bonded hydrogen atoms.

[0047] In yet another particular embodiment, the (B) organosilicon compound is of formula H y’ R 1 3-y’ Si-(OSiR 1 2) m -(OSiR 1 H) m’ -OSiR 1 3-y’ H y’ [In the formula, each R 1 are independently selected hydrocarbyl groups free of ethylenic unsaturation, each y' is independently selected from 0 or 1, and the subscripts m and m' are each 0 to 1,000, with the proviso that m and m' are not simultaneously 0, and m+m' is 1 to 2,000, alternatively 1 to 1,500, alternatively 1 to 1,000.

[0048] In certain embodiments, the (B) organosilicon compound can include an alkylhydrogencyclosiloxane or an alkylhydrogendialkylcyclosiloxane copolymer. Specific examples of suitable organohydrogensiloxanes of this type include (OSiMeH), (OSiMeH), (OSiMeCH), and the like. 13 ), (OSiMeH)2(OSiMeC6H 13 )2, and (OSiMeH)(OSiMeCH 13 )3 [wherein Me represents methyl (—CH3)].

[0049] Other examples of organohydrogensiloxanes suitable for (B) organosilicon compounds are those having at least two SiH-containing cyclosiloxane rings in one molecule. Such organohydrogensiloxanes may be any organopolysiloxane having at least two cyclosiloxane rings, each with at least one silicon-bonded hydrogen (SiH) atom on the ring. The cyclosiloxane rings contain at least three siloxy units (i.e., the minimum number required to form a siloxane ring) and may be any combination of M, D, T, and / or Q siloxy units forming a cyclic structure, provided that at least one of the cyclic siloxy units in each siloxane ring, which may be M, D, and / or T siloxy units, contains one SiH unit. These siloxy units can be represented as MH, DH, and TH siloxy units, respectively, when the other substituent is methyl.

[0050] The (B) organosilicon compound may comprise a combination or two or more different organohydrogensiloxanes that differ in at least one property, such as structure, molecular weight, content of monovalent groups bonded to silicon atoms, and silicon-bonded hydrogen atoms. The PSA composition may comprise the (B) organosilicon compound in an amount such that the molar ratio of silicon-bonded hydrogen atoms in component (B) to silicon-bonded ethylenically unsaturated groups in component (A) (and other components, if present) is 0.01:1 to 5:1, alternatively 0.1 to 3:1, alternatively 0.3 to 2:1, or alternatively 0.3 to 1:1.

[0051] The PSA composition further comprises (C) a hydrosilylation catalyst. The (C) hydrosilylation catalyst is not limited and may be any known hydrosilylation catalyst for catalyzing a hydrosilylation reaction. A combination of different hydrosilylation catalysts may also be used.

[0052] In certain embodiments, the (C) hydrosilylation reaction catalyst comprises a Group VIII-Group XI transition metal. For the Group VIII-Group XI transition metals, reference is made to the latest IUPAC nomenclature. Group VIII transition metals are iron (Fe), ruthenium (Ru), osmium (Os), and hassium (Hs); Group IX transition metals are cobalt (Co), rhodium (Rh), and iridium (Ir); Group X transition metals are nickel (Ni), palladium (Pd), and platinum (Pt); and Group XI transition metals are copper (Cu), silver (Ag), and gold (Au). Combinations of these, complexes (e.g., organometallic complexes), and other forms of such metals may also be utilized as the (C) hydrosilylation reaction catalyst.

[0053] Additional examples of suitable catalysts for (C) the hydrosilylation reaction catalyst include rhenium (Re), molybdenum (Mo), Group IV transition metals (i.e., titanium (Ti), zirconium (Zr), and / or hafnium (Hf)), lanthanides, actinides, and Group I and II metal complexes (e.g., those containing calcium (Ca), potassium (K), strontium (Sr), etc.). Combinations of these, complexes of these (e.g., organometallic complexes), and other forms of such metals may also be utilized as (C) the hydrosilylation reaction catalyst.

[0054] The (C) hydrosilylation catalyst may be in any suitable form. For example, the (C) hydrosilylation catalyst may be solid, and examples thereof include platinum-based catalysts, palladium-based catalysts, and similar noble metal-based catalysts, as well as nickel-based catalysts. Specific examples thereof include nickel, palladium, platinum, rhodium, cobalt, and similar elements, as well as platinum-palladium, nickel-copper-chromium, nickel-copper-zinc, nickel-tungsten, nickel-molybdenum, and similar catalysts containing multiple metal combinations. Further examples of solid catalysts include Cu-Cr, Cu-Zn, Cu-Si, Cu-Fe-AI, Cu-Zn-Ti, and similar copper-containing catalysts.

[0055] The (C) hydrosilylation catalyst may be present in or on a solid support. Examples of supports include activated carbon, silica, silica alumina, alumina, zeolites, and other inorganic powders / particles (e.g., sodium sulfate). The (C) hydrosilylation catalyst may also be deposited, for example, in a solvent that solubilizes the (C) hydrosilylation catalyst, or simply in a vehicle that supports but does not solubilize the (C) hydrosilylation catalyst. Such vehicles are known in the art.

[0056] In specific embodiments, (C) the hydrosilylation catalyst comprises platinum. In these embodiments, (C) the hydrosilylation catalyst is exemplified by, for example, platinum black, platinum compounds (chloroplatinic acid, chloroplatinic acid hexahydrate, reaction products of chloroplatinic acid with monohydric alcohols, platinum bis(ethylacetoacetate), platinum bis(acetylacetonate), platinum chloride, etc.), complexes of such compounds with olefins or organopolysiloxanes, and platinum compounds microencapsulated within a matrix or core-shell compound. Microencapsulated hydrosilylation catalysts and methods for preparing them are also known in the art, as exemplified by U.S. Pat. Nos. 4,766,176 and 5,017,654, which are incorporated herein by reference in their entireties.

[0057] Platinum complexes of organopolysiloxanes suitable for use as (C) hydrosilylation catalysts include platinum complexes of 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane. These complexes may be microencapsulated in a resin matrix. Alternatively, the (C) hydrosilylation catalyst may comprise a platinum complex of 1,3-diethenyl-1,1,3,3-tetramethyldisiloxane. The (C) hydrosilylation catalyst may be prepared by a method comprising reacting chloroplatinic acid with an aliphatically unsaturated organosilicon compound, such as divinyltetramethyldisiloxane, or an alkene-platinum-silyl complex. The alkene-platinum-silyl complex may be prepared, for example, by mixing 0.015 moles of (COD)PtCl with 0.045 moles of COD and 0.0612 moles of HMeSiCl.

[0058] (C) The hydrosilylation catalyst may also, or instead, be a photoactivatable hydrosilylation catalyst, which may initiate curing via irradiation and / or heat. The photoactivatable hydrosilylation catalyst may be any hydrosilylation catalyst capable of catalyzing a hydrosilylation reaction, particularly when exposed to radiation having a wavelength of 150 to 800 nanometers (nm).

[0059] Specific examples of photoactivatable hydrosilylation catalysts suitable for (C) the hydrosilylation catalyst include platinum(II) bis(2,4-pentanedioate), platinum(II) bis(2,4-hexanedioate), platinum(II) bis(2,4-heptanedioate), platinum(II) bis(1-phenyl-1,3-butanedioate, platinum(II) bis(1,3-diphenyl-1,3-propanedioate), platinum(II) bis(1,1,1,5,5,5-heptanedioate), and platinum(II) bis(1,1,1,5,5,5-heptanedioate). platinum(II) β-diketonate complexes such as platinum(II) β-diketonate complexes (eta-cyclopentadienyl) such as (Cp)trimethylplatinum, (Cp)ethyldimethylplatinum, (Cp)triethylplatinum, (chloro-Cp)trimethylplatinum, and (trimethylsilyl-Cp)trimethylplatinum, where Cp represents cyclopentadienyl; (η-cyclopentadienyl)trialkylplatinum complexes such as [Pt[C6H5NNNOCH3]4, Pt[p-CN-C6H4NNNOCH6H 11 ]4, Pt[p-H3COC6H4NNNOC6H 11 ]4, Pt[p-CH3(CH2) x -C6H4NNNOCH3]4, 1,5-cyclooctadienePt[p-CN-C6H4NNNOC6H 11 ]2, 1,5-cyclooctadiene Pt[p-CH3O-C6H4NNNOCH3]2, [(C6H5)3P]3Rh[p-CN-C6H4NNNOC6H 11 ], and Pd[p-CH3(CH2) x triazene oxide-transition metal complexes such as (η 4 -1,5-cyclooctadienyl)diphenylplatinum, (η 4 -1,3,5,7-cyclooctatetraenyl)diphenylplatinum, (η 4 -2,5-norborazienyl)diphenylplatinum, (η 4 -1,5-cyclooctadienyl)bis-(4-dimethylaminophenyl)platinum, (η 4 -1,5-cyclooctadienyl)bis-(4-acetylphenyl)platinum, and (η 4Typically, the photoactivatable hydrosilylation catalyst is a Pt(II) β-diketonate complex, and more typically, the catalyst is platinum(II) bis(2,4-pentanedioate).

[0060] (C) The hydrosilylation catalyst is present in the PSA composition in a catalytic amount, i.e., an amount or quantity sufficient to promote cure thereof under the desired conditions. The hydrosilylation catalyst can be a single hydrosilylation catalyst or a mixture comprising two or more different hydrosilylation catalysts.

[0061] The catalytic amount of (C) hydrosilylation catalyst can be >0.01 ppm to 10,000 ppm, or >1,000 ppm to 5,000 ppm. Alternatively, typical catalytic amounts of (C) hydrosilylation catalyst are 0.1 ppm to 5,000 ppm, or 1 ppm to 2,000 ppm, or >0 to 1,000 ppm. Alternatively, the catalytic amount of (C) hydrosilylation catalyst can be 0.01 ppm to 1,000 ppm, or 0.01 ppm to 100 ppm, or 20 ppm to 200 ppm, or 0.01 ppm to 50 ppm of platinum group metal, based on the total weight of the PSA composition.

[0062] In certain embodiments, the PSA composition further comprises (D) an organopolysiloxane having an average of at least two silicon-bonded ethylenically unsaturated groups per molecule. In certain embodiments, the (D) organopolysiloxane has an average of at least two silicon-bonded groups with terminal aliphatic unsaturation per molecule. The (D) organopolysiloxane may be linear, branched, partially branched, cyclic, resinous (i.e., having a three-dimensional network), or may comprise a combination of different structures. The polyorganosiloxane may have the average formula R 4 a SiO (4-a) / 2 [In the formula, each R 4is independently selected from a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, provided that in each molecule, R 4 at least two of which contain aliphatic unsaturation and the subscript a is selected such that 0 < a ≤ 3.2]. R 4 Suitable monovalent hydrocarbon groups and monovalent halogenated hydrocarbon groups for are as described above for R. The above average formula of the polyorganosiloxane may alternatively be (R 4 3SiO 1 / 2 ) b (R 4 2SiO 2 / 2 ) c (R 4 SiO 3 / 2 ) d (SiO 4 / 2 ) e [wherein R 4 is defined as above, and the subscripts b, c, d, and e are each independently ≥ 0 to ≤ 1, provided that the quantity (b + c + d + e) = 1]. One skilled in the art will understand how such M, D, T, and Q units, and their mole fractions, affect the subscript a in the above average formula. The T units (indicated by the subscript d), the Q units (indicated by the subscript e), or both are typically present in the polyorganosiloxane resin, while the D units indicated by the subscript c are typically present in the polyorganosiloxane polymer (and may also be present in the polyorganosiloxane resin or branched polyorganosiloxane).

[0063] Alternatively, the (D) organopolysiloxane can be substantially linear or can be linear. A substantially linear organopolysiloxane has an average formula R 4 a’ SiO (4-a’) / 2 [wherein each R 4 is as defined above, and the subscript a' is selected such that 1.9 ≤ a' ≤ 2.2].

[0064] The substantially linear organopolysiloxane of component (D) can be a flowable liquid or can be in the form of an uncured rubber at 25°C. The substantially linear organopolysiloxane may have a viscosity at 25°C of 10 mPa·s to 30,000,000 mPa·s, alternatively 10 mPa·s to 10,000 mPa·s, alternatively 100 mPa·s to 1,000,000 mPa·s, alternatively 100 mPa·s to 100,000 mPa·s. Viscosity can be measured at 25°C via a Brookfield LV DV-E viscometer equipped with a spindle appropriately selected for the viscosity of the substantially linear polyorganopolysiloxane, i.e., RV-1 to RV-7. Typically, component (D) is a flowable liquid at 25°C due to its miscibility with component (A).

[0065] Alternatively, when the (D) organopolysiloxane is substantially linear or linear, the (D) organopolysiloxane has the average unit formula (R 6 R 5 2SiO 1 / 2 ) aa (R 6 R 5 SiO 2 / 2 ) bb (R 6 2SiO 2 / 2 ) cc (R 5 3SiO 1 / 2 ) dd [In the formula, each R 5 are independently selected monovalent hydrocarbon radicals free of aliphatic unsaturation or monovalent halogenated hydrocarbon radicals free of aliphatic unsaturation, and each R 6are independently selected from the group consisting of alkenyl and alkynyl, and the subscript aa is 0, 1, or 2, the subscript bb is 0 or more, the subscript cc is 1 or more, and the subscript dd is 0, 1, or 2, with the proviso that the quantity (aa+dd) is 2 or more and the quantity (aa+dd)=2, and with the proviso that the quantity (aa+bb+cc+dd) is 3 to 2,000. Alternatively, the subscript cc is 0 or more. Alternatively, the subscript bb is 2 or more. Alternatively, the quantity (aa+dd) is 2 to 10, alternatively 2 to 8, alternatively 2 to 6. Alternatively, the subscript cc is 0 to 1,000, alternatively 1 to 500, alternatively 1 to 200. Alternatively, the subscript bb is 2 to 500, alternatively 2 to 200, alternatively 2 to 100.

[0066] R 5 The monovalent hydrocarbon group is exemplified by an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 10 carbon atoms, a halogenated alkyl group having 1 to 6 carbon atoms, a halogenated aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a halogenated aralkyl group having 7 to 12 carbon atoms, where the alkyl, aryl, and halogenated alkyl are as described herein. Alternatively, each R 5 is an alkyl group. Alternatively, each R 5 are independently methyl, ethyl or propyl. 5 Each instance of R may be the same or different. 5 is a methyl group.

[0067] R 6 The monovalent hydrocarbon group having aliphatic unsaturation of R is capable of undergoing a hydrosilylation reaction. 6 Suitable aliphatic unsaturated hydrocarbon groups for are exemplified by alkenyl groups as defined herein and exemplified by vinyl, allyl, butenyl, and hexenyl, and alkynyl groups as defined herein and exemplified by ethynyl and propynyl. 6 may be vinyl or hexenyl. Alternatively, each R 6is a vinyl group. The alkenyl or alkynyl content of the (D) organopolysiloxane can be 0.1% to 1%, alternatively 0.2% to 0.5%, based on the weight of the (D) organopolysiloxane.

[0068] The (D) 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. Specific examples of (D) organopolysiloxanes having pendant silicon-bonded aliphatic unsaturated groups include starting materials A) having the average unit formula: [(CH3)3SiO 1 / 2 ]2[(CH3)2SiO 2 / 2 ] cc [(CH3)ViSiO 2 / 2 ] bb where the subscripts bb and cc are as defined above, 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). Alternatively, as a specific example of a polyorganosiloxane having an average of at least two silicon-bonded aliphatic unsaturated groups per molecule, (D) organopolysiloxane may have the average formula Vi(CH3)2SiO[(CH3)2SiO] cc Si(CH3)2Vi, where the subscripts cc and Vi are defined above. Dimethylpolysiloxanes terminated with silicon-bonded vinyl groups can be used alone or in combination with the dimethyl, methyl-vinylpolysiloxanes immediately disclosed as (D) organopolysiloxanes. With respect to this average formula, any methyl group can be replaced with a different monovalent hydrocarbon group, and any vinyl group can be replaced with any terminal aliphatically unsaturated monovalent hydrocarbon group. Since the at least two silicon-bonded aliphatically unsaturated groups can be both pendant and terminal, the (D) organopolysiloxane can alternatively have the average unit formula [Vi(CH3)2SiO 1 / 2 ]2[(CH3)2SiO 2 / 2] cc [(CH3)ViSiO 2 / 2 ] bb where the subscripts bb and cc and Vi are defined above.

[0069] When the (D) organopolysiloxane is a substantially linear polyorganosiloxane, the (D) organopolysiloxane 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 methylphenylsiloxanes capped at both molecular ends with dimethylvinylsiloxy groups. Examples include copolymers of vinylsiloxane and diphenylsiloxane, 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.

[0070] Alternatively, the organopolysiloxane (D) is 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 polydimethylsiloxane; 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) and xvii) It may include a substantially linear or linear polyorganosiloxane selected from the group consisting of combinations thereof.

[0071] Alternatively, (D) the organopolysiloxane may comprise a resinous polyorganosiloxane having an average formula R 4 a’’ SiO (4-a’’) / 2 [In the formula, each R 4 are independently selected as defined above, and the subscript a'' is selected such that 0.5≦a''≦1.7.

[0072] Resinous polyorganosiloxanes have a branched or three-dimensional network molecular structure. At 25°C, resinous polyorganosiloxanes may be in liquid or solid form. Alternatively, resinous polyorganosiloxanes 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). Typically, resinous polyorganosiloxanes contain T units and / or Q units. Specific examples of resinous polyorganosiloxanes include vinyl-terminated silsesquioxanes (i.e., T resins) and vinyl-terminated MDQ resins.

[0073] Alternatively, (D) the organopolysiloxane may comprise a branched siloxane, a silsesquioxane, or both a branched siloxane and a silsesquioxane.

[0074] When the (D) organopolysiloxane comprises a blend of different organopolysiloxanes, the blend can be a physical blend or mixture. For example, when the (D) organopolysiloxane comprises a branched siloxane and a silsesquioxane, the branched siloxane and the silsesquioxane are present in amounts relative to each other such that the combined amounts of the branched siloxane and the silsesquioxane total 100 parts by weight, based on the total weight of all components present in the PSA composition. The branched siloxane may be present in an amount of 50 to 100 parts by weight, and the silsesquioxane may be present in an amount of 0 to 50 parts by weight. Alternatively, the branched siloxane may be present in an amount of 50 to 90 parts by weight, and the silsesquioxane may be present in an amount of 10 to 50 parts by weight. Alternatively, the branched siloxane may be present in an amount of 50 to 80 parts by weight, and the silsesquioxane may be present in an amount of 20 to 50 parts by weight. Alternatively, the branched siloxane may be present in an amount of 50 to 76 parts by weight and the silsesquioxane may be present in an amount of 24 to 50 parts by weight, or alternatively, the branched siloxane may be present in an amount of 50 to 70 parts by weight and the silsesquioxane may be present in an amount of 30 to 50 parts by weight.

[0075] (D) The branched siloxane of the organopolysiloxane has the unit formula (R 7 3SiO 1 / 2 ) p (R 8 R 7 2SiO 1 / 2 ) q (R 7 2SiO 2 / 2 ) r (SiO 4 / 2 ) s [In the formula, each R 7 are independently a monovalent hydrocarbon group free of aliphatic unsaturation or a monovalent halogenated hydrocarbon group free of aliphatic unsaturation, and each R 8 is an alkenyl or alkynyl group, both as defined above, and may have the subscript p≧0, the subscript q>0, 15≧r≧995, and the subscript s is >0.

[0076] In the above unit formula, subscript p≧0. Subscript q>0. Or, subscript q≧3. Subscript r is 15 to 995. Subscript s>0. Or, subscript s≧1. Or, for subscript p, 22≧p≧0, or 20≧p≧0, or 15≧p≧0, or 10≧p≧0, or 5≧p≧0. Or, for subscript q, 22≧q>0, or 22≧q≧4, or 20≧q>0, or 15≧q>1, or 10≧q≧2, or 15≧q≧4. Or, for subscript r, 800≧r≧15, or 400≧r≧15. Alternatively, for subscript s, 10≧s>0, alternatively, 10≧s≧1, alternatively, 5≧s>0, alternatively, s=1. Alternatively, subscript s is 1 or 2. Alternatively, when subscript s=1, subscript p may be 0 and subscript q may be 4.

[0077] The branched siloxane is represented by the formula (R 7 2SiO 2 / 2 ) m wherein each subscript m is independently 2 to 100. Alternatively, the branched siloxane may comprise at least two polydiorganosiloxane chains of the formula (R 7 2SiO 2 / 2 ) o wherein each subscript o is independently 1 to 100; 4 / 2 Alternatively, the branched siloxane may comprise at least one unit of the formula [ka] wherein the subscript u is 0 or 1; each subscript t is independently 0 to 995, alternatively 15 to 995, alternatively 0 to 100; and each R 9 are independently selected monovalent hydrocarbon groups, as described above, and each R 7are independently selected monovalent hydrocarbon radicals free of aliphatic unsaturation or monovalent halogenated hydrocarbon radicals free of aliphatic unsaturation, and each R 8 and may each have the same meaning as defined above and be independently selected from the group consisting of alkenyl and alkynyl. Suitable branched siloxanes are exemplified by those disclosed in U.S. Pat. No. 6,806,339 and U.S. Patent Application Publication No. 2007 / 0289495.

[0078] In certain embodiments, the branched siloxane has the formula (R 2 y R 1 3-y SiO 1 / 2 ) x (R 1 R 2 SiO 2 / 2 ) z (SiO 4 / 2 )[where each R 1 are independently selected hydrocarbyl groups free of ethylenic unsaturation, and each R 2 is R 1 and an ethylenically unsaturated group, wherein the subscript y is independently selected in each siloxy unit designated by the subscript x and is 1 or 2, and wherein the subscript x is 1.5 to 6 and the subscript z is 3 to 1,000. Specific examples of ethylenically unsaturated and ethylenically unsaturated-free hydrocarbyl groups are described above for R.

[0079] Silsesquioxane has the unit formula (R 7 3SiO 1 / 2 ) i (R 8 R 7 2SiO 1 / 2 ) f (R 7 2SiO 2 / 2 ) g (R 7 SiO 3 / 2 ) h [In the formula, R 7 and R 8is as above, and may have subscript i≧0, subscript f>0, subscript g is 15-995, and subscript h>0. Subscript i may be 0-10. Alternatively, for subscript i, 12≧i≧0, or 10≧i≧0, or 7≧i≧0, or 5≧i≧0, or 3≧i≧0.

[0080] Alternatively, the subscript f is ≧1. Alternatively, the subscript f is ≧3. Alternatively, for subscript f, 12≧f>0, or 12≧f≧3, or 10≧f>0, or 7≧f>1, or 5≧f≧2, or 7≧f≧3. Alternatively, for subscript g, 800≧g≧15, or 400≧g≧15. Alternatively, the subscript h is ≧1. Alternatively, the subscript h is 1 to 10. Alternatively, for subscript h, 10≧h>0, or 5≧h>0, or h=1. Alternatively, the subscript h is 1 to 10, or the subscript h is 1 or 2. Alternatively, if subscript h=1, the subscript f may be 3 and the subscript i may be 0. The value of subscript f may be sufficient to provide the silsesquioxane of unit formula (ii-II) with an alkenyl content of from 0.1 wt. % to 1 wt. %, alternatively from 0.2 wt. % to 0.6 wt. %, based on the weight of the silsesquioxane. Suitable silsesquioxanes are exemplified by those disclosed in U.S. Pat. No. 4,374,967.

[0081] The (D) organopolysiloxane may comprise a combination or two or more different polyorganosiloxanes differing in at least one property, such as structure, molecular weight, monovalent groups bonded to silicon atoms, and content of aliphatic unsaturated groups, etc. The PSA composition may comprise the (D) organopolysiloxane in an amount of 60 to 99.5 weight percent, alternatively 60 to 98 weight percent, alternatively 60 to 95 weight percent, alternatively 70 to 95 weight percent, or alternatively 75 to 95 weight percent, based on the total weight of the PSA composition.

[0082] In certain embodiments, the PSA composition further comprises an (E) inhibitor, which can be used to modify the reaction rate or cure rate of the PSA composition when compared to a composition containing the same starting materials but omitting the (E) inhibitor. (E) Inhibitors include acetylenic alcohols such as methylbutynol, ethynylcyclohexanol, dimethylhexynol, and 3,5-dimethyl-1-hexyn-3-ol, 1-butyn-3-ol, 1-propyn-3-ol, 2-methyl-3-butyn-2-ol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, 3-phenyl-1-butyn-3-ol, 4-ethyl-1-octyn-3-ol, and 1-ethynyl-1-cyclohexanol, and combinations thereof; cycloalkenylsiloxanes, such as 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl- ... Examples include methylvinylcyclosiloxanes, such as hexenylcyclotetrasiloxane, and combinations thereof; ene-yne compounds, such as 3-methyl-3-penten-1-yne and 3,5-dimethyl-3-hexen-1-yne; triazoles such as benzotriazole; phosphines; mercaptans; hydrazines; amines, such as tetramethylethylenediamine; dialkyl fumarates, dialkenyl fumarates, dialkoxyalkyl fumarates, maleates, such as diallyl maleate; nitriles; ethers; carbon monoxide; alkenes, such as cyclooctadiene and divinyltetramethyldisiloxane; alcohols, such as benzyl alcohol; and combinations thereof. Alternatively, the (E) inhibitor can be selected from the group consisting of acetylene alcohols (e.g., 1-ethynyl-1-cyclohexanol) and maleates (e.g., diallyl maleate, bismaleate, or n-propyl maleate), and combinations of two or more thereof.

[0083] Alternatively, the (E) inhibitor can be a silylated acetylenic compound. Without being bound by theory, it is believed that the addition of the silylated acetylenic compound reduces yellowing of the reaction product prepared from the hydrosilylation reaction of the PSA composition when compared to the reaction product from the hydrosilylation of a composition that does not contain the silylated acetylenic compound or a composition that contains an organic acetylenic alcohol inhibitor such as those described above.

[0084] The silylated acetylene compounds are (3-methyl-1-butyn-3-oxy)trimethylsilane, ((1,1-dimethyl-2-propynyl)oxy)trimethylsilane, bis(3-methyl-1-butyn-3-oxy)dimethylsilane, bis(3-methyl-1-butyn-3-oxy)silanemethylvinylsilane, bis((1,1-dimethyl-2-propynyl)oxy)dimethylsilane, methyl(tris(1,1-dimethyl-2-propynyloxy))silane, methyl(tris(3-methyl-1-butyn-3-oxy))silane, (3-methyl-1-butyn-3-oxy)dimethylphenylsilane, (3-methyl-1-butyn-3-oxy)dimethylhexenylsilane, (3-methyl-1-butyn-3-oxy)triethylsilane, bis(3-methyl-1- cyclohexyl-1-ethyn-1-oxy)dimethylhexenylsilane, (cyclohexyl-1-ethyn-1-oxy)dimethylvinylsilane, (cyclohexyl-1-ethyn-1-oxy)diphenylmethylsilane, (cyclohexyl-1-ethyn-1-oxy)trimethylsilane, (cyclohexyl-1-ethyn-1-oxy)trifluoropropylsilane, (3,5-dimethyl-1-hexyn-3-oxy)trimethylsilane, (3-phenyl-1-butyn-3-oxy)diphenylmethylsilane, (3-phenyl-1-butyn-3-oxy)dimethylphenylsilane, (3-phenyl-1-butyn-3-oxy)dimethylvinylsilane, (3-phenyl-1-butyn-3-oxy)dimethylhexenylsilane, (cyclohexyl-1-ethyn-1-oxy)dimethylvinylsilane, (cyclohexyl-1-ethyn-1-oxy)diphenylmethylsilane, (cyclohexyl-1-ethyn-1-oxy)trimethylsilane, and combinations thereof. Alternatively, the (E) inhibitor is exemplified by methyl(tris(1,1-dimethyl-2-propynyloxy))silane, ((1,1-dimethyl-2-propynyl)oxy)trimethylsilane, or a combination thereof. Silylated acetylenic compounds useful as (E) inhibitors can be prepared by methods known in the art, such as silylation of the above-mentioned acetylenic alcohols by reaction with a chlorosilane in the presence of an acid acceptor.

[0085] The amount of (E) inhibitor present in the PSA composition will depend on various factors, including the desired pot life of the PSA composition, whether the PSA composition is a one-part or multi-part composition, the particular inhibitor used, and the selection and amounts of components (A) through (D). However, if present, the amount of (E) inhibitor may be from 0% to 1%, alternatively from 0% to 5%, alternatively from 0.001% to 1%, alternatively from 0.01% to 0.5%, alternatively from 0.0025% to 0.025%, based on the total weight of the PSA composition.

[0086] In certain embodiments, the PSA composition further comprises (F) an adhesion promoter. Suitable adhesion promoters are exemplified by the reaction product of a vinylalkoxysilane with an epoxy-functional alkoxysilane; the reaction product of a vinylalkoxysilane with an epoxy-functional alkoxysilane; and a combination (e.g., physical blend and / or reaction product) of a polyorganosiloxane having at least one aliphatic unsaturated hydrocarbon group and at least one hydrolyzable group per molecule with an epoxy-functional alkoxysilane (e.g., a combination of a hydroxy-terminated vinyl-functional polydimethylsiloxane with glycidoxypropyltrimethoxysilane). Alternatively, the adhesion promoter may comprise a polyorganosilicate resin. Suitable adhesion promoters and methods for their preparation are disclosed, for example, in U.S. Pat. No. 9,562,149, U.S. Patent Application Publication Nos. 2003 / 0088042, 2004 / 0254274, and 2005 / 0038188, and European Patent No. 0 556 023.

[0087] Further examples of suitable adhesion promoters include transition metal chelates, hydrocarbonoxysilanes such as alkoxysilanes, combinations of alkoxysilanes with hydroxy-functional polyorganosiloxanes, or combinations thereof. (F) The adhesion promoter can be a silane having at least one substituent with an adhesion-promoting group, such as an epoxy group, an acetoxy group, or an acrylate group. The adhesion-promoting group can additionally or alternatively be any hydrolyzable group that does not affect the (C) hydrosilylation reaction catalyst. Alternatively, (F) the adhesion promoter can include a partial condensate of such a silane, such as an organopolysiloxane with an adhesion-promoting group. Alternatively, (F) the adhesion promoter can include a combination of an alkoxysilane with a hydroxy-functional polyorganosiloxane.

[0088] Alternatively, the (F) adhesion promoter may comprise an unsaturated or epoxy-functional compound. The (F) adhesion promoter may comprise an unsaturated or epoxy-functional alkoxysilane. For example, the functional alkoxysilane may comprise at least one unsaturated organic group or an epoxy-functional organic group. Epoxy-functional organic groups are exemplified by 3-glycidoxypropyl and (epoxycyclohexyl)ethyl. Unsaturated organic groups are exemplified by 3-methacryloyloxypropyl, 3-acryloyloxypropyl, and unsaturated monovalent hydrocarbon groups such as vinyl, allyl, hexenyl, and undecylenyl. A specific example of an unsaturated compound is vinyltriacetoxysilane.

[0089] Specific examples of suitable epoxy-functional alkoxysilanes include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, (epoxycyclohexyl)ethyldimethoxysilane, (epoxycyclohexyl)ethyldiethoxysilane, and combinations thereof. Examples of suitable unsaturated alkoxysilanes include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hexenyltrimethoxysilane, undecylenyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltriethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 3-acryloyloxypropyltriethoxysilane, and combinations thereof.

[0090] The (F) adhesion promoter may also include a reaction product or partial reaction product of one or more of these compounds. For example, in certain embodiments, the (F) adhesion promoter may include a reaction product or partial reaction product of vinyltriacetoxysilane and 3-glycidoxypropyltrimethoxysilane. Alternatively, or in addition, the (F) adhesion promoter may include an alkoxy- or alkenyl-functional siloxane.

[0091] Alternatively, the (F) adhesion promoter may comprise an epoxy-functional siloxane, such as the reaction product of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane, as described above, or a physical blend of a hydroxy-terminated polyorganosiloxane with an epoxy-functional alkoxysilane. The (F) adhesion promoter may comprise a combination of an epoxy-functional alkoxysilane and an epoxy-functional siloxane. For example, the (F) adhesion promoter may be exemplified by a mixture of 3-glycidoxypropyltrimethoxysilane and a reaction product of a hydroxy-terminated methylvinylsiloxane with 3-glycidoxypropyltrimethoxysilane, a mixture of 3-glycidoxypropyltrimethoxysilane and a hydroxy-terminated methylvinylsiloxane, or a mixture of 3-glycidoxypropyltrimethoxysilane and a hydroxy-terminated methylvinyl / dimethylsiloxane copolymer.

[0092] Alternatively, the (F) adhesion promoter may include a transition metal chelate. Suitable transition metal chelates include titanates, zirconates such as zirconium acetylacetonate, aluminum chelates such as aluminum acetylacetonate, and combinations thereof. Alternatively, the (F) adhesion promoter may include a combination of a transition metal chelate and an alkoxysilane (e.g., a combination of glycidoxypropyltrimethoxysilane and an aluminum chelate or a zirconium chelate).

[0093] The specific amount of (F) adhesion promoter present in the PSA composition, if utilized, depends on various factors, including the type of substrate and whether a primer is used. In certain embodiments, the (F) adhesion promoter is present in the PSA composition in an amount of 0 to 2 parts by weight per 100 parts by weight of component (A). Alternatively, the (F) adhesion promoter is present in the PSA composition in an amount of 0.01 to 2 parts by weight per 100 parts by weight of component (A).

[0094] In certain embodiments, the PSA composition further comprises a (G) vehicle. The (G) vehicle typically solubilizes the components of the PSA composition, and when the components are solubilized, the (G) vehicle can be referred to as a solvent. Suitable vehicles include both linear and cyclic silicones, organic oils, organic solvents, and mixtures thereof. A (G) vehicle is not required, but can optionally be utilized to apply the PSA composition to a substrate.

[0095] Typically, the (G) vehicle, when present in the PSA composition, is an organic liquid. Organic liquids include those considered to be oils or solvents. Organic liquids include, but are not limited to, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols with more than three carbon atoms, aldehydes, ketones, amines, esters, ethers, glycols, glycol ethers, alkyl halides, and halogenated aromatics. Hydrocarbons include isododecane, isohexadecane, Isopar L (C11-C13), Isopar H (C11-C12), hydrogenated polydecene, aromatic hydrocarbons, and halogenated hydrocarbons. Ethers and esters include isodecyl neopentanoate, neopentyl glycol heptanoate, glycol distearate, dicaprylyl carbonate, diethylhexyl carbonate, propylene glycol n-butyl ether, ethyl-3 ethoxypropionate, propylene glycol methyl ether acetate, tridecyl neopentanoate, propylene glycol methyl ether acetate (PGMEA), propylene glycol methyl ether (PGME), octyldodecyl neopentanoate, diisobutyl adipate, diisopropyl adipate, propylene glycol dicaprylate / dicaprate, octyl ether, and octyl palmitate. Additional organic fluids suitable as stand-alone compounds or formulation ingredients for the (G) vehicle include fats, oils, fatty acids, and fatty alcohols.(G) The vehicle may also be a 1 to 1,000 mm at 25°C vehicle such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, tetradecamethylhexasiloxane, hexadecamethylheptasiloxane, heptamethyl-3-{(trimethylsilyl)oxy}trisiloxane, hexamethyl-3,3,bis{(trimethylsilyl)oxy}trisiloxane pentamethyl{(trimethylsilyl)oxy}cyclotrisiloxane, as well as polydimethylsiloxane, polyethylsiloxane, polymethylethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, caprylyl methicone, and any mixture thereof. 2 The organopolysiloxane may be a low viscosity organopolysiloxane or a volatile methyl siloxane or a volatile ethyl siloxane or a volatile methylethyl siloxane having a viscosity in the range of 1 / 2 s. / sec.

[0096] In certain embodiments, the (G) vehicle is selected from polyalkylsiloxanes, tetrahydrofuran, mineral spirits; naphtha; alcohols such as methanol, ethanol, isopropanol, butanol, or n-propanol; ketones such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; aromatic hydrocarbons such as benzene, toluene, or xylene; aliphatic hydrocarbons such as heptane, hexane, or octane; glycol ethers such as propylene glycol methyl ether, dipropylene glycol methyl ether, propylene glycol n-butyl ether, propylene glycol n-propyl ether, or ethylene glycol n-butyl ether, or combinations thereof.

[0097] The amount of (G) vehicle depends on various factors, including the type of vehicle selected and the amount and type of other components present in the PSA composition. The (G) vehicle may be added during preparation of the PSA composition, for example, to aid in mixing and delivery. All or a portion of the (G) vehicle may optionally be removed after the PSA composition containing it has been prepared, before and / or simultaneously with the preparation of the PSA from the PSA composition. However, typically, the PSA composition does not contain a (G) vehicle, and therefore the PSA composition is a solvent-free PSA composition.

[0098] The PSA composition may optionally further comprise (H) a polyalkylsiloxane resin. The polyalkylsiloxane resin is an MQ resin consisting essentially of M and Q siloxy units. The M siloxy units may comprise an ethylenically unsaturated group bonded to a non-functional organic group such as silicon or an alkyl group.

[0099] The (H) polyalkylsiloxane resin can contain an average of 3 to 30 mole percent, alternatively 0.1 to 30 mole percent, alternatively 0.1 to 5 mole percent, or alternatively 3 to 100 mole percent, of silicon-bonded alkenyl groups. The mole percent of silicon-bonded alkenyl groups in the (H) polyalkylsiloxane resin is the ratio of the number of moles of alkenyl-containing siloxane units in the (H) polyalkylsiloxane resin to the total number of moles of siloxy units in the (H) polyalkylsiloxane resin multiplied by 100.

[0100] Methods for preparing such resins are well known in the art. For example, the resins can be prepared by treating a resin copolymer produced by the silica hydrosol capping process of Daudt et al. with at least one alkenyl-containing end-capping reagent. The method of Daudt et al. is disclosed in U.S. Pat. No. 2,676,182.

[0101] Typically, (H) polyalkylsiloxane resins containing less than 2% silicon-bonded hydroxyl groups can be prepared by reacting the product of Daudt et al. with an alkenyl-containing endblocking agent and an endblocking agent free from aliphatic unsaturation in an amount sufficient to provide 3 to 30 mole percent unsaturated organic groups in the final product. Examples of endblocking agents include, but are not limited to, silazanes, siloxanes, and silanes. Suitable endblocking agents are known in the art and are exemplified in U.S. Patent Nos. 4,584,355, 4,591,622, and 4,585,836. The resins can be prepared using a single endblocking agent or a mixture of such agents.

[0102] Other optional ingredients may be present in the PSA composition including, for example, reactive diluents, fragrances, preservatives, colorants, dyes, and fillers such as silica, quartz, carbon black, or chalk.

[0103] A method for preparing a PSA composition is also provided. The method includes combining components (A) through (C) together with any optional ingredients to obtain a PSA composition. Typically, (A) the silicate resin is placed directly into the PSA composition in the absence of any solvent, such that both the PSA composition and the method for preparing it are solvent-free. However, the ingredients can be combined in any manner and in any order of addition, optionally with stirring or other mixing. Because (A) the silicate resin is miscible with or compatible with the PSA composition, a solvent is not required.

[0104] The PSA composition can be prepared by a process comprising combining the ingredients at ambient or elevated temperature by any convenient means, such as mixing. (E) The inhibitor may be added before (C) the hydrosilylation reaction catalyst, for example, when the PSA composition is prepared at elevated temperature and / or when the PSA composition is prepared as a one-part composition.

[0105] Alternatively, for example, if the PSA composition is to be stored for an extended period of time before use, the PSA composition can be prepared as a multi-part composition. In multi-part compositions, the (C) hydrosilylation reaction catalyst is typically stored in a separate portion from any starting material having silicon-bonded hydrogen atoms, such as the (B) organosilicon compound, and the portions are combined immediately prior to use of the PSA composition. For example, a two-part composition can be prepared by combining starting materials, including the (A) silicate resin, the (B) organosilicon compound, and, optionally, one or more other additional starting materials described above, to form a base by any convenient means, such as mixing. The curing agent can be prepared by combining, if utilized, components (D) and (C) the hydrosilylation reaction catalyst, and, optionally, one or more other additional starting materials described above, by any convenient means, such as mixing. The starting materials can be mixed at ambient or elevated temperature. The (E) inhibitor can be included in one or more of the base, curing agent, or separate additional portions. (F) The adhesion promoter, if used, can be added to the base or as a separate additive. (H) The polyalkylsiloxane resin, if used, can be added to the base, the curing agent, or a separate additive. When a two-part composition is used, the weight ratio of the amount of base to the curing agent can range from 1:1 to 10:1. The PSA composition cures via a hydrosilylation reaction to form a pressure-sensitive adhesive. In certain embodiments, the pressure-sensitive adhesive formed by curing the PSA composition has at least some tack, which can be easily determined by contact or other known methods.

[0106] The above-described method may further include one or more additional steps. The PSA composition prepared as described above may be used to form an adhesive article, such as a pressure-sensitive adhesive (prepared by curing the PSA composition) on a substrate. Thus, the method may further include applying the PSA composition to a substrate.

[0107] The PSA composition can be applied to a substrate by any convenient means, for example, the pressure-sensitive adhesive curable composition can be applied to a substrate by a gravure coater, an offset coater, an offset gravure coater, a roller coater, a reverse roller coater, an air knife coater, or a curtain coater.

[0108] The substrate can be any material that can withstand the curing conditions (described below) used to cure the pressure-sensitive adhesive curable composition to form a pressure-sensitive adhesive on the substrate. For example, any substrate that can withstand heat treatment at temperatures of 120° C. or higher, or even 150° C. or higher, is suitable.

[0109] 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 (PET), 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); and 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 resin; phenoxy resin; cellulose such as triacetyl cellulose, diacetyl cellulose, and cellophane; fluorinated resins such as polytetrafluoroethylene;Examples of suitable thermoplastic elastomers include polystyrene, polyolefin, polyurethane, polyester, polyamide, polybutadiene, polyisoprene, and fluorocarbon elastomers, as well as copolymers and combinations thereof. Alternatively, the substrate can be a metal foil, such as aluminum foil or copper foil. The thickness of the substrate is not critical, but can range from 5 micrometers to 300 micrometers.

[0110] To improve bonding of the pressure-sensitive adhesive to the substrate, the method may optionally further comprise treating the substrate before applying the pressure-sensitive adhesive composition. Treatment of the substrate may be carried out by any convenient means, such as applying a primer or subjecting the substrate to a corona discharge treatment, etching, or plasma treatment before applying the pressure-sensitive adhesive composition to the substrate.

[0111] Coated articles, e.g., adhesive articles such as protective films, can be prepared by applying the above-described PSA composition to the above-described substrate. The method may optionally further comprise removing all or a portion of the solvent, if used, before and / or during curing. Solvent removal can be accomplished by any convenient means, such as heating the PSA composition at a temperature that will evaporate the solvent without completely curing it, e.g., at a temperature of 70°C to 120°C, alternatively 50°C to 100°C, alternatively 70°C to 80°C, for a time sufficient to remove all or a portion of the solvent (e.g., 30 seconds to 1 hour, alternatively 1 minute to 5 minutes). The method then further includes curing the PSA composition (which may remove some or all of the solvent when a drying step is performed) by heating at room temperature or at a temperature of 140°C to 220°C, alternatively 150°C to 220°C, alternatively 160°C to 200°C, and alternatively 165°C to 180°C for a time sufficient to cure the PSA composition (e.g., 30 seconds to 1 hour, alternatively 1 to 5 minutes). This forms a pressure-sensitive adhesive on the substrate. Drying and / or curing can be carried out by placing the substrate in an oven. The amount of PSA composition applied to the substrate will depend on the particular application, but may be sufficient to provide a pressure-sensitive adhesive thickness of 5 micrometers to 200 micrometers after curing; for protective films, the thickness may be 10 micrometers to 50 micrometers, alternatively 20 micrometers to 40 micrometers, alternatively 30 micrometers.

[0112] The methods described herein may optionally further include applying a removable release liner to the pressure-sensitive adhesive on the side opposite the substrate, for example, to protect the pressure-sensitive adhesive prior to use of the adhesive article.

[0113] The adhesive article (eg, protective film) prepared as described above is suitable for use in flexible OLED device fabrication processes as a protective film with low adhesion, high adhesion stability, and / or low migration.

[0114] For example, a method for fabricating a flexible OLED device can include forming an OLED module on a surface of a substrate, e.g., a passivation layer on the surface of the OLED module opposite the substrate, and applying a protective film prepared as described herein to the surface of the passivation layer opposite the OLED module.

[0115] Apart from adhesive articles, the coated substrates can be utilized in a variety of end uses. For example, the coated substrates can be utilized in coating applications, packaging applications, adhesive applications, fiber applications, fabric or textile applications, construction applications, transportation applications, electronics applications, or electrical applications. However, the curable compositions can be utilized for end uses other than preparing coated substrates, such as preparing articles such as silicone rubber.

[0116] 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. The specific components utilized in the examples are set forth in Table 1 below, followed by a description of the characterization and evaluation procedures also used in the examples. [Table 1] Nuclear Magnetic Resonance (NMR) spectroscopy

[0117] Nuclear magnetic resonance (NMR) spectra were obtained on a Varian EX-400 5 MHz Mercury spectrometer using CDCl3 solvent. 1 H-NMR, 13 C-NMR and 29 Chemical shifts in Si-NMR spectra are referenced to internal solvent resonances and reported relative to tetramethylsilane. Gel Permeation Chromatography (GPC)

[0118] Gel permeation chromatography (GPC) analysis is performed on an Agilent 1260 Infinity II chromatograph equipped with a triple detector consisting of a differential refractometer, an online differential viscometer, low-angle light scattering (LALS: detection angles of 15° and 90°), and a column (2 PL Gel Mixed C, Varian). Toluene (HPLC grade, Biosolve) is used as the mobile phase at a flow rate of 1 mL / min. Dynamic Viscosity (DV)

[0119] Dynamic viscosity (DV) is measured on a Brookfield DV-III Ultra Programmable Viscometer equipped with a CPA-52Z spindle using a sample volume of 0.5 mL at a temperature of 25°C. X-Ray Fluorescence (XRF)

[0120] X-ray fluorescence (XRF) is performed on an Oxford Instruments Lab-X3500 benchtop XRF analyzer. SiOZ content

[0121] The content of the SiOZ portion is 29 It can be calculated via Si-NMR. In particular, the molar content of the following siloxy units in each (A) silicate resin is determined: W=R3SiO 1 / 2 X1=R2(OZ)SiO 1 / 2 X2=R2SiO 2 / 2 Y1=R(OZ)2SiO 1 / 2 Y2 = R(OZ)SiO 2 / 2 Y3=RSiO 3 / 2 Z1=(OZ)3SiO 1 / 2 Z2=(OZ)2SiO 1 / 2 Z3=(OZ)SiO 3 / 2 Z4=SiO4 / 2 The OZ content relative to silicon atoms as mole % can be calculated with the following formula using the label for each peak in the formula corresponding to the integrated area under the peak corresponding to the label:

number

[0122] Peel adhesion (180°) was tested according to the PSTC-101 standard. Using a TMI peel and adhesion tester, 1-inch wide strips of adhesive coated on 2 mil polyester film were pulled from clean stainless steel or glass panels at 12 inches per minute. Adhesion

[0123] Tack was tested according to ASTM D2979. A PT-1000 probe tack tester was used to obtain tack measurements from samples coated on 2 mil polyester film. The dwell time was set at 1.0 second. Initial tack when evaluating various PSA compositions was determined by finger touch. Static shear (room temperature)

[0124] Static shear was tested according to ASTM D3654. 1 inch x 1 inch samples were applied to clean stainless steel panels. The samples were allowed to sit at room temperature for 60 minutes before testing began. After 60 minutes, the panels were placed in a shear bank apparatus. A 500 gram weight was suspended from each sample and a timer was reset to zero. The time to failure was recorded, and the test was stopped after 7 days if no failure occurred. Preparation Example 1: Silicate Resin (A1)

[0125] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 109.0 grams of silane compound 1 and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent was placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. Silicate resin (A1) was isolated from the reaction product by removing volatiles via roto-vap. Silicate resin (A1) was a colorless liquid with a DV of 39,000 cP at 25°C, a weight average molecular weight of 2,969, and a polydispersity of 1.46, each measured via GPC. The (A1) silicate resin had a SiOZ content of 23.5 mol % and a vinyl content of 6.46 wt %. Preparation Example 2: Silicate Resin (A2)

[0126] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 20.2 grams of silane compound 1, 80.6 grams of silane compound 2, and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent was placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. Silicate resin (A2) was isolated from the reaction product by removing volatiles via roto-vap. Silicate resin (A2) was a colorless gum that was liquid at 25°C and had a weight-average molecular weight of 4,329 and a polydispersity of 1.55, as measured by GPC. The (A2) silicate resin had a SiOZ content of 15.5 mol % and a vinyl content of 1.13 wt %. Preparation Example 3: Silicate Resin (A3)

[0127] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 10.4 grams of silane compound 1, 89.7 grams of silane compound 2, and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent was placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. Silicate resin (A3) was isolated from the reaction product by removing volatiles via roto-vap. Silicate resin (A3) was a colorless gum that was liquid at 25°C and had a weight-average molecular weight of 5,397 and a polydispersity of 1.70, as measured by GPC. The (A3) silicate resin had a SiOZ content of 14.35 mol % and a vinyl content of 0.68 wt %. Preparation Example 4: Silicate Resin (A4)

[0128] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 20.2 grams of silane compound 1, 131.1 grams of silane compound 2, and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent were placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. The silicate resin (A4) was isolated from the reaction product by removing volatiles via roto-vap. The silicate resin (A4) was a colorless liquid with a DV of 75,000 cP at 25°C, a weight average molecular weight of 5,450, and a polydispersity of 1.7149, each measured via GPC. The (A4) silicate resin had an SiOZ content of 19.12 mol% and a vinyl content of 1.12 wt%. Preparation Example 5: Silicate Resin (A5)

[0129] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 20.2 grams of silane compound 1, 130.1 grams of silane compound 2, and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent was placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. Silicate resin (A5) was isolated from the reaction product by removing volatiles via roto-vap. Silicate resin (A5) was a colorless liquid with a DV of 9,500 cP at 25°C, a weight average molecular weight of 7,380, and a polydispersity of 1.90, each measured via GPC. The (A5) silicate resin had a SiOZ content of 25.33 mol % and a vinyl content of 1.09 wt %. Preparation Example 6: Silicate Resin (A6)

[0130] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 10.4 grams of silane compound 1, 139.2 grams of silane compound 2, and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent was placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. Silicate resin (A6) was isolated from the reaction product by removing volatiles via roto-vap. Silicate resin (A6) was a colorless liquid with a DV of 9,700 cP at 25°C, a weight average molecular weight of 5,704, and a polydispersity of 1.73, each measured via GPC. The (A6) silicate resin had a SiOZ content of 24.75 mol % and a vinyl content of 0.45 wt %. Preparation Example 7: Silicate Resin (A7)

[0131] 200 g of solvent 1, followed by 300 g of MQ resin, were placed in a 2 L flask equipped with a magnetic stir bar. 3.8 grams of silane compound 1, 145.6 grams of silane compound 2, and 0.30 grams of catalyst were placed in the flask. Under nitrogen, the contents of the flask were stirred at 100°C, and the progress of the reaction in the flask was monitored via GC. After 10 hours, the contents of the flask were cooled to 23°C, and 0.5 grams of neutralizing agent was placed in the flask to neutralize the catalyst. The reaction product in the flask was filtered through a 1 micron filter to obtain a clear, viscous liquid. Silicate resin (A7) was isolated from the reaction product by removing volatiles via roto-vap. Silicate resin (A7) was a colorless liquid with a DV of 9,900 cP at 25°C, a weight average molecular weight of 5,820, and a polydispersity of 1.76, each measured via GPC. The (A7) silicate resin had a SiOZ content of 25.35 mol % and a vinyl content of 0.24 wt %. Screening Examples 1-58

[0132] Screening Examples 1-58 are PSA compositions containing the silicate resins prepared in Preparative Examples 1-7. The PSA compositions of Screening Examples 1-58 were prepared and cured, and the coating appearance was determined by visual inspection and tackiness via finger touch evaluation. Each PSA in Screening Examples 1-58 was prepared by combining a specific (A) silicate resin with a specific (B) organosilicon compound in a dental mixer cup in the absence of any solvent to obtain a sample. The sample was mixed at 2,000 rpm for 2 minutes until homogeneous. The (E) inhibitor was added to the cup, and the sample was then hand-mixed with a spatula. The (C) catalyst was then added to the cup and hand-mixed with a spatula. Finally, each sample was mixed again in the dental mixer at 2,000 rpm for 2 minutes until homogeneous. The target platinum level was 50.0 ppm. The target inhibitor / platinum ratio was 20.0 (mol / mol). Each PSA composition of Screening Examples 1-58 was coated onto a 2 mil thick polyester (PET) sheet using a 1.5 mil coating bar. Each sheet was then cured in a 150°C oven for 5 minutes. Tables 2-12 below describe the relative amounts of each component in grams utilized to prepare the PSA compositions of Screening Examples 1-58. Screening Examples 1-58 Various relative combinations of components, SiH-Vi molar ratios, for further evaluation of PSAs from the screened PSA compositions. [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7] [Table 8] [Table 9] [Table 10] [Table 11] [Table 12] Comparative Examples 1 to 4

[0133] Comparative Examples 1-4 (labeled C1-C4) are comparative PSA compositions. Table 13 below describes the relative amounts of each component in grams utilized to prepare the comparative PSA compositions of Comparative Examples 1-4. [Table 13] Examples 1 to 37 and Comparative Examples 1 to 4 and P1-P2: Coated substrates

[0134] Coated substrates are prepared using the PSAs of Examples 1-37 and Comparative Examples 1-4. The coated substrates include the PSAs formed from a particular screening example disposed on a substrate. The coated substrates are prepared as described above in the screening examples. In the examples, Example 1 is based on Screening Example 1. Example 2 is based on Screening Example 2, etc. The same applies to Comparative Examples 1-4. Screening Examples 38-58 were not further evaluated with respect to the properties of the PSAs formed therefrom. Comparative Examples P1 and P2 are commercially available PSAs. Comparative Example P1 is a solvent-free PSA formed via solvent exchange with xylene. Comparative Example P2 is a solvent-based PSA. The physical properties of each of the PSAs of Examples 1-37 and Comparative Examples 1-4 and P1 / P2, measured as described above, are set forth in Tables 14-20 below. [Table 14] [Table 15] [Table 16] [Table 17] [Table 18] [Table 19] [Table 20] Definitions and Use of Terms

[0135] The abbreviations used herein have the definitions in Table 21 below. [Table 21]

[0136] It is to be understood that the appended claims are not limited to the purposes of describing the Detailed Description and to the specific compounds, compositions, or methods described therein, and that variations may occur among specific embodiments within the scope of the appended claims.

Claims

1. 1. A pressure sensitive adhesive (PSA) composition comprising: (A) a silicate resin that is liquid at 25°C in the absence of any solvent and has an average of at least one silicon-bonded ethylenically unsaturated group per molecule; (B) an organosilicon compound having at least two silicon-bonded hydrogen atoms per molecule; (C) a hydrosilylation reaction catalyst; the silicate resin (A) is miscible with the PSA in the absence of any solvent; (A) The silicate resin has the average formula [W] ａ [X] ｂ [Y] ｃ [Z] ｄ wherein 0.1≦a≦0.5, 0<b<0.5, c is 0 or 0<c≦0.3, and 0.1≦d<0.9, with the proviso that a+b+c+d=1; [W] is [R 3 SiO 1 / 2 ], where each R is an independently selected hydrocarbyl group; [X] is [R ２ SiO １／２ (OZ)] ｂ’ [R ２ SiO ２／２ ] ｂ’’ wherein each R is independently selected and defined above, 0≦b′≦b, 0≦b″≦b, with the proviso that b′+b″=b, and each Z is independently H, an alkyl group, or a cation; [Y] is [RSi(OZ) ｃ’ O ３－ｃ’／２ wherein each R is independently selected, each Z is independently selected, and c′ is an integer from 0 to 2, and each siloxy unit denoted by subscript c in said (A) silicate resin is independently selected; [Z] is [Si(OZ) ｄ’ O ４－ｄ’／２ wherein each Z is independently selected and defined above, and subscript d' is an integer from 0 to 3, and each siloxy unit designated by subscript d in said (A) silicate resin is independently selected; provided that at least one R is an ethylenically unsaturated group; and the (A) silicate resin has a content of 12 to 80 mole percent SiOZ moieties, based on the total number of moles of Si in each molecule, where Z is independently selected from H, an alkyl group, or a cation; Component (B) is present in an amount such that the silicon-bonded hydrogen atoms (SiH) in component (B) are present in a ratio of 0.90:1 to 3:1 relative to the silicon-bonded ethylenically unsaturated groups in component (A).

2. A PSA composition as described in claim 1 that is substantially free of any solvents.

3. 3. A PSA composition according to claim 1 or 2 wherein subscript a is from 0.2 to 0.4, subscript b is from 0.1 to 0.3, subscript c is 0, and subscript d is from 0.4 to 0.

6.

4. A PSA composition according to any one of claims 1 to 3 wherein component (A) has a weight percent of silicon-bonded ethylenically unsaturated groups of from greater than 0 to 10, based on the total weight of component (A).

5. 5. The PSA composition according to claim 1, further comprising (E) a reaction inhibitor.

6. A method for preparing a PSA composition according to any one of claims 1 to 5, comprising the steps of: A method comprising combining components (A), (B), and (C) to obtain a PSA composition.

7. The method of claim 6 further comprising forming said (A) silicate resin from a solid silicate resin.

8. 7. The method of claim 6, wherein the method is free of any solvent and components (A), (B), and (C) are combined in the absence of any solvent.

9. A coated substrate, A substrate; and a coating formed from the PSA composition of any one of claims 1 to 5 disposed on said substrate.

10. 10. The coated substrate of claim 9, wherein the coating is formed by curing the PSA composition.

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