Silicone pressure-sensitive adhesive compositions and articles containing same

Abstract

The present invention relates to a silicone pressure sensitive adhesive composition comprising a boron-containing additive, the boron-containing compound being selected from the group consisting of boroxine-based compounds and borane-based compounds containing a boron-nitrogen covalent bond. The present invention also relates to articles, such as pressure sensitive adhesive tapes, comprising the silicone pressure sensitive adhesive composition.

Description

[Technical Field]

[0001] The present invention relates to silicone pressure-sensitive adhesive (PSA) compositions, particularly to silicone PSA compositions having improved adhesion, especially to low-energy surfaces. The present invention also relates to articles comprising the silicone pressure-sensitive adhesive compositions. [Background technology]

[0002] Pressure-sensitive adhesives (PSAs) are widely used in a variety of applications. Among the various PSAs, silicone PSAs have attracted increasing interest due to their resistance to extreme high and low temperatures, applicability to high- and low-energy surfaces, and excellent insulating properties. Although silicone PSAs can be applied to low-energy surfaces such as silicone, fluoropolymer, and polyolefin materials, they provide poor adhesion to such surfaces without surface treatment, typically exhibiting adhesion of less than 300 gf / in when peeled at a 180° angle, as determined by FINAT Test Method No. 1.

[0003] To increase the adhesion of silicone PSAs to such low-energy surfaces, additives such as trialkyl borates (often tri-n-butyl borate) have been incorporated into silicone PSAs. Although the addition of trialkyl borates can increase adhesion, when trialkyl borates are added in amounts traditionally used in PSAs, the resulting adhesion remains insufficient. Adhesion can increase with the amount of trialkyl borate. However, from the standpoint of compatibility with PSAs at high loadings, it is undesirable to use large amounts of trialkyl borates.

[0004] Thus, there is a need for the development of silicone pressure-sensitive adhesive compositions that contain alternative additives or additional systems that provide improved adhesion to low energy surfaces such as silicones, fluoropolymers, and polyolefin materials, especially at relatively low additive loadings. Summary of the Invention

[0005] In certain embodiments, the present invention provides a silicone pressure-sensitive adhesive composition comprising at least one boron-containing additive comprising a boron-containing compound selected from the group consisting of boroxine-based compounds and borane-based compounds containing a boron-nitrogen covalent bond.

[0006] In another embodiment, the present invention provides a silicone pressure-sensitive adhesive composition comprising at least one boron-containing additive comprising at least two members selected from the group consisting of: i) a boroxine-based compound, a borane-based compound containing a boron-nitrogen covalent bond, or a cyclic borate compound; ii) boric acid; and iii) a non-cyclic borate compound.

[0007] In yet another embodiment, the present invention provides an article comprising a silicone pressure-sensitive adhesive composition according to the above-described embodiment.

[0008] According to the present invention, silicone pressure-sensitive adhesive compositions containing the above-described boron-containing additives provide improved adhesion to low-energy surfaces, such as silicones, fluoropolymers, and polyolefin materials, under the same conditions, compared to corresponding silicone pressure-sensitive adhesive compositions containing conventional trialkyl borate additives. [Brief explanation of the drawings]

[0009] FIG. 1 is a bar graph showing the peel adhesion of adhesive tapes measured 20 minutes, 24 hours, and 72 hours after application onto silicone rubber, where the tapes were coated with a pressure-sensitive adhesive composition and either freshly prepared as described in Example 11 or aged for 8 weeks at room temperature and at 40° C.

[0010] FIG. 2 is a bar graph showing the peel adhesion of silicone pressure-sensitive adhesive compositions containing no additives or pressure-sensitive adhesive compositions containing various amounts of tributyl borate and trimethoxyboroxine.

[0011] FIG. 3 is a graph showing the variation in peel force over time at room temperature for the silicone pressure-sensitive adhesive tapes prepared in the Reference Example and Example 23.

[0012] FIG. 4 is a graph showing the variation in peel force over time at 40° C. for the silicone pressure-sensitive adhesive tapes prepared in the Reference Example and Example 23. DETAILED DESCRIPTION OF THE INVENTION

[0013] In the specification and claims of this application, the following terms and phrases shall be understood as indicated.

[0014] The singular forms "a," "an," and "the" include the plural unless the context clearly dictates otherwise, and references to particular values ​​include at least that particular value.

[0015] Any and all examples provided herein, or the use of exemplary language (e.g., "such as"), are intended merely to further clarify the invention and do not pose a limitation on the scope of the invention unless specifically stated.

[0016] No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0017] The terms "comprise," "include," "contain," and their grammatical equivalents are understood to be inclusive or open-ended terms and do not exclude additional, unrecited elements or method steps, but also include the more restrictive terms "consisting of" and "consisting essentially of."

[0018] Other than in the examples, or unless expressly stated otherwise, all numerical values ​​expressing amounts of materials, temperatures, lengths of time, quantified properties of materials, and the like set forth in the specification and claims are understood to be modified in all instances by the term "about," whether or not the term "about" is used in the context of the expression.

[0019] All numerical ranges recited herein are understood to include all subranges therein, as well as any combination of the various endpoints of such ranges or subranges.

[0020] It will be further understood that any compound, material, or substance explicitly or implicitly disclosed and / or claimed in the specification as belonging to a group of structurally, compositionally, and / or functionally related compounds, materials, or substances includes each individual representative of that group and all combinations thereof.

[0021] The term "alkyl," as used herein, refers to any monovalent saturated, straight- or branched-chain hydrocarbon group having up to about 30 carbon atoms, specifically 1 to about 20 carbon atoms, and more specifically 1 to about 10 carbon atoms, optionally substituted with one or more halogen atoms, such as fluorine, chlorine, bromine, and iodine atoms. Examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, hexyl such as n-hexyl, heptyl such as n-heptyl, octyl such as n-octyl, isooctyl, and 2-ethylhexyl, nonyl such as n-nonyl, and decyl such as n-decyl.

[0022] The term "alkoxy" as used herein refers to a monovalent group that is --O-alkyl, where alkyl is defined above.

[0023] The term "hydroxyalkyl," as used herein, refers to any alkyl group (as defined above) in which one or more hydrogen atoms have been replaced by the same number of hydroxyl groups. Examples of hydroxyalkyl include any alkyl group (as defined above) in which one of the hydrogen atoms attached to the terminal carbon atom has been replaced by a hydroxyl group, such as -alkyl-OH.

[0024] The term "alkoxyalkyl" as used herein means any alkyl group (as defined above) in which one or more hydrogen atoms are replaced by the same number of alkoxy (as defined above). Examples of alkoxyalkyl include any alkyl group (as defined above) in which one of the hydrogen atoms attached to the terminal carbon atom is replaced by one alkoxy, such as -alkyl-O-alkyl.

[0025] The term "aryl," as used herein, refers to any monovalent aromatic hydrocarbon radical having from about 6 to about 30 carbon atoms, specifically from about 6 to about 20 carbon atoms, and more specifically from about 6 to about 12 carbon atoms, including alkylaryl and arylalkyl. Examples of aryl include phenyl, naphthalenyl, benzyl, phenethyl, o-, m-, and p-tolyl, and xylyl.

[0026] The term "divalent linking group" as used herein means any divalent saturated straight- or branched-chain hydrocarbon group having up to about 30 carbon atoms, specifically 1 to about 20 carbon atoms, and more specifically 2 to about 10 carbon atoms, and optionally containing one or more heteroatoms selected from the group consisting of oxygen, nitrogen, silicon, sulfur, fluorine, chlorine, bromine, and iodine atoms. Examples of divalent linking groups include alkylene, oxyalkylene, and thioalkylene.

[0027] The term "cyclic," as used herein, refers to a compound containing any molecule having at least three atoms bonded together to form a ring (excluding phenyl rings), which may be, for example, a 3- to 10-membered ring, particularly a 4- to 8-membered ring, and more particularly a 4-, 5-, 6-, 7-, or 8-membered ring.

[0028] The term "acyclic" as used herein refers to a compound that does not contain a cyclic structure (other than a phenyl ring). For example, in some embodiments, acyclic compounds herein may contain a benzyl or phenyl group.

[0029] Viscosities described in this application are measured at 25°C using a Brookfield viscometer unless otherwise specified.

[0030] In one embodiment, the present invention provides a silicone pressure-sensitive adhesive composition comprising at least one boron-containing additive selected from the group consisting of boroxine-based compounds and borane-based compounds containing a boron-nitrogen covalent bond.

[0031] As used herein, the term "boroxine compound" refers to a compound having a six-membered ring formed by three alternating boron atoms and three oxygen atoms.

[0032] As used herein, a "borane-based compound containing a boron-nitrogen covalent bond" refers to a compound of the formula [ka] where the boranyl is directly bonded to at least one nitrogen atom via a covalent bond.

[0033] In certain embodiments, the boroxine-based compound may have the general formula (I): [ka] R in the formula 1 , R 2 and R 3 are each independently a hydrogen atom; hydroxyl; or a monovalent radical having up to about 30 carbon atoms, specifically up to about 20 carbon atoms, and more specifically up to about 10 carbon atoms, selected from the group consisting of alkyl, alkoxy, hydroxylalkyl, and alkoxyalkyl; or -R 8 -N(R 9 )(R 10 ) where R 8 is a direct bond or a divalent linking group, and R 9 and R 10 are each independently a hydrogen atom, alkyl, hydroxylalkyl, or alkoxyalkyl; preferably R 1 , R 2 and R3 are each independently a monovalent radical having up to about 20 carbon atoms and selected from the group consisting of alkoxy and alkoxyalkyl, or -R 8 -N(R 9 )(R 10 ) where R 8 is a direct bond, an alkylene group, or an oxyalkylene group (where the oxy group is bonded to the nitrogen atom via an alkylene), and R 9 and R 10 are each independently a hydrogen atom, an alkyl, or an alkoxyalkyl; more preferably a monovalent radical selected from the group consisting of alkoxy groups having up to about 10 carbon atoms, particularly 1 to about 8 carbon atoms, and more particularly 1 to about 6 carbon atoms, or -R 8 -N(R 9 )(R 10 ), where R 8 is a direct bond or an oxyalkylene group having from about 2 to about 6 carbon atoms, and R 9 and R 10 are each independently a hydrogen atom, an alkyl having 1 to about 6 carbon atoms, or an alkoxyalkyl having 2 to about 8 carbon atoms.

[0034] In one preferred embodiment, the boroxine-based compound may have the general formula (I-1): [ka] R in the formula 11 , R 12 and R 13 are each independently a monovalent radical selected from the group consisting of alkyl having up to about 20 carbon atoms, or -R 14 -N(R 15 )(R 16 ) where R 14 is an alkylene group, and R 15 and R 16 are each independently a hydrogen atom, alkyl, or alkoxyalkyl; and preferably, R 11 , R 12and R 13 are each independently alkyl having 1 to about 10 carbon atoms, preferably 1 to about 8 carbon atoms, and more preferably 1 to about 6 carbon atoms.

[0035] In another preferred embodiment, the boroxine-based compound may have the general formula (I-2):

[0036] [ka] R in the formula 17 are each independently an alkyl or alkoxyalkyl having up to 20 carbon atoms, or a hydrogen atom; preferably R 17 are each independently a hydrogen atom or alkyl having up to 10 carbon atoms, preferably 1 to about 8 carbon atoms, and more preferably 1 to about 6 carbon atoms.

[0037] Boroxine compounds may be prepared by various methods known in the art. For example, boroxine compounds may be prepared by heating a substituted boronic acid to form a boroxine compound with the corresponding substituent on the B atom; or by reacting a triorganoborane with boric acid to give the corresponding boroxine compound. As a further example, boroxine compounds having formula (I-1) can also be prepared by reacting boric acid with a trialkyl borate in a stoichiometric ratio.

[0038] In another embodiment, the borane-based compound containing a boron-nitrogen covalent bond may have the general formula (II): [ka] R in the formula 4 and R 5are each independently a monovalent radical having up to about 30 carbon atoms, specifically up to about 20 carbon atoms, and more specifically up to about 10 carbon atoms, selected from the group consisting of alkyl, alkoxy, hydroxylalkyl, and alkoxyalkyl, or -R 8 -N(R 9 )(R 10 ), where R 8 is a direct bond or a divalent linking group, and R 9 and R 10 are each independently a hydrogen atom, alkyl, hydroxylalkyl, or alkoxyalkyl; preferably R 4 and R 5 are each independently a monovalent radical having up to about 20 carbon atoms selected from the group consisting of alkoxy groups, or -R 8 -N(R 9 )(R 10 ), where R 8 is a direct bond or an alkylene group, and R 9 and R 10 are each independently a hydrogen atom, alkyl, or alkoxyalkyl; more preferably R 4 and R 5 are each independently an alkoxy group having up to about 10 carbon atoms, specifically 1 to about 8 carbon atoms, and more specifically 2 to about 6 carbon atoms, or -R 8 -N(R 9 )(R 10 ), where R 8 is a direct bond, and R 9 and R 10 are each independently a hydrogen atom or an alkyl having up to about 10 carbon atoms, specifically 1 to about 8 carbon atoms, and more specifically 1 to about 6 carbon atoms; optionally R 4 and R 5 together form a ring and comprise an alkylene group having up to about 10 carbon atoms, preferably about 2 to about 6 carbon atoms, and more preferably about 2 to about 5 carbon atoms, attached to the B atom of formula (II) through an oxygen atom; and R 6 and R 7are each independently alkyl, hydroxyalkyl, or alkoxyalkyl, each independently having up to about 30 carbon atoms, specifically up to about 20 carbon atoms, and more specifically up to about 10 carbon atoms, or a hydrogen atom; preferably R 6 and R 7 are each independently a hydrogen atom or alkyl having up to about 10 carbon atoms, specifically 1 to about 8 carbon atoms, and more specifically 1 to about 6 carbon atoms.

[0039] In one preferred embodiment, the borane-based compound containing a boron-nitrogen covalent bond may have the general formula (II-1): [ka] R in the formula 21 , R 22 , R 23 , R 24 , R 25 and R 26 are each independently alkyl, hydroxyalkyl, or alkoxyalkyl, each independently having up to about 20 carbon atoms, or a hydrogen atom; preferably R 21 , R 22 , R 23 , R 24 , R 25 and R 26 are each independently alkyl having up to about 10 carbon atoms, or a hydrogen atom; more preferably alkyl having up to about 10 carbon atoms, preferably 1 to about 8 carbon atoms, and more preferably 1 to about 6 carbon atoms.

[0040] In another preferred embodiment, the borane-based compound containing a boron-nitrogen covalent bond may have the general formula (II-2): [ka] R in the formula 27 and R 28are each independently an alkyl having up to 20 carbon atoms, or -R 31 -N(R 32 )(R 33 ), where R 31 is an alkylene group, and R 32 and R 33 are each independently a hydrogen atom, alkyl, or alkoxyalkyl; preferably R 27 and R 28 are each independently alkyl having up to 10 carbon atoms, preferably 1 to about 8 carbon atoms, and more preferably 1 to about 6 carbon atoms; optionally, R 27 and R 28 together form a ring and comprise an alkylene group having from about 1 to about 6 carbon atoms, preferably from about 2 to about 6 carbon atoms, and more preferably from about 2 to about 5 carbon atoms, bonded to the O atom of formula (II-2); preferably R 27 and R 28 together form a ring and contain CH2CH2-, -CH2CH2CH2-, -CH2CH(CH3)-, -CH(CH3)CH(CH3)-, -CH2CH(CH3)CH2-, or -CH2C(CH3)2CH2- bonded to the O atom of formula (II-2); and 29 and R 30 are each independently alkyl, hydroxyalkyl, or alkoxyalkyl, each independently having up to 20 carbon atoms or a hydrogen atom; preferably alkyl having up to about 10 carbon atoms or a hydrogen atom; more preferably alkyl having up to about 10 carbon atoms, preferably 1 to about 8 carbon atoms, and more preferably 1 to about 6 carbon atoms.

[0041] Borane-based compounds containing a boron-nitrogen covalent bond can be prepared by various methods known in the art. For example, a boron-nitrogen covalent bond in a borane-based compound can be introduced by reacting a borane halide with a corresponding secondary amine compound and replacing the halogen atom bonded to the boron atom with a corresponding amino group. Furthermore, a boron-oxygen bond in a borane-based compound having a boron-nitrogen covalent bond can be introduced, for example, by subjecting a tri(dialkylamino)borane compound to an alcohol-amine exchange reaction with an aliphatic alcohol compound. For example, a borane-based compound having formula (II-2) can be prepared by reacting tri(dimethylamino)borane with a monohydric alcohol in a stoichiometric ratio to form an acyclic product, or with an alkylene glycol in a stoichiometric ratio to form a cyclic product. References include Gerard W. et al., "The Chemistry of Certain Novel Organoboron Compounds," Chemistry and Industry, Inc., 292-3 (1958), which is incorporated herein by reference in its entirety.

[0042] The at least one boron-containing additive selected from boroxine-based compounds and borane-based compounds may be present in an amount of from about 0.01 to about 10 wt %, preferably from about 0.05 to about 9 wt %, and more preferably from 0.1 to about 8 wt %, based on the total weight of the silicone pressure-sensitive adhesive composition.

[0043] The boroxine-based compounds defined above under Formula (I) or the borane-based compounds containing a boron-nitrogen covalent bond defined under Formula (II) increase the peel adhesion of the silicone pressure-sensitive adhesive compositions of the present invention to silicone rubber by at least about 45%, in some embodiments by about 65% or more, and in further embodiments by about 80% or more, or even 100% or more, compared to conventional trialkyl borate additives under the same conditions.

[0044] In another embodiment, the at least one boron-containing additive is: i) boroxine compounds, borane compounds containing a boron-nitrogen covalent bond, or cyclic borate compounds; ii) boric acid; and iii) Acyclic borate compounds The present invention includes at least two elements (hereinafter referred to as a first element and a second element) selected from the group consisting of:

[0045] The term "cyclic borate," as used herein, refers to a cyclic ester or salt of boric acid (HBO), alkylboric acid, or arylboric acid. The terms "alkylboric acid" and "arylboric acid," as used herein, refer to alkyl- or aryl-substituted boric acid compounds in which one of the three hydroxyl groups bonded to the boron atom is replaced with an alkyl having 1 to about 6 carbon atoms or an aryl having about 6 to about 12 carbon atoms, respectively. Cyclic borates may contain one, two, or three rings per molecule.

[0046] In one embodiment, the cyclic borate compound may have the general formula (III): [ka] R in the formula 34 and R 35 are each independently an alkyl having 1 to 6 carbon atoms or an aryl having 6 to 12 carbon atoms, and optionally R 34 and R 35 Let's get together and have a ceremony -OL 3 forming a ring containing a divalent group having -CH2-, wherein -L 3 - group is bonded to the B atom of formula (III) via an oxygen atom; L 1 , L 2 and L 3 are each independently of the formula -[C(O)] m C n H 2n -, where m is 0 or 1 and n is an integer from 0 to 4, with the proviso that R34 and R 35 together form a ring, L 1 , L 2 and L 3 m is defined as 0 for at least one of the following:

[0047] In one embodiment, the cyclic borate compound is selected from compounds having formula (III), wherein R 34 and R 35 are each independently an alkyl having 1 to 6 carbon atoms, preferably an alkyl having 1 to 4 carbon atoms; L 1 and L 2 are each independently of the formula -[C(O)] m C n H 2n -, where m is 0 or 1 and n is an integer from 0 to 3, provided that m+n is at least 1. Preferably, L 1 and L 2 are each independently a divalent group -CH2-, -CH2CH2-, -CH(CH3)-, -C(CH3)2-, -C(O)-, or -C(O)CH2-.

[0048] In another embodiment, the cyclic borate compound may have the general formula (III-1): [ka] L in the ceremony 1 and L 2 are each independently of the formula -[C(O)] m C n H 2n -, where m is 0 or 1 and n is an integer from 0 to 3, provided that m+n is at least 1; preferably, L 1 and L 2 are each independently a divalent group -CH2-, -CH2CH2-, -CH(CH3)-, -C(CH3)2-, -C(O)-, or -C(O)CH2-; L 3is -CH2-, -CH2CH2-, -CH(CH3)-, or -C(CH3)2-.

[0049] Cyclic borate compounds can be prepared, for example, by reacting boric acid, alkylboric acid (such as methylboric acid or ethylboric acid), or arylboric acid (such as phenylboric acid) with an amine compound containing one to three hydroxyl groups, one or two carboxyl groups, or a combination thereof. Examples of such amine compounds include, but are not limited to, tri(hydroxyalkyl)amines such as triethanolamine, tri-n-propanolamine, or tri-isopropanolamine; hydroxylalkyliminodicarboxylic acids such as (2-hydroxyethyl)iminodiacetic acid; and alkyliminodicarboxylic acids such as N-methyliminodiacetic acid or N-ethyliminodiacetic acid.

[0050] The term "acyclic borate," as used herein, refers to acyclic compounds derived from boric acid, typically trialkyl borates, which are well known in the art. Each alkyl in the trialkyl borate can independently have from 1 to about 20 carbon atoms, specifically from 1 to about 10 carbon atoms, and more specifically from 1 to about 6 carbon atoms. The term "trialkyl borate," as used herein, includes both a single trialkyl borate and a mixture of trialkyl borates having different alkyl groups. Examples of acyclic borate compounds include, but are not limited to, trimethyl borate, triethyl borate, tri-n-propyl borate, tri-iso-propyl borate, tri-n-butyl borate, tri-iso-butyl borate, trioctyl borate, tridodecyl borate, trioctadecyl borate, or combinations thereof; trimethyl borate, triethyl borate, tri-n-propyl borate, tri-iso-propyl borate, tri-n-butyl borate, tri-iso-butyl borate, or combinations thereof are preferred.

[0051] Acyclic borate compounds and boric acid may be collectively referred to herein as acyclic boron compounds.

[0052] In one embodiment, the boron-containing additive comprises one or more compounds of i) above as a first component and ii) above as a second component; or one or more compounds of i) above as a first component and one or more compounds of iii) above as a second component; or ii) above as a first component and one or more compounds of iii) above as a second component. Examples of boron-containing additives according to this embodiment include, but are not limited to, a combination of a boroxine compound having formula (I) as a first component and a trialkyl borate as a second component; a combination of a boroxine compound having formula (I) as a first component and boric acid as a second component; a combination of a borane compound having a boron-nitrogen covalent bond and formula (II) as a first component and a trialkyl borate as a second component; a combination of a borane compound having a boron-nitrogen covalent bond and formula (II) as a first component and boric acid as a second component; a combination of boric acid as a first component and a trialkyl borate as a second component; a combination of a cyclic borate as a first component and a trialkyl borate as a second component; and a combination of a boroxine compound having formula (I) as a first component and a borane compound having a boron-nitrogen covalent bond and formula (II) as a first component and a trialkyl borate as a second component. The boron-containing additives according to this embodiment provide silicone pressure sensitive adhesive compositions with improved adhesion to low energy surfaces such as silicones, fluoropolymers, and polyolefin materials.

[0053] In one embodiment, the boron-containing additive comprises a boroxine compound having formula (I), a cyclic borate compound, boric acid, or a combination thereof as a first component; and a non-cyclic borate compound selected from trialkyl borates as a second component. Examples of boron-containing additives according to this embodiment include, but are not limited to, a combination of a boroxine compound having formula (II) as a first component and a trialkyl borate as a second component; a combination of boric acid as a first component and a trialkyl borate as a second component; and a combination of a cyclic borate compound having formula (III) as a first component and a trialkyl borate as a second component. The two components in the boron-containing additive according to this embodiment provide a synergistic effect in improving the adhesion of silicone pressure-sensitive adhesive compositions to low-energy surfaces such as silicones, fluoropolymers, and polyolefin materials.

[0054] In another embodiment, the boron-containing additive comprises boric acid, a cyclic borate compound having formula (III-I), or a combination thereof, as a first component, and an acyclic borate compound, particularly a trialkyl borate, as a second component. These two components achieve a significant synergistic effect in improving the adhesion of silicone pressure-sensitive adhesive compositions to low-energy surfaces, such as silicones, fluoropolymers, and polyolefin materials.

[0055] In another embodiment, the boron-containing additive comprises a boroxine compound having formula (II) as a first component and a trialkyl borate as a second component. These two components achieve a significant synergistic effect in improving the adhesion of the silicone pressure-sensitive adhesive composition to low-energy surfaces such as silicones, fluoropolymers, and polyolefin materials. In addition, the silicone pressure-sensitive adhesive composition containing the boron-containing additive according to this embodiment has a transparent appearance and long-term stability.

[0056] The weight ratio of the first component to the second component can vary over a wide range. Typically, the weight ratio (first component:second component) can range from about 1:100 to about 1:1, preferably from about 1:70 to about 1:1. The weight ratio (first component:second component) can be, for example, from about 1:60 to about 1:2, such as from about 1:50 to about 1:3, or in another embodiment, from about 1:40 to about 1:4.

[0057] In other embodiments, the boron-containing additive may contain all three of the above elements i), ii), and iii). Preferably, the acyclic borate compound iii), particularly the trialkyl borate, is present in an amount of about 50 wt% to about 99 wt%, specifically about 60 wt% to about 98 wt%, based on the total weight of the boron-containing additive.

[0058] In addition to at least one boron-containing additive, the silicone pressure-sensitive adhesive composition further comprises a silicone pressure-sensitive adhesive (silicone PSA). The silicone PSA may be any known in the art. Silicone PSAs generally comprise a polyorganosiloxane rubber and a silicone resin; and may optionally further comprise a curing catalyst, a solvent, a filler, and other optional ingredient(s) as required. The pressure-sensitive adhesive composition may be cured by a radical reaction or a hydrosilylation reaction.

[0059] The term "polyorganosiloxane gum" as used herein refers to polyorganosiloxanes having a viscosity of at least about 300,000 cps, specifically from about 500,000 cps to about 150,000,000 cps, more specifically from about 1,000,000 cps to about 100,000,000 cps, and even more specifically from about 2,000,000 cps to about 80,000,000 cps. The polyorganosiloxane gum may have a number average molecular weight of at least 100,000, specifically from about 120,000 to about 1,000,000, and more specifically from about 150,000 to about 800,000. The polyorganosiloxane gum may contain one or more functional groups selected from the group consisting of hydroxyl, alkenyl such as vinyl, alkoxy, alkoxyalkenyl and hydride.

[0060] Suitable polyorganosiloxane gums may have the general formula: R2R F SiO(R2SiO) x (RR F SiO) y SiR F R2(IV) wherein each R is independently a monovalent hydrocarbon group having up to about 12 carbon atoms, e.g., an alkyl group having from 1 to about 6 carbon atoms, such as methyl, ethyl, and propyl; or an aryl group having from about 6 to about 12 carbon atoms, such as phenyl; R F are each independently an alkenyl, alkoxy, or alkoxyalkenyl group, such as hydroxyl, halide, or vinyl, having from 1 to about 10 carbon atoms; x and y are independently a positive number of 0 or up to 10,000, specifically 1 to about 8,000, and more specifically 10 to about 5,000, with the proviso that x+y is at least 1,000.

[0061] Examples of polyorganosiloxane gums include, but are not limited to, polydimethylsiloxane, and hydroxyl-terminated polydimethylsiloxane-polydiphenylsiloxane copolymers, and vinyl-functionalized polyorganosiloxanes.

[0062] The term "silicone resin" as used herein means a resin containing at least one (RSiO 3 / 2 ) or (SiO 4 / 2 M=RSiO. In some embodiments, the silicone resin has the formula M=RSiO. 1 / 2 and at least one M unit of the formula T=RSiO 3 / 2 is the T unit and the formula Q = SiO 4 / 2 and optionally comprising at least one unit selected from the group consisting of Q units of the formula D=RSiO 2 / 2 wherein each R is independently a monovalent hydrocarbon group of 1 to about 6 carbon atoms, e.g., alkyl of 1 to about 4 carbon atoms, such as methyl, or phenyl.

[0063] The molecular weight of the silicone resin is not limited and may vary over a wide range. For example, the silicone resin may have a number average molecular weight of about 300 or greater, specifically from about 500 to about 50,000, and more specifically from about 1,000 to about 30,000.

[0064] In one embodiment, the silicone resin is an MQ resin comprising at least one Q unit and at least one M unit. The ratio of M units to Q units can be, for example, from about 0.5:1 to about 1.5:1, specifically from about 0.6:1 to about 1.2:1, more specifically from about 0.7:1 to about 1.1:1, and even more specifically from about 0.85:1 to about 1.0:1. The MQ resin can further comprise D units, T units, or both, for example, in an amount of 20 mol % or less, specifically 10 mol % or less, and more specifically 5 mol % or less of the total number of units in the silicone resin.

[0065] Generally, MQ resins may be functionalized with hydroxyl groups. The total hydroxyl content in the MQ resin is typically about 1-10 wt%, specifically about 2-8 wt%, and more specifically about 2-5 wt%. The MQ resin may also optionally be functionalized with one or more functional groups selected from the group consisting of alkenyl, such as vinyl, alkoxy, alkoxyalkenyl, and hydride.

[0066] In another embodiment, the silicone resin is an MT resin containing at least one T unit and at least one M unit, preferably an MDT resin containing at least one D unit in addition to T and M units. MT and MDT resins may also contain Q units. The amount of T and D units (if present) may be, for example, 60 mol % or more, specifically 70 mol % or more, and more specifically 80 mol % or more of the total number of units in the silicone resin.

[0067] In an MT or MDT resin, the molar ratio of hydrocarbon groups "R" to Si atoms (R / Si) is typically from about 1.0:1 to about 1.8:1, specifically from about 1.1:1 to about 1.7:1, and more specifically from about 1.2:1 to about 1.6:1. In some instances, the hydrocarbon groups "R" include methyl and phenyl (Ph), with a phenyl to hydrocarbon group ratio (Ph / R) of, for example, from about 0.1:1 to about 0.8:1, preferably from about 0.2:1 to about 0.7:1, and more preferably from about 0.2:1 to about 0.6:1.

[0068] The MT or MDT resin may optionally be functionalized with one or more functional groups selected from the group consisting of hydroxyl, alkenyl such as vinyl, alkoxy, alkoxyalkenyl, and hydride.

[0069] The silicone resin may be present in the silicone pressure-sensitive adhesive composition in an amount of from about 50 to about 150 parts by weight, specifically from about 70 to about 130 parts by weight, and more specifically from about 80 to about 120 parts by weight, per 100 parts by weight of the polyorganosiloxane rubber.

[0070] Many suitable silicone pressure sensitive adhesives are commercially available, including both polyorganosiloxane rubbers and silicone resins. Examples of these silicone pressure sensitive adhesives include, but are not limited to: SilGrip from Momentive Performance Materials; TM series, e.g. SilGrip TM These include PSA5080, PSA510, PSA518, PSA529, PSA590LD, PSA595, PSA610, PSA6573A, PSA6574, PSA810, PSA820 and PSA915.

[0071] The silicone pressure-sensitive adhesive composition of the present application preferably contains a curing catalyst to improve performance such as cohesive strength, although in some embodiments, a catalyst may not be used. The curing catalyst used in the present application is not particularly limited and is typically selected depending on the curing mechanism of the silicone pressure-sensitive adhesive. For example, if the silicone pressure-sensitive adhesive is cured by a radical reaction, the curing catalyst may include a peroxide, such as an inorganic peroxide or an organic peroxide. Examples of peroxides include, but are not limited to, aryl peroxides such as dibenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and combinations thereof. If the silicone pressure-sensitive adhesive is cured by a hydrosilylation reaction, the curing catalyst may include, for example, a noble metal catalyst, such as one using ruthenium, rhodium, palladium, osmium, iridium, and platinum, as well as combinations of these metals. Examples of hydrosilylation catalysts include, but are not limited to, Ashby's catalyst, Lamoreax's catalyst, Karstedt's catalyst, Modic's catalyst, and Jeram's catalyst, as well as combinations thereof.

[0072] The cure catalyst may be present in an amount of up to about 10 parts by weight, preferably from about 0.1 to about 8 parts by weight, and more preferably from about 0.5 to about 5 parts by weight, per 100 parts by weight of the polyorganosiloxane rubber.

[0073] A suitable solvent can be included to adjust the viscosity of the silicone pressure-sensitive adhesive composition, but solvent-free silicone pressure-sensitive adhesives are also applicable in this application. Examples of solvents include, but are not limited to, aromatic solvents such as toluene and xylene, aliphatic solvents such as hexane and octane, and isoparaffins, ketones such as methyl ethyl ketone and methyl isobutyl ketone, esters such as ethyl acetate and isobutyl acetate, and ethers such as diisopropyl ether and 1,4-dioxane, or combinations thereof. The amount of solvent typically depends on the viscosity of the rubber and the means for applying the silicone pressure-sensitive adhesive composition. In some cases, a solvent content of about 40% to about 70% by weight provides a solution with a viscosity suitable for coating. The solvent may be removed in a drying process at a relatively low temperature before curing the silicone PSA composition.

[0074] Examples of fillers may include, but are not limited to, quartz powder, zinc oxide, aluminum hydroxide, titanium dioxide, precipitated calcium carbonate, or combinations thereof to increase cohesive strength and reduce cost. The amount of filler may vary over a wide range depending on the silicone PSA, the nature of the filler, and the intended use. For example, the filler may be present in an amount of 0 to about 150 parts by weight, and preferably about 1 to about 100 parts by weight, per 100 parts by weight of polyorganosiloxane rubber.

[0075] Other optional ingredients may include, for example, condensation accelerators for accelerating the condensation reaction of silanol groups, such as dibutyltin diacetate; non-reactive polyorganosiloxanes, such as polydimethylsiloxane resins and silsesquioxane resins; antioxidants, such as phenol-based, quinoline-based, amine-based, phosphorus-based, phosphite-based, sulfur-based, and thioether-based antioxidants; light stabilizers, such as triazole-based and benzophenone-based light stabilizers; flame retardants, such as phosphate ester-based, halogen-based, phosphorus-based, and antimony-based flame retardants; and dyes and pigments.

[0076] Several optional additives are commercially available, including but not limited to AnchorSil™, a silicone PSA additive for improving adhesion to substrates, particularly polyester substrates. TM 2000, SilForce TM SL6020 or SilForce TM SS4300C or SilQuest TM Adhesion promoters such as A-186 silane; and SilGrip TM It includes silicone resin additives for tack control, such as SR500 resin and SR545 resin, all available from Momentive Performance Materials.

[0077] The silicone pressure-sensitive adhesive compositions described herein can have improved peel adhesion to low-energy surfaces such as silicones, fluoropolymers, and polyolefin materials. In one embodiment, the low-energy surface can be silicone rubber. The adhesion to silicone rubber can be at least about 660 gf / inch peeled at a 180° angle, as determined by FINAT Test Method No. 1, preferably from about 700 gf / inch to about 1500 gf / inch, more preferably from about 800 gf / inch to about 1400 gf / inch, and even more preferably from about 1000 gf / inch to about 1300 gf / inch.

[0078] The silicone pressure-sensitive adhesive composition according to the present invention may be prepared by a process comprising mixing at least one boron-containing additive with a polyorganosiloxane rubber and a silicone resin, optionally with any of the optional components described herein above, such as a curing catalyst, a solvent, a filler, and other additives. This mixing may be carried out at room temperature or at an elevated temperature not exceeding 50°C, such as about 30°C to about 45°C, for a time effective to obtain a homogeneous mixture, for example, from a few seconds to a few hours. When two or more boron-containing additives are used, they may be added together or separately. The components to be mixed may be added in any order. For example, in one embodiment, the boron-containing additive may be added together or separately with the curing catalyst to a dispersion of the polyorganosiloxane rubber and the silicone resin, with or without a solvent; or the boron-containing additive may be mixed with the polyorganosiloxane rubber, and then the silicone resin and the curing catalyst, with or without a solvent, may be added thereto, simultaneously or sequentially. In a particular embodiment, the process for preparing the adhesive composition includes dispersing the polyorganosiloxane rubber and the silicone resin in a solvent, preferably an organic solvent such as toluene, xylene, heptane, or a combination thereof; and adding the boron-containing additive and the curing catalyst, optionally along with fillers or other additives, to the dispersion.

[0079] In another embodiment, the present invention provides an article, such as a pressure-sensitive adhesive tape, comprising the silicone pressure-sensitive adhesive composition described herein. The pressure-sensitive adhesive tape may be made by applying the silicone pressure-sensitive adhesive composition to a substrate, such as a rigid substrate or a flexible substrate, such as a polymeric substrate. Examples of polymeric substrates include, but are not limited to, polyester substrates such as polyethylene terephthalate or polybutylene terephthalate. The substrate may be used as is. Alternatively, the substrate may be pre-treated, for example, with corona; or with Momentive Performance Materials' SilForce adhesive. TM SS4191A and SilForceTM It may be coated with a primer such as SS6800.

[0080] Because the silicone pressure-sensitive adhesive compositions described herein have improved adhesion to low-energy surfaces such as silicone, fluoropolymer, and polyolefin materials, pressure-sensitive adhesive tapes containing such compositions can be widely used for bonding materials with low-energy surfaces, particularly silicone materials. Thus, the present invention further relates to articles comprising the silicone pressure-sensitive adhesive compositions described herein on low-energy surfaces such as silicone, fluoropolymer, and polyolefin materials, particularly silicone rubber.

[0081] Example The present invention will be described in more detail with reference to examples, which should not be construed as limiting the scope of the present invention. In the following description, "parts" and "%" mean "parts by weight" and "% by weight" unless otherwise specified. Also, unless otherwise specified, all viscosities were measured at 25°C using a Brookfield rotational viscometer and are reported in centipoise (cps).

[0082] Preparation Example 1 - Synthesis of dimethyldibutoxyboranylamine [ka] In a fume hood, tris(dimethylamino)borane (1.00 g, 0.007 mol, Sigma-Aldrich) and n-BuOH (1.04 g, 0.014 mol) were placed in a 25 mL flask at room temperature. Upon shaking, gas evolved and escaped from the flask. The reaction was continued for approximately 1 day until gas evolution ceased. A clear liquid was obtained and ready for use.

[0083] Preparation Example: Synthesis of 2-dimethyldioxaborolanylamine [ka] In a fume hood, tris(dimethylamino)borane (1.00 g, 0.007 mol, Sigma-Aldrich) and ethylene glycol (0.43 g, 0.007 mol) were placed in a 25 mL flask at room temperature. Upon shaking, gas evolved and escaped from the flask. The reaction was continued for approximately 1 day until gas evolution ceased. A white solid was obtained and was ready for use.

[0084] Preparation Example 3 - Synthesis of tetraacetyl diborate [ka] Acetic anhydride (24.4 g, 0.24 mol, Sinopharm) and boric acid (4.8 g, 0.08 mol, Sinopharm) were placed in a 100 ml three-neck flask equipped with a mechanical stirrer and a thermocouple. The temperature was gradually increased to 59 °C using a hot water bath. After the hot water bath was removed, the temperature continued to rise spontaneously from 59 °C to 60.5 °C over approximately 10 minutes. The temperature was then immediately reduced to 55 °C using a cold water bath. The reaction stabilized at 59–60 °C and was refluxed for 1 hour to complete the reaction.

[0085] The resultant was cooled to 5°C, vacuum filtered and washed with 1:1 heptane / ethyl acetate. After drying in an oven at 40°C, the product was obtained in a yield of about 5g.

[0086] The boron-containing compounds used in the following examples are listed in Table 1 below.

[0087] [Table 1] JPEG0007795545000014.jpg233162

[0088] General Procedure for Preparing Silicone Pressure Sensitive Adhesive Compositions The boron-containing additive in the amounts shown in the following examples, 1.5 parts by weight of benzoyl peroxide, and 1.2 parts by weight of SR545 silicone resin additive (Momentive Performance Materials, Inc.) were added to 100 parts by weight (dry weight) of a toluene solution of a silicone pressure-sensitive adhesive, SilGrip TM The mixture was uniformly dispersed in PSA610 (Momentive Performance Materials) to obtain a silicone pressure-sensitive adhesive composition.

[0089] General Procedure for Preparing Silicone Pressure-Sensitive Adhesive Tapes A silicone pressure-sensitive adhesive composition with a 40% solids content was prepared using SilForce TM The adhesive was applied to a 25 μm PET thin film precoated with SS4191A primer (Momentive Performance Materials), dried at 85°C for 2 minutes, and then cured at 170°C for 2 minutes to yield a silicone pressure-sensitive adhesive tape. The thickness of the dried and cured adhesive composition on the tape was 25 μm.

[0090] Test method for peel adhesion (180 degrees) to silicone rubber Peel adhesion (180°) was measured according to FINAT Test Method No. 1 at 50% relative humidity and 25°C. A 25 mm (1 inch) wide silicone pressure-sensitive adhesive tape was applied to vulcanized silicone rubber LSR2640 (Momentive Performance Materials) and pressed back and forth once with a 2 kg roller at a speed of 300 mm / min. After 20 minutes and 72 hours, the tape was peeled from the silicone rubber at an angle of 180° at a speed of 300 mm / min, and the peel adhesion was measured.

[0091] Examples 1 to 10 Silicone pressure-sensitive adhesive compositions were prepared using 6 parts by weight of each of the additives shown in Table 2 below, and the adhesive compositions were coated onto thin films of PET using the general procedure described above to prepare silicone pressure-sensitive adhesive tapes. The tapes were tested for peel adhesion at 180 degrees after 20 minutes and 72 hours.

[0092] [Table 2]

[0093] It can be seen from Table 2 that Compounds 2 through 6 alone provide silicone pressure-sensitive adhesive compositions with significantly improved peel adhesion to silicone rubber compared to Compound 1 under the same conditions.

[0094] Examples 11 to 19 Silicone pressure-sensitive adhesive compositions were prepared using 0.17 parts by weight of each of the additives shown in Table 3 below in combination with 6 parts by weight of Compound 1, and the adhesive compositions were coated onto thin films of PET using the general procedure described above to prepare silicone pressure-sensitive adhesive tapes. The tapes were then tested for peel adhesion at 180 degrees after 20 minutes and 72 hours, respectively.

[0095] [Table 3]

[0096] From Tables 2 and 3, it can be seen that compounds 2, 7, 8, and 9, each combined with compound 1, achieved a synergistic effect, since all of these combinations resulted in silicone pressure-sensitive adhesive compositions with higher peel adhesion to silicone rubber than the corresponding adhesion obtained when they were used alone. Combinations of compounds 2, 8, and 9 with compound 1 unexpectedly achieved further improved peel adhesion to silicone rubber of greater than 1000 gf / inch. In terms of appearance, silicone pressure-sensitive adhesive compositions using compound 2 were transparent when combined with compound 1. Compounds 7, 8, and 9, when used in combination with compound 1, were less transparent than compound 2, likely due to their polarity.

[0097] Example 20 The silicone pressure-sensitive adhesive composition prepared in Example 11 was aged for 8 weeks at room temperature and at 40° C. The changes in viscosity and appearance of the adhesive composition over time are shown in Table 4 below.

[0098] The silicone pressure-sensitive adhesive composition after 8 weeks of aging was coated onto a thin film of PET using the general procedure described above to prepare silicone pressure-sensitive adhesive tapes. The adhesive tapes were then tested for peel adhesion to silicone rubber at 180 degrees after 20 minutes, 24 hours, and 72 hours. The peel adhesion results for the aged adhesive compositions are shown in Figure 1, compared to freshly prepared adhesive compositions that had not been aged. In Figure 1, in each of three sets of three bars, the left bar represents a fresh sample without aging, the middle bar represents a sample aged at room temperature, and the right bar represents a sample aged at 40°C.

[0099] [Table 4]

[0100] As can be seen from Table 4, the viscosity and appearance of the composition remained substantially unchanged over time, both at room temperature and at an elevated temperature of 40°C.

[0101] Furthermore, as can be seen from Figure 1, the peel adhesion to silicone rubber obtained from the freshly prepared samples without aging and the samples aged at different temperatures (room temperature and elevated 40°C) was virtually the same.

[0102] All the above results demonstrate that the silicone pressure-sensitive adhesive composition of the present invention had excellent stability at both room temperature and elevated storage temperatures.

[0103] Examples 21 to 26 Silicone pressure-sensitive adhesive compositions were prepared using various amounts of Compound 2 in combination with Compound 1, as shown in Table 5. Using the general procedure described above, the adhesive compositions were coated onto thin PET films to prepare silicone pressure-sensitive adhesive tapes. The tapes were then tested for peel adhesion at 180 degrees after 20 minutes and 72 hours, respectively. The results are shown in Table 5 and Figure 2.

[0104] [Table 5]

[0105] Surprisingly, as shown in Table 5 and depicted in Figure 2, it was found that the improvement in peel adhesion to silicone rubber provided by Compound 2 was not proportional to the amount. The maximum improvement in peel adhesion provided by Compound 2 was achieved at a very low weight ratio level of about 1:35 (Compound 2:Compound 1). This technical effect is advantageous for further reducing the amount of additive added to achieve the desired peel adhesion to low-energy surfaces.

[0106] Example 27 Each of the silicone pressure-sensitive adhesive tapes prepared according to the Reference Example and Example 23 was adhered to a fluorine release film FL132 (Housewell) to form a laminate. The laminate was then aged at room temperature and at 40°C, and then tested weekly at room temperature for peel force (180°) to the release liner FL132 according to FINAT Test Method No. 3 (slow peel force) using the procedure described above.

[0107] The laminate was secured with double-sided adhesive over the entire test area of ​​the laminate and pressed back and forth once with a 2 kg roller at a speed of 300 mm / min. The laminate was then pulled apart at an angle of 180 degrees at a speed of 300 mm / min and the peel force required to separate the release film from the pressure-sensitive adhesive tape was measured.

[0108] The measured peel force results are presented in Figure 3 (room temperature) and Figure 4 (at 40°C). These results demonstrate that the silicone pressure-sensitive adhesive compositions of the present invention have more adequate peel force than conventional release films, and that the peel force remains substantially stable over time at room temperature and at an elevated temperature of 40°C.

[0109] While the present disclosure has been described in terms of preferred embodiments, those skilled in the art will recognize that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the disclosure. In addition, many modifications may be made to the disclosed teachings to adapt to a particular situation or material without departing from the essential scope of the disclosure. Therefore, it is not intended that the disclosure be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this disclosure, but rather, the disclosure is intended to include all embodiments falling within the scope of the appended claims.

Claims

1. 1. A silicone pressure sensitive adhesive composition comprising: General formula (I) 【Chemistry 13】 In the formula R １ , R ２ and R ３ are each independently a hydrogen atom; hydroxyl; or a monovalent radical having up to 30 carbon atoms selected from the group consisting of alkyl, alkoxy, hydroxyalkyl, and alkoxyalkyl; or -R ８ -N(R ９ ) (R １０ ) wherein R ８ is a direct bond or a divalent linking group, and R ９ and R １０ are each independently a hydrogen atom, an alkyl, a hydroxyalkyl, or an alkoxyalkyl; and a boroxine compound represented by the general formula (II): 【Chemistry 16】 In the formula R ４ and R ５ are each independently a monovalent radical having up to 30 carbon atoms selected from the group consisting of alkyl, alkoxy, hydroxyalkyl, and alkoxyalkyl, or -R ８ -N(R ９ ) (R １０ ) wherein R ８ is a direct bond or a divalent linking group, and R ９ and R １０ are each independently a hydrogen atom, alkyl, hydroxyalkyl, or alkoxyalkyl; R ４ and R ５ together form a ring, the ring containing an alkylene group having up to about 10 carbon atoms bonded to the B atom of formula (II) through an oxygen atom; and R ６ and R ７ are each independently an alkyl, hydroxyalkyl, or alkoxyalkyl having up to 30 carbon atoms, or a hydrogen atom;

2. In the formula R １ , R ２ and R ３ are each independently a monovalent group having up to 20 carbon atoms selected from the group consisting of alkoxy and alkoxyalkyl, or -R ８ -N(R ９ ) (R １０ ) wherein R ８ is a direct bond, an alkylene group, or an oxyalkylene group, and R ９ and R １０ 10. The silicone pressure-sensitive adhesive composition of claim 1, wherein each independently represents a hydrogen atom, alkyl, or alkoxyalkyl.

3. The boroxine compound has the general formula (I-1) or the general formula (I-2): 【Chemistry 14】 In the formula R １１ , R １２ and R １３ are each independently a monovalent radical having up to 20 carbon atoms selected from the group consisting of alkyl, or -R １４ -N(R １５ ) (R １６ ) wherein R １４ is an alkylene group, and R １５ and R １６ are each independently a hydrogen atom, alkyl, or alkoxyalkyl; 【Chemistry 15】 In the formula R １７ 3. The silicone pressure-sensitive adhesive composition of claim 1, wherein each of is independently alkyl or alkoxyalkyl having up to 20 carbon atoms, or a hydrogen atom.

4. Borane-based compounds containing a boron-nitrogen covalent bond have the general formula (II-1): 【Chemistry 17】 In the formula R ２１ , R ２２ , R ２３ , R ２４ , R ２５ and R ２６ 10. The silicone pressure-sensitive adhesive composition of claim 1, wherein each independently is alkyl, hydroxyalkyl, or alkoxyalkyl, each independently having up to 20 carbon atoms, or is a hydrogen atom.

5. Borane-based compounds containing a boron-nitrogen covalent bond have the general formula (II-2): [Chemistry 18] In the formula R ２７ and R ２８ are each independently a monovalent group having up to 20 carbon atoms selected from alkyl, or -R ３１ -N(R ３２ ) (R ３３ ) wherein R ３１ is an alkylene group, and R ３２ and R ３３ are each independently a hydrogen atom, alkyl, or alkoxyalkyl; R ２７ and R ２８ may together form a ring, the ring containing an alkylene group of 1 to 6 carbon atoms bonded to the O atom of formula (II-2); and ２９ and R ３０ 10. The silicone pressure-sensitive adhesive composition of claim 1, wherein each independently is alkyl, hydroxyalkyl, or alkoxyalkyl, each independently having up to 20 carbon atoms, or is a hydrogen atom.

6. In the formula R ２７ and R ２８ form a ring together, and —CH ２ CH ２ -, -CH ２ CH ２ CH ２ -, -CH ２ CH (CH ３ ) -, -CH(CH ３ ) CH(CH ３ ) -, -CH ２ CH (CH ３ ) CH ２ - or -CH ２ C(CH ３ ) ２ CH ２ The silicone pressure sensitive adhesive composition of claim 5, comprising:

7. 7. The silicone pressure-sensitive adhesive composition of claim 1, wherein the at least one boron-containing additive further comprises a non-cyclic boron compound selected from the group consisting of boric acid, non-cyclic borate compounds, and combinations thereof.

8. 8. The silicone pressure sensitive adhesive composition of claim 7, wherein the acyclic borate compound is selected from the group consisting of trialkyl borates.

9. 9. The silicone pressure-sensitive adhesive composition of claim 7 or 8, wherein the weight ratio of said boron-containing compound to said non-cyclic boron compound is from about 1:100 to about 1:

1.

10. 10. The silicone pressure-sensitive adhesive composition of claim 7, wherein the boron-containing compound is selected from boroxine compounds, the acyclic boron compound is selected from acyclic borate compounds, and the weight ratio of the boroxine compounds to the acyclic borate compounds is from about 1:100 to about 1:

1.

11. 11. The silicone pressure-sensitive adhesive composition of claim 1, wherein the total amount of the at least one boron-containing additive is from about 1 to about 10 wt. %, based on the total weight of the silicone pressure-sensitive adhesive composition.

12. 1. A silicone pressure sensitive adhesive composition comprising: A boron-containing compound as defined in any one of claims 1 to 6, and i) boric acid; and ii) Acyclic borate compounds At least one boron-containing additive comprising at least one member selected from the group consisting of 1. A silicone pressure sensitive adhesive composition comprising:

13. 13. The silicone pressure sensitive adhesive composition of claim 12, wherein the at least one boron-containing additive comprises a non-cyclic borate compound ii) in combination with at least one of a cyclic borate compound or boric acid.

14. 14. The silicone pressure-sensitive adhesive composition of claim 13, wherein the non-cyclic borate compound is present in an amount of from about 50% to about 99% by weight, based on the total weight of the at least one boron-containing additive.

15. 15. The silicone pressure-sensitive adhesive composition of any one of claims 12 to 14, wherein the at least one boron-containing additive comprises an acyclic borate compound in combination with a boroxine-based compound having the general formula (I) defined in claim 1 or 2.

16. 16. The silicone pressure sensitive adhesive composition of claim 15, wherein the weight ratio of said boroxine compound to said non-cyclic borate compound is from about 1:100 to about 1:

1.

17. At least one boron-containing additive comprises a non-cyclic borate compound in combination with a cyclic boronate compound or a cyclic borate compound having the general formula (III): 【Chemistry 19】 In the formula R ３４ and R ３５ are each independently an alkyl having 1 to 6 carbon atoms or an aryl having 6 to 12 carbon atoms, and R ３４ and R ３５ may be joined together to form a ring, and the ring may be represented by the formula -OL ３ -CH ２ - divalent radical, where -L ３ - group is attached to the B atom of formula (III) via an oxygen atom; L １ , L ２ and L ３ each independently represents a group of the formula -[C(O)] ｍ C ｎ H ２ｎ -divalent group, where m is 0 or 1 and n is an integer from 0 to 4, provided that R ３４ and R ３５ When L １ , L ２ and L ３ 15. The silicone pressure sensitive adhesive composition of claim 13 or 14, wherein m defined for at least one of is 0.

18. polyorganosiloxane rubber; and Formula M=R ３ SiO １／２ at least one M unit of the formula T=RSiO ３／２ T units of formula Q = SiO ４／２ and optionally at least one unit selected from the group consisting of Q units of the formula D=R ２ SiO ２／２ wherein each R is independently a monovalent hydrocarbon group of 1 to 6 carbon atoms; and Optionally, a curing catalyst 18. The silicone pressure sensitive adhesive composition of claim 1, further comprising:

19. 19. The silicone pressure-sensitive adhesive composition of any one of claims 1 to 18, wherein the composition is cured by a radical reaction or a hydrosilylation reaction.

20. 20. An article comprising the silicone pressure sensitive adhesive composition of any one of claims 1 to 19.

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