Blue light-curable and UV-curable adhesive compositions including menthyl (METH)acrylate

Abstract

Adhesive compositions comprising 30 to 65 wt.% of an epoxy resin component, and 5 to 50 wt.% of (meth)acrylic polymer comprising polymerized units of monofunctional (meth)acrylate monomers comprising menthyl (meth)acrylate, wherein the amount of monomer is based on the total amount of monofunctional (meth)acrylate monomers. Also provided are articles including the disclosed adhesive compositions and methods of bonding articles using the disclosed adhesive compositions.

Description

[0001] BLUE LIGHT-CURABLE AND UV-CURABLE ADHESIVE COMPOSITIONS INCLUDING MENTHYL (METH)ACRYLATE

[0002] BACKGROUND

[0003] Adhesives are known to be useful for bonding one substrate to another, e.g., a metal to a metal, a metal to a plastic, a plastic to a plastic, a glass to a glass. In some applications, the adhesives are comprised of curable compositions. In some applications, curable compositions include a first curable composition and a second curable composition that can be sequentially cured. Cured compositions formed from these curable compositions are also known.

[0004] SUMMARY

[0005] In one aspect, provided herein are adhesive compositions comprising 30 to 65 wt.% of an epoxy resin component and 5 to 50 wt.% of a (meth)acrylic polymer comprising polymerized units of monofunctional (meth)acrylate monomers comprising menthyl (meth)acrylate, wherein the amount of monomer is based on the total amount of monofunctional (meth)acrylate monomers.

[0006] In another aspect, provided herein are articles including the disclosed adhesive compositions.

[0007] In another aspect, provided are methods of bonding articles using the disclosed adhesive compositions.

[0008] As used herein: the term “biobased” refers to compositions that mainly consist of a substance (or substances) derived from living matter (biomass) that either occur naturally or are synthesized; the term may also refer to products made by processes that use biomass. Many common materials, such as, for example, paper, wood, and leather, can be referred to as biobased, but typically, the term refers to modem materials that have undergone more extensive processing. Materials from biomass sources may include, for example, bulk chemicals, platform chemicals, solvents, polymers, and biocomposites, with the understanding that some materials may fall under more than one category; the term "(meth)acrylate" refers to "methacrylate" and / or "acrylate"; the term "free of isobomyl (meth)acrylate" refers to compositions that are less than 5 wt.%, less than 3 wt.%, or less than 1 wt.% isobomyl (meth)acrylate or are 0 wt.% isobomyl (meth)acrylate; the term “fully cured” refers to all monomers (acrylic and epoxy) being polymerized; the term “semi-structural bond” refers to compositions that when at least partially cured to at least one substrate can resist forces of approximately at least 400 psi as determined by the Overlap Shear Test or 150 psi as determined by the Die Shear Test; the term “structural bond” refers to compositions that when at least partially cured to at least one substrate can resist forces of approximately at least 1000 psi as determined by the Overlap Shear Test or 600 psi as determined by the Die Shear Test. Features and advantages of the present disclosure will be further understood upon consideration of the detailed description as well as the appended claims.

[0009] DETAILED DESCRIPTION

[0010] Adhesives are useful for bonding one or more substrates to one another. Many adhesives fall into one of two groups: (1) heat-curable adhesives and (2) light-curable adhesives. As suggested by the class name, heat-curable adhesives require heat for curing while light-curable adhesives begin to cure when exposed to light. Although heat usually is not required for curing light-curable adhesives, heat can be used to accelerate the rate of curing.

[0011] The curable adhesive can be in the form of a structural bonding tape. In many embodiments, the structural bonding tape has a layer of the curable structural adhesive composition adjacent to a release liner. A length of the structural bonding tape or a die cut piece of the structural bonding tape is removed from a roll and attached to a first substrate using finger pressure. After removal of the release liner, the curable structural adhesive is attached to a second substrate. In the case of light-curable structural adhesives, the curable structural adhesive is often exposed to radiation and then the second substrate is brought into contact with the irradiated curable adhesive. Pressure is applied to the assembly and, ultimately, a cured adhesive is formed between the two substrates. In the case of heat-curable structural adhesives (and optionally for light-curable structural adhesives), the curable structural adhesive is positioned between the first substrate and the second substrate. The entire assembly is then exposed to heat for curing and then allowed to cool. The result is an article having a first substrate bonded to the second substrate with a cured structural adhesive.

[0012] The curable adhesive can be in the form of a liquid adhesive.

[0013] In some embodiments, in the case of light-curable, liquid adhesives, the curable adhesive is often exposed to radiation and then the second substrate is brought into contact with the irradiated curable adhesive. Pressure is applied to the assembly and, ultimately, a cured adhesive is formed between the two substrates. In the case of heat-curable, liquid adhesives (and optionally for light-curable, liquid adhesives), the curable structural adhesive is positioned between the first substrate and the second substrate. The entire assembly is then exposed to heat for curing and then allowed to cool. The result is an article having a first substrate bonded to the second substrate with a cured structural adhesive.

[0014] In some embodiments, in the case of light-curable, liquid adhesives, the curable adhesive is dispensed into an optically clear construction through a channel onto at least one substrate such that the adhesive remains in the channel and is then exposed to radiation. In the case of heat-curable, liquid adhesives (and optionally for light-curable, liquid adhesives), the curable structural adhesive is dispensed into a construction through a channel onto at least one substrate such that the adhesive remains in the channel and is then exposed to heat for curing and then allowed to cool. The result, after removing the construction, is an article bonded to the at least one substrate with a cured adhesive. In some embodiments, the light-curable adhesive is a light-curable tape composition comprised of an acrylic network swollen with bisphenol-A diglycidyl ether reactants, a polyol, and a photoacid. The epoxy cure reaction may be activated with an e.g., 365nm LED, causing a photoacid to generate a superacid, leading to cationic epoxy polymerization and providing a non-tacky, tough bond with semi- structural to structural strength.

[0015] To obtain tape samples that are phase-separated, the acrylic copolymer monomers typically must be adjusted to be less miscible with the epoxy resins, an effect that may be achieved by altering the ratio of polar to non-polar acrylic monomers in the mixture. In addition, to achieve a final material that has an optimized glass transition temperature, one skilled in the art will combine (methjacrylate monomers based on their homopolymer glass transition temperature using the Flory -Fox equation to predict the polymerized, combined (methjacrylate monomers’ glass transition temperature.

[0016] In some embodiments, the light-curable adhesive is a curable liquid adhesive composition comprised of an acrylic polymer swollen with epoxy reactants, a polyol, and a photoacid. The epoxy cure reaction may be activated with an e.g., 365nm LED, causing the photoacid to generate a superacid, leading to cationic epoxy polymerization and providing a tough bond with semi-structural to structural strength.

[0017] To obtain samples that are phase-separated, the acrylic copolymer monomers typically must be adjusted to be less miscible with the epoxy resins, an effect that may be achieved by altering the ratio of polar to non-polar acrylic monomers in the mixture. In addition, to achieve a final material that has an optimized glass transition temperature, one skilled in the art will combine (methjacrylate monomers based on their homopolymer glass transition temperature using the Flory -Fox equation to predict the polymerized, combined (methjacrylate monomers’ glass transition temperature.

[0018] Isobomyl (methjacrylate ("IBO(M)A") is commonly used as an acrylate monomer in adhesives, because when cured it provides materials with a higher glass transition temperature than that which is observed when the IBO(M)A has been replaced with other commercially available, acrylate monomers. However, commercial sources of IBO(M)A are typically contaminated with camphene and residual starting isobomyl alcohol. Camphene produces a distinct, unpleasant odor and can act as a chain transfer agent, thus lowering a cured material's molecular weight and resulting in a lower degree of conversion, ultimately increasing the cured material’s volatile organic content. Additionally, IBO(M)A may be an allergen and unreacted residuals of IBO(M)A can be found in IBO(M)A-containing adhesives. As such, customers purchasing such acrylate adhesives are requesting IBO(M)A-free compositions.

[0019] Furthermore, polymers are traditionally predominantly sourced from crude-oil building blocks. As awareness of implications related to heavily relying on petroleum-based materials grows there is increasing interest in using non-petroleum sourced raw materials. Currently, there are few polymerizable, sustainably sourced raw materials that are commercially available, and these limited sustainably sourced raw materials often utilize fatty acids or the like as a starting material, resulting in a limited set of properties obtainable when using these monomers in polymerizable resins.

[0020] To address at least the deficiencies described above, the present disclosure provides light- activated adhesive formulations including menthyl acrylate ("MTA") instead of IBO(M)A. So that the performance of the fully cured adhesive formulated with MTA would be quite similar to the compositions including IBOA. In some examples, in view of the sensitive nature of the phase separation between the acrylic and epoxy phases in these compositions, the acrylic monomer ratios were adjusted to keep the Fox Tg of the acrylic copolymer as close to the same as possible.

[0021] The glass transition ("Tg") state of a mixture can be calculated using the Flory -Fox ("Fox") Equation:

[0022] 1 / Tg mix= a wi / Tgj

[0023] Additional information about the Fox equation and its uses can be found in various reference texts for polymeric materials such as, for example, Hiemenz and Lodge, Polymer Chemistry, Second Edition. 2007, pp. 492-495.

[0024] The Tg of the homopolymers of many monomers are known and reported in various handbooks. The following table sets forth the Tg of some illustrative monomers as reported (unless specified otherwise) in Polymer Handbook , 4thedition, edited by J. Brandrup, E.H. Immergut, and E. A. Grulke, associate editors A. Abe and D.R. Bloch, J. Wiley and Sons, New York, 1999.

[0025] Table 1. Glass Transition Temperatures of Homopolymers of Selected Monomers

[0026] So that the cured acrylate-epoxy morphology and thus rheological properties of the MTA formulations is similar to IBOA formulations, the glass transition temperature of the copolymer may be tuned by adjusting the ratio of the monomers. Calculated Flory-Fox Tg results are shown in Table2. Table 2. Calculated Flory-Fox Glass Transition Temperature for Selected Acrylic Monomer Compositions

[0027] Provided herein are adhesive compositions including 30 to 65 wt.% of an epoxy resin component and 5 to 50 wt.% of a (meth)acrylic polymer comprising polymerized units of monofunctional (meth)acrylate monomers comprising menthyl (meth)acrylate, wherein the amount of monomer is based on the total amount of monofunctional (meth)acrylate monomers.

[0028] In some embodiments, the adhesive compositions comprise 1 to 30 wt.% menthyl (meth)acrylate.

[0029] In some embodiments, the adhesive compositions further comprise 5 to 20 wt.% of a low Tg (meth)acrylate monomer, wherein a homopolymer thereof has a glass transition temperature (Tg) of less than 0°C, and 5 to 20 wt.% of a non-acidic polar (meth)acrylate monomer, wherein the amount of monomer is based on the total amount of monofunctional (meth)acrylate monomers. In some embodiments, the adhesive compositions further comprise a polyol. In some embodiments, the adhesive compositions further comprise a photoacid generator.

[0030] In some embodiments, the adhesive compositions comprise the (meth)acrylic polymer comprising polymerized units of monofunctional (meth)acrylate monomers that is free of isobomyl (meth)acrylate.

[0031] In some embodiments, the adhesive composition has two Tgs after curing of the monofunctional (meth)acrylate monomers and epoxy resin component.

[0032] In some embodiments, a homopolymer of one or more of the low Tg (meth)acrylate monomer(s) has a Tg less than -10, -20, -30, -40, -50, or -60°C. In some embodiments, the low Tg (meth)acrylate monomer(s) are present in an amount of at least 30, 40, 50, or 60 wt.%. In some embodiments, the low Tg monomer(s) (meth)acrylate monomer(s) comprise an alkyl group with 4 to 12 carbon atoms.

[0033] In some embodiments, the non-acidic polar (meth)acrylate monomer(s) comprises an ether group or a hydroxyl group. In some embodiments, a homopolymer of one or more of the non-acidic polar (meth)acrylate monomer(s) has a Tg less than -10, -20, -30, -40, or -50°C.

[0034] In some embodiments, one or more of the non-acidic polar (meth)acrylate monomer(s) has a Tg of at least 40, 50, 60, 70, 80, or 90°C. In some embodiments, one or more of the non-acidic polar (meth)acrylate monomer(s) comprises a cycloaliphatic moiety. In some embodiments, one or more of the non-acidic polar (meth)acrylate monomer(s) comprising an epoxy moiety. In some embodiments, the epoxy resin(s) comprises an aromatic group inclusive of a bisphenol moiety.

[0035] In some embodiments, the adhesive composition further comprises a hydroxy -functional component inclusive of polyether polyols. In some embodiments, the adhesive composition further comprises up to 2 wt.% of a multifunctional (meth)acrylate crosslinker.

[0036] In some preferred embodiments, the menthyl (meth)acrylate is L-menthyl (meth)acrylate.

[0037] In some embodiments, the menthyl (meth)acrylate is derived from L-menthol. In some embodiments the menthyl (meth)acrylate is derived from biobased L-menthol.

[0038] In some embodiments, the adhesive composition is partially or fully cured. In some embodiments, the adhesive composition is a liquid adhesive that can undergo curing via actinic radiation to form a semi- structural bond or a structural bond.

[0039] Also provided herein are articles comprising at least one layer of the disclosed adhesive compositions, disposed on a major surface of a substrate. In some embodiments, the substrate is selected from the group consisting of a metal, a glass, a coated glass, a plastic, a polymeric film, a release liner, and combinations thereof. In some embodiments, the article is a tape comprising a layer of the adhesive composition disposed on one major surface or both major surfaces of the substrate. In some embodiments, the epoxy resin component of the article is uncured.

[0040] Also provided herein are methods of bonding, the method comprising providing an article as described above, contacting a layer of the adhesive composition with a surface of the article, and curing the epoxy resin component. In some embodiments, the surface of the article comprises metal, plastic, or glass.

[0041] Also provided are methods of preparing the adhesive compositions disclosed herein, the method comprising polymerizing a monomer mixture of (methjacrylate monomers to produce a (methjacrylate copolymer; combining the (methjacrylate copolymer with an epoxy resin to provide a mixture; and combining the mixture with a photoacid generator to provide the adhesive composition. In some embodiments, the step of combining the (methjacrylate copolymer with an epoxy resin to provide a mixture further comprises adding a polyol. In some embodiments, the monomer mixture comprises unreacted monomers.

[0042] Epoxy Resins

[0043] Epoxy resins or epoxides useful in embodiments of the present disclosure typically comprise at least one oxirane ring that is polymerizable by ring opening, i.e., an average epoxy functionality greater than one, and preferably at least two. The epoxides can be monomeric or polymeric, and aliphatic, cycloaliphatic, heterocyclic, aromatic, hydrogenated, or combinations thereof. Preferred epoxides contain more than 1.5 epoxy group per molecule and preferably at least 2 epoxy groups per molecule. The useful materials typically have a weight average molecular weight of about 150 to about 10,000, and more typically of about 180 to about 1,000. The molecular weight of the epoxy resin is usually selected to provide the desired properties of the cured composition. Suitable epoxy resins include linear polymeric epoxides having terminal epoxy groups (e.g., a diglycidyl ether of a polyoxyalkylene glycol), polymeric epoxides having skeletal epoxy groups (e.g., polybutadiene poly epoxy), and polymeric epoxides having pendent epoxy groups (e.g., a glycidyl methacrylate polymer or copolymer), and mixtures thereof.

[0044] These epoxy resins include aromatic glycidyl ethers, e.g., such as those prepared by reacting a polyhydric phenol with an excess of epichlorohydrin, cycloaliphatic glycidyl ethers, hydrogenated glycidyl ethers, and mixtures thereof. Such polyhydric phenols may include resorcinol, catechol, hydroquinone, and the polynuclear phenols such as p,p'-dihydroxydibenzyl, p,p'-dihydroxydiphenyl, p,p'- dihydroxyphenyl sulfone, p,p'-dihydroxybenzophenone, 2,2'-dihydroxy- 1, 1 -dinaphthylmethane, and the 2,2', 2,3', 2,4', 3,3', 3,4', and 4,4' isomers of dihydroxydiphenylmethane, dihydroxydiphenyldimethylmethane, dihydroxydiphenylethylmethylmethane, dihydroxydiphenylmethylpropylmethane, dihydroxydiphenylethylphenylmethane, dihydroxydiphenylpropylphenylmethane, dihydroxydiphenylbutylphenylmethane, dihydroxydiphenyltolylethane, dihydroxydiphenyltolylmethylmethane, dihydroxy diphenyldicyclohexylmethane, and dihydroxy diphenylcyclohexane .

[0045] Also useful are polyhydric phenolic formaldehyde condensation products as well as poly glycidyl ethers that contain as reactive groups only epoxy groups or hydroxy groups. Useful curable epoxy resins are also described in various publications including, for example, "Handbook of Epoxy Resins" by Lee and Nevill, McGraw-Hill Book Co., New York (1967), and Encyclopedia of Polymer Science and Technology, 6, p.322 (1986).

[0046] The choice of the epoxy resin used depends upon the end use for which it is intended. Epoxides with flexibilized backbones may be desired where a greater amount of ductility is needed in the bond line. In some embodiments, the composition is suitable for use as a structural adhesive. Materials such as diglycidyl ethers of bisphenol A and diglycidyl ethers of bisphenol F can provide desirable structural adhesive properties that these materials attain upon curing, while hydrogenated versions of these epoxies may be useful for compatibility with substrates having oily surfaces.

[0047] Examples of commercially available epoxides useful in embodiments of the present disclosure include diglycidyl ethers of bisphenol A (e.g, those available under the trade designations EPON 828, EPON 1001, EPON 1004, EPON 2004, EPON 1510, and EPON 1310 from Momentive Specialty Chemicals, Inc., and those under the trade designations D.E.R. 331, D.E.R. 332, D.E.R. 334, and D.E.N. 439 available from Dow Chemical Co.); diglycidyl ethers of bisphenol F (e.g., that are available under the trade designation ARALDITE GY 281 available from Huntsman Corporation); silicone resins containing diglycidyl epoxy functionality; flame retardant epoxy resins (e.g., that are available under the trade designation DER 560, a brominated bisphenol type epoxy resin available from Dow Chemical Co.); aliphatic epoxides (e.g., that are available under the trade designation CELLOXIDE 202 IP available from Daicel Corporation); and 1,4-butanediol diglycidyl ethers. The (e.g. adhesive) composition desirably contains one or more epoxy resins having an epoxy equivalent weight of at least 100, 200 or 300 and typically no greater than 1500, 1200, or 1000. In some embodiments, the adhesive contains two or more epoxy resins, wherein at least one epoxy resin has an epoxy equivalent weight of from about 300 to about 500, and at least one epoxy resin has an epoxy equivalent weight of from about 1000 to about 1200.

[0048] Polyols

[0049] In some embodiments, the adhesive composition further comprises a polyol. Polyol compounds in some cases comprise at least two, three, or four hydroxy moieties capable of reacting with an epoxy resin. Examples include polyalkylene oxide polyols such as polyoxyethylene and polyoxypropylene glycols; polyoxyethylene and polyoxypropylene triols and polytetramethylene oxide glycols. Such polyols can be suitable for retarding the adhesive curing reaction such that the "open time" of the adhesive composition can be increased.

[0050] Commercially available poly(alkylenoxy) compounds suitable for use in embodiments of the present disclosure include, but are not limited to, the POLYMEGTM series of polytetramethylene oxide glycols (available from Lyondellbasell, Inc., Jackson, Tenn.), the TERATHANETM series of polytetramethylene oxide glycols (from Invista, Newark, Del.); the POLYTHFTM series of polytetramethylene oxide glycol from BASF Corp. (Charlotte, N.C.); the ARCOLTM series of polyoxypropylene polyols (from Bayer MaterialScience., Los Angeles, Calif.) and the VORANOLTM series of polyether polyols from Dow Automotive Systems, Auburn Hills, MI.

[0051] (Meth) acrylate Monomers

[0052] Exemplary low Tg monomers include for example ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2- methylbutyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2-pentyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, octadecyl acrylate, and dodecyl acrylate.

[0053] In some embodiments, the composition comprises at least one low Tg monomer having a non- cyclic alkyl (meth)acrylate monomer(s) having 4 to 20 carbon atoms. In some embodiments, the (meth)acrylic polymer and / or PSA comprises at least one low Tg monomer having a (e.g. branched) alkyl group with 6 to 20 carbon atoms. In some embodiments, the low Tg monomer has a (e.g. branched) alkyl group with 7 or 8 carbon atoms. Exemplary monomers include, but are not limited to, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, 2-octyl (meth)acrylate, isodecyl (meth)acrylate, and lauryl (meth)acrylate.

[0054] In some embodiments, the composition may comprise a high Tg monomer, having a Tg greater than 10°C and typically of at least 15°C, 20 °C or 25°C, and preferably at least 50°C. Suitable high Tg alkyl (meth)acrylate monomers include, for example, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, stearyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, norbomyl (meth)acrylate, benzyl methacrylate, 3,3,5 trimethylcyclohexyl acrylate, cyclohexyl acrylate, and combinations thereof.

[0055] Polar (Meth) acrylates

[0056] Useful non-acidic polar monomers may include 2-hydroxyethyl (meth)acrylate, THF(M)A, poly(alkoxyalkyl) (meth)acrylates including 2-(2-ethoxyethoxy)ethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 2-methoxyethoxyethyl (meth)acrylate, 2-methoxyethyl methacrylate, polyethylene glycol mono(meth)acrylates, and combinations thereof.

[0057] (Meth)acrylates Having More Than One Polymerizable Unit

[0058] (Meth)acrylates having more than one polymerizable unit useful in embodiments of the present disclosure include, for example, hexanediol diacrylate, hexanediol dimethacrylate, dicyclopentyldimethylene diacrylate, polyethylene glycol 200 diacrylate, propoxylated neopentyl glycol diacrylate, ethoxylated bisphenol A diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and combinations thereof.

[0059] Radical Photoinitiators for (Meth) acrylate Polymerizations

[0060] Compositions according to the present disclosure further comprise at least one photoinitiator (i.e., a free-radically polymerization photoinitiator). Useful photoinitiators include Type I and / or Type II photoinitiators, optionally in combination with one or more sensitizing dye, and / or amine synergist, for example.

[0061] Suitable Type I (i.e., Norrish Type I) photoinitiators, which photolyze to form free radicals on absorption of actinic electromagnetic radiation, include benzoin ethers, benzyl ketals, a.cx- dialkoxy-acetophenones, a-hydroxyalkylphenones, a-dialkylaminoalkylphenones, acylphosphine oxides, acylphosphines, substituted derivatives thereof, and combinations thereof.

[0062] Examples of suitable Type I photoinitiators include 2-benzyl-2-(dimethylamino)-4'- morpholinobutyrophenone; 1 -hydroxy cyclohexyl phenyl ketone; 2-methyl-l-[4-(methylthio)phenyl]-2- morpholinopropan- 1 -one; 2 -hydroxy -2 -methyl- 1 -phenylpropanone; 1 -[4-(2-hydroxy ethoxy l)phenyl] -2- hydroxy-2 -methylpropanone; 2, 2-dimethoxy -2 -phenylacetophenone; phenylbis(2,4,6- trimethylbenzoyl)phosphine oxide; phenylbis(2,4,6-trimethylbenzoyl)phosphine; bis(2,4,6- trimethylbenzoyl)phenylphosphine oxide; 2,4,6-trimethylbenzoyldiphenylphosphine oxide; isopropoxyphenyl-2,4,6-trimethylbenzoylphosphine oxide; dimethyl pivaloylphosphonate; ethyl (2,4,6- trimethylbenzoyl) phenyl phosphinate; and bis(cyclopentadienyl) bis[2,6-difluoro-3-(l-pyrryl)phenyl] titanium. These and many others are widely available from commercial sources. The term "Type II photoinitiator" refers to a compound wherein absorption of electromagnetic radiation (e.g., ultraviolet and / or visible light) causes an excited electron state in the Type II photoinitiator that will abstract a hydrogen from the co-initiator, and in the process, generate free radicals. Exemplary Type II photoinitiators include diaryl ketones (e.g., benzophenone, 4-methylbenzophenone, or 4 chlorobenzophenone), 1 -phenylpropane- 1,2-dione, thioxanthones (2 -isopropylthio xanthone, 2- mercaptothioxanthone, 2, 4-diethylthio xanthone, l-chloro-4-propoxythioxanthone, and 2- chloro“thioxanthone, or 4-isopropylthioxanthone), camphorquinone, benzil, naphthoquinones (e.g., 2,2'- bis(3-hydroxy-l,4-naphthoquinone)), anthraquinones (e.g., anthraquinone, 1,4- dihydroxyanthraquinone, 2 methylanthraquinone, or 2,6-dihydroxyanthraquinone), 3 -ketocoumarins, and combinations thereof.

[0063] Typically, the photoinitiator(s) is / are present in the free -radically polymerizable composition in an amount of 0.01 to 10 weight percent, preferably 0.05 to 5 weight percent, and more preferably 0.1 to 3 weight percent, based on the total weight of the free-radically polymerizable composition, although other amounts may also be used.

[0064] Epoxy Polymerization Initiators

[0065] Photoacid generators are generally known to those skilled in the art. Photoacid generators (PAGs) undergo photolysis to generate acids. Such photoacid generators are useful for various applications, because acids generated by photo-irradiation can be reactive species to promote cationic polymerizations and cross-linking reactions. Photoacid generators commonly comprise iodonium salts or sulfonium salts. These salts have been used as photoacid generators to effect UV curing. In some embodiments, to effect e.g., blue light curing, a photoacid generator may be combined with a sensitizer (e.g., camphorquinone) and an amine synergist (e.g., ethyl-4-(dimethylamino)benzoate.

[0066] Useful sulfonium salt photoacid generators include, but are not limited to: diphenyl(4- phenylthio)phenyl sulfonium hexafluorophosphate, bis(4-diphenylsulfonium phenyl)sulfide bis- (hexafluorophosphate), diphenyl(4-phenylthio)phenyl sulfonium hexafluoroantimonate, bis(4- diphenylsulfonium phenyl)sulfide bis-(hexafluoroantimonate), and blends of these triarylsulfonium salts available from Synasia, Metuchen, N.J. under the trade designations of UVI-6992™ and UVI-6976™ for the PF6 and SbF6 salts, respectively. Other useful sulfonium salt include, but are not limited to: triphenyl sulfonium hexafluoroantimonate (e.g., CT-548™ from Chitec Technology Corp. Taipei, Taiwan), diphenyl(4-phenylthio)phenyl sulfonium hexafluorophosphate (e.g., CPI-100 from San-Apro Limited, Tokyo Japan), and diphenyl(4-phenylthio)phenyl sulfonium [(Rf)nPF6-n], where Rf is a perfluorinated alkyl group (e.g., CPI-200 from San-Apro Limited, Tokyo Japan).

[0067] Light

[0068] Compositions according to the present disclosure can be polymerized / cured by exposure to actinic radiation (i.e., electromagnetic actinic radiation). By definition, actinic radiation is electromagnetic radiation that is absorbed by one or more components of the photopolymerizable composition that ultimately leads to at least partial free-radical polymerization of the composition. Exemplary actinic radiation has a wavelength of from 250 nanometers to 700 nanometers. The actinic radiation is absorbed by both the photoinitiator and the organic photoactivatable reducing agent precursor, either simultaneously or sequentially. For example, the same or different wavelengths of actinic radiation may be used for the photoinitiator and the organic photoactivatable reducing agent precursor.

[0069] The source(s) of actinic radiation is / are selected such that the actinic radiation is of an appropriate wavelength to be absorbed by the photoinitiator and organic photoactivatable reducing agent precursor, Exemplary sources of actinic radiation may include lasers (ultraviolet or visible), broad spectrum flashlamps (e.g., xenon flashlamps), and low-, medium-, and high-pressure mercury arc lamp mercury arc lamps, microwave-driven mercury lamps (e.g., using H-type, V-type, or D-type bulbs), and light emitting diode (LEDs). Further details associated with radiation curing are with the capabilities of those skilled in the art.

[0070] Additives

[0071] The compositions may contain optional components to enhance their performance. Exemplary such optional components include thixotropes, wetting agents, tackifiers, levelling agents, fillers, thermoplastic polymers, tougheners (e.g., core-shell rubber particles), colorants, light stabilizers, antioxidants, surfactants, plasticizers / flexibilizers, and antimicrobial agents.

[0072] Substrates

[0073] Exemplary substrates include metals (e.g., aluminum or stainless steel), plastics (e.g., a polyamide, a polycarbonate), and glasses. In particularly embodiments, the substrate is a glass, whether fritted or non-fritted, and the glass is bonded to another glass, or the glass is bonded to a metal. In some embodiments, the substrate(s) can be transparent (e.g., glass and / or plastic).

[0074] In use, compositions according to the present disclosure are disposed on a substrate (when used as a sealant) or between two substrates (when used as an adhesive) and then exposed to the actinic radiation for sufficient time (e.g., from less than a second to several minutes) to cause a desired level of polymerization to occur. In some embodiments, the composition may be sandwiched between two releasable liners to make an adhesive transfer tape.

[0075] Objects and advantages of this disclosure are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and details, should not be construed to unduly limit this disclosure.

[0076] EXAMPLES

[0077] Unless otherwise noted or readily apparent from the context, all parts, percentages, ratios, etc. in the Examples and the rest of the specification are by weight.

[0078] Test Methods

[0079] Shear Dynamic Mechanical Analysis ("DMA") Test: Samples were prepared for rheology by laminating several adhesive layers together until a minimum of 0.5mm was achieved. The stack of adhesive was irradiated using an array of LEDs having a peak emission wavelength of 365 nm (CLEARSTONE TECHNOLOGIES, Hopkins, MN). The total UV-A energy was determined using a POWER PUCK II radiometer (EIT, Inc., Sterling, VA) achieving 7.5 J / cm2and allowed to fully cure over 24 hours to provide the fully cured tape. Dynamic Mechanical Analysis using a DHR-3 parallel plate rheometer (TA Instruments, New Castle, DE, USA) was performed by punching an 8mm circle. A temperature sweep was performed at 1 Hz from -30 °C to 150 °C and the tan(5) peak(s) were recorded.

[0080] Dynamic Mechanical Analysis (“DMA”) Test Method Temperature Ramp: After 5 days, the thickness of each film was measured. The films were mounted in the tensile grips of an DMA850 (TA Instruments, New Castle, DE, USA) with an initial grip separation of 12-16 mm. The measurement procedure was done to determine the precise grip separation with an initial / preload force of 0.1 N with a “Use Force Track” set to 150%. The samples were then tested at an oscillation of 0.2% strain and 1 Hz throughout a temperature ramp from at least -10 °C to 100 °C at a rate of 3 °C per minute. The temperatures at which the tan delta signal reached a maximum were recorded as the glass transition temperature (Tg). The storage (E’) and loss modulus (E’ ’) at 25 °C were recorded for each sample in MPa. The Tan(delta) was integrated 30.9 °C to 97.9 °C to record the area under the curve, the tan(delta) height, and Tan(delta) peak width at half height recorded in °C.

[0081] Overlap Shear ("OLS") Test - Aluminum substrates measuring 1” x 4” x 0.064” (2.5 cm x 10.2 cm x 0.16 cm) were prepared by scrubbing the terminal 1” (2.54 cm) with SCOTCH-BRITE GENERAL PURPOSE HAND PAD #7447 (3M) attached to a handheld power sander (RYOBI 2 Amp Corded 1 / 4 Sheet Sander, Hiroshima, Japan) followed by washing with isopropanol and air-drying. A ‘A” x 1” (1.3 cm x 2.5 cm) portion of the uncured tape was applied to the sanded end of one substrate. The release liner was removed from one side of the uncured tape and the tape was applied to one aluminum substrate. The second release liner was removed and the composition was exposed to UV-A radiation using an array of LEDs having a peak emission wavelength of 365 nm (CLEARSTONE TECHNOLOGIES, Hopkins, MN). The total UV-A energy was determined using a POWER PUCK II radiometer (EIT, Inc., Sterling, VA) achieving 7.5 J / cm2. A second coupon was applied to the irradiated sample, thus closing the bond. The assembly was wet out by means of applying a static load to the specimen for six seconds. Specimens were allowed to cure at ambient temperature and humidity for 24 hours prior to testing. Dynamic overlap shear tests were performed at ambient temperature and 60 °C using an INSTRON TENSILE TESTER MODEL 5581 (Instron Corp., Canton, MA) equipped with a 30 kN load cell. Test specimens were loaded into the grips and the crosshead was operated at 0.1” (0.25 cm) per minute, loading the specimen to failure. Stress at break was recorded in units of megapascals. Three specimens of each sample were tested, and the average result was calculated.

[0082] Die Shear Test: Copper overlap shear panels were cleaned with MEK, and IPA, wiped with a paper towel, and allowed to dry for at least three minutes. A 1 mm thick rubber mold with three 6.5 x 6.5 mm square cut outs was placed on the copper substrate. The adhesive was dripped into the squares. The adhesive was allowed to dwell for one min at room temperature (approximately 25 C). A release liner, release side down, was placed over the adhesives then a 5 mm glass plate was placed over the release liner. The sample was irradiated with a Clearstone CT2000 at 31% power 3 min 75 mm height (500 mW / cm2) the sample was allowed to rest for 30 seconds before removing the glass, release liner, and rubber mold. The samples were allowed to dwell at ambient temperature and pressure for 24 hours before evaluating using an MTS Sintech Tensile Tester pushing the squares at 10 mm per minute and recording peak load in newtons which was converted to newtons per mm2recorded as an average and standard deviation of three samples.

[0083] Cure Monitoring by FTIR (Individual Spectrum): The components of a given compositions was sandwiched between two glass microscope slides: setup consists of a top slide (1" x 3", pre-cleaned, VWR 48300-025) + silicone rubber gasket (15 mil thick, 1" x 3") + bottom slide (2" x 3", pre-cleaned, VWR 48382-179), attached with small binder clips at top and bottom. The rubber gasket has a circle in the middle cut out to allow room for the formulation. The set up was placed in line of the sensor of a Nicolet IR iS50 spectrometer (Nicolet Thermo Fisher Scientific Inc., Waltham, MA). Spectra were taken in a range of 4000-7000 cm-1. The sample before and after irradiation were analyzed. The spectra were analyzed for disappearance of the acrylate / methacrylate overtone peak centered between 6165 cm-1. This disappearance was translated into a % cure value by 100 x (time initial peak integration - time final peak integration) / time initial peak integration.

[0084] Tensile and Elongation: Tensile elongation Analysis: tensile elongation testing was performed at ambient temperature using a Tensile Tester (tensile tester from MTS Sintech, Eden Prairie Minnesota), with a 30 kN loadcell. Films were cut using a type V dogbone and were loaded into the grips at a distance of 2.5 inches (6.35 cm) and the crosshead was operated at 3.94 inch per minute (100 mm per minute), loading the specimen to failure. Peak stress was recorded in units of megapascals (MPa), Young’s Modulus was recorded in MPa, Strain at Break was recorded in %.

[0085] Synthesis of L-menthyl acrylate ("L-MTA"):

[0086] All quantities were calculated relative to the amount of L-menthol. To a 1 L round bottom flask was added L-menthol (500 g, 3.20 mol, 1.00 eq.), acrylic acid (277 g, 3.84 mol, 1.20 eq.), phenothiazine (1.00 g, 2000 ppm), furfural (1.00 g, 2000 ppm), p-toluenesulfonic acid (pTSA, 5.75 g, 1.15 wt%), and cyclohexane (75.0 g, 15.0 wt%). The flask was equipped with a 30 cm Vigreux column and a Dean-Stark head that was filled with cyclohexane containing 50 ppm of furfural. The separated water was collected every 30 min to Ih throughout the complete reaction. First, the mixture was heated to 120 °C and reacted for Ih, where tO is marked by the start of reflux from the Dean-Stark head. Next, the setpoint was increased to 140 °C, and the mixture was allowed to react for 5.5 h. Finally, the temperature was increased to 150 °C for another 2.5 h, after which the mixture was cooled to room temperature. The conversion was determined via 1H-NMR and was found to be typically >98%.

[0087] The Dean-Stark head was replaced with a Claisen head and a distilling condenser. Vacuum was applied and the crude was heated to 80 °C for Ih. An ultimate vacuum of 5 mmHg was obtained. Next, the batch was heated from 115 °C to 135 °C to collect 545 g of the desired product (95-97°C at 5 mmHg), to which 10 mg of MEHQ (18 ppm) was added. A clear change in refractive index compared to lower boiling compounds can be observed when L-MTA is being distilled. The purity was determined to be >98 wt% via 1H-NMR.

[0088] Two batches of distilled L-MTA (545 g and 550 g) were combined and washed with 220 g of a 2% aqueous sodium hydroxide solution. The organic phase was then washed with 220 g of deionized water until the aqueous phase was neutral (three times). The obtained slightly turbid organic phase was finally filtered over a filter paper to obtain clear L-MTA (1083 g, 80.1% yield). The purity was determined to be >98 wt% via 1H-NMR and GC. 19 mg of MEHQ was added (18 ppm expected). Via standard QC tests, the presence of 19 ppm MEHQ, 0.3 ppm phenothiazine, and 0.173% water was determined. No residual furfural was detected in the sample.

[0089] Synthesis of DL-menthyl acrylate ("DL-MTA")

[0090] All quantities were calculated relative to the amount of DL-menthol. To a 1 L round bottom flask was added DL-menthol (500 g, 3.20 mol, 1.00 eq.), acrylic acid (277 g, 3.84 mol, 1.20 eq.), phenothiazine (1.00 g, 2000 ppm), furfural (1.00 g, 2000 ppm), p-toluenesulfonic acid (pTSA, 5.75 g, 1.15 wt%), and cyclohexane (75.0 g, 15.0 wt%). The flask was equipped with a 30 cm Vigreux column and a Dean-Stark head that was filled with cyclohexane containing 50 ppm of furfural. The separated water was collected every 30min to Ih throughout the complete reaction. First, the mixture was heated to 120 °C and reacted for Ih, where tO is marked by the start of reflux from the Dean- Stark head. Next, the setpoint was increased to 140 °C, and the mixture was allowed to react for 5.5 h. Finally, the temperature was increased to 150 °C for another 2.5 h, after which the mixture was cooled to room temperature. The conversion was determined via 1H-NMR and was found to be >98%.

[0091] The Dean-Stark head was replaced with a Claisen head and a distilling condenser. Vacuum was applied and the crude was heated to 80 °C for Ih. An ultimate vacuum of 5 mmHg was obtained. Next, the batch was heated from 115 °C to 135 °C to collect 542 g of the desired product (95-97°C at 5 mmHg), to which 10 mg of MEHQ (18 ppm) was added. A clear change in refractive index compared to lower boiling compounds can be observed when DL-MTA is being distilled. The purity was determined to be >98 wt% via 1H-NMR.

[0092] Two batches of distilled DL-MTA (both 542 g) were combined and washed with 220 g of a 2% aqueous sodium hydroxide solution. The organic phase was then washed with 220 g of deionized water until the aqueous phase was neutral (three times). The obtained slightly turbid organic phase was finally filtered over a filter paper to obtain clear DL-MTA (1076 g, 80.0% yield). The purity was determined to be 98.7 wt% via 1H-NMR. 20 mg of MEHQ was added (19 ppm expected). Via standard QC tests, the presence of 21 ppm MEHQ, 0.2 ppm phenothiazine, and 0.160% water was determined. No residual furfural was detected in the sample.

[0093] Example 1: Preparation of Acrylic -Epoxy Formulations (Comparative Examples CE-1A and CE-1B and Examples EX-1A, EX-1B, and EX-1C)

[0094] An epoxy -polyol blend ("epoxy resin component") was prepared by charging a glass jar with epoxy resins (EPON828 and EPON1001) in the amounts shown in Table 1 and heating the slurry in a 135 °C oven until a homogenous mixture was obtained. ACCLAIM 2200 was added with stirring and the mixture was allowed to cool to ambient temperature. Immediately prior to use, the mixture was re-heated to ca. 200 °F (93 °C) to decrease viscosity for ease of pouring. In a glass jar, acrylic monomers, GPTMS, HDD A, UVI6976, epoxy -polyol blend, TS-720, and OMNIRAD 819 were combined in amounts shown in Table 3. The jar was closed tightly with a foil-lined cap and placed on a jar-roller overnight, protected from light to provide the acrylate-epoxy blended solutions.

[0095] Table 3. Acrylic-Epoxy Formulations

[0096] Example 2: Preparation and Testing of Adhesive Tapes (Comparative Examples CE-2A and CE-2B and Examples EX-2A, EX-2B, and EX-2C)

[0097] The uncured tapes were prepared by coating a layer of acrylic-epoxy formulations from Example 1 between two silicone release-coated PET liners using a two-roll coater having a gap setting of 0.010 inches (254 micrometers) greater than the combined thickness of the two liners.

[0098] The coated layer was exposed to a total UV-A energy of approximately 3400 mJ / cm2(from two sides with approximately 1700 mJ / cm2per side) using a plurality of LED lamps with a peak emission wavelength of 405 nm to provide the partially cured tape. The total UV exposure was determined using a POWER PUCK II radiometer equipped with low power sensing head (EIT, Inc., Sterling, VA).

[0099] Shear dynamic mechanical analysis ("DMA") was performed on fully cured tapes (after 365nm LED activation), prepared as described above, to determine the glass transition temperature(s) and analyze the phase separation / morphology of the compositions. Samples that were visibly opaque were found to have two glass transition temperatures, indicating phase separation between the acrylic and the epoxy phases, while translucent samples were found to have one Tg (less phase separated). Overlap shear ("OLS") tests were performed at room temperature and at 60 °C on the cured tapes (after 365nm LED activation) as described above. The visual appearance of the tapes and testing results are shown in Table 4. Table 4. Summary of Results

[0100] As the data in Table 4 show, menthyl acrylate is an excellent replacement for isobomyl acrylate when the ratios of acrylic monomers are adjusted to keep the Fox Tg’s of the acrylic copolymer nearly the same.

[0101] Example 3: Preparation and Testing of EX-3A, EX-3B, and CE-3):

[0102] Formulations were prepared by combining epoxy, polyol, acrylic monomers, and acrylate initiators into a polypropylene mixing cup (from FlackTek, Inc., Landrum, SC). The cup was closed with a polypropylene lid and the mixture was high shear mixed at ambient temperature using a SPEEDMIXER (Hauschild SpeedMixer Inc., Dallas Texas) for at least 120 seconds at 2000 revolutions per minute (rpm) under reduced pressure (40 mmHg). A stir bar was added to each mixing cup. The mixing cup was then placed on a stir plate and irradiated with a Clearstone 2000, 450 nm, with 2.66 J / cm2(from Clearstone Technologies Inc) while stirring until the acrylic monomers had reached at least 90% bond conversion as measured by FTIR according to the Cure Monitoring by FTIR (Individual Spectrum) procedure above. Subsequently, PI 2074, CPQ, and EDMAB were added to the mixing cup. The cup was closed with a polypropylene lid and the mixture was high shear mixed at ambient temperature using a SPEEDMIXER (Hauschild SpeedMixer inc., Dallas Texas) for at least 300 s at 2000 revolutions per minute (rpm) under reduced pressure (40 mmHg). Table 5. Formulation Details of EX-3A, EX-3B, and CE-3

[0103] Values Recorded in Weight Percent

[0104] Each formulation (20 g) was separately coated between release liners at 0.5 mm thickness, and the liner-formulation-liner sample was placed on a 5 mm thick aluminum panel and covered with 5 mm thick glass top, which was placed in a Clearstone CT2000 and irradiated 500 mW / cm2for three minutes. The samples were allowed to dwell at ambient temperature and pressure for 24 hours before evaluating them with the Dynamic Mechanical Analysis (“DMA”) Test Method Temperature Ramp as described above. Results are shown in Tables 6 and 7.

[0105] Table 6. Mechanical Properties from DMA of EX-3A, EX-3B, CE-3

[0106] Table 7. Tensile and Elongation Data for EX-3A, EX-3B, and CE-3

[0107] The formulations were further analyzed using copper overlap shear panels according to the Die Shear Test. Results are shown in Table 8. Table 8. Adhesion on Copper

[0108] All cited references, patents, and patent applications in the above application for letters patent are herein incorporated by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control. The preceding description, given in order to enable one of ordinary skill in the art to practice the claimed disclosure, is not to be construed as limiting the scope of

Claims

What is claimed is:

1. An adhesive composition comprising:30 to 65 wt.% of an epoxy resin component; and5 to 50 wt.% of a (meth)acrylic polymer comprising polymerized units of monofunctional (meth)acrylate monomers comprising menthyl (meth)acrylate, wherein the amount of monomer is based on the total amount of monofunctional (meth)acrylate monomers.

2. The adhesive composition of claim 1, comprising 1 to 30 wt.% menthyl (meth)acrylate.

3. The adhesive composition of claim 1 or claim 2, further comprising 5 to 20 wt.% of a low Tg (meth)acrylate monomer, wherein a homopolymer thereof has a glass transition temperature (Tg) of less than 0°C, and 5 to 20 wt.% of a non-acidic polar (meth)acrylate monomer, wherein the amount of monomer is based on the total amount of monofunctional (meth)acrylate monomers.

4. The adhesive composition of any one of claims 1 to 3, wherein the adhesive composition further comprises a polyol.

5. The adhesive of any one of claims 1 to 4, wherein the adhesive composition further comprises a photoacid generator.

6. The adhesive composition of any one of claims 1 to 5, wherein the (meth)acrylic polymer comprising polymerized units of monofunctional (meth)acrylate monomers is free of isobomyl (meth)acrylate.

7. The adhesive composition of any one of claims 1 to 6, wherein the adhesive composition has two Tgs after curing of the monofunctional (meth)acrylate monomers and epoxy resin component.

8. The adhesive composition of any one of claims 3 to 7, wherein a homopolymer of one or more of the low Tg (meth)acrylate monomer(s) has a Tg less than -10, -20, -30, -40, -50, or -60°C.

9. The adhesive composition of any one of claims 3 to 8, wherein the low Tg (meth)acrylate monomer(s) are present in an amount of at least 30, 40, 50, or 60 wt.%.

10. The adhesive composition of any one of claims 3 to 9, wherein the low Tg monomer(s) (meth)acrylate monomer(s) comprise an alkyl group with 4 to 12 carbon atoms.

11. The adhesive composition of any one of claims 3 to 10, wherein the non-acidic polar (meth)acrylate monomer(s) comprises an ether group or a hydroxyl group.

12. The adhesive composition of any one of claims 3 to 11, wherein a homopolymer of one or more of the non-acidic polar (meth)acrylate monomer(s) has a Tg less than -10, -20, -30, -40, or -50°C.

13. The adhesive composition of any one of claims 3 to 12, wherein one or more of the non-acidic polar (meth)acrylate monomer(s) has a Tg of at least 40, 50, 60, 70, 80, or 90°C.

14. The adhesive composition of any one of claims 3 to 13, wherein one or more of the non-acidic polar (meth)acrylate monomer(s) comprises a cycloaliphatic moiety.

15. The adhesive composition of any one of claims 3 to 14, wherein one or more of the non-acidic polar (meth)acrylate monomer(s) comprising an epoxy moiety.

16. The adhesive composition of any one of claims 1 to 15, wherein the epoxy resin(s) comprises an aromatic group inclusive of a bisphenol moiety.

17. The adhesive composition of any one of claims 1 to 16, wherein the adhesive composition further comprises a hydroxy -functional component inclusive of polyether polyols.

18. The adhesive of any one of claims 1 to 17 wherein the adhesive composition further comprises up to 2 wt.% of a multifunctional (meth)acrylate crosslinker.

19. The adhesive of any one of claims 1 to 18, wherein the menthyl (meth)acrylate is L-menthyl (meth)acrylate.

20. The adhesive of any one of claims 1 to 19, wherein the menthyl (meth)acrylate is derived from L- menthol.

21. The adhesive of claim 20, wherein the menthyl (meth)acrylate is derived from biobased L- menthol.

22. The adhesive composition of any one of claims 1 to 21 wherein the adhesive composition is partially or fully cured.

23. The adhesive composition of any one of claims 1 to 22, wherein the adhesive composition is a liquid adhesive that can undergo curing via actinic radiation to form a semi-structural bond or a structural bond.

24. An article comprising at least one layer of the adhesive composition of any one of claims 1 to 23, disposed on a major surface of a substrate.

25. The article of claim 24, wherein the substrate is selected from the group consisting of a metal, a glass, a coated glass, a plastic, a polymeric film, a release liner, and combinations thereof.

26. The article of claim 24 or claim 25, wherein the article is a tape comprising a layer of the adhesive composition disposed on one major surface or both major surfaces of the substrate.

27. The article of any one of claims 24 to 26, wherein the epoxy resin component is uncured.

28. A method of bonding comprising: providing the article of any one of claims 24 to 27; contacting a layer of the adhesive composition with a surface of the article; and curing the epoxy resin component.

29. The method of claim 28, wherein the surface of the article comprises metal, plastic, or glass.

30. A method of preparing the adhesive composition of any one of claims 1 to 23, the method comprising: a. polymerizing a monomer mixture of (methjacrylate monomers to produce a (methjacrylate copolymer; b. combining the (methjacrylate copolymer with an epoxy resin to provide a mixture; and c. combining the mixture with a photoacid generator to provide the adhesive composition.

31. The method of claim 30, wherein step b further comprises adding a polyol.

32. The method of claim 30 or 31, wherein the monomer mixture comprises unreacted monomers.

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