Toughening adhesives based on (meth) acrylates

Abstract

Structural adhesives, which contain, in addition to at least one toughening agent immiscible in methacrylic acid adhesives, a core-shell toughening component miscible in methacrylic acid-based adhesives, result in surprisingly improved impact resistance, in particular side impact testing.

Description

Technical Field

[0001] The present invention relates to a (meth)acrylate-based adhesive composition comprising a toughening agent that is soluble and / or miscible in (meth)acrylate and that increases impact toughness properties. Background Art

[0002] Current structural adhesives contain various tougheners to increase their performance in terms of impact resistance. Some of the more common toughener additives that have been shown to be useful for improving performance characteristics including impact resistance include butadiene-styrene solid rubber particles, such as those sold under the commercial Blendex brand. Another known and useful toughener is Kraton D1155, which is described by its manufacturer (Kraton Corporation) as a linear block copolymer based on styrene and butadiene with 40% by mass of bound styrene. Kraton D 1155 is provided in the form of porous pellets coated with amorphous silica. Another commercially available useful toughener is Hypro RLP 200X 168VTM, which is described by its manufacturer (CVC Thermoset Specialties) as a reactive liquid polybutadiene polymer terminated with methacrylate groups. Although tougheners such as these can enhance performance characteristics, they are not easily dispersed, miscible or dissolved in (meth)acrylates, and therefore suffer from various processability and cost issues. Therefore, current (meth)acrylic acid (e.g., (meth)acrylate) based adhesive compositions employing these commercially available materials (and other similar materials) require additional time and expense to ensure that these solid materials are properly incorporated into the (meth)acrylate to achieve the desired toughness. For example, failure to ensure proper dispersion of these toughening agents in their respective adhesive compositions is expected to negatively impact the performance properties of the final adhesive composition.

[0003] Therefore, it would be particularly advantageous to include a toughener material that can be easily incorporated into (meth)acrylic-based adhesives, that is readily miscible and / or soluble in (meth)acrylates, and that exhibits improved impact resistance. The present invention provides compositions comprising toughener materials and toughened compositions that address this problem and provide improved performance properties. Summary of the invention

[0004] An adhesive composition comprising:

[0005] a) Part I, which contains:

[0006] i. (meth)acrylate component;

[0007] ii. from about 10% to about 25% by weight of the total composition of a core-shell impact modifier comprising a polymeric core and at least two polymeric layers surrounding the core, each layer having a different polymeric composition than the other layer, and wherein at least one polymeric layer comprises a polymer that is a gradient polymer, the gradient polymer being a copolymer composed of at least two different monomers (A) and (B) and having a gradient of repeating units arranged along the copolymer from predominantly monomer (A) to predominantly monomer (B);

[0008] iii. about 10% to about 25% by weight of the total composition of a toughening component selected from polybutadiene rubber particles (Kraton D), liquid methacrylate-terminated polybutadiene polymers (Hypro RLP), and combinations thereof;

[0009] iv. amines;

[0010] b) Part II, which contains:

[0011] i. epoxides; and

[0012] ii. Peroxide;

[0013] wherein after curing, the composition exhibits at least a 50% increase in side impact strength compared to a substantially identical composition lacking the impact modifier.

[0014] An adhesive composition comprising the reaction product of:

[0015] a) Part I, which contains:

[0016] i. (meth)acrylate component;

[0017] ii. from about 10% to about 25% by weight of the total composition of a core-shell impact modifier comprising a polymeric core and at least two polymeric layers surrounding the core, each layer having a different polymeric composition than the other layer, and wherein at least one polymeric layer comprises a polymer that is a gradient polymer, the gradient polymer being a copolymer composed of at least two different monomers (A) and (B) and having a gradient of repeating units arranged along the copolymer from predominantly monomer (A) to predominantly monomer (B);

[0018] iii. about 10% to about 25% by weight of the total composition of a toughening component selected from the group consisting of polybutadiene rubber particles, liquid methacrylate-terminated polybutadiene polymers, and combinations thereof;

[0019] iv. amines;

[0020] b) The second part, which contains:

[0021] i. epoxides; and

[0022] ii. Peroxide;

[0023] wherein after curing, the composition exhibits at least a 50% increase in side impact strength compared to a substantially identical composition lacking the impact modifier. DETAILED DESCRIPTION

[0024] The present invention seeks to provide improved toughness properties and especially improved impact resistance properties by including a toughening agent component that is miscible in the methacrylate composition and provides unexpected improvements in impact resistance properties. Generally, the composition of the present invention may include the following components and ranges:

[0025] Components Weight % Range Methyl Methacrylate 20-80%; ideally 30-60%; more ideally 35-45% Acrylic acid monomer stabilizer 0.05-1%; ideally 0.1-0.5% Curing agent 0.05-5%; ideally 0.5-4% Toughening agent 10-60%; ideally 20-50%; more ideally 35-45% Adhesion promoter 1-30％ Rheology Modifiers 0.05-10%; ideally 0.1-5%

[0026] In the context of this disclosure, a number of terms will be used.

[0027] The term "(meth)acrylate" means both "acrylate" and "methacrylate" or either one of them.

[0028] The term "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid" or either one of them.

[0029] The term "monomer" refers to a polymer building block that has a defined molecular structure and that can react to form a part of a polymer.

[0030] The term "oligomer" refers to a molecule comprising at least two repeating units.

[0031] The term "hydrocarbon or hydrocarbon group" refers to an organic compound composed of carbon and hydrogen. Examples of hydrocarbon groups include, but are not limited to, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, tert-butyl, isobutyl, etc.; alkenyl groups such as vinyl, allyl, butenyl, pentenyl, hexenyl, etc.; aralkyl groups such as benzyl, phenethyl, 2-(2,4,6-trimethylphenyl)propyl, etc.; or aryl groups such as phenyl, tolyl, and xylyl, etc.

[0032] The term "optionally substituted" in the term "optionally substituted hydrocarbon group" means that one or more hydrogens on the hydrocarbon group may be replaced by a corresponding number of substituents, and the substituents are preferably selected from halogen, nitro, azido, amino, carbonyl, ester, cyano, sulfide, sulfate, sulfoxide, sulfone, sulfone and the like.

[0033] The term "glass transition temperature" refers to the temperature at which a polymer transitions between a highly elastic state and a glassy state. The glass transition temperature can be measured, for example, by differential scanning calorimetry (DSC).

[0034] The compositions of the present invention are typically two-part compositions (Part (A) and Part (B)) as described below, but in some cases may be made into one-part compositions.

[0035] Part (A)

[0036] Part (A) comprises at least a (meth)acrylic component (e.g., a methacrylate base material); a toughening agent component comprising a core-shell impact modifier miscible in the methacrylic component; at least one additional toughening agent and an amine. Other components may be added to part (A), including stabilizers, cure accelerators, adhesion promoters, rheology modifiers, and other useful materials as described herein.

[0037] (Meth) acrylic acid component

[0038] The (meth)acrylic component may comprise any suitable material containing at least one group having the formula:

[0039]

[0040] Wherein R is selected from H, halogen or C1 to C10 hydrocarbon group.

[0041] Advantageously, the group is a (meth)acryloyloxy group. The term "(meth)acryloyloxy" is intended to refer to both acrylates and methacrylates, wherein R is H or methyl, respectively. Useful amounts of the (meth)acrylic component are generally from about 20% to about 80% by weight of the total composition, and ideally from about 30% to about 60% by weight of the total composition, and more ideally from about 40% to about 50% by weight.

[0042] The (meth)acrylic component may be present in the form of a polymer, a monomer or a combination thereof. When present in the form of a polymer, the (meth)acrylic component may be a polymer chain connecting at least one of the groups shown above. The groups may be located at the side chain or terminal position of the main chain or a combination thereof. Advantageously, at least two such groups may be present and may be located at the terminal 65 position. The (meth)acrylic component may have a polymer chain consisting of polyvinyl, polyether, polyester, polyurethane, polyamide, epoxide, vinyl ester, phenol, amino resin, oil base, etc., as is well known to those skilled in the art, or in random or block combinations.

[0043] The polymer chain can be formed by polymerization of vinyl monomers. Illustrative examples of such vinyl monomers are methyl (meth)acrylate, (meth)acrylic acid, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, ) cresyl acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, octadecyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, 2-(meth)acryloyloxypropyltrimethoxysilane, (meth)acrylic acid-ethylene oxide adduct, trifluoromethyl methyl (meth)acrylate, 2-trifluoromethylethyl (meth)acrylate, 2-perfluoroethylethyl (meth)acrylate, 2-perfluoroethyl -2-Perfluorobutyl ethyl ester, 2-perfluoroethyl (meth)acrylate, perfluoromethyl (meth)acrylate, diperfluoromethyl methyl (meth)acrylate, 2-perfluoromethyl-2-perfluoroethyl methyl (meth)acrylate, 2-perfluorohexylethyl (meth)acrylate, 2-perfluorodecylethyl (meth)acrylate, 2-perfluorohexadecylethyl (meth)acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, dipentaerythritol monohydroxypentaacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, neopentyl glycol Diacrylate, pentaerythritol tetraacrylate, 1,2-butylene glycol diacrylate, trimethylolpropane ethoxylate tri(meth)acrylate, glyceryl propoxylate tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, tri(propylene glycol) di(meth)acrylate, neopentyl glycol propoxylate di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, and ethoxylated bisphenol A di(meth)acrylate. These monomers may each be used alone or a plurality of them may be copolymerized.

[0044] Particularly desirable (meth)acrylate monomers include those in which the alcohol portion of the ester group contains 1 to 8 carbon atoms. For example, 2-ethylhexyl (meth)acrylate, hydroxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, ethyl (meth)acrylate, 1,3-butanediol di(meth)acrylate (BDMA), butyl (meth)acrylate, and methyl (meth)acrylate (MMA) are examples.

[0045] Core-Shell Impact Modifier Components

[0046] Core-shell impact modifiers are ideally "core-shell" graft copolymers. The shell portion may be polymerized from methyl methacrylate and optionally other (meth) alkyl acrylates, such as ethyl (meth) acrylate, butyl (meth) acrylate, or a mixture thereof. Up to 40% by weight or more of the shell monomer may be styrene, vinyl acetate, vinyl chloride, and the like. Other core-shell graft copolymers that may be used in embodiments of the present invention are described in U.S. Pat. Nos. 3,984,497; 4,096,202; 4,034,013; 3,944,631; 4,306,040; 4,495,324; 4,304,709; and 4,536,436, the entire contents of which are incorporated herein by reference. Examples of core-shell graft copolymers include, but are not limited to, "MBS" (methacrylate-butadiene-styrene) polymers, which are prepared by polymerizing methyl methacrylate (MMA) in the presence of polybutadiene or polybutadiene copolymer rubber. MBS graft copolymer resins typically have a styrene butadiene rubber core and an acrylic polymer or copolymer shell. Other useful examples of core-shell graft copolymer resins include ABS (acrylonitrile-butadiene-styrene), MABS (methacrylate-acrylonitrile-butadiene-styrene), ASA (acrylate-styrene-acrylonitrile), all acrylics, SA EPDM (styrene-acrylonitrile grafted onto an elastomeric backbone of ethylene-propylene diene monomers), MAS (methacrylic acid-acrylic rubber styrene, etc. and mixtures thereof.

[0047] The core-shell impact modifier comprises a polymer core and at least two polymer layers surrounding the core, each layer having a different polymer composition than the other layer, and wherein at least one polymer layer comprises a polymer that is a gradient polymer, which is a copolymer composed of at least two different monomers (A) and (B) and has a gradient of repeating units arranged along the copolymer from predominantly monomer (A) to predominantly monomer (B).

[0048] The core-shell impact modifier should comprise particles having a particle size of 170 to 350 nm and a pH of 6 to 7.5, the particles comprising: a polymer rubber core comprising at least partially crosslinked isoprene or butadiene and optionally styrene; and at least two polymer layers, at least one of which is an outermost thermoplastic shell layer having a Tg greater than 25°C, each layer having a different polymer composition.

[0049] The core-shell impact modifier should comprise a polymer rubber core surrounded by a polymer layer, the polymer layer being a polymer core layer having a glass transition temperature below 0°C and a different polymer composition than the polymer rubber core, wherein the polymer core layer is a gradient region.

[0050] The core-shell impact modifier should comprise at least one polymer core layer and at least two polymer shell layers, the polymer core layer having a different composition than the polymer shell layers, wherein each shell layer has a different polymer composition than another shell layer, and wherein at least one polymer shell layer is a gradient region.

[0051] The core-shell impact modifier should comprise a polymer rubber core having a glass transition temperature of less than 0°C, such as less than about -10°C, desirably less than about -20°C, and advantageously less than about -25°C, and most advantageously less than about -40°C, such as from about -80°C to about -40°C.

[0052] The core-shell impact modifier should contain a polymer rubber core composed of any one or more of an isoprene homopolymer or a butadiene homopolymer, an isoprene-butadiene copolymer, a copolymer of isoprene and up to 98% by weight of a vinyl monomer, and a copolymer of butadiene and up to 98% by weight of a vinyl monomer. The vinyl monomer may be styrene, an alkyl styrene, acrylonitrile, an alkyl (meth) acrylate, or butadiene or isoprene. Ideally, the core should be composed of one of a polybutadiene, a copolymer of butadiene and styrene, or a terpolymer of methyl methacrylate, butadiene, and styrene.

[0053] In some embodiments, the core may also be covered by a core layer. By core layer is meant that the polymer composition of the core layer has a glass transition temperature (Tg) of less than 0°C, such as less than about -10°C, desirably less than about -20°C, and advantageously less than about -25°C. Desirably, the core layer is a gradient polymer.

[0054] The core-shell impact modifier should have more than one shell, ideally two shells. At least the outer shell in contact with the thermoplastic matrix has a Tg greater than about 25°C, such as greater than about 50°C.

[0055] The shell of the core-shell impact modifier may be composed of one or more of the following: a styrene homopolymer, an alkylstyrene homopolymer or a methyl methacrylate homopolymer, or a copolymer comprising at least 70% by weight of one of the above monomers and at least one comonomer selected from the group consisting of the other above monomers, another alkyl (meth)acrylate, vinyl acetate and acrylonitrile. The shell may be functionalized, for example, with anhydrides of unsaturated carboxylic acids, unsaturated carboxylic acids and unsaturated epoxides, such as maleic anhydride, (meth)acrylic acid, glycidyl methacrylate, hydroxyethyl methacrylate and alkyl (meth)acrylamides.

[0056] Gradient copolymers are produced by occupying a position between two layers, and in doing so, a gradient region is produced, wherein one side is more enriched in monomers / polymers from an adjacent layer and the other side is more enriched in different monomers / polymers that form the next layer. The gradient region between a core and a shell or between two polymer shells can be produced, for example, by reacting monomers with different copolymerization parameters or by reacting in a semi-continuous mode under underfeed conditions, wherein the rate of adding monomers is slower than the reaction rate. However, a gradient polymer is never the outermost layer of a core-shell particle.

[0057] The monomers used to form the gradient polymer are selected from the monomers described for the core and the corresponding shell depending on the function of the adjacent layers.

[0058] The Young's modulus of the polymer rubber core is always lower than the moduli of the other polymer layers. The Young's modulus of the layer comprising the gradient polymer is always lower than the modulus of the outermost layer.

[0059] The core-shell impact modifier should be in the form of fine particles having a rubber core and at least one thermoplastic shell, with a particle size typically less than 1 μm and advantageously 50 to 500 nm, preferably 100 to 400 nm, and most preferably 150 to 350 nm, advantageously 170 to 350 nm.

[0060] Core-shell impact modifiers can be prepared by emulsion polymerization. For example, a suitable method is a two-stage polymerization technique, in which the core and shell are produced in two continuous emulsion polymerization stages. If there are more shells, another emulsion polymerization stage is then carried out. Graft copolymers are obtained by graft polymerization of monomers or monomer mixtures containing at least aromatic vinyl, alkyl methacrylate or alkyl acrylate in the presence of a latex containing a butadiene-based rubber polymer. For more detailed information on the method for making such core-shell impact modifiers, see U.S. Patent Nos. 9,068,036 and 9,714,314. Commercial examples of such core-shell impact modifiers are commercially available from Arkema Inc., Cary, NC under the trade name CLEARSTRENGTH. Arkema describes, for example, CLEARSTRENGTH XT100 as a methyl methacrylate-butadiene-styrene core-shell toughener that is compatible with a variety of monomers and easily dispersed in most liquid resin systems, and exhibits limited effects on their viscosity while providing toughening effects over a wide range of service temperatures.

[0061] Additional toughening agents

[0062] The composition of the present invention also comprises at least one toughening component selected from "shellless" crosslinked rubber particles, such as acrylonitrile-butadiene-styrene (ABS), methacrylate-butadiene-styrene (MBS) and methacrylate-acrylonitrile-butadiene-styrene (MABS). For example, BLENDEX 338 is an ABS powder from GE Plastics. Another example is Kraton D 1155, a linear block copolymer based on styrene and butadiene with 40% by mass of bound styrene. Kraton D 1155 is provided in the form of porous pellets coated with amorphous silica. Another commercially available useful toughening agent is Hypro RLP 200X 168VTM, a reactive liquid polybutadiene polymer terminated with methacrylate groups.

[0063] amine

[0064] Part A of the composition of the present invention comprises at least one amine which acts as a catalyst by accelerating or otherwise promoting the curing of the composition of the present invention. The amine is desirably a tertiary amine or a sterically hindered amine. Suitable amines include, for example, tertiary amines represented by the formula NR3, wherein R is selected from alkyl, aryl, alkaryl or aralkyl, including C 1-10 Alkyl, C 1-18 Aryl, C 7-17 Alkyl and C 7-15 Suitable hindered amines also include primary or secondary amines, such as HNR2 or H2NR, wherein R is C 4-10Alkyl. For example, alkyl groups such as tert-butyl or neopentyl sterically shield the hydrogen bound to the nitrogen atom and are suitable substituents in this component of the present invention. For tertiary or secondary amines, the R groups can be connected so that the nitrogen is embedded in the ring structure.

[0065] Particularly useful amines for inclusion in the compositions of the present invention include, for example, 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), 1,4-diazabicyclo(2.2.2)octane (DABCO), triethylamine, and substituted guanidines such as tetramethylguanidine (TMG), dimethyl-p-toluidine (DMPT), dimethylaniline, dihydroxyethylaniline, dihydroxyethyl-p-toluidine, dimethyl-o-toluidine, dialkylanilines, dialkyltoluidines, and the like, acyl-thioureas, benzoyl-thioureas, and aryl-thioureas.

[0066] The amine may be present in an amount of about 0.01 wt % to about 5 wt %. Ideally, the amine is present in an amount of about 0.05 wt % to about 2 wt %. More ideally, the amine is present in an amount of about 0.3 wt % to about 0.7 wt %.

[0067] The composition of the present invention may also desirably include an acid or acid ester. Suitable acids or acid esters include phosphoric acid or its derivatives, phosphate esters, and sulfonic acid or their derivatives. The preferred reactive acid component is a phosphate ester. Acid monomers are free radical polymerizable acid monomers, such as ethylenically unsaturated monocarboxylic acids or polycarboxylic acids, maleic acid, and crotonic acid. Desirable monomers include methacrylic acid (MAA) and acrylic acid. Their active acid components also regulate and slow down the curing time of the thermosetting composition. Amine components are necessary for curing the epoxy-containing part (B), but in the absence of a phosphate ester component, the amine-induced curing process is usually too fast for very large parts or laminates, making the manufacture of the laminate too difficult. In addition, too fast curing can cause problems during curing, such as excessive heat from the exothermic curing reaction, resulting in inconsistent or uneven curing, and the resulting product may have undesirable physical properties, such as blistering, brittleness, or a smaller tensile strength than can be obtained when curing at a greater measured rate. Suitable phosphate esters include those represented by the following formula:

[0068]

[0069] Where R 1 H or CH 3 , and R 2 is H, or a group represented by the following structure:

[0070]

[0071] Where R 1 H or CH 3A particularly useful phosphate ester is hydroxyethyl methacrylate (HEMA) phosphate, which is sold under the tradenames T-MULZ 1228 or HARCRYL 1228 or 1228M, all available from Harcross Chemicals, Kansas City, KS. Also included are phosphates having at least one strong acid "active hydrogen" group or having at least one phosphonic acid active hydrogen group (R 1 R 2 The structure of POOH) such as hydroxyethyl diphosphonic acid, phosphonic acid and derivatives or oligomeric or polymeric structures having phosphonic acid functional groups or similar acid strength functional groups.

[0072] The composition of part (A) may also desirably contain a free radical polymerization inhibitor, which prevents part (A) from reacting prematurely prior to mixing. Many suitable free radical polymerization inhibitors are known in the art and include quinones, hydroquinones, hydroxylamines, nitroxyl compounds, phenols, amines, arylamines, quinolones, phenothiazines, and the like. Particularly useful free radical inhibitors include hydroquinone, tert-butyl hydroquinone (TBHQ), methyl hydroquinone, hydroxyethyl hydroquinone, phenothiazines, and NAUGARD-R (a blend of N-alkyl-substituted p-phenylenediamines from Crompton Corp.). One or more separate free radical inhibitor components may also be combined.

[0073] Other additives

[0074] Parts (A) and (B) may also contain other additives, such as fillers, other core-shell polymers, lubricants, thickeners and colorants. Fillers provide volume without sacrificing the strength of the adhesive and may be selected from high or low density fillers. In addition, certain fillers, such as silica, may impart rheology modification or small particle reinforcement. Commercially available examples include those under the Cab-O-Sil brand, such as Cab-O-Sil 610, and those under the AEROSIL brand, such as AEROSIL R8200. Of particular interest are low density fillers.

[0075] Part (B)

[0076] Epoxide

[0077] Useful epoxide components include, but are not limited to, cycloaliphatic epoxides, epoxy novolac resins, bisphenol-A epoxy resins, bisphenol-F epoxy resins, bisphenol-A epichlorohydrin-based epoxy resins, alkyl epoxides, limonene dioxide, and polyepoxides. An ideal resin component is a cycloaliphatic epoxide sold by Dow Chemical under the trade name CYRACURE UVR-6110. UVR-6110 has the following structure:

[0078]

[0079] Another suitable resin component is a bisphenol-based liquid epoxy resin, such as those sold by Dow Chemical under the trade name "DER." For a description of these epoxy resins, see http: / / epoxy.dow.com / epoxy / products / prod / liquid.htm. Examples of "DER" products suitable for use in the present invention include DER 332 (diglycidyl ether of bisphenol A); DER 330 (low viscosity, undiluted bisphenol-A liquid epoxy resin); DER 383 (low viscosity, undiluted bisphenol-A liquid epoxy resin); DER 354 (standard bisphenol-F based liquid epoxy resin); DER 351 (low viscosity, liquid bisphenol-A / F resin blend); DER 352 (low viscosity, liquid bisphenol-A / F resin blend); DER 324 (aliphatic glycidyl ether reactive diluent, modified liquid epoxy resin); DER 323 (aliphatic glycidyl ether reactive diluent, modified liquid epoxy resin); DER 325 (aliphatic glycidyl ether reactive diluent, modified liquid epoxy resin); and DER 353 (aliphatic glycidyl ether reactive diluent, modified liquid epoxy resin). A different brand of bisphenol-based liquid epoxy resin suitable for use in the present invention is EPON Resin 828, which is derived from bisphenol A and epichlorohydrin and is commercially available from Hexion Specialty Chemicals. http: / / www.hexionchem.com / pds / E / EPONTM Resin 828.pdf.

[0080] Another suitable resin component is an epoxy novolac resin, which is the product of epichlorohydrin and a novolac resin and is sold by Dow Chemical under the trade name DEN. For a description of these epoxy resins, see http: / / epoxy.dow.com / epoxy / products / prod / nov.htmExamples of "DEN" products suitable for use in the present invention include DEN 431 (a low viscosity semi-solid epoxy novolac resin) and DEN 438 (a semi-solid epoxy novolac resin). Other suitable epoxy resins include polyepoxides that can be cured at ambient temperature or at a suitable elevated temperature with a catalyst or hardener. Examples of these polyepoxides include polyglycidyl ethers and poly(3-methylglycidyl) ethers, which can be obtained by reacting a compound containing at least two free alcoholic and / or phenolic hydroxyl groups per molecule with an appropriate epichlorohydrin under alkaline conditions or alternatively in the presence of an acidic catalyst and subsequently treating with a base. These ethers can be made from acyclic alcohols such as ethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols, propane-1,2-diol and poly(oxypropylene) glycols, propane 1,3-diol, butane-1,4-diol, poly(oxytetramethylene) glycol, pentane-1,5-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol and poly(epichlorohydrin); from alicyclic alcohols such as resorcinol, p-cyclohexanediol, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and 1,1-bis(hydroxymethyl)-cyclohex-3-ene; and from alcohols with an aromatic core such as N,N-bis(2-hydroxyethyl)aniline and pip'-bis(2-hydroxyethylamino)diphenylmethane. Or they can be made from mononuclear phenols, such as resorcinol and hydroquinone, and from polynuclear phenols, such as bis(4-hydroxyphenyl)methane, 4,4'-dihydroxydiphenyl, bis(4-hydroxyphenyl)sulfone, 1.1.2.2-tetrakisbis(4-hydroxyphenyl)ethane, 2.2.-bis(4-hydroxyphenyl)propane (otherwise known as bisphenol A), 2.2-bis(3,5-dibromo-4-hydroxyphenyl)propane and novolacs formed from aldehydes such as formaldehyde, acetaldehyde, chloral and furfural with phenols such as phenol itself), and phenols substituted in the ring by chlorine atoms or by alkyl groups each containing up to nine carbon atoms, such as 4-chlorophenol, 2-methylphenol and 4-tert-butylphenol.

[0081] Poly(N-glycidyl) compounds include, for example, those obtained by dehydrochlorination of the reaction product of epichlorohydrin with an amine containing at least two amino hydrogen atoms, such as aniline, n-butylamine, bis(4-aminophenyl)methane and bis(4-methylaminophenyl)methane; triglycidyl isocyanurate; and N,N'-diglycidyl derivatives of cyclic alkylene ureas, such as ethylene urea and 1,3-propylene urea, and N,N'-diglycidyl derivatives of hydantoins, such as 5,5-dimethylhydantoin.

[0082] Epoxy resins having 12-epoxy groups attached to various kinds of heteroatoms may be used, such as N,N,O-triglycidyl derivatives of 4-aminophenol, glycidyl ether-glycidyl esters of salicylic acid, N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin, and 2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.

[0083] Also suitable are epoxides derived from oils, such as epoxidized soybean oil, epoxidized castor oil, etc. Also suitable are epoxides derived or derivable from the oxidation of unsaturated peracids, including epoxidized liquid rubbers.

[0084] peroxide

[0085] Benzoyl peroxide itself is a good choice for use in part (B). Commercially available compositions containing benzoyl peroxide may also be used. Benox-50 210 Blue (from 45 Syrgis Performance Initiators, Inc., Helena, AR), a peroxide paste believed to contain 49-50% benzoyl peroxide, is one good choice. Benox-55 108 White, a peroxide paste believed to contain 54-56% benzoyl peroxide, is another good choice. Another good choice is Varox 50 ASNS from RT Vanderbilt, Norwalk, Conn., a peroxide paste believed to contain 55% benzoyl peroxide.

[0086] Plasticizers

[0087] Plasticizer can be used in part (B) of the two-part composition. As noted above, plasticizer can also be used in part (A). Plasticizer can be any liquid or soluble compound that contributes to the flexibility of the reactive composition and / or can serve as a carrier for other components of the composition. Examples include aromatic sulfonamides, aromatic phosphates, alkyl phosphates, dialkyl ether aromatic esters, polymer plasticizers, dialkyl ether diesters, polyglycol diesters, tricarboxylic acid esters, polyester resins, aromatic diesters, aromatic triesters (trimellitates), aliphatic diesters, epoxidized esters, chlorinated hydrocarbons, aromatic oils, alkyl ether monoesters, naphthenic oils, alkyl monoesters, paraffin oils, silicone oils, di-n-butyl phthalate, diisobutyl phthalate, di-n-hexyl phthalate, di-n-heptyl phthalate Esters, di-2-ethylhexyl phthalate, 7C, -9C-phthalate (linear and branched), diisooctyl phthalate, linear 6C-10C phthalate, diisononyl phthalate, linear 7C-10C phthalate, diisodecyl phthalate, linear 9C-11C phthalate, diundecyl phthalate, diisodecyl glutarate, di-2-ethylhexyl adipate, di-2-ethylhexyl azelate, Di-2-ethylhexyl sebacate, di-n-butyl sebacate, diisodecyl adipate, triethylene glycol decanoate octanoate, triethylene glycol 2-ethylhexyl adipate, dibutoxyethyl adipate, dibutoxy-ethoxyethyl adipate, dibutoxyethoxyethyl formal, dibutoxy-ethoxyethyl sebacate, tri-2-ethylhexyl trimellitate, tri-(7C-9C (linear)) trimellitate, tri-(8C-10C (linear)) trimellitate, phosphoric acid Triethyl ester, triisopropylphenyl phosphate, tributyl phosphate, 2-ethylhexyl diphenyl phosphate, trioctyl phosphate, isodecyl diphenyl phosphate, triphenyl phosphate, triaryl phosphate synthesis, tributoxyethyl phosphate, tri(chloro-ethyl) phosphate, butylphenyl diphenyl phosphate, chlorinated organic phosphate, cresyl diphenyl phosphate, tri(dichloropropyl) phosphate, isopropyl phenyl diphenyl phosphate, tri(xylene) phosphate, tricresyl phosphate, diphenyl octyl phosphate.

[0088] Block copolymers

[0089] When used, the block copolymer can be any block copolymer that can contribute to the desired physical properties of the disclosed compositions.The block copolymer can be used in either part (A) or part (B).

[0090] Block copolymer rubbers may be constructed using blocks of butadiene or isoprene with styrene (eg, SBS, SIS, SEBS, and SB), commercial examples of which are available from Shell Chemical Co. as KRATON D-1116 and other KRATON D-grade elastomers, and from Dexco as VECTOR 2411IP.

[0091] Other elastomers having a Tg below about 25°C, which are soluble in methacrylate / acrylate monomers, may replace the polychloroprene and / or block copolymer rubbers. Examples of this class are homopolymers of epichlorohydrin and copolymers of epichlorohydrin and ethylene oxide (available from Zeon Chemicals, such as HYDRIN), acrylate rubber pellets (available from Zeon, such as HYTEMP), polyisoprene rubber, polybutadiene rubber, nitrile rubber, and SBR rubber (a random copolymer of butadiene and styrene).

[0092] In addition, the other block copolymer may be a styrene maleic anhydride copolymer, represented by the following formula:

[0093]

[0094] Styrene maleic anhydride copolymers are well known and some are commercially available, for example, under the trade name SMA EFSO from Sartomer Company, Inc., Exton, Pa. Styrene maleic anhydride copolymers refer to the copolymerization product of styrene and maleic anhydride and are characterized by alternating blocks of styrene and maleic anhydride moieties.

[0095] Amphiphilic block copolymers may be particularly desirable. Arkema sells amphiphilic block copolymers commercially under the trade name NANOSTRENGTH. Such block copolymers are currently available in two forms: SBM and MAM. SBM copolymers are reportedly made from polystyrene, 1,4-polybutadiene, and syndiotactic poly(methyl methacrylate).

[0096] In addition, polymer materials composed of polymethyl methacrylate ("PMMA") and polybutyl acrylate ("PB") can also be used. The polymer materials within this category are called polymethyl methacrylate-block-polybutyl acrylate-block polymethyl methacrylate copolymers ("MAM"). According to Arkema, MAM is a triblock copolymer composed of about 70% PMMA and 30% PB. MAM is composed of different segments, which provide the ability to self-assemble at the molecular scale. That is, M gives the polymer hardness and A gives the polymer elastic properties. The hard polymer segments tend to be soluble in (meth)acrylates, while the elastomeric segments provide toughness to the poly(meth)acrylates formed when cured. MAM also enhances mechanical properties without compromising inherent physical properties. MAM is commercially available under the trade name NANOSTRENGTH and is currently commercially available in several different grades, namely E-21 and M-52N.

[0097] Arkema promotes the NANOSTRENGTH product line as acrylic block copolymers that are miscible with many polymers, most of which are major industrial epoxy resins according to the manufacturer. See also U.S. Patent No. 6,894,113, wherein in its abstract, the '113 patent mentions a thermoset having modified impact resistance. The impact resistance comes from 1 to 80% of an impact modifier comprising at least one copolymer containing SBM, BM and MBM blocks, wherein each block is linked to the other blocks by a covalent bond or is linked to one of the blocks intermediately by a covalent bond and to the other blocks by another covalent bond, M is a PMMA homopolymer or a copolymer comprising at least 50 weight percent methyl methacrylate, B is incompatible with the thermoset resin and the M block and has a glass transition temperature, Tg, less than the operating temperature of the thermoset, and S is incompatible with the thermoset resin, the B block and the M block and has a Tg or its melting temperature greater than the Tg of B.

[0098] Another commercially available example of an amphiphilic block copolymer is a polyether block copolymer known under the trade name FORTEGRA 100 from Dow Chemical Co. Dow describes FORTEGRA 100 as a low viscosity toughening agent used as an efficient second phase in amine-cured epoxy resin systems. FORTEGRA 100 is reported to provide improved toughness without significantly affecting the viscosity, glass transition temperature, corrosion resistance, cure rate or chemical resistance of the final coating or composition. FORTEGRA 100 is reported to be useful for formulation into standard bisphenol A and bisphenol F epoxy resin systems because it does not participate in the epoxy resin curing reaction. As a second phase toughening agent, FORTEGRA 100 is advertised as being effective when formulated in a specific volume fraction of the finished film or part, typically 3% to 8% by dry volume is said to achieve a toughening effect.

[0099] Other block copolymers include those containing both hydrophobic and hydrophilic segments, or portions of the following general formula:

[0100] -[(R 1 ) v -(R 2 ) w l n -

[0101] Here, R1 is independently a hydrophobic olefin, such as ethylene, propylene, 1-butene, 1-hexene, 3-methyl-1-hexene, or 4-methyl-1-pentene, or a polymerizable hydrophobic aromatic hydrocarbon, such as styrene; each R 2 is a hydrophilic anhydride such as maleic anhydride; v is 1 to 12; w is 1 to 6; and n is 1 to 50.

[0102] Other additives

[0103] Parts (A) and (B) may contain other additives such as fillers, lubricants, thickeners and colorants. Fillers provide bulk without sacrificing the strength of the adhesive and may be selected from high or low density fillers.

[0104] Package

[0105] Each of parts (A) and (B) is packaged in a separate container, such as a bottle, can, tube or barrel. Parts (A) and (B) are mixed in a weight ratio of about 3 to 50 parts (A) to one part (B). Preferably, the weight ratio of parts (A) and (B) is about 5 to 20 parts (A) to one part (B).

[0106] The two parts can be mixed using a mixing nozzle that has fluid inputs for the two components, performs a suitable mixing operation and dispenses the adhesive mixture directly onto the surface to be bonded. Examples of commercially available mixing and dispensing devices are the The two parts can also be mixed manually in a bowl, bucket, etc., but the operator needs to ensure thorough mixing. As an aid to ensuring complete mixing, each part can be formulated with a dye or pigment so that after mixing, a third color is formed. For example, one part can have a yellow dye and the other part can have a blue dye so that after mixing, the entire adhesive composition will be green.

[0107] The term "curing" means the chemical reaction that converts the fluid mixture into the solid bond of the present invention. The curing process of the composition is exothermic and can reach temperatures of around 120°C when large adhesive beads are used.

[0108] Example

[0109] Loctite HHD8540 is a 2-part commercial structural adhesive used as a comparison for the compositions of the present invention. Each of the following inventive examples uses the methyl methacrylate-butadiene-styrene core-shell toughening additive of the present invention as a replacement for one or more toughening agents in the Loctite HHD8540 composition; or as an additional toughening additive in addition to one or more toughening agents in the Loctite HHD8540 composition, as shown in the following table.

[0110] Part (B) of the commercial composition Loctite HHD8540 remained constant for all compositions, as shown in the table below for each of the composition groups of the invention.

[0111] The mixing ratio by weight of part (A) to part (B) was 10: 1. The mixed product was cured at 45°C for 20 minutes and then at room temperature for 24 hours before any testing.

[0112] test

[0113] For Izod impact resistance, double-sized aluminum lap shear pieces were used and tested using ASTM D6110-18.

[0114] For side impact resistance, a sandblasted mild steel (GBMS) lap shear with a 5 mil gap was used. Side testing was performed using a drop tower impact tester and recorded by an instrumented hammer. A known block was dropped edgewise onto the bonded lap shear assembly at a specified speed. The force required to break the adhesive bond was recorded by an instrumented hammer. The side impact test was based on GM9751P Rev. August 2014 General Motors Engineering Standards Side Impact Test.

[0115] All compositions tested in the examples used the following Part (B) compositions.

[0116]

[0117]

[0118] Example 1

[0119] Table 1 shows commercially available prior art compositions and inventive compositions 1 to 4. Each of the inventive compositions additionally contains a core-shell impact modifier.

[0120]

[0121]

[0122] 1 ClearStrength XT 100, purchased from Arkema Inc., Cary, NC.

[0123] 2 Hypro TM Reactive liquid polymer methacrylate-terminated polybutadiene from CVC Thermoset Specialties, Moorestown, NJ;

[0124] 3 Comparative Example - Commercially available product from Henkel Corporation

[0125] 4Blendex 338 acrylonitrile butadiene styrene, available from Crompton Corp.

[0126] 5 Kraton D 1155 linear block copolymer of butadiene-styrene solid rubber particles, purchased from KratonCorp.

[0127] 6 BRC-641D polybutadiene urethane acrylate oligomer, purchased from Dymax Corp.

[0128] 7 BR-5541M—Difunctional flexible aliphatic polyether urethane methacrylate diluted in 20% isobornyl acrylate (IBOA) from Dymax Corp.

[0129] 8 IGI 1239 Paraffin

[0130] Each composition in Table 1 was tested for Izod impact resistance (ASTM D 6110-18).

[0131] Table 2 shows the test results. Compositions 1-3 incorporate a core-shell component miscible with methacrylate and another toughening agent component. As can be seen from the test values, compositions 1-4 of the present invention exhibit impact resistance comparable to or better than commercial compositions containing toughening agents Kraton D 1155 and Hypro RLP 2000X 168VTB that are immiscible in methyl methacrylate.

[0132]

[0133] Example 2

[0134]

[0135]

[0136] Each of the inventive compositions 4 and 5 was formulated as shown in Table 3 above and subjected to side impact testing, the results of which are shown in Table 4.

[0137] As shown in Table 4, incorporation of 13-15 parts by weight of the shell-core toughening component along with one or more immiscible toughening agents provides side impact results comparable to commercial Henkel compositions containing only the immiscible toughening agents.

[0138]

[0139] Example 3

[0140]

[0141]

[0142] Composition 7 in Table 5 above contains 15 parts by weight of a core-shell component in addition to Kraton D 1155 and Hypro 1300X33LC VTBNX, both of which are immiscible toughening components.

[0143] The results of the side impact test surprisingly showed that in the case of the combination of Kraton D 1155 and Hypro 1300X33LC VTBNX and the core-shell component, the impact resistance was increased by 53%.

[0144]

[0145]

[0146] Example 4

[0147]

[0148] Similar to Example 3, Composition 8 of the present invention also contains a combination of core-shell components, Kraton D 1155 and Hypro 1300X43LC VTBNX. The side impact test results (Table 8) show that the side impact resistance is increased by about 54%.

[0149]

[0150] Example 5

[0151]

[0152]

[0153] Composition 9 of the present invention contains about 22 parts by weight of a core-shell toughening component in combination with Blendex 338 (ABS rubber particles) and 13 parts by weight of Hypro RLP 2000X 1. Composition 10 of the present invention contains about 6.45 parts by weight of a core-shell toughening component in combination with 4.92 parts by weight of Blendex 338 and 22 parts by weight of Kraton D 1155.

[0154] Side impact testing of compositions 9 and 10 showed that the side impact resistance was each increased by about 41% compared to the commercially available Henkel product containing only the immiscible toughness.

[0155]

Claims

1. An adhesive composition comprising: a) A first part, the first part comprising: i. (meth)acrylate component; ii. from about 10% to about 25% by weight of the total composition of a core-shell impact modifier, the core-shell impact modifier comprising a polymer core and at least two polymer layers surrounding the core, each layer having a different polymer composition than the other layer, and wherein at least one polymer layer comprises a polymer that is a gradient polymer, the gradient polymer being a copolymer composed of at least two different monomers (A) and (B) and having a gradient of repeating units arranged along the copolymer from predominantly the monomer (A) to predominantly the monomer (B); iii. about 10% to about 25% by weight of the total composition of a toughening component selected from polybutadiene rubber particles (Kraton D), liquid methacrylate-terminated polybutadiene polymers (Hypro RLP), and combinations thereof; iv. amines; b) a second part, the second part comprising: i. epoxides; and ii. Peroxide; wherein after curing, the composition exhibits at least a 50% increase in side impact strength compared to a substantially identical composition lacking the impact modifier.

2. The composition of claim 1, wherein after curing, the composition exhibits at least a 60% increase in side impact strength compared to a substantially identical composition but lacking the impact modifier.

3. The adhesive composition of claim 1, wherein the core-shell impact modifier comprises particles having a particle size of 170 to 350 nm, the particles comprising a polymer rubber core comprising at least partially cross-linked isoprene or butadiene and optionally styrene; and at least two polymer layers, at least one of the polymer layers being an outermost thermoplastic shell layer having a Tg greater than 25°C, each layer having a different polymer composition.

4. The composition of claim 1, wherein the core-shell impact modifier comprises a polymer rubber core surrounded by a polymer layer, the polymer layer being a polymer core layer, the polymer core layer having a glass transition temperature below 0°C and a different polymer composition than the polymer rubber core, wherein the polymer core layer is the gradient region.

5. The composition of claim 1, wherein the core-shell impact modifier comprises a polymeric rubber core having a glass transition temperature of less than about -40°C.

6. The composition of claim 1, wherein the core-shell impact modifier comprises a polymeric rubber core having a glass transition temperature of about -80°C to about -40°C.

7. The composition of claim 1 wherein the core-shell impact modifier comprises a polymeric rubber core comprised of polybutadiene.

8. The composition of claim 1 wherein the core-shell impact modifier comprises a polymer rubber core comprised of butadiene and styrene.

9. The composition of claim 1, wherein the (meth)acrylic acid component of part (a) is selected from the group consisting of methyl (meth)acrylate, (meth)acrylic acid, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, cyclohexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-(meth)acrylate, 4-(tert-butyl ... Ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, toluene (meth)acrylate, benzyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, octadecyl (meth)acrylate, glycidyl (meth)acrylate, 2-aminoethyl (meth)acrylate, 2-(meth)acryloyloxypropyltrimethoxysilane, (meth) Acrylic acid-ethylene oxide adduct, trifluoromethyl methyl (meth)acrylate, 2-perfluorohexyl ethyl (meth)acrylate, 2-perfluorodecyl ethyl (meth)acrylate, 2-perfluorohexadecyl ethyl (meth)acrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, dipentaerythritol monohydroxypentaacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, pentaerythritol tetraacrylate, 1,2-butanediol diacrylate Acids, trimethylolpropane ethoxylate tri(meth)acrylate, glyceryl propoxylate tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, tri(propylene glycol) di(meth)acrylate, neopentyl glycol propoxylate di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, and combinations thereof.

10. The composition of claim 1 wherein the toughening component comprises polybutadiene rubber particles and a liquid methacrylate-terminated polybutadiene polymer.

11. The composition of claim 1, wherein the amine is selected from the group consisting of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), 1,4-diazabicyclo(2.2.2)octane, triethylamine, tetramethylguanidine, dimethyl-p-toluidine, dimethylaniline, dihydroxyethylaniline, dihydroxyethyl-p-toluidine, dimethyl-o-toluidine, dialkylanilines and benzoylthioureas, trialkylamines, tributylamine, dihydropyridines, phenyldihydropyridines, dihydropyridine derivatives, aldehyde condensation products of alkyl, aromatic, heterocyclic amines, and combinations thereof.

12. The composition of claim 1 further comprising a (meth)acrylate terminated polyurethane component.

13. The composition of claim 1, further comprising a triaryl phosphine or an alkyl aryl phosphine.

14. The composition of claim 13, wherein the phosphine is selected from the group consisting of tri(o-tolyl)phosphine, tri(4-methoxyphenyl)phosphine, diphenyl(p-tolyl)phosphine, diphenyl(o-tolyl)phosphine, tri(o-methoxyphenyl)phosphine, tri(p-tolyl)phosphine, diphenyl(2-methoxyphenyl)phosphine, tri(3,5-dimethylphenyl)phosphine and triphenylphosphine.

15. The composition of claim 1, wherein the first part and the second part are in a weight ratio of the first part (a) to the second part (b) of about 10: about 1.

16. The composition of claim 1, further comprising a free radical stabilizer selected from the group consisting of quinones, hydroquinones, and combinations thereof.

17. The composition of claim 1, further comprising a free radical stabilizer selected from the group consisting of hydroquinone, tert-butyl hydroquinone, phenothiazine, methyl hydroquinone, hydroxyethyl hydroquinone, N-alkyl substituted p-phenylenediamines, and combinations thereof.

18. The composition of claim 1, further comprising a component selected from the group consisting of plasticizers, fillers, block copolymers, thixotropic agents, rheology modifiers, viscosity modifiers, adhesion promoters, diluents, monomers, oligomers, and combinations thereof.

19. A method of bonding a first surface to a second surface, comprising: providing a two-part adhesive composition according to claim 1, providing a first surface to be bonded and a second surface to be bonded, dispensing the two-part adhesive composition onto at least one of the first surface or the second surface, mating the first surface with the second surface, wherein the adhesive composition is between the mated first and second surfaces, and An adhesive bond is formed therebetween.

20. The method of claim 19, wherein the first part and the second part are mixed in a weight ratio of the first part (a) to the second part (b) of about 10: about 1.

21. An adhesive composition comprising the reaction product of: a) A first part, the first part comprising: i. (meth)acrylate component; ii. from about 10% to about 25% by weight of the total composition of a core-shell impact modifier, the core-shell impact modifier comprising a polymer core and at least two polymer layers surrounding the core, each layer having a different polymer composition than the other layer, and wherein at least one polymer layer comprises a polymer that is a gradient polymer, the gradient polymer being a copolymer composed of at least two different monomers (A) and (B) and having a gradient of repeating units arranged along the copolymer from predominantly monomer (A) to predominantly monomer (B); iii. about 10% to about 25% by weight of the total composition of a toughening component selected from the group consisting of polybutadiene rubber particles, liquid methacrylate-terminated polybutadiene polymers, and combinations thereof; iv. amines; b) a second part, the second part comprising: i. epoxides; and ii. Peroxide; wherein after curing, the composition exhibits at least a 50% increase in side impact strength compared to a substantially identical composition lacking the impact modifier.

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