WO2012134735A1

WO2012134735A1 - Peroxide-free methacrylate structural adhesives

Info

Publication number: WO2012134735A1
Application number: PCT/US2012/027865
Authority: WO
Inventors: Frank Tran; Surendar N. Kaul
Original assignee: Huntsman Advanced Materials Americas Llc
Priority date: 2011-03-25
Filing date: 2012-03-06
Publication date: 2012-10-04

Abstract

The present disclosure relates to multipart structural adhesive systems that are substantially free of peroxide. Also provided are methods of preparing the multipart structural adhesive systems and methods of bonding substrates together with such adhesive systems.

Description

PEROXIDE-FREE METHACRYLATE

STRUCTURAL ADHESIVES

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Pat. App. Ser. No. 61/467,473 filed March 25, 2011 which is incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

FIELD OF THE INVENTION

[0003] The present invention is directed to multipart structural adhesives which are capable of safely and sufficiently bonding substrates. More particularly, the present invention relates to two-part, peroxide-free structural adhesive systems that exhibit high stability without impairing adhesion properties.

BACKGROUND OF THE INVENTION

[0004] Structural adhesives, including acrylic adhesive compositions, have been used in a variety of applications to bond various substrates, such as metal or plastic. These structural adhesives are generally supplied as two components that are mixed just prior to application. Structural adhesives known in the industry include, for example:

[0005] U.S. Pat. No. 3,591,438 which relates to a multi-part adhesive composition containing (A) a polymerizable acrylate ester and peroxy initiator and (B) a condensation reaction product of an aldehyde and amine and either a sulfur-containing free radical accelerator or a compound containing an oxidizable transition metal;

[0006] U.S. Pat. Nos. 4,112,013 and 3,890,407 which disclose two-part adhesives that may contain (A) a solution of a polymerizable vinyl monomer in either chlorosulfonated polyethylene or sulfonyl chloride + chlorinated polyethylene and (B) a peroxide; [0007] U.S. Pat. No. 4,403,058 which is directed to a two-part adhesive including an elastomer in either (A) an acrylic monomer, an organic peroxide, and a metal salt liquid solution and/or (B) an acrylic monomer and a curing accelerator liquid solution;

[0008] U.S. Pat. No. 5,264,525 which discloses a two-part adhesive composition containing (A) an acrylic monomer, chlorosulfonated polyethylene and a peroxide and (B) a condensation reaction product of an aldehyde and amine and an epoxy resin; and

[0009] U.S. Pat. No. 5,313,998 which relates to a two-part adhesive having (A) an acrylic and a peroxide and (B) a condensation reaction product of an aldehyde and amine and a copper salt and wherein an acid phosphate is added to either solution (A) or to both solutions (A) and (B).

[0010] More recently, U.S. Pat. No. 6,869,497 teaches a two part adhesive including (A) an acrylic monomer, a metal molybdate, and acrylic or methacrylic acid and (B) peroxide while U.S. Pat. Nos. 7,348,385 and 7,479,528 teach two part adhesives containing (A) acrylic monomer, chlorosulphonated polymer, and a peroxide and (B) a cycloheteroatom zirconate or titannate.

[0011] Known structural adhesives exhibit some shortcomings, for example, they exhibit inadequate heat stability, they contain hazardous peroxides, they exhibit slow cure, and/or have less than desired shear strengths. Therefore, there is a need for a structural adhesive that is environmentally friendly, storage-stable, and can be conveniently formulated and applied to provide strong bonds over a desired time range.

SUMMARY OF THE INVENTION

[0012] The present disclosure relates to a multipart structural adhesive system that is substantially free of peroxide. In one embodiment, the multipart adhesive system employs a part (A) containing a methacrylic component and a chlorosulfonated polymer and a part (B) containing an aldehyde-amine condensate and a metal quinolate.

[0013] The multipart structural adhesive system of the present disclosure may be used to bond a variety of substrates. Thus, in another embodiment, this disclosure provides a method for adhering a first surface to a second surface which includes: mixing a part (A) and a part (B) to form a curable composition, where the curable composition is substantially free of peroxide and where part (A) comprises a methacrylic component and a chlorosulfonated polymer and part (B) comprises an aldehyde-amine condensate and a metal quinolate; applying the curable composition to at least the first surface, pressing the second surface and the first surface together so that the curable composition is between the two surfaces for a time sufficient to effect curing of the curable composition. Advantageously, the curing occurs at room temperature.

DETAILED DESCRIPTION OF THE INVENTION

[0014] If appearing herein, the term "comprising" and derivatives thereof are not intended to exclude the presence of any additional component, step or procedure, whether or not the same is disclosed herein. In order to avoid any doubt, all compositions claimed herein through use of the term "comprising" may include any additional additive, adjuvant, or compound, unless stated to the contrary. In contrast, the term, "consisting essentially of if appearing herein, excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability and the term "consisting of, if used, excludes any component, step or procedure not specifically delineated or listed. The term "or", unless stated otherwise, refers to the listed members individually as well as in any combination.

[0015] The articles "a" and "an" are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article.

[0016] The term "alkyl" refers to a group derived from an aliphatic hydrocarbon and includes linear, branched or a cyclic group, which may be substituted or unsubstituted.

[0017] The term "alkenyl" refers to a straight-chain or branched hydrocarbon residue containing at least one carbon-carbon double bond which may be substituted or unsubstituted.

[0018] The term "alkylaryl" refers to a group having both alkyl and aryl moieties. [0019] The term "alkoxy' refers to an alkyl group which is attached through an oxygen atom.

[0020] The term "aryl" refers to a group derived from an aromatic hydrocarbon which may be substituted or unsubstituted.

[0021] The term "aryloxy" refers to an aryl group which is attached through an oxygen atom.

[0022] The term "cycloalkyl" refers to refers to a monovalent carbocyclic radical of 3 to 10 carbon atoms, preferably 3 to 6 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0023] The term "halogen" refers to fluorine, chlorine, bromine, and iodine.

[0024] The prefix "hetero" indicates that one or more carbon atoms have been replaced with a different atom.

[0025] The term "hydroxyl" refers to an -OH group.

[0026] The term "8-hydroxyquinolate" refers to a ligand derived from the compound 8- hydroxyquinoline, where the hydrogen on the hydroxy group is removed and the oxygen is coordinated to a metal.

[0027] The phrases "in one embodiment," "according to one embodiment," and the like generally mean the particular feature, structure, or characteristic following the phrase is included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention. Importantly, such phrases do not necessarily refer to the same embodiment.

[0028] If the specification states a component or feature "may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic. [0029] As used herein, the term "substantially free" means, when used with reference to the substantial absence of a material in an adhesive system or curable composition, that such a material is present, if at all, as an incidental impurity or by-product. In other words, the material does not affect the properties of the adhesive system or curable composition.

[0030] The present disclosure provides novel multipart structural adhesive systems and articles or substrates adhered to one another with such systems. According to one embodiment, the multipart structural adhesive system is a two-part structural adhesive system that is substantially free of peroxide, employing a part (A) containing a methacrylic component and a chlorosulfonated polymer, and a part (B) containing an aldehyde-amine condensate and a metal quinolate. It has been surprisingly discovered that the multipart structural adhesive systems of the present disclosure exhibit cure properties similar to those observed in conventional two-part adhesive systems, yet are peroxide-free thus eliminating any environmental concerns. In addition, it has been unexpectedly discovered that the multipart structural adhesive systems of the present disclosure exhibit both improved storage stability, and upon curing, improved lap shear strength as compared to peroxide-containing adhesive systems.

[0031] In an embodiment, part (A) of the two-part structural adhesive system includes a methacrylic component. The methacrylic component may be any suitable material which contains at least one group having the general structural formula:

H₂C=CGC0₂R where G is hydrogen, halogen, or a C₁-C4 alkyl and R is a Ci-C₂o alkyl, C₃-C₁₀ cycloalkyl, C₂-C₂₄ alkenyl, C7-C₃₀ alkylaryl or C₆-C₂₀ aryl group, any of which may be optionally substituted by oxygen, halogen, carbonyl, hydroxyl, epoxy, ester, carboxylic acid, urea, urethane, carbonate, amine, amide, sulfur, or sulfone.

[0032] Preferably, the methacrylic component contains a methacryloxy group. The term "methacryloxy" or "methacrylate" refers to both acrylate and methacrylate, in which G is hydrogen or methyl, respectively. [0033] The methacrylic component may be present in the form of a polymer, a monomer, or a combination thereof. If present in the form of a polymer, the methacrylic component may be a polymer chain to which is attached at least one of the above-identified groups. The groups may be located at a pendant or a terminal position of the backbone, or a combination thereof. Additionally, at least two such groups may be present, and may be located at terminal positions. The methacrylic polymer chain may be polyvinyl, poly ether, polyester, polyurethane, polyamide, epoxy, vinyl, ester, phenolic, amino, oil- based, and the like, as is well known to those skilled in the art, or random or block combinations thereof.

[0034] In one embodiment, the polymer chain of the methacrylic may be formed by polymerization of vinyl monomers. Examples include: methyl methacrylate, methacrylic acid, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-pentyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, n-heptyl methacrylate, n-octyl methacrylate, 2- ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, dodecyl methacrylate, phenyl methacrylate, tolyl methacrylate, benzyl methacrylate, 2-methoxyethyl methacrylate, 3-methoxybutyl methacrylate, 2-hydroxy ethyl methacrylate, 2- hydroxypropyl methacrylate, stearyl methacrylate, glycidyl methacrylate, 2-aminoethyl methacrylate, Y-(methacryloyloxypropyl)trimethoxysilane, methacrylic acid-ethylene adduct, trifluoromethylmethyl methacrylate, 2-trifluoromethylethyl methacrylate, 2- perfluoroethylethyl methacrylate, 2-perfluoroethyl-2-perfluorobutylethyl methacrylate, 2- perfluoroethyl methacrylate, perfluoromethyl methacrylate, diperfluoromethylmethyl methacrylate, 2-perfluoro-2-perfluoroethylmethyl methacrylate, 2-perfluorohexylethyl methacrylate, 2-perfluorodecylethyl methacrylate, 2-perfluorohexadecylethyl methacrylate, ethoxylated trimethylolpropane triacrylate, trimethyol propane trimethacrylate, dipentaerythritol monohydroxypentacrylate, pentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, 1,6-hexanedioldiacrylate, neopentyl glycoldiacrylate, pentaerythritol tetraacrylate, 1,2-butylene glycoldiacrylate, trimethylolpropane ethoxylate trimethacrylate, glyceryl propoxylated trimethacrylate, trimethylolpropane trimethacrylate, dipentaerythritol monohydroxy pentamethacrylate, tri(propylene glycol) dimethacrylate, neopentylglycol propoxylate dimethacrylate, 1,4- butanediol dimethacrylate, polyethyleneglycol dimethacrylate, triethyleneglycol dimethacrylate, butylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate and mixtures thereof.

[0035] The amount of the methacrylic component present in part (A) may range from about 20% by weight to about 90%> by weight, based on the total weight of part (A). Preferably, part (A) contains from about 50% by weight to about 70% by weight of the methacrylate component, based on the total weight of part (A).

[0036] In another embodiment, Part (A) further contains a chlorosulfonated polymer. The chlorosulfonated polymer includes those selected from among chlorosulfonated polyolefms, for example, chlorosulfonated polymers of ethylene, propylene, isobutylene and the like. The chlorosulfonated polymer may be obtained according to techniques known in the art, such as by the chlorination and/or chlorosulfonation of a polyolefin. Chlorosulfonated polyethylene is the preferred chlorosulfonated polymer, although chlorosulfonated copolymers of ethylene with small amounts of propylene or other olefins may be used as well.

[0037] The amount of the chlorosulfonated polymer present in part (A) may range from about 10%) by weight to about 45% by weight, and preferably ranges from about 25% to about 40%) by weight, based on the total weight of part (A).

[0038] If desired, part (A) may contain one or more organic acids to enhance adhesion. In one embodiment, the organic acid is a carboxylic acid. Examples of suitable carboxylic acids include, but are not limited to, methacrylic acid, acrylic acid, maleic acid, crotonic acid, furmaric acid, malonic acid, acetylene dicarboxylic acid, dibromo maleic citranoic acid, mesaconic acid, and oxalic acid

[0039] The amount of the organic acid in part (A), when present, may range from about 0.01%) by weight to about 15% by weight, preferably from about 1% by weight to about 10%) by weight, based on the total weight of part (A).

[0040] Part (A) may also optionally contain a compound having at least one sulfonyl halide group having the structure I

-c—

I

so₂

I

x

where X is selected from chlorine, bromine and iodine.

[0041] The sulfonyl halide-containing compounds may be mono- or polyfunctional. In one embodiment, the sulfonyl halide containing compound is an aliphatic sulfonyl halide having from 1 to 15 carbon atoms. In another embodiment, the sulfonyl halide- containing compound is an aromatic sulfonyl halide having from 1 to 3 aromatic nuclei and containing from 6 to 24 carbon atoms.

[0042] Representative examples of the sulfonyl halide-containing compound include: methane sulfonyl chloride, biphenyl disulfonyl chloride, trichlorobenzene sulfonyl chloride, benzene sulfonyl chloride, p-toluene sulfonyl chloride, hexadecane sulfonyl chloride, and diphenyl ether-4,4'-sulfonly chloride.

[0043] If present, the amount of the sulfonyl halide-containing compound in part (A) may range from about 0.1% to about 5% by weight, preferably from about 0.2% by weight to about 1% by weight, based on the total weight of part (A).

[0044] Part (A) may also include a free radical stabilizer such as a quinonone, hydroquinone, hydroxylamine, nitroxyl compound, phenol, amine, acrylamine, or phenothiazine.

[0045] If employed, the free radical stabilizer may be present in an amount ranging from about 0.01%) by weight to about 5% by weight, preferably from about 0.2%> by weight to about 0.5%) by weight, based on the total weight of part (A).

[0046] Other known additives which may optionally be added to part (A) include: pigments; wax; thixotropic agents; fillers; and chelating agents. [0047] As mentioned above, part (B) of the two-part structural adhesive system contains an aldehyde-amine condensate. The aldehyde-amine condensate includes conventional aldehyde-amine condensates of the type described, for example, in U.S. Pat. No. 3,591,438, columns 6-7, which is herein incorporated by reference. These condensates may be prepared by reacting from about 1 to 3.5 moles of aldehyde with 1 mole of amine at a temperature of from 40° C to 70° C. Examples of aldehydes include, but are not limited to, acetaldehyde, propionaldehyde, butryaldehyde, crotonaldehyde, acrolein, hydrocinnamaldehyde and 2-phenylpropionaldehyde. Examples of amines, include, but are not limited to, secondary aliphatic amines or aromatic primary amines containing from 1 to 18 carbon atoms such as ethyleneamine, butylamine, pentylamine, cyclopentylamine, hexylamine, cyclohexylamine, dodecylamine, aniline, tolylamine and xylylamine. A preferred aldehyde-amine condensate is the condensate of butryaldehyde and aniline, commercially available as VANAX® 808 HP condensate (R.T. Vanderbilt Company Inc.).

[0048] The amount of the aldehyde-amine condensate in part (B) may range from about 0.5% by weight to about 25% by weight, preferably from about 5% by weight to about 15%) by weight, based on the total weight of part (B).

[0049] The metal quinolate used in combination with the aldehyde-amine condensate in part (B) is a compound having the general formula

MY_n where M is a metal in a +2, +3 or +4 oxidation state, n is 1, 2 or 3, and

Y is the same or different at each occurrence and is selected from the group consisting of 8-hyroxyquinolate and substituted 8-hydroxyquinolate having the formula

where R³, R⁴ and R⁵ are, independently, a substituent selected from hydrogen, a Ci-C₂o alkyl, an aryl having 6-20 carbon atoms, an alkylaryl having 7-30 carbon atoms, an alkoxy having 1-20 carbon atoms, an aryloxy having 6-20 carbon atoms, a heteroalkyl having 1-20 carbon atoms, a heteroaryl having 4-20 carbon atoms, a heteroalkylaryl having 4-20 carbon atoms, a heteroalkoxy having 1-20 carbon atoms, a heteroaryloxy having 4-20 carbon atoms, cyano, dialkylamino, diarylamine, and halogen.

[0050] In one embodiment, M is a metal selected from the group consisting of aluminum, tin, beryllium, calcium, magnesium, lead, manganese, copper, nickel, iron, cadmium, silver, thallium, zinc, gallium, zirconium and indium. The "n" can be 1 , 2 or 3, depending on the oxidation state of M, and is selected so that the overall complex is electrically neutral. In one preferred embodiment, M is copper and n is 2.

[0051] In another embodiment, the metal quinolate may be dissolved in an organic solvent. Suitable solvents are those that will sufficiently dissolve, disperse or emulsify the metal quinolate and can be readily determined by one skilled in the art. Examples include Ci-C₂o alcohols, ethers, such as glycol ethers, acid esters, C -Cn alkanes, aromatics, chlorinated hydrocarbons and any mixture thereof.

[0052] The amount of the metal quinolate in part (B) may range from about 0.00001% by weight to about 40%> by weight, preferably from about 0.0001% by weight to about 30%> by weight, based on the total weight of part (B).

[0053] According to some embodiments, part (B) may optionally contain a methacrylic component. The specific methacrylic components used in part (B) are the same as those used in part (A) and are discussed above. When present in part (B), the methacrylic component may be used in amounts ranging from about 20% by weight to about 85% by weight, preferably from about 60% by weight to about 80%> by weight, based on the total weight of part (B).

[0054] In another embodiment, part (B) may optionally contain an impact modifier. As used herein, the term impact modifier can be one impact modifier or two or more impact modifiers. Various impact modifiers may be employed in the practice of the present disclosure and often include one or more elastomers.

[0055] In one embodiment, the impact modifier includes at least one core/shell impact modifier and preferably the impact modifier includes a substantial portion of core/shell impact modifier. In one embodiment, the impact modifier is comprised of at least 60%, more typically at least 80% and even more typically at least 97% core/shell impact modifier. As used herein, the term core/shell impact modifier denotes an impact modifier wherein a substantial portion (e.g., greater than 30%>, 50%>, 70%> or more by weight) thereof is comprised of a first polymeric material (i.e., the first or core material) that is substantially encapsulated by a second polymeric material (i.e., the second or shell material). The first and second polymeric materials, as used herein, can be comprised of one, two, or three or more polymers that are combined and/or reacted together (e.g., sequentially polymerized) or may be part of separate or same core/shell systems.

[0056] The first and second polymeric materials of the core/shell impact modifier can include elastomers, polymers, thermoplastics, copolymers, other components, and combinations thereof. In some embodiments, the first polymeric material, the second polymeric material or both of the core/shell impact modifier include or are substantially composed of (e.g., at least 70%>, 80%>, 90%> or more by weight) one or more thermoplastics. Exemplary thermoplastics include, without limitation, styrenics, acrylonitriles, acrylates, acetates, polyamides, polyethylenes and the like.

[0057] The core/shell impact modifiers may be formed by emulsion polymerization followed by coagulation or spray drying. It is also preferred for the core/shell impact modifier to be formed of or at least include a core-shell graft co-polymer. The first or core polymeric material of the graft copolymer preferably has a glass transition temperature substantially below (i.e., at least 10° C, 20° C, 40° C or more) the glass transition temperature of the second or shell polymeric material. Moreover, it may be desirable for the glass transition temperature of the first or core polymeric material to be below 23° C while the glass temperature of the second or shell polymeric material to be above 23° C, although not required

[0058] Examples of core-shell graft copolymers are those where hard containing compounds, such as styrene, acrylonitrile or methyl methacrylate, are grafted onto core made from polymers of soft or elastomeric containing compounds such as butadiene or butyl acrylate. U.S. Pat. No. 3,985,703, which is herein incorporated by reference, describes useful core-shell polymers, the cores of which are made from butyl acrylate but can be based on ethyl isobutyl, 2-ethylhexel or other alkyl acrylates or mixtures thereof. The core polymer may also include other copolymerizable containing compounds, such as styrene, vinyl acetate, methyl methacrylate, butadiene, isoprene, and the like. The core polymer material may also include a cross linking monomer having two or more nonconjugated double bonds of approximately equal reactivity such as ethylene glycol diacrylate, butylene glycol dimethacrylate, and the like. The core polymer material may also include a graft linking monomer having two or more nonconjugated double bonds of unequal reactivity such as, for example, diallyl maleate and allyl methacrylate.

[0059] The shell portion may be polymerized from methyl methacrylate and optionally other alkyl methacrylates, such as ethyl, butyl, or mixtures thereof. Up to 40% by weight or more of the shell monomers may be styrene, vinyl acetate, vinyl chloride, and the like. Additional core-shell graft copolymers useful 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 entireties of which are herein incorporated by reference. Examples of core-shell graft copolymers include, but are not limited to, "MBS" (methacrylate -butadiene-styrene) polymers, which are made by polymerizing methyl methacrylate in the presence of polybutadiene or a polybutadiene copolymer rubber. The MBS graft copolymer resin generally has a styrene butadiene rubber core and a shell of acrylic polymer or copolymer. Examples of other useful 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 elastomeric backbones of ethylene-propylene diene monomer), MAS (methacrylic-acrylic rubber styrene), and the like and mixtures thereof.

[0060] Commercially available impact modifiers include those sold under the tradename PARALOID (The Dow Chemical Co.). Particularly preferred grades of PARALOID impact modifiers are polymethyl methacrylate shell and MBS core modifier and butyl- acrylate shell and acrylate core modifier sold under the designation EXL 2691 A and KM 330.

[0061] The amount of the core shell polymer in part (B), when present, may range from about 5% by weight to about 35% by weight, preferably from about 10% by weight to about 25% by weight, based on the total weight of part (B).

[0062] Other known additives which may be included in part (B) include: plasticizers such as dioctyl phthalate, dibutyl phthalate, diisobutyl phthalate, diisodecyl phthalate; phthalate-free plasticizers, such as ricinoleate-based plasticizers, 2,2,4-trimethyl-l ,3- pentanediol diisobutyrate, dioctyl succinate, and diisodecyl adipate; fillers; pigments; and thixotropic agents.

[0063] According to one embodiment, the structural adhesive systems of the present disclosure may be prepared by first combining the respective ingredients in part (A) and part (B). Part (A) and part (B) can then be contacted or mixed using any conventional device just prior to use to form a curable composition.

[0064] In another embodiment, the present disclosure provides a method of bonding at least two substrates together which includes:

(a) providing a part (A) containing a methacrylate component and a chlorosulfonated polymer; (b) providing a part (B) containing an aldehyde-amine condensate and metal quinolate;

(c) contacting parts (A) and (B) to form a curable composition;

(d) applying the curable composition to at least one surface of one or more of the substrates; and

(e) matingly engaging the surfaces of the substrates which are to be bonded together permitting the composition to cure to form a bond there between.

[0065] It is generally contemplated that the two parts of the structural adhesive system will be mixed in about a 1 :1 ratio by volume, but the ratio will depend on the components contained in each part and therefore may vary. Thus, in some embodiments, part (A) and part (B) may be mixed in about a 5: 1 to 1 :5 ratio by volume, while in other embodiments part (A) and part (B) may be mixed in about a 10: 1 to 1 : 10 ratio by volume.

[0066] In one embodiment, parts (A) and (B), after mixing, are applied to the surface of at least one substrate by brushing, rolling, spraying, dotting, or kniving to at least one substrate. The surface may be untreated, oily, etc. The substrates to be adhered may be clamped for firmness during cure in those installations where relative movement of the substrates might be expected. For example, to adhere two substrate surfaces, an adherent quantity of the curable composition is applied to at least one surface, preferably to both surfaces, and the surfaces are contacted with the curable composition therebetween. The smoothness of the surfaces and their clearance will determine the required film thickness for optimum bonding. The surfaces and the interposed curable composition are then maintained in engagement until the curable composition has cured sufficiently to bond the surfaces. Examples of substrates which the curable composition may be applied to include, but are not limited to, steel, galvanized steel, aluminum, copper, brass, wood, glass, paper, composites, ceramics, plastics and polymeric materials such as polyester, polyamide, polyurethane, polyvinyl chloride, polycarbonates, ABS plastics, and plexiglass. [0067] The two-part adhesive systems of the present disclosure provide very strong bond strengths which may range from about 3000-4500 psi in shear. In addition, the setting time for the curable compositions may vary somewhat, but may range between about 5- 30 minutes but in some embodiments may range up to several hours in the case of large jobs where applying the curable composition to the substrate can take substantial time. In one embodiment, the cure time for the two-part adhesive system may range from about 10 minutes to about 120 minutes.

[0068] Examples

[0069] Example 1. The following components were combined to form parts (A) and (B) of a two-part structural adhesive system according to the present disclosure:

Ex 1.

Component (grams)

Part A

Methyl methacrylate 61.25

CN- 1500 (chlorosulfonated polyethylene) 30.0

Methacrylic acid 8.0

Methane sulfonyl chloride 0.5

2,6,di-t-butyl,4-methyphenol (BHT) 0.25

Part B

Vanax® 808HP condensate 7.5

Inter #2 (copper 8 quinolate dissolved in glycol 2.0

ether)

Methyl methacrylate 76.25

Impact modifier 14.0

2,6,di-t-butyl,4-methyphenol (BHT) 0.25

Parts (A) and (B) exhibited the following physical properties: Physical Property

Part (A) viscosity by cone #6 17,300-19,500 cps

10 rpm

Part (A) density @ 23° C 1.003 g/cm³

Part (B) viscosity by cone # 6 9,000-11,300 cps

10 rpm

Part (B) density @ 23° C 0.959 g/cm³

Parts (A) and (B) were then mixed at a 1 : 1 ratio by volume to form a curable composition which exhibited the following properties in comparison to a commercially available two- part structural adhesive which contained peroxide:

Physical Property Ex. 1 Comparative Ex.

Setting time 17-25 minutes 15-20 minutes

Initial lap shear strength Ave. = 3441 psi Ave = 3107 psi

Range = 3309-3675 psi Range = 2952-3273 psi

Lap shear strength after 5 weeks Ave = 3427 psi Ave = 3065 psi storage in 50 ml cartridges

Range = 3015-3653 psi Range = 2923-3301 psi

[0070] Examples 2-7. The following components were combined to form parts (A) and (B) of a two-part structural adhesive system according to the present disclosure: Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7

Component (grams) (grams) (grams) (grams) (grams) (grams)

Part A

Methyl methacrylate 61.1 61.8 61.8 61.4 61.4 61.4

CN-1500 30 30 30 30 30 30

(chlorosulfonated

polyethylene)

Methacrylic acid 8 8 8 8 8 8

Methane sulfonyl 0.25 0.25 0.25 0.25 chloride

BHT 0.25 0.25 0.25 0.25 0.25 0.25

Monomethyl ether 0.15 0.15 0.15 0.15 hydroquinone

Aerasol 200 0.5

Part B

Vanax® 808HP 7.5 7.5 7.5 7.5 7.5 7.5 condensate

Inter #2 (copper 8 1.0 1.0 1.0 1.0 1.0 1.0 quinolate dissolved in

glycol ether)

Methyl methacrylate 75.5 75.5 75.5 75.5 75.5 75.5

Impact modifier 16 16 16 14 14 14

BHT 0.25 0.25 0.25

Paraffin wax 0.3

Monomethyl ether 0.15 0.15 0.15 hydroquinone

Phenyl napthamine 0.10

Parts (A) and (B) were then mixed at a 1 : 1 ratio by volume to form a curable composition which exhibited the following properties: Phys. Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Property

Setting time 8-13 10.5-16.5 9.5-13.5 16-22 10-18 13-17

(minutes)

Initial lap Ave=3774 Ave=3038 Ave=3493 Ave=3183 Ave=3681 Ave=3886 shear strength

(3682-3978) (2931-3117) (3402-3717) (2932-3340) (3657-3697) (3476-4130)

(psi)

(On Al, 24

hrs, rt cured)

[0071] The above-disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments, which fall within the true scope of the present invention. Thus, to the maximum extent allowed by law, the scope of the present invention is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.

Claims

WHAT IS CLAIMED IS:

1. A two-part structural adhesive system comprising a part (A) containing a methacrylic component and a chlorosulfonated polymer, and a part (B) containing an aldehyde-amine condensate and a metal quinolate and wherein the adhesive system is substantially free of peroxide.

2. The two-part structural adhesive system of claim 1, wherein the methacrylate component comprises methyl methacrylate.

3. The two-part structural adhesive system of claim 1, wherein the chlorosulfonated polymer comprises chlorosulfonated polyethylene.

4. The two-part structural adhesive system of claim 1, wherein part (A) further comprises a compound having at least one sulfonyl halide group having the structure

where X is selected from chlorine, bromine and iodine.

5. The two-part structural adhesive system of claim 1, wherein part (A) further comprises methacrylic acid.

6. The two-part structural adhesive system of claim 1, wherein the metal quinolate is a compound having the general formula

MY_n where M is a metal in a +2, +3 or +4 oxidation state, n is 1, 2 or 3, and

where R³, R⁴ and R⁵ are, independently, a substituent selected from hydrogen, a C1-C20 alkyl, an aryl having 6-20 carbon atoms, an alkylaryl having 7-30 carbon atoms, an alkoxy having 1-20 carbon atoms, an aryloxy having 6-20 carbon atoms, a heteroalkyl having 1-20 carbon atoms, a heteroaryl having 4-20 carbon atoms, a heteroalkylaryl having 4-20 carbon atoms, a heteroalkoxy having 1-20 carbon atoms, a heteroaryloxy having 4-20 carbon atoms, cyano, dialkylamino, diarylamine, and halogen .

7. The two-part structural adhesive system of claim 6, wherein M is copper and n is 2.

8. The two-part structural adhesive system of claim 6, wherein part (B) further comprises a methacrylate component.

9. The two-part structural adhesive composition of claim 8, wherein part (B) further comprises an impact modifier.

10. A method of preparing a substantially peroxide free two-part structural adhesive comprising:

(a) providing a part (A) comprising a methacrylate component and a chlorosulfonated polymer; and

(b) providing a part (B) comprising an aldehyde-amine condensate and a metal quinolate.

11. A method of method of bonding at least two substrates together which includes:

(a) providing a part (A) containing a methacrylate component and a chlorosulfonated polymer;

(b) providing a part (B) containing an aldehyde-amine condensate and metal quinolate;

(c) contacting parts (A) and (B) to form a curable composition that is substantially free of peroxide;

(e) matingly engaging the surfaces of the substrates together permitting the composition to cure to form a bond therebetween.

12. The method of claim 11 wherein parts (A) and (B) are mixed at a 10: 1 to 1 : 10 ratio by volume.

13. The method of claim 11, wherein at least one of the substrates is steel, galvanized steel, aluminum, copper, brass, wood, glass, paper, composite, ceramic, plastic or polymeric material.

14. The method of claim 11, wherein the surface of at least one of the substrates is untreated.

15. The method of claim 11, wherein the surface of at least one of the substrates is oily.

16. A two part adhesive system produced according to the method of claim 10.

17. A two-part adhesive system produced according to claim 10 having a cure time of about 10 minutes to about 120 minutes.