Cyclic imides and adhesive compositions comprising them

Abstract

Compounds represented by Formula (I) are described. # imgabs0 # in the formula: A represents a saturated, unsaturated or aromatic ring; each R is independently hydrogen or methyl; each R1 is independently an alkylene group optionally interrupted by one or more-O-groups; each R3 is independently an alkylene group, an arylene group, or an alkylene group optionally interrupted or terminated by an arylene group, optionally interrupted by one or more-O-groups or one to three-NR2-groups, and optionally terminated by-N (R2) 2; and each R2 is independently hydrogen, alkyl, aryl, arylalkylene, or formula (II). # imgabs 1 # also describes an adhesive composition comprising said compound. The use of the composition as a tackifier and a method comprising applying the composition to a surface of a substrate are also described.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 432,939, filed Dec. 15, 2022, the disclosure of which is incorporated herein by reference in its entirety. BACKGROUND OF THE INVENTION

[0003] Known structural adhesives can be used to bond one substrate to another. Structural adhesives are an attractive alternative to mechanical joining methods such as riveting or spot welding because structural adhesives distribute load stresses over a larger area rather than concentrating such stresses at a few points.

[0004] International Patent Application Publication No. WO 2022 / 034521 (Ostlund et al.) discloses (meth)acrylate structural adhesive compositions comprising cyclic imide-containing monomers. The compositions cure at room temperature via a free radical initiator system and the resulting structural adhesives are reported to bond well to glass. SUMMARY OF THE INVENTION

[0005] The present disclosure provides a compound that can be used, for example, to improve adhesion between substrates when used in, for example, a structural adhesive composition.

[0006] In one aspect, the present disclosure provides a compound represented by the following formula:

[0007]

[0008] In this formula, A represents a saturated, unsaturated, or aromatic ring; each R is independently hydrogen or methyl; each R 1 is independently an alkylene group optionally interrupted by one or more -O- groups; each R 3 is independently an alkylene group, an arylene group, or an alkylene group optionally interrupted or terminated by an arylene group, optionally interrupted by one or more -O- groups or one to three -NR 2 - groups and optionally terminated by

[0009] -N(R 2 )2; and each R 2 is independently hydrogen, an alkyl group, an aryl group, an arylalkylene group, or

[0010] In another aspect, the present disclosure provides an adhesive composition comprising the compound.

[0011] In another aspect, the present disclosure provides the use of the compound as a tackifier.

[0012] In another aspect, the present disclosure provides a method for bonding a first substrate to a second substrate. The method includes applying an adhesive composition to at least a portion of a surface of the first substrate, bringing at least a portion of the adhesive composition into contact with at least a portion of a surface of the second substrate, and causing the adhesive composition to cure at least partially and form a structural adhesive.

[0013] In another aspect, the present disclosure provides an adhesive article prepared according to the method. The adhesive article includes a structural adhesive bonded to the first substrate and the second substrate.

[0014] In this application:

[0015] Terms such as "a", "an", "the", and "said" are not intended to refer to only a single entity, but rather include a general category of specific examples that can be used for illustration. The terms "a", "an", "the", and "said" can be used interchangeably with the term "at least one".

[0016] The phrase "comprising at least one of...", followed by a list, means including any one item in the list and any combination of two or more items in the list. The phrase "at least one of...", followed by a list, means any one item in the list or any combination of two or more items in the list.

[0017] The terms "cure" and "curable" mean joining together with a polymer chain by covalent chemical bonds, typically by crosslinking molecules or groups, to form a network polymer. Thus, in the present disclosure, the terms "cured" and "crosslinked" can be used interchangeably. A cured or crosslinked polymer is typically characterized by insolubility, but can be swellable in the presence of a suitable solvent.

[0018] The term "polymer" refers to a molecule having a structure that includes multiple repeating units that are actually or conceptually derived from one or more monomers. The term "monomer" refers to a low relative molecular mass molecule that can combine with other molecules to form a polymer. The term "polymer" includes homopolymers and copolymers, as well as blends of homopolymers and copolymers that may form in miscible blends. The term "polymer" includes random polymers, block polymers, graft polymers, and star polymers. The term "polymer" includes oligomers.

[0019] The term "alkyl group" and the prefix "alk-" encompass straight-chain and branched groups as well as cyclic groups. In some embodiments, unless otherwise specified, an alkyl group has up to 30 carbons (in some embodiments, up to 20, 15, 12, 10, 8, 7, 6, or 5 carbons). The cyclic group can be monocyclic or polycyclic and, in some embodiments, has 3 to 10 ring carbon atoms. The terminal "alkenyl" group has at least 3 carbon atoms.

[0020] "Alkylene" is the polyvalent (e.g., divalent or trivalent) form of an "alkyl" group as defined above.

[0021] "Arylalkylene" refers to the "alkylene" portion to which an aryl group is attached. "Alkylarylene" refers to the "arylene" portion to which an alkyl group is attached.

[0022] As used herein, the terms "aryl" and "arylene" include carbocyclic aromatic rings or ring systems, e.g., having 1, 2, or 3 rings and optionally containing at least one heteroatom (e.g., O, S, or N) in the ring, which ring is optionally substituted with up to five substituents including one or more alkyl groups having up to 4 carbon atoms (e.g., methyl or ethyl), alkoxy having up to 4 carbon atoms, halogen (i.e., fluorine, chlorine, bromine, or iodine), hydroxy, cyano, or nitro groups. Examples of aryl groups include phenyl, naphthyl, biphenyl, fluorenyl, as well as furyl, thienyl, pyridyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl, triazolyl, pyrrolyl, tetrazolyl, imidazolyl, pyrazolyl, oxazolyl, and thiazolyl.

[0023] For example, with respect to an alkylene group, the phrase "interrupted by arylene" means a portion having alkylene on both sides of the arylene group. For example, -CH2CH2-C6H5-CH2-CH2- is an alkylene group interrupted by a phenyl group. Similarly, -CH2CH2-NH-CH2-CH2- is an alkylene group interrupted by an -NH- group.

[0024] Unless otherwise indicated, all numerical ranges include their end values as well as non-integer values between the end values (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Detailed Description

[0025] The compounds of the present disclosure are represented by

[0026]

[0027] Formula I.

[0028] In formula I, each A independently represents a saturated, unsaturated or aromatic ring. In some embodiments, each A independently represents a 5- to 8-membered ring. In some embodiments, each A independently represents a 5- to 8-membered (in some embodiments, 5- to 7-membered) saturated ring. In some embodiments, each A independently represents a 6-membered saturated ring. In formula I, each R is independently hydrogen or methyl. In some embodiments, each R is hydrogen. In some embodiments, each R is methyl. In formula I, each R 1 is independently an alkylene group optionally interrupted by one or more –O- groups. In some embodiments, each R 1 is independently an alkylene group having 1 to 18 carbon atoms. In some embodiments, each R 1 is independently an alkylene group having 2 to 16 carbon atoms, 2 to 12 carbon atoms, 2 to 8 carbon atoms, 2 to 6 carbon atoms, 2 to 4 carbon atoms or 2 carbon atoms (in some embodiments, a linear alkylene group).

[0029] In formula I, R 3 is independently an alkylene group, an arylene group or an alkylene group optionally interrupted or terminated by an arylene group, optionally interrupted by one or more -O- groups or one to three -NR 2 - groups and optionally terminated by -N(R 2 )2. When R 3 is terminated by -N(R 2 )2, R 3 is a branched group (e.g., R 3 is trivalent). In some embodiments, R 3 is a polyvalent alkylene group optionally interrupted by one or more -O- groups or at most three -NR 2 - groups. In some embodiments, R 3 is a polyvalent alkylene group optionally interrupted by one or more -O- groups. In some of these embodiments, the polyvalent alkylene group contains a cyclohexane ring. In some embodiments, R 3 is

[0030] -CH-(CH3)CH2-O-CH2-C6H 10 -CH2-O-CH2-CH(CH3)-. In some embodiments, R 3 comprises polyethylene oxide, polypropylene oxide or a combination thereof, which in some embodiments has a number average molecular weight of at most 4000, 3000, 2000, 1000 or 500 g / mol as determined by proton nuclear magnetic resonance spectroscopy. In some embodiments, R 3 is an alkylene group interrupted by an arylene group, which in some embodiments is -CH2-C6H5-CH2-.

[0031] In formula I, each R 2 independently, each R 2 is independently hydrogen, alkyl, aryl, arylalkylene or

[0032] wherein A, R and R 1 are defined as in any of the above embodiments. In some embodiments, all R 2 groups are hydrogen and the compound contains two cyclic imide groups. In some embodiments, each R 2 is In some of these embodiments, R 3 does not include -NR 2 - groups and the compound contains four cyclic imide groups. In some embodiments, each R 2 is independently hydrogen or

[0033] In some embodiments, the compound contains three cyclic imide groups. In some of these embodiments, R 3 is capped with -N(R 2 )2.

[0034] The compounds of the present disclosure can be prepared, for example, by reacting a polyfunctional amine with an α-β unsaturated compound comprising a cyclic amide under conventional Michael addition reaction conditions. The available polyfunctional amines have at least two amino groups and can be aromatic, aliphatic (e.g., linear or cycloaliphatic) or a combination thereof. The amino groups in the polyfunctional amine are each independently a primary or secondary amino group. In some embodiments, the polyfunctional amine contains at least two primary amino groups.

[0035] Useful polyfunctional amines can be aliphatic amines containing at least two amino groups. In some embodiments, the polyfunctional amine is a linear or branched alkylene polyamine. Available alkylene polyamines include ethyleneamines (e.g., ethylenediamine, diethylenetriamine, triethylenetetramine, etc.), higher alkylene diamines (e.g., hexamethylenediamine, methylpentamethylenediamine and trimethylhexamethylenediamine) and polyetheramines (e.g., polyoxyalkylene diamines such as polyoxypropylene diamines of various molecular weights and 4,7,10-trioxa-1,13-tridecanediamine).

[0036] The polyfunctional amine can be an aromatic polyamine in which the amino groups are directly bonded to the aromatic ring, or can be an arylalkylene polyamine in which the amino groups are bonded to an alkylene group which is in turn bonded to an aromatic ring. The polyfunctional amine can also contain two or more aromatic rings and at least two amino groups. In any of these embodiments, the aromatic ring can be unsubstituted or substituted with one or more halogens (e.g., fluorine, chlorine, bromine, iodine), an alkyl group having 1 to 4 carbon atoms (e.g., methyl or ethyl), or a hydroxyalkyl group having 1 to 4 carbon atoms (e.g., hydroxymethyl). For amines containing two or more aromatic rings, these rings can be directly linked or linked, for example, by a branched or straight-chain alkylene group having 1 to 4 carbon atoms (optionally substituted with one or more halogens (e.g., fluorine, chlorine, bromine, iodine), oxygen, sulfur, or sulfone groups). Examples of polyfunctional amines containing at least two amino groups and at least one aromatic ring include phenylenediamines (e.g., m-phenylenediamine or p-phenylenediamine), diethyltoluenediamine (e.g., in any of its isomeric forms), diaminotoluene (e.g., 2,3-diaminotoluene and 3,4-diaminotoluene, and methylm-phenylenediamine), 1,2-diamino-3,5-dimethylbenzene, 4,5-dimethyl-1,2-phenylenediamine, 2,4,6-trimethylm-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, aminobenzylamines (e.g., 2-aminobenzylamine and 4-aminobenzylamine), ethylenediphenylamine, 2,2'-biphenyldiamine, diaminodiphenylmethane, diaminodiphenylsulfone, halogen-substituted phenylenediamines (e.g., 4-chloro-1,3-diaminobenzene, 4-chloro-1,2-diaminobenzene, and 4-bromo-1,2-diaminobenzene), xylylenediamines (e.g., o-xylylenediamine or m-xylylenediamine), and 4-(2-aminoethyl)aniline.

[0037] The polyfunctional amine may include at least two amino groups and at least one alicyclic ring. The amino groups may be directly bonded to the alicyclic ring, or the amino groups may be bonded to a straight-chain or branched alkylene group, which in turn is bonded to the alicyclic ring. The amine curing agent may also contain two or more alicyclic rings and at least two amino groups. In any of these embodiments, the alicyclic ring may be unsubstituted or substituted with one or more halogens (such as fluorine, chlorine, bromine, iodine), a straight-chain or branched alkyl group having 1 to 4 carbon atoms (such as methyl or ethyl), or a hydroxyalkyl group having 1 to 4 carbon atoms (such as hydroxymethyl). In any of these embodiments, the alicyclic ring may be a carbocyclic ring, for example, not containing heteroatoms such as sulfur or nitrogen. For amines containing two or more alicyclic rings, these rings may be directly connected or connected, for example, by a branched or straight-chain alkylene group having 1 to 4 carbon atoms (optionally substituted with one or more halogens (such as fluorine, chlorine, bromine, iodine), oxygen, sulfur, or sulfone groups). Examples of suitable amine curing agents containing at least two amino groups and at least one alicyclic group are the complete or partial hydrogenation products of any of the above amine curing agents containing at least two amino groups and at least one aromatic ring. For example, suitable amine curing agents include diamino cyclohexane (such as 1,2-diamino cyclohexane or 1,4-diamino cyclohexane in cis or trans form) and 3-aminomethyl-3,5,5-trimethyl cyclohexylamine (also known as isophorone diamine).

[0038] Several polyfunctional amines containing at least two amino groups and at least one aromatic ring or alicyclic ring are available from Lonza, Basel, Switzerland and Amberlite Corporation, Baton Rouge, LA. Other amine curing agents available include polyetheramines (such as polypropylene glycol diamine), which are available, for example, under the trade name "JEFFAMINE" from Huntsman Chemical, The Woodlands, TX.

[0039] Any of these polyfunctional amines may react with, for example, a cyclic imide-containing acrylate or a cyclic imide-containing methacrylate. The cyclic imide-containing acrylate or cyclic imide-containing methacrylate contains a ring system that includes one or more rings (in some embodiments, two rings). The ring system may include one or more saturated rings, unsaturated rings, aromatic rings, or combinations thereof. In some embodiments, the cyclic imide-containing acrylate or cyclic imide-containing methacrylate is represented by the following formula: where A, R 1R is as described above in any of its embodiments. In some embodiments, the cyclic imide-containing acrylate or cyclic imide-containing methacrylate is

[0040] wherein R is hydrogen or methyl (i.e., 2-(hexahydrophthalimido)ethyl acrylate or 2-(hexahydrophthalimido)ethyl methacrylate). In some embodiments, the cyclic imide-containing acrylate or cyclic imide-containing methacrylate is 2-(hexahydrophthalimido)ethyl methacrylate. 2-(hexahydrophthalimido)ethyl methacrylate can be commercially obtained, for example, under the trade name "MIRAMER M1089" from Miwon North America (Exton, Pa.). 2-(hexahydrophthalimido)ethyl acrylate can be commercially obtained, for example, under the trade name "MIRAMER M1088" from Miwon North America).

[0041] The compounds of the present disclosure can be prepared by combining a polyfunctional amine with a cyclic imide-containing acrylate or a cyclic imide-containing methacrylate. The reaction can be carried out without a solvent or in a suitable solvent. Optionally, the reaction mixture can be heated at an elevated temperature, such as at least 40 °C, at least 50 °C, or at least 60 °C. The upper temperature can be determined by the boiling point of the solvent (if used).

[0042] The present disclosure provides an adhesive composition that comprises a compound described herein. In some embodiments, the adhesive composition is a structural adhesive composition. "Structural adhesive" means an adhesive that bonds by irreversible curing. Structural adhesives typically bond high-strength materials (e.g., wood, composites, or metals), and the strength, measured using the lap shear test described in the examples herein as the fracture stress (peak stress), is at least 689 kPa (100 psi), at least 1379 kPa (200 psi), at least 3445 kPa (500 psi), or at least 6890 kPa (1000 psi).

[0043] A structural adhesive composition can be packaged as a two - part product or a one - part product. For a two - part product, the two parts can be stored at room temperature. Once the user mixes the two parts, the reaction begins and the composition starts to form a structural adhesive. After at least partial curing, a cross - linked composition is generally obtained, and if fully cured, it can be suitable for use as a structural adhesive for bonding two adherends. In such a use, the composition is typically sandwiched between the adherends and at least partially cured; for example, for a time sufficient to achieve at least a desired level of bond strength. It is desirable for the adhesive composition to exhibit a suitable open time and cure rapidly. The "open time" of a two - part adhesive refers to the amount of time that the adhesive remains flowable and able to bond to a substrate after the two components are mixed.

[0044] For a one - part product that can be at least partially cured at room temperature, the user can avoid the complex mixing step, but the product is typically transported and stored in a freezer before application. One - part products cured by actinic radiation (e.g., one - part products that do not contain a second initiator for curing at room temperature or elevated temperature) can be transported and stored at room temperature before application, sometimes in the dark. Some one - part structural adhesive compositions require elevated temperatures for curing.

[0045] The compounds of the present disclosure can be used in a variety of structural adhesive compositions. These include thermally curable phenolic adhesives, thermally curable epoxy adhesives, thermally curable polyimide adhesives, two - part epoxy adhesives, one - part photo - curable adhesives (e.g., which can be acrylic adhesives or epoxy adhesives), two - part acrylic adhesives, one - part moisture - curable or thermally curable polyurethane adhesives, and two - part polyurethane adhesives. In some embodiments, the adhesive composition of the present disclosure is a two - part structural adhesive composition. In some embodiments, the adhesive composition is part of a two - part structural adhesive composition. In some embodiments, the adhesive composition is a polyurethane adhesive composition. In some embodiments, the adhesive composition is a two - part polyurethane adhesive composition.

[0046] The two - part polyurethane adhesive composition comprises a first part and a second part. The first part contains one or more polyisocyanate compounds, and the second part contains one or more polyols. When the two parts are mixed, the polyisocyanate and the polyol react to form a cured polyurethane adhesive. The polyurethane adhesive can be formulated to cure at room temperature or when exposed to certain conditions such as elevated temperature. When the adhesive cures, it can form a strong adhesive bond with many types of substrates. The polyurethane can include a backbone of any suitable structural configuration. The backbone can optionally include one or more other backbone bonds (e.g., amide, ester, carbonate, epoxy, ether, imide, imine, or urea bonds or combinations thereof). Additionally, the backbone of the polyurethane polymer can optionally include one or more oligomer or polymer segments (e.g., acrylic, polyamide, polyester, poly(carbonate), epoxy, polyether, polyimide, polyimine, or polyurea segments or combinations thereof). The polyurethane can be linear, substantially linear, or branched.

[0047] The polyisocyanate compound can be any compound containing on average more than one isocyanate moiety. The polyisocyanate compound can be in the form of an isocyanate - functional prepolymer, monomer, or oligomer having on average greater than 1 isocyanate group and in some embodiments 2 or more isocyanate groups. The isocyanate prepolymer can be any prepolymer prepared by reacting a polyisocyanate compound with one or more compounds having on average more than one isocyanate - reactive functional group (e.g., hydroxyl, amine, thiol, and carboxyl) under conditions such that the resulting prepolymer has on average more than one isocyanate group per molecule. The polyisocyanate compound is typically present in the structural adhesive composition in an amount sufficient to form a cured component when exposed to curing conditions.

[0048] Examples of suitable polyisocyanate compounds that can be used in the structural adhesive composition and can be used to prepare the isocyanate - functional prepolymer include any aliphatic, cycloaliphatic, aromatic / aliphatic, heterocyclic, and aromatic polyisocyanates and combinations thereof. In some embodiments, the polyisocyanate used has an average isocyanate functionality of about 2.0 or greater and an equivalent weight of about 80, 110, or 120 or greater and up to 300, 250, or 200 equivalents / mole. In some embodiments, the isocyanate functionality of the polyisocyanate compound is about 2.2 or greater, about 2.4 or greater, about 4.0 or less, about 3.5 or less, or about 3.0 or less.

[0049] Suitable aliphatic diisocyanates include isophorone diisocyanate (i.e., 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane); 5-isocyanato-1-(2-isocyanatoethyl-1-yl)-1,3,3-trimethylcyclohexane; 5-isocyanato-1-(3-isocyanatopropyl-1-yl)-1,3,3-trimethylcyclohexane; 5-isocyanato-(4-isocyanatobut-1-yl)-1,3,3-trimethylcyclohexane; 1-isocyanato-2-(3-isocyanatopropyl-1-yl)cyclohexane; 1-isocyanato-2-(3-isocyanatoethyl-1-yl)cyclohexane; 1-isocyanato-2-(4-isocyanatobut-1-yl)cyclohexane; 1,2-diisocyanatocyclobutane; 1,3-diisocyanatocyclobutane; 1,2-diisocyanatocyclopentane; 1,3-diisocyanatocyclopentane; 1,2-diisocyanatocyclohexane; 1,3-diisocyanatocyclohexane; 1,4-diisocyanatocyclohexane; dicyclohexylmethane 2,4'-diisocyanate; trimethylene diisocyanate; tetramethylene diisocyanate; pentamethylene diisocyanate; hexamethylene diisocyanate; ethylidene diisocyanate; trimethylhexane diisocyanate; heptamethylene diisocyanate; 2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentyl-cyclohexane; 1,2-, 1,4- and 1,3-bis(isocyanatomethyl)cyclohexane; 1,2-, 1,4- and 1,3-bis(2-isocyanatoethyl-1-yl)cyclohexane; 1,3-bis(3-isocyanatopropyl-1-yl)cyclohexane; 1,2-, 1,4- or 1,3-bis(4-isocyanatobut-1-yl)cyclohexane; liquid bis(4-isocyanatocyclohexyl)-methane; and their derivatives or mixtures. In some embodiments, the polyisocyanate compound is isophorone diisocyanate, tetramethylxylene diisocyanate, 1,6-hexamethylene diisocyanate and their oligomeric or polymeric derivatives, bis(4-isocyanato-cyclohexyl)methane or trimethylhexamethylene diisocyanate. In some embodiments, the polyisocyanate compound comprises at least one of isophorone diisocyanate (IPDI) or hexamethylene diisocyanate (HMDI).Suitable aromatic isocyanates include diphenylmethane diisocyanate, toluene diisocyanate, bis(isocyanatoethyl)benzene, α,α,α',α'-tetramethylxylene diisocyanate, 1,3-bis(1-isocyanato-1-methylethyl)benzene, bis(isocyanatobutyl)benzene, bis(isocyanatomethyl)naphthalene, bis(isocyanatomethyl)diphenyl ether, bis(isocyanatoethyl)phthalate, mesitylene triisocyanate, 2,5-bis(isocyanatomethyl)furan, phenylene diisocyanate, ethylphenylene diisocyanate, isopropylphenylene diisocyanate, dimethylphenylene diisocyanate, diethylphenylene diisocyanate, diisopropylphenylene diisocyanate, trimethylbenzene triisocyanate, benzene triisocyanate, naphthalene diisocyanate, methylnaphthalene diisocyanate, diphenyl diisocyanate, o-dimethyldiaminobiphenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, bis(3-methyl-4-isocyanatopropyl)methane, bis(isocyanatophenyl)ethylene, 3,3'-dimethoxy-diphenyl-4,4'-diisocyanate, triphenylmethane triisocyanate, polymeric 4,4'-diphenylmethane diisocyanate, naphthalene triisocyanate, diphenylmethane-2,4,4'-triisocyanate, 4-methyldiphenylmethane-3,5,2',4',6'-pentaisocyanate, diphenyl ether diisocyanate, bis(isocyanatophenyl ether)ethylene glycol, bis(isocyanatophenyl ether)-1,3-propanediol, benzophenone diisocyanate, combinations thereof and their polymeric derivatives.

[0050] Higher-functional polyisocyanate compounds include monomeric isocyanates and oligomeric isocyanurates or biurets and can be aliphatic or aromatic. Examples of commercially available isocyanate compounds include trimers of hexamethylene diisocyanate such as those available under the trade names DESMODUR N3300, DESMODUR N3400, DESMODUR N-100 from Bayer. Suitable oligomeric aromatic polyisocyanates include those available under the trademarks PAPI and VORANATE, such as polymeric isocyanates VORANTN M220, PAPI 27 and PAPI 20 from The Dow Chemical Company.

[0051] Suitable polyols for preparing polyurethanes include monomers, oligomers, polymers, and mixtures thereof, and include diols, triols, polyols having 4 or more hydroxyl groups, and mixtures thereof. Examples of polyols used as reactants or starting materials for oligomeric or polymeric polyols include ethylene glycol, propylene glycol, 1,3-propanediol, glycerol, diethylene glycol, dipropylene glycol, triethylene glycol, trimethylolpropane, trimethylolethane, tripropylene glycol, neopentyl glycol, pentaerythritol, 1,4-butanediol, hexanediol, cyclohexanedimethanol, polyethylene glycol or polypropylene glycol, isopropylidene bis(p-phenylene-oxypropanol-2), and mixtures thereof. Examples of available polyols include polyether polyols, polyester polyols, poly(alkylene carbonate) polyols, hydroxyl-containing polysulfides, polyether ester polyols, polyureapolyols, polyamide polyols, polycarbonate polyols, saturated or unsaturated polyolefin polyols, and mixtures thereof. In some embodiments, the polyol is a polyether polyol containing one or more alkylene oxide units (e.g., ethylene oxide, propylene oxide, butylene oxide, and mixtures thereof) in the backbone of the polyol. The alkylene oxide may contain straight-chain or branched-chain alkylene units. When a mixture of alkylene oxide units is present in the polyol, the different units may be randomly arranged or in block arrangements of each alkylene oxide. In some embodiments, the polyol contains a propylene oxide chain, wherein ethylene oxide chains cap the polyol. In some embodiments, the polyol is a mixture of diols and triols. In some embodiments, the available polyols have a functionality of about 1.9 or greater, about 1.95 or greater, about 2.0 or greater, about 4.0 or less, about 3.5 or less, or about 3.0 or less. In some embodiments, the polyol has an equivalent weight of at least about 200, 500, or 1,000 or greater and at most about 5,000, 3,000, or 2,500 or less.

[0052] The isocyanate prepolymers that can be used as the polyfunctional isocyanates in the adhesive compositions of the present disclosure can be prepared by any suitable method, such as bulk polymerization and solution polymerization. The method can be carried out under anhydrous conditions and under an inert atmosphere (such as a nitrogen blanket) to prevent crosslinking of the isocyanate groups by moisture. The reaction can be carried out at a temperature of about 0 °C to about 150 °C or about 25 °C to about 90 °C until the residual isocyanate content determined by sample titration approaches the desired theoretical value. The reaction for preparing the prepolymer can be carried out in the presence of a urethane catalyst, such as stannous salts of carboxylic acids (e.g., stannous octoate, stannous oleate, stannous acetate, and stannous laurate), dialkyltin dicarboxylates (e.g., dibutyltin dilaurate and dibutyltin diacetate), tertiary amines, and tin mercaptides. The amount of the catalyst used is generally about 0.005 to about 5 parts by weight of the mixture being catalyzed. The reaction can be carried out in admixture with a plasticizer. The polyisocyanate and polyol compounds used for preparing the prepolymer can be any of those described above. The amounts of the polyisocyanate compound and polyol used for preparing the prepolymer are amounts that provide the desired properties and the desired free isocyanate content and viscosity.

[0053] The second part of a two-part polyurethane adhesive composition that can be used as an adhesive composition (e.g., a structural adhesive composition) of the present disclosure can include one or more curing agents located in the second part, such as the polyols described above. The curing agent is a compound containing more than one isocyanate-reactive group, and in some embodiments, the isocyanate-reactive group is a hydroxyl or amine functional group. The curing agent can be one or more chain extenders, crosslinkers, polyols, polyamines, or prepolymers prepared as described but having isocyanate-reactive groups due to an excess equivalent of isocyanate-reactive groups.

[0054] The second part of the two - part polyurethane adhesive composition may comprise one or more low - molecular - weight compounds having two or more isocyanate - reactive groups. Such low - molecular - weight compounds may be bifunctional chain extenders or cross - linkers in which each compound has more than two active hydrogen groups. The molecular weight of the low - molecular - weight compound may be about 120 or less or about 100 or less. The low - molecular - weight compound may be one or more polyfunctional alcohols, polyfunctional alkanolamines, one or more adducts of polyfunctional alcohols and alkylene oxides, one or more adducts of polyfunctional alkanolamines and alkylene oxides, or mixtures thereof. Examples of suitable polyfunctional alcohols and polyfunctional alkanolamines include ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, heptylene glycol, octylene glycol, glycerol, trimethylolpropane, pentaerythritol, neopentyl glycol, ethanolamines (such as diethanolamine and triethanolamine), and propanolamines (such as diisopropanolamine and triisopropanolamine). In some embodiments, based on the total weight of the second part, the low - molecular - weight compound is present in the adhesive composition (e.g., the second part of the two - part polyurethane composition) in an amount of about 2 wt%, 3 wt% or 5 wt% or greater and about 16 wt%, 12 wt% or 10 wt% or less.

[0055] In some embodiments, the second part of the two - part polyurethane adhesive composition comprises a polyoxyalkylene polyamine in which each polyamine has 2 or more amines. The polyoxyalkylene polyamine may be any of those described above. In some embodiments, based on the total weight of the second part, the polyoxyalkylene polyamine is present in the adhesive composition (e.g., the second part of the two - part polyurethane composition) in an amount of about 0.2 wt%, 0.3 wt% or 0.5 wt% or greater and up to 6 wt%, 4 wt% or 2 wt% or less.

[0056] The second part of the two - part polyurethane adhesive composition can include one or more catalysts that catalyze the reaction of isocyanate groups with isocyanate - reactive groups. The catalyst can be any of those used above for preparing the polyurethane prepolymer. Based on the total weight of the second part, the organotin compound or metal alkanoate can be present in an amount of about 60 or 120 parts per million or greater and up to about 1.0%, 0.5% or 0.2% or less. Examples of suitable tertiary amine catalysts include dimorpholinodiakyl ethers, bis((dialkyl - morpholinyl)alkyl)ethers, bis-(2 - dimethylaminoethyl)ether, triethylenediamine, pentamethyldiethylenetriamine, N,N - dimethylcyclohexylamine, N,N - dimethylpiperazine, 4 - methoxyethylmorpholine, N - methylmorpholine, N - ethylmorpholine, diazabicyclic compounds, and mixtures thereof. The diazabicyclic compounds are compounds having a diazabicyclic structure, examples of which include diazabicycloalkanes and diazabicycloalkene salts. Examples of diazabicycloalkanes include diazabicyclooctane, which can be purchased from Air Products under the trademarks and names DABCO, DABCO WT, DABCO DC 1, DABCO DC 2, and DABCO DC 21. Examples of diazabicycloalkene salts include diazabicycloundecene in the form of phenolate, ethylhexanoate, oleate, and formate, which can be purchased from Air Products under the trademarks and names POLYCAT SA 1, POLYCAT SA 1 / 10, POLYCAT SA 102, and POLYCAT SA 610. Based on the weight of the second part of the two - part composition, the tertiary amine can be used in an amount of about 0.01 wt%, 0.05 wt%, 0.1 wt% or 0.2 wt% or greater and about 2.0 wt%, 1.5 wt% or 1.2 wt% or less.

[0057] The adhesive compositions of the present disclosure (in some embodiments, structural adhesive compositions) can include various additives, for example, to modify the properties of the adhesive composition. Examples of available additives include resistants (such as some silica gels), thixotropic agents (such as pyrogenic silica); pigments (such as iron oxide, brick dust, carbon black, and titanium oxide), reinforcing agents (such as silica, magnesium sulfate, calcium sulfate, and beryllium aluminosilicate), clays (such as bentonite), and any suitable fillers (such as glass beads, talc, and calcium metasilicate). An amount of up to about 30, 40, 50 parts or more of the additive per 100 parts of the adhesive component (for example, in the first part, second part, or both parts of the two - part adhesive) can be effectively utilized.

[0058] In some embodiments, the adhesive compositions of the present disclosure (in some embodiments, structural adhesive compositions) include silane coupling agents. Examples of suitable silane coupling agents include those of the formula L - [R 4[Si(Y)3] k Those represented. In this formula, L is an amino group (e.g., a primary or secondary amino group), a mercapto group (i.e., HS-), or an epoxy group (i.e., ). In some embodiments, L is an amino group or a mercapto group that can react with an isocyanate. In the formula L-[R 4 [Si(Y)3] k , k is typically 1, but when L is an amino group, k is 1 or 2. In the formula L-[R 4 [Si(Y)3] k , R 4 is an alkylene group optionally interrupted by at least one ether bond (e.g., having up to 8, 6, or 4 carbon atoms), and Y is a hydrolyzable group such as a halogen (i.e., fluorine, chlorine, bromine, or iodine), an alkoxy group (i.e., -O-alkyl), an acyloxy group (i.e., -OC(O)alkyl), or an aryloxy group (i.e., -O-aryl). Silane coupling agents can be used to promote adhesion between polyurethane and a filler (e.g., a silica filler) in an adhesive composition or between polyurethane and a substrate to which it is applied. Examples of available silane coupling agents include 3-glycidoxypropyltrimethoxysilane, which can be purchased, for example, under the trade name "DOW CORNING Z-6040 SILANE" from Dow Corning Corporation, Midland, Michigan; bis(trimethoxysilylpropyl)amine, which can be purchased, for example, from Gelest, Morrisville, PA; (3-aminopropyl)trimethoxysilane, (3-aminopropyl)triethoxysilane, (3-mercaptopropyl)trimethoxysilane, and (3-mercaptopropyl)triethoxysilane, which can be purchased, for example, from Sigma-Aldrich, St. Louis, MO. Based on the total weight of the adhesive composition, the silane coupling agent can be present in the adhesive composition in an amount of up to 5 wt%, 4 wt%, 3 wt%, 2 wt%, or 1 wt% (e.g., in the first part, the second part, or both parts of a two-part adhesive composition). For example, a coupling agent containing an amino group can be incorporated into the second part (containing an isocyanate-reactive compound) of a two-part adhesive composition.

[0059] In some embodiments, the adhesive compositions of the present disclosure (in some embodiments, structural adhesive compositions) comprise a plasticizer. Useful plasticizers can include non-functional plasticizers such as aliphatic and aromatic hydrocarbons, alkyl esters, alkyl ethers, aryl esters, and aryl ethers. Examples of plasticizers include linear and branched alkyl phthalates (such as diisononyl phthalate, dioctyl phthalate, and dibutyl phthalate), partially hydrogenated terpene commercially available as “HB-40”, trioctyl phosphate, alkyl sulfonates of phenol, toluene-sulfonamide, adipates, castor oil, xylene, 1-methyl-2-pyrrolidone, and toluene. In some embodiments, the plasticizer is a branched plasticizer such as a branched alkyl phthalate, for example diisononyl phthalate (available from BASF under the trade name PLATINOL N). The adhesive compositions (in some embodiments, structural adhesive compositions) can comprise a plasticizer in both parts. The amount of plasticizer used can be an amount sufficient to give the desired rheological properties and to disperse the components in the adhesive composition. In some embodiments, based on the total weight of the adhesive composition, the plasticizer is present at about 1 wt%, 5 wt%, or 10 wt% or greater or about 50 wt%, 40 wt%, 10 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, or 1 wt%. For two-part adhesive compositions according to the present disclosure, the plasticizer can be added to the first part, the second part, or both. In some embodiments, the plasticizer is added to the second part.

[0060] In use, the components of the two-part composition are mixed. For the two-part composition to be most amenable to commercial and industrial environments, the combined volume ratio of the two parts is preferably a convenient integer. This facilitates the application of the curable composition using conventional commercially available dispensers (including static and dynamic mixing). Such dispensers with static mixing are shown in U.S. Patent Nos. 4,538,920 and 5,082,147 and are available from Conprotec, Inc. (Salem, N.Y.) under the trade name MIXPAC from Medmix GmbH, Baar, Switzerland. Generally, these dispensers use a pair of tubular receivers arranged side by side, with each tube intended to receive one of the two parts of the polymerizable composition. Two pistons (one piston per tube) are simultaneously advanced (e.g., manually or by a hand-actuated ratchet mechanism) to expel the contents of the tubes into a common hollow elongate mixing chamber, which may also include a static mixer to facilitate blending of the two parts. The blended polymerizable composition is extruded from the mixing chamber onto a substrate. When an electrically driven device is used, dynamic mixing can be employed. Once the tubes are emptied, they can be replaced with new tubes and the application process continued. The combined volume ratio of the two parts of the polymerizable composition is controlled by the diameter of the tubes. (The size of each piston is sized to fit within a tube of fixed diameter, and the pistons are advanced into the tubes at the same rate.) A single dispenser is generally intended to be used with a variety of different two-part polymerizable compositions, and the pistons are sized to deliver the two parts of the polymerizable composition at a convenient mixing ratio. Some common mixing ratios are 1:1, 2:1, 4:1, and 10:1, and can also be advantageous ratios. In some embodiments, the two parts are blended at a mixing ratio of about 1:1.

[0061] In some embodiments, the compounds of the present disclosure are present in a range of 0.1 wt% to 20 wt%, based on the total weight of the adhesive composition (in some embodiments, a structural adhesive composition). In some embodiments, the compounds of the present disclosure are present in a range of 0.1 wt% to 10 wt%, 0.1 wt% to 5 wt%, or 1 wt% to 5 wt%, based on the total weight of the adhesive composition (e.g., the first part, the second part, or both parts of a two-part adhesive).

[0062] The adhesive compositions of the present disclosure can be used, for example, to bond a first substrate to a second substrate to provide a bonded article. Many types of substrates can be bonded with the compositions of the present disclosure, such as metals (e.g., galvanized steel, stainless steel, or aluminum), glass (e.g., which may be coated with indium tin oxide), polymers (e.g., plastics, rubbers, thermoplastic elastomers, or thermosetting materials), or composite materials. Composite materials can be made from any two or more constituent materials having different physical or chemical properties. When the components are combined to prepare a composite material, a material having properties different from the individual components is generally obtained. Some examples of available composite materials include fiber-reinforced polymers (e.g., carbon fiber-reinforced epoxy and glass-reinforced plastics), metal matrix composites, and ceramic matrix composites. Available polymer substrates that can be bonded include polymers such as polyolefins (polypropylene, polyethylene, high-density polyethylene, polypropylene blends), fluoropolymers, polyamide 6 (PA6), polyamide 6,6, acrylonitrile butadiene styrene (ABS), polycarbonate (PC), PC / ABS blends, polyvinyl chloride (PVC), polyamide (PA), polyurethane (PUR), thermoplastic elastomers (TPE), polyolefin elastomers (e.g., ethylene propylene rubber, ethylene propylene diene monomer rubber), fluoropolymer elastomers, polyoxymethylene (POM), polystyrene, poly(methyl)methacrylate (PMMA), polyvinyl chloride (PVC), polyetheretherketone (PEEK), and combinations thereof. The substrate can also include a metal coating on such polymers.

[0063] The present disclosure provides an article bonded with the compositions disclosed herein in any of its embodiments, wherein the composition is cured and wherein the article comprises at least one of plastic, metal, or glass, and in some embodiments, comprises at least one of metal or glass.

[0064] The present disclosure provides a method of making an adhesive article that includes a first substrate and a second substrate. The method includes applying a composition of the present disclosure to at least one of the first substrate or the second substrate, contacting at least a portion of the composition with at least a portion of a surface of the second substrate, and at least partially curing the composition to make the adhesive article. In some embodiments, the method includes combining a first portion and a second portion of a two-part composition to provide an adhesive composition, applying the adhesive composition to at least a portion of a surface of the first substrate, adhering the first substrate and the second substrate using the adhesive composition, and at least partially curing the adhesive composition to make the adhesive article. In some embodiments, at least one of the first substrate or the second substrate includes at least one plastic. In some embodiments, at least one of the first substrate or the second substrate includes at least one of metal or glass. The method is carried out with or without subjecting a low surface energy plastic to flame treatment, corona discharge, plasma treatment, oxidation by ozone or an oxidizing acid, sputter etching, primer treatment, or any combination thereof.

[0065] When combining the first and second portions, as described above, it is desirable to use the composition to adhere the first and second substrates during the pot life of the composition. Although it is not practical to list a specific curing temperature that is applicable to all cases, generally speaking, suitable temperatures are in the range of about 23 °C to about 200 °C. In some embodiments, advantageously, the composition can cure at room temperature (e.g., 23 °C to 30 °C, or less than 40 °C) in, for example, at least 5 minutes, 10 minutes, 20 minutes, 30 minutes, or 45 minutes. In some embodiments, advantageously, the composition can cure at room temperature (e.g., 23 °C to 30 °C, less than 40 °C) in at most 60 minutes, 90 minutes, 120 minutes, 6 hours, 12 hours, 24 hours, 48 hours, or 72 hours. Under ambient conditions, full strength is typically achieved in less than 24 hours. If desired, post-curing at an elevated temperature can also be used.

[0066] The first and second substrates can be joined together with pressure to force excess composition out of the bond layer. This can be advantageous for replacing composition that has cured to too great an extent. A typical bond layer thickness is about 0.1 mm to 0.3 mm, but can exceed 1.0 mm when gap filling is desired.

[0067] The compositions of the present disclosure can be used, for example, to adhere electronic articles as well as automotive (e.g., electric vehicles) and aerospace components.

[0068] As shown in the following examples, the compounds of the present disclosure generally improve the adhesion between metal (e.g., aluminum) substrates. Additionally, with respect to the lap shear strength observed for a control composition that does not include the compounds of the present disclosure, each of Examples 1 to 8 of the compounds increases the lap shear strength of the bond between aluminum and glass by at least about 50%. In some embodiments, the compounds of the present disclosure increase the lap shear strength of the bond between aluminum and glass by 100% or more.

[0069] Some embodiments of the present disclosure

[0070] In a first embodiment, the present disclosure provides a compound represented by the following formula:

[0071]

[0072] wherein

[0073] each A independently represents a saturated, unsaturated, or aromatic ring;

[0074] each R independently is hydrogen or methyl;

[0075] each R 1 independently is an alkylene group optionally interrupted by one or more -O- groups;

[0076] each R 3 independently is an alkylene group, an arylene group, or an alkylene group optionally interrupted or terminated by an arylene group, optionally interrupted by one or more -O- groups or one to three -NR 2 - groups and optionally terminated by -N(R 2 )2; and

[0077] each R 2 independently is hydrogen, an alkyl group, an aryl group, an arylalkylene group, or In a second embodiment, the present disclosure provides the compound according to the first embodiment, wherein A is a saturated six - membered ring, and wherein R 1 is a linear alkylene group having 2 to 4 carbon atoms. In a third embodiment, the present disclosure provides the compound according to the first embodiment or the second embodiment, wherein R 3 is an alkylene group optionally interrupted by one or more -O- groups or one to three -NR 2 - groups and optionally terminated by -N(R 2 )2; and wherein each R 2 independently is hydrogen or In a fourth embodiment, the present disclosure provides the compound according to any one of the first to third embodiments, wherein R 3is an alkylene group optionally interrupted by one or more -O- groups. In a fifth embodiment, the present disclosure provides a composition according to any one of the first to fourth embodiments, wherein each R 2 is hydrogen.

[0078] In a sixth embodiment, the present disclosure provides an adhesive composition comprising a compound according to any one of the first to fifth embodiments. In a seventh embodiment, the present disclosure provides the adhesive composition according to the sixth embodiment, wherein the adhesive composition is a structural adhesive composition. In an eighth embodiment, the present disclosure provides the adhesive composition according to the sixth or seventh embodiment, wherein the adhesive composition is a two-part structural adhesive composition. In a ninth embodiment, the present disclosure provides the adhesive composition according to any one of the sixth to eighth embodiments, wherein the adhesive composition is part of a two-part structural adhesive composition. In a tenth embodiment, the present disclosure provides the adhesive composition according to any one of the sixth to ninth embodiments, wherein the adhesive composition further comprises at least one polyol. In an eleventh embodiment, the present disclosure provides the adhesive composition according to any one of the sixth to tenth embodiments, wherein the adhesive composition is a polyurethane adhesive composition. In a twelfth embodiment, the present disclosure provides the adhesive composition according to any one of the fifth to eleventh embodiments, wherein the adhesive composition further comprises an inorganic filler. In a thirteenth embodiment, the present disclosure provides the adhesive composition according to any one of the fifth to twelfth embodiments, wherein the compound is present in a range of 0.1 wt% to 20 wt% based on the total weight of the adhesive composition.

[0079] In a fourteenth embodiment, the present disclosure provides a method of bonding a first substrate and a second substrate, the method comprising applying an adhesive composition according to any one of the sixth to thirteenth embodiments to at least a portion of one surface of the first substrate, bringing at least a portion of the adhesive composition into contact with at least a portion of one surface of the second substrate; and causing the adhesive composition to cure at least partially and form a structural adhesive. In a fifteenth embodiment, the present disclosure provides the method according to any one of the fourteenth embodiments, wherein at least one of the first substrate or the second substrate comprises at least one of metal, glass, or plastic. In a sixteenth embodiment, the present disclosure provides the method according to the fourteenth or fifteenth embodiment, wherein the adhesive composition is a first part of a two-part structural adhesive composition, the method further comprising combining the first part and a second part to provide a curable adhesive composition. In a seventeenth embodiment, the present disclosure provides a bonded article comprising a structural adhesive bonded to a first substrate and a second substrate, the bonded article being prepared according to the method of any one of the fourteenth to sixteenth embodiments.

[0080] To more fully understand the present disclosure, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and should not be construed as limiting the present disclosure in any way.

[0081] Examples

[0082] Unless otherwise specified, all parts, percentages, ratios, etc. used in the examples and the remainder of the specification are by weight, and all reagents used in the examples are obtained from or commercially available from general chemical suppliers such as, for example, Sigma-Aldrich, St. Louis, MO, USA, or can be synthesized by conventional methods. The following abbreviations are used in this section: cm = centimeter, mm = millimeter, μm = micrometer, g = gram, lb = pound, mmole = millimole, °C = degree Celsius, kN = kilonewton, and N = newton. Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the remainder of this specification are by weight.

[0083] Table 1: Material list

[0084]

[0085]

[0086] Test methods

[0087] Lap - shear test

[0088] Each sample formulation was loaded individually into the two-part side of a 2:1 dual-syringe barrel dispenser, using the promoter from 3M SCOTCH-WELD DP6310NS composite bonding adhesive (3M Company, St. Paul, MN) in the one-part side of the dispenser in each case. All bonds were prepared by dispensing the sample formulation and the promoter through a static mixing head. The resulting adhesive was used to prepare samples for lap shear test specimens on sandblasted aluminum and IPA-wiped glass. The lap shear specimens were 2.54 cm × 10.16 cm × 0.16 cm blocks of aluminum or clear glass specimens, nominally using 0.45 mm spacer beads and having a 1.27 cm overlap. The bond layer was clamped with bulldog clips during the curing process, and the clips were removed after 24 hours at 25 °C. The lap shear test was run on a 5000 lb (22 kN) load cell. Values are the average of three samples.

[0089] Examples 1 to 8 (EX1 - EX8): Preparation of polyfunctional cyclic imides

[0090] A 30 g vial containing a magnetic stir bar was charged with diamine 1 (1.00 g, 3.7 mmol) and acrylate (1.84 g, 7.4 mmol). The vial was loosely capped with a rubber septum and the contents were heated to a temperature of 60 °C by a silicone oil bath under magnetic stirring. After 6 hours at this temperature, the resulting adduct was cooled to 25 °C and stored for further use. All subsequent tackifiers were synthesized using this procedure, varying the molar amounts to produce bipedal (2:1 acrylate:amine), tripedal (3:1 acrylate:amine), or quadrupedal (4:1 acrylate:amine). Table 2 presents Examples PEX1 - PEX8 and CEX9. The materials used and their amounts are listed in Table 2. The molar ratio refers to the molar ratio of acrylate to diamine.

[0091] Table 2. Tackifier Examples 1 to 8 (PEX1 - PEX8) and OLS results

[0092]

[0093] Adhesive composition

[0094] The polyol (44.766 wt%), castor oil (20.0 wt%), DPG (4 wt%), diamine 1 (3 wt%), DABCO (0.145 wt%), aminosilane (0.5 wt%), 5A MS (0.95 wt%), pyrogenic silica (0.95 wt%), rheology modifier (2.039 wt%), talc (20.44 wt%), exemplary cyclic imide (3 wt%) and carbon black (0.21 wt%) are combined in a high speed mixer cup and mixed at 2000 rpm for 4 minutes. Thus, a uniform thick paste is prepared and used as described in the lap shear test protocol.

[0095] Without departing from the scope and spirit of the present disclosure, various modifications and changes may be made by those skilled in the art, and it should be understood that the invention should not be unduly limited to the exemplary embodiments listed herein.

Claims

1. A compound represented by the following formula: Wherein each A independently represents a saturated, unsaturated or aromatic ring; each R is independently hydrogen or methyl; Each R 1 independently is an alkylene group optionally interrupted by one or more -O- groups; Each R 3 is independently an alkylene, arylene or an alkylene optionally interrupted or terminated by arylene and optionally interrupted by one or more -O- groups or one to three -NR 2 - groups and optionally terminated by -N(R 2 )2; and Each R 2 independently is hydrogen, alkyl, aryl, arylalkylene or 2. The compound according to claim 1, wherein A is a saturated six-membered ring, and wherein R 1 is a linear alkylene having 2 to 4 carbon atoms.

3. The compound according to claim 1 or 2, wherein R 3 is an alkylene group optionally interrupted by one or more -O- groups or one to three -NR 2 - groups and optionally terminated by -N(R 2 )2; and wherein each R 2 is independently hydrogen or 4. The compound according to any one of claims 1 to 3, wherein R 3 is an alkylene group optionally interrupted by one or more -O- groups, and wherein each R 2 is hydrogen.

5. An adhesive composition comprising the compound according to any one of claims 1 to 4.

6. The adhesive composition according to claim 5, wherein the adhesive composition is a structural adhesive composition.

7. The adhesive composition according to claim 5 or 6, wherein the adhesive composition is a two-part structural adhesive composition.

8. The adhesive composition according to any one of claims 5 to 7, wherein the adhesive composition is part of a two-part structural adhesive composition.

9. The adhesive composition according to claim 8, further comprising at least one polyol.

10. The adhesive composition according to any one of claims 6 to 9, wherein the adhesive composition is a polyurethane adhesive composition.

11. The adhesive composition according to any one of claims 5 to 10, further comprising an inorganic filler.

12. The adhesive composition according to any one of claims 5 to 11, wherein the compound is present in a range of 0.1% to 20% by weight based on the total weight of the adhesive composition.

13. A method of bonding a first substrate and a second substrate, the method comprising: applying the adhesive composition according to any one of claims 6 to 12 to at least a portion of one surface of the first substrate; bringing at least a portion of the adhesive composition into contact with at least a portion of one surface of the second substrate; and curing at least a portion of the adhesive composition to form the structural adhesive.

14. The method according to claim 13, wherein at least one of the first substrate or the second substrate comprises at least one of metal, glass or plastic.

15. The method according to claim 13 or 14, wherein the adhesive composition is the first part of a two-part structural adhesive composition, and the method further comprises combining the first part and the second part to provide a curable adhesive composition.

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