One-component (1K) compositions based on modified epoxy resins

Abstract

The present invention relates to a one-component (1K) composition comprising: a) at least one epoxy resin; b) at least one internally flexibilized epoxy resin, characterized by a Shore D hardness of 45 or less when cured with diethylenetriamine, as measured by durometer according to ASTM D2240; c) core-shell rubber particles; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, the curing agent comprising dicyandiamide; and e) at least one accelerator. The one-component composition is particularly useful as a structural adhesive.

Description

[Technical Field]

[0001] The present invention relates to a one-component (1K) composition based on a modified epoxy resin. More particularly, the present invention relates to a one-component composition comprising an epoxy resin, at least one modified epoxy resin, and a curing agent comprising dicyandiamide. [Background technology]

[0002] Epoxy resins have enjoyed widespread use primarily due to the ability to tailor the properties of the cured epoxy resin to achieve specific performance characteristics through the specific selection of resins, modifiers, and crosslinkers (or hardeners).

[0003] Recognizing their versatility, properly cured epoxy resins also possess several other attributes, including, among others: excellent chemical resistance, especially to alkaline environments; high tensile and compressive strength; high fatigue strength; low shrinkage upon cure; and electrical insulating properties and their retention upon aging or environmental exposure.

[0004] These attributes allow epoxy resins to be used as structural adhesives to join materials with mechanical strength comparable to mechanical fasteners: structural adhesives can be used to replace or augment traditional joining techniques such as welding, which often cannot be done with dissimilar materials, polymers, or polymer composites, or to replace or augment mechanical fasteners such as nuts and bolts, screws and rivets.

[0005] In such applications, epoxy adhesives are often required to bond inclined, vertical, or other shaped surfaces, examples of which include weld seams and flanges on automotive vehicles, as well as hem flanges. This places requirements on the processability of the epoxy composition and its ability to wet the surfaces to which it is applied. The thixotropic properties of the composition, both during application and during the curing process, especially under conditions of temperature, pressure, moisture, and shear, can also determine the composition's usefulness in bonding specific materials. Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors believe that a need exists for a controlled cure adhesive composition suitable for use in structural bonding applications that can advantageously replace known compositions and eliminate the need for additional support fixtures during adhesive bonding operations. [Means for solving the problem]

[0007] According to a first aspect of the present invention, there is provided a one-component (1K) composition comprising: a) at least one epoxy resin; b) at least one internally flexibilized epoxy resin characterized by a Shore D hardness of 45 or less when cured with diethylenetriamine, as measured with a durometer according to ASTM D2240; c) core-shell rubber particles; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, characterized in that it comprises dicyandiamide; and e) at least one accelerator; A one-component (1K) composition is provided comprising:

[0008] In certain important embodiments, the one-component composition may further comprise at least one chelate-modified epoxy resin; and / or at least one elastomer-modified epoxy resin.

[0009] The internally flexibilized epoxy resin of the composition should preferably have an epoxide equivalent weight of 200 to 600 g / eq. Regardless of or in addition to that consideration, the internally flexibilized epoxy resin should be characterized by a Shore D hardness of 40 or less when cured with diethylenetriamine, as measured by a durometer according to ASTM D2240.

[0010] The dicyandiamide of the present invention preferably has a particulate morphology characterized by an average particle size (d50) of 0.5 to 100 μm as measured by dynamic light scattering. Regardless of or in addition to that consideration, e) the at least one accelerator preferably comprises or consists of at least one urea derivative of formula (V) or formula (VI): TIFF0007809055000001.tif97123In the formula, at least one residue R 1 , R 2 , R 3 is not hydrogen; R 1 and R 2 are independently hydrogen, C1-C 18 Alkyl and C3-C 18 cycloalkyl; R 3 is hydrogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C6-C 18 Aryl, C6-C 18 Aralkyl, C6-C 18 Alkylaryl, -NHC(O)NR 1 R 2 C1-C substituted with 18 Alkyl, -NHC(O)NR 1 R 2 C3-C substituted with 18 Cycloalkyl, -NHC(O)NR 1 R2 C6-C substituted with 18 Aryl; -NHC(O)NR 1 R 2 C6-C substituted with 18 aralkyl; and -NHC(O)NR 1 R 2 C6-C substituted with 18 is aralkyl; and R 4 , R 5 , R 6 , R 7 and R 8 are independently hydrogen, halogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C6-C 18 Aryl, C6-C 18 Aralkyl, C6-C 18 -Alkylaryl, -CF3, -NHC(O)NR 1 R 2 , -NHC(O)NR 1 R 2 C1-C substituted with 18 Alkyl, -NHC(O)NR 1 R 2 C3-C substituted with 18 Cycloalkyl, -NHC(O)NR 1 R 2 C6-C substituted with 18 Aryl; -NHC(O)NR 1 R 2 C6-C substituted with 18 aralkyl; and -NHC(O)NR 1 R 2 C6-C substituted with 18 aralkyl.

[0011] It may be noted that the use of at least one urea derivative selected from the group consisting of N,N-diethylurea, N,N-dipropylurea, N,N-ethyl-methylurea, N,N-dimethylurea, 1,1'-(4-methyl-m-phenylene)-bis-(3,3-dimethylurea) and 1,1'-(2-methyl-m-phenylene)-bis-(3,3-dimethylurea) is particularly preferred.

[0012] When the accelerator of the composition contains or consists of the above urea derivative, the molar ratio of dicyandiamide to the sum of the urea derivatives is preferably within the range of 1:1 to 4:1.

[0013] According to a second aspect of the present invention there is provided a cured product obtainable from a one-component (1K) composition as defined hereinabove and in the appended claims.

[0014] A further aspect of the present invention provides the use of the cured reaction product as defined hereinabove and in the appended claims as a structural adhesive. DETAILED DESCRIPTION OF THE INVENTION

[0015] definition As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0016] As used herein, the terms "comprising," "comprises," and "comprised of" are synonymous with "including," "includes," "containing," or "contains" and are inclusive or open-ended and do not exclude additional, unrecited members, elements, or method steps.

[0017] As used herein, the term "consisting of" excludes any elements, components, materials or method steps not specified.

[0018] As used herein, the term "consisting essentially of" limits the scope of a claim to the specified elements, components, materials, or method steps, as well as auxiliary elements, components, materials, or method steps that do not materially affect the basic and novel characteristics of the claimed invention.

[0019] When amounts, concentrations, dimensions, and other parameters are expressed in the form of ranges, preferred ranges, upper values, lower values, or preferred upper values ​​and limits, it is understood that any range obtained by combining any upper value or preferred value with any lower value or preferred value is also specifically disclosed, whether or not the resulting range is expressly stated in the context.

[0020] Furthermore, according to standard understanding, weight ranges expressed as "from 0" specifically include 0 wt. %: the component defined by the range may or may not be present in the composition.

[0021] The terms "preferred," "preferably," "desirably," and "particularly" are frequently used herein to refer to embodiments of the present disclosure that may offer particular benefits, under certain circumstances. However, the recitation of one or more "preferable," "preferred," "desirable," or "particular" embodiments does not imply that other embodiments are not useful, and is not intended to exclude such other embodiments from the scope of the present disclosure.

[0022] As used throughout this application, the term "may" is used in a permissive rather than a mandatory sense - that is, to mean having the possibility.

[0023] As used herein, room temperature is 23° C.±2° C. As used herein, "ambient conditions" means the temperature and pressure surrounding the composition, or the coating layer or substrate for the coating layer, at which the composition is disposed.

[0024] As used herein, the term "equivalents (eq)" refers to the relative number of reactive groups present in a reaction, as is customary in chemical notation.

[0025] The term "equivalent weight," as used herein, refers to the molecular weight divided by the number of associated functional groups. Thus, "epoxy equivalent weight" (EEW) means the weight in grams of a resin containing one equivalent of epoxy. Similarly, "amine hydrogen equivalent weight" (AHEW) is the weight in grams of an organic amine containing one amine hydrogen.

[0026] As used herein, the term "epoxide" refers to a compound characterized by the presence of at least one cyclic ether group, i.e., a group in which an ether oxygen atom is bonded to two adjacent carbon atoms, thereby forming a cyclic structure. The term is intended to include monoepoxide compounds, polyepoxide compounds (having two or more epoxide groups), and epoxide-terminated prepolymers. The term "monoepoxide compound" is intended to refer to an epoxide compound having one epoxy group. The term "polyepoxide compound" is intended to refer to an epoxide compound having at least two epoxy groups. The term "diepoxide compound" is intended to refer to an epoxide compound having two epoxy groups.

[0027] The epoxides may be unsubstituted or inertly substituted. Exemplary inert substituents include chlorine, bromine, fluorine, and phenyl.

[0028] The term "internal flexibilization" as used herein refers to chemical modification of the epoxy backbone; this is conventionally achieved by incorporating aliphatic moieties, preferably alkylene, oxyalkylene, or polyester units, or C=C bonds into the epoxy backbone. Double carbon-carbon bonds, for example, increase flexibility by improving the rotation of adjacent single carbon-carbon bonds. Separately, the flexibilized epoxy resin, when cured with diethylenetriamine (DETA), has a Shore D hardness of 45 or less, preferably 40 or less, as measured by a durometer according to ASTM D2240. Useful references for preparing internally flexibilized resins that meet this hardness requirement and are useful in the present invention include, for example, U.S. Pat. No. 3,522,210 (Sellers et al.); U.S. Pat. No. 4,883,830 (Kitabatake et al.); and U.S. Pat. No. 4,793,703 (Fretz).

[0029] As used herein, "C1-C n An "alkyl" group refers to a monovalent group containing 1 to n carbon atoms, i.e., a radical of an alkane, and includes straight-chain and branched organic groups. Thus, "C1-C 30 An "alkyl" group refers to a monovalent group containing 1 to 30 carbon atoms, i.e., a radical of an alkane, including straight-chain and branched organic groups. Examples of alkyl groups include, but are not limited to, methyl; ethyl; propyl; isopropyl; n-butyl; isobutyl; sec-butyl; tert-butyl; n-pentyl; n-hexyl; n-heptyl; and 2-ethylhexyl. In the present invention, such alkyl groups may be unsubstituted or substituted with one or more substituents, such as halo, nitro, cyano, amido, amino, sulfonyl, sulfinyl, sulfanyl, sulfoxy, urea, thiourea, sulfamoyl, sulfamido, and hydroxy. Important substituents, such as urea for the accelerators described, may be mentioned individually herein. Also, halogenated derivatives of the exemplary hydrocarbon groups listed above may be mentioned as examples of particularly suitable substituted alkyl groups. However, in general, unsubstituted alkyl groups containing 1 to 18 carbon atoms (C1-C2) are preferred. 18alkyl), e.g., alkyls having 1 to 12 carbon atoms (C1-C 12 It should be noted that unsubstituted alkyl groups containing 1 to 6 carbon atoms (C1-C6 alkyl) are preferred.

[0030] The term “C3-C 30 "Cycloalkyl" is understood to mean a saturated monocyclic, bicyclic or tricyclic hydrocarbon group having 3 to 30 carbon atoms. Generally, cycloalkyl groups containing 3 to 18 carbon atoms (C3-C 18 It should be noted that cycloalkyl groups are preferred. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, adamantane, and norbornane.

[0031] As used herein, the term "C-C alkyl group" used alone or as part of a larger moiety, such as an "aralkyl group," 18 "Aryl" groups refer to optionally substituted monocyclic, bicyclic, and tricyclic ring systems in which the monocyclic ring is aromatic or in which at least one of the rings of the bicyclic or tricyclic ring is aromatic. Bicyclic and tricyclic ring systems include benzo-fused 2- to 3-membered carbocyclic rings. Exemplary aryl groups include phenyl; indenyl; naphthalenyl; tetrahydronaphthyl; tetrahydroindenyl; tetrahydroanthracenyl; and anthracenyl. It may also be noted that the phenyl group is preferred.

[0032] As used herein, "C2-C 20 "Alkenyl" refers to a hydrocarbyl group having 2 to 20 carbon atoms and at least one unit of ethylenic unsaturation. Alkenyl groups can be linear, branched, or cyclic, and can be optionally substituted. The term "alkenyl" also includes groups having "cis" and "trans" configurations, or alternatively, "E" and "Z" configurations, as understood by those skilled in the art. However, generally, alkenyl groups having 2 to 10 (C 2-10 ) or 2 to 8 (C 2-8It should be noted that unsubstituted alkenyl groups containing carbon atoms of C2-C are preferred. 12 Examples of alkenyl groups include: -CH=CH2; -CH=CHCH3; -CH2CH=CH2; -C(=CH2)(CH3); -CH=CHCH2CH3; -CH2CH=CHCH3; -CH2CH2CH=CH2; -CH=C(CH3)2; -CH2C(=CH2)(CH3); -C(=CH2)CH2CH3; -C(CH3)=CHCH3; -C(CH3)CH=CH2; -CH=CHCH2CH2CH3; -CH2CH=CHCH2CH 3; -CH2CH2CH=CHCH3;-CH2CH2CH2CH=CH2;-C(=CH2)CH2CH2CH3;-C(CH3)=CHCH2CH3;-CH(CH3)CH=CHCH ; These include, but are not limited to, -CH(CH3)CH2CH=CH2; -CH2CH=C(CH3)2; 1-cyclopent-1-enyl; 1-cyclopent-2-enyl; 1-cyclopent-3-enyl; 1-cyclohex-1-enyl; 1-cyclohex-2-enyl; and 1-cyclohexyl-3-enyl.

[0033] As used herein, "alkylaryl" refers to an alkyl-substituted aryl group, and "substituted alkylaryl" refers to an alkylaryl group further bearing one or more substituents as defined above. Additionally, as used herein, "aralkyl" refers to an alkyl group substituted with an aryl radical as defined above.

[0034] The term "hetero," as used herein, refers to groups or moieties that include one or more heteroatoms, such as N, O, Si, and S. Thus, for example, "heterocyclic" refers to a cyclic group having, for example, N, O, Si, or S as part of the ring structure. "Heteroalkyl" and "heterocycloalkyl" moieties are alkyl and cycloalkyl groups, as defined above, respectively, that contain N, O, Si, or S as part of their structure.

[0035] As used herein, the term "catalytic amount" means a substoichiometric amount of catalyst relative to a reactant, unless otherwise specified.

[0036] The term "accelerator," as used herein, refers to a chemical agent that is co-reactive with a curing agent and reduces the cure time of a composition compared to that achievable by the curing agent alone under comparable conditions.

[0037] As used herein, a "primary amino group" refers to an NH group bonded to an organic group, and a "secondary amino group" refers to an NH group bonded to two organic groups, both of which may be part of a ring. As used, the term "amine hydrogen" refers to the hydrogen atoms of the primary and secondary amino groups.

[0038] When "amine number" is referred to herein, it can be determined by titration of the amine acetate ion with a diluent, typically a 1N HCl solution. For pure materials, the amine number can be calculated using the molecular weight of the pure compound and KOH (56.1 g / mol). A useful guide for explanation can be found at https: / / dowac.custhelp.com / app / answers / detail / a_id / 12987.

[0039] The term "photoinitiator" as used herein refers to a compound that can be activated by irradiation with an energy-carrying activation beam, such as electromagnetic radiation. The term is intended to encompass both photoacid generators and photobase generators. Specifically, the term "photoacid generator" refers to a compound or polymer that generates an acid for catalysis of an acid-curing resin system upon exposure to actinic radiation. The term "photobase generator" refers to any material that generates one or more bases upon exposure to suitable radiation.

[0040] The term "Lewis acid," as used herein, refers to any molecule or ion—often called an electrophile—that can bind to another molecule or ion by forming a covalent bond with two electrons from the second molecule or ion; thus, a Lewis acid is an electron acceptor.

[0041] The term "polyol" as used herein is intended to include diols and higher functionality hydroxyl compounds.

[0042] The hydroxyl (OH) number given herein is measured according to Japanese Industrial Standard (JIS) K-1557, 6.4. The isocyanate content values ​​given herein are measured according to EN ISO 1 1909.

[0043] Molecular weights as referred to herein can be determined using gel permeation chromatography (GPC), such as performed in accordance with ASTM 3536, using polystyrene calibration standards.

[0044] As used herein, "anhydrous" means that the relevant composition contains less than 0.25% by weight of water. For example, the composition may contain less than 0.1% by weight of water, or may contain no water at all. The term "essentially free of solvent" should be interpreted in the same way as meaning that the relevant composition contains less than 0.25% by weight of solvent.

[0045] The viscosity of the coating compositions described herein is measured using a Brookfield viscometer, Model RVT, at standard conditions of 20°C and 50% relative humidity (RH), unless otherwise specified. The viscometer is calibrated using silicone oils of various known viscosities, ranging from 5,000 cps to 50,000 cps. A set of RV spindles attached to the viscometer is used for calibration. Measurements of the coating compositions are taken at a speed of 20 revolutions per minute using a No. 6 spindle for 1 minute until the viscometer reaches equilibrium. The calibration is then used to calculate the viscosity corresponding to the equilibrium reading.

[0046] As used herein, "thixotropy index" is defined as the viscosity measurement obtained at a spindle speed of 0.5 rpm divided by the viscosity measurement obtained at a spindle speed of 5 rpm.

[0047] As used herein, the term "lap shear strength" is defined as the shear strength of a bonding material adhesive when tested on a single-lap joint specimen. The test is applicable to determining adhesive strength, surface preparation parameters, and adhesive environmental durability. As used herein, lap shear testing was performed in accordance with ASTM D1002 10(2019) Standard Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal) by joining two overlapping aluminum coupons (2.5 cm x 10 cm x 0.16 cm). Prior to application of the composition, the coupons were rinsed twice with acetone to remove any oil and ink residue, and then etched with chromic acid to remove excess surface oxide. Each measurement was performed at least six times for accuracy, and the results were averaged.

[0048] a) Epoxide compounds The composition of the present invention should typically contain the epoxy resin a) in an amount of 20 to 70 wt.%, preferably 30 to 60 wt.%, based on the weight of the composition. For example, the composition of the present invention may contain 35 to 60 wt.%, or 40 to 60 wt.%, of the epoxy resin (a) based on the weight of the composition.

[0049] Epoxy resins, as used herein, can include monofunctional epoxy resins, multifunctional (multi-) or polyfunctional (poly-) epoxy resins, and combinations thereof. Epoxy resins can be pure compounds, as well as mixed epoxy-functional compounds, including mixtures of compounds with different numbers of epoxy groups per molecule. Epoxy resins can be saturated or unsaturated, aliphatic, cycloaliphatic, aromatic, or heterocyclic, and can be substituted. Furthermore, epoxy resins can be monomeric or polymeric.

[0050] While not intended to limit the invention, exemplary monoepoxide compounds include: alkylene oxides; epoxy-substituted alicyclic hydrocarbons, such as cyclohexene oxide, vinylcyclohexene monoxide, (+)-cis-limonene oxide, (+)-cis,trans-limonene oxide, (-)-cis,trans-limonene oxide, cyclooctene oxide, cyclododecene oxide, and α-pinene oxide; epoxy-substituted aromatic hydrocarbons; monoepoxy-substituted alkyl ethers of monohydric alcohols or phenols, such as glycidyl ethers of aliphatic, alicyclic, and aromatic alcohols; monocarboxylic acids; Monoepoxy-substituted alkyl esters include, for example, glycidyl esters of aliphatic, alicyclic, and aromatic monocarboxylic acids; monoepoxy-substituted alkyl esters of polycarboxylic acids in which the other carboxy group is esterified with an alkanol; alkyl and alkenyl esters of epoxy-substituted monocarboxylic acids; epoxy alkyl ethers of polyhydric alcohols in which the other OH group is esterified or etherified with a carboxylic acid or alcohol; and monoesters of polyhydric alcohols and epoxy monocarboxylic acids in which the other OH group is esterified or etherified with a carboxylic acid or alcohol.

[0051] By way of example, the following glycidyl ethers may be mentioned as being particularly suitable monoepoxide compounds for use herein: methyl glycidyl ether; ethyl glycidyl ether; propyl glycidyl ether; butyl glycidyl ether; pentyl glycidyl ether; hexyl glycidyl ether; cyclohexyl glycidyl ether; octyl glycidyl ether; 2-ethylhexyl glycidyl ether; allyl glycidyl ether; benzyl glycidyl ether; phenyl glycidyl ether; 4-tert-butylphenyl glycidyl ether; 1-naphthyl glycidyl ether; 2-naphthyl glycidyl ether; 2-chlorophenyl glycidyl ether; 4-chlorophenyl glycidyl ether; 4-bromophenyl glycidyl ether; 2,4,6-trichlorophenyl glycidyl ether; 2,4,6-tribromophenyl glycidyl ether; pentafluorophenyl glycidyl ether; o-cresyl glycidyl ether; m-cresyl glycidyl ether; and p-cresyl glycidyl ether.

[0052] In important embodiments, the monoepoxide compound conforms to formula (I) herein below: TIFF0007809055000002.tif2560 formula, R 2 , R 3 , R 4 and R 5 may be the same or different and are hydrogen, halogen atoms, C1-C8 alkyl groups, C3-C 10 Cycloalkyl groups, C2-C 12 Alkenyl, C6-C 18 Aryl group or C7-C 18 aralkyl groups, where R 3 and R 4 At least one of these is not hydrogen.

[0053] R 2 , R 3 and R 5 is hydrogen and R 4is preferably either a phenyl group or a C1-C8 alkyl group, more preferably a C1-C4 alkyl group.

[0054] In view of this embodiment, exemplary monoepoxides include: ethylene oxide; 1,2-propylene oxide (propylene oxide); 1,2-butylene oxide; cis-2,3-epoxybutane; trans-2,3-epoxybutane; 1,2-epoxypentane; 1,2-epoxyhexane; 1,2-heptylene oxide; decene oxide; butadiene oxide; isoprene oxide; and styrene oxide.

[0055] The present invention refers to the use of at least one monoepoxide compound selected from the group consisting of ethylene oxide; propylene oxide; cyclohexene oxide; (+)-cis-limonene oxide; (+)-cis,trans-limonene oxide; (-)-cis,trans-limonene oxide; cyclooctene oxide; and cyclododecene oxide.

[0056] Again, without intending to limit the invention, suitable polyepoxide compounds can be liquid, solid, or in solution in a solvent. Furthermore, such polyepoxide compounds should have an epoxide equivalent weight of 100 to 700 g / eq, e.g., 120 to 320 g / eq. Generally, diepoxide compounds having an epoxide equivalent weight of less than 500 g / eq or even less than 400 g / eq are preferred; this is primarily due to cost considerations, as well as production, and the lower the molecular weight of the epoxy resin, the more limited the processing required in purification.

[0057] As examples of types or groups of polyepoxide compounds that can be polymerized in the present invention, mention may be made of glycidyl ethers of polyhydric alcohols and polyhydric phenols; glycidyl esters of polycarboxylic acids; and epoxidized polyethylenically unsaturated hydrocarbons, esters, ethers and amides.

[0058] Suitable diglycidyl ether compounds may be aromatic, aliphatic, or cycloaliphatic in nature and may therefore be derived from dihydric phenols and dihydric alcohols. Useful classes of such diglycidyl ethers include diglycidyl ethers of aliphatic and cycloaliphatic diols, such as 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,12-dodecanediol, cyclopentanediol, and cyclohexanediol; bisphenol A diglycidyl ethers; bisphenol F diglycidyl ethers; diglycidyl o-phthalate, diglycidyl isophthalate, and diglycidyl terephthalate; polyalkylene glycol diglycidyl ethers, particularly polypropylene glycol diglycidyl ether; and polycarbonate diol glycidyl ethers. Other suitable diepoxides that may also be mentioned include: diepoxides of doubly unsaturated fatty acid C1-C18 alkyl esters; butadiene diepoxide; polybutadiene diglycidyl ether; vinylcyclohexene diepoxide; and limonene diepoxide.

[0059] Further exemplary polyepoxide compounds include, but are not limited to: glycerol polyglycidyl ether; trimethylolpropane polyglycidyl ether; pentaerythritol polyglycidyl ether; diglycerol polyglycidyl ether; polyglycerol polyglycidyl ether; and sorbitol polyglycidyl ether.

[0060] The glycidyl esters of polycarboxylic acids having utility in the present invention are derived from polycarboxylic acids containing at least two carboxylic acid groups and no other groups reactive with epoxide groups. The polycarboxylic acids can be aliphatic, cycloaliphatic, aromatic, and heterocyclic. Preferred polycarboxylic acids are those containing 18 or fewer carbon atoms per carboxylic acid group, and suitable examples thereof include, but are not limited to, oxalic acid; sebacic acid; adipic acid; succinic acid; pimelic acid; suberic acid; glutaric acid; dimer and trimer acids of unsaturated fatty acids, such as the dimer and trimer acids of linseed fatty acid; phthalic acid; isophthalic acid; terephthalic acid; trimellitic acid; trimesic acid; phenylene-diacetic acid; chlorendic acid; hexahydrophthalic acid, particularly hexahydroorthophthalic acid (1,2-cyclohexanedicarboxylic acid); diphenic acid; naphthalic acid; polyacid-terminated esters of dibasic acids and aliphatic polyols; polymers and copolymers of (meth)acrylic acid; and crotonic acid.

[0061] Examples of highly preferred polyepoxide compounds include bisphenol A epoxy resins such as DER™ 331, DER™ 332, DER™ 383, JER™ 828, and Epotec YD 128; bisphenol F epoxy resins such as DER™ 354; bisphenol A / F epoxy resin blends such as DER™ 353; aliphatic glycidyl ethers such as DER™ 736; polypropylene glycol diglycidyl ethers such as DER™ 732; solid bisphenol A epoxy resins such as DER™ 661 and DER™ 664. UE; solutions of bisphenol A solid epoxy resins, such as DER™ 671-X75; epoxy novolac resins, such as DEN™ 438; brominated epoxy resins, such as DER™ 542; castor oil triglycidyl ethers, such as ERISYS™ GE-35H; polyglycerol-3-polyglycidyl ethers, such as ERISYS™ GE-38; sorbitol glycidyl ethers, such as ERISYS™ GE-60; and bis(2,3-epoxypropyl)cyclohexane-1,2-dicarboxylate, available as Lapox Arch-11.

[0062] Although not representing a preferred embodiment, the present invention does not exclude curable compositions further comprising one or more cyclic monomers selected from the group consisting of oxetanes, cyclic carbonates, cyclic anhydrides, and lactones. The disclosures of the following references may be useful in disclosing suitable cyclic carbonate-functional compounds: U.S. Pat. No. 3,535,342; U.S. Pat. No. 4,835,289; U.S. Pat. No. 4,892,954; British Patent No. GB-A-1,485,925; and EP-A-0119840. However, such cyclic comonomers should constitute less than 20 wt. %, preferably less than 10 wt. % or less than 5 wt. % of the total weight of the epoxide compounds.

[0063] b) Internally flexible epoxy resin The composition includes at least one internally flexibilized epoxy resin, which should desirably have an epoxide equivalent weight of 200 to 2500 g / eq, for example, 200 to 600 g / eq. While not intending to limit the invention, the composition preferably contains 1 to 30 wt. %, preferably 5 to 30 wt. %, more preferably 10 to 25 wt. % of the internally flexibilized epoxy resin, based on the weight of the composition.

[0064] In a first preferred embodiment, the composition comprises an internally flexibilized epoxy resin having the general formula (II): TIFF0007809055000003.tif64143In the formula, R represents a C1-C6 alkyl group or -CH2OR', and R' represents a C1-C 18 represents a hydrocarbyl group, and m and n are independently an integer of 0 or more, and (m+n) is an integer of 1 to 6, for example, 1 to 3.

[0065] The C1-C 18 The hydrocarbyl group (R') may be an aliphatic, alicyclic, aromatic or araliphatic group, examples of which include C-C 10 , in particular C1-C6 alkyl groups; C2-C4 alkenyl groups; C5-C7 cycloalkyl groups; C6-C 18 aryl groups; and C7-C 10 Aralkyl groups are mentioned. Note that when R is -CH2OR', the condition m=n=1 is preferred.

[0066] The diepoxide compound represented by formula (II) used in the present invention is i) Bisphenol A is reacted with the compound of the following formula (III) adding a compound represented by formula TIFF0007809055000004.tif2458, wherein R is as defined above; and ii) by epoxidizing the adduct with an epihalohydrin such as epihalohydrin.

[0067] Preferred embodiments of compounds of formula (II) include: 1,2-alkylene oxides, such as 1,2-propylene oxide and 1,2-butylene oxide; alkyl glycidyl ethers, such as isopropyl glycidyl ether, butyl glycidyl ether and 2-ethylhexyl glycidyl ether; alkenyl glycidyl ethers, such as vinyl glycidyl ether and allyl glycidyl ether; cycloalkyl glycidyl ethers, such as cyclopentyl glycidyl ether and cyclohexyl glycidyl ether; and allyl glycidyl ethers, such as phenyl glycidyl ether and p-sec-butyl glycidyl ether.

[0068] In a second embodiment, the composition comprises an internally flexibilized epoxy resin having the general formula (IV): TIFF0007809055000005.tif5376 wherein n and o are the same or different and are independently selected from 1 to 10. In one embodiment, n and o are independently selected from 2 to 8, for example, 4 to 8.

[0069] Representative examples of commercially available resins suitable for use in the present invention are: DER 732 available from Dow Chemical; Epo-Tek 310A available from Epoxy Technology; XB-4122, PY-322, and PY-4122US available from Ciba-Geigy; WC-68 available from Wilmington Chemical; Anthiol R-12 available from Pacific Anchor; and NC-514 and NC-514S available from Cardiolite.

[0070] Optional additional epoxy resins: chelate-modified epoxy resins To help improve adhesion of the cured composition to substrate surfaces, particularly metal substrate surfaces contaminated with oily materials commonly encountered in vehicles and other mechanical assembly operations, the composition may include at least one chelate-modified epoxy resin, which desirably should have an epoxide equivalent weight of 150 to 500 g / eq, e.g., 150 to 300 g / eq, is the reaction product of an epoxy resin and a compound containing a chelating functionality.

[0071] Chelating functional groups include functional groups that can form chelate bonds with divalent or polyvalent metal atoms, either by themselves or in cooperation with other functional groups located on the same molecule. While not intended to limit the invention, suitable chelating functional groups include: phosphorus-containing acid groups, such as PO(OH)2; carboxylic acid groups (-CO2H); sulfur-containing acid groups, such as SO3H; amino groups; and hydroxyl groups, especially hydroxyl groups located adjacent to each other on an aromatic ring.

[0072] Preparation of such reaction products can be carried out by methods known in the art. Useful references in this regard include: U.S. Pat. No. 4,702,962; U.S. Pat. No. 4,340,716; EP 342035; JP 58-063758; and JP 58-069265.

[0073] Reaction products of epoxy resins and compounds containing chelating functionality are also available from commercial sources, such as ADEKA Resins EP-49-10N, EP-49-55C, EP-49-10, EP-49-20, EP-49-23, and EP-49-25, available from Asahi Denka.

[0074] When present, the composition of the present invention should contain up to 10% by weight, especially up to 5% by weight, of said chelate-modified epoxy resin, based on the weight of the composition.

[0075] Optional further epoxy resins: elastomer-modified epoxy resins In some embodiments, the composition of the present invention may further comprise an elastomer-modified epoxy resin. In particular, the composition may be characterized by comprising 0 to 10 wt. %, e.g., 0-5 wt. %, of an elastomer-modified epoxy resin, the elastomer-modified epoxy resin having an epoxide equivalent weight of 200-2500 g / eq, e.g., 200-600 g / eq.

[0076] The elastomer modification of the epoxy resin (hereinafter referred to as E1) can be carried out by any suitable method known to those skilled in the art, but is generally carried out by a catalytic addition reaction between the functional groups of the modifier (hereinafter referred to as M1) and the oxirane groups of the epoxy resin (E1). Such an addition reaction can be carried out in a suitable solvent under at least one of the following conditions: i) a temperature of 40°C to 200°C; ii) a reaction duration of 0.5 to 5 hours; and iii) catalysis. Exemplary catalysts include tertiary amine catalysts, such as tributylamine; quaternary ammonium salts, such as tetrabutylammonium chloride; tertiary phosphates, such as triphenylphosphate; quaternary phosphonium salts, such as ethyltriphenylphosphonium iodide (ETPPI); metal salts, such as AMC-2 (chromium octoate salt); and combinations of these catalysts to carry out a stepwise addition reaction.

[0077] The epoxy resin (E1) to be modified has a 1,2-epoxy equivalent of more than 1, preferably at least 2. The epoxy resin (E1) can be linear or branched, saturated or unsaturated, aliphatic, cycloaliphatic, aromatic, or heterocyclic. Examples of epoxy resins (E1) include polyglycidyl ethers of polyhydric compounds; brominated epoxies; epoxy novolac or similar polyhydroxyphenolic resins; polyglycidyl ethers of glycols or polyglycols; and polyglycidyl esters of polycarboxylic acids. It is preferred to use polyglycidyl ethers of polyhydric phenols as the epoxy resin (E1).

[0078] The functionalized modifier (M1) is functionalized either terminally or non-terminally with a group reactive with the oxirane group of the epoxy resin (E1). Suitable functional groups include, but are not limited to, carboxyl, amino, hydroxyl, epoxy, mercaptan, anhydride, and isocyanate. Furthermore, the modifier (M1) can be a functionalized homopolymer or a functionalized random, block, or star copolymer.

[0079] In an important embodiment, the functional modifier (M1) used to modify the epoxy resin (E1) is a functional terminal diene-containing polymer having the general formula: XBX Wherein: B is: C4-C 10 Diene; C4-C 10 a diene and at least one vinyl aromatic monomer, such as styrene, C1-C6 alkyl-substituted styrene or halogen-substituted styrene; C4-C 10 a diene and at least one vinyl nitrile monomer, such as acrylonitrile or methacrylonitrile; C4-C 10 a diene, at least one vinyl nitrile monomer and at least one vinyl aromatic monomer; or C4-C 10 a diene, at least one vinyl nitrile monomer and a compound of formula CH2=CR-COOR 1 (Wherein R and R 1 are each independently hydrogen or C1-C 10 an acrylate of a methyl group selected from alkyl groups; X can be any functional group capable of reacting with an oxirane group, suitable examples of which include carboxy, amino, hydroxyl, epoxy, mercaptan, anhydride, and isocyanate groups.

[0080] As a reactant modifier (M1), the functional terminal diene-containing polymer should typically be characterized by a functionality of 1.1 to 2.5, for example 1.5 to 2.5 or 1.6 to 2.4. Apart from that, it is not excluded that the polymer backbone (X) is partially hydrogenated.

[0081] As non-limiting examples, the functional terminal diene-containing polymer (M1) may be selected from: carboxyl-terminated polybutadiene; carboxyl-terminated poly(butadiene-acrylonitrile); and carboxyl-terminated poly(butadiene-acrylonitrile-acrylic acid).

[0082] As a preferred modifier (M1), carboxyl-terminated poly(butadiene-acrylonitrile) (CTBN), especially carboxyl-terminated poly(butadiene-acrylonitrile) (CTBN) composed of 5 to 30% by weight of acrylonitrile and 70 to 95% by weight of butadiene, may be mentioned. Regardless of or in addition to this composition, the carboxyl-terminated poly(butadiene-acrylonitrile) (CTBN) should have a number-average molecular weight (Mn) of 1,000 to 50,000 g / mol, for example, 2,000 to 10,000 g / mol. Furthermore, the carboxyl-terminated poly(butadiene-acrylonitrile) is not precluded from including other functional groups, such as amino, phenolic, hydroxyl, epoxy, mercaptan, or anhydride groups, pendant to the chain in addition to the terminal carboxyl groups.

[0083] In addition to functional terminal diene-containing polymers, the use of diene-containing polymers that are non-terminally functionalized along the chain backbone can be useful in some embodiments. Such functionalized polymers (M1) can include, by way of example, carboxylated polybutadiene; carboxylated poly(butadiene-styrene); midblock carboxylated poly(styrene-ethylene / butadiene-styrene); amidated poly(butadiene-styrene); mercapto-polybutadiene; epoxidized polybutadiene; and epoxidized poly(butadiene-styrene).

[0084] In a further embodiment of the present invention, the composition is characterized in that the at least one elastomer-functionalized epoxy resin comprises or consists of at least one urethane-modified epoxy resin. In this embodiment, the functionalizing modifier (M1) used to modify the epoxy resin (E1) is an isocyanate-terminated urethane prepolymer obtained by reacting a polyisocyanate compound (I) with a polyhydroxyl compound (P). While not intending to limit this embodiment, the urethane prepolymer (M1) should be characterized by i) an NCO content of 5 to 30% by weight, preferably 10 to 25% by weight, based on the prepolymer, and ii) a functionality of 1.1 to 2.5. These characteristic properties can be found in known, commercially available prepolymers. Alternatively, components (I) and (P) may be reacted in a ratio and under conditions such that these properties of the resulting prepolymer are achieved.

[0085] The polyisocyanate (I) used to prepare the prepolymer (M1) can be any aliphatic, cycloaliphatic, arylaliphatic, heterocyclic, or aromatic polyisocyanate, or mixtures thereof, having an average isocyanate functionality of at least 2.0 and an equivalent weight of at least 80. The isocyanate functionality of the polyisocyanate (I) is more typically 2.2 to 4.0, e.g., 2.3 to 3.5. Functionalities greater than 4.0 may be used, but their use may result in excessive crosslinking. The equivalent weight of the polyisocyanate is typically 100 to 300, preferably 110 to 250, and more preferably 120 to 200.

[0086] The polyisocyanates may, if desired, be biuretized and / or isocyanated by commonly known methods, such as those described in British Patent No. 889,050.

[0087] Examples of suitable polyisocyanates (I) are ethylene diisocyanate; 1,4-tetramethylene diisocyanate; hexamethylene diisocyanate (HDI); biuret or trimer of HDI; 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate and mixtures of these isomers; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; 2,4- and 2,6-hexahydrotolylene diisocyanate and mixtures of these isomers; hexahydrol, 3- and / or 1,4-phenylene diisocyanate; perhydrol. 2,4- and 2,6-tolylene diisocyanate and mixtures of these isomers; diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI); naphthylene-1,5-diisocyanate; triphenylmethane-4,4',4'-triisocyanate; and polyphenylpolymethylene polyisocyanates of the type obtained by condensation of aniline with formaldehyde followed by phosgenation, as described, for example, in British Patents Nos. 874,430 and 848,671. It should be noted that diisocyanates and / or polyisocyanates containing ester, urea, allophanate, carbodiimide, uretdione and / or urethane groups may also be used in the process according to the invention.

[0088] The polyhydroxyl compound (P) used to derive the urethane prepolymer (M1) should typically have a number average molecular weight (Mn) of 400 to 10,000 g / mol. The hydroxyl value of the polyhydroxyl compound (P) should typically be 20 to 850 mg KOH / g, preferably 25 to 500 mg KOH / g. Furthermore, the polyhydroxyl compound (P) is preferably selected from the group consisting of dihydric or polyhydric polyether polyols, polyester polyols, poly(ether-ester) polyols, poly(alkylene carbonate) polyols, hydroxyl-containing polythioethers, polymer polyols, and mixtures thereof.

[0089] Although low-molecular-weight diols and triols, e.g., 60 to 400 or 300 g / mol, can be reactive with isocyanates (I), these polyols are typically used solely as starter molecules, chain extenders, and / or crosslinkers in reaction mixtures containing one or more active hydrogen compounds (P). In this regard, mention may be made of aliphatic, cycloaliphatic, and / or araliphatic diols having 2 to 14, preferably 4 to 10, carbon atoms, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, o-, m-, and p-dihydroxycyclohexane; diethylene glycol; dipropylene glycol; bis(2-hydroxyethyl)hydroquinone; and triols, such as 1,2,4- and 1,3,5-trihydroxycyclohexane, glycerol, and trimethylolpropane.

[0090] Polyether polyols are well known in the art and include polyoxyethylene, polyoxypropylene, polyoxybutylene, and polytetramethylene ether diols and triols. Polyether polyols generally have a weight average molecular weight (Mw) of 400 to 10,000 g / mol, for example, 1,000 to 7,000 g / mol, and can be prepared by polymerizing alkylene oxides in the presence of active hydrogen-containing initiator compounds, as described, for example, in U.S. Pat. Nos. 4,269,9945, 4,218,543, and 4,374,210. The alkylene oxide monomers are typically selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, epibromohydrin, and mixtures thereof. The active hydrogen initiator is then typically selected from the group consisting of: water; ethylene glycol; propylene glycol; butanediol; hexanediol; glycerin; trimethylolpropane; pentaerythritol; hexanetriol; sorbitol; sucrose; hydroquinone; resorcinol; catechol; bisphenol; novolac resin; phosphoric acid; amines; and mixtures thereof.

[0091] As is known in the art, polyester polyols can be prepared by reacting a polycarboxylic acid or its anhydride with a polyhydric alcohol. Examples of suitable polycarboxylic acids include succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, maleic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, maleic anhydride, glutaric anhydride, fumaric acid, and mixtures thereof. Examples of polyhydric alcohols useful in preparing polyester polyols include ethylene glycol, propanediol, butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, glycerol, trimethylolpropane, pentaerythritol, quinitol, mannitol, sorbitol, methylglycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, polypropylene glycol, and mixtures thereof. For the purposes of the present invention, useful polyester polyols typically have a weight average molecular weight (Mw) of 1,000 to 10,000 g / mol.

[0092] In one embodiment of the present invention, the reactant polyhydroxyl compound (P) has an average functionality of at least 1.5, preferably at least 1.8, more preferably at least 2.0, but not more than 4.0, preferably not more than about 3.5, more preferably not more than 3.0. Independently or in addition, the equivalent weight of the reactant polyhydroxyl compound (P) is at least 200 g / eq, preferably at least 500 g / eq, more preferably at least 1,000 g / eq, but not more than 3500 g / eq, preferably not more than 3000 g / eq, more preferably not more than 2500 g / eq.

[0093] Starting with the components (P) and (I) defined above, the polyurethane prepolymer (M1) can be prepared under anhydrous conditions by any suitable method, such as bulk polymerization and solution polymerization. The polyhydroxyl compound (P) is present in an amount sufficient to react with most of the isocyanate groups therein, while leaving sufficient isocyanate groups to correspond to the desired free isocyanate content of the urethane prepolymer (M1). In embodiments in which the polyhydroxyl compound (P) comprises a mixture of diols and triols, the ratio of diol to triol must be selected to achieve the desired isocyanate functionality of the urethane prepolymer (M1).

[0094] In a further preferred embodiment of the present invention, the composition is characterized in that the at least one elastomer-functionalized epoxy resin b) comprises or consists of at least one dimer acid-modified epoxy resin. The dimer acid modifier (M1) can be cyclic or acyclic, but is conventionally a C36-C44 aliphatic diacid that can be prepared by oxidative coupling of C18-C22 unsaturated monoacids. Dimer acids obtained from the oxidative coupling of oleic acid, linoleic acid, or tall oil fatty acid can be mentioned as exemplary dimer acid modifiers (M1).

[0095] In view of the preferred embodiments discussed hereinabove, commercially available examples of suitable elastomer-modified epoxy resins include: Hypox® resins, including Hypox DA 323, available from CVC Thermosets; EPON 58005 and EPON 58034, available from Miller-Stephenson; JER871 and JER872, available from Mitsubishi Chemical Corporation; B-Tough A1, A2, and A3, available from Croda Coatings and Polymers; YD-171 and YD-172, available from Nippon Steel Chemical Co., Ltd.; and EPU-6, EPU-7N, EPU-11F, EPU-15F, EPU-1395, EPU-738, EPU-17, EPU-17T-6, and EPU-80, available from ADEKA Corporation.

[0096] c) Core-shell rubber particles The composition is defined as comprising 1 to 40 wt. %, preferably 1 to 35 wt. %, more preferably 5 to 30 wt. % of c) core-shell rubber particles, based on the weight of the composition.

[0097] The term "core-shell rubber" or CSR is used in accordance with its standard meaning in the art to refer to a rubber particle core formed from a polymer primarily containing an elastomeric or rubbery polymer, and a shell layer formed from a polymer grafted onto the core. The shell layer covers part or all of the surface of the rubber particle core in a graft polymerization process. The core should constitute at least 50% by weight of the core-shell rubber particle.

[0098] The polymer material in the core has a glass transition temperature (T g ), preferably -20°C or less, more preferably -40°C or less, even more preferably -60°C or less, g ) should be present.

[0099] The polymer of the shell has a glass transition temperature (T) above room temperature, preferably above 30°C, more preferably above 50°C. g ) is a non-elastomeric, thermoplastic or thermosetting polymer having a

[0100] Without intending to limit the invention, the core may be composed of: diene homopolymers, such as homopolymers of butadiene or isoprene; diene copolymers, such as copolymers of butadiene or isoprene with one or more ethylenically unsaturated monomers, such as vinyl aromatic monomers, (meth)acrylonitrile, or (meth)acrylates; polymers based on (meth)acrylic acid ester monomers, such as polybutyl acrylate; and polysiloxane elastomers, such as polydimethylsiloxane and crosslinked polydimethylsiloxane.

[0101] Similarly, without intending to limit the invention, the shell may be composed of a polymer or copolymer of one or more monomers selected from (meth)acrylates, such as methyl methacrylate; vinyl aromatic monomers, such as styrene; vinyl cyanides, such as acrylonitrile; unsaturated acids and anhydrides, such as acrylic acid; and (meth)acrylamide. The polymer or copolymer used in the shell may have acid groups ionically crosslinked by metal carboxylate formation, particularly by forming a salt of a divalent metal cation. The shell polymer or copolymer may also be covalently crosslinked by a monomer having two or more double bonds per molecule.

[0102] The core-shell rubber particles preferably have an average particle size (d50) of from 10 nm to 300 nm, for example from 50 nm to 200 nm; the particle size refers to the diameter or largest dimension of a particle in a distribution of particles, as measured by dynamic light scattering.

[0103] The present application does not preclude the presence of two types of core-shell rubber (CSR) particles having different particle sizes in the composition to provide a balance of important properties in the resulting cured product, including shear strength, peel strength, and resin fracture toughness. In this embodiment, the smaller encapsulated particles (first CSR type) may have an average particle size of 10 to 100 nm, and the larger encapsulated particles (second CSR type) may have an average particle size of 120 nm to 300 nm, e.g., 150 to 300 nm. The smaller core-shell rubber particles should typically be used in excess of the larger particles by weight; for example, a weight ratio of 3:1 to 5:1 smaller CSR particles to larger CSR particles may be used.

[0104] The core-shell rubber may be selected from commercially available products, examples of which include the Zefiac series available from Aica Kogyo Co., Ltd.; Paraloid EXL 2650A, EXL 2655, and EXL 2691A available from Dow Chemical Company; KaneAce® MX series from Kaneka Corporation, particularly MX 120, MX 125, MX 130, MX 136, MX 551, and MX 553; and Metablen SX-006 available from Mitsubishi Rayon.

[0105] d) Hardener The curing agent d) necessarily consists of at least one compound having at least two epoxide-reactive groups per molecule. In the present invention, the curing agent d) is characterized by including dicyandiamide. The dicyandiamide is preferably used in a finely divided form; an average particle size (d50) of 0.5 to 100 μm, for example, 1 to 50 μm or 2 to 20 μm, may be desirable. The particle size refers to the diameter or maximum dimension of the particle in the particle distribution and can be measured by dynamic light scattering.

[0106] Preferably, curing agent d) consists of or consists essentially of dicyandiamide, although the presence of other curing agents in amounts up to 20 mol % based on the total moles of dicyandiamide is not excluded by the present invention. Any selected co-curing agent d) for dicyandiamide should not adversely affect the pot life of the one-component (1K) composition.

[0107] When formulating curable compositions, the compositions as a whole are preferably characterized by a molar ratio of epoxide-reactive groups to epoxide groups of from 0.95:1 to 1.5:1, for example, from 0.95:1 to 1.1:1. In particular, a molar ratio of epoxide-reactive groups to epoxide groups of 1:1 falls within these indicated ranges and as such represents a highly preferred molar ratio.

[0108] e) Urea Derivatives as Accelerators According to an interesting embodiment of the accelerator e) of the invention, the composition comprises at least one urea derivative of formula (V) or (VI): TIFF0007809055000006.tif98129Where: at least one residue R 1 , R 2 , R 3 is not hydrogen; R 1 and R 2 are independently hydrogen, C1-C 18 Alkyl and C3-C 18 cycloalkyl; R 3 is hydrogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C6-C 18 Aryl, C6-C 18 Aralkyl, C6-C 18 Alkylaryl, -NHC(O)NR 1 R 2 C1-C substituted with 18 Alkyl, -NHC(O)NR 1 R 2 C3-C substituted with 18 Cycloalkyl, -NHC(O)NR 1 R 2 C6-C substituted with 18 Aryl; -NHC(O)NR 1 R 2 C6-C substituted with 18 aralkyl; and -NHC(O)NR 1 R 2 C6-C substituted with 18 is aralkyl; and R 4 , R 5 , R 6 , R 7 and R 8 are independently hydrogen, halogen, C1-C 18 Alkyl, C3-C 18 Cycloalkyl, C6-C 18 Aryl, C6-C 18 Aralkyl, C6-C 18-Alkylaryl, -CF3, -NHC(O)NR 1 R 2 , -NHC(O)NR 1 R 2 C1-C substituted with 18 Alkyl, -NHC(O)NR 1 R 2 C3-C substituted with 18 Cycloalkyl, -NHC(O)NR 1 R 2 C6-C substituted with 18 Aryl; -NHC(O)NR 1 R 2 C6-C substituted with 18 aralkyl; and -NHC(O)NR 1 R 2 C6-C substituted with 18 aralkyl.

[0109] The substituents (R 1 ~R 8 ) should be selected to ensure that the derivative is liquid at room temperature and 1 atmosphere and has a viscosity of less than 1 Pa.s, preferably less than 100 mPa.s at 25° C. In addition to these considerations, it is preferred that the urea derivatives of formulae (V) and (VI) satisfy the following conditions: At least one residue R 1 , R 2 , R 3 is not hydrogen; R 1 and R 2 is independently selected from hydrogen and C1-C4 alkyl; and R 4 , R 5 , R 6 , R 7 and R 8 are independently hydrogen, halogen, C1-C4 alkyl, and -NHC(O)NR 1 R 2 is selected from.

[0110] It may be noted that the use of N,N-diethylurea, N,N-dipropylurea, N,N-ethyl-methylurea, N,N-dimethylurea, 1,1'-(4-methyl-m-phenylene)-bis-(3,3-dimethylurea) and 1,1'-(2-methyl-m-phenylene)-bis-(3,3-dimethylurea) is particularly preferred.

[0111] When the urea is used as an accelerator, it is essential that the molar ratio of dicyandiamide to the total of the urea derivatives is 1 or more, and the molar ratio of dicyandiamide to the total of the urea derivatives is preferably in the range of 1:1 to 4:1, for example, 1:1 to 3:1.

[0112] f) Additives and auxiliary ingredients The compositions obtained by the present invention typically further contain adjuvants and additives that can impart improved properties to these compositions. For example, the adjuvants and additives can impart one or more of: improved elastic properties; improved elastic recovery; longer effective processing time; faster cure time; and lower residual tack. Such adjuvants and additives can include catalysts, plasticizers, coupling agents, adhesion promoters, stabilizers including UV stabilizers, antioxidants, secondary tougheners, fillers, reactive diluents, drying agents, fungicides, flame retardants, rheological aids, color pigments or color pastes, and / or optionally minor amounts of non-reactive diluents.

[0113] Suitable catalysts are materials that promote the reaction between an epoxide group and an epoxide-reactive group, such as the reaction between an amine group and an epoxide group. A specific example relates to the use of amine catalysts that function by deprotonating any reactive thiol (-SH) groups present to thiolate (-S") groups that react with the epoxide group by nucleophilic ring-opening polymerization.

[0114] Although it is not intended to limit the catalysts used in the present invention, the following are suitable catalysts: i) acids or compounds hydrolyzable by acids, in particular a) organic carboxylic acids such as acetic acid, benzoic acid, salicylic acid, 2-nitrobenzoic acid, and lactic acid; b) organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid, and 4-dodecylbenzenesulfonic acid; c) sulfonic acid esters; d) inorganic acids such as phosphoric acid; e) Lewis acid compounds such as BF3 amine complexes, SbF6 sulfonium compounds, bis-arene iron complexes; f) Bronsted acid compounds such as pentafluoroantimonate complexes; and e) mixtures of the aforementioned acids and acid esters; ii) tertiary amines such as 1,4-diazabicyclo[2.2.2]octane. , benzyldimethylamine, α-methylbenzyldimethylamine, triethanolamine, dimethylaminopropylamine, imidazoles—including N-methylimidazole, N-vinylimidazole and 1,2-dimethylimidazole—and the salts of such tertiary amines; iii) quaternary ammonium salts, such as benzyltrimethylammonium chloride; iv) amidines, such as 1,8-diazabicyclo[5.4.0]undec-7-ene; v) guanidines, such as 1,1,3,3-tetramethylguanidine; vi) phenols, in particular bisphenols; vii) phenolic resins; viii) Mannich bases; and ix) phosphites, such as diphenyl and triphenyl phosphite.

[0115] In one embodiment, the amine catalyst for curing epoxy resin-based compositions may be a photobase generator: upon exposure to UV radiation—typically at wavelengths of 320 to 420 nm—the photobase generator releases an amine that catalyzes the addition of an epoxide-reactive group to an epoxide. The photobase generator is not particularly limited, as long as it generates an amine directly or indirectly upon irradiation with light. However, suitable photobase generators that may be mentioned include: benzyl carbamate; benzoin carbamate; o-carbamoylhydroxyamine; O-carbamoyloxime; aromatic sulfonamides; alpha-lactams; N-(2-allylethenyl)amides; aryl azide compounds, N-arylformamides, and 4-(ortho-nitrophenyl)dihydropyridine.

[0116] For completeness, the preparation of photobase generator compounds is known in the art, and useful references include: J. Cameron et al., J. Am. Chem. Soc, Vol. 113, No. 11, 4303-4313 (1991); J. Cameron et al., J. Polym. Mater. Sci. Eng., 64, 55 (1991); J. Cameron, et al., J. Org. Chem., 55, 5919-5922 (1990); and US Pat. No. 5,650,261 (Winkel). Furthermore, photobase generators are further described in: M. Shirai et al., Photochemical Reactions of Quatenary Ammonium Dithiocarbamates as Photobase Generators and Their Use in The Photoinitiated Thermal Crosslinking of Poly(gycidylmethacrylate), Journal of Polymer Science, Part A: Polymer Chemistry, Vol. 39, pp. 1329-1341 (2001); and M. Shirai et al., Photoacid and photobase generators: chemistry and applications to polymeric materials, Progress in Polymer Science, Vol. 21, pp. 1-45, XP-002299394, 1996.

[0117] In an alternative embodiment, the acid catalyst may be selected from photoacid generators (PAGs): upon irradiation with light energy, ionic photoacid generators undergo a fragmentation reaction to release one or more molecules of Lewis or Bronsted acids that catalyze the ring-opening and addition of pendant epoxide groups to form crosslinks. Useful photoacid generators are thermally stable, do not undergo heat-induced reactions with the forming copolymer, and are readily dissolved or dispersed in the curable composition. Photoacid generators are known in the art; see, for example, K. Dietliker, Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints, Vol. 11, SITA Technology Ltd., London (1991); and Kirk-Othmer Encyclopedia of Chemical Technology, 4. Sup. th Edition, Supplement Volume, John Wiley and Sons, New York, pp. 253-255.

[0118] Exemplary cations that can be used as the cationic moiety of the ionic PAGs of the invention include organic onium cations such as those described in U.S. Patent Nos. 4,250,311, 3,113,708, 4,069,055, 4,216,288, 5,084,586, 5,124,417, and 5,554,664. These references specifically encompass aliphatic or aromatic Group IVA and Group VIIA (CAS-type)-centered onium salts, with I-, S-, P-, Se-N-, and C-centered onium salts being preferred, such as those selected from sulfoxonium, iodonium, sulfonium, selenonium, pyridinium, carbonium, and phosphonium.

[0119] As is known in the art, the nature of the counteranion in an ionic photoacid generator (PAG) can affect the rate and extent of cationic addition polymerization of epoxide groups. For illustrative purposes, Crivello et al., Chem. Mater., 4, 692, (1992) reported that the order of reactivity among commonly used nucleophilic anions is SbF > AsF > PF > BF. The influence of the anion on reactivity is due to three fundamental factors that those skilled in the art must account for in this invention: (1) the acidity of the generated protonic or Lewis acid; (2) the degree of ion pair separation in the growing cationic chain; and (3) the susceptibility of the anion to fluoride abstraction and resulting chain termination.

[0120] It is not excluded that the compositions of the present invention contain alternative photoinitiator compounds to the photobase generator and photoacid generator compounds mentioned above, which initiate polymerization or curing of the composition upon exposure to actinic radiation. It should be noted that the photopolymerizable compositions of the present invention can be cationically polymerizable or free-radically polymerizable: although epoxy groups are cationically active, selecting a free-radical polymerization mechanism imposes the requirement that the composition contain a compound with a free-radically active unsaturated group, such as an acrylate compound, a (meth)acrylate compound, an epoxy-functional acrylate, an epoxy-functional (meth)acrylate, or a combination thereof. Applying this option, preferred photoinitiators are photoactive compounds that undergo Norrish I cleavage to generate free radicals that can be initiated by addition to an acrylic double bond.

[0121] The photoinitiator as a whole should be present in the photopolymerizable composition in an amount of 0.1 to 1.0 parts by weight per 100 parts of reactive compounds.

[0122] The use of photoinitiators and the photobase and photoacid generators described above may generate residual compounds from the photochemical reaction. The residues can be detected by conventional analytical techniques, such as infrared, ultraviolet, and NMR spectroscopy; gas or liquid chromatography; and mass spectrometry. Thus, the present invention may contain detectable amounts of residues from the cured (epoxy) matrix copolymer and the photobase / acid generator. Such residues are present in small amounts and typically do not interfere with the desired physicochemical properties of the product.

[0123] Although not intended to limit the present invention, a mixture containing one or more photoinitiators may be irradiated with activating radiation to polymerize the monomer components. The purpose of irradiation is to generate active species from the photoinitiator, which initiate the curing reaction. Once the species is generated, the curing chemistry follows the same rules of thermodynamics as any chemical reaction: the reaction rate can be accelerated by heat. The practice of using thermal treatment to enhance cationic UV curing of monomers is generally known in the art; an exemplary useful reference is Crivello et al., "Dual Photo- and Thermally Initiated Cationic Polymerization of Epoxy Monomers," Journal of Polymer Science A, Polymer Chemistry, Vol. 44, Issue 23, pp. 6750-6764, (Dec. 1, 2006).

[0124] As will be appreciated by those skilled in the art, photosensitizers can be included in the composition to improve the efficiency with which any photoinitiator uses the delivered energy. Photosensitizers are typically used in amounts of 5-25% by weight of the photoinitiator.

[0125] For the purposes of the present invention, a "plasticizer" is a substance that reduces the viscosity of the composition and thus promotes its processability. Here, the plasticizer can constitute up to 10% by weight or up to 5% by weight based on the total weight of the composition, and is preferably selected from the group consisting of: polydimethylsiloxane (PDMS); diurethane; ethers of monofunctional, linear or branched C4-C16 alcohols, such as Cetiol OE (available from Cognis Deutschland GmbH, Düsseldorf); esters of abietic acid, butyric acid, thiobutyric acid, acetic acid, propionic acid and citric acid; esters based on nitrocellulose and polyvinyl acetate; fatty acid esters; dicarboxylic acid esters; esters of OH-group-bearing or epoxidized fatty acids; glycolic acid esters; benzoic acid esters; phosphate esters; sulfonic acid esters; trimellitic acid esters; epoxidized plasticizers; polyether plasticizers, such as end-capped polyethylene or polypropylene glycol; polystyrene; hydrocarbon plasticizers; chlorinated paraffins; and mixtures thereof. It should be noted that, in principle, phthalates could be used as plasticizers, but these are not preferred due to their toxicological potential. Preferably, the plasticizer comprises or consists of one or more polydimethylsiloxanes (PDMS).

[0126] In some embodiments, the composition contains up to 5 wt. % of at least one epoxy silane coupling agent, which can act to improve adhesion of the cured composition to a given surface. The hydrolyzable groups of the coupling agent can react with the surface to remove undesired hydroxyl groups; the epoxy groups react with the film-forming polymer to chemically bond the polymer to the surface. Preferably, the coupling agent has 1 to 3 hydrolyzable functional groups and at least one epoxy group.

[0127] Examples of suitable epoxy silane coupling agents include, but are not limited to, glycidoxypolymethylenetrialkoxysilanes such as 3-glycidoxy-1-propyl-trimethoxysilane; (meth)acryloxypolymethylenetrialkoxysilanes such as 3-methacrylyloxy-1-propyltrimethoxysilane; gamma-methacryloxypropyltrimethoxysilane (A-174 available from GE Silicones); gamma-glycidoxypropyltrimethoxysilane (A-187 available from Momentive Performance Materials, Inc.); alpha-glycidoxypropylmethyldiethoxysilane (A-2287 available from Momentive Performance Materials, Inc.); vinyl-tris-(2-methoxyethoxy)silane (A-172 available from Momentive Performance Materials, Inc.); and alpha-chloropropyltrimethoxysilane (KBM-703 available from Shin-Etsu Chemical Co., Ltd.).

[0128] For the purposes of the present invention, "stabilizer" should be understood as antioxidant, UV stabilizer, or hydrolysis stabilizer. Herein, the stabilizers may constitute up to 10% by weight or up to 5% by weight in total, based on the total weight of the composition. Standard commercial examples of stabilizers suitable for use herein include sterically hindered phenols; thioethers; benzotriazoles; benzophenones; benzoates; cyanoacrylates; acrylates; hindered amine light stabilizers (HALS) type amines; phosphorus; sulfur; and mixtures thereof.

[0129] As mentioned above, the compositions of the present invention can further contain fillers. Suitable fillers include, for example, chalk, lime powder, precipitated and / or calcined silicic acid, zeolite, bentonite, magnesium carbonate, diatomaceous earth, alumina, clay, talc, titanium oxide, iron oxide, zinc oxide, sand, quartz, flint, mica, glass powder, and other ground mineral substances. Organic fillers, especially carbon black, graphite, wood fiber, wood flour, sawdust, cellulose, cotton, pulp, cotton, wood chips, shredded straw, rice husks, crushed walnut shells, and other shredded fibers, can also be used. Short fibers, such as glass fiber, glass filament, polyacrylonitrile, carbon fiber, Kevlar fiber, and polyethylene fiber, can also be added. Aluminum powder is also suitable as a filler.

[0130] The calcined and / or precipitated silica is advantageously from 10 to 90 m 2 / g. When pyrogenic and / or precipitated silicas are used, they do not cause a further increase in the viscosity of the compositions according to the invention, but contribute to the strengthening of the set composition.

[0131] Similarly, as fillers, advantageously 100 to 250 m 2 / g, especially 110-170m 2 It is conceivable to use calcined and / or precipitated silicic acids with a higher BET surface area of ​​0.1g / g: due to the higher BET surface area, the effect of strengthening the setting composition is achieved with a smaller weight proportion of silicic acid.

[0132] Also suitable as fillers are hollow spheres with a mineral or plastic shell. These can be, for example, hollow glass spheres commercially available under the trade name Glass Bubbles®. Plastic hollow spheres such as Expancel® or Dualite® can also be used, as described in EP 0 520 426 B1: they are composed of inorganic or organic materials and have a diameter of 1 mm or less, preferably 500 μm or less.

[0133] Fillers that impart thixotropy to the composition may be preferred for many applications: such fillers have also been described as rheological aids, e.g., hydrogenated castor oil, fatty acid amides or swellable plastics such as PVC.

[0134] The total amount of filler present in the compositions of the present invention is preferably 0 to 60 wt.%, more preferably 0 to 30 wt.%, based on the total weight of the composition. The desired viscosity of the curable composition typically determines the total amount of filler added, and it is proposed that the curable composition should have a viscosity of 3000 to 150,000 mPas, preferably 40,000 to 80,000 mPas, or even 50,000 to 60,000 mPas, in order to be readily extrudable from a suitable dispensing device, such as a tube.

[0135] With respect to component c) above, it should be noted that other compounds having metal chelating properties may also be used in the compositions of the present invention to help improve the adhesion of the cured adhesive to the substrate surface. Also suitable for use as an adhesion promoter is the acetoacetate-functionalized modified resin sold by King Industries under the trade name K-FLEX XM-B 301.

[0136] Examples of suitable pigments are titanium dioxide, iron oxide or carbon black.

[0137] To further extend shelf life, it is often advisable to further stabilize the compositions of the present invention with respect to moisture penetration by using a desiccant. There is also sometimes a need to reduce the viscosity of the adhesive or sealant compositions of the present invention for specific applications by using a reactive diluent. The total amount of reactive diluent present is typically up to 15 wt. %, preferably 1 to 5 wt. %, based on the total weight of the composition.

[0138] The presence of a non-reactive diluent in the composition of the present invention is not excluded if it can usefully adjust its viscosity.For example, by way of example only, the composition may contain: xylene; 2-methoxyethanol; dimethoxyethanol; 2-ethoxyethanol; 2-propoxyethanol; 2-isopropoxyethanol; 2-butoxyethanol; 2-phenoxyethanol; 2-benzyloxyethanol; benzyl alcohol; ethylene glycol; ethylene glycol dimethyl ether; ethylene glycol diethyl ether; ethylene glycol dibutyl ether; ethylene glycol diphenyl ether; diethylene glycol; diethylene glycol monomethyl ether; diethylene glycol monoethyl ether; diethylene glycol mono-n-butyl ether; diethylene glycol dimethyl ether; diethylene glycol diethyl ether; diethylene glycol di-n-butyl ether; propylene glycol butyl ether ; propylene glycol phenyl ether; dipropylene glycol; dipropylene glycol monomethyl ether; dipropylene glycol dimethyl ether; dipropylene glycol di-n-butyl ether; N-methylpyrrolidone; diphenylmethane; diisopropyl naphthalene; petroleum fractions such as Solvesso® products (available from Exxon); alkylphenols such as tert-butylphenol, nonylphenol, dodecylphenol and 8,11,14-pentadecatrienylphenol; styrenated phenols; bisphenols; aromatic hydrocarbon resins, especially those containing phenolic groups, such as ethoxylated or propoxylated phenols; adipates; sebacates; phthalates; benzoates; organic phosphates or sulfonates; and sulfonamides.

[0139] Apart from the above, the non-reactive diluent preferably constitutes less than 10% by weight, in particular less than 5% or less than 2% by weight, relative to the total weight of the composition.

[0140] For the sake of completeness, the compositions of the present invention may contain one or more monoamines, such as hexylamine and benzylamine.

[0141] Exemplary embodiments of one-component (1K) compositions In an exemplary embodiment of the present invention, a one-component (1K) composition comprises, by weight of the composition: 40-60% by weight of a) at least one epoxy resin; 10 to 25 wt. % of b) at least one internally flexibilized epoxy resin characterized by a Shore D hardness of 45 or less when cured with diethylenetriamine, as measured with a durometer according to ASTM D2240; at least one chelate-modified epoxy resin, present in a total amount of up to 5 wt.%; at least one elastomer-modified epoxy resin, present in a total amount of up to 5 wt.%; 5-30 wt% of c) core-shell rubber particles; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, the curing agent consisting of dicyandiamide, the dicyandiamide having a particle morphology characterized by an average particle size (d50) of 1 to 50 μm, preferably 2 to 20 μm; and e) at least one urea derivative selected from the group consisting of N,N-diethylurea, N,N-dipropylurea, N,N-ethyl-methylurea, N,N-dimethylurea, 1,1'-(4-methyl-m-phenylene)-bis-(3,3-dimethylurea) and 1,1'-(2-methyl-m-phenylene)-bis-(3,3-dimethylurea); the composition is characterized in that the molar ratio of epoxide-reactive groups to epoxide groups provided in the curing agent d) is from 0.95:1 to 1.5:1, preferably from 0.95:1 to 1.1:1, The molar ratio of dicyandiamide to the total of the urea derivatives is in the range of 1:1 to 4:1, preferably 1:1 to 3:1.

[0142] This exemplary embodiment of the composition has been shown to form an effective bonding agent for metallic materials, including those containing metal components that are shaped and joined upon curing, even when the joined metallic materials are dissimilar from one another.

[0143] Methods and Uses To form the composition, the above parts are combined and mixed. As is known in the art, to form a one-component (1K) curable composition, the components of the composition are combined and intimately mixed under conditions that inhibit or prevent reaction of the reactive components; as will be readily understood by those skilled in the art, this may include mixing conditions that limit or prevent exposure to moisture or radiation, or that limit or prevent activation of the constituent latent catalysts. As such, it is often preferred that the curing agent components are not mixed by hand, but instead are mixed in predetermined amounts by machine, e.g., a static or dynamic mixer, under anhydrous conditions without intentional light exposure.

[0144] According to the broadest method aspect of the present invention, the above-described composition is applied to a substrate and then cured in situ. Prior to applying the composition, it is often advisable to pretreat the relevant surface to remove foreign matter therefrom; this step, if applicable, can promote subsequent adhesion of the composition to the surface. Such treatments are known in the art and can be carried out in a single or multi-step manner, for example, by using one or more of: etching with an acid and optionally an oxidizing agent suitable for the substrate; ultrasonic treatment; plasma treatment, including chemical plasma treatment, corona treatment, atmospheric plasma treatment, and flame plasma treatment; immersion in an aqueous alkaline degreasing bath; treatment with an aqueous cleaning emulsion; treatment with a cleaning solvent, such as carbon tetrachloride or trichloroethylene; and water rinsing, preferably with deionized or demineralized water. If an aqueous alkaline degreasing bath is used, any degreaser remaining on the surface should desirably be removed by rinsing the substrate surface with deionized or demineralized water.

[0145] In some embodiments, the adhesion of the coating composition of the present invention to the substrate, preferably pretreated, can be promoted by applying a primer to the substrate.Those skilled in the art can select suitable primer, and useful references for primer selection include but are not limited to United States Patent No. 3,671,483; United States Patent No. 4,681,636; United States Patent No. 4,749,741; United States Patent No. 4,147,685; and United States Patent No. 6,231,990.

[0146] The composition is then applied to the preferably pretreated and optionally primed surface of the substrate by conventional application methods, such as brushing; roll coating, e.g., using a four-roll application apparatus when the composition is solvent-free or a two-roll application apparatus for solvent-borne compositions; doctor blade application; printing; and spraying, including, but not limited to, air-atomized spraying, air-assisted spraying, airless spraying, and high-volume, low-pressure spraying. For coating and adhesive applications, it is recommended that the composition be applied to a wet film thickness of 10 to 500 μm. Applying thinner layers within this range is more economical and reduces the likelihood of thick cured areas that may require sanding for coating applications. However, great care must be exercised when applying thinner coatings or layers to avoid the formation of discontinuous cured films.

[0147] Curing of the compositions of the present invention can be carried out at temperatures ranging from 100°C to 200°C, preferably from 100°C to 170°C, and especially from 120°C to 160°C. The suitable temperature will depend on the particular compounds present and the desired cure rate and can be determined in each case by those skilled in the art, using simple preliminary tests if necessary. However, where applicable, the temperature of the mixture formed from the individual components of the composition can be raised above the mixing and / or application temperatures using conventional means, including microwave induction.

[0148] For completeness, it should be noted that the present invention does not exclude the preparation of epoxy adhesives in the form of "film adhesives." A prepolymer mixture of epoxy resin, hardener, and other desired components is applied as a coating onto a polymer film substrate, rolled up, and stored at a temperature low enough to inhibit chemical reaction between the components. When required, the film adhesive is removed from the cold environment, applied to a metal or composite part, the backing is peeled off, the assembly is completed, and cured in an oven or autoclave.

[0149] The curable compositions according to the present invention may find utility in, inter alia: varnishes; inks; binders for fibers and / or particles; coatings for glass; coating and bonding inorganic building materials such as lime and / or cement-bonded gypsum, gypsum-containing surfaces, fiber cement building materials and concrete; coating, sealing or bonding wood and wood-based materials such as chipboard, fiberboard and paper; coating or bonding metal surfaces; coating asphalt and bitumen-containing pavements; coating, sealing or bonding various plastic surfaces; and coating leather and textiles.

[0150] In a particularly preferred embodiment, the compositions of the present invention are applied to structural substrates to produce adherent, highly abrasion-resistant coatings or bonds. Bonding operations can often be performed at temperatures below 200°C, achieving effective abrasion resistance after curing. Furthermore, when bonding to mechanical structural surfaces or floors or pavements, the coating compositions can provide strong, reliable bonds, impart thermal stability and corrosion protection to the surfaces, and prevent contact of the surfaces with compounds harmful to the operation or efficiency of the particular structure.

[0151] The following examples are illustrative of the present invention and are not intended to limit the scope of the invention in any way. [Example]

[0152] The following compounds and materials are used in the examples. JER™ 828: Bisphenol A, a liquid epoxy resin formed by the condensation polymerization of bisphenol A and epichlorohydrin, available from Mitsubishi Chemical. DER™ 332: Bisphenol A epoxy resin, supplied by Olin Corporation. KanAce MX 154: Bisphenol A epoxy resin premixed with toughening agents, available from Kaneka Corporation. Acryset BPA 328: Bisphenol A epoxy resin premixed with toughening agents, available from Nippon Shokubai Co., Ltd. EP-49-10 N: Chelate modified epoxy resin with epoxide equivalent weight of 220, available from ADEKA Corporation. NC-514 S: A hydrophobic, flexible, difunctional glycidyl ether epoxy resin with an epoxide equivalent weight of 350-500, available from Cardolite. Silquest A-187: A silane coupling agent, available from Momentive Performance Chemicals. 90-EPX-04: Carbon black, available from Harwick Chemical. Zefiac 351: Core-shell rubber particles, available from Aica Kogyo Co., Ltd. DAW 7: Alumina, available from Denka Co., Ltd. Aerosil R202: Fumed silica, available from Evonik Corporation. CG 1200 G: Dicyandiamide (cyanoguanidine), available from Evonik Corporation. Amicure UR2T: Substituted urea accelerator [1,1'-(4 methyl-m-phenylene)bis(3,3 dimethylurea)], available from Evonik Corporation.

[0153] The ingredients were combined in the percentages shown in Table 1 herein below. [Table 1]

[0154] Viscosity and lap shear strength measurements were obtained according to the protocols described above and the results are recorded herein below in Table 2. Further testing was performed as follows.

[0155] <Differential Scanning Calorimetry (DSC) Curing Test> A sample of Example 1 was selected and tested by DSC isothermal method. More specifically, 10.0 mg samples of the composition were individually weighed on a milligram balance, sealed in a sealed aluminum DSC pan, and loaded into a Perkin Elmer Diamond DSC analyzer along with an identical empty pan to serve as a reference. The exotherm was measured at a set temperature of 140°C for 60 minutes. The curing behavior was analyzed from the resulting thermograph, and the curing time at 95% conversion at 140°C was determined and recorded in Table 2 herein below. [Table 2]

[0156] In view of the foregoing description and examples, it will be apparent to one skilled in the art that equivalent modifications can be made without departing from the scope of the claims. Preferred aspects of the present invention include the following. [1] a) at least one epoxy resin; b) at least one internally flexibilized epoxy resin characterized by a Shore D hardness of 45 or less when cured with diethylenetriamine, as measured with a durometer according to ASTM D2240; c) core-shell rubber particles; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, characterized in that the curing agent comprises dicyandiamide; and e) at least one accelerator A one-component (1K) composition comprising: [2] The composition according to [1], comprising 20 to 70% by weight of a) the at least one epoxy resin, based on the weight of the composition. [3] The composition according to [1] or [2], wherein the at least one epoxy resin is selected from: glycidyl ethers of polyhydric alcohols and polyhydric phenols; glycidyl esters of polycarboxylic acids; and epoxidized polyethylenically unsaturated hydrocarbons, esters, ethers, and amides. [4] The composition according to any one of [1] to [3], wherein the internally flexible epoxy resin has an epoxide equivalent weight of 200 to 600 g / eq. [5] The composition according to any one of [1] to [4], wherein the internally flexible epoxy resin, when cured with diethylenetriamine, has a Shore D hardness of 40 or less as measured with a durometer in accordance with ASTM D2240. [6] An internally flexibilized epoxy resin having the general formula (III): JPEG0007809055000009.jpg57129 The composition according to any one of [1] to [5], wherein n and o are the same or different and independently selected from 1 to 10. [7] The composition according to any one of [1] to [6], comprising 1 to 30 wt % of the internally flexible epoxy resin relative to the weight of the composition. [8] The composition according to any one of [1] to [7], comprising c) core-shell rubber particles in an amount of 1 to 40% by weight based on the weight of the composition. [9] The composition according to any one of [1] to [8], wherein the dicyandiamide has a particle form characterized by an average particle size of 0.5 to 100 μm.

[10] e) the at least one accelerator comprises or consists of at least one urea derivative of formula (V) or formula (VI): JPEG0007809055000010.jpg97129 wherein at least one residue R 1 、R 2 、R 3 but not hydrogen; R 1 and R 2 are independently hydrogen, C 1 -C 18 Alkyl and C 3 -C 18 cycloalkyl; R 3 But hydrogen, C 1 -C 18 Alkyl, C 3 -C 18 Cycloalkyl, C 6 -C 18 Aryl, C 6 -C 18 Aralkyl, C 6 -C 18 Alkylaryl, -NHC(O)NR 1 R 2 C replaced with 1 -C 18 Alkyl, -NHC(O)NR 1 R 2 C replaced with 3 -C 18 Cycloalkyl, -NHC(O)NR 1 R 2 C replaced with 6 -C 18 Aryl; -NHC(O)NR 1 R 2 C replaced with 6 -C 18 aralkyl; and -NHC(O)NR 1 R 2 C replaced with 6 -C 18 is aralkyl; and R 4 、R 5 、R 6 、R 7 and R 8 are independently hydrogen, halogen, C 1 -C 18 Alkyl, C 3 -C 18 Cycloalkyl, C 6 -C 18 Aryl, C 6 -C 18 Aralkyl, C 6 -C 18 -Alkylaryl, -CF 3 , -NHC(O)NR 1 R 2 , -NHC(O)NR 1 R 2 C replaced with 1 -C 18 Alkyl, -NHC(O)NR 1 R 2 C replaced with 3 -C 18 Cycloalkyl, -NHC(O)NR 1 R 2 C replaced with 6 -C18 Aryl; -NHC(O)NR 1 R 2 C replaced with 6 -C 18 aralkyl; and -NHC(O)NR 1 R 2 C replaced with 6 -C 18 The composition according to any one of [1] to [9], wherein the composition is selected from aralkyl.

[11] In the formulas (V) and (VI), At least one residue R 1 、R 2 、R 3 but not hydrogen; R 1 and R 2 are independently hydrogen and C 1 -C 4 alkyl; and R 4 、R 5 、R 6 、R 7 and R 8 are independently hydrogen, halogen, C 1 -C 4 Alkyl and -NHC(O)NR 1 R 2 The composition according to

[10] , selected from:

[12] The composition according to

[10] or

[11] , wherein the molar ratio of dicyandiamide to the sum of the urea derivatives is within the range of 1:1 to 4:1.

[13] at least one chelate-modified epoxy resin; and / or The composition according to any one of [1] to

[12] , further comprising at least one elastomer-modified epoxy resin.

[14] 30-60% by weight of a) at least one epoxy resin; at least one internally flexibilized epoxy resin characterized by a Shore D hardness of 45 or less, measured with a durometer according to ASTM D2240, when cured with 5 to 30% by weight of b) diethylenetriamine; 1-35 wt% of c) core-shell rubber particles; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, characterized in that the curing agent consists of dicyandiamide; and e) comprising at least one urea derivative of formula (V) or formula (VI): JPEG0007809055000011.jpg97129 In the formulas (V) and (VI): At least one residue R 1 、R 2 、R 3 but not hydrogen; R 1 and R 2 are independently hydrogen and C 1 -C 4 alkyl; and R 4 、R 5 、R 6 、R 7 and R 8 are independently hydrogen, halogen, C 1 -C 4 Alkyl and -NHC(O)NR 1 R 2 Selected from; the composition is characterized in that the molar ratio of epoxide-reactive groups to epoxide groups provided in the curing agent d) is from 0.95:1 to 1.5:1, preferably from 0.95:1 to 1.1:1; and The composition according to any one of [1] to

[13] , wherein the molar ratio of dicyandiamide to the sum of the urea derivatives is in the range of 1:1 to 4:1, preferably 1:1 to 3:1.

[15] A cured product obtained from the one-component (1K) composition according to any one of [1] to

[14] .

[16] 15. Use of the cured reaction product according to

[15] as a structural adhesive.

Claims

1. a) at least one epoxy resin; b) at least one internally flexibilized epoxy resin characterized by a Shore D hardness of 45 or less when cured with diethylenetriamine, as measured with a durometer according to ASTM D2240; c) two core-shell rubber particles having different average particle sizes (d50), wherein the smaller particles have an average particle size of 10 to 100 nm and the larger particles have an average particle size of 120 to 300 nm, and the weight ratio of the smaller particles to the larger particles is in the range of 3:1 to 5:1; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, characterized in that the curing agent comprises dicyandiamide; and e) at least one accelerator wherein the molar ratio of epoxide-reactive groups to epoxide groups provided in said curing agent d) is from 0.95:1 to 1.5:1, wherein the a) epoxy resin is different from the b) internally flexibilized epoxy resin, the chelate-modified epoxy resin, and the elastomer-modified epoxy resin.

2. 10. The composition of claim 1, comprising 20 to 70 wt. % of a) said at least one epoxy resin, based on the weight of said composition.

3. 3. The composition of claim 1, wherein the at least one epoxy resin is selected from: glycidyl ethers of polyhydric alcohols and polyhydric phenols; glycidyl esters of polycarboxylic acids; and epoxidized polyethylenically unsaturated hydrocarbons, esters, ethers, and amides.

4. The composition of any one of claims 1 to 3, wherein the internally flexibilized epoxy resin has an epoxide equivalent weight of 200 to 600 g / eq.

5. 5. The composition of claim 1, wherein the internally flexibilized epoxy resin, when cured with diethylenetriamine, has a Shore D hardness of 40 or less as measured with a durometer according to ASTM D2240.

6. comprising an internally flexibilized epoxy resin having the general formula (III): The composition of any one of claims 1 to 5, wherein n and o are the same or different and are independently selected from 1 to 10.

7. The composition of any one of claims 1 to 6, comprising 1 to 30 wt% of said internally flexibilized epoxy resin, based on the weight of the composition.

8. The composition according to any one of claims 1 to 7, comprising 1 to 40 wt. % of c) core-shell rubber particles, based on the weight of the composition.

9. 9. The composition according to claim 1, wherein the dicyandiamide has a particulate form characterized by an average particle size of 0.5 to 100 μm.

10. e) the at least one accelerator comprises or consists of at least one urea derivative of formula (V) or formula (VI): wherein at least one residue R １ , R ２ , R ３ is not hydrogen; R １ and R ２ are independently hydrogen, C １ -C １８ Alkyl and C ３ -C １８ cycloalkyl; R ３ But hydrogen, C １ -C １８ Alkyl, C ３ -C １８ Cycloalkyl, C ６ -C １８ Aryl, C ６ -C １８ Aralkyl, C ６ -C １８ Alkylaryl, —NHC(O)NR １ R ２ C substituted with １ -C １８ Alkyl, —NHC(O)NR １ R ２ C substituted with ３ -C １８ Cycloalkyl, —NHC(O)NR １ R ２ C substituted with ６ -C １８ Aryl; —NHC(O)NR １ R ２ C substituted with ６ -C １８ aralkyl; or —NHC(O)NR １ R ２ C substituted with ６ -C １８ aralkyl; and R ４ , R ５ , R ６ , R ７ and R ８ are independently hydrogen, halogen, C １ -C １８ Alkyl, C ３ -C １８ Cycloalkyl, C ６ -C １８ Aryl, C ６ -C １８ Aralkyl, C ６ -C １８ -alkylaryl, -CF ３ , -NHC(O)NR １ R ２ , -NHC(O)NR １ R ２ C substituted with １ -C １８ Alkyl, —NHC(O)NR １ R ２ C substituted with ３ -C １８ Cycloalkyl, —NHC(O)NR １ R ２ C substituted with ６ -C １８ Aryl; —NHC(O)NR １ R ２ C substituted with ６ -C １８ aralkyl; and —NHC(O)NR １ R ２ C substituted with ６ -C １８ The composition of any one of claims 1 to 9, wherein the alkyl group is selected from aralkyl.

11. In the formulas (V) and (VI), At least one residue R １ , R ２ , R ３ is not hydrogen; R １ and R ２ are independently hydrogen and C １ -C ４ alkyl; and R ４ , R ５ , R ６ , R ７ and R ８ are independently hydrogen, halogen, C １ -C ４ Alkyl and —NHC(O)NR １ R ２ The composition of claim 10, wherein the composition is selected from:

12. The composition according to claim 10 or claim 11, wherein the molar ratio of dicyandiamide to the sum of the urea derivatives is within the range of 1:1 to 4:

1.

13. At least one chelate-modified epoxy resin different from a) and b); and / or The composition of any one of claims 1 to 12, further comprising at least one elastomer-modified epoxy resin different from a) and b).

14. 30 to 60 wt. % of a) at least one epoxy resin; at least one internally flexibilized epoxy resin characterized by a Shore D hardness of 45 or less, measured with a durometer according to ASTM D2240, when cured with 5 to 30 wt. % of b) diethylenetriamine; 1 to 35 wt. % of c) core-shell rubber particles; d) a curing agent consisting of at least one compound having at least two epoxide-reactive groups per molecule, characterized in that the curing agent consists of dicyandiamide; and e) comprising at least one urea derivative of formula (V) or formula (VI): In the formulas (V) and (VI): At least one residue R １ , R ２ , R ３ is not hydrogen; R １ and R ２ are independently hydrogen and C １ -C ４ alkyl; and R ４ , R ５ , R ６ , R ７ and R ８ are independently hydrogen, halogen, C １ -C ４ Alkyl and —NHC(O)NR １ R ２ Selected from: the composition is characterized in that the molar ratio of epoxide-reactive groups to epoxide groups provided in the curing agent d) is from 0.95:1 to 1.1:1; and The composition according to any one of claims 1 to 13, wherein the molar ratio of dicyandiamide to the sum of the urea derivatives is in the range of 1:1 to 4:

1.

15. A cured product obtained from a one-component (1K) composition according to any one of claims 1 to 14.

16. 16. Use of the cured reaction product of claim 15 as a structural adhesive.

Images