Method of reinforcing a metal structure using a toughened 2c-epoxy adhesive

Abstract

The invention relates to a method for reinforcing a metal structure comprising the steps of i) mixing a two-component epoxy resin composition; ii) applying the composition onto the surface of the metal structure, or onto the reinforcing element, or onto both; iii) bringing the applied epoxy resin composition into contact with the surface of the reinforcing element and / or the surface of the metal structure, so that the composition forms an intermediate layer between the metal structure and the reinforcing element, iv) optionally pre-stressing the reinforcing element, v) optionally pre-fixing the reinforcing element to the metal structure by mechanical fixation or spot welding, so that the reinforcing element is held in place before curing the composition, and vi) curing the epoxy resin composition at a temperature of 100°C or below; characterized in that the two-component epoxy resin composition contains - a first component comprising 10-50 wt% of at least one epoxy resin containing on average more than 1 epoxy group per molecule; - a second component comprising 5-30 wt% of a hardener for the epoxy resin; - 3-25 wt% of at least one impact modifier in either or both components; - 15-80 wt% of at least one filler F in either or both components; and wherein the two-component epoxy resin composition after curing exhibits an elastic modulus of at least 2500 MPa measured according to DIN EN ISO 527, and an impact peel strength of at least 15 N / mm measured according to ISO 11343. The method according to the invention is particularly suitable for the refurbishment of metal structures, such as bridges, and leads to a significant improvement of the mechanical properties of those structures.

Description

Technical Field

[0001] This invention relates to the field of methods for reinforcing metal structures using two-component epoxy resin compositions and reinforcing elements. Existing technology

[0002] An important area of ​​the building and construction industry is the renovation of structures affected by time and weather, such as buildings and bridges. Completely rebuilding such structures is often commercially and logistically impractical in their aging state, but over time they suffer from fatigue and increased mechanical demands, eventually risking collapse or severe damage.

[0003] The use of epoxy adhesives in structural reinforcement applications, including the permanent attachment of reinforcing elements such as fiber-reinforced plastic sheets to the structure to be reinforced, is a common practice in renovations and significantly improves the capacity, load-bearing capacity, and overall service life of these structures with minimal cost, work time, and aesthetic impact. For these applications, strong epoxy adhesives are typically used to primarily reinforce concrete substrates, such as… -30 (available from Sika Schweiz AG). Concrete is generally more brittle than the epoxy adhesives used, therefore, concrete failure is primarily observed in this application. However, structural reinforcement is more necessary on less brittle substrates such as composites or steel. There are numerous metal structures nearing the end of their service life and partially requiring reinforcement, such as steel bridges, but which cannot be closed for major renovations or replacements due to traffic or use. Welding is generally not an option in metal structure renovations because large-area welding reduces the mechanical strength of the underlying metal structure. To date, adhesives similar to those used for concrete have been used for steel reinforcement, and their performance is known to be poor, particularly in terms of adhesion to steel and failure due to their brittle behavior under relatively small loads / displacements, especially under high fatigue loads (e.g., due to traffic). To bond carbon fiber reinforced plastic (CRP) to concrete, using standard epoxy adhesives, the maximum anchorage length (lap) is sufficient to achieve a strong bond. On the other hand, when bonding CRP or steel to a steel substrate, the maximum anchorage length using this adhesive is more limited to ensure no bond failure. However, a longer anchorage length is required to transfer more additional force to provide reliable reinforcement.

[0004] Therefore, there is a need for a method to reinforce metal structures in the refurbishment market that uses an adhesive that has rapid curing properties under environmental conditions, is suitable for top and vertical applications, has excellent fatigue properties, and is easy to apply to bond reinforcing elements, such as metal or fiber-reinforced plastics, to the metal structure to be reinforced. Summary of the Invention

[0005] Therefore, the object of the present invention is to provide a method for strengthening metal structures, which results in permanent and reliable mechanical improvements to the metal structures without the risk of adhesive failure.

[0006] Surprisingly, it has been found that using a special, highly toughened and filled two-component epoxy adhesive to bond reinforcing elements to a metal structure results in a significant improvement in the mechanical properties of the reinforced metal structure without any of the problems associated with standard strong epoxy adhesives, particularly bond failure.

[0007] In a first aspect, the present invention relates to a method for strengthening a metal structure M, comprising the following steps:

[0008] i) Mix the two-component epoxy resin composition C;

[0009] ii) Apply composition C to the surface of the metal structure M, or to the reinforcing element S, or both;

[0010] iii) The applied epoxy resin composition is brought into contact with the surface of the reinforcing element S and / or the surface of the metal structure M, such that the composition forms an intermediate layer between the metal structure M and the reinforcing element S.

[0011] iv) Optionally, pre-stress is applied to the reinforcing element S.

[0012] v) Optionally, the reinforcing element S is pre-fixed to the metal structure M by mechanical fastening or spot welding to hold the reinforcing element S in place before the curing composition, and

[0013] vi) Curing the epoxy resin composition at or below 100°C, preferably at 10-40°C;

[0014] Its features

[0015] The two-component epoxy resin composition C contains

[0016] - The first component K1 comprises 10-50 wt% of at least one epoxy resin A containing more than one epoxy group per molecule on average, based on the total weight of composition C;

[0017] - The second component K2 contains 5-30 wt% of a curing agent B for epoxy resin based on the total weight of composition C;

[0018] - At least one impact modifier I, in either or both of components K1 and K2, at 3-25 wt% based on the total weight of composition C;

[0019] - At least one filler F, comprising 15-80 wt% of the total weight of component C in either or both of components K1 and K2; and

[0020] The two-component epoxy resin composition C exhibits, after curing, an elastic modulus of at least 2500 MPa, preferably at least 3000 MPa, as measured according to DIN EN ISO 527, and an impact peel strength of at least 15 N / mm, preferably at least 20 N / mm, as measured according to ISO 11343.

[0021] Other aspects of the invention are the subject of the additional independent claims. Particularly preferred embodiments are the subject of the dependent claims.

[0022] Embodiments of the present invention

[0023] Throughout the text, for example, the prefix "poly(poly)" in "polyisocyanate", "polyol" or "polyphenol" indicates a molecule that formally contains two or more corresponding functional groups.

[0024] The term "primary diamine" as used in this invention refers to a diamine having two terminal primary amino groups, which does not contain any additional secondary amino groups. In terms of the branching potential of the amino-terminated impact modifiers according to the invention in continuous reactions, the introduction of secondary amino groups into the molecule has proven to be disadvantageous.

[0025] In this article, "impact modifier" refers to an additive for epoxy resin matrices that, even in small amounts, particularly 0.1-15 wt%, significantly improves the toughness of the cured matrix, allowing it to withstand higher bending, tensile, vibration, or impact stresses before cracking or fracturing. Typically, the impact peel strength according to ISO 11343 is used as a measure of impact strength. Here, the breaking energy (BE) is expressed as the area under the measurement curve (from 25% to 90% according to ISO 11343). Typically, the impact peel strength according to ISO 11343 can also be used as another measure of impact strength.

[0026] Unless otherwise stated, the term "modulus of elasticity" refers to the modulus of elasticity as measured according to DIN EN ISO 527 (within the range of 0.05-0.25% elongation).

[0027] As used herein, the term "polymer" refers, on the one hand, to a collection of chemically homogeneous but differing macromolecules in degree of polymerization, molar mass, and chain length, prepared by polymerization reactions (addition, addition, condensation). On the other hand, the term also includes derivatives of said collection of macromolecules obtained by polymerization reactions, i.e., compounds obtained by reactions such as addition or substitution of functional groups on predetermined macromolecules, which may be chemically homogeneous or chemically heterogeneous. Furthermore, the term also includes so-called prepolymers, i.e., reactive organic preadducts whose functional groups participate in macromolecular formation.

[0028] In this document, the term “independently of each other” when used in conjunction with a substituent, part or group should be interpreted as such that substituents, parts or groups with the same name can coexist in the same molecule with different definitions.

[0029] The term “room temperature” (“RT”) refers to a temperature of 23°C unless otherwise specified.

[0030] Unless otherwise stated, all industry standards and specifications referenced refer to the latest version at the time of the initial filing of this patent application.

[0031] In this document, the term "weight" refers to the mass of a compound or composition measured in kilograms.

[0032] The two-component epoxy resin composition C comprises a first component K1, which contains 10 to 50 wt%, preferably 12 to 48 wt%, and particularly 15 to 45 wt%, of at least one epoxy resin A containing an average of more than one epoxy group per molecule, based on the total weight of composition C.

[0033] The epoxy resin A contained in the first component K1 of composition C can be any conventional difunctional or polyfunctional epoxy resin used in the art. For example, a suitable epoxy resin can be obtained from the reaction of an epoxy compound such as epichlorohydrin with a polyfunctional aliphatic or aromatic alcohol, i.e., a diol, triol, or polyol. One or more epoxy resins may be used.

[0034] Epoxy resin A, which contains an average of more than one epoxy group per molecule, is preferably a liquid epoxy resin and / or a solid epoxy resin.

[0035] The term "solid epoxy resin" is well-known to those skilled in the art of epoxy resins and is used in contrast to "liquid epoxy resin." Solid resins have a glass transition temperature greater than room temperature, meaning they can be pulverized into a free-flowing powder at room temperature.

[0036] Suitable liquid or solid epoxy resins, especially diglycidyl ethers of formula (I), are particularly appropriate.

[0037]

[0038] Where R 4 It is a divalent aliphatic, mononuclear aromatic, or binuclear aromatic group.

[0039] Examples of such diglycidyl ethers are particularly difunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain C2-C ethers. 30 Diglycidyl ethers of alcohols, such as ethylene glycol, butanediol, hexanediol or octanediol diglycidyl ether, cyclohexanediol diglycidyl ether, neopentyl glycol diglycidyl ether;

[0040] Diglycidyl ethers of difunctional low to high molecular weight polyether polyols, such as polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether.

[0041] Difunctional bisphenols and optional triglycerides of diglycidyl ethers should be understood as not only pure phenols, but also optionally substituted phenols.

[0042] The types of substitution can be very diverse. In particular, this is understood to refer to substitution directly on the aromatic nucleus bonded to the phenolic hydroxyl group. Furthermore, phenol should be understood not only as a mononuclear aromatic compound, but also as a polynuclear or fused aromatic or heteroaromatic compound having a phenolic hydroxyl group directly on the aromatic or heteroaromatic compound. Suitable examples of bisphenols and optionally triphenols include 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 1,2-dihydroxybenzene, 1,3-dihydroxytoluene, 3,5-dihydroxybenzoate, and 2,2-bis(4-hydroxyphenyl). Propane (= Bisphenol-A), bis(4-hydroxyphenyl)methane (= Bisphenol-F), bis(4-hydroxyphenyl)sulfone (= Bisphenol-S), naphthoresorcinol, dihydroxynaphthalene, dihydroxyanthraquinone, dihydroxy-biphenyl, 3,3-bis(p-hydroxyphenyl)phthalide, 5,5-bis(4-hydroxyphenyl)hexahydro-4,7-methylindene, phenolphthalein, fluorescein, 4,4'-[bis(hydroxyphenyl)-1,3-phenylenebis(1- Bisphenol-M, 4,4'-[bis(hydroxyphenyl)-1,4-phenylenebis(1-methyl-ethylene)] (= bisphenol-P), 2,2'-diallyl-bisphenol-A, bisphenols and xylenols prepared by reacting phenol or cresol with diisopropylbenzene, phloroglucinol, bile esters, phenols or cresol phenolic varnishes with a -OH functionality of 2.0 to 3.5, and all isomers of the above compounds.

[0043] The preferred solid epoxy resin A has formula (II).

[0044]

[0045] In this formula, the substituents R' and R” are each independently H or CH3. In addition, the index s has a value >1.5, especially 2-12.

[0046] This solid epoxy resin is commercially available, for example from Dow, Huntsman, or Hexion.

[0047] Compounds of formula (II) having an index s of 1-1.5 are considered by those skilled in the art to be semi-solid epoxy resins. For the purposes of this invention, they are also considered solid resins. However, epoxy resins in the narrow sense are preferred, i.e., those with an index s of >1.5.

[0048] The preferred liquid epoxy resin A has formula (III).

[0049]

[0050] In this formula, the substituents R”' and R”” are each independently H or CH3. Additionally, the exponent r has a value between 0 and 1. Preferably, r has a value less than 0.2.

[0051] Therefore, these are preferably bisphenol A diglycidyl ether (DGEBA), bisphenol F diglycidyl ether, and bisphenol A / F diglycidyl ether (here, the name "A / F" refers to a mixture of acetone and formaldehyde, used as a reactant in its preparation). This liquid resin can, for example, be used as... GY 250 PY 304 GY 282 (Huntsman) or DER TM 331, or DER TM Obtained from 330 (Olin) or Epikote 828 (Hexion).

[0052] Furthermore, so-called linear phenolic varnishes are suitable epoxy resins A. These specifically have the following formula:

[0053] Where R2 = Or CH2, R1=H or methyl and z=0 to 7.

[0054] Specifically, they are linear phenolic varnishes of phenol or cresol (R2=CH2).

[0055] These epoxy resins can be EPN or ECN and The product name 556 was purchased from Huntsman or under the name DEN. TM The product line was purchased from Dow Chemical.

[0056] Preferably, epoxy resin A is a liquid epoxy resin of formula (III). In an even more preferred embodiment, the thermosetting epoxy resin composition contains at least one epoxy resin of formula (III) and at least one solid epoxy resin of formula (II).

[0057] Bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, or bisphenol A / F diglycidyl ether are particularly preferred. GY 240 GY 250 GY 281 GY 282 GY 285 PY 304 or PY 720 (all from Huntsman), or 330 331. 332、 336、 351. 352. 354 or 356 (all from Olin), or linear phenolic varnish glycidyl ether.

[0058] The preferred material is linear phenolic varnish glycidyl ether derived from phenol-formaldehyde linear phenolic varnish, which is also known as epoxy phenolic varnish resin.

[0059] This linear phenolic varnish glycidyl ether is commercially available, for example, from Olin, Huntsman, Momentive, or Emerald Performance Materials. The preferred type is... 431. 438 or 439 (from Olin) EPN 1179 EPN 1180 EPN 1182 or EPN 1183 (from Huntsman) 154. 160 or 161 (from Momentive) or 8250 8330 or 8350 (from Emerald Performance Materials).

[0060] The proportion of epoxy resin A is preferably 12-48 wt%, particularly 13-47 wt%, more preferably 15-45 wt%, based on the weight of composition C.

[0061] Additionally, component K1 of composition C may contain monofunctional, difunctional, and polyfunctional reactive diluents (e.g., butylene glycol diglycidyl ether).

[0062] These reactive diluents are specifically for:

[0063] - Monofunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain C4-C 30Glycidyl ethers of alcohols, particularly selected from butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ethers, and trimethoxysilyl glycidyl ether.

[0064] -Difunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C2-C 30 Glycidyl ethers of alcohols, particularly selected from ethylene glycol, butanediol, hexanediol or octanediol glycidyl ether, cyclohexanediol diglycidyl ether and neopentyldiol diglycidyl ether.

[0065] - Glycidyl ethers of trifunctional or polyfunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain alcohols, such as epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol, or aliphatic polyols such as sorbitol, glycerol, or polyglycidyl ethers of trimethylolpropane.

[0066] - Glycidyl ethers of phenol and aniline compounds, particularly selected from phenyl glycidyl ether, tolyl glycidyl ether, p-tert-butyl-phenyl glycidyl ether, nonylphenol glycidyl ether, 3-n-pentadecanenyl glycidyl ether (from cashew nut shell oil), N,N-diglycidylaniline and p-aminophenol triglycidyl ether.

[0067] - Epoxidized amines, such as N,N-diglycidylcyclohexylamine.

[0068] - Epoxidized mono or dicarboxylic acids, particularly selected from glycidyl neodecanoate, glycidyl methacrylate, glycidyl benzoate, diglycidyl phthalate, tetra- and hexahydrophthalates, diglycidyl esters of dimer fatty acids, and diglycidyl esters of terephthalic acid and trimellitic acid.

[0069] - Epoxidized di- or trifunctional low to high molecular weight polyether polyols, particularly polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether.

[0070] Hexanediol diglycidyl ether, toluene diglycidyl ether, p-tert-butylphenyl diglycidyl ether, polypropylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether are particularly preferred.

[0071] Advantageously, the total proportion of reactive diluent is 0.1 to 20 wt%, preferably 1-8 wt%, based on the weight of the total composition C.

[0072] The two-component epoxy resin composition C contains a second component K2, which comprises 5-30 wt%, preferably 6-25 wt%, and particularly 7-20 wt% of a curing agent B for epoxy resin based on the total weight of composition C.

[0073] The curing agent B is preferably a compound or mixture of compounds selected from poly(ethyleneimine), polyamidoamine, amino-terminated butadiene / acrylonitrile copolymer and polyamine.

[0074] Examples of suitable hardener B include, for example:

[0075] ◆Aliphatic, alicyclic, or aryliphatic primary diamines,

[0076] Examples include ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 2-methyl-1,2-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,3-butanediamine, 1,4-butanediamine, 1,3-pentanediamine (DAMP), 1,5-pentanediamine, 1,5-diamino-2-methylpentane (MPMD), 2-butyl-2-ethyl-1,5-pentanediamine (C11-neo-diamine), 1,6... Hexamethylenediamine, 2,5-dimethyl-1,6-hexamethylenediamine, 2,2,4- and 2,4,4-trimethylhexamethylenediamine (TMD), 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, 1,2-,1,3- and 1,4-diaminocyclohexane, bis-(4-aminocyclohexyl)methane (H 12 -MDA), bis-(4-amino-3-methylcyclohexyl)methane, bis-(4-amino-3-ethylcyclohexyl)methane, bis-(4-amino-3,5-dimethylcyclohexyl)methane, bis-(4-amino-3-ethyl-5-methylcyclohexyl)methane (M-MECA), 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (=isophorone diamine or IPDA), 2- and 4-methyl-1,3-diaminocyclohexane and mixtures thereof, 1,3- and 1,4-bis-(aminomethyl)cyclohexane, 2,5(2,6)-bis-(aminomethyl)-bicyclo[2.2.1]heptane (NBDA), 3(4),8(9)-bis-(aminomethyl)-tricyclo[5.2.1.0 2,6 ] Decane, 1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA), 1,8-menthanediamine, 3,9-bis-(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]decane and 1,3- and 1,4-xylenediamine;

[0077] ◆Aliphatic primary diamines containing ether groups,

[0078] Examples include bis(2-aminoethyl) ethers, 3,6-dioxaoctane-1,8-diamine, 4,7-dioxadecane-1,10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-1,12-diamine, 5,8-dioxadodecane-3,10-diamine, 4,7,10-trioxatridecane-1,13-diamine, and higher oligomers of these diamines; bis-(3-aminopropyl)polytetrahydrofuran and other polytetrahydrofuran diamines having molecular weights in the range of, for example, 350-2000; and polyalkylene oxide diamines. Typically, the latter are products of the amination of polyalkylene oxide diols and can be, for example, named... (From Huntsman), by name Polyetheramin (from BASF), or by name PC (Originated from Nitroil). Particularly suitable polyoxyalkylene diamines are... D-230 D-400 D-2000 XTJ-511 ED-600 ED-900 ED-2003 XTJ-568 XTJ-569 XTJ-523 XTJ-536 XTJ-542 XTJ-559 EDR-104 EDR-148 EDR-176;Polyetheramin D 230. Polyetheramin D 400 and Polyetheramin D 2000, PC DA250, PC DA 400, PC DA 650 and PC DA 2000;

[0079] ◆ Polyamines containing secondary amino groups,

[0080] Examples include diethylenetriamine (DETA), dipropyltriamine (DPTA), bis(hexamethylenetriamine) (BHMT), 3-(2-aminoethyl)aminopropylamine, N3-(3-aminopentyl)-1,3-pentanediamine, N5-(3-aminopropyl)-2-methyl-1,5-pentanediamine, N5-(3-amino-1-ethylpropyl)-2-methyl-1,5-pentanediamine, N,N'-dibutylethylenediamine; N,N'-di-tert-butylethylenediamine, N,N'-diethyl-1,6-hexanediamine, 1-(1-methylethylamino)-3-(1-methylethylaminomethyl)-3,5,5-trimethylcyclohexane (… 754, obtained from Huntsman), N4-cyclohexyl-2-methyl-N2-(2-methylpropyl)-2,4-pentanediamine, N,N'-dialkyl-1,3-xylidenediamine, bis-(4-(N-alkylamino)cyclohexyl)methane, 4,4'-trimethylenedipiperidine, N-alkylated polyetheramine, for example Models SD-231, SD-401, SD-404, and SD-2001 (obtained from Huntsman);

[0081] ◆Amine / polyepoxide addition products,

[0082] In particular, the addition products of the polyamines and diepoxides mentioned above at a molar ratio of at least 2 / 1, especially 2 / 1 to 6 / 1;

[0083] ◆ Polyaminoamines

[0084] It is the reaction product of mono- or polycarboxylic acids or their esters or anhydrides, especially dimer fatty acids and aliphatic, cyclic aliphatic or aromatic polyamines used in stoichiometric excess, particularly polyalkylene amines such as DETA or triethylenetetramine (TETA), especially commercially available polyamide amines. 100, 125, 140 and 150 (from Cognis) 223,250 and 848 (from Huntsman) 3607 530 (from Huntsman) EH 651, EH 654, EH 655, EH 661 and EH 663 (obtained from Cytec);

[0085] ◆ Polyethylene imide (PEI)

[0086] These are branched polymeric amines derived from the polymerization of ethyleneimine. Suitable polyethyleneimines typically have an average molecular weight of 250-25000 g / mol and contain tertiary, secondary, and primary amines. Polyethyleneimines can be marketed, for example, under trade names... (Originated from BASF) For example, type FG, G20 and PR 8515.

[0087] ◆Cashew Chitosan

[0088] These are the reaction products of cashew nut shell liquid (CNSL), the main component of which is cashew phenol and amines, forming a phenolic amine structure. These are regenerable raw materials with excellent properties and can be used as curing agent B.

[0089] Suitable polyamines, especially polyoxyalkylene diamines with a molecular weight of less than 500 g / mol ( D-230, Jeffamine D400 EDR-148), 4,7,10-trioxatridecane-1-13-diamine, 4,9-dioxadodecane-1,12-diamine, ethylenediamine, and / or 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0] 2,6 ] Decane (TCD- (Manufactured by Celanese Chemicals). Polyethylene imides with molecular weights (Mw) of less than 100,000 g / mol, and especially less than 50,000 g / mol, have shown to be particularly suitable.

[0090] In particular, the preferred polyamines, which are diamines or triamines, are selected from aliphatic diamines or triamines containing ether groups, especially polyoxyalkylene diamines and triamines; particularly polyoxyethylene diamines and triamines, polyoxypropylene diamines and triamines; polyoxybutylene diamines and triamines, amino-terminated polybutadiene and butadiene / acrylonitrile copolymers or mixtures thereof.

[0091] In particular, these are polyoxyalkylene polyamines having two or three amino groups, for example, those named as... (Originally from Huntsman Chemicals), under the name Polyetheramin (Originally from BASF), or under the name PC (Originally from Nitroil) is commercially available, as well as a mixture of the above polyamines.

[0092] The two-component epoxy resin composition C preferably contains 7-20 wt% of the curing agent B, based on the total weight of composition C.

[0093] In addition, the hardener component K2 may contain an accelerator. Suitable accelerators are substances that promote the reaction between amino and epoxy groups, particularly acids or compounds that can be hydrolyzed to acids, especially organic carboxylic acids such as acetic acid, benzoic acid, salicylic acid, 2-nitrobenzoic acid, lactic acid, organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid, or 4-dodecylbenzenesulfonic acid, sulfonates, other organic or inorganic acids, such as phosphoric acid, or mixtures of the above acids or esters; tertiary amines, such as accelerator B already mentioned, or 1,4-diazabicyclo[2.2.2]octane, triethanolamine, imidazoles, such as N-methylimidazolium, N... -Vinylimidazole or 1,2-dimethylimidazole, salts of these tertiary amines, quaternary ammonium salts, especially benzyltrimethylammonium chloride, amidines, especially 1,8-diazabicyclo[5.4.0]undec-7-ene, guanidines, especially 1,1,3,3-tetramethylguanidine, phenols, especially bisphenols, phenolic resins or Mannich bases, especially 2,4,6-tris(dimethylaminomethyl)phenol or 2,4,6-tris(N,N-dimethyl-4-amino-2-azabutyl)phenol, phosphites, for example, especially di- or triphenyl phosphites, or compounds containing a thiol group. Acids, tertiary amines, or Mannich bases are preferred as promoters.

[0094] The most preferred of these is salicylic acid or 2,4,6-tris(dimethylaminomethyl)phenol or 2,4,6-tris(N,N-dimethyl-4-amino-2-azabutyl)phenol or a combination thereof.

[0095] Furthermore, compounds containing at least one dimethylamino group are preferred as accelerators. In particular, benzyl dimethylamine, α-methylbenzyl dimethylamine, N,N-diethyl-N',N'-dimethyl-1,3-propanediamine, N,N-dimethylethanolamine, 3-(N,N-dimethylamino)propane-1-ol, 2- or 4-(dimethylaminomethyl)phenol, 2,4- or 2,6-bis(N,N-dimethylaminomethyl)phenol, 2,4,6-tris(N,N-dimethylaminomethyl)phenol, 2,4,6-tris(N,N-dimethyl-4-amino-2-azabutyl)phenol, or especially N,N,N',N'-tetramethyl-1,2-ethylenediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'-tetramethyl-1,4-butanediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N,N',N ',N”-pentamethyldiethylenetriamine, N,N,N',N',N”-pentamethyldipropylenetriamine, N,N,N',N',N”-pentamethyl-N-(2-aminoethyl)-1,3-propanediamine, N,N-dimethyl-1,2-ethylenediamine, N,N-dimethyl-1,3-propanediamine, N,N-dimethyl-1,4-butanediamine, N,N-dimethyl-1,6-hexanediamine, 2-(2-(dimethylamino)ethylamino)ethylamine, 2-(3-(dimethylamino)propylaminoethylamine, 3-(2-(dimethylamino)ethylamino)propylamine, 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA), bis(2-(N,N-dimethylamino)ethyl)amine or bis(3-(N,N-dimethylamino)propyl)amine.

[0096] Particularly preferred are N,N,N',N',N"-pentamethyldiethylenetriamine, 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA), or bis(3-(N,N-dimethylamino)propyl)amine. These accelerators are readily available, have low odor, and exhibit high compressive strength, high adhesive strength, and virtually no curing problems at low temperatures. 3-(3-(dimethylamino)propylamino)propylamine (DMAPAPA) is the most preferred accelerator. DMAPAPA is characterized by low odor, toxicological safety, and commercial availability.

[0097] Furthermore, composition C contains 3-25 wt%, preferably 4-20 wt%, particularly 5-15 wt%, of at least one impact modifier I based on the total weight of composition C in either or both of components K1 and K2. This amount refers to a pure, active impact modifier without solvents or other solid or liquid additives typically used for better storage, handling, dispersion, dilution, or other purposes.

[0098] Suitable impact modifiers include, for example, core-shell polymers. Core-shell polymers consist of an elastic core polymer and a rigid shell polymer. Particularly suitable core-shell polymers consist of a core (core) of an elastic acrylate or butadiene polymer encapsulated in a rigid shell of a rigid thermoplastic polymer. This core-shell structure is either spontaneously formed by the separation of block copolymers or predetermined by latex polymerization or suspension polymerization followed by grafting.

[0099] The preferred core-shell polymer is the so-called MBS polymer, which can be traded under various names. By Arkema, By Dow (formerly Rohm and Haas) or by Available commercially from Zeon. Particularly preferred are core-shell polymer particles already present as dried polymer latex. An example is Wacker's product with a polysiloxane core and an acrylate shell. M23A, radiation-crosslinked rubber granules from the NEP series manufactured by Eliokem, or from Lanxess. Or from Dow EXL. Other comparable core-shell polymers are exemplified by Evonik Hanse GmbH (Germany) under the name EXL. Also suitable are nanoscale silicates in epoxy groups, such as those offered by Evonik Hanse GmbH (Germany) under the trade name Nonopox.

[0100] Furthermore, a suitable impact modifier I is a liquid rubber of acrylonitrile / butadiene copolymer or its derivatives that are carboxyl or epoxy-terminated. Such a liquid rubber may, for example, be named... (previous) CTBN, CTBNX, and ETBN are commercially available from Emerald Performance Materials LLC. Derivatives, particularly epoxy-containing elastomer-modified prepolymers, are available as part of a product line. Preferred from product lines 36. By the company (Schill+Seilacher Group (Germany)) or by product line (Those supplied by Evonik Hanse GmbH (Germany)). In another embodiment, the impact modifier is a liquid polyacrylate rubber that is completely miscible with the liquid epoxy resin and only separates into droplets upon curing of the epoxy resin matrix. Such a liquid polyacrylate rubber is, for example, available from Dow (formerly Rohm and Haas) under the name 20208-XPA.

[0101] It will be apparent to those skilled in the art that mixtures of liquid rubbers, particularly mixtures of carboxyl- or epoxide-terminated acrylonitrile / butadiene copolymers or their derivatives with epoxy-terminated or other functionalized polyurethane prepolymers, can also be used.

[0102] Another suitable impact modifier is the reaction product of carboxylated solid nitrile rubber and excess epoxy resin.

[0103] Furthermore, polymers of formula (IV) containing epoxy groups are suitable as impact modifier I.

[0104]

[0105] Here, R 7 This refers to the divalent group remaining after the removal of the terminal carboxyl group in carboxyl-terminated butadiene / acrylonitrile copolymer (CTBN). Group R 4 This is defined and described above for equation (I).

[0106] This epoxy-functional impact modifier should be present only in component K1.

[0107] Polymers of formula (V) are also suitable as impact modifier I.

[0108]

[0109] In this formula, n and n' are each independent of each other and are values ​​from 0 to 7, preferably 0, 1, or 2, provided that n+n' is a value from 1 to 8, especially 1 or 2.

[0110] In addition, R 1 It is a linear or branched polyurethane prepolymer with n+n' isocyanate groups at the end after removing all terminal isocyanate groups. R 2 and R 3 Each of the above is an aliphatic, alicyclic, aromatic or aryliphatic group, independently of each other, having 1-20 C atoms and heteroatoms optionally selected from O, N and S, particularly O and N.

[0111] If the base R is substituted 2 and R 3 If the epoxy group is reactive, then the impact modifier I of formula (V) is part of component K2. If the substituent R... 2 and R 3 If the impact modifier I of formula (V) is reactive to amino groups, then it is part of the hardener component K1. Non-reactive impact modifiers of this type, or impact modifiers compatible with both components K1 and K2, can be incorporated into one or both of components K1 and K2. This principle applies not only to those of formula (V) but to all impact modifiers.

[0112] In a preferred embodiment of the impact modifier according to formula (V), R 1 It is a linear polyurethane prepolymer containing at least n+n' terminal isocyanate groups after removing n+n' terminal isocyanate groups.

[0113] R 2 and R 3 It is the cashew phenol residue after the removal of the hydroxyl H atom, and it is linked via an oxygen atom.

[0114] Cashew phenol (CAS registration number: 37330-39-5) is a phenolic lipid obtained from cashew acid, the main component of cashew nut shell liquid (CNSL), and byproducts of cashew processing. The name derives from the abbreviation of the genus *Anacardium*, which includes the cashew tree *Anacardium occidentale*. Besides being a particularly effective impact modifier, this cashew phenol-terminated impact modifier I also has the advantage of being based on partially natural and renewable resources, and is inexpensive.

[0115] Cashew phenol, for example, can be marketed under a trade name The NC-700 was purchased from Cardolite Corporation.

[0116] Block copolymers, particularly solid block copolymers, are also suitable as impact modifiers I. Block copolymers can be obtained by anionic or controlled radical polymerization of methacrylates with at least one other monomer having an olefinic double bond. Preferred monomers having an olefinic double bond are those in which the double bond is directly conjugated with a heteroatom or with at least one other double bond. In particular, suitable monomers are selected from styrene, butadiene, acrylonitrile, and vinyl acetate. Preferred are acrylate-styrene-acrylic acid (ASA) copolymers, for example, which may be named... 1020 is obtained from GE Plastics. Particularly preferred block copolymers are block copolymers of methyl methacrylate, styrene, and butadiene. Such block copolymers can be obtained by Arkema, for example, as triblock copolymers under the name SBM.

[0117] In addition, amino-terminated acrylonitrile / butadiene copolymers are suitable as impact modifier I, and are part of the curing agent component K2.

[0118] Suitable impact modifiers include epoxy-terminated polyurethane polymers, wherein a prepolymer is first prepared from di / triisocyanates, a polymeric polyol, and an alkoxylated bisphenol, and then reacted with an epoxy compound containing primary or secondary hydroxyl groups. These are described in EP1 972 646A1.

[0119] In addition, suitable impact modifiers I are described in EP 2 917 254 A1 and EP 2 917 255 A1.

[0120] The two-component epoxy resin composition C preferably contains 5-15 wt% of the impact modifier I, based on the total weight of composition C.

[0121] Preferably, the weight ratio of all epoxy functional compounds in the composition (e.g., epoxy resin, reactive diluent) to the pure impact modifier (without any solvents, additives, etc.) in the composition is 1 to 3 (w / w), preferably between 1.2 and 2.9 (w / w), and more preferably between 1.3 and 2.7 (w / w). This ratio makes the composition particularly effective at toughening, thus allowing the use of a variety of different impact modifiers I to achieve the desired impact peel strength and modulus of elasticity. It is worth noting that epoxy-functionalized impact modifiers are not considered epoxy functional compounds in this calculation, but are always considered impact modifiers I. Impact modifiers functionalized in other ways (e.g., those having amino groups) are of course always considered impact modifiers I in the weight ratio calculation as well.

[0122] Furthermore, composition C contains 15-80 wt%, preferably 17-70 wt%, particularly 20-60 wt%, of at least one filler F based on the total weight of composition C in either or both of components K1 and K2.

[0123] The use of fillers is advantageous because they improve the aging resistance of the adhesive and positively affect its mechanical properties.

[0124] Suitable fillers for F include inorganic and organic fillers, such as ground or precipitated calcium carbonate, optionally coated with fatty acids, especially stearic acid, barium sulfate (barite), talc, quartz powder, quartz sand, dolomite, wollastonite, kaolin, mica (potassium aluminum silicate), molecular sieves, alumina, aluminum hydroxide, silica (pyrolytic or precipitated), cristobalite, cement, gypsum, soot, carbon black, graphite, metal powders such as aluminum, copper, iron, silver or steel, PVC powder, or hollow spheres, such as solid or hollow glass spheres and organic hollow spheres.

[0125] Furthermore, layered minerals, particularly those that exchange with organic ions, are suitable as filler F. Ion-exchangeable layered minerals can be either cation-exchangeable or anion-exchangeable. The binder may also contain both cation-exchangeable and anion-exchangeable layered minerals. Such layered minerals can have the added advantage of acting as corrosion inhibitors. If this is the case, and those minerals have significant anti-corrosion properties, then for the purposes of this invention, they should be classified as corrosion inhibitors as discussed further below.

[0126] Thus, cation-exchangeable layered minerals are obtained from layered minerals in which at least a portion of the cations have been replaced by organic cations. Examples of such cation-exchangeable layered minerals are particularly those mentioned in US Pat. No. 5,707,439 or US Pat. No. 6,197,849. Methods for preparing these cation-exchangeable layered minerals are also described therein. Layered silicates are preferred as layered minerals. Layered minerals are particularly preferred as layered silicates, such as those described in column 2, line 38 to column 3, line 5 of US Patent No. 6,198,849, especially bentonite. Layered minerals such as kaolinite, montmorillonite, lithium montmorillonite, or illite have proven to be particularly suitable.

[0127] Preferred cation-exchange layered minerals are known to those skilled in the art by the names organoclay or nanoclay, and may be, for example, named as (Byk Additives&Instruments)or (Byk Additives&Instruments), (or (Nanocor Inc.) or (Byk Additives & Instruments) Obtained through commercial purchase.

[0128] Anion-exchanged layered minerals can be obtained from layered minerals in which at least some of the anions have been exchanged for organic anions. An example of anion-exchanged layered minerals is hydrotalcite, in which at least a portion of the carbonate anions in the middle layer have been replaced by organic anions.

[0129] The filler F preferably comprises particles having a median particle size of at least 0.1 to 1 mm, preferably at least 0.2 to 2 mm, and particularly at least 0.5 to 5 mm. This provides the additional advantage that such large filler particles act as a separator, ensuring a sufficiently thick adhesive layer and preventing extrusion from the adhesive material when the reinforcing element S is pressed onto the applied adhesive.

[0130] The median particle size of filler F is typically determined by methods such as dynamic light scattering or, preferably, sieve analysis according to ASTM C136-06.

[0131] The two-component epoxy resin composition C preferably contains 1-15 wt%, more preferably 2-10 wt%, and particularly 3-7 wt% of an anti-corrosion agent in either or both of components K1 and K2, based on the total weight of composition C.

[0132] The addition of a corrosion inhibitor (also known as a corrosion suppressant) provides the added advantage of eliminating the need for pretreatment of the metal structure to be reinforced with an anti-corrosion layer before applying the adhesive composition C. Without anti-corrosion measures, there is a significant risk of corrosion to the metal structure, especially at the points where reinforcing elements are joined, which can severely impede the reinforcement process and lead to bond failure. While an additional treatment step of applying an anti-corrosion coating could be used before applying the adhesive composition C, this is disadvantageous because it requires an extra step and, moreover, creates a coating interlayer between the metal surface of the structure to be reinforced and the adhesive, which can impair bonding performance. Therefore, the addition of a corrosion inhibitor to composition C is advantageous.

[0133] Suitable corrosion inhibitors are anodic inhibitors (also known as passivation inhibitors), which act through a reducing anodic reaction and form an insoluble, coherent, and very thin film adsorbed onto the metal. Some examples of inorganic anodic inhibitors are nitrates, molybdates, sodium chromate, phosphates, hydroxides, and silicates, particularly calcium oxide-modified silicates and sodium silicates. Additionally, layered minerals, such as ground phlogopite and micronized muscovite, and modified hydrotalcite (MHT), also known as “layered double hydroxide” (LHD), are suitable as corrosion inhibitors.

[0134] Other suitable corrosion inhibitors are cathodic corrosion inhibitors. These inhibitors prevent cathodic reactions in metals. Some examples of inorganic cathodic inhibitors are magnesium, zinc, and nickel ions, which react with the hydroxyl groups (OH-) in water. - The reaction forms insoluble hydroxides, such as Mg(OH)₂, Zn(OH)₂, and Ni(OH)₂, which are deposited on the cathode site of the metal surface for protection. Additionally, polyphosphates, phosphonates, tannins, lignin, and calcium salts are also suitable.

[0135] In addition, suitable are organic corrosion inhibitors that act as cathode inhibitors, anodic inhibitors, or both. Some examples are amines, ureas, mercaptobenzothiazole (MBT), benzotriazole, etoliotriazole, aldehydes, heterocyclic nitrogen compounds, sulfur-containing compounds, and alkyne compounds, as well as ascorbic acid, succinic acid, tryptamine, caffeine, and extracts of natural substances.

[0136] In addition, the two-component epoxy resin composition C may contain other additives. These include, for example:

[0137] Solvents, film-forming aids or chain extenders, such as toluene, xylene, methyl ethyl ketone, 2-ethoxyethanol, 2-ethoxyethyl acetate, benzyl alcohol, ethylene glycol, diethylene glycol butyl ether, dipropylene glycol butyl ether, ethylene glycol butyl ether, ethylene glycol phenyl ether, N-methylpyrrolidone, propylene glycol butyl ether, propylene glycol phenyl ether, diphenylmethane, diisopropylnaphthalene, mineral oil fractions such as Solvesso type (from Exxon), aromatic resins, especially those containing phenolic groups, sebacate, phthalates, organophosphates and sulfonates, and sulfonamides;

[0138] -Reactive diluents, such as the epoxy reactive diluents mentioned above, epoxidized soybean oil or linseed oil, compounds with acetoacetate groups, especially acetoacetic acidified polyols, butyrolactones, isocyanates, and silicones with reactive groups.

[0139] - Polymers, such as polyamides, polysulfides, polyvinyl formal (PVF), polyvinyl butyral (PVB), polyurethane (PUR), carboxyl-containing polymers, polyamides, butadiene-acrylonitrile copolymers, styrene-acrylonitrile copolymers, butadiene-styrene copolymers, homopolymers or copolymers of unsaturated monomers, said monomers particularly including ethylene, propylene, butene, isobutylene, isoprene, vinyl acetate and alkyl (meth)acrylates, particularly chlorosulfonated polyethylene and fluoropolymers, sulfonamide-modified melamine and clean lignite wax;

[0140] - Fibers, such as plastic fibers, carbon fibers, or glass fibers;

[0141] - Pigments, such as titanium dioxide or iron oxide or organic pigments;

[0142] - Rheology modifiers, such as thickeners, such as flake silicates like bentonite, castor oil derivatives, hydrogenated castor oil, polyamides, polyurethanes, urea compounds, pyrolytic silicates, cellulose ethers, and hydrophobically modified polyoxyethylene.

[0143] - Tackifiers, such as organoalkoxysilanes such as 3-glycidoxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-N'[3-(trimethoxysilyl)propyl]ethylenediamine, 3-ureopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, vinyltrimethoxysilane or the corresponding organosilane having an ethoxy or (poly)etheroxy group instead of a methoxy group;

[0144] - Stabilizer resistant to oxidation, heat, light and ultraviolet radiation;

[0145] -Flame retardants, particularly compounds such as aluminum oxide (Al(OH)3; also known as ATH for "aluminum trihydrate"), magnesium hydroxide (Mg(OH)2; also known as MDH for "magnesium dihydrate"), ammonium sulfate ((NH4)2SO4), boric acid (B(OH)3), zinc borate, melamine borate, and melamine cyanurate; phosphorus-containing compounds such as ammonium phosphate ((NH4)3PO4), ammonium polyphosphate, melamine phosphate, melamine pyrophosphate, triphenyl phosphate, diphenyltolyl phosphate, tricresyl phosphate, triethyl phosphate, tri(2-ethylhexyl) phosphate, trioctyl phosphate, mono-, bis-, and tri(isopropylphenyl) phosphates, resorcinol di(diphenyl phosphate), resorcinol diphosphate oligomers, tetraphenylresorcinol diphosphite, ethylenediamine diphosphate, and di(isopropylphenyl) phosphate. Phenol A bis(diphenyl phosphate); halogenated compounds, such as chloroalkyl phosphates, especially tri(chloroethyl) phosphate, tri(chloropropyl) phosphate and tri(dichloroisopropyl) phosphate, polybrominated diphenyl ethers, especially decabromodiphenyl ether, polybrominated diphenyl ethers, tris[3-bromo-2,2-bis(bromomethyl)propyl] phosphate, tetrabromobisphenol A, bis(2,3-dibromopropyl) ether of bisphenol A, brominated epoxy resins, ethylene-bis-tetrabromophthalimide, ethylene bis(dibromonorbornene dicarboximide), 1,2-bis-(tribromophenoxy)ethane, tris(2,3-dibromopropyl)isocyanurate, tribromophenol, hexabromocyclododecane, bis(hexachlorocyclopentadienyl)cyclooctane and chlorinated paraffins; and combinations of halogenated compounds and antimony trioxide (Sb₂O₃) or antimony pentoxide (Sb₂O₅);

[0146] - Surfactants, such as wetting agents, flow control agents, degassing agents, or defoamers;

[0147] - Biocides, such as algaecides, fungicides, or substances that inhibit fungal growth.

[0148] It is clear and known to those skilled in the art that additives can be added to resin component K1 and to hardener component K2. Here, it is particularly important to ensure that such additives do not, or only slightly, impair storage stability. Therefore, it will be apparent to those skilled in the art that polyamines will react with the epoxides in resin component K1 and thus can only be included in hardener component K2.

[0149] In a preferred embodiment, the two-component epoxy resin composition C contains an additive in either or both of components K1 and K2, the additive preferably selected from tackifiers, wetting agents and degassing agents, in an amount of 0.1-5 wt%, preferably 0.25-4 wt%, particularly 0.5-3 wt%, based on the total composition C.

[0150] In epoxy resin composition C, the ratio of the number of amino groups reactive to epoxy groups to the number of epoxy groups is preferably 0.7-1.5, particularly 0.8-1.2.

[0151] In epoxy resin composition C, the preferred weight ratio of epoxy resin A, hardener B, impact modifier I, and filler F is A:B:I:F = 1:(0.25-1):(0.25-1):(1-4), particularly 1:(0.3-0.5):(0.3-0.5):(1.5-3.5).

[0152] Components K1 and K2 of epoxy resin composition C are stored in separate containers. Suitable containers for storing resin K1 or hardener K2 are, in particular, barrels, buckets, bags, bladders, cans, boxes, or tubes. The components are recyclable, meaning they can be stored for months to a year or longer before use without any change in their individual properties relevant to their intended use. For application of the epoxy resin adhesive, the resin is mixed with hardener components K1 and K2, along with any other optional components, shortly before or during application.

[0153] The components are mixed using a suitable method. Mixing can be continuous or batch-wise. If mixing is performed before application, care must be taken to ensure that the mixing and application of the components does not take too long, as this can lead to interference, such as slowing down or incomplete adhesion formation. Mixing is particularly carried out at ambient temperature, typically in the range of about 0 to 40°C, preferably in the range of about 5 to 30°C.

[0154] When the components are mixed, curing begins through a chemical reaction. In this case, the epoxy groups react with amino groups carrying amino hydrogen and any other groups that can react with the epoxy groups, and ring-opening yields an amino alcohol unit. Further epoxy groups react with each other under anionic polymerization, particularly catalyzed by dimethylamino groups. As a result of these reactions, the adhesive cures into a cross-linked material. Those skilled in the art know that primary amino groups are "bifunctional" with respect to epoxy groups, meaning they can react with two separate epoxy groups.

[0155] Curing occurs, especially at ambient temperature. It typically takes from several hours to several days, until it is substantially complete under given conditions. Important influencing factors are temperature, stoichiometry, and the presence of an accelerator.

[0156] As a result of the curing reaction, a cured adhesive was obtained.

[0157] Preferably, the application and curing of the adhesive are carried out at ambient temperature, particularly between 0 and 40°C, especially between 5 and 30°C. This allows for particularly simple handling of the adhesive and is especially advantageous outdoors, on construction sites, and in unheated industrial buildings.

[0158] The two-component epoxy resin composition C, after curing, exhibits an elastic modulus of at least 2500 MPa as measured according to DIN EN ISO 527, and an impact peel strength of at least 15 N / mm as measured according to ISO 11343. These properties are necessary for applying the adhesive in the method according to the invention to obtain appropriate mechanical reinforcement of the metal structure M.

[0159] By carefully adjusting the individual components of composition C, particularly impact modifier I and filler F, within their respective required ranges, technicians are able to achieve those properties in routine experiments.

[0160] If the properties are below these values, the composition is not entirely suitable as an excellent adhesive for reinforcing metal structures, and adhesive failure is expected.

[0161] Preferably, the two-component epoxy resin composition C exhibits an elastic modulus of at least 3000 MPa, preferably at least 3250 MPa, as measured according to DIN EN ISO 527 after curing.

[0162] Preferably, the two-component epoxy resin composition C exhibits an impact peel strength of at least 20 N / mm, preferably at least 25 N / mm, as measured according to ISO 11343 after curing.

[0163] The method for strengthening a metal structure M according to the present invention comprises the following steps:

[0164] i) Mix the above two-component epoxy resin composition C;

[0165] ii) Apply composition C to the surface of the metal structure M, or to the reinforcing element S, or both;

[0166] iii) The applied epoxy resin composition is brought into contact with the surface of the reinforcing element S and / or the surface of the metal structure M such that the composition forms an intermediate layer between the metal structure M and the reinforcing element S.

[0167] iv) Optionally, pre-stress is applied to the reinforcing element S.

[0168] v) Optionally, the reinforcing element S is pre-fixed to the metal structure M by mechanical fastening or spot welding, so as to hold the reinforcing element S in place before the applied composition C is cured, and

[0169] vi) Curing epoxy resin composition C at a temperature of 100°C or below, preferably 10-40°C;

[0170] The metal structure M can be made of any metal or metal alloy used for constructing large metal structures, such as aluminum, iron, steel, or non-ferrous metals, or of surface-refined metals or alloys such as galvanized or chromium-plated metals. Furthermore, it can be made of coated metals or alloys, such as powder-coated metals or alloys, or these materials that have been painted or varnished. If desired, the surface of the metal structure M can be pre-treated before the application of adhesives. Such pre-treatment includes, in particular, physical and / or chemical cleaning processes, such as grinding, sandblasting, shot blasting, brushing, and / or blowing, as well as further treatment with cleaning agents or solvents or the application of tackifiers, primer solutions, or primers.

[0171] The metal structure M is preferably a metal frame or building, especially a bridge.

[0172] In another preferred embodiment, the metal structure M is a metal component of a vehicle, particularly a road vehicle, air vehicle, or water vehicle. The vehicle is preferably a bus, truck, train, tram, airplane, helicopter, ship, vessel, or submarine. The most preferred vehicle is a large road vehicle, especially a bus, or an air vehicle.

[0173] The method according to the invention has significant advantages when used to reinforce the metal structure of a vehicle. Firstly, the metal structure of the vehicle can be significantly reinforced without increasing its overall weight. This is particularly advantageous for efficient fuel consumption and other weight-related effects. By employing the method according to the invention, the vehicle can be structurally reinforced, resulting in greater passenger safety and crashworthiness.

[0174] On the other hand, by using a metal structure reinforced by the method according to the invention, a lower mass or lighter metal structure can be used, and subsequently reinforced by the method, resulting in the same range of structural stability as a higher mass or heavier unreinforced metal structure, but with a lower overall weight. This allows for lightweight structural construction, reducing the overall weight of the vehicle, thereby saving on the manufacturing, use, and maintenance costs of the vehicle.

[0175] The reinforcing element S can be any shape or material suitable for mechanically reinforcing the metal structure M.

[0176] For example, suitable materials include:

[0177] - Metals or alloys, such as aluminum, iron, steel or non-ferrous metals, or surface-refined metals or alloys, such as zinc-plated or chromium-plated metals;

[0178] - Wood, wood materials or other so-called polymer composites bonded with resins such as phenolic resin, melamine resin or epoxy resin;

[0179] - Plastics, especially rigid or flexible polyvinyl chloride (PVC) and flexible polyolefins Adhesion-modified chlorosulfonated polyethylene ABS, polycarbonate (PC), polyamide (PA), polyester, PMMA, epoxy resin, PUR, POM, PO, PE, PP, EPM or EPDM, optionally plastics treated with plasma, corona or flame surface treatment; and

[0180] - Fiber-reinforced plastics, such as carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GRP), or sheet molding compounds (SMC).

[0181] In a preferred embodiment, the reinforcing element S is made of metal or a composite material containing glass fiber or carbon fiber.

[0182] Suitable shapes for reinforcing element S include, for example, plates, lattices, sheets, grids, strips, or any other shape that is geometrically and statically suited to the desired purpose.

[0183] In a preferred embodiment, the reinforcing element S is selected from metal plates, metal grids, glass fiber reinforced plastic plates, glass fiber reinforced plastic sheets, carbon fiber reinforced plastic sheets, and carbon fiber reinforced plastic sheets. Particularly preferred as the reinforcing element S is a sheet made of CFRP, for example, by Sika Schweiz AG under the trade name... Those sold in S market.

[0184] The reinforcing element S can be directly adhered to the metal structure M in step v), or it can be adhered in a prestressed manner (see step iv). This can include mechanical prestressing, i.e., by applying tension along one axis of the reinforcing element S, for example using mechanical clamps, hydraulic or pneumatic or other means to prestress the reinforcing element S during application, but it can also be achieved by using advanced technologies, such as shape memory alloys, which change size upon heating (and subsequently simultaneously cure the composition C). The advantage of prestressing step iv) is that the damaged (e.g., cracked or partially split) concrete substrate can be further reinforced by the relaxation force acting on the prestressed reinforcing element S to prevent further propagation of damage.

[0185] Another aspect of the invention is a set of components for reinforcing a metal structure M, comprising...

[0186] a) Strengthening element S, and

[0187] b) Two-component epoxy resin composition C, containing

[0188] - The first component K1 comprises 10-50 wt% of at least one epoxy resin A containing more than one epoxy group per molecule on average, based on the total weight of composition C;

[0189] - The second component K2 contains 5-30 wt% of a curing agent B for epoxy resin based on the total weight of composition C;

[0190] - At least one impact modifier I, in 3-25 wt% of either or both of components K1 and K2 based on the total weight of composition C;

[0191] - At least one filler F in either or both of components K1 and K2, based on the total weight of component C, at 15-80 wt%;

[0192] The two-component epoxy resin composition C, after curing, exhibits an elastic modulus of at least 2500 MPa as measured according to DIN EN ISO 527, and an impact peel strength of at least 15 N / mm as measured according to ISO 11343.

[0193] In a preferred embodiment of the assembly, the reinforcing element S is made of metal or composite material, particularly plastic, containing glass fiber or carbon fiber, and may be pre-stressed during or before application.

[0194] All components, such as C, M, S, and parameters, such as the amounts of components in a kit, are the same as those detailed above for the method of the present invention. The same applies to preferred embodiments of these components and combinations thereof. Example

[0195] The following examples further illustrate the invention, but do not limit the scope of the invention in any way, and merely illustrate some possible implementations. "Standard conditions" or "standard climate" ("NK") refers to a temperature of 23°C and a relative humidity (rh) of 50%.

[0196] Test methods

[0197] The following testing methods were used:

[0198] Compressive strength (CS) and compressive modulus (C-Mod) (ASTM D695)

[0199] Compressive strength and compressive modulus were determined by applying a mixed adhesive to cuboids measuring 12.7 x 12.7 x 25.4 mm in a silicone mold under standard climatic conditions. These samples were cured under standard conditions. After 7 days, multiple such cuboids were released from the mold for each condition and compressed to failure at a test rate of 1.3 mm / min according to ASTM D695. The compressive strength value for each condition was read at maximum force.

[0200] Tensile strength (TS), elongation at break (EOB), and modulus of elasticity (E-Mod) (DIN) EN ISO 527)

[0201] These mechanical properties were determined by applying a mixed adhesive to a silicone mold under standard climatic conditions and curing therein to form a dumbbell-shaped specimen with a thickness of 10 mm, a length of 150 mm, a face length of 80 mm, and a face width of 10 mm. After a 7-day curing time (NK), the test specimen was removed from the mold. The specimen was measured at a tensile speed of 2 mm / min under standard conditions. Tensile strength, elongation at break, and modulus of elasticity (0.05–0.25%) were determined according to DIN EN ISO 527.

[0202] Lap shear strength (LSS) (DIN EN 1465)

[0203] To measure the lap shear strength of steel (LSS steel), several adhesive bonding materials were prepared by applying a mixed adhesive between two heptane-degreased steel plates with a layer thickness of 0.5 mm and an overlap bonding area of ​​10 x 25 mm. After storage under standard conditions for 7 days, the tensile shear strength was determined according to DIN EN 1465 at a tensile speed of 10 mm / min.

[0204] To measure the lap shear strength (LSS CFK) on carbon fiber reinforced polymer (CFRP) composites, a method was used to measure the lap shear strength (LSS CFK) on two heptane-degreased plates. Several adhesive bonding layers were prepared by applying a mixed adhesive between S512 heat sinks with a layer thickness of 0.5 mm and an overlap of 10 x 50 mm. After storage at NK for 7 days, the overlap shear strength was determined as described.

[0205] Maximum bending force (MBF)

[0206] Using the method according to the invention and the adhesives of the invention and non-invention listed in Table 1, the maximum bending force was determined by applying the mixed adhesive in a 1 mm layer thickness to a heptane-degreased steel plate. Subsequently, a heptane-degreased CFK sheet ( S512) was covered, pressed together, and then cured in NK for 7 days. Afterward, a three-point bending test was performed on each sample until adhesive failure (AF) or substrate failure (SF) was observed. The maximum bending force that the steel test sample reinforced under this force had been subjected to was determined. This value provides a good quantitative description of the steel reinforced by this method and illustrates the behavior of the metal structure under stress and displacement.

[0207] Impact peel strength (IPS) (ISO 11343)

[0208] Test samples were prepared using the described example composition and electroplated zinc DC04 steel (eloZn) with dimensions of 90 × 20 × 0.8 mm, wherein the adhesive surface area was 25 × 10 mm and the layer thickness was 0.3 mm. They were cured at 23 °C for 7 days. Impact peel strength was measured at 23 °C with an impact velocity of 2 m / s according to ISO 11343. Failure modes were also determined. “AF” indicates adhesive failure and “CF” indicates cohesive failure.

[0209] Two-component epoxy resin composition tested

[0210] The two-component epoxy resin compositions used are listed in Table 1.

[0211]

[0212] Table 1: Measurements of two-component epoxy adhesives. *According to the present invention...

[0213] Examples of compositions according to the invention

[0214] A series of exemplary two-component compositions (compositions C1-C8) were prepared using the following ingredients and by mixing these ingredients (all wt% values ​​refer to the total composition C):

[0215] Epoxy resin

[0216]

[0217]

[0218] hardener

[0219]

[0220] filler

[0221]

[0222] Impact modifier

[0223]

[0224]

[0225] additive

[0226]

[0227] For testing purposes, a homogeneous mixture of the above-described components forming each composition C was prepared using a stirrer and applied directly to the surface of a substrate used to prepare the test specimen. Commercially available comparative samples were prepared according to the specifications of the commercial products used for testing. For each embodiment, the resin and hardener components were subsequently processed into a homogeneous paste using a centrifugal mixer and tested immediately as described above.

[0228] Synthesis of an exemplary impact modifier I1

[0229] 150g of isocyanate-terminated prepolymer (composed of 60wt% Poly) 2000 (BASF), 40wt% Poly R45V (Cray Calley) was prepared), isophorone diisocyanate (Evonik) (0.75 equivalents), and dibutyltin dilaurate catalyst were dried with 1 equivalent. The mixture was treated with 828LVEL (Hexion). Subsequently, 8.11 mmol of phthalic anhydride (Sigma Aldrich) was added, the reaction mixture was mixed, and then reacted under vacuum at 110 °C with the addition of a catalyst.

[0230] Synthesis of Impact Modifier I2

[0231] Under a nitrogen atmosphere, with constant stirring, 5687g of 4200g of polyol (Bayer Material Science), 712g of MDI (trade name Desmodur 44MC L, Covestro), and 0.6g of catalyst DABCO 33LV (Air Products) were heated to 80°C and maintained at this temperature to prepare an NCO-terminated prepolymer. After one hour of reaction, the free NCO content was determined by titration. The isocyanate group content reached 1.9 wt%. Subsequently, 910g of cashew nut shellac (trade name Cardolite NC-700, Cardolite) was added, and stirring was continued at 80°C for another 2 hours. Infrared spectroscopy (wavenumber 2275–2230 cm⁻¹) was then performed. -1 The reaction stops when no more free isocyanate is detected.

[0232] Mechanical properties of the tested two-component epoxy resin compositions

[0233] The two-component epoxy adhesives used in Table 1 were tested according to the methods detailed below. The results are shown in Tables 2 and 4.

[0234]

[0235]

[0236] Table 2: Mechanical properties of the tested two-component epoxy resin adhesives.

[0237] According to the present invention

[0238] Structure-reinforcing behavior of the tested two-component epoxy resin compositions

[0239] Some of the two-component epoxy adhesives used in Table 1 were measured according to the three-point bending test method detailed below. The results are shown in Table 3.

[0240]

[0241] Table 3: Reinforcing properties of the tested two-component epoxy adhesives. “AF” indicates adhesive failure, and “SF” indicates substrate failure of the CFK sheet. *According to the present invention.

[0242]

[0243] Table 4: Mechanical properties of exemplary two-component epoxy resin adhesives according to the present invention.

[0244] **Weight / weight ratio of all epoxy functional compounds to all impact modifiers.

Claims

1. A method for strengthening a metal structure M, comprising the following steps: i) Mix the two-component epoxy resin composition C; ii) Apply the two-component epoxy resin composition C to the surface of the metal structure M, or to the reinforcing element S, or both; iii) The applied two-component epoxy resin composition C is brought into contact with the surface of the reinforcing element S and / or the surface of the metal structure M, such that the composition forms an intermediate layer between the metal structure M and the reinforcing element S. iv) Optionally, pre-stress is applied to the reinforcing element S. v) Optionally, the reinforcing element S is pre-fixed to the metal structure M by mechanical fastening or spot welding to hold the reinforcing element S in place before the curing composition, and vi) Curing the epoxy resin composition at or below 100°C; Its features The two-component epoxy resin composition C contains - The first component K1 comprises 10-50 wt% of at least one epoxy resin A containing more than one epoxy group per molecule on average, based on the total weight of the composition; - The second component K2 contains 5-30 wt% of a curing agent B for epoxy resin based on the total weight of composition C; - At least one impact modifier I, in 5-15 wt% of either or both of components K1 and K2 based on the total weight of composition C; - At least one filler F comprising 51.5-60 wt% of the total weight of component C in either or both of components K1 and K2; and The weight ratio of all epoxy functional compounds in the composition to the pure impact modifier in the composition is between 1.2 and 3, and The two-component epoxy resin composition C exhibits, upon curing, an elastic modulus of at least 2500 MPa as measured according to DIN EN ISO 527, and an impact peel strength of at least 15 N / mm as measured according to ISO 11343.

2. The method according to claim 1, characterized in that... In step vi), the epoxy resin composition is cured at a temperature of 10-40°C.

3. The method according to claim 1, characterized in that... The reinforcing element S is made of metal or a composite material containing glass fiber or carbon fiber.

4. The method according to claim 3, characterized in that... The reinforcing element S is selected from metal plates, metal meshes, glass fiber reinforced plastic sheets, glass fiber reinforced thin plates, carbon fiber reinforced plastic sheets, and carbon fiber reinforced thin plates.

5. The method according to claim 1, characterized in that... The two-component epoxy resin composition C contains 1-15 wt% of an anti-corrosion agent in either or both of components K1 and K2, based on the total weight of composition C.

6. The method according to claim 5, characterized in that... The two-component epoxy resin composition C contains 2-10 wt% of an anti-corrosion agent, based on the total weight of composition C.

7. The method according to claim 1, characterized in that... The filler F comprises particles having a median particle size of at least 0.1-1 mm.

8. The method according to claim 1, characterized in that... In the composition, the weight ratio of all epoxy-functionalized compounds to pure impact modifier I in the composition is 1.3-2.

9.

9. The method according to claim 1, characterized in that... In composition C, the weight ratio of epoxy resin A, hardener B, impact modifier I and filler F is A:B:I:F=1 : (0.25-1) : (0.25-1) : (1-4).

10. The method according to claim 1, characterized in that... The two-component epoxy resin composition C contains 15-45 wt% of the epoxy resin A, based on the total weight of composition C.

11. The method according to claim 1, characterized in that... The two-component epoxy resin composition C contains 7-20 wt% of the curing agent B, based on the total weight of composition C.

12. The method according to claim 1, characterized in that... The metal structure is a metal frame or building.

13. The method according to claim 12, characterized in that... The metal structure is a metal component of a bridge or vehicle.

14. The method according to claim 12, characterized in that... The metal structure is a metal component of the bus.

15. A complete set of components for reinforcing the metal structure M, including a) Strengthening element S, and b) Two-component epoxy resin composition C, containing - The first component K1 comprises 10-50 wt% of at least one epoxy resin A containing more than one epoxy group per molecule on average, based on the total weight of composition C; - The second component K2 contains 5-30 wt% of a curing agent B for epoxy resin based on the total weight of composition C; - At least one impact modifier I, in 5-15 wt% of either or both of components K1 and K2 based on the total weight of composition C; - At least one filler F in either or both of components K1 and K2, based on the total weight of component C, at 51.5-60 wt%; and The weight ratio of all epoxy functional compounds in the composition to the pure impact modifier in the composition is between 1.2 and 3, and The two-component epoxy resin composition C exhibits, upon curing, an elastic modulus of at least 2500 MPa as measured according to DIN EN ISO 527, and an impact peel strength of at least 15 N / mm as measured according to ISO 11343.

16. The complete set of components according to claim 15, characterized in that... The reinforcing element S is made of metal or a composite material containing glass fiber or carbon fiber.

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