Heat-curing epoxy resin composition suitable for pre-curing processes without additional metal bonding techniques

Description

Technical area

[0001] The invention relates to the field of heat-curing one-component epoxy resin compositions, in particular for use as body shell adhesives. State of the art

[0002] An important application for heat-curing, one-component epoxy resin compositions is in vehicle construction, particularly for bonding in the bodyshell. After the epoxy resin composition is applied, the body is heated in a cathodic dip painting (CDP) oven, which also cures the heat-curing, one-component epoxy resin composition. Currently, these epoxy adhesives are used exclusively in combination with other metal joining techniques such as welding and riveting, as the bonded components would not withstand mechanical stress prior to curing, for example, during transport to the CDP oven. Partial curing of the applied epoxy adhesives prior to the CDP oven, for example, using induction heating, would be a fast and cost-effective alternative to the complex thermal and mechanical metal joining techniques mentioned above.However, such partial curing processes have the disadvantage that typically only a limited amount of energy is applied to the epoxy adhesives, curing progresses too slowly, and the resulting mechanical strength is low. Especially at the high temperatures of 180 °C in e-coating ovens, the adhesion of conventional partially cured epoxy adhesives fails without additional metal joining techniques before the final cure is achieved.

[0003] EP3677611A1 discloses a heat-curing epoxy resin composition comprising an epoxy resin and the hardener adipic acid dihydrazide. Description of the invention

[0004] The object of the present invention is therefore to provide heat-curing one-component epoxy resin compositions which, without additional metal bonding techniques, exhibit sufficient adhesion after pre-curing, in particular 60 seconds at 180 - 200 °C, preferably 180 °C, upon further heating to 180 °C.

[0005] This object could surprisingly be achieved by a heat-curing, one-component epoxy resin composition according to claim 1. This epoxy resin composition can be used particularly well as a one-component heat-curing adhesive, in particular as a heat-curing, one-component bodyshell adhesive in vehicle construction. Ways to implement the invention

[0006] The present invention relates to thermosetting one-component epoxy resin compositions comprising: a) at least one epoxy resin Awith an average of more than one epoxy group per molecule; b) at least one hardener B1 for epoxy resins, where the hardener is B1 is an aromatic dicarboxylic acid dihydrazide, in particular isophthalic acid dihydrazide and / or terephthalic acid dihydrazide, preferably isophthalic acid dihydrazide; and c) at least one hardener B2 for epoxy resins, where the hardener is B2 a dihydrazide selected from the group consisting of glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, 8,12-eicosadienedioic acid-1,20-dihydrazide and 4-isopropyl-2,5-dioxoimidazolidine-1,3-di(propionohydrazide), in particular adipic acid dihydrazide.

[0007] The weight ratio of hardener B1 to hardener B2 ( B1 / B2 ) is from 0.15 - 20.

[0008] In this document, the use of the term "independently of one another" in connection with substituents, residues or groups is to be interpreted as meaning that in the same molecule the substituents, residues or groups with the same name can occur simultaneously with different meanings.

[0009] In this document, the prefix "poly" in substance names such as "polyol", "polyisocyanate", "polyether" or "polyamine" indicates that the respective substance formally contains more than one of the functional groups mentioned in its name per molecule.

[0010] In this document, "molecular weight" refers to the molar mass (in grams per mole) of a molecule. "Mean molecular weight" refers to the number-average molecular weight Mn of an oligomeric or polymeric mixture of molecules, which is usually determined by GPC against polystyrene as a standard.

[0011] A "primary hydroxyl group" is an OH group that is bonded to a C atom with two hydrogens.

[0012] In this document, the term "primary amino group" refers to an NH2 group bonded to an organic residue, while the term "secondary amino group" refers to an NH group bonded to two organic residues, which may also together be part of a ring. Accordingly, an amine containing a primary amino group is referred to as a "primary amine," one containing a secondary amino group is referred to as a "secondary amine," and one containing a tertiary amino group is referred to as a "tertiary amine."

[0013] In this document, "room temperature" is defined as 23°C.

[0014] The epoxy resin AWith an average of more than one epoxy group per molecule, it is preferably a liquid epoxy resin or a solid epoxy resin. The term "solid epoxy resin" is well known to epoxy experts and is used in contrast to "liquid epoxy resins." The glass transition temperature of solid resins is above room temperature, meaning they can be ground into pourable powders at room temperature.

[0015] Preferred epoxy resins have the formula (II)

[0016] Here, the substituents R' and R" independently represent either H or CH 3 .

[0017] For solid epoxy resins, the index s stands for a value of > 1.5, in particular from 2 to 12.

[0018] Such solid epoxy resins are commercially available, for example from Dow, Huntsman or Hexion.

[0019] Compounds of formula (II) with an index s of 1 to 1.5 are referred to by those skilled in the art as semisolid epoxy resins. For the purposes of the present invention, they are also considered solid resins. However, preferred solid epoxy resins are epoxy resins in the narrower sense, i.e., where the index s has a value of > 1.5.

[0020] For liquid epoxy resins, the index s represents a value less than 1. Preferably, s represents a value less than 0.2.

[0021] These are therefore preferably diglycidyl ethers of bisphenol A (DGEBA), bisphenol F, and bisphenol A / F. Such liquid resins are available, for example, as Araldite ®< GY 250, Araldite ®< PY 304, Araldite ®< GY 282 (Huntsman), DER ™< 331 or DER ™< 330 (Dow), or Epikote 828 (Hexion).

[0022] Also suitable as epoxy resin A are so-called epoxy novolaks. These have the following formula: with or CH 2 , R1 = H or methyl and z = 0 to 7.

[0023] In particular, these are phenol or cresol epoxy novolaks ( R2 = CH2).

[0024] Such epoxy resins are commercially available under the trade names EPN or ECN as well as Tactix ®< from Huntsman or under the DEN ™< product range from Dow Chemical.

[0025] Preferably, the epoxy resin A an epoxy resin of formula (II), in particular an epoxy liquid resin of formula (II).

[0026] In a particularly preferred embodiment, the heat-curing one-component epoxy resin composition contains both at least one liquid epoxy resin of the formula (II) with s < 1, in particular less than 0.2, and at least one solid epoxy resin of the formula (II) with s > 1.5, in particular from 2 to 12.

[0027] The proportion of epoxy resin Ais preferably 10 - 60 wt.%, in particular 30 - 60 wt.%, in particular 40 - 55 wt.%, based on the total weight of the epoxy resin composition.

[0028] Furthermore, it is advantageous if 50-100 wt.%, in particular 80-100 wt.%, of the epoxy resin A is a previously mentioned epoxy liquid resin.

[0029] Furthermore, it is advantageous if 0-30 wt.%, in particular 0-20 wt.%, particularly preferably 5-15 wt.%, of the epoxy resin A is a previously mentioned solid epoxy resin.

[0030] The composition according to the invention further contains at least one hardener B1 for epoxy resins, where the hardener is B1 is an aromatic dicarboxylic acid dihydrazide. In particular, it is isophthalic acid dihydrazide and / or terephthalic acid dihydrazide, preferably isophthalic acid dihydrazide.

[0031] Suitable dihydrazides are, for example, commercially available from Otsuka Chemical Co., Ltd under the trade name Ajicure ®< (from Ajinomoto Fine-TechnoCo., Inc.) and under the trade name Technicure ®< (from A&C Catalysts).

[0032] The composition according to the invention further contains at least one hardener B2 for epoxy resins, where the hardener is B2 a dihydrazide selected from the group consisting of glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, 8,12-eicosadienedioic acid-1,20-dihydrazide (UDH) and 4-isopropyl-2,5-dioxoimidazolidine-1,3-di(propionohydrazide) (VDH).

[0033] Preferably, these are adipic acid dihydrazide, 8,12-eicosadienedioic acid-1,20-dihydrazide (UDH), and 4-isopropyl-2,5-dioxoimidazolidine-1,3-di(propionohydrazide) (VDH). Most preferably, they are adipic acid dihydrazide.

[0034] Suitable dihydrazides are, for example, commercially available from Otsuka Chemical Co., Ltd under the trade name Ajicure ®< (from Ajinomoto Fine-TechnoCo., Inc.) and under the trade name Technicure ®< (from A&C Catalysts).

[0035] Surprisingly, it was found that other aromatic hardeners for epoxy resins were used as hardeners B1 , alone or in combination with hardener B2 , do not lead to sufficiently high values ​​for ZSF during induction pre-hardening at 200 °C, especially 180 °C. This is evident, for example, in Table 1 and Table 2 when comparing R3 and R4 with E1-E5.

[0036] The weight ratio of hardener B1 to hardener B2 ( B1 / B2 ) is from 0.15-20.

[0037] A weight ratio of less than 0.15 is disadvantageous in that low values ​​for the CSF are obtained during induction pre-hardening at 180 °C and 200 °C, respectively. Furthermore, low values ​​for the CSF, Young's modulus, CSF, and Tg are obtained during furnace hardening. This is evident, for example, in Table 1 and Table 2 when comparing R2 with E5.

[0038] A weight ratio of more than 20 is disadvantageous in that low values ​​for the CSF are obtained during induction pre-curing at 180 °C. Furthermore, low values ​​for the IP are obtained at 23 °C and -30 °C during oven curing. This is evident, for example, in Table 1 and Table 2 when comparing R5 with E1.

[0039] Particularly preferably, the weight ratio of hardener B1 to hardener B2 ( B1 / B2) 0.3-15, preferably 0.4-10, especially 0.8-8, especially 1.1-6, especially 2-5, particularly preferably 3-4. This is advantageous in that high values ​​for ZSF are obtained during induction pre-curing at 200 °C, especially 180 °C. Furthermore, high values ​​for ZF and Young's modulus are achieved during furnace curing.

[0040] It may also be advantageous if the weight ratio of hardener B1 to hardener B2 ( B1 / B2 ) is 0.3-15, preferably 0.4-10, especially 0.5-5, especially 0.6-3, especially 0.7-2, especially 0.8-1.5, particularly preferably 0.9-1.3. This is advantageous in that it results in high values ​​for the ZSF during oven curing.

[0041] It can also be advantageous if the weight ratio of hardener B1 to hardener B2 ( B1 / B2) 0.15-8, preferably 0.2-4, especially 0.25-2, especially 0.3-1.5, especially 0.35-1, especially 0.35-0.8, particularly preferably 0.35-0.6. This results in high values ​​for IP during oven curing.

[0042] The ratio of the proportion of epoxy groups of epoxy resin A in mol / total of hardener B1 and hardener B2 in moles ( A / ( B1+B2 )), is preferably 3 - 5, in particular 3.5 - 4.5. This is advantageous in that particularly advantageous values ​​for the mechanical properties, the tensile shear strength, the Tg, and the impact peel of the cured composition as well as the tensile shear strength of the pre-cured composition are obtained in this range.

[0043] Furthermore, it may be advantageous if more than 80% by weight, preferably more than 90% by weight, in particular more than 95% by weight, particularly preferably more than 98% by weight, most preferably more than 99% by weight, based on the total weight of the heat-curing one-component epoxy resin composition, of the molecules containing hydrazide groups are derived from the hardeners B1 and B2 come from.

[0044] Furthermore, it is advantageous if the heat-curing one-component epoxy resin composition contains as little dicyandiamide as possible. If the epoxy resin composition contains dicyandiamide, the weight ratio of the sum of hardener B1 and hardener B2 to dicyandiamide (( B1+B2 ) / Dicyandiamide) ≥ 0.5, ≥ 0.75, ≥ 1, ≥ 2, ≥ 5, in particular ≥ 10, preferably ≥ 50, particularly preferably ≥ 100.

[0045] The amount of dicyandiamide is preferably less than 5 wt.%, less than 3 wt.%, less than 2 wt.%, in particular less than 1 wt.%, preferably less than 0.5 wt.%, particularly preferably less than 0.3 wt.%, most preferably less than 0.1 wt.%, based on the total weight of the epoxy resin composition. The thermosetting one-component epoxy resin composition particularly preferably contains no dicyandiamide.

[0046] Preferably, the heat-curing one-component epoxy resin composition additionally contains at least one accelerator C for epoxy resins.

[0047] Preferably, the accelerator C for epoxy resins selected from the list consisting of substituted ureas, imidazoles, imidazolines and blocked amines, in particular substituted ureas.

[0048] Preferably, these are substituted ureas of the formula (I) wherein R 1< and R 2< independently represent hydrogen atoms or monovalent alkyl radicals having 1 to 10 carbon atoms, which may further optionally comprise oxygen atoms, nitrogen atoms and / or aromatic units, or together form a divalent alkyl radical having 1 to 10 carbon atoms and which may further optionally comprise oxygen atoms, nitrogen atoms or aromatic units; R 3< and R 4< independently represent hydrogen atoms or monovalent alkyl radicals having 1 to 10 carbon atoms, which may further optionally comprise oxygen atoms or nitrogen atoms; and the index n has a value of 1 or 2.

[0049] Preferably, the substituted urea of ​​formula (I) is selected from the group consisting of p-chlorophenyl-N,N-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3,4-dichlorophenyl-N,N-dimethylurea (diuron), N-methylurea, N,N-dimethylurea, N,N'-dimethylurea, N,N,N'-trimethylurea, N,N,N',N'-tetramethylurea and derivatives thereof, wherein some or all of the methyl groups are ethyl groups instead.

[0050] Preferably, R 1< and R 2< independently of one another represent hydrogen atoms or monovalent linear or branched alkyl radicals having 1 to 10, preferably 1 to 5, more preferably 1 to 4 carbon atoms, which optionally together represent a divalent alkyl radical which forms a ring structure with the adjacent nitrogen atom and / or R 3< and R 4< independently of one another represent hydrogen atoms or monovalent linear or branched alkyl radicals having 1 to 10, preferably 1 to 5, more preferably 1 to 4 carbon atoms, which optionally together represent a divalent alkyl radical which forms a ring structure with the adjacent nitrogen atom.

[0051] Very particularly preferred substituted ureas of formula (I) are those in which R 1< and R 2< in formula (I) both represent hydrogen atoms and / or in which R 3< and R 4< both represent ethyl or methyl groups, preferably methyl groups.

[0052] Further preferred urea derivatives of formula (I) include those in which R 1< , R 2< , R 3< and R 4< in formula (I) all represent ethyl or methyl, preferably methyl groups, or in which R 1< , R 2< and R 3< represent ethyl or methyl, preferably methyl, and R 4< is a hydrogen atom, or in which R 1< and R 4< both represent hydrogen atoms and R 2< and R 3< both represent ethyl or methyl groups, preferably methyl groups.

[0053] Suitable urea derivatives are commercially available, for example, under the trade name Dyhard ®< (from AlzChem Group AG), under the trade name Omicure ®< (from CVC Thermoset Specialties), under the trade name Amicure ®< (from Evonik) and from Sigma Aldrich.

[0054] The accelerator CIn particular, a molecule with a molecular weight of less than 1000 g / mol, especially between 80 and 800 g / mol. If the molecular weight is higher, the acceleration effect is reduced and the required application quantity is significantly higher, which in turn can lead to poor mechanical properties.

[0055] The amount of accelerator C is advantageously 0.01 - 6.0 wt.%, in particular 0.02 - 4.0 wt.%, preferably 0.02 - 2.0 wt.%, based on the weight of the epoxy resin A.

[0056] The ratio of the accelerator share C in grams per mole of epoxy groups of the epoxy resin A is preferably from 0.01 - 0.5 g / mol epoxy groups, in particular 0.05 - 0.3 g / mol epoxy groups, particularly preferably 0.075 - 0.2 g / mol epoxy groups, most preferably 0.08 - 0.15 g / mol epoxy groups.

[0057] This is advantageous in that it results in higher values ​​for the CSF during induction pre-hardening and higher values ​​for the mechanical properties, CSF, and IP during furnace hardening. This can be seen, for example, in Table 1 and Table 2 when comparing E2 with E3.

[0058] The one-component thermosetting epoxy resin composition preferably contains at least one toughener D. The toughness improvers D can be solid or liquid.

[0059] In particular, the toughness improver D is selected from the group consisting of terminally blocked polyurethane polymers D1, Liquid rubbers D2 and core-shell polymers D3. The toughness improver is preferred D is selected from the group consisting of terminally blocked polyurethane polymers D1 and liquid rubbers D2.Particularly preferably, it is a terminally blocked polyurethane polymer D1.

[0060] Is the toughness improver D a terminally blocked polyurethane polymer D1.

[0061] Preferably it is a terminally blocked polyurethane polymer D1 blocked with a blocking group which splits off at a temperature above 100°C.

[0062] Phenols or bisphenols are particularly preferred as blocking groups. Preferred examples of such phenols and bisphenols are, in particular, phenol, cresol, resorcinol, pyrocatechol, cardanol (3-pentadecenylphenol (from cashew nut shell oil)), nonylphenol, phenols reacted with styrene or dicyclopentadiene, bisphenol-A, bisphenol-F, and 2,2'-diallylbisphenol-A.

[0063] The terminally blocked polyurethane prepolymer is produced from an isocyanate-terminated linear or branched polyurethane prepolymer with one or more isocyanate-reactive compounds. If several such isocyanate-reactive compounds are used, the reaction can be carried out sequentially or with a mixture of these compounds.

[0064] The reaction is preferably carried out in such a way that the one or more isocyanate-reactive compounds are used stoichiometrically or in stoichiometric excess to ensure that all NCO groups are reacted.

[0065] The polyurethane prepolymer with isocyanate end groups can be prepared from at least one diisocyanate or triisocyanate and a polymer Q PM with terminal amino, thiol or hydroxyl groups and / or from an optionally substituted polyphenol Q PP produce.

[0066] Suitable diisocyanates are aliphatic, cycloaliphatic, aromatic, or araliphatic diisocyanates, especially commercially available products such as methylenediphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), tolidine diisocyanate (TODI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), 2,5- or 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, 1,5-naphthalene diisocyanate (NDI), dicyclohexylmethyl diisocyanate (H12MDI), p-phenylene diisocyanate (PPDI), m-tetramethylxylylene diisocyanate (TMXDI), etc., as well as their dimers. HDI, IPDI, MDI, or TDI are preferred.

[0067] Suitable triisocyanates are trimers or biurets of aliphatic, cycloaliphatic, aromatic, or araliphatic diisocyanates, especially the isocyanurates and biurets of the diisocyanates described in the previous paragraph. Suitable mixtures of di- or triisocyanates can also be used.

[0068] As polymers Q PM with terminal amino, thiol or hydroxyl groups are particularly suitable polymers Q PM with two or three terminal amino, thiol or hydroxyl groups.

[0069] The polymers Q PM advantageously have an equivalent weight of 300 - 6000, in particular of 600 - 4000, preferably of 700 - 2200 g / equivalent of NCO-reactive groups.

[0070] As polymers Q PM Preferred are polyols with average molecular weights between 600 and 6000 Dalton selected from the group consisting of polyethylene glycols, polypropylene glycols, polyethylene glycol-polypropylene glycol block polymers, polybutylene glycols, hydroxyl-terminated polybutadienes, hydroxyl-terminated butadiene-acrylonitrile copolymers and mixtures thereof.

[0071] As polymers Q PMParticularly preferred are α,ω-dihydroxypolyalkylene glycols with C 2 -C 6 alkylene groups or with mixed C 2 -C 6 alkylene groups terminated with amino, thiol, or, preferably, hydroxyl groups. Particular preference is given to polypropylene glycols or polybutylene glycols. Hydroxyl-terminated polyoxybutylenes are also particularly preferred.

[0072] As a polyphenol Q PP Bis-, tris-, and tetraphenols are particularly suitable. These include not only pure phenols, but also optionally substituted phenols. The type of substitution can be very diverse. In particular, this refers to substitution directly at the aromatic nucleus to which the phenolic OH group is bonded. Phenols also include not only mononuclear aromatics, but also polynuclear or condensed aromatics or heteroaromatics, which have the phenolic OH group directly attached to the aromatic or heteroaromatic ring.

[0073] In a preferred embodiment, the polyurethane prepolymer is made from at least one diisocyanate or triisocyanate and from a polymer Q PM with terminal amino, thiol or hydroxyl groups. The polyurethane prepolymer is prepared in a manner known to the polyurethane expert, in particular by adding the diisocyanate or triisocyanate in a stoichiometric excess with respect to the amino, thiol or hydroxyl groups of the polymer. Q PM is used.

[0074] The polyurethane prepolymer with isocyanate end groups preferably has an elastic character. It preferably exhibits a glass transition temperature (Tg) of less than 0°C.

[0075] The toughener D can be a liquid rubber D2 This could be, for example, a carboxyl- or epoxy-terminated polymer.

[0076] In a first embodiment, this liquid rubber can be a carboxyl- or epoxy-terminated acrylonitrile / butadiene copolymer or a derivative thereof. Such liquid rubbers are commercially available, for example, under the names Hypro / Hypox ®< CTBN and CTBNX and ETBN from Emerald Performance Materials. Particularly suitable derivatives are elastomer-modified prepolymers containing epoxy groups, such as those commercially marketed under the Polydis ®< product line, in particular from the Polydis ®< 36.. product line, by Struktol ®< (Schill+Seilacher Group, Germany) or under the Albipox product line (Evonik, Germany).

[0077] In a second embodiment, this liquid rubber can be a polyacrylate liquid rubber that is fully miscible with liquid epoxy resins and only separates into microdroplets upon curing of the epoxy resin matrix. Such polyacrylate liquid rubbers are available from Dow, for example, under the designation 20208-XPA.

[0078] Of course, mixtures of liquid rubbers can also be used, in particular mixtures of carboxyl- or epoxy-terminated acrylonitrile / butadiene copolymers or derivatives thereof.

[0079] The toughness improver D In a third embodiment, a core-shell polymer D3Core-shell polymers consist of an elastic core polymer and a rigid shell polymer. Particularly suitable core-shell polymers consist of a core made of elastic acrylate or butadiene polymer encased in a rigid shell of a rigid thermoplastic polymer. This core-shell structure forms either spontaneously through demixing of a block copolymer or is predetermined by the polymerization process as a latex or suspension polymerization with subsequent grafting. Preferred core-shell polymers are so-called MBS polymers, which are commercially available under the trade names Clearstrength™ from Arkema, Paraloid™ from Dow, or F-351™ from Zeon.

[0080] Preferably, the proportion of toughener is D, especially on terminally blocked polyurethane polymer D1,15-45 wt.%, in particular 20-40 wt.%, in particular 22.5-35 wt.%, in particular 25-35 wt.%, particularly preferably 27.5-32.5 wt.%, based on the total weight of the heat-curing one-component epoxy resin composition.

[0081] This is advantageous in that it results in high values ​​for IP and simultaneously high values ​​for ZF, E-modulus and ZSF.

[0082] In a further preferred embodiment, the composition additionally contains at least one filler F. These are preferably mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or ground), dolomite, quartz, silicas (pyrogenic or precipitated), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic spheres, hollow glass spheres, organic hollow spheres, glass spheres, and color pigments. Particularly preferred fillers are selected from the group consisting of calcium carbonate, calcium oxide, and pyrogenic silicas.

[0083] Advantageously, the total proportion of the total filler is F 5 - 40% by weight, preferably 10 - 30% by weight, based on the total weight of the heat-curing one-component epoxy resin composition.

[0084] In a further preferred embodiment, the composition additionally contains at least one reactive diluent carrying epoxy groups G. Such reactive diluents are known to those skilled in the art. Preferred examples of reactive diluents containing epoxy groups are: Glycidyl ethers of monofunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C 4 - C 30 alcohols, e.g. butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ether, trimethoxysilyl glycidyl ether, etc. Glycidyl ethers of difunctional saturated or unsaturated, branched or unbranched, cyclic or open-chain C 2 - C 30 alcohols, e.g. ethylene glycol, butanediol, hexanediol, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, etc. Glycidyl ethers of tri- or polyfunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain alcohols such as epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythrol or polyglycidyl ethers of aliphatic polyols such as sorbitol, glycerin, trimethylolpropane, etc.Glycidyl ethers of phenol and aniline compounds such as phenyl glycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, nonylphenol glycidyl ether, 3-n-pentadecenyl glycidyl ether (from cashew nut shell oil), N,N-diglycidylaniline etc. Epoxidized amines such as N,N-diglycidylcyclohexylamine etc. Epoxidized mono- or dicarboxylic acids such as neodecanoic acid glycidyl ester, methacrylic acid glycidyl ester, benzoic acid glycidyl ester, phthalic acid, tetra- and hexahydrophthalic acid diglycidyl esters, diglycidyl esters of dimeric fatty acids etc. Epoxidized di- or trifunctional, low to high molecular weight polyether polyols such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether etc.

[0085] Particularly preferred are hexanediol diglycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, polypropylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether.

[0086] Advantageously, the total proportion of the epoxy group-bearing reactive diluent is G 0.1 - 15% by weight, preferably 0.1 - 5% by weight, particularly preferably 0.1 - 2% by weight, particularly preferably 0.2 - 1% by weight, based on the total weight of the heat-curing one-component epoxy resin composition.

[0087] The composition may comprise further components, in particular catalysts, stabilizers, in particular heat and / or light stabilizers, thixotropic agents, plasticizers, solvents, mineral or organic fillers, blowing agents, dyes and pigments, corrosion inhibitors, surfactants, defoamers and adhesion promoters.

[0088] Phenol alkylsulfonic acid esters or benzenesulfonic acid N-butylamide, which are commercially available as Mesamoll ®< or Dellatol BBS from Bayer, are particularly suitable as plasticizers.

[0089] Suitable stabilizers are, in particular, optionally substituted phenols such as BHT or Wingstay ®< T (Elikem), sterically hindered amines or N-oxyl compounds such as TEMPO (Evonik).

[0090] A particularly preferred one-component epoxy resin composition comprises: 10 - 60 wt.%, in particular 30 - 60 wt.%, based on the total weight of the epoxy resin composition, epoxy resin A with an average of more than one epoxy group per molecule; preferably 50-100 wt.%, in particular 80-100 wt.%, of the epoxy resin A an epoxy liquid resin and at 0-30 wt.%, in particular 0-20 wt.%, of the epoxy resin A an epoxy solid resin; at least one hardener B1 for epoxy resins, where the hardener is B1is an aromatic dicarboxylic acid dihydrazide, in particular isophthalic acid dihydrazide and / or terephthalic acid dihydrazide, preferably isophthalic acid dihydrazide; at least one hardener B2 for epoxy resins, where the hardener is B2 a dihydrazide selected from the group consisting of glutaric acid dihydrazide, adipic acid dihydrazide, pimelic acid dihydrazide, 8,12-eicosadiene dioic acid 1,20-dihydrazide, and 4-isopropyl-2,5-dioxoimidazolidine 1,3-di(propionohydrazide), in particular adipic acid dihydrazide, 8,12-eicosadiene dioic acid 1,20-dihydrazide, and 4-isopropyl-2,5-dioxoimidazolidine 1,3-di(propionohydrazide), most preferably adipic acid dihydrazide; preferably 0.01-6.0 wt.%, in particular 0.02-4.0 wt.%, preferably 0.02-2.0 wt.%, based on the weight of the epoxy resin A, of at least one accelerator Cfor epoxy resins selected from the list consisting of substituted ureas, imidazoles, imidazolines and blocked amines, in particular substituted ureas: preferably 15-45 wt.%, in particular 20-40 wt.%, in particular 22.5-35 wt.%, in particular 25-35 wt.%, particularly preferably 27.5-32.5 wt.%, based on the total weight of the heat-curing one-component epoxy resin composition, of at least one toughener D , is selected from the group consisting of terminally blocked polyurethane polymers D1 , liquid rubbers D2 and core-shell polymers D3 , preferably terminally blocked polyurethane polymers D1: preferably 5 - 40% by weight, preferably 10 - 30% by weight, based on the total weight of the thermosetting one-component epoxy resin composition, of a filler Fselected from the group consisting of calcium carbonate, calcium oxide and pyrogenic silicas; preferably 0.1 - 15% by weight, preferably 0.1 - 5% by weight, particularly preferably 0.1 - 2% by weight, particularly preferably 0.2 - 1% by weight, based on the total weight of the heat-curing one-component epoxy resin composition, of an epoxy group-bearing reactive diluent G.

[0091] The weight ratio of hardener B1 to hardener B2 (B1 / B2) is from 0.15 - 20, preferably 0.3-15, preferably 0.4-10, in particular 0.8-8, in particular 1.1-6, in particular 2-5, particularly preferably 3-4.

[0092] The ratio of the proportion of epoxy groups of the epoxy resin A in mol / total of hardener B1 and hardener B2 in moles ( A / ( B1+B2 )), is preferably 3 - 5, in particular 3.5 - 4.5.

[0093] The ratio of the accelerator share Cin grams per mole of epoxy groups of the epoxy resin A is preferably from 0.01 - 0.5 g / mol epoxy groups, in particular 0.05 - 0.3 g / mol epoxy groups, particularly preferably 0.075 - 0.2 g / mol epoxy groups, most preferably 0.08 - 0.15 g / mol epoxy groups.

[0094] Furthermore, it may be advantageous if the preferred one-component epoxy resin composition consists of more than 80% by weight, preferably more than 90% by weight, in particular more than 95% by weight, particularly preferably more than 98% by weight, most preferably more than 99% by weight, based on the total weight of the epoxy resin composition, of the aforementioned components.

[0095] Examples of particularly preferred compositions are E2 and E7, especially E7, in Table 1.

[0096] It is advantageous if the epoxy resin composition according to the invention has a viscosity at 25°C of 500-3500 Pa*s, in particular 1000-3000 Pa*s, preferably 1500-2500 Pa*s, particularly preferably 2000-2500 Pa*s, in particular measured with an oscillatory rheometer using a plate-to-plate geometry with the following parameters: 5 Hz, 1 mm measuring gap, 25 mm plate-to-plate diameter, 1% deformation. This is advantageous in that it ensures good applicability.

[0097] It has been shown that the described heat-curing, one-component epoxy resin compositions are particularly suitable for use as one-component heat-curing adhesives, in particular as heat-curing, one-component bodyshell adhesives in vehicle construction. Such a one-component adhesive has a wide range of applications. Such adhesives are required for bonding heat-stable materials. Heat-stable materials are understood to be materials that are dimensionally stable at a curing temperature of 100–220°C, preferably 120–200°C, at least during the curing time. In particular, these are metals and plastics such as ABS, polyamide, polyphenylene ether, composite materials such as SMC, unsaturated polyesters, GRP, epoxy or acrylate composite materials. The preferred application is one in which at least one material is a metal.A particularly preferred application is the bonding of identical or dissimilar metals, especially in body shells in the automotive industry. The preferred metals are primarily steel, especially electrogalvanized, hot-dip galvanized, oil-treated, Bonazink-coated, and post-phosphated steel, as well as aluminum, especially in the variants typically found in automotive construction.

[0098] With an adhesive based on a heat-curing one-component composition according to the invention, it is possible to ensure sufficient adhesion of the bonded substrates without additional metal joining techniques after pre-curing, in particular 30 - 60 seconds at 180 - 200 °C, preferably 180 °C, upon further heating to 180 °C.

[0099] Such an adhesive is used particularly in applications that do not utilize metal joining techniques, especially thermal and mechanical metal joining techniques, particularly preferably welding and riveting. These applications preferably involve first pre-curing the adhesive, especially for 60 seconds at 180-200°C, preferably 180°C, followed by further heating to at least 160°C, especially at least 180°C, and subsequent complete curing of the adhesive, especially after cooling the pre-cured adhesive to below 60°C.

[0100] Such an adhesive is in particular first brought into contact with the materials to be bonded at a temperature of between 10°C and 80°C, in particular between 10°C and 60°C, then pre-cured and later cured, as described above.

[0101] A further aspect of the present invention relates to a method for bonding heat-stable substrates, which comprises the steps: i) Applying a heat-curing one-component epoxy resin composition as previously described in detail to the surface of a heat-stable substrate S1, in particular a metal; ii) contacting the applied heat-curing one-component epoxy resin composition with the surface of another heat-stable substrate S2,in particular a metal; iii) heating the composition to a temperature of 160-220°C, in particular 170-200°C, preferably 175-190°C, for 10-120 seconds, in particular 20-80 seconds, preferably 30-60 seconds. iv) heating the composition to a temperature of 100-220°C, in particular 120-200°C, preferably between 140 and 190°C, particularly preferably between 150 and 180°C; wherein between step iii) and step iv) the composition reaches a temperature of less than 100°C, in particular less than 60°C, preferably 50-20°C. Preferably, there is a time period of more than 15 minutes, in particular more than 20 minutes, preferably ≥ than 30 minutes, in particular 30 to 300 minutes, between step iii) and step iv).

[0102] The substrate S2 consists of the same or a different material as the substrate S1. The substrates S1 and / or S2are in particular the previously mentioned metals and plastics.

[0103] Preferably, the heating in step iii) is heating by induction.

[0104] Preferably, in step iv) heating the composition to a temperature of 100-220°C, in particular 120-200°C, preferably between 140 and 190°C, particularly preferably between 150 and 180°C, the composition is left at the aforementioned temperature for 10 min - 6 h, 10 min - 2 h, 10 min - 60 min, 10 min - 30 min, 10 min - 20 min, particularly preferably 10 min - 15 min.

[0105] Such a process for bonding heat-stable materials results in a bonded article. Such an article is preferably a vehicle or a part of a vehicle.

[0106] A further aspect of the present invention therefore relates to a bonded article obtained from the aforementioned process. Furthermore, the compositions according to the invention are suitable not only for automotive construction but also for other fields of application. Particular mention should be made of related applications in the construction of means of transport such as ships, trucks, buses, or rail vehicles, or in the construction of consumer goods such as washing machines.

[0107] The materials bonded by means of a composition according to the invention are used at temperatures between typically 120°C and -40°C, preferably between 100°C and -40°C, in particular between 80°C and -40°C.

[0108] A particularly preferred use of the heat-curing one-component epoxy resin composition according to the invention is its use as a heat-curing one-component bodyshell adhesive in vehicle construction or as a stiffening compound or as a foamable, heat-curing composition for reinforcement in cavities of structural components and reinforcing elements.

[0109] A further aspect of the present invention relates to a cured epoxy resin composition as obtained by heating a thermosetting one-component epoxy resin composition as previously described in detail.

[0110] The compositions according to the invention particularly preferably have the following properties: After pre-curing for 35 seconds at 180 °C:ZSF, measured as described in the experimental part at a temperature of 180 °C, of ​​> 2.3 MPa, in particular ≥ 2.4 MPa, in particular ≥ 2.6 MPa, in particular ≥ 2.9 MPa, particularly preferably ≥ 3 MPa. and / or After curing for 40 minutes at 180 °C:ZF, measured as described in the experimental part, of ≥ 30 MPa, in particular ≥ 35 MPa, in particular ≥ 40 MPa; BD, measured as described in the experimental part, of 5 - 20%; Young's modulus, measured as described in the experimental part, of ≥ 1000 MPa, in particular ≥ 1250 MPa, in particular ≥ 1500 MPa, particularly preferably ≥ 1750 MPa; Tg, measured as described in the experimental part, of ≥ 130 °C, in particular ≥ 140 °C, in particular ≥ 150 °C, particularly preferably ≥ 160 °C; CSF, measured as described in the experimental part, of ≥ 30 MPa, in particular ≥ 31 MPa, in particular ≥ 32 MPa, particularly preferably ≥ 33 MPa; IP at 23 °C, measured as described in the experimental part, of ≥ 16 N / mm, in particular ≥ 18 N / mm, in particular ≥ 20 N / mm, particularly preferably ≥ 22 N / mm; IP at -30 °C, measured as described in the experimental part, of ≥ 7 N / mm, in particular ≥ 10 N / mm, particularly preferably ≥ 15 N / mm. Examples

[0111] The following are some examples which further illustrate the invention but are not intended to limit the scope of the invention in any way. Production of a toughener (" D-1 ")

[0112] 150 g of Poly-THF 2000 (OH number 57 mg / g KOH) and 150 g of Liquiflex H (OH number 46 mg / g KOH) were dried for 30 minutes under vacuum at 105°C. After the temperature was reduced to 90°C, 61.5 g of IPDI and 0.14 g of dibutyltin dilaurate were added. The reaction was continued under vacuum at 90°C until the NCO content remained constant at 3.10% after 2.0 h (calculated NCO content: 3.15%). Subsequently, 96.1 g of cardanol was added as a blocking agent. Stirring was continued at 105°C under vacuum until no more free NCO could be detected. The product was thus used as a toughener. D-1 used. A-resin liquid Epoxy liquid resin, DER 331 (bisphenol A diglycidyl ether), Dow RD Reactive diluent, hexanediol glycidyl ether, Denacol EX-212, Nagase America ADH Adipic acid dihydrazide, Technicure ADH-J, A&C Catalysts Inc. IDH Isophthalic dihydrazide, Technicure IDH-J, A&C Catalysts Inc. DDS 3,3' Diaminodiphenylsulfone, Aradur-9719-1, Huntsman C1 N,N-dimethylurea (=1,1-dimethylurea), n = 1, R 1< = H, R 2< = R 3< = CH 3 , Sigma-Aldrich, Switzerland Dicy Dicyandiamide, Dyhard 100SF, AlzChem filler Mixture of calcium carbonate, calcium oxide, fumed silica Poly-THF 2000 (difunctional polybutylene glycol) (OH equivalent weight = approx. 1000 g / OH equivalent), BASF Liquiflex H (hydroxyl-terminated polybutadiene) (OH equivalent weight = approx. 1230 g / OH equivalent), Krahn Isophoron-diisocyanat (= " IPDI "), Evonik Cardolite NC-700 (cardanol, meta-substituted alkenyl mono-phenol), Cardolite

[0113] Raw materials used. Preparation of the compositions

[0114] The reference compositions R1 - R5 and the inventive compositions E1 to E8 were prepared according to the information in Table 1. The quantities in Table 1 are in parts by weight.

[0115] The ratio of the proportion of epoxy groups of the epoxy resin A in mol / total of hardener B1 and hardener B2 in moles ( A / ( B1 + B2 )) is called "DH index" in Table 1 and is expressed in [mol EP groups / mol ( B1+B2 )] is specified.

[0116] The ratio of the accelerator share C in grams per mole of epoxy groups of the epoxy resin A is called "C-index" in Table 1 and is given in [g accelerator / mol EP groups].

[0117] The weight ratio of hardener B1 to hardener B2is shown in Table 1 as "( B1 / B2 )" is shown. Test methods: Tensile strength, elongation at break and modulus of elasticity (DIN EN ISO 527)

[0118] An adhesive sample was pressed between two sheets of Teflon paper to a thickness of 2 mm. After curing for 40 minutes at 180°C, the Teflon paper was removed and the test specimens were punched out according to DIN standards. The test specimens were measured under standard conditions at a tensile speed of 2 mm / min. The tensile strength (TFS), elongation at break, and the modulus of elasticity (0.05-0.25%) were determined according to DIN EN ISO 527 at a temperature of 23°C. Tensile shear strength (TSF) (DIN EN 1465), curing IV (inductive pre-curing Tmax 180°C / 200°C

[0119] Cleaned and re-oiled with Anticorit PL 3802-39S, test panels made of Elo H420 steel (1.5 mm thick) were bonded to a 25 x 10 mm bonding surface using glass beads as spacers in a layer thickness of 0.3 mm. The samples were then heated using induction heating (laboratory induction system EW2, manufacturer IFF GmbH, Germany) to a temperature of 180 °C or 200 °C within 10 seconds and held at that temperature for 35 seconds. The samples were then heated to a temperature of 150 °C or 200 °C using compressed air within 10 seconds, and then allowed to cool to 23 °C.

[0120] The tensile shear strength was determined on a tensile machine at a tensile speed of 10 mm / min in a triple determination according to DIN EN 1465 at a temperature of 23 °C ("TeP @ 23°C [MPa]") and at a temperature of 180 °C ("TeP @ 180°C [MPa]"), respectively. Lap shear strength (LSH) (DIN EN 1465), curing OH (oven curing) (40 min / 180°C)

[0121] Test panels made of steel Elo H420 (thickness 1.5 mm) that had been cleaned and re-oiled with Anticorit PL 3802-39S were bonded to an adhesive surface of 25 x 10 mm with glass beads as spacers in a layer thickness of 0.3 mm and cured for 10 min at 140°C oven temperature.

[0122] The tensile shear strength was determined on a tensile machine at a tensile speed of 10 mm / min in a triple determination according to DIN EN 1465 at a temperature of 23 °C. Impact peel resistance (IP 23°C / -30 °C) (according to ISO 11343)

[0123] The test specimens were manufactured using the adhesive and steel DC04+ZE, measuring 90 x 20 x 0.8 mm. The bonding area was 20 x 30 mm, with a layer thickness of 0.3 mm, and glass beads were used as spacers. The specimens were cured for 10 minutes at an oven temperature of 140°C. The impact peel strength was measured in triplicate at 23°C and at -30°C, respectively, using a Zwick 450 impact pendulum. The impact peel strength is expressed as the average force in N / mm under the measurement curve from 25% to 90% according to ISO 11343. viscosity

[0124] Viscosity measurements of the adhesives were performed 1 day after production on an Anton Paar MCR 101 rheometer using an oscillatory plate-to-plate geometry at a temperature of 25°C with the following parameters: 5 Hz, 1 mm measuring gap, 25 mm plate-to-plate diameter, and 1% deformation. The measured compositions R1 - R5 and E1 to E8 all exhibited a viscosity of 1500 - 2500 Pa*s. Table 1 R1 R2 R3 R4 R5 E1 E2 E3 E4 E5 E6 E2 E7 E8 A-resin liquid 52.2 48.3 46.0 46.6 47.6 47.7 47.8 47.9 47.9 48.1 51.6 47.8 43.9 35.9 RD 0.9 0.9 0.8 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 D1 23.9 22.1 21.1 21.4 21.9 21.9 21.9 21.9 22.0 22.1 17.3 21.9 26.6 36.3 Dicy 4.4 IDH 12.68 11.42 9.53 9.55 6.38 3.20 10.28 9.53 8.77 7.19 ADH 11.52 2.78 1.14 2.85 2.86 5.72 8.61 3.08 2.85 2.63 2.15 DDS 15.65 11.88 C1 0.23 0.21 0.2 0.21 0.21 0.21 0.21 - 0.21 0.21 0.23 0.21 0.2 0.15 Fillers 18.37 16.97 16.25 16.23 16.71 16.73 16.81 16.89 16.89 16.88 16.61 16.81 17 17.41 Sum: 100 100 100 100 100 100 100 100 100 100 100 100 100 100 (B1 / B2) 10.0 3.3 3.3 1.1 0.4 3.3 3.3 3.3 3.3 DH index 5.5 4 4 4 4 4 4 4 4 4 4 4 4 4 C-Index 0.8 0.8 0.8 0.8 0.8 0.8 0.8 - 0.8 0.8 0.8 0.8 0.8 0.8 Table 2 R1 R2 R3 R4 R5 E1 E2 E3 E4 E5 E6 E2 E7 E8 IV, Tmax 180°C ZSF @ 23°C [MPa] 8.60 26.40 0 3.90 22.40 27.50 26.50 9.40 24.70 24.80 27.70 26.50 23.60 15.60 ZSF @ 180°C [MPa] 1.60 2.43 0 0.18 4.47 3.80 3.80 3.00 2.46 2.70 3.30 3.80 2.84 2.33 IV, Tmax 200°C ZSF @ 23°C [MPa] 0.00 10.80 0 2.30 0.70 6.87 14.10 2.32 16.20 16.30 17.20 14.10 13.20 4.35 ZSF @ 180°C [MPa] 0.00 2.30 0 0.40 0.00 2.92 3.19 2.69 2.92 2.44 3.56 3.19 3.00 2.33 OH (40 min / 180°C) IF [MPa] 30 34.20 30 36 46 45 43 21 37 38 47 43 34 24 BD [%] 10% 65% 7% 8% 6% 6% 6% 4% 6% 6% 5% 6% 8% 18% Young's modulus [MPa] 1330 1520 1480 1650 2061 1846 2054 1222 1697 1820 2144 2054 1487 860 Tg DMTA [°C] 118 124 121 121 151 150 145 165 138 130 150 145 142 131 ZSF 23°C [MPa] 32.8 33.8 29.5 32.7 32.20 31.60 33.20 26.70 33.70 32.50 32.90 33.20 31.00 25.30 IP 23°C [N / mm] 40.8 26.6 25.8 28.5 15.5 16.2 18.02 9.5 20.7 22.7 13.9 18.02 22.7 30.1 IP -30°C [N / mm] 33.6 17.4 13.3 12.6 5.2 6.8 8.7 7.2 12.4 15.3 4.4 8.7 15.1 31.3

Claims

1. Thermosetting one-component epoxy resin composition comprising a) at least one epoxy resin A having an average of more than one epoxy group per molecule; b) at least one curing agent B1 for epoxy resins, where the curing agent B1 is an aromatic dicarboxylic dihydrazide, especially isophthalic dihydrazide and / or terephthalic dihydrazide, preferably isophthalic dihydrazide; and c) at least one curing agent B2 for epoxy resins, where the curing agent B2 is a dihydrazide selected from the group consisting of glutaric dihydrazide, adipic dihydrazide, pimelic dihydrazide, 8,12-eicosadienedioic acid 1,20-dihydrazide and 4-isopropyl-2,5-dioxoimidazolidine-1,3-di(propionohydrazide), especially adipic dihydrazide; and where the weight ratio of curing agent B1 to curing agent B2 (B1 / B2) is 0.15-20.

2. Thermosetting one-component epoxy resin composition according to Claim 1, characterized in that the weight ratio of curing agent B1 to curing agent B2 (B1 / B2) is 0.3-15, preferably 0.4-10, especially 0.8-8, especially 1.1-6, especially 2-5, especially preferably 3-4.

3. Thermosetting one-component epoxy resin composition according to either of the preceding claims, characterized in that the ratio of the proportion of epoxy groups of the epoxy resin A in mol / sum total of curing agent B1 and curing agent B2 in mol (A / (B1+B2)) is 3-5, especially 3.5-4.5.

4. Thermosetting one-component epoxy resin composition according to any of the preceding claims, characterized in that the thermosetting one-component epoxy resin composition additionally includes at least one accelerator C selected from the list consisting of substituted ureas, imidazoles, imidazolines and blocked amines, especially substituted ureas.

5. Thermosetting one-component epoxy resin composition according to Claim 4, characterized in that the ratio of the proportion of accelerator C in grams per mole of epoxy groups of the epoxy resin A is 0.01-0.5 g / mol of epoxy groups, especially 0.05-0.3 g / mol of epoxy groups, more preferably 0.075-0.2 g / mol of epoxy groups, most preferably 0.08-0.15 g / mol of epoxy groups.

6. Thermosetting one-component epoxy resin composition according to any of the preceding claims, characterized in that the thermosetting one-component epoxy resin composition additionally includes at least one toughness improver D selected from the group consisting of terminally blocked polyurethane polymers D1, liquid rubbers D2 and core-shell polymers D3, preferably a terminally blocked polyurethane polymer D1.

7. Thermosetting one-component epoxy resin composition according to Claim 6, characterized in that the proportion of the at least one toughness improver D, especially of the terminally blocked polyurethane polymer D1, is 15-45% by weight, especially 20-40% by weight, especially 22.5-35% by weight, especially 25-35% by weight, more preferably 27.5-32.5% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

8. Thermosetting one-component epoxy resin composition according to any of the preceding claims, characterized in that the thermosetting one-component epoxy resin composition has a viscosity at 25°C of 500-3000 Pa*s, especially 1000-2500 Pa*s, preferably 1000-2000 Pa*s, especially measured with a rheometer in oscillation using a plate-plate geometry with the following parameters: 5 Hz, measurement gap 1 mm, plate-plate diameter 25 mm, 1% deformation.

9. Thermosetting one-component epoxy resin composition according to any of the preceding claims, characterized in that the proportion of the epoxy resin A is 10-60% by weight, especially 30-60% by weight, especially 40-55% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

10. Use of a thermosetting one-component epoxy resin composition according to any of Claims 1 to 9 as one-component thermosetting adhesive, especially as thermosetting one-component bodywork adhesive in motor vehicle construction.

11. Method of bonding heat-stable substrates, comprising the steps of i) applying a thermosetting one-component epoxy resin composition according to any of Claims 1 to 9 to the surface of a heat-stable substrate S1, especially of a metal; ii) contacting the thermosetting epoxy resin composition applied with the surface of a further heat-stable substrate S2, especially of a metal; iii) heating the composition to a temperature of 160-220°C, especially of 170-200°C, preferably of 175-190°C, for 10-120 seconds, especially for 20-80 seconds, preferably for 30-60 seconds, iv) heating the composition to a temperature of 100-220°C, especially of 120-200°C, preferably between 140 and 190°C, more preferably between 150 and 180°C; where the composition reaches a temperature between step iii) and step iv) of less than 100°C, especially less than 60°C, preferably 50-20°C; in which the substrate S2 consists of the same material as or a different material from the substrate S1.

12. Method according to Claim 11, wherein there is a period of time between step iii) and step iv) of more than 15 minutes, especially more than 20 minutes, preferably ≥ 30 minutes, especially 30 to 300 minutes.

13. Method according to Claim 11 or 12, wherein the heating in step iii) is heating by induction.

14. Method according to Claim 11 to 13, wherein, in step iv) of heating the composition to a temperature of 100-220°C, especially of 120-200°C, preferably between 140 and 190°C, more preferably between 150 and 180°C, the composition is left at the aforementioned temperature for 10 min - 6 h, 10 min - 2 h, 10 min - 60 min, 10 min - 30 min, 10 min - 20 min, more preferably 10 min - 15 min.

15. Adhesive-bonded article obtained from a process according to any of Claims 11 to 14.