Heat curing epoxy resin composition suitable for low curing temperature with good storage stability

Description

1 / 29 Heat-curing epoxy resin composition suitable for low-temperature curing with good storage stability. Technical field

[0001] The invention relates to the field of one-component thermosetting epoxy resin compositions, especially for use as a bodywork adhesive. State of the art

[0002] Thermosetting epoxy resin compositions have been known for a long time. Efforts have been made for some time to remedy or at least significantly reduce the major disadvantage of epoxy resin compositions, namely their brittleness, the effect of which is that the cured epoxy resin composition cracks or is destroyed under impact stress. Attempts have been made to do this by adding impact modifiers or by chemically modifying epoxy resins.

[0003] An important field of application for thermosetting epoxy resin compositions is in the construction of motor vehicles, especially in bodywork bonding. After application of the epoxy resin composition, the bodywork is heated in a cathodic electrodeposition oven, which cures the thermosetting epoxy resin composition. Document WO 2019081581 A1 describes thermosetting epoxy resin compositions for use as a bodywork adhesive and for the production of structural foams.

[0004] To enable rapid curing, accelerators can be used in conjunction with heat-activated curing agents for epoxy resins. Examples of known categories of accelerators include latent imidazoles and amine boron trifluoride complexes.

[0005] However, efforts are underway in the market to lower the temperature of cathodic electrodeposition coating furnaces. Thus, there is a great need in the market for thermosetting epoxy resin compositions that cure even at relatively low temperatures, or Petition 870250093108, dated 10 / 10 / 2025, p. 13 / 47 2 / 29 that is, at a temperature of 130 to 140°C, even after a short period of time, typically 10 to 15 minutes. If, for example, aromatic ureas, which are much more reactive due to their structure, are used for this purpose, this leads to major problems in the storage stability of thermosetting epoxy resin compositions. There is therefore a need for one-component thermosetting epoxy resin compositions that, on the one hand, cure at lower temperatures, but have sufficient storage stability. Summary of the invention

[0006] It is therefore an objective of the present invention to provide storage-stable thermosetting epoxy resin compositions that have sufficient mechanical properties, especially shear strength and impact performance, after shorter curing times at lower temperatures, especially 10 minutes at 140°C.

[0007] Surprisingly, this objective was achieved by a one-component thermosetting epoxy resin composition according to claim 1. This epoxy resin composition has particularly good usability as a one-component thermosetting adhesive, especially as a one-component thermosetting bodywork adhesive in motor vehicle construction. Ways to implement the invention

[0008] The present invention relates to one-component thermosetting epoxy resin compositions 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 B for epoxy resins, wherein the curing agent B is a dihydrazide, preferably selected from the group consisting of aromatic dicarboxylic dihydrazide B1 and aliphatic dicarboxylic dihydrazide B2; and c) at least one accelerator C for at least one healing agent B, Petition 870250093108, dated 10 / 10 / 2025, p. 14 / 47 3 / 29 which is an imidazolium salt of formula (V): R5 in what R1 is an organic radical with 1 to 20 C atoms. R2, R3, R4, and R5 are each either a hydrogen atom or an organic radical with 1 to 20 carbon atoms. X is an anion and en is 1, 2 or 3, preferably 1;

[0009] The imidazolium salt of formula (V) is selected from 1-Ethyl-3-methylimidazolium ethyl sulfate, 1-Ethyl-3-methylimidazolium diethyl phosphate, 1-Butyl-3-methylimidazolium chloride and 1-Ethyl-3-methylimidazolium acetate, more preferably 1-Ethyl-3-methylimidazolium ethyl sulfate.

[0010] The molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 6-120, preferably 10-100, more preferably 12-75.

[0011] In this document, the use of the term independently in connection with substituents, radicals or groups should be interpreted in such a way that substituents, radicals or groups with the same designation in the same molecule may occur simultaneously with different meanings.

[0012] The prefix poly in names of substances such as polyol, polyisocyanate, polyether or polyamine in this document indicates that the respective substance, from a formal point of view, contains more than one of the functional groups that occur in its name per molecule.

[0013] In this document, molecular weight is understood to mean the molar mass (in grams per mole) of a molecule. Average molecular weight is understood to be the number-average molecular weight of a mixture. Petition 870250093108, dated 10 / 10 / 2025, page 15 / 47 4 / 29 oligomeric or polymeric molecules, which is typically determined by GPC comparison with polystyrene as a standard.

[0014] A primary hydroxyl group refers to an OH group bonded to a carbon atom with two hydrogens.

[0015] In this document, the term primary amino group refers to an NH2 group bonded to an organic radical, while the term secondary amino group refers to an NH group bonded to two organic radicals that may also be part of a ring together. Consequently, an amine with a primary amino group is called a primary amine, one with a secondary amino group is called a secondary amine, and one with a tertiary amino group is called a tertiary amine.

[0016] In this document, ambient temperature refers to a temperature of 23°C.

[0017] Epoxy resin A with an average of more than one epoxy group per molecule is preferably a liquid epoxy resin or a solid epoxy resin. The term solid epoxy resin is well known to one skilled in the art of epoxy and is used in contrast to liquid epoxy resins. The glass transition temperature of solid resins is above room temperature, meaning that they can be milled at room temperature to provide free-flowing powders.

[0018] Preferred epoxy resins have formula (II) (II)

[0019] The substituents R' and R'' here are independently H or CH3.

[0020] In solid epoxy resins, the s index has a value > 1.5, especially from 2 to 12.

[0021] These solid epoxy resins are marketed, for example, by Dow, Huntsman and Hexion. Petition 870250093108, dated 10 / 10 / 2025, page 16 / 47 5 / 29

[0022] Compounds of formula (II) with an s index of 1 to 1.5 are referred to as semi-solid epoxy resins by those skilled in the art. For the present invention, these are also considered solid resins. However, strictly speaking solid epoxy resins are preferred, i.e., where the s index has a value > 1.5.

[0023] In liquid epoxy resins, the s index has a value less than 1. Preferably, s has a value less than 0.2.

[0024] Preference is thus given to 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) or DER™ 331 or DER™ 330 (Dow) or Epikote 828 (Hexion).

[0025] Other suitable epoxy resins A are called epoxy novolaks. More particularly, these are phenol or cresol epoxy novolaks.

[0026] These epoxy resins are commercially available under the trade names EPN or ECN and Tactix® from Huntsman or the DEN™ product series from Dow Chemical.

[0027] Epoxy resin A is preferably an epoxy resin of formula (II), especially a liquid epoxy resin of formula (II).

[0028] In a particularly preferred embodiment, the one-component thermosetting epoxy resin composition contains at least one liquid epoxy resin of formula (II) with s < 1, especially less than 0.2, and at least one solid epoxy resin of formula (II) with s > 1.5, especially from 2 to 12.

[0029] The proportion of epoxy resin A is preferably 10-60% by weight, more preferably 30-60% by weight, most preferably 40-55% by weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0030] It is even more advantageous when 50-100% by weight, especially 80-100% by weight of epoxy resin A is a liquid epoxy resin mentioned above.

[0031] It is even more advantageous when 0-30% by weight, especially 0 Petition 870250093108, dated 10 / 10 / 2025, page 17 / 47 6 / 29 20% by weight, more preferably 5-15% by weight, of epoxy resin A is a solid epoxy resin mentioned above.

[0032] The composition of the invention also contains at least one curing agent B for epoxy resins. Curing agent B is a dihydrazide, which is preferably selected from the group consisting of aromatic dicarboxylic dihydrazide B1 and aliphatic dicarboxylic dihydrazide B2.

[0033] If curing agent B is an aromatic dicarboxylic dihydrazide B1, it is preferably selected from the group consisting of isophthalic dihydrazide and / or terephthalic dihydrazide, preferably isophthalic dihydrazide.

[0034] Suitable dihydrazides are commercially available, for example, 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] Preferably, the curing agent B is an aliphatic dicarboxylic dihydrazide B2, preferably selected from the group consisting of glutaric dihydrazide, adipic dihydrazide, pimelic dihydrazide, 8,12eicosadienedioic acid 1,20-dihydrazide and 4-isopropyl-2,5-dioxoimidazolidine-1,3di(propionohydrazide).

[0036] Preference is given to adipic dihydrazide, 8,12eicosadienedioic acid 1,20-dihydrazide (UDH) and 4-isopropyl-2,5-dioxoimidazolidine 1,3-di(propionohydrazide) (VDH). Adipic dihydrazide is the most preferred.

[0037] Suitable dihydrazides are commercially available, for example, 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)

[0038] A comparison of Table 2 with Table 3 shows that compositions containing aromatic dicarboxylic dihydrazide exhibit lower values ​​for overlap shear strength (LSS) than compositions containing aliphatic dicarboxylic dihydrazide. This is shown, for example, in the comparison of E5 with E1 or E7 with E2. Petition 870250093108, dated 10 / 10 / 2025, page 18 / 47 7 / 29

[0039] Preferably, at least one curing agent B is present in the thermosetting epoxy resin composition in an amount such that the molar ratio of curing agent B to epoxy resin A is 300 - 550 mmol / mol, preferably 400 - 500 mmol / mol, more preferably 425 - 475 mmol / mol.

[0040] The ratio of the proportion of epoxy groups of epoxy resin A in mol / total sum of curing agent B1 and curing agent B2 in mol (A / (B1 + B2)) is preferably 3-5, especially 3.5-4.5. This is advantageous in that, within this range, particularly advantageous values ​​are obtained for mechanical properties, especially shear strength by overlap and peeling by impact of the cured composition.

[0041] It may also be advantageous when more than 80% by weight, preferably more than 90% by weight, especially more than 95% by weight, especially preferably more than 98% by weight, more preferably more than 99% by weight, based on the total weight of the one-component thermosetting epoxy resin composition, of molecules capable of acting as curing agents for epoxy resins at temperatures between 100-220°C, are the molecules of curing agents B1 and B2.

[0042] It is even more advantageous when the one-component thermosetting epoxy resin composition includes a minimum amount of dicyandiamide. If the epoxy resin composition includes dicyandiamide, the weight ratio of the total amount of curing agent B1 and curing agent B2 to dicyandiamide ((B1 + B2) / dicyandiamide) is > 0.5, > 0.75, > 1, > 2, > 5, especially > 10, preferably > 50, more preferably > 100.

[0043] The composition of the invention also contains at least one accelerator C for at least one curing agent B, which is an imidazolium salt of formula (V): Petition 870250093108, dated 10 / 10 / 2025, p. 19 / 47 8 / 29 in what R1 is an organic radical with 1 to 20 C atoms. R2, R3, R4, and R5 are each either a hydrogen atom or an organic radical with 1 to 20 carbon atoms. X is an anion and en is 1, 2, or 3, preferably 1.

[0044] Preferably, the X anion is selected from the group consisting of alkyl sulfates; alkyl sulfonates; halides, more particularly chloride, bromide and iodide; thiocyanate; dicyanamide; carboxylates; phosphates, more particularly dimethyl phosphate and diethyl phosphate; and phosphonates.

[0045] More preferably, the X anion is selected from the group consisting of alkyl sulfates; halides, more particularly chlorides; carboxylates; phosphates; more particularly dimethyl phosphates.

[0046] Even more preferably, the X anion is selected from alkyl sulfonates.

[0047] Preferred alkyl sulfates have the formula RaOSO3', wherein Ra is a C1 to C12 alkyl group or a C5 to C12 aryl group, preferably a C1-C6 alkyl group or a C6 aryl group, more preferably a C2 alkyl group (ethyl sulfate).

[0048] A comparison of Table 3 with Table 4 further shows that compositions containing C1 exhibit higher values ​​for impact peeling and less viscosity increase than compositions containing C2C4. This is shown, for example, in the comparison of E5 with E9, E11 and E12.

[0049] The preferred halides are chloride. Petition 870250093108, dated 10 / 10 / 2025, p. 20 / 47 9 / 29

[0050] Preferred phosphates are dialkyl phosphates of formula RbRcPQ4-, where Rb and Rc independently of each other are a C1 to C6 alkyl group; more particularly Rb and Rc are the same alkyl group, more preferably dimethyl phosphate and diethyl phosphate, especially diethyl phosphate.

[0051] Preferred Qs carboxylates are carboxylates of the formula RdCQQ-, where Rd is a C1 to C20 alkyl group or a C6 to C10 aryl or aralkyl group, preferably a C1-C8 alkyl group, more particularly acetate.

[0052] The particularly preferred X anions are selected from the group consisting of acetate, diethyl phosphate, chloride and ethyl sulfate.

[0053] In formula (V) R1 and R3 are preferably, independently of each other, an organic radical with 1 to 10 C atoms. More particularly R1 and R3 are an aliphatic radical, more particularly an aliphatic radical without additional heteroatoms, such as an alkyl group, for example. With particular preference, R1 and R3, independently of each other, are a C1 to C10 or C1 to C4 alkyl group. Very preferably, R1 is a methyl group and R3 is an ethyl group or R1 is a methyl group and R3 is a butyl group.

[0054] In formula (V) R2, R4 and R5, preferably independently, are either an H atom or an organic radical with 1 to 10 C atoms; more particularly R2, R4 and R5 are either an H atom or an aliphatic radical. Particularly preferably R2, R4 and R5, independently of each other, are either an H atom or an alkyl group; more particularly, R2, R4 and R5, independently of each other, are either an H atom or a C1 to C4 alkyl group. Very preferably R2, R4 and R5 are each either an H atom. Preferably, n is 1.

[0055] X is preferably one of the above-mentioned and preferred anions, most preferably selected from the group consisting of acetate, diethyl phosphate, chloride and ethyl sulfate.

[0056] More preferably, the imidazolium salts of formula (V) are selected from the list consisting of ethyl 1-ethyl-3-methylimidazolium sulfate, diethyl 1-ethyl-3-methylimidazolium phosphate, 1-butyl-3-methylimidazolium chloride and Petition 870250093108, dated 10 / 10 / 2025, page 21 / 47 10 / 29 1-ethyl-3-methylimidazolium acetate.

[0057] Suitable imidazolium salts of formula (V) are commercially available, for example, from BASF under the trade name Basionics®.

[0058] The molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 6 - 120, preferably 10 - 100, more preferably 12 - 75.

[0059] It can be seen from the results in Table 2 that a molecular ratio (B / C) of more than 120 leads to insufficient values ​​for overlap shear strength. This is shown, for example, in the comparison of E1 and E2 with R5. Furthermore, the results in Table 3 show that a molecular ratio (B / C) of more than 120 leads to insufficient values ​​for overlap shear strength. This is shown, for example, in the comparison of E1 and E2 with R5.

[0060] It can also be seen from the results in Table 4 that a molecular ratio (B / C) of more than 120 leads to insufficient values ​​for impact peeling. This is shown, for example, in the comparison of E9-E10 with R10, E11 with R11 and E12 with R12.

[0061] Table 3 further shows that a molecular ratio (B / C) lower than 6 leads to a high increase in viscosity. This is shown, for example, in the comparison of E3-E8 with R9.

[0062] It may be preferable if the molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 12-25, preferably 14-20. This ratio is advantageous compared to higher values ​​for overlap shear strength. This is shown, for example, in Table 3 in the comparison of E6-E7 with E8 and E3-E5. This is also shown in Table 1 in the comparison of E2 with E1.

[0063] It may also be preferable if the molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 25–75, preferably 26–70, more preferably 40–70. Such a ratio is advantageous in relation to a low increase in viscosity after the Petition 870250093108, dated 10 / 10 / 2025, page 22 / 47 11 / 29 storage. This is shown, for example, in Table 3 in the comparison of E3-E5 with E6-E8.

[0064] The amount of dicyandiamide is preferably less than 5% by weight, less than 3% by weight, less than 2% by weight, especially less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.3% by weight, most preferably less than 0.1% by weight, based on the total weight of the epoxy resin composition. More preferably, the one-component thermosetting epoxy resin composition does not include any dicyandiamide.

[0065] It is further preferred if the one-component thermosetting epoxy resin composition contains epoxy resin accelerators other than those mentioned above, at least one accelerator C in an amount less than 0.5% by weight, less than 0.1% by weight, less than 0.05% by weight, especially less than 0.01% by weight, preferably less than 0.001% by weight, based on the total weight of the epoxy resin composition. More preferably, the one-component thermosetting epoxy resin composition does not include any epoxy resin accelerators other than the at least one accelerator C mentioned above. Such other epoxy resin accelerators are preferably selected from the list consisting of substituted ureas, imidazoles and blocked amines.

[0066] The amount of accelerator C is advantageously 0.5 - 5.0% by weight, especially 0.75 - 3.0% by weight, preferably 1.0 - 2.0% by weight, based on the weight of epoxy resin A.

[0067] It is further preferred that at least one accelerator C be present in the one-component thermoset epoxy resin composition in an amount such that the molar ratio of accelerator C to epoxy resin A is 5–95 mmol / mol, preferably 10–50 mmol / mol, more preferably 15–25 mmol / mol.

[0068] The ratio of accelerator C in grams per mole of epoxy groups of epoxy resin A is preferably 0.5 - 9.0 g / mol of groups Petition 870250093108, dated 10 / 10 / 2025, page 23 / 47 12 / 29 epoxy, especially 0.75 - 7.0 g / mol of epoxy groups, more preferably 1.0 - 4.5 g / mol of epoxy groups, more preferably 1.5 - 3.0 g / mol of epoxy groups, more preferably 2.0 - 2.5 g / mol of epoxy groups.

[0069] The one-component thermosetting epoxy resin composition preferably comprises at least one toughness enhancer D. The toughness enhancers D may be solid or liquid.

[0070] More particularly, the toughness enhancer D is selected from the group consisting of terminally locked polyurethane polymers D1, liquid rubbers D2 and core-shell polymers D3. The toughness enhancer D is preferably selected from the group consisting of terminally locked polyurethane polymers D1 and liquid rubbers D2. Particular preference is given to a terminally locked polyurethane polymer D1.

[0071] If the toughness enhancer D is a terminally blocked polyurethane prepolymer D1.

[0072] It is preferably a D1 terminally blocked polyurethane polymer with a blocking group that is eliminated at a temperature above 100°C.

[0073] Preferred blocking groups are especially first phenols or bisphenols. Preferred examples of such phenols and bisphenols are especially phenol, cresol, resorcinol, catechol, cardanol (3-pentadecenylphenol (from cashew nut oil)), nonylphenol, phenols that have been reacted with styrene or dicyclopentadiene, bisphenol A, bisphenol F and 2,2'-diallylbisphenol A.

[0074] The terminally blocked polyurethane prepolymer is prepared from a linear or branched polyurethane prepolymer terminated in isocyanate groups with one or more isocyanate-reactive compounds. If two or more of these isocyanate-reactive compounds are used, the reaction can be carried out sequentially or with a mixture of these compounds. Petition 870250093108, dated 10 / 10 / 2025, p. 24 / 47 13 / 29

[0075] The reaction is preferably carried out in such a way that one or more isocyanate-reactive compounds are used stoichiometrically or in stoichiometric excess in order to ensure that all NCO groups have been converted.

[0076] The polyurethane prepolymer with terminal isocyanate groups can be prepared from at least one di-isocyanate or tri-isocyanate and a Qpm polymer with terminal amino, thiol or hydroxyl groups and / or an optionally substituted Qpp polyphenol.

[0077] Suitable diisocyanates are aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, especially commercial products such as diphenyl methylene diisocyanate (MDI), hexamethylyne diisocyanate (HDI), toluene diisocyanate (TDI), toluidine 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), dicyclohexyl methyl diisocyanate (H12MDI), p-phenylene diisocyanate (PPDI), m-tetramethyl xylylene diisocyanate (TMXDI), etc., and dimers thereof. Preference is given to HDI, IPDI, MDI or TDI.

[0078] Suitable triisocyanates are aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanate trimers or biurets, particularly the diisocyanate isocyanurates and biurets described in the preceding paragraph. Of course, suitable mixtures of di- or triisocyanates may also be used.

[0079] Especially suitable Qpm polymers with terminal amino, thiol or hydroxyl groups are Qpm polymers with two or three terminal amino, thiol or hydroxyl groups.

[0080] Qpm polymers advantageously have an equivalent weight of 300-6000, especially 600-4000, preferably 700-2200, g / equivalent of NCO-reactive groups.

[0081] The preferred Qpm polymers are polyols with average molecular weights between 600 and 6000 daltons, selected from the group consisting of polyethylene glycols, polypropylene glycols, and polyethylene glycol block polymers. Petition 870250093108, dated 10 / 10 / 2025, page 25 / 47 14 / 29 polypropylene glycol, polybutylene glycols, hydroxyl-terminated polybutadienes, hydroxyl-terminated butadiene-acrylonitrile copolymers and mixtures thereof.

[0082] The particularly preferred Qpm polymers are α ω-dihydroxy polyalkylene glycols with C2-C6-alkylene groups or with mixed C2-C6-alkylene groups, terminated by amino, thiol or, preferably, hydroxyl groups. Particular preference is given to polypropylene glycols or polybutylene glycols. Particular preference is given to polyoxybutylenes terminated in a hydroxyl group.

[0083] The particularly suitable Qpp polyphenols are bis-, tris-, and tetraphenols. It is understood that this means not only simple phenols, but optionally also substituted phenols. The nature of the substitution can be very varied. More particularly, it is understood that it means substitution directly on the aromatic ring to which the phenolic OH group is attached. It is further understood that phenols means not only monocyclic aromatics, but also polycyclic or fused aromatics or heteroaromatics that have the phenolic OH group directly on the aromatic or heteroaromatic system.

[0084] In a preferred embodiment, the polyurethane prepolymer is prepared from at least one diisocyanate or triisocyanate and a Qpm polymer with terminal amino, thiol, or hydroxyl groups. The polyurethane prepolymer is prepared in a manner known to those skilled in the art of polyurethane, especially by using the diisocyanate or triisocyanate in a stoichiometric excess relative to the amino, thiol, or hydroxyl groups of the Qpm polymer.

[0085] The polyurethane prepolymer with isocyanate end groups preferably has an elastic character. Preferably, it exhibits a glass transition temperature Tg below 0°C.

[0086] The toughness enhancer D can be a liquid rubber D2. This can be, for example, a carboxy- or epoxy-terminated polymer.

[0087] In a first embodiment, this liquid rubber may be a carboxy- or epoxy-terminated acrylonitrile / butadiene copolymer or a derivative thereof. Such liquid rubbers are commercially available, for Petition 870250093108, dated 10 / 10 / 2025, page 26 / 47 15 / 29 example, under the names Hypro / Hypox® CTBN and CTBNX and ETBN from Emerald Performance Materials. Suitable derivatives are especially elastomer-modified prepolymers with epoxy groups, commercially sold under the Polydis® product line, especially the Polydis® 36 product line, by Struktol® (Schill+Seilacher Gruppe, Germany) or under the Albipox product line (Evonik, Germany).

[0088] In a second embodiment, this liquid rubber may be a polyacrylate liquid rubber that is fully miscible with liquid epoxy resins and only separates to form microdroplets during the curing of the epoxy resin matrix. These polyacrylate liquid rubbers are available, for example, under the name 20208-XPA from Dow.

[0089] Of course, it is also possible to use liquid rubber mixtures, especially mixtures of acrylonitrile / butadiene copolymers terminated in carboxy or epoxy or derivatives thereof.

[0090] The toughness enhancer D, in a third embodiment, may be a core-shell polymer D3. Core-shell type polymers consist of an elastic core polymer and a rigid shell polymer. Particularly suitable core-shell polymers consist of an elastic acrylate polymer or butadiene polymer core, surrounded by a rigid shell of a rigid thermoplastic polymer. This core-shell structure forms spontaneously or as a result of the separation of a block copolymer or is defined by carrying out the polymerization as a latex or suspension polymerization with subsequent grafting. Preferred core-shell polymers are the so-called MBS polymers, which are commercially available under the trade names Clearstrength™ from Arkema, Paraloid™ from Dow or F-351™ from Zeon.

[0091] Preferably, the proportion of toughness enhancer D, especially 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. Petition 870250093108, dated 10 / 10 / 2025, page 27 / 47 16 / 29 weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0092] This is advantageous insofar as it gives high values ​​for impact peeling with simultaneously high values ​​of overlap shear strength.

[0093] In another preferred embodiment, the composition further comprises at least one filler F. In this document, preference is given to mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or ground), dolomite, quartz, silica (fused or precipitated), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic granules, hollow glass granules, hollow organic granules, glass granules, colored pigments. Particular preference is given to fillers selected from the group consisting of calcium carbonate, calcium oxide and fumed silicas.

[0094] Advantageously, the total proportion of the total filler F is 540% by weight, preferably 10-30% by weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0095] In another preferred embodiment, the composition further comprises at least one reactive epoxy-bearing diluent G. Such reactive diluents are known to those skilled in the art. Preferred examples of epoxy-bearing reactive diluents are: - Glycidyl ethers of monofunctional C4-C30 alcohols, saturated or unsaturated, branched or unbranched, cyclic or open-chain, for example, butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ether, trimethoxysilyl glycidyl ether and the like; - Glycidyl ethers of C2-C30 difunctional alcohols, saturated or unsaturated, branched or unbranched, cyclic or open-chain, for example, ethylene glycol glycidyl ether, butanediol glycidyl ether, hexanediol glycidyl ether, octanediol glycidyl ether, diglycidyl ether of Petition 870250093108, dated 10 / 10 / 2025, page 28 / 47 17 / 29 cyclohexanedimethanol, neopentyl glycol diglycidyl ether and the like; - Glycidyl ethers of tri- or polyfunctional alcohols, saturated or unsaturated, branched or unbranched, cyclic or open-chain, such as epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol, or polyglycidyl ethers of aliphatic polyols, such as sorbitol, glycerol, trimethylolpropane, and the like; - Glycidyl ethers of phenol compounds 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 oil), N,N-diglycidylaniline and the like; - epoxidized amines, such as N,N-diglycidylcyclohexylamine and the like; - epoxidized mono- or dicarboxylic acids, such as glycidyl neodecanoate, glycidyl methacrylate, glycidyl benzoate, diglycidyl phthalate, tetrahydrophthalate and hexahydrophthalate, diglycidyl esters of dimeric fatty acids and the like; - Epoxidized di- or trifunctional polyether polyols, ranging from low to high molecular weight, such as polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and the like.

[0096] Particular preference is given to hexanediol diglycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, polypropylene glycol diglycidyl ether and polyethylene glycol diglycidyl ether.

[0097] Advantageously, the total proportion of the reactive epoxy carrier diluent G is 0.1-15% by weight, preferably 0.1-5% by weight, especially preferably 0.1-2% by weight, more preferably 0.21% by weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0098] The composition may include other constituents, especially catalysts, stabilizers, especially heat and / or light stabilizers, thixotropic agents, plasticizers, solvents, mineral fillers or Petition 870250093108, dated 10 / 10 / 2025, page 29 / 47 18 / 29 organic compounds, blowing agents, dyes and pigments, anti-corrosives, surfactants, anti-foaming agents and adhesion promoters.

[0099] Suitable plasticizers are especially phenol alkyl sulfonates or N-butylbenzamide, commercially available as Mesamoll® or Dellatol BBS from Bayer.

[0100] Suitable stabilizers are especially optionally substituted phenols, such as BHT or Wingstay® T (Elkem), sterically hindered amines or N-oxyl compounds, such as TEMPO (Evonik).

[0101] A particularly preferred one-component epoxy resin composition comprises: - 10-60% by weight, especially 30-60% by weight, based on the total weight of the epoxy resin composition, of epoxy resin A with an average of more than one epoxy group per molecule; preferably 50-100% by weight, especially 80-100% by weight, of epoxy resin A is a liquid epoxy resin and 0-30% by weight, especially 0-20% by weight, of epoxy resin A is a solid epoxy resin; - at least one curing agent B for epoxy resins, wherein the curing agent B is a dihydrazide, preferably selected from the group consisting of aromatic dicarboxylic dihydrazide B1, preferably isophthalic dihydrazide, and aliphatic dicarboxylic dihydrazide B2, preferably adipic dihydrazide; - at least one accelerator C for at least one curing agent B, which is an imidazolium salt of formula (V): in what R1 is an organic radical with 1 to 20 C atoms. Petition 870250093108, dated 10 / 10 / 2025, page 30 / 47 19 / 29 R2, R3, R4, and R5 are each either a hydrogen atom or an organic radical with 1 to 20 carbon atoms. X is an anion and en is 1, 2 or 3, preferably 1; Preferably, the imidazolium salt of formula (V) is selected from 1-Ethyl-3-methylimidazolium ethyl sulfate, 1-Ethyl-3-methylimidazolium diethyl phosphate, 1-Butyl-3-methylimidazolium chloride and 1-Ethyl-3-methylimidazolium acetate, more preferably 1-Ethyl-3-methylimidazolium ethyl sulfate; - preferably 15-45% by weight, especially 20-40% by weight, based on the total weight of the one-component thermosetting epoxy resin composition, of at least one toughness enhancer D that is selected from the group consisting of terminally locked polyurethane polymers D1, liquid rubbers D2 and core-shell polymers D3, preferably terminally locked polyurethane polymers D1; - preferably 5-40% by weight, preferably 10-30% by weight, based on the total weight of the one-component thermosetting epoxy resin composition, of a filler F selected from the group consisting of calcium carbonate, calcium oxide and fumed silicas; - preferably 0.1-15% by weight, preferably 0.1-5% by weight, especially preferably 0.1-2% by weight, more preferably 0.2-1% by weight, based on the total weight of the one-component thermosetting epoxy resin composition, of a reactive diluent containing epoxy G.

[0102] The X anion of the imidazolium salt of formula (V) is selected from the group consisting of alkyl sulfates; halides, more particularly chlorides; carboxylates; phosphates, more particularly dimethyl phosphates; more preferably alkyl sulfonates.

[0103] In formula (V), R1 is a methyl group and R3 is an ethyl group or R1 is a methyl group and R3 is a butyl group, preferably R1 is a methyl group and R3 is an ethyl group. In both cases, R2, R4 and R5 are each an atom of Petition 870250093108, dated 10 / 10 / 2025, page 31 / 47 20 / 29 H en é 1.

[0104] The molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 6 - 120, preferably 10 - 100, more preferably 12 - 75.

[0105] At least one accelerator C is present in the one-component thermoset epoxy resin composition in an amount such that the molar ratio of accelerator C to epoxy resin A is 5 - 95 mmol / mol, preferably 10 - 50 mmol / mol, more preferably 15 - 25 mmol / mol.

[0106] At least one curing agent B is present in the thermosetting epoxy resin composition in an amount such that the molar ratio of curing agent B to epoxy resin A is 300 - 550 mmol / mol, preferably 400 - 500 mmol / mol, more preferably 425 - 475 mmol / mol.

[0107] It may also be advantageous when the preferred single-component epoxy resin composition consists of the aforementioned constituents to an extent of more than 80% by weight, preferably more than 90% by weight, especially more than 95% by weight, especially preferably more than 98% by weight, most preferably more than 99% by weight, based on the total weight of the epoxy resin composition.

[0108] It is advantageous when the epoxy resin composition of the invention has a viscosity at 25°C of 500-4500 Pa*s, especially 1000-3000 Pa*s, preferably 1500-2500 Pa*s, particularly measured with an oscillating rheometer using a plate-to-plate geometry with the following parameters: 5 Hz, measuring gap 1 mm, plate-to-plate diameter 25 mm, deformation of 1%. This is advantageous as it ensures good applicability.

[0109] It has been found that the described one-component thermosetting epoxy resin compositions are particularly suitable for use as one-component thermosetting adhesives, especially as a one-component thermosetting bodywork adhesive in motor vehicle construction. This single-component adhesive has a range of possible uses. Such adhesives are required for bonding heat-stable materials. It is understood that Petition 870250093108, dated 10 / 10 / 2025, page 32 / 47 21 / 29 Heat-stable materials are 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 GFP, epoxy, or acrylate composite materials. Preference is given to uses where at least one material is a metal. A particularly preferred use is considered to be the bonding of identical or dissimilar metals, especially in the construction of bodywork in the automotive industry. Preferred metals are mainly steel, especially electrolytically galvanized, hot-dip galvanized, oil-coated steel, Bonazink-coated steel, and subsequently phosphated steel, and also aluminum, especially the types generally used in automobile construction.

[0110] Another aspect of the present invention relates to a process for bonding heat-stable substrates, comprising the following steps: i) Apply a one-component thermosetting epoxy resin composition as described in detail above to the surface of a heat-stable substrate S1, especially a metal; ii) bringing the applied one-component thermosetting epoxy resin composition into contact with the surface of another heat-stable substrate S2, especially a metal; iii) heating the composition to a temperature of 100-220°C, especially 120-200°C, preferably between 130 and 150°C, more preferably between 130 and 140°C. [01 11] Substrate S2 here consists of the same material or a different material from substrate S1. Substrates S1 and / or S2 are, in particular, the metals and plastics mentioned above. [0 112] Preferably, in step iii), the composition is heated to a temperature of 100-220°C, especially 120-200°C, preferably between 130 and 150°C, more preferably between 130 and 140°C, and the composition is left at the above-mentioned temperature for 10 min - 6 h, 10 min - 2 h, Petition 870250093108, dated 10 / 10 / 2025, pp. 33 / 47 22 / 29 min - 60 min, 10 min - 30 min, 10 min - 20 min, more preferably 10 min - 15 min.

[0113] One such method of bonding thermosetting materials results in an article bonded by adhesive. Such an item is preferably a vehicle or part of a vehicle.

[0114] A further aspect of the present invention therefore relates to an adhesive-bonded article obtained by the process mentioned above. Furthermore, the compositions according to the invention are suitable not only for the construction of automobiles, but also for other fields of use. Particular mention should be made of applications relating to the construction of means of transport, such as ships, trucks, buses or railway vehicles, or in the construction of consumer goods, such as, for example, washing machines.

[0115] The materials bonded by adhesive using a composition according to the invention are used at temperatures typically between 120°C and -40°C, preferably between 100°C and -40°C, in particular between 80°C and -40°C.

[0116] A particularly preferred use of the thermosetting epoxy resin composition of a component of the invention is its use as a thermosetting funneling adhesive of a component in the construction of motor vehicles or as a reinforcing compound or as a foamable thermoset composition for reinforcing voids in structural components and reinforcing elements.

[0117] Another aspect of the present invention relates to a cured epoxy resin composition as obtained by heating a one-component thermosetting epoxy resin composition as described in detail above.

[0118] It has been found that the accelerators C of the invention, as described in detail above as a constituent of a thermosetting epoxy resin composition, are suitable in combination with the curing agents B of the invention as accelerators for thermosetting epoxy resin compositions at curing temperatures especially between 130 and 150°C. Petition 870250093108, dated 10 / 10 / 2025, pp. 34 / 47 23 / 29

[0119] More preferably, the compositions of the invention have the following properties: After curing for 10 minutes at 140°C: - LSS, measured as described in the experiment, of > 27.5 MPa, especially > 28 MPa, especially > 28.5 MPa, especially > 29 MPa, more preferably > 30 MPa; - IP, measured as described in the experiment, of > 29 N / mm, especially > 30 N / mm, especially > 31 N / mm, more preferably > 32 N / mm. Examples

[0120] Some examples that further illustrate the invention, but are not intended to limit the scope of the invention in any respect, are cited below. Preparation of a toughness enhancer (D-1)

[0121] 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 under vacuum at 105°C for 30 minutes. Once the temperature was reduced to 90°C, 61.5 g of IPDI and 0.14 g of dibutyltin dilaurate were added. The reaction was carried out under vacuum at 90°C until the NCO content was constant at 3.10% after 2.0 h (calculated NCO content: 3.15%). Subsequently, 96.1 g of cardanol were added as a blocking agent. Stirring was continued at 105°C under vacuum until no more free NCO could be detected. The product was used as such as a D-1 toughness improver. Liquid epoxy resin, DER 331 (bisphenol A diglycidyl ether), Dow E tert-butylphenyl glycidyl ether, Polypox R7, B1 adipic dihydrazide (ADH), CAS: 1071-93-8, Technicure ADH-J (average particle size D50 of 2.4 µm), A&C Catalysts Inc., Mw: 174.20 g / mol B2 isophthalic dihydrazide (IDH), CAS: 2760-98-7, Mw: 194.194 g / mol Petition 870250093108, dated 10 / 10 / 2025, pp. 35 / 47 24 / 29 C1 Basionics LQ 01, 1-Ethyl-3-methylimidazolium ethyl sulfate, BASF, Mw: 236.29 g / mol C2 1-Ethyl-3-methylimidazolium diethyl phosphate, Sigma Aldrich, Mw: 264.26 g / mol C3 1-Butyl-3-methylimidazolium chloride, Sigma Aldrich, Mw: 174.67 g / mol C4 1-Ethyl-3-methylimidazolium acetate, Sigma Aldrich, Mw: 170.21 g / mol F1 Corrosion protection particles F2 Wollastonite F3 Calcium oxide F4 Pyrogenic silica Poly-THF 2000 (bifunctional polybutylene glycol) (OH equivalent weight = approximately 1000 g / OH equivalent), BASF Liquiflex H (terminated polybutadiene hydroxyl) (OH equivalent weight = about 1230 g / OH equivalent), Krahn Isophorone Diisocyanate (= IPDI), Evonik Cardolite NC-700 (cardanol, meta substituted alkenylmonophenol), Cardolite Raw materials used. Production of compositions

[0122] Reference compositions R1-R12 and inventive compositions E1 to E12 were produced according to the compositions in Table 2-4. The quantities indicated in Table 2-4 are in parts by weight.

[0123] The molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is shown as MR (B / C) in Table 2-4. Testing methods: Shear strength by overlap (LSS) (DIN EN 1465)

[0124] Clean test samples of Elo H420 steel (1.2 mm thick) that were wrapped with Anticorit PL 3802-39S (3 g / m2) were bonded Petition 870250093108, dated 10 / 10 / 2025, pp. 36 / 47 25 / 29 with the adhesive applied over a 25 x 10 mm bonding area with glass beads as a spacer in a layer thickness of 0.3 mm and cured at the object temperature of 140°C for 10 min.

[0125] Shear strength was determined on a tensile tester at a stress rate of 10 mm / min in a triple determination according to DIN EN 1465. Impact peel resistance (IP RT) (according to ISO 11343)

[0126] The specimens were produced with DC04+ZE adhesive and steel with dimensions of 90 x 20 x 0.8 mm that had been wrapped with Anticorit PL 3802-39S (3g / m2). The bonding area in this document was 20 x 30 mm, with a layer thickness of 0.3 mm, with glass beads as a spacer. The samples were cured for 10 minutes at the object temperature of 140°C. Impact peel resistance was measured at 23°C as a triple determination on a Zwick 450 impact pendulum. The reported impact peel resistance is the average force in N / mm according to the measurement curve from 25% to 90% of ISO11343. Viscosity / storage stability of adhesives

[0127] To assess the storage stability of the adhesives, viscosity measurement was repeated after storage for 1 week at 50°C, and the resulting percentage increase in viscosity after storage was verified. The increase in viscosity in % is shown in Tables 3 and 4 under Percentage Viscosity Increase. All compositions had a viscosity of 1500-2500 Pa*s at the start of the viscosity measurement. Viscosity was determined by an oscillating rheometer using a plate-to-plate geometry with the following parameters: 5 Hz, measuring gap 1 mm, plate-to-plate diameter 25 mm, strain of 1%. Petition 870250093108, dated 10 / 10 / 2025, pp. 37 / 47 26 / 29 R1 R2 R3 R4 R5 E1 E2 A 44 44 44 44 44 44 44 E 0.5 0.5 0.5 0.5 0.5 0.5 0.5 D1 22 22 22 22 22 22 22 B1 10 B2 11.3 11.3 11.3 11.3 C1 0.5 2 0.1 0.5 1 F1 3 3 3 3 3 3 3 F2 5 5 5 5 5 5 5 F3 4.5 4.5 4.5 4.5 4.5 4.5 4.5 F4 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Total (by weight-%): 96.5 97.8 87 88.5 97.9 98.3 98.8 mMol B1 0.59 0.00 0.00 0.00 0.00 0.00 0.00 mMol B2 0.00 0.59 0.00 0.00 0.59 0.59 0.59 mMol C1 0.000 0.000 0.024 0.096 0.004 0.022 0.043 MR (B / C) - - - - 137 27 14. Index B 4 4 - - 4 4 4 Petition 870250093108, dated 10 / 10 / 2025, pp. 38 / 47 27 / 29 C Index - - 2.16 8.64 0.43 2.16 4.32 LSS (10' 140°C) [MPa] ncncncncnc 1.2 4.6 Table 2, nc = not cured R6 R7 R8 E3 E4 E5 E6 E7 E8 R9 A 44 44 44 44 44 44 44 44 44 44 E 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 D1 22 22 22 22 22 22 22 22 22 22 B1 10 10 10 10 10 10 10 10 10 10 C1 0.01 0.02 0.1 0.2 0.3 0.5 0.75 1 2 3 F1 3 3 3 3 3 3 3 3 3 3 F2 5 5 5 5 5 5 5 5 5 5 F3 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 4.5 F4 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Total (by weight-%): 96.51 96.52 96.6 96.7 96.8 97 97.25 97.5 98.5 99.5 mMol B1 0.59 0.59 0.59 0.59 0.59 0.59 0.59 0.59 0.58 0.58 mMol C1 0.000 0.001 0.004 0.009 0.013 0.022 0.033 0.043 0.086 0.128 MR (B / C) 1356 678 136 68 45 27 18 14. 7. 5 LSS (10' 140°C) [MPa] 20.9 nd 22.9 28.2 29.8 28.8 30.6 30.3 29.8 27.1 IP RT (10' 140°C) [N / mm] 21.8 nd 28.6 30.9 29.8 32.0 31.2 30.4 32.6 27.5 Visco increase [%] 12. 15 16 37 34 32 47 51 100 >100 Petition 870250093108, dated 10 / 10 / 2025, pp. 39 / 47 28 / 29 Table 3, nd = not determined R10 E9 E10 R11 E11 R12 E12 A 44 44 44 44 44 44 44 E 0.5 0.5 0.5 0.5 0.5 0.5 0.5 D1 22 22 22 22 22 22 22 B1 10 10 10 10 10 10 10 C2 0.01 0.5 2 C3 0.01 0.5 C4 0.01 0.5 F1 3 3 3 3 3 3 3 F2 5 5 5 5 5 5 5 F3 4.5 4.5 4.5 4.5 4.5 4.5 4.5 F4 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Total (by weight-%): 96.51 97 98.5 96.51 97 96.51 97 mMol B1 0.59 0.59 0.58 0.59 0.59 0.59 0.59 mMol C2 0.001 0.020 0.077 0.000 0.000 0.000 0.000 mMol C3 0.000 0.000 0.000 0.001 0.030 0.000 0.000 Petition 870250093108, dated 10 / 10 / 2025, pp. 40 / 47 29 / 29 mMol C4 0.000 0.000 0.000 0.000 0.000 0.001 0.030 MR (B / C) 1517 30 8. 1003 20 977 20 IP RT (10' 140°C) [N / mm] 21 31 29 22 30 23 28 Visco increase [%] ndndnd 12. 100 13. 100 Table 4, nd = not determined Petition 870250093108, dated 10 / 10 / 2025, pp. 41 / 47

Claims

1 / 5 Claims 1. One-component thermosetting epoxy resin composition characterized in that it comprises a) at least one epoxy resin A having an average of more than one epoxy group per molecule; b) at least one curing agent B for epoxy resins, wherein the curing agent B is a dihydrazide, preferably selected from the group consisting of aromatic dicarboxylic dihydrazide B1 and aliphatic dicarboxylic dihydrazide B2; and c) at least one accelerator C for the at least one curing agent B, which is an imidazolium salt of formula (V): wherein R1 is an organic radical with 1 to 20 C atoms, R2, R3, R4 and R5 are each an H atom or an organic radical with 1 to 20 C atoms, X is an anion and is 1, 2 or 3, preferably 1;Preferably, the imidazolium salt of formula (V) is selected from 1-Ethyl-3-methylimidazolium ethyl sulfate, 1-Ethyl-3-methylimidazolium diethyl phosphate, 1-Butyl-3-methylimidazolium chloride and 1-Ethyl-3-methylimidazolium acetate, more preferably 1-Ethyl-3-methylimidazolium ethyl sulfate, wherein the molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 6-120, preferably 10-100, more preferably 12-75.

2. One-component thermosetting epoxy resin composition according to claim 1, characterized in that the curing agent B is an aromatic dicarboxylic dihydrazide B1, preferably selected from the group consisting of isophthalic dihydrazide and / or terephthalic dihydrazide, preferably isophthalic dihydrazide.

3. One-component thermosetting epoxy resin composition according to any of the preceding claims, characterized in that the curing agent B is an aliphatic dicarboxylic dihydrazide B2, preferably 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.

4. One-component thermosetting epoxy resin composition according to any of the preceding claims, characterized in that the anion X of the imidazolium salt of formula (V) is selected from the group consisting of alkyl sulfates; alkyl sulfonates; halides, more particularly chloride, bromide and iodide; thiocyanate; dicyanamide; carboxylates; phosphates, more particularly dimethyl phosphate and diethyl phosphate; and phosphonates; preferably selected from the group consisting of alkyl sulfates; halides, more particularly chloride; carboxylates; phosphates, more particularly dimethyl phosphates; more preferably alkyl sulfonates.5 One-component thermosetting epoxy resin composition according to any of the preceding claims, characterized in that in formula (V) R1 is a methyl group and R3 is an ethyl group or R1 is a methyl group and R3 is a butyl group, preferably R1 is a methyl group and R3 is an ethyl group, and further characterized in that R2, R4 and R5 are each an H atom where 1.

6. One-component thermosetting epoxy resin composition according to any of the preceding claims, characterized in that the molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 12-25, preferably 14-20. Petition 870250093108, dated 10 / 10 / 2025, pp. 43 / 47 3 / 5 7. One-component thermosetting epoxy resin composition according to any one of claims 1-5, characterized in that the molar ratio of at least one curing agent B for epoxy resins to at least one accelerator C (B / C) is 25-75, preferably 26-70, more preferably 40-70.

8. One-component thermosetting epoxy resin composition according to any of the preceding claims, characterized in that at least one accelerator C is present in the one-component thermosetting epoxy resin composition in an amount such that the molar ratio of accelerator C to epoxy resin A is 5–95 mmol / mol, preferably 10–50 mmol / mol, more preferably 15–25 mmol / mol.

9. One-component thermosetting epoxy resin composition according to any of the preceding claims, characterized in that at least one curing agent B is present in the thermosetting epoxy resin composition in an amount such that the molar ratio of curing agent B to epoxy resin A is 300–550 mmol / mol, preferably 400–500 mmol / mol, more preferably 425–475 mmol / mol.

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

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

12. One-component thermosetting epoxy resin composition, from Petition 870250093108, dated 10 / 10 / 2025, page 44 / 47 4 / 5 according to any of the preceding claims, characterized in that the epoxy resin composition has a viscosity at 25 °C of 500-4500 Pa*s, especially 1000-3000 Pa*s, preferably 1500-2500 Pa*s, preferably measured with an oscillating rheometer using a plate-to-plate geometry with the following parameters: 5 Hz, measuring interval 1 mm, plate-to-plate diameter 25 mm, 1% deformation.

13. Use of a single-component thermosetting epoxy resin composition according to any one of claims 1 to 12 as a single-component thermosetting adhesive, characterized in that it is especially used as a single-component thermosetting adhesive for sheet metal work in the construction of motor vehicles.

14. Process for bonding heat-stable substrates, characterized in that it comprises the steps of: i) applying a thermosetting one-component epoxy resin composition, according to any one of claims 1 to 12, to the surface of a heat-stable substrate S1, especially a metal; ii) placing the applied thermosetting one-component epoxy resin composition in contact with the surface of another heat-stable substrate S2, especially a metal; iii) heating the composition to a temperature of 100-220°C, especially 120-200°C, preferably between 130 and 150°C, more preferably between 130 and 140°C; wherein the substrate S2 consists of the same material as or a different material from substrate S1.

15. Process according to claim 14, characterized in that in step iii) of heating the composition to a temperature of 100-220°C, especially 120-200°C, preferably between 130 and 150°C, more preferably between 130 and 140°C, the composition is maintained 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. Petition 870250093108, dated 10 / 10 / 2025, p. 45 / 47 5 / 5 16 Article fixed by adhesive, characterized in that it is obtained from a process according to one of claims 14 to 15. Petition 870250093108, dated 10 / 10 / 2025, pp. 46 / 47.