A thermosetting epoxy resin composition with good storage stability, suitable for low curing temperatures.

Abstract

The present invention relates to a thermosetting epoxy resin composition comprising a dihydrazide as a curing agent in combination with an imidazolium salt as an accelerator for the curing agent, wherein the molar ratio of curing agent to accelerator is 6 to 120. This composition is characterized by good storage stability and a low curing temperature. This epoxy resin composition is particularly suitable for use as an adhesive for automotive bodies.

Description

[Technical Field]

[0001] The present invention relates particularly to thermosetting one-component epoxy resin compositions for use as adhesives for automobile bodies. [Background technology]

[0002] Thermosetting epoxy resin compositions have been known for a long time. Efforts have long been made to improve, or at least significantly reduce, the major drawback of epoxy resin compositions, namely their brittleness (which results in the cured epoxy resin composition cracking or breaking under impact stress). Attempts to do this have already been made by adding impact modifiers or chemically modifying the epoxy resin.

[0003] An important application area for thermosetting epoxy resin compositions is automotive assembly, particularly the bonding of car bodies. After application of the epoxy resin composition, the car body is heated in a cationic electrodeposition oven, thereby curing the thermosetting epoxy resin composition. International Publication No. 2019081581A1 describes thermosetting epoxy resin compositions for use as adhesives for car bodies and for the production of structural foams.

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

[0005] However, efforts are currently being made in the market to lower the temperature of cationic electrodeposition coating ovens. Therefore, there is a great need in the market for thermosetting epoxy resin compositions that cure at relatively low temperatures, i.e., 130-140°C, in a short time, typically 10-15 minutes. For example, using aromatic urea, which is far more reactive due to its structure, for this purpose presents significant problems with the storage stability of the thermosetting epoxy resin composition. Therefore, there is a need for a one-component thermosetting epoxy resin composition that cures at lower temperatures and has sufficient storage stability. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Therefore, an object of the present invention is to provide a thermosetting one-component epoxy resin composition with storage stability that has sufficient mechanical properties, particularly lap shear strength and impact peel performance, after curing at a lower temperature and shorter curing time, especially after curing at 140°C for 10 minutes. [Means for solving the problem]

[0007] Surprisingly, this objective was achieved by the thermosetting one-component epoxy resin composition described in claim 1. This epoxy resin composition has particularly good utility as a one-component thermosetting adhesive, especially as a thermosetting one-component body adhesive in automobile assembly. [Modes for carrying out the invention]

[0008] The present invention a) At least one epoxy resin A having an average of two or more epoxy groups per molecule, b) At least one curing agent B for epoxy resin, preferably a dihydrazide selected from the group consisting of aromatic dicarboxylic acid dihydrazide B1 and aliphatic dicarboxylic acid dihydrazide B2, c) At least one accelerator C for at least one curing agent B, wherein formula (V): [ka] (In the formula, R1 is an organic radical having 1 to 20 carbon atoms. R2, R3, R4, and R5 are each organic radicals having either an H atom or 1 to 20 C atoms. X is an anion, and n is 1, 2, or 3, preferably 1. At least one accelerator C which is an imidazolium salt and It relates to a thermosetting one-component epoxy resin composition containing

[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, and most preferably 1-ethyl-3-methylimidazolium ethyl sulfate.

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

[0011] In this specification, in relation to substituents, radicals or groups, the use of the term "independently" should be interpreted such that substituents, radicals or groups having the same name within the same molecule can be present simultaneously in different meanings.

[0012] In this specification, the prefix "poly" in substance names such as "polyol", "polyisocyanate", "polyether" or "polyamine" indicates that each substance contains two or more functional groups present in the name per molecule in a formal sense.

[0013] In this specification, "molecular weight" is understood to mean the molar mass (grams / mol) of one molecule. "Average molecular weight" means the number average molecular weight M of oligomer or polymer mixed molecules n which is typically determined by GPC with respect to polystyrene as a standard.

[0014] "Primary hydroxyl group" refers to an OH group bonded to a carbon atom having two hydrogens.

[0015] In this specification, the term “primary amino group” refers to an NH2 group bonded to one organic radical, and the term “secondary amino group” refers to an NH group bonded to two organic radicals, which may together be part of a ring. Accordingly, amines having one primary amino group are referred to as “primary amines,” amines having a secondary amino group as “secondary amines,” and amines having a tertiary amino group as “tertiary amines.”

[0016] In this specification, "room temperature" refers to a temperature of 23°C.

[0017] Epoxy resin A, which has an average of two or more epoxy groups per molecule, is preferably a liquid epoxy resin or a solid epoxy resin. The term "solid epoxy resin" is very well known to those skilled in the art of epoxy and is used in contrast to "liquid epoxy resin." Because the glass transition temperature of solid resins is higher than room temperature, they can be pulverized at room temperature to obtain a fluid powder.

[0018] A preferred epoxy resin is formula (II) [ka] It holds.

[0019] The substituents R' and R'' in the formula are independently either H or CH3.

[0020] In the case of solid epoxy resins, the subscript s has a value of >1.5, especially between 2 and 12.

[0021] Such solid epoxy resins are commercially available, for example, from Dow, Huntsman, or Hexion.

[0022] Compounds of formula (II) having a subscript s between 1 and 1.5 are referred to by those skilled in the art as semi-solid epoxy resins. In the present invention, these are also considered solid resins. However, preferred solid epoxy resins are epoxy resins in a narrower sense, i.e., epoxy resins in which the subscript s has a value of >1.5.

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

[0024] Therefore, diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol A / F are preferred. 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] A more suitable epoxy resin A is called an epoxy novolac. More specifically, these are phenol or cresol epoxy novolacs.

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

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

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

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

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

[0031] It is even more advantageous if 0 to 30% by weight, particularly 0 to 20% by weight, and more preferably 5 to 15% by weight of epoxy resin A is the aforementioned solid epoxy resin.

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

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

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

[0035] Preferably, the curing agent B is an aliphatic dicarboxylic acid dihydrazide B2 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).

[0036] Dihydrazide adipic acid, 1,20-dihydrazide 8,12-eicosadiene dioic acid (UDH), and 4-isopropyl-2,5-dioxoimidazolidine-1,3-di(propionohydrazide) (VDH) are preferred. The most preferred is dihydrazide adipic acid.

[0037] Suitable dihydrazides are commercially available, for example, from Otsuka Chemical Co., Ltd. under the trade names Ajicure® (from Ajinomoto Fine Techno Co., Ltd.) and Technicure® (from A&C Catalysts).

[0038] Comparing Table 2 with Table 3, it can be seen that compositions containing aromatic dicarboxylic acid dihydrazides exhibit lower lap shear strength (LSS) values ​​than compositions containing aliphatic dicarboxylic acid dihydrazides. This is demonstrated, for example, by comparing E5 and E1 or E7 and E2.

[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 to 550 mmol / mol, preferably 400 to 500 mmol / mol, and more preferably 425 to 475 mmol / mol.

[0040] The ratio of epoxy groups (mol) of epoxy resin A to the total amount (mol) of curing agents B1 and B2 (A / (B1+B2)) is preferably 3 to 5, particularly 3.5 to 4.5. Within this range, it is advantageous to obtain values ​​that are particularly favorable for the mechanical properties of the cured composition, especially for lap shear strength and impact delamination.

[0041] Based on the total weight of the thermosetting one-component epoxy resin composition, it may be even more advantageous if more than 80% by weight, preferably more than 90% by weight, particularly preferably more than 95% by weight, particularly preferably more than 98% by weight, and most preferably more than 99% by weight of molecules that can act as curing agents for the epoxy resin at a temperature of 100 to 220°C are molecules of curing agents B1 and B2.

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

[0043] The composition of the present invention also includes at least one accelerator C for at least one curing agent B, which is of formula (V): [ka] (In the formula, R1 is an organic radical having 1 to 20 carbon atoms. R2, R3, R4, and R5 are each organic radicals having either an H atom or 1 to 20 C atoms. X is an anion, and n is 1, 2, or 3, preferably 1. It is the imidazolium salt of [the substance].

[0044] Preferably, the anion X is selected from the group consisting of alkyl sulfate ions, alkyl sulfonate ions, halide ions, more specifically chloride ions, bromide ions and iodide ions, thiocyanate ions, dicyanamide ions, carboxylate ions, phosphate ions, more specifically dimethyl phosphate ions and diethyl phosphate ions and phosphonate ions.

[0045] More preferably, the anion X is selected from the group consisting of alkyl sulfate ions, halide ions, more specifically chloride ions, carboxylate ions, phosphate ions, and more specifically dimethyl phosphate ions.

[0046] More preferably, the anion X is selected from alkyl sulfonate ions.

[0047] Preferred alkyl sulfate ions are those of formula R a OSO3- which has, in the formula, R a is a C1-C12 alkyl group or a C5-C12 aryl group, preferably a C1-C6 alkyl group or a C6 aryl group, and most preferably a C2 alkyl group (ethyl sulfate ion).

[0048] Comparing Table 3 with Table 4, it is further clear that the composition containing C1 shows higher values for impact peeling than the compositions containing C2-C4 and has a lower increase in viscosity. This is shown, for example, by the comparison between E5 and E9, E11 and E12.

[0049] A preferred halide is chloride ion.

[0050] Preferred phosphate ions are dialkyl phosphate ions of the formula R b R c PO4 - wherein R b and R c are, independently of each other, C1-C6 alkyl groups, and in particular, R b and R c are the same alkyl group, and most preferably dimethyl phosphate ion and diethyl phosphate ion, especially diethyl phosphate ion.

[0051] Preferred carboxylic acid ions are carboxylic acid ions of the formula R d COO - wherein R d is a C1-C20 alkyl group or a C6-C10 aryl group or aralkyl group, preferably a C1-C8 alkyl group, and in particular acetate ion.

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

[0053] In formula (V), R1 and R3 are preferably organic radicals having 1 to 10 carbon atoms independently of each other. In particular, R1 and R3 are aliphatic radicals, more specifically, alkyl groups, and other aliphatic radicals that do not contain any further heteroatoms. Particularly preferably, R1 and R3 are C1 to C10 or C1 to C4 alkyl groups independently of each other. 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 are preferably, independently, an organic radical having an H atom or 1 to 10 C atoms, and more specifically, R2, R4, and R5 are an H atom or an aliphatic radical. Particularly preferably, R2, R4, and R5 are independently an H atom or an alkyl group, and more specifically, R2, R4, and R5 are independently an H atom or a C1-C4 alkyl group. Very preferably, R2, R4, and R5 are each an H atom. Preferably, n is 1.

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

[0056] Most preferably, the imidazolium salt of formula (V) is selected from the list consisting of 1-ethyl-3-methylimidazolium ethyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-butyl-3-methylimidazolium chloride, and 1-ethyl-3-methylimidazolium acetate.

[0057] A suitable imidazolium salt of formula (V) is commercially available, for example, from BASF under the trade name Basionics®.

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

[0059] The results in Table 2 show that a molecular ratio (B / C) exceeding 120 results in insufficient lap shear strength. This is demonstrated, for example, in the comparison between E1 and E2 and R5. The results in Table 3 also show that when the molecular ratio (B / C) exceeds 120, the lap shear strength becomes insufficient. This is demonstrated, for example, in the comparison between E1 and E2 and R5.

[0060] Furthermore, the results in Table 4 show that when the molecular ratio (B / C) exceeds 120, the impact delamination is insufficient. This is demonstrated, for example, in the comparison between E9-E10 and R10, E11 and R11, and E12 and R12.

[0061] Table 3 further demonstrates that molecular ratios (B / C) of less than 6 result in higher viscosity. This is shown, for example, in the comparison between E3-E8 and R9.

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

[0063] It is also preferable that the molar ratio (B / C) of at least one curing agent B and at least one accelerator C for the epoxy resin is 25 to 75, preferably 26 to 70, and more preferably 40 to 70.

[0064] Such ratios are advantageous in terms of a low increase in viscosity after storage. This is shown, for example, in the comparison between E3-E5 and E6-E8 in Table 3.

[0065] The amount of dicyandiamide is preferably less than 5% by weight, less than 3% by weight, less than 2% by weight, particularly less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.3% by weight, and most preferably less than 0.1% by weight, based on the total weight of the epoxy resin composition. More preferably, the thermosetting one-component epoxy resin composition does not contain dicyandiamide.

[0066] A thermosetting one-component epoxy resin composition is even more preferable if it contains an epoxy resin accelerator other than the at least one accelerator C mentioned above in an amount of less than 0.5% by weight, less than 0.1% by weight, less than 0.05% by weight, particularly 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 thermosetting one-component epoxy resin composition does not contain any epoxy resin accelerator 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 block amines.

[0067] The amount of accelerator C is advantageously 0.5 to 5.0% by weight, particularly 0.75 to 3.0% by weight, and preferably 1.0 to 2.0% by weight, based on the weight of epoxy resin A.

[0068] It is even more preferable when 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 to 95 mmol / mol, preferably 10 to 50 mmol / mol, and more preferably 15 to 25 mmol / mol.

[0069] The ratio (grams) of accelerator C per mole of epoxy groups in epoxy resin A is preferably 0.5 to 9.0 g / mol of epoxy groups, particularly preferably 0.75 to 7.0 g / mol of epoxy groups, more preferably 1.0 to 4.5 g / mol of epoxy groups, even more preferably 1.5 to 3.0 g / mol of epoxy groups, and most preferably 2.0 to 2.5 g / mol of epoxy groups.

[0070] The one-component thermosetting epoxy resin composition preferably contains at least one toughness modifier D. The toughness modifier D may be a solid or a liquid.

[0071] More specifically, the toughness modifier D is selected from the group consisting of terminal block polyurethane polymer D1, liquid rubber D2, and core-shell polymer D3. Preferably, the toughness modifier D is selected from the group consisting of terminal block polyurethane polymer D1 and liquid rubber D2. Particularly preferred is terminal block polyurethane polymer D1.

[0072] This is the case when the toughness modifier D is a terminal block polyurethane prepolymer D1.

[0073] This is preferably a terminally blocked polyurethane polymer D1 blocked with protecting groups that are removed at temperatures above 100°C.

[0074] Preferred protecting groups are, in particular, phenols or bisphenols. Preferred examples of such phenols and bisphenols include phenol, cresol, resorcinol, catechol, cardanol (3-pentadecenylphenol (derived from cashew nut oil)), nonylphenol, styrene, or phenols reacted with dicyclopentadiene, bisphenol A, bisphenol F, and 2,2'-diallylbisphenol A.

[0075] Terminally blocked polyurethane prepolymers are prepared from linear or branched polyurethane prepolymers with isocyanate groups at their ends and one or more isocyanate-reactive compounds. When two or more such isocyanate-reactive compounds are used, the reaction may be carried out sequentially or in a mixture of these compounds.

[0076] To ensure that all NCO groups are converted, it is preferable to carry out the reaction so that one or more isocyanate-reactive compounds are used stoichiometrically or in stoichiometric excess.

[0077] Polyurethane prepolymers having isocyanate-terminated groups include at least one diisocyanate or triisocyanate and polymer Q having terminal amino groups, thiol groups, or hydroxyl groups. PM Polyphenol Q replaced with an optional solution PP It can be prepared from the following.

[0078] Suitable diisocyanates are aliphatic, alicyclic, aromatic, or aromatic aliphatic diisocyanates, particularly methylenediphenyl diisocyanate (MDI), hexamethylene 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, naphthalene 1,5-diisocyanate (NDI), and dicyclohexylmethyl diisocyanate (H 12 These include commercially available products such as MDI, p-phenylenediisocyanate (PPDI), and m-tetramethylxylylenediisocyanate (TMXDI), as well as their dimers. HDI, IPDI, MDI, or TDI are preferred.

[0079] Suitable triisocyanates are trimers or biuretes of aliphatic, alicyclic, aromatic, or aromaticaliphatic diisocyanates, particularly isocyanurates and biuretes of the diisocyanates described in the previous paragraph. Naturally, suitable mixtures of diisocyanates or triisocyanates can also be used.

[0080] Particularly preferred polymer Q having terminal amino groups, thiol groups, or hydroxyl groups PM Polymer Q has two or three terminal amino groups, thiol groups, or hydroxyl groups. PM That is the case.

[0081] Polymer Q PMAdvantageously, the NCO reactive group has an equivalent weight of 300 to 6000, particularly 600 to 4000, preferably 700 to 2200 g / equivalent.

[0082] Preferred polymer Q PM This is a polyol having an average molecular weight of 600 to 6000 daltons, which is selected from the group consisting of polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block polymer, polybutylene glycol, hydroxyl-terminated polybutadiene, hydroxyl-terminated butadiene-acrylonitrile copolymer, and mixtures thereof.

[0083] Particularly preferred polymer Q PM This is an αω-dihydroxypolyalkylene glycol having C2-C6 alkylene groups or mixed C2-C6 alkylene groups, with a terminal amino group, thiol group, or preferably a hydroxyl group. Particularly preferred are polypropylene glycol or polybutylene glycol. Furthermore, polyoxybutylene having a hydroxyl group at the terminal is also particularly preferred.

[0084] Particularly suitable polyphenol Q PP These are bis-, tris-, and tetraphenols. This is understood to mean not only straight phenols but also substituted phenols in any select solution. The nature of the substitution can be very diverse. More specifically, this is understood to mean direct substitution on the aromatic ring to which the phenolic OH group is attached. It is further understood that phenol means not only monocyclic aromatics but also polycyclic or condensed aromatics or heteroaromatics that have a phenolic OH group directly on an aromatic or heteroaromatic system.

[0085] In preferred embodiments, the polyurethane prepolymer comprises at least one diisocyanate or triisocyanate and polymer Q having terminal amino groups, thiol groups, or hydroxyl groups. PM It is prepared from the following. The polyurethane prepolymer is prepared in a manner known to those skilled in the art of polyurethane, in particular polymer QPM It is prepared by using a stoichiometrically excess diisocyanate or triisocyanate relative to the amino group, thiol group, or hydroxyl group.

[0086] Polyurethane prepolymers having isocyanate-terminated groups preferably possess elastic properties. These preferably exhibit a glass transition temperature (Tg) of less than 0°C.

[0087] The toughness modifier D may be liquid rubber D2. This may be, for example, a carboxy-terminated polymer or an epoxy-terminated polymer.

[0088] In the first embodiment, the liquid rubber may be a carboxy-terminated or epoxy-terminated acrylonitrile / butadiene copolymer or a derivative thereof. Such liquid rubbers are commercially available, for example, from Emerald Performance Materials under the names Hypro / Hypox® CTBN, CTBNX, and ETBN. Preferred derivatives are epoxy-grouped elastomer-modified prepolymers, such as those commercially available from Struktol® (Schill+Seilacher Gruppe, Germany) under the Polydis® product line, particularly the Polydis® 36 product line or the Albipox product line (Evonik, Germany).

[0089] In a second embodiment, the liquid rubber may be a polyacrylate liquid rubber that is fully miscible with liquid epoxy resin and separates only during the curing process of the epoxy resin matrix to form microdroplets. Such polyacrylate-based liquid rubbers are available, for example, from Dow under the designation 20208-XPA.

[0090] Naturally, it is also possible to use mixtures of liquid rubber, particularly mixtures of carboxy-terminated or epoxy-terminated acrylonitrile / butadiene copolymers or their derivatives.

[0091] In a third embodiment, the toughness modifier D may be a core-shell polymer D3. The core-shell polymer consists of an elastic core polymer and a rigid shell polymer. Particularly preferred core-shell polymers consist of a core of an elastic acrylate or butadiene polymer encased in a rigid shell of a rigid thermoplastic polymer. This core-shell structure is formed spontaneously as a result of the separation of block copolymers or is defined by the implementation of polymerization as latex polymerization or suspension polymerization with subsequent grafting. Preferred core-shell polymers are called MBS polymers and are commercially available under the trade names Clearstrength™ from Arkema, Paraloid™ from Dow, or F-351™ from Zeon.

[0092] Preferably, the proportion of the toughness modifier D, particularly the terminal block polyurethane polymer D1, is 15 to 45% by weight, particularly 20 to 40% by weight, particularly 22.5 to 35% by weight, particularly 25 to 35% by weight, and more preferably 27.5 to 32.5% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

[0093] This is advantageous because it results in high impact delamination while simultaneously providing high lap shear strength.

[0094] In another preferred embodiment, the composition further comprises at least one filler F. In this case, mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or crushed), dolomite, quartz, silica (molten or precipitated), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic beads, hollow glass beads, hollow organic beads, glass beads, and colored pigments are preferred. Fillers selected from the group consisting of calcium carbonate, calcium oxide, and fumed silica are particularly preferred.

[0095] Advantageously, the total proportion of filler F is 5 to 40% by weight, preferably 10 to 30% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

[0096] In another preferred embodiment, the composition further comprises at least one epoxy-supported reactive diluent G. Such reactive diluents are known to those skilled in the art. Preferred examples of epoxy-supported reactive diluents are as follows: - Monofunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain, C4~C 30 Glycidyl ethers of alcohols, such as butanol glycidyl ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ether, trimethoxysilyl glycidyl ether, etc. - Bifunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain, C2-C 30 Glycidyl ethers of alcohols, such as ethylene glycol glycidyl ether, butanediol glycidyl ether, hexanediol glycidyl ether, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, neopentyl glycol diglycidyl ether, etc. - Glycidyl ethers of trifunctional or polyfunctional, saturated or unsaturated, branched or unbranched, cyclic or open-chain alcohols such as epoxidized castor oil, epoxidized trimethylolpropane, and epoxidized pentaerythritol, or polyglycidyl ethers of aliphatic polyols such as sorbitol, glycerol, and trimethylolpropane. - Glycidyl ethers of phenolic compounds and aniline compounds such as phenylglycidyl ether, cresylglycidyl ether, p-tert-butylphenylglycidyl ether, nonylphenol glycidyl ether, 3-n-pentadecenylglycidyl ether (derived from cashew nut shell oil), and N,N-diglycidylaniline. - Epoxyamines such as N,N-diglycidylcyclohexylamine, - Epoxy mono or dicarboxylic acids such as glycidyl neodecanoate, glycidyl methacrylate, glycidyl benzoate, diglycidyl phthalate, tetrahydrophthalate and hexahydrophthalate, and diglycidyl esters of dimeric fatty acids. - Epoxylated difunctional or trifunctional, low to high molecular weight polyether polyols such as polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether.

[0097] In particular, hexanediol diglycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, polypropylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether are preferred.

[0098] Advantageously, the total proportion of epoxy-supported reactive diluent G is 0.1 to 15% by weight, preferably 0.1 to 5% by weight, particularly preferably 0.1 to 2% by weight, and more preferably 0.2 to 1% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

[0099] The composition may further include, in particular, catalysts, stabilizers, especially thermal and / or light stabilizers, thixotropic agents, plasticizers, solvents, mineral or organic fillers, foaming agents, dyes and pigments, rust inhibitors, surfactants, defoamers and adhesion promoters.

[0100] Suitable plasticizers include phenolalkyl sulfonates or N-butylbenzamides, such as those marketed by Bayer as Mesamoll® or Dellatol BBS.

[0101] Suitable stabilizers include phenols, sterically hindered amines, or N-oxyl compounds such as TEMPO(Evonik), substituted with any select solution, particularly BHT or Wingstay(registered trademark)T(Elkem).

[0102] Particularly preferred one-component epoxy resin compositions include: - Based on the total weight of the epoxy resin composition, 10 to 60% by weight, particularly 30 to 60% by weight, of epoxy resin A having an average of 2 or more epoxy groups per molecule, preferably 50 to 100% by weight, particularly 80 to 100% by weight of epoxy resin A, is liquid epoxy resin, and 0 to 30% by weight, particularly 0 to 20% by weight, of epoxy resin A is solid epoxy resin. - At least one curing agent B for epoxy resins, which is preferably a dihydrazide selected from the group consisting of aromatic dicarboxylic acid dihydrazide B1, preferably isophthalic acid dihydrazide and aliphatic dicarboxylic acid dihydrazide B2, and preferably adipic acid dihydrazide. - At least one accelerator C for at least one curing agent B, wherein formula (V): [ka] (In the formula, R1 is an organic radical having 1 to 20 carbon atoms. R2, R3, R4, and R5 are each organic radicals having either an H atom or 1 to 20 C atoms. X is an anion, and n is 1, 2, or 3, preferably 1. At least one accelerator C is an imidazolium salt of formula (V), preferably an imidazolium salt of formula (V), which 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, most preferably 1-ethyl-3-methylimidazolium ethyl sulfate. - A toughness modifier D, preferably in an amount of 15 to 45% by weight, particularly 20 to 40% by weight, based on the total weight of the thermosetting one-component epoxy resin composition, wherein the toughness modifier D is selected from the group consisting of terminal block polyurethane polymer D1, liquid rubber D2, and core-shell polymer D3, preferably terminal block polyurethane polymer D1. - A filler F in an amount of preferably 5 to 40% by weight, preferably 10 to 30% by weight, based on the total weight of the thermosetting one-component epoxy resin composition, which is selected from the group consisting of calcium carbonate, calcium oxide, and fumed silica. - An epoxy-supported reactive diluent G in an amount preferably 0.1 to 15% by weight, preferably 0.1 to 5% by weight, particularly preferably 0.1 to 2% by weight, and more preferably 0.2 to 1% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

[0103] The anion X of the imidazolium salt of formula (V) is selected from the group consisting of alkyl sulfonate ions, halide ions, more specifically chloride ions, carboxylate ions, phosphate ions, and more specifically dimethyl phosphate ions, and most preferably alkyl sulfonate ions.

[0104] 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 either case, R2, R4 and R5 are each H atoms and n is 1.

[0105] The molar ratio (B / C) of at least one curing agent B and at least one accelerator C for epoxy resin is 6 to 120, preferably 10 to 100, and more preferably 12 to 75.

[0106] 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 to 95 mmol / mol, preferably 10 to 50 mmol / mol, and more preferably 15 to 25 mmol / mol.

[0107] 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 to 550 mmol / mol, preferably 400 to 500 mmol / mol, and more preferably 425 to 475 mmol / mol.

[0108] A preferred one-component epoxy resin composition may be even more advantageous if it consists of the aforementioned components in an amount of more than 80% by weight, preferably more than 90% by weight, particularly preferably more than 95% by weight, particularly preferably more than 98% by weight, and most preferably more than 99% by weight, based on the total weight of the epoxy resin composition.

[0109] The epoxy resin composition of the present invention is advantageous when it has a viscosity of 500 to 4500 Pa·s, particularly 1000 to 3000 Pa·s, preferably 1500 to 2500 Pa·s, at 25°C, measured using a vibrating rheometer with a plate-to-plate configuration, with the following parameters: 5 Hz, measurement gap of 1 mm, plate-to-plate diameter of 25 mm, and 1% deformation. This is advantageous in that good applicability is guaranteed.

[0110] The described thermosetting one-component epoxy resin composition has been found to be particularly suitable for use as a one-component thermosetting adhesive, especially as a thermosetting one-component body adhesive in automotive assembly. Such one-component adhesives have a variety of applications. Such adhesives are necessary for bonding thermostable materials. Thermostable materials are understood to mean materials that are dimensionally stable at curing temperatures of 100-220°C, preferably 120-200°C, at least during the curing time. In particular, such materials include metals and plastics, such as ABS, polyamides, polyphenylene ethers, and composite materials, such as SMC, unsaturated polyester GFP, epoxy or acrylate composite materials. Use in which at least one material is metal is preferred. Particularly preferred uses are considered to be the bonding of the same or different metals in body structures, particularly in the automotive industry. Preferred metals include steel in particular, especially electro-galvanized steel, hot-dip galvanized steel or oil-immersed steel, Bonazinc-coated steel and phosphated steel, as well as aluminum, especially the variants that typically occur in automobile assembly.

[0111] A further aspect of the present invention relates to a bonding process for thermally stable substrates, the process being: i) In particular, the step of applying a thermosetting one-component epoxy resin composition, as described in detail above, to the surface of a metal thermally stable substrate S1, ii) The step of bringing the applied thermosetting one-component epoxy resin composition into contact with the surface of a metal substrate S2 that provides further thermal stability, iii) Heating the composition to a temperature of 100-220°C, particularly 120-200°C, preferably 130-150°C, more preferably 130-140°C. Includes.

[0112] In this specification, the base material S2 consists of the same material as base material S1 or a different material from base material S1. Base materials S1 and / or S2 are, in particular, the aforementioned metals and plastics.

[0113] Preferably, in step iii), the composition is heated to a temperature of 100 to 220°C, particularly 120 to 200°C, preferably 130 to 150°C, more preferably 130 to 140°C, and the composition is left at the aforementioned temperature for 10 minutes to 6 hours, 10 minutes to 2 hours, 10 minutes to 60 minutes, 10 minutes to 30 minutes, 10 minutes to 20 minutes, more preferably 10 minutes to 15 minutes.

[0114] Such a method of bonding thermally stable materials results in an adhesively bonded article, which is preferably a vehicle or a part of a vehicle.

[0115] Another aspect of the present invention, therefore, relates to adhesively bonded articles obtained from the above process. Furthermore, the compositions according to the present invention are suitable not only for automobile assembly but also for other fields of use. In particular, relevant applications in the assembly of means of transport such as ships, trucks, buses or railway vehicles, or in the assembly of consumables such as washing machines should be mentioned.

[0116] Materials bonded using compositions according to the present invention are typically used at temperatures of 120°C to -40°C, preferably 100°C to -40°C, and particularly 80°C to -40°C.

[0117] Particularly preferred uses of the thermosetting one-component epoxy resin composition of the present invention are its use as a thermosetting one-component adhesive for vehicle bodies in automobile assembly, or as a reinforcing compound or as a foaming thermosetting composition for reinforcing voids in structural components and reinforcing elements.

[0118] A further aspect of the present invention relates to a cured epoxy resin composition obtained by heating the thermosetting one-component epoxy resin composition described in detail above.

[0119] The accelerator C of the present invention, which has already been detailed above as a component of the thermosetting epoxy resin composition, has been found to be particularly suitable in combination with the curing agent B of the present invention as an accelerator for thermosetting epoxy resin compositions with a curing temperature of 130 to 150°C.

[0120] More preferably, the composition of the present invention has the following properties.

[0121] After curing at 140°C for 10 minutes, - Measured as described in the experiment, the LSS was >27.5 MPa, especially ≥28 MPa, especially ≥28.5 MPa, especially ≥29 MPa, more preferably ≥30 MPa. - Measured as described in the experiment, the IP is ≥29 N / mm, particularly ≥30 N / mm, particularly ≥31 N / mm, and more preferably ≥32 N / mm. [Examples]

[0122] Several embodiments illustrating the present invention are cited below, but these are not intended to limit the scope of the invention.

[0123] Preparation of toughness modifier ("D-1") 150 g of poly-THF 2000 (OH value 57 mg / g KOH) and 150 g of Liquiflex H (OH value 46 mg / g KOH) were dried under vacuum at 105°C for 30 minutes. Once the temperature had dropped 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 stabilized at 3.10% (calculated NCO content: 3.15%) after 2.0 hours. Subsequently, 96.1 g of cardanol was added as a blocking agent. Stirring was continued under vacuum at 105°C until free NCO could no longer be detected. This product was used as toughness modifier D-1.

[0124] [Table 1]

[0125] Manufacturing of the composition Reference compositions R1 to R12 and compositions E1 to E12 of the present invention were prepared according to the compositions shown in Tables 2 to 4. The amounts listed in Tables 2 to 4 are in parts by weight.

[0126] The molar ratio (B / C) of at least one curing agent B and at least one accelerator C for epoxy resins is shown in Tables 2-4 as "MR(B / C)".

[0127] Test method: Lapped shear strength (LSS) (DIN EN 1465) Anticorit PL 3802-39S (3g / m²) 2 A cleaned test specimen of Elo H420 steel (1.2 mm thick), which had been re-oil-immersed, was bonded with adhesive to the entire 25 x 10 mm bonding area with a layer thickness of 0.3 mm using glass beads as spacers, and cured at an object temperature of 140°C for 10 minutes.

[0128] Using a tensile testing machine, the lap shear strength was measured in triple tests according to DIN EN 1465 at a strain rate of 10 mm / min.

[0129] Impact peel strength (IP RT) (according to ISO 11343) The test specimens were coated with adhesive and Anticorit PL 3802-39S (3g / m²). 2 The sample was made from DC04+ZE steel with dimensions of 90 × 20 × 0.8 mm, which had been re-oil-immersed. In this case, glass beads were used as spacers, and the bonding area was 20 × 30 mm, with a layer thickness of 0.3 mm. The sample was cured at an object temperature of 140°C for 10 minutes. The impact peel strength was measured at 23°C as a triple measurement using a Zwick 450 impact pendulum. The reported impact peel strength is the average force (N / mm) under a measurement curve from 25% to 90% in accordance with ISO 11343.

[0130] Adhesive viscosity / storage stability To evaluate the storage stability of the adhesives, viscosity measurements were repeated after one week of storage at 50°C to confirm the viscosity increase rate after storage. The viscosity increase rate (%) is shown in Tables 3 and 4 under "Viscosity Increase Rate (%)". All compositions had a viscosity of 1500-2500 Pa·s at the start of viscosity measurement. Viscosity was measured using a vibrating rheometer with a plate-to-plate configuration under the following parameters: 5Hz, measurement gap 1mm, plate-to-plate diameter 25mm, 1% deformation.

[0131] [Table 2]

[0132] [Table 3]

[0133] [Table 4]

Claims

1. a) At least one epoxy resin A having an average of two or more epoxy groups per molecule, b) At least one curing agent B for epoxy resin, preferably a dihydrazide selected from the group consisting of aromatic dicarboxylic acid dihydrazide B1 and aliphatic dicarboxylic acid dihydrazide B2, c) At least one accelerator C for at least one curing agent B, wherein formula (V): 【Chemistry 1】 (In the formula, R1 is an organic radical having 1 to 20 carbon atoms. R2, R3, R4, and R5 are each organic radicals having either an H atom or 1 to 20 C atoms. X is an anion, and n is 1, 2, or 3, preferably 1. At least one accelerator C which is an imidazolium salt and A thermosetting one-component epoxy resin composition comprising, 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, most preferably 1-ethyl-3-methylimidazolium ethyl sulfate, and the molar ratio (B / C) of the at least one curing agent B to the at least one accelerator C for the epoxy resin is 6 to 120, preferably 10 to 100, more preferably 12 to 75.

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

3. The thermosetting one-component epoxy resin composition according to claim 1 or 2, characterized in that the curing agent B is preferably an aliphatic dicarboxylic acid dihydrazide B2 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), particularly adipic acid dihydrazide.

4. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 3, characterized in that the anion X of the imidazolium salt of formula (V) is selected from the group consisting of alkyl sulfate ions, alkyl sulfonate ions, halide ions, more specifically chloride ions, bromide ions and iodide ions, thiocyanate ions, dicyanamide ions, carboxylate ions, phosphate ions, more specifically dimethyl phosphate ions and diethyl phosphate ions and phosphonate ions, preferably selected from the group consisting of alkyl sulfate ions, halide ions, more specifically chloride ions, carboxylate ions, phosphate ions, more specifically dimethyl phosphate ions, and most preferably alkyl sulfonate ions.

5. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 4, 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 H atoms and n is 1.

6. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 5, characterized in that the molar ratio (B / C) of at least one curing agent B to at least one accelerator C for the epoxy resin is 12 to 25, preferably 14 to 20.

7. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 5, characterized in that the molar ratio (B / C) of at least one curing agent B to at least one accelerator C for the epoxy resin is 25 to 75, preferably 26 to 70, and more preferably 40 to 70.

8. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 7, characterized in that the 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 to 95 mmol / mol, preferably 10 to 50 mmol / mol, and more preferably 15 to 25 mmol / mol.

9. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 8, characterized in that the 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 to 550 mmol / mol, preferably 400 to 500 mmol / mol, and more preferably 425 to 475 mmol / mol.

10. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 9, further comprising at least one toughness modifier D selected from the group consisting of terminal block polyurethane polymer D1, liquid rubber D2, and core-shell polymer D3, preferably terminal block polyurethane polymer D1.

11. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 10, characterized in that the proportion of epoxy resin A is 10 to 60% by weight, preferably 30 to 60% by weight, and more preferably 40 to 55% by weight, based on the total weight of the one-component epoxy resin composition.

12. Preferably, the thermosetting one-component epoxy resin composition according to any one of claims 1 to 11 is characterized by having a viscosity of 500 to 4500 Pa·s, particularly 1000 to 3000 Pa·s, preferably 1500 to 2500 Pa·s, at 25°C, measured using a vibrating rheometer with a plate-to-plate configuration with the following parameters: 5 Hz, measurement gap of 1 mm, plate-to-plate diameter of 25 mm, and 1% deformation.

13. Use of the thermosetting one-component epoxy resin composition according to any one of claims 1 to 12 as a one-component thermosetting adhesive, particularly as a thermosetting one-component body adhesive in automobile assembly.

14. A process for adhesive bonding of thermally stable substrates, wherein the process is: i) A step of applying a thermosetting one-component epoxy resin composition according to any one of claims 1 to 12 to the surface of a thermally stable metal substrate S1, ii) A step of bringing the applied thermosetting one-component epoxy resin composition into contact with the surface of a metal substrate S2 that provides further thermal stability, iii) Heating the composition to a temperature of 100 to 220°C, particularly 120 to 200°C, preferably 130 to 150°C, more preferably 130 to 140°C. A process comprising the above, wherein the base material S2 is made of the same material as or a different material from the base material S1.

15. The process according to claim 14, wherein in step iii) heating the composition to a temperature of 100 to 220°C, particularly 120 to 200°C, preferably 130 to 150°C, more preferably 130 to 140°C, the composition is left standing at the temperature for 10 minutes to 6 hours, 10 minutes to 2 hours, 10 minutes to 60 minutes, 10 minutes to 30 minutes, 10 minutes to 20 minutes, more preferably 10 minutes to 15 minutes.

16. Adhesive bonded articles obtained from the process described in claim 14 or 15.

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