thermosetting sealing composition

Abstract

The present invention relates to a thermosetting one-component epoxy resin composition comprising at least one liquid aromatic epoxy resin A1, at least one liquid aliphatic epoxy resin A2, at least one curing agent B for the epoxy resin, the curing agent B being a dihydrazide, and at least one toughness improver D. The weight ratio (A1 / A2) of at least one liquid epoxy resin A1 to at least one liquid epoxy resin A2 is 0.25 to 5.0. This thermosetting one-component epoxy resin composition does not exhibit bubble formation at a curing temperature of 210°C and provides good mechanical properties and storage properties, particularly with respect to elongation at break and storage at high temperatures of 50°C to 60°C, and can be used as a sealing composition.

Description

[Technical Field]

[0001] The present invention relates particularly to the field of sealing compositions for automobile bodies. [Background technology]

[0002] In automobile bodies, individual metal sheets are joined together. The metal sheets used are coated with oil to minimize corrosion as much as possible. Furthermore, typically, the vehicle body is passed through a CDC bath (CDC = cathodic coating) at the end of assembly, where the body is coated with so-called CDC paint and then baked in a CDC oven. A good CDC coating over the entire surface area contributes significantly to corrosion resistance and is fundamental for the long-term use of the vehicle.

[0003] Therefore, these oils are typically applied to metal sheets, such as steel substrates, which are then coated with a sealer. This sealer needs to adhere well to the oil-coated metal sheet, and does not require curing with heat or UV radiation before immersion in the paint bath. Nevertheless, it needs to increase in strength rapidly.

[0004] International Publication No. 2012 / 084806 provides a thermosetting sealant compound composition having a dual curing mechanism. On the one hand, a skin is rapidly formed by the reaction of polyisocyanate and polyaldimine in contact with air and / or atmospheric humidity, allowing the sealant compound to be reliably passed through a CDC bath without damage. High-quality coatings can then be deposited onto the sealant compound. In the other step, the sealant compound is cured by heat, such as in a typical CDC oven. However, in some cases, the problem of air bubble formation exists in these sealers.

[0005] It is even more important that thermosetting encapsulating compositions have good mechanical properties and storage properties, particularly in terms of elongation at break and storage at high temperatures of 50°C to 60°C. [Overview of the project]

Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to provide a thermosetting one-component epoxy resin composition that does not show bubble formation at a curing temperature of 210° C., and that has good mechanical properties and storage properties, particularly elongation at break performance and storage at high temperatures of 50° C. to 60° C., and can be used as a sealing composition.

Means for Solving the Problems

[0007] Surprisingly, it has been found that this object can be achieved by the thermosetting one-component epoxy resin composition according to claim 1.

[0008] Therefore, the thermosetting one-component epoxy resin composition is particularly suitable for use as a sealing compound in the body of an automobile.

[0009] A further aspect of the present invention is the subject matter of the further independent claims. Particularly preferred embodiments of the present invention are the subject matter of the dependent claims.

Modes for Carrying Out the Invention

[0010] The present invention is a thermosetting one-component epoxy resin composition, a) at least one liquid epoxy resin A1 having an average of more than one epoxy group per molecule, which is an aromatic liquid epoxy resin, b) at least one liquid epoxy resin A2 having an average of more than one epoxy group per molecule, - glycidyl ethers of difunctional saturated, branched or unbranched, cyclic or acyclic C2-C 30 alcohols, - glycidyl ethers of trifunctional or polyfunctional saturated, branched or unbranched, cyclic or acyclic alcohols, and - epoxidized difunctional or trifunctional polyether polyols and at least one liquid epoxy resin A2 selected from the group consisting of c) At least one curing agent B for the epoxy resin, which is a dihydrazide, preferably at least one curing agent B selected from the group consisting of aromatic dicarboxylic acid dihydrazide B1 and aliphatic dicarboxylic acid dihydrazide B2, and d) At least one toughness improver D selected from the group consisting of terminal-blocked polyurethane polymer D1, liquid rubber D2 and core-shell polymer D3, preferably consisting of terminal-blocked polyurethane polymer D1 It relates to a thermosetting one-component epoxy resin composition containing the same.

[0011] The weight ratio (A1 / A2) of at least one liquid epoxy resin A1 to at least one liquid epoxy resin A2 is 0.25 to 5.0, preferably 0.33 to 3.0, more preferably 0.5 to 2.0, and most preferably 0.75 to 1.5.

[0012] As used herein, the term "polymer" on the one hand means a group of macromolecules that are chemically uniform but different in terms of degree of polymerization, molecular weight and chain length and are synthesized by polyreactions (polymerization, polyaddition, polycondensation). On the other hand, this term also includes derivatives of such groups of macromolecules obtained by polyreactions, that is, compounds obtained by reactions of functional groups on a predetermined molecule, such as addition or substitution, which may be chemically uniform or chemically non-uniform. This term further includes so-called prepolymers, that is, reactive oligomer precursors in which functional groups are contained in the structure of the macromolecule.

[0013] As used herein, substance names starting with "poly", such as polyisocyanate, polyaldimine, polyamine, polyol, polymercaptan or polyglycidyl ether, mean substances that formally contain two or more functional groups per molecule that also appear in their names.

[0014] Unless otherwise specified, all industrial standards mentioned herein relate to the version in force on the first filing date.

[0015] The terms “mass” and “weight” are used synonymously herein. Therefore, “percentage by weight” (weight%) is, unless otherwise specified, a percentage mass fraction relating to the mass (weight) of the entire composition or, depending on the context, the entire molecule.

[0016] In relation to polymers, the term "molecular weight" as used herein generally refers to the average molecular weight M measured relative to a polystyrene standard using gel permeation chromatography (GPC). n It means...

[0017] Room temperature as used herein is understood to be 25°C.

[0018] In this specification, the term “vehicle” is understood to mean any means of transport by water, ground, and air. Such means of transport include, in particular, ships, vehicles such as automobiles, buses, cars, and trucks, and rail vehicles such as trams and railway vehicles.

[0019] The terms "epoxide group" or "epoxy group" are, [ka] It is understood to mean a structural element of [something].

[0020] In this specification, the dashed lines in the formulas represent the bonds between each substituent and each molecular group in each case.

[0021] In this specification, a "one-component" composition means a curable composition in which all components of the composition are mixed, stored together in the same container, and are stable during long-term storage at room temperature, so that there is little or no significant change in their usability or application properties due to storage, and such compositions harden after application by the action of heat.

[0022] The thermosetting one-component epoxy resin composition comprises a) an aromatic liquid epoxy resin, which comprises at least one liquid epoxy resin A1 having an average of more than one epoxy group per molecule.

[0023] The preferred liquid epoxy resin A1 is formula (II) [ka] It has.

[0024] In this formula, substituents R''' and R'''' are independently H or CH3. Furthermore, the subscript r has a value between 0 and 1. Preferably, r has a value less than 0.2.

[0025] Therefore, these are preferably diglycidyl ethers of bisphenol A (DGEBA), bisphenol F, and bisphenol A / F (where the name "A / F" refers to a mixture of acetone and formaldehyde used as reactants in its preparation). Such liquid resins are available, for example, as Araldite® GY 250, Araldite® PY 304, Araldite® GY 282 (Huntsman), or DER® 331, or DER® 330 (Olin), or Epikote 828 (Hexion).

[0026] Furthermore, so-called novolacs are suitable epoxy resins A1. These are particularly represented by the following formula: [ka] It has, in the formula, R2 = [ka] Alternatively, it is CH2, R1=H or methyl, and z=0-7.

[0027] In particular, these are phenols or cresol novolacs (R2=CH2).

[0028] Such epoxy resins are marketed under trade names EPN or ECN and Tactix® 556 from Huntsman or DEN® from Dow Chemical's product line.

[0029] Bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, or bisphenol A / F diglycidyl ether, particularly Araldite® GY 240, Araldite® GY 250, Araldite® GY 281, Araldite® GY 282, Araldite® GY 285, Araldite® PY 304 or Araldite® PY 720 (all manufactured by Huntsman) or DER® 330, DER® 331, DER® 332, DER® 336, DER® 351, DER® 352, DER® 354 or DER® 356 (all manufactured by Olin) or novolac glycidyl ether are particularly preferred.

[0030] A novolac glycidyl ether derived from phenol-formaldehyde novolac, also known as epoxyphenol novolac resin, is preferred.

[0031] Such novolac glycidyl ethers are commercially available from, for example, Olin, Huntsman, Momentive, or Emerald Performance Materials. Preferred types include DEN® 431, DEN® 438, or DEN® 439 (Olin), Araldite® EPN 1179, Araldite® EPN 1180, Araldite® EPN 1182, or Araldite® EPN 1183 (Huntsman), Epon® 154, Epon® 160, or Epon® 161 (Momentive), or Epalloy® 8250, Epalloy® 8330, or Epalloy® 8350 (Emerald Performance Materials).

[0032] Preferably, the liquid epoxy resin A1 is a liquid epoxy resin of formula (II).

[0033] The thermosetting one-component epoxy resin composition is b) at least one liquid epoxy resin A2 having an average of more than one epoxy group per molecule, - Particularly selected from the group consisting of ethylene glycol, butanediol, hexanediol, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, and neopentyl glycol diglycidyl ether, bifunctional saturated, branched or unbranched, cyclic or chain-like C2-C2~C2 30 Glycidyl ether of alcohol, - In particular, glycidyl ethers of trifunctional or polyfunctional saturated, branched or unbranched, cyclic or chain-like alcohols selected from the group consisting of epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol and sorbitol, glycerol or trimethylolpropane, and epoxidized polyglycidyl ethers of aliphatic polyols, - Epoxy difunctional polyether polyols selected from the group consisting particularly of polyethylene glycol diglycidyl ether and polypropylene glycol diglycidyl ether It comprises at least one liquid epoxy resin A2 selected from the group consisting of the following.

[0034] More preferably, the liquid epoxy resin A2 is a bifunctional saturated, branched or unbranched, cyclic or chain-type C2-C resin selected from the group consisting of ethylene glycol, butanediol, hexanediol, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, and neopentyl glycol diglycidyl ether. 30 It is selected from glycidyl ethers of alcohols. Most preferably, liquid epoxy resin A2 is a glycidyl ether of hexanediol.

[0035] More preferably, the total ratio of liquid epoxy resins A1 and A2 (A1 + A2) is 5 to 20% by weight, preferably 7.5 to 15% by weight, and more preferably 10 to 12.5% ​​by weight, based on the total weight of the one-component epoxy resin composition.

[0036] The weight ratio (A1 / A2) of at least one liquid epoxy resin A1 to at least one liquid epoxy resin A2 is 0.25 to 5.0, preferably 0.33 to 3.0, more preferably 0.5 to 2.0, and most preferably 0.75 to 1.5.

[0037] At weight ratios below 0.33, storage stability is insufficient, especially at high temperatures. This can be seen, for example, in the comparison between E1 and Ref1 in Table 2.

[0038] At weight ratios exceeding 5.0, the elongation performance becomes insufficient, resulting in extremely high viscosity. This can be seen, for example, in the comparison between E1 and Ref2 in Table 2.

[0039] The preferred weight ratio described above is advantageous in terms of a good balance of high tensile strength, elongation at break, Shore A value, and storage stability. This can be seen, for example, in the comparison between E11 and Ref4, E10, and E12 in Table 3.

[0040] The composition of the present invention also includes at least one curing agent B for epoxy resins. The curing agent B is a dihydrazide, preferably selected from the group consisting of aromatic dicarboxylic acid dihydrazides B1 and aliphatic dicarboxylic acid dihydrazides B2.

[0041] 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.

[0042] 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® (A&C Catalysts).

[0043] Preferably, the curing agent B is an aliphatic dicarboxylic acid dihydrazide B2, and is preferably 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).

[0044] Dihydrazide adipic acid, 1,20-dihydrazide 8,12-eicosadiene dioate (UDH), and 4-isopropyl-2,5-dioxoimidazolidine-1,3-di(propionohydrazide) (VDH) are preferred. Dihydrazide adipic acid is most preferred.

[0045] 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® (A&C Catalysts).

[0046] Preferably, in a thermosetting one-component epoxy resin composition, the ratio of the total number of epoxy groups of liquid epoxy resins A1 and A2 in moles to the ratio of curing agent B in moles ((A1+A2) / B) is 3 to 8, preferably 4 to 7, more preferably 5 to 7, and most preferably 5.5 to 6.5.

[0047] A ratio greater than 8 is unfavorable for smaller Shore A values. A ratio less than 3 is unfavorable for smaller values ​​of elongation at break and storage stability.

[0048] Preferably, the thermosetting one-component epoxy resin composition further comprises at least one accelerator C for the epoxy resin, which is advantageous in particular with respect to curing at lower temperatures.

[0049] Preferably, accelerator C for epoxy resin is selected from the list consisting of substituted ureas, imidazoles, imidazolines, and block amines, particularly substituted ureas.

[0050] This is preferably formula (III) [ka] Contains a substituted urea, in the formula R 1 and R 2 Independently, each is a monovalent alkyl group having a hydrogen atom or 1 to 10 carbon atoms, and optionally including an oxygen atom, a nitrogen atom and / or an aromatic unit, or a combination thereof forms a divalent alkyl group having 1 to 10 carbon atoms, and may further include a nitrogen atom or an aromatic unit, R 3 and R 4 This is a monovalent alkyl group that independently has a hydrogen atom or 1 to 10 carbon atoms, and optionally also has an oxygen atom or a nitrogen atom, and the subscript n has a value of 1 or 2.

[0051] The substituted urea of formula (III) is preferably selected from the group consisting of p-chlorophenyl-N,N-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3,4-dichlorophenyl-N,N-dimethylurea (diuron), N-methylurea, N,N-dimethylurea, N,N'-dimethylurea, N,N,N'-trimethylurea, N,N,N',N'-tetramethylurea, and derivatives thereof in which some or all of the methyl groups are replaced by ethyl groups.

[0052] Preferably, R 1 and R 2 are independently a hydrogen atom or a monovalent linear or branched alkyl group having 1 to 10, preferably 1 to 5, more preferably 1 to 4 carbon atoms, and optionally, the combination thereof forms a divalent alkyl group and forms a ring structure together with the adjacent nitrogen atom, and / or R 3 and R 4 are independently a hydrogen atom or represent a monovalent linear or branched alkyl group having 1 to 10, preferably 1 to 5, more preferably 1 to 4 carbon atoms, and optionally, the combination thereof forms a divalent alkyl group and forms a ring structure together with the adjacent nitrogen atom.

[0053] A very particularly preferred substituted urea of formula (III) is one in which both R 1 and R 2 in formula (III) are hydrogen atoms, and / or both R 3 and R 4 are ethyl or methyl groups, preferably methyl groups.

[0054] Further preferred urea derivatives of formula (III) are those in which all of R 1 , R 2 , R 3 and R 4 in formula (III) represent ethyl or methyl, preferably methyl groups, or all of R 1 , R 2 and R 3R represents ethyl or methyl, preferably methyl, 4 Is it a hydrogen atom, or R 1 and R 4 Both represent hydrogen atoms, and R 2 and R 3 Examples of urea derivatives include those in which both are ethyl or methyl groups, preferably methyl groups.

[0055] Suitable urea derivatives are commercially available, for example, under the trade names Dyhard® (from AlzChem Group AG), Omicure® (from CVC Thermoset Specialties), Amicure® (from Evonik), and also from Sigma Aldrich.

[0056] Accelerator C has molecules with a molecular weight of less than 1000 g / mol, especially between 80 and 800 g / mol. If the molecular weight is larger, the accelerating effect decreases, the required amount increases significantly, and therefore the mechanical properties may become insufficient.

[0057] The amount of accelerator C is advantageously 0.005 to 1.0% by weight, particularly 0.01 to 0.5% by weight, and preferably 0.05 to 0.25% by weight, based on the total weight of liquid epoxy resins A1 and A2.

[0058] The ratio of accelerator C in grams per mole of the total epoxy groups of liquid epoxy resins A1 and A2 ((A1+A2) / C) is preferably 0.01 to 0.5 g / mol of epoxy groups, particularly 0.05 to 0.3 g / mol of epoxy groups, more preferably 0.075 to 0.2 g / mol of epoxy groups, and most preferably 0.08 to 0.15 g / mol of epoxy groups.

[0059] The one-component thermosetting epoxy resin composition contains at least one toughness improver D. The toughness improver D may be a solid or a liquid, preferably a liquid.

[0060] The toughness improver D is selected from the group consisting of terminal block polyurethane polymer D1, liquid rubber D2, and core-shell polymer D3. Preferably, the toughness improver D is selected from the group consisting of terminal block polyurethane polymer D1 and liquid rubber D2. Terminal block polyurethane polymer D1 is particularly preferred.

[0061] A terminally blocked polyurethane polymer D1, which is blocked by blocking groups that detach at temperatures above 100°C, is preferred.

[0062] Preferred blocking groups are, in particular, phenols or bisphenols. Preferred examples of such phenols and bisphenols include phenol, cresol, resorcinol, catechol, 4-hydroxyanisole (HQMME), cardanol (3-pentadecenylphenol (obtained from cashew nut shell oil)), nonylphenol, styrene, or phenols reacted with dicyclopentadiene, bisphenol A, bisphenol F, and 2,2'-diallylbisphenol A.

[0063] Terminal-block polyurethane prepolymers are prepared from linear or branched polyurethane prepolymers having 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 using a mixture of these compounds.

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

[0065] 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 and / or optionally substituted polyphenol Q PP, preferably polymer Q having terminal amino groups, thiol groups, or hydroxyl groups PM It can be prepared from the above.

[0066] 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 are commercially available products such as MDI, p-phenylenediisocyanate (PPDI), m-tetramethylxylylenediisocyanate (TMXDI), and their dimers. HDI, IPDI, MDI, or TDI are preferred.

[0067] Suitable triisocyanates are trimers or biuretes of aliphatic, alicyclic, aromatic, or aromaticaliphatic diisocyanates, particularly isocyanurates and biuretes of the diisocyanates described in the preceding paragraph. Naturally, suitable mixtures of diisocyanates or triisocyanates can also be used.

[0068] Particularly suitable polymer Q having terminal amino groups, thiol groups, or hydroxyl groups PM Polymer Q having two or three terminal amino groups, thiol groups, or hydroxyl groups. PM That is the case.

[0069] Polymer Q PM Advantageously, the equivalent weight is 300 to 6000, particularly 600 to 4000, preferably 700 to 2200 g / equivalent of NCO reactive groups.

[0070] Preferred polymer Q PMThis is a polyol having an average molecular weight of 600 to 6000 daltons, 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.

[0071] Particularly preferred polymer Q PM This is an α-ω-dihydroxypolyalkylene glycol having C2-C6 alkylene groups or mixed C2-C6 alkylene groups, and having an amino, thiol, or preferably hydroxyl group at its terminus. Polypropylene glycol or polybutylene glycol is particularly preferred. Furthermore, hydroxyl-terminated polyoxybutylene is particularly preferred.

[0072] Especially appropriate polyphenol Q PP These are bis, tris, and tetraphenols. This is understood to mean not only linear phenols but also, in some cases, substituted phenols. The nature of the substitution can vary considerably. In particular, this is understood to mean direct substitution on the aromatic ring to which the phenolic OH group is attached. Furthermore, phenols are understood to mean not only monocyclic aromatics but also polycyclic or fused aromatics or heterocyclic aromatics that have a phenolic OH group directly on an aromatic or heterocyclic aromatic system.

[0073] In one preferred embodiment, the polyurethane prepolymer comprises at least one diisocyanate or triisocyanate and polymer Q having terminal amino groups, thiol groups, or hydroxyl groups. PM Polyurethane prepolymers are prepared from the following. Polyurethane prepolymers are prepared by methods well known to those skilled in the field of polyurethane, in particular polymer Q PM It is prepared by using a stoichiometrically excess diisocyanate or triisocyanate relative to the amino group, thiol group, or hydroxyl group.

[0074] Polyurethane prepolymers having isocyanate-terminated groups preferably possess elastic properties. These preferably exhibit a glass transition temperature (Tg) of less than 0°C.

[0075] The toughness enhancer D may be liquid rubber D2. This may be, for example, a carboxy-terminated or epoxy-terminated polymer.

[0076] 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 from Emerald Performance Materials, for example, under the names Hypro / Hypox® CTBN, CTBNX, and ETBN. Suitable derivatives are epoxy-grouped elastomer-modified prepolymers commercially available from the Polydis® product line, particularly the Polydis® 36 production line, by Struktol® (Schill+Seilacher Gruppe, Germany), or the Albipox product line (Evonik, Germany).

[0077] In a second embodiment, the liquid rubber may be a polyacrylate liquid rubber that is well miscible with liquid epoxy resin and separates to form microdroplets only during the curing process of the epoxy resin matrix. Such a polyacrylate liquid rubber is available from Dow, for example, under the designation 20208-XPA.

[0078] Naturally, mixtures of liquid rubber, particularly mixtures of carboxy-terminated or epoxy-terminated acrylonitrile / butadiene copolymers or their derivatives, can also be used.

[0079] In a third embodiment, the toughness enhancer D may be a core-shell polymer D3. The core-shell polymer consists of an elastic core polymer and a rigid shell polymer. Particularly suitable core-shell polymers consist of an elastic acrylate or butadiene polymer shell encased in a rigid thermoplastic polymer shell. This core-shell structure is either formed spontaneously as a result of the separation of block copolymers, or its boundaries are defined by polymerization as latex polymerization or suspension polymerization, followed by grafting. Preferred core-shell polymers are those called MBS polymers, which are commercially available from Arkema under the trade name Clearstrength®, from Dow under Paraloid®, or from Zeon under F-351®.

[0080] Preferably, the ratio of toughness improver D, particularly 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.

[0081] This is advantageous in that it yields a larger growth rate. This can be seen, for example, in the comparison between E6 and E7 in Table 2.

[0082] The weight ratio ((A1+A2) / D) of the sum of at least one liquid epoxy resin A1 and at least one liquid epoxy resin A2 to at least one toughness improver D is preferably 0.25 to 0.6, more preferably 0.3 to 0.5, and more preferably 0.35 to 0.55.

[0083] Such a weight ratio is advantageous for larger elongation values. This can be seen, for example, in the comparison between E6 and E7 in Table 2.

[0084] Preferably, the thermosetting one-component epoxy resin composition further comprises at least one plasticizer PL.

[0085] Preferably, at least one plasticizer PL is selected from the group consisting of phthalate diesters (also known as "phthalates"), particularly dialkyl phthalates, especially preferably di-C6~C13-alkyl phthalates and alkylbenzyl phthalates, dialkyl terephthalates, aliphatic carboxylic acid diesters, polyester polymers, adipic acid polyesters, phosphate esters, preferably triaryl and alkylaryl phosphates, trimellitic acid esters, benzoic acid and dibenzoic acid esters, phenol citrate esters and alkylsulfonic acid esters. More preferably, at least one plasticizer PL is selected from trimellitic acid esters.

[0086] Specific examples of preferred plasticizers are selected from the group consisting of dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), diisononyl phthalate (DINP), diallyl phthalate (DAP), di-2-ethylhexyl phthalate (DEHP or DOP), diisodecyl phthalate (DIDP), di(2-propylheptyl) phthalate (DPHP), di-2-ethylhexyl adipate (DOA), di(tridecyl) phthalate (DTDP), butyl benzyl phthalate (BBP), dihexyl phthalate, tri-2-ethylhexyl trimellitate (TOTM), condensation products of glycols such as 1,3-butylene glycol and dibasic organic acids such as adipic acid, and dipropylene glycol dibenzoate, with tri-2-ethylhexyl trimellitate (TOTM) being the most preferred.

[0087] The weight ratio ((A1+A2) / PL) of the sum of at least one liquid epoxy resin A1 and at least one liquid epoxy resin A2 to at least one plasticizer PL is preferably 1 to 10, preferably 1.25 to 5, more preferably 1.5 to 3, even more preferably 1.75 to 2.5, and most preferably 1.8 to 2.2.

[0088] Such weight ratios are advantageous in terms of higher elongation values ​​and lower viscosity. This can be seen, for example, in the comparison between E6 and E1-E5 in Table 2.

[0089] Advantageously, the overall proportion of at least one plasticizer PL is 2 to 10% by weight, preferably 4 to 8% by weight, more preferably 5 to 7% by weight, and most preferably 5.5 to 6% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

[0090] More preferably, the thermosetting one-component epoxy resin composition further comprises at least one filler F. Herein, mica, talc, kaolin, wollastonite, feldspar, titanium oxide, syenite, chlorite, bentonite, montmorillonite, (settled or crushed) calcium carbonate, dolomite, quartz, (fused or settled) silica, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic beads, hollow glass beads, hollow organic beads, glass beads, and coloring pigments are preferred. Fillers selected from the group consisting of calcium carbonate, calcium oxide, talc, titanium oxide, and fumed silica are particularly preferred.

[0091] Advantageously, the total proportion of the filler F is 35 to 60% by weight, preferably 45 to 55% by weight, and more preferably 47.5 to 52.5% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

[0092] Such a favorable range is advantageous with respect to larger growth values. This can be seen, for example, in the comparison between E6 and E8 and E9 in Table 2.

[0093] In a further preferred embodiment, the thermosetting one-component epoxy resin composition comprises at least one epoxy-containing reactive diluent G containing less than 3% by weight of one epoxy group based on the total weight of the one-component epoxy resin composition. Such reactive diluents are well known to those skilled in the art. Preferred examples of epoxy-containing reactive diluents are: - Monofunctional saturated or unsaturated, branched or unbranched, cyclic or chain-like C4-C 30Glycidyl 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. - Glycidyl ethers of phenolic compounds having only one OH group, such as phenyl glycidyl ether, cresyl glycidyl ether, p-tert-butylphenyl glycidyl ether, nonylphenol glycidyl ether, and 3-n-pentadecenyl glycidyl ether (obtained from cashew nut shell oil). That is the case.

[0094] Phenylglycidyl ether, cresylglycidyl ether, p-tert-butylphenylglycidyl ether, nonylphenol glycidyl ether, and 3-n-pentadecenylglycidyl ether are particularly preferred.

[0095] The amount of at least one epoxy-containing reactive diluent G containing only one epoxy group is preferably 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 any such reactive diluent G.

[0096] This is advantageous with respect to bubble formation at curing temperatures above 210°C. This is demonstrated, for example, by comparing Ref3 with Ref1-2 and E1-E9. Such bubble formation causes a significant decrease in the mechanical properties of the cured material.

[0097] In particular, the A4 complex viscosity h can be determined using a vibratory viscometer with a plate-plate configuration at 10 Hz, with a measurement gap of 1 mm, a plate-to-plate diameter of 25 mm, and deformations of 0.01 to 10%, and a deformation of 10%. *The viscosity of the epoxy resin composition of the present invention at 23°C, as measured by the measurement parameters, is advantageous when it is 150 to 900 Pa·s, particularly 200 to 800 Pa·s, preferably 200 to 400 Pa·s, and more preferably 250 to 350 Pa·s. This is advantageous in that it ensures good coatability.

[0098] Thermosetting one-component epoxy resin compositions are prepared and stored in the absence of moisture. This refers to storage stability, meaning that they can be stored for several months or up to a year or more in a suitable packaging container or configuration, such as a drum, bag, or cartridge, without any change in their cured properties or, to a reasonable extent, their application characteristics or properties with respect to their use. Storage stability is usually determined by measuring viscosity.

[0099] Thermosetting one-component epoxy resin compositions are characterized by excellent storage stability. The viscosity change of the composition in an airtight aluminum cartridge after 7 days of storage at 60°C in a circulating air oven can be used as a measure of long-term storage stability at room temperature. Experiments have shown that a maximum doubling of viscosity, i.e., an increase of up to 150%, is acceptable for the reliable use of the composition as a sealing compound. The composition is very well-suited to this requirement and has been found to achieve viscosity changes of less than 120%, and in some cases even less than 100%.

[0100] The thermosetting one-component epoxy resin composition according to the present invention exhibits very few or no bubbles during curing at 210°C. Therefore, these compositions possess excellent mechanical properties and optimal visual characteristics. This is particularly important because, when used as a sealing compound, a CDC coating is applied to the surface of the composition, and thus the sealing compound surface can be seen through the CDC coating and / or the coloring coating subsequently applied thereon.

[0101] Furthermore, the composition becomes primarily elastic after heat curing. This is particularly advantageous for seals that are subjected to impact or movement during use.

[0102] This combination of advantageous properties makes thermosetting one-component epoxy resin compositions particularly useful as sealing compounds for automobile bodies, especially in engine compartments, or for doors, trunk lids, tailgates, or hoods. In particular, they can also be used as sealing compounds in flange bends, as disclosed in International Publication No. 2008 / 077918A1.

[0103] In another aspect of the present invention, a sealing method, i) A step of applying a thermosetting one-component epoxy resin composition such as the one described above to a substrate (S), ii) Heating the thermosetting one-component epoxy resin composition to a temperature above 120°C, particularly 160°C to 220°C, to form a cured thermosetting one-component epoxy resin composition. A method including the above is disclosed.

[0104] Suitable materials for the base material (S) include metals in particular, especially metals used in the structure of automobile bodies. Such materials include steel in particular, especially electroplated, flame-galvanized, oil-coated steel, Bonazinc-coated steel, and subsequently phosphate-treated steel or aluminum, especially in the modified forms commonly found in automotive engineering. Such materials include steel sheets or aluminum sheets.

[0105] Application, or deposition, is preferably carried out automatically, particularly in the form of a bead. However, the thermosetting one-component epoxy resin composition can also be sprayed onto the surface. Other application methods are also conceivable, such as swirl application, flat stream spraying, mini flat stream spraying, and thin stream spraying at speeds >200 mm / s. Furthermore, manual application or manual touch-up of the applied thermosetting one-component epoxy resin composition with a spatula or paint brush is also possible.

[0106] Therefore, in another aspect, the present invention also relates to a coated substrate obtained by applying a thermosetting one-component epoxy resin composition, such as those described in detail above, to the surface of a substrate.

[0107] In one particularly preferred embodiment, the thermosetting one-component epoxy resin composition is applied to an oil-coated steel plate. The advantage of the composition is that it adheres well to such a substrate and cures with very little blasting.

[0108] Between step i) and step ii), step ia): ia) A step of applying a paint, particularly a CDC paint, to a thermosetting one-component epoxy resin composition. It is preferable to do so.

[0109] Those skilled in automotive engineering are familiar with the concept of CDC coating, which means applying paint to a metal sheet in a CDC bath (CDC = cathode immersion coating).

[0110] Step ii) is preferably carried out in a CDC oven.

[0111] When a thermosetting one-component epoxy resin composition is heated, curing occurs, and this is how the thermosetting one-component epoxy resin composition achieves its final strength.

[0112] Preferably, in step ii), the composition is heated to a temperature of 100-220°C, particularly 120-200°C, preferably 130-150°C, more preferably 130-140°C, and the composition is maintained at the above 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.

[0113] Thermosetting one-component epoxy resin compositions are particularly suitable for sealing gaps.

[0114] Therefore, in step i), it is preferable to apply a thermosetting one-component epoxy resin composition to or within the gap, the gap being bounded by two surfaces, the base material (S) and the second base material (S2), the second base material (S2) being made of the same material as or different from the base material (S).

[0115] Therefore, sealed articles are obtained by the method described above.

[0116] More preferably, the compositions of the present invention have the following properties.

[0117] After curing at 180°C for 30 minutes, - Measure as described in the experiment, with a TS of 2-6 MPa, preferably 3-5 MPa. - Measured as described in the experiment, EB ≥80%, preferably ≥100%. - Measured as described in the experiment, Shore A is 40-90, preferably 60-90. [Examples]

[0118] The following are some examples that further illustrate the present invention, but are not intended to limit its scope.

[0119] Preparation of toughness improver ("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 reduced pressure at 105°C for 30 minutes. After reducing the temperature to 90°C, 61.5 g of IPDI and 0.14 g of dibutyltin dilaurate were added. The reaction was carried out under reduced pressure at 90°C until the NCO content remained constant at 3.10% after 2.0 hours (calculated NCO content: 3.15%). Subsequently, 96.1 g of cardanol was added as a blocking agent. Stirring was continued under reduced pressure at 105°C until free NCO could no longer be detected. This product itself was used as toughness improver D-1.

[0120] [Table 1]

[0121] Manufacturing of the composition The reference compositions Ref1 to Ref4 and compositions E1 to E12 of the present invention were prepared according to the compositions shown in Tables 2 and 3. The amounts listed in Tables 2 and 3 are in parts by weight. The ratio of the total epoxy groups of liquid epoxy resins A1 and A2 in moles to the ratio of curing agent B in moles ((A1+A2) / B) is 6. The ratio of accelerator C in grams per mole of the total epoxy groups of liquid epoxy resins A1 and A2 ((A1+A2) / C) is 0.1.

[0122] Test method: Bubble formation (BF) The mixed composition was applied to a silicone mold to form a layer 2 mm thick, and cured at 210°C for 30 minutes. After curing, the formation of bubbles in the test specimens was analyzed. If bubbles formed, the sample was evaluated as "present," and if no bubbles formed, the sample was evaluated as "absent."

[0123] Tensile strength (TS) and elongation at break (EB) (DIN EN ISO 527) These mechanical properties were measured using a dumbbell-shaped bar with a thickness of 2 mm and a length of 750 mm (test specimen type 5A according to DIN EN ISO 527). After curing at 180°C for 30 minutes, the specimens were measured under standard conditions at a tensile speed of 200 mm / min (TS, EB). Tensile strength and elongation at break were determined in accordance with DIN EN ISO 527.

[0124] Shore A (DIN 53505) Shore A hardness was measured in accordance with DIN 53505 using a 6 mm thick specimen cured at 180°C for 30 minutes.

[0125] Viscosity / Storage Stability of the Composition At a temperature of 23°C, the viscosity of the composition was measured one day after manufacturing using a plate-to-plate vibration on an Anton Paar MCR 101 rheometer with the following parameters: 10Hz, measurement gap 1mm, plate-to-plate diameter 25mm, deformation of 0.01-10%, and the A4 complex viscosity h obtained at 10% deformation. * Measurement of [value]. This measurement is shown in Tables 2 and 3 under "Visco initial 23℃".

[0126] To evaluate the storage stability of the adhesives, viscosity measurements were repeated after storage at a specified temperature for a specified time in units of weeks (W) or months (M), and the percentage increase in viscosity obtained after storage was confirmed. The measured viscosity in Pa·s, measured at 23°C after storage at 50°C and 60°C for one week, is shown in Table 2 for "Visco 1W 50°C" and "Visco 1W 60°C," respectively. The measured viscosity in Pa·s, measured at 23°C after storage at 23°C for one month, is shown in Table 3 for "Visco 1M 23°C." The values ​​in parentheses indicate the percentage increase in viscosity.

[0127] [Table 2]

[0128] [Table 3]

[0129] [Table 4]

Claims

1. A thermosetting one-component epoxy resin composition, a) At least one liquid epoxy resin A1, which is an aromatic liquid epoxy resin, having an average of more than one epoxy group per molecule, b) At least one liquid epoxy resin A2 having more than one epoxy group on average per molecule, - Bifunctional saturated, branched or unbranched, cyclic or chain-type C ２ ~C ３０ Glycidyl ether of alcohol, - Trifunctional or polyfunctional saturated, branched or unbranched, cyclic or chain-like glycidyl ethers of alcohols, and - Epoxy-modified difunctional polyether polyols At least one liquid epoxy resin A2 selected from the group consisting of, c) At least one curing agent B for epoxy resin, which is a dihydrazide, preferably selected from the group consisting of aromatic dicarboxylic acid dihydrazide B1 and aliphatic dicarboxylic acid dihydrazide B2, d) At least one toughness enhancer 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. A thermosetting one-component epoxy resin composition comprising, wherein the weight ratio (A1 / A2) of the at least one liquid epoxy resin A1 to the at least one liquid epoxy resin A2 is 0.25 to 5.0, preferably 0.33 to 3.0, more preferably 0.5 to 2.0, and most preferably 0.75 to 1.

5.

2. The thermosetting one-component epoxy resin composition according to claim 1, 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), and particularly adipic acid dihydrazide.

3. The at least one liquid epoxy resin A1 is of formula (II) 【Chemistry 1】 (In the formula, substituents R''' and R'''' are each independently H or CH ３ (where the subscript r has a value between 0 and 1, preferably r has a value less than 0.2) A thermosetting one-component epoxy resin composition according to claim 1 or 2, characterized by having the following:

4. Liquid epoxy resin A2 is a bifunctional saturated, branched or unbranched, cyclic or chain-type C selected from the group consisting particularly of ethylene glycol, butanediol, hexanediol, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether, and neopentyl glycol diglycidyl ether. ２ ~C ３０ A thermosetting one-component epoxy resin composition according to any one of claims 1 to 3, characterized in that the liquid epoxy resin A2 is selected from alcohol glycidyl ethers, and most preferably, is a hexanediol glycidyl ether.

5. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 4, further comprising at least one accelerator C selected from the list consisting of substituted ureas, imidazoles, imidazolines, and block amines, particularly substituted ureas.

6. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 5, characterized in that the weight ratio ((A1 + A2) / D) of the sum of the at least one liquid epoxy resin A1 and the at least one liquid epoxy resin A2 to the at least one toughness improver D is 0.25 to 0.6, preferably 0.3 to 0.5, and more preferably 0.35 to 0.

55.

7. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 6, further comprising at least one plasticizer PL selected from a list consisting preferably of phthalate diesters, dialkyl terephthalates, aliphatic carboxylic acid diesters, polyester polymers, adipic acid polyesters, phosphate esters, trimellitic acid esters, benzoic acid and dibenzoic acid esters, phenol citrate esters and alkyl sulfonic acid esters, and preferably selected from trimellitic acid esters.

8. The thermosetting one-component epoxy resin composition according to claim 7, characterized in that the weight ratio ((A1 + A2) / PL) of the sum of the at least one liquid epoxy resin A1 and the at least one liquid epoxy resin A2 to the at least one plasticizer PL is 1 to 10, preferably 1.25 to 5, more preferably 1.5 to 3, even more preferably 1.75 to 2.5, and most preferably 1.8 to 2.

2.

9. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 8, further comprising preferably at least one filler F selected from the group consisting of calcium carbonate, calcium oxide, talc, titanium oxide, and fumed silica, wherein preferably the total ratio of the filler F is 35 to 60% by weight, preferably 45 to 55% by weight, and more preferably 47.5 to 52.5% by weight, based on the total weight of the thermosetting one-component epoxy resin composition.

10. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 9, characterized in that the ratio of the total number of epoxy groups in the liquid epoxy resins A1 and A2 in molar units to the ratio of the curing agent B in molar units ((A1 + A2) / B) is 3 to 8, preferably 4 to 7, more preferably 5 to 7, and most preferably 5.5 to 6.

5.

11. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 10, characterized in that the ratio of accelerator C in grams per mole of the total epoxy groups of the liquid epoxy resins A1 and A2 ((A1 + A2) / C) is preferably 0.01 to 0.5 g / mol of epoxy groups, particularly 0.05 to 0.3 g / mol of epoxy groups, more preferably 0.075 to 0.2 g / mol of epoxy groups, and most preferably 0.08 to 0.15 g / mol of epoxy groups.

12. The thermosetting one-component epoxy resin composition according to any one of claims 1 to 11, characterized in that the total ratio of the liquid epoxy resins A1 and A2 is 5 to 20% by weight, preferably 7.5 to 15% by weight, and more preferably 10 to 12.5% ​​by weight, based on the total weight of the one-component epoxy resin composition.

13. A thermosetting one-component epoxy resin composition according to any one of claims 1 to 12, characterized by having a viscosity of 150 to 900 Pa·s at 23°C, particularly 200 to 800 Pa·s, preferably 200 to 400 Pa·s, and more preferably 250 to 350 Pa·s.

14. Use of the thermosetting one-component epoxy resin composition according to any one of claims 1 to 13 as a sealing compound for the body of an automobile, particularly within the engine compartment, or for doors, trunk lids, tailgates, or hoods.

15. A method of sealing, i) A step of applying a thermosetting one-component epoxy resin composition according to any one of claims 1 to 13 to a substrate (S), ii) The step of heating the thermosetting one-component epoxy resin composition to a temperature above 120°C, particularly 160°C to 220°C, to form a cured thermosetting one-component epoxy resin composition. The method includes, preferably, step ii) preferably being carried out in a CDC oven.

16. The method according to claim 15, wherein in step i), the thermosetting one-component epoxy resin composition is applied to or within a gap, the gap is bounded by two surfaces of the base material (S) and the second base material (S2), and the second base material (S2) is made of the same material as or different from the base material (S).

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