MXPA01006013A - Shock-resistant epoxide resin compositions - Google Patents

Abstract

The invention relates to compositions which are based on a copolymer with at least one glass transition temperature of -30°C or lower and groups which are reactive with epoxides or a reaction product of said copolymer with a polyepoxide and a reaction product of a polyurethane prepolymer and a polyphenol or aminophenol;at least one epoxide resin and optionally, latent hardeners. Said compositions are suitable for use as structural adhesives with good shock resistance atlow temperatures. Adhesive joints formed with these compositions also have a very high shock peel resistance at low temperatures. Consequently, structural adhesive joints of this type can be used for crash resistant structures in vehicle construction.

Description

COMPOSITIONS OF EPOXY RESINS RESISTANT TO SHOCKS This invention relates to the use of mixtures of copolymers of special dienes and polyurethanes or polyureas or polyimides terminated in phenol in admixture with epoxy resins and / or the addition products of epoxy resins with copolymers of dienes and / or polyurethane or polyurea as epoxy resin adhesives with high impact strength, with particularly good properties at low temperature and reactive, hot melt adhesives, preferably of a component with good resistance to low temperature shocks. Hot melt adhesives based on epoxies, reagents, are already known. In the construction of machinery and vehicles, and especially in the construction of aircraft, railway vehicles and motorized vehicles, the components of various metals and / or composite materials are increasingly bound with the aid of adhesives. Epoxy adhesives are widely used for high-strength structural bonding, more specifically, as one-component, thermosetting adhesives which, in many cases, are also formulated as hotmelts or reactive hot melt materials. The hot melt adhesives, reagents are solid at room temperature and they soften and behave like a thermoplastic material at temperatures of up to approximately 80 to 90 ° C. It is only at relatively high temperatures of about 100 ° C and higher than the latent hardeners present in these hot melt adhesives that they are thermally activated so that irreversible cure to a thermoset occurs. To join the components together, for example, in the vehicle industry, the adhesive is first applied hot to at least one surface of the substrate, after which the parts to be joined then fit together. The adhesive then solidifies with cooling and, through this physical solidification, establishes resistance to proper handling, i.e., a temporary bond. The parts thus joined together are also treated in different washing, phosphating and immersion painting baths. Only after these is the adhesive cured at relatively high temperatures in an oven. Traditional adhesives and hot-melt adhesives based on epoxy resin are hard and brittle in the cured state. Although the bonds obtained with these are generally characterized by very high resistance to the tensile cutting, the adhesives are dehusked or descaled under adhesion efforts, Shock or shock / adhesion, in particular at relatively low temperatures, so that easily loss of adhesion force occurs when the adhesive is subjected to this kind of stress. Consequently, numerous proposals have already been made regarding the modification of epoxy resins by flexible adhesives that clearly reduce their fragility. A known process is based on the use of special rubber / epoxy resin addition products that are incorporated as a heterodisperse phase into the epoxy resin matrix so that the epoxies are more resistant to shocks. These epoxy resin compositions are also known as "hardened". Another known modification of epoxy resins of the aforementioned type consists in the reaction of a carboxyl-co-acrylonitrile-terminated polybutadiene copolymer with an epoxy resin. This rubber / epoxy addition product is then dispersed in one or more different epoxy resins. The reaction of the epoxy resin with the butadiene rubber containing carboxyl / acrylonitrile has been carried out in such a way that the addition product does not cure prematurely. Although the corrected epoxy resin compositions already represent an obvious improvement over unmodified epoxy resins in relation to their impact resistance, their low performance Adhesion or shock / adhesion effort is still not satisfactory. EP-A-0 343 676 discloses adhesive compositions consisting of a mixture of some epoxy resins, a phenolic resin and a polyurethane / epoxy addition product. The polyurethane / epoxy addition product present therein consists of a product of the reaction of various polyalkylene glycol homopolymers and copolymers containing primary and secondary OH groups, a diisocyanate and at least one epoxy resin. According to the document in question, these hot melt adhesive compositions show better shear strength, adhesion strength and impact strength in relation to different commercial one component hot melt adhesive compositions. Unfortunately, there is no reference to the adhesive properties of the adhesive gasket cured at low temperatures. US-A-5 290 857 discloses an epoxy resin adhesive composition containing an epoxy resin and a core / shell polymer in the form of a powder and a heat-activated hardener for the epoxy resin. The core / shell polymer in powder form is composed of a core containing an acrylate or methacrylate copolymer with a glass transition temperature of -30 ° C or less and a cover containing an acrylate or methacrylate polymer containing crosslinker monomer units and having a vitreous transition temperature of 70 ° C or higher, the weight ratio of the core to the shell being between 10: 1 and 1: 4. It is said that these compositions have excellent adhesive properties, such as peeling resistance, tensile shear strength and tear resistance in T, and also good partial gelling ability. No mention is made of the properties of the bonds with these adhesives at low temperatures. Similarly, US-A-5, 686,509 discloses an adhesion-enhancing composition for epoxy resins consisting of copolymer particles in powder form, ionically cross-linked with a mono- or divalent metal cation. The core of the core / shell polymer is composed of a diene monomer and optionally crosslinker monomer units and has a glass transition temperature of -30 ° C or less. The coating copolymer has a glass transition temperature of at least 70 ° C and is composed of acrylate or methacrylate monomer units and unsaturated carboxylic acid units that can be radically polymerized, the composition is said to be adhesive contains from 15 to 60 parts by weight of the copolymer-reinforcing powder of the adhesion and from 3 to 30 parts by weight of a hardening agent heat-activatable for 100 parts of the epoxy resin. These compositions are recommended for use as structural adhesives for auto parts. No mention is made of the low temperature properties of the corresponding joints. EP-A-0 308 664 discloses epoxy resin compositions containing an epoxide addition product of a carboxyl-containing copolymer based on butadiene / acrylonitrile or butadiene-like copolymers [sic] and a reaction product of an isocyanate-terminated prepolymer, Elastomeric, soluble or dispersible in epoxy resins with a polyphenol or aminophenol and the subsequent reaction of this addition product with an epoxy resin. In addition, these compositions may contain one or more epoxy resins. In addition, aminofunctional hardeners, polyaminoamides, polyphenols and polycarboxylic acids and their anhydrides or catalytic hardeners and optionally accelerators are proposed to harden these compositions. It is said that the compositions in question are suitable as adhesives that can have high strength, a glass transition temperature high, high resistance to peeling, high impact resistance or high resistance to tear propagation according to its specific composition. EP-A-0 308 664 does not indicate whether the compositions described herein are suitable for adhesives with good resistance to low temperature shocks. In the same wayEP-A-0 353 190 describes epoxy resin compositions containing an addition product of an epoxy resin and a carboxylated butadiene / acrylonitrile copolymer and a reaction product of a hydroxyl-terminated polyalkylene glycol, mercapto or amino with a Phenol carboxylic acid with the subsequent reaction of the phenolic group with an epoxy resin. According to EP-A-0 353 190, these compositions are suitable for the production of adhesives, adhesive films, patches, sealants or sealants, paints and matrix resins. There is no indication if the adhesives thus produced have good shock resistance at low temperature. According to the teaching of EP-A-0 354 498 or EP-A-0 591 307, the reactive, hot melt adhesive compositions can be produced from a resin component, at least one heat-activating latent hardener for the resin component and optionally accelerators, fillers, agents thixotropizers and other common additives, the resin component can be obtained by the reaction of a solid epoxy resin at room temperature and a liquid epoxy resin at room temperature with one or more polyoxypropylenes terminated in amino, linear or branched. It is said that the epoxy resins have to be used in such quantity, based on the amino-terminated polyoxypropylene, that an excess of the epoxy groups is guaranteed, based on the amino groups. These adhesive compositions have a high resistance to desquamation in the T-desquamation test that they retain even at low temperatures. The problem addressed by the present invention was also to improve the reactive adhesives of the type mentioned at the beginning to the extent that they have adequate flexibility and greater resistance to desquamation not only at room temperature, but also, and in particular, at low temperatures (below 0 ° C). In particular, these would exhibit high resistance to desquamation at low temperatures and low impact resistance so that, even in the event of a collision, the bonded structural parts would comply with modern safety standards in vehicle construction. These improvements would be obtained without deterioration in the resistance to desquamation at high temperatures or in the resistance to traction cutting. In addition, the reactive adhesives would have to exhibit adequate resistance to washing immediately after application and before final curing. For this purpose, the adhesive compositions would have to be presented as hot melt materials for formulation as a highly viscous adhesive suitable for hot application. Another possibility would be to formulate the compositions as an adhesive that could be gelled by a preliminary thermal reaction in a so-called "white body furnace" or by induction heating of the bonded parts. The solution provided by the invention to the problem as set forth above is defined in the clauses and consists mainly of the use of the compositions containing: A) a copolymer having at least a glass transition temperature of -30 ° C or minor and groups reactive to the epoxies, B) A reaction product of a polyurethane prepolymer and a polyphenol or aminophenol, and C) at least one epoxy resin, As structural adhesives with good resistance to low temperature shocks. A structural adhesive in this context of the invention is an adhesive having a tensile strength of 15 MPa at room temperature in steel and still guaranteeing a tensile strength in steel of more than 10 MPa at an elevated temperature of 90 ° C. Such an adhesive has good resistance to low temperature shocks when the energy for desquamation by shock at 2 m / sec according to ISO 11343 at -20 ° C is at least 5J. Components A), B) and C) can also be mixtures of compounds of the type mentioned. Preferably, the components A and B react with a large stoichiometric excess of the epoxy resins in separate reactions and then optionally are mixed with other epoxy resins, heat activatable hardeners and / or other additives. Examples of the copolymers of component A) are 1,3-diene polymers containing carboxyl groups and other comonomers with ethylenic unsaturation, polar. The diene may be butadiene, isoprene or chloroprene and is preferably butadiene. Examples of polar ethylenically unsaturated comonomers are acrylic acid methacrylic acid, lower alkyl esters of acrylic or methacrylic acid, for example, methyl or ethyl esters thereof, acrylic or methacrylic acid amides, fumaric acid, itaconic acid, maleic acid or alkyl esters lower or semi-esters of these or maleic acid or itaconic anhydride, vinyl esters such as for example vinyl acetate or, more specifically, acrylonitrile or methacrylonitrile. The most particularly preferred copolymers A) are the carboxyl-terminated butadiene / acrylonitrile copolymers (CTBN) which are commercially available in liquid form under the trademark Hycar from B. F. Goodrich. These copolymers have molecular weights of 2000 to 5000 and acrylonitrile contents of 10% to 30%. Examples of these are Hycar CTBN 1300 X 8, 1300 X 13 or 1300 X 15. The known core / shell polymers of US-A-5,290,857 and US-A-5, 686, 509 can also be used as component A). The monomers of the core must have a glass transition temperature of or below -30 ° C and may be selected from the group of the monomers dienes, as already mentioned or the suitable acrylate or methacrylate monomers. The core polymer may optionally contain units of crosslinking monomers in small amounts. The cover is made up of copolymers having a glass transition temperature of at least 60 ° C. The cover preferably consists of monomer units of lower alkyl acrylate or methacrylate (methyl or ethyl esters) and polar monomers, such as (meth) acrylonitrile), (meth) acrylamide, styrene or carboxylic acids or unsaturated carboxylic anhydrides, which can be polymerized by radicals. However, the addition products of the epoxy resins and the liquid CTBN rubbers mentioned above are particularly preferred for component A). Component B) can be represented by the following formula I: R1- [X- (C = 0) -NH-R2-NH- (C = 0) -Y-R3- (Z) m] n (I) wherein m = 1 or 2, n = 2 or 3, R1 is a residue of a polyalkylene glycol after removing the functional groups (hydroxyl or amino groups). R Cß-C alkyl? , aryl, aralkyl (residue of a diisocyanate after removing the isocyanate groups). X, Y = -O-, -S-, or -NR4-, where R4 = H or C? -C4 alkyl, or phenyl, R3 is a carbocyclic-aromatic or aliphatic m + 1 functional residue with directly attached Z groups to the aromatic ring and Z = -OH or -NHR4 (residue of a polyphenol or aminophenol after eliminating the functional groups).

Component B) is a reaction product of a di- or polyamine or di- or polyol and a diisocyanate. The stoichiometric ratio between the amino groups or the hydroxyl groups and the isocyanate groups is selected such that the isocyanate groups are present in a stoichiometric excess, preferably from 1.5 to 2, on the amino groups or the hydroxyl groups. The isocyanate-terminated polyurethane prepolymer thus formed is then reacted with an excess of polyphenol or aminophenol so that the reaction product bears the phenolic or amino terminal groups. The polyester polyols can also be mixed in this reaction mixture. The reaction mixture thus formed usually reacts directly with the other constituents of the composition, such as component A) and other epoxy resins, although it is also possible for it to react with a large stoichiometric excess of epoxy resins so that the product is formed of addition finished in epoxy. In principle, it is possible to use a large number of polyurethane prepolymers for the addition of the poly-or aminophenols, but preferably hydroxyl-terminated or amino-terminated polyalkylene glycols, more specifically, di- or trifunctional polypropylene glycols, hydroxyl-terminated, are used. or amino-terminated, polyethylene glycols or copolymers of propylene glycol and ethylene glycol, and in particular polytetramethylene glycols (poly-THF). Other suitable synthesis components for polyurethane prepolymers are polybutadienes terminated in amino or hydroxyl terminated. The polyalkylene glycols terminated by hydroxyl or amino termini and the corresponding polybutadiene derivatives have molecular weights of 400 to 5,000. In principle, the di- or polyisocyanates suitable for the production of the polyurethane prepolymers are any of the aromatic, aliphatic or cycloaliphatic polyisocyanates known in polyurethane chemistry. Examples of suitable aromatic polyisocyanates are any of the isomers of toluene diisocyanate (TDI) in pure isomeric form or in the form of a mixture of various isomers, naphthalene 1,5-diisocyanate, 4,4'-diphenylmethane diisocyanate ( MDI), 2,4'-diphenylmethane diisocyanate and mixtures of 4,4 'diisocyanate-diphenylmethane with the 2,4'-isomer or mixtures of these with oligomers of relatively high functionality (referred to as crude MDI). Examples of suitable cycloaliphatic polyisocyanates are the hydrogenation products of the above-mentioned aromatic diisocyanates, such as, for example, 4,4'-dicyclohexylmethane diisocyanate (H? 2MDI), l-isocyanatomethyl-3-isocyanato-1,5,5-trimethylcyclohexane (isophorone diisocyanate, IPDI), 1-4 cyclohexane diisocyanate, hydrogenated xylylene diisocyanate (H6XDI), m- or p-tetramethylxylylene diisocyanate (m-TMXDI, p-TMXDI) and dimeric fatty acid diisocyanate. The examples of the aliphatic polyisocyanates are 1, Hexane-6-diisocyanate (HDI), 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, butan-1,4-diisocyanate and 1, 12- dodecandiisocyanate (C? 2DI). Particularly preferred are aliphatic, cycloaliphatic or even araliphatic diisocyanates. The polyphenols or aminophenols to be used for the reaction product B) are aromatic di- or trihydroxy compounds derived from a carbocyclic-aromatic mono- or polynuclear radical or the corresponding amino-hydroxy groups. The aromatic rings can be condensed or linked together by bonding or covalent bonding. Examples of the compounds mentioned first are hydroquinone, resorcinol, pyrocatechol, isomers of dihydroxynaphthalene (pure isomers or a mixture of some isomers), isomers of dihydroxyanthracene and the corresponding aminohydroxy compounds. The polyphenols or aminophenols, which are obtained from the aromatic carbocyclic compounds of which the aromatic nuclei are linked by linking bonds, can be represented by the following general formula II: Z AR B AR Z: n) in which Z is as defined. AR is a mononuclear aromatic radical which can optionally also be substituted by alkyl or alkenyl radicals. B represents the binding link that can be selected from the group consisting of a covalent bond, -CR5R6-, -O-, '-S-, -S02-, -CO-, -COO-, -CONR7- and SiR8R9- where R5, R6 and R7, independent of each other, represent hydrogen, -CF3 or C? -C6 alkyl or R5 and R6 together with the common C atom form a cycloaliphatic radical with 5 to 7 carbon atoms in the ring, R8 and R9 represent C? -C6 alkyl. The two groups B and Z in formula II independent of each other can be located in the ortho, meta or para position. Particularly preferred compounds corresponding to formula II are 4,4'- dihydroxydiphenyl or the bisphenols A and / or F. The polyester polyols optionally present in component B) are the polyester polyols known per se which are used in polyurethane chemistry, for example for the production of hot melt adhesives. Examples of these polyester polyols are the products of the reaction of dicarboxylic acids such as glutaric acid, adipic acid, sebacic acid, suberic acid, 3, 3-dimethylglutaric acid, terephthalic acid, isophthalic acid, dimeric fatty acid, with dihydric alcohols of low molecular weight such as, for example, ethylene glycol, propylene glycol, butan-1,4-diol, diethylene glycol, triethylene glycol or dimeric fatty alcohol. Convenient polyester polyols may optionally be slightly branched, that is, small amounts of a tricarboxylic acid or trihydric alcohol were used for their production. The epoxy resins suitable for component C) or for forming the epoxide addition product or for mixing components A) and B) are any of the different polyepoxides that contain at least two 1,2-epoxy groups per molecule. The epoxy equivalent of these polyepoxides can be between 150 and 4,000. Basically, polyepoxides can be polyepoxide saturated, unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic compounds. Examples of suitable polyepoxides include the polyglycidyl ethers which are obtained by the reaction of epichlorohydrin or epibrorno idrin with a polyphenol in the presence of alkali. Suitable polyphenols for this purpose are, for example, resorcinoi, piocatechol, hydroquinone, bisphenol A (bis- (4-hydroxyphenyl) -2, 2-propane), bisphenol F (bis (4-hydroxyphenyl) methane), (4-hydroxyphenyl) -1,1-isobutane, 4,4'-dihydroxybenzophenone, bis- (4-hydroxyphenyl) -1, 1-ethane, 1,5-hydroxynaphthalene. Other polyepoxides suitable in principle are the polyglycidyl ethers of the polyalcohols or diamines. These polyglycidyl ethers are obtained from polyalcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, triethylene glycol, pentan-1,5-diol, hexan-1,6-diol. or trimethylolpropane. Other polyepoxides are the polyglycidyl esters of polycarboxylic acids, for example, the products of the reaction of glycidol or epichlorohydrin with aliphatic or aromatic polycarboxylic acids such as oxalic acid, succinic acid, glutaric acid, terephthalic acid or dimeric fatty acid.

Other epoxides are obtained from the epoxidation products of the cycloaliphatic compounds with olefinic unsaturation or natural oils and fats. Epoxy resins obtained by reaction of bisphenol A or bisphenol F and epichlorohydrin are more particularly preferred. Mixtures of liquid and solid epoxy resins are generally used, the liquid epoxy resins being preferably based on bisphenol A and having a sufficiently low molecular weight. Liquid epoxy resins at room temperature which usually have an epoxy equivalent weight of 150 to about 220 and, more specifically, in the range of 182 to 192 are particularly preferred for the formation of the addition product of components A) and B). The hardness of the reactive adhesive in the cooled state, ie, in particular after application to the substrate to be bound, but before curing, depends on the degree of condensation and therefore on the molecular weight of component B) in particular, and of the ratio of the solid epoxy resin to the liquid epoxy resin. The greater the degree of condensation (and therefore the molecular weight) of the addition product B) and the greater the proportion of the solid epoxy resin in the composition, the cooled semicrystalline adhesive will be harder. Suitable thermo-activatable or latent hardeners for the binder system of the epoxy resin of components A), B) and C) are guanidines, substituted guanidines, substituted ureas, melamine resins, guanamine derivatives, cyclic tertiary amines, aromatic amines and / or mixtures thereof. Hardeners may be included in stoichiometric amounts in the curing reaction although these may also be catalytically active. Examples of the substituted guanidines are methylguanidine, dimethylguanidine, trimethylguanidine, tetramethylguanidine, methyl isobiguanidine, dimethyl isobiguanidine, tetramethyl isobiguanidine, hexamethylisobiguanidine, heptamethyl isobiguanidine and, more specifically, cyanoguanidine (diacyanodiamide). Alkylated benzoguanamine resins, benzoguanamine or methoxymethyletoxymethyl benzoguanamine resins are mentioned as being representative of the suitable guanamine derivatives. The selection criteria for one-component, heat-cured hot melt adhesives is of course its low solubility at room temperature in the resin system so that finely ground solid hardeners are preferred, being particularly convenient dicyanodiamide. In this way, a prolonged storage life for the composition is guaranteed. The substituted, catalytically active ureas can be used in addition to, or in place of, the aforementioned hardeners. These substituted ureas are, in particular, p-chlorophenyl-N, N-dimethyl urea (Monuron), 3-phenyl-1, 1-dimethyl urea (Fenuron) or 3,4-dichlorophenyl-N, N-dimethyl urea (Diuron). ). In principle, it is possible to use the catalytically active tertiary alkyl aryl amines, for example benzyldimethylamine, tris (dimethylamino) phenol, piperidine or piperidine derivatives, but they tend to have too high solubility in the adhesive system so that the one component system it is not guaranteed with a life in useful storage in this case. In addition, it is possible to use some imidazole derivatives, preferably solids, as catalytically active accelerators. 2-Ethyl-2-methyl imidazole, N-butyl imidazole, benzimidazole and N-alkyl of C? -C? 2-imidazoles or N-arylimidazoles are mentioned as being representative of these accelerators.

In addition, the adhesives according to the invention contain fillers known per se as the different crushed or precipitated calcium carbonates, carbon black, calcium-magnesium carbonates, dense feldspar and, in particular, silicate fillers. of the aluminum-magnesium-calcium silicate type, for example, ollastonite, chlorite. The adhesive compositions according to the invention can also contain other common auxiliaries and additives such as, for example, plasticizers, reactive diluents, rheology aids, wetting agents, anti-aging agents, stabilizers and / or pigments. The adhesives according to the invention can be formulated on the one hand as one-component adhesives which in turn can be formulated as highly viscous adhesives designed for hot application and as heat-activatable hot melt adhesives. These adhesives can also be formulated as pre-flammable one-component adhesives, in which case, the compositions contain thermoplastic powders of fine particles such as polymethacrylates, polyvinylbutyral or other thermoplastic (co) polymers or the curing system is adapted in such a way that it occurs a two-step curing process, the gelling step by only partially curing the adhesive and the final curing in the construction of the vehicle taking place, for example, in one of the paint furnaces, preferably the cathodic electrodeposition furnace. The adhesive compositions according to invention can also be formulated as two-component epoxy adhesives where the two components of the reaction are mixed just before application, curing then taking place at room temperature and at moderately elevated temperature. The second component of the reaction can be selected from the reaction components known per se for the two-component epoxy adhesives, for example, di or polyamines, amino-terminated polyalkylene glycols (for example Jeffamine, amino-poly-THF) or polyaminoamides . Other reactants can be mercapto functional prepolymers such as liquid Thiokol polymers. Basically, the epoxy compositions according to the invention can also be cured with carboxylic anhydrides as the second reaction component in the two-component adhesive formulations. In addition to the applications mentioned at the beginning, the adhesive compositions according to the invention can also be used as encapsulation compounds in the electrical or electronic industries and as die-bonding adhesives in electronics for joining components to circuit boards. Other possible applications for the compositions according to the invention are as matrix materials for composite materials such as fiber reinforced composites. However, a more particularly preferred application for the adhesives according to the invention is in the structural adhesion in the construction of vehicles. The ratios in quantity between the individual components may vary within relatively wide limits, depending on the requirements the adhesive is expected to meet with respect to its application properties, flexibility, resistance to flaking by shock or tensile strength. The common ranges for the key components are: • Component A): 5-25% by weight, preferably 6-20% by weight. • Component B): 5-30% by weight, preferably 5-20% by weight. • Component C): 10-60% by weight, preferably 15-50% by weight; this component may be composed of one or more liquid and / or solid epoxy resins, in which case it may optionally contain low molecular weight epoxides as reactive diluents.

• Filling materials: 10-40% by weight. • Hardener component (for thermosetting one-component systems): 1-10% by weight, of 3-8% by weight preference. • Accelerator: 0.01-3% by weight, preferably 0.1 to 0.8% by weight. • Auxiliary rheology (thixotropizing agent): 0.5-5% by weight. As mentioned at the beginning, the requirements of the modern structural adhesives that are expected to be met in the construction of vehicles continue to increase because more and more structural elements, including those with load carrying functions, are being joined by adhesion processes . As already mentioned in the article by G. Ldtting and S. Singh entitled: "Anforderungen and Klebstoffe für Strukturverbindungen im Karossßriebau" Accession 1988, No. 9, pages 19 to 26, on the one hand, the adhesives are expected to comply with the following aspects: of production of practical importance, including automated application in short cycle times, adhesion to metallic boards covered with oil, adhesion to different types of metal boards and compatibility with the process conditions in the paint line (resistance to washing and phosphating baths, the curing capacity during baking of the CED primer, resistance to the following painting and drying operations). In addition, modern structural adhesives they have to have better resistance and deformation properties, even in the cured state. These include the high resistance to corrosion and resistance to bending of structural components and the deformability of the joint under mechanical stress. The high deformability of the structural components guarantees a considerable safety advantage in the event of a collision. This behavior in the collision can best be determined by considering the impact energy for the cured joints; High enough values for shock energy or shock / desquamation energy are desirable at high temperatures of up to 90 ° C and, in particular, at low temperatures below -40 ° C. High tensile strength must also be achieved. Both resistances must be achieved in a large number of substrates, mainly metallic boards covered with oil, for example, steel body panels, galvanized steel plates by different methods, boards of different aluminum alloys and even magnesium alloys and plates. Steel covered by serpentine or bovine coating with organic coatings of the "Bonazinc" or "Granocoat" type. As shown in the following examples, the adhesive compositions according to the invention comply surprising these requirements to a very high degree. The following examples are proposed to illustrate the invention. All amounts related to the compositions are parts by weight, unless otherwise indicated.

General procedure for producing component A) A carboxyl-terminated poly (butadiene-co-acrylonitrile) (Hycar CTBN 1300 X 13) was reacted for 3 hours with agitation under nitrogen at 140 ° C with an approximately 10 molar excess of a resin DGEBA epoxy liquid until the reaction was constant.

General procedure for the preparation of the reaction product B) Approximately 1.85 equivalents of the diisocyanate were introduced with nitrogen at 120 ° C in a tank reactor with stirring, with heating, after which one equivalent of the polyol was added dropwise at 120 °. C and the reaction was continued for 3 hours at 120 ° C. The isocyanate-terminated polyurethane prepolymer then formed reacted with a stoichiometric excess of the polyphenol, the polyphenol being rapidly added to the reaction mixture. The reaction was continued for another hour at 120 ° C, after which a liquid polyester polyol to the reaction mixture. The obtained mixture was used for the production of the adhesive.

Overall production of the adhesive In a kneader, components A), B) and a liquid epoxy resin and a solid epoxy resin were mixed until homogeneous at room temperature or, as an option, at 80 ° C in the presence of the fillers, hardeners, accelerators and rheology auxiliaries, and the resulting mixture was poured into storage containers optionally while still hot.

Example 1 Component B) was prepared from 66.3 parts by weight of poly-THF-2000 (a product of BASF), 10.3 parts by weight of hexamethylene diisocyanate, 8.4 parts by weight of resorcinium and 15.0 parts by weight of Dynacol 7250 (a product of Hüls) by the general procedure for preparing the reaction product B). Component A) was prepared from Hycar CTBN 1300 X 13 and a liquid DGEBA resin by the method described above. The resulting composition contained 40% butyl rubber and had an epoxy equivalent weight of 900 and a viscosity at 80 ° C of 200 Pa-s, Examples 2-3 The adhesive compositions according to the invention were prepared from components B) of Example 1, component A) and a liquid DGEBA resin (epoxy equivalent weight 189), fillers, dicyanodiamide as a hardener and accelerators and hydrophobic silica as a thixotropizing agent and optionally the powder of the thermoplastic polymer. The compositions are as set forth in Table 1.

Table 2. [sic] Adhesives according to the invention Loading material ollastonite Silica: Carbosil TS 720 (Cabot) The adhesive properties of the examples according to the invention and the adhesive properties of the known adhesives are compared in Table 2. The adhesive of Comparative Example 1 was Betamate 1044/3 from Gurit Essex. It is assumed that this adhesive had been produced in accordance with the teaching of EP-A-0 308 664.

Table 2. Adhesive properties Shock: peel desquamation test according to ISO 11343 at 2 m / sec. RT: room temperature. TSS: tensile cut resistance according to DIN 53283 in steel 1403 of 1.5 mm thickness. SST: salt spray test according to DIN 50021 the 100% cohesive fracture pattern unless otherwise indicated.

As these test results show, the energy of flaking by shock for ISO 11343 of the adhesives according to the invention is several times greater than that of the known adhesives. At very low temperatures in particular, the impact desquamation energy of the adhesives according to the invention is clearly better than that of the known adhesives without deterioration in tensile strength or aging behavior in the salt spray test. .

Claims (14)

1. CLAIMS 1. The use of compositions containing: A) a copolymer having at least a vitreous transition temperature of -30 ° C or less and epoxy reactive groups or a reaction product of this copolymer with a polyepoxide, and B) a product of reaction of a polyurethane prepolymer and a polyphenol or aminophenol, and C) at least one epoxy resin as structural adhesives with good shock resistance at low temperature.
2. 2. The use of the compositions claimed in claim 1, characterized in that component A) is a copolymer based on butadiene.
3. 3. The use of the compositions claimed in claim 2, characterized in that the copolymer of component A) is a carboxyl-containing copolymer based on butadiene / acrylonitrile, butadiene / (meth) acrylates, a butadiene / acrylonitrile / styrene copolymer or a butadiene / (meth) acrylate / styrene copolymer.
4. 4. The use of the composition claimed in claim 1, characterized in that the copolymer of A) is a core / shell polymer in which the core polymer is a diene polymer or a polymer of (meth) acrylate with a glass transition temperature of -30 ° C or less and which can optionally be crosslinked with 0.01 to 5% by weight of a diolefin comonomer and of which the shell polymer has a glass transition temperature of 60 ° C or higher and can be obtained from monomers of the group consisting of (meth) alkyl acrylate, (meth) acrylonitrile, (methyl) styrene and carboxylic acids or carboxylic anhydrides with olefinic unsaturations or mixtures thereof. The use of the compositions claimed in at least one of the preceding claims, characterized in that an addition product of an epoxy resin and a copolymer according to claims 2 to 4 is used as component A). 6. The use of the compositions claimed in at least one of the preceding claims, characterized in that component B) is a compound corresponding to formula I: Rx- [X- (C = 0) -NH-R2-NH- (C = 0) -Y-R3- (Z) m] n (I) in which m = 1 or 2, n = 2 or 3, R1 is a residue of a polyalkylene glycol after removing the functional groups (groups hydroxyl or Not me) . R2 = C 1 -C 4 alkyl, aryl, aralkyl (residue of a diisocyanate after removing the isocyanate groups). X, Y = -0-, -S-, or -NR4-, where R4 = H or C? -C alkyl, or phenyl, R3 is a carbocyclic-aromatic or aliphatic m + 1 functional residue with directly attached Z groups to the aromatic ring and Z = -OH or -NHR4 (residue of a polyphenol or aminophenol after eliminating the functional groups). The use of the composition claimed in claims 1 to 6, characterized in that the component B) according to claim 6 is dissolved in a liquid polyepoxide. 8. The use of the composition claimed in claims 1 to 5, characterized in that the component B) according to claim 6, reacts with a stoichiometric excess of a polyepoxide. 9. The use of the composition claimed in at least one of the preceding claims, characterized in that, in addition to the components A), B) and C), it contains: D) a latent hardener of the group consisting of dicyanodiamide, guanamines, guanidines, aminoguanidines, solid aromatic diamines and / or an accelerating hardener, and E) optionally plasticizers, reactive diluents, rheology aids, fillers, wetting and / or anti-aging agents and / or stabilizers. The use of the claimed compositions in at least one of the preceding claims as a structural adhesive with high strength and high impact resistance, with a peeling desquamation energy of at least 5 J at -20 ° C (according to ISO 11343 ) in the construction of vehicles, construction of aircraft or construction of vehicles for railways. 11. The use of the compositions claimed in claim 10 for the production of composite materials, as compounds for encapsulation in the electrical and electronic industry and as a die-bonded adhesive in the production of circuit boards in the electronics industry. 12. A composition for use as an adhesive, characterized in that, in addition to the components A), B) and C) according to any of the preceding claims, it contains: D) a latent hardener of the group consisting of dicyanodiamide, guanamines , guanidines, aminoguanidines, solid aromatic diamines and / or an accelerator hardener, E) optionally plasticizers, reactive diluents, rheology aids, fillers, wetting and / or anti-aging agents and / or stabilizers F) a polyester polyol with a molecular weight of 400 to 5,000, and G) optionally a powder of thermoplastic polymer. 13. A process for hardening components A), B), C), D), E), optionally F) and optionally G) according to claim 12 by heating the composition at temperatures of 80 ° C to 210 ° C and preferably at temperatures of 120 ° C to 180 ° C. 14. A process for bonding metallic materials and / or composites consisting of the following key process steps: • applying the adhesive composition claimed in clause 12 to at least one of the substrate surfaces to be joined, optionally after a cleaning and / or surface treatment • adjust the parts to be joined together • optionally pre-gel the adhesive composition, and • cure the joint by heating the parts at temperatures of 80 ° C to 210 ° C and, preferably, at temperatures of 120 ° C to 180 ° C.