Mercapto-functional adduct of an isocyanate-group-containing polymer with low monomer content

Abstract

The invention relates to a mercapto-functional adduct from the reaction of at least one polymercaptan with at least one isocyanate-group-containing polymer having an average molecular weight Mn of at least 1000 g / mol in a ratio of the number of mercapto groups to the number of isocyanate groups at the start of the reaction of at least 2.5, wherein the isocyanate-group-containing polymer has a content of monomeric diisocyanates of less than 0.5% by weight. The adduct makes it possible to produce epoxy resin adhesives with good workability, rapid curing, good adhesion properties and a surprising combination of high strength, high extensibility and high impact resistance.

Description

[0001] MERCAPTO-FUNCTIONAL ADDUCT OF LOW MONOMER-CONTAINING ISOCYANAT GROUP POLYMER Technical Field The invention relates to mercapto-functional adducts resulting from the reaction of polymer mercaptans with isocyanate-containing polymers and their use in curable compositions, particularly in adhesives, sealants, and coatings. Prior Art Polymercaptans are known as hardeners in curable compositions, especially in room-temperature curable epoxy adhesives, where they enable particularly rapid curing. Epoxy adhesives offer high bond strengths on various substrates. However, they are typically not very elongable and have low impact strength. For applications requiring high impact strength of the bond or where strong vibrations and movements occur, conventional epoxy adhesives are often too brittle.For such applications, so-called impact-modified (toughened) epoxy resin products have been developed, for example, for bonding in a vehicle body requiring high crash resistance. The cured adhesive contains finely dispersed, flexible polymers bound to the epoxy resin matrix as an impact modifier or toughener. These polymers absorb mechanical energy during a crash and can thus significantly reduce crack propagation in the adhesive. Functionalized liquid rubber, such as ATBN (amine-terminated butadiene-acrylonitrile copolymer) or ETBN (epoxy-terminated butadiene-acrylonitrile copolymer), is known as a toughener, but these are highly viscous and expensive and have disadvantages regarding low-temperature flexibility. US2021 / 0198537 describes metals bonded using a toughened epoxy resin adhesive.Polyurethanes, particularly isocyanate-containing polymers, which are blocked with an epoxy resin or with cardanol, have been described as impact tougheners. Such adhesives exhibit high cold flexibility. However, the epoxy-blocked tougheners are very viscous, and in the case of cardanol-blocked tougheners, cardanol is released during curing, which can have an undesirable softening effect in the cured adhesive and migrate out of the adhesive. US 7,847,034 describes the reaction of a dimercaptan with isocyanate-containing polymers and its use in epoxy resin adhesives. The object of the present invention is to provide a hardener that can be used as an impact toughener for epoxy resin adhesives and that overcomes the disadvantages of the prior art with regard to high viscosity and released releasers.Surprisingly, this problem is solved with a mercapto-functional adduct as described in claim 1. The adduct is obtained from the reaction of at least one polymercaptan with an isocyanate-containing polymer with a low content of monomeric diisocyanates. The adduct according to the invention can be produced in a simple process from readily available, inexpensive raw materials. It is stable in storage and, in particular, liquid and low-viscosity at room temperature. It is therefore particularly easy to use as a hardener and / or impact modifier for epoxy resin compositions, as well as a hardener for compositions with other reactive groups that are reactive towards mercapto groups, such as, in particular, isocyanate groups, acrylate groups, or aromatic aldehyde groups. The adduct according to the invention contains a particularly low content of reaction products of polymercaptan and monomeric diisocyanate.It is particularly suitable as a component of a hardener for epoxy resins, where it enables good processability, rapid curing, and a surprising combination of high strength and high elongation. This makes the adduct according to the invention particularly advantageous as an impact modifier for epoxy resin adhesives. Compared to a corresponding adduct starting from an isocyanate-containing polymer with a high content of monomeric diisocyanates, the adduct according to the invention surprisingly enables higher strength and / or higher elongation when used as a hardener for epoxy resin compositions. Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of the dependent claims.Ways to Implement the Invention The invention relates to a mercapto-functional adduct formed by the reaction of at least one polymercaptan with at least one isocyanate-containing polymer having an average molecular weight Mn of at least 1,000 g / mol, in a ratio of the number of mercapto groups to the number of isocyanate groups at the beginning of the reaction of at least 2.5, preferably at least 3, wherein the isocyanate-containing polymer has a content of monomeric diisocyanates of the formula based on the isocyanate-containing polymer of less than 0.5 wt%, preferably less than 0.2 wt%, and particularly less than 0.1 wt%, and D represents a divalent organic residue with 4 to 15 carbon atoms. Substance names beginning with "Poly" such as polymercaptan, polyisocyanate, polyepoxide, or polyamine denote substances that formally contain two or more of the functional groups appearing in their name per molecule.The term "molecular weight" refers to the molar mass (in grams per mole) of a molecule. The term "mean molecular weight" refers to the number-average molecular weight (Mn) of a polydisperse mixture of oligomeric or polymeric molecules. It is determined by gel permeation chromatography (GPC) against polystyrene as a standard. The term "NCO content" refers to the content of isocyanate groups in weight percent. The term "mercapto equivalent weight" refers to the mass of a compound or composition containing mercapto groups that contains one mole equivalent of mercapto groups. It is expressed in the unit "g / eq".An adduct or composition is described as "storage-stable" if it can be stored at room temperature in a suitable container for an extended period, typically at least 3 months up to 6 months or more, without its application or performance characteristics being altered by storage to an extent relevant to its use. A "primary amine group" is defined as an amine group bonded to a single organic residue and bearing two hydrogen atoms; a "secondary amine group" is defined as an amine group bonded to two organic residues, which may also be part of a ring, and bearing one hydrogen atom; and a "tertiary amine group" is defined as an amine group bonded to three organic residues, which may also be part of one or more rings in pairs or groups of three, and bearing no hydrogen atom.The hydrogen atoms of primary and secondary amine groups are referred to as "hydrogen amine." "Hydrogen amine equivalent weight" is the mass of an amine or amine-containing composition containing one mole equivalent of hydrogen amine. It is expressed in the unit "g / eq." "Epoxide equivalent weight" is the mass of an epoxy compound or composition containing one mole equivalent of epoxy groups. It is expressed in the unit "g / eq." "Room temperature" refers to a temperature of 23 °C. All industry standards and norms mentioned in this document refer to the versions valid at the date of initial filing. Weight percent (wt%) denotes the mass fraction of a component of a composition or molecule, relative to the entire composition or molecule, unless otherwise specified.The terms "mass" and "weight" are used synonymously in this document. The monomeric diisocyanate content is preferably determined by HPLC chromatography after prior derivatization with N-propyl-4-nitrobencylamine using 0.04 M sodium acetate / acetonitrile as the mobile phase and detection by photodiode array. The total reaction product from the reaction of the polymer captan with the isocyanate-containing polymer is referred to in this document as the mercapto-functional adduct. It typically contains a mixture of mercapto-functional polymer and unreacted polymer captan. The mercapto-functional adduct according to the invention is, in particular, free of isocyanate groups. The mercapto-functional adduct according to the invention is storage-stable.In the case of a polymercaptan with two mercapto groups and a linear isocyanate group-containing polymer, the adduct according to the invention contains, in addition to unreacted polymercaptan, mainly the following adduct molecules of formula (Ia) and (IIa), (Ia) OOOO (IIa) H. S E SN G N SE S N G NS E SHHHHH where G represents the remainder of the isocyanate-containing polymer after removal of two isocyanate groups and E represents the remainder of the polymercaptan after removal of the two mercapto groups. In the case of a polymercaptan with three mercapto groups and a linear isocyanate-containing polymer, the adduct according to the invention contains, in addition to unreacted polymercaptan, mainly the following adduct molecules of formula (Ib) and (IIb), (Ib) (IIb) where G represents the remainder of the isocyanate-containing polymer after removal of two isocyanate groups and E represents the remainder of the polymercaptan after removal of the three mercapto groups. An adduct molecule of formula (Ia) or (Ib) is also referred to as a "monoadduct". It contains only one G residue. An adduct molecule of formula (IIa) or (IIb) is also referred to as a "diadduct". It contains two G residues. In addition, the adduct also contains more highly adducted components,in which more than two residues G are adducted via the polymercaptan. A high ratio of the number of mercapto groups to the number of isocyanate groups corresponds to a high excess of polymercaptan and favors a high content of monoadduct and a comparatively high content of unreacted polymercaptan. A lower ratio of the number of mercapto groups to the number of isocyanate groups corresponds to a lower excess of polymercaptan and favors a higher content of more highly adducted components and a lower content of unreacted polymercaptan. Preferably, the ratio of the number of mercapto groups to the number of isocyanate groups at the beginning of the reaction is in the range of 2.5 to 20, more preferably 3 to 15, and more preferably 3.5 to 10.In particular, 4 to 8. Such an adduct is easily handled at ambient temperatures and is particularly suitable for the described uses. In the case of a polymercaptan with two mercapto groups, the ratio is preferably 3 to 10, in particular 4 to 6. This corresponds to a ratio of the number of dimercaptan molecules to the number of isocyanate groups of 1.5 to 5, in particular 2 to 3. In the case of a polymercaptan with three mercapto groups, the ratio is preferably 4 to 15, in particular 6 to 9. This corresponds to a ratio of the number of trimercaptan molecules to the number of isocyanate groups of 1.5 to 5, in particular 2 to 3. Preferably, the polymercaptan has two, three, or four, in particular two or three, mercapto groups. Most preferably, the polymercaptan has three mercapto groups. Preferably, the polymer captan has a mercapto equivalent weight of 45 to 400 g / eq, in particular 90 to 300 g / eq,preferably the polymercaptan is free of hydroxyl groups. Preferably, the polymercaptan is selected from the list consisting of 1,8-dimercapto-3,6-dioxaoctane, 1,2-ethanediol di(2-mercaptoacetate), 1,2-ethanediol di(3-mercaptopropionate), 1,2-ethanediol di(3-mercaptobutyrate), 1,4-butanediol di(2-mercaptoacetate), 1,4-butanediol di(3-mercaptopropionate), 1,4-butanediol di(3-mercaptobutyrate), glycerol di(2-mercaptoacetate), glycerol di(3-mercaptopropionate), glycerol di(3-mercaptobutyrate), glycerol tris(2-mercaptoacetate), glycerol tris(3-mercaptopropionate), and glycerol tris(3-mercaptobutyrate). 1,1,1-Trimethylolpropane-di(2-mercaptoacetate), 1,1,1-Trimethylolpropane-di(3-mercaptopropionate), 1,1,1-Trimethylolpropane-di(3-mercaptobutyrate), 1,1,1-Trimethylolpropane-tris(2-mercapto-acetate), 1,1,1-trimethylolpropane tris(3-mercaptopropionate), 1,1,1-trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tris(2-mercaptoacetate), pentaerythritol tris(3-mercaptopropionate),Pentaerythritol tris(3-mercaptobutyrate), Pentaerythritol tetrakis(2-mercaptoacetate), Pentaerythritol tetrakis(3-mercaptopropionate), Pentaerythritol tetrakis(3-mercaptobutyrate), 3-mercapto-2-hydroxypropyl ether of propoxylated pentaerythritol with a mean mercapto equivalent weight of 180 to 400 g / eq, preferably 180 to 300 g / eq, tris(2-(2-mercaptoacetyloxy)ethyl)isocyanurate, tris(2-(3-mercaptopropionyloxy)ethyl)isocyanurate and tris(2-(3-mercaptobutanoyloxy)ethyl)isocyanurate. Preferred compounds include 1,2-ethanediol di(2-mercaptoacetate), 1,2-ethanediol di(3-mercaptopropionate), 1,2-ethanediol di(3-mercaptobutyrate), 1,4-butanediol di(3-mercaptopropionate), glycerol di(3-mercaptopropionate), glycerol tris(3-mercaptopropionate), 1,1,1-trimethylolpropane tris(2-mercaptoacetate), 1,1,1-trimethylolpropane tris(3-mercaptopropionate), or 1,1,1-trimethylolpropane tris(3-mercaptobutyrate). In one embodiment of the invention, a polymer captan with two mercapto groups is preferred.such as, in particular, 1,2-ethanediol di(2-mercaptoacetate), 1,2-ethanediol di(3-mercaptopropionate), 1,2-ethanediol di(3-mercaptobutyrate), 1,4-butanediol di(3-mercaptopropionate), or glycerol di(3-mercaptopropionate). Such an adduct is particularly low-viscosity and allows for particularly high ductility. The polymer captan is particularly preferably a trimercaptan, such as, in particular, glycerol tris(3-mercaptopropionate), 1,1,1-trimethylolpropane tris(2-mercaptoacetate), 1,1,1-trimethylolpropane tris(3-mercaptopropionate), or 1,1,1-trimethylolpropane tris(3-mercaptobutyrate). Such an adduct enables particularly high strength and impact resistance. The isocyanate-containing polymer has a mean molecular weight Mn of at least 1,000 g / mol. A mean molecular weight M is preferred. nfrom 1,000 to 20,000 g / mol, in particular 1,000 to 10,000 g / mol, wherein the mean molecular weight Mn is determined, in particular by gel permeation chromatography (GPC) against polystyrene as a standard. The isocyanate-containing polymer has a content of monomeric diisocyanates of the formula of less than 0.5 wt%, preferably less than 0.2 wt%, in particular less than 0.1 wt%, where D represents a divalent organic residue with 4 to 15 carbon atoms. The preferred monomeric diisocyanate is selected from the list consisting of 1,6-hexane diisocyanate (HDI), 2,2(4),4-trimethyl-1,6-hexane diisocyanate (TMDI), 1-methyl-2,4(6)-diisocyanatocyclohexane, isophorone diisocyanate (IPDI), 4,4'-diisocyanatodicyclohexylmethane, 4(2),4'-diphenylmethane diisocyanate (MDI), and 2,4(6)-toluene diisocyanate (TDI). HDI, IPDI, or MDI are preferred, and IPDI is particularly preferred.Such an adduct is particularly low-viscosity and enables particularly high ductility combined with high strength. MDI is especially preferred. The isocyanate-containing polymer preferably has an NCO content of 1 to 9 wt%, more preferably 1.5 to 6.5 wt%. The NCO content is determined, in particular, by reacting the isocyanate groups with an excess of dibutylamine and back-titration of the unreacted dibutylamine with aqueous hydrochloric acid. The isocyanate-containing polymer preferably has an average isocyanate functionality of 1.5 to 4, more preferably 1.7 to 3, more preferably 1.8 to 2.5, and most preferably 1.9 to 2.0. The isocyanate-containing polymer preferably contains a polyether, polyester, or hydrocarbon backbone, more preferably a polyether or hydrocarbon backbone, and most preferably a polyether backbone.Preferably, the polyether backbone should be poly(oxy-1,4-butylene), poly(oxy-1,3-propylene), or poly(oxy-1,2-propylene), wherein a poly(oxy-1,2-propylene) backbone may additionally contain oxy-1,2-ethylene units, particularly at the chain ends. The isocyanate-containing polymer is preferably liquid at room temperature, particularly with a viscosity at 20 °C of 0.2 to 100 Pa. . s, preferably 0.5 to 75 Pa . s, especially 1 to 50 Pa . s, measured using a cone-plate viscometer with a cone diameter of 10 mm, a cone angle of 1°, a cone tip-plate distance of 0.05 mm and a shear rate of 10 s -1Preferably, the isocyanate-containing polymer is a reaction product of at least one monomeric diisocyanate of the formula with at least one polymeric polyol in a molar NCO / OH ratio of at least 3:1 to 10:1, preferably between 4:1 and 8:1, and subsequent removal of the monomeric diisocyanate by a suitable separation process to a content of less than 0.5 wt%, preferably less than 0.2 wt%, and particularly less than 0.1 wt%, based on the isocyanate-containing polymer. The reaction is preferably carried out in the absence of moisture at 20 to 160 °C, particularly 40 to 140 °C, optionally in the presence of a suitable catalyst. Preferably, the monomeric diisocyanate is removed from the resulting polymer by thin-film distillation or short-path distillation under vacuum. The isocyanate-containing polymer has a particularly narrow molecular weight distribution and a particularly low viscosity.It enables the production of adducts according to the invention with a particularly low content of reaction products from monomeric diisocyanate and polymercaptan. Preferably used as polymeric polyols for the production of the isocyanate-containing polymer are polyether polyols, in particular polyoxyalkylene diols or polyoxyalkylene triols, especially polymerization products of 1,2-propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, oxetane or tetrahydrofuran, optionally with the co-use of ethylene oxide, wherein these are optionally polymerized by means of a starter molecule with two or more active hydrogen atoms. Preferred polyether polyols are poly(oxy-1,4-butylene)diols, also called polytetrahydrofurans, poly(oxy-1,3-propylene)diols, poly(oxy-1,2-propylene)diols, poly(oxy-1,2-propylene)triols or ethylene oxide-terminated (EO-endcapped) poly(oxy-1,2-propylene)diols or triols.The latter are obtained by further alkoxylating poly(oxy-1,2-propylene)diols or triols with ethylene oxide after completion of the polypropoxylation reaction, thereby ultimately exhibiting primary hydroxyl groups. They contain, in particular, up to 25 wt% oxy-1,2-ethylene units based on the total polyol. Preferred polyether polyols have a degree of unsaturation of less than 0.02 mEq / g, particularly less than 0.01 mEq / g. – Polyester polyols from the polycondensation of dicarboxylic acids with di- or trihydric alcohols, in particular adipic acid, sebacic acid, dodecanedicacarboxylic acid or a dimer fatty acid, with di- and / or triols such as in particular 1,6-hexanediol, neopentyl glycol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, trimethylolpropane, glycerol or castor oil.– Polyhydroxy functional fats or oils, especially natural fats or oils, such as castor oil, derivatives of castor oil or vegetable oil-based polyols, such as those sold under the trade name Sovermol. ®(from BASF). – Polyether polyester polyols. – Polyhydrocarbon polyols, such as, in particular, polybutadiene polyols or hydrogenated polybutadiene polyols. Preferably, polymeric polyols are liquid at room temperature. Preferably, the polymeric polyol has an OH number of 12 to 175 mg KOH / g, preferably 18 to 120 mg KOH / g, and particularly 25 to 60 mg KOH / g. Preferably, the polymeric polyol is selected from the list consisting of polyether polyols, polyester polyols, and hydrocarbon polyols. Polyether polyols or polyhydrocarbon polyols, especially polyether polyols, are preferred. Particularly preferred are poly(oxy-1,4-butylene)diols, poly(oxy-1,3-propylene)diols, poly(oxy-1,2-propylene)diols, poly(oxy-1,2-propylene)triols, or ethylene oxide-terminated poly(oxy-1,2-propylene)diols or triols.The reaction of the polymer captan with the isocyanate-containing polymer to form the adduct according to the invention is preferably carried out at a temperature of 10 to 100 °C, particularly 15 to 80 °C, preferably in the presence of a basic catalyst, such as triethylamine. Preferably, the polymer captan is initially supplied, and the isocyanate-containing polymer is slowly added with thorough stirring. Alternatively, the polymer captan and the isocyanate-containing polymer can be mixed, followed by the addition of a basic catalyst. Furthermore, the reaction to form the adduct can be carried out in a continuous process. The reaction is complete when the reaction product is free of isocyanate groups. The decrease in the isocyanate group content can be monitored, in particular, by titrimetric analysis or by infrared spectroscopy. Preferably, the reaction is carried out without the use of organic solvents.The reaction yields the mercapto-functional adduct according to the invention. As already mentioned, it contains a mixture of unreacted polymercaptan and adducted molecules in which polymercaptans are adducted via thiourethane bonds. The type of polymercaptan used, the isocyanate-containing polymer used, and the ratio of the number of mercapto groups to the number of isocyanate groups primarily determine the composition of the adduct obtained. An isocyanate-containing polymer with an isocyanate functionality of more than two and / or a polymercaptan with more than two mercapto groups leads to a high mercapto functionality of the adduct. The properties of the adduct according to the invention can be specifically influenced, in particular, by varying the polymercaptan used, the isocyanate-containing polymer, and the stoichiometric ratio during the reaction.Surprisingly, an adduct starting from an isocyanate-containing polymer with a low content of monomeric diisocyanates has been shown to exhibit high elongation combined with high strength, and thus high impact resistance, when used in epoxy resin compositions. Compared to a corresponding adduct starting from an isocyanate-containing polymer produced conventionally without monomer removal, the adduct according to the invention surprisingly offers higher strength and / or higher elongation when used in a hardener for epoxy resin compositions. In particular, the processability of the composition is also especially good due to its lower viscosity.Preferably, the adduct according to the invention contains less than 5 parts by weight, preferably less than 1 part by weight, and in particular less than 0.5 parts by weight, of volatile organic solvents with a boiling point at atmospheric pressure of less than 250 °C, based on 100 parts by weight of the reaction product of polymercaptan and isocyanate-containing polymer. Such an adduct causes particularly low emissions. Preferably, the adduct is liquid at room temperature and has a low viscosity. In particular, the adduct has a viscosity at 20 °C of 1 to 500 Pa·s, preferably 2 to 300 Pa·s, and in particular 3 to 250 Pa·s, measured using a cone-plate viscometer with a cone diameter of 10 mm, a cone angle of 1°, a cone tip-to-plate distance of 0.05 mm, and a shear rate of 10 s. -1Preferably, the adduct according to the invention has an average mercapto equivalent weight of 150 to 1,500 g / eq, particularly 200 to 1,000 g / eq. The mercapto equivalent weight can be calculated from the mercapto equivalent weight of the polymer captan used and the NCO content of the isocyanate-containing polymer, or it can be determined using a suitable analytical method. The mercapto-functional adduct according to the invention is advantageously used for curing compounds with at least two reactive groups that are reactive towards mercapto groups. Furthermore, the mercapto-functional adduct according to the invention can be used by curing it with a suitable catalyst under oxidation and the formation of disulfide groups.A further aspect of the invention is the use of the mercapto-functional adduct according to the invention as a hardener in a curable composition containing reactive groups selected from epoxy groups, isocyanate groups, aldehyde groups, vinyl groups, allyl groups, acrylate groups, and methacrylate groups. Aromatic aldehyde groups bonded to an aromatic or heteroaromatic carbon atom are preferred as aldehyde groups. Polyaldehydes with two or more aldehyde groups, such as terephthalaldehyde, isophthalaldehyde, or phthalaldehyde, or reaction products of polyisocyanates, particularly isocyanate-containing polymers, with hydroxyaldehydes, such as 5-hydroxymethylfurfural, ethoxylated salicylaldehyde, particularly 2-(2-hydroxyethoxy)benzaldehyde, or ethoxylated vanillin, particularly 4-(2-hydroxyethoxy)-3-methoxybenzaldehyde, are preferred.Such curable compositions cure with the adduct according to the invention in the presence of an acidic catalyst, such as p-dodecylbenzenesulfonic acid, forming a solid polymer with the formation of thioacetal groups. The adduct according to the invention is particularly preferably used in a curable composition containing epoxy groups. It enables the production of flexible or impact-modified epoxy resin products with good processability at ambient temperatures, rapid curing, and high final hardness and strength. A further object of the invention is therefore an epoxy resin composition comprising at least one epoxy resin and at least one hardener for epoxy resins, containing at least one mercapto-functional adduct as described above. A suitable epoxy resin is obtained in particular from the reaction of epichlorohydrin with polyols, polyphenols, or amines, or from the oxidation of olefins.Aromatic epoxy resins are preferred, in particular the glycidyl ethers of bisphenol A, bisphenol F or bisphenol A / F, where A stands for acetone and F for formaldehyde, which served as starting materials for the production of these bisphenols. In the case of bisphenol-F, positional isomers may also be present, in particular derived from 2,4'- or 2,2'-hydroxyphenylmethane, – dihydroxybenzene derivatives such as resorcinol, hydroquinone or catechin, – other bisphenols or polyphenols such as bis(4-hydroxy-3-methylphenyl)methane, 2,2-bis(4-hydroxy-3-methylphenyl)propane (bisphenol C), bis(3,5-dimethyl-4-hydroxyphenyl)methane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-tert.butylphenyl) propane, 2,2-bis(4-hydroxyphenyl)butane (bisphenol B), 3,3-bis(4-hydroxyphenyl)pentane, 3,4-bis(4-hydroxyphenyl)hexane, 4,4-bis(4-hydroxyphenyl)heptane, 2,4-bis(4-hydroxyphenyl)-2-methylbutane, 2,4-Bis(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1-Bis(4-hydroxyphenyl)cyclohexane (Bisphenol Z), 1,1-Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (Bisphenol TMC), 1,1-Bis(4-hydroxyphenyl)-1-phenylethane, 1,4-Bis[2-(4-hydroxyphenyl)-2-propyl]benzene (Bisphenol P), 1,3-Bis[2-(4-hydroxyphenyl)-2-propyl]benzene (Bisphenol M), 4,4'-Dihydroxydiphenyl (DOD), 4,4'-Dihydroxybenzophenone, Bis(2-hydroxynaphth-1-yl)methane, Bis(4-hydroxynaphth-1-yl)methane, 1,5-Dihydroxynaphthalene, Tris(4-hydroxyphenyl)methane, 1,1,2,2-Tetrakis(4-hydroxyphenyl)ethane, Bis(4-hydroxyphenyl)ether or Bis(4-hydroxyphenyl)sulfone, – novolacs, which are in particular condensation products of phenol or cresols with formaldehyde orParaformaldehyde, acetaldehyde, crotonaldehyde, isobutyraldehyde, 2-ethylhexanal, benzaldehyde, or furfural are aromatic amines such as aniline, toluidine, 4-aminophenol, 4,4'-methylenediphenyldiamine, 4,4'-methylenediphenyldi-(N-methyl)amine, 4,4'-[1,4-phenylene-bis(1-methylethylidene)]bisaniline (bisaniline P), or 4,4'-[1,3-phenylene-bis(1-methylethylidene)]bisaniline (bisaniline M). Other suitable epoxy resins are aliphatic or cycloaliphatic polyepoxides, in particular glycidyl ethers of saturated or unsaturated, branched or unbranched, cyclic or open-chain di-, tri-, or tetrafunctional C2- to C3-units. 30-Alcohols, in particular ethylene glycol, propylene glycol, butylene glycol, hexanediol, octanediol, polypropylene glycols, dimethylolcyclohexane, neopentyl glycol, dibromoneopentyl glycol, castor oil, trimethylolpropane, trimethylolethane, pentaerythrol, sorbitol or glycerol, or alkoxylated glycerol or alkoxylated trimethylolpropane; – a hydrogenated bisphenol A, F or A / F liquid resin, or the glycidylation products of hydrogenated bisphenol A, F or A / F; – an N-glycidyl derivative of amides or heterocyclic nitrogenous bases, such as triglycidyl cyanurate or triglycidyl isocyanurate, or reaction products of epichlorohydrin with hydantoin. – Epoxy resins from the oxidation of olefins, such as in particular vinylcyclohexene, dicyclopentadiene, cyclohexadiene, cyclododecadiene, cyclododecatriene, isoprene, 1,5-hexadiene, butadiene, polybutadiene or divinylbenzene.Other suitable epoxy resins are those produced by reacting bio-based hydroxy-functional raw materials with epichlorohydrin, in particular vanillin-based epoxy resins such as diglycidyl ethers of vanillin alcohol, or glycerol-based epoxy resins. Preferably, the epoxy resin is a liquid resin or a mixture containing two or more liquid epoxy resins. "Liquid epoxy resin" is defined as a technical-grade polyepoxide with a glass transition temperature below 25°C. Optionally, proportions of solid epoxy resin are also used. Aromatic liquid epoxy resins are preferred as epoxy resins, in particular bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, or phenol-formaldehyde novolac glycidyl ether, or mixtures thereof, especially a mixture of bisphenol A diglycidyl ether and bisphenol F diglycidyl ether. Such epoxy resins are very reactive, hydrophobic, and have a low viscosity for epoxy resins.They offer good processability, rapid curing, and high adhesive strength. Aromatic liquid epoxy resins with a mean epoxy equivalent weight of 150 to 250 g / eq are preferred. In addition to the epoxy resin, at least one epoxy-group-containing reactive diluent may be included. Suitable for this purpose are, in particular, 1,4-butanediol diglycidyl ethers, 1,6-hexanediol diglycidyl ethers, trimethylolpropane di- or triglycidyl ethers, phenylglycidyl ethers, cresyl glycidyl ethers, guaiacol glycidyl ethers, 4-methoxyphenyl glycidyl ethers, pn-butylphenyl glycidyl ethers, p-tert-butylphenyl glycidyl ethers, 4-nonylphenyl glycidyl ethers, 4-dodecylphenyl glycidyl ethers, cardanol glycidyl ethers, benzyl glycidyl ethers, allyl glycidyl ethers, butyl glycidyl ethers, hexyl glycidyl ethers, 2-ethylhexyl glycidyl ethers, or glycidyl ethers of natural alcohols such as, in particular, C8 to C9. 10 - or C 12- to C14 or C13 to C15 alkyl glycidyl ethers. Preferably, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, or p-tert-butylphenyl glycidyl ether is used as a reactive diluent. The hardener for epoxy resins contains the mercapto-functional adduct according to the invention. Additionally, the hardener preferably contains at least one polyamine with at least three hydrogen amines. Such a hardener enables the production of flexible or impact-modified epoxy resin products of very high strength.Suitable polyamines with at least 3 hydrogen amines are commercially available polyamines with aliphatic amine groups, such as those commonly used for curing epoxy resins, in particular 1,5-diamino-2-methylpentane (MPMD), 1,6-hexanediamine, 2,2(4),4-trimethyl-1,6-hexanediamine (TMD), 2-butyl-2-ethyl-1,5-pentanediamine (C11-neodiamine), isophoronediamine (IPDA), 1,3-bis(aminomethyl)benzene (MXDA), 1,4-bis(aminomethyl)benzene, 2,5-bis(aminomethyl)furan, 2,5-bis(aminomethyl)tetrahydrofuran, 1,3-bis(aminomethyl)cyclohexane (BAC), 1,4-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)- methane, 1,2-diaminocyclohexane (DACH), 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, 2(4)-methyl-1,3-diaminocyclohexane (MCDA), 2,5(2,6)-bis(aminomethyl)bicyclo[2.2.1]heptan (NBDA), N-Benzyl-1,2-ethandiamin, N-Furfuryl-1,2-ethan- diamin, N-Tetrahydrofurfuryl-1,2-ethandiamin, Diethylentriamin (DETA), Triethylen- tetramin (TETA), Tetraethylenpentamin (TEPA), Dipropylentriamin (DPTA), N-(2- Aminoethyl)-1,3-propandiamin (N3-Amin), N,N'-Bis(3-aminopropyl)1,2-ethandiamin (N4-Amin), Bis(1,6-hexylen)triamin (BHMT), N-3-Benzylaminopropyl-N'-3-aminopropyl- 1,2-ethandiamin,, 3-(3-(Dimethylamino)propylamino)propylamin (DMAPAPA), Polyetheramine wie Bis(2-aminoethyl)ether, 3,6-Dioxaoctan-1,8-diamin, 4,7- Dioxadecan-1,10-diamin, 4,7-Dioxadecan-2,9-diamin, 4,9-Dioxadodecan-1,12-diamin, 5,8-Dioxadodecan-3,10-diamin, 4,7,10-Trioxatridecan-1,13-diamin oder die als Jeffamine. ®Poly(oxy-1,2-propylene)di- or -triamines available from Huntsman D-230, D-400 or T-403, as well as corresponding types from BASF or Nitroil, phenalkamines or -amides, which are reaction products of cardanol with aldehydes, in particular formaldehyde, and polyamines, amine-functional adducts of the aforementioned amines with epoxides, as well as a combination of two or more of these amines. Preferred among these are IPDA, MXDA, BAC, N-benzyl-1,2-ethanediamine, N-3-benzyl-aminopropyl-N'-3-aminopropyl-1,2-ethanediamine, polyetheramines, phenalkamines or an amine-functional adduct of N-benzyl-1,2-ethanediamine with an epoxy resin, in particular a bisphenol A diglycidly ether. The epoxy resin composition may contain further components, in particular – further amines, especially amines with two hydrogen amines such as N,N'-dibenzyl-1,2-ethanediamine, monoamines such as benzylamine or furfurylamine,Polyamidoamines, in particular reaction products of dimer fatty acids with DETA, TETA or TEPA, Mannich bases or aromatic polyamines, in particular 4(2),4'-diaminodiphenylmethane or 2,4(6)-toluenediamine; compounds containing other mercapto groups, in particular mercaptan-terminated polysulfide polymers, mercaptan-terminated polyoxyalkylene ethers or polyesters of thiocarboxylic acids; impact modifiers with epoxide or amine groups, in particular amine-functionalized butadienes or reaction products of hydrophobic polyols or isocyanate-containing polymers with epoxy resins, or impact modifiers in the form of isocyanate-containing polymers with blocked isocyanate groups, in particular with cardanol-blocked isocyanate groups; reactive diluents, in particular epoxidized soybean oil or linseed oil, compounds containing aceto-acetate groups, butyrolactone. Silicones containing carbonates, aldehydes, isocyanates or reactive groups,– Accelerators for curing, in particular phenols, phenolic resins or Mannich bases such as, in particular, 2,4,6-tris(dimethylaminomethyl)phenol, organic carboxylic acids such as salicylic acid or 2-nitrobenzoic acid, organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid or 4-dodecylbenzenesulfonic acid, nitrates such as, in particular, calcium nitrate, tertiary amines, imidazoles, ammonium salts, amidines or guanidines, – Fillers, in particular ground or precipitated calcium carbonate, which may be coated with fatty acids, in particular stearates, barite, talc, quartz flour, quartz sand, silicon carbide, micaceous iron oxide, dolomite, wollastonite, kaolin, mica (potassium aluminum silicate), molecular sieves, aluminum oxide, zinc oxide, aluminum hydroxide, magnesium hydroxide, silica, pyrogenic silica, cement, gypsum, fly ash, carbon black, Graphite, ground fillers from agricultural sources such as olive kernel flour or nut shell flour, hollow spheres, especially glass spheres,Metal powders such as aluminum, copper, iron, zinc, silver or steel, or PVC powders; pigments, in particular titanium dioxide, iron oxides, chromium(III) oxides, organic pigments, carbon black or corrosion protection pigments, in particular phosphates, orthophosphates or polyphosphates, which contain as a counterion in particular chromium, zinc, aluminum, calcium, strontium or a combination of these metals; surfactant additives, in particular defoamers, deaerators, wetting agents, dispersants, leveling agents or dispersed paraffin waxes; solvents or thinners, in particular benzyl alcohol, styrenized phenol, 2-phenoxyethanol, 2-benzyloxyethanol, aromatic hydrocarbon resins containing phenol groups, diisopropylnaphthalene, isopropyl biphenyls, cardanol or phenol-formaldehyde novolacs; polymers, in particular polyamides, polysulfides, polyvinyl formal (PVF), polyvinyl butyral (PVB), polyurethanes (PUR), polymers with carboxyl groups, polyamides,Butadiene-acrylonitrile copolymers, styrene-acrylonitrile copolymers, butadiene-styrene copolymers, homo- or copolymers of unsaturated monomers, in particular from the group comprising ethylene, propylene, butylene, isobutylene, isoprene, vinyl acetate or alkyl(meth)acrylates, in particular chlorosulfonated polyethylenes or fluorine-containing polymers or sulfonamide-modified melamines, – fibers, in particular glass fibers, carbon fibers, metal fibers, ceramic fibers or plastic fibers such as polyamide fibers or polyethylene fibers, – nanofillers, in particular carbon nanotubes, – rheology modifiers, in particular thickeners or anti-settling agents, – adhesion promoters, in particular organoalkoxysilanes, – flame retardants, in particular the fillers already mentioned, aluminium hydroxide or magnesium hydroxide, antimony trioxide, antimony pentoxide, boric acid (B(OH)3), zinc borate, zinc phosphate, melamine borate, Melamine cyanurate, ammonium polyphosphate, melamine phosphate, melamine pyrophosphate,Polybrominated diphenyl oxides or diphenyl ethers, phosphates such as in particular diphenylcresyl phosphate, resorcinol bis(diphenyl phosphate), resorcinol diphosphate oligomer, tetraphenylresorcinol diphosphite, ethylenediamine diphosphate, bisphenol A bis(diphenyl phosphate), tris(chloroethyl) phosphate, tris(chloropropyl) phosphate, tris(dichloroisopropyl) phosphate, tris[3-bromo-2,2-bis(bromomethyl)propyl] phosphate, tetrabromobisphenol A, bis(2,3-dibromopropyl ether) of bisphenol A, brominated epoxy resins, ethylene bis(tetrabromophthalimide), ethylene bis(dibromonorbornane dicarboximide), 1,2-bis(tribromophenoxy)ethane, tris(2,3-dibromopropyl)isocyanurate, tribromophenol, hexabromocyclododecane, Bis(hexachlorocyclopentadieno)cyclooctane or chlorinated paraffins, or stabilizers against oxidation, heat, light or UV radiation, or biocides. Preferably, the epoxy resin composition contains less than 5% by weight, in particular less than 1% by weight,Organic solvents with a boiling point at normal pressure of less than 250 °C, based on the total epoxy resin composition. Preferably, the epoxy resin composition contains less than 5% by weight of water, based on the total epoxy resin composition. Preferably, the molar ratio of the sum of hydrogen amines and mercapto groups to the epoxy groups in the epoxy resin composition is in the range of 0.5 to 1.5, particularly 0.8 to 1.2. Preferably, the mercapto-functional adduct according to the invention is present in the epoxy resin composition in such an amount that the weight ratio between the mercapto-functional adduct and epoxy resins is in the range of 5 / 95 to 70 / 30, preferably 7 / 93 to 50 / 50, particularly 10 / 90 to 35 / 65. Such an epoxy resin composition has high hardness and high strength.Good elongation and good impact strength. Preferably, the epoxy resin composition comprises a resin component and a hardener component, each of which is independently stable and stored in separate containers. For use of the epoxy resin composition, the resin and hardener components are mixed together shortly before or during application, at which point the curing process begins. The resin component comprises at least one epoxy resin, optionally at least one epoxy group-containing reactive diluent, and optionally further components reactive with hydrogen amines or mercapto groups. The hardener component comprises the mercapto-functional adduct according to the invention and optionally further components reactive with epoxy groups, such as, in particular, at least one polyamine with at least three hydrogen amines. Further components of the epoxy resin composition, such as, in particular, fillers, pigments,Accelerators or surfactant additives can be present as components of the resin or the hardener, or as components of both. The resin and hardener components of the epoxy resin composition are stored in separate containers. Suitable containers for storing the resin or hardener components include, in particular, a drum, a pail, a bag, a bucket, a can, a cartridge, or a tube. The components are storable, meaning they can be stored for several months up to a year or longer before use without their respective properties changing to an extent relevant for their application. The resin and hardener components are mixed shortly before or during application. The mixing ratio is preferably chosen such that the molar ratio of the epoxy-reactive groups to the epoxy groups is in the range of 0.5 to 1.5.in particular 0.8 to 1.2. In parts by weight, the mixing ratio between the resin and the hardener components is typically in the range of 1:2 to 20:1. The components are mixed using a suitable method, in particular a static mixer or a dynamic mixer. Mixing can be continuous or batchwise. Mixing and application can take place at ambient temperature, which is typically in the range of 5 to 45 °C, preferably 10 to 35 °C. If the components are mixed before application, care must be taken to ensure that not too much time elapses between mixing and application and that the application takes place within the pot life. The curing of the epoxy resin composition by chemical reaction begins with the mixing of the ingredients or components. The mercapto groups of the adduct according to the invention,The hydrogen amines of any amines present, and any other groups reactive towards epoxide groups, react with the epoxide groups, causing ring opening. As a result primarily of these reactions, the composition polymerizes and thus hardens. The curing process typically extends over several hours to several days. The duration depends, among other things, on the temperature, the reactivity of the components, their stoichiometry, and any accelerators present. Curing can occur at ambient conditions, particularly at 5 to 45 °C, preferably at 10 to 35 °C, or it can be accelerated and / or completed by heating, particularly by heating to a temperature of 50 to 130 °C, preferably 70 to 120 °C, preferably for 5 minutes to 24 hours.especially during periods of 30 minutes to 4 hours. The epoxy resin composition is preferably applied to at least one substrate. Suitable substrates include, in particular: glass, glass ceramics, concrete, mortar, cement screed, fiber cement, brick, tile, gypsum, or natural stone such as granite or marble; repair or leveling compounds based on PCC (polymer-modified cement mortar) or ECC (epoxy-modified cement mortar); metals or alloys such as aluminum, iron, steel, copper, other non-ferrous metals, including surface-treated metals or alloys such as galvanized or chrome-plated metals; asphalt or bitumen; leather, textiles, paper, wood, bonded with resins, for example phenolic, melamine, or epoxy resins, wood-based materials, resin-textile composites, or other so-called polymer composites. – Plastics such as rigid and flexible PVC, polycarbonate, polystyrene, polyester, polyamide, PMMA, ABS, SAN, epoxy resins, phenolic resins, PUR, POM, TPO, PE, PP,EPM or EPDM, either untreated or surface-treated, for example by plasma, corona, or flame; – Fiber-reinforced plastics, such as carbon fiber-reinforced plastics (CFRP), glass fiber-reinforced plastics (GFRP), natural fiber-reinforced plastics (NFRP), and sheet molding compounds (SMC); – Insulating materials, in particular foams, especially those made of EPS, XPS, PUR, PIR, aerogel, or foamed glass (Foamglas), or fibers made of rock wool or glass wool; – Coated or painted substrates, in particular painted tiles, painted concrete, powder-coated metals or alloys, or painted sheets; – Coatings, paints, or varnishes. The substrates can be pre-treated before application if required.In particular, this can be achieved through physical and / or chemical cleaning processes or the application of an activator or primer. Two identical or two different substrates can be bonded and / or sealed. The application and curing process yields the cured epoxy resin composition. This is characterized by high hardness and strength, combined with high impact resistance or high flexibility. The epoxy resin composition is suitable for a wide variety of applications. It is particularly suitable as an adhesive, casting resin, coating, or filler. The epoxy resin composition is especially suitable as an adhesive. Such an epoxy resin adhesive is particularly suitable for bonds requiring high strength and high impact resistance or crash resistance.The adhesive can absorb high forces without breaking in the event of strong mechanical stress on the bond. The epoxy resin adhesive preferably has a paste-like consistency. Preferably, the adhesive can be applied from a dual cartridge with separate chambers for the resin and hardener components using an attached static mixer. It is advantageous if the adhesive has a low viscosity. Furthermore, such an adhesive preferably has a mixing ratio by volume of 1:1 between the resin and hardener components. Such an adhesive is particularly easy to process using a dual cartridge and attached static mixer. The adduct according to the invention enables the production of epoxy resin compositions, especially epoxy resin adhesives, with very good processability and rapid curing.good adhesion properties and a surprising combination of high strength and high elongation, and thus high impact strength. Examples The following are exemplary embodiments intended to further illustrate the described invention. Of course, the invention is not limited to these described embodiments. "Standard climate" ("SC") refers to a temperature of 23°C and a relative humidity of 50%. Unless otherwise specified, the chemicals used were supplied by Sigma-Aldrich Chemie GmbH. Description of the measurement methods: The viscosity was measured on a thermostatically controlled cone-plate viscometer Rheotec RC30 (cone diameter 10 mm, cone angle 1°, cone tip-plate distance 0.05 mm, shear rate 10 s). -1Infrared spectra (FT-IR) were measured as undiluted films on a Thermo Scientific Nicolet iS5 FT-IR instrument equipped with a horizontal ATR measuring unit with a diamond crystal. The absorption bands are given in wavenumbers (cm⁻¹). –1 The content of monomeric diisocyanate was determined by HPLC (detection via photodiode array; 0.04 M sodium acetate / acetonitrile as mobile phase) after prior derivatization with N-propyl-4-nitrobencylamine. Substances used and abbreviations: TMPMP: 1,1,1-Trimethylolpropane tris(3-mercaptopropionate) technical grade, 138 g / eq SH (Thiocure) ® TMPMP, from Bruno Bock GmbH) GDMP: Ethylene glycol di(3-mercaptopropionate) technical grade, 123.5 g / eq SH (Thiocure ® GDMP, from Bruno Bock GmbH) BADGE: Bisphenol A diglycidyl ether (Araldite ® GY-250, EEW 188 g / eq, from Huntsman) K54: 2,4,6-Tris(dimethylaminomethyl)phenol (Ancamine ®K54 (from Evonik) MXDA: 1,3-Bis(aminomethyl)benzene, AHEW 34 g / eq (from Mitsubishi Gas Chem.) Preparation of isocyanate-containing polymers: Polymer-1: 600 g polyoxypropylenediol (Voranol) ® 1010 L, OH number 112 mg KOH / g, from Dow) and 533.3 g isophorone diisocyanate (Vestanate) ^ IPDI (from Evonik) was reacted at 80 °C according to a known procedure to form a reaction mixture with an NCO content of 15.6 wt%. Subsequently, the volatile components, in particular unreacted isophorone diisocyanate, were removed by distillation in a short-path evaporator (jacket temperature 160 °C, pressure 0.1 to 0.005 mbar), yielding a polymer with a viscosity at 20 °C of 10.7 Pa^s, an NCO content of 5.0 wt%, and a monomeric isophorone diisocyanate (IPDI) content of 0.03 wt%. Polymer 2: 727 g polyoxypropylene diol (Acclaim) ® 4200, OH number 28 mg KOH / g, from Covestro) and 273 g 4,4'-Diphenylmethane diisocyanate (Desmodur ^44 MC L (from Covestro) were reacted at 80 °C according to a known procedure to give a reaction mixture with an NCO content of 7.6 wt%. Subsequently, the volatile components, in particular monomeric 4,4'-diphenylmethane diisocyanate, were removed by distillation in a short-path evaporator (jacket temperature 180 °C, pressure 0.1 to 0.005 mbar, condensation temperature 47 °C), yielding a polymer with a viscosity at 20 °C of 17.4 Pa^s, an NCO content of 1.8 wt%, and a monomeric 4,4'-diphenylmethane diisocyanate (MDI) content of 0.08 wt%. Polymer 3: 725 g ethylene oxide-terminated polyoxypropylenetriol (Desmophen). ® 5031 BT, OH number 28.0 mg KOH / g, OH functionality approx. 2.3, from Covestro) and 275 g 4,4'-Diphenylmethane diisocyanate (Desmodur ^44 MC L (from Covestro) were reacted at 80 °C according to a known procedure to give a reaction mixture with an NCO content of 7.6 wt%. Subsequently, the volatile components, in particular unreacted 4,4'-diphenylmethane diisocyanate, were removed by distillation in a short-path evaporator (jacket temperature 180 °C, pressure 0.1 to 0.005 mbar), yielding a polymer with a viscosity at 20 °C of 25.1 Pa^s, an NCO content of 1.7 wt%, and a monomeric 4,4'-diphenylmethane diisocyanate content of 0.04 wt%. Polymer 4: 780 g ethylene oxide-terminated polyoxypropylenetriol (Desmophen). ® 5031 BT, OH number 28.0 mg KOH / g, OH functionality approx. 2.3, from Covestro) and 303 g isophorone diisocyanate (Vestanat) ^IPDI (from Evonik) were reacted at 80 °C according to a known procedure to form a reaction mixture with an NCO content of 9.1 wt%. Subsequently, the volatile components, in particular unreacted isophorone diisocyanate, were removed by distillation in a short-path evaporator (jacket temperature 160 °C, pressure 0.1 to 0.005 mbar), yielding a polymer with a viscosity at 20 °C of 16.4 Pa^s, an NCO content of 1.8 wt%, and a monomeric isophorone diisocyanate content of 0.02 wt%. Polymer-5: 600 g polyoxypropylenediol (Voranol) ® 1010 L, OH number 112 mg KOH / g, from Dow) and 266.6 g isophorone diisocyanate (Vestanate) ^ IPDI (from Evonik) were reacted at 80 °C according to a known process to form a polymer with a viscosity at 20 °C of 26.5 Pa^s, an NCO content of 5.1 wt%, and a monomeric isophorone diisocyanate (IPDI) content of more than 1 wt%. Polymer-6: 400 g polyoxypropylene diol (Acclaim ®4200, OH number 28 mg KOH / g, from Covestro) and 52 g 4,4'-Diphenylmethane diisocyanate (Desmodur ^44 MC L, from Covestro) were reacted at 80 °C according to a known process to give a polymer with a viscosity at 20 °C of 43.6 Pa^s, an NCO content of 1.8 wt%, and a monomeric 4,4'-diphenylmethane diisocyanate (MDI) content of 2.3 wt%. Preparation of mercapto-functional adducts: Adducts S1 to S7 and R1 to R3: The amount (in grams) of the specified polymercaptan given in Table 1 was reacted in the presence of 2 drops of triethylamine at room temperature, excluding moisture, with the specified amount (in grams) of the specified isocyanate-containing polymer until no more isocyanate groups were detectable by IR spectroscopy. The properties of the adducts are given in Table 1. Adducts R1 to R3, designated "(Ref.)", serve as comparative examples. They are based on an isocyanate group-containing polymer with a high content of monomeric diisocyanate.

[0002] Adduct S1 R1 R2 (Ref.) S2 S3 (Ref.) Polymer-1 100.0 - 100.0 - - Polymer-2 - - - 100.0 - Polymer-3 - - - - - Polymer-4 - - - - - Polymer-5 - 100.0 - - - Polymer-6 - - - - 100.0 TMPMP 123.0 125.7 - 44.4 44.4 GDMP - - 73.5 - - NCO / OH ratio at the start of the production of the NCO-containing polymer 4 / 1 2 / 1 4 / 1 6 / 1 2 / 1 mer Monomer content of the NCO-containing polymer 0.03 % > 1 % 0.03 % 0.08 % 2.3 % [wt.%] IPDI IPDI IPDI MDI MDI Viscosity (20°C) [Pa^s] 61.2 81.2 10.4 147 217 SH / NCO ratio 1 7.5 7.5 5.0 7.5 7.5 Polymer captane / NCO ratio 2 2.5 2.5 2.5 2.5 2.5 SH equivalent weight 3 [g / eq] 289 286 364 518 518 Table 1: Mercapto-functional adducts S1 to S7 and R1 to R3. 1 Ratio of the number of mercapto groups to the number of isocyanate groups 2 Ratio of the number of polymercaptan molecules to the number of isocyanate groups 3 Calculated

[0003] Adduct S4 R3 (Ref.) S5 S6 S7 Polymer-1 - - - - Polymer-2 100.0 - - - - Polymer-3 - - 100.0 - - Polymer-4 - - - 100.0 100.0 Polymer-5 - - - - - Polymer-6 - 100.0 - - - TMPMP - - - - 44.4 GDMP 26.5 26.5 25.0 26.5 - NCO / OH ratio at the start of the production of the NCO-containing polymer 6 / 1 2 / 1 6 / 1 7 / 1 7 / 1 mer Monomer content of the NCO-containing polymer 0.08 % 2.3 % 0.04 % 0.02 % 0.02 % [wt.%] MDI MDI MDI IPDI IPDI Viscosity (20°C) [Pa^s] 70 107 242 48 66 SH / NCO ratio 1 5.0 5.0 5.0 5.0 7.5 Polymer captane / NCO ratio 2 2.5 2.5 2.5 2.5 2.5 SH equivalent weight 3[g / eq] 737 737 772 737 518 Table 1: (continued) Use in epoxy resin compositions: Compositions Z1 and Z2: For each composition, the amount of bisphenol A diglycidyl ether (in parts by weight) specified in Table 2 was used as the resin component. Furthermore, the ingredients of the hardener component specified in Table 2 were mixed in the specified amounts (in parts by weight) and stored in a dry place. Subsequently, the two components of each composition were processed into a homogeneous liquid using a centrifugal mixer and immediately tested as follows: The gel time was determined by stirring a freshly mixed quantity of approximately 3 g at regular intervals with a spatula under standard climatic conditions until the mixture gelled.To determine the mechanical properties, the mixed composition was applied to a silicone-coated release paper to form a 2 mm thick film. This film was stored for 7 days under standard climatic conditions. Several dumbbell-shaped test specimens (length 75 mm, web length 30 mm, web width 4 mm) were punched out of the film and tested for tensile strength, elongation at break, and modulus of elasticity (5% at 0.5–5% elongation) according to DIN EN 53504 at a tensile speed of 200 mm / min. The Shore A hardness was determined according to DIN 53505 on test specimens cured for 7 days under standard climatic conditions. The results are given in Table 2. The composition Z2, designated "(Ref.)", is a comparative example. Composition Z1 Z2 (Ref.) Resin component: BADGE 188 188 Hardener component: Adduct S1 289 - Adduct R1 - 286 K54 2.3 2.3 Gel time [h:min] 1:15 1:00 Tensile strength [MPa] 17.5 11.7 Elongation at break [%] 150 125 Modulus of elasticity 5% [MPa] 46.5 14.3 Shore A 88 95 Table 2: Composition and properties of Z1 and Z2. Table 2 shows that composition Z1 with the adduct S1 according to the invention, starting from a monomer-free isocyanate-containing polymer, exhibited very high strength (tensile strength and modulus of elasticity) with very high elongation at break. The comparative composition Z2 (Ref.) with adduct R1, based on a corresponding isocyanate-containing polymer with a typically high content of monomeric diisocyanate, showed significantly lower tensile strength and a much lower modulus of elasticity, with slightly less elongation at break. This is surprising, as a person skilled in the art would expect the reaction products of monomeric IPDI and TMPMP in adduct R1 to result in increased strength with reduced elongation.Compositions Z3 to Z6: For each composition, the amount of bisphenol A diglycidyl ether (in parts by weight) specified in Tables 3 and 4 was used as the resin component. Furthermore, the ingredients of the hardener component specified in Tables 3 and 4 were mixed in the indicated amounts (in parts by weight) and stored in a dry place. Subsequently, the two components of each composition were processed into a homogeneous liquid using a centrifugal mixer and immediately tested as follows: The viscosity (5') was measured 5 minutes after mixing the resin and hardener components as described, at a temperature of 20 °C.To determine the mechanical properties, the mixed composition was cured in a silicone mold under standard climate conditions to form dumbbell-shaped test specimens (2 mm thick, 75 mm long, 30 mm web length, 4 mm web width). The cured specimens were removed from the mold and tested for tensile strength, elongation at break, and modulus of elasticity (1% at 0.5–1% elongation) according to EN ISO 527 at a tensile speed of 10 mm / min. Curing was carried out either for 7 days under standard climate conditions (indicated in the tables as "7d NK"), or for 24 hours under standard climate conditions followed by 24 hours at 80°C, followed by 3 days under standard climate conditions (indicated in the tables as "1d NK + 1d 80°C"). The Shore D hardness was determined according to DIN 53505 on test specimens hardened for 1 day (24h) or 2 days in standard climate conditions, indicated in the tables as "(1d NK)" or "(2d NK)".The Tg value (glass transition temperature) was determined by DSC on cured samples stored for 14 days under standard climate conditions, using a Mettler Toledo DSC 3+ 700 instrument and the following measurement program: (1) -10 °C for 2 min, (2) -10 to 200 °C with a heating rate of 10 K / min (= 1st run), (3) 200 to -10 °C with a cooling rate of -50 K / min, (4) -10 °C for 2 min, (5) -10 to 180 °C with a heating rate of 10 K / min (= 2nd run). The results are given in Tables 3 and 4. The composition Z6, designated "(Ref.)", is a comparison example. Composition Z3 Z4 Resin component: BADGE 188 188 Hardener component: Adduct S1 144.5 - Adduct S2 - 144.5 MXDA 17.0 20.5 K54 2.1 2.1 Viscosity (5') [Pa^s] 21.4 11.8 1d NK + 1d 80°C: Tensile strength [MPa] 39.7 25.2 Elongation at break [%] 13 41 Modulus of elasticity 1% [MPa] 1884 1105 Shore D (1d NK) 74 59 (2d NK) 79 66 Table 3: Composition and properties of Z3 and Z4.

[0004] Composition Z5 Z6 (Ref.) Resin component: BADGE 188 188 Hardener component: Adduct S3 70.0 - Adduct R2 - 70.0 MXDA 29.7 29.2 Viscosity (5') [Pa^s] 18.7 23.5 Gel time [h:min] 2:10 2:10 7d NK: Tensile strength [MPa] 28.3 33.9 Elongation at break [%] 54.2 8.1 Modulus of elasticity 0.5-1% [MPa] 1290 1352 1d NK + 1d 80°C: Tensile strength [MPa] 36.4 39.6 Elongation at break [%] 23.8 7.4 Modulus of elasticity 1% [MPa] 1264 1510 Tg 1st / 2nd run [°C] 87 / 104 88 / 104 Table 4: Composition and properties of Z5 and Z6. Table 4 shows that composition Z5 with the adduct S3 according to the invention, starting from a monomer-free isocyanate-containing polymer, exhibited high elongation at break with high strength (tensile strength and modulus of elasticity). The comparative composition Z6 (Ref.) with the adduct R2 based on a corresponding isocyanate-containing polymer with a typically high content of monomeric diisocyanate in conventional preparation showed a significantly lower elongation at break with similarly high strength. Compositions Z7 to Z11: (Epoxy resin adhesives) A ​​resin component was prepared by mixing the following ingredients in the specified amounts (in parts by weight, wt) and storing them under exclusion of moisture: 40 wt Bisphenol A diglycidyl ether (Epikote. ® 828 LVEL, from Westlake Epoxy), 16 GT bisphenol F diglycidyl ether (Epicote ® 862, from Westlake Epoxy), 6 GT Butanediol diglycidyl ether (Araldite ® DY-D (from Huntsman), 20 g of reaction product U1, prepared as described below, 1 g of 3-glycidoxypropyltrimethoxysilane, 12 g of fillers, and 5 g of pyrogenic silica. The reaction product U1 was prepared by reacting 5687 g of polyetherdiol (Acclaim)® 4200, OH number 28 mg KOH / g, from Covestro), 712 g 4,4'- Diphenylmethane diisocyanate (Desmodur ® 44 MC L, from Covestro) at 80 °C to a constant NCO content of 1.9 wt.%, followed by reaction with Cardanol (Cardolite) ® NC-700 (from Cardolite) was heated for 2 hours at 80 °C until no isocyanate groups were detectable by FT-IR. A hardener component was then prepared by mixing the following ingredients in the specified amounts (in parts by weight, wt) and storing them in a dry place: 14 wt modified polyamine (Ancamine) ® 2712M, AHEW 95 g / eq, from Evonik), 6 GT Polyetheramine (Jeffamine) ® D-230, AHEW 60 g / eq, from Huntsman), 6 GT Phenalkamine (Cardolite ® LITE 2002, AHEW 104 g / eq, from Cardolite), 5 GT 2,4,6-Tris(dimethylaminomethyl)phenol (Ancamine ®K54 (from Evonik), 44 g fillers, 6 g pigments, 4 g pyrogenic silica and 15 g of the adduct or commercial amine-functional butadiene-acrylonitrile copolymer specified in Table 5 (Hypro ®1300X16 ATBN, AHEW 900 g / eq, from Huntsman), listed as "ATBN" in Table 5. The two components of each composition were then mixed to form a homogeneous liquid in the mixing ratio specified in Table 5 using a centrifugal mixer and immediately tested as follows: The mechanical properties of tensile strength, elongation at break, and modulus of elasticity were determined as described for composition Z3, with curing carried out for 1 hour in standard climate followed by 1 hour at 80 °C followed by 1 day in standard climate. The specimen thickness was 1 mm, the measurement was performed at a tensile speed of 2 mm / min, and the modulus of elasticity was determined to be 0.25% (at 0.05 to 0.25% elongation). The dynamic resistance was determined as a measure of impact strength using an impact peel test according to ISO 11343. For this purpose, test specimens were made with two bonded electrolytically zinc-plated DC04 steel plates 90 x 20 x 0.8 mm thick, manufactured with a bonding area of ​​20 x 30 mm and an adhesive thickness of 0.3 mm, cured for 1 hour under standard climate conditions followed by 1 hour at 80 °C, followed by 1 day under standard climate conditions. The impact peel resistance was measured at an impact velocity of 2 m / s. The results are given in Table 5. The compositions marked "(Ref.)" are comparative examples. Composition Z7 Z8 Z11 (Ref) Z9 Z10 (Ref) Added Adduct Adduct Adduct Adduct Toughener S4 R3) S5 S6 ATBN Mixing ratio. 1100 / 112 100 / 112 100 / 112 100 / 112 100 / 113 1h 80°C: Tensile strength [MPa] 22.3 20.2 25.5 22.3 22.9 Elongation at break [%] 6.3 4.2 4.7 5.5 4.9 Modulus of elasticity 0.25% [MPa] 1850 1760 2200 1790 2120 1h 80°C: Impact Peel Dynamic Resistance 21.7 15.6 27.8 26.9 24.8 [N / mm] Table 5: Composition and properties of Z7 to Z11. 1 Resin component / hardener component (weight) Table 5 shows that the adhesive according to the invention of composition Z7, in which the adduct used as a toughener is based on an NCO-containing polymer with a low content of monomeric diisocyanate, exhibited higher strength (tensile strength and modulus of elasticity) and higher impact strength (impact peel, dynamic resistance) than the adhesive of composition Z8 (Ref.) based on a corresponding NCO-containing polymer with a high content of monomeric diisocyanate.The adhesives according to the invention, compositions Z9 and Z10, both exhibit significantly higher impact strength than the reference adhesive of composition Z11 (Ref.) with a commercially available amine-functional ATBN. Use in aldehyde-containing compositions: Compositions Z12 and Z13: For each composition, the ingredients of the first component K1, as specified in Table 6, were mixed in the indicated quantities (in parts by weight) using a centrifugal mixer and stored in a sealed container. Similarly, the ingredients of the second component K2, as specified in Table 6, were processed and stored. Subsequently, the two components of each composition were mixed to form a homogeneous liquid using the centrifugal mixer and immediately tested as follows: Gel time, tensile strength, elongation at break, modulus of elasticity (5%), and Shore A were tested as described for composition Z1.The tensile shear strength on glass was determined as a measure of the strength of an adhesive bond. For this purpose, composite specimens were produced by degreasing two glass surfaces with isopropanol and applying Sika adhesive. ® Glass plates pretreated with Activator-205 (from Sika Switzerland) were bonded together such that the overlapping adhesive joint had dimensions of 12 x 25 mm and a thickness of 4 mm, with the glass plates protruding at the ends. After storage of the composites for 7 days under standard climatic conditions, the tensile shear strength was tested according to DIN EN 1465 at a tensile rate of 20 mm / min. Subsequently, the fracture pattern was assessed, where "CF" stands for cohesive failure covering 90 to 100% of the fracture surface. The results are given in Table 6.

[0005] Composition Z12 Z13 Component K1: Aldehyde-functional polymer 1 20.0 20.0 Diisodecyl phthalate 15.6 17.9 Aluminum hydroxide (ATH) 2 22.7 25.9 Russ 37.8 8.9 Component K2: Adduct S1 S7 4.2 7.8 3-Mercaptopropyltrimethoxysilane 0.4 0.4 p-Dodecylbenzenesulfonic acid 0.2 0.2 Gel time [min] 10 35 Tensile strength [MPa] 2.1 2.3 Elongation at break [%] 104 130 Modulus of elasticity 5% [MPa] 3.5 3.3 Shore A 59 58 Tensile shear strength (glass) [MPa] 1.2 1.2 Fracture pattern CF CF Table 6: Composition and properties of Z12 and Z13. 1 Aldehyde equivalent weight 2400 g / eq, from the reaction of 500 g of polymer-4 with 27.7 g of 5-hydroxymethylfurfural in the presence of 0.1 g of dibutyltin dilaurate at 110 °C, until no isocyanate groups were detectable by IR spectroscopy. 2 Martinal ® OL-104 (from Martinswerk) 3 Monarch ® 570 (by Cabot)

Claims

Claims:

1. Mercapto-functional adduct from the reaction of – at least one polymercaptan with – at least one isocyanate-group-containing polymer with an average molecular weight M nof at least 1,000 g / mol, in a ratio of the number of mercapto groups to the number of isocyanate groups at the start of the reaction of at least 2.5, wherein the isocyanate-containing polymer has a content of monomeric diisocyanates of the formula, based on the isocyanate-containing polymer, of less than 0.5 wt%, preferably less than 0.2 wt%, in particular less than 0.1 wt%, and D represents a divalent organic residue with 4 to 15 carbon atoms.

2. Adduct according to claim 1, characterized in that the ratio of the number of mercapto groups to the number of isocyanate groups at the start of the reaction is in the range of 2.5 to 20, preferably 3 to 15, more preferably 3.5 to 10, in particular 4 to 8.

3. Adduct according to one of claims 1 or 2, characterized in that the polymercaptan has two, three or four, in particular two or three, mercapto groups. 4.Adduct according to any one of claims 1 to 3, characterized in that the polymercaptan has a mercapto equivalent weight of 45 to 400 g / eq, preferably 90 to 300 g / eq, wherein the polymercaptan is in particular selected from the list consisting of 1,8-dimercapto-3,6-dioxaoctane, 1,2-ethanediol di(2-mercaptoacetate), 1,2-ethanediol di(3-mercaptopropionate), 1,2-ethanediol di(3-mercaptobutyrate), 1,4-butanediol di(2-mercaptoacetate), 1,4-butanediol di(3-mercaptopropionate), 1,4-butanediol di(3-mercaptobutyrate), glycerol di(2-mercaptoacetate), glycerol di(3-mercaptopropionate). Glycerol-di(3-mercaptobutyrate), Glycerol-tris(2-mercaptoacetate), Glycerol-tris(3-mercaptopropionate), Glycerol-tris(3-mercaptobutyrate), 1,1,1-Trimethylolpropane-di(2-mercaptoacetate), 1,1,1-Trimethylolpropane-di(3-mercaptopropionate), 1,1,1-Trimethylolpropane-di(3-. mercaptobutyrat), 1,1,1-Trimethylolpropan-tris(2-mercaptoacetat), 1,1,1-Tri- methylolpropan-tris(3-mercaptopropionat), 1,1,1-Trimethylolpropan-tris(3- mercaptobutyrat), Pentaerythritol-tris(2-mercaptoacetat), Pentaerythritol-tris(3- mercaptopropionat), Pentaerythritol-tris(3-mercaptobutyrat), Pentaerythritol- tetrakis(2-mercaptoacetat), Pentaerythritol-tetrakis(3-mercaptopropionat), Pentaerythritol-tetrakis(3-mercaptobutyrat), 3-Mercapto-2-hydroxypropylether von propoxyliertem Pentaerythritol mit einem mittleren Mercapto-Equivalentgewicht von 180 bis 400 g / eq, bevorzugt 180 bis 300 g / eq, Tris(2-(2- mercaptoacetyloxy)ethyl)isocyanurat, Tris(2-(3-mercaptopropionyl- oxy)ethyl)isocyanurat und Tris(2-(3-mercaptobutanoyloxy)ethyl)isocyanurat. 5.Adduct according to any one of claims 1 to 4, characterized in that the monomeric diisocyanate of the formula is selected from the list consisting of 1,6-hexane diisocyanate, 2,2(4),4-trimethyl-1,6-hexane diisocyanate, 1-methyl-2,4(6)-diisocyanatocyclohexane, isophorone diisocyanate, 4,4'-diisocyanatodicyclohexylmethane, 4(2),4'-diphenylmethane diisocyanate, and 2,4(6)-toluene diisocyanate.

6. Adduct according to any one of claims 1 to 5, characterized in that the isocyanate-containing polymer has an NCO content of 1 to 9 wt%, preferably 1.5 to 6.5 wt%. 7.An adduct according to any one of claims 1 to 6, characterized in that the isocyanate-containing polymer is a reaction product of at least one monomeric diisocyanate of the formula with at least one polymeric polyol in a molar NCO / OH ratio of 3:1 to 10:1 and subsequent removal of the monomeric diisocyanate by a suitable separation process to a content, based on the isocyanate-containing polymer, of less than 0.5 wt%, preferably less than 0.2 wt%, and in particular less than 0.1 wt%. An adduct according to claim 7, characterized in that the polymeric polyol is selected from the list consisting of polyether polyols, polyester polyols, and hydrocarbon polyols.

9. Adduct according to any one of claims 1 to 8, characterized in that the adduct, based on 100 parts by weight of reaction product of polymercaptan and isocyanate-containing polymer, contains less than 5 parts by weight, preferably less than 1 part by weight, and in particular less than 0.5 parts by weight, organic solvents with a boiling point at atmospheric pressure of less than 250 °C.

10. Adduct according to any one of claims 1 to 9, characterized in that the adduct has a viscosity at 20 °C of 1 to 500 Pa·s, preferably 2 to 300 Pa·s, and in particular 3 to 250 Pa·s, as measured by a cone-plate viscometer with a cone diameter of 10 mm, a cone angle of 1°, a cone tip-plate distance of 0.05 mm, and a shear rate of 10 s⁻¹. -111. Adduct according to any one of claims 1 to 10, characterized in that the adduct has a mean mercapto equivalent weight of 150 to 1,500 g / eq, preferably 200 to 1,000 g / eq.

12. Use of the adduct according to any one of claims 1 to 11 as a hardener in a curable composition comprising reactive groups selected from an epoxy group, an isocyanate group, an aldehyde group, a vinyl group, an allyl group, an acrylate group, and a methacrylate group.

13. Epoxy resin composition obtained from the use according to claim 12, comprising at least one epoxy resin and at least one hardener for epoxy resins comprising at least one adduct according to any one of claims 1 to 11.

14. Epoxy resin composition according to claim 13, characterized in that the hardener additionally comprises at least one polyamine with at least three hydrogen amines.

15. Epoxy resin composition according to one of claims 13 or 14, characterized in that the weight ratio between the mercapto-functional adduct and epoxy resins is in the range of 5 / 95 to 70 / 30, preferably 7 / 93 to 50 / 50, in particular 10 / 90 to 35 / 65.