Catalyst system comprising a thiol-group-containing compound

Abstract

The invention relates to a catalyst system which comprises at least components (C) and (K), wherein component (C) is at least one catalyst that contains bismuth (Bi) and zirconium (Zr) as metal components, and component (K) is at least one thiol-group-containing compound, and wherein the molar ratio of all thiol groups in component (K) to the total of all metal components in component (C) is ≤ 0.99 : 1 [mol / mol]. The invention also relates to a polyurethane system which comprises the catalyst system according to the invention, at least one polyhydroxy-group-containing compound (A), at least one polyisocyanate-group-containing compound (B), and optionally additional components, wherein, in a first option, all components (A) to (C) and (K), and, if applicable, also the additional optional components, are separate from one another, i.e. the individual components are not mixed together. In a second option of the polyurethane system according to the invention, the aforementioned components may, however, also be in part mixed together. If the components are in part mixed together, this means that, for example, components (C) and (K) are mixed with component (A), while component (B) is separate from this mixture of (A), (C), and (K). Optionally, however, component (B) may also be mixed with a partial quantity of component (C). Furthermore, the mixtures of (A), (C) and (K) and of (B) and (C) may additionally contain at least one optional component.

Description

[0001] Catalyst system comprising a thiol group-containing compound

[0002] Description

[0003] The invention relates to a catalyst system comprising at least components (C) and (K), wherein component (C) is at least one catalyst containing bismuth (Bi) and zirconium (Zr) as metal components, and component (K) is at least one compound containing thiol groups, and wherein the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is < 0.99:1 [mol / mol]. The present invention further provides a polyurethane system comprising the catalyst system according to the invention, at least one compound (A) containing polyhydroxy groups, at least one compound (B) containing polyisocyanate groups and optionally further components, wherein in a first option all components (A) to (C) and (K) and optionally also the further optional components are present separately from one another, i.e. the individual components are not mixed with one another.In a second option of the polyurethane system according to the invention, however, the aforementioned components can also be partially mixed with one another. If the components are partially mixed with one another, this means that, for example, components (C) and (K) are mixed with component (A), while component (B) is present separately from this mixture of (A), (C), and (K). Optionally, however, component (B) can also be mixed with a portion of component (C). Furthermore, the mixtures of (A), (C), and (K), as well as of (B) and (C), can additionally contain at least one optional component.

[0004] Preferably, components (C) and (K) are mixed with component (A), while component (B) is present separately from this mixture of (A), (C) and (K).

[0005] Further components that may be contained in the polyurethane system according to the invention are, for example, fillers (D), solvents (E) and / or further additives (F).

[0006] Further objects of the present invention are the use of the polyurethane system according to the invention as an adhesive, as a potting compound or as a binder in composite materials, preferably in the transport and construction industries, a method for bonding a surface of a first substrate to a surface of a second substrate using a polyurethane system according to the invention and the article resulting therefrom.

[0007] The production of polyurethanes by reacting a compound containing at least two hydroxyl groups per molecule with a compound containing at least two isocyanate groups per molecule has long been known. Depending on the reactivity of the respective compounds, spontaneous and / or partial curing (reaction of the two reactant components) can occur simply by mixing the reactant components. For technical reasons, however, the spontaneous reaction should be suppressed to ensure safe handling. However, in order to allow the reaction to proceed sufficiently quickly after mixing and a certain latency period, so-called catalysts are used.

[0008] Due to the reactivity of the two reactant components of the polyurethane, it is very common in practice for the respective reactant components to be prepared separately from one another. If necessary, the catalyst can be added beforehand to the reactant containing hydroxyl groups and / or the reactant containing isocyanate groups. Such systems are widely used in practice under the term "two-component (polyurethane) systems" (2K systems) and are also commercially available. Multi-component systems with more than two components are also conceivable; it may be the case that one component is not compatible with either of the other components, and therefore these three components can only be combined immediately before application.

[0009] On the other hand, it is also possible to provide single-component systems (mixtures / 1K system) in which, for example, by blocking the reactive groups of the individual reactants, for example, by blocking the free isocyanate groups with suitable blocking agents, the two reactant components and also the catalyst can be provided as a storable mixture. In practice, the individual starting components or, if applicable, the starting mixture in the 1K system often also contain additional components such as solvents.

[0010] Two-component (2K) polyurethane systems have the advantage over single-component (1K) systems in that they cure quickly after mixing and can therefore absorb and transfer higher forces within a short period of time. For the use of a polyurethane system as an adhesive or binder, high strength requirements are placed on such systems, as such adhesives or binders are elements of load-bearing structures.

[0011] However, for some applications, it is desirable for the two-component (2K) polyurethane system to have a slightly delayed curing time after mixing, meaning that the viscosity remains low for a certain period and does not increase. This ensures better pumpability of the mixture and thus improved processability.

[0012] WO 2019 / 002538 A1 discloses a polyurethane composition consisting of a first and a second component, wherein the first component A comprises at least one polyol A1 having an OH functionality in the range from 1.5 to 4 and an average molecular weight (number average) M nin the range from 250 to 15,000 g / mol, and at least one diol A2 having two hydroxyl groups linked via a C2 to C9 carbon chain, and at least one compound T having at least one thiol group; and the second component B comprises at least one polyisocyanate I; wherein one of the two components additionally contains at least one metal catalyst K for the reaction of hydroxyl groups and isocyanate groups, which can form thiocomplexes, and the second component contains such an amount of polyisocyanate I that at least 5% by weight, based on the total polyurethane composition, of isocyanate groups are present, and the molar ratio of all thiol groups of the at least one compound T to all metal atoms of the at least one metal catalyst K is between 1:1 and 250:1. The polyurethane composition can be used as a structural adhesive for bonding two substrates or as a matrix in composite materials.

[0013] WO 2020 / 127484 A1 discloses a method for applying a two-component polyurethane composition by means of 3D printing, comprising the steps of: providing a pumpable first component A comprising at least one polyol, preferably at least one diol, and at least one compound T having at least one thiol group; feeding a pumpable second component B into the mixing area of ​​the continuous mixer, wherein the second component B comprises at least one polyisocyanate, wherein one of the two components A and B additionally contains at least one metal catalyst for reacting hydroxyl groups and isocyanate groups, which can form thio complexes, and the molar ratio of all thiol groups of the at least one compound T to all metal atoms of the at least one metal catalyst is between 1:1 and 250:1.

[0014] The object of the present invention was therefore to provide a new catalyst for an improved polyurethane system.

[0015] The object is achieved by a catalyst system comprising at least the following components (C) and (K)

[0016] (C) at least one catalyst containing bismuth (Bi) and zirconium (Zr) as metal components, and

[0017] (K) at least one compound which has at least one thiol group, wherein the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is < 0.99:1 [mol / mol].

[0018] Furthermore, the object is achieved by a polyurethane system at least comprising the catalyst system according to the invention,

[0019] (A) at least one compound containing polyhydroxyl groups and

[0020] (B) at least one compound containing polyisocyanate groups, wherein i) components (A), (B), (C) and (K) are present separately from one another or ii) are partially mixed with one another.

[0021] The catalyst system according to the invention is characterized, among other things, by the fact that the use of toxic tin-containing catalysts can be avoided and / or rapid curing is ensured.

[0022] An advantage of the present invention is also that the presence of at least one compound containing thiol groups in the catalyst or polyurethane system according to the invention makes it possible to achieve a balanced relationship between pot life on the one hand and curing on the other.

[0023] "Curing" (hardening) in the context of the present invention means that components (A) and (B) contained in the polyurethane system according to the invention react with each other in the presence of the catalyst system to form a polyurethane. The reaction, i.e., curing, can take place at least partially, but preferably, complete curing occurs, i.e., components (A) and (B) contained in the polyurethane system according to the invention react completely or almost completely with each other.

[0024] The "pot life" in the context of the present invention is defined as the processability of the reactive materials. It is the time between mixing components (A) and (B) and the end of their processability, i.e., the period during which the reactive mixture can still be removed from the pot and processed. The end of the pot life is usually indicated by a significant increase in viscosity, which prevents further processing.

[0025] When used as an adhesive, the polyurethane system according to the invention advantageously exhibits a low viscosity after mixing the individual components and before curing, making it very easy to pump and process. This allows, for example, minor corrections or touch-ups after the adhesive has been applied to the substrate. Advantageously, the viscosity of the mixture remains low even for extended periods, for example, from a few minutes to hours, making the mixture pumpable, so that the mixture only cures after the substrates to be bonded have been joined.

[0026] The mixture advantageously cures quickly after the substrates to be bonded have been joined. This allows the resulting article according to the invention to be subjected to stress quickly, and any subsequent processing steps are not delayed. Therefore, the polyurethane system according to the invention is highly suitable as an adhesive in automotive manufacturing.

[0027] The catalyst or polyurethane system according to the invention and the further objects of the present invention are defined in more detail below.

[0028] Catalyst system

[0029] The first subject of the present invention is the catalyst system already mentioned above, comprising at least the following components (C) and (K)

[0030] (C) at least one catalyst containing bismuth (Bi) and zirconium (Zr) as metal components, and

[0031] (K) at least one compound which has at least one thiol group, wherein the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is < 0.99:1 [mol / mol].

[0032] In the catalyst system according to the invention, it is possible for the individual components (C) and (K), and optionally also further optional components, to be present separately from one another, i.e., the individual components are not mixed with one another. However, it is also possible for the aforementioned components to be completely or at least partially mixed with one another. If the components are at least partially mixed with one another, this means that, for example, component (C) is mixed with another optional component, while component (K) is present separately from this mixture of (C) and the further optional component.

[0033] Optional components include fillers (D), solvents (E) and / or other additives (F).

[0034] Component (C) The catalyst system according to the invention contains, as component (C), at least one catalyst containing bismuth (Bi) and zirconium (Zr) as metal components. Such catalysts are known in principle to those skilled in the art.

[0035] If desired, other metal components known to those skilled in the art may also be present besides bismuth (Bi) and zirconium (Zr). In principle, all metals known to those skilled in the art in connection with the production of polyurethane are suitable for this purpose. The other metal components can, in principle, be used in any molar ratio to bismuth (Bi) and zirconium (Zr). Manganese (Mn), zinc (Zn), iron (Fe), titanium (Ti), and / or lithium (Li) are preferably used as other metal components.

[0036] Preferably, at least one catalyst is used as component (C) which contains bismuth (Bi) and zirconium (Zr) as metal components, wherein the molar ratio of zirconium to bismuth is at least 5:1 [mol / mol], preferably from 5:1 to 50:1 [mol / mol], in particular from 7:1 to 45:1 [mol / mol].

[0037] The person skilled in the art knows how to set a molar ratio of the metal components zirconium to bismuth of at least 5:1 [mol / mol] in the catalyst. The metal components can be used in the form of salts of at least one organic acid. The metal is the cation, the organic acid the anion of the corresponding salt. Mixtures of organic acids can also be used as anion. The organic acids have hydrocarbon fragments, preferably they are (long-chain) carboxylic acids having 2 to 30 carbon atoms, more preferably having 6 to 18 carbon atoms (C6-C 18- carboxylic acids), particularly preferably having 8 to 12 carbon atoms (C8-C 12 - carboxylic acids), such as 2-ethylhexanoic acid, n-octanoic acid, or neodecanoic acid. The catalysts can also be present as an alcoholic solution or as a solution in the corresponding organic acid, for example, in the case of bi-neodecanoate. In addition, other substances may be present that serve to stabilize the compounds against traces of water or to prevent the tendency to crystallize.

[0038] For example, the catalysts according to component (C) can be prepared by mixing the corresponding salts of organic acids in the appropriate molar ratios. It is also possible for the catalyst according to component (C) to be prepared in situ in the catalyst system according to the invention.

[0039] Preferably, the catalyst is present as a salt, more preferably as Bi salt and Zr salt with C6-C 18-carboxylic acids as anion component of the respective salt, even more preferably as Bi salt and Zr salt with C8-C 12 -Carboxylic acids as anion component of the respective salt, in particular as Bi-octoate, Zr-octoate, Bio or Zr salt of the C 10 -Neodecanoic acid and / or Li or Bi salt of C9-neononanoic acid, most preferably as Bi and Zr salt of C 10 -Neodecanoic acid.

[0040] The present invention therefore also relates to a catalyst system in which component (C) is present as a salt, preferably as a Bi salt and Zr salt with C6-C 18 - Carboxylic acids as anion component of the respective salt, in particular as Bi and Zr salt of C 10 -Neodecanoic acid.

[0041] In the catalyst system according to the invention, in addition to the catalysts according to component (C) described above, it is also possible to additionally use other catalysts which are known to the person skilled in the art in connection with the production of polyurethanes but which do not fall under the definition of the catalysts according to component (C).

[0042] Component (K)

[0043] The catalyst system according to the invention contains, as component (K), at least one compound containing at least one thiol group. Such compounds are known in principle to the person skilled in the art.

[0044] Suitable for the purposes of the present invention are all compounds that contain at least one thiol or mercapto group and that can be formulated into the catalyst or polyurethane system according to the invention. A thiol group is understood here to be an SH group bonded to an organic radical, for example, an aliphatic, cycloaliphatic, or aromatic carbon radical.

[0045] Compounds with 1 to 6, especially 1 to 4, and most preferably 1 or 2, thiol groups are preferred. Compounds with one thiol group have the advantage that they do not tend to form poorly soluble complexes with component (C), and the pot life can be adjusted particularly precisely. Compounds with two thiol groups have the advantage that the mechanical properties of the polyurethane system are improved after curing.

[0046] Suitable compounds (K) with a thiol group are, for example, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercapto-1,2-propanediol, 2-mercaptotoluimidazole and 2-mercaptobenzothiazole.

[0047] Suitable compounds (K) with more than one thiol group are, for example, ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate,

[0048] Dipentaerythritol hexa(3-mercaptopropionate), 2,3-dimercapto-1,3,4-thiadiazole, or pentaerythritol tetrakis(3-mercaptopropionate). Compound (K) is preferably a polythiol compound having 2 to 6 thiol groups or a mercaptosilane. Component (K) is preferably selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate, and 3-mercaptopropyltrimethoxysilane, more preferably 3-mercaptopropyltrimethoxysilane and ethylene glycol di(3-mercaptopropionate).

[0049] The present invention therefore also relates to a catalyst system in which component (K) is a polythiol compound having 2 to 6 thiol groups or a mercaptosilane, preferably component (K) is selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate and 3-mercaptopropyltrimethoxysilane, more preferably from 3-mercaptopropyltrimethoxysilane and ethylene glycol di(3-mercaptopropionate).

[0050] The molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is < 0.99 : 1 [mol / mol].

[0051] Preferably, the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is in the range from 0.5 : 1 [mol / mol] to 0.99 : 1 [mol / mol], more preferably in the range from 0.8 : 1 [mol / mol] to 0.99 : 1 [mol / mol],

[0052] The present invention therefore also relates to a catalyst system in which the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is in the range from 0.8 : 1 [mol / mol] to 0.99 : 1 [mol / mol].

[0053] Polyurethane system

[0054] A further subject of the present invention is the polyurethane system already mentioned above, comprising at least the catalyst system according to the invention,

[0055] (A) at least one compound containing polyhydroxy groups and

[0056] (B) at least one compound containing polyisocyanate groups, where i) components (A), (B), (C) and (K) are present separately from one another or ii) are partially mixed with one another. In the polyurethane system according to the invention, it is possible for the individual components (A) to (C) and (K) and optionally also further optional components to be present separately from one another, i.e. the individual components are not mixed with one another. However, it is also possible for the aforementioned components to be partially mixed with one another. If the components are partially mixed with one another, this means that, for example, components (C) and (K) are mixed with component (A), while component (B) is present separately from this mixture of (A), (C) and (K). If appropriate, however, component (B) can also be mixed with a portion of component (C).Furthermore, the mixtures of (A), (C) and (K) as well as of (B) and (C) may additionally contain at least one optional component such as, for example, a solvent (E).

[0057] Preferably, components (C) and (K) are mixed with component (A), while component (B) is present separately from this mixture of (A), (C) and (K).

[0058] Further optional components that can be used include additional additives (F) such as stabilizers, flame retardants, pigments and UV scavengers.

[0059] Component (A)

[0060] The polyurethane system according to the invention contains, as component (A), at least one compound containing polyhydroxy groups. All compounds known to the person skilled in the art which have at least two hydroxyl groups per molecule can be used as the polyhydroxy group-containing compound according to component (A). The number of hydroxyl groups per molecule can be as high as desired; it is determined by the hydroxyl number (OH number), as described below. The compounds according to component (A) are also referred to as "polyols"; they can be oligomeric and / or polymeric. Thus, mixtures of two or more oligomeric and / or polymeric polyols (compounds containing polyhydroxy groups) can also be used as component (A).

[0061] Preferred polyhydroxy group-containing compounds (polyols) are polyether polyols, polyester polyols, polyacrylate polyols, polymethacrylate polyols, polybutadiene polyols and polycarbonate polyols, more preferably polyether polyols.

[0062] The present invention therefore also relates to a polyurethane system in which component (A) is selected from the group consisting of polyether polyols, polyester polyols, polyacrylate polyols, polymethacrylate polyols, polybutadiene polyols and polycarbonate polyols, preferably polyether polyols.

[0063] The aforementioned polymer classes, such as polyacrylate polyols or polymethacrylate polyols, can all be used as homopolymers or as copolymers (copolymers) of at least two different monomers. For the purposes of the present invention, copolymers are preferably used as polyhydroxy-containing compounds, particularly in the aforementioned polymer classes. The polymer classes are based on at least one hydroxy-containing monomer building block. Monomers (monomer building blocks) suitable for the respective polymer class are known to the person skilled in the art. Likewise, the person skilled in the art knows which specific (polymerization) processes can be used to produce the respective polymers from the corresponding monomers. Furthermore, mixtures of at least two different specific polymers of a polymer class and / or mixtures of at least one specific polymer from at least two different polymer classes may also be present.It is also possible that so-called copolymers are present, i.e. polymers that contain fragments that can be assigned to two or more polymer classes.

[0064] Particularly suitable polyether polyols, also called polyoxyalkylene polyols or oligoetherols, are those which are polymerization products of ethylene oxide, 1,2-propylene oxide, 1,2- or 2,3-butylene oxide, oxetane, tetrahydrofuran or mixtures thereof, optionally polymerized with the aid of a starter molecule having two or more active hydrogen atoms such as, for example, water, ammonia or compounds having several OH or NH groups such as, for example, 1,2-ethanediol, 1,2- and 1,3-propanediol, neopentyl glycol, diethylene glycol, triethylene glycol, the isomeric dipropylene glycols and tripropylene glycols, the isomeric butanediols, pentanediols, hexanediols, heptanediols, octanediols, nonanediols, decanediols, undecanediols, 1,3- and 1,4-cyclohexanedimethanol, Bisphenol A, hydrogenated bisphenol A, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, glycerol, aniline, and mixtures of the above-mentioned compounds.Both polyoxyalkylene polyols with a low degree of unsaturation (measured according to ASTM D-2849-69 and expressed in milliequivalent unsaturation per gram of polyol (mEq / g)), produced for example using so-called double metal cyanide complex catalysts (DMC catalysts), and polyoxyalkylene polyols with a higher degree of unsaturation, produced for example using anionic catalysts such as NaOH, KOH, CsOH or alkali metal alcoholates, can be used.

[0065] Particularly suitable are polyoxyethylene polyols and polyoxypropylene polyols, especially polyoxyethylene diols, polyoxypropylene diols, polyoxyethylene triols, and polyoxypropylene triols. Particularly suitable are polyoxyalkylene diols or polyoxyalkylene triols with a degree of unsaturation lower than 0.02 mEq / g and a molecular weight in the range of 1,000 to 15,000 g / mol, as well as polyoxyethylene diols, polyoxyethylene triols, polyoxypropylene diols, and polyoxypropylene triols with a molecular weight of 400 to 15,000 g / mol.

[0066] Also particularly suitable are so-called ethylene oxide-terminated (EO-endcapped, ethylene oxide-endcapped) polyoxypropylene polyols. The latter are special polyoxypropylene polyoxyethylene polyols which are obtained, for example, by further alkoxylating pure polyoxypropylene polyols, in particular polyoxypropylene diols and triols, after completion of the polypropoxylation reaction with ethylene oxide and thus having primary hydroxyl groups. Preference is given in this case to polyoxypropylene polyoxyethylene diols and

[0067] Polyoxypropylene polyoxyethylene triols.

[0068] Also suitable are hydroxyl group-terminated polybutadiene polyols, such as those produced by polymerization of 1,3-butadiene and allyl alcohol or by oxidation of polybutadiene, as well as their hydrogenation products.

[0069] Particularly suitable polyester polyols are polyesters which carry at least two hydroxyl groups and are produced by known processes, in particular the polycondensation of hydroxycarboxylic acids or the polycondensation of aliphatic and / or aromatic polycarboxylic acids with di- or polyhydric alcohols.

[0070] Particularly suitable are polyester polyols which are produced from di- to trihydric alcohols such as 1,2-ethanediol, diethylene glycol, 1,2-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, glycerol, 1,1,1-trimethylolpropane or mixtures of the aforementioned alcohols with organic dicarboxylic acids or their anhydrides or esters such as succinic acid, glutaric acid, adipic acid, trimethyladipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, dimer fatty acid, phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, dimethyl terephthalate, hexahydrophthalic acid, trimellitic acid and trimellitic anhydride or mixtures of the aforementioned acids, as well as polyester polyols from lactones such as for example e-caprolactone.

[0071] Polyesterdiols are particularly suitable, especially those prepared from adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, dimer fatty acid, phthalic acid, isophthalic acid, and terephthalic acid as dicarboxylic acid or from lactones such as e-caprolactone and from ethylene glycol, diethylene glycol, neopentyl glycol, 1,4-butanediol, 1,6-hexanediol, dimer fatty acid diol, and 1,4-cyclohexanedimethanol as dihydric alcohol. Particularly suitable polycarbonate polyols are those obtainable by reacting, for example, the above-mentioned alcohols used to synthesize the polyester polyols with dialkyl carbonates such as dimethyl carbonate, diaryl carbonates such as diphenyl carbonate, or phosgene. Also suitable are polycarbonates obtainable from the copolymerization of CO2 with epoxides such as ethylene oxide and propylene oxide. Polycarbonate diols, especially amorphous polycarbonate diols, are particularly suitable.

[0072] Other suitable polyols are polyacrylate polyols and polymethacrylate polyols. These two polymers or polymer classes are also referred to as poly(meth)acrylate polyols.

[0073] The optionally used poly(meth)acrylate polyols are preferably based on at least one of the monomers (monomer building blocks) listed below. More preferably, at least one of the following hydroxyl-containing monomer building blocks and, optionally, at least one of the following monomer building blocks that are not hydroxyl-containing monomer building blocks are used. Particular preference is given to using copolymers based on at least one hydroxyl-containing monomer building block and at least one monomer building block that does not contain hydroxyl groups. Examples of the corresponding monomer building blocks are listed below.

[0074] Hydroxyalkyl acrylates and / or hydroxyalkyl methacrylates are preferably used as hydroxyl-containing monomer units for the poly(meth)acrylate polyols. These are preferably selected from

[0075] 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate, 3-hydroxypropyl methacrylate,

[0076] 3-hydroxybutyl acrylate, 3-hydroxybutyl methacrylate, 4-hydroxybutyl acrylate and / or

[0077] 4-Hydroxybutyl methacrylate. Particularly preferred hydroxyl-containing monomer units are 4-hydroxybutyl acrylate and / or 4-hydroxybutyl methacrylate. The hydroxyl-containing monomer units are preferably used in amounts of 20 to 60 wt. %, based on the total monomer content of the respective polymer.

[0078] Alkyl acrylates and / or alkyl methacrylates are preferably used as further monomer building blocks for the poly(meth)acrylate polyols. These are preferably selected from methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, amyl acrylate, amyl methacrylate, hexyl acrylate, hexyl methacrylate, ethylhexyl acrylate, ethylhexyl methacrylate, 3,3,5-trimethylhexyl acrylate, 3,3,5-trimethylhexyl methacrylate, stearyl acrylate, stearyl methacrylate, lauryl acrylate,

[0079] Lauryl methacrylate, cycloalkyl acrylates, and / or cycloalkyl methacrylates. Preferred cycloalkyl (meth)acrylates are cyclopentyl acrylate, cyclopentyl methacrylate, isobornyl acrylate, isobornyl methacrylate, or, in particular, cyclohexyl acrylate and / or cyclohexyl methacrylate. If the above monomers are used, this is preferably done in amounts of 35 to 80 wt. %, based on the total amount of monomer.

[0080] Further monomer building blocks for the poly(meth)acrylate polyols that can be used are vinylaromatic hydrocarbons, such as vinyltoluene, alpha-methylstyrene or, in particular, styrene, amides or nitriles of acrylic or methacrylic acid, vinyl esters or vinyl ethers, and optionally in small amounts, preferably not more than 0.5 wt. %, acrylic and / or methacrylic acid. If vinylaromatic hydrocarbons are used as monomers, this is preferably done in amounts of 0.1 to 40 wt. %, based on the total amount of monomers. If acrylic and / or methacrylic acid is used, this is preferably done in amounts of 0.05 to 0.5 wt. %, based on the total amount of monomers used.

[0081] Furthermore, compounds containing a phosphate group may optionally be used as monomer building blocks in small amounts, preferably not more than 0.5 wt.%. These are prepared by reacting suitable hydroxyl-containing (meth)acrylic compounds by transesterification.

[0082] Such monomers are preferably represented by the general formula (1):

[0083] (R')2C = C(R')(-COO-R”-OP(O) (-OR)2) (1)

[0084] With R' = H or CH3

[0085] R“ = alkyl or alkyl-O-alkyl and

[0086] R"' = H or alkyl.

[0087] In the aforementioned radicals R', R" and R"', alkyl can be branched or unbranched and optionally cyclic. The term "alkyl" in the context of the present invention refers to saturated hydrocarbon radicals having at least one carbon atom, such as methyl (C1-alkyl), ethyl (C2-alkyl) or hexyl (C6-alkyl). The number of carbon atoms is in principle not limited; preferably there are no more than 18 carbon atoms per alkyl. If present, such monomers are preferably used in amounts of 0.05 to 0.5 wt. %, based on the total amount of monomers. Such monomers are commercially available, for example as Sipomer PAM® from the Rhodia Solvay Group.

[0088] Component (B) The polyurethane system according to the invention contains, as component (B), at least one compound containing polyisocyanate groups. All compounds known to those skilled in the art can be used as the polyisocyanate-containing compound. Suitable components (B) include, for example, known substituted or unsubstituted aromatic, aliphatic, cycloaliphatic, and / or heterocyclic polyisocyanates.

[0089] Suitable compounds containing polyisocyanate groups are in particular monomeric di- or triisocyanates, as well as oligomers, polymers and derivatives of the monomeric di- or triisocyanates, as well as any mixtures thereof.

[0090] Suitable aromatic monomeric di- or triisocyanates are in particular 2,4- and 2,6-tolylene diisocyanate and any mixtures of these isomers (TDI), 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate and any mixtures of these isomers (MDI), mixtures of MDI and MDI homologues (polymeric MDI or PMDI), 1,3- and 1,4-phenylene diisocyanate, 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI), dianisiside diisocyanate (DADI), 1,3,5-tris-(isocyanatomethyl)benzene, tris-(4-isocyanatophenyl)methane and tris-(4-isocyanatophenyl)thiophosphate.

[0091] Suitable aliphatic monomeric di- or triisocyanates are in particular 1,4-tetramethylene diisocyanate, 2-methylpentamethylene-1,5-diisocyanate, 1,6-hexamethylene diisocyanate (HDI), 2,2,4- and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate (TMDI), 1,10-decamethylene diisocyanate, 1,12-dodecamethylene diisocyanate, lysine and lysine ester diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate, 1-methyl-2,4- and -2,6-diisocyanatocyclohexane and any mixtures of these isomers (HTDI or HETDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (=isophorone diisocyanate or IPDI), perhydro-2,4'- and -4,4'-diphenylmethane diisocyanate (HMDI or H12MDI), 1,4-diisocyanato-2,2,6-trimethylcyclohexane (TMCDI), 1,3- and 1,4-bis-(isocyanatomethyl)cyclohexane, m- and p-xylylene diisocyanate (m- and p-XDI), m- and p-tetramethyl-1,3- and -1,4-xylylene diisocyanate (m- and p-TMXDI), bis-(1-isocyanato-1-methyl-ethyl)naphthalene, dimer and trimer fatty acid isocyanates such as 3,6-bis-(9-isocyanatononyl)-4,5-di-(1-heptenyl)cyclohexene (dimeryl diisocyanate) and a,a,a',a',a",a"-hexamethyl-1,3,5-mesitylene triisocyanate.

[0092] The preferred ones are MDI, TDI, HDI and IPDI.

[0093] Suitable oligomers, polymers and derivatives of the above-mentioned monomeric di- and triisocyanates are in particular derived from MDI, TDI, HDI and IPDI.Of these, commercially available types are particularly suitable, in particular HDI biurets such as Desmodur® N 100 and N 3200 (from Covestro), Tolonate® HDB and HDB-LV (from Vencorex) and Duranate® 24A-100 (from Asahi Kasei); HDI isocyanurates such as Desmodur® N 3300, N 3600 and N 3790 BA (all from Covestro), Tolonate® HDT, HDT-LV and HDT-LV2 (from Vencorex), Duranate® TPA-100 and THA-100 (from Asahi Kasei) and Coronate® HX (from Nippon Polyurethane); HDI uretdiones such as Desmodur® N 3400 (from Covestro); HDI iminooxadiazinediones such as Desmodur® XP 2410 (from Covestro); HDI allophanates such as Desmodur® VP LS 2102 (from Covestro); IPDI isocyanurates, such as in solution as Desmodur® Z 4470 (from Covestro) or in solid form as Vestanat® T1890 / 100 (from Evonik); TDI oligomers such as Desmodur® IL (from Covestro); and mixed isocyanurates based on TDI / HDI, for example as Desmodur® HL (from Covestro).Also particularly suitable are forms of MDI that are liquid at room temperature (so-called "modified MDI"), which are mixtures of MDI with MDI derivatives, such as in particular MDI carbodiimides or MDI uretonimines or MDI urethanes, known under trade names such as Desmodur® CD, Desmodur® PF, Desmodur® PC (all from Covestro) or Isonate® M 143 (from Dow), as well as mixtures of MDI and MDI homologues (polymeric MDI or PMDI), available under trade names such as Desmodur® VL, Desmodur® VL50, Desmodur® VL R10, Desmodur® VL R20, Desmodur® VH 20 N and Desmodur® VKS 20F (all from Covestro), Isonate® M 309, Voranate® M 229 and Voranate® M 580 (all from Dow) or Lupranat® M 10 R (from BASF). In practice, the aforementioned oligomeric polyisocyanates usually represent mixtures of substances with different degrees of oligomerization and / or chemical structures. They preferably have an average NCO functionality of 2.1 to 4.0.

[0094] Preferably, the polyisocyanate is selected from the group consisting of MDI, TDI, HDI and IPDI and oligomers, polymers and derivatives of the said isocyanates, as well as mixtures thereof.

[0095] The polyisocyanate preferably contains isocyanurate, iminooxadiazinedione, uretdione, biuret, allophanate, carbodiimide, uretonimine, or oxadiazinetrione groups. Particularly preferred polyisocyanates are liquid forms of MDI at room temperature. These include, in particular, so-called polymeric MDI and MDI with oligomers or derivatives thereof. The MDI content (=4,4'-, 2,4'-, or 2,2'-diphenylmethane diisocyanate and any mixtures of these isomers) of such liquid forms of MDI is in particular 50 to 95 wt. %, especially 60 to 90 wt. %.

[0096] Particularly preferred as component (B) are polymeric MDI and MDI types which are liquid at room temperature and which contain proportions of MDI carbodiimides or their adducts.

[0097] The present invention therefore also relates to a polyurethane system in which component (B) is selected from the group consisting of 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate (MDI), 2,4- and 2,6-tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate (HDI) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (= isophorone diisocyanate; IPDI) and oligomers, polymers and derivatives of the isocyanates mentioned and mixtures thereof.

[0098] Component (B) may contain portions of polyurethane polymers containing isocyanate groups. Component (B) may either comprise a separately prepared polyurethane polymer containing isocyanate groups, or the compound containing polyisocyanate groups has been mixed with at least one polyol, in particular a polyether polyol, wherein the isocyanate groups are present in a stoichiometric excess over the OH groups. In the polyurethane system according to the invention, component (B) is preferably present in an amount of 10 wt.% to 35 wt.%, in particular 15 wt.% to 30 wt.%, particularly preferably 20 wt.% to 25 wt.%, based on the total polyurethane system.

[0099] Component (D)

[0100] The polyurethane system according to the invention may contain at least one filler as component (D). Fillers as such are known to the person skilled in the art.

[0101] If present, component (D) preferably has a proportion of 0.05 to 95 wt.%, based in each case on the total polyurethane system.

[0102] Examples of suitable fillers are silica, talc, calcium oxide, aluminum oxide and aluminum hydroxide.

[0103] Component (E)

[0104] The polyurethane system according to the invention optionally contains at least one solvent as optional component (E). Solvents as such, particularly in connection with the production of polyurethane, are known to those skilled in the art. If present, the solvent (E) preferably has a proportion of 0.01 to 10 wt. %, based in each case on the total polyurethane system.

[0105] Preferably, solvents suitable for dissolving component (A) and / or component (B) are used.

[0106] Suitable solvents are those that allow sufficient solubility of component (B) and are free of isocyanate-reactive groups. Examples of such solvents are acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone, methyl isoamyl ketone, diisobutyl ketone, ethyl acetate, n-butyl acetate, ethylene glycol diacetate, butyrolactone, diethyl carbonate, propylene carbonate, ethylene carbonate, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, methylal, butylal, 1,3-dioxolane, glycerol formal, benzene, toluene, xylene, n-hexane, cyclohexane, Solventnaphtha®, 2-methoxypropyl acetate (MPA), and ethyl ethoxypropionate.

[0107] Other additives (F)

[0108] Other additives are, for example, selected from the group consisting of drying agents and plasticizers.

[0109] The present invention therefore also relates to a polyurethane system in which the polyurethane system comprises at least one further component selected from the group consisting of fillers (D), solvents (E) and further additives (F).

[0110] Use of the polyurethane system

[0111] The polyurethane system according to the invention can be advantageously used as an adhesive, as a casting compound or as a binder in composite materials, preferably in the transport and construction industries.

[0112] The invention also relates to a method for bonding a surface of a first substrate to a surface of a second substrate, comprising the steps of a) mixing at least the components (A), (B), (C) and (K) of a polyurethane system according to the invention to obtain a mixture (M), b) applying the mixture (M) to at least one of the surfaces to be bonded, c) joining the substrates to be bonded and d) curing the mixture (M) to obtain an article (A).

[0113] The two substrates can be made of the same or different materials.

[0114] Suitable substrates include, for example, glass, glass ceramics, glass mineral fiber mats, metals and alloys such as aluminum, iron, steel and non-ferrous metals, as well as surface-treated metals and alloys such as galvanized or chrome-plated metals, coated and painted substrates such as powder-coated metals or alloys and painted sheets, plastics such as polyvinyl chloride (rigid and soft PVC), acrylonitrile-butadiene-styrene copolymers (ABS), polycarbonate (PC), polyamide (PA), poly(methyl methacrylate) (PMMA), polyesters, epoxy resins, in particular epoxy-based thermosets, polyurethanes (PUR), polyoxymethylene (POM), polyolefins (PO), polyethylene (PE) or polypropylene (PP), ethylene / propylene copolymers (EPM) and ethylene / propylene / diene terpolymers (EPDM), whereby the plastics can preferably be surface-treated by means of plasma, corona or flames, fiber-reinforced Plastics such as carbon fiber reinforced plastics (CFRP),Glass-fiber reinforced plastics (GRP) and sheet molding compounds (SMC), wood, with resins, for example phenolic, melamine or epoxy resins, bonded wood materials, resin-textile composites and other so-called polymer composites, as well as concrete, mortar, bricks, gypsum and natural stones such as granite, limestone and quarry stone or marble.

[0115] Preferred substrates are a metal or a glass ceramic or a glass or a glass fiber reinforced plastic or a carbon fiber reinforced plastic or an epoxy-based thermoset.

[0116] If necessary, the substrates can be pretreated before applying the mixture (M). Such pretreatments include, in particular, physical and / or chemical cleaning processes, as well as the application of an adhesion promoter, an adhesion promoter solution, or a primer.

[0117] The bonding process described produces an article in which the composition bonds two substrates together.

[0118] The present invention therefore also relates to an article obtained by the process according to the invention.

[0119] This article is in particular a sandwich element of a lightweight structure, a building, for example a bridge, an industrial good or a consumer good, in particular a window, a rotor blade of a wind turbine or a means of transport, in particular a vehicle, preferably an automobile, a bus, a lorry, a rail vehicle or a ship, as well as an aircraft or a helicopter; or an attachment of such an article.

[0120] The invention is illustrated below using examples.

[0121] Examples

[0122] L Components

[0123] The following components are used:

[0124] Component (A1): Polyalkylene glycol obtained by alkoxylation of glycerol with an OH number of 35 mg KOH / g and a propylene oxide content of 80 to 90 wt% based on the total weight of the alkylene oxide.

[0125] Component (A2): Polypropylene glycol obtained by propoxylation of propylene oxide with an OH number of 250 mg KOH / g.

[0126] Component (A3): Polyalkylene glycol obtained by alkoxylation (with ethylene oxide and propylene oxide) of glycerol with an OH number of 158 mg KOH / g.

[0127] Component (B1): Polymeric MDI with a functionality of 2.7 and an NCO content of 31.5 wt.%.

[0128] Component (B2): Polyether-HDI prepolymer with an NCO content of 13.0 wt.%, obtained by reaction of allophanate-modified hexamethylene diisocyanate (HDI; NCO content 20 wt.%) and polypropylene glycol.

[0129] Component (C1): bismuth(III)trineodecanoate; M w= 722.75 g / mol; with 21.1 wt.% bismuth.

[0130] Component (C2): zirconium (IV) tetraneodecanoate; M w = 776.25064 g / mol; with 18.0 wt.% zirconium.

[0131] Component (C3): Zirconium(IV) isopropoxide isopropanol complex (Zr(OCH(CH3)2)4' (CH3)2CHOH)); with 23.0 wt.% zirconium.

[0132] Component (K1): 3-mercaptopropyltrimethoxysilane.

[0133] Component (K2): Ethylene glycol di(3-mercaptopropionate).

[0134] Component (D1): AEROSIL® R 202 is a polydimethylsiloxane-modified fumed silica from Evonik.

[0135] Component (D2): Alkyl silane treated aluminum trihydroxide with a

[0136] Particle size D90 of about 100 pm.

[0137] Component (F1): alkali aluminosilicate; drying agent.

[0138] Component (F2): Water scavenger for isocyanates (Luna PTSI); drying agent.

[0139] Component (F3): Non-reactive diluent, a natural oil-based

[0140] Fatty acid polyol with epoxy groups; plasticizer. IL Production of a two-component polyurethane system

[0141] First, approximately 100 g of a mixture of components (A), (C), and (K) are prepared. For this purpose, the catalysts (component (C)) and the compound containing thiol groups (component (K)) are placed in a beaker. Component (A), which has previously been mixed with 10% by weight (based on the amount of component (A)) of drying agent (component (F1)), is added. The mixture is mixed for two minutes at 1600 rpm using a Hauschild speed mixer and left to stand for approximately one hour at room temperature. Component (B) is then added, and the mixture is mixed for 20 seconds at 1600 rpm. Immediately following this, the resulting paste is subjected to a rheological test, and its pot life is determined.

[0142] The weights of the components used and molar ratios are listed in Table 1 below:

[0143] III. of a

[0144] First, a first mixture (G1) is prepared. All liquid components are placed in a speed mixer beaker, followed by the fillers (500 g in total). This mixture is stirred with a Hauschild speed mixer for 1 minute at 800 rpm and another minute at 1600 rpm. Mixing is then continued for 10 minutes under vacuum at 800 rpm.

[0145] A second mixture (G2) is then prepared. All liquid components are placed in a speed mixer beaker, followed by the fillers (200 g in total). This mixture is stirred with a Hauschild speed mixer for 1 minute at 800 rpm and another minute at 1600 rpm. Mixing is then continued for 10 minutes under vacuum at 800 rpm.

[0146] The two mixtures (G1) and (G2) are then mixed in a speed mixer for 20 seconds at 1600 rpm, resulting in an index of 115. This index defines the equivalent ratio of NCO to OH groups. An index of 115 means that there are 115 isocyanate groups for every 100 OH groups. The resulting paste is then subjected to a rheological test.

[0147] The compositions of mixtures (G1) and (G2) are listed in Table 2.

[0148] Pot life refers to the processing time of the reactive materials.

[0149] It is the time between mixing components (A) and (B) and the end of their workability, i.e., the period during which the reactive mixture can still be removed from the pot and processed. The end of the pot life is usually indicated by a significant increase in viscosity, which prevents further processing.

[0150] It is determined by means of a cup test, in which the time for which material can be removed from the cup for application is determined after the components have been mixed.

[0151] V. Determination of the A portion

[0152] The A-portion, or A-fraction, is a measure of the relationship between pot life and curing time. The A-fraction attempts to represent the viscosity measurement curve (plate-to-plate) as a number. For this purpose, the area below the curve is calculated as a percentage of the total area. A linear reaction curve would result in an A-fraction of 0.5. The smaller the value, the longer the pot life and, at the same time, the faster the reaction.

[0153] • Rheological measurements

[0154] The rheological measurements for determining the A portion are performed on a HAAKE MARS III rheometer (Thermo Fisher Scientific, USA). The freshly prepared mixtures are rheologically tested at 23 °C using a plate-to-plate (20 mm) geometry, a plate spacing of 1 mm, and a shear rate of 1 1 / s. Viscosity [Pa*s] is plotted on the y-axis against time [s] on the x-axis until a viscosity of 3000 Pa*s is reached.

[0155] • Determination of the A portion

[0156] The A-component is a measure of the ratio of pot life (ideally with a nearly constant viscosity) to curing time. The A-component attempts to represent the viscosity measurement curve as an area / number.

[0157] The area under the viscosity versus time curve is determined from the rheological measurements. For this purpose, after the intrinsic viscosity of the mixture has been reached (usually after one minute), measurements are repeated until a viscosity of 3000 Pa*s is reached. From this point, a perpendicular to the x-axis is drawn, and the area between the curve and the x-axis at the level of the intrinsic viscosity is determined. The area under the curve is then calculated as a proportion of the total area. A linear reaction would result in an A-component of 0.5. Therefore, the smallest possible value is desired, as this represents a long pot life and subsequent rapid, almost vertical curing.

[0158] The following evaluation scheme applies:

[0159] • A value < 0.05 is very good

[0160] • A value of 0.05 to 0.1 is good

[0161] • A value > 0.1 is satisfactory to poor VL results

[0162] Table 1 :

[0163] I3 to I9 are examples according to the invention, C1 and C2 are comparative examples. As can be seen from Table 1, the pot life in the polyurethane systems according to the invention (inventive examples I3 to I9) is significantly increased compared to the pot life in the polyurethane systems of comparative examples C1 and C2. Furthermore, Table 1 shows that the A portion, i.e., the measure of the ratio of pot life to full cure, in the polyurethane systems according to the invention (inventive examples I3 to I9) has better values ​​than the A portion in the polyurethane systems of comparative examples C1 and C2. Table 2:

[0164] As can be seen from Table 2, the filled two-component polyurethane system (inventive example 110) also has a good pot life to curing ratio.

Claims

Patent claims 1. Catalyst system comprising at least the following components (C) and (K) (C) at least one catalyst containing bismuth (Bi) and zirconium (Zr) as metal components, and (K) at least one compound which has at least one thiol group, wherein the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is < 0.99:1 [mol / mol].

2. Catalyst system according to claim 1, characterized in that component (K) is a polythiol compound having 2 to 6 thiol groups or a mercaptosilane, preferably component (K) is selected from the group consisting of ethylene glycol di(3-mercaptopropionate), ethylene glycol dimercaptoacetate and 3-mercaptopropyltrimethoxysilane, more preferably from 3-mercaptopropyltrimethoxysilane and ethylene glycol di(3-mercaptopropionate).

3. Catalyst system according to claim 1 or claim 2, characterized in that component (C) is present as a salt, preferably as a Bi salt and Zr salt with C 6 -C 18 -Carboxylic acids as anion component of the respective salt, in particular as Bi and Zr salt of C 10 -Neodecanoic acid.

4. Catalyst system according to one of claims 1 to 3, characterized in that the molar ratio of all thiol groups of component (K) to the sum of all metal components of component (C) is in the range from 0.8:1 [mol / mol] to 0.99:1 [mol / mol].

5. Polyurethane system at least comprising the catalyst system according to one of claims 1 to 4, (A) at least one compound containing polyhydroxy groups and (B) at least one compound containing polyisocyanate groups, wherein i) components (A), (B), (C) and (K) are present separately or ii) are partially mixed together.

6. Polyurethane system according to claim 5, characterized in that component (A) is selected from the group consisting of polyether polyols, polyester polyols, polyacrylate polyols, polymethacrylate polyols, polybutadiene polyols and polycarbonate polyols, preferably polyether polyols.

7. Polyurethane system according to claim 5 or claim 6, characterized in that component (B) is selected from the group consisting of 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate (MDI), 2,4- and 2,6-tolylene diisocyanate (TDI), 1,6-hexamethylene diisocyanate (HDI) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (= Isophorone diisocyanate; IPDI) and oligomers, polymers and derivatives of the above-mentioned isocyanates and mixtures thereof.

8. Polyurethane system according to one of claims 5 to 7, characterized in that the polyurethane system comprises at least one further component selected from the group consisting of fillers (D), solvents (E) and further additives (F).

9. Use of a polyurethane system according to one of claims 5 to 8 as an adhesive, as a casting compound or as a binder in composite materials, preferably in the transport and construction industries.

10. A method for bonding a surface of a first substrate to a surface of a second substrate, comprising the steps of a) mixing at least the components (A), (B), (C) and (K) of a polyurethane system according to one of claims 5 to 8 to obtain a mixture (M), b) applying the mixture (M) to at least one of the surfaces to be bonded, c) joining the substrates to be bonded and d) curing the mixture (M) to obtain an article (A).

11. Article (A) obtained by the method according to claim 10.

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