Compositions containing uretdione groups

Description

[0001] The present invention relates to a process for the preparation of compounds containing thioallophanate groups, to compositions containing uretdione groups, and to the use of these compositions for the production of polythiourethane plastics or coatings. Furthermore, the invention relates to coating compositions containing the compositions and to substrates coated with the coating composition.

[0002] Polyaddition products containing uretdione groups are known as crosslinker components for thermally crosslinkable polyurethane (PUR) coating and adhesive compositions. The crosslinking principle in these products is the thermal ring opening of the uretdione groups to form isocyanate groups and their reaction with a hydroxy-functional or amino-functional binder.

[0003] In practice, crosslinkers containing uretdione groups are now used almost exclusively for the production of release-free polyurethane (PUR) powder coatings (e.g. DE-A 2 312 391, DE-A 2 420 475, EP-A 0 045 994, EP-A 0 045 996, EP-A 0 045 998, EP-A 0 639 598 or EP-A 0 669 353). The use of polyurethanes containing uretdione groups as crosslinking components for solvent-based or aqueous one-component systems has also been described previously (e.g. WO 99 / 11690, WO 2014 / 053269). However, due to the comparatively low reactivity of the isocyanate groups present internally blocked in the form of uretdione structures, which in combination with polyols generally requires baking temperatures of at least 160°C, such systems have not yet been able to establish themselves on the market.

[0004] There has been no lack of attempts to lower the curing temperatures of coating systems containing uretdione groups by using suitable catalysts. For this purpose, various compounds have already been proposed, for example the organometallic catalysts known from polyurethane chemistry, such as tin(II) acetate, tin(II) octoate, tin(II) ethylcaproate, tin(II) laurate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate (e.g. EP-A 0 045 994, EP-A 0 045 998, EP-A 0 601 079, WO 91 / 07452 or DE-A 2 420 475), iron(III) chloride, zinc chloride, zinc 2-ethylcaproate and molybdenum glycolate, tertiary amines, such as triethylamine, pyridine, methylpyridine, benzyldimethylamine, N,N-endoethylenepiperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N-dimethylaminocyclohexane and N,N'-dimethylpiperazine (e.g. EP-A 0 639 598) or N,N,N'-trisubstituted amidines, in particular bicyclic amidines, such as 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7ene (DBU) (e.g. EP-A 0 803 524 or WO 2011 / 115669).

[0005] Of these catalysts, the bicyclic amidines mentioned allow the lowest baking temperatures. However, they also lead to a yellowing level that is unacceptable for many applications.

[0006] According to the teaching of EP-A 1 137 689, Lewis acid catalysts, such as the aforementioned tin or zinc compounds, are inhibited by acidic groups, such as carboxyl groups. They can therefore only exhibit their full catalytic activity in a uretdione system if the hydroxy-functional binder used is free of carboxyl groups. This can be achieved, for example, by simultaneously adding a sufficient amount of an agent reactive toward carboxyl groups, such as a carbodiimide or an epoxide.

[0007] In the absence of carboxyl groups or with the use of a compound reactive towards carboxyl groups, quaternary ammonium hydroxides and ammonium fluorides (e.g. EP-A 1 334 987), ammonium carboxylates (e.g. EP-A 1 475 399, EP-A 1 522 547), phosphonium hydroxides, alkoxides or carboxylates (e.g. WO 2005 / 085315) or metal hydroxides and alkoxides (e.g. EP-A 1 475 400) are also suitable catalysts with which the curing temperature of uretdione / polyol systems can be significantly reduced.

[0008] WO 2020 / 065438 A1 describes two-component adhesive compositions that, for the first time, use polythiols as reactants for uretdione crosslinkers. These compositions cure within a few hours after the addition of amine accelerators, such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), tris(dimethylaminomethyl)phenol, or tetramethylammonium hydroxide.

[0009] However, the disadvantage is that this catalyzed polythiol / uretdione composition cannot be used to produce visually appealing paints and coatings, as unacceptable surface defects, in particular severe flow defects and blistering, occur.

[0010] As has now surprisingly been discovered, quaternary ammonium hydroxides with longer-chain alkyl substituents on the nitrogen atom than the tetramethylammonium hydroxide used in WO 2020 / 065438 allow coating systems based on crosslinker components containing uretdione groups and polythiols to be cured at low temperatures with the formation of thioallophanate groups, whereby fully crosslinked coating films with excellent leveling and high gloss are obtained.

[0011] The present invention relates to a process for the preparation of compounds containing thioallophanate groups, comprising reacting A) at least one component having at least one uretdione group with B) at least one component having at least one thiol group in the presence of C) at least one catalyst of the general formula in which R 1< , R 2< , R 3< and R 4< independently of one another represent identical or different radicals which are saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, araliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, where R 1< and R 2< can also form heterocyclic rings having 3 to 8 carbon atoms in combination with one another together with the nitrogen atom and optionally with a further heteroatom, which can optionally be further substituted, with the proviso that at least one of the radicals R 1< to R 4< has at least two carbon atoms.

[0012] According to the invention, references to "comprising," "containing," etc., preferably mean "consisting essentially of" and most preferably "consisting of." The further embodiments mentioned in the claims and in the description can be combined as desired, unless the context clearly indicates otherwise.

[0013] An "organic compound" or "organic residue" contains at least one unit comprising a covalent carbon-hydrogen bond.

[0014] For the purposes of this document, the term "aliphatic" is defined as non-aromatic hydrocarbon groups that are saturated or unsaturated.

[0015] For the purposes of this document, the term "araliphatic" is defined as hydrocarbon residues that consist of both an aromatic and a saturated or unsaturated hydrocarbon group directly bonded to the aromatic residue.

[0016] For the purposes of this document, the term "alicyclic" or "cycloaliphatic" is defined as optionally substituted, carbocyclic, or heterocyclic compounds or moieties that are not aromatic (such as cycloalkanes, cycloalkenes, or oxa-, thia-, aza-, or thiazacycloalkanes). Specific examples include cyclohexyl groups, cyclopentyl groups, and their N- or O-heterocyclic derivatives, such as pyrimidine, pyrazine, tetrahydropyran, or tetrahydrofuran.

[0017] "At least one," as used herein, refers to 1 or more, for example, 2, 3, 4, 5, 6, 7, 8, 9, or more. In the context of components of the compounds described herein, this statement does not refer to the absolute amount of molecules, but rather to the type of component. "At least one catalyst" therefore means, for example, that only one type of compound or several different types of compounds of this type may be present, without specifying the amount of the individual compounds.

[0018] Numerical values ​​stated without decimal places refer to the full specified value with one decimal place. For example, "99%" stands for "99.0%."

[0019] Numerical ranges specified in the format "in / from x to y" include the specified values. If multiple preferred numerical ranges are specified in this format, it goes without saying that all ranges resulting from the combination of the different endpoints will also be included.

[0020] In the event that the groups or compounds are disclosed as "optionally substituted" or "substituted", suitable substituents are -F, -Cl, -Br, -I, -OH, -OCH 3 , -OCH 2 CH 3 , -O-isopropyl or -on-propyl, -OCF 3 , -CF 3 , -SC 1-6 -alkyl and / or (optionally via an attached heteroatom) a linear or branched, aliphatic and / or alicyclic structural unit having 1 to 12 carbon atoms, each acting as a replacement for a carbon-bonded hydrogen atom of the molecule in question. Preferred substituents are halogen (especially -F, -Cl), C 1-6 -alkoxy (especially methoxy and ethoxy), hydroxy, trifluoromethyl and trifluoromethoxy, each acting as a replacement for a carbon-bonded hydrogen atom of the molecule in question.

[0021] The component A) containing uretdione groups comprises any compounds A1) which may contain isocyanate-functional uretdione groups, such as are obtainable by methods known per se, for example by oligomerization of monomeric isocyanates, and / or polyaddition compounds A2) obtainable by reacting compounds A1) containing isocyanate-functional uretdione groups with alcohols and / or amines.

[0022] In a first preferred embodiment, component A) is a compound A1) containing isocyanate-functional uretdione groups and / or polyaddition compounds A2) obtainable by reacting compounds A1) containing isocyanate-functional uretdione groups with alcohols and / or amines.

[0023] Suitable isocyanates for preparing the compounds A1) containing uretdione groups are any mono-, di- and triisocyanates having aliphatically, cycloaliphatically, araliphatically and / or aromatically bound isocyanate groups which can be obtained in various ways, for example by phosgenation in the liquid or gas phase or by a phosgene-free route, such as by thermal urethane cleavage.

[0024] Preferred monoisocyanates are those in the molecular weight range 99 to 300, such as n-butyl isocyanate, n-amyl isocyanate, n-hexyl isocyanate, n-heptyl isocyanate, n-octyl isocyanate, undecyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, cetyl isocyanate, stearyl isocyanate, cyclopentyl isocyanate, cyclohexyl isocyanate, 3- or 4-methylcyclohexyl isocyanate, benzyl isocyanate, phenyl isocyanate or naphthyl isocyanate.

[0025] Preferred diisocyanates are those in the molecular weight range 140 to 400, such as: B. 1,4-diisocyanatobutane, 1,5-diisocyanatopentane (pentamethylene diisocyanate, PDI), 1,6-diisocyanatohexane (hexamethylene diisocyanate, HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1,4-diisocyanatocyclohexane, 1,3- and 1,4-bis-(isocyanatomethyl)-cyclohexane, 1,3-diisocyanato-2(4)-methylcyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 2,4'- and 4,4'-Diisocyanatodicyclohexylmethane (H 12 -MDI), 4,4'-Diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-Diisocyanato-3,3',5,5'-tetramethyldicyclohexylmethane, 4,4'-Diisocyanato-1,1'-bi(cyclohexyl), 4,4'-Diisocyanato-3,3'-dimethyl-1,1'-bi(cyclohexyl), 4,4'-Diisocyanato-2,2',5,5'-tetra-methyl-1,1'-bi(cyclohexyl), 1,8-Diisocyanato-p-menthane, 1,3-Diisocyanatoadamantane, 1,3-Dimethyl-5,7-diisocyanatoadamantane,1-Isocyanato-1-methyl-4(3)isocyanato-methylcyclohexane, bis-(isocyanatomethyl)-norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), 1,3- and 1,4-bis(2-isocyanatopropan-2-yl)benzene (tetramethylxylylene diisocyanate, TMXDI), 1,3-bis(isocyanatomethyl)-4-methylbenzene, 1,3-bis(isocyanatomethyl)-4-ethylbenzene, 1,3-bis(isocyanatomethyl)-5-methylbenzene, 1,3-bis(isocyanatomethyl)-4,5-dimethylbenzene, 1,4-bis(isocyanatomethyl)-2,5-dimethylbenzene, 1,4-bis(isocyanatomethyl)-2,3,5,6-tetramethylbenzene, 1,3-bis(isocyanatomethyl)-5-tert-butylbenzene, 1,3-bis(isocyanatomethyl)-4-chlorobenzene, 1,3-bis(isocyanatomethyl)-4,5-dichlorobenzene, 1,3-bis(isocyanatomethyl)-2,4,5,6-tetrachlorobenzene, 1,4-bis(isocyanatomethyl)-2,3,5,6-tetrachlorobenzene, 1,4-bis(isocyanatomethyl)-2,3,5,6-tetrabromobenzene, 1,4-bis(2-isocyanatoethyl)benzene and 1,4-bis(isocyanatomethyl)naphthalene, 1,2-, 1,3- and 1,4-diisocyanatobenzene (phenylene diisocyanate), 2,4- and 2,6-diisocyanatotoluene (toluylene diisocyanate,TDI), 2,3,5,6-Tetramethyl-1 ,4-diisocyanatobenzol, die isomeren Diethylphenylendiisocyanate, Diisopropylphenylendiisocyanate, Diisododecylphenylendiisocyanate und Biphenyldiisocyanate, 3,3'-Dimethoxybiphenyl-4,4'-diisocyanat, 2,2'-, 2,4'- und 4,4'-Diisocyanatodiphenylmethan (MDI), 3,3'-Dimethyldiphenylmethan-4,4'-diisocyanat, 4,4'-Diisocyanatodiphenylethan, 1,5-Diisocyanatonaphthalin (Naphthylendiisocyanat, NDI), Diphenyletherdiisocyanat, Ethylenglycoldiphenyletherdiisocyanat, Diethylenglycoldiphenyletherdiisocyanat, 1,3-Propylenglycoldiphenyletherdiisocyanat, Benzophenondiisocyanat, Triisocyanatobenzol, 2,4,6-Triisocyanatotoluol, Trimethylbenzoltriisocyanat, Diphenylmethan-2,4,4'-triisocyanat, 3-Methyldiphenylmethan-4,6,4'-triisocyanat, die isomeren Naphthalintriisocyanate und Methylnaphthalindiisocyanate, Triphenylmethantriisocyanatoder 2,4-Diisocyanato-1-[(5-isocyanato-2-methylphenyl)methyl]benzol.,

[0026] Other suitable diisocyanates can also be found, for example, in Justus Liebig's Annalen der Chemie Volume 562 (1949), pp. 75 - 136.

[0027] A particularly suitable triisocyanate is 4-isocyanatomethyl-1,8-octane diisocyanate (triisocyanatononane; TIN).

[0028] Mixtures of at least two such mono-, di- and / or triisocyanates can also be used to prepare the compounds A1) containing uretdione groups.

[0029] Monomeric diisocyanates are preferably used to produce the compounds A1) containing uretdione groups.

[0030] The use of PDI, HDI, IPDI, XDI, NBDI and / or H 12 -MDI is particularly preferred.

[0031] The preparation of the compounds A1) containing uretdione groups can be carried out by various methods which are generally based on the customary processes known from the literature for the oligomerization of simple diisocyanates, as described, for example, in J. Prakt. Chem. 336 (1994) 185 - 200, DE-A 16 70 666, DE-A 19 54 093, DE-A 24 14 413, DE-A 24 52 532, DE-A 26 41 380, DE-A 37 00 209, DE-A 39 00 053, DE-A 39 28 503, EP-A 336 205, EP-A 339 396 and EP-A 798 299.

[0032] The uretdione-containing compounds A1) can be free of isocyanate groups when monoisocyanates are used exclusively or in part. However, their preparation is preferably carried out using at least additional di- and / or triisocyanates in amounts sufficient to obtain uretdione-containing compounds A1) having an average NCO functionality of at least 1.6, preferably from 1.8 to 3.5, particularly preferably from 1.9 to 3.2, and most preferably from 2.0 to 2.7.

[0033] With average NCO functionalities of > 2.0, these compounds A1) containing isocyanate-functional uretdione groups contain, in addition to linear difunctional uretdione structures, further, at least trifunctional polyisocyanate molecules. These higher-functional components of compounds A1) are, in particular, the known derivatives of diisocyanates with isocyanurate, allophanate, biuret, urethane, and / or iminooxadiazinedione structures.

[0034] The compounds A1) containing uretdione groups are generally freed from unreacted excess monomer immediately after their preparation as described above by modifying simple monomeric mono-, di-, and / or triisocyanates using known methods, for example by thin-film distillation or extraction. They therefore generally have residual contents of monomeric diisocyanates of less than 5 wt. %, preferably less than 2 wt. %, particularly preferably less than 1 wt.

[0035] Regardless of the preparation process chosen, the compounds A1) containing uretdione groups generally have a content of uretdione structures (calculated as C 2 N 2 O 2 , molecular weight = 84) of 10 to 25 wt.%, preferably 12 to 23 wt.%, particularly preferably 14 to 20 wt.%.

[0036] In a further preferred embodiment, component A1) comprises compounds containing uretdione groups based on PDI, HDI, IPDI, XDI, NBDI and / or H 12 -MDI, which preferably have an average NCO functionality of at least 1.6 and particularly preferably have a content of uretdione structures (calculated as C 2 N 2 O 2 , molecular weight = 84) of 10 to 25 wt.%.

[0037] Also suitable as component A) of the compositions according to the invention containing uretdione groups are polyaddition compounds A2), such as can be obtained by reacting at least some of the free isocyanate groups of the above-described isocyanate-functional uretdione group-containing compounds A1) with alcohols and / or amines.

[0038] Suitable alcohols for the preparation of the polyaddition compounds A2) are, for example, simple aliphatic orcycloaliphatic monoalcohols, such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols, octanols and nonanols, n-decanol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, Cyclohexanol, the isomeric methylcyclohexanols and hydroxymethylcyclohexane, ether alcohols such as 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, 3-methoxy-1-butanol and glycerol 1,3-diethyl ether, Ester alcohols such as hydroxyethyl acetate, butyl glycolate, Ethyl lactate, glycerol diacetate or those as can be obtained by reacting the above-mentioned monoalcohols with lactones or ether alcohols as can be obtained by reacting the above-mentioned monoalcohols with alkylene oxides, in particular ethylene oxide and / or propylene oxide.

[0039] Also suitable alcohols for preparing the polyaddition compounds A2) are any at least difunctional polyols in the molecular weight range 62 to 22,000, preferably those having an average functionality of 2 to 6 and a number-average molecular weight of 62 to 18,000, particularly preferably an average functionality of 2 to 4 and a number-average molecular weight of 90 to 12,000.

[0040] Suitable polyols for the preparation of the polyaddition compounds A2) are, for example, simple polyhydric alcohols having 2 to 14, preferably 4 to 10 carbon atoms, such as: B. 1,2-ethanediol, 1,2- and 1,3-propanediol, the isomeric butanediols, pentanediols, hexanediols, heptanediols and octanediols, 1,10-decanediol, 1,12-dodecanediol, 1,2- and 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis-(4-hydroxyphenyl)propane (bisphenol A), 2,2-bis-(4-hydroxycyclohexyl)propane (perhydrobisphenol), 1,2,3-propanetriol, 1,2,4-butanetriol, 1,1,1-trimethylolethane, 1,2,6-hexanetriol, 1,1,1-trimethylolpropane (TMP), Bis-(2-hydroxyethyl)-hydroquinone, 1,2,4- and 1,3,5-trihydroxycyclohexane, 1,3,5-tris(2-hydroxyethyl)-isocyanurate, 3(4),8(9)-bis-(hydroxymethyl)-tricyclo-[5.2.1.0 2,6< ]decane, di-trimethylolpropane, 2,2-bis(hydroxymethyl)-1,3-propanediol (pentaerythritol), 2,2,6,6-tetrakis(hydroxymethyl)-4-oxa-heptane-1,7-diol (dipentaerythritol), mannitol or sorbitol, low molecular weight ether alcohols such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or dibutylene glycol or low molecular weight ester alcohols such as neopentyl glycol hydroxypivalate.

[0041] Suitable polyols for preparing the polyaddition compounds A2) also include the polymeric polyether polyols, polyester polyols, polycarbonate polyols, and / or polyacrylate polyols commonly known from polyurethane chemistry, which typically have a number-average molecular weight of 200 to 22,000, preferably of 250 to 18,000, particularly preferably of 250 to 12,000. A broad overview of suitable polymeric polyols for preparing the polyaddition compounds A2) can be found, for example, in N. Adam et al. Polyurethanes. In: Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH & Co. KgaA; 2005. URL: https: / / doi.org / 10.1002 / 14356007.a21_665.pub2.Suitable polyether polyols are, for example, those of the type mentioned in DE 26 22 951 B, column 6, line 65 to column 7, line 26, EP-A 0 978 523 page 4, line 45 to page 5, line 14 or WO 2011 / 069966, page 4, line 20 to page 5, line 23, provided they correspond to the information given above with regard to functionality and molecular weight. Particularly preferred polyether polyols are addition products of ethylene oxide and / or propylene oxide with 1,2-propanediol, 1,3-propanediol, glycerol, trimethylolpropane, ethylenediamine and / or pentaerythritol or those prepared, for example, according to Angew. Chem. 72, 927 (1960) (https: / / doi.org / 10.1002 / ange.19600722402) polytetramethylene ether glycols with number average molecular weights of 400 g / mol to 4000 g / mol obtainable by polymerization of tetrahydrofuran.

[0042] Suitable polyester polyols are, for example, those of the type mentioned in EP-A 0 978 523, page 5, lines 17 to 47, or EP-A 0 659 792, page 6, lines 32 to 45, provided they meet the above-mentioned specifications regarding functionality and molecular weight. Particularly preferred polyester polyols are condensation products of polyhydric alcohols, such as, for example, ethylenediamine dimethyl ether (EDI). B. 1,2-ethanediol, 1,2-propanediol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, perhydrobisphenol, 1,1,1-trimethylolpropane, 1,2,3-propanetriol, pentaerythritol and / or sorbitol, with sub-saturated amounts of polybasic carboxylic acids or carboxylic acid anhydrides, such as e.g.Succinic acid, adipic acid, sebacic acid, dodecanedioic acid, glutaric anhydride, maleic anhydride, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, hexahydrophthalic anhydride and / or tetrahydrophthalic anhydride, or those which are obtainable in a manner known per se from lactones, such as ε-caprolactone, and simple polyhydric alcohols, such as those mentioned above as examples, as starter molecules by ring opening.

[0043] Suitable polycarbonate polyols are, in particular, the known reaction products of dihydric alcohols, for example, those exemplified above in the list of polyhydric alcohols, with diaryl carbonates, such as diphenyl carbonate, dimethyl carbonate, or phosgene. Also suitable polycarbonate polyols are those that contain ester groups in addition to carbonate structures. These are, in particular, the known polyester carbonate diols, such as those obtained, for example, according to the teaching of DE-AS 1 770 245, by reacting dihydric alcohols with lactones, such as, in particular, ε-caprolactone, and subsequently reacting the resulting polyester diols with diphenyl or dimethyl carbonate.

[0044] Suitable polyacrylate polyols are, for example, those of the type mentioned in WO 2011 / 124710, page 10, line 32 to page 13, line 18, provided they correspond to the information given above regarding functionality and molecular weight. Particularly preferred polyacrylate polyols are polymers or copolymers of hydroxyalkyl esters of acrylic acid or methacrylic acid, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybutyl (meth)acrylate, optionally together with alkyl acrylates and / or alkyl methacrylates, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybutyl (meth)acrylate. B. methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, lauryl (meth)acrylate, styrene or other copolymerizable olefinically unsaturated monomers, such as B. acrylic acid, methacrylic acid or dimethyl maleate.

[0045] Suitable polyols are, for example, the known polyacetal polyols obtainable by reacting simple glycols, such as diethylene glycol, triethylene glycol, 4,4'-dioxethoxy-diphenyldimethylmethane (adduct of 2 mol of ethylene oxide with bisphenol A) or hexanediol, with formaldehyde or polyacetals produced by polycondensation of cyclic acetals, such as trioxane.

[0046] Further suitable polyols for preparing the polyaddition compounds A2) are, for example, the special polyols described in EP-A 0 689 556 and EP-A 0 937 110, obtainable, for example, by reacting epoxidized fatty acid esters with aliphatic or aromatic polyols with epoxide ring opening, as well as hydroxyl-containing polybutadienes.

[0047] Suitable amines for preparing the polyaddition compounds A2) are, for example, simple aliphatic or cycloaliphatic monoamines, such as methylamine, ethylamine, n-propylamine, isopropylamine, the isomeric butylamines, pentylamines, hexylamines and octylamines, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, cyclohexylamine, the isomeric methylcyclohexylamines and aminomethylcyclohexane, secondary monoamines, such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, bis(2-ethylhexyl)amine, N-methyl- and N-ethylcyclohexylamine and dicyclohexylamine.

[0048] Suitable amines also include any aliphatic and cycloaliphatic amines with at least two primary and / or secondary bonded amino groups, such as: B. 1,2-diaminoethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,2-diamino-2-methylpropane, 1,5-diaminopentane, 1,3-diamino-2,2-dimethylpropane, 1,6-diaminohexane, 1,5-diamino-2-methylpentane, 1,6-diamino-2,2,4-trimethylhexane, 1,6-diamino-2,4,4-trimethylhexane, 1,7-diaminoheptane, 1,8-diaminooctane, 2,5-diamino-2,5-dimethylhexane, 1,9-diaminononane, 2-methyl-1,8-diaminooctane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-Diaminocyclopentane, 1,2-Diaminocyclohexane, 1-Amino-3,3,5-trimethyl-5-aminomethylcyclohexane (Isophoronediamine, IPDA), 3(4)-Aminomethyl-1-methylcyclohexylamine, 1,3-Diamino-2- and / or -4-methylcyclohexane, Isopropyl-2,4- and / or 2,6-diaminocyclohexane, 1,3-Bis(aminomethyl)cyclohexane, 1,8-p-Diaminomenthane, Bis(4-aminocyclohexyl)methane, Bis(4-amino-3-methylcyclohexyl)methane, Bis(4-amino-3,5-dimethylcyclohexyl)-methan, Bis(4-amino-2,3,5-trimethylcyclohexyl)-methan, 1,1-Bis(4-aminocyclohexyl)-propan, 2,2-Bis(4-aminocyclohexyl)-propan, 1,1-Bis(4-aminocyclohexyl)-ethan, 1,1-Bis(4-aminocyclohexyl)-butan, 2,2-Bis(4-aminocyclohexyl)-butan, 1,1-Bis(4-amino-3-methylcyclohexyl)-ethan, 2,2-Bis(4-amino-3-methylcyclohexyl)-propan, 1,1-Bis(4-amino-3,5-dimethylcyclohexyl)-ethan, 2,2-Bis(4-amino-3,5-dimethylcyclohexyl)-propan, 2,2-Bis(4-amino-3,5-dimethylcyclohexyl)-butan, 2,4-Diaminodicyclohexylmethan, 4-Aminocyclohexyl-4-amino-3-methylcyclohexyl-methan, 4-Amino-3,5-dimethylcyclohexyl-4-amino-3-methylcyclohexyl-methan und 2-(4-Aminocyclohexyl)-2-(4-amino-3-methylcyclohexyl)-methan, m-Xylylendiamin, Methyliminobispropylamin, Iminobispropylamin, Bis(6-aminohexyl)-amin, N,N-Bis(3-aminopropyl)-ethylendiamin, 4-Aminomethyl-1,8-octandiamin, Bis(aminopropyl)piperazin, Aminoethylpiperazin, Diethylentriamin, Dipropylentriamin, Triethylentetramin, Tetraethylenpentamin, Pentaethylenhexamin,Heptaethyleneoctamine.,

[0049] Suitable amines also include amino-functional polyalkylene glycols, such as 1,2-bis(aminoethoxy)ethane, 1,11-diamino-3,6,9-trioxaundecane, 1,13-diamino-4,7,10-trioxatridecane and, in particular, the amine-functionalized polyalkylene glycols marketed commercially under the trade name Jeffamine®< by Huntsman Corp., having number-average molecular weights of up to 5000, preferably up to 2000, particularly preferably up to 1000.

[0050] If appropriate, sterically hindered aliphatic diamines having two secondarily bonded amino groups can also be used to prepare the polyaddition compounds A2), such as, for example, the reaction products of aliphatic and / or cycloaliphatic diamines with maleic or fumaric esters known from EP-A 0 403 921, the bisadduct of acrylonitrile with isophoronediamine obtainable according to the teaching of EP-A 1 767 559 or the hydrogenation products of Schiff bases accessible from aliphatic and / or cycloaliphatic diamines and ketones, such as, for example, diisopropyl ketone, described, for example, in DE-A 19 701 835.

[0051] Other suitable polyamines are also the polyamidoamines, polyimines and / or polyvinylamines known as crosslinking components for epoxy resins.

[0052] Finally, amino alcohols such as 2-aminoethanol, the isomeric aminopropanols and -butanols, 3-amino-1,2-propanediol and 1,3-diamino-2-propanol are also suitable for the preparation of the polyaddition compounds A2).

[0053] In the preparation of the polyaddition compounds A2) from the compounds A1) containing isocyanate-functional uretdione groups, the alcohols and / or amines mentioned are used either individually or as mixtures of at least two such alcohols and / or amines.

[0054] The preparation of the polyaddition compound A2) containing uretdione groups can be carried out by various methods, for example the processes known from the literature for the preparation of polyuretdione compositions, as described by way of example in WO 99 / 11690 and WO 2011 / 115669.

[0055] In addition to the compounds A1) containing isocyanate-functional uretdione groups, further monomeric isocyanates of the above-mentioned type and / or oligomeric polyisocyanates, preferably those with isocyanurate, biuret, iminooxadazinedione, allophanate and / or urethane structure, can optionally be used in an amount of up to 30 wt.%, based on the total weight of all reactants (comprising the compounds A1 containing isocyanate-functional uretdione groups), alcohols and / or amines).

[0056] The reaction is preferably carried out while maintaining an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 2:1 to 0.5:1, preferably of 1.5:1 to 0.7:1, particularly preferably of 1:1 to 0.9:1.

[0057] In a further preferred embodiment, the polyaddition compounds A2) are compounds which are prepared by reacting isocyanate-functional, uretdione group-containing compounds A1) with at least difunctional polyols of the molecular weight range 62 to 22,000 and optionally monoalcohols while maintaining an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 2:1 to 0.5:1.

[0058] The reaction can be carried out solvent-free or in a suitable solvent that is inert towards isocyanate groups.

[0059] Suitable solvents for the preparation of the polyaddition compounds A2) are in particular those which are inert towards the isocyanate groups of the compound A1), for example the known conventional aprotic lacquer solvents such as, for example,Ethyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, amyl acetate, 2-ethylhexyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, 1-methoxypropyl-2-acetate, 3-methoxy-n-butyl acetate, acetone, diethyl ketone, 2-butanone, 4-methyl-2-pentanone, diisobutyl ketone, cyclohexanone, cyclohexane, toluene, xylene, chlorobenzene, dichlorobenzene, white spirit, higher substituted aromatics, such as those sold under the names solvent naphtha, Solvesso ®< , Isopar ®< , Nappar ®< (Deutsche EXXON CHEMICAL GmbH, Cologne, DE) and Shellsol ®< (Deutsche Shell Chemie GmbH, Eschborn, DE), but also solvents such as propylene glycol diacetate, Diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether acetate, ethyl ethoxypropionate, propylene carbonate, N-methylpyrrolidone and N-methylcaprolactam, dioxane, tetrahydrofuran or any mixtures of such solvents.

[0060] The reaction of the isocyanate-functional uretdione-containing compounds A1) with the alcohols and / or amines to form the uretdione-containing polyaddition compounds A2) can be carried out without catalysts. However, catalysts commonly used in polyurethane chemistry can also be used to accelerate the reaction. Examples include tertiary amines, such as ethylenediamine, ethylenediamine, ethylenediamine, and ethylenediamine. B. triethylamine, tributylamine, dimethylbenzylamine, diethylbenzylamine, pyridine, methylpyridine, dicyclohexylmethylamine, dimethylcyclohexylamine, N,N,N',N'-tetramethyldiaminodiethyl ether, bis(dimethylaminopropyl)urea, N-methyl or N-ethylmorpholine, N-cocomorpholine, N-cyclohexylmorpholine, N,N,N',N'-Tetramethylethylenediamine, N,N,N',N'-Tetramethy-1,3-butanediamine, N,N,N',N'-Tetramethyl-1,6-hexanediamine, Pentamethyldiethylenetriamine, N-Methylpiperidine, N-Dimethylaminoethylpiperidine, N,N'-Dimethylpiperazine, N-Methyl-N'-dimethylaminopiperazine, 1,8-diazabicyclo(5.4.0)undec-7-ene, 1,2-dimethylimidazole, 2-methylimidazole, N,N-dimethylimidazole-β-phenylethylamine, 1,4-diazabicyclo-(2,2,2)-octane, bis-(N,N-dimethylaminoethyl)adipate; Alkanolamine compounds, such as B. triethanolamine, triisopropanolamine, N-methyl and N-ethyl diethanolamine, dimethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol, N,N',N"-tris-(dialkylaminoalkyl)hexahydrotriazines, e.g. N,N', N"-tris-(dimethylaminopropyl)-s-hexahydrotriazine and / or bis(dimethylaminoethyl)ether; metal salts, such as B. inorganic and / or organic compounds of iron, lead, bismuth, zinc, and / or tin in the usual oxidation states of the metal, for example iron(II) chloride, iron(III) chloride, bismuth(III) acetate, bismuth(III) 2-ethylhexanoate, bismuth(III) octoate, bismuth(III) neodecanoate, zinc chloride, zinc 2-ethylcaproate, tin(II) octoate, tin(II) ethylcaproate, tin(II) palmitate, dibutyltin(IV) dilaurate (DBTL), dibutyldilauryltin mercaptide, or lead octoate; amidines, such as2,3-Dimethyl-3,4,5,6-tetrahydropyrimidine; alkali metal hydroxides, such as sodium hydroxide, and alkali metal alcoholates, such as sodium methylate and potassium isopropylate, as well as alkali metal salts of long-chain fatty acids with 10 to 20 carbon atoms and optionally pendant OH groups.

[0061] Preferred catalysts are tertiary amines, bismuth and tin compounds of the type mentioned.

[0062] Regardless of the method of their preparation, the uretdione-containing polyaddition compounds A2) in solvent-free form, in a preferred embodiment, have a free isocyanate group content of less than 5 wt. %, preferably less than 2 wt. %, and particularly preferably less than 1 wt. Polyaddition compounds A2) free of isocyanate groups are very particularly preferred.

[0063] In the process according to the invention, component A) containing uretdione groups is combined with at least one component B) containing at least one thiol group as a reaction partner.

[0064] Suitable components B) also include compounds that have at least one thiol group per molecule. Component B) is preferably at least difunctional polythiols with a molecular weight range of 80 to 22,000. Suitable thiofunctional components B) are preferably polythiols, for example simple alkanethiols, such as, for example, B. Methandithiol, 1,2-ethanedithiol, 1,1-propanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,4-butanedithiol, 2,3-butanedithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,2,3-propanetrithiol, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 3,4-dimethoxybutane-1,2-dithiol or 2-methylcyclohexane-2,3-dithiol, polythiols containing thioether groups, such as. B. 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-Dimercaptomethyl-1,11-dimer-capto-3,6,9-trithiaundecane, 5,7-Dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecan, 5,6-Bis-(mercaptoethylthio)-1,10-dimercapto-3,8-dithiadecan, 4,5-Bis-(mercaptoethylthio)-1,10-dimercapto-3,8-dithiadecan, Tetrakis(mercaptomethyl)methan, 1,1,3,3-Tetrakis(mercaptomethylthio)propan, 1,1,5,5-Tetrakis(mercaptomethylthio)-3-thiapentan, 1,1,6,6-Tetrakis(mercaptomethylthio)-3,4-dithiahexan, 2-Mercaptoethylthio-1,3-dimercaptopropan, 2,3-Bis(mercaptoethylthio)-1-mercaptopropan, 2,2-Bis(mercaptomethyl)-1,3-dimercaptopropan, Bis-(mercaptomethyl)sulfid, Bis(mercaptomethyl)disulfid, Bis(mercaptoethyl)sulfid, Bis(mercapto-ethyl)disulfid, Bis(mercaptopropyl)sulfid, Bis(mercaptopropyl)disulfid, Bis(mercaptomethyl-thio)methan, Tris(mercaptomethylthio)methan, Bis(mercaptoethylthio)methan, Tris(mercapto-ethylthio)methan, Bis(mercaptopropylthio)methan, 1,2-Bis(mercaptomethylthio)ethan, 1,2-Bis-(mercaptoethylthio)ethan, 2-Mercaptoethylthio)ethan, 1,3-Bis(mercaptomethylthio)propan, 1,3-Bis(mercaptopropylthio)propan, 1,2,3-Tris(mercaptomethylthio)propan, 1,2,3-Tris(mercapto-ethylthio)propan, 1,2,3-Tris(mercaptopropylthio)propan, Tetrakis(mercaptomethylthio)methan, Tetrakis(mercaptoethylthiomethyl)methan, Tetrakis(mercaptopropylthiomethyl)methan, 2,5-Dimercapto-1,4-dithian, 2,5-Bis(mercaptomethyl)-1,4-dithian und dessen gemäß JP-A 07118263 erhältliche Oligomere, 1,5-Bis(mercaptopropyl)-1,4-dithian, 1,5-Bis(2-mercaptoethylthiomethyl)-1,4-dithian, 2-Mercaptomethyl-6-mercapto-1,4-dithiacycloheptan, 2,4,6-Trimercapto-1,3,5-trithian, 2,4,6-Trimercaptomethyl-1,3,5-trithian oder 2-(3-Bis(mercaptomethyl)-2-thiapropyl)-1,3-dithiolan, Polyesterthiole, wie z. B. Ethylenglycol-bis(2-mercaptoacetat), Ethylenglycol-bis(3-mercaptopropionat), Diethylenglycol(2-mercaptoacetat), Diethylenglycol(3-mercaptopropionat), 2,3-Dimercapto-1-propanol(3-mercaptopropionat), 3-Mercapto-1,2-propandiol-bis(2-mercaptoacetat), 3-Mercapto-1,2-propandiol-bis(3-mercaptopropionat), Trimethylolpropan-tris(2-mercaptoacetat),Trimethylolpropan-tris(3-mercaptopropionat), Trimethylolethan-tris(2-mercaptoacetat), Tri-methylolethan-tris(3-mercaptopropionat), Pentaerythrit-tetrakis(2-mercaptoacetat), Pentaerythrit-tetrakis(3-mercaptopropionat), Glycerin-tris(2-mercaptoacetat), Glycerin-tris(3-mercaptopropionat), 1,4-Cyclohexandiol-bis(2-mercaptoacetat), 1,4-Cyclohexandiol-bis(3-mercaptopropionat), Hydroxy-methylsulfid-bis(2-mercaptoacetat), Hydroxymethylsulfid-bis(3-mercaptopropionat), Hydroxyethyl-sulfid(2-mercaptoacetat), Hydroxyethylsulfid(3-mercaptopropionat), Hydroxymethyldisulfid(2-mercaptoacetat), Hydroxymethyldisulfid(3-mercaptopropionat), (2-Mercaptoethylester)thioglycolat oder Bis(2-mercaptoethylester)thiodipropionat und aromatische Thioverbindungen, wie z. B. 1,2-Dimercaptobenzol, 1,3-Dimercaptobenzol, 1,4-Dimercaptobenzol, 1,2-Bis(mercaptomethyl)benzol, 1,4-Bis(mercaptomethyl)benzol, 1,2-Bis(mercaptoethyl)benzol, 1,4-Bis(mercaptoethyl)benzol, 1,2,3-Trimercaptobenzol, 1,2,4-Trimercaptobenzol, 1,3,5-Trimercaptobenzol, 1,2,3-Tris-(mercaptomethyl)benzol, 1,2,4-Tris(mercaptomethyl)benzol, 1,3,5-Tris(mercaptomethyl)benzol, 1,2,3-Tris(mercaptoethyl)benzol, 1,3,5-Tris(mercaptoethyl)benzol, 1,2,4-Tris(mercaptoethyl)-benzol, 2,5-Toluoldithiol, 3,4-Toluoldithiol, 1,4-Naphthalindithiol, 1,5-Naphthalindithiol, 2,6-Naphthalindithiol, 2,7-Naphthalindithiol, 1,2,3,4-Tetramercaptobenzol, 1,2,3,5-Tetramercaptobenzol, 1,2,4,5-Tetramercaptobenzol, 1,2,3,4-Tetrakis(mercaptomethyl)benzol, 1,2,3,5-Tetrakis-(mercaptomethyl)benzol, 1,2,4,5-Tetrakis(mercaptomethyl)benzol, 1,2,3,4-Tetrakis(mercaptoethyl)benzol, 1,2,3,5-Tetrakis(mercaptoethyl)benzol, 1,2,4,5-Tetrakis(mercaptoethyl)benzol, 2,2'-Dimercaptobiphenyl oder 4,4'-Dimercaptobiphenyl.,

[0065] Particularly preferred thiofunctional components B) are polyether and polyester thiols of the type mentioned. Very particular preference is given to 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, trimethylolpropane tris(2-mercaptoacetate), trimethylolpropane tris(3-mercaptopropionate), pentaerythritol tetrakis(2-mercaptoacetate) and Pentaerythritol tetrakis(3-mercaptopropionate).

[0066] According to a further preferred embodiment of the process according to the invention and the composition according to the invention, at least one component A) containing at least one uretdione group and at least one component B) containing a thiol group are present in amounts such that each uretdione group of component A) accounts for 0.5 to 2.0, preferably 0.7 to 1.5, particularly preferably 0.8 to 1.2, very particularly preferably exactly one thiol group of component B).

[0067] To accelerate the reaction between the uretdione groups of component A) and the thiol groups of component B), at least one quaternary ammonium hydroxide is used as catalyst C) in the process according to the invention.

[0068] These catalysts C) are compounds of the general formula in which R 1< , R 2< , R 3< and R 4< independently of one another represent identical or different radicals which are saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, araliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, where R 1< and R 2< can also form heterocyclic rings having 3 to 8 carbon atoms in combination with one another together with the nitrogen atom and optionally with a further heteroatom, which can optionally be further substituted, with the proviso that at least one of the radicals R 1< to R 4< has at least two, preferably at least 3 carbon atoms.

[0069] Preferred catalysts C) are those of the general formula (I) in which R 1< , R 2< , R 3< and R 4< independently of one another represent identical or different radicals which are saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, araliphatic or aromatic organic radicals having 2 to 10, preferably 3 to 10, carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, where R 1< and R 2< can also form heterocyclic rings having 3 to 5 carbon atoms in combination with one another together with the nitrogen atom and optionally with a further heteroatom, which can optionally be further substituted.

[0070] Particularly preferred catalysts C) are those of the general formula (I) in which R 1< , R 2< , R 3< and R 4< independently of one another represent identical or different radicals which are a phenyl, benzyl, phenylethyl radical or saturated or unsaturated, linear or branched, aliphatic or cycloaliphatic organic radicals having 2 to 8, preferably 3 to 8 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, where R 1< and R 2< can also form heterocyclic rings having 3 to 5 carbon atoms in combination with one another together with the nitrogen atom and optionally with a further heteroatom, which can optionally be further substituted,

[0071] Examples of suitable catalysts C) of the general formula (I) are ethyltrimethylammonium hydroxide, n-hexyltrimethylammonium hydroxide, cyclohexyltrimethylammonium hydroxide, hexadecyltrimethylammonium hydroxide, phenyltrimethylammonium hydroxide, benzyltrimethylammonium hydroxide, diethyldimethylammonium hydroxide, N-ethyl-N,N-dimethylcyclohexylammonium hydroxide, methyltriethylammonium hydroxide, methyltributylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, tetradecylammonium hydroxide, tetraoctadecylammonium hydroxide, trihexyltetradecylammonium hydroxide, 2-hydroxyethyltrimethylammonium hydroxide, N,N-dimethyl-N-dodecyl-N-(2-hydroxyethyl)ammonium hydroxide, N-(2-hydroxyethyl)-N,N-dimethyl-N-(2,2'-dihydroxymethylbutyl)ammonium hydroxide and 1-(2-Hydroxyethyl)-1,4-diazabicyclo-[2.2.2]-octane hydroxide (monoadduct of ethylene oxide and water with 1,4-diazabicyclo-[2.2.2]-octane), N-ethylpyridinium hydroxide.

[0072] Preferred catalysts C) are tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, hexadecyltrimethylammonium hydroxide and benzyltrimethylammonium hydroxide, particularly preferably tetrabutylammonium hydroxide, tetrahexylammonium hydroxide and tetraoctylammonium hydroxide.

[0073] The most preferred catalyst C) is tetrabutylammonium hydroxide.

[0074] In a preferred embodiment, the catalysts C) are used in the process according to the invention either individually or as mixtures of at least two such catalysts in an amount of 0.001 to 15% by weight, preferably 0.005 to 12% by weight, particularly preferably 0.01 to 1% by weight, based on the total weight of components A) and B), excluding any solvents, auxiliaries or additives present in these components.

[0075] The process according to the invention is outstandingly suitable for the production of polythiourethane plastics and is used for this purpose. The process according to the invention is preferably used for the production of coating materials.

[0076] Therefore, compositions, preferably coating agents, containing at least one component A) containing at least one uretdione group, at least one component B) containing at least one thiol group and at least one quaternary ammonium hydroxide as catalyst C) and optionally further auxiliaries and additives, with the proviso that at least one residue of the quaternary ammonium hydroxide has at least 2, preferably at least 3, carbon atoms, are also the subject of the invention.

[0077] Depending on the activity of the catalyst used, the process according to the invention and the curing of the compositions according to the invention are generally carried out in the temperature range from 20 to 200°C, preferably from 60 to 180°C, particularly preferably from 70 to 170°C and very particularly preferably from 80 to 100°C, preferably over a period of from 1 minute to 12 hours, preferably from 30 minutes to 3 hours.

[0078] Under these conditions, the uretdione groups originally contained in component A) usually react completely to form thioallophanate groups.

[0079] The invention further relates to the use of at least one composition according to the invention for producing polythiourethane plastics. Furthermore, the invention further relates to the use of at least one composition according to the invention for producing coating materials.

[0080] Any substrates can be considered as substrates for the coatings formulated with the aid of the compositions according to the invention, such as metal, wood, glass, stone, ceramic materials, concrete, hard and flexible plastics, textiles, leather and paper, which can optionally also be provided with conventional primers before coating.

[0081] The invention further provides coating compositions comprising at least one composition according to the invention and a substrate coated with a coating composition according to the invention optionally cured under the action of heat.

[0082] The coating compositions formulated with the compositions according to the invention, to which the customary auxiliaries and additives known to the person skilled in the art from coating technology, such as solvents, UV stabilizers, antioxidants, leveling agents, rheology additives, slip additives, dyes, matting agents, flame retardants, hydrolysis inhibitors, microbicides, algicides, water scavengers, thixotropic agents, wetting agents, deaerating agents, adhesion promoters, fillers and / or pigments, can optionally be incorporated, result in films with good coating properties under the curing conditions mentioned.

[0083] The invention also relates to polythiourethane plastics, preferably coatings obtained by using the coating agents described above. Examples

[0084] Unless otherwise stated, all percentages are based on weight.

[0085] The NCO content was determined titrimetrically according to DIN EN ISO 11909:2007-05.

[0086] All viscosity measurements were performed using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219:1994-10 at a shear rate of 250 s-1.

[0087] The residual monomer contents were measured according to DIN EN ISO 10283:2007-11 using gas chromatography with an internal standard.

[0088] The compositions of the uretdione model compounds were determined by gel permeation chromatography following DIN 55672-1:2016-03 (Gel Permeation Chromatography (GPC) - Part 1: Tetrahydrofuran (THF) as Eluent), with the exception of a flow rate of 0.6 ml / min instead of 1.0 ml / min. The proportions of the different oligomers in area % obtained from the chromatograms, which were determined using software, were approximately equated to their respective proportions in wt. %.

[0089] The determination of pendulum damping according to König was carried out according to DIN EN ISO 1522:2007-04 on glass plates.

[0090] The uretdione derivatives formed during curing of the compositions according to the invention were determined using protocone-decoupled 13< C NMR spectra (recorded using CDCl 3 as the solvent on a Bruker DPX-400 instrument). The individual structural elements exhibit the following chemical shifts (in ppm): uretdione: 157.1; isocyanurate: 148.4. Solvent resistance was determined using xylene as a typical paint solvent. For this purpose, a small amount of the solvent was placed in a test tube and a cotton swab was placed over the opening to create a xylene-saturated atmosphere within the test tube. The test tube was then placed on the paint surface with the cotton swab and left there for 5 minutes. After wiping off the solvent, the film was tested for destruction / softening / loss of adhesion (0 = no change, 5 = film destroyed).Water resistance was determined using the same method, so the film was also tested for destruction / softening / loss of adhesion after exposure to water (1 hour). (0 = no change, 5 = film destroyed). Output connections Preparation of an HDI-uretdione model compound (HDI-UD1) Preparation of 1,3-bis(6-isocyanatohexyl)-1,3-diazetidine-2,4-dione

[0091] According to the process described in Example 1 of EP-A 0 789 017, 1,3-bis(6-isocyanatohexyl)-1,3-diazetidine-2,4-dione (ideal bis(6-isocyanatohexyl)uretdione) was prepared by tributylphosphine-catalyzed oligomerization of 1,6-diisocyanatohexane (HDI) and subsequent distillative workup. NCO content: 25,0 % monomeric HDI: < 0,03 % Viscosity (23°C): 28 mPas

[0092] According to gel permeation chromatography (GPC) analysis, the following composition is obtained: HDI-uretdione (n = 2): 99,2 % (according to GPC) HDI isocyanurate (n = 3): 0,4% (according to GPC) higher oligomers: 0,4 % (according to GPC) Production of the dimethyl urethane bis(6-isocyanatohexyl)uretdione (HDI-UD1)

[0093] 10 g (0.0595 eq) of the above-described HDI uretdione were dissolved in 30 ml of dichloromethane, treated with 2 g (0.0625 mol) of methanol, and stirred at 40°C under dry nitrogen until no isocyanate was detectable by IR spectroscopy after 8 h. Dichloromethane and excess methanol were then removed using a rotary evaporator. The dimethyl urethane of bis(6-isocyanatohexyl) uretdione (HDI-UD1) was obtained as a colorless solid. Uretdione group content: 21.0% (calculated as C 2 N 2 O 2 , molecular weight 84) Production of an HDI polyurethane crosslinker (HDI-UD2)

[0094] 1000 g (5.95 eq) of the ideal bis(6-isocyanatohexyl)uretdione (NCO content: 25.0%) described above were dissolved in 800 g of butyl acetate, mixed with 4.6 g (0.2 wt%) of a 10% solution of dibutyltin dilaurate (DBTL) in butyl acetate, and heated to 80°C under dry nitrogen with stirring. A mixture of 347.5 g (4.76 eq) of 2,2,4-trimethylpentane-1,3-diol and 154.7 g (1.19 eq) of 2-ethyl-1-hexanol was added dropwise to this solution over a period of 2 hours. After stirring for 16 hours at 80°C, the NCO content was <0.2%. A practically colorless solution of an HDI polyurethane crosslinker (HDI-UD2) was obtained. NCO content: 0,16 % Uretdione group content: 10,8 % (calculated as C 2 N 2 O 2 , molecular weight 84) Uretdione functionality: 5 (calculated) Solid content:: approx. 65% Viscosity (23°C): 1400 mPas Catalysts

[0095] TMAH: Tetramethylammonium hydroxide 25% in water; Sigma Aldrich Chemie GmbH, Munich, Germany.

[0096] TBAH: Tetrabutylammonium hydroxide 20% in water; Sigma Aldrich Chemie GmbH, Munich, Germany. Thiols

[0097] PETMP: Pentaerythritol tetrakis(3-mercaptopropionate); Sigma Aldrich Chemie, GmbH, Munich, DE GDMP: Ethylene glycol bis(3-mercaptopropionate); BRUNO BOCK Chemische Fabrik GmbH & Co. KG TMPMP: Trimethylolpropane tris(3-mercaptopropionate) BRUNO BOCK Chemische Fabrik GmbH & Co. KG Polyol

[0098] PETHP: Pentaerythritol tetrakis(3-hydroxypropionate), prepared by Pd-catalyzed hydrogenation of pentaerythritol tetrakis(3-benzyloxypropionate), obtained according to the procedure described in Organic Letters 2007, 9, 10, 1951-1954 and an adapted version of the procedure described in Beilstein J. Org. Chem. 2015, 11, 233-241. For this purpose, 750 mg of Pd / C were added at room temperature to a solution of 7.5 g (9.6 mmol) of the tetrabenzyl ether in 300 ml of a 1:1 mixture of chloroform / methanol. The reaction mixture was purged with argon at room temperature for 5 minutes and then reacted with hydrogen at room temperature for three days. After filtration through Celite, the reaction mixture was concentrated on a rotary evaporator and the product PETHP was purified by column chromatography (SiO 2 , ethyl acetate / methanol (95 :5)). Example 1 (inventive and comparison):

[0099] 0.37 g (3.03 meq) of PETMP was mixed with 2.10 g (2.70 meq) of the HDI polyurethane crosslinker (HDI-UD2), corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1, to form a coating composition. The mixture was dissolved in 1 ml of butyl acetate and stirred for 10 minutes. After adding 0.06 g (0.05 wt.%, based on solids) of the aqueous tetrabutylammonium hydroxide solution as a catalyst, the mixture was applied to a degreased glass plate using a coating dumbbell in a coating thickness of 150 µm.

[0100] For comparison, a coating agent was prepared using the same procedure from 61 mg (0.57 mval) of PETHP and 411 mg (0.52 mval) of the HDI polyurethane crosslinker (HDI-UD2), corresponding to an equivalent ratio of hydroxyl groups to uretdione groups of 1.1:1. This coating agent was dissolved in 0.2 ml of butyl acetate and, after addition of 0.12 mg (0.05 wt.%, based on solids) of the aqueous tetrabutylammonium hydroxide solution as catalyst, applied to a degreased glass plate using a coating dumbbell in an application layer thickness of 150 µm.

[0101] Both coatings were cured at 100°C for 60 minutes after 15 minutes of flash-off at room temperature. Using PETMP as the binder, a hard, elastic, and completely transparent coating was obtained. The reaction mixture with the tetrafunctional alcohol PETHP did not result in film formation.

[0102] The following table shows the coating properties of the cured materials: PETMP as binder (according to the invention) PETHP as a binder (comparison) Course good inhomogeneous transparency transparent not transparent Film education very good no film formation Solvent resistance very good bad Water resistance very good not water-resistant Example 2 (according to the invention):

[0103] 4.0 g (0.032 eq) of TMPMP (solids content: 100%) were mixed with 21.7 g (0.027 eq) of the HDI polyurethane crosslinker (HDI-UD2) corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1 to form a coating composition. After adding 0.06 g (0.05 wt.%, based on solids) of the aqueous tetrabutylammonium hydroxide solution as a catalyst, the coating was applied to a degreased glass plate using a coating dumbbell in a layer thickness of 150 µm. After 15 minutes of flash-off at room temperature, the coating was cured within 60 minutes at 100°C.

[0104] A smooth, colorless-transparent coating was obtained, which had a pendulum damping of 60 s and a water resistance of 0. Example 3 (according to the invention):

[0105] 4.0 g (0.038 eq) of GDMP (solids content: 100%) were mixed with 29.1 g (0.035 eq) of the HDI polyurethane crosslinker (HDI-UD2) corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1 to form a coating composition. After adding 0.3 g (0.2 wt.%, based on solids) of the aqueous tetrabutylammonium hydroxide solution as a catalyst, the coating was applied to a degreased glass plate using a coating dumbbell in a layer thickness of 150 µm. After 15 minutes of flash-off at room temperature, the coating was cured within 60 minutes at 100°C.

[0106] A smooth, colorless-transparent coating was obtained, which had a pendulum damping of 14 s and a water resistance of 0. Example 4 (comparison):

[0107] 4.0 g (0.033 eq) of PETMP were mixed with 23.2 g (0.030 eq) of the HDI polyurethane crosslinker (HDI-UD2), corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1, to form a coating composition. The mixture was dissolved in 10 ml of butyl acetate and stirred for 10 minutes. After adding 0.03 g (0.025 wt.%, based on solids) of the aqueous tetramethylammonium hydroxide solution as a catalyst, the mixture was applied to a degreased glass plate using a coating dumbbell in a coating thickness of 150 µm.

[0108] A coating with a pendulum damping of 168 s and a water resistance of 0 was obtained, but it had very poor flow and an extremely high number of bubbles. Example 5 (comparison):

[0109] 4.0 g (0.032 eq) of TMPMP were mixed with 21.7 g (0.027 eq) of the HDI polyurethane crosslinker (HDI-UD2), corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1, to form a coating composition. The mixture was dissolved in 10 ml of butyl acetate and stirred for 10 minutes. After adding 0.03 g (0.025 wt.%, based on solids) of the aqueous tetramethylammonium hydroxide solution as a catalyst, the mixture was applied to a degreased glass plate using a coating dumbbell in a coating thickness of 150 µm.

[0110] A coating with a pendulum damping of 146 s and a water resistance of 0 was obtained, but it had very poor flow and an extremely high number of bubbles and specks. Example 6 (according to the invention):

[0111] 4 g (0.033 eq) of PETMP: pentaerythritol tetrakis(3-mercaptopropionate) were mixed with 23.2 g (0.030 eq) of the HDI polyurethane crosslinker (HDI-UD2) corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1 to form a coating agent. The mixture was dissolved in 10 ml of butyl acetate and stirred for 10 min. After adding 0.68 g (0.025 wt.%, based on solids) of a 5:95 mixture (by weight) of the aqueous tetrabutylammonium hydroxide solution with dimethyl sulfoxide (DMSO) as catalyst, the mixture was applied to a degreased glass plate using a coating dumbbell in a coating thickness of 150 µm.

[0112] A smooth, colorless-transparent coating was obtained, which had a pendulum damping of 182 s and a water resistance of 0. Example 7 (according to the invention):

[0113] 4.0 g (0.032 eq) of TMPMP were mixed with 21.7 g (0.027 eq) of the HDI polyurethane crosslinker (HDI-UD2), corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1, to form a coating composition. The mixture was dissolved in 10 ml of butyl acetate and stirred for 10 min. After adding 0.64 g (0.025 wt.%, based on solids) of a 5:95 mixture (by weight) of the aqueous tetrabutylammonium hydroxide solution with DMSO as catalyst, the mixture was applied to a degreased glass plate using a coating dumbbell in a coating thickness of 150 µm.

[0114] A smooth, colorless-transparent coating was obtained, which had a pendulum damping of 142 s and a water resistance of 0. Example 8 (comparison):

[0115] 4.0 g (0.033 eq) of PETMP were mixed with 23.2 g (0.030 eq) of the HDI polyurethane crosslinker (HDI-UD2) corresponding to an equivalent ratio of thiol groups to uretdione groups of 1.1:1 to form a coating agent. The mixture was dissolved in 5 ml of butyl acetate and stirred for 10 min. 0.013 g (0.05 wt.% based on solids) of 1,8-diazabicyclo[5.4.0]undec-7ene (DBU) was added as a catalyst.

[0116] The reaction mixture gelled immediately. No coating could be applied.

Claims

1. Process for preparing compounds containing thioallophanate groups, comprising reaction of A) at least one component having at least one uretdione group with B) at least one component having at least one thiol group in the presence of C) at least one catalyst of the general formula in which R1, R2, R3 and R4 are independently identical or different radicals that are saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, araliphatic or aromatic organic radicals which have 1 to 18 carbon atoms and are substituted or unsubstituted and / or have heteroatoms in the chain, where R1 and R2, including in combination with one another, together with the nitrogen atom and optionally with any further heteroatom, may form heterocyclic rings which have 3 to 8 carbon atoms and may optionally have further substitution, with the proviso that at least one of the R1 to R4 radicals has at least two carbon atoms.

2. Process according to Claim 1, characterized in that component A) consists of isocyanate-functional compounds A1) containing uretdione groups and / or polyaddition compounds A2) obtainable by reaction of isocyanate-functional compounds A1) containing uretdione groups with alcohols and / or amines.

3. Process according to Claim 2, characterized in that component A1) consists of compounds containing uretdione groups and based on PDI, HDI, IPDI, XDI, NBDI and / or H12-MDI, preferably having an average NCO functionality of at least 1.6 and more preferably having a content of uretdione structures (calculated as C2N2O2, molecular weight = 84) of 10% to 25% by weight.

4. Process according to Claim 2 or 3, characterized in that the polyaddition compounds A2) are compounds that are prepared by reaction of isocyanate-functional compounds A1) containing uretdione groups with at least difunctional polyols in the molecular weight range from 62 to 22 000 and optionally monoalcohols, observing an equivalents ratio of isocyanate groups to isocyanate-reactive groups of 2:1 to 0.5:1.

5. Process according to any of Claims 2 to 4, characterized in that the polyaddition compounds A2) containing uretdione groups in solvent-free form have a content of free isocyanate groups of less than 5% by weight.

6. Process according to any of Claims 1 to 5, characterized in that component B) consists of at least difunctional polythiols in the molecular weight range from 80 to 22 000.

7. Process according to any of Claims 1 to 6, characterized in that components A) and B) are present in amounts such that there are 0.5 to 2.0 thiol groups of component B) for each uretdione group of component A).

8. Process according to any of Claims 1 to 7, characterized in that component C) consists of compounds of general formula (I) in which R1, R2, R3 and R4 are independently identical or different radicals that are saturated or unsaturated, linear or branched, aliphatic, cycloaliphatic, araliphatic or aromatic organic radicals which have 2 to 10 and preferably 3 to 10 carbon atoms and are substituted or unsubstituted and / or have heteroatoms in the chain, where R1 and R2, including in combination with one another, together with the nitrogen atom and optionally with any further heteroatom, may form heterocyclic rings which have 3 to 5 carbon atoms and may optionally have further substitution.

9. Process according to any of Claims 1 to 8, characterized in that catalyst C) is tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, hexadecyltrimethylammonium hydroxide and benzyltrimethylammonium hydroxide, preferably tetrabutylammonium hydroxide, tetrahexylammonium hydroxide and tetraoctylammonium hydroxide, more preferably tetrabutylammonium hydroxide.

10. Process according to any of Claims 1 to 9, characterized in that component C) is used in an amount of 0.001% to 15% by weight, based on the total weight of components A) and B), excluding any solvents, auxiliaries or additives present in these components.

11. Composition comprising at least one component A) having at least one uretdione group, at least one component B) having at least one thiol group and at least one quaternary ammonium hydroxide as catalyst C), and optionally other auxiliaries and additives, provided that at least one radical in the quaternary ammonium hydroxide has at least 2 carbon atoms.

12. Use of compositions according to Claim 11 for production of polythiourethane plastics or coating media.

13. Coating medium comprising at least one composition according to Claim 11.

14. Substrate coated with a coating medium according to Claim 13 that has optionally been cured by heating.

15. Polythiourethane plastic obtainable or produced from a composition according to Claim 11 that has optionally been cured by heating.