Compositions containing uretdione groups which crosslink at low temperatures

Abstract

The invention relates to a composition comprising A) at least one component comprising at least one uretdione group, B) at least one component comprising at least one hydroxyl group, C1) at least one catalyst comprising structural units of the general formula (I) and / or (II), wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently of one another represent identical or different radicals, i.e. saturated or unsaturated, linear or branched, aliphatic, alicyclic, araliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, wherein these radicals can also form, in combination with one another, optionally together with further heteroatoms, optionally further substituted rings having 3 to 8 carbon atoms, wherein R 3 , R 4 , R 5 and R 6 may also independently represent hydrogen, and R 7 represents hydrogen or carboxylate anion (COO ‑ ), and C2) at least one catalyst comprising at least one N,N,N'-trisubstituted amidine structure and having an amidine group content of 12.0 wt.% to 47.0 wt.% (calculated as CN2; molecular weight = 40).

Description

[0001] The present invention relates to compositions containing uretdione groups and to the use of these compositions for producing polyurethane plastics or coatings. The present invention further relates to coating compositions containing said compositions and substrates coated with said coating compositions.

[0002] Polyaddition products containing uretdione groups are known as crosslinker components for thermally crosslinkable polyurethane (PUR) coating and adhesive compositions. In these products, the crosslinking principle is the thermal ring opening of the uretdione groups to provide isocyanurate groups and their reaction with hydroxy-functional or amino-functional binders.

[0003] In practice, crosslinkers containing uretdione groups are nowadays used almost exclusively for the production of cleavage-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). Although the use of polyurethanes containing uretdione groups as crosslinker components of solvent-containing or aqueous one-component systems has also been described (e.g. WO 99 / 11690, WO 2014 / 053269), such systems have hitherto not been able to gain a foothold in the market, especially due to the relatively low reactivity of the internally blocked isocyanate groups present in the form of uretdione structures, which in combination with polyols generally require baking temperatures of at least 160° C.

[0004] There has been no shortage of attempts to lower the curing temperature of coating systems containing uretdione groups by using suitable catalysts. Various compounds have been proposed for this purpose, for example the organometallic catalysts known from polyurethane chemistry, such as tin(II) acetate, tin(II) octoate, tin(II) ethylhexanoate, tin(II) laurate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate (for example 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-ethylhexanoate and platinum glycolate, tertiary amines, such as triethylamine, pyridine, picoline, benzyldimethylamine, N,N-endoethylenepiperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N-dimethylaminocyclohexane and N,N′-dimethylpiperazine (for example 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-7-ene (DBU) (for example EP-A 0 803 524 or WO 2011 / 115669).

[0005] Among these catalysts, the bicyclic amidines listed enable the lowest baking temperatures to be achieved. However, they also lead to yellowing which is unacceptable for many areas of application.

[0006] EP-A 1 137 689 teaches that Lewis acid catalysts, such as the aforementioned tin or zinc compounds, are inhibited by acidic groups, such as carboxyl groups. They can therefore only exert their full catalytic activity in uretdione systems if the hydroxy-functional binder used does not contain carboxyl groups. This can be achieved, for example, by simultaneously adding sufficient amounts of carboxyl-reactive reagents, such as carbodiimides or epoxides.

[0007] In the absence of carboxyl groups or in the co-use of carboxyl-reactive compounds, suitable catalysts also include 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-A1 475 400), which can significantly reduce the curing temperature of uretdione systems.

[0008] The subject of the applicant's own unpublished patent application 2018PF30286 is the use of specific salts with imidazolium or dihydroimidazolium structures as catalysts for reducing the curing temperature of uretdione systems. When using these catalysts, uretdione reacts almost completely with alcohols and / or thiols at temperatures of 80° C. to 100° C. to give allophanate or thioallophanate structures, wherein optionally minor amounts of isocyanurate structures may also be formed. However, due to the very high reactivity, coatings produced using uretdione systems catalyzed in this way exhibit only moderate optical properties and, in particular, a flow that is insufficient for many applications.

[0009] It was therefore an object of the present invention to provide novel uretdione systems which likewise undergo as complete a curing as possible at very low temperatures and at the same time give rise to coatings which have significantly improved flow properties compared with the prior art.

[0010] This object is achieved by providing a catalyzed uretdione group-containing composition as described in more detail below.

[0011] The present invention is based on the surprising observation that coating systems containing uretdione groups which contain a specific catalyst combination of imidazolium salts and amidine bases undergo complete crosslinking in a very low temperature range and simultaneously provide coating films which are characterized by significantly higher hardness and, in particular, greatly improved flow compared to coating films cured using only one of these catalyst types alone.

[0012] The subject of the present invention is a composition comprising

[0013] A) at least one component comprising at least one uretdione group,

[0014] B) at least one component comprising at least one hydroxyl group,

[0015] C1) at least one catalyst comprising structural units of the general formula (I) and / or (II)

[0016] ,

[0017] in

[0018] R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently of one another represent identical or different radicals, which represent saturated or unsaturated, linear or branched, aliphatic, alicyclic, araliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, wherein these radicals can also form, in combination with one another, optionally together with further heteroatoms, optionally further substituted rings having 3 to 8 carbon atoms, wherein

[0019] R 3 , R 4 , R 5 and R 6 may also independently represent hydrogen, and

[0020] R 7 represents hydrogen or carboxylate anion (COO - ),and

[0021] C2) at least one catalyst comprising at least one N,N,N′-trisubstituted amidine structure and having an amidine group content of 12.0% to 40.0% by weight (calculated as CN2; molecular weight=40).

[0022] According to the invention, reference to "comprising", "containing" etc. preferably means "consisting essentially of", unconventionally particularly preferably means "consisting of". The further embodiments listed in the claims and the description can be combined arbitrarily, as long as the context does not clearly indicate otherwise.

[0023] The uretdione group-containing component A) is any desired optionally isocyanate-functional uretdione group-containing compound A1) obtainable by processes known per se, for example by oligomerization of monomeric isocyanates, and / or polyaddition compounds A2) obtainable by reaction of isocyanate-functional uretdione group-containing compounds A1) with alcohols and / or amines.

[0024] An "organic compound" or "organic group" comprises at least one unit containing a covalent carbon-hydrogen bond.

[0025] The term "aliphatic" is presently defined to mean a saturated or unsaturated non-aromatic hydrocarbon group.

[0026] The term "araliphatic" is presently defined to mean a hydrocarbon group consisting of an aromatic hydrocarbon group and a saturated or unsaturated hydrocarbon group directly bonded to the aromatic group.

[0027] The term "alicyclic" or "cycloaliphatic" is currently defined to mean non-aromatic, optionally substituted carbocyclic or heterocyclic compounds or units (e.g., cycloalkanes, cycloalkenes or oxa-, thia-, aza- or thiazacycloalkanes). Specific examples are cyclohexyl, cyclopentyl and their N- or O-heterocyclic derivatives, such as pyrimidine, pyrazine, tetrahydropyran or tetrahydrofuran.

[0028] Where a group or compound is disclosed as "optionally substituted" or "substituted", suitable substituents are -F, -Cl, -Br, -I, -OH, -OCH3, -OCH2CH3, -O-isopropyl or -O-n-propyl, -OCF3, -CF3, -SC 1-6 -alkyl and / or (optionally via lateral heteroatoms) straight-chain or branched aliphatic and / or alicyclic structural units having 1 to 12 carbon atoms, which in each case serve as substitutes for carbon-bonded hydrogen atoms of the molecule in question. Preferred substituents are halogen (especially -F, -Cl), C 1-6 - alkoxy (especially methoxy and ethoxy), hydroxy, trifluoromethyl and trifluoromethoxy, which in each case act as a replacement for a carbon-bonded hydrogen atom of the molecule in question.

[0029] In a first preferred embodiment, component A) is an isocyanate-functional compound A1) containing uretdione groups and / or an addition-polymerizing compound A2) obtainable by reaction of an isocyanate-functional compound A1) containing uretdione groups with an alcohol and / or an amine.

[0030] Suitable isocyanates for the production of compounds A1) containing uretdione groups are any desired monoisocyanates, diisocyanates and triisocyanates having aliphatically, cycloaliphatically, araliphatically and / or aromatically bonded isocyanate groups, which are obtainable in various ways, for example by phosgenation in the liquid or gas phase or by phosgene-free routes, for example by thermal carbamate cleavage.

[0031] Preferred monoisocyanates are those in the molecular weight range from 99 to 300, for example n-butyl isocyanate, n-pentyl isocyanate, n-hexyl isocyanate, n-heptyl isocyanate, n-octyl isocyanate, undecyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate, octadecyl isocyanate, cyclopentyl isocyanate, cyclohexyl isocyanate, 3- and 4-methylcyclohexyl isocyanate, benzyl isocyanate, phenyl isocyanate or naphthyl isocyanate.

[0032] Preferred diisocyanates are those in the molecular weight range of 140 to 400, such as 1,4-butane diisocyanate, 1,5-pentane diisocyanate (pentamethylene diisocyanate, PDI), 1,6-hexane diisocyanate (hexamethylene diisocyanate, HDI), 2-methyl-1,5-pentane diisocyanate, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- and 2,4,4-trimethyl-1,6- Hexane diisocyanate, 1,10-decane diisocyanate, 1,3- and 1,4-cyclohexane diisocyanate, 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'-dicyclohexylmethane diisocyanate (H 12-MDI), 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3'-dimethyl-1,1'-bis(cyclohexyl), 4,4'-diisocyanato-2,2',5,5'-tetramethyl-1,1'-bis(cyclohexyl), 1,8-diisocyanato-p-menthane, 1,3-adamantane diisocyanate, 1,3-dimethyl-5,7-adamantane diisocyanate, 1-isocyanato-1-methyl-4(3)-isocyanatomethylcyclohexane, bis(isocyanate) 1,3-bis(isocyanatomethyl)norbornane (NBDI), 1,3- and 1,4-bis(isocyanatomethyl)benzene (xylylene diisocyanate, XDI), 1,3- and 1,4-bis(2-isocyanatopropyl-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( 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 (toluene diisocyanate, TDI), 2,3,5,6-tetrabromobenzene, 1,4-bis(2-isocyanatoethyl)benzene and 1,4-bis(isocyanatomethyl)naphthalene, Methyl-1,4-phenylene diisocyanate, isomeric diethylphenylene diisocyanate, diisopropylphenylene diisocyanate, diisododecylphenylene diisocyanate and biphenyl diisocyanate, 3,3'-dimethoxybiphenyl 4,4'-diisocyanate, 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate (MDI), 3,3'-dimethyldiphenylmethane 4,4'-diisocyanate, 4,4'-diphenylethane diisocyanate, 1,5-diisocyanatonaphthalene (naphthalene diisocyanate, NDI), diphenyl ether diisocyanate, ethylene glycol diphenyl ether diisocyanate, diethylene glycol diphenyl ether diisocyanate, 1,3-propylene glycol diphenyl ether diisocyanate, benzophenone diisocyanate, benzene triisocyanate, 2,4,6-Toluene triisocyanate, trimethylbenzene triisocyanate, diphenylmethane 2,4,4'-triisocyanate, 3-methyldiphenylmethane 4,6,4'-triisocyanate, isomeric naphthalene triisocyanates and methylnaphthalene diisocyanates, triphenylmethane triisocyanate or 2,4-diisocyanato-1-[(5-isocyanato-2-methylphenyl)methyl]benzene.

[0033] Other diisocyanates which are likewise suitable may be found, for example, in Justus Liebigs Annalen der Chemie, volume 562 (1949), pages 75-136.

[0034] An example of a particularly suitable triisocyanate is 4-isocyanatomethyloctane 1,8-diisocyanate (nonane triisocyanate; TIN).

[0035] Mixtures of at least two such monoisocyanates, diisocyanates and / or triisocyanates can also be used for the production of the compounds A1) containing uretdione groups.

[0036] Monomeric diisocyanates are preferably used for producing the uretdione group-containing component A1).

[0037] Particularly preferably, PDI, HDI, IPDI, XDI, NBDI and / or HDI are used. 12 -MDI.

[0038] The production of the compounds A1) containing uretdione groups can be carried out by different processes, 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 41380, 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.

[0039] The uretdione group-containing compound A1) may be free of isocyanate groups in the case of complete or partial co-use of monoisocyanates. However, its production preferably also uses at least diisocyanates and / or triisocyanates in an amount such that a uretdione group-containing compound A1) having an average NCO functionality of at least 1.6, preferably 1.8 to 3.5, particularly preferably 1.9 to 3.2, very particularly preferably 2.0 to 2.7 is obtained.

[0040] At an average NCO functionality of >2.0, these isocyanate-functional compounds A1) containing uretdione groups contain not only linear difunctional uretdione structures but also additional at least trifunctional polyisocyanate molecules. These higher-functional components of the compounds A1) are in particular the known reaction products of diisocyanates having isocyanurate, allophanate, biuret, urethane and / or iminooxadiazinedione structures.

[0041] The compounds A1) containing uretdione groups are usually freed from unreacted excess monomers immediately after their above-described production by modification of simple monomeric mono-, di- and / or triisocyanates by known methods, for example by thin-film distillation or extraction. The compounds therefore usually have a residual content of monomeric diisocyanates of less than 5% by weight, preferably less than 2% by weight, particularly preferably less than 1% by weight.

[0042] Regardless of the production process selected, the uretdione group-containing compounds A1) generally have a uretdione structure content of 10% to 25% by weight, preferably 12% to 23% by weight, particularly preferably 14% to 20% by weight (calculated as C2N2O2; molecular weight = 84).

[0043] In another preferred embodiment, component A1) is based on PDI, HDI, IPDI, XDI, NBDI and / or H 12 - compounds containing uretdione groups of MDI, which preferably have an average NCO functionality of at least 1.6, particularly preferably have a uretdione structure content of 10% to 25% by weight (calculated as C2N2O2; molecular weight = 84).

[0044] Likewise suitable as uretdione group-containing component A) of the composition according to the invention are polyaddition compounds A2), such as are obtainable by reaction of at least a portion of the free isocyanate groups of the abovementioned isocyanate-functional uretdione group-containing compounds A1) with alcohols and / or amines.

[0045] Suitable alcohols for producing the polyaddition compounds A2) are, for example, simple aliphatic or cycloaliphatic 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-octadecyl alcohol, cyclohexanol, the isomeric methylcyclohexanols and hydroxymethylcyclohexanes, 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 such as are obtainable by reacting the monoalcohols listed with lactones or such as are obtainable by reacting the monoalcohols listed with alkylene oxides, in particular ethylene oxide and / or propylene oxide.

[0046] Alcohols which are likewise suitable for producing the polyaddition compounds A2) include any desired at least difunctional polyols in the molecular weight range from 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.

[0047] Suitable polyols for producing the polyaddition compounds A2) are, for example, simple polyols having 2 to 14, preferably 4 to 10, carbon atoms, for example ethane-1,2-diol, propane-1,2-diol and -1,3-diol, the isomeric butanediols, pentanediols, hexanediols, heptanediols and octanediols, nonane-1,9-diol, decan-1,10-diol, dodecane-1,12-diol, cyclohexane-1,2-diol and -1,4-diol, cyclohexane-1,4-dimethanol, 1,4-bis(2-hydroxyethoxy)benzene, 2,2-bis((2-hydroxyethoxy)benzene)-1,4-diol, 1,4 ... 4-hydroxyphenyl) propane (bisphenol A), 2,2-bis(4-hydroxycyclohexyl) propane (perhydrobisphenol), propane-1,2,3-triol, butane-1,2,4-triol, 1,1,1-trimethylolethane, hexane-1,2,6-triol, 1,1,1-trimethylolpropane (TMP), bis(2-hydroxyethyl) hydroquinone, 1,2,4- and 1,3,5-trihydroxycyclohexane, 1,3,5-tri(2-hydroxyethyl) isocyanurate, 3(4),8(9)-bis(hydroxymethyl)-tricyclo-[5.2.1.0 2,6 ] decane, di-trimethylolpropane, 2,2-bis(hydroxymethyl)propane-1,3-diol (pentaerythritol), 2,2,6,6-tetra(hydroxymethyl)-4-oxaheptane-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.

[0048] Suitable polyols for producing the polyaddition compounds A2) also include the customary polymeric polyether polyols, polyester polyols, polycarbonate polyols and / or polyacrylate polyols known from polyurethane chemistry, which generally have a number average molecular weight of 200 to 22 000, preferably 250 to 18 000, particularly preferably 250 to 12 000. A comprehensive overview of suitable polymeric polyols for producing the polyaddition compounds A2) can be found, for example, in N. Adam et al. Polyurethanes, 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 22951 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 that they comply with the above description of functionality and molecular weight. Particularly preferred polyether polyols are addition products of ethylene oxide and / or propylene oxide onto propane-1,2-diol, propane-1,3-diol, glycerol, trimethylolpropane, ethylenediamine and / or pentaerythritol or polytetramethylene ether glycols having a number-average molecular weight of 400 to 4000 g / mol, obtainable, for example, by polymerization of tetrahydrofuran according to Angew. Chem. 72, 927 (1960) (https: / / doi.org / 10.1002 / ange.19600722402).

[0049] Suitable polyester polyols include, 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 that they comply with the above statements regarding functionality and molecular weight. Particularly preferred polyester polyols are condensation products of polyols, for example ethane-1,2-diol, propane-1,2-diol, diethylene glycol, butane-1,4-diol, hexane-1,6-diol, neopentyl glycol, cyclohexane-1,4-dimethanol, cyclohexane-1,4-diol, perhydrobisphenol, 1,1,1-trimethylolpropane, propane-1,2,3-triol, pentaerythritol and / or sorbitol with substoichiometric amounts of polycarboxylic acids or carboxylic anhydrides, for example 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 as are obtainable in a manner known per se from lactones, for example ε-caprolactone, and simple polyols, for example those mentioned above by way of example as starter molecules (under ring opening).

[0050] Suitable polycarbonate polyols include in particular the reaction products of diols, such as those listed above by way of example in the list of polyols, with diaryl carbonates, such as diphenyl carbonate, dimethyl carbonate or phosgene, which are known per se. Likewise suitable polycarbonate polyols include those which contain not only carbonate structures but also ester groups. These are in particular the polyester carbonate diols known per se, which are obtainable, for example, according to the teaching of DE-AS 1 770 245, by reaction of diols with lactones, such as in particular ε-caprolactone, and subsequent reaction of the polyester diols obtained therefrom with diphenyl carbonate or dimethyl carbonate.

[0051] Suitable polyacrylate polyols include, for example, those of the type listed in WO 2011 / 124710, page 10, line 32 to page 13, line 18, provided that they comply with the description given above with respect to functionality and molecular weight. Particularly preferred polyacrylate polyols include hydroxyalkyl esters of acrylic acid or methacrylic acid, such as hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate or hydroxybutyl (meth)acrylate, optionally polymers or copolymers with alkyl acrylates and / or alkyl methacrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, lauryl (meth)acrylate, styrene or other copolymerizable ethylenically unsaturated monomers, such as acrylic acid, methacrylic acid or dimethyl maleate.

[0052] Suitable polyols also include the known polyacetal polyols obtainable, for example, by reaction of simple diols, such as diethylene glycol, triethylene glycol, 4,4'-dihydroxyethoxydiphenyldimethylmethane (adduct of 2 mol of ethylene oxide onto bisphenol A) or hexanediol with formaldehyde or polyacetals prepared by polycondensation of cyclic acetals, such as trioxane.

[0053] Suitable polyols for producing the polyaddition compounds A2) further include those described, for example, in EP-A 0 689 556 and EP-A 0 937 110, for example specific polyols obtainable by reaction of epoxidized fatty acid esters with aliphatic or aromatic polyols under epoxide ring opening, and hydroxyl-containing polybutadienes.

[0054] Suitable amines for producing the polyaddition compounds A2) include, for example, simple aliphatic and cycloaliphatic monoamines, such as methylamine, ethylamine, n-propylamine, isopropylamine, the isomeric butylamines, pentylamine, hexylamine and octylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, cyclohexylamine, the isomeric methylcyclohexylamines and aminomethylcyclohexanes, secondary monoamines, such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, bis(2-ethylhexyl)amine, N-methyl- and N-ethylcyclohexylamine, and also dicyclohexylamine.

[0055] Suitable amines also include any desired aliphatic and cycloaliphatic amines having at least two primary and / or secondary amino groups, for example 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, 1,9-diaminooctane, 2,5-diaminooctane, 1,10-diaminooctane, 1,11-diaminooctane, 1,12-diaminooctane, 1,13-diaminooctane, 1,14-diaminooctane, 1,15-diaminooctane, 1,16-diaminooctane, 1,17-diaminooctane, 1,18-diaminooctane, 1,19-diaminooctane, 1,18-diaminooctane, 1,19-diaminooctane, 1,13-diaminooctane, 1,14-diaminooctane, 1,15-diaminooctane, 1,13-diaminooctane, 1,13-diaminooctane, 1,14-diaminooctane 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-di-methylcyclohexyl)methane, bis(4-amino-2,3,5- 1,1-bis(4-aminocyclohexyl)propane, 2,2-bis(4-aminocyclohexyl)propane, 1,1-bis(4-aminocyclohexyl)ethane, 1,1-bis(4-aminocyclohexyl)butane, 2,2-bis(4-aminocyclohexyl)butane, 1,1-bis(4-amino-3-methylcyclohexyl)ethane, 2,2-bis(4-amino-3-methylcyclohexyl)propane, 1,1-bis(4-amino-3,5-dimethylcyclohexyl)ethane, 2,2-bis(4-amino-3,5-dimethylcyclohexyl)propane, 2,2-bis(4-amino-3,5-dimethylcyclohexyl)butane, 2,4-diaminodicyclohexylmethane, 4-aminocyclohexyl-4-amino-3-methylcyclohexylmethane , 4-amino-3,5-dimethylcyclohexyl-4-amino-3-methylcyclohexylmethane and 2-(4-amino-cyclohexyl)-2-(4-amino-3-methylcyclohexyl)methane, tetrahydrofurandimethylamine, 3S,3aR,6S,6aR-hexahydrofurano[3,2-b]furan-3,6-diamine, 3R,3aR,6S,6aR-hexahydrofurano[3,2-b]furan-3,6-diamine, 3S,3aR,6S,6aR-6-(aminomethyl)-hexahydrofurano[3,2-b furan-3-yl]-methylamine, meta-phenylenediamine, methyliminobispropylamine, iminobispropylamine, bis(6-aminohexyl)amine, N,N-bis(3-aminopropyl)ethylenediamine, 4-aminomethyl-1,8-Octanediamine, bis(aminopropyl)piperazine, aminoethylpiperazine, diethylenetriamine, dipropylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, heptaethyleneoctamine.

[0056] Suitable amines further include amino-functional polyalkylene glycols, for example 1,2-bis(aminoethoxy)ethane, 1,11-diamino-3,6,9-trioxaundecane, 1,13-diamino-4,7,10-trioxatridecane, in particular amine-functional polyalkylene glycols having an average molecular weight of at most 5000, preferably at most 2000, particularly preferably at most 1000, which are marketed by Huntsman Corp. under the trade name Jeffamine ® sell.

[0057] Hindered aliphatic diamines having two bound secondary amino groups may optionally also be used for the production of the polyaddition compounds A2), for example the reaction products of aliphatic and / or cycloaliphatic diamines known from EP-A 0 403 921 with maleic esters or fumaric esters, the bisadducts of acrylonitrile and isophoronediamine obtainable according to the teaching of EP-A 1 767 559 or the hydrogenation products of Schiff bases obtainable from aliphatic and / or cycloaliphatic diamines and ketones, for example diisopropyl ketone, as described, for example, in DE-A 19 701 835.

[0058] Suitable polyamines further include polyamidoamines, polyimines and / or polyvinylamines which are known as crosslinker components of epoxy resins.

[0059] Finally, amino alcohols such as 2-aminoethanol, the isomeric aminopropanols and aminobutanols, 3-aminopropane-1,2-diol and 1,3-diamino-2-propanol are also suitable for producing the polyaddition compounds A2).

[0060] In the production of the polyaddition compounds A2) from the isocyanate-functional compounds A1) containing uretdione groups, the alcohols and / or amines listed are used alone or as a mixture of at least two of such alcohols and / or amines.

[0061] The production of the polyaddition compounds A2) containing uretdione groups can be carried out by different processes, such as the processes known from the literature for producing polyuretdione compositions as described by way of example in WO 99 / 11690 and WO 2011 / 115669.

[0062] In addition to the isocyanate-functional uretdione group-containing compound A1), further monomeric isocyanates and / or oligomeric polyisocyanates of the abovementioned type, preferably those having an isocyanurate, biuret, iminooxadiazinedione, allophanate and / or urethane structure, may optionally also be used together in an amount of up to 30% by weight, based on the total weight of all reaction partners (comprising the isocyanate-functional uretdione group-containing compound A1), alcohol and / or amine.

[0063] The reaction is preferably carried out while maintaining an equivalent ratio of isocyanate groups / isocyanurate-reactive groups of 2:1 to 0.5:1, preferably 1.5:1 to 0.7:1, particularly preferably 1:1 to 0.9:1.

[0064] In another preferred embodiment, the polyaddition compound A2) is a compound prepared by reaction of an isocyanate-functional uretdione group-containing compound A1) with at least difunctional polyols and optionally monools in the molecular weight range of 62 to 22 000, observing an equivalent ratio of isocyanate groups / isocyanurate-reactive groups of 2:1 to 0.5:1.

[0065] The reaction can be carried out solvent-free or in a suitable solvent which is inert toward isocyanate groups.

[0066] Suitable solvents for producing the polyaddition compounds A2) include, in particular, those which are inert toward the isocyanate groups of component A1), for example the known customary aprotic coating solvents, 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-methoxyprop-2-yl 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, aromatic hydrocarbons with a higher degree of substitution, for example Solventnaphtha, Solvesso ® Isopar ® 、Nappar ® (Deutsche EXXONCHEMICAL GmbH, Köln, DE) and Shellsol ®(Deutsche Shell Chemie GmbH, Eschborn, DE), and solvents such as propylene glycol diacetate, diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl ether and butyl ether acetate, ethyl ethoxypropionate, propylene carbonate, N-methylpyrrolidone and N-methylcaprolactam, dioxane, tetrahydrofuran, or any desired mixtures of these solvents.

[0067] The reaction of isocyanate-functional uretdione group-containing compounds A1) with alcohols and / or amines to provide uretdione group-containing polyaddition compounds A2) can be carried out without catalysis. However, in order to accelerate the reaction, conventional catalysts known in polyurethane chemistry can also be used. Examples include tertiary amines, such as triethylamine, tributylamine, dimethylbenzylamine, diethylbenzylamine, pyridine, picoline, 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'-tetramethyl-1,3-butanediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, pentamethyldiamino ethyltriamine, 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 triethanolamine, triisopropanolamine, N-methyl- and N-ethyldiethanolamine, dimethyl ethylaminoethanol, 2-(N,N-dimethylaminoethoxy)ethanol, N,N',N''-tris(dialkylaminoalkyl)hexahydrotriazines, for example N,N',N''-tris(dimethylaminopropyl)-s-hexahydrotriazine and / or bis(dimethylaminoethyl)ether; metal salts, for example inorganic and / or organic compounds of iron, lead, bismuth, zinc and / or tin in the conventional oxidation state of the metal, for example iron(II) chloride, iron(III) chloride, bismuth(III) acetate, bismuth(III) 2-ethylhexanoate, bismuth(III) octanoate, bismuth(III) neodecanoate The invention also includes tin(III), zinc chloride, zinc 2-ethylhexanoate, tin(II) octoate, tin(II) ethylhexanoate, tin(II) palmitate, dibutyltin(IV) dilaurate (DBTL), dibutyldilauryltin mercaptan or lead octoate; amidines, for example 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine; tetraalkylammonium hydroxides, for example tetramethylammonium hydroxide; alkali metal hydroxides, for example sodium hydroxide; and alkali metal alkoxides, for example sodium methoxide and potassium isopropoxide, and alkali metal salts of long-chain fatty acids having 10 to 20 carbon atoms and optionally OH side groups.

[0068] Preferred catalysts are tertiary amines, bismuth and tin compounds of the type mentioned.

[0069] Independently of their mode of production, the uretdione group-containing polyaddition compounds A2) in a preferred embodiment, in solvent-free form, have a content of free isocyanate groups of less than 5% by weight, preferably less than 2% by weight, particularly preferably less than 1% by weight. Isocyanate-free polyaddition compounds A2) are very particularly preferred.

[0070] In the composition according to the invention, a component A) containing uretdione groups is combined with a component B) comprising at least one hydroxyl group as reaction partner.

[0071] Component B) is, for example, the compounds listed above as suitable alcohols for producing the polyaddition compounds A2), in particular at least difunctional polyols having a molecular weight range of 62 to 22,000.

[0072] Suitable hydroxy-functional components B) are preferably the abovementioned simple polyols having 2 to 14 carbon atoms, low molecular weight ether and ester alcohols and also the customary polymeric polyether polyols, polyester polyols, polycarbonate polyols and / or polyacrylate polyols known from polyurethane chemistry.

[0073] In a further preferred embodiment, the at least one component A) comprising at least one uretdione group and the at least one component B) comprising at least one hydroxyl group are used in the composition according to the invention in such amounts that for each uretdione group of component A), there are 0.5 to 2.0, preferably 0.7 to 1.5, particularly preferably 0.8 to 1.2 and very particularly preferably exactly one hydroxyl group of component B).

[0074] To accelerate the reaction between the uretdione groups of component A) and the hydroxyl groups of component B), a combination of at least one salt-type catalyst C1) comprising imidazolium and / or imidazolinium cations and at least one catalyst C2) comprising an N,N,N′-trisubstituted amidine structure is used in the composition according to the invention.

[0075] Compounds suitable as catalysts C1) are known as ionic liquids of the imidazolium and imidazolinium type and are used, for example, as solvents in chemical syntheses. Their production processes are described, for example, in Chem. Rev. 99, 8, 2071-2084 and WO 2005 / 070896.

[0076] The catalyst C1) is a salt compound containing a structural unit of the general formula (I) or (II),

[0077] ,

[0078] in

[0079] R 1 , R 2 , R3 , R 4 , R 5 and R 6 independently of one another represent identical or different radicals which represent saturated or unsaturated, linear or branched, aliphatic, alicyclic, araliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, wherein these radicals can also form, in combination with one another, optionally together with further heteroatoms, rings having 3 to 8 carbon atoms which may be optionally further substituted,

[0080] R 3 , R 4 , R 5 and R 6 may also independently represent hydrogen, and

[0081] R 7 represents hydrogen or carboxylate anion (COO - ).

[0082] Preferred catalysts C1) are salt compounds containing structural units of the general formula (I) or (II), wherein

[0083] R 1 and R 2 independently of one another represent identical or different radicals which represent saturated or unsaturated, linear or branched, aliphatic, alicyclic, araliphatic or aromatic organic radicals having 1 to 12 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain,

[0084] R 3 , R 4 , R 5 and R 6 represents hydrogen, and

[0085] R 7 represents hydrogen or carboxylate anion (COO - ).

[0086] Particularly preferred catalysts C1) are salt compounds containing structural units of the general formula (I) or (II), wherein

[0087] R 1 and R 2 independently represent the same or different groups, which represent saturated or unsaturated, linear or branched aliphatic organic groups having 1 to 12 carbon atoms,

[0088] R 3 , R 4 , R 5 and R 6 represents hydrogen, and

[0089] R 7 represents hydrogen or carboxylate anion (COO - ).

[0090] Suitable catalysts of the general formula (I) include, for example, 1,3-dimethylimidazolium, 1-methyl-3-ethylimidazolium, 1-methyl-3-propylimidazolium, 1-methyl-3-butylimidazolium, 1-methyl-3-pentylimidazolium, 1-methyl-3-hexylimidazolium, 1-methyl-3-octylimidazolium, 1-methyl-3-nonylimidazolium, 1-methyl-3-decylimidazolium, 1-decyl-3-methylimidazolium, 1-methyl-3-benzylimidazolium, 1-methyl-3-(3 -phenylpropyl)imidazolium, 1-ethyl-3-methylimidazolium (EMIM), 1-isopropyl-3-methylimidazolium, 1-butyl-3-methylimidazolium (BMIM), 1-hexyl-3-methylimidazolium, 1-heptyl-3-methylimidazolium, 1-(2-ethyl)hexyl-3-methylimidazolium (OMIM), 1,3-bis(tert-butyl)imidazolium, 1,3-bis(2,4,6-trimethylphenyl)imidazolium or 1,3-dimethylbenzimidazolium cations.

[0091] Suitable catalysts of the general formula (II) include, for example, those containing 1,3-dimethylimidazolinium, 1-ethyl-3-methylimidazolinium, 1-butyl-3-methylimidazolinium, 1,3-bis-(2,6-diisopropylphenyl)imidazolinium or 1,3-bis(2,4,6-trimethylphenyl)imidazolinium, 1-(1-adamantyl)-3-(2,4,6-trimethylphenyl)imidazolinium, 1,3-diphenyl-4,4,5,5-tetramethylimidazolinium, 1,3-di-o-tolyl-4,4,5,5-tetramethylimidazolinium cations.

[0092] As counterions to the imidazolium and imidazolinium cations, the catalyst C1) present in the composition according to the invention contains any desired inorganic and / or organic anions, for example halide, sulfate, hydroxysulfate, sulfite, nitrate, carbonate, bicarbonate, arylsulfonate, alkylsulfonate, trifluoromethylsulfonate, alkylsulfonate, phosphate, dialkylphosphate, hexafluorophosphate, trifluoromethylborate, tetrafluoroborate, bis(trifluoromethylsulfonyl)imide, dicyanamide and / or carboxylate anions.

[0093] The counterions of the imidazolium and imidazolinium cations may also be additionally R 7 The carboxylate group (COO - ), wherein the catalyst C1) in this case is in the form of a zwitterionic structure.

[0094] Suitable catalysts C1) for the composition according to the invention include, for example, 1,3-dimethylimidazolium chloride, 1,3-dimethylimidazolium 2-formate, 1,3-dimethylimidazolium dimethylphosphate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium iodide, 1-ethyl-3-methylimidazolium nitrate, 1-ethyl-3-methylimidazolium hydrogen carbonate, 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium trifluoro(trifluoromethyl)borate, 1-ethyl-3-methylimidazolium hydrogensulfate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium dicyanoacrylate, Amine salts, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium 2-formate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium pivalate imidazolium, (L)-(+)-1-ethyl-3-methylimidazolium lactate, 1-methyl-3-propylimidazolium iodide, 1,3-diisopropyl-4,5-dimethylimidazolium 2-formate, 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium iodide, 1-butyl-3-methylimidazolium trifluoromethanesulfonate 1-butyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium n-octyl sulfate, 1-butyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium trifluoro(trifluoromethyl)borate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium dibutyl phosphate, 1-butyl-3- Methylimidazolium, 1-butyl-3-methylimidazolium 2-carboxylate, 1-butyl-3-methylimidazolium acetate, butyl-3-methylimidazolium pivalate, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, bis(tert-butyl)imidazolium 2-carboxylate, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium bromide, 1-tetrafluoroborate 1-Hexyl-3-methylimidazolium, 1-Hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-Hexyl-3-methylimidazolium hexafluorophosphate, 1-Methyl-3-n-octylimidazolium bromide, 1-Methyl-3-n-octylimidazolium chloride, 1-Methyl-3-n-octylimidazolium hexafluorophosphate, 1-Decyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide 1,3-Dimethylimidazolinium chloride, 1,3-Dimethylimidazolinium 2-formate, 1,3-Dimethylimidazolinium acetate, 1-Ethyl-3-methylimidazolinium chloride, 1-Ethyl-3-methylimidazolinium 2-formate, 1-Ethyl-3-methylimidazolinium acetate, 1-Butyl-3-methylimidazolinium 2-formate, 1,3-Bis(2,6-diisopropylphenyl)imidazolinium or 1,3-bis(2,4,6-trimethylphenyl)imidazolinium-1-(1-adamantyl)-3-(2,4,6-trimethylphenyl)imidazolinium chloride and / or 1,3-diphenyl-4,4,5,5-tetramethylimidazolinium chloride.

[0095] Particularly preferred catalysts C1) are imidazolium salts of the types listed with a carboxylate anion, very particularly preferably 1,3-dimethylimidazolium 2-carboxylate, 1-ethyl-3-methylimidazolium 2-carboxylate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium pivalate, 1-butyl-3-methylimidazolium 2-carboxylate and / or 1-butyl-3-methylimidazolium acetate.

[0096] Catalysts C2) are compounds containing N,N,N'-trisubstituted amidine structures with an amidine group content of 12.0% to 47.0% by weight, preferably 15.0% to 40.0% by weight (calculated as CN2; molecular weight = 40). Suitable catalysts C2) are any desired amidine bases with optionally substituted alkyl, aralkyl or aryl groups, where the CN double bond of the amidine structure can be part of an open-chain molecule, a component of a cyclic or bicyclic ring system, or can be arranged exocyclically on the ring system, or any desired mixtures of these amidines.

[0097] Suitable amidine catalysts C2) in which the CN double bond is part of an open-chain molecule include, for example, N,N-dimethyl-N'-phenylformamidine or N,N,N'-trimethylformamidine, the production of which is described, for example, in Chem Ber. 98, 1078 (1965). Examples of suitable amidines C2) in which the CN double bond is a component of a ring system include: 2-methyltetrahydropyrimidines substituted in the 1-position, as obtainable, for example, according to the teaching of DE-A 2 439 550 by reaction of N-monosubstituted 1,3-propylenediamines with acetoacetic acid derivatives, or monocyclic amidine bases, as obtainable, for example, according to DE-A 1 078 568, by reaction of carbamoyl chlorides formed from secondary amines with lactams. Suitable catalysts C2) in which the CN double bond is arranged exocyclically on the ring system include, for example, imines of N-alkyl-substituted lactams, such as 2-methylimino-1-methylpyrrolidone, the production of which is described, for example, in Chem. Ber. 101, 3002 (1968).

[0098] However, preferred catalysts C2) are bicyclic catalysts of the general formula (III) containing an N,N,N'-trisubstituted amidine structure

[0099]

[0100] wherein m is an integer from 1 to 9, preferably from 1 to 3, and n is an integer from 1 to 3, preferably from 2.

[0101] The production of such bicyclic amidines is known and is described, for example, in DE-A 1545855 or EP-A 662 476. Particularly preferred catalysts C2) for the process according to the invention are 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).

[0102] In the composition according to the invention, the catalyst C1) is always used together with the catalyst C2), wherein the catalyst C1) and the catalyst C2) can each be a single compound C1) and C2) of the above-mentioned type, or each be any desired mixture of at least two such catalysts C1) or C2). The amount of the catalysts C1) and C2) in the composition according to the invention is here in each case from 0.0005% to 5% by weight, preferably from 0.0025% to 4% by weight, particularly preferably from 0.005% to 2.5% by weight, very particularly preferably from 0.05% to 0.5% for the individual catalyst components C1) and C2), based on the total weight of the components A) and B) (excluding solvents, auxiliaries or additives optionally present in these components).

[0103] Accordingly, the total amount of catalysts C1) and C2) in the composition according to the invention may be 0.001% to 10% by weight, preferably 0.005% to 8% by weight, particularly preferably 0.01% to 5% by weight and very particularly preferably 0.1% to 1%, based on the total weight of components A) and B) (excluding any solvents, auxiliaries or additives present in these components).

[0104] The compositions according to the invention are particularly suitable for the production of polyurethane plastics and are used therefor. The compositions according to the invention are preferably used for the production of coating compositions.

[0105] The present invention therefore also provides a coating composition comprising at least one component A comprising at least one uretdione group, at least one component B comprising at least one hydroxyl group, at least one catalyst C1) having an imidazolium or imidazolinium structure and at least one catalyst C2) having an amidine structure and optionally further auxiliaries and additives.

[0106] The curing of the composition according to the invention is carried out, depending on the activity of the catalyst used, generally in a temperature range of 20° C. to 200° C., preferably 60° C. to 180° C., particularly preferably 70° C. to 160° C., very particularly preferably 80° C. to 140° C., for a period of preferably 1 minute to 12 hours, preferably 10 minutes to 3 hours.

[0107] Under these conditions, the uretdione groups initially contained in component A) generally react completely to form allophanate groups and optionally isocyanurate groups.

[0108] A further subject of the present invention is the use of at least one composition according to the invention for producing polyurethane plastics. Furthermore, a further subject of the present invention is the use of at least one composition according to the invention for producing coating compositions.

[0109] Substrates envisaged for coatings formulated with the compositions according to the invention include any desired substrates, for example metal, wood, glass, stone, ceramic materials, concrete, hard and soft plastics, textiles, leather and paper, which may optionally also be provided with conventional primers before coating.

[0110] The present invention further provides a coating composition 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.

[0111] The coating compositions formulated with the compositions according to the invention provide films having good coating technical properties under the listed curing conditions, to which compositions customary auxiliary and additive substances known to the person skilled in the art from coating technology, such as solvents, UV stabilizers, antioxidants, flow control agents, rheological additives, slip additives, dyes, matting agents, flame retardants, hydrolysis inhibitors, microbicides, algaecides, water scavengers, thixotropic agents, wetting agents, deaerators, adhesion promoters, fillers and / or pigments, may optionally be added.

[0112] The invention also provides polyurethane plastics, preferably coatings, obtainable using the above-described coating compositions.

[0113] Example

[0114] Unless stated otherwise, all percentage data are by weight.

[0115] The NCO content is determined titrimetrically in accordance with DIN EN ISO 11909:2007-05.

[0116] All viscosity measurements were performed with a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219:1994-10 at 250 s -1 The experiment was carried out at a shear rate of 5.

[0117] The residual monomer content is measured by gas chromatography using an internal standard in accordance with DIN EN ISO 10283:2007-11.

[0118] The composition of the HDI-uretdione polyisocyanates was determined by gel permeation chromatography based on DIN 55672-1:2016-03 (Gel Permeation Chromatography (GPC) – Part 1: Tetrahydrofuran (THF) as eluent), with the modification that operation was performed with a flow rate of 0.6 ml / min instead of 1.0 ml / min. The proportions of the various oligomers from the chromatograms in area % determined with the aid of the software were in each case approximately equivalent to the proportions in weight %.

[0119] The König pendulum damping was determined on glass panels in accordance with DIN EN ISO 1522:2007-04.

[0120] The microhardness (surface hardness / Martens hardness at a test force of 0.6 mN) and the elastic deformation component of the coating films were measured using a Fischerscope HM 2000 instrument according to DIN EN ISO 14577-1:2015-11.

[0121] The appearance measurements were carried out using a "Wave Scan" instrument from BYK-Gardner GmbH, Geretsried, DE. The values ​​for Dullness (the smaller the value, the less matte) and Distinctness of Image DOI (the larger the value, the greater the brightness) are shown in each case as an average from 5 individual measurements.

[0122] Solvent resistance is determined using xylene as a typical coating solvent. For this purpose, a small amount of solvent is added to a test tube and a cotton ball is placed at the opening to create an atmosphere saturated with xylene in the test tube. The test tube is then placed on the coating surface with the cotton ball and left there for 5 minutes. Once the solvent has been wiped off, the film is checked for damage / softening / loss of adhesion. (0 = no change, 5 = film damage).

[0123] Starting compound

[0124] Production of HDI polyuretdione crosslinking agent

[0125] 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 (ideally bis(6-isocyanatohexyl)uretdione) is produced by tributylphosphine-catalyzed oligomerization of 1,6-hexane diisocyanate (HDI) and subsequent distillative work-up.

[0126] NCO content: 25.0%

[0127] Monomer HDI: < 0.03%

[0128] Viscosity (23°C): 28 mPas

[0129] According to gel permeation chromatography (GPC), the following composition exists:

[0130] HDI uretdione (n = 2): 99.2% (according to GPC)

[0131] HDI isocyanurate (n = 3): 0.4% (according to GPC)

[0132] Higher oligomers: 0.4% (according to GPC).

[0133] 1000 g (5.95 eq.) of this desired bis(6-isocyanatohexyl)uretdione (NCO content: 25.0%) were dissolved in 800 g of butyl acetate, 4.6 g (0.2 wt. %) of a 10% solution of dibutyltin dilaurate (DBTL) in butyl acetate were added and heated to 80° C. under dry nitrogen and 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 h. After a stirring time of 16 h at 80° C., the NCO content was <0.2%. An almost colorless solution of the HDI polyurethane crosslinker (HDI-UD2) was obtained.

[0134] NCO content: 0.16%

[0135] Urea dione group content: 10.8% (calculated as C2N2O2, molecular weight 84)

[0136] Ureadione functionality: 5 (calculated value)

[0137] Solid content: about 65%

[0138] Viscosity (23°C): 1400 mPas.

[0139] Catalyst C1)

[0140] 1-Ethyl-3-methylimidazolium acetate (97%), Sigma-Aldrich Chemie GmbH, München, DE

[0141] 1-Ethyl-3-methylimidazolium pivalate was prepared according to the method described in RSC Advances, 2019, Vol. 9, 4048 - 4053, D. Hirose, SB Wardhana Kusuma, S. Nomura, M. Yamaguchi, Y. Yasaka, R.Kakuchi and K. Takahashi.

[0142] Catalyst C2)

[0143] 1,8-Diazabicyclo[5.4.0]undec-7-ene, DBU (98%), Sigma-Aldrich Chemie GmbH, München, DE.

[0144] Examples 1 to 5 (The present invention and comparison)

[0145] In each case 2.5 g (0.014 equivalent) of a commercially available aromatic-free branched polyester polyol (with a solids content of 75% in butyl acetate and an OH content of 9.5%, based on the solid resin, available from Desmophen ® 775 (Covestro Deutschland AG, Leverkusen, DE)) was mixed with 10.4 g (0.014 equivalent) of the above-mentioned HDI polyuretdione crosslinker (corresponding to a hydroxyl / uretdione group equivalent ratio of 1:1) to provide a coating composition and, after addition of the catalyst component, was applied to a degreased glass slide using a coating bar in an application layer thickness of 180 µm.

[0146] After ventilation at room temperature for 5 minutes, the coatings were cured at 100° C. for 30 minutes. Completely transparent coatings were obtained in all cases. The table below shows the type and amount of catalyst added in each case and the coating technical properties of the resulting coatings.

[0147]

[0148] nm: unmeasurable

[0149] nd: not determined.

[0150] The comparison shows that the curing of the coating of Example 1 of the present invention produces a fully crosslinked hard coating with good optical properties. Although the coating film from Comparative Example 3 has slightly better flow properties, it exhibits severe yellow discoloration. The low values ​​of pendulum damping and microhardness and the extremely poor xylene resistance indicate that the system from Comparative Example 3 catalyzed only with DBU is not crosslinked under the selected curing conditions. The high hardness and good solvent resistance of the coating film obtained according to Comparative Example 2 indicate that this is also fully crosslinked. However, the structuring of the film surface is so severe that the values ​​of the optical appearance cannot be measured. Compared with coatings 1 and 4 made according to the present invention, the coating film from Comparative Example 5 catalyzed only with imidazolium salts has significantly lower pendulum damping and lower xylene resistance.

Claims

1. A composition comprising A) at least one component comprising at least one uretdione group, B) at least one component comprising at least one hydroxyl group, C1) at least one catalyst comprising structural units of the general formula (I) and / or (II) in R 1 , R 2 , R 3 , R 4 , R 5 and R 6 independently of one another represent identical or different radicals which represent saturated or unsaturated, linear or branched, aliphatic, alicyclic, araliphatic or aromatic organic radicals having 1 to 18 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, or these radicals, in combination with one another, optionally together with further heteroatoms, form an optionally further substituted ring having 3 to 8 carbon atoms, or R 3 , R 4 , R 5 and R 6 independently represent hydrogen, and R 7 represents hydrogen or carboxylate anion (COO - ),and C2) at least one catalyst comprising at least one N,N,N′-trisubstituted amidine structure and having an amidine group content of 12.0% to 47.0% by weight, calculated as CN2 with a molecular weight of 40.

2. The composition as claimed in claim 1, characterized in that Component A) is an isocyanate-functional compound containing uretdione groups A1) and / or an addition polymerization compound A2) obtained by reaction of an isocyanate-functional compound containing uretdione groups A1) with an alcohol and / or an amine.

3. The composition as claimed in claim 2, characterized in that Component A1) is based on PDI, HDI, IPDI, XDI, NBDI and / or H 12 - Compounds of MDI containing uretdione groups.

4. The composition as claimed in claim 3, characterized in that The uretdione group-containing compound has an average NCO functionality of at least 1.

6.

5. The composition as claimed in claim 3, characterized in that The uretdione group-containing compound has a uretdione structure content of 10% to 25% by weight, calculated as C2N2O2 with a molecular weight of 84.

6. A composition as claimed in claim 2 or 3, characterized in that The polyaddition compounds A2) are compounds prepared by reaction of isocyanate-functional compounds A1) containing uretdione groups with at least difunctional polyols and optionally monools in the molecular weight range of 62 to 22 000, observing an equivalent ratio of isocyanate groups to isocyanurate-reactive groups of 2:1 to 0.5:1, and have a free isocyanate group content of less than 5% by weight in solvent-free form.

7. A composition as claimed in any one of claims 1 to 5, characterized in that Component B) is an at least difunctional polyol in the molecular weight range from 62 to 22,000.

8. A composition as claimed in any one of claims 1 to 5, characterized in that Components A) and B) are present in amounts such that for each uretdione group of component A) there are 0.5 to 2.0 hydroxyl groups of component B).

9. A composition as claimed in any one of claims 1 to 5, characterized in that Component C1) is a catalyst containing structural units of the general formula (I) and / or (II), wherein R 1 and R 2 independently of one another represent identical or different radicals which represent saturated or unsaturated, linear or branched, aliphatic, alicyclic, araliphatic or aromatic organic radicals having 1 to 12 carbon atoms, which are substituted or unsubstituted and / or have heteroatoms in the chain, R 3 , R 4 , R 5 and R 6 represents hydrogen, and R 7 represents hydrogen or carboxylate anion (COO - ).

10. A composition as claimed in any one of claims 1 to 5, characterized in that Catalysts C1) are imidazolium salts of the types listed which have a carboxylate anion.

11. The composition as claimed in claim 10, characterized in that Catalyst C1) is 1,3-dimethylimidazolium 2-carboxylate, 1-ethyl-3-methylimidazolium 2-carboxylate, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium 2-carboxylate, 1-ethyl-3-methylimidazolium pivalate and / or 1-butyl-3-methylimidazolium acetate.

12. A composition as claimed in any one of claims 1 to 5, characterized in that Catalyst C2) is a bicyclic catalyst containing an N,N,N'-trisubstituted amidine structure of the general formula (III) wherein m is an integer from 1 to 9, and n is an integer from 1 to 3.

13. A composition as claimed in any one of claims 1 to 5, characterized in that Catalyst C2) is 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and / or 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).

14. A composition as claimed in any one of claims 1 to 5, characterized in that Catalysts C1) and C2) are each present in an amount of 0.0005% to 5% by weight, based on the total weight of components A) and B), excluding solvents, auxiliaries or additives optionally present in these components.

15. The composition as claimed in claim 14, characterized in that Catalysts C1) and C2) are each present in an amount of 0.0025% to 4% by weight, based on the total weight of components A) and B), excluding solvents, auxiliaries or additives optionally present in these components.

16. The composition as claimed in claim 14, characterized in that Catalysts C1) and C2) are each present in an amount of 0.005% to 2.5% by weight, based on the total weight of components A) and B), not including solvents, auxiliaries or additives optionally present in these components.

17. The composition as claimed in claim 14, characterized in that Catalysts C1) and C2) are each present in an amount of 0.05% to 0.5% by weight, based on the total weight of components A) and B), not including solvents, auxiliaries or additives optionally present in these components.

18. Use of a composition as claimed in any one of claims 1 to 17 for producing polyurethane plastics.

19. Use of a composition as claimed in any one of claims 1 to 17 for producing a coating composition.

20. A coating composition comprising a composition as claimed in any one of claims 1 to 17.

21. A substrate coated with a coating composition as claimed in claim 20, optionally cured under the action of heat.

22. Polyurethane plastics obtainable from a composition as claimed in any one of claims 1 to 17, optionally cured under the action of heat.

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