Single-component system for coatings

Abstract

The invention relates to a single-component system for coatings, comprising: a) at least one blocked polyisocyanate containing two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures; b) at least one binder which is reactive toward isocyanate groups and has, on a statistical average, at least two isocyanate-reactive groups per molecule; c) optionally catalysts; and d) optionally solvents and / or optionally auxiliaries and additives. The invention further relates to the use thereof and to methods for producing aqueous, solvent-free or solvent-containing lacquers, paints, adhesives and molded articles, as well as to the corresponding products.

Description

[0001] One-component system for coatings

[0002] The present invention relates to a one-component system (hereinafter also referred to as 1K system or 1K-PUR system) for coatings, as well as its use and methods for the production of varnishes, paints, adhesives and molded parts and the corresponding products.

[0003] The use of blocking agents for the temporary deactivation of isocyanate groups has been known for a long time. Blocked polyisocyanates are used, among other things, for the production of room-temperature stable 1-component polyurethane (1K-PUR) systems that begin to crosslink when the blocking agent's deblocking temperature is reached. The blocked polyisocyanates react with typical isocyanate-reactive compounds. 1K-PUR coatings are used today in can and coil coating, automotive OEM coating, and plastic coating. Depending on the requirements, various polyisocyanates based on aliphatic diisocyanates are used. Examples include the linear aliphatic diisocyanates hexamethylene diisocyanate (HDI) and pentamethylene diisocyanate (PDI), or the cycloaliphatic diisocyanates isophorone diisocyanate (I-PDI) and 4,4'-diisocyanatodicyclohexylmethane (H12MDI).

[0004] Review articles on the use of blocked polyisocyanates and their properties can be found, for example, in Wicks, Z. Progress in Organic Coatings 3 (1975) 73-99, Wicks, Z. Progress in Organic Coatings 9 (1981) 3-28, DA Wicks and ZW Wicks, Progress in Organic Coatings 36 (1999), 148-172.

[0005] The blocking agent has a significant influence on the properties of 1-component polyurethane (1-K-PUR) systems. For example, the blocking agent significantly affects, among other things, the reactivity (deblocking temperature), thermal yellowing, compatibility, and viscosity of the 1-component polyurethane formulation. (U. Meier-Westhues et al. “Polyurethanes: Coatings, Adhesives and Sealants”, 2nd Revised Edition, pp. 35–42. Hanover: Vincentz Network, 2019).

[0006] The most technically relevant blocking agents are e-caprolactam, methyl ethyl ketoxime (hereinafter also referred to as butanone oxime or MEKO), diethyl malonates, secondary amines, and triazole and pyrazole derivatives, for example described in EP-A 0576952, EP-A 0 566 953, EP-A 0 159 117, US-A 4482 721, WO 97 / 12924 or EP-A 0 744 423.

[0007] Polyisocyanates blocked with aliphatic alcohols such as methanol or ethanol are generally not used as blocking agents due to their very high curing temperatures (>180°C). Polyisocyanates blocked with aromatic alcohols, such as phenol, do have lower curing temperatures than their aliphatic counterparts (approximately 150°C for phenol), but are not widely used due to compatibility, solubility, and toxicity issues. The most commonly used blocking agents for isocyanates are e-caprolactam and MEKO. While curing temperatures of around 170°C or higher are typically used with e-caprolactam, blocked 1K-PUR stoving enamels using MEKO as a blocking agent can be cured at temperatures 10 to 20°C lower. However, MEKO is disadvantageous due to its toxicological properties.

[0008] Blocked polyisocyanates based on linear aliphatic diisocyanates such as HDI and PDI are highly prone to crystallization and solidification, but their property profile makes them indispensable for high-quality polyurethane (PUR) stoving enamels. Polyisocyanates based on linear aliphatic diisocyanates blocked with e-caprolactam or MEKO exhibit a lower tendency to crystallize and solidify compared to other blocking agents (due to their asymmetric structures), but show disadvantages, particularly in high-solids formulations, with regard to processable viscosities.

[0009] Furthermore, many blocking agents are based entirely on fossil raw materials, which is another disadvantage of the blocking agents known in the prior art.

[0010] The present invention was therefore based on the objective of providing a one-component system for coatings that enables lower crosslinking or curing temperatures and exhibits a significantly lower tendency to yellow and at least the same solvent and water resistance as the one-component systems blocked with e-caprolactam or MEKO.

[0011] This problem could be solved by providing a one-component system for coatings comprising a) at least one blocked polyisocyanate containing two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures, b) at least one binder reactive towards isocyanate groups with at least two isocyanate-reactive groups per molecule on average, c) optionally catalysts and d) optionally solvents and / or optionally auxiliary and additives.

[0012] Surprisingly, it was found that citric acid triesters (also referred to as "citrates" within the scope of the invention) can be used as blocking agents for isocyanates and, in addition to lower viscosity, offer the further advantages of a low crosslinking or curing temperature, as well as at least consistent solvent and water resistance and a significantly lower tendency to yellow. The terms "comprising" or "containing" preferably mean "essentially consisting of" and particularly preferably "consisting of". The further embodiments mentioned in the claims and in the description can be combined arbitrarily, unless the context clearly indicates otherwise.

[0013] “At least one,” as used herein, refers to one or more, for example, two, three, four, five, six, seven, eight, nine, or more. In the context of constituents of the compounds described herein, this term refers not to the absolute quantity of molecules but to the type of constituent. “At least one blocked polyisocyanate,” for example, means that only one type of blocked polyisocyanate or several different types of blocked polyisocyanates may be present, without specifying the quantity of each individual compound.

[0014] Numerical values ​​given herein without decimal places refer to the full value given with one decimal place. For example, "99%" means "99.0%".

[0015] Numerical ranges specified in the format "in / from x to y" include the values ​​mentioned. If multiple preferred numerical ranges are specified in this format, it is understood that all ranges resulting from the combination of the different endpoints are also included.

[0016] In this context, the term "aliphatic" is defined as non-aromatic hydrocarbon groups that are branched or unbranched and, in each case, saturated or unsaturated.

[0017] For the purposes of this document, the term "alicyclic" or "cycloaliphatic" is defined as possibly substituted, carbocyclic or heterocyclic compounds or units 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.

[0018] In this context, the term "araliphatic" is defined as aliphatic hydrocarbon residues that are saturated or unsaturated and have at least one aromatic substituent.

[0019] In the event that the groups or compounds are disclosed as "optionally substituted" or "substituted", suitable substituents are -F, -CI, -Br, -I, -OH, -OCH3, OCH2CH3, -O-isopropyl or -one-propyl, -OCF3, -CF3, -S-C1-6-alkyl and / or (optionally via an attached heteroatom) a linear or branched, aliphatic and / or alicyclic structural unit with 1 to 12 carbon atoms, each acting as a replacement for a carbon-bound hydrogen atom of the molecule in question. Preferred substituents are halogen (in particular -F, -CI), C1-6-alkoxy (in particular methoxy and ethoxy), hydroxy, trifluoromethyl and trifluoromethoxy, each acting as a replacement for a carbon-bound hydrogen atom of the molecule in question.

[0020] Polyisocyanates A) for the at least one blocked polyisocyanate a) are any diisocyanates, triisocyanates and / or polyisocyanates with aliphatic, cycloaliphatic, araliphatic and / or aromatic bonded isocyanate groups.

[0021] Suitable diisocyanates and triisocyanates A) are any diisocyanates and triisocyanates accessible in various ways, for example by phosgenation of the corresponding diamines or triamines, which can be produced using fossil raw materials or renewable raw materials, optionally on a mass balance basis, in the liquid or gas phase or by a phosgene-free method, such as thermal urethane cleavage, preferably those in the molecular weight range of 140 to 400 with aliphatic, cycloaliphatic, araliphatic and / or aromatically bonded isocyanate groups, such as... B. 1,4-Diisocyanatobutane, 1,5-Diisocyanatopentane (PDI), 1,6-Diisocyanatohexane (HDI), 2-Methyl-1,5-diisocyanatopentane, 1,5-Diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-Trimethyl-1,6-diisocyanatohexane, 1,8-Diisocyanatooctane, 1,9-Diisocyanatononane, 1,10-Diisocyanatodecane, 1,3- and 1,4-Diisocyanatocyclohexane, 1,3- and 1,4-Bis-(isocyanatomethyl)cyclohexane,1-lsocyanato-3,3,5-trimethyl-5- isocyanatomethylcyclohexan (Isophorondiisocyanat, IPDI), 2,4’- und 4,4'-Diiso- cyanatodicyclohexylmethan (H12-MDI), 4,4'-Diisocyanato-3,3'-dimethyldicyclohexylmethan, 4,4'-Diisocyanato-3,3',5,5'-tetramethyldicyclohexylmethan, 4,4'-Diisocyanato-1 ,T- 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-menthan, 1 ,3-Diisocyanatoadamantan, 1 ,3-Dimethyl-5,7-diisocyanatoadamantan, 1-lsocyanato-1-methyl-4(3)isocyanato- methylcyclohexan, Bis-(isocyanatomethyl)-norbornan (NBDI), 4-lsocyanatomethyl-1 ,8- octandiisocyanat (Triisocyanatononan; TIN), 1 ,3- und 1 ,4-Bis(isocyanatomethyl)benzol (Xylylendiisocyanat, XDI), 1 ,3- und 1 ,4-Bis-(2-isocyanato-prop-2-yl)-benzol (TMXDI), 1 ,3- Bis(isocyanatomethyl)-4-methylbenzol, 1 ,3-Bis(isocyanatomethyl)-4-ethylbenzol, 1 ,3- Bis(isocyanatomethyl)-5-methylbenzol, 1 ,3-Bis(isocyanatomethyl)-4,5-dimethylbenzol, 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,

[0022] (Phenylene diisocyanate), 2,4- and 2,6-diisocyanatotoluene (TDI), 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, the isomeric diethylphenylene diisocyanates, diisopropylphenylene diisocyanates, diisododecylphenylene diisocyanates and

[0023] Biphenyl diisocyanates, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-, 2,4'- and 4,4'-diisocyanatodiphenylmethane (MDI), 3,3'-dimethyldiphenylmethane-4,4'-diisocyanate, 4,4'-diisocyanatodiphenylethane, 1 ,5-Diisocyanatonaphthalene (naphthylene diisocyanate, NDI), diphenyl ether diisocyanate, ethylene glycol diphenyl ether diisocyanate,

[0024] Diethylene glycol diphenyl ether diisocyanate, 1,3-propylene glycol diphenyl ether diisocyanate, benzophenone diisocyanate, triisocyanatobenzene, 2,4,6-triisocyanatotoluene,

[0025] Trimethylbenzene triisocyanate, diphenylmethane-2,4,4'-triisocyanate, 3-methyldiphenylmethane-4,6,4'-triisocyanate, the isomeric naphthalene triisocyanates and methylnaphthalene diisocyanates, triphenylmethane triisocyanate, 2,4-diisocyanato-1-[(5-isocyanato-2-methylphenyl)methyl]benzene or mixtures of at least two such diisocyanates and triisocyanates.

[0026] Suitable polyisocyanates A) are any polyisocyanates with uretdione, isocyanurate, allophane, biuret, iminooxadiazindione and / or oxadiazintrione structure produced by modifying simple aliphatic, cycloaliphatic, araliphatic and / or aromatic diisocyanates and / or triisocyanates, for example those of the type mentioned above, as described, for example, in J. Prakt. Chem. 336 (1994) 185 - 200, in DE-A 1 670 666, DE-A 1 954 093, DE-A 2 414 413, DE-A 2 452 532, DE-A 2 641 380, DE-A 3 700 209, DE-A 3 900 053 and DE-A 3 928 503 or in EP-A 0 336 205, EP-A 0 339 396 EP-A 0 798299, EP-A 0 962 454, EP-A 0 962 455, EP-A 2 785760, EP-A 2 883 895, EP-A 3 107922, EP-A 3 107 948 and EP-A 3 337 836 are described as examples or any mixtures of such polyisocyanates.

[0027] If necessary, when modifying the aforementioned diisocyanates and / or triisocyanates to polyisocyanates A), subordinate amounts of monoisocyanates, especially those in the molecular weight range of 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, may also be present.

[0028] Cyclopentyl isocyanate, cyclohexyl isocyanate, 3- or 4-methylcyclohexyl isocyanate, benzyl isocyanate, phenyl isocyanate, or naphtyl isocyanate may also be used. If any monoisocyanates are used at all, they are present in amounts of up to 30 wt.%, preferably up to 20 wt.%, and particularly preferably up to 10 wt.%, based on the total amount of mono-, di-, and triisocyanates.

[0029] In the production of polyisocyanates A), the actual modification reaction is generally followed by a further process step to separate the unreacted excess monomeric diisocyanates and / or triisocyanates and optionally monoisocyanates. This monomer separation is carried out according to methods known per se, preferably by thin-film distillation under vacuum or by extraction with suitable solvents inert to isocyanate groups, for example, aliphatic or cycloaliphatic hydrocarbons such as pentane, hexane, heptane, cyclopentane, or cyclohexane.

[0030] In a first preferred embodiment of the one-component system according to the invention, the blocked polyisocyanate a) additionally contains one or more isocyanurate, allophane, urethane, urea, uretdione, iminooxadiazindione, oxadiazintrione and / or biuret structures.

[0031] Preferably, the starting material of the blocked polyisocyanate a) as polyisocyanate A) polyisocyanates, preferably polyisocyanates of the type mentioned, are used, which have an isocyanate group content of 6.0 to 26.0 wt.%, preferably of 8.0 to 25.0 wt.%, particularly preferably 10.0 to 24.0 wt.%, and / or a monomeric diisocyanate content of less than 0.50 wt.%, preferably less than 0.30 wt.%, more preferably less than 0.20 wt.%, particularly preferably less than 0.10 wt.%. For the alternative, optional case that triisocyanates and / or monoisocyanates were used to produce the polyisocyanates A), the aforementioned residual monomer contents of less than 0.50 wt.%, preferably less than 0.30 wt.%, more preferably less than 0.20 wt.%, and particularly preferably less than 0.10 wt.%, refer to all diisocyanates, triisocyanates and monoisocyanates used.The NCO content is determined according to DIN EN ISO 11909:2007-05, the residual monomer content according to DIN EN ISO 10283:2007-11 by gas chromatography with internal standard.

[0032] Particularly preferred polyisocyanates (A) are those of the type mentioned above with exclusively aliphatic and / or cycloaliphatic bonded isocyanate groups.

[0033] Particularly preferred polyisocyanates A) are polyisocyanates containing at least isocyanurate structures based on 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 1,3-bis(isocyanatomethyl)benzene, bis-(isocyanatomethyl)norbornane and / or 4,4'-diisocyanatodicyclohexylmethane.

[0034] Alternatively or in combination, the polyisocyanates A) preferably exhibit an average NCO functionality of 2.0 to 5.0, preferably of 2.5 to 4.5. The average NCO functionalities are determined by gel permeation chromatography.

[0035] Preferably, the free NCO content of the blocked polyisocyanate a) is < 5 wt.%, preferably < 2 wt.%, particularly preferably < 1 wt.%, even more preferably < 0.5 wt.% and most preferably < 0.3 wt.%, determined by titration according to DIN EN ISO 11909:2007-05 and based on the total weight of the blocked polyisocyanate a). The blocked polyisocyanates a) can be identified, for example, by NMR spectrometry or HPLC-MS by qualitative and quantitative determination of the 2-carbamoylpropane-1,2,3-tricarboxylate structures.

[0036] In a further preferred embodiment of the one-component system according to the invention, the two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures of the blocked polyisocyanate a) have a general formula (I), (I) on, in which

[0037] R independently represents any saturated or unsaturated, linear or branched, aliphatic residue with 1 to 18 carbon atoms, saturated or unsaturated cycloaliphatic residue with 3 to 18 carbon atoms, araliphatic residue with 7 to 18 carbon atoms and / or aromatic residue with 6 to 18 carbon atoms, each of which is substituted or unsubstituted and / or has heteroatoms in the chain.

[0038] In a further preferred embodiment of the one-component system according to the invention, the two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures of the blocked polyisocyanate a) have a general formula (I), (I) on, in which

[0039] R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 1 to 8 carbon atoms and / or saturated or unsaturated cycloaliphatic residue with 5 to 8 carbon atoms, each being substituted or unsubstituted and / or having heteroatoms in the chain, preferably in which R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 1 to 4 carbon atoms, each being substituted or unsubstituted and / or having heteroatoms in the chain, particularly preferably in which R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 2 to 4 carbon atoms.The carbamoylpropane-1,2,3-tricarboxylate structures, and thus also the structures of the general formula (I), represent the blocked NCO groups, with a corresponding citrate acting as the blocking agent. Since blocking agents are always used in large quantities to essentially block all free isocyanate groups, citrates offer the ecological advantage of being available on an industrial scale from (partially) bio-based raw materials.

[0040] The blocked polyisocyanate a) can be produced by a manufacturing process comprising a reaction of at least one polyisocyanate A) with at least one citrate B) optionally in the presence of at least one catalyst, wherein the citrate B) is used in an amount of > 95 equivalent % based on the isocyanate groups of the polyisocyanate A).

[0041] The suitable and preferred polyisocyanates A) are those described above. Preferably, in the manufacturing process, the at least one polyisocyanate A) has aliphatic, cycloaliphatic, araliphatic and / or aromatically bonded isocyanate groups and / or preferably comprises one or more polyisocyanates containing isocyanurate structures based on 1,5-diisocyanatopentane, 1,6-diisocyanatohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 1,3-bis(isocyanatomethyl)benzene, bis-(isocyanatomethyl)norbornane and / or 4,4'-diisocyanatodicyclohexylmethane.

[0042] The citrate B) is preferably used in an amount of > 98 equivalent %, particularly preferably > 99 equivalent %, even more preferably > 99.5 equivalent % and most preferably > 99.7 equivalent %, based on the isocyanate groups of the polyisocyanate A).

[0043] The at least one citrate (B) can be selected from various compounds. Preferably, in the manufacturing process, the at least one citrate (B) is one of the general formula (II).

[0044] (II), in which

[0045] R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 1 to 18 carbon atoms, saturated or unsaturated cycloaliphatic residue with 3 to 18 carbon atoms, araliphatic residue with 7 to 18 carbon atoms, and / or aromatic residue with 6 to 18 carbon atoms, each of which is substituted or unsubstituted and / or has heteroatoms in the chain. Particularly preferred in the manufacturing process is the at least one citrate (B), one of the general formula (II),

[0046] (II), in which

[0047] R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 1 to 8 carbon atoms and / or saturated or unsaturated cycloaliphatic residue with 5 to 8 carbon atoms, each being substituted or unsubstituted and / or having heteroatoms in the chain, preferably in which R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 1 to 4 carbon atoms, each being substituted or unsubstituted and / or having heteroatoms in the chain, particularly preferably in which R independently represents any saturated or unsaturated, linear or branched aliphatic residue with 2 to 4 carbon atoms.

[0048] Beispielhafte geeignete und bevorzugte Citrate B) sind Trimethylcitrat, Triethylcitrat, Tri-n- propylcitrat, Tri-iso-propylcitrat, Tri-n-butylcitrat, Tri-sec-butylcitrat, Tri-iso-butylcitrat, Tri-tert- butylcitrat, Tri-n-pentylcitrat, Tri(2-pentyl)citrat, Tri(3-pentyl)citrat, Tri(2-methyl-1-butyl)citrat , T ri (2-methy l-2-buty l)citrat, T ri-(3-methyl-1 -buty l)citrat, T ri (3-methy l-2-buty l)citrat, T ri (2 , 2- Dimethyl-1-propyl)citrat, Tri-n-hexylcitrat, Tri(2-hexyl)citrat, Tri(3-hexyl)citrat, Tri(2-methyl-1- pentyl)citrat, Tri(2-methyl-2-pentyl)citrat, Tri(2-methyl-3-pentyl)citrat, Tri(4-methyl-1- pentyl)citrat, Tri(4-methyl-2-pentyl)citrat, Tri(3-methyl-1-pentyl)citrat, Tri(3-methyl-2- pentyl)citrat, Tri(3-methyl-3-pentyl)citrat, Tri(2,2-dimethyl-1 -butyl)citrat, Tri(3,3-dimethyl-1- buty l)citrat, T ri (3, 3-d i methy l-2-buty l)citrat, T ri(2,3-dimethyl-1 -buty l)citrat, T ri(2,3-dimethyl-2- butyl)citrat, Tri(2-ethyl-1-butyl)citrat, Tri-n-heptylcitrat, Tri-(2-heptyl)citrat,Tri-(3-heptyl)citrat, T ri-(4-heptyl)citrat, T ri(5-methyl-1 -hexyl)citrat, T ri(5-methyl-2-hexyl)citrat, T ri(5-methyl-3- hexyl)citrat, T ri(2-methyl-3-hexyl)citrat, T ri(2-methyl-2-hexyl)citrat, T ri(2-methyl-1 -hexyl)citrat, Tri(4-methyl-1-hexyl)citrat, Tri(4-methyl-2-hexyl)citrat, Tri(4-methyl-3-hexyl)citrat, Tri(3- methyl-3-hexyl)citrat, Tri(3-methyl-2-hexyl)citrat, Tri(3-methyl-1-hexyl)citrat, Tri(2-ethyl-1 - penty l)citrat, T ri (3-ethy I- 1 -penty l)citrat, T ri (3-ethy l-2-penty l)citrat, T ri (3-ethy l-3-penty l)citrat, Tri(3,4-dimethyl-1 -pentyl)citrat, Tri(3,4-dimethyl-2-pentyl)citrat, Tri(2,3-dimethyl-1 -pentyl)citrat, Tri(2,3-dimethyl-2-pentyl)citrat,Tri(2,3-dimethyl-3-pentyl)citrat, Tri(2-isopropyl-1-butyl)citrat, Tri(2,3,3-trimethyl-1 -butyl)citrat); Tri(2,2,3-trimethyl-1 -butyl)citrat); Tri(2,3,3-trimethyl-2- buty l)ci trat) , T ri(3,3-dimethyl-1 -penty l)citrat, T ri (3, 3-d i methy l-2-penty l)citrat, T ri (2-ethy I- 2methyl-1-butyl)citrat, Tri(4,4-dimethyl-1 -pentyl)citrat, Tri(4,4-dimethyl-2-pentyl)citrat, Tri(2,2- dimethyl-1-pentyl)citrat, Tri-n-octylcitrat, Tri (2-octy I) citrat, Tri(3-octyl)citrat), Tri (4-octy I) citrat,

[0049] T ri(2-methyl-1 -hepty l)citrat, T ri(2-methyl-2-heptyl)citrat, T ri(2-methyl-3-heptyl)citrat, T ri (2- methyl-4-heptyl)citrat, T ri(3-methyl-1 -hepty l)citrat, T ri(3-methyl-2-heptyl)citrat, T ri(3-methyl-3- hepty l)citrat, T ri(3-methyl-4-heptyl)citrat, T ri(4-methyl-1 - hepty l)citrat, , Tri(4-methyl-3- hepty l)citrat, T ri(4-methyl-4-heptyl)citrat, Tri(5-methyl-1-heptyl)citrat, Tri(5-methyl-2- hepty l)citrat, T ri(5-methyl-3-heptyl)citrat, Tri(6-methyl-1-heptyl)citrat, Tri(6-methyl-2- hepty l)citrat, T ri(6-methyl-3-heptyl)citrat, T ri(2,2-dimethyl-1 -hexyl)citrat, T ri(2,2-dimethyl-3- hexyl)citrat, Tri(2,3-dimethyl-1-hexyl)citrat , Tri(2,3-dimethyl-2-hexyl)citrat, Tri(2,3-dimethyl-3- hexyl)citrat, T ri (2 , 4-d i methyl- 1 -hexyl)citrat, T ri(2,4-dimethyl-2-hexyl)citrat, T ri(2,4-dimethyl-3- hexyl)citrat T ri (2 , 5-d i methyl- 1 -hexyl)citrat, T ri(2,5-dimethyl-2-hexyl)citrat, T ri(2,5-dimethyl-3- hexyl)citrat, Tri(3,3-dimethyl-1-hexyl)citrat, Tri(3,3-dimethyl-2-hexyl)citrat,Tri(3,4-dimethyl-1- hexyl)citrat, T ri(3,4-dimethyl-2-hexyl)citrat, T ri(3,4-dimethyl-3-hexyl)citrat, T ri (3, 5-di m ethy I- 1 - hexyl)citrat, T ri(3,5-dimethyl-2-hexyl)citrat,T ri(3,5-dimethyl-3-hexyl)citrat, T ri (4, 4-d i methyl- 1 - hexyl)citrat, T ri(4,4-dimethyl-2-hexyl)citrat, T ri(4,4-dimethyl-3-hexyl)citrat, T ri(4,5-dimethyl-1 - hexyl)citrat, T ri(4,5-dimethyl-2-hexyl)citrat, T ri(4,5-dimethyl-3-hexyl)citrat, T ri(5,5-dimethyl-1 - hexyl)citrat, Tri(5,5-dimethyl-2-hexyl)citrat, Tri(5,5-dimethyl-3-hexyl)citrat, Tri(2-ethyl-1 - hexyl)citrat, Tri(3-ethyl-1-hexyl)citrat, Tri(3-ethyl-2-hexyl)citrat, Tri(3-ethyl-3-hexyl)citrat, Tri(4- ethyl-1-hexyl)citrat, Tri(4-ethyl-2-hexyl)citrat, Tri(4-ethyl-3-hexyl)citrat, Tri(2-propyl-1 - pentyl)citrat, Tri(2-ethyl-2-methyl-1-pentyl)citrat, Tri(2-ethyl-3-methyl-1-pentyl)citrat, Tri(2- ethyl-4-methyl-1-pentyl)citrat, Tri(3-ethyl-2-methyl-1-pentyl)citrat, Tri(3-ethyl-2-methyl-2- pentyl)citrat, Tri(3-ethyl-2-methyl-3-pentyl)citrat, ,Tri(3-ethyl-3-methyl-1-pentyl)citrat, , Tri(3- ethyl-3-methyl-2-pentyl)citrat, Tri(3-ethyl-4-methyl-1-pentyl)citrat, Tri(3-ethyl-4-methyl-2- pentyl)citrat, T ri (2 , 2 , 3-tri methy I- 1 -penty l)citrat) , T ri (2 , 2 , 3-tri methy l-2-penty I) citrat) , T ri (2 , 2 , 3- trimethyl-3-pentyl)citrat) , Tri(2,2,4-trimethyl-1 -pentyl)citrat), Tri(2,2,4-trimethyl-3-pentyl)citrat), Tri(2,3,3-trimethyl-1 -pentyl)citrat), Tri(2,3,3-trimethyl-2-pentyl)citrat), Tri(2,3,4-trimethyl-1 - pentyl)citrat), T ri (2 , 3, 4-tri methy l-2-penty l)citrat) , T ri (2 , 3, 4-tri methy l-3-penty I) ci trat) , T ri (2 , 4, 4- trimethyl-1 -pentyl)citrat), Tri(2,4,4-trimethyl-2-pentyl)citrat), Tri(3,3,4-trimethyl-1 -pentyl)citrat), T ri (3 , 3, 4-tri methy l-2-penty l)citrat) , T ri (3, 4, 4-tri methy I- 1 -pentyl) citrat), T ri (3, 4, 4-tri methy I-2- pentyl)citrat),Tri(2-Ethyl-2,3-dimethyl-1 -butyl)citrat, Tri(2-Ethyl-3,3-dimethyl-1 -butyl)citrat, Tri(3-methyl-2-(1-methylethyl)-1-butyl)citrat, Tri(2,2-diethyl-1-butyl)citrate, tri(2, 2,3,3-,

[0050] Tetramethyl-1-butyl)citrate, Trivinyl citrate, Trial ly citrate, Tri(2-(acryloyloxy)ethyl)citrate, Tri(2-(methacryloyloxy)ethyl)citrate, tribenzyl citrate, triphenyl citrate, tricyclopropyl citrate, tricyclobutyl citrate, tricyclopentyl citrate, tricyclohexyl citrate, tricycloheptyl citrate, Tricyclooctyl citrate and mixtures of the aforementioned.

[0051] Particularly preferred citrates B) are trimethyl citrate, triethyl citrate, tripropyl citrate, triisopropyl citrate, tri-n-butyl citrate, tri-sec-butyl citrate, tri-isobutyl citrate, tri-tert-butyl citrate, tri-n-pentyl citrate, tri-n-hexyl citrate, tri-n-octyl citrate, tri(2-ethyl-1-hexyl) citrate and mixtures of the aforementioned, and most particularly preferred citrates B) are trimethyl citrate, triethyl citrate, tributyl citrate and mixtures of the aforementioned.

[0052] If desired, the citrates mentioned (B) can also be mixed-esterified, for example diethyl methyl citrate or butyl diethyl citrate.

[0053] Since the citrates B) with the isocyanate groups form the 2-carbamoylpropane-1,2,3-tricarboxylate structures of the blocked polyisocyanates a), the 2-carbamoylpropane-1,2,3-trimethoxylate structures, 2-carbamoylpropane-1,2,3-triethoxylate structures, 2-carbamoylpropane-1,2,3-tributoxylate structures and mixtures of the aforementioned are particularly preferred structures and particularly preferred embodiments of the general formula (I).

[0054] Citric acid esters such as triethyl citrate, unlike blocking agents known from the prior art, are not toxic, irritating or otherwise harmful to health.

[0055] To carry out the manufacturing process, the at least one polyisocyanate A) is reacted with the at least one citrate B) preferably at temperatures of 20 to 120 °C, particularly preferably from 40 to 100 °C to form the blocked polyisocyanate a).

[0056] The blocking reaction in the manufacturing process can be carried out thermally induced without a catalyst or in the presence of at least one catalyst. Preferably, the reaction is carried out in the presence of at least one catalyst. This offers the advantage of further increasing the efficiency and cost-effectiveness of the manufacturing process.

[0057] Suitable catalysts include tertiary amines such as triethylamine, pyridine, methylpyridine, 1,4-diazabicyclo[2.2.2]octane, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, 4-(dimethylamino)pyridine, benzyldimethylamine, N,N-endoethylenepiperazine, N-methylpiperidine, pentamethyldiethylenetriamine, N,N-dimethylaminocyclohexane, N,N'-dimethylpiperazine, but also metal salts and chelates, salts of transition metals, semimetals or inorganic bases, such as potassium carbonate. Preferably, iron(III)-, bismuth(III)-, zinc(II)-, tin(II)-, tin(IV)-, zirconium(IV)-, titanium(IV)-, molybdenum(VI)- and Al(III)- are used as catalytically acting metal ions.Examples include iron(III) chloride, bismuth(III) octoate, bismuth(III) triflate, bismuth(III) neodecanoate, aluminum tri(ethyl acetoacetate), zinc(II) chloride, zinc(II) n-octanoate, zinc(II)-2-ethyl-1-hexanoate, zinc 2-ethyl caproate, zinc(II) stearate, Zinc (II) naphtenate, zinc (II) acetylacetonate, tin (II) n-octanoate, tin (II) 2-ethyl-1-hexanoate, tin (II) ethyl caproate, tin (II) laurate, tin (II) palmitate), tin (II) triflate, tin (II) chloride, dibutyl tin (IV) oxide, Dibutyltin(IV) dichloride, dibutyltin(IV) diacetate, Dibutyltin(IV) dimaleate, dibutyltin(IV) dilaurate, dioctyltin(IV) diacetate, molybdenum glycolate, tetraisopropyl titanate, tetrabutyl titanate, titanium(IV) acetylacetonate, zirconium(IV) neodecanoate, aluminum trisec butylate, aluminum(III) acetylacetonate, aluminum(III) triflate or any mixtures of such catalysts may be used.

[0058] The at least one catalyst that may be present is preferably in the manufacturing process in amounts of 1 to 10000 ppm, preferably 2 to 5000 ppm, particularly preferably 5 to 1000 ppm and most preferably 10 to 250 ppm.

[0059] A further advantage of the aforementioned catalysts containing metal ions is that these can be measured qualitatively and quantitatively in the blocked polyisocyanates a) and the one-component system according to the invention, for example by means of ICP-OES or ICP-MS.

[0060] The manufacturing process can be carried out without solvents. However, suitable solvents that are inert to the reactive groups of polyisocyanates A) can also be used if necessary. Suitable solvents include those produced using fossil raw materials or renewable raw materials, in particular the commonly known paint solvents, such as...Ethyl acetate, butyl acetate, ethylene glycol monomethyl or ethyl ether acetate, 1-methoxypropyl-2-acetate, 3-methoxy-n-butyl acetate, ethyl (-)-L-lactate, acetone, 2-butanone, 4-methyl-2-pentanone, cyclohexanone, dihydrolevoglucosenone, toluene, xylene, chlorobenzene, white spirit, highly substituted aromatics such as those sold under the names solvent naphtha, Solvesso®, Isopar®, Nappar®, Varsol® (ExxonMobil Chemical Central Europe, Cologne, Germany) and Shellsol® (Shell Deutschland Oil GmbH, Hamburg, Germany), but also solvents such as dimethylfuran, 2-methyltetrahydrofuran, dimethyl isosorbide (DMI), γ-valerolactone, propylene glycol diacetate, diethylene glycol dimethyl ether, Dipropylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether acetate, N-methylpyrrolidone and N-methylcaprolactam, or any mixtures of such solvents.

[0061] Following the reaction of polyisocyanate A) with citrate B), when the content of free isocyanate groups is preferably 2 wt.% or less, more preferably 1 wt.%, particularly preferably 0.5 wt.% or less, and most preferably 0.3 wt.% or less, the blocked polyisocyanates a) can optionally be further diluted with solvent, for example to reduce the viscosity. In addition to the solvents mentioned above, alcoholic solvents such as n-butanol or isobutyl alcohol can also be used, since the isocyanate groups will then have reacted largely, preferably completely, with the blocking agent.

[0062] In the manufacturing process, additional auxiliary and additive substances, such as antioxidants or light stabilizers, may optionally be used. These can be added to one or more of the reactants A), B) and optionally to the catalyst before the actual reaction begins. Alternatively, they can be added to the reaction mixture at any time during the reaction or to the blocked polyisocyanates a) after the reaction has taken place. The auxiliary and additive substances described herein as suitable and preferred may also be optionally included as component d) in the one-component system according to the invention.

[0063] Suitable antioxidants include phenols, especially sterically hindered phenols such as 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 2,6-di-tert-butyl-4-methylphenol, and triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate.

[0064] Octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), esters of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid with aliphatic branched O7 to C9 alcohols, such as e.g.isoheptyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, isooctyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or isononyl-3-(3,5-di-tert-butyl-4-hydroxyphenylpropionate, Isotridecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethyl bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylene-bis(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid amide, 1 ,2-Bis(3,5-di-tert-butyl-4-hydroxyphenylpropionic acid)hydrazide, 2,4-di-tert-butylphenyl-4'-hydroxy-3',5'-di-tert- butylbenzoate, esters of (3,5-di-tert-butyl-4-hydroxyphenyl)methylthioacetic acid with aliphatic branched C10 to C14 alcohols, 2,2'-thio-bis(4-methyl-6-tert-butylphenol), 2-methyl-4,6-bis(octylthiomethyl)phenol, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate or 2,5-di-tert-amylhydroquinone.

[0065] Suitable antioxidants also include thioethers, such as didodecyl-3,3'-thiodipropionate or dioctadecyl-3,3'-thiodipropionate, which are preferably used in combination with phenolic antioxidants of the type mentioned.

[0066] Other suitable antioxidants are phosphites, for example di- or preferably trisubstituted phosphites, such as... B. dibutyl phosphite, dibenzyl phosphite, triethyl phosphite, tributyl phosphite, triisodecyl phosphite, trilauryl phosphite, tris (tridecyl) phosphite, triphenyl phosphite, tris (2,4-di-tert-butylphenyl) phosphite, tris (nonylphenyl) phosphite, diphenyl isooctyl phosphite, Diphenyl isodecyl phosphite, diisodecyl phenyl phosphite, diisooctyl-octylphenyl phosphite, phenyl neopentyl glycol phosphite, 2,4,6-T ri-tert-butylphenyl-(2-butyl-2-ethyl-1,3-propanediol) phosphite, diisodecyl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, Bis(2,4-di-tert-butylphenyl)-pen-taerythritol diphosphite or tetraphenyl-dipropylene glycol diphosphite.

[0067] Suitable light stabilizers include, for example, UV absorbers of the type 2-hydroxyphenylbenzotriazole, those of the type of nitrogen-substituted or unsubstituted HALS compounds, such as Tinuvin® 292 or Tinuvin® 770 DF (BASF SE, Ludwigshafen, DE), or those described, for example, in "Light Stabilizers for Paints" (A. Valet, Vincentz Verlag, Hannover, 1996) and "Stabilization of Polymer Materials" (H. Zweifel, Springer Verlag, Berlin, 1997, Appendix 3, pp. 181-213).

[0068] Other auxiliary and additive substances that may optionally be used in the process according to the invention are also the hydrazide group-containing and / or hydroxy-functional stabilizers described in EP-A 0 829 500, such as the addition product of hydrazine and propylene carbonate.

[0069] The aforementioned auxiliary and additive materials can optionally be used individually or in any combination with each other in the process according to the invention in amounts of 0.001 to 3.0 wt.%, preferably 0.002 to 2.0 wt.%, particularly preferably 0.005 to 1.0 wt.%, in each case based on the total amount of polyisocyanate A).

[0070] Regardless of the type of process, the manufacturing process yields completely clear and transparent polyisocyanates or organic solutions of such polyisocyanates blocked with citric acid triesters (also citrates within the scope of the present invention), which exhibit significantly lower toxicity of the blocking agent, very high storage and solidification stability and low viscosity.

[0071] Furthermore, the use of one or more blocked polyisocyanates a), containing two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures, to lower the curing onset temperature and / or to increase the yellowing resistance of one-component systems is another preferred embodiment of the present invention. Compared to products known in the prior art, the blocked polyisocyanates a) exhibit significantly lower viscosities, so that they can be used with a higher solids content in the one-component system according to the invention. This results in the further advantage of an improved environmental footprint.

[0072] The blocked polyisocyanates a) represent valuable starting materials for the production of the one-component systems according to the invention. They are ideally suited as crosslinking components for one-component thermosetting solvent-free, solvent-containing, or aqueous coating systems, which are used particularly in plastic coating, automotive primary coating, or for coil coating applications. Thus, the use of the one-component system according to the invention as thermosetting solvent-free, solvent-containing, or aqueous coating systems, particularly in plastic coating, automotive primary coating, or for coil coating applications, is a further object of the present invention. In its use, thermosetting preferably takes place by baking in temperature ranges of 90 to 210°C, more preferably 105 to 180°C, particularly preferably 110 to 160°C, and most preferably 120 to 140°C.For the production of the one-component system according to the invention, the blocked polyisocyanates a) are mixed with paint binders b) known per se from paint technology, optionally with the addition of catalysts c) that accelerate the crosslinking reaction and optionally solvents and / or optionally auxiliary and additive substances d). The mixing must take place below the temperature at which the blocking agent is cleaved, since the release of the isocyanate groups would lead to premature crosslinking of the paint system. Preferably, the one-component systems according to the invention are produced at temperatures between 15 and 100°C. In the present work, the blocked polyisocyanates a) are also referred to as the blocked polyisocyanate component a) and / or the binders b) are also referred to as the binder component b).

[0073] As a binder component b), the one-component systems according to the invention contain at least one binder reactive towards isocyanate groups with at least two isocyanate-reactive groups, such as hydroxyl, mercapto, amino or carboxylic acid groups, per molecule on average.

[0074] Preferably, these binders are (b) the usual di- and / or polyhydroxyl compounds known from polyurethane chemistry, such as polyester polyols, polyether polyols, polycarbonate polyols and / or polyacrylate polyols, or any mixtures of such polyols. Preferably, the binder (b) comprises or consists of polyester polyols, polyether polyols, polycarbonate polyols and / or polyacrylate polyols, or any mixtures of such polyols; more preferably, the binder (b) comprises or consists of polyester polyols and / or polyacrylate polyols.

[0075] Suitable polyester polyols b) are, for example, those with a number-average molecular weight of 500 to 150,000 g / mol, calculable from functionality and hydroxyl number, preferably 600 to 30,000 g / mol, more preferably 700 to 15,000 g / mol, even more preferably 800 to 10,000 g / mol, particularly preferably 900 to 5,000 g / mol, and most preferably 1,000 to 3,000 g / mol, and / or with a hydroxyl group content of 0.03 to 21 wt.%, preferably 0.1 to 20 wt.%, particularly preferably 1 to 19 wt.%, and most particularly preferably 2 to 18 wt.%, as they are prepared in a manner known per se by reacting polyhydric alcohols with subtractive amounts of polyhydric carboxylic acids, corresponding carboxylic anhydrides, corresponding They can be produced from polycarboxylic acid esters of lower alcohols or by reaction with lactones.

[0076] Suitable polyhydric alcohols for the production of polyester polyols b) are, for example, 1,2-ethanediol, 1,2- and 1,3-propanediol, the isomeric butanediols, pentanediols, hexanediols, heptanediols and octanediols, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,10-decanediol, 1,12-dodecanediol, 2,2,4,4-tetramethylcyclobutane-1,3-diol (TMCD), 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-[5.2.1.02,6]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 hydroxypivalic acid neopentyl glycol esters, or mixtures of at least two such alcohols.

[0077] Suitable carboxylic acids or carboxylic acid derivatives for the production of the polyester polyols to be used in the one-component systems according to the invention (b) are polyhydric carboxylic acids, their carboxylic anhydrides, and polycarboxylic esters of lower alcohols. These are any aromatic, aliphatic, or cycloaliphatic, saturated or unsaturated di- and tricarboxylic acids or their anhydrides, in particular those with 4 to 18 carbon atoms, preferably with 4 to 10 carbon atoms, such as succinic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, cortic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, and tetrahydrophthalic acid.

[0078] Phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic acid, tetrahydrophthalic anhydride, dimethyl terephthalate and bis-glycol terephthalate, as well as dimeric and trimeric fatty acids, which can be used individually or in any mixture with each other.

[0079] If necessary, monocarboxylic acids such as benzoic acid, acetic acid, propionic acid, butyric acid or 2-ethylhexanoic acid may also be used in subordinate quantities for the production of polyester polyols b).

[0080] Suitable polyester polyols b) for the one-component systems according to the invention are also those that can be prepared in a known manner from lactones and polyhydric alcohols, such as those mentioned above as examples, as starter molecules via ring opening. Suitable lactones for the preparation of these polyester polyols b) are, for example, β-propiolactone, γ-butyrolactone, γ- and β-valerolactone, β-caprolactone, 3,5,5- and 3,3,5-trimethylcaprolactone, or any mixtures of such lactones. The preparation of these lactone polyesters generally takes place in the presence of catalysts such as Lewis or Brønsted acids, organotin or titanium compounds at temperatures of 20 to 200°C, preferably 50 to 160°C.Suitable components for the production of these polyester polyols b) include, for example, the polyhydric alcohols, polyhydric carboxylic acids and their derivatives mentioned above as suitable for the production of polyester polyols b), which can also be used in the form of any mixtures.

[0081] The preparation of the polyester polyols b) can be carried out according to methods known per se, such as those described in detail in E. Gubbels et al., Polyesters. In: Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH & Co. KGaA; 2018. URL: https: / / doi.org / 10.1002 / 14356007.a21_227.pub2. If necessary, catalytic amounts of common esterification catalysts, such as acids, bases, or transition metal compounds like titanium tetrabutylate, can be used. The esterification reaction is generally carried out in a temperature range of approximately 80 to 260°C, preferably 100 to 230°C, until the desired values ​​for hydroxyl and acid numbers are reached.

[0082] Suitable polyether polyols b) are, for example, those with a medium molecular weight of 200 to 6000, preferably 250 to 4000, calculable from functionality and hydroxyl number, with a hydroxyl group content of 0.6 to 34 wt.%, preferably 1 to 27 wt.%, as can be obtained in a manner known per se by alkoxylation of suitable starter molecules. Any polyhydric alcohols, such as those described above as suitable for the preparation of polyester polyols b), can be used as starter molecules for the preparation of these polyether polyols.

[0083] Suitable alkylene oxides for the alkoxylation reaction are in particular ethylene oxide and propylene oxide, which can be used in any order or in a mixture in the alkoxylation reaction.

[0084] Suitable polycarbonate polyols (b) are, in particular, the reaction products of dihydric alcohols, such as those listed above as examples of polyhydric alcohols, with diaryl carbonates, such as diphenyl carbonate, dimethyl carbonate, or phosgene, which are known per se. Suitable polycarbonate polyols (b) also include those that contain ester groups in addition to carbonate structures. These are, in particular, the polyester carbonate polyols known per se, such as those that can be obtained, for example, according to the teaching of DE-AS 1 770245, by reacting dihydric alcohols with lactones, such as s-caprolactone, and subsequently reacting the resulting polyester polyols with diphenyl or dimethyl carbonate. Also suitable are polycarbonate polyols (b) that contain ether groups in addition to carbonate structures.These are in particular the polyether carbonate polyols known per se, such as those obtained, for example, by the process of EP-A 2 046 861 through catalytic reaction of alkylene oxides (epoxides) and carbon dioxide in the presence of H-functional starter substances.

[0085] Suitable polyacrylate polyols b) are, for example, those with a mean molecular weight of 800 to 50000, preferably 1000 to 20000, which can be calculated from functionality and hydroxyl number or determined by gel permeation chromatography (GPC), with a hydroxyl group content of 0.1 to 12 wt.%, preferably 1 to 10, as they can be produced in a manner known per se by copolymerization of olefinically unsaturated monomers having hydroxyl groups with hydroxyl-group-free olefinic monomers.

[0086] Examples of suitable monomers for the preparation of polyacrylate polyols b) are vinyl or vinylidene monomers such as styrene, α-methylstyrene, β- or p-chlorostyrene, β-, m- or p-methylstyrene, p-tert-butylstyrene, acrylic acid, acrylonitrile, methacrylonitrile, acrylic and methacrylic acid esters of alcohols with up to 18 carbon atoms, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, 3,3,5-trimethylhexyl acrylate, stearyl acrylate, lauryl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, 4-tert--Butycyclohexyl acrylate, isobornyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, 3,3,5-trimethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, 4-tert-butylcyclohexyl methacrylate, norbornyl methacrylate or isobornyl methacrylate, diesters of fumaric acid, itaconic acid or maleic acid with alcohols having 4 to 8 carbon atoms, acrylamide, methacrylamide, vinyl esters of alkane monocarboxylic acids with 2 to 5 carbon atoms, such as... B. Vinyl acetate or vinyl propionate, hydroxyalkyl esters of acrylic acid or methacrylic acid with 2 to 5 carbon atoms in the hydroxyalkyl group, such as e.g.2-Hydroxyethyl, 2-Hydroxypropyl, 3-Hydroxypropyl, 3-Hydroxybutyl, 4-Hydroxybutyl, Trimethylolpropane monoacrylate or pentaerythritol monoacrylate or methacrylate, as well as any mixtures of such exemplary monomers.

[0087] The one-component systems according to the invention may optionally contain catalysts c). These are in particular the urethanization catalysts already mentioned above as suitable for accelerating the reaction of the polyisocyanate component A) with the diol component B) and the amine component C), preferably bismuth(III), zinc(III), tin(III) and / or tin(IV) as the catalytically active metal ion and especially preferably bismuth(III) octoate, bismuth(III) triflate, bismuth(III) neodecanoate, zinc(III) chloride, zinc(III) n-octanoate, zinc(III) 2-ethyl-1-hexanoate, zinc 2-ethylcaproate, zinc(III) stearate, zinc(III) naphthenate, zinc(III) acetylacetonate, tin(III) n-octanoate, tin(III) 2-ethyl-1-hexanoate, tin(III) ethylcaproate, tin(III) iaurate. Tin(II) palmitate), tin(II) triflate, tin(II) chloride, dibutyltin(IV) oxide, dibutyltin(IV) dichloride, dibutyltin(IV) diacetate, dibutyltin(IV) dimaleate,Dibutyltin(IV) dilaurate and / or dioctyltin(IV) diacetate and most preferably bismuth(III) octoate, bismuth(III) triflate, bismuth(III) neodecanoate, zinc(III)n octanoate, zinc(III) 2-ethyl-1-hexanoate and / or dibutyltin(IV) dilaurate. These catalysts c) are used in the one-component systems according to the invention as individual substances or in the form of any mixtures with each other in amounts of 0.001 wt.% to 6 wt.%, preferably from 0.002 wt.% to 5 wt.%, particularly preferably from 0.005 wt.% to 2 wt.% and most preferably from 0.005 wt.% to 1 wt.%, calculated as the sum of all catalysts c) used and based on the total amount of solvent-free blocked polyisocyanate a) and solvent-free binder component b).

[0088] The one-component systems according to the invention may optionally also contain further auxiliary and additive substances d). In addition to the antioxidants and light stabilizers mentioned above, which may optionally be used in the process according to the invention, these include, for example, the usual plasticizers, leveling agents, rheology additives, slip additives, defoamers, fillers and / or pigments known to those skilled in the art, which are used in quantities customary in coating technology, if at all. A detailed overview of such suitable auxiliary and additive substances can be found, for example, in Bodo Müller, “Additive kompakt”, Vincentz Network GmbH & Co KG (2009).

[0089] In the production of the one-component systems according to the invention, the polyisocyanate component a) and the binder component b) are preferably used in such quantities that the equivalent ratio of the sum of blocked and unblocked isocyanate groups from a) to isocyanate-reactive groups from b) is from 0.5 : 1 to 1.5 : 1, particularly preferably from 0.7 : 1 to 1.3 : 1, and most preferably from 0.8 : 1 to 1.2 : 1.

[0090] Thus, a further preferred embodiment is a one-component system for coatings, comprising a) at least one blocked polyisocyanate containing two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures, b) at least one binder reactive towards isocyanate groups with, on average, at least two isocyanate-reactive groups per molecule, c) optionally catalysts, and d) optionally solvents and / or optionally auxiliary and additive substances, wherein a) and b) are present in an equivalent ratio of the sum of blocked and unblocked isocyanate groups from a) to isocyanate-reactive groups from b) of 0.5 : 1 to 1.5 : 1, particularly preferably of 0.7 : 1 to 1.3 : 1, and most preferably of 0.8 : 1 to 1.2 : 1.

[0091] The one-component systems according to the invention may optionally contain further compounds reactive towards isocyanate-reactive groups as an additional crosslinking component. These are, for example, compounds containing epoxy groups and / or aminoplast resins. Aminoplast resins are the condensation products of melamine and formaldehyde, or urea and formaldehyde, known in paint technology.

[0092] All conventional melamine-formaldehyde condensates, either unetherified or etherified with saturated monoalcohols with 1 to 4 carbon atoms, are suitable. If other crosslinking components are used, the amount of binder with isocyanate-reactive groups must be adjusted accordingly.

[0093] The invention also relates to a method for producing a shaped body or an adhesive between two substrates or a coating on a substrate by reacting a one-component system according to the invention under the influence of heat, preferably by baking in temperature ranges of 90 to 210°C, more preferably 105 to 180°C, particularly preferably 110 to 160°C, and most preferably 120°C to 140°C, or by reacting a one-component system obtainable or produced according to the method under the influence of heat, preferably by baking in temperature ranges of 90 to 210°C, more preferably 105 to 180°C, more preferably 110 to 160°C, and most preferably 120°C to 140°C.

[0094] A shaped body, bonded substrate, or coated substrate comprising a hardened one-component system according to the invention, or comprising a product obtainable or produced by the method for producing a shaped body, an adhesive, or a coating on a substrate by reacting a one-component system according to the invention under the influence of heat, preferably by baking in temperature ranges of 90 to 210°C, more preferably 105 to 180°C, particularly preferably 110 to 160°C, and most preferably 120°C to 140°C, are further objects of the present invention, as is a substrate at least partially coated with at least one hardened one-component system according to the invention, or at least partially coated with at least one hardened one-component system, obtainable or produced according to the method according to the invention.The application of the one-component systems according to the invention can be carried out using methods known per se, for example by spraying, brushing, dipping, flooding or with the aid of rollers or squeegees in one or more layers.

[0095] Any substrates can be used as substrates, such as metal, wood, glass, stone, ceramic materials, composite materials or plastics of all kinds, which may also be coated with common, known primers, fillers, base coats and / or clear coats before coating.

[0096] The dried films are cured by baking at temperatures ranging from 90 to 210°C, preferably 105 to 180°C, particularly preferably 110 to 160°C, and preferably 120 to 140°C. The dry film thickness can be, for example, 10 to 120 µm.

[0097] The one-component systems according to the invention can also be used for continuous strip coating, whereby maximum curing temperatures, known to those skilled in the art as peak metal temperatures, between 130 and 300°C, preferably 190 to 260°C, and / or dry film thicknesses of, for example, 3 to 40 pm can be achieved. Such use is a further object of the present invention.

[0098] The features and embodiments identified as exemplary and preferred for the blocked polyisocyanate a) are also preferred for the other subject matter of the invention.

[0099] The following examples serve to illustrate the present invention, but should in no way be understood as a limitation of the scope of protection.

[0100] Examples

[0101] Syntheses were carried out inertly, using Schlenk technology, in previously heated glass apparatus under dry nitrogen.

[0102] Unless otherwise stated, all percentages refer to weight.

[0103] The determination of the NCO content, including the determination of the content of free NCO groups, was carried out titrimetrically according to DIN EN ISO 11909:2007-05.

[0104] The course of the blocking reaction and the NCO-free status of the blocked polyisocyanates were determined by the decrease or absence of the isocyanate band (approx. 2270 cm⁻¹). -1 ) tracked in the IR spectrum.

[0105] The residual monomer content was measured by gas chromatography with an internal standard according to DIN EN ISO 10283:2007-11.

[0106] 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 .

[0107] Dynamic mechanical analysis (DMA):

[0108] Analyzer DMA 2980 from TA-Instruments.

[0109] Calibration: Temperature of indium in glass fabric

[0110] Measurement: Dual cantilever clamps

[0111] Deformation amplitude 0.2 mm, excitation 2 Hz, heating from room temperature to +2500 °C, heating rate 2 K / min

[0112] Chemicals and starting compounds:

[0113] Triethyl citrate (Merck KGaA, Sigma Aldrich Germany)

[0114] MEKO (Merck KGaA, Sigma Aldrich Germany)

[0115] 8-Caprolactam (Merck KGaA, Sigma Aldrich Germany)

[0116] Hexamethylene diisocyanate HDI (Desmodur® H, Covestro Deutschland AG)

[0117] Desmodur® BL 3175 (MEKO blocked HDI polyisocyanate, Covestro Deutschland AG)

[0118] Desmodur® BL 3272 (s-caprolactam blocked HDI polyisocyanate, Covestro Germany)

[0119] AG)

[0120] Desmophen 650 MPA (branched polyester polyol, OH number: approx. 5.3; acid number: <3 mg)

[0121] KOH / g, Covestro Deutschland AG)

[0122] Desmorapid® SO (Tin octoate, Covestro Deutschland AG)

[0123] Butyl acetate (Azelis Deutschland GmbH)

[0124] Solvent Naphtha 150 ND (S 150 ND) (DHC Solvent Chemie GmbH)

[0125] Borchi® Kat 24 (bismuth octoate, Borchers GmbH) Setalux® A 870 BA (polyacrylate, OH number: approx. 2.8-3.1; acid number: approx. 7.5 mg KOH / g, Allnex)

[0126] Germany GmbH)

[0127] Application-related tests:

[0128] Pendulum damping according to König was carried out on glass plates in accordance with DIN EN ISO 1522.

[0129] Solvent and water resistance were determined according to DIN EN ISO 4628-1. Xylene, methoxypropyl acetate (MPA), ethyl acetate (EA), and acetone were tested for solvent resistance. The contact time was 5 minutes in each case. For water resistance, the contact time was 1 hour in each case. Sampling was carried out according to the specified standard. The test surface was assessed visually and by scratching, using the following classification: 0 = No change detectable; 1 = Swelling ring, surface hard, only visible change; 2 = Swelling ring, slight softening; 3 = Significant softening; 4 = Severe softening, scratchable to the substrate; 5 = Coating completely destroyed without external influence.

[0130] Thermal yellowing:

[0131] Lacquers were applied to glass plates using a doctor blade and baked in an oven at 140°C, 160°C, and 180°C for 30 minutes each. The dry film thickness ranged from 25 to 40 µm. The initial yellowing of the dried lacquer films was measured at three different locations using an X-Rite SP60 spectrophotometer. The glass plates were then baked for another 30 minutes at a temperature 20°C higher than during the initial baking process. After cooling, the thermal yellowing of the lacquers was measured again at three different locations.

[0132] Starting polyisocyanate

[0133] Polyisocyanate 1 :

[0134] Polyisocyanate containing isocyanurate groups, based on HDI, produced according to EP 330 966.

[0135] 1000 g of hexamethylene diisocyanate (HDI) were placed in a four-necked flask equipped with a stirrer, reflux condenser, nitrogen feed tube, and internal thermometer. The flask was degassed three times at room temperature by applying a vacuum of approximately 50 mbar and then purged with nitrogen. To initiate the trimerization reaction, 12 g of a catalyst solution, 0.5% (2-hydroxyethyl)trimethylammonium hydroxide in a 1:1 mixture of methanol and 2-ethylhexane-1,3-diol, was added dropwise over 30 minutes and slowly heated to 70°C. The mixture heated to approximately 75°C and was stirred at this temperature for one hour. Subsequently, another 12 g of catalyst solution were added dropwise, and the reaction mixture was stirred until an NCO content of 38.0% was reached.The reaction was stopped equimolarly (based on catalyst loading) with dibutyl phosphate (25% in HDI) and subsequently freed from excess HDI by thin-film distillation (130 °C, 0.1 mbar). A colorless polyisocyanurate polyisocyanate with the following properties was obtained:

[0136] NCO content: 21.7 wt.%

[0137] Monomeric HDI content: < 0.1%

[0138] Solids content: 100%

[0139] Viscosity (23°C): 3000 mPas

[0140] Blocked polyisocyanates

[0141] Blocked polyisocyanate 1 :

[0142] Polyisocyanate 1 (986.4 g, 1.0 val) was dissolved in butyl acetate (800.3 g). Triethyl citrate (1414.6 g, 1.0 val) was added dropwise to this solution under dry nitrogen and mechanical stirring. The reaction mixture was then heated to 50°C, Desmorapid® SO (100 ppm) was added, and stirring continued until all NCO groups had reacted (determined by IR spectroscopy). A colorless, blocked polyisocyanate with the following properties was obtained:

[0143] Free NCO content: 0.0%

[0144] Blocked NCO content: 6.7%

[0145] Solids content: 75%

[0146] Viscosity (23°C): 1180 mPas

[0147] Blocked polyisocyanate 2:

[0148] Desmodur® BL 3175, a MEKO-blocked HDI polyisocyanate

[0149] Blocked NCO content: 11.1%

[0150] Solids content: 75%

[0151] Viscosity (23°C): 3300 mPas Blocked 3:

[0152] Desmodur® BL 3272, an s-caprolactam-blocked HDI polyisocyanate

[0153] Blocked NCO content: 10.2%

[0154] Solids content: 72%

[0155] Viscosity (23°C): 2700 mPas

[0156] Single-component systems (1 K-PUR systems)

[0157] Example 1 (according to the invention):

[0158] Blocked polyisocyanate 1 (7.82 g) was mixed with Setalux® A 870 BA (OH-functional polyacrylate polyol, 70% dissolved in butyl acetate, 7.18 g). A 10% catalyst solution in butyl acetate (Borchi® Kat 24) was added to this mixture (1.09 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 68% was obtained.

[0159] Example 2 (comparison):

[0160] Blocked polyisocyanate 2 (5.95 g) was mixed with Setalux® A 870 BA (OH-functional polyacrylate polyol, 70% dissolved in butyl acetate, 9.05 g). A 10% catalyst solution in butyl acetate (Borchi® Kat 24) was added to this mixture (1.09 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 68% was obtained.

[0161] Example 3 (comparison):

[0162] Blocked polyisocyanate 3 (6.26 g) was mixed with Setalux® A 870 BA (OH-functional polyacrylate polyol, 70% dissolved in butyl acetate, 8.74 g). A 10% catalyst solution in butyl acetate (Borchi® Kat 24) was added to this mixture (1.09 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 67% was obtained.

[0163] Example 4 (according to the invention):

[0164] Blocked polyisocyanate 1 (7.82 g) was mixed with Setalux® A 870 BA (OH-functional polyacrylate polyol, 70% dissolved in butyl acetate, 7.18 g). A 10% catalyst solution in butyl acetate (Borchi® Kat 24) was added to this mixture (5.45 g, corresponding to approximately 5% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 56% was obtained. Example 5 (comparison):

[0165] Blocked polyisocyanate 2 (5.95 g) was mixed with Setalux® A 870 BA (OH-functional polyacrylate polyol, 70% dissolved in butyl acetate, 9.05 g). A 10% catalyst solution in butyl acetate (Borchi® Kat 24) was added to this mixture (5.40 g, corresponding to approximately 5% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 56% was obtained.

[0166] Example 6 (according to the invention):

[0167] Blocked polyisocyanate 1 (12.36 g) was mixed with Desmophen® 650 (OH-functional polyester polyol dissolved 65% in methoxypropyl acetate, 6.31 g). A 25% catalyst solution in methoxypropyl acetate (Borchi® Kat 24) was added to this mixture (0.54 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 70% was obtained.

[0168] Example 7 (comparison):

[0169] Blocked polyisocyanate 2 (8.12 g) was mixed with Desmophen® 650 (OH-functional polyester polyol dissolved 65% in methoxypropyl acetate, 6.88 g). A 25% catalyst solution in methoxypropyl acetate (Borchi® Kat 24) was added to this mixture (0.42 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 69% was obtained.

[0170] Example 8 (comparison):

[0171] Blocked polyisocyanate 3 (8.44 g) was mixed with Desmophen® 650 (OH-functional polyester polyol dissolved 65% in methoxypropyl acetate, 6.56 g). A 25% catalyst solution in methoxypropyl acetate (Borchi® Kat 24) was added to this mixture (0.42 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 69% was obtained.

[0172] Example 9 (according to the invention):

[0173] Blocked polyisocyanate 1 (6.62 g) was mixed with Desmophen® 650 (OH-functional polyester polyol dissolved 65% in methoxypropyl acetate, 3.38 g). A 10% catalyst solution in methoxypropyl acetate (Addocat 201) was added to this mixture (0.72 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 68% was obtained. Example 10 (comparison):

[0174] Blocked polyisocyanate 2 (4.57 g) was mixed with Desmophen® 650 (OH-functional polyester polyol dissolved 65% in methoxypropyl acetate, 5.43 g). A 10% catalyst solution in methoxypropyl acetate (Borchi® Kat 24) was added to this mixture (0.70 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 66% was obtained.

[0175] Example 11 (comparison):

[0176] Blocked polyisocyanate 3 (8.44 g) was mixed with Desmophen® 650 (OH-functional polyester polyol dissolved 65% in methoxypropyl acetate, 6.56 g). A 10% catalyst solution in methoxypropyl acetate (Addocat 201) was added to this mixture (1.03 g, corresponding to approximately 1% of the solid resin). The mixture was homogenized using a speed mixer (30 s at 2800 rpm). A clear lacquer with a solids content of 65% was obtained.

[0177] DMA analyses:

[0178] DMA analyses were carried out in order to determine the temperature ranges in which the 1 K-PUR systems can be baked on.

[0179] Table 1: DMA analyses of the described 1 K-PUR systems for determining the deblocking temperatures of various blocking agents, catalyzed with 1 wt.% Borchi®Kat24. The DMA analyses in Table 1 demonstrate that polyisocyanates blocked with trialkyl citrates, such as triethyl citrate, unblock at a lower temperature than those blocked with MEKO and s-caprolactam. The curing of triethyl citrate-blocked isocyanates is catalyzed from 110°C (polyacrylate) or 108°C (polyester), whereas isocyanates blocked with MEKO or s-caprolactam can only be cured from 124°C / 120°C or 154°C / 122°C, respectively.

[0180] Application-related testing:

[0181] The above-mentioned single-component systems were applied to glass plates using a squeegee and fired in an oven. The firing conditions and the resulting application data are summarized in the following tables:

[0182] Table 2: Application-related test results of examples 1 to 3.

[0183] Table 2 shows that the 1-component polyurethane (1K-PUR) system according to the invention from Example 1 achieves very good solvent and water resistance after baking at 160°C, comparable to the 1K-PUR system of the MEKO-blocked polyisocyanate from Example 2. At the same time, it is clear that the formulation from Example 1 achieves better resistance than the s-caprolactam-blocked one-component system from Example 3. Furthermore, the coating based on Example 1 exhibits higher pendulum damping according to König than the coatings from comparative examples 2 and 3. Table 3: Application-related test results of Examples 4 and 5.

[0184] The results from Table 3 clearly show that by increasing the catalyst concentration to 5%, a reduction in the curing temperature to 120°C is possible, whereby the coating produced from Example 4 according to the invention still exhibits good to very good resistance and very high oscillation damping. However, coatings cured at 120°C based on the formulation from Example 5 exhibit poorer resistance and lower oscillation damping. Formulations based on s-caprolactam do not react under these conditions. Table 4: Application-related test results, Examples 6 to 8. One-component polyurethane (1-K-PUR) systems containing trialkyl citrate-blocked polyisocyanate in combination with polyester polyols (Example 6) also exhibit exceptionally high solvent and water resistance after curing at 140°C, as shown in Table 4. These properties are significantly superior to s-caprolactam-blocked systems and comparable to MEKO-blocked systems. Furthermore, it is shown that the 1-component polyurethane system according to the invention from Example 6 achieves both excellent solvent and water resistance and exceptionally high surface hardness (pendulum damping).

[0185] Table 5: Thermal yellowing example 9.

[0186] Table 6: Thermal yellowing example 10.

[0187] Table 7: Thermal yellowing example 11. Tables 5 to 7 clearly show that the yellowing tendency of the inventive one-component system containing the trialkyl citrate-blocked polyisocyanate (Example 9) is significantly superior to that of comparative examples 10 and 11. Even under very high curing and over-curing conditions, the inventive 1K-PUR system hardly tends to yellow.

Claims

1. A one-component system for coatings comprising a) at least one blocked polyisocyanate containing two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures, b) at least one binder reactive towards isocyanate groups with, on average, at least two isocyanate-reactive groups per molecule, c) optionally catalysts and d) optionally solvents and / or optionally auxiliary and additive substances.

2. One-component system according to claim 1, characterized in that the blocked polyisocyanate a) additionally contains one or more isocyanurate, allophane, urethane, urea, uretdione, iminooxadiazindione, oxadiazintrione and / or biuret structures.

3. One-component system according to one of claims 1 or 2, characterized in that the two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures of the blocked polyisocyanate a) a general formula (I), exhibit in which R independently represents any saturated or unsaturated, linear or branched, aliphatic residue with 1 to 18 carbon atoms, saturated or unsaturated cycloaliphatic residue with 3 to 18 carbon atoms, araliphatic residue with 7 to 18 carbon atoms and / or aromatic residue with 6 to 18 carbon atoms, each of which is substituted or unsubstituted and / or has heteroatoms in the chain.

4. One-component system according to one of claims 1 to 3, characterized in that the two or more 2-carbamoylpropane-1,2,3-tricarboxylate structures of the blocked polyisocyanate a) a general formula (I), (I) exhibit in which R independently for any saturated or unsaturated, linear or branched, aliphatic residue with 1 to 8 carbon atoms and / or saturated or unsaturated cycloaliphatic residue with 5 to 8 carbon atoms, each being substituted or unsubstituted and / or having heteroatoms in the chain, preferably in which R independently represents any saturated or unsaturated, linear or branched, aliphatic residue with 1 to 4 carbon atoms, each being substituted or unsubstituted and / or having heteroatoms in the chain, particularly preferably in which R independently represents any saturated or unsaturated, linear or branched, aliphatic residue with 2 to 4 carbon atoms.

5. One-component system according to one of claims 1 to 4, characterized in that for the production of the blocked polyisocyanate component a) as polyisocyanate A) polyisocyanates are used which have an isocyanate group content of 6.0 to 26.0 wt.%, preferably of 8.0 to 25.0 wt.%, particularly preferably of 10.0 to 24.0 wt.%, and / or a monomeric diisocyanate content of less than 0.50 wt.%, preferably less than 0.30 wt.%, more preferably less than 0.20 wt.%, particularly preferably less than 0.10 wt.%.

6. One-component system according to one of claims 1 to 5, characterized in that the binder b) comprises or consists of polyester polyols, polyether polyols, polycarbonate polyols and / or polyacrylate polyols or any mixtures of such polyols, preferably comprising or consisting of polyester polyols and / or polyacrylate polyols.

7. One-component system according to any one of claims 1 to 6, characterized in that the binder b) is used in such an amount that the equivalent ratio of the sum of blocked and unblocked isocyanate groups of the polyisocyanate component a) to isocyanate-reactive groups of the binder b) is from 0.5 : 1 to 1.5 : 1, particularly preferably from 0.7 : 1 to 1.3 : 1, most preferably from 0.8 : 1 to 1.2 :

1.

8. One-component system according to one of claims 1 to 7, characterized in that one or more catalysts c) are included in amounts of 0.001 wt.% to 6 wt.%, preferably 0.002 wt.% to 5 wt.%, particularly preferably 0.005 wt.% to 2 wt.% and most preferably 0.005 wt.% to 1 wt.%, calculated as the sum of all catalysts c) used and based on the total amount of solvent-free blocked polyisocyanate a) and solvent-free binder component b).

9. A method for producing one-component systems according to any one of claims 1 to 8, characterized in that the blocked polyisocyanate component a) is mixed with the binder b), optionally with the use of catalysts accelerating the crosslinking reaction c) and optionally solvents and / or optionally auxiliary and additive substances d) at temperatures below the unblocking temperature of component a), preferably at temperatures between 15 and 100°C.

10. A method for producing a shaped body or an adhesive between two substrates or a coating on a substrate by reacting a one-component system according to any one of claims 1 to 8 under the influence of heat, preferably by baking in temperature ranges of 90 to 210°C, more preferably 110 to 160°C, more preferably 120 to 140°C, or by reacting a one-component system obtainable or produced according to the method according to claim 9 under the influence of heat, more preferably by baking in temperature ranges of 90 to 210°C, more preferably 110 to 160°C, more preferably 120 to 140°C.

11. Use of the one-component system according to any one of claims 1 to 8 as heat-curing solvent-free, solvent-containing or aqueous coating systems, preferably heat curing is carried out by baking in temperature ranges of 90 to 210°C, preferably 110 to 160°C, particularly preferably 120 to 140°C.

12. Use of the one-component systems according to any one of claims 1 to 8 in coil coating applications at peak metal temperatures between 130 and 300°C, preferably 190 to 260°C.

13. Molded body or bonded substrate comprising a cured one-component system according to any one of claims 1 to 8 or comprising a product obtainable or manufactured by the method according to claim 10 or 11.

14. Substrate, at least partially coated with at least one hardened single-component system according to one of claims 1 to 8 or at least partially coated with at least one hardened single-component system, obtainable or produced according to the method according to claim 10 or 11.

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