Water-based radiation-curable polyurethane dispersions having excellent properties in use

Abstract

The present invention relates to radiation-curable polyurethane dispersions having a particularly high double-bond density. These polyurethane dispersions can be used independently as coating agents, or especially advantageously added to conventional polyacrylate dispersions or to radiation-curing polyurethane dispersions in order to improve the properties in use thereof.

Description

[0001] Water-based radiation-curable polyurethane dispersions with excellent application properties

[0002] The present invention relates to radiation-curable polyurethane dispersions with a particularly high double bond density. These polyurethane dispersions can be used independently as coating agents or, particularly advantageously, as additives to conventional polyacrylate dispersions or radiation-curing polyurethane dispersions to improve their performance properties.

[0003] Polyacrylate dispersions are frequently used coating materials because their production is very cost-effective. However, their application properties are often not entirely satisfactory. If a high-quality coating is required, two-component polyurethane dispersions are a better alternative. However, due to the reactivity of the isocyanate used as a crosslinker, these have a limited pot life and often require special equipment for application. They are also more expensive than polyacrylate dispersions.

[0004] The study underlying the present invention has shown that the hydrophilicity (measured, for example, by acid number) and the double bond density of the dispersion are crucial for ensuring good miscibility with polyacrylate dispersions and improving the performance properties of this polyacrylate dispersion. This applies in particular to blocking resistance and chemical resistance. It should be emphasized that the dispersions according to the invention do not contain any additional cosolvents besides the reactive diluent.

[0005] EP 1 869 097 describes very generic compositions containing an ethylenically unsaturated oligomer and a resin free of energy-curing functional groups. No oligomers with the properties of the invention are described.

[0006] EP 0 453 838 describes urethane oligomers that have a high density of ethylenically unsaturated groups. However, the acid number is lower and the oligomers contain a cosolvent.

[0007] JP 2008-303258 describes nonionically hydrophilized urethane acrylates. Due to the nonionic hydrophilization, these have no acid number and thus differ from the reaction products of the invention.

[0008] US 2016 / 0304742 describes a polyurethane polymer obtained by chain extension of an isocyanate-terminated prepolymer. Due to the quantitative ratio of the building blocks, the oligomer contained in the dispersion according to the invention no longer has any free isocyanate groups even without chain extension. The present invention is defined by the patent claims and the embodiments described in the following description.

[0009] In a first embodiment, the present invention relates to an aqueous composition comprising a product obtained or obtainable from the reaction of a reaction mixture comprising a) a polyisocyanate component A having an average isocyanate functionality of at least 2.2 NCO groups per molecule; b) at least one ionic or potentially ionic hydrophilizing compound B having at least one isocyanate-reactive group per molecule; and c) a radiation-curable component C containing at least 2 (meth)acrylate groups per molecule; wherein the composition has a double bond density of at least 7 mol / kg based on its total weight.

[0010] The term "reaction mixture" refers to a mixture containing components A, B and C and optionally at least one catalyst in a form that enables a reaction in which hydroxyl groups and isocyanate groups are crosslinked to form urethane groups.

[0011] In a preferred embodiment, the reaction mixture consists of at least 90 wt.%, more preferably at least 95 wt.% and particularly preferably at least 98 wt.% of components A, B and C, based on the total weight of all compounds present therein, with the exception of water and inert solvents.

[0012] The product of the reaction of components A, B and optionally C preferably has an acid number of at least 80 mg KOH / g.

[0013] The molar ratio of hydroxyl groups to isocyanate groups in the reaction mixture is preferably between 1 : 1 and 1.2 : 1 at the start of the reaction.

[0014] The term "inert solvents" refers to organic compounds that serve as solvents for the components of the reaction mixture but are themselves incapable of reacting with isocyanate groups or hydroxyl groups. They also do not contain any radiation-curable groups, in particular no ethylenically unsaturated groups. The addition of such inert solvents during synthesis may be useful; they are separated by distillation during the preparation of the aqueous composition according to the invention. Preferred inert solvents are N-methylpyrrolidone, N-ethylpyrrolidone, butyl acetate, ethyl acetate, methoxypropyl acetate, diethylene glycol dimethyl ether, dioxane, dimethylformamide, xylene, toluene, solvent naphtha, cyclohexanone, methyl isobutyl ketone, diethyl ketone, methyl ethyl ketone, and acetone.

[0015] The reaction of the polyisocyanate component A present in the reaction mixture with the ionically or potentially ionically hydrophilizing compound B leads to a product which is hereinafter also referred to as the "inventive reaction product". The acid number of the product is preferably determined according to DIN EN ISO 2114:2002-06.

[0016] If component C contains hydroxy-functional molecules, the following reaction products are present in the aqueous composition according to the invention: (i) molecules composed only of components A and B and (ii) molecules composed of components A, B, and C. Since a hydroxy-functional component C also contains molecules that do not have free hydroxyl groups due to the low OH number, free molecules of component C will also always be present. In this case, the "product" having the acid number according to the invention is a mixture of the reaction products (i) and (ii).

[0017] Based on its total weight, the aqueous composition according to the invention preferably contains less than 5% by weight, more preferably less than 1% by weight, of inert solvents.

[0018] Polyisocyanate component A

[0019] The term "polyisocyanate component A" refers to the totality of all compounds in the reaction mixture that carry at least one isocyanate group per molecule. It is essential to the invention that all constituents of the polyisocyanate component have on average at least 2.2 isocyanate groups per molecule, i.e., the presence of molecules with an isocyanate functionality of less than 2.2 must be balanced by the presence of a sufficient number of molecules with an isocyanate functionality of more than 2.2.

[0020] The polyisocyanate component A preferably contains polyisocyanates. The term "polyisocyanate," as used here, is a collective term for compounds that contain two or more isocyanate groups in the molecule (by this, the person skilled in the art understands free isocyanate groups of the general structure -N=C=O). The simplest and most important representatives of these polyisocyanates are the diisocyanates. These have the general structure O=C=NRN=C=O, where R usually stands for aliphatic, alicyclic, araliphatic and / or aromatic radicals. The term "polyisocyanates" in this application refers equally to monomeric and / or oligomeric polyisocyanates. However, to understand many aspects of the invention, it is important to distinguish between monomeric diisocyanates and oligomeric polyisocyanates. When "oligomeric polyisocyanates" are mentioned in this application, this refers to polyisocyanates that are composed of at least two monomeric diisocyanate molecules, i.e.They are compounds that represent or contain a reaction product of at least two monomeric diisocyanate molecules.

[0021] The production of oligomeric polyisocyanates from monomeric diisocyanates is also referred to here as the modification of monomeric diisocyanates. This "modification," as used here, means the reaction of monomeric diisocyanates with, if appropriate, other isocyanate-reactive molecules to form oligomeric polyisocyanates with uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione, and / or oxadiazinetrione structures.

[0022] For example, hexamethylene-1,6-diisocyanate (HDI) is a “monomeric diisocyanate” because it contains two isocyanate groups and is not a reaction product of at least two polyisocyanate molecules:

[0023] HDI

[0024] In contrast, reaction products of at least two HDI molecules, which still have at least two isocyanate groups, are "oligomeric polyisocyanates" within the meaning of the invention. Representatives of such "oligomeric polyisocyanates" starting from the monomeric HDI are, for example, HDI isocyanurate and HDI biuret, which are each composed of three monomeric HDI molecules:

[0025] HDI-isocyanurate HDI-biuret

[0026] (idealized structural formulas) The weight fraction of isocyanate groups based on the total amount of polyisocyanate component A is preferably at least 5 wt.%. More preferably, at least 10 wt.%.

[0027] In principle, monomeric and oligomeric polyisocyanates are equally suitable for use in the reaction mixture according to the invention. Consequently, polyisocyanate component A can consist of monomeric polyisocyanates or essentially of oligomeric polyisocyanates. However, it can also contain oligomeric and monomeric polyisocyanates in any mixing ratio, provided that it has the NCO content defined further below in this application.

[0028] In a preferred embodiment of the invention, however, polyisocyanate component A contains at least one oligomeric polyisocyanate. Preferably, polyisocyanate component A has a monomeric diisocyanate content of at most 60 wt. %, more preferably at most 50 wt. %, even more preferably at most 40 wt. %, and particularly preferably at most 5.0 wt. %, based in each case on the weight of polyisocyanate component A.

[0029] Polyisocyanate compositions that are low in monomer content or essentially free of monomeric isocyanates can be obtained by carrying out at least one further process step after the actual modification reaction to remove the unreacted excess monomeric diisocyanates. This monomer removal can be carried out particularly practically using conventional methods, preferably by thin-film distillation under high vacuum or by extraction with suitable solvents that are inert toward isocyanate groups, for example, aliphatic or cycloaliphatic hydrocarbons such as pentane, hexane, heptane, cyclopentane, or cyclohexane.

[0030] According to a preferred embodiment of the invention, a low-monomer oligomeric polyisocyanate is obtained by modifying monomeric diisocyanates with subsequent separation of unreacted monomers.

[0031] According to a further particular embodiment of the process according to the invention, the polyisocyanate component A contains monomeric isocyanates with an isocyanate functionality greater than two, i.e., with more than two isocyanate groups per molecule. The addition of monomeric isocyanates with an isocyanate functionality greater than two can serve to adjust the average isocyanate functionality of the polyisocyanate component A. Monomeric isocyanates with an isocyanate functionality > 2 are, for example, triisocyanatononane and PMDI.

[0032] According to the invention, the oligomeric polyisocyanates may, in particular, have uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione, and / or oxadiazinetrione structures. According to one embodiment of the invention, the oligomeric polyisocyanates have at least one of the following oligomeric structure types or mixtures thereof:

[0033] Uretdione Isocyanurate Allophanate Biuret Iminooxadiazindione Oxadiazintrione

[0034] According to a preferred embodiment of the invention, a polyisocyanate component A is used whose isocyanurate structure content is at least 50 mol%, preferably at least 60 mol%, more preferably at least 70 mol%, even more preferably at least 80 mol%, even more preferably at least 90 mol% and particularly preferably at least 95 mol%, based on the sum of the oligomeric structures present from the group consisting of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and oxadiazinetrione structure in the polyisocyanate component A.

[0035] According to a further preferred embodiment of the invention, a polyisocyanate component A which, in addition to the isocyanurate structure, contains at least one further oligomeric polyisocyanate with uretdione, biuret, allophanate, iminooxadiazinedione and oxadiazinetrione structure and mixtures thereof, is used in the process according to the invention.

[0036] The proportions of uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione, and / or oxadiazinetrione structures in polyisocyanate component A can be determined, for example, by NMR spectroscopy. 13C NMR spectroscopy, preferably proton-decoupled, is preferred, since the aforementioned oligomeric structures yield characteristic signals.

[0037] Particularly practical results are achieved when the polyisocyanate component A to be used according to the invention has an isocyanate group content of 8.0 to 40.0 wt.%, preferably 14.0 to 37.0 wt.%, particularly preferably 20.0 to 35.0 wt.%, in each case based on the weight of the polyisocyanate component A.

[0038] Manufacturing processes for the oligomeric polyisocyanates with uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure that can be used in polyisocyanate component A are described, for example, in J. Prakt. Chem. 336 (1994) 185 - 200, in DE-A 1 670 666, DE-A 1 954093, DE-A 2 414413, 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 and EP-A 0 798 299.

[0039] According to an additional or alternative embodiment of the invention, polyisocyanate component A is defined as containing oligomeric polyisocyanates obtained from monomeric diisocyanates, regardless of the type of modification reaction used, while maintaining a degree of oligomerization of 5 to 45%, preferably 10 to 40%, particularly preferably 15 to 30%. "Degree of oligomerization" is understood to mean the percentage of the isocyanate groups originally present in the starting mixture that is consumed during the preparation process to form urethane, uretdione, isocyanurate, allophanate, biuret, iminooxadiazinedione, and / or oxadiazinetrione structures.

[0040] Suitable polyisocyanates for producing the polyisocyanate component A to be used according to the invention and the monomeric and / or oligomeric polyisocyanates contained therein are any polyisocyanates accessible in various ways, for example by phosgenation in the liquid or gas phase or by a phosgene-free route, such as by thermal urethane cleavage. Particularly good results are achieved when the polyisocyanates are monomeric diisocyanates. Preferred monomeric diisocyanates are those which have a molecular weight in the range from 140 to 400 g / mol and contain aliphatically, cycloaliphatically, araliphatically and / or aromatically bound isocyanate groups, such as, for example, B. 1,4-diisocyanatobutane (BDI), 1,5-diisocyanatopentane (PDI), 1,6-diisocyanatohexane (HDI), 2-methyl-l,5-diisocyanatopentane, l,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or2,4,4-Trimethyl-l,6-diisocyanatohexane, 1,10-Diisocyanatodecane, 1,3- and 1,4-Diisocyanatocyclohexane, l,4-Diisocyanato-3,3,5-trimethylcyclohexane, l,3-Diisocyanato-2-methylcyclohexane, l,3-Diisocyanato-4-methylcyclohexane, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (Isophorone diisocyanate; I PDI), l-isocyanato-l-methyl-4(3)-isocyanatomethylcyclohexane, 2,4'- and 4,4'-Diisocyanatodicyclohexylmethane (H12MDI), 1,3- and 1,4-Bis(isocyanatomethyl)cyclohexane, Bis-(isocyanatomethyl)-norbornane (NBDI), 4,4'-Diisocyanato-3,3'- dimethyldicyclohexylmethane, 4,4'-diisocyanato-3,3',5,5'-tetramethyldicyclohexylmethane, 4,4'-.

[0041] Diisocyanato-l,l'-bi(cyclohexyl), 4,4'-diisocyanato-3,3'-dimethyl-l,l'-bi(cyclohexyl), 4,4'-diisocyanato-2,2',5,5'-tetra-methyl-l,l'-bi(cyclohexyl), 1,8-diisocyanato-p-menthane, 1,3- Diisocyanato-adamantane, l,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and 1,4-bis-

[0042] (Iso-cyanatomethyl)benzene (xylylene diisocyanate; XDI), 1,3- and l,4-bis(l-isocyanato-l-methylethyl)benzene (TMXDI) and bis(4-(l-isocyanato-l-methylethyl)phenyl) carbonate, 2,4- and 2,6-diisocyanatotoluene (TDI), 2,4'- and 4,4'-diisocyanatodiphenylmethane (MDI), 1,5-diisocyanatonaphthalene and any mixtures of such diisocyanates. Other suitable diisocyanates can also be found, for example, in Justus Liebig's Annalen der Chemie Volume 562 (1949), pages 75 - 136. Suitable monomeric monoisocyanates which can optionally be used in the polyisocyanate component A are, for example, n-butyl isocyanate, n-amyl isocyanate, n-hexyl isocyanate, n-heptyl isocyanate, n-octyl isocyanate, undecyl isocyanate, dodecyl isocyanate, tetradecyl isocyanate, cetyl isocyanate, stearyl isocyanate, cyclopentyl isocyanate, cyclohexyl isocyanate, 3- or 4-methylcyclohexyl isocyanate or any mixtures of such monoisocyanates.As an example of a monomeric isocyanate with an isocyanate functionality greater than two, which can optionally be added to the polyisocyanate component A, 4-isocyanatomethyl-1,8-octane diisocyanate (triisocyanatononane; TIN) may be mentioned.

[0043] According to a preferred embodiment of the invention, polyisocyanate component A contains at most 30 wt. %, in particular at most 20 wt. %, at most 15 wt. %, at most 10 wt. %, at most 5 wt. %, or at most 1 wt. %, based in each case on the total weight of polyisocyanate component A, of aromatic polyisocyanates. As used herein, "aromatic polyisocyanate" means a polyisocyanate having at least one aromatically bound isocyanate group. Aromatically bound isocyanate groups are understood to mean isocyanate groups bonded to an aromatic hydrocarbon radical.

[0044] According to a particularly preferred embodiment of the invention, polyisocyanate component A consists of at least 90, more preferably 95, even more preferably 98, and most preferably 99 wt. %, based in each case on the total weight of polyisocyanate component A, polyisocyanates containing exclusively aliphatically and / or cycloaliphatically bound isocyanate groups. Practical experiments have shown that particularly good results can be achieved with polyisocyanate component A in which the isocyanates contained therein contain exclusively aliphatically and / or cycloaliphatically bound isocyanate groups.

[0045] Aliphatically or cycloaliphatically bound isocyanate groups are understood to be isocyanate groups that are bound to an aliphatic or cycloaliphatic hydrocarbon radical.

[0046] According to a further particularly preferred embodiment of the process according to the invention, a polyisocyanate component A is used which consists of or contains one or more oligomeric polyisocyanates, wherein the one or more oligomeric polyisocyanates have exclusively aliphatically and / or cycloaliphatically bound isocyanate groups.

[0047] According to a particularly preferred embodiment of the process according to the invention, a polyisocyanate component A is used which consists of or contains one or more oligomeric polyisocyanates, wherein the one or more oligomeric polyisocyanates are based on 1,4-diisocyanatobutane (BDI), 1,5-diisocyanatopentane (PDI), 1,6-diisocyanatohexane (HDI), isophorone diisocyanate (IPDI) or 4,4'-diisocyanatodicyclohexylmethane (H12MDI) or mixtures thereof.

[0048] Ionic or potentially ionic hydrophilizing compound B

[0049] In order for the reaction product according to the invention to have the acid number defined above, the use of an ionic or potentially ionic hydrophilizing group is essential. Compounds with non-ionic hydrophilizing groups can also be used, as long as the proportions are chosen such that the acid number required according to the invention is achieved.

[0050] The ionic or potentially ionic hydrophilizing compound B contains at least one isocyanate-reactive group. The term "isocyanate-reactive group" refers to all functional groups that have at least one Zerewitinoff-active hydrogen atom. The term preferably refers to hydroxyl, amino, and thiol groups, particularly preferably hydroxyl groups.

[0051] The ionically or potentially ionically hydrophilizing compounds are preferably hydroxy- or aminocarboxylic acids, preferably mono- and dihydroxycarboxylic acids, mono- and diaminocarboxylic acids, mono- and dihydroxysulfonic acids, mono- and diaminosulfonic acids and mono- and dihydroxyphosphonic acids or mono- and diaminophosphonic acids and their salts. More preferably, it is at least one compound selected from the group consisting of dimethylolpropionic acid, dimethylolbutyric acid, hydroxypivalic acid, N-(2-aminoethyl)alanine, 2-(2-aminoethylamino)ethanesulfonic acid, ethylenediaminepropyl acid, ethylenediaminebutylsulfonic acid, 1,2- and 1,3-propylenediamineethylsulfonic acid, malic acid, citric acid, glycolic acid, lactic acid, glycine, alanine, taurine, lysine, 3,5-diaminobenzoic acid, polyethersulfonate, the adduct of sodium bisulfite with butene-2-diol-1,4 and the alkali and ammonium salts of the aforementioned compounds.Even more preferably, at least one compound selected from the group consisting of 2,2-dimethylolacetic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid, dihydroxysuccinic acid, and α,α-diaminovaleric acid is used as compound B. 2,2-dimethylolpropionic acid is particularly preferred as compound B. Alternatively, monohydroxy-functional compounds having at least one carboxylic acid group, such as hydroxypivalic acid or hydroxydecanoic acid, can also be used. Mixtures of two or more of the aforementioned compounds are likewise preferred. Less preferably, polyhydroxy acids, in particular gluconic acid, can also be used as compound B. The above-mentioned acids are converted into the corresponding salts by reaction with neutralizing agents, such as triethylamine, ethyldiisopropylamine, dimethylcyclohexylamine, dimethylethanolamine, ammonia, N-methylmorpholine, NaOH, LiOH, and / or KOH.For neutralizing agents that do not react with isocyanates, this can be done at any time during production up to and including the dispersing step. The degree of neutralization, i.e., the number of equivalents of neutralizing agent relative to the number of equivalents of potentially ionic groups, can be between 30 and 150%, preferably between 50 and 110%.

[0052] Optionally used non-ionic hydrophilizing compounds are polyalkylene oxide polyether alcohols or polyalkylene oxide polyether amines, in particular polyethylene oxide polyethers or mixed polyalkylene oxide polyethers, whose alkylene oxide units consist of at least 30 mol% ethylene oxide units.

[0053] Radiation-curable component C

[0054] The term "radiation-curable component C" refers to all compounds present in the reaction mixture with two or more ethylenically unsaturated groups. These ethylenically unsaturated groups are preferably (meth)acrylate groups. It is preferred that at least 80 mol%, preferably at least 90 mol%, and particularly preferably at least 95 mol% of the molecules contained in component C have a molecular weight between 170 and 800 g / mol. However, due to production reasons, it cannot be ruled out that individual molecules oligomerize during synthesis, so that component C may also contain a small proportion of larger molecules.

[0055] According to the invention, it is possible to use a mixture of two or more compounds having the features defined here as radiation-curable component C.

[0056] In a preferred embodiment of the present invention, the radiation-curable component C contains at least one (meth)acrylate ester containing an alcohol selected from the group consisting of 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,10-decanediol, 1,12-dodecanediol, 1,3-butanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4- and 1,6-dimethylolcyclohexane, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, diglycerol, ditrimethylolpropane, Dipentaerytritol, sorbitol and alkoxylated derivatives of the above alcohols.

[0057] In a particularly preferred embodiment of the present invention, the radiation-curable component C contains at least one (meth)acrylate ester containing an alcohol selected from the group consisting of pentaerythritol, ditrimethylolpropane, dipentaerythritol, and alkoxylated derivatives of the above alcohols.

[0058] In a further particularly preferred embodiment, component C consists, based on its total weight, of at least 60 wt.%, preferably at least 80 wt.%, more preferably at least 90 wt.% and particularly preferably at least 95 wt.% of one or more of the compounds defined in the preceding paragraph.

[0059] In a further preferred embodiment of the present invention, compound C is hydrofunctional. If component C is hydroxyfunctional, it has an OH number between 1 and 60, preferably between 5 and 60 mg KOH / g, according to the invention, preferably determined according to DIN EN ISO 4629-2:2015-02. For the advantageous properties of the aqueous composition, it is essential that the upper limit of 60 mg KOH / g is adhered to.

[0060] Catalyst D

[0061] To accelerate the reaction, in a preferred embodiment of the present invention, the reaction mixture additionally contains a catalyst D. Suitable catalysts for accelerating the reaction are, in principle, all those that catalyze the reaction of isocyanate groups with hydroxyl groups. These are known to the person skilled in the art or can be found in the current literature on urethane synthesis. Tertiary amines, tin, zinc, zirconium, copper, and / or bismuth compounds are particularly suitable, preferably triethylamine, ethyldiisopropylamine, dimethylcyclohexylamine, N-methylmorpholine, 1,4-diazabicyclo-[2,2,2]octane, dibutyltin oxide, dibutyltin dilaurate, tin(II) 2-ethylhexyloctoate, and bismuth(III) 2-ethylhexyloctoate. Also suitable are salts of zinc, titanium, and molybdenum. Suitable amounts are, for example, 0.002 to 2.5 wt.%, preferably 0.01 to 1 wt.%, based on the total mass of the reaction mixture.The reaction can also be carried out without the use of a catalyst.

[0062] Manufacturing process

[0063] The dispersions according to the invention are prepared at temperatures from 20°C to 150°C, preferably from 25°C to 75°C. Components A, B, C, and optionally D, can be diluted with inert solvents at the start of the reaction. The inert solvent can also be added in any desired reaction step. The optionally used inert solvent can then be removed by distillation. Preparation without the use of inert solvents is possible, but preparation is preferably carried out in inert solvents. Preference is given to preparation in 3 to 50% by weight, based on the total mass of the reaction mixture, particularly preferably in 5 to 25% by weight, of an inert solvent, in particular acetone, with subsequent removal of the solvent by distillation after preparation of the dispersion or during the dispersing step.

[0064] In a preferred embodiment of the present invention, the aqueous composition is prepared without chain extension of the reaction product contained therein. This means that no increase in molecular weight occurs due to the reaction of any free isocyanate groups still present after the reaction of components A, B, and C using compounds with two or more hydroxyl, thiol, or amino groups per molecule. It is also preferred not to add any further polyisocyanates to the finished reaction product, which would lead to crosslinking of any free hydroxyl groups present.

[0065] Aqueous acrylate dispersion

[0066] In a further embodiment, the present invention relates to an aqueous coating composition comprising as component (i) at least one aqueous composition comprising a product as defined above in this application and as component (ii) at least one polyacrylate dispersion or at least one polyurethane dispersion or a mixture of at least one polyacrylate dispersion and at least one polyurethane dispersion.

[0067] In a preferred embodiment, the weight fraction of the solid of component (i) relative to the total mass of the total solid of components (i) and (ii) is 5 to 60 wt.%, preferably 10 to 50 wt.%, more preferably 20 to 30 wt.%.

[0068] In a particularly preferred embodiment of the present invention, the binder in the coating composition consists of at least 30 wt.%, based on its total weight, of components (i) and (ii). "Binder" is understood here to mean any compound or composition that imparts strength to the coating, in particular polymers with a number-average molecular weight of at least 5,000 g / mol. Pigments, UV stabilizers, catalysts, rheological additives, and inert solvents are not considered binder components.

[0069] Polyacrylate dispersion

[0070] In principle, all non-ionic and anionic polyacrylate emulsion polymers known in the art are suitable as component (ii). Such polymers are generally prepared by polymerizing acrylic and / or methacrylic acid esters of alkanols containing 1 to 10 carbon atoms. The polyacrylate emulsion polymers can contain up to 60% by weight of styrene, up to 20% by weight of vinyl esters, and / or up to 10% by weight of water-soluble monoolefinically unsaturated comonomers. Preferred water-soluble monoolefinically unsaturated comonomers are acrylic acid, methacrylic acid, itaconic acid, acrylamide, and methacrylamide. The polymerization is preferably carried out in an aqueous emulsion at 30 to 95°C in the presence of free-radical polymerization initiators, such as water-soluble peroxides, e.g., persulfates such as ammonium persulfate or potassium persulfate. In general, anionic and / or non-anionic emulsifiers are used in amounts of 0.1 to 5 wt.%.Such polymers and their preparation are described, for example, in EP0065162B1 or in U. Poth et al., Acrylic Resins, Vincentz Network, (2011). Self-crosslinking non-ionic and anionic polyacrylate emulsion polymers, such as those described in D. Mestach, FATIPEC Congress (2000), 25th (Vol. 2), 347-361, are also suitable.

[0071] Polyurethane dispersion

[0072] Anionic 1K polyurethane dispersions are also suitable as component (ii). These are high-molecular-weight, non-functional polyurethane dispersions known in the art. They preferably contain the reaction products of polyisocyanates with polyether polyols, polycarbonate polyols, and / or polyester polyols, as well as at least one of the hydrophilizing compounds defined above as component B. These reaction products preferably have a number-average molecular weight between 50,000 and 200,000 g / mol.

[0073] Anionic UV-curable polyurethane dispersions are also suitable as component (ii). Such dispersions are described in detail in U. Meier-Westhues, Polyurethane, Vincentz Network, (2007).

[0074] The study underlying the present invention has shown that the aqueous composition containing the reaction product according to the invention is well suited to improving the application properties of the aforementioned by blending with polyacrylate dispersions and / or polyurethane dispersions, even if the aqueous composition containing the reaction product according to the invention has a significantly lower proportion in the mixture than the polyacrylate and / or polyurethane dispersion.

[0075] Therefore, in a further embodiment, the present invention relates to the use of the aqueous composition defined above containing the reaction product according to the invention for improving the performance properties of a polyacrylate and / or polyurethane dispersion. The improved performance properties preferably relate to blocking resistance and / or chemical resistance. Chemical resistance preferably relates to resistance to iodine, ethanol, red wine, coffee, or water.

[0076] By blending conventional polyacrylate and polyurethane dispersions with the reaction product according to the invention, coating compositions can be obtained whose application properties are significantly improved compared to the pure dispersions and reach the level of two-component polyurethane dispersions. Unlike the known two-component compositions, however, the mixtures according to the invention have no pot life, since the reaction product according to the invention does not contain any free isocyanate groups.

[0077] In yet another embodiment, the present invention relates to a coating obtained or obtainable from the aqueous composition according to the invention comprising the above-defined reaction product according to the invention.

[0078] Blends of the reaction product according to the invention with polyurethane dispersions are particularly suitable for improving the abrasion resistance of plastic floor coverings, in particular those containing or consisting of polyvinyl chloride.

[0079] Blends of the reaction product according to the invention with polyacrylate dispersions are particularly suitable for improving the chemical resistance, especially resistance to coloring substances, of coatings on wood. At the same time, blocking resistance is increased. Polyurethane-polyacrylate hybrid dispersions are also suitable as component (ii) in the same way as polyacrylate dispersions. Highly suitable polyurethane-polyacrylate hybrid dispersions are described in CR Hegedus and KA Kloiber, Journal of Coatings Technology, Vol. 68, No. 860, September 1996, pp. 39-48.

[0080] In yet another embodiment, the present invention relates to a coating obtained or obtainable from the above-defined aqueous composition comprising at least one component (i) and at least one component (ii).

[0081] It is preferred that the coating be applied to a surface selected from the group consisting of wood, plastic, metal, and composite materials. The plastic is preferably polyvinyl chloride, and particularly preferably a floor covering containing or consisting of polyvinyl chloride.

[0082] The following embodiments serve only to illustrate the invention. They are not intended to limit the scope of the patent claims in any way.

[0083] Raw materials

[0084] DPPA - Dipentaerythritol pentaacrylate, available e.g. under the trade name Miramer M 500, Miwon Specialty Chemical Co.

[0085] DPHA - Dipentaerythritol hexaacrylate, available e.g. under the trade name Miramer M 600, Miwon Specialty Chemical Co, or AgiSyn 2830L, Covestro AG

[0086] PETiA - Pentaerythritol triacrylate, available e.g. under the trade name AgiSyn 2884, Covestro AG

[0087] Laromer PE 44 F - liquid polyester acrylate, free from reactive diluent, available from BASF SE

[0088] Desmodur N 3600 - Low viscosity HDI trimer, approx. 23% NCO, Covestro AG

[0089] Desmodur N 3300 - HDI trimer, approx. 22% NCO, Covestro AG

[0090] HDI - Hexamethylene diisocyanate

[0091] IPDI - Isophorone diisocyanate

[0092] DBTL - Dibutyltin dilaurate

[0093] Borchi Kat 24 - Bismuth catalyst, Borchers GmbH

[0094] Kosmos T9 - Tin di(2-ethylhexanoate), Evonik Operations GmbH

[0095] DMPS = 2,2-bis(hydroxymethyl)propionic acid

[0096] HPS = 2,2-dimethyl-3-hydroxypropionic acid

[0097] Bayhydrol A 2846 - a self-crosslinking hydroxy-functional polyacrylate dispersion, Covestro AG

[0098] Picassian AC-169 - an aqueous anionic, self-crosslinking styrene-acrylic copolymer emulsion, Stahl Holdings BV

[0099] Carboset CA7160 RC - a styrene-acrylic copolymer emulsion, Lubrizol Bayhydrol UV 2282 - a UV-curing, aqueous polyurethane dispersion, Covestro AG

[0100] Bayhydrol UV 2720 / 1 - a UV-curing, aqueous polyurethane dispersion, Covestro AG

[0101] Methods

[0102] Viscosity measurements were carried out using a Physica MCR 51 rheometer from Anton Paar Germany GmbH (DE) according to DIN EN ISO 3219:1994-10.

[0103] The NCO content was determined titrimetrically according to DIN EN ISO 11909:2007-05.

[0104] Determination of the non-volatile fraction (NF) was carried out using a convection oven according to DIN EN ISO 3251:2008-06, method B (lg / lh / 125°C)

[0105] The mean particle size (MTG) was determined using a Zetasizer Nano from Malvern (DE) according to DIN ISO 13321:2004-10

[0106] The pH value was determined using a pH meter according to DIN ISO 976:2008-07 in a dilution of 1:4 with distilled water.

[0107] Flow time - measurements were carried out according to DIN EN ISO 2431:2011 with a 4 mm cup at 23°C.

[0108] The gloss and haze values ​​were determined according to DIN EN ISO 2813: 2015 on black plexiglass, unless otherwise stated in the text.

[0109] Chemical resistance was determined according to DIN EN 68861-1 1B 2011_01 and IKEA IOS-MAT-066 R2 & R0 on melamine-foiled MDF boards, unless otherwise stated in the text. Immediate damage and damage after regeneration were recorded, if indicated accordingly. The test was carried out and evaluated according to DIN EN 12720 2014_2: 5 - no change, 1 - strong change.

[0110] The pencil hardness was determined on glass according to DIN EN ISO 15184 2020_05; unless otherwise stated in the text.

[0111] Pendulum hardness was measured on glass after 1 and 7 days according to DIN EN ISO 1522:2022 according to König. Abrasion resistance was determined according to ASTM D 4060-1 (Taber Abraser, 1000g weight CS 10 grinding wheel, 1000 circles).

[0112] The blocking strength was determined as follows: the coated substrates (equal size, melamine-foiled MDF boards) were placed on top of each other after irradiation so that the coated

[0113] The sides are in contact with each other, forming a cross. A weight is placed on top, with the corresponding load determined by the surface area of ​​the substrate and the mass of the weight. After the specified time, the weight is removed, and an attempt is made to manually separate the parts. Both the required force and the damage caused to the surfaces were assessed.

[0114] Force: Damage:

[0115] A - It is not possible to separate the parts 0 - It is not possible to separate the parts

[0116] B - Very high force to achieve separation 1 - Significant damage

[0117] 2 - Minor damage

[0118] C - High force to achieve separation

[0119] 3 - Visible markings

[0120] D - Average force to separate

[0121] 4 - Reach visible light stains

[0122] 5 - No damage

[0123] E - Light force to achieve separation

[0124] F - The parts are completely separated

[0125] Example 1 (according to the invention)

[0126] 69.13 g of DPPA, 212.50 g of DPHA, 68.50 g of Desmodur N 3600, 0.18 g of DBTL 24, and 65 g of acetone were placed in a reactor, heated to 60 °C, and stirred until a homogeneous mixture was formed. Then, 6.70 g of DMPS and 11.80 g of HPS were added, and stirring continued at 60 °C until the NCO content reached < 0.3 wt.%. 15.00 g of triethylamine was then added to the mixture. After a further 15 minutes, the mixture was dispersed with 481.68 g of water. Finally, acetone was removed by distillation under vacuum. A dispersion with the following characteristics was obtained: NCO 48 wt.%

[0127] Flow time (DIN 4mm, 23°C) 33 sec. pH value 7.3

[0128] MTG 69 nm Example 2 (according to the invention)

[0129] 1082.17 g of DPPA, 156.65 g of Desmodur N 3600, 92.61 g of HDI, 0.74 g of Borchikat 24, and 96 g of acetone were placed in a reactor, heated to 60°C, and stirred until a homogeneous mixture was formed. Then, 82.08 g of DMPS, followed by 223 g of acetone, were added to the mixture, and stirring was continued at 60°C until the NCO content reached <0.3 wt.%. 59.44 g of triethylamine was then added to the mixture. After a further 15 minutes, the mixture was dispersed with 1871.80 g of water. Finally, acetone was removed by distillation under vacuum. A dispersion with the following characteristics was obtained: NCO 43 wt.%

[0130] Flow time (DIN 4mm, 23°C) 32 sec. pH value 7.9

[0131] MTG 41 nm

[0132] Example 3 (according to the invention)

[0133] 530.04 g of DPPA, 81.90 g of Desmodur N 3300, 45.36 g of HDI, and 0.36 g of Borchikat 24 were placed in a reactor, heated to 60 °C, and stirred until a homogeneous mixture was formed. Then, 40.20 g of DMPS, followed by 156 g of acetone, were added to the mixture, and stirring was continued at 60 °C until the NCO content reached 0.2 wt.%. 25.80 g of triethylamine was then added to the mixture. After a further 15 minutes, the mixture was dispersed with 916.80 g of water. Finally, acetone was removed by distillation under vacuum. A dispersion with the following characteristics was obtained: NCO 40 wt.%

[0134] Viscosity (23°C, d=40 / s) 93 mPas pH value 7.8

[0135] MTG 94 nm

[0136] Example 4 (according to the invention)

[0137] 672.50 g of DPHA, 78.49 g of Desmodur N 3300, 43.47 g of HDI, and 0.35 g of Borchikat 24 were placed in a reactor, heated to 60°C, and stirred until a homogeneous mixture was formed. Next, 38.53 g of DMPS, followed by 150 g of acetone, were added to the mixture, and stirring was continued at 60°C until the NCO content reached 0.2 wt.%. 26.45 g of triethylamine was then added to the mixture. After a further 15 minutes, the mixture was dispersed with 954.50 g of water. Finally, acetone was removed by distillation under vacuum. A dispersion with the following characteristics was obtained: NCO 47 wt.%

[0138] Viscosity (23°C, d=40 / s) 107 mPas pH value 7.4

[0139] MTG 67 nm

[0140] Example 5 (according to the invention)

[0141] 658.78 g of DPHA, 68.25 g of Desmodur N 3300, 37.80 g of HDI, and 0.42 g of Borchikat 24 were placed in a reactor, heated to 60°C, and stirred until a homogeneous mixture was formed. 33.50 g of DMPS, followed by 130 g of acetone, were then added to the mixture, and stirring was continued at 60°C for 15 minutes. 23.00 g of triethylamine was then added to the mixture, and stirring was continued at 60°C until the NCO content reached <0.2 wt.%. The mixture was then dispersed with 830.00 g of water. Finally, acetone was removed by distillation under vacuum. A dispersion with the following characteristics was obtained: NCO 50 wt.%

[0142] Viscosity (23°C, d=40 / s): 150 mPas pH value 7.5

[0143] MTG 90 nm

[0144] Comparison example 6

[0145] 187.10 g of La romer PE 44F, 13.74 g of DMPS, 0.28 g of DBTL, 23.55 g of HDI, 47.67 g of IPDI, and 65 g of acetone were placed in a reactor, heated to 60 °C, and stirred at 60 °C until the NCO content reached 1.7 wt.%. The reaction mixture was then cooled to 50 °C. 116.79 g of DPHA were added and stirred for 15 minutes. In the next step, 9.55 g of triethylamine were added to the mixture and stirred for 15 minutes. The mixture was then dispersed with 591.24 g of water and chain-extended with a 3.42 g ethylenediamine / 11.5 g water mixture. Finally, acetone was removed by distillation under vacuum. A dispersion with the following characteristics was obtained: nfA 42 wt.%

[0146] Viscosity (23°C, d=40 / s) 35 mPas pH value 8.1

[0147] MTG 89 nm Comparison Example 7

[0148] 224.46 g of PETiA, 17.63 g of DMPS, and 149.98 g of dicyclohexylmethane-4,4'-diisocyanate were placed in a reactor and heated to 50 °C. 0.11 g of Kosmos T9 catalyst was then added in two portions while stirring. The reaction mixture was stirred at 60 °C until the NCO content reached 4.5 wt.%. The reaction mixture was then cooled to 50 °C. 13.32 g of triethylamine were added and stirred for 15 minutes. The mixture was then dispersed in 556.80 g of water and chain-extended with 52.60 g of a 64% hydrazine solution. After adjusting the solids content to approximately 40 wt.%, a dispersion with the following characteristics was obtained: nfA 40 wt.%

[0149] Viscosity (23°C, d=40 / s) 20 mPas pH value 8.5

[0150] MTG 65 nm

[0151] Comparative Examples 8-10 and Inventive Example 11:

[0152] DPPA and the PUD dispersion from inventive example 2 were mixed with a conventional polyacrylate dispersion (Bayhydrol A 2846):

[0153] Mixing was performed by hand using a wooden spatula. The resulting dispersions were stored at room temperature and at 40°C. The dispersions from Comparative Examples 8 to 10 showed clear phase separation just one day after mixing, while the inventive dispersion from Example 11 remained homogeneous and without visual change for two weeks at 40°C. These results confirm that the inventive dispersion from Example 2 can be easily and effortlessly incorporated into a commercially available polyacrylate dispersion, in contrast to reactive diluent, which does not contain the inventive reaction product. Performance tests of the inventive dispersion from Example 3, as well as the comparative dispersions from Examples 6 and 7, compared to a commercially available polyurethane dispersion, Bayhydrol UV 2282, were conducted using the formulations recorded in Tables 1 and 2.

[0154] Table 1. Compositions of white matt varnish based on dispersions from examples 3, 6 and 7, as well as a commercially available UV dispersion Bayhydrol UV 2282.

[0155] Tego® Airex 902W - defoamer, Evonik

[0156] Acematt® TS-100 - matting agent, Evonik Ceraflour® 929 - wax, BYK Chemie

[0157] Omnirad® 500 - Photoinitiator, IGM Resins

[0158] Omnirad® 819 - Photoinitiator, IGM Resins

[0159] Tego® Disperse 660C - Dispersant, Evonik Table 2. Composition of the pigment paste used in Examples 12 to 15

[0160] The coatings were applied with a manual air spray gun onto melamine-foiled MDF boards (single layer, layer thickness 120g / m 2 ), aired for 10 minutes at 22 °C / 50 % humidity, dried for 20 minutes at 45 °C and then irradiated with a UV lamp (Hg lamp, 120 W / cm 2+ Ga lamp, 120 W / cm 2 , belt speed approx. 7 m / min.). The irradiated panels were conditioned for 16 hours at 22°C prior to the application tests. The results of the application tests are listed in Table 3.

[0161] Table 3. Test results of the formulations from Examples 12 to 15

[0162] As Table 3 shows, the composition according to the invention from Example 3 allows the production of hard coatings (Example 12) with a satin gloss, which even surpass both the conventional UV polyurethane dispersions (Example 13) and the non-inventive chain-extended dispersions from Examples 6 and 7 (Examples 14 and 15) in terms of chemical resistance.

[0163] The dispersion from Example 5 was also formulated as a clearcoat, as shown in Table 4, and tested for performance in comparison to a clearcoat based on Bayhydrol UV 2282.

[0164] Table 4. Compositions of clear coat based on dispersions from Example 5 and a commercially available UV dispersion Bayhydrol UV 2282

[0165] Omnirad 1173 - Photoinitiator, IGM Resins

[0166] Byk 348 - Silicone surfactant for water-based coatings, Byk Chemie

[0167] AMP 90 - Buffer, Angus Chemical Co.

[0168] The coatings were applied with a box doctor blade to a corresponding substrate (single layer, layer thickness 150 μm wet), flashed off for 10 minutes at 23 °C / 45 % humidity, dried for 15 minutes at 50 °C and then irradiated with a UV lamp (Hg lamp, 80 W / cm 2, belt speed approx. 5 m / min.). The irradiated panels were conditioned for 16 hours at 23 °C prior to the application tests. The results of the application tests are listed in Table 5. Table 5. Test results of the formulations from Examples 16 and 17

[0169] The results of the performance tests in clearcoat formulations shown in Table 5 confirm that the composition according to the invention from Example 5 also leads to improved hardness, blocking resistance and better chemical resistance in clearcoat formulations (Example 16) than the commercially available polyurethane dispersion from Example 17.

[0170] The inventive dispersions from Examples 1 and 2 were also tested in blends with conventional non-UV-functional polyacrylate dispersions. The aim was to improve the properties by adding small amounts of the inventive dispersions. The coatings were applied with a box-type doctor blade to a suitable substrate (single layer with a layer thickness of 150 μm wet for the pendulum hardness and blocking resistance measurements), flashed off for 10 minutes at 23 °C / 45% humidity, dried for 15 minutes at 50 °C, and then irradiated with a UV lamp (Hg lamp, 80 W / cm 2, belt speed approx. 5 m / min.). For the chemical resistance test on beechwood, the coating was applied in two layers with a wet thickness of 150 μm. The irradiated panels were conditioned for 16 hours at 23 °C prior to the application tests. The substrates with comparative coatings from Examples 24 and 31 were tested after 7 days of conditioning at 23 °C. The results of the application tests are listed in Table 6.

[0171] Table 6 Compositions of clear coats based on dispersions from examples 1 and 2 in blends with conventional PAC dispersions.

[0172] Irgacure 500 - photoinitiator, BASF

[0173] Dowanol DPM and PNB - Solvents, Dow Chemicals

[0174] Table 7. Test results of the formulations from Examples 18 -31

[0175] *on beech wood

[0176] The following conclusion can be drawn from the data in Table 7:

[0177] In combination with Picassian AC-169, the inventive products demonstrate very good chemical resistance and a significant improvement in blocking resistance, as well as approximately 10% increased hardness compared to the unmodified polyacrylate dispersion. In combination with Carboset CA 7160, the inventive products also demonstrate improved blocking resistance and chemical resistance compared to the unmodified dispersion.

[0178] The dispersions from inventive example 3 and comparative example 7 were also tested in blends with a conventional non-UV-functional polyacrylate dispersion Bayhydrol A 2846. The coatings were applied to a corresponding substrate (single layer with a layer thickness of 180 μm) using a box-type doctor blade, flashed off for 10 minutes at 23 °C / 45% humidity, dried for 15 minutes at 50 °C and then irradiated with a UV lamp (Hg lamp, 80 W / cm 2 , belt speed approx. 5 m / min.). For the chemical resistance test on beechwood, two coats were applied, each with a wet thickness of 180 μm. The irradiated panels were conditioned at 23 °C for 24 hours prior to the application tests. The formulations and the results of the application tests are listed in Table 8.

[0179] Table 8 Compositions and test results of the clear coats based on dispersions from Examples 3 and 7 in blends with a conventional PAC dispersion Table 8 shows that even the addition of small amounts (20-30 wt. %) of the inventive dispersion from Example 3, as well as the comparative dispersion from Example 7, to a conventional polyacrylate dispersion, such as Bayhydrol A 2846, significantly improves chemical resistance. This applies particularly to resistance to coloring substances. However, only the inventive dispersion from Example 3 is also capable of significantly improving blocking resistance.

[0180] The dispersions of the invention can also be used to improve the properties of commercially available UV-curing polyurethane dispersions. Table 9 shows an example of such use.

[0181] The dispersions shown in Table 9 were applied to a corresponding substrate (single layer with a layer thickness of 36 μm) using a spiral doctor blade, flashed off for 10 minutes at 23 °C / 45% humidity, dried for 15 minutes at 50 °C and then irradiated with a UV lamp (Hg lamp, 80 W / cm 2 , belt speed approx. 15 m / min.).

[0182] Table 9 Compositions and test results of the clear coats based on dispersions from Examples 2 in blends with a conventional UV polyurethane dispersion DISPERBYK 191 - Dispersing additive for water-based coating systems, Byk Chemie

[0183] DEUTERON MK - matting agent, Deuteron GmbH

[0184] BYK-093 - silicone-based defoamer for waterborne coating systems, Byk Chemie

[0185] ESACURE KIP 100 F - Photoinitiator, IGM Resins

[0186] TAFIGEL PUR 45 - Associative thickener, Münzing Chemie

[0187] Table 9 confirms that the inventive dispersion from Example 2, even in small amounts (20-30 wt%), significantly improves the resistance of a conventional UV-curing coating to strongly coloring substances. The abrasion resistance of the coatings based on the mixtures is also significantly higher. The inventive dispersion from Example 2 is also well compatible with the Bayhydrol UV dispersion, which is reflected in good gloss values ​​and even better haze values. The combination of these properties would represent a technical advantage, particularly in the field of PVC floor coatings.

[0188] Comparison Example 32 (Comparison)

[0189] Example lb from US 2018 / 0244948 was reproduced, whereby the proportion of component B

[0190] (Dipropylene glycol diacrylate) was increased so that a double bond density of 6 mol / kg (6 mmol / g) was achieved.

[0191] 19.63 g dimethylolpropionic acid, 90.87 g 2-hydroxyethyl acrylate, 20.25 g polyethylene glycol monoethyl ether MPEG 1000 (TCI Deutschland GmbH), 9.96 g 1,4-cyclohexanedimethanol, 14.47 g Baycoll AD 1225 (Covestro AG, Leverkusen), 29.74 g hexamethylene diisocyanate trimer (Desmodur N 3300, Covestro AG, Leverkusen), 43.69 g 4,4'-diisocyanatodicyclohydroxylmethane (Desmodur W, Covestro AG, Leverkusen), 201.18 g isophorone diisocyanate trimer (Vestanat T 1890 / 100, Evonik Industries, Essen), 0.21 g 3,5-di-tert-butyl-4-hydroxyloluene and 0.09 g 4-Oxypiperidol (4-hydroxy-TEMPO) was placed in a stirred vessel and diluted by adding 108 g of methyl ethyl ketone. After adding 0.30 g of zinc neodecanoate, the mixture was heated to 80 °C. The reaction progress was monitored by measuring the NCO content. At an NCO content of <0.40 wt.%, the mixture was further diluted by adding 1000 g of acetone. The amount of acetone was adjusted to accommodate the increased amount of the mixture.Then, 850 g of Laromer DPGDA (dipropylene glycol diacrylate) was added as component B. The amount of component B was selected so that the final dispersion had a double bond density of 6 mmol / g. The resulting mixture was neutralized by adding 41.02 g of aqueous NaOH solution (10 wt%) and dispersed in 1900 g of deionized water. The amount of water was adjusted to the increased amount of solids, resulting in a dispersion with a solids content of 40 wt%. The solvents were then removed by distillation. A dispersion with the following characteristics was obtained: nfA (calculated) 40 wt%.

[0192] Viscosity (23°C) 18 mPas

[0193] MTG 18 nm

[0194] Due to azeotrope formation between Laromer DPGDA and water, the non-volatile fraction of the dispersion (nfA) could not be measured and was calculated.

[0195] After two weeks of storage at room temperature, the characteristics were measured again. The mean particle size increased to 349 nm and remained bimodal; the viscosity increased to 66 mPas. This change in the characteristics indicates that the dispersion is not storage-stable. Furthermore, the very high mean particle size (from the beginning, but especially after storage) indicates that the dispersion is unsuitable as a coating. Despite all this, the dispersion was subjected to coating technology tests.

[0196] Coating test of the comparison dispersion in white pigmented formulation analogous to Examples 12, 13, 14 and 15 shown in Table 1:

[0197] Table 10: Reproduction of Example 1b from US 2018 / 0244948

[0198] The coating was applied and cured as described for the above examples. The test results, analogous to Table 3, are presented in Table 12 below. Overall, the chemical resistance was lower than for Example 12 according to the invention. It was also striking that the comparison dispersion did not form a continuous film at all, and the surface was full of gel particles. Furthermore, despite the high double bond density, the film exhibited very low pendulum hardness.

[0199] The comparison dispersion was also tested in a clear coat formulation analogous to Table 4 (Examples 16 and 17):

[0200] Table 11: Formulation as clear coat

[0201] The clearcoat was applied and cured as described there. The test results are shown in Table 13. All films with the comparison dispersion showed blisters after exposure and slightly lower resistance. However, the blocking resistance of the film with the comparison dispersion was particularly poor compared to the dispersion according to the invention.

[0202] Table 12: Results of the application testing of the comparison dispersion Table 13: Further results of the application testing of the comparison dispersion

[0203] Comparison Example 33 (Comparison)

[0204] Example 1b of US 2018 / 0244948 and the preparation process of the dispersions according to the invention differ in the time of addition of the hydroxy-functional radiation-curable component C (in US 2018 / 0244948: component B). Therefore, it was examined whether the time of addition of this component has a technical effect.

[0205] Example 5 according to the invention was modified by adding DPHA after urethanization, analogous to Example 1 from US 2018 / 0244948. This component was therefore not part of the original reaction mixture.

[0206] 33.50 g of DMPS, 68.25 g of Desmodur N 3300 (Covestro Deutschland AG, Leverkusen), 37.80 g of HDI, 0.42 g of Borchikat 24 (Borchers GmbH, Langenfeld), and 108 g of methyl ethyl ketone were placed in a reactor, heated to 80 °C, and stirred. A homogeneous mixture was formed, but it solidified very quickly and could no longer be dissolved despite the addition of 130 g of acetone. Thus, the preparation of a dispersion was not possible.

[0207] Consequently, it is necessary that component C is also present in the reaction mixture from the beginning of the reaction and is not added subsequently.

Claims

Patent claims 1. An aqueous composition comprising a product obtained or obtainable from the reaction of a reaction mixture comprising a) a polyisocyanate component A having an average isocyanate functionality of at least 2.2 NCO groups per molecule; b) at least one ionic or potentially ionic hydrophilizing compound B having at least one hydroxyl group per molecule; and c) a radiation-curable component C containing at least 2 (meth)acrylate groups per molecule; The composition has a double bond density of at least 7 mol / kg based on its total weight.

2. The aqueous composition according to claim 1, wherein the radiation-curable component C is hydroxy-functional.

3. The aqueous composition according to claim 2, wherein component C has an OH number between 1 and 60.

4. The composition according to any one of claims 1 to 3, wherein a) in the presence of a radiation-curable component C which is free of hydroxyl groups, the product of the reaction of components A and B; or b) in the presence of a hydroxy-functional radiation-curable component C, the product of the reaction of components A, B and C has an acid number of at least 80 mg KOH / g.

5. The composition according to any one of claims 1 to 4, wherein component C has a weight fraction of at least 50 wt.% based on the sum of the weight fractions of components A, B and C.

6. The composition according to any one of claims 1 to 5, wherein the polyisocyanate component A consists of at least 90 wt.% of its total weight of aliphatic and / or cycloaliphatic polyisocyanates.

7. The composition according to any one of claims 1 to 6, wherein the polyisocyanate component A contains an oligomeric polyisocyanate 8. The composition according to any one of claims 1 to 7, wherein the molar ratio of isocyanate-reactive groups to isocyanate groups in the reaction mixture is between 1:1 and 1.2:

1.

9. The composition according to any one of claims 1 to 8, wherein components A, B and C have a weight proportion of at least 90 wt.% based on all components of the dispersion with the exception of water.

10. Aqueous coating composition comprising as component (i) at least one aqueous composition as defined in any one of claims 1 to 9 and as component (ii) at least one polyacrylate dispersion or at least one polyurethane dispersion or a mixture of at least one polyacrylate dispersion and at least one polyurethane dispersion.

11. Coating composition according to claim 10, wherein the weight fraction of the solids of component (i) relative to the total mass of the total solids of components (i) and (ii) is 5 to 60 wt.%.

12. A coating obtained or obtainable from the coating composition according to claim 10 or 11.

13. Surface coated with the coating composition according to claim 10 or 11.

14. Coating obtained or obtainable from the aqueous composition according to any one of claims 1 to 9.

15. Surface coated with the coating according to claim 14.

16. The surface of claim 13 or 15, selected from the group consisting of wood, plastic, metal and composite materials.

17. Use of the aqueous composition as defined in claims 1 to 9 for improving the blocking resistance and / or chemical resistance of a polyacrylate and / or polyurethane dispersion.

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