HK1175795B - Aqueous polyurethane dispersions - Google Patents

Description

Aqueous polyurethane dispersions

The invention relates to oxidatively and radiation-curable coating agents based on aqueous polyurethane dispersions, to a method for the production thereof, to the use of the coating agents as varnishes and/or adhesives, and to objects and substrates provided with these varnishes and/or adhesives.

Radiation-curable aqueous coating systems based on polyurethane dispersions find application in particular in the coating of wood, plastics and leather and are distinguished by a large number of positive properties, such as good chemical resistance and mechanical stability. A particular advantage is that the polyurethane cover layer is cured instantaneously by crosslinking through the olefinic double bonds contained in the polymer by means of high-energy radiation. Another advantage of aqueous coating systems is the low viscosity. This is particularly advantageous for spray applications.

The current trend, especially in the furniture industry, is to use aqueous radiation-curable polyurethane dispersions in pigmented formulations of white, black or colored shades. In this case, certain hues, for example yellow, red or black, prove particularly difficult, since they have a very strong absorption in the wavelength range in which commercially available photoinitiators absorb radiation. The result is that the radiation-induced polymerization does not proceed completely and the coating can be very easily damaged mechanically or chemically. In addition, good adhesion to the substrate cannot be achieved, since the lowermost varnish layer is still soft (Garrat, P. G., Strahlenh ä rtung, 1996, p. 115-.

EP-A753531 and EP-A942022 describe polyurethane acrylate dispersions based in particular on polyepoxy (meth) acrylates. Combinations with polyester polyols are described, but not with polyesters comprising unsaturated fatty acids. The adhesives cure only insufficiently in colored formulations, so that they have inadequate resistance to chemical or mechanical influences.

EP-A1914253 discloses urethane acrylate dispersions based on cyclopentadiene-modified polyesters. The cyclopentadiene-modified polyester may also contain, but is not necessarily required, soya oil fatty acid or oleic acid (a2), among others. The polyepoxy (meth) acrylates serve in particular as acrylate-containing structural motifs. There is no disclosure of aromatic poly (epoxy) (meth) acrylates in combination with polyesters comprising unsaturated fatty acids. The adhesives described in EP-A1914253 have inadequate performance properties in color-pigmented formulations (see example 6 in the present application).

EP-A613915 discloses polyurethane acrylate dispersions comprising 20 to 80% of esters comprising polyethylene glycol units, unsaturated fatty alcohols or unsaturated acids. Esters comprising unsaturated fatty alcohols or unsaturated acids are obtained by reaction of unsaturated fatty acids or acrylic acid with glycidyl esters. Aromatic poly (epoxy) (meth) acrylates are not described. Furthermore, it can be seen by those skilled in the art that a very high proportion of polyethylene glycol units results in coatings that are very hydrophilic and therefore susceptible to colorants and solvents.

WO-a2006047431 describes radiation-curable and non-radiation-curable polyurethane dispersions comprising polyesters based on hydroformylated unsaturated fatty acids. The double bonds of unsaturated fatty acids are hydroformylated or hydrogenated by hydroformylation. The double bonds for oxidative curing are therefore no longer present in the polyurethane dispersion.

In WO-a 2005021615, unsaturated fatty acids B) are added to aromatic epoxides a) in a first step, polyacrylates are grafted onto the double bonds of the fatty acids with (meth) acrylate monomers C) in a second step, and finally the product thus obtained is used as a starting material for radiation-curable urethane acrylate dispersions. In the synthesis of the urethane acrylate dispersion, (meth) acrylate monomers, such as hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate, are used as radiation-curable component D). Since the double bond of the unsaturated fatty acid has already been copolymerized with the (meth) acrylate monomer, the double bond for oxidative curing is no longer present in the polyurethane dispersion.

Oxidatively drying varnish resins based on unsaturated fatty acids and oils are known as alkyd resins (Brock, T.; Groteklas, M.; Mischke, P., Lehrbuch der Lacktechnology, first edition; Vincentz: Hannover, 2000, pages 62 to 65). These are non-aqueous systems which, due to the high viscosity, must be diluted with organic solvents or low molecular weight reactive diluents for spray application. Disadvantages are the emission of organic components and/or as a characteristic of irritation.

Alkyd-based oxidatively drying aqueous polyurethane dispersions are described in DE-A19917161 and DE-A102006054237. The varnishes prepared therefrom are dried with atmospheric oxygen at room temperature or at elevated temperature, optionally in the presence of a drying agent, for a few hours to a few days. Complete curing is very tedious compared to radiation curable polyurethane dispersions. Furthermore, the mechanical properties and chemical resistance are inferior to radiation curable polyurethane dispersions.

EP-A451590 and DE-A4405208 disclose aqueous polyurethane dispersions based on polyesters containing allyl ethers. Such dispersions are both radiation curable and oxidatively curable. Polyesters comprising allyl ethers are significantly more hydrophilic and result in poorer chemical resistance in the coating than polyesters comprising unsaturated fatty acids. No combination with a polyepoxyacrylate is described.

Combinations of two crosslinking mechanisms, for example radiation-induced free-radical polymerization and urethanization by addition of unblocked or blocked polyisocyanates, are likewise known and are referred to as dual curing. For example, WO-A03106577 discloses coating agents comprising aqueous radiation-curable polyurethane dispersions and unblocked, blocked, hydrophilized and/or non-hydrophilized polyisocyanates. If unblocked polyisocyanates are used, consideration must be given to the pot life of the varnish, i.e. the varnish forms a gel in a few minutes to a few hours. Pot life has a significant impact on the working regime and ultimately results in large amounts of waste, since the unwanted varnish can neither be recycled nor stored. If blocked polyisocyanates are used, the coating must be baked at temperatures above 100 ℃ after radiation curing in order to unblock the isocyanates. Such temperatures are disadvantageous for heat-sensitive substrates, such as wood or plastics.

The object was therefore to develop radiation-curable aqueous adhesives which have better chemical and mechanical resistance in colored formulations than known hitherto. They must in particular give a tack-free film after physical drying, and the coatings must have a high resistance to colorants and solvents.

It has surprisingly been found that aqueous radiation-curable polyurethane acrylate dispersions achieve good chemical and mechanical resistance in color formulations if they are based on aromatic polyepoxy (meth) acrylates and on oligoesters and/or polyesters comprising unsaturated fatty acids. By radiation curing and oxidative curing, the color clearcoat coatings based on such binders achieve significantly higher mechanical strength and better chemical resistance than has hitherto been the case for clearcoats based on known urethane acrylate dispersions. In this case, the resistance to the colorant is unexpectedly good. After the instantaneous radiation curing, the painted substrate can already be subjected to sufficient mechanical and chemical pressure for further processing or assembly. Full resistance of the coating will be obtained within hours to days depending on the implementation of the oxidative cure. This is an important advantage over systems which can only be cured oxidatively, since in principle these systems which can only be cured oxidatively can only be further processed after hours or days of oxidative curing. The adhesives according to the invention have no pot life and do not need to be crosslinked at elevated temperatures, since oxidative crosslinking also occurs at room temperature.

The invention relates to aqueous radiation-curable dispersions based on urethane acrylates (i), characterized in that the urethane acrylates (i) comprise as building components:

A) one or more aromatic poly (epoxy) (meth) acrylates having an OH number of 20 to 300mg KOH/g of substance,

B) optionally a compound having at least one isocyanate-reactive group and at least one radiation-curable double bond different from A),

C) one or more oligo-or polyesters comprising an OH number of 15-300 mg KOH/g substance and more than 50 g I₂Unsaturated fatty acids with iodine value per 100 g of substance,

D) optionally one or more compounds having at least one isocyanate-reactive group but no radiation-curable and oxidatively curable double bonds,

E) one or more compounds having at least one isocyanate-reactive group and additionally at least one group having a hydrophilicizing action,

F) one or more organic polyisocyanates, and

G) optionally a compound having at least one amine function different from A) to F).

The dispersion optionally comprises component (ii), wherein the component is a reactive diluent having at least one free radically polymerizable group.

In the context of the present invention, "(meth) acrylate" means the corresponding acrylate-or methacrylate function or a mixture of both.

The OH number is determined in accordance with DIN 53240 and the iodine number is determined in accordance with DIN 53241-1.

Here, the building components A) and optionally B) and (ii) are used in such amounts that the radiation-curable double bond content is between 0.5 and 6.0, preferably between 1.0 and 5.5, particularly preferably between 1.5 and 5.0 mol/kg of the nonaqueous components of the dispersion.

Component (A) is used in amounts of 5 to 45% by weight, preferably 10 to 40% by weight, particularly preferably 15 to 35% by weight, where components (i) and (ii) add up to 100% by weight.

Component C) is used in amounts of 15 to 65% by weight, preferably 20 to 55% by weight, particularly preferably 25 to 50% by weight, the components (i) and (ii) adding up to 100% by weight.

Preferably, the content of polyethylene glycol units is less than 20% by weight, based on the sum of the non-aqueous components of the dispersion.

Polyepoxide (meth) acrylates known per se containing hydroxyl groups having OH numbers in the range from 20 to 300mg KOH/g, preferably 100-280 mg KOH/g, particularly preferably 150-250 mg KOH/g, are suitable as component A). Such compounds are described on pages 37-56 of P.K.T. Oldring (eds.), Chemistry & Technology of UV & EB Formulations For Coatings, Inks & paintings, Vol.2, 1991, SITA Technology, London. Aromatic polyepoxide (meth) acrylates containing hydroxyl groups are based on the reaction product of acrylic and/or methacrylic acid with aromatic glycidyl ethers (epoxides), preferably of monomeric, oligomeric or polymeric bisphenol a and/or bisphenol F or their alkoxylated derivatives.

The compounds listed under component A) can be used as such individually or also in mixtures.

Component B) comprises one or more compounds selected from the group consisting of: polyester (meth) acrylates, polyether (meth) acrylates, polyetherester (meth) acrylates, and unsaturated polyesters having an OH number in the range from 15 to 300mg KOH/g of substance, having allyl ether structural units, and monohydroxy-functional alcohols containing (meth) acrylate groups.

In the polyester (meth) acrylates, polyester (meth) acrylates containing hydroxyl groups having an OH number of from 15 to 300mg KOH/g of substance, preferably from 60 to 200 mg KOH/g of substance, are used as component B). In the preparation of the hydroxy-functional polyester (meth) acrylates as component B), a total of 7 monomer components can be used.

The first group (a) contains alkanediols or diols or mixtures of these. The alkanediol has a molecular weight of from 62 to 286 g/mol. The alkanediol is preferably selected from the group consisting of: ethylene glycol, 1, 2-and 1, 3-propanediol, 1,2-, 1, 3-and 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, neopentyl glycol, cyclohexane-1, 4-dimethanol, 1, 2-and 1, 4-cyclohexanediol, 2-ethyl-2-butylpropanediol. Preferred diols are diols containing ether oxygen, such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycols, polypropylene glycols or polybutylene glycols having a number-average molar mass Mn of 200-. The reaction products of the above diols with caprolactone or other lactones may likewise be used as diols.

The second group (b) contains trihydric and higher-hydric alcohols having a molecular weight in the range from 92 to 254 g/mol and/or polyethers starting from these alcohols. Particularly preferred trihydric and higher hydric alcohols are glycerol, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol. A particularly preferred polyether is the reaction product of 1mol trimethylolpropane and 4mol ethylene oxide.

The third group (c) contains monohydric alcohols. Particularly preferred monoalcohols are selected from the group consisting of ethanol, 1-and 2-propanol, 1-and 2-butanol, 1-hexanol, 2-ethylhexanol, cyclohexanol and benzyl alcohol.

The fourth group (d) contains dicarboxylic acids having a molecular weight of 104-600 g/mol and/or their anhydrides. Preferred dicarboxylic acids and their anhydrides are selected from phthalic acid, phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, cyclohexanedicarboxylic acid, maleic anhydride, fumaric acid, malonic acid, succinic anhydride, glutaric acid, adipic acid, pimelic acid, suberic acid, sebacic acid, dodecanedioic acid, hydrogenated dimers of the fatty acids listed, for example, under the sixth group (f).

The fifth group (e) contains trimellitic acid or trimellitic anhydride.

The sixth group (f) contains monocarboxylic acids such as benzoic acid, cyclohexanecarboxylic acid, 2-ethylhexanoic acid, caproic acid, caprylic acid, capric acid, lauric acid, and natural and synthetic fatty acids such as lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, behenic acid, cerotic acid, palmitoleic acid, oleic acid, eicosenoic acid, linoleic acid, linolenic acid, and arachidonic acid.

The seventh group (g) contains acrylic acid, methacrylic acid and/or dimeric acrylic acid.

Suitable hydroxyl-containing polyester (meth) acrylates B) comprise the reaction products of at least one component of group (a) or (B) with at least one component of group (d) or (e) and at least one component of group (g).

Particularly preferred components of group (a) are selected from ethylene glycol, 1, 2-and 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol, cyclohexane-1, 4-dimethanol, 1, 2-and 1, 4-cyclohexanediol, 2-ethyl-2-butylpropanediol, glycols containing ether oxygen, which are selected from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol and tripropylene glycol. Preferred components of group (b) are selected from glycerol, trimethylolpropane, pentaerythritol or the reaction product of 1mol trimethylolpropane and 4mol ethylene oxide. Particularly preferred components of groups (d) and (e) are selected from phthalic anhydride, isophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid, hexahydrophthalic anhydride, maleic anhydride, fumaric acid, succinic anhydride, glutaric acid, adipic acid, dodecanedioic acid, hydrogenated dimers of fatty acids such as those listed under group six (f), and trimellitic anhydride. The preferred component of group (g) is acrylic acid.

Groups with dispersing action, which are generally known from the prior art, can also optionally be incorporated in these polyester (meth) acrylates. For example, polyethylene glycol and/or methoxypolyethylene glycol may be used as part of the alcohol component. Polyethylene glycols, polypropylene glycols and their block copolymers starting from alcohols, and also the monomethyl ethers of these polyglycols, can be used as compounds. Polyethylene glycol monomethyl ethers having a number average molecular weight Mn in the range from 500 and 1500 g/mol are particularly suitable.

It is furthermore possible to react some of the still free, unesterified carboxyl groups, in particular carboxyl groups of (meth) acrylic acid, with mono-, di-or polyepoxides after esterification. Preferred epoxides are glycidyl ethers of monomeric, oligomeric or polymeric bisphenol a, bisphenol F, hexanediol and/or butanediol or their ethoxylated and/or propoxylated derivatives. This reaction can be used in particular to increase the OH number of polyester (meth) acrylates, since in each case OH groups are formed in the epoxide-acid reaction. The acid number of the product obtained is between 0 and 20 mg KOH/g, preferably between 0 and 10 mg KOH/g and particularly preferably between 0 and 5 mg KOH/g of substance. The reaction is preferably catalyzed by catalysts such as triphenylphosphine, thiodiglycol, ammonium halides and/or phosphonium halides, and/or zirconium compounds or tin compounds, for example tin (II) ethylhexanoate.

The preparation of polyester (meth) acrylates is described on page 3, line 25 to page 6, line 24 of DE-A4040290, page 5, line 14 to page 11, line 30 of DE-A3316592 and on pages 123-135 of Chemistry & Technology of UV & EB formulations for Coatings, Inks & paintings, Vol.2, 1991, SITA Technology, London, eds.

Polyether (meth) acrylates which contain hydroxyl groups and are obtained by reaction of acrylic acid and/or methacrylic acid with polyethers are likewise suitable as component B), so that, for example, ethylene oxide, propylene oxide and/or tetrahydrofuran are employed as homopolymers, copolymers or block copolymers on any hydroxy-and/or amine-functional starter molecules, such as trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, glycerol, pentaerythritol, neopentyl glycol, butanediol and hexanediol.

Also suitable as component B) are monohydroxy-functional alcohols containing (meth) acrylate groups, for example 2-hydroxyethyl (meth) acrylate, caprolactone-extended modifications of 2-hydroxyethyl (meth) acrylate, such as Pemcure^®12A (Cognis, Germany), 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxy-2, 2-dimethylpropyl (meth) acrylate, the average monohydroxy-functional di-, tri-or penta- (meth) acrylates of polyols, such as trimethylolpropane, glycerol, pentaerythritol, di-trimethylolpropane, dipentaerythritol, ethoxylated, propoxylated or alkoxylated trimethylolpropane, glycerol, pentaerythritol, di-trimethylolpropane, dipentaerythritol or industrial mixtures thereof.

Furthermore, the reaction product of (meth) acrylic acid with a monomeric epoxide compound optionally containing double bonds may also be used as a monohydroxy-functional alcohol containing (meth) acrylate groups. Preferred reaction products are selected from the group consisting of glycidyl (meth) acrylate and glycidyl (meth) acrylate or glycidyl esters of tertiary saturated monocarboxylic acids. Examples of tertiary saturated monocarboxylic acids are 2, 2-dimethylbutyric acid, ethylmethylbutanoic acid, ethylmethylpentanoic acid, ethylmethylhexanoic acid, ethylmethylheptanoic acid and/or ethylmethyloctanoic acid.

Preferred unsaturated group-containing compounds are selected from: polyester (meth) acrylates, polyether (meth) acrylates, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and addition products of glycidyl ethylmethylheptanoate with (meth) acrylic acid, and industrial mixtures thereof.

The compounds listed under component B) can be used as such individually or also in mixtures.

Component C) comprises a catalyst having from 15 to 300mg KOH/g of substance, preferably from 50 to 180 mg KOH/g of substanceParticularly preferably 70 to 140 mg KOH/g of substance, and an OH number of more than 50 g I₂A hydroxy-functional oligoester or polyester comprising an unsaturated fatty acid per 100 g of material.

Oligoesters or polyesters comprising di-, tri-, tetra-and/or hexa-alcohols and unsaturated fatty acids, optionally additionally saturated aliphatic and/or aromatic di-and tribasic acids as building components are suitable as component C).

Examples of di-, tri-, tetra-and/or hexa-alcohols as building components of component C) are ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, neopentyl glycol, 2-ethyl-2-butylpropanediol, trimethylpentanediol, 1, 3-butanediol, 1, 4-cyclohexanedimethanol, 1, 6-hexanediol, 1, 2-and 1, 4-cyclohexanediol, hydrogenated bisphenol A (2, 2-bis (4-hydroxycyclohexyl) propane), diols derived from dimer fatty acids, 2-dimethyl-3-hydroxypropionic acid- (2, 2-dimethyl-3-hydroxypropyl ester), glycerol, trimethylolethane, Trimethylolpropane, trimethylolbutane, ditrimethylolpropane, castor oil, partially dehydrated castor oil, pentaerythritol and/or dipentaerythritol. Unsaturated fatty acids as building components of component C) are for example linseed oil fatty acid, soya oil fatty acid, sunflower oil fatty acid, rapeseed oil fatty acid and menhaden oil fatty acid, mainly (> 60% by weight) comprising the distillation products of oleic acid, linoleic acid, octadecatriene-4-keto acid, arachidonic acid, palmitoleic acid, ricinoleic acid and linolenic acid, preferably unsaturated fatty acids whose composition in the fatty acid residues correspond to naturally occurring fatty acid mixtures, as can be obtained from vegetable or animal oils, such as soybean oil, tall oil, linseed oil or sunflower oil. Saturated aliphatic and/or aromatic dibasic and tribasic acids may also optionally be included as building components, for example phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, adipic acid, hexahydrophthalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, sebacic acid, dodecanedioic acid, hydrogenated dimeric fatty acids, trimellitic acid and their analogous anhydrides.

Partially dehydrated castor oil obtained by thermal loading of castor oil under acid catalysis and described in EP-A709414 (page 2, lines 37 to 40) is also suitable as component C).

Esterification-and transesterification products of unsaturated fatty acids and/or unsaturated oils with at least difunctional polyol compounds, preferably tri-and tetrafunctional hydroxyl components, such as trimethylolethane, trimethylolpropane, glycerol, castor oil and pentaerythritol, are also suitable as component C). Such transesterification products are described in EP-A017199 (page 10, line 27 to page 11, line 31).

Further suitable products comprising unsaturated fatty acids are described in EP-A640632 (page 2, lines 50-58 and page 3, lines 10-14). They are obtained by esterification of unsaturated fatty acids and/or unsaturated oils with polyhydric alcohols. Examples of such fatty acids which may be mentioned are linoleic acid, octadecatrien-4-oic acid, arachidonic acid, palmitoleic acid, and/or linolenic acid, preferably those of fatty acid mixtures derived from vegetable or animal oils, such as soybean oil, tall oil, linseed oil or sunflower oil, esterified with polyhydric alcohols, such as trimethylolethane, trimethylolpropane, glycerol or pentaerythritol. Particular preference is given to transesterification products of unsaturated oils, such as dehydrogenated castor oil, sunflower oil, soybean oil, linseed oil, tall oil, olive oil or mixtures of these, with trimethylolethane, trimethylolpropane, glycerol or pentaerythritol.

Preferred components C) are reaction products of unsaturated fatty acids, such as oleic acid, lauric acid, linoleic acid or linolenic acid, with castor oil in the presence of glycerol and/or reaction products of unsaturated oils with castor oil. Preferred unsaturated fatty acids are mixtures of unsaturated fatty acids which can be obtained from vegetable or animal oils, for example soybean oil, tall oil, linseed oil, sunflower oil or olive oil.

Component C) is particularly preferably a transesterification product of castor oil with one or more oils having an iodine value of more than 100.

Transesterification products of castor oil and soybean oil are most particularly preferred as component C).

Mixtures of the components C) are likewise suitable.

Component D) comprises monomeric monoalcohols, dialcohols and/or trialcohols, in each case having a molecular weight of from 32 to 240 g/mol, such as methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, 2-butanol, 2-ethylhexanol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, neopentyl glycol, 2-ethyl-2-butylpropanediol, trimethylpentanediol, 1, 3-butanediol, 1, 4-cyclohexanedimethanol, 1, 6-hexanediol, 1, 2-and 1, 4-cyclohexanediol, hydrogenated bisphenol A (2, 2-bis (4-hydroxycyclohexyl) propane), Glycols derived from dimerized fatty acids, 2-dimethyl-3-hydroxypropionic acid- (2, 2-dimethyl-3-hydroxypropyl ester), glycerol, trimethylolethane, trimethylolpropane, trimethylolbutane and/or castor oil. Preference is given to neopentyl glycol, 1, 4-butanediol, 1, 4-cyclohexanedimethanol, 1, 6-hexanediol and/or trimethylolpropane.

Furthermore, component D) comprises oligomeric and/or polymeric hydroxy-functional compounds. These oligomeric and/or polymeric hydroxy-functional compounds are, for example, those having a functionality of from 1.0 to 3.0, in each case having a weight-average molecular weight M of from 300 to 4000, preferably from 500 to 2500 g/mol_wPolyester, polycarbonate, polyether carbonate polyol, C2-, C3-and/or C4-polyether, polyether ester and/or polycarbonate polyester.

Hydroxy-functional polyesterols are those based on dihydric and trihydric alcohols of mono-, di-and/or trihydric carboxylic acids and monomers as already listed as component D), and also polyesterols based on lactones. Such as phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, adipic acid, hexahydrophthalic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, suberic acid, sebacic acid, dodecanedioic acid, hydrogenated dimers of fatty acids, and saturated fatty acids such as palmitic acid and stearic acid. In the di-and tricarboxylic acids, similar anhydrides may also be used.

Hydroxy-functional polyether alcohols are obtainable, for example, by polymerization of cyclic ethers or by reaction of alkylene oxides with starter molecules.

Hydroxy-functional polycarbonates are hydroxy-terminated polycarbonates obtainable by reacting diols, lactone-modified diols or bisphenols, for example bisphenol A, with phosgene or carbonic diesters, for example diphenyl carbonate or dimethyl carbonate. Hydroxyl-functional polyether carbonate polyols are those which are used to build up polyurethane dispersions, as described in DE 102008000478A.

The compounds listed under component D) can be used as such, alone or in mixtures.

Component E) comprises compounds having at least one isocyanate-reactive group and additionally at least one hydrophilicizing group.

The groups which effect hydrophilization comprise ionic groups E1) and/or ionic groups E1) derived from potentially ionic groups E2) (for example by salt formation), which may be of anionic nature E1.1), for example sulfonium groups, phosphonium groups, carboxylate groups, sulfonate groups, phosphonate groups, or of cationic nature E1.2) for example ammonium groups, potentially ionic groups E2), i.e.groups which can be converted into ionic groups E1) for example by salt formation, and/or nonionic groups E3) such as polyether groups, which can be introduced into the macromolecule via isocyanate-reactive groups. Preferred suitable isocyanate-reactive groups are hydroxyl and amino groups.

Compounds containing a potentially ionic group E2) include compounds having a potentially anionic group E2.1) such as mono-and dihydroxycarboxylic acids, mono-and diaminocarboxylic acids, mono-and dihydroxysulfonic acids, mono-and diaminosulfonic acids, mono-and dihydroxyphosphonic acids, mono-and diaminophosphonic acids, and/or compounds having a potentially cationic group E2.2) such as ethanolamine, diethanolamine, triethanolamine, 2-propanolamine, dipropanolamine, tripropanolamine, N-methylethanolamine, N-methyldiethanolamine and N, N-dimethylethanolamine.

Preferred compounds comprising a latent anionic group E2.1) are selected from dimethylolpropionic acid, dimethylolbutyric acid, hydroxypivalic acid, N- (2-aminoethyl) -alanine, 2- (2-aminoethylamino) ethanesulfonic acid, ethylenediamine propyl-or butylsulfonic acid, 1, 2-or 1, 3-propylenediamine-ethanesulfonic acid, 3- (cyclohexylamino) propane-1-sulfonic acid, malic acid, citric acid, glycolic acid, lactic acid, glycine, alanine, taurine, lysine, 3, 5-diaminobenzoic acid, isophoronediamine (1-amino-3, 3, 5-trimethyl-5-aminomethylcyclohexane, IPDA) and the addition product of acrylic acid (EP-A0916647, example 1), sodium hydrogen sulfite in but-2-ene-1, adducts on 4-diol polyether sulfonates and 2-butenediols and NaHSO as described, for example, in DE-A24464405-9, formulae I to III₃Propoxylated adducts of (a).

Particularly preferred compounds containing latent anionic groups E2) are compounds containing carboxyl, sulfonic and/or tertiary amino groups, such as 2- (2-aminoethylamino) ethanesulfonic acid, 3- (cyclohexylamino) propane-1-sulfonic acid, addition products of isophoronediamine and acrylic acid (EP 916647A 1, example 1), hydroxypivalic acid, dimethylolpropionic acid, triethanolamine, tripropanolamine, N-methyldiethanolamine and/or N, N-dimethylethanolamine.

Very particular preference is given to hydroxypivalic acid and/or dimethylolpropionic acid as component E) of the compounds having potentially ionic groups.

Suitable groups E3) which act as nonionic hydrophilicizing groups are, for example, polyalkylene oxide ethers which comprise at least one hydroxyl or amino group and one or more alkylene oxide units, at least one of which is an ethylene oxide unit. These polyalkylene oxide ethers can be obtained in a manner known per se by alkoxylation of suitable starter molecules.

Suitable starter molecules are, for example, saturated monoalcohols, such as methanol, ethanol, N-propanol, isopropanol, N-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols, octanols and nonanols, N-decanol, N-dodecanol, N-tetradecanol, N-hexadecanol, N-octadecanol, cyclohexanol, the isomeric methylcyclohexanols or hydroxymethylcyclohexane, 3-ethyl-3-hydroxymethyloxetane or tetrahydrofurfuryl alcohol, diethylene glycol monoalkyl ethers, such as diethylene glycol monobutyl ether, unsaturated alcohols, such as allyl alcohol, 1-dimethylallyl alcohol or oleyl alcohol, aromatic alcohols, such as phenol, the isomeric cresols or methoxyphenols, araliphatic alcohols, such as benzyl alcohol, anisyl alcohol or cinnamyl alcohol, secondary monoamines, such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, bis- (2-ethylhexyl) amine, N-methyl-and N-ethylcyclohexylamine or dicyclohexylamine, and heterocyclic secondary amines such as morpholine, pyrrolidine, piperidine or 1H-pyrazole. Trimethylolpropane alkoxylated on only one OH group is likewise suitable. Preferred starter molecules are saturated monoalcohols and trimethylolpropane alkoxylated on only one OH group. Particular preference is given to using diethylene glycol monobutyl ether as starter molecule.

Alkylene oxides suitable for the alkoxylation reaction are, for example, ethylene oxide, 1-butylene oxide and propylene oxide, which can be used in any order or in mixtures for the alkoxylation reaction.

The polyalkylene oxide polyether alcohols are pure polyethylene oxide polyethers or mixed polyalkylene oxide polyethers whose alkylene oxide units comprise at least 30 mol%, preferably at least 40mol%, of ethylene oxide units. Preferred nonionic compounds are monofunctional mixed polyalkylene oxide polyethers having at least 40mol% ethylene oxide units and up to 60 mol% propylene oxide units. Trimethylolpropane-initiated polyalkylene oxides having an OH functionality of 2, e.g. Tegomer^®D3403 (Evonik Industries AG, Essen, Germany) and Ymer^®N120 (Perstorp AB, Sweden) is likewise preferred.

The acids mentioned under component E2.1) are converted into the corresponding salts by reaction with neutralizing agents such as triethylamine, ethyldiisopropylamine, dimethylcyclohexylamine, dimethylethanolamine, ammonia, N-ethylmorpholine, LiOH, NaOH and/or KOH. Here, the degree of neutralization is preferably between 50 and 125%. The degree of neutralization is defined as follows: as a quotient of base and acid in the case of acid-functionalized polymers; in the case of base-functionalized polymers, as a quotient of acid and base. If the degree of neutralization is above 100%, more base is added than the acid groups present in the polymer in the case of acid-functionalized polymers; in the case of base-functionalized polymers, more acid is added than is present in the polymer.

The bases mentioned under component E2.2) are converted into the corresponding salts by reaction with neutralizing agents, for example mineral acids, such as hydrochloric acid, phosphoric acid and/or sulfuric acid, and/or organic acids, such as formic acid, acetic acid, lactic acid, methane-, ethane-and/or p-toluenesulfonic acid. Here, the degree of neutralization is preferably 50 to 125%.

The compounds listed under component E) can also be used in mixtures.

Ionic hydrophilization and combinations of ionic and nonionic hydrophilization are preferred over pure nonionic hydrophilization.

Component F) is a polyisocyanate selected from aromatic, araliphatic, aliphatic or cycloaliphatic polyisocyanates or mixtures of these polyisocyanates. Suitable polyisocyanates are, for example, 1, 3-cyclohexane diisocyanate, 1-methyl-2, 4-diisocyanatocyclohexane, 1-methyl-2, 6-diisocyanatocyclohexane, tetramethylene diisocyanate, 4 '-diisocyanatodiphenylmethane, 2, 4-diisocyanatotoluene, 2, 6-diisocyanatotoluene, alpha' -tetramethyl-m-or-p-xylylene diisocyanate, 1, 6-hexamethylene diisocyanate, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate or IPDI), 4,4' -diisocyanatodicyclohexylmethane, 1, 3-bis (isocyanatomethyl) benzene (XDI), 1, 3-bis (1-isocyanato-1-methylethyl) benzene (TMXDI), 4-isocyanatomethyl-1, 8-octane diisocyanate (triisocyanatononane, TIN) (EP-A928799), the homologs or oligomers of these polyisocyanates listed having biuret-, carbodiimide-, isocyanurate-, allophanate-, iminooxadiazinedione-and/or uretdione groups, and mixtures thereof.

As component F), likewise suitable are compounds having at least two free isocyanate groups, at least one allophanate group and at least one C = C double bond which can be radically polymerized and is bonded via an allophanate group, as described in WO 2006089935 a1 as component a).

Preference is given to 1, 6-hexamethylene diisocyanate, 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate or IPDI) and 4,4 '-diisocyanatodicyclohexylmethane, homologues or oligomers of 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate or IPDI) and 4,4' -diisocyanatodicyclohexylmethane having biuret-, carbodiimide-, isocyanurate-, allophanate-, iminooxadiazinedione-and/or uretdione groups, and also mixtures thereof.

The compounds listed under component F) can be used as such individually or in mixtures.

In order to increase the weight-average molecular weight M of the urethane acrylate_wAs component G) monoamines and diamines and/or monofunctional or difunctional amino alcohols are used. Preferred diamines are those which are more reactive with isocyanate groups than with water, since the extension of the polyester-urethane (meth) acrylate is optionally carried out in an aqueous medium. Particularly preferably, the diamine is selected from the group consisting of ethylenediamine, 1, 6-hexamethylenediamine, isophoronediamine, 1, 3-phenylenediamine, 1, 4-phenylenediamine, piperazine, 4' -diphenylmethanediamine, amino-functional polyethylene oxide, amino-functional polypropylene oxide (known under the name Jeffamin D series (huntsman Corp. Europe, Zavantem, Belgium) and hydrazine, very particularly preferably ethylenediamine.

Preferred monoamines are selected from butylamine, ethylamine and Jeffamin^®Amines of the M series (huntsman corp. Europe, Zavantem, belgium), amino-functional polyethylene oxides, amino-functional polypropylene oxides and/or amino alcohols.

The aqueous dispersions based on urethane acrylates (i) according to the invention are preferably free of unsaturated polyester resins modified with dicyclopentadiene.

Component (ii) is a reactive diluent, which is understood to be a compound which contains at least one radical-polymerizable group, preferably acrylate and methacrylate groups, and preferably no groups which react with isocyanate groups or hydroxyl groups.

Preferred compounds (ii) have from 2 to 6, particularly preferably from 4 to 6, (meth) acrylate groups.

Particularly preferred compounds (ii) have a boiling point of over 200 ℃ at normal pressure.

Reactive diluents are generally described in P.K.T. Oldring (eds.), Chemistry & Technology of UV & EB Formulations for Coatings, Inks & Paints, Vol.II, Chapter III, reactive diluents for UV & EB Current Formulations, Wiley and SITA Technology, London 1997.

Reactive diluents are, for example, the following alcohols which are completely esterified with (meth) acrylic acid: methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, 2-butanol, 2-ethylhexanol, dihydrodicyclopentadienol, tetrahydrofurfuryl alcohol, 3, 5-trimethylhexanol, octanol, decanol, dodecanol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, neopentyl glycol, 2-ethyl-2-butylpropanediol, trimethylpentanediol, 1, 3-butanediol, 1, 4-cyclohexanedimethanol, 1, 6-hexanediol, 1, 2-and 1, 4-cyclohexanediol, hydrogenated bisphenol A (2, 2-bis (4-hydroxycyclohexyl) propane), Tricyclodecane dimethanol, glycerol, trimethylolethane, trimethylolpropane, trimethylolbutane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, as well as ethoxylated and/or propoxylated derivatives of the alcohols listed, and the technical mixtures obtained during the (meth) acrylation of the above-mentioned compounds.

Component (ii) is preferably selected from (meth) acrylates of tetraols and hexaols, such as pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, (meth) acrylates of ethoxylated, propoxylated or alkoxylated pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol and also ethoxylated and/or propoxylated derivatives of the cited alcohols, and the technical mixtures obtained during the (meth) acrylation of the abovementioned compounds.

For the preparation of the dispersions according to the invention, all processes known from the prior art can be used, for example emulsifier-shear force-, acetone-, prepolymer-mixing-, melt-emulsification-, ketimine-and solid spontaneous dispersion processes or their derivatives. A summary of these processes can be found in Methodender Organischen Chemie, Houben-Weyl, 4 th edition, volume E20/part 2, page 1682, Georg Thieme Verlag, Stuttgart, 1987. The melt emulsification-and acetone processes are preferred. The acetone process is particularly preferred.

The invention also provides a process for preparing radiation-curable aqueous dispersions based on urethane acrylates (i), characterized in that urethane acrylates (i) are obtained by reacting components A) to E) with component F) in one or more reaction steps, wherein neutralizing agents can be added before, during or after the preparation of the addition products of A) to F) to generate the ionic groups required for the dispersion, followed by a dispersion step by adding water to the addition products of A) to F), or the addition products of A) to F) are transferred into a water-containing vessel, wherein chain extension can be carried out before, during or after the dispersion by means of component G).

The present invention also provides a process according to the above description, wherein one or more reactive diluents (component (ii)) comprising at least one group which can undergo free radical polymerization are mixed.

For the preparation of radiation-curable aqueous dispersions based on urethane acrylates (i), components a) to E) are introduced into the reactor in advance and optionally diluted with acetone. Component (ii) may also optionally be added to components A) to E). In addition, catalysts known in the industry for urethanization, such as dibutyltin dilaurate, tin (II) octoate and bismuth (III) octoate, can be added. Typically, the mixture is heated to 30-60 ℃ to start the reaction. One or more polyisocyanates F) are then metered in. The opposite variant is also possible, the polyisocyanate F) being introduced beforehand and the isocyanate-reactive components A) to E) being added. Components A) to E) can also be added in succession and in any desired order. Stepwise reaction of the components is also possible, that is to say reaction of component F) with one or more isocyanate-reactive components A) to E) separately before further reaction of the resulting adduct with components which have not yet been used.

For monitoring the reaction, the isocyanate content is determined at regular intervals by titration or by infrared-or near-infrared spectroscopy.

F) The molar ratio of isocyanate groups in A) to isocyanate-reactive groups in E) is from 0.8: 1 to 2.5: 1, preferably from 1.2: 1 to 1.5: 1.

After the preparation of the urethane acrylates (i) from components A) to F) according to the process of the invention, the salt formation of the dispersing groups of compound E) is carried out if it has not already been carried out in the starting molecule. In case component E) comprises acidic groups, it is preferred to use a base selected from triethylamine, ethyldiisopropylamine, dimethylcyclohexylamine, dimethylethanolamine, ammonia, N-ethylmorpholine, LiOH, NaOH and/or KOH. In case component E) comprises basic groups, it is preferred to use an acid selected from lactic acid, acetic acid, phosphoric acid, hydrochloric acid and/or sulfuric acid. If compounds containing only ether groups are used as component E), this neutralization step is omitted.

Then, a reactive diluent (ii) or a mixture of reactive diluents (ii) may optionally be added. The mixing of component (ii) is preferably carried out at 30 to 45 ℃. Once it has dissolved, a final reaction step is optionally carried out in which the molecular weight increase is carried out in an aqueous medium and the desired dispersion of the coating system according to the invention is formed: the urethane acrylates (i) synthesized from components a) to F), optionally dissolved in acetone, and optionally one or more reactive diluents (ii) are added with vigorous stirring to the dispersion water containing the amine or amines G) or, conversely, the dispersion water-amine mixture is added to the urethane acrylate solution. Furthermore, a dispersion is formed which is contained in the coating system according to the invention. The amount of amine G) used depends on the unreacted isocyanate groups still present. The reaction of the isocyanate groups still free with the amines G) can be carried out to an extent of 35% to 150%. In the case of using an insufficient amount of amine G), the isocyanate groups still free react slowly with water. If an excess of amine G) is used, unreacted isocyanate groups are no longer present and an amine-functional polyurethane will result. Preferably from 80% to 110%, particularly preferably from 90% to 100%, of the remaining free isocyanate groups are reacted with the amine G).

In another variant, the molecular weight increase may have been carried out by the amine G) in acetone solution, i.e. before the dispersion, and optionally before or after the addition of the reactive diluent(s) (ii).

In a further variant, the molecular weight increase can be carried out after the dispersing step by means of the amine G).

If desired, the organic solvent, if present, may be distilled off. The dispersion then has a solids content of from 20 to 60% by weight, in particular from 30 to 58% by weight.

It is likewise possible to carry out the dispersing steps in parallel, i.e. simultaneously or at least partially simultaneously.

The present invention also provides the use of the radiation-curable aqueous dispersions according to the invention for the preparation of coatings, in particular varnishes and adhesives.

The dispersions according to the invention yield clear films after removal of water by customary methods, such as heat, thermal radiation, moving optionally dry air and/or microwaves. Followed by radiation curing and oxidative curing. Here, the two curing types are carried out in any order. Preferably, the radiation curing is performed first and the oxidative curing is performed subsequently.

Optionally with the addition of a suitable photoinitiator, electromagnetic radiation is suitable for the radiation-chemically induced polymerization, the energy of the electromagnetic radiation being sufficient to cause free-radical polymerization of the (meth) acrylate double bonds.

The radiation-chemically induced polymerization is preferably carried out by means of radiation having a wavelength of less than 400nm, such as UV-, electron-, x-ray-or gamma-radiation. UV radiation is particularly preferred, wherein the curing with UV radiation is initiated in the presence of a photoinitiator. Photoinitiators are in principle distinguished between two classes, monomolecular (type I) and bimolecular (type II). Suitable (type I) systems are aromatic ketone compounds, for example benzophenones in combination with tertiary amines, alkylbenzophenones, 4 '-bis (dimethylamino) benzophenone (Michler's ketone), anthrone and halogenated benzophenones or mixtures of the stated types. Also suitable are (type II) initiators, such as benzoin and its derivatives, benzil ketals, acylphosphine oxides, 2,4, 6-trimethylbenzoyl-diphenylphosphine oxides, bisacylphosphine oxides, mandelates, camphorquinones, alpha-aminoalkylphenones, alpha-dialkoxyacetophenones and alpha-hydroxyalkylphenylketones. Photoinitiators which can be easily incorporated into aqueous coating agents are preferred. Such products are for example Irgacure^®500 (mixture of benzophenone and (1-hydroxycyclohexyl) phenyl ketone, Ciba, Lampertheim, Germany), Irgacure^®819 DW (phenyl bis- (2,4, 6-trimethylbenzoyl) -phosphine oxide, Ciba, Lampertheim, Germany), Esacure^®KIP EM (oligo- [ 2-hydroxy-2-methyl-1- [4- (1-methylethenyl) -phenyl)]-acetone]Lamberti, Aldizzate, italy). Mixtures of these compounds may also be used.

Polar solvents such as acetone and isopropanol can also be used for the introduction of the photoinitiator.

Radiation curing is advantageously carried out at from 30 to 70 ℃ since the degree of conversion of the (meth) acrylate groups tends to increase at higher temperatures. This may result in better withstand performance. However, the possible thermal sensitivity of the substrate must be taken into account during UV curing, so that optimum curing conditions for a certain coating agent-substrate combination will be determined by the person skilled in the art in simple preliminary experiments.

Here, the radiation emitter or emitters initiating the free-radical polymerization can be stationary and the coated substrate moved past the emitter by suitable conventional means, or the radiation emitters can be moved by conventional means such that the coated substrate is stationary during curing. It is also possible, for example, to carry out the irradiation in a chamber, wherein the coated substrate is introduced into the chamber, then the irradiation is started for a certain time and the substrate is removed from the chamber again after the irradiation.

Curing is optionally carried out under an inert gas atmosphere, i.e. excluding oxygen, to prevent free radical crosslinking from being inhibited by oxygen.

Instead of radiation curing, thermal radical curing may also be carried out. Aqueous emulsions of water-soluble peroxides or water-insoluble initiators are suitable for this. These free-radical initiators may be combined with accelerators in a known manner.

Oxidative curing is carried out under oxygen conditions. In this case, atmospheric oxygen is usually sufficient.

For oxidative curing, the substrate may be heated at 30 ℃ to 200 ℃ for several hours to promote oxidative crosslinking. However, oxidative crosslinking is also carried out at room temperature.

To promote oxidative crosslinking, drying agents, such as lead, cobalt, iron, manganese and copper salts, may be added.

The aqueous radiation-curable polyurethane dispersions according to the invention can be applied to various substrates by conventional techniques, preferably spraying, rolling, flow coating, printing, knife coating, pouring, brushing and dipping.

Substantially all substrates can be painted or coated with the aqueous radiation-curable polyurethane dispersions according to the invention. Preferred substrates are selected from mineral substrates, wood materials, furniture, parquet, doors, window frames, metal objects, plastics, paper, cardboard, cork, mineral substrates, textiles or leather. They are suitable here as base coats and/or as top coats. In addition, the aqueous radiation-curable polyurethane dispersions according to the invention can also be used or employed as adhesives, for example in contact adhesives, in heat-activated adhesives or in laminating adhesives.

The aqueous radiation-curable polyurethane dispersions according to the invention can be used alone but also in binder mixtures with other dispersions. The further dispersions may be those which likewise contain unsaturated groups, for example dispersions based on polyesters, polyurethanes, polyepoxide (meth) acrylates, polyethers, polyamides, polysiloxanes, polycarbonates, polyesteracrylates, polyurethane-polyacrylates and/or polyacrylates which contain unsaturated polymerizable groups.

Those dispersions based on polyesters, polyurethanes, polyethers, polyamides, polyvinyl esters, polyvinyl ethers, polysiloxanes, polycarbonates and/or polyacrylates having functional groups such as alkoxysilane groups, hydroxyl groups and/or optionally isocyanate groups in blocked form can also be included in the coating systems according to the invention. Thus a dual cure system can be prepared which can cure by two different mechanisms.

Also for dual-cure systems, it is furthermore possible to add so-called crosslinkers to the coating systems according to the invention. Preference is given to unblocked and/or blocked polyisocyanates, polyaziridines, polycarbodiimides and melamine resins. For aqueous coating agents, unblocked and/or blocked hydrophilicized polyisocyanates are particularly preferred. Preferably, 20% by weight or less, particularly preferably 10% by weight or less, of the solid crosslinking agent is added, based on the solids content of the coating agent.

Dispersions based on polyesters, polyurethanes, polyethers, polyamides, polysiloxanes, polyvinyl ethers, polybutadienes, polyisoprenes, chlorinated rubbers, polycarbonates, polyvinyl esters, polyvinyl chlorides, polyacrylates, polyurethane-polyacrylates, polyester acrylates, polyether acrylates, alkyd compounds, polyepoxide compounds or polyepoxide (meth) acrylates which do not have functional groups may also be included in the coating system according to the invention. The degree of crosslinking density, which influences physical drying, for example, is increased, or elastification or adhesion regulation can be carried out, can thereby be reduced.

Melamine-or urea-based amino crosslinker resins and/or polyisocyanates having free or blocked polyisocyanate groups based on hexamethylene diisocyanate, isophorone diisocyanate and/or tolylene diisocyanate with urethane-, uretdione-, iminooxadiazinedione-, isocyanurate-, biuret-and/or allophanate structures, optionally containing hydrophilicizing groups, can also be added to the coating agents comprising the aqueous radiation-curable urethane acrylates according to the invention. Carbodiimides or polyazetidines may also be used as further crosslinking agents.

Binders, auxiliary substances and additives known in the lacquer art, such as pigments, colorants or matting agents, can be added to or combined with the coating agents according to the invention. These are flow-and wetting additives, slip additives, pigments including metal effect pigments, fillers, nanoparticles, photoprotectant particles, anti-yellowing additives, thickeners and additives for reducing the surface tension.

The coating agent according to the invention is suitable for the coating of films, in which deformation of the coating film occurs between oxidative drying and UV curing.

The coating compositions according to the invention are suitable for use as clear lacquers on wood and plastic substrates, where blocking resistance after physical drying and good chemical resistance after radiation curing are important.

The coating compositions according to the invention are particularly suitable for use in colour formulations for the production of coatings for wood and plastics.

The coating compositions according to the invention are most particularly suitable for use in preparations for the colour and black colouring of coatings for wood and plastics.

The present invention also provides a coating agent comprising: the radiation-curable aqueous dispersions according to the invention based on urethane acrylates, and also crosslinking agents based on amino resins, blocked polyisocyanates, unblocked polyisocyanates, polyaziridines and/or polycarbodiimides, and/or one or more further dispersions.

Furthermore, the present invention provides substrates coated with the coating agents according to the invention.

Examples

The NCO content was monitored in each case by titration in accordance with DIN 53185.

The solids content of the polyurethane dispersions was determined gravimetrically after evaporation of all nonvolatile constituents in accordance with DIN 53216.

The average particle size was determined by laser correlation spectroscopy.

The run-off time was measured according to DIN 53211 by means of a4 mm DIN cup.

The OH number was determined in accordance with DIN 53240 using acetic anhydride and the iodine number in accordance with DIN 53241-1.

The room temperature means 23 ℃.

1) Polyesters based on unsaturated oils

3200 g of castor oil and 1600g of soybean oil and 2.4 g of lithium hydroxide were weighed into a 5 l reactor with a distillation apparatus. A stream of nitrogen (5 l/h) was passed through the reaction. Heating to 240 ℃ within 140 min. After 7 h at 240 ℃ the mixture was allowed to cool. OH number 109 mg KOH/g substance, acid number 3.2mg KOH/g substance, iodine number 97 mg I₂Per 100 g of material.

2) Preparation of radiation-curable aqueous polyurethane Dispersion (according to the invention)

168.9 parts of bisphenol A-diglycidyl diacrylate AgiSyn^®1010 (AGI corp., taipei, taiwan), component a), 247.1 parts of polyester 1), component C), 32.0 parts of dimethylolLevulinic acid, component E), 323.1 parts of 4,4' -diisocyanatodicyclohexylmethane, component F), and 0.7 part of dibutyltin dilaurate are dissolved in 220 parts of acetone and reacted with stirring at 60 ℃ to an NCO content of up to 4.0% by weight. Then, neutralization was carried out by adding and stirring 21.0 parts of triethylamine, and 78.6 parts of ditrimethylolpropane tetraacrylate Ebecryl was added^®140 (Cytec Surface specialties SA/NV, Drogenbos, Belgium), component (ii). The clear solution was introduced into 1230 parts of water with stirring. Subsequently, a mixture of 22.3 parts of ethylenediamine, component G), and 84.0 parts of water is added to the dispersion with stirring. The acetone was then distilled off from the dispersion under a slight vacuum. Radiation-curable aqueous polyurethane dispersion 2) having a solids content of 37% by weight, an outflow time of 18 seconds, a mean particle diameter of 95 nm and a pH of 8.4 was obtained.

3) Preparation of radiation-curable aqueous polyurethane Dispersion (according to the invention)

37.3 parts of bisphenol A-diglycidyl diacrylate AgiSyn^®1010 (AGI corp., taibei, taiwan), component a), 120.7 parts of polyester acrylate AgiSyn^®720 (AGI Corp., Taipei, Taiwan), component B), 109.8 parts of polyester 1), component C), 8.2 parts of trimethylolpropane, component D), 4.5 parts of 1, 4-butanediol, component D), 22.1 parts of dimethylolpropionic acid, component E), 199.9 parts of 4,4' -diisocyanatodicyclohexylmethane, component F), and 0.6 part of dibutyltin dilaurate are dissolved in 175 parts of acetone and the solution is reacted at 60 ℃ with stirring to an NCO content of up to 1.9% by weight. Neutralization is then carried out by adding and stirring 15.2 parts of triethylamine. The clear solution is introduced into 900 parts of water with stirring. Subsequently, a mixture of 8.1 parts of ethylenediamine, component G), and 24.0 parts of water is added to the dispersion with stirring. The acetone was then distilled off from the dispersion under a slight vacuum. A radiation-curable aqueous polyurethane dispersion 3) having a solids content of 40% by weight, an outflow time of 24 seconds, an average particle diameter of 146 nm and a pH of 8.8 was obtained.

4) Preparation of radiation-curable aqueous polyurethane dispersions (not according to the invention)

241.5 bisphenol A-diglycidyl diacrylate AgiSyn^®1010 (AGI Corp., Taipei, Taiwan), component A), 127.27 parts of polyester Desmophen^®PE 170 HN (Bayer MaterialScience AG, Leverkusen, Germany), component D), 5.25 parts of neopentyl glycol, component D), 31.98 parts of dimethylolpropionic acid, component E), 323.10 parts of 4,4' -diisocyanatodicyclohexylmethane, component F), and 0.7 part of dibutyltin dilaurate are dissolved in 200 parts of acetone and the solution is reacted at 50 ℃ with stirring to an NCO content of up to 3.7% by weight. 80.50 parts of propoxylated glyceryl triacrylate OTA 480 (Cytec Surface Specialties SA/NV, Drogenbos, Belgium), component (ii), and 78.32 parts of ditrimethylolpropane tetraacrylate Ebecryl^®140 (Cytec Surface specialties SA/NV, Drogenbos, Belgium), the mixture of component (ii) is added to the solution obtained in this way and stirred. Then, neutralization was carried out by adding and stirring 22.93 parts of triethylamine. The clear solution was introduced into 1150 parts of water with stirring. Subsequently, a mixture of 22.36 parts of ethylenediamine, component G), and 134.2 parts of water is added to the dispersion with stirring. The acetone was then distilled off from the dispersion under a slight vacuum. A radiation-curable aqueous polyurethane dispersion 4) having a solids content of 40% by weight, an outflow time of 34 seconds, an average particle diameter of 125 nm and a pH of 8.5 was obtained.

5) Preparation of a1) of EP-A1914253 unsaturated polyester resins modified with dicyclopentadiene

42.47 parts of maleic anhydride and 22.95 parts of diethylene glycol are weighed into a stainless steel apparatus with electrical heating, built-in serpentine condenser, armature stirrer, reflux condenser, column, glass bridge and nitrogen inlet or throughflow, inertized with nitrogen and heated to 150 ℃ in 1 hour under nitrogen overflow and with exothermic reaction conditions, and stirred at this temperature for 1 hour to complete the formation of the half-ester. After cooling to 140 ℃, 16.45 parts of dicyclopentadiene are added and the mixture is kept at 140 ℃ for 4 hours. Subsequently, the acid value (205+/-5) and OH value (<15) were measured. Then 5.95 parts ethylene glycol, 17.73 parts diethylene glycol and 0.2 part methyl hydroquinone are added. The mixture was heated to 190 ℃ so that the temperature at the top of the column did not rise above 105 ℃ and was maintained at this temperature until an acid number of about 12 and a hydroxyl number of 105-125 mg KOH/g of substance were reached by esterification. After cooling to 150 ℃, 0.1 part of methylhydroquinone and 0.03 part of trimethylhydroquinone are added. The mixture was then further cooled to 55 ℃ and dissolved in acetone. A 71% solution of unsaturated polyester resin 5) modified with dicyclopentadiene was obtained.

6) Preparation of a radiation-curable aqueous polyurethane Dispersion based on an unsaturated, dicyclopentadiene-modified polyester resin, example 2 of EP-A1914253) (not according to the invention)

158.4 parts of the acetone solution prepared in example 5), 425.6 parts of a polyester acrylate Laromer^®PE 44F (BASF AG, Ludwigshafen, germany), component B), 26.8 parts of dimethylolpropionic acid, component E), 50.4 parts of hexamethylene diisocyanate and 102.2 parts of isophorone diisocyanate, component F), and 0.6 part of dibutyltin dilaurate are dissolved in 180 parts of acetone and the solution is reacted at 50 ℃ with stirring to an NCO content of up to 1.6% by weight. 20.2 parts of triethylamine were added to the polymer solution obtained in this manner and stirred. The clear solution is then introduced with stirring into 1100 parts of distilled water and a mixture of 10.2 parts of ethylenediamine, component G) and 31.0 parts of water is added to the dispersion. Acetone was distilled off from the dispersion under a slight vacuum. An unsaturated polyurethane dispersion 6) comprising a polyester modified with dicyclopentadiene and having a solids content of 40% by weight, an outflow time of 27 seconds, an average particle diameter of about 112 nm and a pH of 8.1 is obtained.

Watch (A) 1:Formulation of coloured systems

¹Adjusted to 35% solids with water/butanediol = 1/1

²From BYK, Wesel, GermanyDefoaming agents based on polysiloxanes

³Levelling agents based on polyether-modified hydroxy-functional polydimethylsiloxanes from BYK, Wesel, Germany

⁴Iron-based drying agents for oxidative drying from OMG Borchers GmbH, Langenfeld, Germany

⁵Silica-based matting agents from Evonik Industries AG, Essen, Germany

⁶Aqueous dispersions of polyethylene waxes from BYK, Wesel, Germany

⁷Mixtures of benzophenone and (1-hydroxycyclohexyl) phenyl methanone from Ciba, Lampertheim, Germany

⁸Phenyl-bis- (2,4, 6-trimethylbenzoyl) phosphine oxides from Ciba, Lampertheim, Germany

⁹Polyurethane-based thickeners from Munzing Chemie GmbH, Heilbronn, Germany

¹⁰Yellow pigment Xfast^®Yellow 1256 (arylate yellow), Red pigment Xfast^®Red 3860 (diketopyrrolopyrrole) available from BASF SE, Ludwigshafen, germany.

Watch (A) 2:Application and curing conditions for colored pigmented systems

After thermal drying for water evaporation, the coatings of examples 2, 3 and 4 were very tack-free, i.e. capable of pressing a finger on the coating without leaving an impression. The coating from example 6 is still slightly tacky and accordingly susceptible to dust or mechanical damage. After radiation curing, the coated substrates were stored at room temperature for three days and then examined. Oxidative curing was carried out by atmospheric oxygen during three days at room temperature.

Watch (A) 3:Yellow pigmented clear coats without drying agent 1h after radiation curing and before oxidative curing [ A-1]Using the test data

Use test¹¹

¹¹The resistance was evaluated by visual observation after exposure (duration in hours).

Grade 5: no visible change (no damage).

Grade 4 gloss or shade changes slightly, only if the light source in the test surface is reflected on or very close to the mark and directly to the observer's eye, or just some well-discernable definite mark is detected (discernable swelling ring, or no softening detected with the fingernail).

Grade 3-slight markings are visible from multiple viewing angles, such as just discernible almost complete circles or circular areas (discernible swelling rings, or detectable nail scratches).

Grade 2: heavily marked, but the surface structure is largely unchanged (closed swelling ring, detectable scratch).

Grade 1 severe mark, but with most unchanged surface structure, the mark can scratch down to the substrate.

For oxidative curing, the coatings were stored at room temperature for three days.

Watch (A) 4:Yellow pigmented varnish without drying agent after radiation and oxidative curing [ A-1 ]]Using the test data

Use test¹²

¹²See footnote 11, table 3.

Watch (A) 5:Yellow pigmented varnish without drying agent after radiation and oxidative curing [ A-3 ]]Using the test data

Use test¹³

¹³See footnote 11, table 3.

Watch (A) 6:Red pigmented varnish without drying agent after radiation and oxidative curing [ A-2 ]]Using the test data

Use test¹⁴

¹⁴See footnote 11, table 3.

Watch (A) 7:Red clearcoats without siccatives after radiation and oxidative curing [ A-4 ]]Using test data of

Test of use¹⁵

¹⁵See footnote 11, table 3.

Table 3 shows the chemical resistance immediately after radiation curing. At this point in time, little oxidative cure occurred. The coatings according to examples 1 and 2 of the invention have been very well tolerated and are at the level of comparative example 4. From experience, coatings from fully oxidatively drying systems, for example those from alkyd resins or aqueous polyurethane dispersions based on alkyd resins, are still very soft at this point in time, and therefore mechanical and chemical resistance tests are not carried out with these systems.

Substrates coated with the adhesive according to the invention can already be assembled and subsequently further oxidatively cured during storage or during transport.

The effect of oxidative curing at room temperature for three days after radiation curing is shown in tables 4-7. In the yellow and red varnishes without drying agent (tables 4 and 6), examples 2 and 3 according to the invention show better resistance than comparative examples 4 and 6. This becomes particularly evident in the case of water/ethanol (50%). It is again emphasized that example 4, although based on polyepoxyacrylates, does not contain unsaturated fatty acid-containing polyesters. The advantages of the combination of a polyepoxy acrylate and a polyester comprising unsaturated fatty acids as in examples 2 and 3 are thus apparent.

By adding the drying agents (tables 5 and 7), the resistance of examples 2 and 3 becomes even better, while no improvement is observed in examples 4 and 6, since they contain no oxidatively curable groups. The addition of a drying agent promotes oxidative curing. Coatings without desiccants will achieve similarly good results over longer periods of time.

It also becomes apparent that the higher proportion of aromatic polyepoxy acrylate and unsaturated fatty acid containing polyester in example 2 results in better resistance compared to example 3.

Claims (16)

1. Radiation-curable aqueous dispersion based on a urethane acrylate (i), characterized in that the urethane acrylate (i) comprises as building components:

A) one or more aromatic poly (epoxy) (meth) acrylates having an OH number of from 20 to 300mg KOH/g of substance,

C) one or more transesterification products of castor oil and one or more oils having an iodine value of greater than 100, said transesterification products having an OH value of 15 to 300mg KOH/g substance and an OH value of greater than 50 g I₂The iodine number per 100 g of substance,

E) one or more compounds having at least one isocyanate-reactive group and additionally at least one hydrophilicizing group, and

F) one or more organic polyisocyanates.

2. The aqueous radiation-curable dispersion based on urethane acrylates (i) according to claim 1, characterized in that it comprises a component B) which is different from a) and has at least one isocyanate-reactive group and at least one radiation-curable double bond.

3. Radiation-curable aqueous dispersions based on urethane acrylates (i) according to one of claims 1 to 2, characterised in that they comprise component D) with one or more compounds having at least one isocyanate-reactive group but no radiation-curable and oxidatively curable double bonds.

4. Radiation-curable aqueous dispersion based on urethane acrylates (i) according to one of claims 1 to 2, characterized in that it comprises a component G) which is different from a) to F) and has at least one amine function.

5. Radiation-curable aqueous dispersions based on urethane acrylates (i) according to one of claims 1 to 2, characterised in that the aqueous dispersions comprise as component (ii) a reactive diluent having at least one radical-polymerizable group.

6. Radiation curable aqueous dispersion according to one of claims 1 to 2, characterised in that component a) comprises the reaction product of (meth) acrylic acid with an aromatic glycidyl ether selected from monomeric, polymeric bisphenol a and/or bisphenol F or alkoxylated derivatives thereof.

7. Radiation curable aqueous dispersion according to claim 6, characterized in that the polymerization is referred to as oligomerization.

8. Radiation curable aqueous dispersion according to one of claims 1 to 2, characterised in that component C) is a transesterification product from castor oil and soybean oil.

9. Radiation curable aqueous dispersion according to one of claims 1 to 2, characterized in that it is free of unsaturated dicyclopentadiene modified polyester resins.

10. Radiation-curable aqueous dispersion according to one of claims 1 to 2, characterised in that it comprises 5 to 45% by weight of component a) and 15 to 65% by weight of component C).

11. Process for the preparation of radiation-curable aqueous dispersions based on urethane acrylates (i) according to one of claims 1 to 10, characterized in that the urethane acrylate (i) is obtained by reacting components a) to E) with component F) in one or more reaction steps, wherein before, during or after the preparation of the addition product of a) to F) a neutralizing agent can be added to generate the ionic groups required for the dispersion, followed by a dispersion step by adding water to the addition product of a) to F) or transferring the addition product of a) to F) into an aqueous container, wherein before, during or after the dispersion a chain extension can be carried out by component G).

12. Use of the radiation-curable aqueous dispersions according to one of claims 1 to 11 for the preparation of coatings.

13. Use of the radiation-curable aqueous dispersions according to one of claims 1 to 11 for the preparation of varnishes and adhesives.

14. Coating agent comprising a urethane acrylate-based radiation-curable aqueous dispersion according to one of claims 1 to 13.

15. Use of the coating agent according to claim 14 in colour formulations for coating wood and plastics.

16. A substrate coated with a coating agent according to claim 14.