Transparent PUD and application thereof

Abstract

The invention relates to an aqueous dispersion comprising at least one polyurethane, the at least one polyurethane being prepared from at least the following components: (A) at least one polyisocyanate, (B) at least one polymeric polyol having a number average molecular weight of 400 to 6000 g / mol, wherein the at least one polycarbonate polyol is present in the polymeric polyol component (B) in an amount of 55 to 100 wt%, based on the total weight of component (B), (C) optionally, at least one monofunctional non-ionic hydrophilic agent, (D) at least one compound selected from the group consisting of polyols, amino polyols, polyamines and mixtures thereof, in each case having a number average molecular weight of less than 400 g / mol, and (E) optionally, at least one compound selected from the group consisting of polyols, amino polyols, polyamines and mixtures thereof, (E) at least one compound selected from monoalcohols, diols, polyols, monoamines, diamines, polyamines and mixtures thereof, in each case having at least one salt group, preferably an anionic group, or a functional group that can be converted into a salt group, preferably into an anionic group, (F) at least a neutralizing agent, the present invention relates to at least one polyurethane dispersion selected from the group consisting of tertiary amine compounds having a boiling point at atmospheric pressure above 100 DEG C, inorganic bases, preferably potassium hydroxide, sodium hydroxide, and mixtures thereof, the at least one polyurethane dispersion having an average particle size D (i) 90 of 20 nm to 95 nm and the viscosity of the dispersion being 50 to 1500 mPa.s, to coating formulations comprising such aqueous dispersions, and to the use thereof. The present invention relates to an aqueous dispersion for coating a substrate, to the use of such an aqueous dispersion in a coating formulation, to a method for coating a substrate, in which a coating formulation comprising such an aqueous dispersion is used, to the use of such a coating formulation for coating a substrate, and to a substrate coated with the coating formulation.

Description

[0001] The present invention relates to an aqueous dispersion comprising at least one polyurethane, wherein the at least one polyurethane is prepared from at least the following components: (A) at least one polyisocyanate, (B) at least one polymeric polyol having a number-average molecular weight of 400 to 6000 g / mol, wherein at least one polycarbonate polyol is present in the polymeric polyol component (B) in an amount of 55 to 100% by weight, based on the total weight of component (B), (C) optionally, at least one monofunctional nonionic hydrophilizing agent, (D) at least one compound selected from the group consisting of polyols, aminopolyols, polyamines and mixtures thereof, in each case having a number-average molecular weight of less than 400 g / mol, (E) at least one compound selected from the group consisting of monools, diols, polyols, monoamines, diamines, polyamines and mixtures thereof, in each case having a at least one salt group, preferably an anionic group, or a functional group convertible into a salt group, preferably into an anionic group, (F) at least one neutralizing agent selected from tertiary amine compounds having a boiling point above 100° C. at atmospheric pressure, inorganic bases, preferably potassium hydroxide, sodium hydroxide, and mixtures thereof, wherein the at least one polyurethane dispersion has an average particle size D(i)90 of 20 nm to 95 nm and wherein the viscosity of the dispersion is 50 to 1500 mPa·s, coating formulations comprising such aqueous dispersions, use of such aqueous dispersions in coating formulations, methods for coating substrates, using coating formulations comprising such aqueous dispersions, use of such coating formulations for coating substrates, and substrates coated with the coating formulations.

[0002] A good wet color match means that the color difference between the paint film in wet conditions and the paint film in dry conditions is as close as possible. A good wet color match helps body shops improve efficiency, for example. A key step in the base coat repainting workflow is color comparison or color matching, i.e., the comparison between the paint mixed for the repair of the car's exterior and the corresponding color of the car.

[0003] Solvent-based paint formulations typically offer better wet color matching than water-based paint formulations. However, as paint manufacturers implement increasingly stringent VOC restrictions, there's a growing trend away from solvent-based paint formulations and toward water-based paint formulations. If a water-based paint formulation offers excellent wet color matching, painters can save an average of over two hours by avoiding waiting for the water to evaporate.

[0004] Furthermore, with improved living standards and the increasing prevalence of cars in households, people are increasingly concerned about in-car air quality. In-car air quality is primarily assessed based on two factors: the level of volatile organic compounds (VOCs) and the degree of odor. In the Initial Quality Study (IQS) PP100 (problems per 100 vehicles) ranking, "unpleasant odor / smell" has consistently topped the list in recent years. Consumers are increasingly demanding minimal odor in their cars. As a source of odor, coatings are also required to have low odor.

[0005] Some polyurethane dispersion synthesis methods known in the prior art include the use of solvents such as N-methylpyrrolidone (NMP) or N-ethylpyrrolidone (NEP) to obtain products in which the polyurethane particles have a reduced particle size and the polyurethane dispersion itself has a lower viscosity. However, due to their reproductive toxicity, the use of organic solvents such as NMP or NEP is prohibited in more and more industries.

[0006] The object of the present invention is therefore to provide a polyurethane dispersion which is essentially free of any organic solvents, in particular free of organic solvents which are prohibited for use in consumer products. In addition, the polyurethane dispersion should have an improved wet color match and a lower odor, in particular compared to the polyurethane dispersions known in the prior art.

[0007] These objects are achieved according to the invention by an aqueous dispersion comprising at least one polyurethane, wherein the at least one polyurethane is prepared from at least the following components:

[0008] (A) at least one polyisocyanate,

[0009] (B) at least one polymeric polyol having a number-average molecular weight of 400 to 6000 g / mol, wherein the at least one polycarbonate polyol is present in the polymeric polyol component (B) in an amount of 55 to 100% by weight, based on the total weight of component (B),

[0010] (C) optionally, at least one monofunctional nonionic hydrophilizing agent,

[0011] (D) at least one compound selected from monools, diols, polyols, aminopolyols, monoamines, diamines, polyamines and mixtures thereof, in each case having a number average molecular weight of less than 400 g / mol,

[0012] (E) at least one compound selected from monools, diols, polyols, monoamines, diamines, polyamines and mixtures thereof, in each case having at least one salt group, preferably anionic group, or a functional group convertible into a salt group, preferably into anionic group,

[0013] (F) at least a neutralizing agent selected from tertiary amine compounds having a boiling point above 100° C. at atmospheric pressure, inorganic bases, preferably potassium hydroxide, sodium hydroxide, and mixtures thereof,

[0014] wherein the at least one polyurethane dispersion has an average particle size D(i)90 of 20 nm to 95 nm and wherein the viscosity of the dispersion is 50 to 1500 mPa·s.

[0015] The polyurethane dispersions according to the invention are described in detail below. In the sense of the present invention, the term polyurethane refers to polyurethanes and / or polyurethane-ureas.

[0016] In the sense of the present invention, the expressions “substantially free of any organic solvent” and “free of organic solvent” mean that the content of organic solvent is not more than 1% by weight, based on the total amount of the polyurethane dispersion.

[0017] The polyurethane dispersion according to the invention comprises at least one polyurethane prepared from at least components (A), (B), (C), (D), (E) and (F) as described above.

[0018] In addition to components (A), (B), (C), (D), (E) and (F), the at least one polyurethane used according to the invention may comprise further components. According to a preferred embodiment, in addition to components (A), (B), optionally (C), (D), (E) and (F), the at least one polyurethane used according to the invention does not comprise further components, i.e. the at least one polyurethane used according to the invention consists of (A), (B), optionally (C), (D), (E) and (F).

[0019] Component (A):

[0020] At least one polyisocyanate is used as component (A).

[0021] In general, any polyisocyanate known to the skilled person can be used according to the invention.According to one preferred embodiment, a mixture of at least two different polyisocyanates is used according to the invention.

[0022] According to the invention, the at least one polyisocyanate is generally an organic compound having at least two isocyanate groups.

[0023] Therefore, the at least one polyisocyanate used according to the present invention is preferably selected from diisocyanates having the general formula Y(NCO)2, wherein Y is a C4-12 divalent aliphatic hydrocarbon group, i.e. an aliphatic diisocyanate compound, a C6-15 divalent alicyclic hydrocarbon group, i.e. an alicyclic diisocyanate compound, a C6-15 divalent aromatic hydrocarbon group, i.e. an aromatic diisocyanate compound, or a C7-15 divalent araliphatic hydrocarbon group, i.e. an araliphatic diisocyanate compound.

[0024] Preferred examples of such organic diisocyanate compounds according to the present invention include tetramethylene diisocyanate, methylpentamethylene diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 1,2-bis(isocyanatomethyl)cyclohexane, 1,4-cyclohexane diisocyanate, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI, isophorone diisocyanate), 4 ... ,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylpropane diisocyanate-(2,2), 1,4-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, p-xylylene diisocyanate, p-isopropylidene diisocyanate and 1,5-naphthalene diisocyanate.

[0025] The at least one polyisocyanate used according to the present invention can also be a polyisocyanate with three or more isocyanate groups per molecule.The example of such organic polyisocyanate compounds can be, for example, a modified preparation of an aliphatic, alicyclic, aromatic and / or aromatic diisocyanate composed of at least two types of diisocyanates and with uretdione, isocyanurate, ammonia, allophanate, biuret, carbodiimide, iminooxadiazinedione and / or oxadiazinetrione structure.An example of unmodified polyisocyanate with three or more isocyanate groups per molecule includes 4-isocyanatomethyl-1,8-octane diisocyanate (nonane triisocyanate).

[0026] According to a preferred embodiment of the present invention, the at least one polyisocyanate is selected from hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI, isophorone diisocyanate), 4,4'-dicyclohexylmethane diisocyanate ( W) and mixtures thereof.

[0027] Particularly preferably, 4,4'-dicyclohexylmethane diisocyanate ( W) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI, isophorone diisocyanate). 4,4'-dicyclohexylmethane diisocyanate (

[0028] The molar ratio of W) to 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI, isophorone diisocyanate) is preferably 1:10 to 10:1, more preferably 1:6 to 6:1.

[0029] In general, component (A) is present in the polyurethanes according to the invention in an amount of 5 to 60% by weight, preferably 10 to 50% by weight, particularly preferably 15 to 45% by weight, based in each case on the polyurethane.

[0030] Component (B):

[0031] At least one polymeric polyol having a number-average molecular weight of 400 to 6000 g / mol is used as component (B), wherein the at least one polycarbonate polyol is present in the polymeric polyol component (B) in an amount of 55 to 100% by weight, based on the total weight of component (B).

[0032] The polymeric polyol having a molecular weight of 400 to 6000 g / mol used as component (B) has at least two isocyanate-reactive hydroxyl groups.

[0033] Examples of the at least one polymeric polyol compound used according to the present invention are selected from polyether polyols, polyester polyols, polycarbonate polyols, polycarbonate polyester polyols, polylactone polyols, polybutadiene polyols, silicone polyols and mixtures thereof.

[0034] Preferred components (B) preferably contain 2 to 4, particularly preferably 2 to 3, and most preferably 2 hydroxyl groups. Furthermore, component (B) can also be a mixture of various compounds of this type.

[0035] Examples of the polyether polyol include cyclic ether addition polymers and polyol condensates. Examples of the cyclic ether include styrene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, and epichlorohydrin, and these may be used alone or in combination.

[0036] The polyester polyols used according to the present invention are preferably polyester polyols having hydroxyl groups at least at both ends of the main chain. Examples of polyester polyols include straight-chain polyester diols and slightly branched polyester polyols. These can be prepared by known methods using aliphatic, alicyclic or aromatic dicarboxylic acids and diols and optionally using polycarboxylic acids and / or high-functionality polyols.

[0037] Examples of the polylactone polyol used as component (B) are homopolymers or copolymers of lactone having hydroxyl groups at both ends of at least the main chain.

[0038] Examples of polycarbonate polyols used as component (B) according to the present invention are obtained by reacting a diol with an aryl carbonate (e.g., diphenyl carbonate) and / or an alkyl carbonate (e.g., dimethyl carbonate), wherein the diol is one or more selected from 1,3-propylene glycol, 1,4-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, and 2,2-dimethyl-1,3-propanediol. Polycarbonate polyols obtained from dimethyl carbonate and 1,6-hexanediol are preferably used.

[0039] The polycarbonate polyol according to the present invention preferably has hydroxyl groups at least at both ends of the main chain, and is produced by adjusting the production conditions of the polycarbonate.

[0040] Preferably, at least one polycarbonate polyol is used as component (B) according to the present invention, which is selected from polycarbonates obtained by reaction of dimethyl carbonate with 1,6-hexanediol, polycarbonates obtained by reaction of dimethyl carbonate with 1,6-hexanediol and 1,4-butanediol, and / or copolymers of polycaprolactone and polycarbonate obtained by reaction of dimethyl carbonate with 1,6-hexanediol. The preferred number-average molecular weight of the polycarbonate polyester polyol is between 1000 and 4000 g / mol.

[0041] The at least one polycarbonate polyol is present in the polymeric polyol component (B) in an amount of 55 to 100% by weight.

[0042] The organosilicon polyol used as component (B) according to the present invention includes silicone oils having a hydroxyl group at the terminal end thereof having a siloxane bond in the molecule.

[0043] Preferably, according to the present invention, the at least one polymeric polyol (B) is selected from polycarbonate polyols, polyester polyols, polyether polyols, polycarbonate polycaprolactone polyols and mixtures thereof.

[0044] The polymeric polyol used as component (B) has a molecular weight of 400 to 6000 g / mol, preferably 800 to 5000 g / mol, more preferably 1000 to 4000 g / mol.

[0045] According to the invention, component (B) is contained in the polyurethane used according to the invention in an amount of preferably 20 to 85% by weight, more preferably 25 to 80% by weight and even more preferably 30 to 75% by weight, based in each case on the polyurethane.

[0046] Component (C):

[0047] At least one monofunctional nonionic hydrophilizing agent is used as optional component (C).

[0048] Examples of monofunctional nonionic hydrophilic agents that can be used as component (C) according to the present invention are selected from polyethylene oxide monoalkyl ethers and polyethylene oxide polypropylene oxide copolymer monoalkyl ethers; preferably one or more are selected from polyethylene oxide monomethyl ether and polyethylene oxide polypropylene oxide copolymer monomethyl ether and mixtures thereof.

[0049] When at least one monofunctional nonionic hydrophilizing agent is present in the polyurethane according to the invention, it is preferably used in an amount of less than 10% by weight, more preferably less than 5% by weight, based on the solids content of the aqueous polyurethane resin. When at least one monofunctional nonionic hydrophilizing agent is present in the polyurethane according to the invention, the lower limit of this amount is generally 0.1% by weight, based on the solids content of the aqueous polyurethane resin.

[0050] Component (D):

[0051] As component (D), at least one compound selected from the group consisting of monools, polyols, aminopolyols, monoamines, polyamines and mixtures thereof is used, in each case having a number-average molecular weight of less than 400 g / mol.

[0052] The monoamine according to the present invention is a compound having one amino group or imino group. Examples of the monoamine compound include propylamine, butylamine, pentylamine, hexylamine, 1-tetradecylamine and mixtures thereof.

[0053] The polyamine according to the present invention is a compound having two or more amino groups and / or imino groups. Examples of the polyamine compound include triamine compounds such as diethylenetriamine, bis(2-aminopropyl)amine and bis(3-aminopropyl)amine; tetraamine compounds such as triethylenetetramine, tripropylenetetramine, N-(benzyl)triethylenetetramine, N,N'-(dibenzyl)triethylenetetramine and N-(benzyl)-N"'-(2-ethylhexyl)triethylenetetramine; pentamine compounds such as tetraethylenepentamine and tetrapropylenepentamine; hexamine compounds such as penta- ethylenehexamine and pentapropylenehexamine; and polyamine compounds such as polyethyleneimine and polypropyleneimine, and mixtures thereof. From the viewpoint of reactivity with the polyurethane prepolymer, the polyamine is preferably a polyamine having two amino groups and one or more imino groups, such as diethylenetriamine, triethylenetetramine, bis(2-aminopropyl)amine, bis(3-aminopropyl)amine, tripropylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, pentaethylenehexamine, or pentapropylenehexamine.

[0054] Examples of the diamine compound that can be used as component (D) include hydrazine, 1,2-ethylenediamine, 1,4-tetramethylenediamine, 2-methyl-1,5-pentanediamine, 1,6-hexamethylenediamine, 1,4-hexamethylenediamine, 3-aminomethyl-3,5,5-trimethylcyclohexylamine, 1,3-bis(aminomethyl)cyclohexane, xylenediamine, piperazine, 2,5-dimethylpiperazine, and mixtures thereof.

[0055] The monool according to the present invention is a compound having one hydroxyl group. Examples of the monool compound that can be used as component (D) include butyl glycol, diethylene glycol monobutyl ether, dipropylene glycol) butyl ether, and mixtures thereof.

[0056] The polyol according to the present invention is a compound having two or more hydroxyl groups. Examples of the polyol compound that can be used as component (D) include ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol, 1,2-propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,4-dihydroxycyclohexane, 1,4- Dimethylcyclohexane, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 1,2-dihydroxybenzene, 2,2-bis(4-hydroxyphenyl)-propane (bisphenol A), TCD-diol, trimethylolpropane, glycerol, pentaerythritol, dipentaerythritol, and mixtures thereof.

[0057] The aminopolyols according to the invention are organic compounds having one or more hydroxyl groups and one or more amino groups.

[0058] Examples of amino polyols that can be used as component (D) include ethanolamine, propanolamine, butylethanolamine, 1-amino-2-methyl-2-propanol, 2-amino-2-methylpropanol, diethanolamine, diisopropanolamine, dimethylaminopropylethanolamine, dipropanolamine, N-methylethanolamine, N-ethylethanolamine, and mixtures thereof.

[0059] According to the present invention, one type may be used alone, or a plurality of types may be used in combination as component (D).

[0060] The amount of component (D) is preferably not greater than the equivalent weight of the residual isocyanate groups obtained after the reaction of the polyisocyanate and the polyol. The amount of reactive groups in component (D) is preferably 0.6 to 0.99 equivalent weight of the residual isocyanate groups.

[0061] Component (E):

[0062] As component (E) at least one compound selected from the group consisting of monools, diols, polyols, monoamines, diamines, polyamines and mixtures thereof is used, in each case having at least one salt group, preferably anionic group, or a functional group convertible into a salt group, preferably into anionic group.

[0063] The at least one salt group present in component (E) is preferably at least one acidic group. According to the present invention, the at least one acidic group may be selected from a carboxylic acid group or a sulfonic acid group.

[0064] Component (E) is preferably a compound having at least two or more hydroxyl groups and / or two or more amino groups. At least one compound having at least two or more hydroxyl groups is preferably used as component (E).

[0065] A combination of at least one compound containing carboxylic acid groups and at least one compound containing sulfonic acid groups may be used. Preferably, at least one compound containing carboxylic acid groups is used as component (E).

[0066] Component (E) is preferably present in the at least one polyurethane used according to the invention in an amount such that the total weight of compounds containing carboxylic acid groups and / or compounds containing sulfonic acid groups is preferably 0.5 to 10% by weight, more preferably 1 to 7% by weight, based in each case on the polyurethane.

[0067] The ratio of the acid value of the carboxylic acid group to the total acid value in component (E) is preferably 0.20 to 1.00, more preferably 0.50 to 1.00, and even more preferably 0.70 to 1.00. The acid value herein refers to a calculated value expressed as milligrams of potassium hydroxide required to neutralize the carboxyl groups or sulfonic groups present in the polyurethane resin (mgKOH / g). The total acid value refers to the sum of the acid value of the carboxyl group and the acid value of the sulfonic group.

[0068] Specific examples of the acidic group-containing compound that can be used as component (E) according to the present invention are acidic group-containing diol compounds having 4 to 12 carbon atoms, particularly preferably selected from N-(2-aminoethyl)-2-aminoethanesulfonic acid, N-(3-aminopropyl)-2-aminoethanesulfonic acid, N-(3-aminopropyl)-3-aminopropanesulfonic acid, N-(2-aminoethyl)-3-aminopropanesulfonic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, 3,6-dihydroxy-2-toluenesulfonic acid, and sodium salts, lithium salts, potassium salts, tertiary amine salts, and the like, which are reaction products obtained by Michael addition of a diamine (e.g., 1,2-ethylenediamine or isophoronediamine) with twice the molar amount of acrylic acid or maleic acid.

[0069] Most preferably, component (E) is selected from 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, N,N-bishydroxyethylglycine, N,N-bishydroxyethylalanine, 3,4-dihydroxybutanesulfonic acid, 3,6-dihydroxy-2-toluenesulfonic acid, 2-[(2-aminoethyl)amino]ethanesulfonic acid and its salts, and mixtures thereof.

[0070] Component (F):

[0071] At least a neutralizing agent selected from tertiary amine compounds having a boiling point above 100° C. at atmospheric pressure, inorganic bases, preferably potassium hydroxide, sodium hydroxide, and mixtures thereof is present as component (F).

[0072] The at least one neutralizing agent having a boiling point greater than 100°C at atmospheric pressure is typically used to neutralize at least some of the acidic groups of the polyurethane prepolymer and to disperse the polyurethane prepolymer in an aqueous medium. Examples of tertiary amine compounds such as trialkylamines preferably include N,N-diisopropylethylamine, tributylamine, etc., N,N-dialkylalkanolamines including N,N-dimethylethanolamine, N,N-dimethylpropanolamine, N,N-dipropylethanolamine, 1-dimethylamino-2-methyl-2-propanol, etc., N-alkyl-N,N-dialkanolamines, and trialkanolamines including triethanolamine, inorganic alkali metal salts such as potassium hydroxide and sodium hydroxide. These can be used alone or in combination of two or more. From the perspective of processability, the neutralizing agent is preferably an organic amine, more preferably N,N-dimethylethanolamine or N,N-diisopropylethylamine. The amount of the neutralizing agent is, for example, 0.4 to 1.2 equivalents, preferably 0.6 to 1.0 equivalents, per equivalent of the acidic group possessed by the aqueous polyurethane resin composition.

[0073] Component (F) is preferably present in the at least one polyurethane used according to the invention in an amount of 1 to 10% by weight, more preferably 1.5 to 8% by weight, based in each case on the polyurethane.

[0074] Preferably, the amounts of components (A), (B), optionally (C), (D), (E) and (F) in each case add up to 100% by weight.

[0075] The polyurethane dispersion according to the invention generally contains the at least one polyurethane in an amount of 20 to 60% by weight, preferably 25 to 50% by weight, particularly preferably 30 to 40% by weight, in each case based on the polyurethane dispersion. This solids content is measured using a Metteler TeredoHalogen Moisture Analyzer Excellence HS153 at 120°C.

[0076] The polyurethanes present in the polyurethane dispersions according to the invention generally have an average particle size of 25 to 70 nm, preferably 30 to 60 nm, particularly preferably 30 to 55 nm.

[0077] The polyurethane dispersion according to the present invention has an average particle size D(i)90 of 20 nm to 95 nm, preferably 50 nm to 90 nm. The average particle size is tested by a Malvern Zetasizer Nano ZS particle analyzer at 23°C. The average particle size refers to the Z-average particle size used in dynamic light scattering as defined in ISO 13321:1996. D(i)90 represents the point in the particle size distribution up to and including which 90% of the total intensity of the material in the "containing" sample is present. The average particle size and D(i)90 [nm] are measured as follows: 1 drop (approximately 0.05 grams) of PUD is added to 50 milliliters of ultrapure water. The diluted sample is tested by a Malvern ZetasizerNano ZS particle size analyzer at 23.0±0.1°C. Materials: Polystyrene latex (RI: 1.590; Absorbance: 0.010), Dispersant: Water (Temperature: 23.0°C; Viscosity: 0.9308 cP; RI: 1.330), Equilibration Time: 60 seconds, Cell Type: Disposable Cuvette DTS0012, Positioning Method: Automatic Decay Selection, Find Best Position: Yes, Analysis Model: General (Normal Resolution), Measurement Angle: 173° Backscatter (NIBS Default), Number of Runs: 3, Run Duration: 10 seconds, Number of Measurements: 10. Average particle size refers to the Z-average particle size used in dynamic light scattering as defined in ISO 13321:1996. D(i)90 represents the point in the particle size distribution up to and including the point at which 90% of the total intensity of the material in the sample "contains" is present.

[0078] In particular, the average particle size D(i)90 brings about the technical effects according to the invention and solves the objects according to the invention. If the average particle size D(i)90 is less than or equal to 100 nm, in particular from 20 nm to 95 nm, the wet color matching of the coating composition containing such a polyurethane dispersion is significantly improved.

[0079] The polyurethane dispersions according to the invention generally have a viscosity of 50 to 1500 mPa·s, preferably 70 to 1500 mPa·s, and particularly preferably 80 to 1200 mPa·s. This viscosity is measured using a Brookfield DV-II+ Pro viscometer at room temperature (23±2° C.) using a spindle S62 at a speed of 30 rpm in accordance with ISO 3219:1994.

[0080] The polyurethane dispersions according to the invention have an average transmittance of generally greater than 30%, preferably 40 to 99%, particularly preferably 55 to 99%. This average transmittance is measured at 23°C using a UV-2600 UV-VIS spectrophotometer (SHIMADZU, Japan) for light wavelengths between 420 nm and 700 nm.

[0081] The average molecular weight of the polyurethane resin in the aqueous polyurethane resin composition of the present invention is not particularly limited and can be selected within a range that provides dispersibility and a good coating film as a water-based coating, and is preferably 5,000 to 500,000 g / mol, more preferably 10,000 to 100,000 g / mol. In this specification, the average molecular weight of the polyurethane resin is a number average molecular weight measured by gel permeation chromatography, using polystyrene as a standard substance.

[0082] The acid value of the carboxylic acid groups in the polyurethane in the aqueous polyurethane dispersion according to the present invention is preferably 4.5 to 30 mg KOH / g, more preferably 5 to 28 mg KOH / g, and even more preferably 10 to 25 mg KOH / g. In this specification, the acid value of a resin refers to the number of milligrams of potassium hydroxide required to neutralize 1 gram of the resin. The acid value is a value measured by the indicator titration method according to JIS K 1557:2007.

[0083] The hydroxyl value of the polyol in the aqueous polyurethane dispersion according to the present invention is not particularly limited, but is generally between 1 and 100 mg KOH / g. In this specification, the hydroxyl value of a resin refers to the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 gram of polyol. The hydroxyl value is measured using the indicator titration method according to Method B of JIS K1557:2007.

[0084] The polyurethane dispersion according to the present invention is an aqueous dispersion that does not contain any organic solvent. Preferably, the upper limit of the content of organic solvent in the polyurethane dispersion according to the present invention is 1% by weight. The inventors of the present invention have surprisingly found that the polyurethane dispersion according to the present invention has a low viscosity even in the absence of an organic solvent.

[0085] The present invention further relates to a process for preparing the polyurethane dispersion according to the invention, comprising at least the following steps:

[0086] a. charging a reaction vessel with at least one polymeric polyol (B) and optionally a monofunctional nonionic hydrophilic agent (C), optionally removing the water contained in the pre-charged mixture to less than 0.2 wt %, preferably less than 0.1 wt %, by increasing the temperature and / or reducing the pressure and / or purging with nitrogen under stirring,

[0087] b. loading a portion or all of the amount of component (D) and / or a portion or all of the amount of component (E) into the reaction vessel,

[0088] c. reacting the precharged contents of the reaction vessel by metering in a mixture comprising at least one polyisocyanate (A), for example at a temperature of 60 to 135° C., and reacting the mixture at a temperature of 60 to 135° C. to obtain a prepolymer,

[0089] d. before or after step c, adding a solvent miscible with water but inert to isocyanate groups to dissolve the prepolymer from step c,

[0090] e. reacting the prepolymer with the portion of component (D) and component (E) not yet added in step b, for example at a temperature of 30 to 60° C. to obtain a polyurethane or polyurethane-urea,

[0091] f. before or after step d or e, adding at least one neutralizing agent, and

[0092] g. before, during or after step e, adding water to obtain an aqueous polyurethane-urea dispersion,

[0093] h. Removal of the solvent, preferably by distillation.

[0094] The solvent which is miscible with water but inert towards isocyanate groups is preferably selected from acetone, methyl ethyl ketone (MEK), propylene glycol dimethyl ether, any other ethers / esters without OH functionality and mixtures thereof.

[0095] In the method for producing an aqueous polyurethane dispersion, the step of neutralizing the acidic group and the step of dispersing the polyurethane prepolymer in an aqueous medium may be performed separately or together. In the method for producing an aqueous polyurethane dispersion, the step of reacting the polyurethane prepolymer with the compound (D) may be performed after the step of dispersing the polyurethane prepolymer in an aqueous medium, or may be performed together with the step of dispersing the polyurethane prepolymer in an aqueous medium.

[0096] Each step in the method of producing the aqueous polyurethane resin composition may be performed under an inert gas atmosphere, or may be performed in the atmospheric air.

[0097] The aqueous polyurethane dispersion may contain a neutralizing agent having a boiling point greater than 100°C at atmospheric pressure. The neutralizing agent is used to neutralize at least some of the acidic groups of the polyurethane prepolymer and disperse the polyurethane prepolymer in the aqueous medium. Examples of neutralizing agents include tertiary amine compounds, such as trialkylamines, including N,N-diisopropylethylamine and tributylamine, N,N-dialkylalkanolamines, including N,N-dimethylethanolamine, N,N-dimethylpropanolamine, N,N-dipropylethanolamine, and 1-dimethylamino-2-methyl-2-propanol, N-alkyl-N,N-dialkanolamines, and trialkanolamines, including triethanolamine, and inorganic alkali metal salts such as potassium hydroxide and sodium hydroxide. These can be used alone or in combination of two or more. From the perspective of processability, the neutralizing agent is preferably an organic amine, more preferably N,N-dimethylethanolamine or N,N-diisopropylethylamine. The amount of the neutralizing agent is, for example, 0.4 to 1.2 equivalents, preferably 0.6 to 1.0 equivalents, per equivalent of the acidic group possessed by the aqueous polyurethane resin composition.

[0098] The aqueous polyurethane dispersion according to the present invention may be further mixed with a solvent. The solvent is one or more selected from butyl glycol, butyl diglycol ethanol, 1-methoxy-2-propanol, dipropylene glycol monomethyl ether, propylene glycol butyl ether, dipropylene glycol butyl ether, and mixtures thereof. The amount of the solvent is preferably 10 to 25 wt % based on 100 wt % of the PUD.

[0099] In a preferred embodiment of the present invention, the temperature of the water introduced in step g is controlled and preferably set to a temperature between 0 and 40°C, more preferably between 2 and 30°C, and particularly preferably between 5 and 20°C.

[0100] It is also beneficial to control the ion content of the water added in step g. This can be done by measuring the conductivity or hardness of the water using established tests or measurement methods. Low conductivity and low ion concentration are preferred, which can be achieved, for example, by passing tap water through an ion exchange resin. The preferred conductivity of the water is less than 0.2 μS / cm.

[0101] The present invention further relates to coating formulations comprising at least one aqueous dispersion according to the invention.

[0102] The present invention also relates to the use of the aqueous dispersions according to the invention in coating formulations.

[0103] The present invention furthermore relates to a process for coating substrates, wherein a coating formulation comprising the aqueous dispersion according to the invention is used.

[0104] The present invention further relates to the use of the coating formulations according to the invention for coating substrates.

[0105] The present invention also relates to substrates coated with the coating formulations according to the invention.

[0106] According to the present invention, the coating composition may be a painting composition or an ink composition.

[0107] In addition to the aqueous polyurethane dispersion, another resin may be added to the coating composition of the present invention.

[0108] The example of another resin comprises polyester resin, acrylic resin, polyether resin, polycarbonate resin, polyurethane resin, epoxy resin, alkyd resin, polyolefin resin, vinyl chloride resin etc.These can be used alone or in combination of two or more.From the angle of dispersibility in water, another resin preferably has one or more types of hydrophilic groups.Hydrophilic groups comprise hydroxyl, carboxyl, sulfo group, polyethylene glycol group etc.

[0109] Polyester resin can be generally produced by esterification or transesterification between an acid component and an alcohol component. As the acid component, a compound generally used as an acid component to produce polyester resin can be used. For example, aliphatic polybasic acid, alicyclic polybasic acid, aromatic polybasic acid etc. can be used as the acid component.

[0110] The acrylic resin is preferably, for example, a hydroxyl-containing acrylic resin. The hydroxyl-containing acrylic resin can be produced by a known method, such as a solution polymerization method in an organic solvent or an emulsion polymerization method in water, wherein a hydroxyl-containing polymerizable unsaturated monomer is copolymerized with another polymerizable unsaturated monomer copolymerizable with the hydroxyl-containing polymerizable unsaturated monomer.

[0111] The hydroxyl-containing polymerizable unsaturated monomer is a compound having one or more hydroxyl groups and one or more polymerizable unsaturated bonds in one molecule. Examples include: monoesterification products of (meth)acrylic acid and diols having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; caprolactone-modified products of these monoesterification products; N-hydroxymethyl (meth)acrylamide; allyl alcohol; (meth)acrylic acid having a polyoxyethylene chain containing a hydroxyl group at the molecular end; and the like.

[0112] The hydroxyl-containing acrylic resin preferably has an anionic functional group. The hydroxyl-containing acrylic resin having an anionic functional group can be produced by, for example, using a polymerizable unsaturated monomer having an anionic functional group such as a carboxylic acid group, a sulfonic acid group or a phosphoric acid group as one type of polymerizable unsaturated monomer.

[0113] Examples of the polyether resin include polymers or copolymers having an ether bond, such as polyoxyethylene polyether, polyoxypropylene polyether, polyoxybutylene polyether, polyethers derived from aromatic polyhydroxy compounds including bisphenol A, bisphenol F, and the like, and the like.

[0114] Examples of polycarbonate resins include polymers made from bisphenol A, 3-methyl-1,5-pentanediol, and 1,6-hexanediol.

[0115] Examples of the epoxy resin include resins obtained by reacting a bisphenol compound with epichlorohydrin, etc. Examples of the bisphenol include bisphenol A and bisphenol F.

[0116] Examples of the alkyd resin include, for example, alkyd resins obtained by reacting a polyacid such as phthalic acid, terephthalic acid or succinic acid and a polyol, and further reacting with a modifier such as fats and oils / fatty and oleic acid (e.g., soybean oil, linseed oil, palm oil, stearic acid, etc.) or a natural resin (e.g., rosin, amber, etc.).

[0117] Examples of the polyolefin resin include a polyolefin resin obtained by polymerizing or copolymerizing an olefin-based monomer with another monomer according to a normal polymerization method, optionally subjected to water dispersion using an emulsifier, or a resin obtained by emulsion polymerization of an olefin-based monomer with another monomer, as appropriate. In addition, in some cases, a so-called chlorinated polyolefin-modified resin obtained by chlorinating a polyolefin resin may be used.

[0118] Examples of olefin-based monomers include olefins such as ethylene, propylene, 1-butene, 3-methyl-1-butene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-hexene, 1-decene, and 1-dodecene; and conjugated dienes and non-conjugated dienes such as butadiene, ethylidene norbornene, dicyclopentadiene, 1,5-hexadiene, and styrene. These monomers can be used alone or in combination of two or more. Examples of other monomers copolymerizable with olefin-based monomers include vinyl acetate, vinyl alcohol, maleic acid, citraconic acid, itaconic acid, maleic anhydride, citraconic anhydride, and itaconic anhydride.

[0119] These monomers may be used alone or in combination of two or more.

[0120] The coating composition according to the present invention may further include a curing agent. By including the curing agent, it is possible to improve the durability of a painting film, a multilayer coating film, a coating film, or a printed matter obtained using the coating composition.

[0121] For example, polyisocyanate, blocked polyisocyanate, melamine resin, carbodiimide, oxazoline, aziridine, hydrazine, etc. can be used as the curing agent. These curing agents can be used alone or in combination of two or more.

[0122] The polyisocyanate is not particularly limited as long as the polyisocyanate has two or more isocyanate groups in the molecule, and examples thereof include the same ones as exemplified as the polyisocyanate compound (a).

[0123] The blocked polyisocyanate is not particularly limited as long as the blocked polyisocyanate has two or more blocked isocyanate groups in the molecule, and examples thereof include polyisocyanate compounds or compounds obtained by providing hydrophilicity to a polyisocyanate compound blocked by a known blocking agent such as phenol, secondary or tertiary alcohol, oxime, aliphatic or aromatic secondary amine, phthalimide, lactam, active methylene compound (e.g., dialkyl malonate, etc.), pyrazolyl compound (e.g., pyrazole, 3,5-dimethylpyrazole, etc.), acidic sodium sulfite, etc.

[0124] The melamine resin is not particularly limited, and those generally used as curing agents can be used. For example, the melamine resin is preferably an alkyl etherified melamine resin obtained by alkyl etherification, more preferably a melamine resin substituted with a methoxy group and / or a butoxy group. Such melamine resins include: those having only methoxy groups, such as Cymel 325, Cymel 327, Cymel 370, and My Coat 723; those having methoxy and butoxy groups, such as Cymel 202, Cymel 204, Cymel 211, Cymel 232, Cymel 235, Cymel 236, Cymel 238, Cymel 251, Cymel 254, Cymel 266, Cymel 267, and Cymel 285 (all of which are trade names, manufactured by Nippon Cytec Industries, Ltd.); and those having only butoxy groups, such as My Coat 506 (trade name, manufactured by Mitsui-Cytec Ltd.), U-VAN20N60, and U-VAN 20SE (all of which are trade names, manufactured by Mitsui Chemicals, Inc.). These can be used alone or in combination of two or more. Among them, Cymel 211, Cymel 251, Cymel 285, Cymel 325, Cymel 327 and My Coat 723 are more preferred.

[0125] Carbodiimide is not particularly limited as long as it is a compound having two or more carbodiimide groups in the molecule. For example, aliphatic polycarbodiimides [poly(hexamethylenecarbodiimide) etc.], alicyclic polycarbodiimides [poly(4,4'-dicyclohexylmethanecarbodiimide) etc.], and aromatic polycarbodiimides [poly(p-phenylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(diisopropylphenylcarbodiimide) etc.] obtained by polymerizing aromatic polyisocyanates having 8 to 26 carbon atoms, aliphatic polyisocyanates having 4 to 22 carbon atoms, alicyclic polyisocyanates having 8 to 18 carbon atoms, or aromatic aliphatic polyisocyanates having 10 to 18 carbon atoms can be used. For example, commercially available products include "Carbodilite V-01", "Carbodilite V-02", "Carbodilite V-03", "Carbodilite V-04", "Carbodilite V-05", "Carbodilite V-07", "Carbodilite V-09", "Carbodilite E-02", "Carbodilite E-03A", and "Carbodilite E-04", each manufactured by Nisshinbo Chemical Inc.

[0126] Oxazoline is not particularly limited as long as it is a compound having two or more oxazoline groups (oxazoline skeleton) in the molecule. Examples thereof include compounds having two or more oxazoline groups, such as 2,2'-isopropylidenebis(4-phenyl-2-oxazoline); polymerizable oxazoline compounds, such as (co)polymers of 2-isopropenyl-2-oxazoline, 2-vinyl-2-oxazoline, and 2-vinyl-4-methyl-2-oxazoline; copolymers of polymerizable oxazoline compounds and copolymerizable monomers that do not react with oxazoline groups [(meth)acrylates, such as methyl (meth)acrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, and polyethylene glycol (meth)acrylate, (meth)acrylamide vinyl acetate, styrene, α-methylstyrene, sodium styrenesulfonate, etc.]; and the like. Examples of commercially available products include “Epocros K-2010E,” “Epocros K-2020E,” and “Epocros WS-500” manufactured by Nippon Shokubai Co., Ltd.

[0127] The aziridine is not particularly limited as long as it is a compound having two or more aziridine groups in the molecule. Examples thereof include tetramethylolmethane tris(aziridine propionate) and trimethylolpropane tris(aziridine propionate).

[0128] Hydrazine includes hydrazine and compounds having two or more hydrazine groups (hydrazine skeleton) in the molecule [for example, dicarboxylic acid dihydrazides having 2 to 10 carbon atoms (oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, etc.) and alkylene dihydrazides having 2 to 10 carbon atoms (ethylene dihydrazide, 1,3-propylene dihydrazide, 1,4-butylene dihydrazide, 1,6-hexylene dihydrazide, etc.)].

[0129] Coloring pigments, extender pigments, and bright pigments can be added to the coating composition of the present invention. Examples of coloring pigments include titanium oxide, zinc white, carbon black, yellow iron oxide, red iron oxide, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, selenium-based pigments, perylene pigments, and the like.

[0130] Examples of extender pigments include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and aluminum oxide white. Barium sulfate and / or talc are preferably used as extender pigments, and barium sulfate is more preferably used. These can be used alone or in combination of two or more.

[0131] For example, aluminum, copper, zinc, brass, nickel, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, or mica coated with titanium oxide or iron oxide can be used as the bright pigment.

[0132] The coating composition of the present invention may contain common additives such as thickeners, curing catalysts, ultraviolet absorbers, light stabilizers, defoamers, plasticizers, surface conditioners and anti-settling agents, depending on their functions or uses. These may be used alone or in combination of two or more, or commercially available products may be used as they are.

[0133] The method for producing the coating composition of the present invention is not particularly limited and known production methods can be adopted. However, the coating composition is suitably prepared by mixing an aqueous polyurethane dispersion with the various resins and additives mentioned above, further adding an aqueous medium and adjusting the viscosity for the application method.

[0134] The present invention therefore also relates to a process for producing the coating composition according to the invention by mixing the aqueous polyurethane dispersion according to the invention with suitable resins and additives, further adding an aqueous medium, and adjusting the viscosity.

[0135] Suitable substrates to which the coating composition according to the present invention can be applied include: metal materials commonly used for automobile bodies or parts, road materials, household building materials, etc., such as electrodeposition-coated steel sheets, phosphated steel sheets, galvanized steel sheets, cold-rolled steel sheets, aluminum sheets, stainless steel sheets, zinc phosphate-treated steel sheets, iron phosphate-treated steel sheets, etc., or plastic materials such as polyurethane, polycarbonate, polybutylene terephthalate, polyamide, polyphenylene oxide, acrylonitrile / butadiene / styrene copolymer (i.e., ABS resin), polypropylene, and unsaturated polyester (commonly abbreviated as SMC). However, the present invention is not limited thereto.

[0136] The substrate can be used as is or can be subjected to surface treatments such as degreasing or primer coating and / or intermediate coating. These treatments can be carried out individually or in combination of two or more.

[0137] In order to repair a multi-layer coating film previously applied to the material using the coating composition according to the present invention, it is preferred that the portion of the coating film to be repaired is first subjected to solvent cleaning or sanding treatment and then painted.

[0138] The coating composition according to the present invention can be adjusted before use to have a specific viscosity suitable for conventional coating methods such as air spraying, airless spraying or electrostatic coating or for obtaining a desired film thickness. For example, for coating plastic materials, the aqueous coating composition is preferably adjusted before use by adding deionized water and, if necessary, additives such as thickeners and defoamers to have a solid content of about 10 to 40% by weight and a viscosity of about 800 to 5.000 m·Pas (measured using a B-type viscometer).

[0139] The above-mentioned suitable substrates can be coated with a single coat of the coating composition according to the invention, but an intermediate coating material can be applied over the applied coating of the coating composition according to the invention by the so-called wet-on-wet process or by a wet-on-wet process after preheating.

[0140] Meanwhile, after applying the coating material of the coating composition according to the present invention on the electrodeposited film, top coating can be performed by a wet-on-wet method or a wet-on-wet method after preheating. Preheating is a method of heating at 40 to 80° C. for 5 to 60 minutes, for example, at 80° C. for 5 minutes, and is performed by hot air heating, infrared irradiation, etc.

[0141] The dry film thickness of the coating composition used for coating may vary depending on the coating method and necessity, but may generally be approximately 10 to 50 μm.

[0142] The applied coating composition is then completely or partially dried by standing at room temperature, air drying, forced drying using hot air drying or infrared heaters, or in some cases, completely or partially cured by baking at a temperature of not more than 120°C to obtain a water-based coating film. In particular, to form a water-based coating film on a plastic material according to the present invention, it is preferred to obtain the water-based film by drying the film at a temperature of 40 to 120°C to a water content of not more than approximately 25% by weight after coating using air drying or hot air drying. Alternatively, to repair a multilayer coating film, it is preferred to obtain the water-based film by drying the film after coating using air blowing or hot air at a temperature of not more than 80°C.

[0143] Since the aqueous polyurethane dispersion according to the present invention has good flowability even when the composition has a high solid content, the coating material using the composition has a good finished appearance.

[0144] In addition, the coating film using the composition has good adhesion to the substrate, especially good adhesion to the electrodeposition coating film, and also provides excellent impact resistance even in single coating (monocoat) system and multi-layer coating system. The aqueous polyurethane dispersion according to the present invention is suitable as a raw material for aqueous coatings for coating electrodeposition films.

[0145] A particular advantage of the polyurethane dispersions according to the invention is the improved wet color matching, so that if, for example, a car body or component has to be repaired, a considerable amount of time can be saved, since if the premixed color is the color of the car, the coating does not need to be allowed to dry before evaluation. Example:

[0146] Raw materials and reagents

[0147] Polycarbonate polyester diol C 1200: polycarbonate polycaprolactone copolymer polyol, polycarbonate content 55% by weight, number average molecular weight = 2000 g / mol, commercially available from Covestro AG, Germany.

[0148] Polycarbonate polyester diol C 2202: polycarbonate diol, polycarbonate content 100% by weight, number average molecular weight = 2000 g / mol, commercially available from Covestro AG, Germany.

[0149] Polyester I: a polyester diol comprising 1,6-hexanediol, neopentyl glycol and adipic acid, with an OH value of 66 and a number average molecular weight of 1700 g / mol, available from Covestro AG, Germany.

[0150] Polyether LB 25: monohydroxy-functional polyether, number average molecular weight 2250 g / mol, commercially available from Covestro AG, Germany.

[0151] H: 1,6-hexamethylene diisocyanate, commercially available from Covestro AG, Germany.

[0152] W: dicyclohexylmethane diisocyanate, available from Covestro AG, Germany.

[0153] I: isophorone diisocyanate, available from Covestro AG, Germany.

[0154] Synthesis of PUD

[0155] Example 1

[0156] 150g C 1200 was dehydrated at 110°C and 85 mbar (a) for 1 hour, and then further 27.5 g of neopentyl glycol, 19.9 g of 2,2-bis(hydroxymethyl)propionic acid, 0.9 g of butyl glycol and 2.7 g of trimethylolpropane were added. The mixture was dissolved in 240.4 g of acetone, and then 111.2 g of 1 and 48.5 grams The resulting mixture was stirred under reflux acetone until an isocyanate content of 2.3% by weight was reached. The mixture was then cooled to 40°C, and 13.2 g of 2-dimethylaminoethanol was added. The resulting mixture was added to 594 g of pre-weighed water with stirring. The water temperature was 23.6°C. A solution of 8.3 g of ethylenediamine in 80.4 g of water was added to the mixture over 5 minutes. The acetone was then removed by distillation. The resulting PUD had the following characteristics:

[0157] Solid content: 30.42 wt%

[0158] Average particle size: 33.2nm

[0159] D(i)90:52.7nm

[0160] Viscosity: 474 mPa·s

[0161] Example 2

[0162] 261 grams C 1200 was dehydrated at 110°C and 85 mbar (a) for 1 hour, and then a further 10.6 g of neopentyl glycol, 34.4 g of 2,2-bis(hydroxymethyl)propionic acid and 0.9 g of butyl glycol were added. This mixture was dissolved in 154 g of acetone, and then 107.6 g of 1 and 46.9 grams The resulting mixture was stirred under reflux of acetone until an isocyanate content of 2.3% by weight was reached. The mixture was then cooled to 40°C, and 24.8 g of diisopropylethylamine was added. The resulting mixture was added to 765 g of pre-weighed water with stirring. The water temperature was 9°C. To this mixture was added a solution of 2.0 g of DETA, 4.2 g of ethylenediamine, and 1.1 g of butylamine in 105.5 g of water over 5 minutes. The acetone was then removed by distillation. The resulting PUD had the following characteristics:

[0163] Solid content: 37.33% by weight

[0164] Average particle size: 44.0nm

[0165] D(i)90:88.3nm

[0166] Viscosity: 112 mPa·s

[0167] Comparative Example 3

[0168] 280g C 2202 and 16.0 g of polyether LB 25 were dehydrated at 110°C and 85 mbar (a) for 1 hour, and then 13.7 g of 2,2-bis(hydroxymethyl)propionic acid were further added. The mixture was cooled while stirring. 72.2 g of 1 and 17.2 grams The resulting mixture was stirred at 90 to 100°C until an isocyanate content of 3.0% by weight was reached. The mixture was then dissolved in 709 grams of acetone and cooled to 50°C to produce a reaction solution. 10.1 grams of triethylamine was added. A solution of 3.5 grams of hydrazine hydrate and 3.4 grams of ethylenediamine in 36 grams of water was added to the reaction solution. The resulting mixture was vigorously stirred for 10 minutes, and then 672 grams of water was added to disperse the mixture. The acetone was then removed by distillation. The resulting PUD had the following characteristics:

[0169] Solid content: 36.34 wt%

[0170] Average particle size: 52.5nm

[0171] D(i)90:77.0nm

[0172] Viscosity: 619 mPa·s

[0173] Comparative Example 4

[0174] 280g C 1200 and 29.2 g of polyether LB 25 were dehydrated at 110°C and 85 mbar (a) for 1 hour, and then 10.1 g of 2,2-bis(hydroxymethyl)propionic acid were further added. The mixture was cooled while stirring. 72.2 g of 1 and 17.2 grams The resulting mixture was stirred at 90 to 100°C until an isocyanate content of 3.5% by weight was reached. The mixture was then dissolved in 726 grams of acetone and cooled to 50°C to produce a reaction solution. 7.4 grams of triethylamine was added. A solution of 7.5 grams of ethylenediamine in 49.4 grams of water was added to the reaction solution. The resulting mixture was vigorously stirred for 10 minutes, and then 723 grams of water was added to disperse the mixture. The acetone was then removed by distillation. The resulting PUD had the following characteristics:

[0175] Solid content: 33.58% by weight

[0176] Average particle size: 51.4nm

[0177] D(i)90:83.7nm

[0178] Viscosity: 9738 mPa·s (using rotor S63, 30 rpm)

[0179] Comparative Example 5

[0180] 162.5 grams C 1200 and 138.1 g of polyester I were dehydrated at 110°C and 85 mbar (a) for 1 hour, and then 59.6 g of neopentyl glycol, 43.0 g of 2,2-bis(hydroxymethyl)propionic acid, 2.1 g of butyl glycol and 6.0 g of trimethylolpropane were further added. The mixture was dissolved in 505 g of acetone, and then 240.8 g of 1 and 105.0 g The resulting mixture was stirred under reflux of acetone until an isocyanate content of 2.4% by weight was reached. The mixture was then cooled to 40°C, and 28.6 g of 2-dimethylaminoethanol was added. The resulting mixture was added to 1275 g of pre-weighed water with stirring. The water temperature was 50°C. To this mixture was added a solution of 13.2 g of ethylenediamine and 3.5 g of butylamine in 161.7 g of water over 5 minutes. The acetone was then removed by distillation. The resulting PUD had the following characteristics:

[0181] Solid content: 35.46 wt%

[0182] Average particle size: 110.4nm

[0183] D(i)90:184nm

[0184] Viscosity: 65mPa·s

[0185] Comparative Example 6

[0186] 200 grams C 1200 and 21.6 g of polyether LB 25 were dehydrated at 110 ° C and 85 mbar (a) for 1 hour, and then 24.8 g of 2,2-bis (hydroxymethyl) propionic acid, 6.3 g of trimethylolpropane and 15.8 g of 1,4-butanediol were further added. The mixture was dissolved in 320 g of acetone, and then 211 g of The resulting mixture was stirred under reflux of acetone until an isocyanate content of 4.4% by weight was reached. 16.5 g of 2-dimethylaminoethanol was added. The resulting mixture was added to 733 g of pre-weighed water with stirring. The water temperature was 22.8°C. A solution of 18.9 g of ethylenediamine in 182.3 g of water was added to the reaction solution. The resulting mixture was stirred vigorously for 20 minutes, after which the acetone was removed by distillation. The resulting PUD had the following characteristics:

[0187] Solid content: 37.47% by weight

[0188] Average particle size: 73.9nm

[0189] D(i)90:122nm

[0190] Viscosity: 38 mPa·s

[0191] Comparative Example 7 (according to Example 3 of US2006 / 240264)

[0192] 152.1 grams W and 348.7 grams I was heated to 55°C and stirred. Then 62.2 g of dimethylolpropionic acid was added. After 5 minutes, 470.4 g of A solution of C 1200, 96.3 g of neopentyl glycol, 2.8 g of butyl glycol, and 377.5 g of acetone was prepared and the mixture was heated to 68°C. It was stirred at this temperature until an NCO content of 2.8% was reached. It was then cooled to 60°C. 46.9 g of triethylamine were added. 450 g of this solution were dispersed with vigorous stirring in 545.9 g of water introduced at 35°C. After dispersion, the mixture was stirred for 5 minutes. Subsequently, a solution of 2.0 g of diethylenetriamine, 1.1 g of n-butylamine, and 3.5 g of ethylenediamine in 60.7 g of water was added over the course of 10 minutes. After all of this had been added, the mixture was stirred at 40°C for 20 minutes, and the acetone was then removed by vacuum distillation at this temperature. The resulting PUD had the following characteristics:

[0193] Solid content: 36.47% by weight

[0194] Average particle size: 34.3nm

[0195] D(i)90:58.5nm

[0196] Viscosity: 74 mPa·s

[0197] Comparative Example 8 [According to Example 1 of US2018 / 0118971 (WO2016166096A1)]

[0198] 308 grams A mixture of C 1200, 25 g of dimethylolpropionic acid, 10 g of neopentyl glycol, 1 g of butyl glycol and 161 g of acetone was heated to 55°C and stirred. 41 g of W and 93 grams I, and the mixture was heated to 65°C. The mixture was stirred at this temperature until an NCO content of 1.8% was reached. Thereafter, the mixture was cooled to 60°C and 12 g of dimethylethanolamine was added. 648 g of this solution was dispersed in 812 g of water, which had been initially charged at 35°C, with vigorous stirring. After dispersion, stirring was continued for a further 5 minutes. Subsequently, over a period of 10 minutes, a solution of 3 g of diethylenetriamine, 2 g of ethylenediamine, and 1 g of butylamine in 73 g of water was added. After the addition was complete, the mixture was stirred at 40°C for 20 minutes, after which the acetone was removed by distillation under reduced pressure at this temperature. To complete the reaction of the isocyanate groups, the mixture was stirred at 40°C until no NCO was detected by infrared spectroscopy. After the mixture had cooled to <30°C, it was filtered through a 240 μm filter. The resulting PUD had the following characteristics:

[0199] Solid content: 35.38% by weight

[0200] Average particle size: 67.1nm

[0201] D(i)90:100nm

[0202] Viscosity: 16mPa·s

[0203] Test Method

[0204] Hydroxyl (OH) value: The hydroxyl (OH) value of a resin is the number of milligrams (mg) of potassium hydroxide equivalent to the hydroxyl groups in 1 gram of polyol. The hydroxyl value is measured using the indicator titration method according to Method B of JIS K 1557:2007.

[0205] Molecular weight: To measure the number average molecular weight and weight average molecular weight of a polyol or polyurethane, gel permeation chromatography was used. The polyol was weighed and dissolved in tetrahydrofuran at a concentration of 8 mg / mL. The aqueous polyurethane dispersion was coated on a polytetrafluoroethylene plate, and the coated plate was naturally dried at room temperature to obtain a dry film. An appropriate amount of the dry film was weighed and dissolved in tetrahydrofuran at a concentration of 8 mg / mL. The test was performed using an Agilent 1260 (column temperature = 35°C, injection volume = 60 μL, flow rate = 0.7 mL / min). The test results were obtained based on a polystyrene standard as a control, and fractions with a molecular weight of 100 or higher were selected for calculation.

[0206] Transmittance [%]: 3 ml of PUD was placed in a polystyrene cuvette. The transmittance of the sample was measured using a UV-2600 UV-VIS spectrophotometer (SHIMADZU, Japan) at 24 ± 1°C, wavelength range: 420 to 700 nm, scan speed: fast, scan mode: single, slit width: 5.0, accumulation time: 0.1 sec, detector unit: direct.

[0207] Average Particle Size and D(i)90 [nm]: One drop (approximately 0.05 g) of PUD was added to 50 mL of ultrapure water. The diluted sample was measured on a Malvern Zetasizer Nano ZS particle size analyzer at 23.0 ± 0.1°C. Materials: Polystyrene latex (RI: 1.590; Absorbance: 0.010), Dispersant: Water (Temperature: 23.0°C; Viscosity: 0.9308 cP; RI: 1.330), Equilibration Time: 60 sec, Cell Type: Disposable Cuvette DTS0012, Positioning Method: Auto-attenuation Selection, Find Best Position: Yes, Analysis Mode: General (Normal Resolution), Measurement Angle: 173° Backscatter (NIBS Default), Number of Runs: 3, Run Duration: 10 sec, Number of Measurements: 10.

[0208] Average particle size refers to the Z-average particle size used in dynamic light scattering as defined in ISO 13321:1996.

[0209] D(i)90 represents the point in the particle size distribution up to and including that point at which 90% of the total intensity of the material in the sample is "contained".

[0210] Viscosity [mPa·s]: 150 g of PUD was placed in a glass bottle and the viscosity of the sample was measured using a Brookfield DV-II+ Pro viscometer at room temperature (20 to 25° C.) using a spindle S62 (unless otherwise specified) at 30 rpm according to ISO 3219:1994.

[0211] Solids Content [wt%]: Approximately 1 gram of PUD was spread onto a glass fiber filter placed on an aluminum sample pan. Solids content was measured using a Metteler Teredo Halogen Moisture Analyzer Excellence HS153. Drying Procedure: Standard, Drying Temperature: 120°C, Shutoff Criterion: 5 (1 mg / 140 seconds) (Maintain heating of the sample at 120°C and weighing. If the weight loss within 140 seconds is less than 1 mg, stop the test and record the remaining weight percentage as the result).

[0212] Wet color matching: 13 grams of yellow iron oxide paste (available from Axalta Coating System) was thoroughly mixed into 87 grams of the corresponding PUD (performed with PUDs according to Example 1, Comparative Example 4, Comparative Example 6, and Comparative Example 7).

[0213] 13 grams of red iron oxide paste (available from Axalta Coating System) were thoroughly mixed into 87 grams of the corresponding PUD (this was done with the PUDs according to Example 2, Comparative Example 3, and Comparative Example 5).

[0214] The resulting formulation was then coated onto a glass plate using a wire-wound rod at a wet film thickness of 120 μm. The wet film was dried at room temperature for 24 hours. The color difference between the dried film and the freshly applied wet film was visually assessed, with possible ratings of excellent, fair, and poor. Smaller color differences indicate better wet color matching performance.

[0215] Odor evaluation of polyurethane dispersions was performed with the aid of an electronic nose as follows:

[0216] 1. Cut the aluminum foil into a 30cm*21cm rectangle;

[0217] 2. Use a 40μm film making machine to coat PUD on the matte surface of aluminum foil;

[0218] 3. Heat the aluminum foil coated with the PUD sample in an oven at 130°C for 3 minutes;

[0219] 4. Cut the dried sample into rectangles using a press cutter. Each test sample has a size of 10 cm*5 cm.

[0220] 5. Store the test sample in a sealed plastic bag for 24 hours;

[0221] 6. Place four samples (each 10 cm*5 cm) in a 1 L glass bottle that has been preheated at 80°C for 30 minutes;

[0222] 7. Heat the sealed glass bottle at 80°C for 2 hours;

[0223] 8. Remove the glass bottle and place it at room temperature for 2 minutes;

[0224] 9. The odor of the samples was tested using a Cosmos XP-329IIIR (New Cosmos Electric (Shanghai) Co., Ltd.) in "batch mode": the probe was inserted into the glass bottle immediately after opening the lid, and the value was measured and recorded;

[0225] 10. Higher values ​​indicate stronger odor of the test sample.

[0226] The experimental results are shown in Table 1.

[0227] Table 1

[0228]

[0229]

[0230] C contrast

[0231] It is clear that only Examples 1 and 2 according to the invention meet the requirements for wet color matching, low average particle size at acceptable solids content (>30%) and viscosity (<1000 mPas), and low odor emission. The comparative examples fail to meet the requirements for wet color matching or odor emission or both.

Claims

1. An aqueous dispersion comprising at least one polyurethane, wherein the at least one polyurethane is prepared from at least the following components: (A) at least one polyisocyanate, (B) at least one polymeric polyol having a number-average molecular weight of 400 to 6000 g / mol, wherein the at least one polycarbonate polyol is present in the polymeric polyol component (B) in an amount of 55 to 100% by weight, based on the total weight of component (B), (C) optionally, at least one monofunctional nonionic hydrophilizing agent, (D) at least one compound selected from monools, diols, polyols, aminopolyols, monoamines, diamines, polyamines and mixtures thereof, in each case having a number average molecular weight of less than 400 g / mol, (E) at least one compound selected from monools, diols, polyols, monoamines, diamines, polyamines and mixtures thereof, in each case having at least one salt group, preferably anionic group, or a functional group convertible into a salt group, preferably into anionic group, (F) at least a neutralizing agent selected from tertiary amine compounds having a boiling point above 100° C. at atmospheric pressure, inorganic bases, preferably potassium hydroxide, sodium hydroxide, and mixtures thereof, It is characterized by The at least one polyurethane dispersion has an average particle size D(i)90 of 20 nm to 95 nm and wherein the viscosity of the dispersion is 50 to 1500 mPa·s.

2. The dispersion according to claim 1, wherein the at least one polyisocyanate (A) is selected from the group consisting of hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI, isophorone diisocyanate), 4,4'-dicyclohexylmethane diisocyanate and mixtures thereof. 3 . The dispersion according to claim 1 , wherein the component (A) is a mixture of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI, isophorone diisocyanate) and 4,4′-dicyclohexylmethane diisocyanate.

4. The dispersion according to any one of claims 1 to 3, wherein the at least one polymeric polyol (B) is selected from the group consisting of polycarbonate polyols, polyester polyols, polyether polyols, polycarbonate polycaprolactone polyols and mixtures thereof. 5 . The dispersion according to claim 1 , wherein the viscosity of the dispersion is from 70 to 1500 mPa·s.

6. The dispersion according to any one of claims 1 to 5, wherein the solids content of the dispersion is from 20 to 60% by weight.

7. A method for preparing a polyurethane dispersion according to any one of claims 1 to 6, comprising at least the following steps: a. charging a reaction vessel with at least one polymeric polyol (B) and optionally a monofunctional nonionic hydrophilic agent (C), optionally removing the water contained in the pre-charged mixture to less than 0.2 wt %, preferably less than 0.1 wt %, by increasing the temperature and / or reducing the pressure and / or purging with nitrogen under stirring, b. loading a portion or all of the amount of component (D) and / or a portion or all of the amount of component (E) into the reaction vessel, c. reacting the precharged contents of the reaction vessel by metering in a mixture comprising at least one polyisocyanate (A), for example at a temperature of 60 to 135° C., and reacting the mixture at a temperature of 60 to 135° C. to obtain a prepolymer, d. before or after step c, adding a solvent miscible with water but inert to isocyanate groups to dissolve the prepolymer from step c, e. reacting the prepolymer with the portion of component (D) and component (E) not yet added in step b, for example at a temperature of 30 to 60° C. to obtain a polyurethane or polyurethane-urea, f. before or after step d or e, adding at least one neutralizing agent, and g. before, during or after step e, adding water to obtain an aqueous polyurethane-urea dispersion, h. Removal of the solvent, preferably by distillation.

8. Coating formulation comprising at least one aqueous dispersion according to any one of claims 1 to 6.

9. A process for producing a coating formulation according to claim 8 by mixing the aqueous polyurethane dispersion according to any one of claims 1 to 6 with suitable resins and additives, further adding an aqueous medium and adjusting the viscosity.

10. Use of the aqueous dispersion according to any one of claims 1 to 6 in coating formulations.

11. Process for coating substrates, wherein a coating formulation comprising the aqueous dispersion according to any one of claims 1 to 6 is used.

12. Use of the coating formulation according to claim 8 for coating a substrate.

13. A substrate coated with the coating formulation according to claim 8.

Images