WO2011061206A1

WO2011061206A1 - Light-stable anionic polyurethane polyureas

Info

Publication number: WO2011061206A1
Application number: PCT/EP2010/067631
Authority: WO
Inventors: Rolf Gertzmann; Henricus Peerlings
Original assignee: Bayer Materialscience Ag
Priority date: 2009-11-19
Filing date: 2010-11-17
Publication date: 2011-05-26

Abstract

The present invention relates to new recyclable peelable coatings based on cosolvent-free water-based light-stable anionic polyurethane polyureas, methods for the manufacture thereof and the use thereof as a coating, preferably as a peelable coating for temporarily protecting motor vehicles, aeroplanes, steel and aluminium profiles, panes of glass and plastics and any other substrates, and methods for the re-use of the used peeled-off coating films.

Description

Light-stable anionic polyurethane polyureas

The present invention relates to new peelable coatings based on cosolvent-free water-based light-stable anionic polyurethane polyureas, methods for the manufacture thereof and the use thereof as a coating, preferably as a peelable coating for temporarily protecting motor vehicles, aeroplanes, steel and aluminium profiles, panes of glass and plastics and any other substrates, and methods for the re-use of the used peeled-off coating films.

Anionic polyurethane polyurea dispersions are in principle known. Cosolvent-free water-based anionic polyurethane dispersions, methods for the manufacture thereof and the use thereof as coatings, coating compounds, adhesives and peelable coatings are also known from the prior art. An assessment of the relevant prior art is given in this regard in DE-A 19 653 585.

DE-A 19 653 585 describes polyurea dispersions which after physical drying at 20 to 100°C [...] transparent high-gloss UV-resistant heat-resistant (-30 to 80°C) coatings which are resistant to precipitation (of an organic or inorganic nature) and on the one hand adhere well and on the other can easily be removed by peeling. The tear resistance and elongation behaviour of the coating films are reasonably high, as described for example in DE- A 19 653 585.

WO 98/23692 describes mixtures of polyolefins which are used as peelable coatings for motor cars. These mixtures do not contain any PU components, however. Nor are the peelable coatings described here recyclable. DE-A 10311420 describes polyether-based peelable coatings which do not, however, have the required light stability.

EP-B 1 072652 and EP-A 1132413 describe complex methods for the manufacture of polyurethane dispersions, in which a mixture of two polyurethane dispersions having different glass transition temperatures or an additional grafting of acrylic monomers is carried out on the polyurethane dispersion.

EP-A 1338634 and DE-A 10311420 describe in principle the fact that a mixture of hyrophilising agents that contain both carboxylate groups and sulfonate groups can be used. The users of coatings of this kind now seek coating compounds which, after they have been used in coatings, in addition to the conventional advantageous properties such as light stability and acid resistance display better water resistance and peelability.

It was therefore an object of the present invention to provide new peelable coatings based on cosolvent-free water-based light-stable anionic polyurethane polyureas which display improved peelability and water resistance. It was therefore also an object of the present invention to provide new peelable coatings based on cosolvent-free water-based light-stable anionic polyurethane polyureas which display improved peelability and water resistance without impairing other advantageous properties such as a high level of light stability, high transparency, high heat resistance and high resistance to precipitation (of an organic or inorganic nature).

It has now been found, surprisingly, that the desired application-engineering properties are obtained if there is used as the hydrophilising agent a mixture of substances containing carboxyl groups and sulfonyl groups in a certain ratio and a certain quantity in relation to all the components of the polyurethane polymer.

The invention therefore relates to new peelable coatings based on containing a water-based anionic polyurethane polyurea which contains a mixture of substances containing carboxyl groups and sulfonyl groups. The invention further relates to light-stable coatings which are manufactured therefrom, in which these coatings may be applied to any substrates and dried at temperatures of up to 150°C.

Suitable dispersions for the light-stable coating compounds according to the invention, which are based on low-cosolvent or cosolvent-free water-based anionic dispersions of polyurethane polyureas whereof the solids contain the reaction product at least partly in salt form, comprising a) at least one NCO prepolymer, including i) 20 to 60 wt.% of at least one diisocyanate, ii) 20-80 wt.%) of at least one macrodiol having a number average molecular weight of from 500 to 10 000, iii) 2 to 12 wt.%) of at least one 2,2-bis-(hydroxymethyl)-alkane-monocarboxylic acid, iv) 0 to 15 wt.%) of at least one short-chain diol having a number average molecular weight of from 62 to 400, v) 0 to 10 wt.%) of at least one monofunctional alcohol having a number average molecular weight of from 32 to 350, bl) 0,5 t o 1 0 w t . % o f a t l e a s t o n e N-(2-aminoalkyl)-2- aminoalkylsulfonic acid, b2) 0 to 15 wt.%) of at least one diamine having a molecular weight of from 60 to 300, c) 0 to 10 wt.%) of at least one monofunctional amine, d) 0 to 3 wt.% of water, and e) 0 to 10 wt.%) of at least one neutralising agent, in which, in prepolymer stage a), the NCO content is adjusted to from 65 to 85 of the calculated NCO content, the sum of aiii) and bl) lies in the range of from 3 to 15 wt.%, and the ratio of aiii) to b 1 ) lies in the range of from 6:1 to 1 :1.

Preferably, in prepolymer stage a), the NCO content is adjusted to from 75 to 80% of the calculated NCO content. Preferably, the sum of aiii) and bl) lies in the range of from 3 to 10 wt.%, particularly preferably in the range of from 3 to 8 wt.%.

Preferably, the ratio of aiii) to b 1 ) lies in the range of from 5:1 to 1 :1.

Preferably, the acid value of the prepolymer lies in the range of from 5 to 20 mg KOH/g, particularly preferably in the range of from 8 to 18 mg KOH/g.

The polyurethane dispersions used according to the invention are low in cosolvents. The polyurethane dispersions used according to the invention preferably contain 0.0 to 0.9 wt.%>, particularly preferably 0.0 to 0.5 wt.%>, most particularly preferably 0.0 to 0.4 wt.%>, of cosolvents in relation to the total polyurethane dispersion.

The polymer mixtures according to the invention are low in cosolvents. The polyurethane dispersions used according to the invention preferably contain 0.0 to 0.9 wt.%>, particularly preferably 0.0 to 0.5 wt.%>, most particularly preferably 0.0 to 0.4 wt.%>, of cosolvents in relation to the total polyurethane dispersion.

In the context of the present invention, cosolvents are polar organic solvents. Preferably, cosolvents are organic solvents having a Hansen parameter in the range of from 7.2 to 16.0 (cal/cm³)⁰'⁵, as published in "Polymer Handbooks", Eds. Brandrup, J.; Immergut, E.H.; Grulke, E.A., 4th Edition, John Wiley, New York, 1999, VH/pages 675-711.

In the context of the present invention, preferred cosolvents are polar organic solvents selected from the group comprising acetone, methyl ethyl ketone, butyl diglycol, dimethyl sulfoxide, n- ethyl pyrrolidone, dimethyl formamide, dimethyl acetamide and dipropylene glycol dimethyl ether.

The coating compound according to the invention preferably has a solids content in the range of from 20 - 60 wt.%>, particularly preferably in the range of from 30 - 40 wt.%>, in water determined according to DIN EN ISO 3251. As component a)i) there are preferably used aliphatic and/or cycloaliphatic diisocyanates such as diisocyanates selected from the group comprising isophorone diisocyanate (IPDI), 4,4'- dicyclohexylmethane diisocyanate, l-methyl-2,4-diisocyanato-cyclohexane, l-methyl-2,6- diisocyanato-cyclohexane, 1 ,6-hexamethylene diisocyanate and 1,3-cyclohexane diisocyanate.

The concurrent use of small proportions of aromatic diisocyanates such as 2,4- and 2,6- toluene diisocyanate or 2,4'- and 4,4'-diphenylmethane diisocyanate is also possible.

As component a)ii) there are preferably used macrodiols having a molecular weight of from 500 to 10 000. These are preferably polyester diols, which are obtained by reacting dicarboxylic acids or their anhydrides with diols, optionally with the aid of conventional esterification catalysts, preferably by the principle of melt or azeotropic condensation at temperatures of from 140 - 240°C.

Examples of suitable dicarboxylic acids or their anhydrides are adipic acid, succinic acid (anhydride), maleic acid (anhydride), sebacic acid, azelaic acids, dimer fatty acids (in hydrogenated and unhydrogenated form), phthalic acid (anhydride), isophthalic acid, tetrahydrophthalic acid (anhydride), 1 ,4-cyclohexane dicarboxylic acid and hexahydrophthalic acid (anhydride). Diols which may be used are the industrially available diols such as ethylene glycol, 1,2- and 1 ,3-propanediol, 1,3- and 1 ,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol or mixtures of such diols. Preferable as component a)ii) are polyester diols of adipic acid, hexanediol and neopentyl glycol.

Also suitable as component a)ii) are polycarbonate diols, polycaprolactone diols, hydroxypolytetrahydrofurans or hydroxypolyethers based on propylene oxide. Suitable polycarbonate diols are obtained for example by reacting carbonic acid derivatives such as diphenyl carbonate or phosgene with alcohols, preferably diols of the type mentioned above.

The average molar mass of the polyols of component a)ii) lies between 500 and 10 000, preferably between 700 and 4 000, and macrodiols having a molar mass of between 1 000 and 2 500 are particularly preferred. The starting components a)iii) are preferably 2,2-bis-(hydroxymethyl)-alkane-monocarboxylic acids having a total of 5 - 8 carbon atoms, that is to say compounds of the general formula (I),

in which

R represents an alkyl radical having 1 - 4 carbon atoms. Preferably, R represents an unsubstituted alkyl radical having 1 - 4 carbon atoms.

Most particularly preferably, the component a)iii) is 2,2-dimethylolpropionic acid.

Possible as the starting component a)iv) are short-chain diols having a molecular weight in the range of from 62 - 400. Particularly preferred as the component a)iv) is 1 ,4-butanediol.

Possible as the starting component a)v) are alcohols having a molecular weight in the range of from 32 to 350. Preferably, alcohols selected from the group comprising methanol, ethanol, butanol, hexanol, 2-ethylhexanol, octanol and dodecanol are used.

Possible as the component bl) are compounds of the general formula (II)

H₂N-R¹-NH-R2-S0₃R³ (II), in which R¹ and R² independently of one another represent a Ci to C6-alkanediyl group, preferably ethylene, and R³ represents H or alkali, preferably Na.

As the component b2) it is possible to use any aliphatic and/or cycloaliphatic compounds which have at least two amino groups that are reactive with isocyanates and have a molecular weight in the range of from 60 to 300. Possible for this are in particular ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, p-xylylenediamine, 4,4'-di- amino-dicyclohexylmethane and 4,4'-diamino-3,3'-dimethyldicyclohexylmethane.

Possible as the component c) there are, as well as ammonia and alkanolamines, also monofunctional amines such as primary amines from the group comprising methylamine, ethylamine, n-propylamine, n-butylamine, n-octylamine, laurylamine, stearylamine, isopropylamine and cyclohexylamine, as well as secondary amines such as dimethylamine, diethylamine, diisopropylamine, dibutylamine and piperidine. Particularly preferred are secondary amines such as dibutylamine. It goes without saying that mixtures of these may be used.

Suitable as the neutralising agent e) are for example ammonia, N-methylmorpholine, dimethylisopropanolamine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, diethanolamine, triisopropanolamine, n-ethyl-diisopropylamine and mixtures thereof.

Light-stable coating compounds including a) at least one NCO prepolymer, including i) 20 to 60 wt.% of at least one diisocyanate, ii) 20-80 wt.% of at least one macrodiol having a molecular weight of from 500 to 10 000, iii) 2 to 12 wt.% of dimethylolpropionic acid, iv) 0 to 15 wt.%) of at least one short-chain diol having a molecular weight of from 62 to 400, v) 0 to 10 wt.%) of at least one monofunctional alcohol having a molecular weight of from 32 to 350, bl) 0,5 to 10 wt.% of the sodium salt of N-(2-aminoethane)-2-aminoethanesulfonic acid, b2) 0 to 15 wt.% of at least one diamine having a molecular weight of from 60 to 300, c) 0 to 10 wt.%) of at least one monofunctional amine, d) 0 to 3 wt.%) of water, and e) 0 to 10 wt.%) of at least one neutralising agent, in which, in prepolymer stage a), the NCO content is adjusted to from 65 to 85 of the calculated NCO content, the sum of aiii) and bl) lies in the range of from 3 to 15 wt.%, and the ratio of aiii) to bl) lies in the range of from 6:1 to 1 :1, are preferred.

The present invention further relates to a method for manufacturing water-based polyurethane dispersions. In a preferred embodiment, the components a)i), ii) and iii) are placed in a reactor and reacted in anhydrous conditions in a temperature range of from 50 - 150°C, preferably 50 - 110°C, and the batch is then cooled and has added to it industrially conventional acetone and optionally the short-chain diol (iv) and optionally monofunctional alcohols (v), and the mixture is heated until the NCO content thereof has fallen to a value of from 65 to 85% of the calculated NCO content. In this way, the NCO prepolymer is obtained. Then the batch is diluted with further acetone and the calculated quantity of a mixture of diamine and chain terminator (components bl), b2) and c)) is added, dissolved in water. In this way, 90%> of the NCO groups are reacted with the chain extender, the diamine and the chain terminator. The remaining isocyanate is reacted with the water that is present to give the polyurethane polyurea according to the invention.

The reaction that creates the polymer structure is preferably carried out without the use of catalysts, but it also possible to use catalysts that are known in isocyanate chemistry (for example tertiary amines such as triethylamine, tin compounds such as tin(II) octoate, dibutyl tin dilaurate and similar commonly available catalysts). When no more NCO can be detected, for example by an appropriate check using IR, the calculated quantity of neutralising agent, preferably ammonia solution, is added to the batch such that 50 - 100% of the carboxyl groups present are neutralised by the neutralising agent, or ammonia.

By adding water and then removing the acetone that was used by distillation, the desired concentration of solids is adjusted. Polyurethane polyurea dispersions which are obtained by the method according to the invention preferably have a solids content in the range of from 20 - 60 wt.%, particularly preferably in the range of from 30 - 40 wt.%, in water determined according to DIN EN ISO 3251.

The polyurethane dispersion includes particles having an average particle diameter in the range of from 20 - 1 000 nm, particularly preferably in the range of from 50 - 500 nm, as measured by the method of dynamic light scattering according to ISO 13320-1.

The pH values of the polyurethane polyurea dispersions used according to the invention, which are white and stable on storage, lie within the range of from 6 - 9.

The dispersion can be blended with other anionic or non-ionic dispersions such as polyvinyl acetate, polyethylene, polystyrene, polybutadiene, polyvinylchloride, polyacrylate and copolymer plastics dispersions.

Any desired adjustment of the pH value of the mixtures may be made using organic or inorganic bases, such as ammonia, alkali carbonates, amines or aminoalcohols, in which organic bases are preferred. Most particularly preferred is 2-amino-2-methyl-l-propanol.

The invention further also relates to the use of the polyurethane polyurea in coating compounds in order to manufacture high-gloss, light-stable, weathering-resistant, solvent- free coatings and finishes. These coatings and finishes serve to protect motor vehicles, steel, aluminium and metal articles of all kinds, glass and plastics articles of all kinds, mineral substrates, masonry or natural stone, and to prevent corrosion in ships, bridges, aeroplanes or railways, and to protect articles of wood and natural materials and any other substrates. The coating compounds are applied by dipping, knife coating, pouring, brush application or spraying and are then dried at 120 to 150°C.

The invention further also relates to the use of the polyurethane polyurea in coating compounds in order to manufacture recyclable peelable coatings. These peelable coatings serve to temporarily protect motor vehicles, railways, ships, furniture, metal articles, mineral articles, glass and plastics articles and any other substrates. For this purpose, the coating compounds are applied by dipping, knife coating, pouring, spraying or brush application and are then dried at 20 to 100°C, preferably 20 to 80°C, by heat or infrared light, microwave irradiation or ultrasonic treatment.

The finishes according to the invention are coatings which are water-resistant, transparent, tear-resistant, UV-resistant, heat-resistant, resistant to precipitation (of an organic or inorganic nature) and optionally pigmented and which on the one hand adhere well to the substrates and on the other can easily be removed by peeling.

When the coatings are formulated, the aids which are conventional in coatings chemistry, such as pigments, light stabilisers, anti-sedimentation agents, thickeners, surface-active compounds, defoaming agents, etc. can be used.

The coatings are applied by the conventional methods of coating technology, by dipping, knife coating, pouring, spraying, brush application or roller application. They serve as a peelable coating for temporarily protecting motor vehicles, steel and aluminium profiles, or panes or articles of glass and plastics. After application the coated parts are dried at room temperature or at an elevated temperature of up to 100°C.

The polyurethane polyurea dispersions according to the invention are dried for 30 minutes at 140-150°C, such that finishes which adhere well to the substrates are produced. It goes without saying that drying temperatures above 150°C are also possible, but the use of such high temperatures is generally uneconomic. Examples

The solids content was determined according to DIN EN ISO 3251 (thick- layer method: lid, 1 g sample, 1 h 125°C, convection oven). The OH number was determined according to DIN

53240 (mg KOH/g sample, acetylation, hydrolysis, titration with 0.1 mol/1 NaOH). The pH was measured according to international standard ISO 976.

The molecular weight (M_n, M_w) is determined by means of gel permeation chromatography (GPC). The samples were characterized in tetrahydrofuran eluent in accordance with DIN 55672- 1. M_n (UV)=number-average molar weight (GPC, UV detection), result in g/mol M_w

(UV)=mass-average molar weight (GPC, UV detection), result in g/mol

The particle size was measured by the method of dynamic light scattering according to ISO 13320-1.

Example 1 (not according to the invention):

170 g (0.1 mol) of a polyester comprising adipic acid, 1,6-hexanediol and neopentyl glycol having an average molecular weight of 1 700 g/mol and 2 % OH was dewatered for 30 minutes in a reaction vessel at 120°C and 10 mbar with stirring. 10.5 g (0.078 mol) of dimethylolpropionic acid and 111 g (0.5 mol) of isophorone diisocyanate were introduced under nitrogen. After a reaction time of 1 hour at 1 10°C, the batch was cooled to 60°C and dissolved in 100 g of acetone. 19.8 g (0.22 mol) of 1,4-butanediol was added and the batch was then stirred for another 22 hours at 50°C. The NCO content was 1.60% (calculated: 2.06%). The batch was diluted with 600 g of acetone. The following were added to the NCO prepolymer at 50°C: first 9.5 g (0.056 mol) of isophorone diamine, 2.22 g (0.017 mol) in 60 g of water, and then dibutylamine. Then the batch was stirred at 50°C for a further 5 hours. It was neutralised with 7.2 g (0.063 mol) of 15%> ammonia solution and dispersed using 463 g of water. The acetone was removed at 50°C and 150 mbar, and a white dispersion with a solids content of 38%> and an average particle size of 218 nm was obtained.

The degree of neutralisation was 81 %>, and the ratio of DMPA (dimethylolpropionic acid) to AAS (sodium salt of N-(2-aminoethane)-2-aminoethanesulfonic acid) = 100:0. The acid value of the prepolymer was 14 mg KOH/g and the total quantity of hydrophilising agent was 3.12 wt.% in relation to the quantity of solid resin.

Example 2 (not according to the invention):

170 g (0.1 mol) of a polyester comprising adipic acid, 1,6-hexanediol and neopentyl glycol having an average molecular weight of 1 700 g/mol and 2 % OH was dewatered for 30 minutes in a reaction vessel at 120°C and 10 mbar with stirring. 1 1 1 g (0.5 mol) of isophorone diisocyanate was introduced under nitrogen. After a reaction time of 1 hour at 110°C, the batch was cooled to 60°C and dissolved in 100 g of acetone. 23 g (0.26 mol) of 1,4-butanediol was added and the batch was stirred for another 22 hours at 50°C. The NCO content was 2.38% (calculated: 2.95%). The batch was diluted with 600 g of acetone. The following were added to the NCO prepolymer at 50°C : first 2.5 g (0.01 9 mol) of dibutylamine, then an aqueous mixture comprising 10.6 g (0.062 mol) of isophorone diamine and 18.4 g of a 45 wt.% solution of AAS in 1 16 g of water. Then the batch was stirred at 50°C for a further 5 hours. It was dispersed using 405 g of water. The acetone was removed at 50°C and 150 mbar, and a white dispersion with a solids content of 33.5% and an average particle size of 149 nm and a pH value (10% solids) of 6.93 was obtained. The degree of neutralisation was 0%, and the ratio of DMPA to AAS = 0: 100. The acid value of the prepolymer was 0 mg KOH/g and the total quantity of hydrophilising agent was 2.55 wt.%) in relation to the quantity of solid resin.

Example 3:

170 g (0.1 mol) of a polyester comprising adipic acid, 1 ,6-hexanediol and neopentyl glycol having an average molecular weight of 1 700 g/mol and 2 % OH was dewatered for 30 minutes in a reaction vessel at 120°C and 10 mbar with stirring. 7 g (0.052 mol) of dimethylolpropionic acid and 1 1 1 g (0.5 mol) of isophorone diisocyanate were introduced under nitrogen. After a reaction time of 1 hour at 110°C, the batch was cooled to 60°C and dissolved in 100 g of acetone. 19.8 g (0.22 mol) of 1,4-butanediol was added and the batch was stirred for another 22 hours at 50°C. The NCO content was 2.12% (calculated: 2.62%). The batch was diluted with 600 g of acetone. The following were added to the NCO prepolymer at 50°C: first 2.22 g (0.017 mol) of dibutylamine, then an aqueous solution comprising 9.5 g (0.056 mol) of isophorone diamine and 10.89 g of a 45 wt.% solution of AAS in 82 g of water. Then the batch was stirred at 50°C for a further 5 hours. It was dispersed using 442 g of water. The acetone was removed at 50°C and 150 mbar, and in this way a white dispersion with a solids content of 39.4%> and an average particle size of 164 nm and a pH value (10%> solids) of 6.80 was obtained.

The degree of neutralisation was 0%>, and the ratio of DMPA to AAS = 1.4:1. The acid value of the prepolymer was 9.5 mg KOH/g and the total quantity of hydrophilising agent was 3.65 wt.%) in relation to the quantity of solid resin.

Example 4:

170 g (0.1 mol) of a polyester comprising adipic acid, 1,6-hexanediol and neopentyl glycol having an average molecular weight of 1 700 g/mol and 2 %> OH was dewatered for 30 minutes in a reaction vessel at 120°C and 10 mbar with stirring. 1 1.9 g (0.089 mol) of dimethylolpropionic acid and 1 1 1 g (0.5 mol) of isophorone diisocyanate were introduced under nitrogen. After a reaction time of 1 hour at 1 10°C, the batch was cooled to 60°C and dissolved in 100 g of acetone. 19 g (0.21 mol) of 1 ,4-butanediol was added and the batch was stirred for another 22 hours at 50°C. The NCO content was 1.66% (calculated: 2.06%>). The batch was diluted with 600 g of acetone. The following were added to the NCO prepolymer at 50°C: first 2.22 g (0.017 mol) of dibutylamine, then an aqueous solution comprising 7.29 g (0.043 mol) of isophorone diamine and 5.45 g of a 45 wt.%> solution of AAS in 51 g of water. Then the batch was stirred at 50°C for a further 5 hours. It was neutralised using 2.13 g of a 15 wt.%) ammonia solution and then dispersed using 430 g of water. The acetone was removed at 50°C and 150 mbar, and in this way a white dispersion with a solids content of 40.5%> and an average particle size of 201 nm and a pH value (10%> solids) of 8.24 was obtained.

The degree of neutralisation was 10%>, and the ratio of DMPA to AAS = 4.8:1. The acid value of the prepolymer was 16 mg KOH/g and the total quantity of hydrophilising agent was 4.43 wt.%) in relation to the quantity of solid resin. Example 5:

170 g (0.1 mol) of a polyester comprising adipic acid, 1,6-hexanediol and neopentyl glycol having an average molecular weight of 1 700 g/mol and 2 % OH was dewatered for 30 minutes in a reaction vessel at 120°C and 10 mbar with stirring. 1 1.9 g (0.89 mol) of dimethylolpropionic acid and 1 1 1 g (0.5 mol) of isophorone diisocyanate were introduced under nitrogen. After a reaction time of 1 hour at 110°C, the batch was cooled to 60°C and dissolved in 100 g of acetone. 19 g (0.21 mol) of 1 ,4-butanediol was added and the batch was stirred for another 22 hours at 50°C. The NCO content was 1.65% (calculated: 2.06%). The batch was diluted with 600 g of acetone. The following were added to the NCO prepolymer at 50°C: first 2.22 g (0.017 mol) of dibutylamine, then an aqueous solution comprising 7.29 g (0.043 mol) of isophorone diamine and 5.45 g of a 45 wt.% solution of AAS in 51 g of water. Then the batch was stirred at 50°C for a further 5 hours. It was neutralised using 4.44 g of a 15 wt.%) ammonia solution and then dispersed using 430 g of water. The acetone was removed at 50°C and 150 mbar, and in this way a white dispersion with a solids content of 30.3% and an average particle size of 89 nm and a pH value (10%> solids) of 8.17 was obtained.

The degree of neutralisation was 20%, and the ratio of DMPA to AAS = 4.8:1. The acid value of the prepolymer was 16 mg KOH/g and the total quantity of hydrophilising agent was 4.42 wt.%) in relation to the quantity of solid resin.

Example 6:

170 g (0.1 mol) of a polyester comprising adipic acid, 1,6-hexanediol and neopentyl glycol having an average molecular weight of 1 700 g/mol and 2 % OH was dewatered for 30 minutes in a reaction vessel at 120°C and 10 mbar with stirring. 6.9 g (0.052 mol) of dimethylolpropionic acid and 1 1 1 g (0.5 mol) of isophorone diisocyanate were introduced under nitrogen. After a reaction time of 1 hour at 110°C, the batch was cooled to 60°C and dissolved in 100 g of acetone. 20 g (0.22 mol) of 1 ,4-butanediol was added and the batch was stirred for another 22 hours at 50°C. The NCO content was 2.11 % (calculated: 2.62%). The batch was diluted with 600 g of acetone. The following were added to the NCO prepolymer at 50°C: first 2.22 g (0.017 mol) of dibutylamine, then an aqueous solution comprising 11.73 g (0.069 mol) of isophorone diamine and 5.45 g of a 45 wt.% solution of AAS in 69 g of water. Then the batch was stirred at 50°C for a further 5 hours. It was neutralised using 3.56 g of a 15 wt.% ammonia solution and then dispersed using 460 g of water. The acetone was removed at 50°C and 150 mbar, and in this way a white dispersion with a solids content of 36.4% and an average particle size of 128 nm and a pH value (10% solids) of 8.7 was obtained.

The degree of neutralisation was 60%>, and the ratio of DMPA to AAS = 2.8:1. The acid value of the prepolymer was 9.5 mg KOH/g and the total quantity of hydrophilising agent was 2.9 wt.%) in relation to the quantity of solid resin.

Testing the water resistance of the film

A film of both dispersions was applied, without the aid of a cosolvent, using a knifing applicator frame (150 μιη) and was stored in a water bath for 24 hours. Then the peelability and the cloudiness of the film were subjected to qualitative assessment. In addition, the stability on storage was tested by continuous pumping of the dispersion at 40°C. After 24 h, a qualitative assessment was made of whether agglomeration had taken place.

Comparison Example 1 describes a polyurethane dispersion in which only DMPA was used as the hydrophilising agent. Although the peelability is good, the pumping test shows agglomeration, which results in undesirable specks forming in the film when it is applied.

Comparison Example 2 describes a polyurethane dispersion in which only AAS was used for hydrophilisation. Although the dispersion is stable in the pumping test, the film comes away from the substrate too easily when stored in water, which can lead to its becoming detached when the vehicles in question are transported in wet weather conditions. Examples 3 to 6, which are according to the invention and which comprise a mixture of both hydrophilising agents, meet the requirements of both stability on pumping and good peelability.

Claims

1. Anionically hydrophilised polyurethane-polyurea-polymer comprising a) at least one NCO prepolymer, including i) 20 to 60 wt.% of at least one diisocyanate, ii) 20-80 wt.%) of at least one macrodiol having a number average molecular weight of from 500 to 10 000, iii) 2 to 12 wt.%) of at least one 2,2-bis-(hydroxymethyl)-alkane-monocarboxylic acid, iv) 0 to 15 wt.%) of at least one short-chain diol having a number average molecular weight of from 62 to 400, v) 0 to 10 wt.%) of at least one monofunctional alcohol having a number average molecular weight of from 32 to 350, bl) 0,5 to 10 wt.%) of at least one N-(2-aminoalkyl)-2-aminoalkylsulfonic acid, b2) 0 to 15 wt.%) of at least one diamine having a molecular weight of from 60 to 300, c) 0 to 10 wt.% of at least one monofunctional amine, d) 0 to 3 wt.%) of water, and e) 0 to 10 wt.% of at least one neutralising agent, in which, in prepolymer stage a), the NCO content is adjusted to from 65 to 85% of the calculated NCO content, the sum of aiii) and bl) lies in the range of from 3 to 15 wt. %>, and the ratio of aiii) to b 1 ) lies in the range of from 6:1 to 1 :1. - I f

Polyurethane-polyurea-polymer according to Claim 1 , wherein, in prepolymer stage a), the NCO content is adjusted to from 75 to 80% of the calculated NCO content.

Polyurethane-polyurea-polymer according to Claim 1 , wherein the sum of aiii) and bl) lies in the range of from 3 to 10 wt.%.

Polyurethane-polyurea-polymer according to Claim 1, wherein the ratio of aiii) to bl) lies in the range of from 5:1 to 1 :1.

Polyurethane-polyurea-polymer according to Claim 1 , wherein the acid value of the prepolymer lies in the range of from 5 to 20 mg KOH/g.

Polyurethane-polyurea-polymer according to Claim 1 , wherein the component aiii) is dimethylolpropionic acid.

Polyurethane-polyurea-polymer according to Claim 1, wherein the component bl) is the sodium salt of N-(2-aminoethane)-2-sulfonic acid.

Coating composition comprising polyurethane-polyurea-polymer according to one or more of claims 1 to 7.

A method for manufacturing polyurethane-polyurea-polymer according to one or more of claims 1 to 7, including the steps of:

- placing the components a)i), ii) and iii) in a reactor under anhydrous conditions in a temperature range from 50 - 150°C,

- adding acetone and optionally components a)iv) and optionally component a) v) and heating until the NCO content of the mixture has fallen to a value of 65 to 85% of the calculated NCO content,

- adding acetone and component bl) and optionally components b2), c) and e).

10. Use of the coating composition according to claim 8 as coatings and finishes. Use according to claim 10, in which the coatings and finishes are used for the protection of motor vehicles, steel, aluminium and metal articles of all kinds, glass and plastics articles of all kinds, mineral substrates, masonry or natural stone, and for the prevention of corrosion in ships, bridges, aeroplanes or railways, and for the protection of articles of wood and natural materials.

12. Use of the coating composition according to claim 8 as recyclable peelable coatings.