HK1081582B - Aqueous two-component polyurethane systems - Google Patents

Description

Aqueous two-component polyurethane system

The present invention relates to aqueous two-component polyurethane systems comprising vinyl polymer polyol dispersions modified with reactive diluents, to a process for preparing them and to their use as coatings.

The prior art, for example EP-A0358979, EP-A0496210 and EP-A0557844, fully describes aqueous two-component (2K) Polyurethane (PUR) systems; both the so-called secondary dispersions and the so-called primary dispersions are used as polyol component and are combined with the appropriate polyisocyanate.

"Secondary dispersions" are those aqueous dispersions which are first polymerized in a homogeneous organic medium and then redispersed and neutralized in an aqueous medium, generally without the addition of external emulsifiers. "Primary dispersion" is a polyol dispersion prepared directly in the aqueous phase by emulsion polymerization techniques. In such techniques, it is generally necessary to use external emulsifiers which bring about an electrostatic or steric stabilization.

Highly suitable as fast physically drying aqueous 2K PUR systems are, for example, those which comprise a primary dispersion as polyol component. These polyol components have a molar mass value of Mn significantly greater than 5000g/mol and Mw values generally greater than 30000 g/mol. These primary dispersions can generally only be combined with (partially) hydrophilicized polyisocyanates, so that relatively uncomplicated dispersions can be provided with relatively simple stirring devices or by hand and glass rods (for example, EP-A0557844). In addition, such aqueous 2K PUR systems typically include relatively high concentrations of organic co-solvents that act as coalescing aids in forming thin films on the aforementioned substrates. For example, when such aqueous, co-solvent containing 2K PUR systems are applied as coatings on, for example, mineral substrates, such as floors as substrates, coatings are obtained which show very good levelling, relatively high gloss and low haze values, but Volatile Organic Compounds (VOC) have a severe adverse effect on the environment and can even be a burden for health care.

Oligoether or polyether polyols are likewise known from the prior art as reactive diluents in so-called aqueous vinyl polymer dispersions. For example, EP-A0557844 describes that the polyvinyl polyol dispersion of the primary dispersion type used in aqueous 2K PUR systems may further comprise up to 10% by weight of a water-soluble polyhydric alcohol, such as ethylene glycol, propylene glycol, glycerol, trimethylolpropane or low molecular weight, water-soluble alkoxylation products of these polyhydric alcohols, based on the total weight of the polymer resin.

EP-A0758007 discloses aqueous crosslinkable binder dispersions A) with a low solvent content, comprising at least one hydroxy-functional polyether A1) and a hydroxy-functional vinyl polymer resin synthesized in two steps from a relatively hydrophobic component A2) and a relatively hydrophilic component A3). These hydroxyl-functional vinyl polymers are secondary dispersions which are prepared by free-radical polymerization in a homogeneous organic medium in the presence of a low-molecular-weight volatile solvent and the hydroxyl-functional polyether A1) and are then dispersed in the aqueous phase together with a neutralizing agent. Although it is possible in principle to remove the organic cosolvents from these binder dispersions by distillation, the additional use of cosolvents as auxiliaries in the binder/crosslinker system is considered to be unavoidable for better compatibility of the components (binder and crosslinker) and for better film-forming properties.

It is therefore an object of the present invention to provide polyol dispersions as binders for aqueous 2KPUR systems, which do not require the addition of further co-solvents and can be used as coatings for any desired substrates.

It has been surprisingly found that when the hydroxyl-functional vinyl polymer of the primary dispersion type is used with a hydroxyl-functional, hydrophobic (i.e., water-insoluble) polyether and an unblocked polyisocyanate as a crosslinker, no volatile co-solvent is required in an aqueous 2KPUR system to provide good compatibility between the polyol component and the polyisocyanate component or to provide excellent film-forming properties after application of the 2KPUR system.

The invention provides a process for preparing aqueous two-component polyurethane systems, characterized in that, in a first step, a polyol component a) formed from a hydrophobic core polymer having a glass transition temperature of 40 to 100 ℃, preferably 40 to 80 ℃, and a hydrophilic shell polymer having a glass transition temperature of-100 ℃ to +25 ℃, preferably-50 ℃ to +20 ℃, grafted thereon by aqueous emulsion polymerization is prepared, a hydroxyl-containing polyether component b) is added before, during or after the polymerization of component a), and then, in a second step, a polyisocyanate component c) is admixed.

In the process of the present invention, it is preferred not to add any co-solvent.

The polyol component a) comprises a hydroxyl-functional copolymer having a hydroxyl number of from 10 to 264mg KOH/g resin solids, preferably from 30 to 150mg KOH/g resin solids, an acid number of from 3 to 55mg KOH/g resin solids, preferably from 4 to 30mg KOH/g resin solids, which acid number is associated both with free, unneutralized acid groups and with acid groups present in neutralized form. Suitable acid groups are, for example, carboxyl groups and/or sulfonic acid groups. Preferred are carboxyl and/or carboxylate groups. The amount of carboxylate and/or sulfonate groups chemically bound is from 5 to 98, preferably from 7 to 53, milliequivalents per 100g of solid.

The polyol component a) generally has a molecular weight Mn, determined by gel permeation chromatography using polystyrene as standard, of 5000-. These molar measurements do not take into account the crosslinked polymer fraction, e.g. microgels.

The polyol component a) contains:

A)0.5 to 7 wt.%, preferably 0.5 to 5 wt.%, particularly preferably 0.7 to 3.0 wt.% of acrylic acid and/or methacrylic acid,

B)5 to 75 wt.%, preferably 20 to 70 wt.%, particularly preferably 30 to 60 wt.%, of methyl methacrylate and/or styrene,

C)3 to 40 wt.%, preferably 10 to 40 wt.%, particularly preferably 20 to 30 wt.% of one or more acrylic acids C_1-8Alkyl esters and/or methacrylic acid C_2-8An alkyl ester, a carboxylic acid,

D)2 to 74 wt.%, preferably 5 to 50 wt.%, particularly preferably 10 to 30 wt.%, of one or more monohydroxy-functional alkyl acrylates and/or monohydroxy-functional alkyl methacrylates,

E) from 0 to 30% by weight, preferably from 0 to 15% by weight, particularly preferably 0% by weight, of other ethylenically unsaturated monomers,

the sum of the components is 100 wt%.

Suitable acrylic acids C_1-8Alkyl esters C) include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate, n-octyl acrylate or 2-ethylhexyl acrylate. Preference is given to n-butyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, particular preference to n-butyl acrylate and/or 2-ethylhexyl acrylate.

Suitable methacrylic acids C_2-8Alkyl esters are, for example, ethyl methacrylate, n-butyl methacrylate and/or 2-ethylhexyl methacrylate.

Suitable hydroxy-functional (meth) acrylates D) include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyisopropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate or any desired mixtures of these monomers. Preferred are 2-hydroxyethyl methacrylate and technical grade mixtures of 2-hydroxypropyl methacrylate and 2-hydroxyisopropyl methacrylate, commonly known as hydroxypropyl methacrylate.

Other monomer units E) may be substituted styrene derivatives, for example the isomeric vinyltoluenes, alpha-methylstyrene, propenylbenzene, the (meth) acrylic acids C₅-C₁₂Cycloalkyl esters, isobornyl (meth) acrylate, vinyl esters, such as vinyl acetate, vinyl propionate or vinyl versatate, or vinylsulfonic acid.

The preparation of the polyol component a) is carried out directly in the aqueous phase by emulsion polymerization techniques, which are known in principle, for example as summarized in B.Vollmert, "Grundris der Makromolekulare Chemie", first volume, page 181 below, Vollmert Verlag1988, Karlsruhe, or H.G.Elias, "Makromolekule", second volume, page 93 below, Huthig & Wepf Verlag Basel, Heidelberg, New York 1992.

Examples of suitable free radical initiators include peroxodisulfates, such as potassium peroxodisulfate or ammonium peroxodisulfate. However, redox systems, such as ammonium peroxodisulfate/sodium hydroxymethanesulfinate (Rongalit ® C, BASF AG, Ludwigshafen)/iron sulfate or tert-butyl hydroperoxide/Rongalit ® C/iron sulfate, can also be used as free-radical initiators.

In the preparation of the polyol component a) according to the principle of emulsion polymerization, it is also possible to use together external emulsifiers, for example anionic emulsifiers, examples being those based on alkyl sulfates, such as those indicated in Houben-Weyl, Methoden der organischen Chemie, Erweiterung-und Folgeb nde, fourth edition, Vol.E 20, 1987 (part 1, page 262 259-If.262), alkylaryl sulfonates, alkylphenol polyether sulfates, or alkyl polyether sulfates, sulfosuccinate salts or nonionic emulsifiers, for example alkoxylation, in particular ethoxylation products, of alkanols, phenols or fatty acids, which remain in the 2K PUR system of the invention after the preparation of the polyol component a) and can be regarded as auxiliaries and additives d).

In the presence of such emulsifiers, it is generally sufficient to neutralize only very small amounts of the acid groups present in order to ensure the homogeneity of the solution or dispersion of the polyol component a). The neutralizing agent still used, at least in low concentration, can be introduced into the system as early as possible during the emulsion polymerization. Thus, in the case of low concentrations of salt-like groups, the solubility or dispersibility of the polyol component a) in water can be promoted by the concomitant use of external emulsifiers. In any case, it is necessary to ensure the dilutability of the copolymers in water, either in the form of dispersions or colloidal to molecularly dispersed "solutions".

The process for preparing the polymer polyol component a) is carried out in at least two stages: in the first polymerization stage, the free-radical-initiated polymerization forms a relatively hard polymer as the graft base, i.e.a polymer having a glass transition temperature of from 40 to 100 ℃, preferably from 40 to 80 ℃, and in the second polymerization stage, a relatively soft polymer, i.e.a polymer having a glass transition temperature of from-100 ℃ to +25 ℃, preferably from-50 ℃ to +20 ℃, as the graft is grafted onto this graft base, for example in a manner analogous to DE-A19858732, page 3, line 30. In this connection, the first polymerization stage and the second grafting stage can be carried out using relatively hydrophilic monomer mixtures (i.e. with comonomers containing acid groups).

Preference is given, however, to a process in which a relatively hydrophobic, hard polymer which is free of acid groups and serves as a grafting base is first prepared in the aqueous phase by free-radical-initiated polymerization in the presence of an external emulsifier, and a more hydrophilic, softer graft (stufe) which contains carboxyl groups is grafted in a subsequent second polymerization stage.

It is also possible to have multiple sequential polymerization steps, where sequential steps result in increasingly hydrophilic and more flexible polymers. Of course, also possible is a so-called gradient procedure as described in WO-A98/12230, page 8, line 25, below, in which the hydrophilicity and the polymer hardness (determined by means of the glass transition temperature) are continuously varied during the feed

The unsaturated acid a) and optionally E) added in the polymerization are at least partially neutralized after the end of the polymerization, so that the resulting anionic groups ensure the solubility or dispersibility of the polyol component a) in water. Here, 5 to 100% of the acid groups added in the polymerization should be present in a form neutralized with aliphatic amines or ammonia.

Compounds suitable for at least partially neutralizing the acid groups added in the polymerization include ammonia or aliphatic amines, such as triethylamine, dimethylethanolamine, diethylethanolamine, triethanolamine, or any other aliphatic amine having a molecular weight of from 31 to 200 g/mol. Preference is given to using ammonia, triethylamine or dimethylethanolamine.

Ideally, the final product is a core-shell polymer having a hydrophobic, relatively hard core and a hydrophilic, relatively soft shell.

The polyol component a) in the aqueous phase generally has a solids content of from 20 to 60% by weight, preferably from 30 to 50% by weight, a pH of from 6 to 10, preferably from 6.5 to 8.5, a viscosity of from 5 to 5000 mPas, preferably from 5 to 2000mPas (at 23 ℃ C. and 45.4 s)^-1Measured at a shear rate) and an average particle size (measured by laser correlation spectroscopy) of 50 to 300nm, preferably 70 to 200 nm.

Suitable hydroxy-functional polyethers b) have an OH functionality of from 1.8 to 6.0, preferably from 2.0 to 4.0, an OH number of from 50 to 700, preferably from 100, mg KOH/g solids and a molecular weight Mn of from 106 to 4000, preferably from 200 to 3500g/mol, for example hydroxy-functional precursor molecules, such as ethylene glycol, propylene glycol, butanediol, hexanediol, trimethylolpropane, glycerol, pentaerythritol, sorbitol or mixtures thereof and also alkoxylation products of other hydroxy-functional compounds with propylene oxide or butylene oxide. Preferred as polyether component b) are polypropylene oxide polyols having a molecular weight of 300-4000 g/mol. In this case, particularly low molecular weight polyether polyols can be dissolved in water at a suitably high OH content. However, particularly preferred are water-insoluble polypropylene oxide polyols.

The polyisocyanate component c) has a viscosity of from 5 to 12000mPa · s, preferably from 50 to 10000mPa · s, and may have:

c1) hydrophobic, non-hydrophilizing properties or

c2) Hydrophilizing properties.

When using the non-hydrophilicized, water-insoluble or water-nondispersible polyisocyanate component c1) in the process of the invention, effective dispersing action can be achieved using only highly effective dispersing devices, for example using nozzle dispersers according to EP-A0685544. With this dispenser, the greatest possible chemical and water resistance of the 2K PUR system is obtained after application of the film.

However, nonionic or anionic hydrophilization of c) is absolutely necessary in the case of effective dispersion of the polyisocyanate component c) in finely divided form with simpler dispersing devices such as dissolvers or possibly even manually with the polyol components a) and b). The use of hydrophilicized polyisocyanates c2) or mixtures of c1) and c2) with good dispersibility in the aqueous phase is therefore preferred.

Polyisocyanates suitable as component c) are, in particular, "lacquer polyisocyanates", which, as is known, have aromatic, aliphatic or cycloaliphatic radical-bonded isocyanate groups, preferably aliphatic or cycloaliphatic polyisocyanates.

Examples of preferred polyisocyanates c) include "lacquer polyisocyanates" based on hexamethylene diisocyanate or 1-isocyanato-3, 3, 5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) and/or bis (isocyanatocyclohexyl) methane, in particular those based on hexamethylene diisocyanate alone.

By "lacquer polyisocyanates" based on these diisocyanates is meant the derivatives of these diisocyanates known per se which contain biuret, urethane, uretdione, allophanate and/or isocyanurate groups and whose residual content after their preparation has been reduced to a residual content of less than 0.5% by weight in a known manner, preferably by distillation, with excess starting diisocyanate being removed. Preferred aliphatic polyisocyanates are the polyisocyanates containing biuret groups and based on hexamethylene diisocyanate, consisting of mixtures of N, N ', N "-tris (6-isocyanatohexyl) biuret with small amounts of its higher homologues, and the cyclic trimers of hexamethylene diisocyanate which meet the stated criteria and consist essentially of mixtures of N, N', N" -tris (6-isocyanatohexyl) isocyanurate with small amounts of its higher homologues. Especially preferred are the corresponding mixtures based on hexamethylene diisocyanate and polyisocyanates containing uretdione and/or isocyanurate groups, such as those formed by catalytic oligomerization of hexamethylene diisocyanate using trialkylphosphines. Particular preference is given to the last-mentioned mixtures having a viscosity (23 ℃) of from 50 to 500 mPas and an NCO functionality of from 2.2 to 5.0. However, monomeric polyisocyanates such as 4-isocyanatomethyloctane 1, 8-diisocyanate can also be used.

Likewise suitable are "lacquer polyisocyanates" based on 2, 4-diisocyanatotoluene or its technical-grade mixtures with 2, 6-diisocyanatotoluene or on 4, 4' -diisocyanatodiphenylmethane or mixtures with its isomers and/or higher homologues. Examples of such aromatic lacquer polyisocyanates are urethane group-containing isocyanates, such as those obtained by reacting an excess of 2, 4-diisocyanatotoluene with a polyol, such as trimethylolpropane, followed by removal of excess unreacted diisocyanate by distillation. Other polyisocyanates for aromatic lacquers are, for example, the trimers of the monomeric diisocyanates exemplified, i.e. the corresponding isocyanatoisocyanurates, which likewise have been freed of excess monomeric diisocyanate after preparation, preferably by distillation.

In principle, it is also possible to use the unmodified polyisocyanates of the type exemplified, provided they comply with the comments given for viscosity.

Furthermore, the polyisocyanate component c) can consist of any desired mixtures of the polyisocyanates exemplified.

Preference is given to using hydrophilicized polyisocyanates c2) which can be prepared by nonionically and/or anionically hydrophilicizing the abovementioned hydrophobic polyisocyanates.

The nonionic hydrophilicization of the polyisocyanate component c) is generally carried out by modifying unmodified hydrophobic polyisocyanates with polyether monools, for example according to EP-A0540985, page 3 line 55 to page 4 line 5 and EP-A0959087, pages 3 lines 39 to 51.

The anionic hydrophilization of component c) can be carried out using phosphate, sulfate or sulfonate groups. Preference is given here to using sulfonate groups which are present in chemically bound form in the polyisocyanate. They are prepared, for example, by reacting polyisocyanates with sulfonate group-containing compounds which additionally carry at least one group which is reactive with NCO groups. As examples of such compounds, mention may be made of the reaction products of polyisocyanates with 3- (cyclohexylamino) propanesulfonic acid. The sulfonic acid and/or sulfonate ester groups may be present here in an amount of from 0.1 to 5.0% by weight, based on the polyisocyanate.

It is also possible in principle to use polyisocyanates with hybrid hydrophilicization, as described, for example, in EP-A0510438, page 2, line 56 to page 3, line 5. In this case, the hydrophilization with nonionic polyether groups is carried out simultaneously with the hydrophilization with anionic or potentially ionic groups, i.e. groups capable of forming ionic groups, preferably with anionic carboxyl groups.

Examples of suitable auxiliaries and additives d) include pigments, fillers, levelling agents, thickeners, defoamers, devolatilizers (Entl fur) and the like.

The aqueous two-component polyurethane systems of the invention are generally prepared simply by manually stirring the individual components a), b) and c), or by subjecting them to the action of a stirrer, or optionally, in the case of difficult-to-disperse 2K systems, with a nozzle disperser, the proportions being selected so as to provide NCO/OH equivalent ratios of from 0.2: 1 to 5: 1, preferably from 0.7: 1 to 3: 1.

It is possible here in principle to add the hydroxyl-containing polyether component b) before or during the polymerization of a). When component b) is introduced into the polyol component a) before the polymerization, it is added to the aqueous initial charge, optionally together with an anionic emulsifier, in the case of emulsion polymerization.

Component a) is preferably combined with 1.0 to 30.0% by weight of a hydroxy-functionalized polyether b) as reactive diluent.

In a preferred embodiment of the process of the invention, the polyether component b) is used during the feed polymerization of a), and is then added subsequently to the inflow monomer mixture or, in the case of sufficient dissolution or dispersion in water, to the aqueous inflow initiator solution. It is particularly preferred to use the polyether component b) in the monomer feed during the preparation of the graft polymers described above.

It is also possible in principle to add the polyether component b) to the polyol component a) at the end of the polymerization, for example during neutralization. However, this process variant is only of interest if both polyol components a) and b) are highly compatible with one another, since in this case they constitute a pure mixture of a) and b) (reine Mischungen).

The compatibility between the polyisocyanate component c) and the sum of the polyol components a) and b) and thus the easy dispersibility of the aqueous 2K PUR systems prepared from these components is markedly increased if the polyisocyanate component c) has been subjected to nonionic or anionic hydrophilization. It is therefore preferred to carry out the dispersion by hand or by simple stirring means, such as a dissolver.

The invention also provides aqueous two-component polyurethane systems obtainable by the process of the invention.

To prepare the coating compositions, it is optionally possible to incorporate further auxiliaries and additives d) of the coating technology into the aqueous 2K PUR systems of the invention. Such auxiliaries and additives d) also include, for example, an additional amount of water for adjusting the 2K PUR systems of the invention to a suitable processing viscosity. The 2K PUR systems according to the invention can therefore be used as coatings, for example as lacquers or adhesives.

The present invention likewise provides coating compositions comprising the aqueous 2K PUR systems of the invention.

In the process of the present invention, no organic solvent is added to the resin component or curing component or coating formulation. Nevertheless, many commercially available coating adjuvants and additives are supplied as solutions in organic solvents so that small amounts of organic co-solvents can be incorporated into the coating if such additives are used. The aqueous coating composition of the invention may therefore optionally contain less than 2 wt.%, preferably less than 1 wt.%, particularly preferably less than 0.5 wt.% of organic co-solvents.

The coating compositions comprising the 2K PUR systems of the invention can be applied to any desired substrates, such as wood, metal, plastic and mineral substrates, and also synthetic resin coatings based on EP and PU, by all standard industrial processes such as spraying, dipping or brushing, and can be dried at temperatures of from 0 to 180 ℃, preferably curing temperatures of from 15 to 80 ℃.

The invention further provides a process for producing coated substrates, characterized in that the 2K PUR system according to the invention is used as a coating composition. Preferred substrates in this case are mineral substrates and synthetic resin coatings based on EP and PU. In this respect, particularly high resistance of the cured coating to aqueous chemicals can be found.

The present invention likewise provides substrates coated with coating compositions comprising the aqueous two-component polyurethane systems of the invention.

The experimentally determined acid number is generally significantly higher than the theoretical value corresponding to the above-mentioned incorporation conditions. This can be attributed to hydrolysis phenomena and to the ionic groups of the emulsifier and initiator fragments.

Examples

Polyisocyanate 1

Hydrophilicized polyisocyanates containing isocyanurate, urethane and allophanate groups and based on 1, 6-diisocyanatohexane (HDI) and having an NCO content of 16.2% and a viscosity of 6800mPa.s (23 ℃, 100% form) (Bayhydur ® VPLS2336, Bayer AG, Leverkusen, DE).

Polyisocyanate 2

Hydrophilicized polyisocyanates containing isocyanurate, urethane and allophanate groups and based on 1, 6-diisocyanatohexane (HDI) have an NCO content of 18.1% and a viscosity of 4500mPa.s (23 ℃, 100% form) (Ba yhydu r ® VP LS 2319, Bayer AG, Leverkusen, DE).

Polyisocyanate 3

Hydrophilized polyisocyanates containing isocyanurate groups and urethane groups and based on 1, 6-diisocyanatohexane (HDI) have an NCO content of 17.3% and a viscosity of 3000mPa.s (23 ℃, 100% form) (Bayhydu r ® XP7063, Bayer Corp., USA).

Polymer polyol 1 (comparative example with core/shell Structure, but without polyether polyol)

12.5g of an aqueous slurry of 80% by weight of emulsifier A (C with a degree of polymerization of about 3) are charged in a 3L glass reactor with a high-efficiency paddle stirrer, gas inlet and outlet, reflux condenser and thermal regulating device to ensure isothermal conditions_12-18Ammonium salts of monoesters of fatty alcohol polyethylene oxides; emulgator 951, Bayer AG, Leverkusen, DE) and 720g of deionized water (solution I). After the mixture was thoroughly purged with nitrogen, the initial charge was heated to a temperature of 80 ℃. During this time, a continuous nitrogen flow was maintained above the liquid level. Subsequently, mixture II and solution III were metered in over the course of approximately 5 minutes.

II. Hydroxypropyl methacrylate: 8.3g

Methyl methacrylate: 30g of

Styrene: 45g of

N-butyl acrylate: 14.7g

III, ammonium peroxodisulfate: 0.3g

Deionized water: 17g

After a reaction time of 30 minutes, during which so-called "in situ" seeds are formed, mixture IV is metered in over 2 hours and solution V is metered in over 4 hours, both below the level of the liquid, i.e. in the impregnated state.

IV, hydroxypropyl methacrylate: 37.4g

Methyl methacrylate: 135.1g

Styrene: 202.6g

N-butyl acrylate: 65.9g

V, ammonium peroxodisulfate: 3.0g

Emulsifier a (see above, 80% form): 12.5g

Deionized water: 600g

Immediately after the end of the addition of the monomer stream IV, the metering of the monomer stream VI is started. The monomer stream is likewise metered in over 2 hours, so that both volume flows V and VI end at the same time.

VI, acrylic acid: 10.0g

Hydroxypropyl methacrylate: 123.3g

Methyl methacrylate: 34.9g

Styrene: 52.4g

N-butyl acrylate: 220.4g

After this time, the mixture was stirred for a further 1 hour and subsequently reactivated with solution VII.

VII, ammonium peroxodisulfate: 1.0g

Deionized water: 10.0g

After subsequent stirring for a further 4 hours, the mixture is cooled to room temperature and then neutralized with mixture VIII.

VIII, ammonia (25% aqueous solution): 7.5g

Deionized water: 10.0g

(calculation of degree of neutralization 79.4% based on carboxyl group.)

The product was then discharged and filtered.

The physicochemical properties of the dispersion are as follows:

solid content: 42.0 wt.%

pH： 7.3

Viscosity (23 ℃ C.; D42 s)^-1)： ＜100mPas

Average particle size (LKS): 91nm

Acid value: 7.3mg KOH/g Dispersion

Polymer polyol 2 (inventive)

Analogously to example 1, however, the polyether is added during the polymerization of the graft

The polymer polyol was prepared as in the examples other than polymer polyol 1 of the present invention; the composition of the monomer mixture VI which forms the graft after polymerization is modified as follows:

VI, acrylic acid: 10.0g

Hydroxypropyl methacrylate: 123.3g

Methyl methacrylate: 34.9g

Styrene: 52.4g

N-butyl acrylate: 170.4g

Polyether-Desmophen®550U

(Bayer AG，Leverkusen，DE) 50.0g

(Polyether-Desmophen ® 550U, Bayer AG, Leverkusen, DE is a polypropylene oxide based on trimethylolpropane as precursor, having an average molecular weight Mn of 437g/mol and an OH number of 385mg KOH/g resin solids; the degree of neutralization here is 100% based on carboxyl groups).

The physicochemical properties of the dispersion are as follows:

solid content: 41.8 wt.%

pH： 8.0

Viscosity (shear gradient D ═ 45.4 s)^-1；T＝23℃)： 14mPa.s

Average particle size (LKS): 106nm

Acid value: 6.8mg KOH/g Dispersion

Glass transition temperature (DSC method): 11.5 ℃/66.0 DEG C

(i.e., clearly 2 glass transitions)

Polymer polyols, examples 3 to 7 (according to the invention)

Solution I (see table 1) was charged in a 3L glass reactor with a high-efficiency paddle stirrer, gas inlet and outlet, reflux condenser and thermal regulation to ensure isothermal conditions, and flushed thoroughly with nitrogen. Thereafter, the initial charge I was heated to a temperature of 80 ℃ with stirring at about 200 rpm. During this time, a continuous nitrogen flow was maintained above the liquid level. Subsequently, mixture II and solution III (see Table 1) were metered into the initial charge I over the course of approximately 5 minutes.

After a reaction time of 30 minutes, the mixture IV (see table 1) and the solution V (see table 1) were metered into the in situ seed in the impregnated state over 2 hours.

Immediately after the end of the addition of the monomer stream IV (cf. Table 1), the metering of the monomer stream VI is started. These monomer streams VI are likewise metered in over 2 hours.

After this time, the mixture was stirred for a further 1 hour, after which the batch was reactivated with solution VII (see table 1).

The batch is subsequently stirred for a further 4 hours, then cooled to room temperature and neutralized with mixture VIII (see Table 1). The product was subsequently discharged and filtered through a polyamide cloth having a mesh size of 100 μm.

Dispersions 3-7 have the characteristic physicochemical data listed in table 1.

Table 1:

composition and physicochemical Properties of polyol dispersions 3 to 7

	Example 3[ g)]	Example 4[ g ]]	Example 5[ g)]	Example 6[ g)]	Example 7[ g)]
						Initial charge I: emulsifier A deionized water	5.0720	4.0720	2.0720	1.0720	1.0720
Monomer mixture II (in situ seed): hydroxypropyl methacrylate methyl methacrylate styrene n-butyl acrylate	8.330.04 5.014.7	8.330.045.014.7	8.330.045.014.7	8.330.045.014.7	8.330.045.014.7
						Initiator solution III (in situ seed): ammonium peroxodisulfate deionized water	0.317.0	0.317.0	0.317.0	0.317.0	0.317.0
Monomer stream IV (feed): hydroxypropyl methacrylate methyl methacrylate styrene n-butyl acrylate	37.4135.1202.665.9	37.4135.1202.665.9	37.4135.1202.665.9	37.4135.1202.665.9	37.4135.1202.665.9
						Initiator/emulsifier feed V: ammonium peroxydisulfate emulsifier A deionized water	3.020.0600	3.021.0600	3.023.0600	3.024.0600	3.024.0600

Monomer stream VI (feed): hydroxypropyl methacrylate methyl methacrylate n-butyl styrene acrylate Polyther-Desmophen ® 550UPolyether-Desmophen ® L400 Polyther-Desmophen ® 1600UPolyether-Desmophen ® 3600	10.012 3.334.952.4170.450.0	20.0123.324.952.4170.450.0	10.0123.334.952.4170.450.0	10.0123.334.952.4170.450.0	10.0123.334.952.4170.450.0
						Reactivator solution VII: ammonium peroxodisulfate deionized water	1.010.0	1.010.0	1.010.0	1.010.0	1.010.0
Neutralizing solution VIII: ammonia (25%, aqueous solution) deionized water	9.410.0	15.010.0	9.410.0	9.410.0	9.410.0
						Solids content [ wt.%]	42.1	42.3	42.1	41.8	42.0
pH	8.0	7.3	7.5	7.7	7.4
						Viscosity (T ═ 23 ℃ C.; D ═ 45.4 s)-1)[mPa.s]	32	118	2 0	22	18
Average particle size (LKS) [ nm ]]	110	125	160	135	136
						Acid number [ mg KOH/g Dispersion]	7.4	11.6	6.7	7.4	7.5

Emulsifier a: reference comparative example Polymer polyol 1

Polyether-Desmophen®550U：Bayer AG，Lev，DE，Mn＝437g/mol，

Polypropylene oxide polyols having a functionality f-3

Polyether-Desmophen®L400：Bayer AG，Lev，DE，Mn＝561g/mol，

OH value: 200mg KOH/g FH (f ═ 2) polypropylene oxide polyol

Polyether-Desmophen ® 1600U: polypropyleneoxide polyol from Bayer AG, Lev, DE, Mn 1000g/mol

Polyether-Desmophen®3600：Bayer AG，Lev，DE，Mn＝2000g/mol，

OH value: 56mg KOH/g FH (f ═ 2) polypropylene oxide polyol

Polymer polyols, examples 8 and 9 (according to the invention)

Polyether is added in the neutralization process

Solution I (see table 2) was charged in a 3L glass reactor with a high-efficiency paddle stirrer, gas inlet and outlet, reflux condenser and thermal regulation to ensure isothermal conditions, and was flushed thoroughly with nitrogen. Thereafter, the initial charge I was heated to a temperature of 80 ℃ with stirring at about 200 rpm. During this time, a continuous nitrogen flow was maintained above the liquid level. Subsequently, mixture II and solution III (see Table 2) were metered into the initial charge I over the course of approximately 5 minutes.

After a reaction time of 30 minutes, the mixture IV was metered into the in situ seed in the impregnated state over 2 hours and the solution V (cf. table 3) over 4 hours.

Immediately after the end of the addition of the monomer feed IV, the metering of the second monomer stream VI is started.

After the simultaneous conclusion of the feeds V and VI, stirring was continued for 1 hour and then reactivated with solution VII (cf. Table 3). After this time, stirring was continued for a further 4 hours, after which the product was cooled to room temperature and neutralized with mixture VIII (see Table 3).

The product was then discharged and filtered through a polyamide filter having a mesh size of 100 μm.

Dispersions 8 and 9 have the characteristic physicochemical data listed in table 3.

Table 2:

composition and physicochemical Properties of polyol dispersions 8 and 9

	Example 8[ g)]	Example 9[ g)]
			Initial charge I:emulsifier A deionized water	12.5720	12.5720
Monomer mixture II (in situ seed): hydroxypropyl methacrylate methyl methacrylate styrene n-butyl acrylate	8.330.045.014.7	8.330.045.014.7
			Initiator solution III (in situ seed): ammonium peroxodisulfate deionized water	0.317.0	0.317.0
Monomer stream IV (feed):hydroxypropyl methacrylate methyl methacrylate styrene n-butyl acrylate	37.4135.1202.665.9	37.4135.1202.665.9
			Initiator/emulsifier stream V (feed): ammonium peroxydisulfate emulsifier A deionized water	3.012.5600	3.012.5600
Monomer stream VI (feed): acrylic acid hydroxypropyl methacrylate methyl methacrylate styrene n-butyl acrylate	10.0123.334.952.470.4	10.0123.334.952.420.4
			Reactivating an agent solution VII;ammonium peroxodisulfate deionized water	1.010.0	1.010.0

Neutralization solution VIII:ammonia (25%, aqueous solution) Polyether-Desmophen ® 550U deionized water	9.415010	9.420010
			Solids content [ wt.%]	41.6	41.6
pH	7.0	7.1
			Viscosity (T ═ 23 ℃ C.; D ═ 45.4 s)-1)[mPa.s]	10	＜100
Average particle size (LKS) [ nm ]]	97	107
			Acid number [ mg KOH/g Dispersion]	7.0	6.6

Emulsifier a: emulgator 951, Bayer AG, Lev, DE

Polymer polyol example 10 (comparative example)

Dispersion of coreless/shell structure

25g of an aqueous slurry of 80% by weight of emulsifier A (C with a degree of polymerization of about 3) are charged in a 3L glass reactor with a high-efficiency paddle stirrer, gas inlet and outlet, reflux condenser and thermal regulating device to ensure isothermal conditions_12-18Ammonium salts of monoesters of fatty alcohol polyethylene oxides; emulgator 951, Bayer AG, Leverkus en, DE) and 690g of deionized water (solution I). After the mixture was thoroughly purged with nitrogen, the initial charge was heated to a temperature of 80 ℃. During this time, a continuous nitrogen flow was maintained above the liquid level. Subsequently, mixture II and solution III were metered in over the course of approximately 5 minutes.

II. Acrylic acid 3.0g

Hydroxypropyl methacrylate: 34.0g

Methyl methacrylate: 50.0g

N-butyl acrylate: 10.0g

1.0g of alpha-methylstyrene dimer

III, ammonium peroxodisulfate: 0.5g

Deionized water: 86.0g

After a reaction time of 30 minutes, during which so-called "in situ" seeds are formed, the mixture IV and the solution V are metered in parallel below the level of the liquid, i.e. in the impregnated state over 6 hours.

IV, acrylic acid 27.0g

Hydroxypropyl methacrylate: 305.0g

Methyl methacrylate: 450.0g

N-butyl acrylate: 81.0g

19.0g of alpha-methylstyrene dimer

V, ammonium peroxodisulfate: 3.0g

Deionized water: 516.0g

After this time, the mixture was stirred for a further 2 hours and subsequently reactivated with solution VII.

VI, ammonium peroxodisulfate: 0.5g

Deionized water: 86.0g

After subsequent stirring for a further 4 hours, the mixture was cooled to room temperature and then neutralized with mixture VII.

VII, ammonia (25% aqueous solution): 17.0g

Deionized water: 20.0g

The product was then discharged and filtered.

The physicochemical properties of the dispersion are as follows:

solid content: 43.9 wt.%

pH： 7.0

Viscosity (23 ℃ C.; D42 s)^-1)： 150mPa·s

Average particle size (LKS): 103nm

Acid value: 12.0mg KOH/g Dispersion

Performance examples:

the source of the components used can be found in the manufacturer's catalog

TABLE 3: film-forming adhesive for transparent sealing with polyol dispersions according to examples 1 and 2 (invention) and example 10 (comparative)

Composition (I)		Composition in parts by weight
								Component 1:
polyol dispersion of example 1		58.34	58.34	58.34	-.-	-.-
								Polyol Dispersion example 2		-.-	-.-	-.-	50.00	50.00
Polyol Dispersion example 10							58.34
								Acrysol ® RM 8 (5% aqueous solution)	(1)	2.33	2.33	2.33	2.00	2.00	2.33
Foamaster®306	(2)	0.47	0.47	0.47	1.00	1.00	0.47
								Baysilone ® paint additive 3466 (10% aqueous solution)	(3)	5.83	5.83	5.83	3.00	3.00	5.83
Softened water		11.67	11.67	11.67	12.00	12.00	11.67
								Methyl propyl acetate		-.-	4.67	4.67	-.-	-.-	4.67
And (2) component:
								polyisocyanate 1		-.-	12.02	-.-	10.00	-.-
Polyisocyanate 2		10.07	-.-	10.07	-.-	8.6	20.39
								The composition (wt%):
binder		39.0	38.3	37.0	39.6	38.5	42.6
								Water content		59.7	55.6	56.8	58.6	59.7	51.8
Content of solvent		-；-	4.9	5.0	-；-	-.-	4.5
								Additive agent		1.3	1.1	1.1	1.7	1.7	1.0
Evaluation criteria
								Is the coating solvent free?		Is that	Whether or not	Whether or not	Is that	Is that	Whether or not
Film optical Properties/compatibilities		Not good	Good taste	Good taste	Good taste	Good taste	Not good
								Water resistance		Not good	n.d.**	Good taste	n.d.**	Good taste	Not good

*): the film is not uniform and is full of gel spots

**): not determined

Polyol dispersions 1, 2 and 10 were added to a dissolver and the additives described in table 3 and demineralized water were dispersed at about 5m/s for about 15 minutes. This gives dispersion batches of virtually unlimited storage stability.

a) In the case of the polyol dispersions of examples 1 and 10, it is also necessary to add methylpropyl acetate so that it can be mixed by hand with the polyisocyanate 1 or 2. If no co-solvent is added, a non-uniform film is obtained, which is saturated with gel spots.

The addition of polyisocyanate 1 or 2 gives a clear, water-dilutable two-component polyurethane coating having the composition as described in table 3.

The ready-to-use batch contains about 5% by weight of solvent. The lifetime is about 1 hour at 23 ℃.

b) In the case of the polyol dispersion of example 2, the polyisocyanate 1 or 2 can be mixed in manually. No organic co-solvent needs to be added. A clear, water-dilutable, two-component polyurethane coating having the composition as described in table 3 was obtained. The lifetime is about 1 hour at 23 ℃.

TABLE 4: matt clear sealants with polyol dispersions of examples 3, 4, 5, 6 and 7

Composition (I)	Composition in parts by weight
						Component 1:
polyol Dispersion example 3	59.5	-.-	-.-	-.-	-.-
						Polyol Dispersion example 4	-.-	59.5	-.-	-.-	-.-
Polyol Dispersion example 5	-.-	-.-	59.5	-.-	-.-
						Polyol Dispersion example 6	-.-	-.-	-.-	59.5	-.-
Polyol Dispersion example 7	-.-	-.-	-.-	-.-	59.5
						Drewplus®T-4201 (4)	1.0	1.0	1.0	1.0	1.0
Hydropalat®14 0 (2)	0.7	0.7	0.7	0.7	0.7
						Ultralube®D-818 (5)	4.8	4.8	4.8	4.8	4.8
Water (softened)	-.-	-.-	26.8	26.8	26.8
						Deuteron®MK (6)	4.9	4.9	-.-	-.-	-.-
Ceraflour®920 (7)	-.-	-.-	4.4	4.4	4.4
						Acrysol ® RM 8 (5% aqueous solution))(1)	2.4	2.4	1.2	1.2	1.2
And (2) component:
						polyisocyanate 3	7.5	7.5	10.0	10.0	10.0
Composition (wt%)
						Binder	40.3	40.4	32.3	31.9	32.3
Solids content	52.4	52.6	40.9	40.4	40.8
						Water content	45.5	45.3	57.6	58.0	57.6
Additive agent	2.1	2.1	1.6	1.6	1.6
						Characteristic data:
drying time (dry to touch (grittfest)) (room temperature, min)	360	360	-	-	-
						Tai Shi Sha, mg (CS10/1000 turn)	-	-	46	53	52
Gloss (85 degree)	12.4	14.1	15.2	14.3	15.4
						K ö nig pendulum bar hardness: (after 14 days of curing at room temperature)	86s	84s	79s	73s	76s
Chemical resistance: (according to DIN 68861 Part B) ethanol [1h]Water [9 days]	Good and good	Good and good	Good and good	Good and good	Good and good
						Cosolvent content of the coating	＜＜1％	＜＜1％	＜＜1％	＜＜1％	＜＜1％

The polyol dispersions (of examples 3, 4, 5, 6 and 7) were added to a dissolver and the additives described in table 4 and demineralized water were dispersed at about 5m/s for about 15 minutes. This gives dispersion batches of virtually unlimited storage stability.

These coatings were applied at a wet film thickness of 100 and 800 μm (corresponding to a dry film thickness of 40-320 μm) and dried to a tack-free film within 10-20 minutes. The curing process reaches full completion after 7-14 days.

The characteristic data collected in table 4 were used to measure the physical and chemical properties of the coating film.

TABLE 5: film-forming binders for clear sealants with polyol dispersions of examples 8 and 9

Composition (I)	Composition in parts by weight
			Component 1:
polyol Dispersion example 8	50.0	-.-
			Polyol Dispersion example 9	-.-	50.0
Acrysol ® RM 8 (5% aqueous solution) (1)	1.5	2.0
			Byk®025 (8)	0.7	0.7
Byk®348 (8)	0.2	0.2
			Byk®380 (8)	0.3	0.3
Water (softened)	15.0	15.0
			Deuteron®MK (6)	4.0	-.-
And (2) component:
			polyisocyanate 3	8.6	8.5
Worlee Add ® 575 (10% MPA solution) (9)	0.2	-.-
			Composition (wt%)
Binder	36.5	38.2
			Solids content	41.6	38.3
Water content	56.7	60.1
			Additive agent	1.7	1.6
Characteristic data:
			k ö nig pendulum bar hardness: (after 14 days of curing at room temperature)	99s	30s
Cosolvent content of the coating	＜＜1％	＜＜1％

The polyol dispersions (of examples 8 and 9) were added to a dissolver and the additives described in table 5 and demineralized water were dispersed at about 5m/s for about 15 minutes. This gives dispersion batches of virtually unlimited storage stability.

These coatings were applied at a wet film thickness of 100 and 240 μm (corresponding to a dry film thickness of 40-96 μm) and dried to a tack-free film within 10-20 minutes. The curing process reaches full completion after 7-14 days.

The characteristic data collected in table 5 were used to measure the physical and chemical properties of the coating film.

Manufacturer index:

(1)Acrysol®RM 8

rheological additives

Rohm& Haas Company

100 Independence Mall West，Philadelphia，PA 19 106-2399，USA

Tel.：00 1-2 15-5 92-30 00 Fax：00 1-2 15-5 92-33 77

www.rohmhaas.com

(2)Foamaster®306，Hydropalat140

Devolatilizing additives, levelling additives

Cognis GmbH

Henkelstraβe 67，40 589 Düsseldorf，Germany

Tel.：0049(0)21 1-79400 Fax：0049(0)211-7988567

www.cognis.com

(3)Baysilone®Lackadditive 3466

Levelling additives

Borchers GmbH

Alfred-Nobel-Straβe 50，40765 Monheim，Germany

Tel.：00 49(0)21 73-38 25 00 Fax：00 49(0)21 73-38 26 99

(4)Drewplus®T-4201

Devolatilizing additives

Ashland Chemical

One Drew Plaza，Boonton，N.J.07 00 5，USA

Tel.：00 1-97 3-26 37 600 Fax：00 1-97 3-26 33 32 3

www.ashland.com

(5)Ultralube®D-818/D-865

Wax

Keim Additec

Postfach 1204，55 478 Kirchberg/Hunsrück，Germany

Tel.：00 49(0)67 63-93 33 0 Fax：00 49(0)67 63-93 33 30

www.keim-additec.de

(6)Ceraflour®920

Matting agent

Byk Chemie

Abelstraβe 45，Postfach 10 02 45，46 462 Wesel，Germany

Tel.：00 49(0)28 1-67 00 Fax：00 49(0)28 1-65 73 5

www.byk-chemie.com

(7)Deuteron®MK

Matting agent

DEUTERON GmbH

In den Ellern 2，D-28832 Achim，Germany

Tel.：00 49(0)42 1-48 32 77 Fax：00 49(0)42 1-48 36 02

www.deuteron.com

(8)Byk®025，Byk®348，Byk®380

Devolatilizers, wetting additives, leveling additives

Byk Chemie

Abelstraβe45，Postfach 10 02 45，46 462 Wesel，Germany

Tel.：00 49(0)28 1-67 00 Fax：00 49(0)28 1-65 73 5

www.byk-chemie.com

(9)Worlee Add®575

Catalyst and process for preparing same

Worlée-Chemie GmbH

Grusonstr.22，22113 Hamburg，Germany

Tel.：00 49(0)40-7 33 33-0 Fax：00 49(0)40-7 33 33-296

Worlee-chemie@ch.worlee.de

Claims (11)

1. Process for preparing aqueous two-component polyurethane systems, characterized in that, in a first step, a polyol component a) formed from a hydrophobic core polymer having a glass transition temperature of 40 to 100 ℃ and a hydrophilic shell polymer having a glass transition temperature of-100 ℃ to +25 ℃ grafted thereon by aqueous emulsion polymerization is prepared, a hydroxyl-containing polyether component b) is added before, during or after the polymerization of component a), and then, in a second step, a polyisocyanate component c) is admixed.

2. The process for preparing aqueous two-component polyurethane systems according to claim 1, characterized in that no co-solvent is used.

3. A process according to claim 1 or 2, characterized in that the polyol component a) contains:

A)0.5 to 7% by weight of acrylic acid and/or methacrylic acid,

B)5-75 wt.% of methyl methacrylate and/or styrene,

C)3-40 wt.% of one or more C1-8 alkyl acrylates and/or C2-8 alkyl methacrylates,

D)2 to 74 wt.% of one or more monohydroxy-functional alkyl acrylates and/or monohydroxy-functional alkyl methacrylates,

E) from 0 to 30% by weight of other ethylenically unsaturated monomers,

the sum of the components is 100 wt%.

4. Process according to claim 1 or 2, characterized in that the polyether component b) is a polypropylene oxide polyol having a molecular weight of 300-4000 g/mol.

5. The process according to claim 1 or 2, characterized in that the polyisocyanate component c) has a viscosity of 5 to 12000 mPas.

6. The process according to claim 1 or 2, characterized in that components a), b) and c) are mixed by hand or by the action of a stirrer, the quantitative ratios being chosen so as to obtain an NCO/OH equivalent ratio of 0.2: 1 to 5: 1.

7. Aqueous two-component polyurethane system obtainable by the process according to one of claims 1 to 6.

8. Coating composition comprising an aqueous two-component polyurethane system according to claim 7.

9. Coating compositions according to claim 8, characterized in that they comprise an organic co-solvent content of less than 2% by weight.

10. A process for producing a coated substrate, characterized in that an aqueous two-component polyurethane system according to claim 7 is used as coating composition.

11. A substrate coated with a coating composition comprising an aqueous two-component polyurethane system according to claim 7.