DE19847077A1 - Polyether-modified polyisocyanate mixtures with improved water dispersibility - Google Patents

Abstract

The invention relates to polyether-modified, water-dispersible polyisocyanate mixtures, a process for their preparation and their use as a starting component in the production of polyurethane plastics, in particular as a crosslinking agent for water-soluble or -dispersible lacquer binders or binder components with groups which are reactive towards isocyanate groups.

Description

The invention relates to polyether-modified, water-dispersible polyisocyanate mix, a process for their preparation and their use as a source component in the production of polyurethane plastics, in particular as a crosslinker for water-soluble or -dispersible paint binders or -binder components ten with groups reactive towards isocyanate groups.

Water-dispersible polyisocyanate for various applications taking on importance.

Water-dispersible polyisocyanates play a special role as crosslinking agents components for water-dilutable two-component polyurethane (2K-PUR) coatings. In Combination with aqueous polyol dispersions allows the formulation to be dissolved medium-free paint systems that are already of high quality at room temperature Cure coatings that are resistant to solvents and chemicals strength or mechanical resilience in no way comparable to conventional paints stand (cf. e.g. EP-A 358 979, EP-A 469 389, EP-A 496 210, EP-A 542 105, EP-A 543 228, EP-A 562 282 EP-A 562 436, EP-A 583 728, DE-A 41 29 951, DE-A 42 26 242, DE-A 42 26 243 or DE-A 42 26 270).

Water-dispersible polyisocyanate preparations are also important as additives typesetting means z. B. for aqueous dispersion adhesives. With their help at for example the heat resistance and water resistance of bonds under significantly improve different materials (see e.g. EP-A 61 628 and EP-A 206 059).

Water-dispersible polyisocyanates are also used as crosslinkers Components for aqueous dispersions in textile finishing (EP-A 560 161 or  WO 95/30045) or in formaldehyde-free textile printing inks (EP-A 571 867 or DE-A 195 33 218) and are also suitable, for example, as auxiliaries for wet strengthening of paper (EP-A 564 912, EP-A 582 166, EP-A 707 113, WO 96/20309 and WO 97/04169).

In practice, all of these application areas have been non-ionic, with the help enforced by polyethers hydrophilically modified polyisocyanates. The production Such water-dispersible polyisocyanates are published in a number of described.

According to the teaching of DE-A 24 15 435, for example, urethanes are made of organi , especially aromatic polyisocyanates and at least 5 ethylene oxide units containing polyethylene glycol monoalkyl ethers surface-active sub punch the manufacture according to GB-PS 1 444 933 and DE-A 29 08 844 enable stable aqueous emulsions of aromatic polyisocyanates.

Aromatic modified hydrophilically by reaction with alkylene oxide polyethers Polyisocyanates are also known from EP-A 61 628 and 95 594. In the form of water These emulsions are used especially in the adhesive sector dung.

Water-dispersible preparations (cyclo) aliphatic polyisocyanates are e.g. B. known from EP-A 206 059. They contain reaction products as emulsifiers from polyisocyanates with mono- or polyhydric polyalkylene oxide alcohols, be consisting of at least one, having at least 10 ethylene oxide units Polyether chain, and also serve as additives for aqueous adhesives.

EP-A 516 277 describes the hydrophilization of special, tertiary-bonded iso Polyisocyanates containing cyanate groups by reaction with monovalent poly alkylene oxide polyethers and the use of these products as crosslinker compo nente for aqueous coating agents.  

For high-quality, lightfast coating applications, z. B. the in EP-B 540 985 and US-A 5 200 489, by urethanization aliphatic and / or cycloaliphatic lacquer polyisocyanates with short-chain, in statistical mean less than 10 ethylene oxide units polyethylene oxide polyether alcohols available polyisocyanate mixtures proven.

Also those from EP-A 645 410 and EP-A 680 983 as crosslinking agents for aqueous wood and Furniture varnishes known water-dispersible polyisocyanates based on 2,4 (6) -diisocyanatotoluene (TDI) or mixtures of TDI and 1,6-diisocyanato Hexane (HDI) contain urethanes made of polyisocyanate and as hydrophilic components monofunctional polyethylene oxide polyether alcohols.

In addition to these purely non-ionically hydrophilized, containing polyether urethanes Polyisocyanates are also polyether-modified water-dispersible polyiso cyanate known to improve emulsifiability or to achieve special effects additionally ionic groups, for example sulfonate groups (cf. e.g. EP 703 255) or amino or ammonium groups (cf. e.g. EP-A 582 166 and EP-A 707 113). Such ionically / nonionically modified Polyisocyanates are generally less suitable for paint applications. she come preferably in environmentally friendly textile equipment or as paper wet strength agent for use.

Despite their wide range of applications, the polyether urethane modifi adorned a series of water-dispersible polyisocyanates of the prior art fundamental disadvantages. So the water-dispersible polyisocyanates, those using higher molecular weight polyether alcohols (e.g. in the case pure polyethylene oxide polyether from an average molecular weight of approx. 700) were produced due to a very high level during the dispersion overcoming viscosity maximums often only by using considerable ones Shear forces (e.g. high-speed stirrer) homogeneously into aqueous media  work. In addition, such products, especially at high emulsifier contents, tend how to achieve particularly fine-particle, sedimentation-stable dispersions are often required for crystallization.

In contrast, shorter polyether chains can be used to disperse water Obtain bare polyisocyanates that are very easy to stabilize by hand Allow dispersions to be stirred into water and even with high hydrophilization degrees, d. H. at high levels of ethylene oxide units, no crystallization show tendency. Due to the relatively low molecular weight of the Modifi However, the polyalkylene oxide polyether used for the decoration increases with the degree of hydrophilization both the content of isocyanate groups and the mean isocyanate functionality decreases steadily. In practice, however, for the majority of above-mentioned fields of application, for example as crosslinker components for Varnishes and coatings, especially highly hydrophilized to emul particularly fine gating polyisocyanates with high NCO contents and the highest possible functionality naturality desired.

The object of the present invention was therefore to develop new water-dispersible poly to provide isocyanate mixtures for use in the above mentioned application areas of hydrophilic polyisocyanates, especially as Aus aisle components for the production of polyurethane plastics and especially as Crosslinker for aqueous binders or binder components in Beschich tion systems are suitable without having the disadvantages of the water disper prior art polyisocyanates to be afflicted.

This object was achieved with the polyisocyanate mixtures according to the invention or the Process for their preparation to be solved. The polyisocya according to the invention natural mixtures are based on the surprising observation that the implementation mo Low-nomene polyisocya consisting of at least two diisocyanate molecules nate with monofunctional polyethylene oxide polyether alcohols under Allophanati conditions of water-dispersible polyisocyanate mixtures  considerably lighter and finer even at significantly lower degrees of hydrophilization Allow more stirring in aqueous systems than using identical poly Water-dispersible polyisocyanates of the prior art produced by ether alcohols Technology in which the polyether chains are linked to the polyiso via urethane bonds cyanate are linked.

The method according to the invention allows the production of crystallization-stable hy drophilic polyisocyanates that differ from the previously known polyether chains containing polyisocyanate mixtures with the same or even better water disperser Greedability due to a higher content of isocyanate groups and a higher radio distinguish functionality.

Although in some publications that ent the manufacture of allophanate groups holding polyisocyanates to the subject, for example in the EP-A 000 194, EP-A 303 150, EP-A 682 012, US-PS 5 380 792 or US-PS 5 086 175, as possible alcoholic starting compounds for the production of such products too the usual polyether alcohols are mentioned and in addition in EP-A 000 194, EP-A 303 150 and EP-A 682 012 within long lists of suitable starting materials cyanates also polyisocyanates with a functionality <2, such as. B. Trimerization products of HDI or 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), to be mentioned blanketly, the skilled worker could not do any of the above Publications take any concrete reference to the fact that under Allophanatization conditions produced reaction products low in monomers Polyisocyanates with monofunctional polyethylene oxide polyether alcohols considerably lighter and more finely divided into stable emulsions in water than poly isocyanate mixtures of the same gross composition, which according to the ver driving the prior art were produced under urethanization.

The present invention relates to water-dispersible polyisocyanate mixtures based on aliphatic, cycloaliphatic, araliphatic and / or aromatic diisocyanates

• a) an average isocyanate functionality of at least 2.0,
• b) a content of isocyanate groups (calculated as NCO; molecular weight = 42) from 5.0 to 25.0% by weight and
• c) a content of ethylene oxide units bound within polyether chains (calculated as C ₂ H ₂ O; molecular weight = 44) of 2 to 50% by weight, the polyether chains containing on average 5 to 35 ethylene oxide units,

characterized in that the polyether chains at least 60 mol% over Allo phanate groups each with two, each made up of at least two diisocyanates built polyisocyanate molecules are linked.

The invention also relates to a process for the preparation of these water-dispersible polyisocyanate mixtures, characterized in that

• A) a polyisocyanate component with an (average) NCO functionality of 2.0 to 5.0, containing aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups (calculated as NCO; Molecular weight = 42) from 8.0 to 27.0% by weight and containing monomeric diisocyanates of less than 1 wt .-% with
• B) a monovalent, on average from 5 to 35 ethylene oxide units containing polyalkylene oxide polyether alcohol

while maintaining an NCO / OH equivalent ratio of 6: 1 to 400: 1 as above reacted with one another that at least 60% of the primary ge by NCO / OH reaction formed urethane groups to react further to allophanate groups, the amounts ratios of the starting compounds mentioned are chosen so that the resul  The reaction products ent ent the conditions mentioned under a) to c) speak.

The invention also relates to the use of these polyisocyanate mixtures as starting components in the production of polyurethane plastics.

Finally, the use of these polyisocyanate mixtures is also an object Crosslinker for water-soluble or water-dispersible lacquer binders or lacquer binders agent components in the manufacture of coatings using aq coating agents based on such binders or binder compo nenten.

Component A) to be used in the method according to the invention has one (Average) NCO functionality from 2.0 to 5.0, preferably from 2.3 to 4.5, one Isocyanate group content of 8.0 to 27.0% by weight, preferably 14.0 to 24.0 wt .-% and a content of monomeric diisocyanates of less than 1% by weight, preferably less than 0.5% by weight. It consists of at least an organic polyisocyanate with aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups.

The polyisocyanate part or polyisocyanate mixtures from Kompo nente A) around any, by modification simple aliphatic, cycloalipha table, araliphatic and / or aromatic diisocyanates made from min at least two diisocyanates made up of polyisocyanates with uretdione, isocyanurate, Allophanate, biuret, iminooxadiazinedione and / or oxadiazinetrione structure as they for example in J. Prakt. Chem. 336 (1994) 185-200, DE-A 16 70 666, 19 54 093, 24 14 413, 24 52 532, 26 41 380, 37 00 209, 39 00 053 and 39 28 503 or EP-A 336 205, 339 396 and 798 299 are described by way of example.

Suitable diisocyanates for the production of such polyisocyanates are arbitrary Phosgenation or by phosgene-free processes, for example by thermal  Urethane cleavage, accessible diisocyanates in the molecular weight range 140 to 400 with aliphatic, cycloaliphatic, araliphatic and / or aromatically bound Isocyanate groups, such as. B. 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 2-methyl-1,5-diisocyanatopentane, 1,5-diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and 1,4-diiso cyanatocyclohexane, 1,3- and 1,4-bis (isocyanatomethyl) cyclohexane, 1-isocyanato 3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI), 4,4'- Diisocyanatodicyclohexylmethane, 1-isocyanato-1-methyl-4 (3) isocyanatomethyl cyclohexane, bis (isocyanatomethyl) norbornane, 1,3- and 1,4-bis (2-isocyanato-prop- 2-yl) benzene (TMXDI), 2,4- and 2,6-diisocyanatotoluene (TDI), 2,4'- and 4,4'-di isocyanatodiphenylmethane, 1,5-diisocyanatonaphthalene or any mixture such diisocyanates.

The starting components A) are preferably polyisocyanates or Polyisocyanate mixtures of the type mentioned with only aliphatic and / or cycloaliphatically bound isocyanate groups.

Very particularly preferred starting components A) are polyisocyanates or Polyisocyanate mixtures with an isocyanurate structure based on HDI, IPDI and / or 4,4'-diisocyanatodicyclohexylmethane.

Component B) is a monovalent, on average 5 to 35, preferably 7 to 30 ethylene oxide units per molecule having polyalky lenoxidpolyether alcohols, such as those known per se by alkoxylation suitable starter molecules are accessible (see e.g. Ullmanns Encyclopedia of technical chemistry, 4th edition, volume 19, Verlag Chemie, Weinheim p. 31-38) or any mixture of such polyether alcohols.

As suitable starter molecules for the production of the ver polyether alcohols B) used are examples: saturated Monoalcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, iso  butanol, sec-butanol, the isomeric pentanols, hexanols, octanols and nonanols, n- Decanol, n-dedecanol, n-itendecanol, n-hexadecanol, n-octadecanol, cyclo hexanol, the isomeric methylcyclohexanols or hydroxymethylcyclohexane, 3- Ethyl 3-hydroxymethyloxetane or tetrahydrofurfuryl alcohol; unsaturated alcohols such as allyl alcohol, 1,1-dimethyl-allyl alcohol or oleic alcohol, aromatic alcohols like phenol, the isomeric cresols or methoxyphenols, araliphatic Alcohols such as benzyl alcohol, anise alcohol or cinnamon alcohol; secondary monoamines such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, Diisobutylamine, bis (2-ethylhexyl) amine, N-methyl and N-ethylcyclohexylamine or dicyclohexylamine and heterocyclic secondary amines such as morpholine, Pyrrolidine, piperidine or 1H-pyrazole.

Preferred starter molecules are saturated monoalcohols with up to 4 carbon atoms. Methanol is particularly preferably used as the starter molecule.

Alkylene oxides suitable for the alkoxylation reaction are, in particular, ethylene oxide and propylene oxide, in any order or in a mixture at the Alkoxylation reaction can be used.

The polyalkylene oxide polyether alcohols B) are either pure Polyethylene oxide polyethers or mixed polyalkylene oxide polyethers, their alkylene oxide units of at least 30 mol%, preferably at least 40 mol% Ethylene oxide units exist.

Preferred starting components B) for the process according to the invention are pure polyethylene glycol monomethyl ether alcohols, the statistical average 7 to 30, very particularly preferably 7 to 25 ethylene oxide units.

If necessary, in addition to the ge mentioned polyether alcohols B) in minor amounts compared to others Isocyanate reactive compounds with anionic or cationic groups  for example with carboxylate, sulfonate or ammonium groups, as a hydrophilic construction components are also used.

The starting compo ment A) and B) at temperatures from 40 to 180 ° C, preferably 50 to 150 ° C, while maintaining an NCO / OH equivalent ratio of 6: 1 to 400: 1 preferably from 8: 1 to 140: 1, reacted with one another such that at least 60 mol%, preferably at least 80 mol%, particularly preferably at least 90 mol% of the urethane groups formed primarily by NCO / OH reaction to form allophanate groups continue to react.

In order to accelerate the allophanatization reaction in the Invention If appropriate, suitable catalysts can also be used in accordance with the process. These are the usual known allophanatization catalysts, for example, metal carboxylates, metal chelates or tertiary amines in the GB-A 994 890 describes alkylating agents of the type described in US-A 3,769,318 described type or strong acids, as exemplified in EP-A 000 194 are described.

Suitable allophanatization catalysts are, in particular, zinc compounds, such as B. zinc (II) stearate, zinc (II) n-octanoate, zinc (II) -2-ethyl-1-hexanoate, zinc (II) naphthenate or zinc (II) acetylacetonate, tin compounds, such as. B. Tin (II) - n-octanoate, tin (II) -2-ethyl-1-hexanoate, tin (II) laurate, dibutyltin oxide, dibutyl tin dichloride, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dimaleate or Dioctyltin diacetate, aluminum tri (ethylacetoacetate), iron (III) chloride, potassium octoate, manganese cobalt or nickel compounds and strong acids such as B. Tri fluoroacetic acid, sulfuric acid, hydrogen chloride, hydrogen bromide, phosphoric acid or perchloric acid, or any mixture of these catalysts.

Suitable, albeit less preferred, catalysts for the present invention Procedures are also those compounds that are in addition to the allophanatization craze  tion also trimerization of isocyanate groups to form isocyanurate catalyze structures. Such catalysts are for example in the EP-A 649 866 page 4, line 7 to page 5, line 15.

Preferred catalysts for the process according to the invention are zinc compounds gene of the above-mentioned type. The use of zinc (II) n-octanoate, zinc (II) -2-ethyl-1-hexanoate and / or zinc (II) stearate.

These catalysts may be used in the process according to the invention an amount of 0.001 to 5% by weight, preferably 0.005 to 1% by weight on the total weight of the reactants.

The addition to the reaction mixture can be carried out by any method. For example, it is possible to use the catalyst that may be used either the polyisocyanate component A) and / or the polyether component B) mix in before the actual implementation begins. It is also possible to Catalyst the reaction mixture at any time during the Urethanization reaction or in the sense of a two-stage reaction procedure following urethanization, d. H. if a full turnover of Isocyanate and hydroxyl groups theoretically corresponding NCO content is reached, to add.

The course of the reaction in the method according to the invention by z. B. titrimetric determination of the NCO content can be followed. After reaching the desired NCO content, preferably if the molar ratio of Allo phanate groups to urethane groups in the reaction mixture at least 4: 1, especially preferably at least 9: 1, the reaction is stopped. This can happen with purely thermal reaction control, for example by cooling the reaction mixtures take place at room temperature. If you prefer to use one Allophanatization catalyst of the type mentioned is the implementation in general  mean by adding suitable catalyst poisons, for example acid chlorides such as benzoyl chloride or isophthaloyl dichloride.

Otherwise, the quantitative ratios of the Starting components selected in the context of the information provided so that the right resulting polyisocyanate mixtures the information given under a) to c) above correspond, where a) the average NCO functionality is preferably 2.3 to 9.9, particularly preferably 2.8 to 5.8, b) the NCO content preferably 6.0 to 22.5 % By weight, particularly preferably 8.5 to 21.5% by weight and c) the content of inside of ethylene oxide units bound by polyether chains, preferably 5 to 40 % By weight, particularly preferably 7 to 25% by weight.

The statements made with regard to the NCO functionality of the process products according to the invention relate to the value which arithmetically results from the type and functionality of the starting components according to the formula

lets determine in which x the proportion of the urethane groups converted to allophanate groups in the process according to the invention. The functionality f _{NCO of} the starting _{polyisocyanates} A) can be calculated from the NCO content and, for example, molecular weight determined by gel permeation chromatography (GPC) or vapor pressure osmosis.

If appropriate, the process according to the invention can be carried out in a suitable, counter be carried out over isocyanate-inert solvents. Suitable ransom medium are, for example, the conventional paint solvents known per se, such as. B. Ethyl acetate, butyl acetate, ethylene glycol monomethyl or ethyl ether acetate, 1-  Methoxypropyl-2-acetate, 3-methoxy-n-butyl acetate, acetone, 2-butanone, 4-methyl-2- pentanone, cyclohexanone, toluene, xylene, chlorobenzene, white spirit, more highly substituted Aromatics, such as those under the names Solventnaphtha®, Sol vesso®, Shellsol®, Isopar®, Nappar® and Diasol® are on the market, are carbonic acid esters, such as dimethyl carbonate, diethyl carbonate, 1,2-ethylene carbonate and 1,2-propylene carbonate, lactones such as β-propiolactone, γ-butyrolactone, ε-caprolactone and ε-methyl caprolactone, but also solvents such as propylene glycol diacetate, diethylene glycol di melthyl ether, dipropylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether acetate, N-methylpyrrolidone and N-methylcaprolactam, or any mixture such solvents.

The process products according to the invention are clear, practically colorless poly isocyanate mixtures that are easy to use without using high shear forces Allow stirring to disperse in water, to obtain sedimentation stable aqueous dispersions with a given composition and molecular weight distribution of the polyether segments already a significantly lower total stop at ethylene oxide units is sufficient than in the case of water-dispersible poly Isocyanate mixtures of the prior art, which by urethanization with poly ether alcohols of the same composition and molecular weight distribution were manufactured. The method according to the invention thus allows production crystallization-stable, highly hydrophilic polyisocyanates, which are different from the Previously known polyisocyanate mixtures containing polyether urethanes same or even better water dispersibility due to a higher content Characterize isocyanate groups and a higher functionality.

The excellent dispersibility even at low ethylene oxide contents in Combination with high NCO contents and functionalities is particularly important for the use of the polyisocyanate mixtures according to the invention in aqueous 2K PUR lacquers are an advantage, because in this way highly cross-linked coating can be obtained in addition to very good solvent and chemical resistance  due to the low content of hydrophilic groups have excellent water resistance.

If appropriate, the polyisocyanate mixtures according to the invention can be mixed with other non-hydrophilized polyisocyanates, in particular lacquer polyisocyanates of the type mentioned above, before emulsification. The proportions are preferably chosen so that the resulting polyiso cyanate mixtures correspond to the conditions mentioned under a) to c) above and thus likewise represent polyisocyanate mixtures according to the invention, since these generally consist of mixtures

• (i) polyisocyanates modified according to the invention and
• (ii) there are unmodified polyisocyanates of the type mentioned by way of example.

In such mixtures, the process products according to the invention take over Function of an emulsifier for the subsequently mixed portion of non-hydro phile polyisocyanates.

The polyisocyanate mixtures according to the invention are valuable starting materials materials for the production of polyurethane plastics according to the isocyanate Polyaddition method.

For this purpose, the polyisocyanate mixtures are preferably in the form of aqueous emulsions NEN used in combination with water-dispersed polyhydroxyl in the sense of aqueous two-component systems for implementation ge can be brought.

The polyisocyanate mixtures according to the invention are particularly preferred as Ver wetting agent for paint binders or paint binders dissolved or dispersed in water Components with groups reactive towards isocyanate groups, in particular their alcoholic hydroxyl groups, in the manufacture of coatings under  Use of aqueous coating compositions based on such binders or binder components used. The association of the crosslinker, given otherwise in emulsified form, with the binders or binder components can be done by simply stirring before processing the coating medium by any method or also using two-component ten spray guns.

In this context, as a paint binder or paint binder compo Examples mentioned: hydroxyl groups dissolved or dispersed in water polyacrylates, in particular those of the molecular weight range 1000 up to 10,000, the valuable two-component with organic polyisocyanates as crosslinkers represent component binders or dispersed in water, if appropriate Urethane-modified, hydroxyl-containing polyester resins from the Polyester and alkyd resin chemistry known type. In principle, are as reactants for the polyisocyanate mixtures according to the invention all dissolved in water or dispersed binders which have groups reactive toward isocyanates, suitable. These include, for example, polyurethanes dispersed in water or polyureas, which are present in the urethane or urea groups lying active hydrogen atoms can be crosslinked with polyisocyanates.

In the use according to the invention as a crosslinking component for aqueous The polyisocyanate mixtures according to the invention are generally paint binders mean used in such amounts that an equivalent ratio of NCO Groups to groups which are reactive towards NCO groups, in particular alcoholic hydroxyl groups, from 0.5: 1 to 2: 1, correspond.

If appropriate, the polyisocyanate mixtures according to the invention can be found in below ordered quantities of non-functional aqueous paint binders to achieve very special properties, for example as an additive to improve adhesion be mixed.  

The polyisocyanate mixtures according to the invention can of course also be used in with blocking agents known per se from polyurethane chemistry Form in combination with the above-mentioned aqueous paint binders or Paint binder components in the sense of aqueous one-component PUR Stoving systems are used. Suitable blocking agents are examples as diethyl malonate, acetoacetic ester, acetone oxime, butanone oxime, ε-capro lactam, 3,5-dimethylpyrazole, 1,2,4-triazole, dimethyl-1,2,4-triazole, imidazole or any mixtures of these blocking agents.

As substrates for the polyisocyanate mixtures according to the invention Formulated aqueous coatings can be any substrate, such as e.g. B. metal, wood, glass, stone, ceramic materials, concrete, hard and flexible Plastics, textiles, leather and paper, if necessary, before coating can also be provided with conventional primers.

In general, they have with the polyisocyanate mixtures according to the invention formulated aqueous coating compositions, which may be those on the paint industry-standard auxiliaries and additives, such as. B. flow aids, color pigments, Fillers, matting agents or emulsifiers that can be incorporated, yes good drying properties when dried at room temperature.

Of course, they can also be used under forced conditions Dry at elevated temperature or by baking at temperatures up to 260 ° C.

Due to their excellent water emulsifiability, which is a homogeneous, enables particularly fine-particle distribution in aqueous paint binders Use of the polyisocyanate mixtures according to the invention as crosslinking agent component for aqueous polyurethane paints to coatings with excellent optical properties, especially high surface gloss, flow and high Transparency.  

In addition to the preferred use as crosslinker components for aqueous 2K The polyisocyanate mixtures according to the invention are particularly suitable for PUR coatings excellent as a crosslinker for aqueous dispersion adhesives, leather and textile coatings tions or textile printing pastes, as AOX-free paper auxiliaries or as additives Substitute for mineral building materials, such as concrete or mortar.

Examples

The term "degree of allophanatization" in the following denotes that from the NCO Calculable percentage of the proportion of allophanate groups converted urethane groups formed from polyether alcohol and polyisocyanate. The rest Percentages refer to the weight.

example 1

900 g (4.65 eq) of an isocyanurate group-containing polyisocyanate based on 1,6-diisocyanatohexane (HDI) with an NCO content of 21.7%, an average NCO functionality of 3.5 (according to GPC), one The monomeric HDI content of 0.1% and a viscosity of 3000 mPa.s (23 ° C) are introduced at 100 ° C under dry nitrogen and stirring, within 30 min with 100 g (0.29 eq) Methanol started, monofunctional polyethylene oxide polyether with an average molecular weight of 350, corresponding to an NCO / OH equivalent ratio of 16: 1, added and then stirred at this temperature until the NCO content of the mixture after about 2 h to a value corresponding to complete urethanization fell from 18.3%. The allophanatization reaction is started by adding 0.01 g of zinc (II) -2-ethyl-1-hexanoate. The temperature of the reaction mixture rises to 106 ° C. due to the heat of reaction released. After the exotherm subsided, about 30 minutes after the addition of catalyst, the reaction was stopped by adding 0.01 g of benzoyl chloride and the reaction mixture was cooled to room temperature. There is a practically colorless, clear polyisocyanate mixture according to the invention with the following characteristics:

Fixed salary: 100%
NCO content: 17.2%
NCO functionality: 3.9
Viscosity (23 ° C): 3200 mPa.s
Ethylene oxide content: 9.1%
Degree of allophanatization: 92%.

Example 2

870 g (4.81 eq) of a polyisocyanate containing isocyanurate groups and based on HDI with an NCO content of 23.2%, an average NCO functionality of 3.2 (according to GPC) and a content of monomeric HDI of 0, 2% and a viscosity of 1200 mPa.s (23 ° C) are placed at 100 ° C under dry nitrogen and stirring, within 30 min with 130 g (0.26 val) of a monofunctional polyethylene oxide polyether started on methanol Molecular weight of 500, corresponding to an NCO / OH equivalent ratio of 18.5: 1, added and then stirred further at this temperature until the NCO content of the mixture fell after 19 h to a value corresponding to complete urethanization of 19.1% is. The allophanatization reaction is started by adding 0.01 g of zinc (II) -2-ethyl-1-hexanoate. The temperature of the reaction mixture rises to 109 ° C. due to the heat of reaction released. After the exothermic reaction has subsided, about 20 minutes after the addition of catalyst, the reaction is terminated by adding 0.01 g of benzoyl chloride and the reaction mixture is cooled to room temperature. There is a colorless, clear polyisocyanate mixture according to the invention with the following characteristics:

Fixed salary: 100%
NCO content: 18.0%
NCO functionality: 3.5
Viscosity (23 ° C): 1400 mPa.s
Ethylene oxide content: 12.2%
Degree of allophanatization: 100%.

Example 3

890 g (2.52 eq) of a 70% isocyanurate group-containing polyisocyanate based on 1-isocyanato-3,3,5-trimethyl-5-isocyanato methylcyclohexane (IPDI) with an NCO content of 11.9 %, an average NCO functionality of 3.3 (according to GPC), a content of monomeric IPDI of 0.2% and a viscosity of 650 mPa.s (23 ° C.) together with a further 47.1 g of butyl acetate at 100 ° C submitted under dry nitrogen and stirring, within 30 min with 110 g (0.22 eq) of a monofunctional polyethylene oxide polyether started on methanol with an average molecular weight of 500, corresponding to an NCO / OH equivalent ratio of 11.5: 1, added and then stirred further at this temperature until after about 2.5 h the NCO content of the mixture has dropped to the value of 9.7% corresponding to complete urethanization. The allophanatization reaction is started by adding 0.02 g of zinc (II) stearate. The temperature of the reaction mixture rises to 105 ° C. due to the heat of reaction released. After the exothermic reaction has subsided, about 1 h after the addition of catalyst, the reaction is stopped by adding 0.01 g of benzoyl chloride and the reaction mixture is cooled to room temperature. There is a clear colorless solution of a polyiso cyanate mixture according to the invention with the following characteristics:

Fixed salary: 70%
NCO content: 8.9%
NCO functionality: 3.8
Viscosity (23 ° C): 700 mPa.s
Ethylene oxide content: 9.8%
Degree of allophanatization: 80%.

Example 4

850 g (2.00 eq) of a 60% isocyanurate group-containing polyisocyanate containing aromatic and aliphatic bound NCO groups based on 2,4- or 2,6-diisocyanatotoluene (TDI) and HDI in the ratio of 2: 1 with an NCO content of 9.9 0/0, an average NCO functionality of 4.5 (according to GPC), a total content of monomeric diisocyanates (TDI and HDI) of 0.2% and a viscosity of 2400 mPa.s (23 ° C) are presented together with a further 46.7 g of butyl acetate at 100 ° C under dry nitrogen and stirring, within 30 minutes with 70 g (0.14 val) of a monofunctional polyethylene oxide polyether started on methanol an average molecular weight of 500, corresponding to an NCO / OH equivalent ratio of 14.3: 1, and then stirred further at this temperature until the NCO content of the mixture after about 1 h to a value of 8 corresponding to complete urethanization , 1% has fallen. The allophanation reaction is started by adding 0.01 g of zinc (II) -2-ethyl-1-hexanoate. The temperature of the reaction mixture rises to 109 ° C. due to the heat of reaction released. After the exothermic reaction has subsided, about 20 minutes after the catalyst has been added, the reaction is terminated by adding 0.01 g of benzoyl chloride and the reaction mixture is cooled to room temperature. There is a clear colorless solution of a polyisocyanate mixture according to the invention with the following characteristics:

Fixed salary: 60%
NCO content: 7.6%
NCO functionality: 5.6
Viscosity (23 ° C): 2600 mPa.s
Ethylene oxide content: 6.8%
Degree of allophanatization: 83%.

Example 5 (comparison, analogous to EP-B 540 985, exemplary embodiments)

900 g (4.65 eq) of the isocyanurate group-containing poly isocyanate based on HDI described in Example 1 are placed at 100 ° C. under dry nitrogen and stirring, within 30 min with 100 g (0.29 eq) of the in Example 1 be described polyether alcohol added and stirred at this temperature until the NCO content of the mixture has dropped to about 18 h to a value corresponding to a complete urethane. After cooling to room temperature, there is a colorless, clear polyisocyanate mixture with the following characteristics:

Fixed salary: 100%
NCO content: 18.3%
NCO functionality: 3.3
Viscosity (23 ° C): 3100 mPa.s
Ethylene oxide content: 9.1%
Degree of allophanatization: 0%.

Example 6 (comparison, analogous to EP-B 540 985, exemplary embodiments)

860 g (4.44 eq) of the isocyanurate group-containing polyisocyanate based on HDI described in Example 1 are initially introduced at 100 ° C. under dry nitrogen and with stirring, within 30 min with 140 g (0.40 eq) of the in Example 1 The polyether alcohol described is added and stirring is continued at this temperature until the NCO content of the mixture has dropped to 16.8%, corresponding to complete urethanization, after about 2 hours. After cooling to room temperature, there is a colorless, clear polyisocyanate mixture with the following characteristics:

Fixed salary: 100%
NCO content: 16.8%
NCO functionality: 3.2
Viscosity (23 ° C): 3200 mPa.s
Ethylene oxide content: 12.7%
Degree of allophanatization: 0%.

Example 7 (Preparation of Emulsions)

75 g of the polyisocyanate mixture according to the invention from Example 1 are in one Erlenmeyer flask mixed with 175 g of deionized water and gently stirred by hand into a fine, bluish emulsion. The emulsion is after a standing time of 24 h still stable and shows no precipitation or Sediment.

For comparison, 75 g of the polyisocyanate mixture from Example 5 are combined in one Erlenmeyer flask mixed with 175 g of deionized water and 5 min on the Mag stirred with 900 U / min. This creates higher shear despite the application forces only a very coarse-grained, only slightly stable emulsion that already contains has formed a thick white sediment after a standing time of 2 h.

The comparison shows that the polyisocyanate mixture produced according to the invention is composed of Example 1 compared to one produced according to the teaching of EP-B 540 985 Polyisocyanate mixture of the same gross composition, in which the polyether chains are linked to the polyisocyanate exclusively via urethane bonds, one  significantly better dispersibility and at the same time higher NCO functionality having.

Example 8

100 parts by weight of an aqueous, cosolvent-free, hydroxy-functional polyacrylate dispersion with a solids content of 43% and an OH content of 2.5%, based on solid resin, consisting essentially of 48.0% methyl methacrylate, 27.4 % n-butyl acrylate, 21.6% hydroxy-C ₃ -alkyl methacrylate (adduct of propylene oxide with methacrylic acid) and 3.0% acrylic acid are mixed with 0.5 part by weight of a commercially available defoamer (Foamaster TCX, Henkel). The preparation has an unlimited shelf life.

15.5 parts by weight of the poly according to the invention are used in the above-mentioned approach isocyanates from Example 1 to (corresponding to an equivalent ratio of Iso cyanate groups to alcoholic hydroxyl groups of 1: 1) and homogenized by intensive stirring (2000 rpm). Then the solids content adjusted to 40% by adding water.

The processing time of the ready-to-use, i.e. mixed, batch is approx. 3 hours. The film applied in a wet film thickness of 150 µm (approx. 60 µm dry) appears almost transparent with a slightly yellowish shimmer immediately after application (Tyndall effect). At room temperature, the time to dust drying is less than 30 minutes, to pressure drying approx. 1 to 1.5 hours. A second identical film winding was dried under forced conditions (30 min / 60 ° C). A high-gloss, completely clear and transparent lacquer film is obtained with the following properties:

For comparison, 100 parts by weight of the hydroxyfunk described above tional polyacrylate dispersion and 15.8 parts by weight of the polyisocyanate EP-B 540 985 from Example 6 (corresponding to an equivalent ratio of Iso cyanate groups to alcoholic hydroxyl groups of 1: 1) according to the above the procedure described a varnish.

The processing time of the ready-to-use approach is approx. 3 hours. The film applied in a wet film thickness of 150 µm (approx. 60 µm dry) appears milky white immediately after application. At room temperature, the time to dust drying is approx. 1 hour, to pressure drying approx. 2 to 3 hours. An analog film produced was dried under forced conditions (30 min / 60 ° C). In both cases you get slightly cloudy paint films with the following properties:

The comparison shows that the polyisocyanate produced according to the invention consists of Example 1 with a lower content of hydrophilic ethylene oxide units has better dispersibility than one made from the same raw materials water-dispersible polyisocyanate of the prior art (Example 6) and consequently provides completely transparent paint films. Due to the higher NCO Ge halt and in particular the higher functionality of the poly according to the invention Isocyanates also show the lacquer films obtained with them considerably higher resistance to solvents and water.

Example 9

100 parts by weight of an aqueous, cosolvent-free, hydroxy-functional polyacrylate dispersion with a solids content of 44% and an OH content of 3.0%, based on solid resin, consisting essentially of 44.9% methyl methacrylate, 26.1% n-Butyl acrylate, 25.9% hydroxy-C ₃ -alkyl methacrylate (adduct of propylene oxide with methacrylic acid and 3.1% acrylic acid) are mixed with 0.5 part by weight of a commercially available defoamer (Foamaster TCX, Henkel). The preparation is unlimited storage stability.

The above approach is 22.7 parts by weight of an 80% solution of Polyisocyanates according to the invention from Example 2 in dipropylene glycol dimethyl ether too (corresponding to an equivalent ratio of isocyanate groups to alcohol hydroxyl groups of 1: 1) and homogenized by intensive stirring (2000 rpm). Then a solid content is obtained by adding water of 40% by weight.

The processing time of the ready-to-use, i.e. mixed, batch is approx. 3 hours. The film applied in a wet film thickness of 150 µm (approx. 60 µm dry) appears almost transparent with a slightly yellowish shimmer immediately after application (Tyndall effect). At room temperature, the time to dust drying is approx. 1 hour, to pressure drying approx. 2 to 3 hours. A second same film lift was dried under forced conditions (30 min / 60 ° C). In both cases, you get a high-gloss, completely clear and transparent paint film with the following properties:

Claims (13)

1. Water-dispersible polyisocyanate mixtures based on aliphatic, cyclo aliphatic, araliphatic and / or aromatic diisocyanates

• a) an average isocyanate functionality of at least 2.0
• b) a content of isocyanate groups (calculated as NCO; molecular weight = 42) from 5.0 to 25.0% by weight and
• c) a content of ethylene oxide units bound within polyether chains (calculated as C ₂ H ₂ O; molecular weight = 44) of 2 to 50% by weight, the polyether chains containing on average 5 to 35 ethylene oxide units,

characterized in that the polyether chains are linked to at least 60 mol% via allophanate groups with two polyisocyanate molecules each composed of at least two diisocyanates. 2. Water-dispersible polyisocyanate mixtures based on aliphatic and / or cycloaliphatic diisocyanates

• a) an average isocyanate functionality of 2.3 to 9.9,
• b) a content of isocyanate groups (calculated as NCO; molecular weight = 42) from 6.0 to 22.5% by weight and
• c) a content of ethylene oxide units bound within polyether chains (calculated as C ₂ H ₂ O; molecular weight = 44) of 5 to 40% by weight, the polyether chains containing on average 7 to 30 ethylene oxide units,

characterized in that the polyether chains are linked to more than 60 mol% via allophanate groups with two polyisocyanate molecules each composed of at least two diisocyanates. 3. Water-dispersible polyisocyanate mixtures according to claim 1, characterized ge indicates that the polyether chains to more than 60 mol% over allophanate groups each with two isocyanurate polyisocyanate molecules are linked. 4. Water-dispersible polyisocyanate mixtures according to claim 1, characterized ge indicates that the polyether chains to more than 80 mol% over allophanate groups each with two isocyanurate polyisocyanate molecules with exclusively aliphatic and / or cycloaliphatic bound which isocyanate groups are linked. 5. A process for the preparation of water-dispersible Polyisocyanatge mix according to claim 1, characterized in that

• A) a polyisocyanate component with an average functionality of 2.0 to 5.0, containing aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups (calculated as NCO; molecular weight = 42) from 8.0 to 27.0% by weight .-% and a content of monomeric diisocyanates of less than 1 wt .-%
• B) a monovalent polyalkylene oxide polyether alcohol which has a statistical average of 5 to 35 ethylene oxide units

while maintaining an NCO / OH equivalent ratio of 6: 1 to 400: 1 so that at least 60% of the urethane groups primarily formed by the NCO / OH reaction continue to react to allophanate groups, the proportions of the starting compounds mentioned being chosen so that the resulting reaction products correspond to the conditions mentioned in claim 1 under a) to c). 6. The method according to claim 5, characterized in that one

• A) a polyisocyanate component with an average functionality of 2.3 to 4.5, containing aliphatic and / or cycloaliphatic bound isocyanate groups (calculated as NCO; molecular weight = 42) from 14.0 to 24.0% by weight and a content of monomeric diisocyanates of less than 0.5 wt .-%
• B) a monovalent polyalkylene oxide polyether alcohol which has a statistical average of 7 to 30 ethylene oxide units

while maintaining an NCO / OH equivalent ratio of 8: 1 to 140: 1 so that at least 60% of the urethane groups primarily formed by NCO / OH reaction continue to react to allophanate groups, the proportions of the starting compounds mentioned being selected so that the resulting reaction products correspond to the conditions mentioned in claim 2 under a) to c). 7. The method according to claim 5, characterized in that as a polyiso cyanate component A) isocyanurate polyisocyanate based on 1,6-diisocyanatohexane, 1-isocyanato-3,3,5-trimethyl-5-iso cyanatomethylcyclohexane and / or 4,4'-diisocyanatodicyclohexylmethane starts. 8. The method according to claim 5, characterized in that the implementation in the presence of an accelerate the formation of allophanate groups performs the catalyst. 9. The method according to claim 8, characterized in that one as Allopha natisation catalyst uses organic zinc compounds.   10. The method according to claim 8, characterized in that one as Allopha natization catalyst zinc (II) n-octoate, zinc (II) -2-ethyl-1-hexanoate and / or zinc (II) stearate. 11. Use of the polyisocyanate mixtures according to claim 1 as a starting point component in the production of polyurethane plastics. 12. Use of the polyisocyanate mixtures according to claim 1 for the preparation of coatings. 13. Use of the polyisocyanate mixtures according to claim 1 as a crosslinking agent component for water-soluble or -dispersible paint binders or Paint binder components in the manufacture of coatings under Ver Use of aqueous coating compositions based on such Binder or binder components.