EP3768748A1

EP3768748A1 - Catalyst system for uretdione dispersions

Info

Publication number: EP3768748A1
Application number: EP19711127.1A
Authority: EP
Inventors: Saskia BEUCK; Sebastian Dörr; Hans-Josef Laas; Dorota Greszta-Franz; Nusret Yuva; Ralph-Georg BORN
Original assignee: Covestro Deutschland AG; Covestro LLC
Current assignee: Covestro Deutschland AG; Covestro LLC
Priority date: 2018-03-23
Filing date: 2019-03-21
Publication date: 2021-01-27
Also published as: CN112105666A; CN111886273A; EP3768756A1; CN112041367B; WO2019183304A1; WO2019180128A1; EP3768751A1; CN111886272B; EP3768749A1; WO2019183308A1; CN111886271A; WO2019183330A1; WO2019183305A1; EP3768758A1; WO2019180129A1; CN112105665A; CN112105666B; WO2019183307A1; EP3768755A1; EP3768747A1

Abstract

The present invention relates to a catalyst system comprising: A) at least one compound selected from azoles, oxazoles, thiazoles, benzotriazole, benzimidazole, benzoxazole and salts thereof; B) at least one acid catcher, which contains at least one expoy group; and C) at least one catalyst containing an Ν,Ν,Ν'-trisubstituted amidine structure with an amidine group content of from 12.0 to 47.0 wt%, calculated as CN2 with molecular weight = 40. The invention also relates to a kit which comprises the catalyst system of the present invention and an aqueous uretdione dispersion having an acid number of from 1 to 100 KOH/g and additionally at least one carboxyl group. The invention further relates to a method for producing a polyurethane layer using the catalyst system of the present invention and said uretdione dispersion, and to the obtained polyurethane layer, and to the use of the catalyst system for curing aqueous acidic uretdione dispersions and/or for the production of paints or coatings.

Description

Katalvsatorsvstem for Uretdiondispersionen

The present invention relates to a catalyst system comprising

A) at least one compound selected from azoles, oxazoles, thiazoles, benzotriazole, benzimidazole, benzoxazole and their salts;

B) at least one acid scavenger containing at least one epoxy group; and

C) at least one catalyst containing an N, N, N'-trisubstituted amidine structure, having an amidine group content of 12.0 to 47.0% by weight, calculated as CN2 with molecular weight = 40. The present invention further relates to a kit, which comprises the catalyst system of the present invention and an aqueous uretdione dispersion having an acid value of from 1 to 100 mg KOH / g and further having at least one carboxyl group, a process for producing a polyurethane layer comprising the catalyst system of the present invention and said uretdione dispersion and the thereby obtained Polyurethane layer, as well as the use of the catalyst system for curing aqueous uretdione dispersions and / or for the production of paints or coatings.

The preparation of polyurethane layers starting from uretdione dispersions is known. This is done mainly by the use of uretdione group-containing powder coating compositions.

EP 0 803 524 A1 describes amidines as catalysts in uretdione group-containing PU powder coating compositions. The uretdione component and the OH-containing binder component are solid at room temperature. These are applied to the substrate by electrostatic powder spraying or vortex sintering, the curing temperatures being above 130 ° C. Their application as aqueous systems is not possible.

Also EP1526146 A1 describes a polyurethane powder coating composition. In this regard, it is disclosed that the activity of the amidine catalysts decreases significantly in the presence of acids. Epoxide group-terminated, uretdione-group-containing polyaddition compounds having a melting point of 40-130 ° C. are used. The epoxide is anchored in the backbone, it is for example 2,3-epoxy-l-propanol and / or epoxidized soybean oil used. In addition, a catalyst from the group of metal acetylacetonates, metal hydroxides, metal alcoholates, quaternary ammonium hydroxides, quaternary ammonium fluorides or quaternary ammonium carboxylates is used for curing. The curing temperature is usually 120-160 ° C. Their application as aqueous systems is not possible. In WO 2009/095117 Al powder coating compositions are described which have a melting point of more than 40 ° C. The catalyst used are quaternary ammonium salts or phosphonium salts. The co-catalyst used is an epoxide compound of terephthalic acid diglycidyl ether and trimellitic triglycidyl ether (Araldit PT 912) or acetylacetonate. With these systems, no curing temperatures below 120 ° C are possible. Also, their use as aqueous systems is not possible.

However, the application of powder coating compositions for producing polyurethane layers is complicated with regard to the devices required for this purpose. Furthermore, it is desirable to use lower crosslinking temperatures to make the process more energy efficient. The starting point should therefore form aqueous polyurethane dispersions containing uretdione groups, and simpler and thus more advantageous to handle. Nonionic hydrophilicized dispersions have a permanent hydrophilicity, poor chemicals, and water resistance. Therefore, ionically hydrophilicized dispersions should be used. These are known to be anionic better than cationic. Typical anionic systems contain carboxyl groups to provide better dispersion. Catalysts that are sensitive to acids, including carboxyl groups, such as Na triazolate seemed therefore not suitable.

An acidic, ie anionic, self-crosslinking polyuretdione dispersion is disclosed, for example, in DE 10 2005 036 654 A1. However, the crosslinking temperatures of such systems are over 130 ° C.

Therefore, a catalyst system was needed that is tolerant to acids and leads to at least as good cross-linking. However, these polyurethane dispersions were not compatible with the catalysts known in the art, e.g. the catalysts disclosed in US 9080074, crosslinkable.

The object of the present invention was therefore to develop catalyst systems for the crosslinking of aqueous anionic polyurethane dispersions containing uretdione groups. About the uretdione groups, a cross-linking of the polymers should be possible. The polymerization should preferably be able to take place below 100 ° C. (low-temperature crosslinking). The catalyst systems should also be insensitive to acidic conditions. Preferably, the catalyst systems should contain no organometallic compounds.

Surprisingly, it has been possible to find catalyst systems which are suitable for the crosslinking of aqueous compositions which contain acidic groups and in particular uretdione groups and with which crosslinking temperatures below 100 ° C. are achieved. The object of the present invention could be solved by:

A catalyst system comprising or consisting of

B) at least one acid scavenger containing at least one epoxide group; and

C) at least one N, N, N'-trisubstituted amidine structures-containing catalyst having an amidine group content of 12.0 to 47.0 wt .-%, calculated as CN2; Molecular weight = 40.

In particular, the present invention relates to:

1. Catalyst system comprising or consisting of

A) at least one compound selected from azoles, oxazoles, thiazoles, benzotriazole, benzimidazole, and benzoxazole and their salts;

B) at least one acid scavenger containing at least one epoxy group; and

C) at least one catalyst containing an N, N, N'-trisubstituted amidine structure and having an amidine group content of 12.0 to 47.0% by weight, calculated as CN 2; Molecular weight = 40.

2. Catalyst system according to embodiment 1, characterized in that the at least one compound A) is selected from pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole and benzotriazole and salts thereof; in particular from 1,2,3-triazole, 1,2,4-triazole and benzotriazole and their salts, more preferably from the alkali and alkaline earth salts of

1,2,3-triazole, 1,2,4-triazole and benzotriazole; most preferably from the Na, Li and K salts of 1,2,3-triazole, 1,2,4-triazole and benzotriazole.

3. Catalyst system according to embodiment 1 or 2, characterized in that the at least one acid scavenger B) is selected from aliphatic or aromatic alcohols, diols, polyols, ethers and acids containing at least one epoxy group.

4. Catalyst system according to one of the preceding embodiments, characterized in that the containing at least one, an N, N, N'-trisubstituted amidine structure, catalyst having an amidine group content of 12.0 to 47.0 wt .-% calculated as CN2; Molecular weight = 40, C) is selected from optionally substituted alkyl, aralkyl, or allyl radicals bearing amidine bases, wherein the CN- Double bond of the amidine structure may be both part of an open-chain molecule and part of a cyclic or bicyclic system or may be arranged exocyclically on a ring system, or any mixtures of such amidines. 5. Catalyst system according to one of the preceding embodiments, characterized in that A) to B) in a mass ratio of 1: 1 to 10: 1, preferably 2: 1 to 6: 1 and / or A) to C) in a mass ratio of 0.5: 1 to 5: 1, preferably 1: 1 to 2: 1 and / or B) to C) in a mass ratio of 1: 1 to 1:10, preferably 1: 1 to 1: 6 present.

6. A kit comprising the catalyst system according to any of embodiments 1 to 5 and separately therefrom an aqueous uretdione dispersion characterized by having an acid value of 1 to 100 mg KOH / g, preferably 2 to 50 mg KOH / g, stronger preferably 5 to 30 mg KOH / g, preferably measured according to DIN EN ISO 2114: 2002-06 with acetone and ethanol in a weight ratio of 2: 1 as a solvent and also having at least one carboxyl group.

7. The kit according to embodiment 6, characterized in that the equivalent ratio of uretdione to hydroxy groups used is 0.5: 1 to 1: 0.5, preferably 0.75: 1 to 1: 0.75, most preferably 1: 1 ,

A process for producing a polyurethane layer comprising the steps

i) providing an aqueous Uretdiondispersion having an acid number of 1 to 100 mg KOH / g, preferably 2 to 50 mg KOH / g, more preferably 5 to 30 mg KOH / g, preferably measured according to DIN EN ISO 2114: 2002-06 with Acetone and ethanol in the weight ratio 2: 1 as a solvent, and having at least one carboxyl group;

ii) adding the catalyst system according to any one of embodiments 1 to 5, preferably with stirring;

iii) applying the mixture obtained under ii) to a substrate;

iv) drying the mixture from step iii), preferably at room temperature and v) curing the mixture from step iv) with heat to 120 ° C, preferably up to 100 ° C, for up to 180 minutes, preferably up to 120 minutes.

9. Polyurethane layer, in particular polyurethane film, obtainable by a method according to embodiment 8. 10. Use of the catalyst system according to any one of embodiments 1 to 5 for curing aqueous Uretdiondispersionen having an acid number of 1 to 100 mg KOH / g, preferably 2 to 50 mg KOH / g, more preferably 5 to 30 mg KOH / g, preferred measured according to DIN EN ISO 2114: 2002-06 with acetone and ethanol in a weight ratio of 2: 1 as a solvent and at least one carboxyl group and / or for the production of paints or coatings, in particular polyurethane films.

Unless otherwise stated in the present invention, molecular weights are determined by GPC (gel permeation chromatography) using polystyrene standards.

Unless otherwise stated, percentages by weight in the present invention refer to the total weight of the particular system or the total weight of the particular component. For example, a copolymer may contain a given monomer in weight percent, in which case the weight percentages would be based on the total weight of the copolymer.

Unless otherwise stated, the term "at least one" refers to the nature of the compounds rather than individual molecules. For example, at least one acid scavenger B) is to be understood as containing at least one type of acid scavenger, but contained in an arbitrary number of molecules in the composition. Thus, two or more types of acid scavengers may be present in any arbitrary number, if the amounts are not defined.

A kit in the sense of the present invention is a system in which the catalyst system of the present invention and the aqueous carboxyl group-containing uretdione dispersion are spatially separated from each other.

The catalyst system comprises at least one compound A) selected from azoles, oxazoles, thiazoles, benzotriazole, benzimidazole, and benzoxazole and their salts. Preferably, the at least one compound A) is selected from pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole and benzotriazole and their salts. The salts are preferably alkali metal, alkaline earth metal or ammonium salts. Especially preferred is the at least one compound A) selected from 1,2,3-triazole, 1,2,4-triazole and benzotriazole and their salts, more preferably from the alkali and alkaline earth salts of 1,2,3-triazole, 1 2,4-triazole and benzotriazole; most preferably from the Na, Li and K salts of 1,2,3-triazole, 1,2,4-triazole and benzotriazole, especially the sodium salts thereof. Furthermore, the catalyst system comprises at least one acid scavenger B) containing at least one epoxy group. In a preferred embodiment, the at least one acid scavenger B) is selected from aliphatic or aromatic alcohols, diols, polyols, ethers and acids containing at least one epoxy group, preferably selected from C _2-20 alcohols, C _2-20 diols, C _{4- 50} polyols having at least 3 hydroxy groups, C _3-50 ethers and polyethers and C _3-20 acids containing at least one epoxy group. Particularly preferred are mono- and polyfunctional glycidyl ethers, such as butyl glycidyl ether, pentaerythritol tetraglycidyl ether, glycidyl isopropyl ether, 2-ethylhexyl glycidyl ether,

Polyethylene glycol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether or polyfunctional glycidyl ethers which are commercially available under the name HELOXY ™ Modifier from Hexion.

The at least one acid scavenger B) preferably has a viscosity of from 5 to 500 mPas, more preferably from 50 to 250 mPas, most preferably from 100 to 200 mPas, measured at 25 ° C. according to DIN 53015: 2001-02.

In a further preferred embodiment, the at least one acid scavenger B) has an epoxy equivalent (weight per epoxy group) of 120 to 650 g / eq, preferably 125 to 250 g / eq, measured according to DIN 16945: 1989-03.

Also preferably, the at least one acid scavenger B) has an epoxy value of from 20.0 to 35.0%, more preferably from 23.5 to 33.0%, most preferably from 26.5 to 32.5%, measured according to DIN 16945: 1989-03.

The catalyst system further contains at least one catalyst containing N, N, N'-trisubstituted amidine structures having an amidine group content of 12.0 to 47.0 wt.%, Calculated as CN2; Molecular weight = 40. Suitable amidine catalysts C) in which the CN double bond is present as part of an open-chain molecule are, for example, N, N-dimethyl-N'-phenylformamidine or N, N, N'-trimethylformamidine, the preparation of which, for. In Chem. Ber. 98, 1078 (1965). As examples of suitable amidines C), in which the CN double bond is part of a cyclic system, may be mentioned here: in 1-position substituted 2-methyltetrahydropyrimidines, as described for. B. according to the teaching of DE 2,439,550 Al can be obtained by reacting N-monosubstituted 1,3-propanediamines with acetoacetic acid derivatives, or monocyclic amidine bases, as in accordance with DE 1 078 568 A1 by reaction of carbamoyl chlorides from sec. Amines with lactams are accessible. Suitable catalysts C), in which the CN double bond is arranged exocyclically on a ring system are, for example, imines of N-alkyl-substituted lactams, such as 2-methylimino-1-methylpyrrolidone, the preparation of which, for. In Chem. Ber. 101, 3002 (1968). Preferred as at least one component C) are bicyclic, N, N, N'-trisubstituted amidine-containing catalysts of the general formula (1)

in which m is an integer from 1 to 9, preferably from 1 to 3, and n is an integer from 1 to 3, preferably 2.

The preparation of such bicyclic amidines is known and described, for example, in DE 1 545 855 A1 or EP 662 476 A1. Particularly preferred catalysts C) are 1,5-diazabicyclo [4.3.0] non-5-ene (DBN) and 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU), in particular DBU.

In a preferred embodiment, no ammonium or phosphonium salts are included. In a further preferred embodiment, no organometallic catalysts and / or quaternary ammonium hydroxides, quaternary ammonium fluorides or quaternary ammonium carboxylates are contained. In a further preferred embodiment, no further catalysts are included.

The invention further relates to a kit in which an acidic aqueous uretdione dispersion and the catalyst system of the present invention are present separately. Suitable uretdione dispersions are those generally known to those skilled in the art, with the proviso that they have an acid number of 1 to 100 mg KOH / g, preferably 2 to 50 mg KOH / g, more preferably 5 to 30 mg KOH / g, preferably measured according to DIN EN ISO 2114: 2002-06 with acetone and ethanol in the weight ratio 2: 1 as solvent, and having at least one carboxyl group.

In a preferred embodiment, the aqueous uretdione dispersion according to the present invention has an equivalent ratio of uretdione to hydroxy groups of from 0.5: 1 to 1: 0.5, preferably from 0.75: 1 to 1: 0.75, most preferably 1 : 1 up.

Suitable aqueous polyurethane dispersions usually contain, in the same polymer molecule, the essential structural units (I) and (II) in which R is an aliphatic, cycloaliphatic, araliphatic or aromatic radical which is derived from a polyisocyanate selected from the group consisting of tetramethylene diisocyanate, cyclohexane-1,3- or 1,4-diisocyanate, pentamethylene diisocyanate (PDI),

Hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate IPDI), dicyclohexylmethane 2,4'- and / or 4,4'-diisocyanate,

Tetramethylxylylene diisocyanate (TMXDI), triisocyanatononane, tolylene diisocyanate (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), triphenylmethane-4,4'-diisocyanate or naphthylene-1,5-diisocyanate, R 'is an alkyne, preferably ethyl or methyl, more preferably methyl, X is a carboxylic acid (COOH) or carboxylate (COCT) radical and Y is NH ₂ , NHR "or OH, preferably OH and R" is an alkyne, preferably hexyl , Butyl, propyl, ethyl or methyl, more preferably methyl. The dispersion which can be used in the present invention may contain both uretdione groups (acting as capped isocyanates) and hydroxyl groups in one molecule.

Suitable uretdione dispersions can be prepared by the following process comprising the steps of:

In a first step (I), an ionic uretdione group-containing, hydrophilicized, hydroxyl or isocyanate end-group-containing prepolymer by reaction of

- At least one uretdione group-containing polyisocyanate component (A2 '), having an isocyanate functionality> 2 and a ratio of uretdione to isocyanate groups of at least 0.10 and

at least one compound (C) which has at least one isocyanate-reactive and one acid-functional group,

optionally a further polyol component (BG) having a hydroxyl group functionality of> 2 and a molecular weight M _n of 62 to 500 g / mol, preferably 62 to 400 g / mol, particularly preferably 62 to 300 g / mol, - optionally one or more polyisocyanates (AG) having an NCO functionality of> 2, which are different from (A2 ') and preferably do not contain uretdione groups, prepared in a second step.

(II) the uretdione group-containing prepolymer,

which may be terminated by hydroxyl groups or isocyanate groups, by reaction of

- optionally one or more polyol components (B2 ') having a hydroxyl group functionality of> 1 and

optionally polyisocyanates (AG) having an NCO functionality of> 2 and

- At least one polyol component (B3 ') having an average hydroxyl group functionality of> 2 and a molecular weight Mn of 500 to 5000 g / mol, preferably 500 to 3000 g / mol, more preferably 500 to 2000 g / mol, in an isocyanate group-free and hydroxyl-functional polyurethane polymer which is added to a neutralizing agent (N) for complete or partial neutralization and dispersed in water. To this aqueous composition is then added the catalyst system of the present invention.

Likewise, the implementation of the first two synthesis steps can be carried out in the reverse order or in a single reaction step. It is also possible to use the polyol component (BG) proportionally in the preparation of the prepolymer (I). It is likewise possible to use the compound (C) proportionally in the prepolymerization (II) of the uretdione group-containing polyisocyanate mixture.

In a preferred embodiment of the invention, after addition of the polyol component (B3 '), an acid-functional compound (C) and a further polyisocyanate component (AG) are added simultaneously or in a further step.

The ratio of the isocyanate groups, including the uretdione groups, to all isocyanate-reactive groups is preferably from 0.5 to 5.0 to 1, more preferably from 0.6 to 2.0 to 1, especially from 0.8 to 1.5 to comply with 1.

Suitable polyisocyanate components (AG) are aliphatic, cycloaliphatic, araliphatic and / or aromatic isocyanates having an average functionality of from 2 to 5, preferably 2 and having an isocyanate content of from 0.5 to 60% by weight, preferably from 3 to 40% by weight. %, particularly preferably from 5 to 30 wt .-%, such as tetramethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), l-isocyanato-3,3,5-trimethyl 5-isocyanatomethylcyclohexane (isophorone diisocyanate IPDI), dicyclohexylmethane 2,4'- and / or 4,4'-diisocyanate, tetramethylxylylene diisocyanate (TMXDI), triisocyanatononane, Toluylene diisocyanate (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), triphenylmethane-4,4'-diisocyanate or naphthylene-l, 5-diisocyanate and any mixtures of such isocyanates. Preference is given to isophorone diisocyanate, dicyclohexylmethane 2,4'- and / or 4,4'-diisocyanate or hexamethylene diisocyanate, in particular isophorone diisocyanate.

Likewise suitable polyisocyanate components (AG) are polyisocyanates prepared by modifying the di- and / or triisocyanates mentioned above with isocyanurate, iminooxadiazinetrione, urethane, allophanate, biuret and / or oxadiazinetrione structures, as described, for example, in J. Prakt. Chem. 336 (1994) 185-200 or DE-A 16 70 666 and EP-A 798 299 are described by way of example.

Suitable polyisocyanates (AG) are also the known prepolymers having terminal isocyanate groups, such as are obtainable in particular by reacting the abovementioned simple polyisocyanates, especially diisocyanates, with substoichiometric amounts of organic compounds having at least two isocyanate-reactive functional groups. In these known prepolymers, the ratio of isocyanate groups to NCO-reactive hydrogen atoms is 1.05: 1 to 10: 1, preferably 1.5: 1 to 4: 1, wherein the hydrogen atoms are preferably derived from hydroxyl groups. The type and proportions of the starting materials used in the preparation of NCO prepolymers are selected so that the NCO prepolymers preferably have an average NCO functionality of 2 to 3 and a number average molecular weight of 300 to 10,000 g / mol, preferably 800 to 4000 g / mol.

Suitable components (A2 ') are polyisocyanates which contain at least one isocyanate group and at least one uretdione group. These are prepared, as described, for example, in WO 02/92657 A1 or WO 2004/005364 A1 by reaction of suitable starting isocyanates. Here, under catalysis, for example with triazolates or 4-dimethylaminopyridine (DMAP) as catalysts, some of the isocyanate groups are converted into uretdione groups. Examples of isocyanates from which the uretdione-containing building blocks (A2 ') are synthesized are tetramethylene diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), 1-isocyanato-3,3, 5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate IPDI), dicyclohexylmethane 2,4'- and / or 4,4'-diisocyanate, tetramethylxylylene diisocyanate (TMXDI), triisocyanatononane,

Toluylene diisocyanate (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), triphenylmethane-4,4'-diisocyanate or naphthylene-l, 5-diisocyanate and any mixtures of such isocyanates. Preference is given to isophorone diisocyanate, dicyclohexylmethane 2,4'- and / or 4,4'-diisocyanate or hexamethylene diisocyanate.

In addition to the isocyanate groups and uretdione groups, component (A2 ') may also have isocyanurate, biuret, allophanate, urethane and / or urea structures. The polyol component (BG) preferably contains 2- to 6-valent polyol components of molecular weight Mn of 62 to 500 g / mol, preferably 62 to 400 g / mol, particularly preferably 62 to 300 g / mol. Preferred polyol components (BG) are, for example, 1,4- and / or 1,3-butanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane, polyester and / or polyether polyols of the middle one Molar weight M _n of less than or equal to 500 g / mol.

Suitable acid functional compounds (C) are hydroxy-functional carboxylic acids, preferably mono- and dihydroxycarboxylic acids, e.g. 2-hydroxyacetic acid, 3-hydroxypropanoic acid or 12-hydroxy-9-octadecanoic acid (ricinoleic acid). Preferred carboxylic acids (C) are those in which the carboxyl group is hindered in its reactivity due to steric effects, e.g. Lactic acid. Particularly preferred are 3-hydroxy-2,2-dimethylolpropanoic acid (hydroxypivalic acid) or dimethylolpropionic acid, most preferably exclusively dimethylolpropionic acid is used.

However, if component (BG) is used as a proportion in step (I), its proportion is at most 50% by weight, based on the sum of components (C) and (BG). Preferably, in step (I) only component (C) is used.

The polyol component (B2 ') is selected from the group of

b1) 2- to 6-hydric alcohols having average molecular weights Mn of from 62 to 300 g / mol, preferably from 62 to 182 g / mol, particularly preferably from 62 to 118 g / mol,

b2) linear, difunctional polyols having average molecular weights Mn of from 350 to 4000 g / mol, preferably from 350 to 2000 g / mol, particularly preferably from 350 to 1000 g / mol,

b3) monofunctional linear polyether having average molecular weights Mn of 350 to 2500 g / mol, preferably from 500 to 1000 g / mol.

Suitable polyol component (bl) are 2 to 6-hydric alcohols and / or mixtures thereof which have no ester groups. Typical examples are 1,2-ethanediol, 1,2-propanediol and 1,3-diol, 1,4-butanediol, 1,2 or 2,3, 1,6-hexanediol, 1,4-dihydroxycyclohexane, glycerol, Trimethylolethane, trimethylolpropane, pentaerythritol and sorbitol. Of course, as component (bl) it is also possible to use alcohols with ionic groups or groups convertible into ionic groups. Preference is given, for example, to 1,4- or 1,3-butanediol, 1,6-hexanediol or trimethylolpropane and mixtures thereof.

Suitable linear difunctional polyols (b2) are selected from the group of polyethers, polyesters and / or polycarbonates. Preferably, the polyol component (b2) contains at least one ester group-containing diol of molecular weight Mn from 350 to 4000 g / mol, preferably from 350 to 2000 g / mol, more preferably from 350 to 1000 g / mol. It is the average, calculated from the hydroxyl number molecular weight. In general, the ester diols are mixtures in which, in minor amounts, individual components may also be present which have a molecular weight below or above these limits. These are the polyester diols known per se, which are built up from diols and dicarboxylic acids.

Suitable diols are, for example, 1,4-dimethylolcyclohexane, 1,4- or 1,3-butanediol, 1,6-hexanediol, neopentyl glycol, 2,2,4-trimethyl-1,3-pentanediol, trimethylolpropane and also pentaerythritol or mixtures thereof diols. Suitable dicarboxylic acids are, for example, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid, cycloaliphatic dicarboxylic acids such as e.g. Hexahydrophthalic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid or its anhydrides and aliphatic dicarboxylic acids, which are preferably used, such as succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacic acid or their anhydrides.

Polyester diols based on adipic acid, phthalic acid, isophthalic acid and tetrahydrophthalic acid are preferably used as component (b2). As preferred diols, for example, 1,4- or 1,3-butanediol, 1,6-hexanediol or trimethylolpropane and mixtures thereof are used.

Likewise suitable as component (b2) are polycaprolactone diols having an average molecular weight of from 350 to 4000 g / mol, preferably from 350 to 2000 g / mol, particularly preferably from 350 to 1000 g / mol, which are prepared in a manner known per se from a diol or diol mixture the type exemplified above as starter and e-caprolactone have been prepared. The preferred starter molecule is 1,6-hexanediol. Particularly preferred are those polycaprolactone diols which have been prepared by polymerization of e-caprolactone using 1,6-hexanediol as a starter.

As the linear polyol component (b2) it is also possible to use (co) polyethers of ethylene oxide, propylene oxide and / or tetrahydrofuran. Preferred are polyethers having an average molecular weight Mn of from 500 to 2000 g / mol, such as e.g. Polyethylene oxides or polytetrahydrofurandiols.

Also suitable as (b2) are hydroxyl-containing polycarbonates, preferably average molecular weight Mn of from 400 to 4000 g / mol, preferably from 400 to 2000 g / mol, for example hexanediol polycarbonate and polyestercarbonates. Suitable mono-functional linear polyethers (b3) are, for example, (co) polyethers of ethylene oxide and / or propylene oxide. Preference is given to monoalcohol-initiated polyalkylene oxide polyethers of average molecular weight Mn of from 350 to 2500 g / mol with at least 70% of ethylene oxide units.

Particularly preferred are (co) polymers with more than 75% ethylene oxide units and a molecular weight Mn of 350 to 2500 g / mol, preferably from 500 to 1000 g / mol. As starter molecules in the preparation of these polyether monofunctional alcohols having 1 to 6 carbon atoms are preferably used.

Suitable polyols (B3 ') are polyols having an OH functionality greater than or equal to 2, and with average molecular weights of 500 to 5000 g / mol, preferably from 500 to 3000 g / mol, particularly preferably from 500 to 2000 g / mol.

Preferred polyols (B3 ') are e.g. Polyether average molecular weight of 300 to 2000 g / mol and an average functionality of 2.5 to 4 OH groups / molecule. Also preferred are polyesters of average OH functionality of 2.5 to 4.0. Suitable diols and dicarboxylic acids for the polyesters are those mentioned under component (b2), but additionally contain tri- to hexafunctional short-chain polyols, e.g. Trimethylolpropane, pentaerythritol or sorbitol. It is preferred to use polyester polyols based on adipic acid, phthalic acid, isophthalic acid and tetrahydrophthalic acid, as well as 1,4-butanediol and 1,6-hexanediol.

Also suitable as component (B3 ') are (co) polyethers of ethylene oxide, propylene oxide and / or tetrahydrofuran average functionality of greater than or equal to 2, as well as polycarbonate polyols.

The process according to the invention should be carried out in such a way that in the reaction of components (A ') and (BG) according to the theoretical stoichiometric equation there is as little as possible unreacted excess components (A) and / or (B1).

The preparation of the aqueous dispersions containing the self-crosslinking polyurethanes according to the invention is carried out by methods of the prior art.

The carboxylic acid groups present in the polyurethanes of the invention are preferably at least 50%, more preferably 80% to 120%, particularly preferably 95 to 105% neutralized with suitable neutralizing agents (N) and then dispersed with deionized water. The neutralization can take place before, during or after the dispersing or dissolving step. However, preference is given to neutralization before the addition of water. Suitable neutralizing agents (N) are, for example, triethylamine, dimethylaminoethanol, dimethylcyclohexylamine, triethanolamine, methyldiethanolamine, diisopropanolamine, ethyldiisopropylamine, diisopropylcyclohexylamine, N-methylmorpholine, 2-amino-2-methyl-1-propanol, ammonia or other customary neutralizing agents or neutralization mixtures thereof.

Preference is given to tert. Amines such as e.g. Triethylamine, diisopropylhexylamine, particularly preferred is dimethylethanolamine.

To regulate the viscosity, solvents may also be added to the reaction mixture if appropriate. Suitable are all known paint solvents such as N-methylpyrrolidone, methoxypropyl acetate, Proglyde DMM ^® (Dow Chemicals), Shellsol ^® (Shell AG) or xylene. Preferably, amounts of 0 to 10 wt .-%, preferably 0 to 5 wt .-%, are used. The solvent is preferably added during the polymerization.

Optionally, auxiliaries and additives of the coating technology which are to be used, such as, for example, pigments, leveling agents or bubble-preventing additives, can also be added to the aqueous dispersions according to the invention.

Alternative, likewise suitable uretdione dispersions of the present invention are storage-stable, reactive aqueous uretdione-group-containing compositions which comprise a physical mixture dispersed in water and, if appropriate, organic solvents

(Al I) at least one hardener containing uretdione groups, based on aliphatic, (cyclo) aliphatic, araliphatic and / or aromatic polyisocyanates, which contains no chemically bonded hydrophilicizing groups;

(B12) at least one hydroxyl-containing polyol which contains at least one chemically bonded carboxylic acid group;

(CI 3) optionally solvents, and

(D14) where appropriate, auxiliaries and additives,

wherein the amount ratio of the components (Al l) and (Bl 2) is such that the molar ratio of the uretdione present NCO groups of the harder (Al l) to NCO-reactive groups of the polyol (B12) 0.5: 1 to 1: 0.5 and the aqueous composition has an acid number of 1 to 100 mg KOH / g, preferably 2 to 50 mg KOH / g, more preferably 5 to 30 mg KOH / g, preferably measured according to DIN EN ISO 2114: 2002-06 with acetone and ethanol in a weight ratio of 2: 1 as a solvent. To this aqueous composition is then added the catalyst system of the present invention. Suitable polyisocyanates containing uretdione groups as starting compounds for the component (Al 1) are the polyisocyanates (A2 ') described above.

The reaction of these uretdione group-carrying polyisocyanates to uretdione-containing hard (Al1) involves the reaction of the free NCO groups of the starting compounds (A2 ') with the polyol component (BG), optionally with the concomitant use of the polyol component (b2).

As polyol component in the preparation of uretdione groups having curing agent (Al l) also low molecular weight ester-containing diols of a mean, calculated from functionality and hydroxyl number molecular weight of 134 to 349 g / mol, preferably 176 to 349 g / mol, are used.

These are, for example, the per se known, ester-containing diols or mixtures of such diols, as they are, for. B. by reacting alcohols with minor amounts of dicarboxylic acids, corresponding dicarboxylic anhydrides, corresponding dicarboxylic acid esters of lower alcohols or lactones. Examples of suitable acids are succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic acid, maleic acid, maleic anhydride, terephthalic acid dimethyl ester and terephthalic acid bis-glycol ester. Suitable lactones for the preparation of these ester diols are, for example, β-propiolactone, g-butyrolactone, g- and d-valerolactone, ε-caprolactone, 3,5,5- and 3,3,5-trimethylcaprolactone or any desired mixtures of such lactones.

In the preparation of uretdione groups having curing agent (Al l) and amino-functional compounds can be used. Examples of suitable low molecular weight amino-functional compounds are aliphatic and cycloaliphatic amines and amino alcohols having primary and / or secondary bound amino groups, such as. Cyclohexylamine, 2-methyl-l, 5-pentanediamine, diethanolamine, monoethanolamine, propylamine, butylamine, dibutylamine, hexylamine, monoisopropanolamine, diisopropanolamine, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, isophoronediamine, diethylenetriamine, ethanolamine, Aminoethyl-ethanolamine, diaminocyclohexane, hexamethylenediamine, methyliminobispropylamine, iminobispropylamine, bis (aminopropyl) piperazine, aminoethylpiperazine, 1,2-diaminocyclohexane, triethylenetetramine, tetraethylenepentamine, bis (4-amino-cyclohexyl) methane, bis (4-amino-3-methylcyclohexyl ) methane, bis (4-amino-3,5-dimethylcyclohexyl) methane, bis (4-amino-2,3,5-trimethylcyclohexyl) methane, 1,1-bis (4-aminocyclohexyl) propane, 2,2-bis (4-aminocyclohexyl) propane, 1,1-bis (4-aminocyclohexyl) ethane, 1,1-bis (4-aminocyclohexyl) butane, 2,2-bis (4-aminocyclohexyl) butane, 1,1-bis (4 -amino-3-methylcyclohexyl) ethane, 2,2-bis (4-amino-3-methylcyclohexyl) propane, 1,1-bis (4-amino-3,5-dimethylcyclohexyl) ethane, 2,2-bis (4 amino-3,5 dimethylcyclohexyl) propane, 2,2-bis (4-amino-3,5-dimethylcyclohexyl) butane, 2,4-

Diaminodicyclohexylmethane, 4-aminocyclohexyl-4-amino-3-methylcyclohexylmethane, 4-amino-3,5-dimethylcyclohexyl-4-amino-3-methylcyclohexylmethane and 2- (4-aminocyclohexyl) -2- (4-amino-3-methylcyclohexyl )methane.

If necessary, solvents may be used in the preparation of the uretdione group-containing hardeners (Al 1). Suitable solvents for uretdione hardeners (Al l) are all liquid substances which do not react with other ingredients, eg. As acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene, Solvesso 100, Solvesso 150, propylene glycol mono-n-butyl ether (Dowanol PnB, (Dow Chemicals)), ^® Proglyde DMM (Dow Chemicals), methoxypropyl acetate and Dibasicester.

The uretdione group-containing hardener (Al l) are free from ionic or non-ionic hydrophilizing compounds. Amongst the ionically hydrophilizing compounds, the person skilled in the art understands compounds which have at least one group capable of anion or cation formation. Groups capable of anion or cation formation are those which can be converted by chemical reaction into an anionic or cationic group, in particular by neutralization.

The uretdione hardening agents (Al 1) are preferably free of anion-forming, carboxyl-containing polyols or diols, e.g. Dihydroxycarboxylic acids, such as α, α-dialkylolalkanoic acids, in particular α, α-dimethylolalkanoic acids, such as 2,2-dimethylolacetic acid, 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,

Dihydroxysuccinic acid, or polyhydroxy acids such as gluconic acid. Furthermore, uretdione-containing curing agents (Al 1) are preferably free from anion-containing compounds capable of forming anions, such as, for example, α, ω-diaminovaleric acid, 2,4-diamino-toluenesulfonic acid and the like. The uretdione group-containing hardeners (Al 1) are also preferably free of sulfonic acid groups capable of forming anions.

In addition, the uretdione hardening agents (Al 1) are preferably free of cation-forming compounds from the group of tertiary amino or ammonium compounds, e.g. Tris (hydroxyalkyl) amines, N, N'-bis (hydroxyalkyl) alkylamines, N-hydroxyalkyldialkylamines, trisaminoalkylamines, N, N'-bisaminoalkylalkylamines, N-aminoalkyldialkylamines, and mixtures thereof.

The uretdione group-containing hardeners (Al 1) are furthermore preferably free from nonionically hydrophilizing compounds, such as, for example, polyalkylene oxide polyether alcohols or polyalkylene oxide polyether amines. In particular, the uretdione groups are hardeners (Al 1) preferably free of polyethylene oxide polyether or mixed polyalkylene oxide polyethers whose alkylene oxide units consist of at least 30 mol% of ethylene oxide units.

Preferred uretdione hardeners (Al 1) have a free NCO content of less than 5% by weight and a content of uretdione groups of 1 to 18% by weight (calculated as C 2 N 2 O 2, molecular weight 84 g / mol). In addition to the uretdione groups, the hardeners A (11) may also have isocyanurate, biuret, allophanate, urethane and / or urea structures.

Suitable polyols (Bl 2) can be selected from polyester polyols, polyether polyols, polyurethane ether polyols, polyurethane ester polyols, polycaprolactone polyols,

Polyetheresterpolyole, polycarbonate polyols, poly (metha) acrylate polyols, C2-io hydrocarbon having at least two hydroxyl groups or mixtures thereof are selected, as long as such polyols have at least one chemically bonded carboxylic acid groups.

As having at least one chemically bonded carboxylic acid group

Starting component for the polyols (B12) are those polyols, preferably diols, in question, which contain at least one carboxylic acid group, generally 1 to 3 carboxylic acid groups per molecule. Examples of these are dihydroxycarboxylic acids, such as a, a-dialkylolalkanoic acids, especially a, a dimethylolalkanoic acids, such as 2,2-dimethylolacetic acid, 2,2-

Dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolpentanoic acid,

Dihydroxysuccinic acid, furthermore polyhydroxy acids, such as gluconic acid, or aminocarboxylic acids, such as, for example, a, W-diaminovaleric acid, 2,4-diamino-toluenesulfonic acid and the like. It is also possible to use mixtures of the compounds described above.

As having at least one chemically bonded carboxylic acid group

Starting component for the polyols (B12) is particularly preferred 2,2-dimethylolpropionic acid. Less preferred may also be monohydroxy-functional compounds having at least one carboxylic acid group, such as hydroxypivalic acid or hydroxydecanoic acid.

For the polyols (Bl 2) selected from poly (metha) acrylate polyols are copolymers which contain monomer units with carboxylic acid or carboxylic anhydride groups, such as acrylic acid, methacrylic acid, ß-carboxyethyl acrylate, crotonic acid, fumaric acid, maleic acid (anhydride), ltaconic acid or monoalkyl esters of dibasic acids or anhydrides, for example maleic acid monoalkyl esters. Preference is given to acrylic acid or methacrylic acid copolymers. Suitable polyols (B12) are polyols having an OH content greater than 1% by weight (calculated as OH group on solid content, molecular weight 17 g / mol) and with number-average molecular weights Mn from 500 to 20,000 g / mol, preferably from 500 to 10,000 g / mol, more preferably from 500 to 5,000 g / mol.

The preparation of the polyurethane resin used according to the invention is preferably carried out in such a way that a non-aqueous resin precursor of the polyol (B12) with at least one uretdione curing agent (Al l) based on aliphatic, (cyclo) aliphatic, araliphatic and / or aromatic polyisocyanates which contains no chemically bound hydrophilizing groups, homogeneously mixed in a nonaqueous system. Subsequently, the carboxylic acid groups present in the polyol (B12) are preferably neutralized to at least 50%, more preferably 80% to 120%, particularly preferably 95 to 105% with suitable neutralizing agents (N) and then dispersed with deionized water. The neutralization may be carried out before, during or after the dispersing step. However, preference is given to neutralization before the addition of water.

Suitable neutralizing agents (N) are, for example, triethylamine, dimethylaminoethanol, dimethylcyclohexylamine, triethanolamine, methyldiethanolamine, diisopropanolamine, ethyldiisopropylamine, diisopropylcyclohexylamine, N-methylmorpholine, 2-amino-2-methyl-1-propanol, ammonia or other customary neutralizing agents or neutralization mixtures thereof.

As solvents under (CI 3) are all liquid substances suitable that do not react with other ingredients. Preferred are acetone, methyl ethyl ketone, ethyl acetate, butyl acetate, xylene, Solvesso 100, Solvesso 150, propylene glycol mono-n-butyl ether (Dowanol PnB), methoxypropyl acetate and dibasic ester. Optionally, the solvent used can then be removed by distillation.

According to the invention, the customary in the paint or adhesive technology additives (D14), such as leveling agents, z. As polysilicones or acrylates, light stabilizers, for. As sterically hindered amines, or other auxiliaries, such as. As described in EP 0 669 353, be contained in a total amount of 0.05 to 5 wt.%. Fillers and pigments such as titanium dioxide may be added in an amount of up to 50% by weight of the uretdione dispersion. Examples:

Methods and materials:

methods:

Unless otherwise stated, all analytical methods are based on measurements at temperatures of 23 ° C.

Pendulum hardness: The pendulum hardness was measured on a glass plate according to DIN EN ISO 1522: 2007-04 and is determined by König.

Solvent and water resistance:

The cured paints were tested for resistance to xylene, 1-methoxy-2-propyl acetate, ethyl acetate, acetone and water. A piece of cotton wool soaked in the test substance was placed on the coating surface and covered with a watch glass. After the indicated exposure time, the cotton was removed, the exposed area was dried and examined immediately. The evaluation of the softening or discoloration of the coating surface was carried out according to DIN EN ISO 4628-1: 2016-07.

0 unchanged, i. no discernible change

1 very light, i. only visible change, e.g. Trace of a shade change

2 identifiable, i. clearly recognizable change, e.g. noticeable softening with the fingernail

3 clearly noticeable change, e.g. average color change, possibly slight blistering

4 strong change, e.g. strong blistering

5 Completely destroyed coating without external influence

IR measurement:

The uretdione ring opening was characterized by a Bruker FT-fR spectrometer (Tensor II with platinum ATR (diamond crystal) unit) The spectra were recorded in a wavenumber range of (4000-400) cm ^1. The maximum of the uretdione peak (approximately 1760 cm ¹ ) was evaluated, and peak heights to comparative systems were compared to an initial value set to 100% (uretdione film without catalyst, dried at room temperature) The uretdione peak height of the films cured at 180 ° C. for 30 min set to 0%. Variations were determined relative to these 100 and 0% values (ratio formation).

When measured on an ATR crystal, the intensity of the spectrum depends on the occupation of the crystal surface. Since comparable measurements by sample preparation can not guarantee a comparable coverage of the crystal surface, a correction of this effect for the ratio formation by normalization of all spectra on the top of the CH- Stretching oscillation (wavenumber range) (3000-2800 cm ¹ ) In the evaluation of the peak heights described above, a basic correction of the spectra is additionally performed.

The solids content (non-volatile content) was determined by heating a weighed sample at 125 ° C to constant weight. At constant weight, the solids content is calculated by weighing the sample back.

The NCO content was determined volumetrically according to DIN-EN ISO 11909. The control of free NCO groups was carried out by IR spectroscopy (band at 2260 cm ¹ ).

The indicated viscosities were determined by means of rotational viscometry according to DIN 53019: 2016-10 at 23 ° C. using a rotational viscometer with a shear rate of 40 l / s, Anton Paar Germany GmbH, Ostfildern, Germany.

The mean particle sizes (number average) of the polyurethane dispersions were determined after dilution with deionized water by laser correlation spectroscopy (instrument: Malvern Zetasizer 1000, Malver Inst. Limited, London, UK).

The zeta potential was measured by diluting one drop of the sample with 20 mL of demineralized water and homogenizing by stirring. Subsequently, the zeta potential was determined at 23 ° C in the Malvern Nanosizer ZS90 (Malvern Instruments, Herrenberg, Germany).

The acid number of the respective dispersion was determined in accordance with DIN EN ISO 2114: 2002-06. Instead of a mixture of toluene and ethanol, as described in DIN EN ISO 2114: 2002-06, the solvent used was a mixture of acetone and ethanol (2: 1, by weight). The unit of acid number is mg KOH per g of the sample analyzed.

Materials:

Lupragen N 700 (l, 8-diazabicyclo-5,4,0-undecene-7 (DBU)): Fa. BASF SE

Na-1, 2,4-triazolate: Fa. Sigma-Aldrich

Heloxy Modifier TP: Polyfunctional glycidyl ether of trimethylolpropane, Hexion

Bayhydrol A2695: water-dilutable, OH-functional polyacrylate dispersion; about 41% in water / l-butoxy-2-propanol, neutralized with triethanolamine / dimethylethanolamine, 7.2% 1-butoxy-2-propanol, Fa. Covestro

Dowanol PnB: Propylene glycol mono-n-butyl ether, Dow

Peroxan DB: di-tert-butyl peroxide: Pergan

Solvent Naphtha 100: an aromatic solvent, Azelis

Butyl glycol: Brenntag

Dimethylolpropionic acid (DMPS): Perstorp

Addocat SO: tin (II) 2-ethylhexanoate, Rhein Chemie,

All acrylate monomers and amines (from Sigma-Aldrich) were used as supplied

Veova 9: Versatic acid vinyl ester, company Momentive

Other solvents and chemicals: Sigma-Aldrich

Xylene (Xy); l-methoxy-2-propyl acetate (MPA); Ethyl acetate (EA); Acetone (Ac)

Examples of Polvmersvnthese:

Production Example 1

Preparation of a uretdione polyisocyanate based on isophorone diisocyanate

1000 g (4.50 mol) of isophorone diisocyanate (IPDI) were admixed successively with 10 g (1%) of triisodecyl phosphite and 20 g (2%) of 4-dimethylaminopyridine (DMAP) as catalyst at room temperature under dry nitrogen with stirring. After 20 h, the reaction mixture, which had an NCO content of 28.7%, corresponding to a degree of oligomerization of 21.8%, without prior addition of a catalyst poison with the aid of a thin-film evaporator at a temperature of 160 ° C. and a pressure of 0, 3 mbar of volatile components.

This gave a light yellow uretdione with a content of free NCO groups of 17.0%, a content of monomeric IPDI of 0.4% and a viscosity (according to DIN EN ISO 3219: 1994-10) of more than 200,000 mPas (23 ° C).

Preparation of a water-emulsifiable crosslinking agent containing uretdione groups

247 g (1.00 eq) of the above-described uretdione group-containing polyisocyanate based on IPDI with a content of free isocyanate groups of 17.0% and a calculated content of uretdione groups of 20.8% were dissolved in 370.3 g of 1-methoxy- Submitted 2-propyl acetate, treated with 0.2 g of dibutyltin dilaurate (DBTL) as a catalyst and heated to 80 ° C under dry nitrogen. Subsequently, a mixture of 40.6 g (0.90 eq) of 1,4-butanediol and 82.5 g (0.11 eq) of methoxypolyethylene glycol 750 was added over 30 minutes and stirred at a reaction temperature of max. 105 ° C until the NCO content of the reaction mixture had dropped after about 6 h to a value of less than 0.1%. There was a pale yellow solution of a crosslinking agent containing uretdione groups with the following characteristics:

NCO content: <0.1%

Uretdione group content (calculated): 6.9%

monomeric IPDI: 0.09%

Solid content: 50%

Production Example la

337 g of 1,4-butanediol, 108 g of 2-ethylhexanol and 569 g of e-caprolactone were mixed at room temperature under dry nitrogen, mixed with 0.3 g of stannous octoate, stirred at 160 ° C. for 5 hours and then taken up Room temperature cooled. To this mixture were then 1850 g uretdiongruppenhaltigen polyisocyanates based on fPDI with a content of free isocyanate groups of 17.0% and a calculated content of uretdione groups of 20.8 % of Preparation 1, heated to 80 ° C within 30 minutes added. The reaction mixture was heated at a temperature of max. Stirred 100 ° C until the NCO content of the reaction mixture after 7 to 8 h has dropped to a value of 0.8%. Subsequently, 1910 g of Dowanol PnB was added to the reaction mixture, and the solution was cooled to room temperature.

Production Example 2

Preparation of an anionic uretdione prepolymer dispersion:

218.5 g of IPDI dimer from Preparation Example 1 were dissolved in 850 g of acetone at 50 ° C. in a standard stirrer. 22.9 g of dimethylolpropionic acid, 265.9 g of an OH-functional polyester based on 3039 g of adipic acid, 4041 g of isophthalic acid, 267 g of 1,2-propylene glycol, 4773 g of neopentyl glycol and 1419 g of trimethylolpropane (OH number of the polyester: 181 mg KOH / g) and 0.63 g of tin neodecanoate were added and the mixture was stirred at reflux under atmospheric pressure until the NCO content dropped below 0.5%. Then, 16.8 g of N, N-dimethylaminoethanol and 927 g of water were added. The acetone was removed by distillation in vacuo, the viscosity was adjusted by adding water.

The resulting white dispersion had the following properties:

Solid content: 37.6%

Average particle size: 91 nm

Viscosity: 31 mPas

Acid number: 7.3 mg KOH / g (based on the dispersion)

Zeta potential: 49.6 mV

Production Examples 3a-d:

Production Example 3a

Table 1.

Part 1 of Table 1 was weighed into a stirring apparatus under nitrogen and heated to 138 ° C. Thereafter, Part 2 was added uniformly at 138 ° C in 20 min. Subsequently, immediately part 3 and part 4 were added in parallel in 4 hrs. 30 Min. At 138 ° C evenly. After the addition, the reaction mixture was kept at 138 ° C for 30 min. Finally, Part 5 and Part 6 were added uniformly in 1 hr. 30 Min. At 138 ° C in parallel. After the addition, the reaction mixture was again held at 138 ° C for 1 hr. After cooling to 100 ° C, the reaction mixture was bottled. This gave a slightly yellowish, highly viscous polyacrylate solution. 500 g of this solution were weighed into a stirring apparatus under nitrogen and heated to 70 ° C. After homogenization, 567 g of the solution from preparation 1a were added and the mixture was again homogenized at 70 ° C. for 30 min, followed by the addition of a mixture of 21.5 g of triethanolamine and 4.3 g of dimethylethanolamine. After stirring for a further 30 minutes at 70 ° C., 463 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solid content: 43.7% by weight

Acid number (100%): 13 mg KOH / g

OH content (100%, calculated): 2.8% by weight

Average particle size: 230 nm

Viscosity: 2030 mPas Production Example 3b

500 g polyacrylate solution from Preparation Example 1 were weighed into a stirring apparatus under nitrogen and heated to 70 ° C. After homogenization, 283 g of the solution from Preparation 1a were added and the mixture was again homogenized at 70 ° C. for 30 minutes, followed by the addition of a mixture of 21.5 g of triethanolamine and 4.3 g

Dimethylethanolamine. After stirring for a further 30 minutes at 70 ° C., 407 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solid content: 41.7% by weight

Acid number (100%): 16.6 mg KOH / g

OH content (100%, calculated): 3.6% by weight

Average particle size: 175 nm

Viscosity: 2360 mPas Preparation Example 3c

Table 2.

Part 1 of Table 2 was weighed into a stirring apparatus under nitrogen and heated to 138 ° C. Thereafter, Part 2 was added uniformly at 138 ° C in 20 min. Subsequently, immediately part 3 and part 4 were added in parallel in 4 hrs. 30 Min. At 138 ° C evenly. After the addition, the reaction mixture was kept at 138 ° C for 30 min. Finally, Part 5 and Part 6 were added uniformly in 1 hr. 30 Min. At 138 ° C in parallel. After the addition, the reaction mixture was again held at 138 ° C for 1 hr. After cooling to 110 ° C, the reaction mixture was bottled. This gave a slightly yellowish, highly viscous polyacrylate solution. 552 g of this solution were weighed into a stirring apparatus under nitrogen and heated to 70 ° C. After homogenization, 471 g of the solution from Preparing Example la were added and the mixture was again homogenized at 70 ° C. for 30 minutes, followed by the addition of 14.6 g of dimethylethanolamine. After stirring for a further 30 minutes at 70 ° C., 466 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solid content: 46.1% by weight

Acid number (100%): 16.3 mg KOH / g

OH content (100%, calculated): 2.1% by weight

Average particle size: 225 nm

Viscosity: 1110 mPas

Production example 3d

Table 3.

Part 1 from Table 3 was weighed into a stirring apparatus under nitrogen and heated to 148 ° C. Thereafter, Part 2 was uniformly added at 128 ° C in 20 min. Subsequently, Part 3 and Part 4 were added in parallel at the same time in 6 hours at 148 ° C. After the addition, the reaction mixture was held at 148 ° C for 60 min. After the addition, the reaction mixture was again held at 148 ° C for 1 hr. After cooling to 80 ° C, the polyacrylate solution was bottled.

Table 4.

Part 1 of Table 4 was weighed into a stirring apparatus under nitrogen and heated to 144 ° C. Thereafter, part 2 was uniformly added at 144 ° C in 20 min. Subsequently, Part 3 and Part 4 were immediately added in parallel in 4 hrs. 30 Min. At 144 ° C evenly. After the addition, the reaction mixture was held at 144 ° C for 5 min. Finally, Part 5 and Part 6 were added uniformly in 1 hour 30 min. At 144 ° C dosed. After the addition, the reaction mixture was again held at 144 ° C for 1 hr. After cooling to 100 ° C, the reaction mixture was bottled. This gave a slightly yellowish, highly viscous polyacrylate solution. 304 g of this solution were weighed into a stirring apparatus under nitrogen and heated to 70 ° C. After homogenization, 385 g of the solution from preparation example 1a were added thereto and the mixture was again homogenized for 30 min. At 70 ° C., followed by the addition of 11 g of dimethylethanolamine. After stirring for a further 30 minutes at 70 ° C., 324 g of distilled water were stirred into the mixture. After fine adjustment of the viscosity to about 2000 mPas, a dispersion was obtained with the following characteristics:

Solid content: 42.6% by weight

Acid number (100%): 18 mg KOH / g

OH content (100%, calculated): 2.5% by weight

Average particle size: 287 nm

Viscosity: 2030 mPas

Paint tests:

Lacquer tests of Example Dispersion 1 from Preparation Example 1:

Clearcoats were prepared from the following composition:

The uretdione dispersion of Preparation Example 1 was dispersed in water and then mixed in a speed mixer (2000 rpm) with Bayhydrol A2695. Heloxy Modifier TP was added, then 1,2,4-Na triazolate (10% in water) and DBU (10% in water, freshly mixed) were added. The mixture was again mixed with a speed mixer (2000 rpm) and allowed to stand on the bench for 30 minutes for foam reduction.

The mixture was applied to glass or to a normalized coil test panel (Coil Coating black - CS 200570, Heinz Zanders Prüf-Blech-Logistik) with a coating bar with a layer thickness of 150-180 μm (wet). The plates were dried at room temperature for 5 minutes and then baked at 100 ° C for 30 minutes. The films obtained were evaluated by application technology and an IR spectrum was recorded.

Example 4: Formulations and Comparative Formulations with Example Dispersion 1

V = Comparative Example, not according to the invention

FG = solids content in% Application Tests / Physical Properties of Paints from Example 4:

V = Comparative Example, not according to the invention

Curing conditions unless explicitly stated otherwise 30 min at 100 ° C

1 = uretdione IR intensity of the peak with peak max. Between 1750 and 1800 cm ¹ in%

2 = against Xy / MPA / EA / Ac on plate for 5 minutes

³ = against water, on glass for 1 hour

Lacquer tests of Example Dispersion 2:

Clearcoats were prepared from the following composition:

To the uretdione dispersion of Preparation Example 2 were added Heloxy Modifier TP, 1,2,4-Na-triazolate (10% in water) and DBU (10% in water, freshly mixed) and the resulting mixture was stirred in a speed mixer (2000 rpm) and then allowed to stand for 30 min to reduce the foam.

The mixture was applied to glass or sheet with a coating knife having a layer thickness of 150-180 μm (wet). The plates were dried at room temperature for 5 minutes and then baked at 100 ° C for 30 minutes. The resulting coatings were evaluated by application technology and an IR spectrum was recorded.

Example 5 Comparative Experiments and Experiments with Formulations with Example Dispersion 2

V = Comparative Example, not according to the invention

EG = solids content (%) Application Tests / Physical Properties of the Paints from Example 5:

V = Comparative Example, not according to the invention

Curing conditions unless explicitly stated otherwise 30 min at 100 ° C

2 = against Xy / MPA / EA / Ac on plate for 5 minutes

³ = against water, on glass for 1 hour

Lacquer Testing of Dispersions of Preparation Examples 3a-d:

Clearcoats were prepared from the following composition:

The uretdione dispersion from Preparation Examples 3 ad was in a speed mixer (2000 rev / min) with the uretdione dispersion of Preparation Example 1, Heloxy Modifier TP, 1,2,4-Na triazolate (10% in water) and DBU (10% in water, freshly mixed). The mixture was allowed to stand for 30 minutes to reduce foam.

The mixture was applied to glass or sheet with a coating knife having a layer thickness of 150-180 μm (wet). The plates were dried at room temperature for 5 minutes and then baked at 100 ° C for 30 minutes. The resulting coatings were evaluated by application technology and recorded an IR spectrum.

Example 6 Comparative Experiments and Experiments with Formulations from Preparation Example 3a-d:

V = Comparative Examples

FG = solids content (%)

Application Tests / Physical Properties of the Coatings from Example 6:

V = Comparative Example, not according to the invention

Curing conditions unless explicitly stated otherwise 30 min at 100 ° C

2 = against Xy / MPA / EA / Ac on plate for 5 minutes

³ = against water, on glass for 1 hour

V = Comparative Example, not according to the invention

Curing conditions unless explicitly stated otherwise 30 min at 100 ° C

² = against Xy / MPA / EA / Ac on plate for 5 minutes

³ = against water, on glass for 1 hour

The curing reaction can be monitored by observing the ring opening of the uretdione by IR spectroscopy. With the combination of sodium triazolate, DBU and heloxy modifier TP, the IR uretdione peak has almost disappeared (<4% relative to the height of the uretdione peak of the dried starting material). Pendulum hardness also increases with the effectiveness of the catalyst mixture. The resistance to xylene, MPA, EA and acetone should be at least 1/1/2/4, the water resistance must be at least 1-2. Both resistances can only be obtained by the catalyst mixture. In example 6 it can be seen that an equimolar amount of uretdione to alcohol (entries 13 to 16) leads to much higher hardnesses and better resistances than an excess of alcohol (entries 9 to 12).

Claims

claims

1. Catalyst system comprising

B) at least one acid scavenger containing at least one epoxy group; and

C) at least one containing an N, N, N'-trisubstituted amidine structure,

Catalyst having an amidine group content of 12.0 to 47.0 wt.%, Calculated as CN2 with molecular weight = 40.

2 catalyst system according to claim 1, characterized in that the at least one compound A) is selected from pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole and benzotriazole and salts thereof.

3. A catalyst system according to claim 1 or 2, characterized in that the at least one acid scavenger B) is selected from aliphatic or aromatic alcohols, diols, polyols, ethers and acids containing at least one epoxy group.

4. Catalyst system according to one of the preceding claims, characterized in that the at least one containing an N, N, N'-trisubstituted amidine structure, catalyst having an amidine group content of 12.0 to 47.0 wt .-%, calculated as CN2; Molecular weight = 40, C) is selected from optionally substituted alkyl-, aralkyl- or allyl-containing amidine bases, wherein the CN double bond of the amidine structure may be both part of an open-chain molecule and part of a cyclic or bicyclic system or also be arranged exocyclically on a ring system can, or any mixtures of such amidines.

5. Catalyst system according to one of the preceding claims, characterized in that A) to B) in a mass ratio of 1: 1 to 10: 1 and / or A) to C) in a mass ratio of 0.5: 1 is present to 5: 1 and / or B) to C) in a mass ratio of 1: 1 to 1: 10 is present.

6. A kit comprising a catalyst system according to any one of claims 1 to 5 and separated therefrom an aqueous Uretdiondispersion, which is characterized in that it has an acid number of 1 to 100 mg KOH / g and also at least one carboxyl group.

7. Kit according to claim 6, characterized in that the equivalent ratio of uretdione to hydroxy groups used is 0.5: 1 to 1: 0.5.

8. A process for producing a polyurethane layer, comprising the steps

i) providing an aqueous Uretdiondispersion having an acid number of 1 to 100 mg

KOH / g and at least one carboxyl group;

ii) adding the catalyst system according to any one of claims 1 to 5;

iii) applying the mixture obtained under ii) to a substrate;

iv) drying the mixture from step iii), and

v) curing the mixture from step iv) with heat up to 120 ° C for up to 180

Minutes.

9. polyurethane layer, in particular polyurethane film, obtainable by a method according to claim 8.

10. Use of a catalyst system according to any one of claims 1 to 5 for curing aqueous Uretdiondispersionen having an acid number of 1 to 100 mg KOH / g and at least one carboxyl group and / or for the production of paints or coatings, in particular polyurethane films.