DE10243029A1 - Uretdione group containing compounds containing up to 10 mol.% isocyanurate structure, useful for polyurethanes, are prepared by dimerization of (cyclo)aliphatic isocyanates having exclusively secondary and/or tertiary isocyanate groups - Google Patents

Abstract

Uretdione group containing compounds (I) containing up to 10 mol.% isocyanurate structure (with respect to the sum of uretdione and isocyanurate groups) are prepared by dimerization of aliphatic and/or cycloaliphatic isocyanates (II) having exclusively secondary and/or tertiary isocyanate groups. An Independent claim is included for a process for the dimerization of isocyanates (II) in the presence of salt-type oligomerization catalysts that contain a 1,2,3- and/or 1,2,4-triazolate anion.

Description

The invention relates to new uretdione groups containing polyaddition compounds, a process for their preparation and their use as a starting component in the manufacture of polyurethane materials, especially as crosslinkers for heat-crosslinkable Powder coatings.

As a crosslinker free of blocking agents for high weatherproof Polyurethane (PUR) powder find increasingly today Polyaddition compounds containing uretdione groups. The principle of crosslinking for these compounds is thermal cleavage the uretdione structures into free isocyanate groups and their subsequent reaction used with a hydroxy functional binder.

The uretdione powder coating crosslinkers available on the market today are all based on linear dimerizates of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate; IPDI). Although experience with blocked PU powder coating crosslinkers shows that products based on 4,4'-diisocyanatodicyclohexylthane have advantageous properties compared to the corresponding IPDI crosslinkers, for example they have a higher reactivity and lead to coatings with significantly higher elasticity (cf. e.g. EP-A 517 028 ), uretdione powder coating crosslinkers of 4,4'-diisocyanatodicyclohexylthane are not yet known. A number of publications, such as the EP-A 639 598 . EP-A 669 354 . EP-A 720 994 . EP-A 818 482 . EP-A 818 483 . EP-A 818 484 . DE-A 197 28 855 , WO 99/11690, EP-A 1 024 158 . EP-A 1 063 251 or EP-A 1 083 209 , 4,4'-diisocyanatodicyclohexylmethane is also mentioned as a possible starting diisocyanate in a long list of diisocyanates suitable for the production of uretdione crosslinkers, but none of these publications contains any concrete description of a corresponding product. This is due to the fact that it has so far not been possible with the dimerization catalysts belonging to the prior art to produce an at least largely isocyanurate group-free uretdione polyisocyanate from 4,4'-diisocyanatodicyclohexylmethane, as is required as a starting compound for uretdione powder coating crosslinkers.

While for the linear catalytic dimerization of aliphatic and / or cycloaliphatic diisocyanates which have at least one primarily bound isocyanate group, such as 1,6-diisocyanatohexane (HDI) or 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate; IPDI , different procedures exist (e.g. EP-A 45 995 . EP-A 317 744 . EP-A 735 027 and EP-A 896 973 ), isocyanurate group-free uretdione polyisocyanates made from aliphatic and / or cycloaliphatic diisocyanates with only secondary and / or tertiary bonded isocyanate groups, such as 4,4'-diisocyanatodicyclohexylhexane, have so far not been known. The usual dimerization catalysts show no or such a low activity compared to such diisocyanates that even with the use of very high catalyst concentrations, the corresponding dimerizates cannot be produced, or can only be produced in a negligibly low yield.

The production of the uretdione groups according to the invention containing polyaddition products was only possible in that succeeded in creating a highly reactive and selective catalyst for the dimerization of Diisocyanates with only secondary and / or tertiary to find bound isocyanate groups, which makes it possible to a large extent linear, preferably isocyanurate-free uretdione polyisocyanates manufacture.

The production of uretdione polyisocyanates from aliphatic and / or cycloaliphatic diisocyanates exclusively secondary and / or tertiary bound isocyanate groups is within the scope of the present invention unclaimed. It is done by catalytic dimerization in the presence of special salt-like oligomerization catalysts, which contain 1,2,3- and / or 1,2,4-triazolate structures in the anion, and is the subject of a parallel German patent application.

Object of the present invention are uretdione group-containing polyaddition compounds obtainable from Implementation of uretdione polyisocyanates from diisocyanates with only secondary and / or tertiary bound isocyanate groups, which have a molar proportion of isocyanurate structures, based on the sum of uretdione and isocyanurate groups, of maximum Have 10% with opposite Isocyanate reactive compounds.

• A) Uretdionpolyisocyanate aus Diisocyanaten mit ausschließlich sekundär und/oder tertiär gebundenen Isocyanatgruppen, die einen molaren Anteil an Isocyanuratstrukturen, bezogen auf die Summe an Uretdion- und Isocyanuratgruppen, von maximal 10 % aufweisen, gegebenenfalls unter Mitverwendung von
• B) weiteren Diisocyanaten und/oder Polyisocyanaten in einer Menge von bis zu 70 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten A) und B), mit
• C) Polyofen des Molekulargewichtsbereiches von 62 bis 2000 und gegebenenfalls
• D) weiteren gegenüber Isocyanatgruppen reaktiven, monofunktionellen Verbindungen in einer Menge von bis zu 40 Gew.-%, bezogen auf das Gesamtgewicht der Komponenten C) und D),

unter Einhaltung eines Äquivalentverhältnisses von Isocyanatgruppen zu gegenüber Isocyanaten reaktiven Gruppen von 1,8 : 1 bis 0,6 : 1 umgesetzt werden.The invention also relates to a process for the preparation of these polyaddition compounds, in which

• A) Uretdione polyisocyanates from diisocyanates with only secondary and / or tertiary bonded isocyanate groups, which have a molar proportion of isocyanurate structures, based on the sum of uretdione and isocyanurate groups, of at most 10%, optionally with the use of
• B) further diisocyanates and / or polyisocyanates in an amount of up to 70% by weight, based on the total weight of components A) and B)
• C) Polyofen of the molecular weight range from 62 to 2000 and optionally
• D) further monofunctional compounds which are reactive toward isocyanate groups in an amount of up to 40% by weight, based on the total weight of components C) and D),

while maintaining an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 1.8: 1 to 0.6: 1.

Finally, the subject of the invention is also the use of these uretdione group-containing polyaddition compounds as starting components in the production of polyurethane plastics, in particular as crosslinking components in heat-crosslinkable two-component polyurethane powder coatings when coating any heat-resistant substrates the methods of powder coating technology.

Starting compounds A) for the process according to the invention are uretdione polyisocyanates such as those obtained by catalytic dimerization a part of the isocyanate groups of simple diisocyanates with only secondary and / or tertiary bound isocyanate groups and preferably subsequent separation the unreacted excess diisocyanate, for example by thin film distillation, get preserved. To prepare the starting compounds A) aliphatic and / or cycloaliphatic diisocyanates with only secondary and / or tertiary bound isocyanate groups suitable by any method, e.g. by phosgenation or by a phosgene-free route, for example by splitting urethane. The term aliphatic or cycloaliphatic refers only to the type of Carbon atoms bearing isocyanate groups, i.e. in the molecule can well aromatic structures are also present. Suitable starting diisocyanates are for example 1,3- or 1,4-diisocyanatocyclohexane, 1,4-diisocyanato-3,3,5-trimethylcyclohexane, 1,3-diisocyanato-2-methylcyclohexane 1,3-diisocyanato-4-methylcyclohexane, 1,8-diisocyanato-p-menthan, 4,4'-diisocyanato-1,1'-bi (cyclohexyl), 4,4'-diisocyanato-3,3'-dimethyl-1,1'-bi (cyclohexyl), 4,4'-diisocyanato-2,2 ', 5,5'-tetramethyl-1,1'-bi ( cyclohexyl), 4,4'-diisocyanatodicyclohexylmethane, 4,4'-diisocyanato-3,3'-dimethyldicyclohexyhnethan; 4,4'-diisocyanato-3,3 ', 5,5'-tetramethyldicyclohexyhnethan, 1.3 Diisocyanatoadamantan, 1,3-dimethyl-5,7-diisocyanatoadamantane, 1,3- and 1,4-bis (1-isocyanato-1-methylethyl) benzene (TMXDI or bis (4- (1-isocyanato-1-methylethyl) phenyl) carbonate as well Mixtures of such diisocyanates. Other diisocyanates which are also suitable with exclusively secondary and / or tertiary bound isocyanate groups can also be found, for example, in Justus Liebigs Annalen der Chemie Volume 562 (1949) pp. 75-136.

Preferred diisocyanates for production of the starting compounds A) are 4,4'-diisocyanatodicyclohexylmethane, 4,4'-diisocyanato-3,3'-dimethyldicyciohexyl methane, 1,3- or 1,4-diisocyanatocyclohexane and / or TMXDI. Most notably preferred diisocyanate is 4,4'-diisocyanatodicyclohexylmethane.

The preparation of the starting compounds A) from the diisocyanates mentioned, for example, as in of the parallel German patent application No. ... described by catalytic dimerization in the presence of special salt-like oligomerization catalysts, which contain 1,2,3- and / or 1,2,4-triazolate structures in the anion.

The available in this way Starting compounds A) have, depending on the type of starting diisocyanates chosen and the chosen one Degree of oligomerization has an isocyanate group content of 11.2 to 25.4% by weight, preferably from 12.8 to 23.9% by weight, particularly preferably from 13.5 to 16.0% by weight, and contain less than 5% by weight, preferably less than 2% by weight, particularly preferred less than 1% by weight of monomeric diisocyanates. The molar fraction of isocyanate structures in the starting compounds A) on the sum of uretdione and isocyanate groups, maximum 10%, preferably at most 8% and particularly preferably at most 5%.

If appropriate, further diisocyanates and / or polyisocyanates B) can also be used in the process according to the invention. These are, for example, any monomeric diisocyanates with aliphatic, cycloaliphatic, araliphatic and / or aromatically bound isocyanate groups, in particular those of the molecular weight range 140 to 400, such as 1,4-diisocyanatobutane, 1,6-diisocyanatohexane (HDI), 1.5 -Diisocyanato-2,2-dimethylpentane, 2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, IPDI, 1-isocyanato-1-methyl-4 (3rd ) -isocyanatomethylcyclohexane, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate, diphenylmethane-2,4'- and / or -4,4'-diisocyanate, naphthylene-l, 5- diisocyanate, the diisocyanates described above in the preparation of the starting compounds A) with exclusively secondary and / or tertiary bonded isocyanate groups or any mixtures of such diisocyanates, and also polyisocyanates prepared by modification of these monomeric diisocyanates with uretdione, isocyanate, urethane, allophanate and biuret - And / or oxadiazinetrione structure, such as s ie for example in the DE-A 1 670 666 . 3,700,209 and 3,900,053 or that EP-A 336 205 and 339 396 are described by way of example.

These diisocyanates and / or polyisocyanates B) are, if at all, in amounts of up to 70 % By weight, preferably up to 50% by weight, based on the total weight of components A) and B). Preferred starting components B), such as can optionally be used in the process according to the invention, are diisocyanates and polyisocyanates with aliphatic and / or cycloaliphatic isocyanate groups. Particular preference is given to the use of monomeric HDI, IPDI and / or 4,4'-diisocyanatodicyclohexylmethane or polyisocyanates made of HDI and / or IPDI with uretdione and / or isocyanurate structure.

Starting compounds C) for the process according to the invention are polyols of the molecular weight range from 62-2000, the one (medium) OH functionality of at least 2.0 or mixtures of such polyols.

Suitable polyols C) are, for example polyhydric alcohols in the molecular weight range 62 to 400, such as 1,2-ethanediol, 1,2- and 1,3-propanediol, the isomeric butanediols, Pentanediols, hexanediols, heptanediols and octanediols, 1,2- and 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol or 4,4 '- (1-methylethylidene) biscyclohexanol, 1,2,3-propanetriol, 1,1,1-trimethylolethane, 1,2,6-hexanetriol, 1,1,1-trimethylolpropane, 2,2-bis (hydroxymethyl) -1,3-propanediol or 1,3,5-tris (2-hydroxyethyl) isocyanate, but also ester or ether alcohols, such as hydroxypivalinsäweneopentylglykolester, Diethylene glycol or dipropylene glycol.

Suitable starting compounds C) are also known polyhydroxyl compounds of polyester, Polycarbonate, polyester carbonate or polyether type.

Suitable as polyol components C) Polyester polyols are, for example, those of a number average Molecular weight from 200 to 2000, preferably from 250 to 1500, with a hydroxyl group content of 1 to 21 wt .-%, preferably 2 to 18 wt .-%, as they are known in a manner by reacting polyhydric alcohols, for example those above mentioned the molecular weight range 62 to 400, with insufficient amounts of polyvalent carboxylic acids, corresponding carboxylic acid anhydrides, corresponding polycarboxylic acid esters lower alcohols or lactones.

The for the production of polyester polyols acids used or acid derivatives can be aliphatic, cycloaliphatic and / or aromatic in nature and optionally, e.g. by halogen atoms, substituted and / or unsaturated his. Examples of suitable acids are polyvalent carboxylic acids of the molecular weight range 118 to 300 or their derivatives, for example Succinic acid, adipic acid, sebacic, phthalic acid, isophthalic acid, trimellitic acid, Phthalsäweanhydrid, tetrahydrophthalic maleic acid, maleic anhydride, dimeric and trimeric fatty acids, dimethyl terephthalate and terephthalic acid bisglycol esters.

For the production of polyester polyols can also any mixtures of these starting compounds mentioned as examples be used.

One preferred as polyol component C) Type of polyester polyols used are as they are in a manner known per se from lactones and simple polyvalent ones Alcohols such as the examples mentioned above as starter molecules under ring opening have it made. Suitable lactones for the production of these polyester polyols are, for example, β-propiolactone, γ-butyrolactone, γ- and δ-valerolactone, ε-caprolactone, 3,5,5- and 3,3,5-trimethylcaprolactone or any mixture of such Lactones.

Polyhydroxyl compounds suitable as polyols C) of the polycarbonate type are in particular the polycarbonate diols known per se represents how, for example, by implementing bivalent Alcohols, such as those listed above polyhydric alcohols in the molecular weight range 62 to 400 are exemplary with dialkyl or diaryl carbonates, e.g. Dimethyl or diphenyl carbonate, or have phosgene produced.

Polyhydroxyl compounds of the polyester carbonate type which are suitable as polyols C) are, in particular, the diols which are known per se and have ester groups and carbonate groups, as described, for example, in accordance with the teachings of DE-A 1 770 245 can be obtained by reacting dihydric alcohols with lactones of the type exemplified above, in particular ε-caprolactone, and then reacting the resulting polyester diols with diphenyl carbonate.

Polyether polyols suitable as polyols C) are in particular those of a number average molecular weight from 200 to 2000, preferably 250 to 1500, with a hydroxyl group content from 1.7 to 25% by weight, preferably 2.2 to 20% by weight, as described in are accessible in a manner known per se by alkoxylation of suitable starter molecules. Any multivalent can be used to prepare these polyether polyols Alcohols such as those described above in the molecular weight range 62 to 400, as starter molecules be used. For alkylene oxides suitable for the alkoxylation reaction are in particular Ethylene oxide and propylene oxide in any order or can also be used in a mixture in the alkoxylation reaction.

Suitable polyether polyols are also the polyoxytetramethylene glycols known per se, such as, for example according to Angew. Chem. 72, 927 (1960) obtained by polymerizing tetrahydrofuran can be.

Also suitable as starting compounds C) are dimer diols, as are known in the art for example by hydrogenating dinate fatty acids and / or their esters according to the in DE-A 1 768 313 or other in EP-A 720 994 Page 4, line 33 to line 58 described methods can be produced.

Preferred starting compounds C) for the method according to the invention are the above-mentioned simple polyhydric alcohols in the molecular weight range 62 to 400, the polyester or polycarbonate polyols mentioned and any mixtures of these polyol components.

However, particularly preferred those above within the list of simple polyhydric alcohols mentioned diols of the molecular weight range 62 to 300, polyester diols or polycarbonate diols in the molecular weight range 134 to 1200 or mixtures thereof.

Very particularly preferred starting compounds C) for the inventive method are mixtures of the polyester diols mentioned with up to 80% by weight, preferably up to 60 wt .-%, based on the total weight of the Polyols C) used on simple diols in the molecular weight range 62 to 300.

In the method according to the invention can optionally also other reactive towards isocyanate groups monofunctional compounds D) can also be used. This is about it is in particular aliphatic or cycloaliphatic monoamines, such as methylamine, ethylamine, n-propylamine, isopropylamine, the isomers Butylamines, pentylamines, hexylamines and octylamines, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, n-octadecylamine, cyclohexylamine, the isomeric methylcyclohexylamine and also aminomethylcyclohexane, secondary monoamines, such as dimethylamine, Diethylamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, Bis (2-ethylhexyl) amine, N-methyl and N-ethylcyclohexylamine as well Dicyclohexylamine or monoalcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols, Octanols and nonanols, n-decanol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, Cyclohexanol, the isomeric methylcyclohexanols and hydroxymethylcyclohexane.

These monofunctional connections D) come, if any, in amounts of up to 40% by weight, preferably 25% by weight towards the total amount of Isocyanate-reactive starting compounds C) and D) are used.

Preferred starting compounds D) for the inventive method are the simple aliphatic or cycloaliphatic monoalcohols of the type mentioned.

To carry out the method according to the invention are the uretdione polyisocyanates A), optionally with concomitant use further diisocyanates and / or polyisocyanates B) with the polyols C) and optionally further monofunctional isocyanates reactive Compounds D) in a discontinuous or continuous Process, for example in special equipment such as intensive kneaders or static mixers, in the stated equivalent ratio of Isocyanate groups too Isocyanate-reactive groups from 1.8: 1 to 0.6: 1, preferably 1.6: 1 to 0.8: 1 at a reaction temperature of 40 to 200 ° C, especially preferably from 60 to 180 ° C, preferably until the theoretically calculated NCO content is reached implemented.

The implementation is preferably carried out solvent-free in the melt, but it can of course also in a suitable, across from Solvents inert to isocyanate groups carried out become. Suitable solvents for this less preferred procedures are, for example, those per se known conventional paint solvents such as ethyl acetate, butyl acetate, ethylene glycol monomethyl or ethyl ether acetate, 1-methoxypropyl-2-acetate, acetone, 2-butanone, 4-methyl-2-pentanone, Cyclohexanone, toluene, or their mixtures, but also solvents such as propylene glycol diacetate, diethylene glycol dimethyl ether, diethylene glycol ethyl and butyl ether acetate, N-methylpyrrolidone and N-methylcaprolactam, or mixtures of such solvents.

These may also be used solvent have to after implementation using suitable methods, for example through failures and easy suction, spray drying or melt extrusion in an evaporation screw, from the process product according to the invention be separated.

To accelerate the urethanization reaction can in the method according to the invention the usual catalysts known from polyurethane chemistry are used, for example tert. Amines such as triethylamine, pyridine, methylpyridine, Benzyldimethylamine, N, N-endoethylene piperazine, N-methylpiperidine, Pentamethyldiethylenetriamine, N, N-dimethylaminocyclohexane, N, N'-dimethylpiperazine or metal salts such as iron (III) chloride, zinc chloride, zinc octoate, Zinc 2-ethyl caproate, zinc acetylacetonate, tin (II) octoate, tin (II) ethyl caproate, Tin (II) palmitate, dibutyltin (IV) dilaurate and molybdenum glycolate.

These catalysts may come in amounts of 0.001 to 2.0% by weight, preferably 0.01 to 0.2% by weight, based on the total amount of starting compounds used for use.

Regardless of the type of implementation, the process according to the invention gives, depending on the selected equivalent ratio of isocyanate groups to isocyanate-reactive groups, polyaddition compounds containing uretdione groups and containing free isocyanate groups (calculated as NCO; molecular weight = 42) of 0 to 6.0% by weight. , preferably from 0 to 5.0% by weight, particularly preferably from 0 to 4.0% by weight, a uretdione group content (calculated as C ₂ N ₂ O ₂ ; molecular weight = 84) from 3 to 25% by weight. %, preferably from 5 to 17% by weight, particularly preferably from 6 to 17% by weight, and a content of monomeric diisocyanates of less than 1.0% by weight, preferably less than 0.5% by weight %, particularly preferably less than 0.3% by weight, which is solid below 40 ° C. and liquid above 125 ° C. are and in particular have a melting point or melting range determined according to differential thermal analysis (DTA), which is within a temperature range from 40 to 110 ° C, particularly preferably within the temperature range from 50 to 100 ° C.

The polyaddition compounds according to the invention provide valuable starting materials for the production of polyurethane plastics by the isocyanate polyaddition process. You will find in particular Use as a crosslinking component in thermosetting blocking agent-free PUR powder coatings. They are similar to commercially available ones built-up uretdione powder coating crosslinkers based on IPDI increased Reactivity and deliver coatings with improved chemical and mechanical resistance, especially a higher one Elasticity.

Suitable reactants for the polyaddition compounds according to the invention are fundamental all binders known from powder coating technology with isocyanates reactive Groups such as Hydroxyl, carboxyl, amino, thiol, urethane or urea groups. However, hydroxy-functional ones are preferred Powder coating binders are used that are solid and below 40 ° C above 130 ° C liquid are. The softening temperatures of these hydroxy-functional resins - determined after differential thermal analysis (DTA) - are preferably within the temperature range from 30 to 120 ° C, particularly preferably within the temperature range from 35 to 110 ° C.

Their hydroxyl numbers are in general between 20 and 200, preferably between 30 and 130 and their number average (from the functionality and the molecular weight which can be calculated from the hydroxyl content in general between 400 and 10,000, preferably between 1,000 and 5,000.

Such powder coating binders are, for example, hydroxyl-containing polyesters, polyacrylates or polyurethanes, as described in the above-mentioned prior art publications, for example EP-A 45 998 , or EP-A 254 152 are described, but also any mixtures of such resins.

To make a ready-to-use The polyaddition compounds according to the invention become powder coating mixed with suitable hydroxy-functional powder coating binders, optionally with other auxiliaries and additives, such as e.g. catalysts Pigments, fillers or leveling agents, and for example in extruders or Kneading above the melting range of the individual components, for example 70 to 130 ° C, preferably 70 to 110 ° C, united into a homogeneous material.

The polyaddition compounds according to the invention and the hydroxy-functional binders come in such proportions used that for each hydroxyl group 0.6 to 2.0, preferably 0.6 to 1.4, particularly preferably 0.8 to 1.2, isocyanate groups are eliminated, with isocyanate groups in the polyaddition compounds according to the invention the sum of isocyanate groups present in dimeric form as uretdione groups and free isocyanate groups is understood.

The catalysts which may optionally be used to accelerate curing are the usual compounds known from polyurethane chemistry, as have already been described above in the process according to the invention for accelerating the reaction, or amidines, such as, for example, 1,5-diazabicyclo [4.3.0] non -5-ene (DBN), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and 1,2-dimethyl-tetrahydropyrimidine, which are based on the teaching of EP-A 803 524 have proven to be particularly suitable catalysts for lowering the baking temperatures of uretdione powder coating crosslinkers. These catalysts may optionally be present in amounts of 0.01 to 5.0% by weight, preferably 0.05 to 2.0% by weight, based on the total amount of organic binder, ie polyaddition compounds according to the invention in combination with the hydroxy-functional powder coating binders any other auxiliaries and additives used may be added.

Like IR spectroscopic examinations show react under the conditions of powder coating production optionally in the polyaddition compounds according to the invention existing free isocyanate groups practically completely. The one after cooling the resulting isocyanate group-free solid subsequently ground and by sieving the grain proportions above the desired grain size, for example above 0.1 mm, exempt.

The ready to spray produced in this way Powder coating can be made according to usual Powder application processes, e.g. electrostatic powder spraying or Vertebral sinter, on those to be covered Substrates are applied. According to the invention, any heat-resistant can Substrates, such as those made of metals, wood or glass, be coated.

The coatings are hardened by heating Temperatures from 110 to 220 ° C, preferably 130 to 200 ° C for example during a period of about 10 to 30 minutes. You get hard and elastic coatings with good resistance to solvents and chemicals, which is characterized by an excellent course and very high gloss distinguished.

In the following, all percentages, with the exception of the gloss values, relate to the weight. The uretdione group contents given were determined by hot titration (refluxing for 30 minutes with excess di-n-butylamine in 1,2-dichlorobenzene and subsequent back titration with hydrochloric acid).

Preparation of the starting compounds A)

1. Preparation of a Dimerization Catalyst:

Trihexyltetradecylphosphonium-1,2,4-triazolate

In a three-necked flask with mechanical stirrer, internal thermometer and reflux condenser, 180 g of a 30% methanolic sodium methanolate solution, corresponding to 1.0 mol of sodium methoxide, were placed at room temperature under dry nitrogen. A solution of 69 g (1.0 mol) of 1,2,4-triazole in 200 ml of methanol was added dropwise within 45 min and the reaction mixture was stirred for 12 hours. Was then added dropwise over 1 hour a solution of 518 g (1.0 mol) trihexyltetradecylphosphonium chloride (CYPHOS ^® 3653, Fa. Cytec Industries, Neuss, Germany) dissolved in 60 g of methanol. Immediately after the beginning of the phosphonium salt addition, the excretion of sodium chloride began. The reaction mixture was stirred overnight at room temperature, the precipitated sodium chloride was filtered off and the solvent was then distilled off in a commercially available thin-film evaporator at a temperature of 50 ° C. and a pressure of about 0.3 mbar. The residue was filtered again and 510 g (yield: 92.6% of theory) of trihexyltetradecylphosphonium-1,2,4-triazolate were obtained as a clear, almost colorless liquid with a viscosity of 570 mPas (23 ° C.) and one Refractive index n 20 / D of 1.4821. The residual methanol content was 0.1% by weight.

uretdione polyisocyanate from 4,4'-diisocyanatodicyclohexylmethane A1)

1000 g (3.82 mol) of 4,4'-diisocyanatodicyclohexylmethane were degassed for 1 hour under reduced pressure (2 mbar), then aerated with dry nitrogen and heated to 30 ° C. Subsequently, 12 g (0.022 mol) of the above-described dimerization catalyst trihexyltetradecylphosphonium-1,2,4-triazolate were continuously added over a reaction time of 3 hours with the aid of an infusion laboratory pump (KDS 100, KD Scientific, Boston). After a subsequent stirring time of 30 minutes, the NCO content in the reaction mixture was 26.2%, corresponding to a degree of oligomerization of 17.1%. The catalyst was deactivated by adding 4.6 g (0.022 mol) of dibutyl phosphate and the resulting clear, colorless mixture was freed from excess diisocyanate using a thin-layer evaporator at a temperature of 155 ° C. and a pressure of 0.2 mbar. A highly viscous, almost colorless uretdione polyisocyanate with a free NCO group content of 14.2%, a monomeric 4,4'-diisocyanatodicyclohexylmethane content of 0.5% and a color number (APHA), determined on a 10% strength, was obtained Solution in methylene chloride, of 11. According to ¹³ C-NMR spectroscopy, the product only contained uretdione groups, and isocyanurate structures were not detectable. The content of uretdione groups, determined by hot titration, was 17.8%.

uretdione polyisocyanate from 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane A2)

1000 g (3.45 mol) of 4,4'-diisocyanato-3,3'-dimethyldicyclohexyhnethan were degassed in vacuo (2 mbar) for 1 hour, then aerated with dry nitrogen and heated to 30 ° C. Subsequently, 10 g (0.018 mol) of the above-described dimerization catalyst trihexyltetradecylphosphonium-1,2,4-triazolate were added continuously over a reaction time of 3 hours with the aid of an infusion laboratory pump (KDS 100, KD Scientific Boston). After stirring for a further 30 minutes, the NCO content in the reaction mixture was 25.1%, corresponding to a degree of oligomerization of 13.4%. The catalyst was then deactivated by adding 4.6 g (0.022 mol) of dibutyl phosphate and the resulting clear, colorless mixture was freed from excess diisocyanate using a thin-film evaporator at a temperature of 155 ° C. and a pressure of 0.2 mbar. A highly viscous, almost colorless uretdione polyisocyanate with a free NCO group content of 13.3%, a monomeric 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane content of 0.6% and a color number (APHA) was obtained, determined on a 10% solution in methylene chloride, of 29. According to ¹³ C-NMR spectroscopy, the product only contained uretdione groups, and isocyanurate structures were not detectable. The content of uretdione groups, determined by hot titration, was 15.9%.

Preparation of starting compounds C)

Having ester groups Diol C 1)

901 g of 1,4-butanediol and 1712 g of ε-caprolactone were mixed at room temperature under dry nitrogen, mixed with 0.3 g of stannous octoate and then heated to 160 ° C. for 5 h. After cooling to room temperature, a colorless liquid product was obtained with the following characteristics: η (23 ° C): 180 mPas OH number: 416 mg KOH / g free ε-caprolactone: 0.1% number average molecular weight (from OH number calculated): 269

Having ester groups Diol C 2)

761 g 1,3-propanediol and 1712 g ε-caprolactone were mixed at room temperature under dry nitrogen, 0.3 g of tin (II) octoate were added and the mixture was then heated to 160 ° C. for 5 h. After cooling down A colorless liquid product was obtained at room temperature with the following Characteristics:

η (23 ° C): 190 mPas OH number: 449 mg KOH / g free ε-caprolactone: 0.3% number average Molecular weight (calculated from OH number): 249

Having ester groups Triol C 3)

1 341 g 1,1,1-trimethylolpropane (TMP) and 1 712 g ε-caprolactone were mixed at room temperature under dry nitrogen, 0.3 g of tin (II) octoate were added and the mixture was then heated to 160 ° C. for 5 h. To cooling down at room temperature, a colorless liquid product was obtained with the following Characteristics:

η (23 ° C): 2400 mPas OH number: 546 mg KOH / g free ε-caprolactone: 0.2% number average Molecular weight (calculated from OH number): 308

Example 1

360.0 g (1.22 eq) of the uretdione polyisocyanate A1) were placed under dry nitrogen, with 0.26 g of dibutyltin (N) dilaurate (DBTL) as a catalyst and heated to 80 ° C. Then gave a mixture of 131.3 g (0.98 eq) of the Diol C1) containing ester groups, 5.5 g (0.12 eq) 1,4-butanediol and 15.9 g (0.12 val) of 2-ethyl-1-hexanol, the temperature being due to the heat of reaction released up to 125 ° C rise. After a stir of 5 minutes the NCO content of the reaction mixture was one Value dropped by 0.9. The melt was on for cooling Cast sheet, and a uretdione group-containing invention was obtained Polyaddition compound in the form of a colorless solid resin. The Product had the following characteristics

NCO content: 0.9 Uretdione content (Calc.): 12.5% monomeric 4,4'-Diisocyanatodicyclohexyhnethan: 0.31 Melting point: 95-100 ° C

Example 2

360.0 g (1.22 eq) of the uretdione polyisocyanate A1) were placed under dry nitrogen, 0.25 g of DBTL was added as a catalyst and the mixture was heated to 80.degree. A mixture of 122.0 g (0.98 eq) of the diol C2) containing ester groups and 5.5 g (0.12 eq) of 1,4-butanediol was then added within 10 min and the mixture was stirred at a maximum reaction temperature of 125 ° C until the NCO content of the reaction mixture after about 15 minutes had dropped to a value of 1.2%. The melt was poured onto a metal sheet to cool, and a polyaddition compound according to the invention was obtained as a light yellow solid resin with the following characteristics:

NCO content (. Gef./ber): 1.2 / 1.0% Uretdione content (Calc.): 13.1% NCO content total (calc.): 14.1% NCO functionality: 2.0 monomeric 4,4'-Diisocyanatodicyclohexyhnethan: 0.26% Melting point: 99-110 ° C

Example 3

350.0 g (1.11 eq) of the uretdione polyisocyanate A2) were placed under dry nitrogen, with 0.25 g DBTL added as a catalyst and heated to 80 ° C. Then gave a mixture of 119.7 g (0.89 eq) of the Diol Cl) containing ester groups, 3.4 g (0.11 eq) 1,2-ethanediol and 14.3 g (0.11 va1) 2-ethyl-1-hexanol, the temperature due to the released heat of reaction rose to 118 ° C. After a stir of 10 minutes the NCO content of the reaction mixture was one 0.8% lower. The melt was on for cooling Cast sheet, and a uretdione group-containing invention was obtained Polyaddition compound in the form of a colorless solid resin. The Product had the following characteristics:

NCO content: 0.8% Uretdione content (Calc.): 11.4% monomeric 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane: 0.42 Melting point: 95-100 ° C

Example 4

300.0 g (1.01 eq) of the uretdione group-containing Polyisocyanates A1) were at 50 ° C. mixed with 50.0 g (0.60 eq) HDI under dry nitrogen, subsequently treated with 0.5 g DBTL as a catalyst and heated to 80 ° C. To this mixture, which has a uretdione group content of 15.3% a mixture of 64.6 g (0.48 val) of the diol C 1) containing ester groups, 36.0 g (0.80 val) 1,4-butanediol and 41.6 g (0.32 eq) 2-ethyl-1-hexanol and stirred in a maximum reaction temperature of 122 ° C to the NCO content of the reaction mixture had dropped to a value of 0.7% after about 15 minutes. The melt was poured onto a tray to cool, and one was obtained polyaddition compound according to the invention as a light yellow solid resin with the following characteristics:

NCO content: 0.7% Uretdione content (Calc.): 10.8% monomeric 4,4'-Diisocyanatodicyclohexyhnethan: 0.27% monomeric HDI: 0.09% Melting range: 93-101 ° C

Example 5

300 g (1.01 val) of the uretdione group-containing Polyisocyanates A1) were at 50 ° C. with 30 g (0.16 eq) of a prepared analogously to Example 7 of EP-A 330 966 Isocyanurate polyisocyanate based on HDI containing free isocyanate groups of 21.8%, a monomeric HDI content of 0.1% and an average NCO functionality of 3.5 mixed under dry nitrogen, then with 0.5 g DBTL as catalyst offset and to 80 ° C. heated. This mixture, which has a uretdione group content of 16.2% and had an average NCO functionality of 2.12 a mixture of 24 g (0.23 eq) of the ester groups within 20 min containing triols C 3), 47 g (0.35 eq) of the diol containing ester groups C 1) and 16 g (0.35 eq) 1,4-butanediol and stirred at a maximum reaction temperature from 120 ° C to the NCO content of the reaction mixture to about 15 minutes Value had dropped by 2.8%. The melt was on for cooling poured a sheet, and a polyaddition compound of the invention was obtained as a light yellow solid resin with the following characteristics:

NCO content (. Gef./ber): 2.8 / 2.4% Uretdione content (Calc.): 12.8% NCO content total (calc.): 15.2% NCO functionality: 5.1 monomeric 4,4'-diisocyanatodicyclohexylmethane: 0.33% monomeric HDI: <0.03 % Melting range: 98-107 ° C

Example 6

340.0 g (1.15 eq) of the uretdione polyisocyanate A1) were placed under dry nitrogen, with 0.25 g DBTL added as a catalyst and heated to 80 ° C. Then gave 185.6 g (1.38 eq) of the diol Cl) containing ester groups a portion and stirred the reaction mixture at a maximum reaction temperature of 130 ° C to after about 5 minutes all Had reacted isocyanate groups. The melt became cold poured onto a metal sheet and a polyaddition compound according to the invention was obtained as a pale yellow solid resin with the following characteristics:

NCO content: 0% Uretdione content (Calc.): 11.5% monomeric 4,4'-diisocyanatodicyclohexylmethane: 0.23% Melting point: 103-115 ° C

Example 7: (Comparison, analog EP-A 639 598 )

350.0 g (1.39 eq) of a uretdione group Polyisocyanates based on 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) with a free isocyanate group content of 16.7% and a content of uretdione groups (determined by hot titration) of 20.9% were treated with 0.5 g DBTL under dry nitrogen Catalyst added and to 80 ° C. heated. Subsequently a mixture of 149.3 g (1.11 eq) was added within 20 min of the diol C 1) containing ester groups, 6.3 g (0.14 eq) 1,4-butanediol and 18.2 (0.14 eq) 2-ethyl-1-hexanol and stirred at a reaction temperature by Max. 110 ° C until the NCO content of the reaction mixture drops to about 20 minutes Value had dropped by 0.7%. The melt was on for cooling poured a sheet, and a polyaddition compound of the invention was obtained as a pale yellow solid resin with the following characteristics:

NCO content: 0.7% Uretdione content (Calc.): 14.0% monomeric IPDI: 0.17% Melting range: 94-98 ° C

Example 8 (Use; according to the invention [a] and Comparison [b])

• [a] 26.5 parts by weight of a commercially available hydroxyl-containing polyester (Rucote 182 ^®, Bayer AG) having an OH number of 30 and 24.6 parts by weight of a commercially available hydroxyl-containing polyester (Rucote 194 ^®, Bayer AG) an OH number of 45 with 11.4 parts by weight of the polyaddition compound according to the invention from Example 1, corresponding to an equivalent ratio of total NCO to OH of 1: 1, 1.5 parts by weight of a commercially available leveling agent (Resiflow ^® PV 88, Worlée-Chemie GmbH, Hamburg), 0.5 part by weight of tin (II) palmitate as a catalyst, 0.5 part by weight of benzoin and 35.0 parts by weight of a white pigment (Kronos 2160, Kronos Titan GmbH, Leverkusen) thoroughly mixed and then homogenized in the process section using a PLK 46 Buss co-mixer at 100 rpm and a housing temperature of 100 to 120 ° C. After cooling, the solidified melt was ground and sieved using a classifier mill (ACM 2, Hosokawa Mikropul) with a 90 μm sieve.
• [b] For comparison, 27.0 parts by weight of Rucote ^® 182 and 25.2 parts by weight of Rucote ^® 194 were analogously mixed with 10.3 parts by weight of the polyaddition compound obtained in Comparative Example 6, 1.5 parts by weight. Parts of a commercially available leveling agent (Resiflo ^® PV 88, Worlée-Chemie GmbH, Hamburg), 0.5 parts by weight of tin (II) palmitate as a catalyst, 0.5 parts by weight of benzoin and 35.0 parts by weight of a white pigment (Kronos 2160, Kronos Titan GmbH, Leverkusen). The equivalent ratio of total NCO to OH was also 1: 1.

The two powder coatings thus obtained were shot with an ESB cup gun at a high voltage of 70 KV sprayed onto degreased steel sheets and 15 min each at one Temperature of 160 ° C, 170 ° C and 180 ° C to smooth, white Cured coatings. With layer thicknesses of around 60 μm the following paint properties were found:

Powder coating cross-linked with polyaddition compound

The comparison shows that with the help of the powder coating according to the invention a fully cross-linked paint film even at a lower baking temperature will get who is facing the coating using the known polyaddition compound of the prior art was characterized by a higher elasticity.

Examples 9 to 12 (use, Inventive)

Following the procedure described in example 7, the hydroxyl-containing polyester described in Example 8 of the OH number 30 (Rucote ^® 182, Bayer AG, Leverkusen) and the polyaddition compounds 2 according to the invention, 3, 4 and 5 White pigmented powder coatings were prepared starting from the. The formulated powder coatings were each sprayed onto a degreased steel sheet using an ESB cup gun at a high voltage of 70 KV and cured at 170 ° C. for 15 minutes. The table below shows the compositions (parts by weight) of the powder coating materials and the coating data of the coatings obtained therefrom (layer thickness in each case about 60 μm).

Claims (5)

Polyaddition compounds containing uretdione groups, available by reacting uretdione polyisocyanates from diisocyanates with exclusively secondary and / or tertiary bound isocyanate groups, which have a molar proportion of isocyanurate structures, based on the sum of uretdione and isocyanurate groups, of maximum Have 10% with opposite Isocyanate reactive compounds. Process for the preparation of polyaddition compounds according to claim 1, where A) Uretdione polyisocyanates from diisocyanates with exclusively secondary and / or tertiary bound isocyanate groups, which have a molar proportion of isocyanurate structures, based on the sum of uretdione and isocyanurate groups, of maximum Have 10%, possibly with the use of B) others Diisocyanates and / or polyisocyanates in an amount of up to 70 wt .-%, based on the total weight of components A) and B), with C) Polyols in the molecular weight range from 62 to 2000 and possibly D) further reactive towards isocyanate groups, monofunctional compounds in an amount of up to 40% by weight, based on the total weight of components C) and D), under Compliance with an equivalent ratio from isocyanate groups to opposite Isocyanate reactive groups from 1.8: 1 to 0.6: 1 with each other be implemented. Use of the polyaddition compounds according to claim 1 as starting components in the production of polyurethane plastics. Use of the polyaddition compounds according to claim 1 as starting components in the production of moldings and Moldings. Use of the polyaddition compounds according to claim 1 as starting components in the manufacture of paints and coatings.