DE102005014641A1 - Use of aqueous and/or water soluble blocked polyisocyanate, e.g. in the preparation of coating, which is useful in automobile varnishing, and in burning system for coating e.g. wood and metal - Google Patents

Abstract

Use of aqueous and/or water soluble blocked polyisocyanate compound (I), in the preparation of coating. -Use of aqueous and/or water-soluble blocked polyisocyanate compound of formula (I), in the preparation of coating. A : polyisocyanate; B1>a cationic, anionic and/or nonionic hydrophilizing agent; R1>-R3>H, 1-4C-alkyl or 6-10C-cycloalkyl; R4>1-4C-alkyl, 6-10C-cycloalkyl or 1-14C-aralkyl; X : 1-5; Y1>1-8; and Z : 0-4 (where the equivalent ratio of Y1>-Z is 20:1-1:1). Independent claims are included for: (1) the preparation of (I); and (2) a hydrophilic (I) comprising 100% equivalents of polyisocyanate, 40-90 (preferably 60-85)% equivalents of secondary benzyl amine, 10-40 (preferably 10-25)% equivalents of a hydrophilizing agent, optionally 10-40 (preferably 10-25)% equivalents of difunctional hydroxyl and/or amino groups containing compound, aggregates and auxiliary materials, where the average molar weight is 62-3000 (preferably 62-1500) and the amount of ratio of is 1:0.8-1:1.2, related to the isocyanate compound. [Image].

Description

The The invention relates to the use of aqueous and / or water-dilutable blocked polyisocyanates in self-crosslinking one-component clearcoats.

Of the Use of blocking agents for the temporary protection of isocyanate groups has been known for a long time. Blocked polyisocyanates are used for the production of storage stable at room temperature, heat curable 1-component PUR baking systems used. The blocked polyisocyanates are e.g. with hydroxyl-containing polyesters, polyacrylates, other polymers and other components of paints and coatings like pigments, cosolvents or additives mixed. Another option, at room temperature To obtain storage-stable stoving enamels is the partial blocking the isocyanate groups of polymers containing both blocked isocyanates as well as hydroxyl groups.

The main compounds that block polyisocyanates are used ε-caprolactam, Methyl ethyl ketoxime, malonic acid ester, secondary Amines and triazole and pyrazole derivatives, such as e.g. in the EP-A 0 576 952, EP-A 0 566 953, EP-A 0 159 117, US-A 4 482 721, WO 97/12924 or EP-A 0 744 423 are described.

Secondary amines are used as blocking agents in the patent EP-A 0 096 210 described. Although there are also aralkyl-substituted amines as Blocking claimed, but their application is in the Examples not disclosed. The use of such amines in aqueous Systems is not known from EP-A 0 096 210.

The technically most common today used blocking agents for isocyanates are ε-caprolactam and Butanone oxime. While in ε-caprolactam usually firing temperatures applied around 160 ° C may be blocked 1-component stoving lacquers in which butanone oxime is used as blocking agent became lower already at 10-20 ° C Temperatures are baked. However, at these stoving temperatures in some paint systems the desired Property level is no longer reached. But also these temperatures are perceived as too high for the time being, so that the need for Burning systems exist, even at lower temperatures Completely network.

Such aqueous and / or water-dilutable stoving systems with reduced stoving temperature are in the EP 853 639 . DE 19810660 and EP 137 555 2 claimed.

Aqueous 1-component PUR stoving lacquers for topcoats, preferred for the automotive finish, contain reactive towards polyisocyanate groups Polyols. In order to obtain the required high quality of the topcoats, is a very good compatibility of the crosslinker in the system required.

Only in this way can coatings with high gloss and low haze values be produced. The topcoats produced according to the prior art do not sufficiently meet these requirements, in particular when systems with a low stoving temperature, such as are used in EP 853 639 and DE 19810660 be claimed used.

EP 1375552 describes polyisocyanates blocked with secondary benzylamines for the production of coatings. The use of these products for the production of topcoats, which have a particularly high quality level, is not mentioned there.

It There was therefore a need for new blocked polyisocyanates for the preparation from transparent to high gloss Coatings, in particular of topcoats for automotive finishing, what an outstanding compatibility the individual components requires.

These Task was with the blocked polyisocyanates of the invention and self-crosslinking one-component stoving systems containing them solved.

worin
A den Rest eines Polyisocyanats bedeutet,
B den Rest eines kationischen, anionischen und/oder nichtionischen Hydro-philierungsmittels bedeutet,
R¹, R², R³ gleich oder verschieden sein können und Wasserstoff, C₁-C₄-Alkyl, C₆-C₁₀-Cycloalkyl bedeuten, wobei Wasserstoff bevorzugt ist,
R⁴ C₁-C₄-Alkyl, C₆-C₁₀-Cycloalkyl oder C₁-C₁₄-Aralkyl, bevorzugt Methyl, Ethyl, Isopropyl und tert.-Butyl, besonders bevorzugt tert.-Butyl, bedeuten
x für die Zahl 1, 2, 3, 4 oder 5 steht und
y eine Zahl von 1 bis 8, bevorzugt 2 bis 6, besonders bevorzugt 2,5 bis 4,0 und
z eine Zahl von 0,1 bis 4, bevorzugt 0,2 bis 2 bedeutet;
wobei das Äquivalent-Verhältnis von y zu z 20:1 bis 1:1, bevorzugt 10:3 bis 3:1, besonders bevorzugt 8:1 bis 4:1 beträgt, bedeutet
zur Herstellung von Decklacken, bevorzugt bei der Automobilerstlackierung.The present invention relates to the use of aqueous and / or water-dilutable blocked polyurethane-based polyisocyanates of the formula (I)

wherein
A is the radical of a polyisocyanate,
B is the radical of a cationic, anionic and / or nonionic hydro-philic agent,
R ¹ , R ² , R ^{3 may be} identical or different and denote hydrogen, C ₁ -C ₄ -alkyl, C ₆ -C ₁₀ -cycloalkyl, hydrogen being preferred,
R ^{4 is} C ₁ -C ₄ -alkyl, C ₆ -C ₁₀ -cycloalkyl or C ₁ -C ₁₄ -aralkyl, preferably methyl, ethyl, isopropyl and tert-butyl, particularly preferably tert-butyl
x is the number 1, 2, 3, 4 or 5 and
y is a number from 1 to 8, preferably 2 to 6, particularly preferably 2.5 to 4.0 and
z is a number from 0.1 to 4, preferably 0.2 to 2;
where the equivalent ratio of y to z is 20: 1 to 1: 1, preferably 10: 3 to 3: 1, more preferably 8: 1 to 4: 1
for the production of topcoats, preferably in automotive finishing.

worin
R¹, R², R³ und R⁴ und x die bei Formel (I) genannte Bedeutung haben,
umgesetzt werden.The invention also provides a process for the preparation of the blocked polyisocyanates of the general formula (I), which comprises polyisocyanates with secondary amines of the formula (II)

wherein
R ¹ , R ² , R ³ and R ⁴ and x have the meaning given in formula (I),
be implemented.

Especially preferred are unsymmetrical substituted secondary amines, i.e. secondary Amines with two different substituents.

When examples for Secondary amines according to the invention may be mentioned: N-methyl, N-ethyl, N- (iso) propyl, N-n-butyl, N-iso-butyl, N-tert-butylbenzyl or 1,1-dimethylbenzylamine, N-alkyl-N-1,1-dimethylmethylphenylamine, Adducts of benzylamine on compounds with activated double bonds like malonic esters, N, N-dimethylaminopropylbenzylamine and other tertiary amino groups containing optionally substituted benzylamines and / or dibenzylamine. Of course can also mixtures of these amines with each other and / or with other blocking agents be used.

When Polyisocyanates within the meaning of the invention are all known per se hydrophilized, aliphatic, cycloaliphatic and aromatic Polyisocyanates having an isocyanate content of 0.5 to 50, preferably From 3 to 30, particularly preferably from 5 to 25,% by weight, such as tetramethylene diisocyanate, Cyclohexane-1,3- and 1,4-diisocyanate, hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanato-methylcyclohexane (Isophorone diisocyanate, IPDI), methylene bis (4-isocyanatocyclohexane), tetramethylxylylene diisocyanate (TMXDI), Triisocyanatononane.

in principle also suitable are aromatic polyisocyanates such as tolylene diisocyanate (TDI), diphenylmethane-2,4'- and / or 4,4'-diisocyanate (MDI), triphenylmethane-4,4'-diisocyanate, Naphthylene-1,5-diisocyanate.

Prefers suitable are polyisocyanates, the heteroatoms in which the isocyanate groups containing radical. Examples are carbodiimide groups, Allophanate groups, isocyanurate groups, urethane groups and biuret groups having polyisocyanates.

Especially preferred for the use as topcoats in the automotive OEM the known polyisocyanates, which are mainly used in the production of paints, e.g. Biuret, isocyanurate or uretdione groups having modification products of the above-mentioned simple polyisocyanates, in particular hexamethylene diisocyanate or isophorone diisocyanate.

Farther suitable are low molecular weight polyisocyanates containing urethane groups, as they do by putting in excess used IPDI or TDI with simple polyhydric alcohols the molecular weight range 62-300, especially with trimethylolpropane or glycerin.

suitable Polyisocyanates are also the known prepolymers containing terminal isocyanate groups, in particular, by implementing the above simple Polyisocyanates, especially diisocyanates, with minor amounts on organic compounds with at least two towards isocyanates reactive accessible to functional groups are. In these known prepolymers, the ratio of Isocyanate groups to opposite NCO reactive hydrogen atoms 1.05: 1 to 10: 1, preferably 1.1: 1 to 3: 1, wherein the hydrogen atoms are preferably selected from hydroxyl groups come. The type and proportions the starting materials used in the preparation of NCO prepolymers by the way preferably chosen the NCO prepolymers preferably have an average NCO functionality of 2 to 3 and have a number average molecular weight of 500-10000, preferably 800-4000.

Of course, everyone can mentioned polyisocyanates as mixtures with each other or also with other crosslinkers such as melamine resins for the production of Lacquers, colors and other formulations are used. The Use of aromatic polyisocyanates is for those Suitable applications where no high weathering resistance be requested.

The Preparation of the blocked invention Polyisocyanates can be made by methods known per se. For example can one or more polyisocyanates and the blocking agent (for example, during about 10 minutes) with stirring be dosed. It is stirred until no free isocyanate is more detectable. It is also possible to use one or more polyisocyanates with a mixture of two or more blocking agents To block. Of course is also a preparation in optionally water-miscible solvents possible, which are optionally removed after production. But it is also possible the polyisocyanates of the invention in water immiscible solvents and then disperse these mixtures in water or with water-miscible solvents such as acetone or N-methylpyrrolidone to dilute water-miscible solutions. at The preparation of the polyisocyanates according to the invention can also Catalysts, Colöser and other aids and additives are used.

One an essential component of the preparation of the blocked invention Polyisocyanates is their hydrophilization, which leads to the polyisocyanates thus prepared remain in solution after the addition of water or form finely divided, sedimentation-stable dispersions.

When Hydrophilizing agents can all for suitable for this purpose cationic, anionic and / or nonionic Compounds are used such as mono- and / or dihydroxycarboxylic or monofunctional Alkylethoxilate. Of course can It is also possible to use mixtures of different hydrophilicizing agents.

Of the Incorporation of the hydrophilizing agent in the polyisocyanates according to the invention can be done by per se known method. Thus, e.g. first a part of the isocyanate groups with the blocking agents according to the invention and subsequently the remainder are reacted with the hydrophilizing agent. But it can also be reversed procedure or so that the blocking the isocyanate groups in two steps, namely before and after the hydrophilization he follows.

Of course, the Hydrophilic also at another time of production the polyisocyanates of the invention be added as e.g. in the preparation of the prepolymers. When Hydrophilizing agents can Furthermore also hydrophilized polyether, polyester and / or polyacrylates used be as they are e.g. in the production of self-crosslinking One-component stoving lacquers are used.

If mono- or dihydroxycarboxylic acids are used for the hydrophilization, then a full or partial neutralization of the carboxyl groups. The neutralization can be carried out with any amines such as triethyl, dimethylcyclohexyl, methyldiisopropyl or dimethylethanolamine. Also ammonia is suitable.

• a) 100 Äquivalent % Polyisocyanat
• b) 40–90, bevorzugt 60–85 Äquivalent % sekundäres Benzylamin
• c) 10–40, bevorzugt 10–30, besonders bevorzugt 10–25 Äquivalent % eines Hydrophilierungsmittels und gegebenenfalls
• d) 0–40, bevorzugt 5–25 Äquivalent % einer bevorzugt difunktionellen Hydroxyl- und/oder Aminogruppen enthaltenden Verbindung eines mittleren Molgewichts von 62 bis 3000, bevorzugt 62 bis 1500, wobei die Mengenverhältnisse der Reaktionspartner so gewählt werden, dass das Äquivalentverhältnis von NCO-Gruppen der Komponente a) zu gegenüber Isocyanaten reaktionsfähigen Gruppen der Komponenten b), c) und d) bei 1:0,8 bis 1:1,2 liegt, sowie gegebenenfalls Zuschlagstoffe und Hilfsstoffe,

verwendet.The blocked polyisocyanates according to the invention are preferably used as hydrophilized aqueous and / or water-dilutable blocked polyisocyanates as crosslinkers in a composition:

• a) 100 equivalent% polyisocyanate
• b) 40-90, preferably 60-85 equivalent% of secondary benzylamine
• c) 10-40, preferably 10-30, more preferably 10-25 equivalent% of a hydrophilizing agent and optionally
• d) 0-40, preferably 5-25 equivalent% of a preferably difunctional hydroxyl and / or amino-containing compound having an average molecular weight of 62 to 3000, preferably 62 to 1500, wherein the proportions of the reactants are chosen so that the equivalent ratio of NCO Groups of component a) to isocyanate-reactive groups of components b), c) and d) is 1: 0.8 to 1: 1.2, and optionally adjuvants and auxiliaries,

used.

Diamines, diols and also hydroxyamines in the molecular weight range from 32 to 300 are suitable as the difunctional chain extender component d). Examples are hydrazine, ethylenediamine, isophoronediamine, the bisketimine of isophoronediamine and methyl isobutyl ketone, 1,4-dihydroxy-butane, 1,6-hexanediol, ethanolamine, N-methylethanolamine, hydroxyethylethylenediamine, the adduct of 2 moles of propylene carbonate and 1 mol of hydrazine of the formula ( III)
in question.

The aqueous and / or water-dilutable blocked polyisocyanates are either as solutions in preferably water-miscible solvents such as N-methylpyrrolidone at a concentration of 40-95, preferably 60-85 Wt .-% before or as finely divided dispersions having a solids content from 25-70, preferably 35-50 Wt .-%.

The polyisocyanates according to the invention are, as described above, crosslinkers for polyol components. Suitable polyol components which can also be used as mixtures are:
Polyhydroxypolyester and polyesterpolyurethanes, polyhydroxy-polyethers or polymers containing hydroxyl groups, for example the polyhydroxypolyacrylates known per se, polyester polyacrylates or polyols containing urethane groups. The compounds generally have a hydroxyl number of from 20 to 200, preferably from 50 to 130, based on 100% products on.

at the polyhydroxyl polyacrylates are known per se Copolymers of styrene with simple esters of acrylic acid and / or methacrylic acid, being for the purpose of introduction hydroxyalkyl esters such as the 2-hydroxyethyl, 2-hydroxypropyl, 2-, 3- or 4-Hydroxybutylester these acids also used become.

suitable Polyether polyols are known from polyurethane chemistry Ethoxylation and / or Propoxylation products of suitable 2- to 4-valent starter molecules such as e.g. Water, ethylene glycol, propanediol, trimethylolpropane, glycerol and / or Pentaerythritol.

Examples suitable polyester polyols are in particular those in polyurethane chemistry known reaction products of polyhydric alcohols, for example, of alkane polyols just mentioned by way of example Kind with excess quantities polycarboxylic or polycarboxylic anhydrides, especially dicarboxylic acids or dicarboxylic anhydrides. Suitable polycarboxylic acids or polycarboxylic anhydrides are, for example, adipic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, maleic acid, maleic anhydride, their Diels-Alder adducts with cyclopentadiene, fumaric acid or dimeric or trimeric fatty acids. In the preparation of polyester polyols, of course, mixtures the exemplified polyhydric alcohols or mixtures of exemplified acids or acid anhydrides be used.

The Preparation of the polyester polyols is carried out by known methods, such as. in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 2, G. Thieme-Verlag, 1963, pages 1 to 47 are described. The optionally required hydrophilic modification of these polyhydroxyl compounds takes place according to methods known per se, such as, for example in EP-A-0 157 291 or EP-A-0 427 028.

Of course you can too Mixtures or reaction products based on polyesters, polyethers and polyacrylates, optionally also modified by polyurethanes the known type, are used.

The blocked according to the invention Polyisocyanates are preferred for the production of stoving topcoats used in the automotive OEM. For this purpose, the Coating compositions according to the invention by doctoring, dipping, spray application such as compressed air or airless spraying, as well as by electro-static application, for example high-rotation bell application, be applied. The dry film layer thickness can be, for example at 10-120 microns. The curing The dried films are baked by baking in the temperature range of 90-260 ° C, preferred 110-180 ° C, especially preferably 120-130 ° C.

The Production of lacquers, paints and other formulations from the polyisocyanates according to the invention takes place according to known methods.

Except the Polyisocyanates and polyols can the usual formulations Additives and other auxiliaries (e.g., pigments, fillers, Leveling agent, defoamer, Catalysts) in easily determined by the skilled person amounts be added.

The explain the following examples closer to the Invention without limiting it.

example 1

221.00 g (0.26 Val OH) of a polyester of adipic acid, hexanediol and neopentyl glycol of average molecular weight of. Were added to 557.70 g (2.86 g of NCO) Desmodur N 3300 (Bayer AG, Leverkusen) with stirring at 70 ° C. 1700 added and stirred for 30 minutes. Then 61.36 g (0.52 mol) of hydroxypivalic acid dissolved in 99.01 g of N-methylpyrrolidone were added dropwise over the course of 3 hours. Thereafter, 26.00 g (0.052 mol) of a methanol-started polyethylene oxide average molecular weight of 500 was added and stirred for 90 minutes. Then 299.35 (1.833 mol) of tert-butylbenzylamine were added within 40 minutes and stirred for 20 minutes. Thereafter, no NCO groups were detectable by IR spectroscopy. There were added 50.99 g (0.572 mol) of dimethylethanolamine, stirred for 10 minutes and dispersed with 1725.6 g of 50 ° C warm water, stirred for 60 minutes at 50 ° C, allowed to cool with stirring to room temperature and then stirred for a total of 6 hours , The resulting dispersion had the following properties: Solids content: 40.93% PH value: 9.42 Viscosity (Haake rotational viscometer, 23 ° C): 90 mPas Particle size (laser correlation spectroscopy, LKS): 31 nm

Example 2

391.00 g (0.46 Val OH) of a polyester of adipic acid, hexanediol and neopentyl glycol were added to 908.27 g (2.53 eq NCO) Desmodur Z 4470 M / X (Bayer AG, Leverkusen) at 70 ° C. with stirring average molecular weight of 1700 was added and stirred for 10 minutes. Thereafter, a solution of 67.85 g (0.25 mol) of hydroxypivalic acid in 109.48 g of N-methylpyrrolidone was added over 3 hours. Thereafter, 23.00 g (0.046 eq. OH) of a methanol-started polyethylene oxide of average molecular weight 500 was added and stirring was continued for 2 hours. Then 220.34 (0.58 mol) of tert-butylbenzylamine were added within 40 minutes and stirred for 10 minutes. Thereafter, no NCO groups were detectable by IR spectroscopy. Then 56.38 g (0.275 mol) of dimethyl ethanolamine were added, stirred for 10 minutes and dispersed with 1709.6 g of 50 ° C warm water. It was further stirred for 1 hour and then cooled with stirring to room temperature (about 2 hours) and stirred for 4 hours. The resulting dispersion had the following properties: Solids content: 41.50% PH value: 8.97 Viscosity (Haake rotational viscometer, 23 ° C): 820 mPas Particle size (laser correlation spectroscopy, LKS): 48 nm

Example 3

The procedure was as described in Example 1, but 569.1 g of Desmodur XP 2489 (Bayer AG, Leverkusen) were used instead of Desmodur N 3300. The resulting dispersion had the following properties: Solids content: 41.0% PH value: 9.11 Viscosity (Haake rotational viscometer, 23 ° C): 25 mPas Particle size (laser correlation spectroscopy, LKS): 33 nm

Comparative Example 1

The procedure was as described in Example 1, but 176.19 g (0.705 mol) of dimethylpyrazole were added instead of tert-butylbenzylamine. The resulting dispersion had the following properties: Solids content: 38.1% PH value: 9.13 Viscosity (Haake rotational viscometer, 23 ° C): 105 mPas Particle size (laser correlation spectroscopy, LKS): 23.8 nm

Claims (8)

Use of aqueous and / or water-dilutable blocked polyisocyanates of the general formula

where A is the radical of a polyisocyanate, B is the radical of a cationic, anionic and / or nonionic hydrophilicizing agent, R ¹ , R ² , R ^{3 may be} identical or different and are hydrogen, C ₁ -C ₄ -alkyl or C ₆ -C _{10 is} cycloalkyl, R ^{4 is} C ₁ -C ₄ -alkyl, C ₆ -C ₁₀ -cycloalkyl or C ₁ -C ₁₄ -aralkyl, and x is the number 1, 2, 3, 4 or 5 and y is one Number of 1 to 8 and z is a number from 0.1 to 4, wherein the equivalent ratio of y to z 20: 1 to 1: 1, for the preparation of topcoats. Blocked polyisocyanates according to claim 1, characterized in that that as a secondary Amine N-benzyl-tert-butylamine is used. Process for the preparation of the blocked polyisocyanates according to Claim 1, characterized in that polyisocyanates with secondary amines of the general formula (II)

wherein R ¹ , R ² , R ³ and R ⁴ and x have the meaning given in claim 1 to formula (I), are reacted. Use of the blocked polyisocyanates according to claims 1 and 2 for the production of topcoats for the automotive OEM. Use according to claim 4, characterized in that the topcoats are clearcoats is. Use according to claim 4, characterized in that it is pigmented in the topcoats Systems acts. Use according to claims 4 to 6, characterized in that it is in the topcoats to burn-in systems for coating substances from wood, metals, mineral Substances and plastics. Hydrophilic, aqueous and / or water-dilutable A composition containing blocked polyisocyanates according to claims 1 and 2 off a) 100 equivalent % Polyisocyanate b) 40-90, preferably 60-85 equivalent % secondary benzylamine c) 10-40, preferably 10-25 equivalent % of a hydrophilizing agent and optionally d) 0-40, preferred 5-25 equivalent % of a preferably difunctional hydroxyl and / or amino groups Compound, average molecular weight of 62 to 3000, preferably 62 until 1500, wherein the proportions of the reactants so chosen be that the equivalent ratio of NCO groups the component a) compared to Isocyanates reactive Groups of components b), c) and d) is 1: 0.8 to 1: 1.2, and, where appropriate, aggregates and excipients.