KR20040015326A - Cyclic Ketones As Blocking Agents - Google Patents

Abstract

The present invention relates to novel blocked polyisocyanates which can obtain high quality, crack free coatings and low yellowing index paint lacquers and methods for their preparation and their use in single component polyurethane systems.

Description

Cyclic Ketones As Blocking Agents

The present invention relates to novel blocked polyisocyanates, processes for their preparation and their use in polyurethane systems.

Blocking of polyisocyanates to temporarily protect isocyanate groups is a long known method and is described, for example, in Houben Weyl, Methoden der organischen Chemie XIV / 2, pages 61-70. Curable compositions containing blocked polyisocyanates are used, for example, in polyurethane lacquers, preferably monocomponent (1C) polyurethane systems.

Monocomponent (1C) polyurethanes are widely used in the field of industrial stoving lacquers, such as production automotive coatings and coil coatings, and are characterized by very good film properties such as chemical resistance, scratch resistance and weather resistance. do. These lacquer films cure the blocked polyisocyanate with the polyol by thermal activation (stobbing operation), optionally in the presence of a suitable catalyst. An overview of blocking agents suitable in principle herein is described, for example, in Wicks et al. in Progress in Organic Coatings 1975, 3, pages 73-79, 1981, 9, pages 3-28 and 1999, 36, pages 148-172.

For use in the field of automotive coatings, the blocked polyisocyanates should be crosslinkable at a maximum stoving temperature of 140 ° C. and should have a slight yellowing during the stoving operation, preferably no yellowing. Stoving temperature is controlled primarily by the reactivity of the blocked polyisocyanate.

Most stoving systems, such as melamine-formaldehyde and urea-formaldehyde resins, are characterized by releasing volatile components that increase the VOC value during curing. In addition, certain proportions of blocking agent remain in the formed lacquer film, adversely affecting the properties of the lacquer film. Due to residual blocking agents, the properties of single component lacquer films, such as scratch and acid resistance, fall short of these properties of what is called a two-component (2C) polyurethane lacquer coating (see, for example, T. Engbert, E. Koenig, E. Juergens, Farbe & Lack, Curt R. Vincentz Verlag, Hannover 10/1995). In addition, separation of the blocking agent and exiting the gaseous form from the lacquer film can cause bubble formation in the lacquer film. Subsequent incineration of the released blocking agent may sometimes be necessary.

Isocyanates blocked with diethyl malonate have recently been used for particularly low stoving temperatures, mainly in the range from 90 to 120 ° C. (eg EP-A 0 947 531). In contrast to blocking methods using heterocyclic N compounds such as, for example, caprolactam or butanone oxime, here the whole blocking agent is cleaved and not removed or separated, but rather the blocking agent is blocked with diethyl malonate. Causes transesterification in the isocyanate. Ethanol is separated during this transesterification. This method can be used at relatively low stoving temperatures because the second adjacent isster functional group is an activated ester. The disadvantage of this method is that systems such as these are extremely sensitive to acids because unstable ester bonds can be cleaved quickly. Thus, the possible uses of these products are limited.

It was an object of the present invention to provide novel blocked polyisocyanates which react without separation of the blocking agent, ie without emissions, and exhibit low crosslinking temperatures. It was also an object of the present invention that these blocked polyisocyanate systems should be stable upon storage at room temperature and that they should be suitable for the production of single component stoving lacquers, in particular in combination with suitable polyol components.

Surprisingly, the present inventors have found that polyisocyanates for obtaining an emission-free coating in which the acidic CH compound having the basic structure of the activated cyclic ketone, in particular the basic structure of cyclopentanone-2-carboxymethyl ester, have a reduced tendency to yellowing. It was found to be particularly suitable for the blocking of.

The present invention relates to an organic polyisocyanate comprising at least two isocyanate groups, wherein the isocyanate is blocked with an acidic CH cyclic ketone of the formula (I) and the content of the blocked isocyanate groups (calculated as NCO) is 0.1 to 20% by weight in total will be.

Where

X is an electron attractor

R ¹ and R ² independently of one another are radicals H, C ₁ -C ₂₀ (cyclo) alkyl, C ₆ -C ₂₄ aryl, C ₁ -C ₂₀ (cyclo) alkyl esters or amides, C ₆ -C ₂₄ aryl esters or Amides, or mixed aliphatic / aromatic radicals having 1 to 24 carbon atoms, which may form part of 4 to 8 membered rings,

n is an integer of 0-5.

Preference is given to the content of blocked isocyanate groups (calculated as NCO) in the range from 0.1 to 15.6% by weight. Particular preference is given to the content of blocked isocyanate groups (calculated as NCO) in the range from 0.1 to 14% by weight. Partial blocking of polyisocyanates can optionally be effective, in which case unblocked isocyanate groups can be used for further reactions. Typically, all isocyanate groups are blocked.

Electron attraction group X may include any substituent which results in an α-terminal hydrogen exhibiting acidic CH properties. Substituents may include ester groups, sulfoxide groups, sulfone groups, nitro groups, phosphonate groups, nitrile groups, isonitrile groups, polyhalogen alkyl groups, fluorine, chlorine or carbonyl groups. Nitrile groups and ester groups are preferred, and methyl carboxylate groups and ethyl carboxylate groups are particularly preferred.

Also suitable are compounds of formula I, wherein the ring optionally contains heteroatoms such as oxygen, sulfur or nitrogen atoms.

Activated cyclic ketones of formula I preferably have a ring size of 5 (n = 1) or 6 (n = 2).

Preferred compounds of formula I include cyclopentanone-2-carboxymethyl ester and cyclopentanone-2-carboxyethyl ester, cyclopentanone-2-carboxylic acid nitrile, cyclohexanone-2-carboxymethyl ester and cyclohexa Non-2-carboxyethyl ester, or cyclopentanone-2-carbonylmethyl. Particular preference is given to cyclopentanone-2-carboxymethyl esters and cyclopentanone-2-carboxyethyl esters, and cyclohexanone-2-carboxymethyl esters and cyclohexanone-2-carboxyethyl esters. The cyclopentanone system can be easily obtained industrially by Dieckmann condensation of dimethyl adipate or diethyl adipate. Cyclohexanone-2-carboxymethyl ester can be obtained by hydrogenation of methyl salicylate.

The polyisocyanate to be blocked is any organic polyisocyanate suitable for the crosslinking of compounds comprising active hydrogens, ie aliphatic polyisocyanates comprising two or more isocyanate groups, cycloaliphatic polyisocyanates, as well as aromatic and heterocyclic polyisocyanates, and Mixtures thereof. Typical examples of polyisocyanates include aliphatic isocyanates such as di- or triisocyanates such as butane diisocyanate (BDI), pentane diisocyanate, hexane diisocyanate (HDI), 4-isocyanatomethyl-1,8- Octane diisocyanate (triisocyanatononane, TIN), or cyclic system such as 4,4'-methylene-bis (cyclohexyl isocyanate) (Desmodur W (registered trademark), Bayer AG) , Leverkusen, Germany), 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethyl-cyclohexane (IPDI), as well as ω, ω'-diisocyanato-1,3 Dimethylcyclohexane (H ₆ XDI). Examples of aromatic polyisocyanates include 1,5-naphthalene diisocyanate, diisocyanato-dipetylmethane (MDI) or crude MDI, diisocyanatomethylbenzene (TDI), in particular 2,4- and 2,6 thereof -Isomers and industrial mixtures of the two isomers thereof, as well as 1,3-bis (isocyanatomethyl) benzene (XDI).

Likewise very suitable polyisocyanates include di- or triisocyanates via their isocyanates with di- or triisocyanates, such as urethanedione or carbodiimide compounds, or isocyanurates or iminooxadiazinediones formed by the reaction of three isocyanate groups. It is a polyisocyanate obtained by making it react. Polyisocyanates are also oligomeric polyisocyanates comprising monomeric di- and / or triisocyanates and / or biurets, allophanates and acylurea structural elements, triisocyanates with low monomer content, or partially modified monomeric Di- or triisocyanates, and any mixtures of these polyisocyanates.

Polyisocyanate prepolymers containing on average more than one isocyanate group per molecule are also very suitable. They are obtained by prereacting one of the aforementioned polyisocyanates with an excessive molar amount, for example with an organic material containing at least two active hydrogen atoms per molecule, for example in the form of hydroxy groups.

Preferred polyisocyanates are polyisocyanates containing uretdione, isocyanurate, iminooxadiazinedione, acylurea, biuret or allophanate structures, for example butane diisocyanate (BDI), pentane diisocyanate, hexane Based on diisocyanate (HDI), 4-isocyanatomethyl-1,8-octane diisocyanate (triisocyanatononane, TIN) or 4,4'-methylene-bis (cyclohexyl isocyanate) ( Desmodur W (registered trademark), Bayer AG, Leverkusen, Germany), 3,5,5-trimethyl-1-isocyanato-3-isocyanatomethylcyclohexane (IPDI), as well as ω, ω Polyisocyanates based on cyclic systems such as' -diisocyanato-1,3-dimethylcyclohexane (H ₆ XDI). Examples of aromatic polyisocyanates include 1,5-naphthalene diisocyanate, diisocyanato-dipetylmethane (MDI) or crude MDI, diisocyanatomethylbenzene (TDI), in particular 2,4- and 2,6 thereof -1,3-bis (isocyanatomethyl) benzene (XDI), as well as industrial mixtures of isomers and both isomers thereof.

Particularly preferred polyisocyanates are polyisocyanates based on hexane diisocyanate (HDI), polyisocyanates based on 4,4'-methylene-bis (cyclohexyl isocyanate), or 3,5,5-trimethyl-1-iso Polyisocyanate based on cyanato-3-isocyanatomethylcyclohexane (IPDI).

The present invention also reacts a polyisocyanate with an acidic CH cyclic ketone of the formula (I) in the presence of a catalyst, wherein using 0.8 to 1.2 moles of the cyclic ketone of the formula (I) per equivalent of isocyanate of the polyisocyanate to be blocked A process for the production of blocked organic polyisocyanates according to the invention is characterized.

<Formula I>

Where

X is an electron attractor

R ¹ and R ² independently of one another are radicals H, C ₁ -C ₂₀ (cyclo) alkyl, C ₆ -C ₂₄ aryl, C ₁ -C ₂₀ (cyclo) alkyl esters or amides, C ₆ -C ₂₄ aryl esters or Amides, or mixed aliphatic / aromatic radicals having 1 to 24 carbon atoms, which may form part of 4 to 8 membered rings,

n is an integer of 0-5.

One equivalent of isocyanate groups of the polyisocyanate to be blocked is preferably reacted with one equivalent of the blocking agent.

Suitable catalysts include alkali metal and alkaline earth metal bases, such as powdered sodium carbonate (soda). Depending on the cyclic ketones used, trisodium phosphate or dabco (Dabco, 1,4-diazabicyclo [2.2.2] octane) may be used. Carbonates of subgroup II metals are also suitable. Sodium carbonate or potassium carbonate is preferably used. Alternatively, the reaction of cyclic ketones with isocyanates can also be carried out in the presence of zinc salts as catalyst. Particular preference is given to reactions with zinc-2-ethylhexanoate. Mixtures can also be used as catalysts.

When carrying out the process according to the invention, 0.05 to 10% by weight, preferably 0.1 to 3% by weight of catalyst is added. Most preferably, 0.2 to 1 weight percent catalyst is used.

The reaction can be carried out at room temperature or at higher temperatures up to 140 ° C. Preference is given to a temperature range of 40 to 90 ° C., in particular 15 to 90 ° C.

Blocking can be carried out without solvent or in the presence of a suitable solvent. Suitable solvents are solvent naphtha supplied as solvent containing aromatic compounds in butyl acetate, methoxypropyl acetate or Exxon-Chemie (Esso Deutschland GmbH, Hamburg, Germany), and of these solvents. Conventional lacquer solvents such as mixtures. Blocking is preferably carried out in the solvents described above, wherein the solids content should be adjusted to range from 10 to 90%.

In order to achieve the required lacquer properties in each case, besides the cyclic ketones of the formula (I) used according to the invention, mixtures of any blocking agents can also be used in combination with the process according to the invention, wherein The proportion of the compound of I is at least 30% by weight, preferably 50% by weight, most preferably 100% by weight.

Finally, the present invention also relates to a process for the preparation of 1-C PUR stoving lacquer, characterized in that the organic polyisocyanate according to the invention is used as a crosslinker component for the organic polyhydroxy compound.

Blocked polyisocyanates according to the present invention are cured in combination with a suitable organic polyhydroxyl compound at a temperature of from 110 to 140 ° C., preferably from 120 to 140 ° C., in a presence of a suitable catalyst for 15 to 30 minutes. It features. Stoving time depends in particular on the amount of catalyst used. Stoving is preferably carried out at a temperature of 120 to 140 ° C. for a time of 30 minutes.

If the blocked polyisocyanate according to the invention is suitable for producing the coil coating, it is cured at a stoving time within a maximum of 2 minutes, preferably 5 seconds up to 35 seconds. At this time, the furnace temperature reaches 300 to 400 ° C. Here, the stoving temperature naturally depends on the material added and the thickness of the plate to be coated. The furnace temperature is typically a temperature of at least 180 ° C. and at most 260 ° C. PMT. Preferably, the temperature range is 210 ° C. to 245 ° C. PMT. Especially preferably, the range is 216 ° C to 241 ° C PMT. The technical properties of the lacquer of the stowed lacquer film, such as MEK (methylethylketone) solvent durability, hardness, and elasticity at a given stove temperature, depend first of all on the amount of catalyst added. Preferably, the stove is stowed at a temperature of 232 ° C. over a period of 38 seconds. A temperature of 216 ° C. is also possible. Stoving time is 33 seconds on aluminum substrate. Specific optimum conditions are determined by preliminary tests generally known to those skilled in the art, and in use the temperature of the coil coating furnace is controlled over sensitive bands.

Suitable crosslinking catalysts are for example DBTL (dibutyltin dilaurate), titanium-2-ethylhexanoate, titanium-tetraisopropylate and other conventional titanium- (IV) -compounds, zircon-2-ethyl Hexanoate and other common zircon- (IV) -compounds, aluminum triethylate, scandium trifluoromethanesulfonate, yttrium-2-ethylhexanoate, yttrium trifluoromethanesulfonate, lanthan-2-ethylhexano Eate, lanthanum trifluoromethanesulfonate, cobalt-2-ethylhexanoate, copper-2-ethylhexanoate, indium trifluoromethanesulfonate, gallium acetylacetonate, nickel acetylacetonate, lithium-2-ethylhexa Noate, lithium trifluoromethanesulfonate, sodium-2-ethylhexanoate, sodium acetate, sodium trifluoromethanesulfonate, magnesium-2-ethylhexanoate, magnesium trifluor Methanesulfonate, calcium-2-ethylhexanoate, magnesium trifluoromethanesulfonate, calcium-2-ethylhexanoate, calcium trifluoromethanesulfonate, zinc-2-ethylhexanoate, zinc-dithiocar Bamate, zinc-acetylacetonate, zinc-tetramethylheptadionate, zinc-salicylate, zinc chloride and other common zinc- (II) -compounds, bismuth-2-ethylhexanoate and bismuthacetate. Preferred catalysts are zinc compounds and bismuth compounds, particularly preferably zinc-2-ethylhexanoate and bismuth-2-ethylhexanoate.

Polyhydroxyl compounds suitable for this purpose of addition, and other details regarding the manufacture and use of such stoving lacquers can be obtained from literature such as, for example, DE-A 19 738 497 or EP-A 0 159 117. . Particularly preferred fields of use for the products according to the invention are the use as crosslinkers in automotive fillers and as crosslinkers in the field of coil coatings.

According to the blocked polyisocyanate according to the invention, a high quality crack-free coating or a lacquer with a low yellowing value is obtained.

In addition, the blocked polyisocyanates according to the invention can be cured with di- or polyamines. This reaction is preferably carried out at room temperature. It can be used to make lacquers or workpieces.

To prepare coil coatings, polyesterpolyols, polycarbonate polyols, and polyacrylate polyols can be used. In principle, all binders with a sufficiently high OH content can be added.

Trademark *) type Supply mode Alkynol® 1665 SN / IB Oil-free branched saturated polyester 65% SN100 / NB Alkynol® VP LS 2013 Oil-free branched polyester 70% SN100 Alkynol® VP LS 2326 Oil-free branched saturated polyester 60% SN100 Desmophen® 651 MPA Branched polyester 67% MPA Desmophen® 670 Weakly branched polyester Solvent free Desmophen® 690 MPA Branched polyester 70% MPA Desmophen® 1200 Weakly branched polyester Solvent free Desmophen (registered trademark) 1652 Oil-free linear polyester Solvent free Desmophen® C 200 Linear polycarbonate-polyester Solvent free *) Bayer AG of Leverkusen, Germany

In addition to the components mentioned, the binders according to the invention may contain up to 5% by weight of OH-functional hydrazide compounds (relative to solids of the finished lacquer) and other stabilizing additives such as, for example, HALS-amines or solvents. have. As other additives, for example CAB (cellulose acetobutyrate) and for example Acronal® 4 F (fusing agent and antifoaming agent) are suitable.

As a stabilizing component against heat yellowing, an addition product of hydrazine hydrate to 2 moles of propylene carbonate having the formula (II) as already known from EP-A 0 829 500 can be added.

The polyisocyanate used was an HDI polyisocyanate (Desmodur® N3300, Bayer AG, Leverkusen, Germany), having an isocyanurate structure, an NCO content of 21.8% and a viscosity of 3200 mPa · s.

The cyclopentanone-2-carboxymethyl ester and cyclohexanone-2-carboxymethyl ester used as blocking agents were ordered from Fluka and used without further purification.

Preparation of Polyisocyanates Blocked with Acid αcyclic Ketones

Example 1

Cyclopentanone-2-carboxymethyl ester (42.7 g, 0.3 equiv) in a solution of 58.5 g (0.3 equiv) of Desmodur® N3300 in 81 mL of butyl acetate slowly dissolved in 20 mL of butyl acetate with strong stirring Was added to the solution. 1.02 g of zinc 2-ethylhexanoate was added as catalyst. The bath was heated at a temperature of 50 ° C. until a value of about 0.2% was obtained (for about 8 hours) in measuring the NCO value. The theoretical value of blocked NCO content was 6.2%.

Example 2

Cyclohexanone-2-carboxymethyl ester (42.6 g, 0.25 equiv) in a solution of 42.6 g (0.25 equiv) of Desmodur® N3300 in 71.4 mL of butyl acetate slowly dissolved in 20 mL of butyl acetate with vigorous stirring Was added to the solution. 0.9 g of zinc 2-ethylhexanoate was added as catalyst. The bath was heated at a temperature of 80 ° C. until a value of about 0.3% was obtained (for about 6 hours) in measuring NCO values. The theoretical value of blocked NCO content was 5.75%.

Preparation of Polyurethane Lacquer According to the Invention

Among the stoichiometric amounts of polyols for forming the polyisocyanates listed in the table below according to the compositions listed below, the conventional additive Baysilone® OL 17 (Bayerge, Leverkusen, Germany), flow enhancer, 0.1% solids for solid binder vehicle) and Mododaflow® (Monsanto Corp., Solutia Inc., USA; 0.01% solids for solid binder vehicle) It was added and processed.

Example 3

Lacquer Composition A

Desmodur® N3300 (Bay AG, Leverkusen, Germany) blocked with cyclopentanone-2-carboxymethyl ester (supplied as a solution of about 50% in butyl acetate; blocked NCO content: 6.2%) ( SN = solvent naphtha)

weight% Desmophen® A 870 (Bayer AG, Leverkusen, Germany), 70% solution in BA 35.94 Desmodours® N3300. Blocked with cyclopentanone-2-carboxymethyl ester (50% solution in BA from Example 1) 34.82 Bisilon® OL 17, 10% solution in xylene 0.48 Modaflow®, 1% solution in xylene 0.48 Tinuvin® 292 (Ciba AG, Basel, Switzerland), 10% solution in xylene 4.78 Tinuvin® 1130 (Shiba Age, Basel, Switzerland), 10% solution in xylene 9.56 Bismuth 2-ethylhexanoate, 10% solution in MPA 7.17 MPA / SN 100 (1: 1) 6.77 Sum 100.00 Blocked NCO / OH ratio: 1.0, solids content: about 45%, catalyst content: 1.5% (solids to solid binder vehicle)

This system showed only very slight yellowing. This system could also be used successfully with an NCO / OH ratio of 1: 1.5.

Lacquer Composition B (Comparative)

weight% Desmophen® A 870, 70% solution in BA 37.15 Mixed trimer of hexamethylene diisocyanate and IPDI, blocked with diisopropylamine (50% solution in BA) 33.88 Bisilon® OL 17, 10% solution in xylene 0.48 Modaflow®, 1% solution in xylene 0.48 Tinuvin® 292 (Shiba Age, Basel, Switzerland), 10% solution in xylene 4.80 DBTL, 10% solution in xylene 4.80 Tinuvin® 1130 (Shiba Age, Basel, Switzerland), 10% solution in xylene 9.61 MPA / SN 100 (1: 1) 8.80 Sum 100.00 Stoving conditions: 30 minutes at 140 ℃

In the case of solvent-containing lacquers, the system showed a clear yellow coloration even at relatively low stoving temperatures. The delta b value at 3.2 to 160 ° C. (30 min) was 3.2 and therefore, in each case, when applied on a base lacquer containing a white solvent, the system showed only slight yellowing (eg dimethylpyrazole). About 4 times higher than for delta b.

Determination of Yellowing Due to Overstorving: After the lacquer was stowed at 140 ° C. for 30 minutes, the first coloring measurement was measured using a method called CIELAB method. The higher the value of positive b measured by this method, the more yellow the clear lacquer. Then overstove at 160 ° C. for 30 minutes. The increase in yellow coloration, called the Δb value, was then measured according to the CIELAB color system (DIN 6174, "Colorimetric determination of color separations for body colors according to the CIELAB formula" (Edition 01.79)). For a non-yellowing clear lacquer, this value should be as close to zero as possible.

Examples for coil coating applications

Starting material: blocked polyisocyanate

Preparation of Polyisocyanates Blocked with Acid α-cyclic Ketones

Blocked Polyisocyanate A:

0.17 in 14 g of methoxypropyl acetate (8 parts) and 29.9 g of xylol (17 parts) (70% total solution) to dissolve 193.5 g (1 equivalent) of Desmodour® N3300 g of zinc-2-ethylhexanoate (0.05 wt.%) was dissolved as catalyst. The following reaction was carried out in a nitrogen atmosphere. After the mixture was stirred homogeneously, 156.2 g (1 equivalent) of cyclopentanone-2-carboxyethylester (distilled) was carefully added dropwise. At this time, the reaction temperature should not exceed 40 ° C. After the addition of the ester was complete, stirring was continued at 40 ° C. until the NCO value reached zero (after about 6 minutes). The theoretical value of blocked NCO content was 8.3%. Thereafter it was adjusted to the desired viscosity with 7% 2-butanol on solids. 2.5% Tinuvin® 770 DF was also added to the solids (8.7 g). The polyisocyanate added was an HDI-polyisocyanate (Desmodur® N 3300, Bayer AG, Leverkusen) having an isocyanurate structure and having an NCO content of 21.8% and a viscosity of 3000 mPas.

Blocked Isocyanate B:

Three equivalents (580.5 g) of Desmodur® N3300 and one equivalent (353 g) of Desmodur® Z4470 were dissolved in 415 g of xylol under nitrogen (70% mixture after reaction). For this mixture, 1.45 g (0.1 wt.%) Zinc-2-ethylhexanoate was added as catalyst. After the mixture was stirred homogeneously, 4 equivalents (624.8 g) of cyclopentanone-2-carboxyethylester was carefully added dropwise. At this time, the reaction temperature should not exceed 40 ° C. After the addition of the ester was complete, stirring was continued at 40 ° C. until the NCO value approached zero (about 12 hours). The blocked NCO content was 8.1%. After the reaction was completed, 101.7 g of 2-butanol (7% for solids) and 29 g (2% for solids) of Tinuvin® 770 DF were added. The added polyisocyanates have an isocyanurate structure and have HDI-polyisocyanate (20.0% NCO content and 3000 mPas) (Desmodur® N3300, Bayer AG, Leverkusen) and IPDI [NCO content 11.9% And a viscosity of 2000 mPas, Desmodur® Z4470, Bayer AG, Leverkusen) polyisocyanate having an isocyanurate structure.

Blocked Polyisocyanate C:

0.9 equivalents (174.2 g) of Desmodours® N3300 and 0.1 equivalents (29 g) of Desmodours® W-trimer were dissolved in 141.6 g of xylol under nitrogen (70% after reaction). mixture). For this mixture, 0.351 g (0.1 wt.%) Zinc-2-ethylhexanoate was added as catalyst. After the mixture is stirred homogeneously, one equivalent (156.2 g) of cyclopentanone-2-carboxyethylester is carefully added dropwise. At this time, the reaction temperature should not exceed 40 ° C. After the addition of the ester was complete, stirring was continued at 40 ° C. until the NCO value approached zero (about 12 hours). The blocked NCO content was 8.16%. After the reaction is complete, 7 g (2% of solids) tinuvin 770 DF is added. The added polyisocyanates have an isocyanurate structure, HDI-polyisocyanate (Desmodur® N3300, Bayer AG, Leverkusen) and Desmodur W (13.5) having an NCO content of 21.8% and a viscosity of 3000 mPas. Mixture of polyisocyanates with isocyanurate structure based on% Desmodur® N3300, trimerization rate 20%, NCO content 14.5%, 65% solids (dissolved in xylol / methoxypropylacetate) It was.

The blocking agent used, cyclopentanone-2-carboxyethyl ester, was purchased from Fluka.

Comparison of Blocked Isocyanates Considered:

BL 3175 (Bayer AG), hexamethylene diisocyanate-based crosslinked stoving urethane resin dissolved 75% in solvent naphtha 100, viscosity about 3300 mPas, (blocked) NCO content about 11.1%, blocking agent buta Nonoksim.

BL 3370 (Bayer AG), aliphatic crosslinked stoving urethane resin dissolved about 70% in 1-methoxypropylacetate-2 (MPA), viscosity about 3500 ± 1200 mPas, (blocked) NCO content about 8.9%, the blocking agent is diisopropylamine.

Polyols used: see the following table.

Preparation of Polyurethane Lacquer According to the Invention

The preparation of the lacquers according to the invention is described according to the preparation rules for balllocked isocyanate components.

Polyols Suitable for Coil Coating Methods Registered trademark type Supply mode Viscosity [mPas] Acid OH-ratio [%] Equivalent weight Alkynol 1665 SN / IB Oil-free branched saturated polyester 65% SN100 / IB 2700 ± 300 ≤5.5 About 1.7 1000 Alkynol VP LS 2013 Oil-free branched polyester 70% SN100 4000 ± 200 5.0 ± 1.0 About 2.0 850 Alkynol VP LS 2326 Oil-free branched saturated polyester 60% SN100 About 1500 About 2.2 0.6 2830 Desmophen 651 MPA Branched polyester 67% MPA 14500 ± 3500 ≤3.0 5.5 ± 0.4 309 Desmophen 670 Weakly branched polyester Solvent free > 200000 ≤2.5 4.3 ± 0.4 395 Desmophen 690 MPA Branched polyester 70% MPA 10000 ± 3500 ≤6.0 1.4 ± 0.2 1214 Desmopen 1200 Weakly branched polyester Solvent free 300 ± 100 (70% of MPA) ≤4.0 About 5.0 340 Desmophen 1652 Oil-free linear polyester Solvent free 11000 ± 2000 ≤4.0 1.6 ± 0.2 1063 Desmophen C 200 Linear polycarbonate-polyester Solvent free 1050 ± 250 (75 ℃) ≤0.1 1.7 ± 0.2 1000

1C-PUR-Coil Coated Deck Lacquer, White, Polyol Component Alkynol® 1665

A = polyisocyanate A, B = polyisocyanate B, C = polyisocyanate C

One 2 3 4 5 Bead Grinding Formulations (Particle Size <5 μm) BL 3175 BL 3370 A B C Alkynol 1665, 65% solution in solvent naphtha 100 / isobutanol 31.5: 3.5 9.8 9.8 9.8 9.8 9.8 Kronos 2160 29.3 29.3 29.3 29.3 29.3 Solvesso 200 S (SN 200 S) 7.8 7.8 7.8 7.8 7.8 lacquer Alkynol 1665, supplied at 65% 21.5 20.0 19.3 19.1 19.2 Desmodour BL 3175, 75% solution in solvent naphtha 100 11.9 Desmodour BL 3370, 70% solution in 1-methoxypropylacetate-2 14.1 A, 70% solution in xylol / MPA 17: 8 14.8 B, 70% solution in xylol 15.0 C, 70% solution in xylol 14.9 Zinc-2-ethylhexanoate, 10% solution in SN 200 S 0.7 0.7 0.7 DBTL, 10% Solution in SN 200 S (3) 0.7 0.7 Acronal 4 F, 50% solution in SN 200 S (4) 1.5 1.5 1.5 1.5 1.5 CAB 531-1, 10% solution in SN 200 S / butyldiclicol 2: 1 (5) 7.3 7.3 7.3 7.3 7.3 SN 200 S 10.3 9.6 9.6 9.6 9.6 100.0 100.0 100.0 100.0 100.0 Comparative Example According to the present invention

Property Data Binder29.3

Pigment29.3

Additive 1.5

Solvent39.3

100.00

OH / NCO ratio 1: 1

Binder / Pigment Ratio

Solid content (% by weight) about 60

Thinner Solveso 200 S

Application viscosity

DIN EN ISO 2431 (5 mm nozzle / 23 ° C) approx. 100 s

Storing conditions PMT: see test results

weight%

Additive Catalyst Additives0.2

(With binder-FK

Calculated for

Active substance)

Acronal 4F2.6

Cellulose Acetobutyrate 2.5

Note The combination of (4 + 5) CAB and Acronal 4F is used for degassing and melting.

Sources (1) Kronos International INC, Leverkusen, Germany

(2) Deutsche Exxon, Cologne, Germany

(3) Brendantag, Muhlheim / Luer, Germany

(4) BASF AG, Ludwigshafen, Germany

(5) Krahn Chemie, Hamburg, Germany

Additive raw materials

Alkinol® 1665 , isophthalic acid / adipic acid / NPG / propylglycol oil-free saturated polyesters, Bayer AG, Leverkusen, OH content: solvent naphtha 100 / isobutanol 31.5: 3.5 for 65% feed form 1.7%

CAB (Cellulose Acetobutyrate), Source: Cranchemy, Hamburg, Germany, Eastman Kingsport, USA, CAB 531-1 (about 53% butyryl content, hydroxyl content 1.7% -not calculated Not)

Acronal (R) 4 F , manufacturer: BASF, Ludwigshafen, Germany, butyl acrylate polymer (melting agent and bubble remover)

Solvesso® 200 S , manufactured by Esso / Exxon, solvent aromatic content: 99%, evaporation rate (ether = 1): ~ 1000

Crystal of whiteness

ASTM E 313, White Index

Degree of white according to Berger (not DIN)

Whiteness = Ry + 3 (Rz-Rx)

The yellow index (G) according to DIN 6167 is calculated according to the formula:

G = (ax-bz) / y × 100

x, y + z = normal color values according to DIN 5033

a = red / green axis *

b = blue / yellow axis **

* Positive value → Red tone value → Green side

** Positive value → Yellow negative value → Blue side

MEK-determination of durability

Explanation of the method (according to ECCA-T11 and DIN EN ISO 28121 and DIN EN 12720):

The MEK-smear test is a rapid test to test the final hardness of lacquer film. For this purpose, the cotton pads infiltrated with MEK are moved back and forth on the lacquer film at a constant pressure.

Device / Auxiliary Means: Balance (Marke Bizerba), weight 100 g, 1 kg, and 2 kg

Perform:

1 kg-counter pressure is used for layer thicknesses up to 20 μm and 2 kg-counter pressure is used for layer thicknesses above 20 μm.

On the weighing dish of the balance, the test plate is fixed by a film clamp and an anti-slip foil. The balance is adjusted by 100 g weight and tare weight adjustment. The cotton pads infiltrated with MEK are moved back and forth on the lacquer film until the lacquer film breaks for the selected test pressure.

evaluation:

The number of before and after cycles performed until the coating breaks should be indicated within the test area, and a maximum of 100 before and after cycles should be performed. After 100 back and forth cycles have been reached, the film is evaluated in terms of change (matting, softening).

Determination of the T-Bending Test

Explanation of the method according to the European Coil Coating Association (ECCA) T7:

purpose:

This method accounts for the determination of the resistance of the organic coating to crack formation at 180 ° bending.

principle:

In this test, a sample with a coating on the outer side is bent at 180 ° parallel to the rolling direction for 1-2 seconds. Close contact should be made between the plates to ensure equal bending. The smallest bend radius that produces a crack free bend of the sample determines the resistance at 180 ° bend. The adhesion here is checked by Scotch tape after each bend.

Device:

The apparatus capable of performing this method consists of a vice and a set of jaws.

Ready:

The sample is placed at room temperature and room humidity for at least 24 hours. The measurement is carried out under the same conditions.

When the exact conditions are specified or in any case, the indication according to ISO 3270-1984, ie a temperature of 23 ± 2 ° C. and a relative humidity of 50 ± 5%, should be considered.

Way:

A strip of plate about 2 cm wide is cut opposite to the rolling direction. This plate strip with the coating on the outer side is bent at 180 ° parallel to the rolling direction for 1-2 seconds. Thereafter, the plate is pressed closely in a vise.

Bend edges are inspected for cracks with a 20x magnifier. The adhesion is then checked by three attachments and removals of the Scotch tape.

The evaluation of this 0 T bend is made with R for cracks and with H for adhesion evaluated from 0 to 5, with 0 being the best value and 5 being the worst value.

Now, the plate is bent until a crack is formed and the adhesion reaches a value of zero.

The test ends at 3.0 T at the latest.

Rupture resistance

The formed T-bending strip is warmed at 100 ° C. for 30 minutes and then again evaluated for cracks.

Lacquer manufacture:

Testing is done according to the standard method (reference method RR 6830) in white coil coated deck lacquer. To this end, powders are first prepared from oil-free saturated polyesters according to the following bead grinding formulations.

9.8 Non-oil-free polyester, alkynol® 1665, supplied as 65%

7.8 solvents, Solvesso® 200 S

22.3 Pale white pigment, Chronos 2330

The powder is dispersed with 2 mm of silicate crystal beads.

Dispersion takes place in a Skandex® mixer for 1 hour.

(Note: In bead mills and Scandex® mixers (shakers), the same formulation can be worked in. In Scandex® mixers, a plurality of samples are simultaneously dispersed and friction plated in the following vessels. There is an advantage, after which the sieving of the beads takes place at the exit.)

The powder is separated by beating from glass beads.

The remaining lacquer components are added during stirring.

21.5 Non-oil-free polyester, supplied as alkynol® 1665, 65%

11.9 part blocked polyisocyanate *)

0.7 parts DBTL, 10% of Solvesso® 200 S

7.3Butcellulose acetobutyrate CAB 531-1, 10% in Solvesso® 200 S / butyldiglycol 2: 1

1.5% Acrinol® 4 F, 50% in Solvesso® 200 S

Xbu Solbeso® 200 S (10.3 parts as polyisocyanate blocked in BL 3175)

*) The amount of addition to the blocked PIC varies with the equivalent of the PIC (in this case compared to Desmodur® BL 3175). Polyols and blocked polyisocyanates are equivalently combined. That is, if a small amount of blocked NCO groups is available, the ratio of blocked PIC should be high. Equivalent weights are given in the reference sheet.

The adjustment of the lacquer to a working viscosity of about 70 seconds DIN 4/23 ° C. is done by Solvesso® 200 S.

Application of the lacquer to the chromed aluminum plate (1 mm thick) is done by scraper.

Immediately after application of the lacquer, the plate is stowed on a turntable in a long auxiliary furnace.

30 seconds at PMT 210 ℃ 350 ℃ furnace temperature

33 sec at PMT 216 ℃ 350 ℃ furnace temperature

35 seconds at PMT 224 ℃ 350 ℃ furnace temperature

38 seconds at PMT 232 ℃ to 350 ℃ furnace temperature

50 sec at PMT> 254 ℃ 350 ℃ furnace temperature

The dried layer thickness was 20 to 22 μm.

Coil Coating Lacquer Binder: Alkinol 1665 Binder Ratio: Equivalent Pigment: Titanium Dioxide Chronos 2330 Binder-Pigment Ratio: 1: 1 Catalyst: (relative to binder solids) 0.2% Stoving conditions: 232 ° C (PMT) Number of dumbbells: 42 Substrate: Al plate pretreated with bonder 772 Blocked Polyisocyanates Studyed BL 3175 Example A Example B Example C BL 3370 Layer Thickness [μm] ECCA-T1 (* 1) 20-22 20-22 20-22 20-22 20-22 Whiteness W = Ry + 3 (Rz-Rx) (according to Berger) 92.3 91.6 92.2 91.4 91.6 Yellow index -3.1 -2.4 -2.6 -2.5 -2.8 According to Gloss Gardner 60 °, ECCA-T2 (1 *) 76 67 68 65 69 MEK-Smear Test (PMT196 ℃) / Whiteness - - - - 95X / 92.4 MEK-Smear Test (PMT199 ℃) / Whiteness 10X / 94.1 100X / 94.6 65X / 94.0 100M / 93.9 100X / 92.4 MEK-Smear Test (PMT204 ℃) / Whiteness 95X / 93.6 100X / 94.6 100M / 94.3 100X / 94.4 100X / 92.5 MEK-Smear Test (PMT210 ℃) / Whiteness 100X / 93.6 100X / 94.2 100X / 94.0 100X / 94.1 100X / 92.4 MEK-Smear Test (PMT216 ℃) / Whiteness 100X / 93.3 100X / 93.8 100X / 94.0 100X / 94.2 100X / 92.0 MEK-Smear Test (PMT224 ℃) / Whiteness 100X / 93.1 100X / 93.0 100X / 92.9 100X / 93.2 100X / 91.8 MEK-smear test (PMT232 ℃) 100X 100X 100X 100X 100X Fine Hardness HU Calibration Value (N / mm2) 3 Measurement Averages 128.7 55.1 99.8 86.0 140.7 Shock Test [inch / pound] ECCA-T5 (* 1) 80 80 80 80 80 6 mm cupping index ECCA-T6 in adhesive cross section (* 1) 0 0-1 0 0 0 T-Bending Test T0.0 R5 H1 R5 H1 R5 H1 R5 H1 R5 H1 R = crack T0.5 R1 H0 R1 H0 R2 H0 R2 H0 R1 H0 H = Adhesive T1.0 R0 R0 R0 R0 R0 0 = best value T1.5 5 = Worst value T2.0 Burst Test 30 minutes 100 ℃ T1.5 + T1.0- T1.5 + T1.0- T1.5 + T1.0 + T1.5 + T1.0 + T1.5 + T1.0- (* 1): Depends on not measured in the air-conditioned space -= Lowered, + = not lowered

Claims (12)

An organic polyisocyanate comprising at least two isocyanate groups, wherein the isocyanate is blocked with an acidic CH cyclic ketone of the formula (I), wherein the content of the blocked isocyanate groups (calculated as NCO) is 0.1 to 20% by weight in total. <Formula I> Where X is an electron attractor R ¹ and R ² independently of one another are radicals H, C ₁ -C ₂₀ (cyclo) alkyl, C ₆ -C ₂₄ aryl, C ₁ -C ₂₀ (cyclo) alkyl esters or amides, C ₆ -C ₂₄ aryl esters or Amides, or mixed aliphatic / aromatic radicals having 1 to 24 carbon atoms, which may form part of 4 to 8 membered rings, n is an integer of 0-5. The group of claim 1, wherein the electron withdrawing group X comprises an ester group, a sulfoxide group, a sulfone group, a nitro group, a phosphonate group, a nitrile group, an isonitrile group, a polyhalogen alkyl group, a fluorine, a chlorine or a carbonyl group Selected organic polyisocyanate. The cyclopentanone-2-carboxymethyl ester and cyclopentanone-2-carboxyethyl ester, cyclopentanone-2-carboxylic acid nitrile, cyclohexanone- according to claim 1, wherein the acidic CH cyclic ketones of formula I are An organic polyisocyanate characterized in that it is 2-carboxymethyl ester and cyclohexanone-2-carboxyethyl ester or cyclopentanone-2-carbonylmethyl. The cyclopentanone-2-carboxymethyl ester and cyclopentanone-2-carboxyethyl ester, or cyclohexanone-2-carboxymethyl ester and cyclohexanone of claim 1, wherein the acidic CH cyclic ketones of formula I Organic polyisocyanate, characterized in that it is 2-carboxyethyl ester. Reacting the polyisocyanate with an acidic CH cyclic ketone of the formula (I) in the presence of a catalyst, wherein 0.8 to 1.2 moles of the cyclic ketone of the formula (I) are used per equivalent of isocyanate groups of the polyisocyanate to be blocked A process for producing the organic polyisocyanate of claim 1. <Formula I> Where X is an electron attractor R ¹ and R ² independently of one another are radicals H, C ₁ -C ₂₀ (cyclo) alkyl, C ₆ -C ₂₄ aryl, C ₁ -C ₂₀ (cyclo) alkyl esters or amides, C ₆ -C ₂₄ aryl esters or Amides, or mixed aliphatic / aromatic radicals having 1 to 24 carbon atoms, which may form part of 4 to 8 membered rings, n is an integer of 0-5. The method of claim 5 wherein the organic polyisocyanate contains a uretdione, isocyanurate, iminooxadiazinedione, acylurea, biuret or allophanate structure. 6. Process according to claim 5, characterized by the use of alkali and alkaline earth metal bases, zinc salts or other Lewis acids as catalysts. PUR-lacquer containing the organic polyisocyanate of claim 1. 9. PUR-lacquer according to claim 8, characterized in that it is a monocomponent (1C) PUR-lacquer. Use of the organic polyisocyanate of claim 1 as a filler. Use of the organic polyisocyanate of claim 1 as a coil coating. A coating of PUR-lacquer containing the blocked organic polyisocyanate of claim 1.