NZ530396A

NZ530396A - Cyclic ketones as blocking agents

Info

Publication number: NZ530396A
Application number: NZ530396A
Authority: NZ
Inventors: Michael Schelhaas; Christoph Gurtler; Beate Baumbach; Christian Fussel
Original assignee: Bayer Ag
Priority date: 2001-07-03
Filing date: 2002-07-03
Publication date: 2005-07-29
Also published as: HK1069181A1; HUP0401289A3; WO2003004545A1; HUP0401289A2; EP1404737A1; JP4118803B2; MXPA03011808A; CN100467511C; JP2004533526A; CA2451744A1; KR100875808B1; KR20040015326A; HU226903B1; BR0210799A; CN1524099A; PL367450A1

Abstract

The invention relates to blocked polyisocyanates, from which high quality, crack-free coatings and paint lacquers with low yellowing index may be obtained, a method for production thereof and use thereof in single component polyurethane systems. Such polyisocyanates are blocked at the isocyanate group with acidic CH cyclic ketones of general formula (I) wherein: X is an electron-attracting group, R1 and R2 independently of each other represent the radicals H, a C1-C20 (cyclo)alkyl, a C1-C24 aryl, a C1-C20 (cyclo)alkyl ester or amide, a C1-C24 aryl ester or amide or mixed aliphatic/aromatic radicals comprising 1-24 carbon atoms which can also form part of a 4-8 membered ring N is an integer from 0-5, And which have a content of blocked isocyanate groups (calculated as NCO) of 0.1-20% by weight in total.

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number 530396 WO 03/004545 Cyclic ketones as blocking agents The present invention relates to new blocked polyisocyanates, to a method of producing them and to the use thereof in single-component polyurethane systems. 5 Blocking of polyisocyanates to effect temporary protection of the isocyanate groups thereof is a procedure which has long been known, and is described, for example, in Houben Weyl, Methoden der organischen Chemie XIV/2, pages 61-70. Hardenable compositions which contain blocked polyisocyanates are used in polyurethane lacquers, for example, preferably 10 single-component (1C) polyurethane systems. ^ Single-component (1C) polyurethane systems are widely used in the field of industrial stoving lacquers such as mass-production automobile coating and coil coating, and are distinguished by their very good film properties, such as resistance to chemicals, scratch-resistance and 15 resistance to weathering. These lacquer films are hardened by thermal activation (by a stoving operation) of the blocked polyisocyanates with polyols, optionally in the presence of a suitable catalyst. A review of blocking agents which are suitable in principle here is given by 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 example. 20 25 For use in the field of automobile coating, the blocked polyisocyanates must be crosslinkable at maximum stoving temperatures of 140°C, and must only exhibit very slight yellowing, and preferably no yellowing, during the stoving operation. The stoving temperature is mainly controlled via the reactivity of the blocked polyisocyanate. Most stoving systems, such as melamine-formaldehyde and urea-formaldehyde resins, for example, are characterised by the release of volatile constituents during hardening, which increase the VOC value. Moreover, a certain proportion of the blocking agent remains in the lacquer film which is formed and has a disadvantageous effect on the properties thereof. Due 30 to the blocking agent which remains, properties such as the scratch-resistance and acid-resistance of single-component lacquer films are not comparable with those of what are termed two-component (2C) polyurethane lacquer coatings (e.g. T. Engbert, E. Konig, E. Jiirgens, Farbe&Lack, Curt R. Vincentz Verlag, Hannover 10/1995). Furthermore, separation WO 03/004545 PCT/EP02/07325 -2- of the blocking agent and the escape thereof in gaseous form from the lacquer film can also lead to bubble formation in the lacquer film. Subsequent incineration of the emitted blocking agent can sometimes be necessary. 5 Isocyanates blocked with diethyl malonate have mainly been used recently for particularly low stoving temperatures within the range from 90 to 120°C (e.g. EP-A 0947531). In contrast to blocking procedures which employ heterocyclic N compounds, such as caprolactam or butanone oxime, for example, the blocking agent as a whole is not split off or separated here; rather, this blocking agent results in a transesterification reaction on the isocyanate which is 10 blocked with diethyl malonate. Ethanol is separated during this transesterification. This method can be employed at relatively low stoving temperatures, since the second, adjacent ) ester function is an activated ester. The disadvantage of this method is that systems such as these are extremely susceptible to the effect of acids, because the labile ester bond can be rapidly cleaved. The possibilities for the use of these products are thereby restricted. 15 The object of the present invention was to provide new blocked polyisocyanate systems which react without separation of the blocking agent, i.e. free from emissions, and which exhibit low crosslinking temperatures. The object was also that these blocked polyisocyanate systems should be stable on storage at ambient temperature, and that they should be suitable, 20 particularly in combination with suitable polyol components, for the production of single-component stoving lacquers. ^ Surprisingly, it has now been found that acidic CH compounds which possess the basic structure of an activated cyclic ketone, particularly that of cyclopentanone-2-carboxymethyl 25 ester, are particularly suitable for blocking polyisocyanates in order to obtain emission-free coatings with a reduced tendency to exhibit yellowing. The present invention relates to organic polyisocyanates comprising at least two isocyanate groups, the isocyanate groups of which are blocked with acidic CH cyclic ketones of general 30 formula (I), WO 03/004545 PCT/EP02/07325 5 X is an electron-attracting group, independently of each other, represent the radicals H, a C1-C20 (cyclo)alkyl, a C6-C24 aryl, a C1-C20 (cyclo)alkyl ester or amide, a C6-C24 aryl ester or amide, or mixed aliphatic/aromatic radicals comprising 1 to 24 carbon atoms, which can also form part of a 4 to 8-membered ring, n is an integer from 0 to 5, and which have a content of blocked isocyanate groups (calculated as NCO) of 20 to 0 % by 15 weight in total. A content of blocked isocyanate groups (calculated as NCO) ranging from 0.1 to 15.6 % by weight is preferred. A content of blocked isocyanate groups (calculated as NCO) ranging ^ from 0.1 to 14 % by weight is particularly preferred. Partial blocking of the polyisocyanate 20 can optionally be effected; the non-blocked isocyanate groups can then be used for further reactions. Typically, all the isocyanate groups are blocked. The electron-attracting group X can comprise any substituent which results in the a-terminal hydrogen exhibiting an acidic CH character. This substituent can comprise ester groups, 25 sulphoxide groups, sulphone groups, nitro groups, phosphonate groups, nitrile groups, isonitrile groups or carbonyl groups. Nitrile and ester groups are preferred, whilst methyl carboxylate and ethyl carboxylate groups are particularly preferred. R1 and R2, 10 WO 03/004545 PCT/EP02/07325 -4- Compounds of general formula (I), the ring of which optionally contains hetero atoms such as oxygen, sulphur or nitrogen atoms, are also suitable. The activated cyclic ketone of formula (I) preferably has a ring size of 5 (n = 1) or 6 (n = 2). 5 Preferred compounds of general formula (I) include cyclopentanone-2-carboxymethyl ester and -carboxyethyl ester, cyclopentanone-2-carboxylic acid nitriles, cyclohexanone-2-carboxymethyl ester and -carboxyethyl ester, or cyclopentanone-2-carbonylmethyl. Cyclopentanone-2-carboxymethyl ester and -carboxyethyl ester, as well as cyclohexanone-2-10 carboxymethyl ester and -carboxyethyl ester, are particularly preferred. The cyclopentanone systems can readily be obtained industrially by the Dieckmann condensation of dimethyl adipate or of diethyl adipate. Cyclohexanone-2-carboxymethyl ester can by be obtained by the hydrogenation of methyl salicylate. The polyisocyanate to be blocked can be any organic polyisocyanate which is suitable for the crosslinking of compounds comprising active hydrogen, i.e. aliphatic polyisocyanates, including cycloaliphatic polyisocyanates, as well as aromatic and heterocyclic polyisocyanates comprising at least two isocyanate groups and mixtures thereof. Typical examples of polyisocyanates include aliphatic isocyanates such as di- or triisocyanates, e.g. butane diisocyanate (BDI), pentane diisocyanate, hexane diisocyanate (HDI), 4-isocyanatomethyl-l,8-octane diisocyanate (triisocyanatononane, TIN), or cyclic systems such as 4,4'-methylene-bis(cyclohexyl isocyanate) (Desmodur W®, Bayer AG, Leverkusen), 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethyl-cyclohexane (IPDI), as well as (O,(o'-diisocyanato-1,3-dimethylcyclohexane (HeXDI). Examples of aromatic polyisocyanates include 1,5-naphthalene diisocyanate, diisocyanato-diphenylmethane (MDI) or crude MDI, diisocyanatomethylbenzene (TDI), particularly the 2,4- and the 2,6-isomers thereof and industrial mixtures of the two isomers thereof, as well as l,3-bis(isocyanato-methyl)benzene (XDI). 30 Polyisocyanates which are also very suitable are those which can be obtained by the reaction of di- or triisocyanates with themselves via their isocyanate groups, such as uretdiones or carbodiimide compounds, or such as isocyanurates or iminooxadiazinediones which are formed by the reaction of three isocyanate groups. The polyisocyanates can also contain 15 20 25 WO 03/004545 PCT/EP02/07325 -5- monomeric di- and/or triisocyanates and/or oligomeric polyisocyanates comprising biuret, allophanate and acylurea structural elements, triisocyanates which have a low monomer content or partially modified monomeric di- or triisocyanates, as well as any mixtures of the aforementioned polyisocyanates. 5 Polyisocyanate prepolymers which on average contain more than one isocyanate group per molecule are also very suitable. These are obtained by the preliminary reaction of a molar excess of one of the aforementioned polyisocyanates, for example, with an organic material which contains at least two active hydrogen atoms per molecule, e.g. in the form of hydroxy 10 groups. ^ The preferred polyisocyanates are those which contain a uretdione, isocyanurate, iminooxa-diazinedione, acylurea, biuret or allophanate structure, e.g. those which are based on butane diisocyanate (BDI), pentane diisocyanate, hexane diisocyanate (HDI), 4-isocyanatomethyl-15 1,8-octane diisocyanate (triisocyanatononane, TIN) or on cyclic systems such as 4,4'-methylene-bis(cyclohexyl isocyanate) (Desmodur W®, Bayer AG, Leverkusen), 3,5,5-trimethyl-l-isocyanato-3-isocyanatomethylcyclohexane (IPDI), as well as a),co'-diisocyanato-1,3-dimethylcyclohexane (HeXDI). Examples of aromatic polyisocyanates include 1,5-naphthalene diisocyanate, diisocyanato-diphenylmethane (MDI) or crude MDI, 20 diisocyanatomethylbenzene (TDI), particularly the 2,4- and 2,6-isomers thereof and industrial mixtures of both isomers thereof, as well as l,3-bis(isocyanato-methyl)benzene (XDI). ^ Polyisocyanates which are particularly preferred are those based on hexane diisocyanate (HDI), on 4,4'-methylene-bis(cyclohexyl isocyanate) or on 3,5,5-trimethyl-l-isocyanato-3-25 isocyanatomethylcyclohexane (IPDI). The present invention further relates to a method of producing the blocked organic polyisocyanates according to the invention, characterised in that polyisocyanates are reacted with acidic CH cyclic ketones of general formula (I), WO 03/004545 PCT/EP02/07325 -6- O R 2 R X ■H (I), wherein X is an electron-attracting group, R1 and R2, independently of each other, represent the radicals H, a C1-C20 (cyclo)alkyl, in the presence of a catalyst, wherein 0.8 to 1.2 mol of the cyclic ketone of formula (I) are used per isocyanate group equivalent of the polyisocyanate to be blocked. One isocyanate group equivalent of the polyisocyanate to be blocked is preferably reacted with 1 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 ketone used, trisodium phosphate or Dabco (l,4-diazabicyclo[2.2.2]octane) can also be used. Carbonates of metals of subgroup II are also suitable. Sodium carbonate or potassium carbonate is preferably used. Alternatively, the reaction of the cyclic ketone with the isocyanate can also be conducted in the presence of zinc salts as catalysts. Reaction with zinc 2-ethylhexanoate is particularly preferred. C6-C24 aryl, a C1-C20 (cyclo)alkyl ester or amide, a C6-C24 aryl ester or amide, or mixed aliphatic/aromatic radicals comprising 1 to 24 carbon atoms, which can also form part of a 4 to 8-membered ring, and n is an integer from 0 to 5, 0.05 to 10 % by weight, preferably 0.1 to 3 % by weight of a catalyst, is added when conducting the method according to the invention. 0.2 to 1 % by weight of catalyst is most preferably used. WO 01 4545 PCT/EP02/07325 -7- The reaction can be conducted at room temperature or at higher temperatures up to 140°C. A temperature range from 40 to 90°C is preferred, most preferably from 15°C to 90°C. Blocking can be effected free from solvents or in the presence of suitable solvents. Suitable solvents comprise customary lacquer solvents such as butyl acetate, methoxypropyl acetate or the solvent naphtha supplied by Exxon-Chemie (Esso Deutschland GmbH, Hamburg) as solvents which contain aromatic compounds, as well as mixtures of the aforementioned solvents. Blocking is preferably effected in the aforementioned solvents, wherein the solids content should be adjusted so that it ranges between 10 and 90 %. In addition to the cyclic ketones of general formula (I) which are used according to the invention, mixtures of any blocking agents can also be used in conjunction in the method according to the invention in order to achieve the lacquer properties which are required in each case, wherein the proportion of compounds of formula (I) is at least 30 % by weight, preferably 50 % by weight, most preferably 100 % by weight. The present invention also relates to the use of the blocked organic polyisocyanates according to the invention in primer surfacers. The present invention also relates to the use of the blocked organic polyisocyanates according to the invention in the coating of coils. The present invention also relates to coatings or PUR lacquers containing the blocked organic polyisocyanates according to the invention. Finally, the present invention also relates to a method of producing 1-C PUR stoving lacquers, characterised in that organic polyisocyanates according to the invention are used as a crosslinking component for organic polyhydroxyl compounds. The blocked polyisocyanates according to the invention are distinguished in that, in combination with a suitable organic polyhydroxyl compound and in the presence of suitable catalysts, they harden at stoving times of 15 to 30 minutes and at temperatures from 110 to 140°C, preferably from 120 to 140°C. The stoving times depend in particular on the amount of catalyst used. Stoving is preferably conducted for a period of 30 minutes at a temperature of 120-140°C. If the blocked polyisocyanates according to the invention are used for the production of coil coatings, the latter are cured using maximum stoving times of two minutes, preferably within 5 to a maximum of 35 seconds. The oven temperature is 300-400°C. The stoving conditions depend, of course, on the material used_and on the sheet metal thickness of the sheet metal strip to be coated. The oven temperature generally ranges from a minimum temperature of WO 03/004545 PCT/EP02/07325 -8- 180°C to a maximum temperature of 260°C PMT. A temperature range from 210°C to 245°C PMT is preferred. A range from 216°C to 241°C PMT is particularly preferred. The lacquer technology properties of the stoved lacquer coats, such as their resistance to solvents such as MEK (methyl ethyl ketone), their hardness, and their elasticity at a given stoving temperature 5 depend, amongst other factors, on the amount of catalyst used. Stoving is preferably effected for a period of 38 seconds at a temperature of 232°C. Temperatures of 216°C are also possible. An aluminium substrate results in a stoving time of 33 seconds. The optimum specific conditions are determined by oriented preliminary tests in the manner which is customary for one skilled in the art, and during the application concerned the temperatures in 10 the coil coating oven are monitored over a sensitive range. Examples of suitable catalysts for crosslinking include DBTL (dibutyltin dilaurate), titanium 2-ethylhexanoate, titanium tetraisopropylate and other common titanium(IV) compounds, zirconium 2-ethylhexanoate and other common zirconium(IV) compounds, aluminium triethylate, scandium trifluoromethanesulphonate, yttrium 2-ethylhexanoate, yttrium trifluoroethanesulphonate, lanthanum 2-ethylhexanoate, lanthanum trifluoromethanesulphonate, cobalt 2-ethylhexanoate, copper 2-ethylhexanoate, indium trifluoromethanesulphonate, gallium acetylacetonate, nickel acetylacetonate, lithium 2-ethyl-hexanoate, lithium trifluomethanesulphonate, sodium 2-ethylhexanoate, sodium acetate, sodium trifluoromethanesulphonate, magnesium 2-ethyl hexanoate, magnesium trifluoromethanesulphonate, calcium 2-ethylhexanoate, magnesium trifluoromethanesulphonate, calcium 2-ethylhexanoate, calcium trifluoromethanesulphonate, zinc 2-ethylhexanoate, zinc dithiocarbamate, zinc acetylacetonate, zinc tetramethylheptadionate, zinc salicylate, zinc chloride, and other common zinc(II) compounds, bismuth 2-ethylhexanoate and bismuth acetate. The preferred catalysts are zinc and bismuth compounds; zinc 2-ethylhexanoate and bismuth-2-ethylhexanoate are particularly preferred. Suitable polyhydroxyl compounds for this purpose of use, as well as further details regarding the production and use of stoving lacquers of this type, are given in the literature, e.g. in DE-30 A 19 738 497 or EP-A 0 159 117. Particularly preferred fields of application for the products according to the invention include the use thereof as crosslinking agents in automobile primer surfacers, and their use in the coil coating field. WO 03/004545 PCT/EP02/07325 -9- High-grade, non-separating coatings of lacquer coats with reduced yellowing tendencies are obtained with the blocked polyisocyanates according to the invention.. Moreover, the blocked polyisocyanates according to the invention can be cured using di- or polyamines. This reaction is preferably conducted at room temperature. It can be used for the production of lacquer coatings or workpieces. Polyester polyols, polycarbonate polyols and polyacrylate polyols can be used for the production of coil coatings. In principle, all binder vehicles which have a sufficiently high OH content can be used. Trade name or Trade Mark*) Type Form in which supplied Alkynol® 1665 SN/IB Oil-free, branched, saturated polyester 65%SN100/IB Alkynol® VP LS 2013 Oil-free, branched polyester 70% SN100 AlkynofVP LS 2326 Oil-free, branched, saturated polyester 60% SN100 Desmophen® 651MPA Branched polyester 67% MPA Desmophen®670 Slightly branched polyester Solvent-free Desmophen® 690 MPA Branched polyester 70% MPA Desmophen® 1200 Slightly branched polyester Solvent-free Desmophen® 1652 Oil-free, linear polyester Solvent-free Desmophen® C 200 Linear polycarbonate polyester Solvent-free *) Products of Bayer AG, Leverkusen, DE Apart from the aforementioned components, the binder vehicles according to the invention can also contain other stabilising additives, such as HALS amines or solvents, as well as up to 5 % by weight of an OH-functional hydrazide compound (based on the solids content of the finished lacquer). Examples of other additives also include CAB (cellulose acetobutyrate), as well as. Acronal® 4 F (flow enhancer and anti-foaming agent). WO 03/004545 PCT/EP02/07325 -10- A substance which can be used as a stabilising component against thermal yellowing is that which has already been cited in EP-A 0 829 500, namely the addition product formed from hydrazine hydrate and 2 mol propylene carbonate, which has the following formula (II) WO 03/004545 PCT/EP02/07325 - 11 - Examples 10 The polyisocyanate used was an HDI polyisocyanate with an isocyanurate structure, an NCO content of 21.8 %, and a viscosity of 3200 mPa.s (Desmodur® N3300, Bayer AG, Leverkusen). The cyclopentanone-2-carboxymethyl ester and cyclohexanone-2-carboxymethyl ester which were used as blocking agents were ordered from the Fluka company and were used without further purification. Preparation of polyisocyanates blocked with acidic a cyclic ketones Example 1 15 A solution of 58.5 g (0.3 equivalent) Desmodur N3300 in 81 ml butyl acetate was added, slowly and with intensive stirring, to a solution of cyclopentanone-2-carboxymethyl ester (42.7 g, 0.3 equivalent) dissolved in 20 ml butyl acetate. 1.02 g zinc 2-ethylhexanoate was added as a catalyst. The batch was heated to a temperature of 50°C, (for about 8 hours) until a determination of the NCO value gave a value of about 0.2 %. The theoretical blocked NCO 20 content was 6.2 %. Example 2 A solution of 42.6 g (0.25 equivalent) Desmodur® N3300 in 71.4 ml butyl acetate was added, 25 slowly and with intensive stirring, to a solution of cyclohexanone-2-carboxymethyl ester (42.6 g, 0.25 equivalent) dissolved in 20 ml butyl acetate. 0.9 g zinc 2-ethylhexanoate was added as a catalyst. The batch was heated to a temperature of 80°C, until a determination of the NCO value gave a value of about 0.3 % (after about 6 hours). The theoretical blocked NCO content was 5.75 %. 30 10 WO 03/004545 PCT/EP02/07325 - 12- Production of polyurethane lacquers according to the invention The polyisocyanates listed in the following Table were processed in stoichiometric amounts with polyols to form clear lacquers according to the formulations listed below, and with the addition of the customary additives Baysilone® OL 17 (Bayer AG, Leverkusen; flow enhancer, 0.1 % solids with respect to solid binder vehicle) and Modaflow® (Monsanto Corp., Solutia Inc., USA; 0.01 % solids with respect to solid binder vehicle). Example 3 Lacquer formulation A Desmodur N3300 (Bayer AG, Leverkusen), blocked with cyclopentanone-2-carboxymethyl ester (supplied as an approximately 50 % solution in butyl acetate; blocked NCO content: 6.2 15 %) (SN = solvent naphtha): % by weight Desmophen® A 870 (Bayer AG, Leverkusen), 70 % in BA 35.94 Desmodur® N3300. blocked with cyclopentanone 20 2-carboxymethyl ester (50 % in BA from Example 1) 34.82 Baysilone® OL 17, 10 % in xylene 0.48 Modaflow®, 1 % in xylene 0.48 ^ Tinuvin® 292 (Ciba AG, Basle, Switzerland), 10 % in xylene 4.78 Tinuvin-1130 (Ciba AG, Basle, Switzerland), 10 % in xylene 9.56 25 bismuth 2-ethylhexanoate, 10 % in MPA 7.17 MPA/SN 100(1:1) 6.77 Total 100.00 30 ratio of blocked NCO/OH: 1.0, solids content: about 45 %, catalyst content: 1.5 % (solid with respect to solid binder vehicle). WO 03/004545 PCT/EP02/07325 -13- The system exhibited only very slight yellowing. This system could also be used successfully when the NCO/OH ratio was 1:1.5. Lacquer formulation B (comparison') 5 % by weight Desmophen® A 870, 70 % in BA 37.15 mixed trimer of hexamethylene diisocyanate and IPDI, blocked with diisopropylamine (50 % in BA) 33.88 10 Baysilone® OL 17,10 % in xylene 0.48 Modaflow®, 1 % in xylene 0.48 ^ Tinuvin® 292 (Ciba AG, Basle, Switzerland), 10 % in xylene 4.80 Tinuvin® 1130 (Ciba AG, Basle, Switzerland), 10 % in xylene 9.61 DBTL, 10 % in xylene 4.80 15 MPA/SN 100(1:1) 8.80 Total 100.00 Stoving conditions: 30 minutes at 140°C. 20 In solvent-containing lacquers, even at relatively low stoving temperatures, this system exhibited a clear yellow coloration. The delta b value from 140 to 160°C (30 minutes) was 3.2, and was thus about four times higher than that of a system which exhibited only slight ^ yellowing (e.g. dimethylpyrazole), when applied over a white base lacquer which contained a solvent. 25 Measurement of yellowing due to over-stoving: after stoving the lacquers for 30 minutes at 140°C, a first colour measurement was made using what is termed the CIELAB method. The higher the positive b value which is determined in this manner, the more yellow the clear lacquer has become. This was followed by over-stoving for 30 minutes at 160°C. The increase 30 in yellow coloration was subsequently measured, namely what is termed the Ab value according to the CIELAB colour system (DIN 6174, "Colorimetric determination of colour WO 03/004545 PCT/EP02/07325 - 14- separations for body colours according to the CIELAB formula" (Edition 01.79). For non-yellowing clear lacquers, this value should be as close as possible to 0. Examples of coil coating applications 5 Starting materials: blocked polyisocyanates Production of polyisocyanates blocked with a-acidic cyclic ketones Blocked polyisocyanate A: 10 0.17 g zinc 2-ethylhexanoate (0.05 % by weight) was added as a catalyst to a solution of 193.5 g (1 equivalent) Desmodur® N3300 dissolved in 14 g methoxypropyl acetate (8 parts) ^ and 29.9 g xylene (17 parts) (overall, a 70 % solution). The subsequent reaction occurred under a nitrogen atmosphere. After the mixture had been homogeneously stirred, 156.2 g (1 equivalent) cyclopentanone-2-carboxyethyl ester (distilled) were carefully added drop-wise so 15 that the reaction temperature did not exceed 40°C. When the addition of the ester was complete, the batch was stirred at 40°C until the NCO value had reached zero (after about 6 hours). The theoretical blocked NCO content was 8.3 %. The desired viscosity was then set with 7 % 2-butanol with respect to the solids content. 2.5 % (8.7 g with respect to the solids content) Tinuvin® 770 DF were then added. The added polyisocyanate was an HDI 20 polyisocyanate with an isocyanurate structure, NCO content 21.8 %, viscosity 3000 mPas, (Desmodur® N 3300, Bayer AG, Leverkusen). ^ Blocked polyisocyanate B: 3 equivalents (580.5 g) Desmodur® N3300 and 1 equivalent (353 g) Desmodur® Z4470 were 25 dissolved in 415 g xylene (a 70 % mixture after reaction) under nitrogen. 1.45 g (0.1 % by weight) zinc 2-ethylhexanoate was added as a catalyst to this mixture. After the mixture had been homogeneously stirred, 4 equivalents (624..8 g) cyclopentanone-2-carboxyethyl ester were carefully added drop-wise so that the reaction temperature did not exceed 40°C. After addition of the ester was complete, the batch was stirred at 40°C until the NCO value was 30 zero (about 12 hours). The blocked NCO content was then 8.1 %. After the reaction was complete, 101.7 g 2-butanol (7 % with respect to the solids content) and 29 g (2 % with respect to the solids content) Tinuvin® 770 DF were added. The polyisocyanate used was a mixture of an HDI polyisocyanate with an isocyanurate structure, NCO content 21.8 %, WO 03/004545 PCT/EP02/07325 -15- viscosity 3000 mPas, (Desmodur® N3300, Bayer AG, Leverkusen) and of a polyisocyanate with an isocyanurate structure based on IPDI (NCO content 11.9%, viscosity 2000 mPas, Desmodur® Z4470, Bayer AG, Leverkusen),. 5 Blocked polyisocyanate C: 0.9 equivalent (174.2 g) Desmodur® N3300 and 0.1 equivalent (29 g) Desmodur® W trimer were dissolved in 141.6 g xylene (a 70 % mixture after reaction) under nitrogen. 0.351 g (0.1 % by weight) zinc 2-ethylhexanoate were added as a catalyst to this mixture. After the 10 mixture had been homogeneously stirred, 1 equivalent (156.2 g) cyclopentanone-2-carboxyethyl ester was carefully added drop-wise so that the reaction temperature did not ^ exceed 40°C. After addition of the ester was complete, the batch was stirred at 40°C until the NCO value was zero (about 12 hours). The blocked NCO content was then 8.16 %. After the reaction was complete, 7 g (2% with respect to the solids content) Tinuvin 770 DF were 15 added. The polyisocyanate used was a mixture of an HDI polyisocyanate with an isocyanurate structure, NCO content 21.8 %, viscosity 3000 mPas, (Desmodur® N3300, Bayer AG, Leverkusen) and of a polyisocyanate with an isocyanurat structure based on Desmodur W (13,5% Desmodur® N3300, degree of trimerisation 20 %, NCO content 14.5 %, 65 % solids (dissolved in xylene/methoxypropyl acetate). 20 The cyclopentanone-2-carboxyethyl ester blocking agent used was acquired from the Fluka company. Blocked polyisocyanates used as comparisons: BL 3175 (Bayer AG); crosslinking urethane stoving resin based on hexamethylene diisocyanate, 75 % solution in solvent naphtha 100, viscosity about 3300 mPas, NCO content (blocked) about 11.1 %, butanonoxime blocking agent. BL 3370 (Bayer AG); aliphatic, crosslinking urethane stoving resin, an approximately 70 % solution in l-methoxypropylacetat-2 (MPA), viscosity about 3500 1200 mPas, NCO content 30 (blocked) about 8.9 %, diisopropylamine blocking agent. Polyols used: see the following Table. WO 03/004545 PCT/EP02/07325 - 16- Production of polyurethane lacquers according to the invention The production of lacquers according to the invention is described by the directions for producing the blocked isocyanate components. WO 03/004545 PCT/EP02/07325 - 17- Table: Polyols suitable for the coil coating process Trade name / Trade Mark Type Form in which supplied Viscosity [mPa.s] Acid number OH content [%] Equivalent weight Alkynol 1665 SN/IB Oil-free, branched, saturated polyester 65% SN100/EB 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 about 0.6 2830 Desmopben 651 MPA Branched polyester 67% MPA 14500 ±3500 <3.0 5.5 ±0.4 309 Desmophen 670 Slightly 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 Desmophen 1200 Slightly branched polyester solvent-free 300 ±100 L (70% in 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 at 75°C <0.1 1.7 ±0.2 1000 WO 03/004545 PCT/EP02/07325 -18- 1C PUR Coil coating covering lacquer, white, Alkynol® 1665 polyol component A = polyisocyanate A, B = polyisocyanate B, C = polyisocyanate C 1 2 3 4 5 Bead mill formulation (fineness of grain < 5 jLim) BL 3175 BL 3370 A B C Alkynol 1665, 65% 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 components Alkynol 1665, 65 % with respect to form as supplied 21.5 20.0 19.3 19.1 19.2 Desmodur BL 3175, 75% in solvent naphtha 100 11.9 Desmodur BL 3370, 70% in 1-methoxypropyl acetate-2 14.1 A, 70 % in xylene / MPA (17 : 8) 14.8 B, 70% in xylene 15.0 C, 70 % in xylene 14.9 Zinc 2-ethylhexanoate, 10 % in SN 200S 0.7 0.7 0.7 DBTL, 10 % in SN 200 S (3) 0.7 0.7 Acronal 4 F ,50% in SN 200S (4) 1.5 1.5 1.5 1.5 1.5 CAB 531-1,10% in SN 200 S / butyl diglycol (2:1) (5) 7.3 7.3 7.3 7.3 7.3 SN200S 10.3 9.6 9.6 9.6 9.6 100.0 100.0 100.0 100.0 100.0 Comparison examples According to the invention WO 03/004545 PCT/EP02/07325 -19- Characteristic data binder vehicle 29.3 pigment 29.3 additives 1.5 solvent 39.3 100.00 OH/NCO ratio 1 : 1 binder vehicle/pigment ratio 1 : 1 solids content (% bv weight) about 60 thinner Solvesso 200 S application viscosity. DIN EN 150 2431 with 5mm nozzle /23 °C about 100 s Stoving conditions PMT: see test results % by weight additives (active amount of catalyst added 0.2 substance calculated with respect to binder vehicle solids content) Acronal® 4F 2.6 cellulose acetobutvrate 2.5 Remarks (4+5) The combination of CAB and Acronal® 4 F ensures aeration and flow. WO 03/004545 PCT/EP02/07325 -20- Suppliers (1) Kronos International INC, Leverkusen (2) Deutsche Exxon, Cologne (3) Brenntag, Miilheim / Ruhr (4) BASF AG, Ludwigshafen (5) Krahn Chemie, Hamburg Raw materials used Alkynol® 1665, an oil-free saturated polyester based on isophthalic acid/adipic acid/NPG/propyl glycol, Bayer AG, Leverkusen, OH content: 1.7 % based on the 65 % form supplied in solvent naphtha 100/isobutanol (31.5 : 3.5) CAB (cellulose acetobutyrate) - supplier: Krahn Chemie Hamburg, manufacturer: Eastman Kingsport USA; CAB 531-1 (butyryl content about 53%; the hydroxyl content of 1.7% is not included in the calculation) Acronal® 4 F - manufacturer: BASF Ludwigshafen, a polymer based on butyl acrylal (flow enhancer and anti-foaming agent) Solvesso® 200 S - manufacturer: Esso/Exxon; aromatics content of solvent 99%, evaporation rate (ether=l) ~ 1000 Determination of the white index ASTM E 313, White index Berger brightness (no DIN) Brightness = Ry +3 (Rz-Rx) The DIN 6167 Yellow Index G is calculated from the following formula: WO 03/004545 PCT/EP02/07325 -21 - G = a.x—b.z .100 y where X, Y and Z are the CIE coordinates according to DIN 5033 a = red/green axis* b = blue/yellow axis** * positive values => redder negative => greener ** positive values => yellower negative => bluer Determination of the resistance to MEK Description of the method (according to ECCA -T11 and DIN EN ISO 28 12-1 and DEN EN 12720): The MEK wipe test is a rapid test for checking the final curing of the lacquer coat. For this purpose, a cotton swab saturated with MEK is moved to and fro at a constant pressure over the lacquer coat. Apparatus and accessories: balance (made by Bizerba), 100 g, 1 kg and 2 kg weights. Experimental: For coating thicknesses up to 20 jam, a counter-pressure of 1 kg was used, and above 20 ^m a counter-pressure of 2 kg was used. The test panel was secured to the weighing pan of the balance by means of film clips and anti-slip film. The balance was adjusted by means of the 100 g weight and the tare setting. A swab saturated with MEK was moved to and fro over the lacquer coat, against the selected test pressure, until the lacquer coat was destroyed. WO 03/004545 -22- PCT/EP02/07325 Assessment: The number of double strokes performed until the coating was destroyed is given in the test report, with a maximum of 100 double strokes being reported. After 100 double strokes, the lacquer coat was optionally assessed for changes (becoming matt, softening). Performing a T-bend test According to ECCA T 7. (ECCA: European coil coating Association) Description of the method: Purpose: This procedure determines the resistance of an organic coating to crack formation when bent by 180°. Principle: In this test, the sample was bent for 1 - 2 seconds by 180° parallel to the direction of rolling, with the coating being situated on the outer face. There had to be close contact between the panels to ensure uniform bending. The smallest bending radius which enabled the sample to be bent without crack formation determined the resistance to a 180° bend. The adhesion was checked by means of adhesive tape after each bend. Apparatus: The apparatus with which this method was carried out consisted of a vice with protective jaws. Preparation: The samples were stored for at least 24 hours at laboratory temperature and relative humidity. The measurements were made under the same conditions. WO 03/004545 PCT/EP02/07325 - 23 - If more precise conditions are specified, or in cases of arbitration, the specifications according to ISO 3270-1984 have to be complied with, namely a temperature of 23 ± 2 °C and a relative humidity of 50±5 %. Procedure: A sheet metal strip about 2 cm wide was cut off opposite to the direction of rolling, and was bent by 180° for 1-2 seconds parallel to the direction of rolling, with the coating situated on the outer face. Thereafter, the metal sheet was tightly compressed in the vice. The bending edge was tested for cracks using a 20 x magnifying glass. Thereafter, the adhesion was checked pressing on and pulling off an adhesive tape three times. The T-bending results were ranked by with R for cracks and H for adhesion, using an assessment from 1 to 5, where 0 was the best value and 5 was the worst value. The metal sheet was then bent about itself until a value of 0 was achieved for adhesion and crack formation. Testing was terminated at not more than 3 T-bends. Subsequent crack resistance The deformed T-bend strip was heated to 100°C for 30 minutes and thereafter was again assessed for cracks. Lacquer preparation: Testing was performed on a white coil coating covering lacquer of a standard formulation (standard formulation RR 6830). For this purpose, a ground material of the following pearl mill formulation was first prepared using the oil-free, saturated polyester: 9.8 parts Alkynol® 1665 oil-free polyester, in the 65% form as supplied. WO 03/004545 PCT/EP02/07325 -24- 7.8 parts Solvesso® 200 S solvent 22.3 parts Kronos 2330 white pigment. The ground material was dispersed with 2 mm silica quartz beads. Dispersion was effected for 1 hour in a Skandex® mixer. (Remarks: the same formulation can be processed in a bead mill or in a Skandex® mixer (shaking device. The Skandex® mixer has the advantage that several samples are dispersed simultaneously, and are triturated in a closed vessel. The beads are subsequently removed by sieving the outlet.) The ground material was separated from the glass beads by sieving. The remaining lacquer components were added with stirring. 21.5 parts Alkynol® 1665 oil-free polyester, in the 65% form as supplied, 11.9 parts of blocked polyisocyanate 0.7 parts DBTL, 10 % solution in Solvesso® 200 S. 7.3 parts CAB 531-lcellulose acetobutyrate, 10 % solution in Solvesso® 200 S / butyl diglycol (2:1) 1.5 parts Acrynol® 4 F, 50 % solution in Solvesso® 200 S X parts Solvesso® 200 S (10.3 parts were used with BL 3175 as the blocked polyisocyanate). The amount of blocked PIC added varied depending on the equivalent weight of the PIC (in this case Desmodur® BL 3175 was used as the comparison. The polyol and blocked polyisocyanate were combined equivalently, i.e. if fewer blocked NCO groups were available, the proportion of blocked PIC had to be increased. The equivalent weights are given in the instructions. WO 03/004545 PCT/EP02/07325 -25- The lacquer was adjusted to its processing viscosity of about 70 sec DIN 4/23° C with Solvesso® 200 S. The lacquer was applied to chromated aluminium sheets (1 mm thick) using a doctor blade. Immediately after application of the lacquer, the sheets were stoved on the turntable in an Aalborg oven. PMT 210°C 30 sec at 350° C oven temperature PMT 216°C 33 sec at 350° c oven temperature PMT 224°C 35 sec at 350° c oven temperature PMT 232°C 38 sec at 350° c oven temperature PMT >254°C 50 sec at 350° c oven temperature The dry coat thickness was 20-22 jim. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> WO 03/004545 Coil coating lacquers binder vehicle: Alkynol 1665 binder vehicle ratio: equivalent pigment: Kronos 2330 titanium dioxide binder vehicle : pigment ratio: 1:1 PCT/EP02/07325 •26- catalyst: 0.2% (with respect to binder vehicle solids) stoving conditions: 232°C(PMT) Hantel: 42 substrate: AI sheet pretreated with Bonder 722 Blocked polyisocyanate tested BL 3175 Example A Example B Example C BL 3370 Coat thickness [nm] ECCA-Ti(*l) 20-22 20-22 20-22 20-22 20-22 Brightness Wb=Ry+3(Rz-Rx) (Berger) 92.3 91.6 92.2 91.4 91.6 Yellow index -3.1 -2.4 -2.6 -2.5 -2.8 60° Gardner gloss ECCA-T2 (l*) 76 67 68 65 69 MEK wipe test(PMT196°C)/brightness - - - - 95X /92.4 MEK wipe test(PMT 199°C)/brightness 10X/94.1 100X/94.6 65X/94.0 100M /93.9 100X/92.4 MEK wipe test(PMT204°C)/brightness 95X/93.6 100X/94.6 100M/94.3 100X/94.4 100X/92.5 MEK wipe test(PMT210°)/brightness 100X/93.6 100X/94.2 100X/94.01 100X/94.1 100X/92.4 MEK wipe test(PMT216°C)/brightness 100X / 93.3 100X/93.8 100X/94.0 100X / 94.2 100X/92.0 MEK wipe test(PMT224°C)/brightness 100X/93.1 100X/93.0 100X/92.9 100X/93.2 100X /91.8 MEK wipe test(PMT232°C) 100X 100X 100X 100X 100X Microhardness HU corr. (N/mm2) (|) from 3 measurements 128.7 55.1 99.8 86.0 140.7 Impact test [inch/lbs] ECCA-T5 (*l) 80 80 80 80 80 Adhesion 6mm cupping index in ECCA-T6 cross-cut adhesion test (*1) 0 0-1 0 0 0 T-bend test TO.O R5H1 R5H1 R5H1 R5H1 R5H1 R=cracks T0.5 R1H0 R1H0 R2H0 R2H0 R1H0 H=adhesion Tl.O R0 R0 R0 R0 R0 0=best value T1.5 5=worst value T2.0 Subsequent crack resistance after 30 min at 100°C T1.5+ T1.0- T1.5+ T1.0- T1.5+ T1.0+ T1.5+ T1.0+ T1.5+ Tl.O (*1): following Gardner gloss test, since not measured in air-conditioned room - = subsequent cracking; + = no subsequent cracking WO 03/004545 Claims -27- PCT/EP02/07325

1. Organic polyisocyanates comprising at least two isocyanate groups, the isocyanate groups of which are blocked with acidic CH cyclic ketones of general formula (I), wherein X is an electron-attracting group, R1 and R2, independently of each other, represent the radicals H, a C1-C20 (cyclo)alkyl, a C6-C24 aryl, a C1-C20 (cyclo)alkyl ester or amide, a C6-C24 aryl ester or amide, or mixed aliphatic/aromatic radicals comprising 1 to 24 carbon atoms, which can also form part of a 4 to 8-membered ring, n is an integer from 0 to 5, and which have a content of blocked isocyanate groups (calculated as NCO) of 0.1 to 20 % by weight in total.

2. Organic polyisocyanates according to claim 1, characterised in that the electron-attracting group X is selected from the group comprising ester, amide, sulphoxide, sulphone, nitro, phosphonate, nitrile, isonitrile, a polyhalogeno group, fluorine, chlorine or carbonyl groups. 3. Organic polyisocyanates according to claim 1, characterised in that the acidic CH cyclic ketones of general formula (I) are cyclopentanone-2-carboxymethyl ester and -carboxyethyl ester, cyclopentanone-2-carboxylic acid nitriles, REPLACEMENT PAGE (RULE 26) WO 03/004545 PCT/EP02/07325 -28- cyclohexanone-2-carboxymethyl ester and -carboxyethyl ester, or cyclopentanone-2-carbonylmethyl. 4. Organic polyisocyanates according to claim 1, characterised in that the acidic CH cyclic ketones of general formula (I) are cyclopentanone-2-carboxymethyl ester and carboxyethyl ester, or cyclohexanone-2-carboxy-methyl ester and -carboxyethyl ester. 5. A method of producing organic polyisocyanates according to claim 1, characterised in that polyisocyanates are reacted with acidic CH cyclic ketones of general formula (I), A? ,,k R2 R is an electron-attracting group, wherein X R1 and R2, independently of each other, represent the radicals H, a C1-C20 (cyclo)alkyl, a C6-C24 aryl, a C1-C20 (cyclo)alkyl ester or amide, a C6-C24 aryl ester or amide, or mixed aliphatic/aromatic radicals comprising 1 to 24 carbon atoms, which can also form part of a 4 to 8-membered ring, and n is an integer from 0 to 5, in the presence of a catalyst, wherein 0.8 to 1.2 mol of the cyclic ketone of formula (I) are used per isocyanate group equivalent of the polyisocyanate to be blocked. REPLACEMENT PAGE (RULE 26) WO

03/004545 PCT/EP02/07325 -29- 6. A method according to claim 5, characterised in that the organic polyisocyanate contains a uretdione, isocyanurate, iminooxadiazinedione, acylurea, biuret or allophanate structure. 5 7. A method according to claim 5, characterised in that alkali metal and alkaline earth metal bases, zinc salts or other Lewis acids are used as catalysts. 8. PUR lacquers containing organic polyisocyanates according to claim 1. 10 9. PUR lacquers according to claim 8, characterised in that they are 1C PUR lacquers. 10. Use of the organic polyisocyanates according to claim 1 in primer surfacers. 15 11. Use of the organic polyisocyanates according to claim 1 in the coating of coils. 12. Coatings or PUR lacquers containing blocked organic polyisocyanates according to claim 1. REPLACEMENT PAGE (RULE 26) 30 13. An organic polyisocyanate according to claim 1 substantially as herein described or exemplified. 14. A method according to claim 5 substantially as herein described or exemplified. 15. A PUR lacquer according to claim 8 substantially as herein described or exemplified. 16. A use according to claim 10 substantially as herein described or exemplified. 17. A use according to claim 11 substantially as herein described or exemplified. 18. A coating or PUR lacquer according to claim 12 substantially as herein described or exemplified. </div>