Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes

Definitions

• the present invention relates to coating compositions containing B-[3-(2H-benzotriazol- 2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid-poly(ethylene glycol) ester as an UV- absorber, and to a process for producing a coating system, particularly an automotive coating system comprising application of the coating composition as at least one layer of the coating system.
• UV-absorbers are well known in the state of the art for use in coatings, in particular in automotive coating systems.
• the UV-protection is achieved not only by the use of UV- absorbers, but normally by a mixture of various stabilizers, such as anti-oxidizing agents, hindered amine light stabilizers, phosphites, phosphonites, etc.
• a detailed description of all the other components which are useful in combination with UV-absorbers in automotive coatings is available, e.g. in EP 0669330A1, especially page 8 or in WO 2006082145A1, especially pages 26 to 43. Since there is quite some effort to reduce organic volatile components in automotive coatings, one of the key requirements for UV-absorbers in automotive coatings is their compatibility with water-borne coating formulations, which are more and more used in the automotive industry.
• UV-absorbers abbreviated as UVAs
• UVAs UV-absorbers
• UVAs UV-absorbers
• benzotriazoles are very effective as described by Andreas Valet, "Lichtschutzstoff fiir Lacke. Die Technologie des Be Anlagenens, Vincentz, 1996". Since these UVAs have a very unique structure and hydrophobic properties, the challenge is to render these basically very hydrophobic molecules much more hydrophilic to make them more compatible with water-borne coatings. It is also well known that the UVA-based light stabilizers can have quite some interactions - even if they are used in original equipment manufacture clear coat (abbreviated as OEM CC) - with pigments coming from the base coats, as described by G. Haacke, E. Longordo, F.
• OEM CC original equipment manufacture clear coat
• UVAs such as hydroxyphenyl-s-triazines, oxalanilides, hydroxyphenylpyrimidines or hydroxybenzophenones.
• benzotriazoles show a much more suitable absorption spectrum to enhance durability, as described by A. Valet "Lichtstoffstoffstoff fur Lacke", pp. 23, benzotriazoles are much more preferred for the application in automotive OEM coatings.
• the interaction and migration occur due to the hydrophobic property profile of the UV- absorbers. Based on that, an improved compatibility is most likely obtained by UVAs which do exhibit amphiphilic properties.
• modifications have been developed, for example, modification of benzotriazoles with aromatic substituents, substituents based on sulfonic acid or modification based on polyethylene oxide substituents.
• UV-absorbers examples include, but not limited to,
• UV-absorbers are very hydrophobic, which are rather incompatible with water borne coating formulations due to that hydrophobic property.
• the overall target of the automotive industry is to reduce cost and to provide excellent coating properties even within much lower film builds (film thickness).
• one challenge is to identify suitable UV-absorbers, which can be embedded into the multi-layer coating systems in a way that the coating provides excellent appearance already at very low film builds, which is most critical for the automotive Base Coat - Clear Coat wet in wet applications.
• the application of OEM CC at low film builds can be very critical and in general it can be said that the overall appearance of an automotive coating system very strongly depends on the overall film build.
• one another option to improve the overall appearance of the coating system is to embed the UVAs in the water borne base coat (abbreviated hereinafter as WBBC) and not anymore in the OEM CC. This could be one advantage, presuming that with this step the overall appearance of the total coating system can be improved.
• WBBC water borne base coat
• UV-absorber and a coating composition in particular an automotive coating composition, containing an UV- absorber, which UV-absorber exhibits improved compatibility with water borne automotive coatings, in particular base coats and does not possess the disadvantages of the known UV- absorbers.
• the UV-absorbers should be soluble within automotive clear coats at least to the extend they migrate into them as well as within automotive base coats, in particular water borne automotive base coats.
• the object of the present invention can be achieved by use of a mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]-propionic acid ⁇ -PEG X ester in automotive coating systems as an UV-absorber with reduced amount of residual free PEG X, in which X is a number in the range of more than 100 and less than 1000.
• the present invention provides a composition, especially an automotive coating composition, which contains as an UVA mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl- 4-hydroxyphenyl]propionic acid ⁇ -PEG X ester, wherein the automotive coating composition contains less than 10 wt. % of residual free PEG X, based on overall weight of all UVAs present in the automotive coating composition, in which X is a number in the range of more than 100 and less than 1000.
• the present invention relates to the following aspects:
• a coating composition preferably an automotive coating composition, containing a mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester as an UV-absorber, characterized in that
• the coating composition contains less than 10 % by weight of free PEG X, based on the overall weight of all UVAs in the coating composition,
• the free PEG X refers to unesterified poly(ethylene glycol) with a weight average molecular weight of X in g/mol and wherein X is a number in the range of from 100 ⁇ X ⁇ 1000, which comes from preparation of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t- butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester with the PEG X as a starting material and remains as an impurity of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxy- phenyljpropionic acid ⁇ -PEG X ester.
• a multilayer coating system which comprises a pigmented and/or effect coating layer and a clearcoat layer, wherein the pigmented and/or effect coating layer and/or the clearcoat layer, preferably the pigmented coating layer contains the UV absorber as defined in any of above 1) to 8).
• a process for producing a coating system comprising application of the coating composition according to any of above 1) to 11) as at least one layer of the coating system, preferably the automotive coating system.
• Figure 1 is a graph showing UV absorption spectra of one of the UV-absorbers of the present invention, i.e. mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyljpropionic acid ⁇ -PEG 300 ester in a concentration of 92 wt% and with a content of free PEG X of 0.3 weight % (Sample 2)), and of Tinuvin 1130 and Eversorb 80 as comparative UV-absorbers, in which the abscissa represents the wave length and the ordinate represents the absorbance.
• the abscissa represents the wave length and the ordinate represents the absorbance.
• the three absorption curves from top to bottom represent the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG 300 ester (curve 1), Tinuvin 1130 (curve 2) and Eversorb 80 (curve 3), respectively.
• Figure 2 is a graph showing the purities of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t- butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG 300 ester of the present invention (one UV- absorber of the present invention), Tinuvin 1130 and Eversorb 80, as measured by HPLC.
• Monoester represent the component mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyljpropionic acid ⁇ -PEG 300 ester present in each sample
• Diester represents the component bis ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxy- phenyljpropionic acid ⁇ -PEG 300 ester in each sample. All ratios indicated above the peaks represent Eversorb 80 : the UV-absorber of the present invention: Tinuvin 1130.
• Figure 3 is a bar graph showing the results of LW-Wavescan at different CC film builds for each sample prepared in the Formulation Examples.
• the bars arranged from left to right represents Reference 1, Reference 2, Reference 3, Formulation 1 , Formulation 2 and Formulation 3 respectively.
• Figure 4 is a bar graph showing the results of SW-Wavescan at different CC film builds for each sample prepared in the Formulation Examples.
• the bars arranged from left to right represents the Reference 1, Reference 2, Reference 3, Formulation 1 , Formulation 2 and Formulation 3 respectively.
• the present invention relates to a coating composition containing mono ⁇ B-[3-(2H- benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester as an UV- absorber, characterized in that
• the coating composition contains less than 10 % by weight of free PEG X, based on the overall weight of all UVAs present in the automotive coating composition,
• the free PEG X refers to unesterified poly(ethylene glycol) with a weight average molecular weight of X in g/mol and wherein X is a number in the range of from 100 ⁇ X ⁇ 1000, which comes from preparation of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t- butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester with the PEG X as a starting material and remains as an impurity of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxy- phenyljpropionic acid ⁇ -PEG X ester.
• the coating composition of the present invention contains less than 8 % by weight of the free PEG X based on the overall weight of UVAs in the automotive coating composition, more preferably less than 5 % by weight, still preferably less than 4% by weight, and even preferably less than 1% by weight, for example 0.3% by weight.
• the coating composition of the present invention contains less than 10 % by weight of bis ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyljpropionic acid ⁇ -PEG X ester, based on the overall weight of all UVAs in the coating composition.
• the compatibility of the mono ⁇ B-[3-(2H-benzotriazol-2- yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester is above 10.4, preferably above 13.5, and more preferably below 15, measured as solubility parameter.
• the coating composition of the present invention is preferably an automotive coating composition.
• PEG-X occurs in the terms mono ⁇ B-[3-(2H-benzotriazol- 2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester and bis ⁇ B-[3-(2H-benzotriazol- 2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester represents the moieties derived from the free PEG-X as defined hereinabove during the ester formation.
• the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyljpropionic acid ⁇ -PEG X ester means the materials have the same structures as the monoesters obtained from the esterification of B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydro xyphenyljpropionic acid with free PEG X.
• the mono ⁇ B-[3-(2H-benzotriazol- 2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters according to the present invention are not limited to those derived from esterification reaction.
• the bis ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester optionally present in the coating composition of the present invention represents a byproduct during the preparation of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyl] propionic acid ⁇ -PEG X ester.
• the compounds that are used as the UV-absorber of the present invention per se are known in the state of the art, i.e. mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxy- phenyljpropionic acid ⁇ -PEG X ester in which X is in the range of from 100 ⁇ X ⁇ 1000, which may be represented by the following formula:
• m is an average number of the oxyethylene repeating unit derived from the PEG X in which X is in the range of from 100 ⁇ X ⁇ 1000.
• mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]pro- pionic acid ⁇ -PEG X esters are used as a mixture with bis ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t- butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters and free PEG X, which mixture is obtained from the preparation reaction to obtain the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t- butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters.
• the mixture under Tinuvin 1130 and Eversorb 80 may be mentioned, in which the contents of free PEG X and bis ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters are relatively high.
• the use of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyljpropionic acid ⁇ -PEG X esters in which X is in the range of from 100 ⁇ X ⁇ 1000 without byproducts or at least with reduced amounts of byproducts, as an UV-absorber in automotive coating composition are not known in the state of the art.
• the UV-absorber of the present invention is mono ⁇ B- [3- (2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters in which X is in the range of from 200 to 600 or less, more preferably 200 to 400.
• the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters of the present invention may be obtained by separation from the commercially available mixtures containing the reaction product of B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyl] propionic acid with PEG X wherein X is a number in the range of from 100 ⁇ X ⁇ 1000, preferably 200 ⁇ X ⁇ 600, most preferably 200 ⁇ X ⁇ 400, such as Tinuvin 1130 (available from BASF SE) or Eversorb 80 (available from Everlight) or any other products which may be available by suppliers not mentioned here.
• Tinuvin 1130 available from BASF SE
• Eversorb 80 available from Everlight
• the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propio- nic acid ⁇ -PEG X esters of the present invention may be prepared according to the methods known in the state of the art, for example in WO 02/24668 Al wherein the preparation of mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG PEG 300 ester are described, or in US 7915322 B2.
• mono methyl ester of B-[3-(2H-benzotriazol-2-yl)-5-t-butyl- 4-hydroxyphenyl]propionic acid first and then transfer it into the PEG X monoester (such as PEG 200 monoester, PEG 300 monoester, PEG 600 monoester or similar, etc.) by conventional transesterification procedures.
• the mono methyl ester of B-[3-(2H-benzotriazol- 2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid may be synthesized by the procedures as described in WO 02/24668A1, especially Example 19 or by enzymatic synthesis methods as described by M. Schroeder, L. Pereira, S. Rodriguez Couto, A. Erlacher, K.-U. Schoening, A. Cavaco-Paulo, G. M. Guebitz, Enzyme and Microbial Technology 40 (2007), 1748-1752.
• the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X (e.g. PEG 200) esters of the present invention may also be prepared as described in US 7915322 B2, especially Example 5, except that no step of adding methacrylic acid is carried out.
• any purification processes known in the state of the art for example column chromatography, may be used in order to reduce the content of impurities, especially of the free PEG X, to obtain the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyljpropionic acid ⁇ -PEG X esters with reduced amounts of impurities as used in the present invention, i.e. the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]- propionic acid ⁇ -PEG X ester with less than 10 % by weight of the free PEG X impurity.
• the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester is prepared as described in WO 02/24668A1, and then separated by column chromatography as described in Example 5 of US 7915322 B2.
• the purification process of column chromatography might be repeated once or two time to reduce the amount of residual free PEG X even below 1 wt. %.
• the resulting mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X esters of the present invention may be characterized with HPLC or UV- spectroscopy. Both methods can indicate the purity and also the effective UV-absorption of the purified material.
• hydrophilicity of the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4- hydroxyphenyl] -propionic acid ⁇ -PEG X (e.g. PEG 200) ester UV-absorbers may be measured easily in the laboratory by applying the so called solubility parameter. The exact procedure to measure this parameter is described in K. W. Suh, J. M. Corbett, Journal of Applied Polymer Science, Vol. 12, pp 2359-2370 (1968). Additionally, a more detailed description of the calculation as well as the sample volumes for the titrations is described in WO 2008/148555 Al
• the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X (e.g. PEG 200) ester UV-absorbers used in the automotive coating composition of the present invention exhibits a solubility parameter of more than 10.4 and below 15, more preferably more than 13.5.
• the most preferable range of the solubility parameter is in the range between 13.5 and 15.
• solubility parameter corresponds to a more hydrophilic property profile of the molecules, while a lower numerical value means a rather hydrophobic profile. Consequently, one option to increase the solubility parameters is to introduce hydrophilic substituents into the molecule.
• the standard benzotriazole UVAs are rather hydrophobic which is represented by a solubility parameter of 9.41 for a standard grade.
• the automotive coating composition of the present invention may contain one or more other UV-absorber(s) commonly used in an automotive coating composition in the state of the art. However, preferably there is no other organic UV-absorbers than the mono ⁇ B-[3-(2H-benzotriazo 1-2- yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X as described above present in the automotive coating composition of the present invention.
• the number of different UVAs in a coating system also the danger that some of the materials are not compatible with each other is reduced. Incompatibilities of different UVAs are likely to result in poor appearance of the final cured coating film.
• the UV-absorbers capable to be modified with a PEG X polymeric chain are not limited to the benzotriazole types as described above.
• the following types can be modified with a PEG X polymeric chain to render them hydrophilic:
• Benzophenone(s) and in particular their derivates such as Hydroxybenzophenones, e.g., 2,4-dihydroxybenzophenone:
• Oxalanilides and their derivatives such as mentioned in EP 0727318 Al, a non- limiting example is:
• R J m and R 2 n are defined as in EP 0727318 Al (see lines 47, page 2 to line 8, page 3, especially, the Table in page 3 ), provided that at least one of R 1 and R 2 is hydroxy 1 group.
• esterification of phenolic hydroxyl is known in the state of the art and can be done for the above Benzophenones, Oxalanilides and Triazines. According to the acidity of the phenolic hydroxyl, suitable catalysts may be employed. For the specially modified Benzotriazoles, the same approach as described herein is applicable.
• Such modified UV-absorbers with PEG X may be used instead of or in addition to the mono ⁇ B-[3-(2H-benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester UV-absorbers of the present invention in the automotive coating composition.
• the composition of the present invention preferably the automotive coating composition comprises other components conventionally used in such compositions.
• Deionized water at content from 40 - 90 wt. % depending on the particular materials may be contained in the water borne basecoat formulations.
• binders are used in the formulations.
• the binders contain functional groups which render them dispersible in water and/or soluble in water. These are alternatively
• nonionic hydrophilic groups especially poly(alkylene ether) groups.
• Suitable functional groups which can be converted into cations by neutralizing agents and/or quaternizing agents are primary, secondary or tertiary amino groups, secondary sulfide groups or tertiary phosphine groups, especially tertiary amino groups or secondary sulfide groups.
• Suitable cationic groups are primary, secondary, tertiary or quaternary ammonium groups, tertiary sulfonium groups or quaternary phosphonium groups, preferably quaternary ammonium groups or tertiary sulfonium groups, but especially tertiary sulfonium groups.
• Suitable functional groups which can be converted into anions by neutralizing agents are carboxylic, sulfonic or phosphonic acid groups, especially carboxylic acid groups.
• Suitable anionic groups are carboxylate, sulfonate or phosphonate groups, especially carboxylate groups.
• Suitable neutralizing agents for functional groups convertible into cations are inorganic and organic acids such as sulfuric acid, hydrochloric acid, phosphoric acid, formic acid, acetic acid, lactic acid, dimethylolpropionic acid or citric acid.
• neutralizing agents for functional groups convertible into anions are ammonia, amines such as trimethylamine, triethylamine, tributylamine, or amino alcohols, dibutylamine, dimethylaniline, diethylaniline, triphenylamine, dimethylethanolamine, diethylethano lamine, methyldiethanolamine, 2-aminomethylpropano 1, dimethylisopropylamine, dimethylisopropanolamine or triethano lamine, for example.
• Preferred neutralizing agents used are dimethylethanolamine, dibutylamine and/or triethylamine.
• the complementary reactive functional groups described above may be incorporated into the binders by the customary and known methods of polymer chemistry. This can be done, for example, by incorporating monomers which carry the corresponding reactive functional groups, and/or by means of polymer-analogous reactions.
• Suitable olefmically unsaturated monomers containing reactive functional groups by means of which these groups may be introduced into (meth)acrylate copolymers are monomers which carry per molecule at least one hydroxyl, amino, alkoxymethylamino, carbamate, allophanate or imino group, such as hydroxy alkyl esters of acrylic acid, methacrylic acid or another ⁇ , ⁇ -olefmically unsaturated carboxylic acid which are derived from an alkylene glycol which is esterified with the acid, or which are obtainable by reacting the ⁇ , ⁇ -olefmically unsaturated carboxylic acid with an alkylene oxide such as ethylene oxide or propyleneoxide, especially hydroxy alkyl esters of acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, fumaric acid or itaconic acid in which the hydroxy alkyl group contains up to 20 carbon atoms, such as 2-hydroxy ethyl, 2-hydroxyprop
• melamine resins are used to achieve crosslinling.
• Those resins are polycondensation resins formed from melamine ( 1,3,5 -triazine- 2,4,6-triamine) and a maximum of 6 mol of formaldehyde per mole of melamine.
• Some or all of the resulting methylol groups may be etherified with one or more different alcohols.
• melamine resins may have different degrees of methylolation and different degrees of etherification.
• the degree of methylolation of a melamine resin describes how many of the possible methylolation sites of the melamine have been methylolated, i.e., how many of the total of six hydrogen atoms of the primary amino groups of melamine (i.e., of l,3,5-triazine-2,4,6- triamine) have been replaced by a methylol group.
• a fully methylolated mononuclear melamine resin accordingly, has six methylol groups per triazine ring, such as hexamethylolmelamine, for example.
• the methylol groups may independently of one another also be in etherified form.
• basecoat materials contain preferably 0% to 20% by weight of melamine resin.
• Polyester Binders may be employed.
• polyester binders are meant polyester resins and polyester-polyurethanes.
• the basecoat materials contain 0% to 30 % by weight polyester binders (PE).
• Suitable polyester binders may be saturated or unsaturated, especially saturated.
• Unsaturated polyester binders are those which contain at least one polymerizable carbon-carbon double bond.
• Saturated polyester binders are those which contain no polymerizable carbon-carbon double bond.
• polyester resins can be prepared by esterifying organic dicarboxylic acids or their anhydrides with organic diols, or may derive from a hydroxycarboxylic acid or a lactone. With particular preference the polyester resins are prepared by esterifying organic dicarboxylic acids or their anhydrides with organic diols.
• the particularly preferred polyester resins therefore comprise structural units which originate from aliphatic, cycloaliphatic and/or aromatic dicarboxylic and/or polycarboxylic acids and from diols and/or polyols.
• the dicarboxylic and/or polycarboxylic acids and diols and/or polyols may be linear or branched aliphatic, cycloaliphatic or aromatic dicarboxylic and/or polycarboxylic acids or diols and/or polyols.
• diols suitable for preparing the polyester resins include alkylene glycols, such as ethylene glycol, propylene glycol, butylene glycol, butane- 1,4-diol, hexane-l,6-diol, neopentylglycol, and other diols, such as dimethylolcyclohexane. It is also possible, however, to add small amounts of polyols, such as trimethylolpropane, glycerol or pentaerythritol, for example.
• the acid component of the polyester is composed primarily of low molecular weight dicarboxylic acids or their anhydrides having 2 to 44, preferably 4 to 36, carbon atoms in the molecule.
• acids examples include o-phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, glutaric acid, hexachloroheptanedicarboxylic acid, tetrachlorophthalic acid and/or dimerized fatty acids.
• these acids it is also possible to use their anhydrides, where they exist.
• polyester polyols it is also possible to use relatively small amounts of carboxylic acids having 3 or more carboxyl groups, examples being trimellitic anhydride or the adduct of maleic anhydride with unsaturated fatty acids.
• Further binders that are used typically are, for example, random, alternating and/or block, linear and/or branched and/or comb (co)polymers of ethylenically unsaturated monomers, or polyaddition resins and/or polycondensation resins.
• Polyurethane dispersions are manufactured in addition reactions in process solvents.
• polyisocyanates especially diisocyanates are employed together with polyols, especially diols or triols based on polyether or polyester.
• the organic polyisocyanate can be an aliphatic polyisocyanate, including a cycloaliphatic polyisocyanate or an aromatic polyisocyanate.
• Useful aliphatic polyisocyanates include aliphatic diisocyanates such as ethylene diisocyanate, 1,2-diisocyanatopropane, 1,3- diisocyanatopropane, 1,6-diisocyanatohexane, tetramethylenediisocyanate, lysine diisocyanate, methylene bis(4-cyclohexylisocyanate), 4,4'-Dicyclohexylmethanediisocyanate and isophorone diisocyanate.
• Useful aromatic diisocyanates and araliphatic diisocyanates include the various isomers of toluene diisocyanate, meta-xylylene diioscyanate and para- xylylene diisocyanate, also 4-chloro-l,3-phenylene diisocyanate, 1, 5 -tetrahydro -naphthalene diisocyanate, 4,4'-dibenzyl diisocyanate and 1,2,4-benzene triisocyanate.
• the various isomers of alpha,alpha,alpha',alpha'-tetramethyl xylylene diisocyanate can be used.
• isocyanurates such as DESMODUR® 3300 from Bayer and biurets of isocyanates such as DESMODUR® N100 from Bayer.
• suitable polyols are diols and triols, especially diols. Normally, triols are used alongside the diols in minor amounts in order to introduce branches into the polyester polyols.
• Suitable diols are ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4-butanediol, 1,2-, 1,3-, 1,4- or 1,5-pentanediol, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexanediol, neopentyl glycol mono(hydroxypivalate), neopentyl glycol, diethylene glycol, 1,2-, 1,3- or 1,4- cyclohexanediol, 1 ,2-, 1,3- or 1,4-cyclohexanedimethanol, 2,2,4-trimethyl-l,3-pentanediol, 1- ethyl-2-butyl- 1,3-propanediol or the positional isomers of diethyloctanediols.
• basecoats contain 0 - 30 % by weight of the aforementioned further binders.
• the basecoat material comprises at least one pigment.
• Pigments are colorants in powder or platelet form which unlike dyes are insoluble in the surrounding medium (cf. Rompp Lacke und Druckmaschine, page 451, entry heading "Pigmente” [Pigments]).
• the pigment is selected from the group consisting of organic and inorganic, color-imparting, effect-imparting, color- and effect-imparting, magnetically shielding, electrically conductive, corrosion-inhibiting, fluorescent, and phosphorescent pigments.
• the basecoat material comprises at least one effect pigment, more particularly at least one metal flake pigment. Together with the effect pigment or pigments, the basecoat may further comprise at least one, or two or more, color pigments.
• suitable effect pigments which may also impart color
• metal flake pigments such as commercial aluminum bronzes and commercial stainless steel bronzes
• nonmetallic effect pigments such as, for example, pearlescent pigments and interference pigments, platelet-shaped effect pigments based on iron oxide, or liquid-crystalline effect pigments.
• pearlescent pigments and interference pigments such as, for example, pearlescent pigments and interference pigments, platelet-shaped effect pigments based on iron oxide, or liquid-crystalline effect pigments.
• the metal flake pigment has a thickness in the range between 200 to 2000 nm and typically has an average particle size between 10 to 50 and more typically 13 to 25 um (ISO 13320-1 by Cilas (instrument 1064)).
• Suitable organic and/or inorganic color pigments are the pigments typically employed in the paint industry.
• suitable inorganic color pigments are white pigments such as titanium dioxide, zinc white, zinc sulfide or lithopones; black pigments such as carbon black, iron manganese black or spinel black; chromatic pigments such as chromium oxide, chromium oxide hydrate green, cobalt green or ultramarine green, cobalt blue, ultramarine blue or manganese blue, ultramarine violet or cobalt violet and manganese violet, red iron oxid, cadmium sulfoselenide, molybdate red or ultramarine red; brown iron oxide, mixed brown, spinel phases and corundum phases or chromium orange; or yellow iron oxide, nickel titanium yellow, chromium titanium yellow, cadmium sulfide, cadmium zinc sulfide, chromium yellow or bismuth vanadate.
• suitable organic color pigments are monoazo pigments, disazo pigments, anthraquinone pigments, benzimidazole pigments, quinacridone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, dioxazine pigments, indanthrone pigments, isoindoline pigments, isoindolinone pigments, azomethine pigments, thioindigo pigments, metal complex pigments, perinone pigments, perylene pigments, phthalocyanine pigments or aniline black.
• the amount of the pigments may vary very widely and is guided primarily by the depth of color and/or intensity of effect that are to be brought about, and also by the dispersibility of the pigments in basecoat materials.
• the pigment content is typically between 0.5 to 60% by weight.
• Solid-color basecoat materials are basecoat materials which contain no metallic or effect pigments.
• metallic coating materials based in each case on the total weight of the basecoat material, the pigment content is typically between 0.1% and 40% by weight.
• the basecoat material contains at least one organic solvent typically in an amount of from 1 % to 30 % by weight, based on the total weight of the basecoat composition.
• Suitable organic solvents are all solvents which are typically used in the paint industry, examples being alcohols, glycol ethers, esters, ether esters, and ketones, aliphatic and/or aromatic hydrocarbons, such as, for example, acetone, methyl isobutyl ketone, methyl ethyl ketone, butyl acetate, 3-butoxy-2-propanol, ethyl ethoxypropionate, butylglycol, butylglycol acetate, butanol, ethylhexanol, dipropylene glycol methyl ether, butyl glycolate, n- methylpyrrolidone, n-ethylpyrrolidone, dimethylsulfoxid, xylene, toluene, Shellsol T, Pine Oel 90/95, Solventnaphtha®, Shellsol® A, Solvesso, benzine 135/180, Isopar L, I
• the basecoat material may comprises catalyst(s).
• Suitable catalysts are the known catalysts which are typically used for crosslinking with melamine resins, such as, for example, sulfonic acid catalysts or phosphoric acid derivatives.
• the catalyst or catalysts are used in amounts of typically 0.5%> to 5% by weight, based on the total weight of the basecoat material.
• the basecoat material may comprise customary and known auxiliaries and additives in typical amounts, preferably 0%> to 40%> by weight, more typically 0.5%> to 30%> by weight, based in each case on the total weight of the basecoat material, of at least one auxiliary or additive.
• auxiliaries or additives are the known auxiliaries and additives that are typically used in the paint industry.
• suitable auxiliaries and additives are organic and inorganic fillers, such as talc, and/or dyes (organic substances that are black or chromatic and are soluble in the surrounding medium (cf.
• auxiliaries and additives such as, for example, antioxidants, deaerating agents, wetting agents, dispersants, emulsifiers, rheological assistants such as flow control agents, thickeners, antisag agents, and thixotropic agents, such as layered silicates, waxes, polyacrylate or polyurethane based thickeners and wax-like compounds, slip additives, reactive diluents, free-flow aids, siccatives, biocides, additives for improving the substrate wetting, additives for improving the surface smoothness, matting agents, free-radical scavengers, light stabilizers, corrosion inhibitors, flame retardants or polymerization inhibitors, as described in detail in the book "Lackadditive” [Additives for Coatings] by Johan Bieleman, Wiley- VCH, Weinheim, New York, 1998.
• auxiliaries and additives are rheological assistants, deaerating agents, wetting agents, dispersants, waxes and wax-like compounds, and free-radical scavengers.
• Particularly preferred auxiliaries and additives are wetting agents, and waxes and wax- like compounds.
• Suitable clear coat material for producing the clear coat of the multilayer coating of the invention may comprise the transparent coating compositions that are typically employed as solvent borne transparent coating compositions, which may be formulated either as one- component coating compositions or as two-component or multi-component coating compositions.
• the transparent coating compositions (clear coat materials) preferably have a solids fraction in the range between 40 % and 70 % by weight.
• the transparent coating compositions used may be curable thermally and/or by means of radiation, in particular by means of UV radiation.
• the transparent coating compositions typically comprise at least one binder with functional groups and also at least one crosslinker having a functionality which is complementary to the functional groups of the binder.
• complementary functionalities are in particular the following pairings (a/b) that are in each case complementary to one another: (carboxyl / epoxy), (amine or thiol or hydroxyl / blocked or free isocyanate or alkoxylated amino groups or transesterifiable groups), ((meth)acryloyl / CH-acidic or amine or hydroxyl or thiol), (carbamate / alkoxylated amino groups), and ((meth)acryloyl / (meth)acryloyl) and (hydroxyl / methoxysilane.
• clear coats based on a silane self-crosslinking mechanism as described in patent WO 2007033786 Al can be used.
• transparent coating compositions based on polyurethane resins and/or polyacrylate resins and/or polyester resins, preferably with hydroxyl, amino, carbamate, carboxyl, methoxysilane, (meth)acryloyl and/or thiol groups, in combination with the corresponding crosslinkers, more particularly in combination with isocyanates, amino resins, anhydrides, and the like.
• the transparent coating compositions may comprise customary auxiliaries and additives, such as, for example, catalysts for crosslinking, defoamers, adhesion promoters, additives for improving substrate wetting, additives for improving surface smoothness, matting agents, light stabilizers, corrosion inhibitors, biocides, flame retardants or polymerization inhibitors, as described in detail in the book "Lackadditive” by Johan Bieleman, Wiley- VCH, Weinheim, New York, 1998.
• auxiliaries and additives such as, for example, catalysts for crosslinking, defoamers, adhesion promoters, additives for improving substrate wetting, additives for improving surface smoothness, matting agents, light stabilizers, corrosion inhibitors, biocides, flame retardants or polymerization inhibitors, as described in detail in the book "Lackadditive” by Johan Bieleman, Wiley- VCH, Weinheim, New York, 1998.
• the present invention also relates to a process for producing a coating system, in particular an automotive coating system, comprising application of the coating composition of the present invention as at least one layer of a coating system, in particular an automotive coating system.
• the coating composition of the present invention is applied as an automotive OEM clear coat or an automotive OEM base coat or both.
• the automotive coating composition of the present invention is applied as the OEM base coat and the OEM clear coat does not contain any organic UVAs.
• the process for producing the automotive coating system may be carried out in accordance with any well-known process for producing an automotive coating system in the state of the art, provided that the automotive coating composition of the present invention is applied as at least one layer of the coating system.
• the process of the present invention is carried out by applying a basecoat material provided with color and/or effect pigments, especially an aqueous basecoat material, to the substrate surface, drying the applied basecoat film at a temperature between 15°C and 100°C, afterwards applying to the dried basecoat film a transparent coating material (clear coat) and subsequently baking the basecoat film and clear coat film together, preferably at a temperature between 70°C and 160°C.
• a basecoat material provided with color and/or effect pigments, especially an aqueous basecoat material
• primed or unprimed/pretreated (flamed) or non - pretreated plastics such as for example ABS, AMMA, ASA, CA, CAB, EP, UF, CF, UF, PPE, POM, PE, PA, HDPE, LDPE, UHMWPE, PET, PMMA, PP, PP-EPDM, PVC, SAN, SMC (abbreviations according to DIN 7728T1).
• spray application is the preferred application method.
• a detailed description of variants and different spray application techniques can be found in the literature, A. Goldschmidt, H.-J. Streitberger, "BASF Handbuch Lackiertechnik”, Vincentz, 2002, pp. 494 - 644.
• a very detailed description of the application processes can also be found in "Automotive Paints and Coatings", edited by Hans- Joachim Streitberger and Karl - Friedrich Dossel, Wiley - VCH, 2008, pp. 259 - 305.
• the automotive coatings might also be applied by alternative methods, such as dipping.
• the invention is directed to a process for producing a multilayer coating system comprising a pigmented and/or effect coating layer and a clear coat layer on a surface of primed or unprimed substrates, wherein the pigmented and/or effect coating layer and/or the clear coat layer, preferably the pigmented and/or effect coating layer contains the UV absorber of the present invention as defined hereinbefore.
• a multilayer coating system which is obtained according to this process is also a subject of the present invention.
• a silver shaded water borne base coat commercially available from BASF Shanghai Coatings, product code FW797055 CB GREYSTONE was used.
• FW797055 CB GREYSTONE does not contain any organic UVAs, such as benzotriazoles or similar derivatives.
• the formulations were applied by the pneumatic application known in the state of the art. This was carried out by employing metal test panels which had each been coated with a customary and known, cathodically deposited, thermally cured electrocoat, a customary and known, thermally cured solvent borne primer surfacer (product code FC60715A UNIB 5910 GREY, commercially available from BASF Shanghai Coatings, Guanghua Lu 521). After application of the base coat from above Formulation Examples, a flash off was applied for drying at 80°C for 10 minutes.
• the basecoat film and the clear coat (StarGloss, commercially available from BASF Shanghai Coatings, Guanghua Lu 521, product code FF71045A STARGLOSS 5910) film were cured jointly at 140°C for 24 minutes.
• the resulting basecoat had a film thickness of 12 ⁇ , while the clear coat was applied in a wedge to evaluate the wetting as well as the appearance at low film builds (20 ⁇ , 30 ⁇ ) as well as at standard film builds (40 ⁇ and 50 ⁇ ).
• the measurement of the appearance is carried out by employing a device from BYK, "Wavescan Dual" which is based on a laser measurement under an incident angle of 60°.
• the device is moved over the surface and the results are recorded depending on the size of the structures.
• the SW - values refer to structures in the range between 0.3 and 1.2 mm
• the LW values refer to structures in the range of from 1.2 to 12 mm.
• the chain length of the PEG moiety also has an effect on the appearance.
• an UVA which is as pure as possible having an moderate hydrophilicity is most favorable for the application, since it can balance an superior LW-appearance at low film build and a good-acceptable SW-appearance at higher film builds. It has surprisingly been found that such optimum balanced property profile is obtained by using the mono ⁇ B-[3-(2H- benzotriazol-2-yl)-5-t-butyl-4-hydroxyphenyl]propionic acid ⁇ -PEG X ester with reduced content of free PEG X as an UV-absorber wherein X being a number in the range of from more than 100 to less than 1000, especially form 200 and 600.
• PEG 300 may be omitted which might deteriorate the long term weathering and in particular humidity performance of the cured coating films, and also be rather harmful for the overall appearance of the automotive coating system.
• the bis-ester may also be omitted, which is rather likely to increase the incompatibility due to its high molecular weight, which is well known in the state of the art due to entropic effects.

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