MX2007013913A - A method of catalyzing a reaction to form a urethane coating and a complex for use in the method - Google Patents

Abstract

A urethane coating is formed by a reaction of a hydroxy-functional resin and a blocked isocyanate crosslinker. A method of catalyzing this reaction includes forming a polymeric ligand from the resin and/or the crosslinker. The method also includes incorporating a metal catalyst with the polymeric ligand to complex the metal catalyst with the polymeric ligand. The method further includes reacting resin and the crosslinker to form the urethane coating.

Description

A METHOD OF CATALYZING A REACTION TO FORM A URETAN COATING AND A COMPLEX FOR USE IN THE METHOD FIELD OF THE INVENTION The present invention generally relates to a method of catalyzing a reaction of a hydroxy-fional resin and a blocked isocyanate entrixer to form a urethane coating. More specifically, the present invention uses a complex, which is the reaction product of a polymeric ligand and a metal catalyst complexed with the polymeric ligand, to catalyze the reaction. The polymeric ligand is formed from the hydroxy-fional resin and / or the blocked isocyanate interleaver.

BACKGROUND OF THE INVENTION It is known that blocked isocyanate crosslinkers will be used as components in coating compositions, together with hydroxy-functional resins, to form urethane coatings on substrates. The urethane coating results once the coating composition is cured sufficiently. Illustrative urethane coatings include urethane powder coatings, automotive urethane base coatings, automotive urethane clear coatings, urethane electrorevestim ents, urethane primer coatings, continuous urethane pre-coatings and wire coatings and the like. It is also known that blocked isocyanate crosslinkers require curing at elevated temperatures (ie, greater than 160 ° C and even higher than approximately 177 ° C) since, at high temperatures, a blocking group associated with the interlacer unblocks, that is, it removes itself from the interlacer and the isocyanate functional groups (NCO) remain free. The free NCO functional groups are then capable of reaction with the hydroxy-functional groups of the resin to form an interlaced network like the urethane coating! Even at elevated temperatures, unlocking of the interlayer is slow and, without a catalyst, typically results in urethane coatings that respond to poor cure so that the resulting coating is "less baked" or "less cured". As such, metal catalysts have been employed and function, at elevated temperatures, to advance the unlocking of the interleaver and improve the cure response of the coating. The use of such catalysts also justifies variations in curing temperatures that often result in the lower baking condition whereby a target temperature for curing the urethane coating is not achieved. Metal catalysts typically include metal oxides, such as tin oxide, dibutyl tin oxide, and bismuth oxide, and organometallic salts, such as bisrrute carboxylate and dibutyl tin dilaurate. Either a metal oxide or an organometallic salt, these metal catalysts are added, in an unmodified form, directly into the composition forming the urethane coating. Examples of said conventional metal catalysts and said conventional additions of metal cata lycers are described in the patents of E.U.A. Nos. 5,554,700; 5,670,441; 5,908,912; 5,972,189; 6,174,422; 6,190,524; 6,265,079; 6,333,367; 6,353,057; 6,436,201; 6,617,030; and 6,624,215. There are several differences associated with this direct addition of the metal catalysts. It is difficult to directly add the metal oxides in the composition. Metal oxides often require mechanical processes, such as grinding, to effectively incorporate into the coating composition. As regards the organometallic salts, in many cases, portions of the organometallic salts are solubilized in the coating composition and, as a result, lead to certain physical defects, such as craters and / or poor film coalescence (realized as a crack type of poor flow not desirable), in the cured coating. Frequently, portions of the organometallic salts simply are not compatible with the curing composition. Also, these types of metal catalysts, such as the specialized metal carboxylates described in the U.S.A. No. 6,353,057, are based on fatty acid ligands formed of weight carboxylic acids low molecular Although the ligands of the? 57 patent are sufficient for complex formation with the metal, such as bismuth, it is known that they can have damaging effects at the end, i.e., cured coating. For example, if the particular carboxylic acid used in the '057 patent is of low molecular weight, eg, a n of Menois of about 200 Daltons, and is also at least partially soluble in water, then the carboxylic acid can cause contamination that It is made as craters in the cured coating. More specifically, in the electrocoating technique of a substrate, it is typical for an e-coating 'bath', containing the coating composition, to be filtered through an ultrafilter to provide an aqueous medium which is then used to rinse the substrate . When the bath is filtered through the ultrafilter, the ultrafiltrate, that is, the portion of the bath that passes through the filter, is the aqueous medium. It is contemplated that carboxylic acids of low molecular weight, such as those of the? 57 patent, pass through the ultrafilter and contaminate the aqueous medium. This is not desired because, in preparing a particular substrate, such as a body component of a vehicle, the substrate is sprayed with the aqueous medium to rinse the substrate. During spraying, low molecular weight carboxylic acids contaminating the aqueous medium can also be sprayed onto the substrate thus introducing a potentially crater material into the substrate.

On the other hand, if the particular carboxylic acid used in paterite? 57 is of high molecular weight, for example, an Mn of more than about 500 Daltons, then it can remain in the cured coating and cause problems during the formation of the cured coating. , that is, during film formation, and also cause problems associated with adhesion of the cured coating to metal. The low molecular weight specialized metal carboxylates of the '057 patent also tend to exhibit poor stability which comes from the addition of the metal carboxylates, such as a bismuth carboxylate, to an aqueous acidic medium. In this situation, the hydroxyl potential exists and this potential is not desirable. In this way, there remains a need to improve the catalysis of reactions that form urethane coatings.

BRIEF DESCRIPTION OF THE INVENTION A method of catalyzing a reaction forming a urethane coating is described. A complex for catalyzing a urethane coating composition is also described. In curing, the entrissement of the urethane coating composition forms the urethane coating. The reaction forming the urethane coating in the present invention is, more specifically, the reaction of a hydroxy-functional resin and a blocked isocyanate crosslinker.

The method includes the step of forming a polymeric ligand of the resin and / or the crosslinker. A metal catalyst is incorporated with the polymeric compound to complex the metal catalyst with the polymeric ligand. In this way, the complex is the reaction product of the polymeric ligand and the metal catalyst in complex with the polymeric ligand. The resin and the interlayer are to be reacted to form the urethane coating. As described above, the polymeric ligand commingling with the metal catalyst is derived from the resin and / or the interlayer which are both the 'structure' of the urethane coating. The resin and / or the interlayer are essentially being made a 'ligand' for the metal catalyst. The polymeric ligand of this invention replaces the simple low molecular weight carboxylic acids used in the prior art which are not effective. Since the polymeric ligand is formed by itself from the resin and / or the crosslinker, the polymeric ligand is integrated so that it is capable of covalently binding, that is, fix or link, itself to the resin and / or the interleaver. With this covalent binding, the polymeric ligand and therefore the metal catalyst in complex with the polymeric ligand are not extracted in the ultrafiltrate during the ultrafiltration process. As a result, the maximum compatibility of the complex in the urethane coating composition is achieved and the performance of the polymeric ligand in the urethane coating, i.e., the final cured film, is improved. With the polymeric ligand in the final urethane coating, the physical properties are improved. Also, as alluded to above, the metallic catalyst is easily and effectively incorporated into the urethane coating composition via the customary polymer ligand as compared to the direct addition of the unmodified metal catalysts of the prior art. In addition, improved cure response is achieved, especially response to cure at low temperature, due to the catalytic efficiency and reactivity associated with the method and complex of the present invention. Without wishing to be limited to the theory, it is conjectured that, due to its association with the polymeric ligand, the metallic catalyst is closer to the functional groups in reaction, i.e., the hydroxy-functional groups of the resin and the functional groups of NCO free of the unlocked interlacing, during interlacing. The advantages associated with the present invention are realized in particular in the physical properties of the urethane coating, such as solvent resistance, chip resistance, and corrosion inhibition. i BRIEF DESCRIPTION OF THE DRAWINGS Other advantages of the present invention will be readily appreciated, as it is better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: Figure 1 is a bar graph summarizing the performance 50 MEK Double Rub Performance of examples A-J at two different temperatures; Figure 2 is a bar graph summarizing% pin loss of Examples A-J in CRS panels (with zinc phosphate treatment); Figure 3 is a bar graph summarizing% paint loss of examples A-J on Zn / Fe panels; Figure 4 is a bar graph summarizing an average corrosion diameter (mm) of Examples A-J in the corrosion test G; and Figure 5 is a bar graph summarizing an average corrosion diameter (mm) of Examples A-J in the corrosion test L.

DETAILED DESCRIPTION A method according to the present invention catalyzes a reaction to form a urethane coating. The reaction to form the urethane coating is, more specifically, the reaction of a hydroxy-functional resin and a blocked isocyanate interleaver, also referred to as a curing agent. The hydroxy-functional resin and the blocked isocyanate crosslinker react, or interlock, after unlocking the interlayer to establish urethane linkages (-NH-CO-0-) in the urethane coating. For descriptive purposes only, the hydroxyfunctional resin and the blocked isocyanate interleaver are described below simply as the resin and the interlayer, respectively. The method more specifically uses a complex to catalyze a urethane coating composition to form the urethane coating. The resin.a and the interlayer are components of the urethane coating composition. As alluded to immediately above, the urethane coating, also referred to in the art as a urethane film or an unsuitable urethane layer, is formed from the coating composition.

I of urjetane in the application of the urethane coating composition to a substrate and in curing the urethane coating composition. The urethane coating results once the urethane coating composition is sufficiently cured. Illustrative urethane coatings include urethane powder coatings, automotive urethane base coatings, automotive urethane clear coatings, urethane coatings, urethane primer coatings, continuous precoat coatings, and urethane wire coatings and simihares. These and other urethane coatings can be formed from urethane coating compositions which are solvent systems or water systems. | Preferred applications for the present invention are in urethane coatings, or e-coatings, whereby the Urethane coating composition is a cathodic electrocoat composition or anodic electrocoat composition. With urethane electro-coatings, the urethane coating composition is deposited electrophoretically on a substrate, such as a structural body of a motor vehicle, by immersing the substrate in a bath including the urethane coating composition. An electrical potential is applied between the substrate and an opposite load pole, usually a stainless steel electrode. This produces a relatively smooth coating on the substrate. This relatively smooth coating is converted to the LRW coating of the present invention by entangling the resin and the luer on exposure to elevated temperatures as is known to those skilled in the art. | In addition to the hydroxy functionality, that is, one or more groups containing active hydrogen, the resin preferably has one or more ionic groups or groups convertible into ionic groups. Ionic groups or groups that can be converted to ionic groups can be anionic groups or groups that can be converted into anionic groups, for example, acid groups such as -COCH groups, or cationic groups or groups that can be converted into cationic groups, for example, basic groups such as amino groups and ammonium groups such as quaternary ammonium groups, or phosphonium and / or sulfonium groups. Basic groups containing nitrogen are particularly preferred. These groups may be present in quaternized form, or at least become partially in ionic groups with a customary neutralizing agent such as an acid, for example, an organic monocarboxylic acid, such as formic acid or acetic acid, for example. For example, it is ideal that the resin be neutralized with an acid, such as formic acid, before the reaction of the resin and the interlayer. Once neutralized, the resin is more conductive to be dispersed in water. With the preferred applications of urethane electro-coatings, the resin is more preferably an amine-modified resin of an epoxy compound, most preferably a cationic resin. However, as alluded to above, anionic resins can also be used. Said epoxy resins are common throughout the urethane electrocoating industry and are typically the reaction product of (A) polyepoxides, (B) primary and / or secondary amines or salts thereof and / or salts of tertiary amines, and optionally (C) polyfunctional alcohols, polycarboxylic acids, polyamines, and / or polysulfides. Suitable amine-modified resins derived from epoxy compounds include, but are not limited to, those described in U.S. Patents. Nos. 4,882,090 and 4,988,420, the descriptions of which are incorporated herein by reference, and also those commercially available as resins from BASF Corporation of Southfield, Michigan under the tradename CathoGuard®. The interleaver, as indicated above, is a blocked isocyanate interleaver and is of the type described in the U.S. Patents.

Nos. 4,882,090 and 4,988,420, the descriptions of which have already been incorporated herein by reference. The linker preferably has one or more functional groups reactive with the hydroxy-functional groups of the resin. The interleaver, more specifically, has an average higher than one isocyanate functional group (NCO) per molecule that becomes unblocked at the time of curing the urethane coating composition at elevated temperatures. More specifically, with the particular resins used in the urethane coating composition, any desired crosslinker is possible wherein the NCO group or functional groups have been reacted with a blocking group or compound, so that the interleaver formed is resistant to the hydroxy-functional groups of the resin at room temperature but reacts with the hydroxy-functional groups of the resin at the elevated temperatures which are generally within the range of about 93 ° C to about 204 ° C. I In the preparation of the interleaver, it is possible to use any desired organic isocyanate, typically polyisocyanate, suitable for interlacing. Preference is given to isocyanates containing about 3 to 36, in particular about 8 to about 15, carbon atoms. Examples of suitable diisocyanates include, but are not limited to, trimethylene diisocyanate, tetramethylene diisocyanate, penfylmethylene diisocyanate, hexamethylene diisocyanate, propylene diisocyanate, ethylethylene diisocyanate, 2,3-dimethylethylene diisocyanate, diisocyanate 1. - i methyltrimethylene, 1,3-cyclopentylene diisocyanate, diisocyanate 1. 4- cyclohexylene, 1,2-dichlohexylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 2,4-toluylene diisocyanate, 2,6-toluylene diisocyanate, 4.4-diisocyanate -diphenylene (for example, 4,4'-methylene bidifenyldiisocyanate), diisocyanate 1. 5- naphthylene, 1,4-naphthylene diisocyanate, 1-isocyanatomethyl-5-isocyanurate-1,3,3-trimethylcyclohexane, bi (4-isocyanatocyclohexyl) -methane, bi (4-isocyanatophenyl) methane, ether 4.4 '-diisocyanatodiphenyl and 2,3-bi (8-isocyanatoctyl) -4-octyl-5-hexylcyclohexane. It is also possible to use polyisocyanates of higher isocyanate functionality. Examples of these include tri (4-isocyanatophenyl) methane, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, 1,3,5-tri (6-isocyanatohexylbiuret), bi (2,5-diisocyanate), 4-methylphenyl) methane, and polymeric polyisocyanates, such as dimers and trimers of diisocyanatotoluene. It is also possible to use mixtures of polyisocyanates. The isocyanates which are considered to be used as the interlayer in the invention may also be prepolymers which are derived, for example, from a polyol, including a polyether polyol or a polyester polyol. For the blocking group of the interlayer, aliphatic, cycloaliphatic or alkyl aromatic alcohols are suitable. Examples of suitable aliphatic alcohols for the blocking group include, but are not limited to, methyl, ethyl, chloroethyl, propyl, butyl, amyl, hexyl, heptyl, octyl, nonyl, 3, 3, 5-trimethylhexyl, decyl or lauryl alcohol . Examples of suitable cycloaliphatic alcohols for The blocking group includes, but is not limited to, cyclopentanol or cyclohexanol. Examples of suitable aromatic alkyl alcohols for the blocking group include, but are not limited to, phenylcarbinol and mephenylcarbinol. Other suitable blocking groups are hydroxylamines such as ethanolamine, oximes such as methyl ethyl ketone oxime, acetone oxime and cyclohexanone oxime or amines such as dibutylamine and diisopropylamine. Several caprolactams, such as e-caprolactam, are also suitable as blocking groups for the interlayer. The isocyanates and blocking groups mentioned, as long as these components are mixed in suitable ratios, can also be used to prepare partially blocked interlators. At the elevated temperatures described above, the blocking group unblocks, ie leaves or disassociates chemically, from the interlacer. The method includes the step of forming a polymeric ligand of the resin and / or the interlayer. That is, the polymeric ligand can be formed from the resin alone, from the interlayer only, or from both the resin and the interlayer. The resin and / or the interlayer function as the ligand for a metallic catalyst described below. In any case, in forming the polymeric ligand, it is preferred that the resin and / or the interlayer are carboxylated to form the polymeric ligand. When formed from the resin, the polymeric ligand preferably has a molecular weight n, greater than about 1,000 Daltons, more preferably greater than about 2,000 Daltons. When the interlacer is formed, X and Y of the hydroxy-fional resin are the same as described generally above. The anhydride used immediately before in the specific chemical representation is a doxycyclic anhydride (DDSA), where the R 'of the anhydride is a hydrogen atom and R "of the anhydride is an alkenyl group with 12 carbon atoms Other suitable anhydrides include, but are not limited to, maleic anhydride, hexahydrophthalic anhydride, nitrilophthalic methyl-hexahydride, tetrahydrophthalic anhydride, italic anhydride, succinic anhydride, trimellitic anhydride, and mixtures thereof In the above specific chemical representation of the polymeric ligand, 1 mole of the anhydride is reacted for every 1 mole of the resin, as is further emphasized below, it should be understood that the above chemical representation is an idealized structure for the polymeric ligand and, therefore, is merely illustrative. It should be understood that it is not necessary that the entire polymer structure be modified with the anhydride. In fact, most of the polymer structure is left unmodified by the anhydride. It is only necessary to modify enough polymer structure to provide enough ligand to coordinate with the metal catalyst being introduced so that sufficient cure results can be achieved. One way to describe the degree of modification by the anhydride is that an anhydride is grafted by polymer structure to form the polymeric ligand. As understood by those skilled in the art, the terminology polymer structure is used interchangeably with other terms in the art including polymer chain, polymer molecule and polymer segment. In an alternative embodiment, the polymeric ligand is formed from the interlayer instead of the resin. Typically, the interlayer is carboxylated to form the polymeric ligand by reacting a hydroxy-functional carboxylic acid with the interlayer. The hydroxy-functional carboxylic acid must be hydroxy-functional to the extent that it has at least one hydroxy group. Preferably, the hydroxy-functional carboxylic acid has two hydroxy groups. As such, the hydroxy-functional carboxylic acid may be a monol carboxylic acid, having a hydroxy group and the carboxylic acid group, or a diol carboxylic acid, having two hydroxy groups and the carboxylic acid group. í > and describes below a general formula suitable for the hydroxy-functional carboxylic acid with a hydroxy group and the carboxylic acid group. wherein and R2 each independently comprises an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, an alkyl ether group, or a hydrogen atom. Examples of said hydroxy-functional carboxylic acids include, but are not limited to a, | á c i d o lactic and 12-hydroxystearic acid. A general formula suitable for hydroxy-functional carboxylic acid with two hydroxy groups and the carboxylic acid group is described below. wherein R ,, R2 and R3 each independently are organic chains having from 1 to 8 carbon atoms. Examples of said hydroxy-functional carboxylic acid include, but are not limited to, 2,2'-bi (hydroxymethyl) propionic acid, also referred to as dimethylolpropionic acid (D PA), 2,2-bi (hydroxymethyl) butyric acid, and dimethylbi (hydroxymethyl) malonate. The carboxylation of the interlayer with the carboxylic monol acid is generally described in the following chemical representation wherein the exemplary interlayer is 4,4'-methylene bidifenyldiisocyanate (MDI) which is a pure MDI isomer which is commercially available from BASF Corporation under the trade name Lupranate® M. It should be understood that this pure MDI isomer is used herein primarily for illustrative purposes. To this end, it should be understood that polymer-grade interlayers, such as polymeric MDI, are most commonly used. or an aromatic alkyl group. R, and R2 each independently comprises an alkyl group, an alkenyl group, an alkynyl group, an aromatic group, an alkyl ether group, or a hydrogen atom. In addition, the first reaction illustrates blocking the interleaver with an alcohol such as the blocking group, and the second reaction illustrates the carboxylation of the interleaver with the monol carboxylic acid. A typical blocker group alcohol is diethylene glycol butyl ether alcohol (Bu-0-CH2CH2-0-CH2CH2-OH), wherein R '"is Bu-0-CH2CH2-0-CH2CH2 0. The polymeric ligand comprises the reaction product of the interlayer and the hydroxy-functional carboxylic acid, in this case the monol carboxylic acid In this particular chemical representation, one mole of the hydroxy-functional carboxylic acid is reacted for each mole of the interlayer The carboxylation of the interlayer with the diol carboxylic acid it is generally described in the following chemical representation where the exemplary hydroxy-functional carboxylic acid is D PA and the exemplary interlayer is 4,4'-methylene bidifenyldiisocyanate (MDI) as described above. , as well as the other general chemical representations included herein, are merely to illustrate generally the salient characteristics of the components and the reaction. They should not be exact representations.

Particular chemical representation, one mole of the hydroxy functional carboxylic acid is reacted for each mole of the interleaver. The remaining hydroxyl group in the polymeric ligand also it can be reacted with isocyanate to extend the chain of the structure. This will result in a carboxyl group in the middle of the polymer chain. The method of the present invention also includes the steps of incorporating the metal catalyst with the polymeric ligand to complex the metal catalyst with the polymeric ligand and reacting the resin and the interlayer to form the urethane coating. The complex includes the reaction product of the polymeric ligand, as represented above, and the metallic catalyst which is in complex with the polymeric ligand. In this context, the reaction product is a metal carboxylate. It is ideal that the metal catalyst be incorporated with the polymeric ligand before reacting the resin and interlayer to form the urethane coating. However, it should also be recognized that, in theory, the metallic catalyst could be incorporated with the polymeric ligand as the resin and the interlayer are reacted to form the urethane coating instead of before the reaction. Preferably, the metal catalyst is of the formula gene to that of MO or M (OH) not R \M, wherein M is a metal selected from the group consisting of Bi, Sn, Sb, Zn, Y, Al, Pb , Z Ir, Ce, Cu and mixtures thereof, O represents an atom of oxygen, OH represents a hydroxide ion, n is an integer that satisfies the valence of M, R4 is an organic group, preferably alkyl, having from 4 to 15 carbon atoms, and x is an integer from 1 to (> this way, in this preferred scenario, the step of incorporating the metal catalyst with the polymeric ligand comprises incorporating a metal catalyst of the general formula MO or M (OH) not R4xMO.Dibutyl tin oxide and a metal oxide, such as sodium oxide. Zinc or bismuth oxide, are combined or independently, the preferred metal catalysts for use in the present invention It is also understood that the various metal catalysts of the formulas MO or M (OH) not R xMO can be used alone or in combinations In other words, a metal catalyst or even a combination of metal catalysts can be used Other potential metal catalysts include, but are not limited to, several other zin oxides c or bismuth, are, Sn02, Y2O3, and CuO. Preferably, the metal catalyst, including the exemplary oxides listed above is supplied in a milled form having a low particle size (eg, less than 20 microns, more typically less than 10 microns), so that no additional milling is needed for reducing the particle size of the metal catalyst for effective incorporation of the metal catalyst with the polymeric ligand. In the context of the preferred embodiment wherein the polymeric ligand is formed by carboxylating the resin, the metal catalyst is complex. It should be appreciated that, although not shown, the metallic catalyst can be complexed with the interlayer instead of the resin as described immediately above. The metallic catalyst can be incorporated with the polymeric ligand at various times. In one embodiment, the metal catalyst actually incorporates the polymeric ligand simultaneously with the step of forming the polymeric ligand of the resin and / or the interleaver, that is, as the polymeric ligand itself is being formed. Alternatively, the metal catalyst can be incorporated with the polymeric ligand after the polymeric ligand is formed and prior to the reaction of the resin and the interlayer to form the urethane coating. For example, a pigment-containing composition can be incorporated before the step of reacting the resin and the interlayer. As is known in the art, said pigment-containing compositions are common with the electrocoating compositions described above. These pigment-containing compositions can also be refered as pigment pastes. The metal catalyst can be incorporated into the pigment-containing composition to complex the metal catalyst with the polymeric ligand. In any case, the metal catalyst, such as a simple metal oxide, is complexed with the polymeric ligand before! of reaction of the resin and the interlayer to form the urethane coating. | It must be understood that all chemical representations precedents are merely chemical representations of two dimensions and that the structure of these chemical representations may be different from that indicated. The following specific illustrative examples associated with the urethane coating composition and the complex and its use in forming the urethane coating according to the present invention, as presented herein, should illustrate and not limit the invention.

EXAMPLES Twenty examples, specifically A-T examples, are prepared as described below and as indicated in Tables I A, IB, 2A and 2B. Examples A-J use emulsion 1 and examples K-T use emulsion 2. Examples A-F, I, J-P, S and T are examples according to the invention. Examples G and Q are a form of a control example where, although DDSA is included in the urethane coating composition, no metallic catalyst is included. Examples H and R are another form of a control example where, although a metal catalyst is included in the urethane coating composition, no anhydride is included to carboxylate the resin. The examples are everything! »Urethane coating compositions, specifically cationic urethane electrodeposition coatings. In these examples, the hydroxy functional resin is carboxylated with the arid, specifically with dodecenylsuccinic anhydride (DDSA). A suitable hydroxy-functional resin for these examples is a cathodic electrodeposition resin. The DDSA is obtained from Dixie Chemical of Pasadena, TX. As described in greater detail more oidelante, this reaction product is in the form of an emulsion, emulsions 1 and 2 below. Additionally, a pigment-containing composition is used, also known to those skilled in the art as a pigment paste. For all examples, except for examples J and T, the metal catalyst is incorporated into the pigment paste and then the pigment paste containing the metal catalyst is incorporated into the emulsion to establish an electroplating bath wherein the metal catalyst it is complexed with the hydroxy-functional resin. The type 1 emulsion is made more specifically in the following manner. In a 3L bottle with an associated heating mantle are combined: diglycidyl ether of biphenol A, DGEBA, (17.94 g, 0.095 eq epoxy), biphenol A, BPA, (4.08 g, 0.036 eq. OH), a phenol or substituted phenol (0.015 eq. OH) (such as dodecylphenol, p-cresol, phenol, or combinations thereof), and xylene (0.357 g). shake, the temperature rises to 125 ° C. Subsequently add triphenyl phosphine (0.032 g) in xylene (0.07 g) and record the exotherm (189 ° C). The mixture is then allowed to cool to 132 ° C, and a WPE determination is keyed (target = 525 +/- 25) and is 529. After cooling to 82 ° C and turning off the heating mantle, 0.016 eq. N of an amine, such as dietanol amine, methylethylanolamine, or combinations thereof, is introduced and the exotherm is recorded (107 ° C). The mixture is allowed to stir for an additional 30 minutes after reaching exotherm. After stirring for 30 minutes, 3-dimethylamino propyl amine is added at 105 ° C, and the exotherm is recorded (144 ° C). The mixture is stirred for an additional hour. Subsequently, a solution of toluene (O. 44 g) of DDSA (1.13 g, 0.004 eq.) Is introduced at 105 ° C, and the mixture is allowed to stir for about 1.5 hour. An additional 50 g of toluene is added. Then Pluracol P710R polyol (2.5413 g) is added followed by the interlayer (13.53 g, 0.051 eq.) And Dowanol PnB (0.344 g). The interlayer is a blocked isocyanate based on polymeric DI and monofunctional alcohols, such as diethylene glycol butyl ether. After achieving a homogeneous mixture, the carboxylated resin is added to an acid mixture, under constant agitation, including deionized water (31,095 g), formic acid (85%) (0.588 g), and nitric acid (0.050 g). After completely mixing all the components using a metal spatula with mixing, the theoretical solids are further reduced by the addition of water (20.0 g). Additives (0.4 g) are added independently, or in an additive package, to the acid mixture and to 20.0 g of water. All The raw material, including the various solvents used before, are industrial grade and no further purifications are made. The type 2 emulsion is made more specifically in the following manner. In a reactor equipped with an agitator, refill condenser, internal thermometer and inert gas inlet, 6150 parts of epoxy resin based on biphenol A having an epoxy equivalent weight (EEW) of 188 are heated to 125 ° C under an atmosphere of nitrogen together with 1400 parts of biphenol A, 335 parts of dodecylphenol, 470 parts of p-cresol and 441 parts of xylene and the mixture is stirred for 10 minutes. Subsequently, it is heated to 130 ° C and 23 parts of?,? - dimethylbenzylamine are added. The roaction mixture is maintained at this temperature until the EEW has reached the 880 g / eq level. A solution of toluene (118 g) of DDSA (389 g, 1377 eq.) Is then introduced at 105 ° C to form a carboxylated resin, and the mixture is allowed to stir for about 1.5 hour. A mixture of 7097 parts of the interleaver and 90 parts of a flow additive is then added and the resulting mixture maintained at 100 ° C. The interlayer is a blocked isocyanate based on polymeric fvlDI and monofunctional alcohols, such as diethylene glycol butyl ether and / or butyl digliool. Approximately 30 minutes later, 211 parts of butyl glycol and 1210 parts of isobutanol are added. Immediately after this addition, a mixture of 467 partel of a precursor (diethylenetriamine diketimine in methyl isobutyl cetbna) and 520 parts of methylethanoiamine are introduced into the reactor and the batch is brought to a temperature of 100 ° C. After an additional half hour, the temperature is raised to 105 ° C and 159 parts of α, β-dimethylaminopropylamine are added. 75 minutes after the addition of amine, 903 parts of Plafetilit® 3060 (composed of propylene glycol, BASF / Germany) are added and the mixture is diluted with 522 parts of propylene glycal phenyl ether (mixture of 1-phenoxy-2-). propanol and 2-phenoxy-1-propanol, BASF / Germany), in the course of which it is rapidly cooled to 95 ° C. After 10 minutes, 14821 parts of the reaction mixture are transferred to a dispersion vessel. 474 parts of lactic acid (88% in water), dissolved in 7061 parts of deionized water, are added in portions with stirring. The mixture is subsequently homogenized for 20 minutes before further dilution with 12,600 additional parts of deionized water in small portions. The volatile solvents are removed by vacuum distillation and then replaced by an equal volume of deionized water. j The metal catalysts included in the tables below are added in a pigment paste. The raw material for metallic catalysts, metal salts, are usually available in the form of ZnO, Bi203, Bu2SnO, Sn02, Zr02, Y203 and CuO from Aldrich Chemical Co. As is known to those skilled in the art, pigment pastes for urethane-based electrecoverings also include the pignjiento (s), fillers and additives. The pigment paste containing the metal catalyst is incorporated into the emulsion to establish an electroplating coating wherein the metal catalyst is complexed with the polymeric ligand, in these examples the carboxylated hydroxy functional resin, to catalyze the urethane forming reaction at the time of healing.

EXAMPLES A-J Composition Example of Relative Level of Quantity Quantity Urethane coating paste anhydride emulsion (DDSA) of DDSA pigment (Electroplating bath) 1 Weight mmol (%) 2 HIGH 10 DBTO B HIGH 10 DBTO HIGH 10 DBTO D HIGH 10 DBTO HIGH 10 DBTO ALTO 10 DBTO ALTO 10 DBTO H DBTO UNDER 1.5 DBTO HIGH 10 DBTO TABLE 1A TABLE 1B EXAMPLES K-T TABLE 2A TABLE 2B Approximately 6500 g with 19% non-volatile and one P / B = 0.16; 2 _ (grams of DDSA) / (grams of emulsion solids) X 100%; added during the preparation of the resin in the emulsion (except for Example J); 3 _ (mmol of DDSA) / (grams of emulsion solids) X 100%; 4 = pigment paste contains approximately 0.50% DBTO (dibutyl tin oxide) relative to emulsion solids; 5 _ added to the pigment paste in the oxide form; 6 _ (grams of metal) / (grams of emulsion solids) X 100%; Y 7 _ (mmol of metal) / (grams of emulsion solids) X 100%; 8 _ Metallic catalyst added directly to the emulsion (after carboxylation with DDSA and then the interlayer) instead of the pigment paste.

With the urethane coating compositions of the formed sheets, panels are prepared for certain tests (described in detail below) involving only examples A-J. The tests are the ME Double Rub solvent resistance test, the apostille resistance test, and the G and L corrosion tests. Two types of panel substrates are used depending on the particular test: cold rolled steel treatment (CRS ) with zinc phosphate and panels treated with zinc-hierium (Zn / Fe). All panels are 4"x 6" in dimension and are purchased from ACT. The panels are electrorevised by techniques known to those skilled in the art for film constructions of 0.40 thousand and 0.80 thousand, again depending on the try particular.

MEK Double Rub Solvent Resistance Test: As an initial screening tool to evaluate the cure, double stripping with methyl ethyl ketone (MEK) is carried out. The panels are CRS with zinc phosphate treatment and the urethane coating compositions are coated and cured at various times and temperatures to form urethane coatings of about 0.80 mil. Using a piece of cheesecloth soaked with MEK and wrapped around the index finger, a total of 20, 50, and 100 double rubs are carried out using light pressure. After the double strips, the panels are rated: 0 (no change), 1 (light change), 3 (moderate change), and 5 (severe change - metal exposure, failure). The complete data for the MEK double-strength solvent resistance test of Examples AJ is found later in Table 3. For illustrative purposes, a graph summarizing the performance of 50 MEK Double Rub of the AJ examples at two temperatures different is included as figure 1.

All panels baked at 290 ° F (approximately 143 ° C) exhibit full failure, except for those containing Zn and Sn at 20 strings after baking for 20 minutes. Better solvent resistance is noted after baking at 300 ° F (approximately 148 ° C). Baths containing Sn, Bi, Zr and Zn are found to exhibit moderate solvent resistance (ie, rating of 3) in this baking, while those that contain Cu and Y show complete failure. Do not add any cataloger or DDSA also produces poor results. Raising the bake temperature to 325 and 350 ° F (approximately 162 and 176 ° C, respectively) results in an increase in solvent resistance since all panels show no change except for | those coated with baths containing Cu and those that do not contain any catalyst or DDSA.

Tarring resistance test: The CRS with zinc phosphate treatment panels and Zn / Fe panels are coated with the urethane coating compositions of Examples A-J to form urethane coatings of approximately 0.8 mil. These panels cure at approximately 325 ° F for approximately 15 minutes. To these electro-coated panels, first apply a layer of primer, base coat and clear coat. The primer layer is a gray primer based on acrylic / polyester - melamine chemistry. The base layer is a layer white base based on acrylic - melamine chemistry. The transparent layer is a clear layer of high solids solvent also based on acrylic - melamine chemistry. The corresponding film construction for the primer layer, base coat and clear coat are 0.9-1.0, 1.0-1.1 and 1.7-2.0 mil, respectively. With the primer layer, a 5 minute flash is used in the area, followed by baking for 20 minutes at 325 ° F :. After applying the primer, a 10-minute zone rebate is used for the basecoat without any additional baking, and the clearcoat is subsequently sprayed, followed by 10-minute reheating and 20-minute baking at 280 ° F. . Using the Multi-Test Gravelometer, produced by Q-Panel Lab Products, resistance to apostillement is carried out by first placing each panel in a freezer (approximately -20 ° C) for at least 4 hours and then exposing the panels, individually, to two pints of gravel at 70 psi with an impact of 90 degrees. After cleaning each powder panel, a standard tape pull is performed using Scotch Filament Tape 898 with a width of 2 inches, and the VIEW Digital Image Analyzer 5.0, produced by ATLAS Analytical Instruments, is used to determine a paint loss as a percentage. The results are indicated in Figures 2 and 3. Referring to Figure 2, the best performance in CRS is observed using Sn, Bi and Zr as the catalyst. They are noticed adequate performance results with Zn, Cu and without the use of a catalyst and high DDSA content. And it shows relatively low performance in chipping resistance. Referring to Figure 3, similar trends are made with Zn / Fe panels since Sn, Bi and Zr show better resistance to astylation than Y and not using DDSA produces poor performance. Overall, referring to both figures 2 and 3, the addition of DDSA shows improved performance.

Corrosion test G (would give individual): The CRS with zinc phosphate treatment panels are coated with the urethane coating compositions of Examples A-J to form urethane coatings of about 0.8 mil. These panels are cured at about 325 ° L- for about 15 minutes. These panels are baked strategically at 325 ° F, unlike 350 ° F, to better differentiate performance. After coating, each panel is drawn directly in the middle with the vertical line shape, "|". The exposure cycle is as follows. On Monday, each panel is kept at 60 ° C for one hour in a circulating air oven and then subjected to a cold cabinet at -25 ° C and maintained for 30 minutes. Then, the panels are immersed for 15 minutes in a 5% (by weight) solution of NaCl (saline). After removing and let them air dry for 1 hour 15 minutes at room temperature, the panels are transfer to a humidity cabinet set at 60 ° C and 85% humidity with an air flow not exceeding 15 m / ft on the panel. From Tuesday to Friday, the panels are once again submerged for 15 minutes in the saline solution and left to dry in the air as previously explained. They are then transferred to the humidity cabinet and left over the weekend. The cycle is then repeated for a total of 5 cycles. After completing, each panel is rinsed with water and scratched with a metal spatula. The average corrosion diameter is then obtained by randomly selecting points on the dart. The results of the corrosion test G are summarized in Figure 4. Zinc-coated and low-level panels of DDSA show promising corrosion inhibition. Adding higher levels of DDSA seems to be crucial since an average corrosion diameter of 5.15 mm is obtained without the presence of any DDSA. The best system in operation (example D) contains the high level of D SA and 0.50% zinc and has an average corrosion of 2.51 mm. I Referring to Example J, adding the catalyst (zinc) to the resin also shows similar level of corrosion inhibition. In addition, decreasing the amount of DDSA by half also results in good corrosion inhibition in the presence of the same amount of zinc. As alluded to above, not adding anything of DDSA produces a panel exhibiting complete failure, even in the presence of zinc. Adding DDSA without any catalyst, however, leads to Satisfactory corrosion inhibition, which can be attributed to the activation of the DBTO, which is present in the pigment paste. Other metals working relatively well are Sn, Bj, Zr and Y.

Corrosion test L (double give): The CRS with zinc phosphate treatment panels are coated with the urethane coating compositions of Examples A-J to form urethane coatings of approximately 0.4 mil. These panels cure at approximately 325 ° F for approximately 15 minutes. These panels are baked strategically at 325 ° F, unlike 350 ° F, to better differentiate performance. After coating, each panel is drawn with the appearance of an "X". The initial adhesion and explosion is omitted in the L corrosion test. The daily test sequence and test cycle are carried out by placing the panels under test on any day between Tuesday and Friday. A total of 36 test cycles were carried out, with each cycle equating to one day. The cycle starts first by subjecting each panel to a 60-minute bake with an oven temperature of 60 ° C, followed by gradual cooling to room temperature for 30 minutes. The salt immersion and moisture portion of the test follows by first placing each panel in an aqueous solution of 5% (by weight) of NaCl for 15 minutes followed by drying at room temperature for 75 minutes. This is done once a week. After the dive, the Pancakes are placed in a humidity cabinet (85% humidity) set at 60 ° C for 22.5 hours (Note: on weekends, the panels are left in the humidity cabinet). After the 6 day cycle, the panels are removed from the test, rinsed completely and traced with a metal spatula to remove any loose paint. The average corrosion diameter is then obtained by using a gauge and taking random measurements on each side of the gauge. The results of the corrosion test L are summarized in figure 5. The combination of zinc and high levels of DDSA exhibits the best inhibition of corrosion with yttrium and bismuth also having an average corrosion diameter of less than 4 mm. Consistent with the corrosion test results G, the direct addition of zinc oxide to the resin (example J) provides adequate corrosion inhibition. The invention has been described in an illustrative manner, and it should be understood that the terminology that has been used should be in the nature of description words rather than limitation. Obviously, many modifications and variations of the present invention are possible in view of the above teachings, and the invention can be practiced otherwise than specifically described.

I

Claims (1)

1. CLAIMS 1. - A method of catalyzing a reaction of a hydroxy-functional resin and a blocked isocyanate interleaver to form a urethane coating, said method comprising the steps of: forming a polymeric ligand of the resin and / or the interlayer; Incorporating a metal catalyst with the polymeric ligand to complex the metal catalyst with the polymeric ligand; and reacting the resin and the interlayer to form the urethane coating. 2 - A method for catalyzing according to claim 1, wherein the step of forming the polymeric ligand of the resin and / or the interlayer comprises carboxylating the resin and / or the crosslinker. 3. A method of catalyzing according to claim 2, wherein the step of incorporating the metal catalyst with the polymeric ligand comprises incorporating the metal catalyst with the carboxylase resin and / or the carboxylated interlayer to complex the metal catalyst with the carboxylase resin and / or the carboxylated crosslinker. A method of catalyzing according to claim 1, wherein the polymeric ligand is formed from the resin and the carboxylating step comprises reacting an anhydride with the resin. 5l- A method of catalyzing in accordance with the claim 1, wherein the anhydride is selected from the group consisting of dodecyl succinic anhydride, maleic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, succinic anhydride, dodecyl anhydride, trimellitic anhydride, and mixtures thereof . 6. - A method of catalyzing according to claim 1, wherein the polymeric ligand is formed from the crosslinker and the step of carboxylating comprises reacting a hydroxy-functional carboxylic acid with the crosslinker. 7. - A method of catalyzing according to claim 6, wherein the hydroxy-functional carboxylic acid is selected from the group consisting of monol carboxylic acids, diol carboxylic acids, and mixtures thereof. 8. - A method of catalyzing according to claim 7, wherein the hydroxy-functional carboxylic acid is selected from the group consisting of lactic acid, 12-hydroxy stearic acid, dimethylolpropionic acid (DfvIPA), acid 2,2- bi (hydroxymethyl) butyric acid, dimethylbi (hydroxymethyl) malonate, and mixtures thereof. 9 - A method of catalyzing in accordance with the claim 1, wherein the step of incorporating the metal catalyst with the polymeric ligand comprises incorporating the metal with the polymaric ligand before reacting the resin and the interlayer. 10. A method of catalyzing according to claim 1, wherein the step of incorporating the catalyst resin with an acid before the step of reacting the resin and the interlayer. 16 - A method of catalyzing according to claim 1, wherein the urethane coating is a cathodic electrocoating. 17. A method of catalyzing according to claim 1, wherein the urethane coating is an anode electrocoating. 18 - A method of catalyzing according to claim 4, wherein the polymeric ligand formed of the resin has a molecular weight, n, greater than about 1,000 Daltpns. 19 - A method of catalyzing according to claim 6, wherein the polymeric ligand formed of the interlayer has a molecular weight, Sv1n, greater than about 800 Daltons. 20. A complex for catalyzing a urethane coating composition, said complex comprising the reaction product of: a polymeric ligand; and a metal catalyst complexed with said polymeric ligand. 21. - A complex according to claim 20, wherein said polymeric ligand is formed of a hydroxy-functional resin and / or a blocked isocyanate interleaver. 28. - A complex according to claim 20, wherein said metal catalyst is of the general formula MO or? (??)? or R \ MO, wherein M is a metal selected from the group consisting of Bi, S [n, Sb, Zn, Y, Al, Pb, Zr, Ce, Cu, and mixtures thereof, O represents a oxygen atom, OH represents a hydroxide ion, n is an integer that satisfies the valence of, R4 is an organic group that has 4 to 15 carbon atoms, and x is an integer from 1 to 6. 29. - A complex according to claim 20, wherein said urethane coating composition is a cathode electrocoating composition. 30. A complex according to claim 20, wherein said urethane coating composition is an anodic electrocoating composition. 31. - A complex according to claim 22, wherein said polymeric ligand formed of said hydroxy-functional resin and said anhydride has a molecular weight, Mn, greater than about 1,000 Daltons. 32. - A complex according to claim 25, wherein said polymeric ligand formed of said blocked isocyanate interleaver and said hydroxy-functional carboxylic acid has a molecular weight, Mn, greater than about 800 Daltons.