MXPA98007840A - Curable coating composition that has late functionality - Google Patents

Abstract

The present invention relates to a composition comprising a compound or resin having latent primary amine functionality. The compound or resin having the latent amine functionality is obtained by reacting a cyclic anhydride with an amine compound having two primary amine groups and a secondary amine group. The latent amine compound is combined with a compound or resin having a plurality of cyclic carbonate groups in a reticulab coating composition.

Description

COMPOSITION OF CURABLE COATING THAT HAS LATENT FUNCTIONALITY Field of the Invention The present invention relates to coating compositions and coating methods and in particular to said coatings having latent amine functionality.

BACKGROUND OF THE INVENTION Thermosetting and curing coating compositions are widely used in coating operations. In automotive coatings in particular, the thermosetting coatings provide durable finishes. Automotive coatings include primers and top coatings, which can be single-layer top coatings or two-coat top coat / base coat systems. The primer can be applied either as a first coating layer or on another layer, for example on an electrocoat coating primer. The top coating is usually then applied directly onto the primer layer.

Various problems arise with the thermosetting coating compositions. One consideration is the curing conditions necessary to achieve sufficient film crosslinking. In general, higher curing temperatures and longer times in the curing temperature increase the manufacturing costs of the coated article. Another important issue in some cases is that undesirable by-products of the curing reaction are generated. For example, blocked curing agents usually release blocking agents as volatile organic compounds that are regulated emissions by various governmental rules. It is also important that the cross-links formed by the curing thermosetting composition are appropriate to provide long life to the coating according to the particular conditions to which the coated article will be exposed. One type of thermosetting reversal is the electrocoat coatings. Electrocoating methods, or electrodeposition coating, have been used commercially to apply protective coatings to metal substrates for a number of years. In the process of electrodeposition coating, a conductive article or substrate to be coated is used as an electrode in an electrochemical cell. The article is immersed in an aqueous dispersion of the coating composition, which contains a charged resin, preferably a cationic resin. The resin is deposited on the article by applying an electric potential between the article and a second electrode (which can be, for example, the walls of the container that retains the bathroom). The coating is deposited on the article until it forms an insulating layer on the article which essentially prevents more current from passing. The electrocoating process is particularly suitable for applying a protective primer layer -, 15 continuous and uniform to an article or piece of work that has a complex configuration or construction. When the surfaces of the article closest to the other electrode have been coated and isolated, the current then deposits the coating into the areas recesses and other less accessible areas until the insulating coating layer is formed on all conductive surfaces of article or workpiece, regardless of how irregularly the article is configured.

Electro-coating processes. particularly for coating automotive bodies and parts, they usually employ a thermosetting coating composition comprising an ionic, preferably cationic, main resin and a polyfunctional oligomeric or monomeric crosslinking agent which is capable of reacting with the main resin to cure or crosslink the coating . The crosslinking agent is associated with the main resin in the dispersion and is deposited together with the main resin on the article or work piece. After the deposition, the deposited coating can be cured to a durable, crosslinked coating layer. A number of crosslinking mechanisms may be employed in the thermosetting coatings. A curing mechanism uses a melamine formaldehyde resin curing agent in the coating composition to react with hydroxyl groups in the resin. This curing method provides good cure at relatively low temperatures (e.g., 121aC with a blocked acid catalyst, or even lower with an unblocked acid catalyst), but the crosslink bonds contain undesirable ether linkages and coatings resulting low total durability under certain service conditions or low corrosion resistance as well low resistance to chipping and cyclic corrosion in electrodeposition coatings. In an alternative curing method, the polyisocyanate crosslinkers can be reacted with amine or hydroxyl groups in the resin. This curing method provides urea or urethane crosslinking bonds, but also has various disadvantages. In order to prevent premature gelation of the coating composition, the polyisocyanate must be kept separate from the resin in what is known in the art as a Two-pack or double-pack coating system, or the highly reactive isocyanate groups in the curing agent must be blocked (eg, with an oxime or alcohol). The blocked polyisocyanates, however, require high temperatures (e.g., 150SC or more) to unblock and start the curing reaction. The resulting electrocoating can also be susceptible to yellowing. Additionally, volatile release blocking agents during curing can adversely affect the coating properties and increase emissions, decreasing the amount of solid material in the coating composition that eventually becomes part of the cured film formed on the substrate. In this way there is a need in the field of coating compositions that can provide desirable urethane crosslinkers, but avoid the problems that accompany the use of polyisocyanate curing agents. Coating compositions comprising carbonate curing agents and crosslinkable primary functional amine resins have been proposed for electrocoating primers in December and Col., U.S. Patent. No. 5,431,791. The Patent of E.U.A. No. 5,431,791 discloses a method of cathodic electrodeposition which applies a coating layer of a resin having a plurality of primary amine groups salted with acid and a curing agent having a plurality of cyclic carbonate groups. In the electrocoating bath, the primary amine groups are rendered unreactive with the carbonate groups of the crosslinker. When the coating is deposited towards the conductive substrate, the primary amine groups are generated from the salt and once again are reactive towards the crosslinker. This method for achieving packing stability, however, is inappropriate for compositions in which the primary amines are not salted. Also in this method, high levels of salty primary amine were needed in order to achieve desirable levels of crosslinking. He High content of salty primary amine, however, can cause excessive bath conductivity. In this method, elevated levels of the salt primary amine were needed in order to achieve desirable levels of crosslinking.

SUMMARY OF THE INVENTION A coating composition capable of forming durable urethane bonds has now been invented by curing the coating without the inherent problems of polyisocyanate curing agents. The compositions of the present invention comprise a compound or resin having a latent primary amine functionality and a compound or resin having a plurality of cyclic carbonate groups. The latent amine compound is formed by reacting a compound having at least two primary amines and at least one functional groups that remains unreacted with a cyclic anhydride of a polycarboxylic acid. The unreacted functional group of the latent amine compound is reacted with the resin to form a resin with latent amine functionality. The present invention further provides a method of coating a substrate by applying a coating composition comprising a resin or compound having a latent primary amine functionality and a carbonate resin or compound having a plurality of cyclic carbonate groups and then curing the applied composition. The present invention also provides a substrate having thereon a coating derived from a composition containing a resin or compound having latent primary amine functionality and a carbonate compound having a plurality of cyclic carbonate groups. In a preferred embodiment, the coating composition of the invention is an electrodeposition coating composition comprising, in an aqueous medium, a cationic resin having latent primary amine functionality and a curing agent having a plurality of cyclic carbonate groups. The latent amine functionality of the electrocoating compositions of the invention is available for crosslinking when the deposited coating cures, but does not increase the bath conductivity or cause coating deposition problems as would the free amine groups. The cationic resin may additionally have primary salt amine groups which, after deposition, provide primary amine groups as additional crosslinking sites, The present invention further provides a method for coating a conductive substrate. In the method of the invention, a conductive substrate is immersed in an electrodeposition coating composition comprising, in an aqueous medium, a cationic resin having latent primary amine functionality and a curing agent having a plurality of carbonate groups cyclic; then, an electric current potential is applied between an anode and the conductive substrate (which is then the cathode) to deposit a coating layer towards the conductive substrate. The present invention also provides a conductive substrate having thereon a coating derived from the composition containing a resin having latent primary amine functionality and a curing agent having a plurality of cyclic carbonate groups.

Detailed Description The compositions of the invention include a compound or resin having latent primary amine functionality and a curing agent with a plurality of cyclic carbonate groups. The compound having latent amine functionality can be formed by reacting two moles of a cyclic anhydride of an acid polycarboxylic with two moles of a compound having at least two primary amine groups - The resin having latent amine functionality can be formed by a two-step synthesis. In the first case a, two moles of a cyclic anhydride of a polycarboxylic acid are reacted with two moles of a compound having at least two primary amine groups and at least one group reactive with a functional group in the main resin. In a second step, the product of the first stage is reacted with a resin to form the main resin with latent primary amine functionality. The compound having the plurality of cyclic carbonate groups has at least two carbonate groups, and preferably has more than two carbonate groups on average per molecule. In the synthesis of the compound with latent primary amine functionality, an amine compound with preferably two primary amine groups is employed. The amine compound may optionally have additional functional groups that are not primary amine groups, so long as said groups do not interfere with the reaction between the primary amine groups of the amine compound and the cyclic anhydride. Suitable examples of the primary amine compounds include, without limitation. alpha, omega-alkylenediamines and polyalkylene polyamines. Examples of suitable polyalkylene polyamines include, without limit, ethylenediamine, diethylenetriamine, triethylene tetra, tetraethylenepentamine, dipropylenetriamine, 1,6-diaminohexane, 1,3-diaminopropane, imino-bis (propylamine) methyl, 1-4, diaminobutane, and mixtures thereof. Particularly preferred among these are ethylene diamine, diethylenetriamine, dipropylenetriamine and mixtures of these compounds. Preferred polyamines have molecular weights in the range of from about 60 to about 400, more preferably from about 60 to about 250, and still more preferably from about 60 to about 160. In the first step of the synthesis of the primary resin with latent primary amine functionality, an amine compound with at least two primary amine groups and at least one different reactive group is employed. Preferably, the amine compound has up to three, more preferably one or two, and particularly preferably a group that is reactive with an epoxide group. Preferably, the amine compound has a secondary amine group. Appropriate examples of the primary amine compounds include. without limit, polyalkylene polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, dipropylenetriamine, and mixtures thereof. Diethylenetriamine is particularly preferred among these, dipropylenetriamine, and mixtures of these compounds. Preferred polyamines have molecular weights in the range of from about 75 to about 400, more preferably from about 75 to about 250, and still more preferably from about 100 to about 160, The appropriate examples of cyclic anhydrides of polycarboxylic acids which can be used in the reaction with the primary amine compound include, without limit, phthalic anhydride and substituted phthalic anhydride derivatives such as 4-sulfophthalic anhydride, 4-methylphthalic anhydride, 3-hydroxyphthalic anhydride, nitrophthalic anhydride, and 4,4 anhydride. '-carbonildiftálico; hydrogenated derivatives of phthalic acid such as hexahydrophthalic anhydride, anhydride 1,2,3,6-tetrahydrophthalic 3,4,5,6-tetrahydrophthalic anhydride hexahydro-4-methylphthalic anhydride and methyltetrahydrophthalic anhydride; Maloic anhydride and its derivatives, such as 2,3-dimethylmalonic anhydride, 2,3-diphenyl-malic anhydride, bromomaléic anhydride, and dichloromaléic anhydride; pyromellitic dianhydride; succinic anhydride and its derivatives, such as dodecenylsuccinic anhydride, and methylsuccinic anhydride; 1,2-cyclohexane dicarboxylic acid, methyl acid anhydride (methyl-5-norbornene-2, 3-dicarboxylic anhydride), cis-5-norbornene-endo-2,3-dicarboxylic anhydride, itaconic anhydride, 2, 3- anhydride pyridinedicarboxylic pyromellitic dianhydride, endo-bicyl (2.2.2) oct-5-en-2,3-dicarboxylic anhydride, 1,2,4,4-cyclobutetracarboxylic dianhydride, and 1-cyclopentene-1,2-dicarboxylic anhydride. Preferred among these are phthalic anhydride and substituted derivatives of phthalic anhydride and hydrogenated derivatives of phthalic acid. The reaction between the cyclic anhydride and the amine compound is preferably carried out with purified reagents and with an excess of the primary amine compound in order to minimize the polydispersity of the product. Thus, even when a ratio of about one mole of primary amine compound to about one mole of the anhydride is the stoichiometric ratio of the reactants, the reaction is preferably carried out using an excess of the amine compound. It is preferred to employ a ratio of at least about two moles, and preferably at least about three moles, of the primary amine compound per mole of the anhydride. In a particularly preferred embodiment, a ratio of about four moles of the primary amine compound per mole of the anhydride is used. For example, it is preferred to react a ratio of about four moles of distilled diethylenetriamine to about one mole of reactive grade phthalic anhydride to form a latent primary amine compound. The excess amine compound is separated, for example by vacuum distillation, after completion of the reaction. Due to the reasons that the person of experience in the field will observe, the ratio of moles of primary amine compound to anhydride should not be too high, and it is preferred that the ratio does not exceed about eight moles, and preferably about six. moles, of primary amine compound per mole of anhydride. The product of the excess amine compound process is found to have a low concentration, or to be free, of residual carboxylic acid groups. It is intended to indicate that the cyclic tetramide is preferably formed on a linear product. The reaction product of the amine compound and the cyclic anhydride can have a polydispersity of about 20, but polydispersities are preferred inferiors The polydispersity is preferably less than about 5. More preferably, especially when the reaction product is then reacted to form the resin having latent amine functionality, the reaction product of the amine compound and the cyclic anhydride has a polydispersity of about 3 or less, still more preferably about 2 or less, and even more preferably about 1.1 or less. Reaction products that have a polydispersity of about 1.05 or less are particularly preferred. The reaction product has at least two latent primary amines per molecule on average. The crosslinkable r-egsj-na compound of the invention has latent amine functionality that can be represented by the structure (a): O H H O il i H C_ N- L2 N - C \ L1 L1 a) \ / C- - L2 - N - C "I I II O H H o wherein L1 is a b-divalent bond g-cx? D in pl link valencies, which connect to the bonus of the - íe - amide carbonyl, are on two adjacent carbon atoms and where L2 is a linking group with the terminal carbon atoms. Adjacent link carbon atoms of L1 can be linked together with a single bond (as for the product prepared using hexahydrophthalic anhydride), a double bond (as for the product prepared using maleic anhydride), or an aromatic linkage (as the product prepared using phthalic anhydride). Either or both of the adjacent link carbon atoms can carry a substituent or the adjacent link carbon atoms can be members of an aliphatic or aromatic ring, wherein the ring itself can be substituted at any available carbon atom. In this way, L1 can have different structures R1 R2 Rs R6 i 'I I -C - C -c = c I I R3 R4 wherein R1 to R10 can be independently selected from hydrogen; halides; alkyl, cycloalkyl or aryl groups, including derivatives thereof such as halogenated and sulphonated derivatives; or two R groups together can form a cyclic structure. Lz is preferably an arylene, alkylene or N, N-dialkyleneamine group, with the alkylene groups preferably having about eight or less carbon atoms. In the second step of the synthesis of the resin in which the latent amine functionality is reacted towards a resin, the latent primary amine compound is reacted with a resin having at least one group reactive with the functionality of the compound of latent primary amine. The resin used to form the latent amine resin can be any of a number of resins, including, without limitation, epoxy, acrylic, polyester, polyurethane, polyamide and polybutadiene resins. In a preferred embodiment, the resin having the latent amine functionality that can be represented by structure (Ib): O H H O I N CH2 - CH, N - CH2 - CH2 - N - C / \ L1 L1 (Ib) wherein at least one of the amine nitrogens is covalently bound to the resin and the other nitrogen is preferably a secondary amine (ie, linked to a hydrogen atom) or a derivative of a secondary amine (e.g., a urea group of the reaction of the secondary amine with an isocyanate functional compound). L1 is a bivalent linking group as defined for structure la. In a preferred embodiment, particularly when the coating composition is to be used as a primer, the resin has at least one epoxide group and is an epoxy resin, preferably a polyglycidyl ether. Preferred polyglycidyl ethers are polyglycidyl ethers of bisphenol A, bisphenol F, and similar polyphenols. Epoxy resins can be prepared, for example, by etherifying a polyphenol using an epihaiohydrin, such as epichlorohydrin, in the presence of alkali. In a preferred embodiment, the epoxy resins are extended with polyphenol, such as bisphenol A, or with polyamine. The polyepoxide compound can be modified or extended, for example by reaction of the glycidyl groups with a polyphenol such as bisphenol A or with a polyamine such as those sold by BASF AG of Germany under the tradename POLYAMIN and under the trade name Jeffaminet®) by Huntsman Co. of Houston, TX. Preferred epoxy resins have a weight average molecular weight, which can be determined by GPC, from at least 3000 and up to 6000. Epoxy equivalent weights can vary from 500 to 1900, and preferably from 800 to 1200. Novolac epoxies also they are suitable as a functional polyepoxide resin which is reacted with a latent primary amine compound to produce a crosslinkable latent primary amine resin of the invention. The novolak epoxy resin may be epoxy phenol novolak resins or epoxy cresol novolak resins having the formula II: wherein R-, is H or methyl, R can be H or a glycidyl group, with the proviso that on average at least two R groups per molecule are glycidyl groups, and n is from 0 to 12, preferably from 3 to 8. , and more preferably 3 or 4. The -novolac resin can also be an aromatic novolac bisphenol A resin, having any of the formula III or of formula IV wherein, for each formula, Rp can be H or a glycidyl group, with the proviso that on average at least two Rp groups per molecule are glycidyl groups, and m is 0 to 4, of -ference from 0 to 2. The Acrylic polymers are preferred for use in topcoat compositions, including topcoat or topcoat compositions. Acrylic polymers having at least one group reactive with the latent amine compound can be prepared from functional epoxide monomers, such as glycidylmethacrylate, or isocyanate-functional monomers, such as isocyanatoeti-1-methacrylate, isopropenyl isocyanate or eta-isopropene. -alpha, alpha-dimethylbenzene isocyanate. The monomers which have functional groups reactive with the latent anion compound are copolymerized with other monomers, such as esters and other derivatives of acrylic acid and methacrylic acid, butyl methacrylate, cyclohexyl methacrylate, hydroxyethyl acrylate, hydroxybutyl acrylate, 2-ethylhexyl acrylate, n-butyl acrylate, and / or other monomers that are known to be copolymerizable therewith such as vinyl esters, aromatic monomers, such as styrene, and so forth. The latent primary amine compound is reacted with the glycidyl or isocyanate groups of the acrylic resin. Another amine functionality can be incorporated into the acrylic polymers by copolymerization of an acrylic monomer containing tertiary amine or by reaction of a polyamine with one or more of the isocyanate or epoxide groups. The polyesters can also be used as the resin in the composition according to the invention. The polyesters can be prepared by the reaction of organic polycarboxylic acids (e.g., phthalic acid, hexahydrophthalic acid, adipic acid, malonic acid) or their anhydrides with organic polyols containing primary or secondary hydroxyl groups (e.g., ethylene glycol, butylene glycol, neopentyl glycol). The epoxide groups can be incorporated into polyesters by reacting a functional carboxylic acid polyester with a molar excess of a polyepoxide compound. The isocyanate groups can be incorporated into the polyesters by reacting a polyester functional hydroxyl with a molar excess of a polyisocyanate (preferably, a diisocyanate). The epoxide or isocyanate groups can then be reacted with the latent amine reaction product to introduce the latent primary amine functionality. The epoxy-modified polybutadiene, polyisoprene, amine-terminated nitrile butyl rubber, butadiene-acrylonitrile rubber, or other epoxy-modified rubber-based polymers can be used as the resin of the present invention. At least one functional group, eg, epoxide or isocyanate group, in the resin is reacted with a secondary amine of the reaction product product of cyclic anhydride-amine compound in order to introduce the latent amine functionality. The reaction can be carried out at temperatures, for example, of about 65-75 ° C. The reaction temperature is preferably lower than the temperature at which the latent amine compound would be expected to decompose to regenerate the primary amine functionality. If desired, other amine groups can be incorporated by reacting one or more reactive groups on the resin with a polyamine containing secondary and / or primary amines. In a preferred embodiment, one or more epoxide groups or a functional epoxide resin it is reacted with the latent amine compound. If desired, other latent amine groups can be incorporated by reacting one or more reactive groups on the resin with a compound comprising at least one primary amine group blocked by a ketimine. The ketimine will decompose at the temperatures at which the cyclic anhydride / amine reaction product decomposes to regenerate a primary amine that can be crosslinked by the carbonate curing agent. In a preferred embodiment for cathodic electrodeposition coatings, one or more epoxide groups in an epoxy resin are reacted with the latent amine compound and with a compound comprising a secondary amine group and at least one primary amine group bocheted by a ketimine. The ketimine will decompose at temperatures at which the cyclic anhydride / amine reaction product decomposes to regenerate a primary amine that can be crosslinked by the carbonate curing agent. When used in an electrodeposition coating composition, the ketimine will be hydrolysed during dispersion in water to regenerate a primary amine that can be sawn to provide dispersion stability and can be crosslinked by the carbonate curing agent.

The polyurethanes can also be used as the resin in the present invention. The polyurethanes are prepared by the reaction of a polyisocyanate and a polyol. Examples of useful polyisocyanates include hexamethylene diisocyanate, toluene diisocyanate, methyldiphenyldiisocyanate (MDI), isophorone diisocyanate, and biurets and isocyanurates of these diisocyanates. Examples of useful polyols include low molecular weight aliphatic polyols, polyester polyols, polyether polyols, fatty alcohols and the like. Aliphatic reagents are preferred for resins that will be incorporated in topcoat compositions. In the case of a polyurethane resin, the polyurethane can be synthesized with terminal isocyanate groups which can then be reacted with the secondary amine groups of the latent amine compound. Again, if desired, the primary amine functionality can be included by reaction of an isoclananate group of the polyurethane with a compound comprising a secondary amine group and at least one latent primary amine group blocked by a ketimine. when the resin having latent primary amine functionality is used in an electrocoating composition, the amount of primary amine versii the amount of latent primary amine provided by the anhydride / amine compound reaction product can be equilibrated to provide a sufficient concentration of crosslinkable groups for good curing without excessively high bath conductivities. The resins used according to the invention preferably have an equivalent weight of functional groups available for crosslinking, including primary amine groups and primary latent amine groups, of at least about 300 eq / g and preferably up to about 500 eq / g. The resins used according to the invention also preferably have an equivalent weight of groups available for salt, including primary amine groups, of at least about 1300 eq / g and preferably up to about 1500 eq / g. It may be advantageous to include other functional groups such as hydroxyl groups in any of the resins described above. These functional groups can serve as reaction sites for optional auxiliary crosslinkers such as aminoplast resins. Lower amounts of blocked isocyanate crosslinking agents, for example up to about 10%, preferably up to about% by weight based on the combined weight of the crosslinking agents and resin, can be included.

Incorporation of these groups are well known in the industry. When used in electrocoating coating compositions, the amine groups in the resin are at least partially salty, and can be completely salted, with an acid, such as acetic acid, lactic acid, or citric acid, to make a cationic resin in the resin. dispersion in an aqueous medium. The resin must carry a cationic charge to allow the resin to be electrodeposited on the cathode of an electrodeposition cell. In the case of an amine compound having more than about two secondary amines available for reaction with the resin, it may be desirable to reduce the number of secondary amine sites to two or less, for example, by reacting the excess of secondary amine groups before or during the direction of the latent amine compound with the resin. For example, excess secondary amine groups can be reacted with a monoisocyanate to form a compound substituted with urea. The compositions of the invention further include at least one compound having a plurality of carbonate groups. The carbonate compound may comprise cyclic carbonate groups having various ring sizes as are well known in the art, such as five-membered cyclic carbonate rings, six-membered cyclic carbonate rings, seven-membered cyclic carbonate rings, or fused ring systems containing the carbonate fraction -0-CO-0-characteristic. The cyclic carbonate compounds can be synthesized by any of several different approaches. One approach involves reacting an epoxy group containing compound with C02, preferably under pressure with a catalyst. Useful catalysts include any that activates an oxirane ring, such as quaternary tertiary amine salts (e.g., tetramethylammonium bromide), tin and / or phosphorus complex salts (e.g., (CH3) 3SnI, (CH3) 4PI). The epoxides can also be reacted with beta-butyrolactone in the presence of said catalysts. In another approach, a glycol, such as glycerin, can be reacted at temperatures of at least about 80 ° C (usually under reflux) with diethyl carbonate in the presence of a catalyst (e.g., potassium carbonate) to form a cyclic carbonate . Alternatively, a functional compound containing a ketal of a 1,2-diol having the structure: R it can be ring-opened with water at temperatures of at least 60 ° C, preferably with a vestigial amount of acid to form a 1,2-glycol. As an alternative to the reaction with diethyl carbonate, the glycols can reacting with phosgene in the presence of sodium hydroxide to form a cyclic carbonate. The five-membered cyclic carbonate rings can be formed from 1,2-glycols. The six-membered cyclic carbonate rings can be formed from 1, _ 1, 3-glycols. Molten rings can be formed, for example, by the reaction of phenol with phosgene to form phenylene carbonate. Cyclic carbonates typically have rings of 5-6 members. Five-member rings are preferred, due to their ease of _n synthesis and to a greater degree of commercial availability. In a preferred embodiment, the compounds useful as the carbonate crosslinking agent are prepared by reaction of a polyepoxide with carbon dioxide to convert the epoxy groups to cyclic carbonate groups. Polyepoxides useful for preparing Carbonate crosslinking agents include, for example, any of the functional epoxy resins described above. Preferred are monomeric or oligomeric polyepoxide materials. Among the preferred compounds for synthesis of the curing agents of the invention are glycidyl ethers of polyols and glycidyl esters of polyacids. The polyepoxides can be reacted with carbon dioxide, as described above, to form the carbonate crosslinker cyclical. The polyepoxide compound used to make the crosslinker can be any aliphatic or aromatic compound having at least two epoxide groups per molecule on average, and it is preferred to use compounds ,, - which have from about 2 to about 4 epoxide groups per molecule on average. Examples of useful polyepoxide compounds include, without limitation, polyglycidyl ethers and esters, epoxy novolak resins, and functional epoxy acrylics. In particular, 2Q The polyepoxide compound can be the polyglycidyl ether of aliphatic or aromatic polyols such as 1,4-butanediol, neopentyl glycol, diclohexane dimethanol, diethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 2-, 2,4-trimethyl-1,3. -pentanediol, 1,6-hexanediol, Z trimethylolpropanol, trimethyloletanol, glycerol, bisphenol A (4,4'-isopropylidenediphenyl), hydroquinone, Z , 4'-biphenol, 2, 2'-bisphenol, 4, 4'-dihydroxybenzophenone, 1,5-dihydroxynaphylene, novolac polyphenols, resorcinol, and the like. In principle, the glycidyl ether of any polyol can be used. The polyepoxide compound is preferably a polyglycidyl ether of a polyphenol, and particularly preferably, is the diglycidyl ether of bisphenol A. The polyepoxide compound could also be extended, as described above. The polyepoxide could be an ot-novolac epoxy resin, including epoxy phenol novolak resins, epoxy cresol novolak resins, or aromatic novolak bisphenol A resins, as described above. even though not all oxirane groups of the novolak resin should be converted to carbonate groups, it is preferred that all oxirane groups are converted to carbonate groups. Polyglycidyl esters of polyacids are also useful in the present invention. Preferably, the polyglycidyl ester is the ester of a compound having two to about four carboxylic acid groups. These esters include, without limitation, the diglycidyl esters of terephthalic acid.

Z - 32 - succinic acid, glutaric acid, 2,6-naphthylene dicarboxylic acid, and oxalic acid. The scale of equivalent epoxide weights useful for the polyepoxide compound is broad, but in general it is preferred that the epoxide equivalent weight should be selected to provide a sufficient crosslink density during curing to make a film that is strong and durable. In a preferred embodiment, the equivalent weight of epoxide is from about 50 to about 500. Cyclic carbonates with average functionality greater than about three are also contemplated, and in many cases, are preferred. Compounds having higher carbonate functionality can be obtained, for example, by reacting one mole of a diisocyanate such as isophorone diisocyanate with two moles of a polyol such as trimethylolpropane to produce a tetrafunctional alcohol, which can be epoxidized with an epihaiohydrin to produce a tetrafunctional polyepoxide. The tetrafunctional polyepoxide, in turn, can be reacted with carbon dioxide to form a tetrafunctional cyclic carbonate. Other polyepoxides of higher functionality, e.g., tetrakis-4-glycidyloxy-phenyl) ethane or functional epoxy novolac epoxies can also be made se 33 react with C02 to form polycyclic carbonates. Functional still substantially 07 can be used higher, such as polymeric polyepoxides (e.g., functional epoxy acrylic resins) converted into polymeric cyclic carbonate compounds, for which functionality will be a function of the CT equivalent weight of the polymer. A preferred class of cyclic carbonate compounds useful as the carbonate resin or crosslinking agent of the invention are compounds having an average of at least about four cyclic carbonate groups per molecule. In another preferred embodiment, each cyclic carbonate group is attached to an ether segment, for example a segment having at least one propylene oxide unit. These cyclic carbonate compounds can be prepared by reacting a polyether polyol with an epihaiohydrin to convert the hydroxyl groups to the epoxy groups. The polyether polyols can be based on simple polyols having three or four hydroxyl groups, or mixtures of said compounds. Illustrative examples, without limitation, include trimethylolpropane, pentaerythritol, 1,2,6-trihydroxyhexane, xylose, adonitol and so on. The epoxy groups can then be converted HE. 3. 4 in cyclic carbonate groups by reaction with COz. Examples of useful polyol polyols include Q Z polypropylene glycols based on pentaerythritol and having up to 7 polyether units in total. A route for the preparation of cyclic ring carbonates can be represented by the formula: i 0 ot wherein p and O or a positive integer (preferably 0, 1, or 2) and R1, R2 and R3 are each independently H or an organic radical with the proviso that at least one of R1, R2 and R3 is a radical organic to which other cyclic carbonate groups or a group capable of binding to an organic radical to which other cyclic carbonate groups can be linked can be linked. In a preferred embodiment of the invention, the carbonate compounds are represented by the formula: 2 35 wherein R represents a polyvalent organic radical, and preferably a trivalent or tetravalent organic radical; Z represents the carbon atoms necessary to complete a five, six or seven membered cyclic carbonate ring, substituted or unsubstituted; and m represents an integer of at least 2, ot In another preferred embodiment of the invention, the carbonate compounds are represented by the formula: wherein R represents a polyvalent organic radical, and preferably a trivalent or tetravalent organic radical; and n is at least about two, more preferably at least about 3, and n is preferably up to about eight, more preferably up to about 6, and even more preferably up to about 4.

Z 36 -. 36 - Coating compositions used in the practice of the present invention in which the latent amine-functional compound has a structure preferably are powder coating compositions or solvent-borne coating compositions. The coating composition can also be a powder coating composition or a solvent-borne coating composition when the latent amine-functional material is a resin having a structure (Ib) attached thereto. The concentration of the resinous products and carbonate crosslinkers by weight in the compositions, based on the total resin solids, depends on the particular application and selected materials and can be determined by direct testing. Preferably, the coating compositions of the invention include at least about 40% by weight of the latent amine-functional resin, preferably up to about 67% by weight of the latent amine-functional resin, based on the total resin solids. . The coating compositions also include at least about 15% by weight of the functional carbonate crosslinker, preferably up to about 40% by weight of the functional carbonate crosslinker, based on the total resin solids.

Z 37 -. 37 - The above components are mixed uniformly, optionally together with other ingredients or z to form a coating composition. Other suitable ingredients include organic solvents, antioxidants, UV absorbers, light stabilizers, pigments, fillers, catalysts, rheology control agents, adhesion promoters and so on. In general, a solvent can be used to prepare a composition that is in a substantially liquid state. Depending on the solubility characteristics of the various coating components, a solvent can be selected from ketones, esters, glycol ethers and esters of glycol ethers, aprotic amides, aromatic solvents, and other solvents commonly used for compositions of coating. c The coating composition of the invention may also contain one or more pigments. The pigments can be inorganic pigments, including metal oxides, chromates, molybdates, phosphates and silicates. Examples of inorganic pigments that could be used include no limit, titanium dioxide, barium sulfate, carbon black, ocher, siena, hematite, limonite, red iron oxide, transparent red iron oxide, black iron oxide, brown iron, green S2 38 chromium oxide, strontium chromate, zinc phosphate, silicas such as fumed silica, talc, barite, 03 Lead ferrocyanide and lead silicate, Organic pigments can also be used. Examples of useful organic pigments include, without limit, non-metallized and metallized azo reds, quinacridone reds and violets, perylene reds, copper phthalocyanine blues and greens, carbazole violet, yellow monoaryl and yellow diarylurides, benzimidazolone yellows , tolyl orange, naphthol orange and the like. Flake pigments such as metallic flake pigments and mica pigments are included when a metal or pearl effect is desired. Preferred pigments depend on the desired color of the coating. When the applied coating is a primer, extenders such as clay and anti-corrosion pigments are commonly included. The pigments can be dispersed using a grinding resin, or preferably, a pigment dispersant, using methods well known in the art. The coating compositions of the invention can be thermally cured at a sufficiently high temperature to generate primary amine groups from the latent primary amine groups. Usually, the coating will cure at a temperature at least about 80aC, preferably at least about 100SC, and particularly preferably at least about 120SC. The curing time will vary depending on the particular components used, and the physical parameters such as the thickness of the layers. Typical cure times vary from 15 to 60 minutes. Unlike curing systems with blocked isocyanate carbonate compounds or alkylated melamine resins, the curing chemistry of the present invention does not involve the release of a volatile organic byproduct. In this way, the inventive compositions offer significant advantages to produce lower emissions and provide superior conversion of paint solids into cured coating. The compositions of the invention are typically applied at a thickness sufficient to produce a cured coating layer that is at least about 0.3 microns thick and preferably less than 5 microns thick. When the compositions of the invention are used as primers, the thickness of the cured coatings should typically be from about 0.5 to about 1.5 microns thick. When the compositions of the invention are used as base coatings, the thickness of the cured coatings should typically be from about 0.4 to about 1.3 microns thick. When the compositions of the invention are used as one of top coating coatings or as clear coatings, the thickness of the cured coatings should typically be from about 0.8 to about 2.5 microns thick. The coating preparations according to the invention can be used to coat various kinds of substrates using any of a number of processes known to those skilled in the art, such as spraying, roller coating, and coil coating methods and so forth. Preferably, the substrate is a plastic or metallic substrate. In a preferred embodiment, the substrate is a car component such as a body panel. The compositions of the invention are preferably used as exterior automotive coatings. The substrate may have one or more coating layers before the present compositions are applied, particularly when the composition according to the present invention is applied as a topcoat. When the coating compositions of the * invention are applied as a primer layer to a substrate, a pigmented resin coating and optionally a clear coating layer can be applied over the primer layer. In automotive applications, the pigmented resin layer is often referred to as a base coat or color coat when a clear coat layer is to be applied thereon, or a top coat when the pigmented resin coat is to be the coat. external The resin in the pigmented resin layer may be a number of resins known in the art. For example, the resin can be an acrylic, a polyurethane or a polyester. Typical pigmented resin coating formulations are described in U.S. Pat. 4,791,168, 4,414,357 and 4,546,046, the teachings of which are incorporated herein by reference. In a preferred embodiment, the resin is an acrylic resin modified with epsilon-caprolactone, as described in the U.S. Patent. 4,720,528, the disclosure of which is incorporated herein by reference. The pigmented resin can be cured by any of the known mechanisms and carbonate compounds, such as a melamine polyol reaction (e.g., melamine curing of a hydroxy functional acrylic resin).

Other pigmented basecoat compositions for these composite coatings are well known in the art, and do not require detailed explanation herein. Polymers known in the art as useful in basecoat compositions include acrylics, vinyls, polyurethanes, polycarbonates, polyesters, alkyds and polysiloxanes. Preferred polymers include acrylics and polyurethanes. The base coating polymers are preferably crosslinkable, and thus comprise one or more types of crosslinkable functional groups. These groups include, for example, hydroxy, isocyanate, amine, epoxy, acid, anhydride, acrylate, vinyl, silane and acetoacetate groups. These groups can be masked or blocked in such a way that they are unblocked and available for the crosslinking reaction under the desired curing conditions, usually elevated temperatures. Preferred crosslinkable functional groups include hydroxy functional groups and amino functional groups. The basecoat polymers may be self-crosslinkable, or they may require a separate carbonate compound that is reactive with the functional groups of the polymer. When the polymer comprises hydroxy functional groups, for example, the compound of carbonate can be selected from blocked aminoplast resins, isocyanates and isocyanates (including isocyanurates), and functional acid or anhydride crosslinking agents. Preferably, a transparent coating containing a vehicle having a carbamate functionality, such as, for example, a clear coating in accordance with US Pat. No. 5,474,811, is applied wet-on-wet over a layer of a basecoating composition. The coatings applied on the electrocoat coating layer of the invention are applied and, preferably, cross-linked according to methods well known in the art. The coating having latent amine functionality can also be an electrodepositing, or electrodepositable coating composition. The electrodepositable coating compositions used in the practice of the present invention are dispersed in aqueous medium. The term "dispersion" as used in the context of the present invention refers to a translucent or opaque two-phase aqueous resinous system in which the resin is believed to be the dispersed or emulsified phase and water the continuous phase, even when a minor portion of the resin can still be dissolved in the continuous phase. The diameter of particle size average of the resinous phase is usually at least about 0.1 micron; the average particle size diameter can be up to about 10 microns, but preferably it is less than about 5 microns. The concentration of the resinous products by weight in the aqueous medium, in general, is not critical, but ordinarily the main portion of the aqueous dispersion is water. The aqueous dispersion usually contains at least about 3 percent, preferably at least about 10 percent, by weight resin solids; and the dispersion may contain up to about 50 percent, preferably up to about 35 percent, by weight resin solids. The aqueous resin concentrates to be further diluted with water can generally be at least about 10% by total solids weight and can be up to about 30 percent by weight total solids. In general, sufficient water is added so that the dispersion has a solids content of more than about 20% by weight, preferably more than about 30% by weight. The above components are uniformly dispersed in an aqueous medium. Usually, the main resin and the crosslinking agent are mixed together before the resins are dispersed in the water. He Salty acid can be mixed with the resins, mixed with the water, or both, before the resins are added to the water. The acid is used in an amount sufficient to neutralize enough of the amine groups of the main resin to impart dispersibility in water to the resin. The resin must be neutralized to a sufficient degree to prevent premature reaction of any primary amine groups with the cyclic carbonate groups in the crosslinking agent adversely affecting the properties of the coating bath (typically at least 80%, more preferably 90%). -100%). Examples of useful acids include phosphoric acid, acetic acid, propionic acid, citric acid and lactic acid. In addition to water, the aqueous medium of an electrocoating composition may also contain a coalescence solvent. Useful coalescing solvents include hydrocarbons, alcohols, esters, ethers and ketones. Specific coalescing solvents include ethylene glycol monobutyl and monohexyl ethers and propylene glycol phenyl ether, ethylene glycol monoalkyl ethers such as the monomethyl, monoethyl, monopropyl and monobutyl ethers of ethylene glycol; dialkyl ethers of ethylene glycol such as ethylene glycol dimethyl ether; or alcohol diacetone. A small amount of a water-immiscible organic solvent, such as xylene, toluene, methyl isobutyl ketone or 2-ethylhexanol, may be added to the mixture of water and the water-miscible organic solvent. The amount of the coalescing solvent is not unduly critical and is generally between about 0 to 15 weight percent, preferably about 0.5 to 5 weight percent, based on the total weight of the resin solids. The electrodeposition coating composition may additionally contain conventional pigments such as titanium dioxide, ferric oxide, carbon black, aluminum silicate, barium sulfate precipitate, aluminum phosphomolybdate, strontium chromate, basic lead silicon or lead chromate. The pigments can be dispersed using a ground resin or, preferably, a pigment dispersant as described by Carpenter et al. in the Patents of E.U.A. Nos. 5,527,614 and 5,536,776, incorporated herein by reference. The weight ratio of pigment to resin in the electrocoat bath can be important and preferably should be less than 50: 100, more preferably less than 40: 100, and usually about 10 to 30: 100. The weight ratios of pigment to resin solids Higher concentrations have been found to adversely affect coalescence and flow. The electrodeposition coating compositions may contain optional ingredients such as wetting agents, surfactants, defoamers, antioxidants, UV absorbers, light stabilizers, and so forth. Examples of surfactants and wetting agents include alkyl imidazolines such as those available from Ciba-Geigy Industrial Chemicals such as Amine C (R), acetylenic alcohols available from Air Product-s and Chemicals such as Surfynol (R) 104. These optional ingredients, when present, they constitute from about 0 to 20 weight percent based on the resin solids. Plasticizers can be included, for example, to promote the flow and coalescence of the film. Preferred plasticizers include polyether products, such as poly (ethylene oxide) or poly (propylene oxide), with phenolic compounds such as nonyl phenols, p-cresol or bisphenol A. Plasticizers are usually included from about 0 to 15 weight percent resin solids. The electrodeposition coating composition must have an electroconductivity of at least approximately 1200 icroohms. While higher conductivities are possible, the conductivity should preferably be 3000 microohms or less, but preferably about 2000 microohms or less. When the conductivity is too low, it is difficult to obtain a film thickness having the desired protective and other functions. Conversely, if the composition is too conductive, problems such as dissolution of the coated or film-breaking film during deposition may arise. The electrodeposition of the coating preparations according to the invention can be carried out by any of a number of processes known to those skilled in the art. The deposition can be carried out on all electrically conductive substrates, for example metal, such as steel, copper, aluminum and the like. The electrodeposition coating composition used in this invention can be applied to a conductive substrate at a dry film thickness of 15 to 35 microns. After application, the coating can be cured at a sufficiently high temperature to generate the primary amine groups of the primary amine groups latent. Usually, the coating will cure at a temperature of at least about 80aC, preferably at least about 120aC. The curing time will vary depending on the particular components used, and the physical parameters such as the thickness of the layers, however, the typical curing types vary from 15 to 60 minutes. Unlike curing systems with blocked isocyanate crosslinkers or alkylated melamine resins, the curing chemistry of the present invention does not involve the release of a volatile organic byproduct. In this way, the inventive compositions offer the significant advantages of producing lower emissions and of providing a higher conversion of bath solids to the cured coating. According to the invention, a pigmented resin coating and optionally a clear coating layer can be applied on the electrocoat coating layer, as described above. The electrocoat primer layer may optionally be first coated with a second primer layer by spraying. The invention is further described in the next example. The example is merely illustrative and in no way limits the scope of the invention as described and claimed. All parts are by weight unless noted otherwise.

Synthesis 1: Preparation of Latent Amine Compound A latent amine compound was prepared according to Example 2 of Moran, Jr. , and col .. Patent of E.U.A. No. 3,639,657. The product had a number average molecular weight of 326 and a weight average molecular weight of 4973, as measured by GPC against a polystyrene, thereby having a polydispersity of about 15.2. The amine equivalent weight was determined by titration with 0.1N HCl which is 7.5 mdq, with base per gram of resin solids.

Synthesis 2: Preparation of Latent Amine Compound A 1 liter glass flask was charged with 340 grams of fresh diethylenetriamine. Diethylenetriamine was heated to about 90 ° C under a blanket of nitrogen. A total of 122.3 grams of phthalic anhydride (ACS grade,> 99.5%) was added over a period of about 20 minutes. The reaction mixture was maintained at 100aC for two hours. The reaction mixture then it was vacuum cleaned. The residue (165.5 grams) was milled, washed with three 350 ml portions of THF, then dried in the oven. The product (approximately 150 grams) had a number average molecular weight of 143 and a weight average molecular weight of 154, as measured by GPC. The amine equivalent weight was determined by titration which is 164 eq / gram.

Synthesis 3: Preparation of Carbonate Compound A stainless steel pressure reactor was charged with 170.0 grams of tetraglycidyl ether (reaction product of pentaerythritol, propylene oxide and epichlorohydrin having an epoxide weight of 169.5) and 5.0 grams of bromide of tetrabutylammonium. The contents of the reactor were heated to 105 aC under a constant stream of carbon dioxide gas. The system was then pressurized with carbon dioxide at a pressure of 8.44 kg / cm 2 and this pressure was maintained by the addition of C02 as needed throughout the remainder of the reaction. The reaction mixture was kept under these conditions for 7 hours, at which time the heat was turned off and the reaction mixture was allowed to cool for 14 hours. Analysis by titration of epoxide groups indicated that the reaction was complete.

Example 1: Preparation of Coating Composition The latent amine compound of Synthesis 2 was reduced to 50% solids in methanol. A 7.2 gram portion of the reduced latent amine compound was mixed with 5.0 grams of the carbonate crosslinker of Synthesis 3 (equivalent ratio of 1: 1). The mixture was removed on a glass plate in a wet film thickness of 4 microns. The methanol was allowed to evaporate for 5 minutes at room temperature, and then the removed was baked for 30 minutes at 166 aC. The cured film was a light yellow and had a resistance to MEK solvent of 50 rubs.

Synthesis 4: Preparation of Latent Amine Resin An appropriate reaction vessel was charged with 128.6 grams of the diglycidyl ether of bisphenol A, 39.0 grams of bisphenol A, and 10.0 grams of xylene. The vessel was heated to 125 ° C and 0.2 grams of triphenylphosphine catalyst was added. The reaction mixture was maintained at 150 ° C until a weight per epoxide of 494 grams / equivalent was reached. The resin product was then reduced with an addition of 117.0 grams of butyl glycol. The temperature of the resin was reduced to 85aC, at which temperature 43.4 grams of diethylenetriamine diketimine (70% by weight) were added. methyl isobutyl ketone). Then, 61.5 grams of the latent amine compound of Synthesis 2 was added. The temperature was maintained at about 80aC for three hours. The resin was then reduced with 50 grams of xylene and 50 grams of butyl glycol.

Example 2: Preparation of Coating Composition A 5.0 gram portion of the latent amine resin of Synthesis 4 was mixed with 2.4 grams of the carbonate crosslinker of Synthesis 3. The resulting composition was carried in a glass as a wet film of 4.0 microns thick and then baked for 30 minutes at 110 aC. The resulting film was transparent and had a MEK resistance of 50 rubs.

Synthesis 5: Preparation of Latent Amine Resin A suitable reaction vessel was charged with 250.7 grams of diglycidyl ether of bisphenol A, 76.0 grams of bisphenol A, and 17.2 grams of xylene. The vessel was heated to 125 ° C and 0.25 grams of triphenylphosphine catalyst were added. The reaction mixture is maintained at 150 aC until a weight per epoxide of about 500 grams / equivalent is reached. The resin product is then reduced with an addition of 24.0 grams of ethylene glycol monobutyl ether, 36.8 grams of xylene, 100 grams of isobutanol and cooled to about 50SC. Then, 177 grams of the latent amine compound of Synthesis 2 is added. The temperature is maintained at around 60 ° C for three hours.

Synthesis 6: Preparation of Carbonate Reticulator A 5 liter stainless steel pressure reactor was charged with 398.0 grams of tetraglycidyl ether (reaction product of pentaerythritol ---- propylene oxide, and epichlorohydrin having a weight per epoxide of 169.5). A total of 2.5 grams of tetrabutylammonium bromide was added. The contents of the reactor were heated to 100SC. after a short purge of the reactor with a constant stream of carbon dioxide gas, the system was sealed and carbon dioxide gas was introduced at a pressure of 8 atmospheres. The reaction mixture was maintained under these conditions for 14 sheets, at which time analysis by infrared spectroscopy indicated that the reaction was complete. The resin product was 99.8% non-volatile and had a viscosity of 6800 centipoise.

Example 3: Preparation of Emulsion of Electrocoating A 1 liter glass flask was charged with a mixture of 256.5 grams of the diglycidyl ether of bisphenol A, 58.6 grams of bisphenol A, 56.1 grams of dodecylphenol, and 20.3 grams of xylene. The mixture was heated to 125 ° C, and then 0.9 grams of dimethylbenzylamine was added. An exothermic reaction raised the temperature of the reaction mixture to 168SC. The mixture was then cooled, and an additional 0.4 grams of dimethylbenzylamine was added. The reaction mixture was maintained at 133 ° C for 3 hours, at which time the weight per epoxide was determined to be 950 grams of polymer per equivalent epoxide. The reaction temperature was reduced to 10aC, and 18.9 grams of propoxylated p-cresol plasticizer (Synfac 8100, available from Milliken Chemical, Spartanburg, SC), 15.4 grams of butyl glycol were added. At 96 [deg.] C., 36.7 grams of diethylenetriamine diketimine (70% solution in methyl isobutanol) was added. The reaction mixture was cooled to 75 [deg.] C. for one hour, and then 92 grams of the latent amine compound of Synthesis 2 was added. After 15 minutes of agitation, 65.3 grams of isobutanol, 72.5 grams of butyl glycol, 1.5 grams of Surgynol 104 BC (available from Air Products Co., Állentown, PA), and 2.0 grams of an anti-crater agent were added. they added. The temperature was maintained at 75 aC for 2 hours. The resulting resin solution was 72% solids. An appropriate container was charged with 500.0 grams of the resin solution (60aC). The resin was mixed for five minutes with 17.5 grams of lactic acid. Then, 145 grams of the carbonate crosslinker of Synthesis 6 was added and the mixing was confined for fifteen minutes. The mixture was emulsified by the gradual addition of 2242 grams of deionized water and 21.8 grams of 86% lactic acid with good agitation. The resulting emulsion was 17% solids and had a particle size of 134 nm.

The job 4j Preparation d? Emulsion of Electrocoating A 1 liter flask was charged with a mixture of 64.3 grams of the diglycidyl ether of bisphenol A, 19.5 grams of bisphenol A, and 5.0 grams of xylene. The mixture was heated to 125 aC, and then 0.1 gram of triphenylphosphine was added. An exothermic reaction raised the temperature of the reaction mixture to 164aC. The mixture was then cooled and maintained at 150 ° C for one hour, at which time the weight per epoxide was determined to be 490 grams of polymer per equivalent epoxide. The The reaction temperature was reduced to 145 ° C., and 58.5 grams of butyl glycol were added. At 851C, 21.7 grams of diethylenetriamine diketimine (70% solution in methyl isobutyl ketone) was added. The reaction mixture maintained at the temperature for about one hour, and then 37.7 grams of the latent amine compound of Synthesis 2 was added. The temperature was maintained at 85-90sC for about four hours. The resulting resin solution was 60% solids. A suitable vessel was charged with 170.0 grams of the resin solution together with 33.4 grams of the carbonate crosslinker from Synthesis 6. Then 3.6 grams of acetic acid were added and the mixture was emulsified by the gradual addition of 356.7 grams of water Deionized with good agitation. The resulting emulsion was 18% solids and had a particle size of 154 nm. An electrocoating bath is prepared by adding a pigment paste (60% non-volatile by weight, ratio of pigment to binder 3.5, with Ti02, carbon black and a clay extender) to the emulsion, and then reducing the pigmented emulsion to the final desired nonvolatile by adding deionized water. The coating is electrodeposited on the metal substrate (cathode) at approximately 100 volts to a thickness of approximately 0.5 microns. The deposited film is baked at 177aC for about twenty minutes to crosslink the film to an insoluble coating film. The invention has been described in detail with reference to the preferred embodiments thereof. It should be understood, however, that variations and modifications may be made within the spirit and scope of the invention and the following claims.

Claims (30)

CLAIMS:

1. - A coating composition comprising: (a) a compound with latent primary amine functionality comprising the latent amine reaction product of: (i) a cyclic anhydride and (ii) an amine compound comprising two primary amine groups and a secondary amine group; and (b) a compound comprising a plurality of cyclic carbonate groups.

2, - A coating composition comprising: (a) a latent functional amine resin comprising the reaction product of: (i) a resin having a functional group reactive with a secondary amine, and (ii) a product of latent amine reaction of (A) a cyclic anhydride and (B) an amine compound comprising two primary amine groups and a secondary amine group; Y (b) a compound comprising a plurality of cyclic carbonate groups.

3. A coating composition comprising, in an aqueous medium; (a) a cationic resin having latent amine functionality, comprising the reaction product of: (i) a resin having a functional group with a secondary amine and (ii) a latent amine reaction product of (A) a cyclic anhydride and (B) an amine compound comprising two primary amine groups and a secondary amine group; and (b) a compound comprising a plurality of cyclic carbonate groups.

4. A coating composition according to claim 1, wherein the compound (b) is a carbonated polyepoxide resin.

5. A coating composition according to claim 2 or claim 3, wherein the resin (a) (i) is a polyepoxide resin.

6. A coating composition according to claim 4 or claim 5, wherein the polyepoxide resin is selected from the group consisting of epoxy resins, acrylic resins and mixtures thereof.

7. A coating composition according to claim 5, wherein the resin (a) (i) is a polyepoxide formed by reacting an excess of a polyglycidyl ether of a polyphenol with an extender compound having at least two groups epoxide reagents.

8. A coating composition according to claim 6, wherein the polyepoxide resin is an epoxy resin based on bisphenol A.

9. A coating composition according to claim 7, wherein the extender compound is selects from the group consisting of alkoxypolyamines, polyphenols and mixtures thereof.

10. A coating composition according to claim 4, wherein the polyepoxide resin is the reaction product of polyglycidyl ether of a polyol, an alkylene oxide, and epichlorohydrin.

11. A coating composition according to any of claims 1-3, wherein the latent amine reaction product has a polydispersity of about 3 or less.

12. A coating composition according to any of claims 1-3, wherein the latent amine reaction product has a polydispersity of about 1.1 or less.

13. A coating composition according to any of claims 1-3, wherein the latent amine reaction product has a polydispersity of about 1.05 or less.

14. A coating composition according to any of claims 1-3, wherein the latent amine reaction product is formed by reacting a molar excess of the amine compound with the cyclic anhydride.

15. A coating composition according to claim 14, wherein there is a ratio of at least about four moles of amine compound per mole of cyclic anhydride.

16. A coating composition according to any of claims 1-3, wherein the cyclic anhydride is selected from the group consisting of phthalic anhydride compounds, hydrogenated phthalic anhydride compounds, succinic anhydride compounds, and compounds of maleic anhydride,

17. - A coating composition according to any of claims 1-3, wherein the amine compound is a polyalkylene polyamine.

18. A coating composition according to claim 1, wherein the amine compound is an alpha, omega-alkylenediamine.

19 - A coating composition according to any of claims 1-3, wherein the latent amine reaction product is the reaction product of a ratio of at least about four moles of diethylenetriamine per mole of phthalic anhydride.

20. A coating composition according to claim 3, wherein the cationic resin (a) comprises at least partially salted primary amine groups.

21. A coating composition according to claim 20, wherein the cationic resin (a) is the reaction product of a resin (a) (i) having a plurality of functional groups reactive with a secondary amine with the reaction product of latent amine (a) (ii) and (a) (iii) a compound comprising a secondary amine group and at least one ketimine group.

22. - A coating composition according to claim 2, wherein the latent functional amine resin (a) is the reaction product of a resin (a) (i) having a plurality of functional groups reactive with a secondary amine with the reaction product of latent amine (a) (ii) and (a) (iii) a compound comprising a secondary amine group and at least one ketimine group.

23. A coating composition according to any of claims 1-3, wherein the compound (b) has at least about three cyclic carbonate groups per molecule, on average.

24. A coating composition comprising (a) a compound having the structure 0HHO C-N-L2-N-C \ L1 L1 \ / C-N-L2- -C II II li OHHO where L1 is a bivalent linking group in which the bond valences are two adjacent carbon atoms, and in addition where L2 is selected from the group consisting of arylene, alkylene and N, N'-dialkyleneamine groups and (b) a compound comprising a plurality of cyclic carbonate groups.

25. A coating composition comprising: (a) a resin comprising a structure / C - N - CH2 - CH2 - - CH2 - N - C | l I I II O H H O wherein at least one of the amine nitrogens is covalently linked to the resin, and further wherein L is a bivalent linking group in which the bond valences are on two adjacent carbon atoms; and (b) a compound comprising a plurality of cyclic carbonate groups.

26. A coating composition comprising, in an aqueous medium, (a) a cationic resin comprising a structure O H H O - '- CH2 -CH, - N - CH2 - CH2 - N - C / / N - N - CH2 - CH2 - N - CH2 - CH2 - N - C II I I 1 II O H I H O wherein at least one of the amine nitrogens is covalently linked to the main resin, and further wherein L is a bivalent linking group in which the bond valences are two adjacent carbon atoms; And (b) a compound comprising a plurality of cyclic carbonate groups.

27. A substrate having therein a coating derived from a composition according to any of claims 1-26.

28.- A method of coating a conductive substrate, comprising the steps of: (a) providing an aqueous coating composition comprising a cationic resin having latent primary amine functionality and a curing agent having a plurality of groups of cyclic carbonate, wherein the functionality of latent primary amine is obtained by reacting (i) a cyclic anhydride and (ii) an amine compound comprising two primary amine groups and a secondary amine group; (b) immersing a conductive substrate in the electrodeposition curing composition; and (c) applying an electric current potential between an anode and the conductive substrate to deposit a coating layer to the conductive substrate.

29. A method according to claim 28, wherein the cationic resin is an epoxy resin.

30. A method according to claim 28, wherein the reaction product of (a) (i) and (a) (ii) has a polydispersity of about 1.1 or less. 31.- A cationic resin formed by the process comprising the steps of: (a) reacting a cyclic anhydride and an amine compound comprising two primary amine groups and a secondary amine group to form a latent amine compound; (b) reacting the latent amine compound with a resin having at least one group reactive with secondary amine functionality; Y (c) salt the resin with an acid.