CA1189995A - Resinous compositions curable through a transesterification curing mechanism - Google Patents

Abstract

Abstract of the Disclosure Coating compositions comprising a polymeric polyol with a poly-aster crosslinking agent having at least two substituted ester groups per molecule are disclosed. The substituents are selected from the class con-sisting of beta-alkoxyester groups, beta-ester groups, beta-amido groups, gamma-hydroxy groups, gamma-ester groups and delta-hydroxy groups. The compositions, when applied to a substrate and cured in the presence of a transesterification catalyst, give solvent-resistant coatings.

Description

US

Background of the Invention Field of the Invention: The present invention relates to heat-curable resinous coating compositions and to the use of these coating come positions in cat ionic electrode position. More particularly, the present invention relates to resinous coating compositions which cure through a transesterification reaction.
Brief Description of the Prior Art: US. Patent 3,937,679 disk closes cat ionic heat-curable resinous coating compositions such as hydroxyl group-containing polymers in combination with aminoplast resin curing agents.
These compositions can be used in an electrode position process where they coat out on the cathode, and when cured, produce coatings with excellent properties. Coating compositions using aminoplast cure best in an acidic environment. However, the deposit on the cathode is basic and high curing temperatures must be used to overcome the unfavorable curing environment.
US. Patent 4,101,486 is similar to US. 3,937,679 in that it discloses cat ionic electrode position of hydroxyl group containing polymers, however, the curing agent is a blocked isocyanate. Coating compositions using blocked isocyanates cure very well at relatively low temperatures in a basic environment and are today widely used in industrial cat ionic electrode position. Examples of cat ionic elertrodepositable compositions which are used industrially ore those described in US. Patents 4,031,050 and 4,190,567 and DYES 2,75~,255. Although used extensively throughout the electrode position industry, blocked isocyanate-containing compositions are undesirable from the point of view of the isocyanate, some of which are undesirable to handle.

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1 European Patent Application 0012463 discloses thermosetting resinous coating compositions which cure through a transesterification reaction. The resinous binder of the coating composition comprises a hydroxyl-containing polymer and a cross linking agent which is a polyester containing two or more beta-hydroxyester groups per molecule. The coating composition can be made cat ionic and used for electrode position.
It is known in the art that esters containing beta-hydroxyalkyl groups transesterify very quickly. See, for example, J P T. THEM. 312 z~c~ e (1970), 660-668. However, European Patent Application 0012463~discloses that polyesters which do not contain beta-hydroxyester groups but rather simple ester groups such as methyl esters or bottle esters do not trays-esterify as readily and are too sluggish to effect sufficient cross linking at acceptable conditions.
Surprisingly, it has been found that coating compositions comprise in hydroxyl group-containing polymers and a polyester crosslink1ng agent which do not contain beta-hydroxyester groups can be cured quite effectively.
It is an object of the invention to provide heat-curable coating compositions which can be cured quite effectively forming solvent-resistant coatings.

Summary of the Invention In accordance with this invention, a coating composition which is heat curable to give a solvent-resistant coating is provided. The coating composition comprises as the resinous binder:
(A) a polymeric polyol, (B) a polyester cross linking agent having at least two substituted ester groups per molecule, and (C) a transesterification catalyst.

1 The substituents to the ester group are selected from the class consisting of beta-alkoxyester groups, beta-ester groups, bottomed groups, gamma-hydroxy groups, gamma-ester groups and delta-hydroxy groups.
it The coating compositions oan/b~ made cat ionic in character such as by using a polymeric polyol which contains cat ionic salt groups, the resinous binder dispersed in water and the aqueous dispersion used in a method of cat ionic electrode position.

Detailed Description The polymeric polyol component of the coating compositions can be selected from a wide variety of hydroxyl group-containing polymers such as alkyd resins, polyester resins, hydroxyl group-containing acrylic polymers, hydroxyl group-containing epoxy resins and hydroxyl group-containing resins which are derived from epoxy resins such as polyepoxide-amine adduces.
The molecular weights of the polymeric polyols can vary over a wide range depending upon their type and on whether the coating composition is organic solvent based or aqueous based and also on the desired perform-ante characteristics of the coating. Polyester, epoxy and alkyd resins can have molecular weights as low as about 500 and as high as about 10,000, preferably the molecular weights are usually in the range of about 1,000 to 5,000; the molecular weights being on a weight average basis relative to polystyrene, as determined by gel permeation chromatography. Acrylic polymers, on the other hand, can have molecular weights as high as about 100,000, and usually will be in the range of about 5,000 to 50,000 on a weight average basis relative to polystyrene, as determined by gel permea-lion chromatography.

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1 The hydroxyl content of the polymeric polyol should be sufficient such that when the polyol is in combination with the curing agent, the Cam-position will cure to a solvent-resistant coating. Generally, the hydroxyl number of the polymeric polyol will be at least about 170 and preferably will be in the range of about 180 to 3009 based on resin solids.
A preferred class of polymeric polyols are hydroxyl group-containing epoxy resins or resins which are derived from epoxy resins such as polyepoxide-amine adduces which are particularly preferred. The epoxy resins which can be used in the practice of the invention are polyepoxides, 10 that is, polymers having a 1,2-epoxy equivalency greater than 1, prefer- -by about 2 or more. Preferred are polyepoxides which are difunctional with regard to epoxy. The preferred polyepoxides are polyglycidyl ethers of cyclic polyols. Particularly preferred are polyglycidyl ethers of polyphenols such as bisphenol A. Examples of polyepoxides are given in US. Patent 4,260,716, column 3, line 20, to column 4, line 30.
Besides the epoxy resins disclosed above, other epoxy-containing polymers which can be used are acrylic polymers which contain epoxy groups.
These polymers are formed by polymerizing an unsaturated epoxy group-containing monomer such as glycidyl acrylate or methacrylate with one or more other polymerizable ethylenically unsaturated monomers. Examples of these polymers are described in US. Patent 4,001,156, column 3, line 59, to column 5, line 60.
Besides the hydroxyl group-containing epoxy resins disclosed above, hydroxyl group-containing polymers derived from epoxy resins such as polyepoxide-amine adduces can also be used. Examples of amine are ammonia, primary, secondary and tertiary amine and mixtures thereof. The reaction product of the polyepoxide and the amine can be at least partially us 1 neutralized with an acid to form a polymeric produce containing amine salt and/or qua ternary ammonium salt groups. Reaction conditions of polyepoxides with amine, examples of various amine and at least partial neutralization with acid are disclosed in US. Patent 4,260,720, column 5, line 20, to column 7, line 4.
Also, voyeur pi yepoxide-amine adduces are described in European Patent application 001~46 With regard to the amount of organic amine and polyepoxide which are reacted with one another, the relative amounts depend upon the extent of cat ionic salt group formation desired and this in turn will depend upon the molecular weight of the polymer. The extent of cat ionic salt group formation and the molecular weight of the reaction product should be selected such that when the cat ionic polymer is mixed with aqueous medium, a stable dispersion will form. A stable dispersion is one which does not settle or is one which is easily dispersible if some sedimentation occurs.
In addition, the dispersion should be of sufficient cat ionic character that the dispersed resin particles will migrate towards the cathode when an electrical potential is impressed between an anode and a cathode immersed in aqueous dispersion.
Also, the molecular weight, structure and extent of cat ionic salt group formation should be controlled such that the dispersed resin will have the required flow to form a film on the substrate; in the case of electrode position, to form a film on the cathode. The film should be insensitive to moisture to the extent that it will not redissolve in the electrode position bath or be rinsed away from the coated surface after removal from thy bath.
In general, most of the cat ionic polymers useful in the practice of the invention will have average molecular weights within the range of I

l about 500-100,000 and contain from about 0.01 to 10, preferably about 0.1 to 5.0, preferably from about 0.3 to 3.0 milliequivalents of cat ionic group per gram of resin solids. Obviously one must use the skill in the art to couple the molecular weight with the cat ionic group content to arrive at a satisfactory polymer. The polyglycidyl ethers will have molecular weights of about ~00 to 10,000, preferably 1000 to 5,000. Acrylic polymers, on the other hand, will have molecular weights as high as 100,000, preferably 5,000 to 50,000.
Besides epoxy resins and resins derived from epoxy resins, other hydroxyl group-containing polymers such as alkyd resins, polyester resins and hydroxyl group-containing acrylic polymers can also be used in the practice of the invention. examples of these polymers and their cat ionic electrodepositable derivatives are shown, for example, in British Patent 1,303,480 (hydroxyl group-containing acrylic polymers and polyesters) and British Patent 1,159,390 (hydroxyl group-containing acrylic polymers).
Besides the cat ionic polymers which are designed to form aqueous-based coating compositions which may be used in coating applications such as electrode position, it should also be appreciated that organic solvent-based coatings employing the above polymers without cat ionic salt groups can also be used. Formulating coating compositions with such polymers is well known in the art and need not be described in any further detail.
The cross linking agent of the coating composition it a polyester containing at least two substituted ester groups per molecule and is sub-staunchly tree of polyesters containing more than one beta-hydroxyester group per molecule. By substantially free is meant the beta-hydroxyester groups are present in amounts less than that sufficient to get a cured coating by themselves, i.e., a coating which can withstand 40 acetone double rubs as described infer. In general, the beta-hydroxyester groups 1 will be present in amounts less than 5, preferably less than 2 percent by weight calculated as weight of beta-hydroxyester groups per total weight of cross linker. Usually, the cross linkers of the present invention are come pletely free of beta-hydroxyester groups.
The substituents to the ester group are selected from the class consisting of beta-alkoxyester groups, beta-ester groups, bottomed groups gamma-hydroxy groups, gamma-ester groups and delta-hydroxy groups. Examples of suitable cross linking agents are those which contain at least two beta-alkoxyester groups per molecule such as those formed from reacting a polycar-10 boxlike acid or its functional equivalent thereof with on or more 1,2-polyol monoethers. Examples of suitable polycarboxylic acids include dicarboxylic acids such as saturated aliphatic dicarboxylic acids, for example, adipic acid and azelaic acid; aromatic acids such as phthalic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid and itaconic acid.
Besides the acids themselves, functional equivalents of the acids such as androids where they exist and lower alkyd (Cluck) esters of the acids can be used. Examples include succinic android, phthalic android and malefic android.
Polycarboxylic acids or their functional equivalents having a 20 functionality greater than 2 can also be used. Examples include trimellitic android and polycarboxylic acids formed from reacting a dicarboxylic acid with a stoichiometric deficiency of a polyol having a functionality of 3 or more, for example, reacting adipic acid with trimethylolpropane in a 3:1 molar ratio. The resulting product will have an acid functionality of about 3.
Examples of suitable 1,2-polyol monoethers are those of the structure:

I - C - C - 0 - Us ~.L~9~315 1 where Al, R2, R3, R4 and Us are the same or different and include hydrogen, and the radicals alkyd, cycloalkyl, aureole, alkaryl containing from 1 to 18 carbon atoms, including substituted radicals in which the radicals and the substituents will not adversely affect the esterification reaction with the polycarboxylic acid or its functional equivalent thereof and will not adversely affect the transesterification curing reaction or the desirable properties of the coating composition. Examples of suitable substituents include sheller, alkoxy3 car boxy, vinyl and when Al and R3 form a closed hydrocarbon ring. Examples of suitable radicals for Al, R2, R3 and I

include methyl, ethyl and chloromethyl. Examples of suitable radicals for R5 include methyl, ethyl, propel, bottle, isobutyl, cyclohexyl, phenol, ethics-ethyl and 2-methoxysthyl. Preferably, Al, R2, R3 and R4 are hydrogen or methyl and Us is alkyd, cycloalkyl, aureole containing from 1 to 6 carbon atoms.Specific examples of 1,2-glycol monoethers are 2-e~hoxyethanol, 2-butoxyethanol, 2-phenoxyethanol, 2-ethoxypropanol and 2-butoxypropanol. Other examples are 2-methoxyethanol~ 2-isopropoxyethanol, 2-(2-ethoxyethoxy)ethanol and 2-(2-methoxyethoxy)ethanol.
The cross linking agent can be formed from reacting the polycar-boxlike acid or its functional equivalent thereof with a 1,2-glycol monoether at an elevated temperature, usually reflex temperature, in the presence of an esterification catalyst such as an acid or a tin compound. Usually a solvent, for example, an azeotropic solvent such as Tulane or zillion, is used. Reaction is continued with water being constantly removed until a low acid value, for example, 3 or less, is obtained.
Examples of other cross linking agents are polyesters containing at least two bottomed ester groups per molecule. Examples of suite-bye cross linking agents are those which are formed from reacting a polyp carboxylic acid or its functional equivalent thereof with one or more 9~5 beta-hydroxyalkylamides to form the polyester containing at least two beta-alkoxy-amido groups per molecule.
Examples of suitable polycarboxylic acids are those mentioned above.
Examples of suitable beta-hydroxyalkylamides are those of the structure:
Al R2 H 0 l 11 Ho - OH - OH - N - C - R3 where I and R2 are hydrogen and Al, R2 and R3 are selected from the class consisting of alkali cycloalkyl, aureole, alkaryl containing from 1 to 18 car-bun atoms, including substituted radicals in which the substituents will not adversely affect the esterification reaction with the polycarboxylic arid or its functional equivalent thereof and will not adversely affect tube transesterification curing reaction or the desirable properties of the coating composition. Examples ox suitable radicals include alkyd such as methyl, ethyl and i30butyl.
The beta-hydroxyalkylamides of the above structure can be formed by reacting a beta-hydroxyamine with an ester, android, or other lung-tonal equivalent of an organic monocarboxylic acid. Examples of beta-hydroxyamines are hydroxyethylamine, beta-hydroxypropylamine and 2-hydroxy-butylamine. Examples of esters of organic monocarboxylic acids are alkyd esters of aliphatic monocarboxylic acids such as methyl, ethyl, hydroxyethyl and alkoxyethyl esters of acetic, prop ionic and isobutyric acids. The reaction conditions for forming the beta-hydroxyalkylamides are typical ammonialysis reaction conditions.
The cross linking agent can be formed from reacting the polycarboxy-fig acid or its functional equivalent thereof with the beta-hydroxyalkylamide at an elevated temperature, usually reflex temperature, in the presence of l a solvent, for example, an azeotropic solvent such as Tulane or zillion.
Reaction is continued with water being constantly removed until a low acid value, for example, 7 or less, is obtained.
Examples of other cross linking agents are polyesters containing at least two gamma and/or delta-hydroxyester groups per molecule. Examples of suitable cross linking agents are those which are formed from reacting a polycarboxylic acid or its functional equivalent thereof with one or more lo and/or l,4-polyols.
Examples of suitable polyrarboxylic acids are those mentioned above.
Examples of suitable 1,3-polyols and 1,4-polyols are those of the structure:

If lo lo if lo lo lo HO - C - C - C - OH Andy - C - C - C - C - OH

where Al, R2, R3, R4, R5, R6, R7 and R8 can be the same or different and include hydrogen, and the radicals alkyd, cycloalkyl, aureole, alkaryl, anal-Kyle containing from 1 to 18 carbon atoms, including substituted radicals in which the radicals and the substituents will not adversely affect the 20 esterification reaction with the polycarboxylic acid or its functional equivalent thereof nor adversely affect the transesterification curing reaction or the desirable properties of the coating composition. Examples of suitable substituents include sheller, hydroxy, alkoxy, car boxy and vinyl. Examples of suitable radicals include methyl, ethyl, propel, phenol and hydroxymethyl.
Specific examples of 1,3-polyols include 1,3-propanediol~ in-methylolpropane, trimethylolethane and 1,3-butanediol.
Specific examples of 1,4-polyols include 1,4 butanediol and 2-butene-1,4-diol.

~&9~5 the cross linking agent can be formed from reacting the polycar-boxlike acid or its functional equivalent thereof with the 1,3- and/or 1~4-polyol at an elevated temperature, usually reflex temperature, id the presence of an esterification catalyst such as an acid or a tin compound.
Usually a solvent, for example, an azeotropic solvent such as Tulane or zillion, is used Reaction is continued with water being constantly removed until a low acid value, for example, 3 or less, is obtained.
Examples of other cross linking agents are polyesters containing at least two beta- andtor gamma-ester ester groups per molecule. Examples of suitable cross linking agents are those which are formed from reacting: -- PA) a polycarboxylic acid or its functional equivalent with (B) a member selected from the class of:
(i) 1,2-polyols or 1,2-epoxy compounds, (ii) 1,3-polyols, (C) a monocarboxylic acid.
Examples of suitable polycarboxylic acids are those mentioned above.
The cross linking agent can be formed by reacting the polycarboxy-fig acid or its functional equivalent thereof with the 1,2-polyol, 1,2-20 epoxy compound, or 1,3-polyol and the monocarboxylic acid in about a 1/2/1 equivalent ratio at sun elevated temperature, usually reflex temperature, in the presence of an esterification catalyst such as an acid or a tin compound.
Usually a solvent, for example, an azeotropic solvent such as Tulane or zillion it used. Reaction it continued with water constantly being removed until a low acid value, for example, 7 or less, is obtained.
Examples of suitable 1,2-polyols and 1,3-polyols are those men-toned above. Examples of 1,2-epoxy compounds are those of the structure:

:L~89~

OH - OH
o where Al and R3 are the same or different and include hydrogen and the radicals alkyd, cycloalkyl, aureole, alkaryl containing from 1 to 18 carbon atoms, including substituted radicals in which the radicals or the sub-stituents will not adversely affect the esterification reaction with the polycarboxylic acid or its functional equivalent thereof, nor adversely affect the transesterification curing reaction or the desirable properties of the coating composition. Examples of suitable substituents include sheller, hydroxy, alkoxy, car boxy, vinyl and when Al and R3 form closed hydrocarbon ring. Examples of suitable radicals include methyl, ethyl, hydroxymethyl, chloromethyl, carboxymethyl, phenol, methoxy and phonics.
Specific examples of 1,2-epoxy compounds include ethylene oxide, propylene oxide, 1,2-epoxy butane, butadiene monoepoxide, glycidol, cycle-hexane oxide and a glycidyl ester of a saturated aliphatic monocarboxylic acid containing from 9 to 12 carbon atoms, i.e., CORRODER E.
Examples of monocarboxylic acids are organic monocarboxylic acids having the following structure:

Rug C - OH

where Rug it a hydrocarbamyl radical containing from 1 to 18 carbon atoms.
The preferred monocarboxylic acids contain from 1 to 8 carbon atoms and include acetic, prop ionic, isobutyric, benzoic and Starkey acids.
The cross linking agent can be formed from reacting the polycar-boxlike acid or its functional equivalent thereof with the 1,3-polyol and l the monocarboxylic acid a elevated temperature, usually reflex temperature, in the presence of an esterification catalyst such as an acid or a tin compound. Visually a solvent such as Tulane or zillion is used. Reaction is continued with water being constantly removed until a low acid value, for example, 7 or less, is obtained.
The third component in the coating compositions of the invention is a transesterification catalyst. These catalysts are known in eke art and include salts or complexes of metals such as lead, zinc, iron, eon and manganese. Suitable salts and complexes include 2-ethylhexonates (octets), lo naphthanates and acutely acetonates.
The relative amounts of the polymeric polyol and the cross linking agent which are present in the coating composition can vary between fairly wide limits depending upon the reactivity of the components and the time and temperature of curing and the properties desired in the cured coating.
In general, the polymeric polyol will be present in amounts of about 20 to 95 percent, preferably about 50 to 85 percent by weight, and the cross link-in agent in amounts of about 5 to 80, preferably 15 to 50 percent by weight;
the percentages by weight being based on total weight of polymeric polyol and cross linking agent, and being determined on a solids basis.

The catalyst is present in amounts of about 0.1 to 2.0, prefer-ably about 0.2 to 1.0 percent by weight metal based on total weight (solids) of the polymeric polyol and the cross linking agent.
The components of the coating composition can be mixed simultane-ouzel or in any order that is convenient. If the components are a liquid and ox sufficiently low viscosity, they can be mixed together neat to form the coating composition. Alternately, if the components are higher vise costly liquids or solids, the components can be mixed with a delineate to 39~

l reduce the viscosity of the composition so that it may be suitable for coating applications.
By liquid delineate is meant a solvent or a nonsolvent which is volatile and which is removed after the coating is applied and is needed to reduce viscosity sufficiently to enable forces available in simple coating techniques, that is, brushing and spraying, to spread the coating to con-troll able, desired, and uniform thickness. Also, delineates assist in sub-striate wetting, resinous component compatibility and coalescence or film formation. Generally, when used, the delineate will be present in the combo-lo session in amounts of about 20 to 90, preferably 50 to 80 percent by weight based on total weight of the coating composition, although more delineate may be employed depending upon the particular coating application.
Examples of suitable liquid delineates for organic ~olvent-based coatings will depend somewhat on the particular system employed. In gent oral, however, aromatic hydrocarbons such as Tulane and zillion, tones such as methyl ethyl kitten and methyl isobutyl kitten, alcohols such as isopropyl alcohol, normal bottle alcohol, monoalkyl ethers of glycols such as 2-alko~yethanol, 2-alkoxypropanol and compatible mixtures of these solvents can be used.
Besides organic solvents, water can be used as a delineate either alone or in combination with water-miscible organic solvents. When water is used, the coating composition is usually modified such as by incorporate in water-solubilizing groups such as the cat ionic groups mentioned above to provide for the necessary volubility in water. Besides the cat ionic groups mentioned above, other water-solubilizing groups such as non-ionic groups, for example, ethylene oxide groups, and anionic groups such as carboxylate silt groups may be introduced into the polymeric polyol or the I

l polyester cross linking agent to ~isper6e or syllables the coating compost-lion in water.
The coating compositions of the invention may also optionally contain a pigment. Pigments may be of any conventional type, comprising, for example, iron oxides, lead oxides, strontium chromates carbon black, coal dust, titanium dioxide, talc, barium sulfate, as well as color pig-mints such as cadmium yellow cadmium red, chromium yellow and metallic pigments such as aluminum flap.
The pigment content of the coating composition is usually expressed as the pigment-to-resin weight ratio. In the practice of the present invent lion, pigment-to-resin weight ratios can be as high as 2:1, and for most pigmented coatings, are usually within the range of about ~.05 to lo In addition to the above ingredients, various fillers, plastic Sirius, anti-oxidantsl ultraviolet light absorbers, flow control agents, surfactants and other formulating additives can be employed if desired.
These materials are optional and generally constitute up to 30 percent by weight of the coating composition based on total solids.
The coating compositions of the invention can be applied by con-ventional methods including brushing, dipping, flow coating, spraying, and, 20 for aqueous-based compositions containing ionic salt groups, by electron -deposition. Usually, they can be applied virtually over any substrate including wood, metal, glass, cloth, leather, plastic, foam and the like, as well as over various primers. For electroconductive substrates such as metals, the coatings can be applied by electrode position. In general, the coating thickness will vary somewhat depending upon the application desired.
In general, coatings from about 0.1 to 10 miss can be applied and coatings from about 0.1 to 5 miss are usual.

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1 When aqueous dispersions of the coating composition are employed for use in electrode position, the aqueous dispersion is placed in contact with an electrically conductive anode and an electrically conductive cathode. In the ruse of caCionic electrode position, the surface to be coated is the cathode. Following contact with the aqueous dispersion, an adherent film of the coating composition is deposited on the electrode being coated when a sufficient voltage is impressed between the electrodes.
Conditions under which electrode position is carried out are known in the art. me applied voltage may be varied and can be, for example, as low as 1 volt or as high as several thousand volts, but is typically between 50 and 500 volts. Current density is usually between 1.0 ampere and 15 amperes per square foot and tends to decrease during electrode position indicating the formation of an insulating film.
After the coating has been applied, it is cured by heating at elevated temperatures such as at about 150 to 205C. for about 10 to 45 minutes to form solvent-resistant coatings. By solvent-resistant coatings is meant that the coating will be resistant to acetone, for example, by rubbing across the coating with an acetone-saturated cloth. Coatings which are not cured or poorly cured will not withstand the rubbing action with acetone and will be removed with less than 10 acetone double rubs. Cured coatings, on the other hand, will withstand 30 acetone double rubs, and preferably at least 100 acetone double rubs.
Illustrating the invention are the following examples which, how-ever, are not to be construed as limiting the invention to their details.
All parts and percentages in the examples, as well as throughout the specie -ligation, are by weight unless otherwise indicated.

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1 Example I
The following example shows the preparation of a coating compost-lion containing a cross linking agent having three beta~alkoxyester groups per molecule. The cross linking agent was formed by reacting trimellitic android with 2-butoxyethanol in a 1:3 molar ratio. The cross linking agent was then mixed with a polymeric polyol formed from condensing an epoxy resin (polyglycidyl ether of a polyphenol) with an amine. The mix-lure was dispersed in water with the aid of acid and combined with lead octet catalyst. Steel panels were catholically electrocuted in the dispersion and the coatings heated to make them solvent resistant. The details of the Example are shown below:

Cross linking Agent The cross linking agent was prepared from the following mixture of ingredients:

Weight Solids Ingredient (in grams) Equivalents Moles Trimellitic android 192 19~.0 3.00 1.00

2-butoxyethanol 365 354.0 3.09 3.09 Para-toluenesulfonic 20 acid 1.4 1.4 Zillion 40.0 The ingredients were charged to a reaction vessel under a vitro-gun blanket. The mixture was heated to reflex until an acid value of 2.2 was obtained.

l Polymeric Polyol to the polymeric polyol as described in European Patent Application I 5J~ or e up wise formed from reacting a polyglycidyl ether of bisphenal A with diethanolamine in above a 3:1 equivalent ratio. The adduce was then chain extended with a mixture of a primary and a disecondary amine, namely, 3- -dimethylaminopropylamine, and the adduce of 1,6-hexamethylene Damon and the glycidyl ester of Voyeuristic acid (CORRODER E).

Weight Solids Injgredient(in grams) (in grams) Moles lo EON 8291 460.7 445.5 2.269 1.135 >(1.146) >(0.573) Bisphenol A 128.0 128.0 1.123 0.562 Zillion 30.0 Diethanolamine 38.0 38.0 0.362 0.362 2-butoxyethanol 307.2 - - - -

3-dimethylamino-propyli~mine 18.4 18.4 0.361 0.180 1,6-hexamethyl~ne-CORRODER E adduce (1:2 molar Russia 122.4 122.4 0.36 0.18 lPolyglycidyl ether of bisphenol A having an epoxide equivalent of 196 commercially available from Shell Chemical Company.
adequate formed by adding the glycidyl ester of Voyeuristic acid drops to the 1,6-hexamethylene Damon at 60C. At the completion of addition, the mixture was heated to 100C. and held for two hours. The glycidyl ester of Voyeuristic acid it commercially available from Shell Chemical Company as CORRODER E.

Aqueous Dispersion An aqueous dispersion was prepared by mixing together the follow-in ingredients:

l Weight Solids Ingredient in grams) (in grams) Equivalents Polymeric polyol 144.3 107.4 0.155 (amine) Cross linking agent 39.9 Lead octet (catalyst) 2.70 2.05 Lactic acid 7.11 owe Deionized water 797.1 lead octet dissolved in a hydrocarbon solvent.
lo 245 percent of the total theoretical neutralization.

Into a large stainless steel beaker was added the polymeric polyol, the cross linking agent prepared as described above and the lead catalyst. The ingredients were blended until uniform. Lactic acid was added with agitation and the reaction mixture thinned with water to form the aqueous dispersion having a solids content of 14.8 percent (15 percent calculated). Both untreated and zinc phosphate pretreated steel panels were catholically electrode posited in the dispersion at about 90-1~0 volts for 90 seconds. The coated panels were baked at 180 C. for 30 minutes to form solvent-resistant coatings. The untreated steel panels withstood 100 Sutton double rubs and the zinc phosphate pretreat panels withstood 45 acetone double rubs. The number of acetone double rubs are the number of rubs back and forth with an acetone-saturated cloth using normal hand pressure to remove the cured coating.

Example II
The following example shows the preparation of a coating compost-lion containing a cross linking agent containing 6 beta-alkoxyester groups l per molecule. Lowe cross linking agent was formed from reacting trimellitic android with trimethylolpropane in a 3:1 molar ratio and esterifying with 6 moles of 2-butoxyethanol. The cross linking agent was mixed with a polyp metric polyol formed from condensing an epoxy resin (polyglycidyl ether of a polyphenol) with an amine as described below. The mixture was formulated into an organic solvent-based coaxing composition with and without lead octet catalyst. Steel panels were coated with the composition and the coated substrates heated to give cured coatings.

Polymeric Polyol The polymeric polyol was formed by chain extending an epoxy resin with a polyester dill and reacting the chain-extended epoxy resin with a mixture of amine, namely, methylethanolamine and a diketimine derivative of diethylene thiamine.

Weight Solids Ingredient (in grams) Equivalents Moles UPON 8281 953.7 953.7 4.819 (epoxy) 2.41 POP 02002 320.6 320.6 1.2 (OH) 0.6 Zillion 80.0 Bisphenol A 274.7 274.7 2.41 (OH) 1.205 20 Benzyldimethylamine 5.9 2-ethoxyethanol317.9 Methylisobutyl diketimine of diethylene Truman 85.7 61.9 0.232 (amine) 0.232 N-methylethanolamine $9.5 69.5 0.926 (amine) 0.92S

1Polyglycidyl then of bisphenol A having an epoxide equivalent of about 19B commercially available from the Shell Chemical Company.

2Polycaprolactone dill having a molecular weight of about 545 common-Shelley available from the Union Carbide Company.
3Methylisobutyl kitten solvent.

S
i , The EON 828, POP 0200 and zillion were charged to a reaction vessel under a nitrogen blanket and heated to reflex and held for 30 mint vies. The reaction mixture was cooled to 155C.~ followed by the addition of the bisphenol A. Ben~yldimethylamine (1.9 grams) was added and the react lion mixture exothermed. It was cooled to 130 C., hollowed by the addition of the remaining 4.0 grams of the benzyldimethylamine. The reaction mix-lure was held at about 130 C. for about 3 hours until the viscosity of the reaction mixture as a 50 percent resin solids solution in 2-ethoxyethanol was No. The 2-ethoxyethanol, methylisobutyl diketimine of diethylene in-lo amine and methylethanolamine were added and the reaction mixture held at about 110 C. for about one hour, followed by cooling to room temperature.
The reaction mixture had a solids content of about 80 percent by weight.
A coating composition was prepared by mixing 27.9 grams ~23.2 grams solids) of the polymeric polyol and 12.3 grams (11.5 grams solids) of the cross linking agent. Thy mixture was thinned with 6.1 grams of 2- -ethoxyethanol to form a 75 percent solids foaling composition. A portion of this coating composition was set aside; a second portion (21.2 grams) was mixed with 0.34 parts by weight (0.26 grams solids) of lead octet.
Both coating compositions were drawn down on untreated and zinc phosphate 20 pretreated steel panels and the wet films cured at 350F. (177C.) for 30 minutes. The coatings without the lead catalyst were removed by 23 acetone double rubs (on untreated steel panels) and 15 acetone double rubs (on zinc phosphate pretreated steel panel), whereas the coating with the catalyst withstood 175 acetone double rubs on both substrates.

Example III
The following example shows the preparation of a coating compost-lion containing a cross linking agent having two bottomed ester groups per Jo off l molecule. The cross linking agent was prepared by reacting N-(2-hydroxyethyl)-isobutyramide with a condensate of trimethylolpropane and trimellitic ashy-drive. The cross linking agent was mixed with a polymeric polyol made from condensing an epoxy resin (polyglycidyl ether of a polyphenol) with an amine. The mixture was formulated into a coating composition with lead octet catalyst and the composition drawn down on steel panels to form coatings. The coatings were heated to give solvent-resistant coatings.

N-(2-hydroxyethyl)isobutyramide N-(2-hydroxyethyl)isobutyramide was prepared as follows:

Weight Solids 10 Ingredient (in grams) yin grams) Equivalents Moles Isobutyric Acadia 440.0 4.994 4~994 2-ethoxyethanol 495.0 450.0 5.500 5.500 ~ylene 80.0 Para-toluenesulfonic acid 2.0 2.0 Ethanol amine 305.0 305.0 5.000 5.000 The isobutyric acid, 2-ethoxyethanol, zillion and para-toluenesulfonic acid were charged to a reaction vessel under a nitrogen blanket and a Dean-Stark trap and heated to reflex. The reaction mixture was held at reflex temperature (165C.) until an acid value of 3.4 was obtained (123 grams of aqueous phase collected). The reaction mixture was cooled to 100C., the ethanol amine was added and refluxing was continued for 9 hours. At that point, the reaction mixture was sparred until 447 grams of distillate was obtained. The product formed a dark brown, wet crystalline mass on standing overnight. This was recrystallized from ethanol and Tulane to obtain 231.8 grams (35.4 percent yield, which could be increased with subsequent crops) of off-white needle crystals, my 54-57 C.

l Cross linking Agent Weight Solids Ingredient (in grams? (in grams) Equivalents Moles TrimPllitic android 131.9 131.9 2.061 0.687 Trimethylolpropane 30.7 30.7 0.687 0.229 N-(2-hydroxyethyl)-isobutyramide180.0 180.0 1.374 1.374 Zillion 80.0 The trimellitic android, trimethylolpropane and the zillion were lo charged to a reaction vessel under a nitrogen blanket and a Dean-Stark trap and held at reflex for 30 minutes. The reaction mixture was then cooled to 100C., the amino alcohol was added, sod refluxing was continued until an acid value of 3.2 was obtained. The product was found to have a solids content of 81.7 percent.

Polymeric Polyol The polymeric polyol was formed by chain extending an epoxy resin with a polyester dill and then reacting the chain-extended polyester with a mixture of ammonias one of which included primary amine groups blocked with ketimine.

Weight Solids Ingredient (in grams) (in grams) Equivalents owes EON 8281 1686.2 1686.2 8.674 (epoxy) 4.337 POP owe 588.4 588.4 2.160 (OH) 1.080 Zillion 144.Q
Bisphenol A 494.5 494.5 4.337 (OH) 2.169 Benzyldimethylamine 10.6 2-ethoxyethanol572.2 Methylisobutyl diketimine of diethylene Truman 111.4 0.417 (amine 0.417 30 Monoethanolamine125.1 125.1 1.668 famine) 1.668 9~3~i l lPolyglycidyl ether of bisphenol A having an epoxide equivalent of about 198 commercially available from Shell Chemical Company.

2Polycaprolactone dill having a molecular weight of about 5~5 commercially available from the Union Carbide Company.
solution in methylisobutyl kitten.
The EON 828, POP 0200 and zillion were charged to a reaction Yes-sol and heated under a nitrogen blanket to reflex and held for 30 minutes.
The reaction mixture was cooled to 155C., followed by the addition of the bisphenol A. Benzyldimethylamine (3.4 grams) was added and the reaction lo mixture exothermed~ The reaction mixture was cooled to 130C., followed by the addition of the remaining benzyldimethylamine and the reaction mixture held at 130 C. until it attained a reduced Gardner-Holdt viscosity (50 percent resin solids in 2-ethoxyethanol) of N+. The 2-ethoxyethanol, diketimine and monoethanolamine were then added and the reaction mixture held at 110C. for about one hour to complete the reaction.
To 34.78 parts by weight of the polymeric polyol reaction mixture prepared as described above were added 17.43 parts by weight of the cross-linking agent and 7.87 grams of 2-ethoxyethanol. The mixture was heated and stirred until homogeneous to form a coating composition. A portion of 20 this mixture was put aside and the remaining portion (27.70 grams) was blended with 0.44 grams of lead octet (0.33 grams solids). Both coating compositions were drawn down over untreated and zinc phosphate pretreated steel panels. The coated panel were then baked at 350F. (177C.) for 30 minutes. The coatings obtained from the compositions which contained no lead exhibited practically no acetone resistance (13-15 acetone double rubs). However, the coatings obtained from compositions containing the lead catalyst exhibited 75 acetone double rubs on the untreated steel and 60 acetone double rubs on the zinc phosphate pretreated steel panels.

l Example IV
The following example shows the preparation of a coating compost-lion containing a cross linking agent having two delta hydroxyester groups per molecule. The cross linking agent is formed by reacting adipic acid with 1,4-butanediol in a 1:2 molar ratio. The cross linking agent was mixed with a polymeric polyol formed from condensing an epoxy resin (polyglycidyl ether of a polyphenol) with an amine. The mixture was dissolved in organic solvent, lead octet was added, end the solution drawn down on steel panels and the coated panels heated to give solvent-resistant coatings.

The details of the Example are shown below: -Cross linking Agent The cross linking agent was prepared from the following mixture of ingredients:

Weight Solids Ingredient in grams? (in grams) Equivalents Moles Adipic acid 146.0 146.0 2.000 1.000 1,4-butanediol180.0 180.0 4.000 2.000 Zillion 50.0 Para-toluenesulfonic acid 1.0 1.0 The ingredients were charged to a reaction vessel under a nitrogen blanket. The reaction mixture was heated to reflex until an acid value of 1.3 was obtained. During the reaction 48.1 grams of aqueous layer was collected in a Dean-Stark trap.

Polymeric Polyol The polymeric polyol was formed from reacting a polyglycidyl ether of bisphenol A with diethanolamine in about a 3:1 equivalent ratio. The adduce was then chain extended with a mixture of a primary and a disecond-cry amine, namely, 3-dimethylaminopropylamin~, and the adduce of 1~6-hexamethylene Damon and the glycidyl ester of Voyeuristic acid (CORRODER E).

Weight Solids Ingredient in grams) (in_~ra~s)Equivalents Moles EON 8291 921.0890.6 4.537 2.268 >(2.293) lo Bisphenol A 255.8255.R 2.244 1.122 Zillion DUO
2-ethoxyethanol 608.0 Diethanolamine 80.3 80.3 0.765 0.765 Dimethylaminopropyl- -amine 38.0 38.0 0.744 0.372 1,6-hexamethylene diamine-glycidyl ester of Voyeuristic acid adduce (1:2 molar Russia 252.9244.5 Q.745 0.372 lPolyglycidyl ether of bisphenol A having an epoxide equivalent of about 196 commercially available from the Shell Chemical Company.
adequate formed by adding the glycidyl ester of Voyeuristic acid drops to the 1,6-hexamethylene Damon at a temperature of 60C. At the complex lion of addition, the mixture was heated to 100C. and held for two hours.
The glycidyl ester of Voyeuristic acid is commercially available from Shell Chemical Company as CORRODER E.

Organic Solvent-Based Coating Composition Weight Ingredient (in grams) Polymeric polyol 36.18 Gross linking agent 11.04 Lead octet (75.9% solids in 0.67 hydrocarbon solvent) 2-ethoxyethyl acetate 8.79 ho 1 The ingredients were mixed together and heated in a 2-ounce glass jar to obtain a clear, yellow resin. The coating composition was drawn down on an untreated steel panel and on a zinc phosphate pretreated steel panel. The coated panels were cured for about 30 minutes at 180DC. The cured coatings exhibited a medium to high gloss and had a thickness of from about 1.6 to 2.2 miss. The coating on the untreated steel was removed after 125 acetone double rubs. The coated zinc phosphate pretreated steel panel withstood 132 acetone double rubs.

Example V

The following example shows the preparation off coating compost- -lion containing a cross linking agent which is a gamma-hydroxy polyester formed by reacting adipic acid with trimethylolpropane in a 1:2 molar ratio.
The cross linking agent was mixed with a polymeric polyol formed from con-denying a polyglycidyl ether of a polyphenol with an amine. The mixture was combined with lead octet catalyst to form a coating composition.
Steel panels were coated with the composition and the coated substrates heated to give solvent-resistant coatings. Also the mixture was dispersed in water with the aid of acid and steel panels were catholically electron coated with the dispersion. The details of the example are show below:

Cross linking Agent The cross linking agent was prepared from the following mixture of ingredients:

Weight Solids Ingredient in grams) yin grams) ~uivalents Notes Adipic acid 146.0146.0 2.000 1.000 Trimethylolpropane 268.0 268.0 6.000 2.000 Zillion 40.0 Para-toluenesulfonic acid 1.0 1.0 1 The ingredients were charted to a reaction vessel under a nitrogen blanket and heated to rollicks. The reaction mixture was held at reflex them-portray until an acid value of about 1.7 was obtained.

Polymeric Polyol The polymeric polyol was formed from chain extending a polyglycidyl ether of bisphenol A with a polyester dill. The adduce was then reacted with a mixture of amine, namely, monoethanolamine and the methylisobutyl diketimine of ethylene thiamine.

Weight Solids 10 Ingredient (in grams) (in trams) Equivalents Moles UPON 8281 953.7 953 7 4.819 (epoxy) 2.41 POP owe 320.6 320.6 1.2 I 0.6 Zillion 80.0 Bisphenol A 274.7 274.7 2.41 (OH) 1.205 Benzyldimethylamine5.9 2-ethoxyethanol 317.9 Methylisobutyl diketimine of diethylene Truman 85.7 61.9 0.232 (amine) 0.232 Monoethanolamine69.5 69.5 0.926 (amine) 0.926 20lPolyglycidyl ether of bi~phenol A having an epoxide equivalent of about 198 commercially available from Shell Chemical Company.

2Polycaprolactone dill having a molecular weight of about 545 common-Shelley available from the Union Carbide Company.
solution in methylisobutyl kitten.

The EON 828, POP 0200 and zillion were charged to a reaction vessel and heated under a nitrogen blanket to reflex and held for 30 mint vies. The reaction mixture was cooled to 155C. followed by addition of 1 the bisphenol .~. Benæyldimethylamine (1.9 grams was added and the react lion mixture exothermed. The reaction mixture was cooled to 130C. followed by the addition of the remaining benzyldimethylamine and the reaction mix-lure held at 130 C. until it attained a reduced Gardner Hold viscosity (50 percent resin solids in 2-ethoxyethanol) of N+. The 2-ethoxyethanol, diXetimine and monoethanolamine were then added and the reaction mixture held at 108-112C. for about one hour eon complete the reaction.
To 39.55 grams (31.64 grams solids) of the polymeric polyol pro-pared as described immediately above was added 17.07 grams (15.60 grams solids) of the cross linking agent prepared as described above. To a 31.78 gram sample (26.5 grams solids) of the mixture was added 0.50 grams of the lead octet solution as described in Example IV. The composition was drawn down with a drubber over untreated and zinc phosphate pretreated steel panels and the panels heated to 360 F. (182 C.) for 30 minutes. The cured films were glossy with a textured surface. The coating over the untrusted steel was removed after 150 acetone double rubs, whereas the coating over the zinc phosphate pretreated steel withstood 107 acetone double rubs.
When comparable coatings were made without the use of the lead gala-lust, the cured coatings were removed by about 10 to 23 acetone double rubs.

ye Aqueous Dispersion An aqueous dispersion was prepared by mixing together the follow-in ingredients:
Weight Solids I~redients (in grams? (in grams) ~u~valents Polymeric polyol 122.4 100.5 0.098 Cross linking agent 49.5 Lead octet (catalyst 2.75 2.09 Surfactant2 3.75 Lactic acid 3.49 0,034 Deionized water 829~1 -1 lead oust in a hydrocarbon solvent.

Surfactant was prepared by blending 120 grams of alkyd imida~oline commercially available from Geigy Industrial Chemicals as GEIGY AMINE Sue 120 parts by weight of an acetylenic alcohol commercially available Fran Air Products and Chemicals Inc. as SURFYNOL 104, 120 parts by weight of 2-butoxyethanol and ~21 parts by weight of deionized water and 19 parts by weight of glacial acetic acid.

The pol~neric polyol and the cross linking agent were blended together with warming in a steel beaker. The lead octet was blended in, followed by the addition of the lactic acid. The reaction mixture was then thinned with the deionized water to form a 14.6 percent by weight resin solids dispersion.
Untreated steel and zinc phosphate pretreated steel panels were catholically electrocuted in the dispersion at 200 volts for 90 seconds.
The coated substrates were then heated to foe (204C.) for 30 minutes to form cured coatings. The coating on the untreated steel withstood 150 acetone double rubs, whereas the coating on the zinc phosphate pretreated steel withstood 140 acetone double rubs.

Example VI

The following ex~nple was similar to Example V with the exception that the cross linking agent was introduced into the resin cook.

Polymeric Polyol Containing Ross linking Agent The polymeric polyol was prepared as generally described above in Example Y with the exception that the cross linking agent was cooked in.

The charge for preparing the polymeric polyol was as follows:

O

9~5 l Weight Solids In~redient(in grams) (in trams) Equivalents Moles UPON 8~8 702.6 702.6 3.614 (epoxy) 1.807 POP 0~00 244.0 244.0 0.90 (OH) 0.45 Zillion 60.0 Bisphenol A 206.1 206.1 1.808 (OH) 0.904 Benzyldimethylamine4.8 Cross linking agentl652.9 616.3 2-butoxyethanol 373.

lo ~ethylisobutyl diketimine of diethylene thiamine 59.7 46.5 0.174 (amine) 0.174 Monoethanolamine52.1 52.1 0.694 (mine) 0.694 1Crosslinker was the adipic acid/trimethylolpropane condensate pro-pared as generally described in Example V.

The EON 828, POP 0200 and zillion were charged to a reaction vessel under a nitrogen blanket and heated to reflex and held for 30 mint vies. The reaction mixture was cooled to 155C. and the bisphenol A added.
The temperature dropped to 128 C. and the reaction mixture was held for about 20 minutes at this temperature. Benzyldimethylamine (1.5 grams) was added and the reaction mixture exothermed with the temperature reaching 170C. The reaction mixture was cooled to 130C., followed by the addition of 3.3 grams of the benzyldimethylamine. The reaction mixture was held at a temperature ox about 130C. until a Gardner-Holdt viscosity (50 percent resin solids in 2-ethoxyethanol) of P was obtained. The cross linking agent dissolved in the 2~butoxyethanol was then added, the reaction mixture temperature dropping to 85C. The reaction mixture was heated to 110C.
and held for about one hour to complete the }exaction. The reaction mixture had a solids content of 82.7 percent.

1 Aqueous Dispersion The resinous reaction product prepared as described immediately above was dispersed in aqueous medium as follows:

Weight Solids Ingredient (in gram sin grams) Equivalents Polymeric polyol containing cross linking agent prepared as described immediately above 965.0 800.0 0.521 (amine) Surfactant of Example Y 20.0 Tactic acid 18.65 0.1822 Deionized water 1282.1 The polymeric polyol and the surfactant were mixed together in a stainless steel beaker, followed by the addition with mixing of the lactic acid. The reaction mixture was then thinned with deionized water to form a 34.2 percent solids aqueous dispersion.
A cat ionic electrode position paint was prepared from the following mixture of ingredients:

Weight 2 Ingredient Deionized water 1704.2 Lead acetate 6.9 Aqueous dispersion of polymeric polyol 1703.2 Pigment pastel 385.7 lithe pigment paste contained 32.9 percent by weight pigment, 13.2 per- -cent by weight resinous vehicle and 1.1 percent by weight dibutyltin oxide.
The pigment paste was prepared as generally described in example III of US. 4,007,154.

The deionized water was charged to a mixing vessel followed by the addition of the lead acetate. The polymeric polyol (34.2 percent 1 solids) was then stirred in, followed by the addition of the pigment paste with stirring. The final paint had a total solids content of 20 percent, a pi of 6.25, pigment-to-binder ratio of 0.2:1. After stirring for two day, the pi remained at 6.25 and the specific conductivity of the dispersion was 1250 measured a 77 F. (25 C.). Zinc phosphate pretreated steel panels were catholically electrocuted in the dispersion at 120 volts for 20 mint vies at a bath temperature of 70 F. (21 C.). The coatings were cured at 350F. (177~.) for 30 minutes. The coatings were removed after 35 acetone double rubs and were evaluated for corrosion resistance which was deter-lo mined by scribing the cured coated panel with an "I" and exposing the scribed panel to a salt spray fog in accordance with ASTM D-117 for 14 days. The panels were removed from the chamber, dried and the scribe mark taped with masking tape, the tape pulled off at a 45 angle and the creep-age from the scribe mark measured. Creep age is the rusted, darkened area of the panel where the coating has lifted from the panel surface. The scribe creep age was 1/16 inch. When untreated steel panels were cathodic gaily electrocuted in the bath at 80 volts for 2 minutes and the coatings cured and exposed for 14 days to salt spray corrosion as described above, the scribe creep age was 3/16 of an inch.

Example VII
The following example shows the preparation of a coating combo-session containing the cross linking agent of Example IV and the polymeric polyol of Example V. The coating composition was formulated with lead catalyst and steel panels were coated with the composition and the coated substrates heated to give solvent-resistant coatings. The specific coating formulation is shown below:

1 Organic ~olvent-Based Coating Composition Weight Solids Ingredient (in grams) Polymeric polyol 11.64 9.67 Cross linking agent 5.2~ 4.77 2-ethoxyethanol 7.15 Lead octet 0.24 0.18 The ingredients were mixed and heated to form a homogeneous come position which was then drawn down on untreated and zinc phosphate pro-treated steel panels. The coated panels were cured for 30 minutes at 400F.
(204C.) to give cured coatings which withstood 150 acetone double rubs.
Coatings formulated without lead catalyst and baked at ~00F.(204C.) for 30 minutes were removed by only 23 acetone double rubs on untreated steel and 16 acetone double rubs on zinc phosphate pretreated steel.

Example VIII
The following example shows the preparation of a coating compost-lion containing a croæslinking agent having three beta-ester ester groups per molecule. The cross linking agent was formed by reacting trimellitic android with ethylene glycol and isobutyric acid in a 1:3:3 molar ratio.
The cross linking agent was then mixed with a polymeric polyol formed from condensing an epoxy resin (polyglycidyl ether of a polyphenol) with an amine.
The mixture was combined with lead octet catalyst and dispensed in water with the aid of acid. Steel panels were catholically electrocuted with the dispersion and the coatings heated to give solvent-resiRtant coating. -Also, the mixture was dissolved in organic solvent, the solution drawn down on steel panels and the coated panels heated to give solvent-resistant coatings. The details of the Example are shown below:

9~5 l Cross linking Agent The cross linking agent was prepared from the flying mixture of ingredients:

Weight Solids In~redient(in grams) (in grams) equivalents Moles Trimellitic android 192.0 3.000 l.000 Ethylene glycol217.2 186.2 7.000 3.500 Isobutyric assiduous 264.3 3.000 3.000 Para-toluenesulfonic acid 1.4 1.4 Tulane 80.0 The above ingredients were charged to a reaction vessel under a - nitrogen blanket and heated to reflex. Reflex was continued until an acid value of 4.1 was obtained. The hydroxyl value of the product was 2.9 (apart from the acid value), and the water content was 0.03 percent.
Polymeric Polyol The polymeric polyol was formed from reacting a polyglycidyl ether of bisphenol A with diethanolamine in about a 3:1 equivalent ratio. The adduce was then chain extended with a mixture of a primary and a disecond-cry amine, namely, 3-dimethylaminopropylamine, and the adduce of 1,6-hexamethylene Damon and the glycidyl ester of Voyeuristic acid (CORRODER E).

Weight Solids Ingredient in trams) (in grams) Equivalents Moles EON 8291 921.0 890.6 4.537 2.268 >(2.293) >(1.147) -Bisphenol A 255.8 255.8 2.244 1.122 Zillion 30.0 Diethanolamine 80.3 80.3 0.765 0.765 3-dimethylaminopropyl-amine 38.0 38.0 0.745 0.372 30 1,6-hexamethylene glycidyl ester of Voyeuristic acid adduce (1:2 molar Russia 256.8 253.4 0.745 0.372 2-butoxyethanol 614.2 ~1~39~3~i 1 lPolyglycidyl ether of bisphenol A having an epoxide equivalent of about 193-203 commercially available from the Shell Chemical Company.

adequate formed by adding the glycidyl ester of Voyeuristic acid drops to the 1,6-hexam2~hylene Damon at a temperature of 60 C. At the complex lion of addition the mixture was heated to 100C. and held for two hours.
The glycidyl ester of Voyeuristic acid is commercially available from Shell Chemical Company as CORRODER E.

Aqueous Dispersion An aqueous dispersion of the polymeric polyol and the cross linking agent prepared as described above was made as follows: -Weight Solids Ingredient (in gram sin grams Polymeric polyol 146.2 109.4 0.162 (amine) Cross linking agent 40.7 Lead octoste solution 2.75 2.091 -Lactic acid 7.48 0.0732 Deionized water 805.5 175.9% solids lead octet dissolved in hydrocarbon solvent.
245 percent of the total theoretical neutralization.

The polymeric polyol, cross linking agent and lead were charged to a stainless steel beaker and mixed together. The lactic acid was added and blended into the mixture, followed by thinning with the deionized water.
The aqueous dispersion had a solids content of 14.3 percent.
Untreated and zinc phosphate pretreated steel panels were catholically electrocuted in the dispersion sty 100 volts for 90 seconds.
The coatings were then cured at 180C. for 30 minutes to form films having a thickness of about 0.7 to 0.9 mill The untreated steel panels had from between 56 to 70 acetone double rubs and the zinc phosphate pretreated steel panels withstood between 38 to So acetone double rubs.

lo S

Organic Solvent-Based Coating Composition Weigh Solids Ingredient (in grams) (in trams) Polymeric polyol 36.39 27.19 Cross linking agent 18.12 13.46 2-ethoxyethanol 11.82 The above ingredients were charged to a 2-ounce glass jar and 25.19 grams was transferred (after heating and mixing to homogeneity) to a second 2-ounce glass jar. After transfer, 0.37 gram of lead octet 10(75 9 percent solids in a hydrocarbon solvent) was added to form the coating composition.
The coating composition was drawn down on an untreated steel panel and on a zinc phosphate pretreated steel panel. The coated panels were cured for 30 minutes at 350F. (177C.). The cured coating had a thickness of above 1.8-2.8 miss and withstood 150 acetone double rubs (untreated steel) and 175 acetone double rubs (zinc phosphate pretreated steel).
Coating compositions formulated without lead, applied and cured as described above were removed by only 25 acetone double rubs over untreated JO steel and 37 acetone double rubs over zinc phosphate pretreated steel.

vamp e IX
The following example shows the preparation of a coating compost-lion containing a cross linking agent having three gamma-ester ester groups per molecule. The cross linking agent was formed by reacting trimellitic android with 1,3-propanediol and isobutyric acid in a 1:3:3 molar ratio.
The cross linking agent was mixed with a polymeric polyol as described in Example VIII, combined with lead octet catalyst and dispersed in water ~9~9~i 1 with the aid of acid. Steel panels were catholically electrocuted with the dispersion and the coating baked to give solvent-resistant coatings. Also, the mixture was dissolved in organic solvent, the solution drawn down on steel panels and the coated panels heated to give solvent-resist~nt coatings.

Cross linking Agent The cross linking agent was prepared from the following mixture of ingredients:

Weight Solids Ingredient in grams) (in grams) Equivalents Moles 10 Trimellitic android 80.1 80.1 1.252 0.417 1,3-propanediol 100.0 95.3 2.628 1.314 Isobutyric acid 110.3 110.3 1.252 1.252 Para-toluenesulfonic acid 1.0 1.0 Tulane 50-0 The ingredients were charged to a reaction vessel and heated to reflex under a nitrogen blanket until an acid value of 6.3 was obtained.

Aqueous Dispersion An aqueous dispersion of the cross linking agent prepared as described above and the polymeric polyol of Example VIII and lead catalyst was prepared as follows:

Weight Solids Ingredient (in gram sin grays) Equivalents Polymeric polyol of Example VIII 146.2 109.4 0.162 (amine) Cross linking agent 68.1 40.7 Lead octet 2.75 2.09 Lactic acid 7.48 0.073 Deionized water 790.1 - I -1 145 percent of the total theoretical neutralization.

The polymeric polyol and the cross linking agent were charged to a stainless steel beaker, followed by the addition of the lead octet. The ingredients were blended together followed by the addition of the lactic acid. The blend was then thinned with deionized water to form 14.4 per- -cent solids dispersion.
Untreated and zips phosphate pretreated steel panels were cathodic gaily electrocuted in the dispersion at 100 volts for 90 seconds. The coated panels were baked for 30 minutes at 180C. to form coatings having a thickness of about 0.9-1.1 mill The untreated steel panels withstood 39-41 acetone double rubs, whereas the coatings on the zinc phospbated panels withstood 16-21 acetone double rubs.

Organic Solvent-Based Coating Composition Weight Solids Ingredient (in grams) (in trams) Polymeric polyol 34.43 27.10 Cross linking agent 22.36 13.35 The above ingredients were charged to a 2-ounce glass jar and warmed and mixed to uniformity. The contents were transferred to a second 2-ounce glass jar and combined with 0.35 grams of lead octet (75 percent solids to form the coating composition.
The coating composition was drawn down on steel panels and cured at elevated temperature. The results are presented below:

I

Curing l Schedule Coating Thickness Acetone Panel F./minutes yin miss) Resistance Untreated steel 350/30 1.9 95-96 Zinc phosphate pretreated steel 350¦30 3.2 84 Untreated steel 400/30 2.0 131-175 Zinc phosphate pretreated steel 400/30 2.8-3.3 >175 lo Coating compositions formulated without lead, deposited and cured as described above had the following properties:

Curing ScheduleGoating Thickness Acetone Panel F./minutes (in miss) Resistance Untreated steel 350/30 1.7 30 Zinc phosphate pretreated steel 350/30 2.3 32 Untreated steel 400/30 2.2 89 Zinc phosphate 20 pretreated steel 400/30 4.0-4.2 91 Example X
The following example shows the preparation of a coating combo-session containing a cross linking agent having three gamma-ester ester groups per molecule as described in Example IX. The cross linking agent was mixed with a polymeric polyol as described below; the mixture dissolved in organic solvent and combined with lead octet catalyst. The coating composition was drawn down on steel panels and heated to give solvent-resistant coatings.

I

1 Polymeric Polyol The polymeric polyol was formed from chain extending a polygly-idyll ether of bisphenol A with a polyester dill. The adduce was then reacted with a mixture of amine, namely, monoethanolamines and the methyl-isobutyl diketimine of diethylene thiamine.

Weigh Solids Ingredients (in grams) (in grams) Equivalents Moles EON 8281 g53 7 g53 7 4.819 (epoxy) 2.41 POP owe 320.6 320.6 1.2 (OH) 0.6 10 Zillion 80.0 Bisphenol A 274.7 274.7 2.41 (OH) 1.205 Benzyldimethylamine 5.9 2-ethoxyethanol317.9 Methylisobutyl diketimine of diethylene Truman 85.7 61.9 0.232 (amine) 0.232 Monoethanolamine69.5 69.5 0.926 (amine) 0.926 lPolyglycidyl ether of bisphenol A having an epoxide equivalent of about 198 commercially available from Shell Chemical Company.
2Polycaprolactone dill having a molecular weight of about 545 commercially available from the Union Carbide Company.
solution in methylisobutyl kitten.

The EON 828, POP 0200 and zillion were charged to a reaction vessel and heated under a nitrogen blanket to reflex and held for 30 mint vies. The reaction mixture was cooled to 155C., followed by the addition of the bisphenol A. Benzyldimethylamine (1.9 grams) was added and the reaction mixture exothermed. The reaction mixture was cooled to 130C., followed by the addition of the remaining benzyldimethylamine and the reaction mixture held at 1~0C. until it attained a reduced Gardner-Holdt 1 viscosity (50 percent resin solids in 2-etho~yethanol) of No. The 2-ethoxyethanol, diketimine and monoethanolamine were then added and the reaction mixture nerd at 108-112C. for about one hour to complete the reaction.
To 24.23 grams (20.14 grams solids) of the polymeric polyol pro-pared as described immediately above was added 16.69 grams (9.96 grams solids) of the cross linking agent prepared as described in Example IX
and 5.6 grams of 2-ethoxyathanol. To a 20.01 gram sample (12.94 grams solids) of the mixture was added 0.23 grams of the lead octet solution as described in example VIII. The composition was drawn down with a draw bar over untreated and zinc phosphate pretreated steel panels and the panels heated to 350 F. (177 I for 30 minutes. The cured coatings over the untreated steel were 1.6 miss in thickness and withstood 150 acetone double rubs, whereas the coating over the zinc phosphate pretreated steel was 2.8 miss in thickness and withstood 75 acetone double rubs.
When comparable coatings were made without the use of the lead catalyst, the cured coatings withstood only from about 13 to 25 acetone double rubs.

Claims (29)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heat-curable coating composition comprising a hydroxyl-containing polymer, a polyester curing agent and a transesterification catalyst, characterized in that the polyester crosslinking agent has at lease two substituted ester groups per molecule in which the substituents are selected from the class consisting of:
(A) beta-alkoxy groups, (B) beta-ester groups, (C) beta-amido groups, (D) gamma-hydroxy groups, (E) gamma-ester groups, (F) delta-hydroxy groups;
including mixtures thereof.

2. The coating composition of Claim 1 in which the hydroxyl-containing polymer also contains cationic groups and the coating composi-tion is dispersed in an aqueous medium.

3. The coating composition of Claim 1 or 2 in which the hydroxyl-containing polymer has a hydroxyl value within the range of 180 to 300.

4. The coating composition of Claim 1 in which the sub-stituents are beta-alkoxy groups.

5. The coating composition of Claim 4 in which the polyester crosslinking agent is prepared from reacting a polycarboxylic acid or its functional equivalent thereof with one or more 1,2-polyol monoethers.

6. The composition of Claim 5 in which the polycarboxylic acid or its functional equivalent thereof is selected from the class consisting of trimellitic anhydride, adipic acid, and phthalic anhydride.

7. The composition of Claim 5 in which the 1,2-polyol monoether is an alkyl ether of ethylene or propylene glycol in which the alkyl group contains from 1 to 6 carbon atoms.

8. The composition of Claim 1 in which the substituents are gamma and/or delta-hydroxy groups.

9. The composition of Claim 8 in which the substituents are gamma-hydroxy groups.

10. The composition of Claim 9 in which the crosslinking agent is formed from reacting a polycarboxylic acid or its functional equivalent thereof with a 1,3-polyol.

11. The composition of Claim 10 in which the polycarboxylic acid or its functional equivalent thereof is selected from the class consisting of trimellitic anhydride, adipic acid and phthalic anhydride.

12. The composition of Claim 10 in which the 1,3-polyol is selected from the class consisting of trimethylolethane, trimethylolpropane, 1,3-butanediol, 1,3-propanediol and mixtures thereof.

13. The composition of Claim 8 in which the substituents are delta-hydroxy groups.

14. The composition of Claim 13 in which the crosslinking agent is formed from reacting a polycarboxylic acid or its functional equivalent thereof with a 1,4-polyol.

15. The composition of Claim 14 in which the 1,4-polyol is 1,4-butanediol.

16. The composition of Claim 1 in which the substituents are beta and/or gamma-ester groups.

17. The composition of Claim 16 in which the substituents are beta-ester groups.

18. The composition of Claim 17 in which the crosslinking agent is prepared from reacting:
(A) a polycarboxylic acid or its functional equivalent thereof, (B) a 1,2-polyol or 1,2-epoxy compound, (C) a monocarboxylic acid.

19. The composition of Claim 18 in which the 1,2-polyol is selected from the class consisting of ethylene glycol, propylene glycol, and 1,2-butanediol.

20. The composition of Claim 18 in which the 1,2-epoxy compound is selected from the class consisting of 1,2-epoxy butane, the glycidyl ester of a saturated aliphatic monocarboxylic acid containing from 9 to 12 carbon atoms, ethylene oxide, propylene oxide and n-butyl glycidyl ether.

21. The composition of Claim 16 in which the substituents are gamma-ester groups.

22. The composition of Claim 21 in which the crosslinking agent is formed from reacting:
(A) a polycarboxylic acid or its functional equivalent thereof, (B) a 1,3-polyol, (C) a monocarboxylic acid.

23. The composition of Claim 22 in which the 1,3-polyol is selected from the class consisting of 1,3-propanediol, trimethylolpropane, trimethylolethane and 1,3-butanediol.

24. The composition of Claim 18 or 22 in which the polycarboxylic acid or its functional equivalent thereof is selected from the class con-sisting of trimellitic anhydride, adipic acid and phthalic acid.

25. The composition of Claim 18 or 22 in which the monocarboxylic acid is selected from the class consisting of isobutyric acid, acetic acid, propionic acid and benzoic acid.

26. The coating composition of Claim 1 in which the sub-stituents are beta-amido groups.

27. The composition of Claim 26 in which the crosslinking agent is formed from reacting a polycarboxylic acid or its functional equivalent thereof with a beta-hydroxyalkylamide.

28. The composition of Claim 27 in which the beta-hydroxyl-alkylamide is of the structure:
where R1 and R2 are hydrogen and R1, R2 and R3 are selected from the class consisting of alkyl, cycloalkyl, aryl, alkaryl, including substituted radicals in which the substituents will not adversely affect the esterification reaction with the polycarboxylic acid or its functional equivalent thereof and will not adversely affect the transesterification curing reaction or the desirable properties of the coating composition.

29. The composition of Claim 27 in which the polycarboxylic acid or its functional equivalent thereof is selected from the class consisting of trimellitic anhydride, phthalic anhydride, and adipic acid.