US3640810A - Steam rinsing of electrocoated articles - Google Patents

Abstract

Method of removing dragout from an article which has been electrocoated, utilizing steam as a rinsing agent to remove the dragout. The use of steam produces a rinse water of appreciably higher solids than is achieved by the use of water.

Description

United States Patent Plasynski et al.

[ 1 Feb. 8, 1972 [54] STEAM RINSING OF ELECTROCOATED ARTICLES [72] Inventors: Joseph E. Plasynski, Arnold; Robert D.

Jerabek, Glenshaw, both of Pa.

[52] US. Cl ..204/181, 117/102, 134/37 [51] Int. Cl. ..BOlk 5/02, C23b 13/00 [58] Field ofSearch ..204/181; 134/37, 30,31, 10; 117/102'R, 102 L, 102 A [56] References Cited UNITED STATES PATENTS 3,501,390 3/1970 Turner ..204/181 3,146,122 8/1964 Renner et al. ....117/102 3,034,971 5/1962 Seaward ..204/181 X 3,462,286 8/1969 DeGeest et al... ....204/1 81 X 3,476,666 11/ 1969 Bell et a1 ..204/181 3,215,553 11/1965 Nawakowskiet a1... ....l17/102 X 3,152,918 10/1964 Kraus ....l17/102 X 3,231,415 1/1966 Grenley et a1. ..117/102 FOREIGN PATENTS OR APPLICATIONS 451,236 9/1948 Canada ....l17/l02 375,138 6/1932 Great Britain ..1 17/102 Primary Examiner-Morris O. Wolk Assistant Examiner-Joseph T. Zatarga AttorneyChisholm and Spencer [57] ABSTRACT Method of removing dragout from an article which has been electrocoated, utilizing steam as a rinsing agent to remove the dragout. The use of steam produces a rinse water of appreciably higher solids than is achieved by the use of water.

16 Claims, No Drawings STEAM RINSING OF ELECTROCOATED ARTICLES STATE OF THE ART Electrodeposition has become a widely commercially accepted industrial coating technique. The coatings achieved have excellent properties for many applications and electrodeposition results in a coating which does not run or wash off during baking. Virtually any conductive substrate may be coated by electrodeposition. Those normally employed are metal substrates, including metals such as iron, steel, copper, zinc, brass, tin, nickel, chromium, and aluminum, as well as other metals and pretreated metals. Impregnated paper and other substrates rendered conductive under the conditions of the coating process may also be employed as substrates.

In the electrodeposition process, the articles to be electrocoated are immersed in an aqueous dispersion of a solubilized, ionized, film-forming material such as a synthetic organic vehicle resin. An electric current is passed between the article to be coated, serving as an electrode, and a counterelectrode to cause deposition of a coating of the vehicle resin on the articleQ The article is then withdrawn from the bath, usually rinsed and the coating either air dried or baked in the manner of a conventional finish.

The rinse water obtained in an electrodeposition process represents an economic loss of coating materials and a waste disposal problem. The economic loss is occasioned by the fact that when the article is coated and is being withdrawn from the coating bath, the portion of the coating material which is not electrocoated on the article, but merely adherent thereto or trapped by the configuration of the article, is withdrawn with the article. This material is commonly called dragout. The purpose of the rinse water is to remove this dragout, leaving an adherent electrocoated film. This dragout, which is essentially a portion of the bath composition, when rinsed from the article represents waste material and reduces the efficiency of the system. Further, the rinse water containing the dragout comprises the waste disposal problem since many of the materials contained in this rinse water are undesirable in drain lines and are either unlawful under sewage codes or stream pollution or other disposal problems.

DESCRIPTION OF THE INVENTION It has now been found that articles having been electrocoated may be rinsed with steam. The resultant dragoutcontaining rinse water formed by the condensation of steam upon the article being rinsed is of appreciably higher solids than conventional rinse water and thus may more readily be returned to the electrodeposition bath without unduly diluting the bath composition or overflowing the electrodeposition bath. Secondarily, even if the rinse water obtained by the utilization of steam is at a solids level lower than that of the bath composition, and a secondary treatment is necessitated to increase the solids of the rinse before it is retumed to the electrodeposition bath, for instance, by use of an ultrafiltration process as described in copending application Ser. No. 814,789, filed Apr. 9, 1969, since the steam generates rinse waters of appreciably higher solids than conventional rinse waters, the amount of secondary treatment necessary and the duration of the treatment is greatly reduced. Again, even if the rinse water is of solids lower than that of the original bath and the rinse water is nevertheless returned to the bath, the bath composition may more readily be controlled by the use of a process involving the removal of water from the electrodeposition bath, for example, an ultrafiltration process as described in application Ser. Nos. 881,259, filed Dec. 1, I969 and 883,584, filed Dec. 9, 1969.

The steam utilized in the process of the invention may be steam from any source and may be high-pressure steam or low-pressure steam and includes the use of low-pressure steam which, upon release, comprises a visual steam which contains a substantial quantity of minute droplets of condensed water.

It has been further found that to increase the mechanical working force of this low-pressure steam impinging upon the surface of the article that admixture of steam and compressed air produces equally beneficial results.

It has been found that for effective dragout removal in the process of this invention the temperature generated at the surface of the panel should preferably be above about F. and preferably above F.

The steam may be delivered to the surface of the article being rinsed by various means known in the art. For example, it may be played upon the article by means of a flexible hose, by means of a head or orifice moving in relationship to the ar ticle or by means of a stationary head or series of heads or orifices with the panel passing in relationship to the stationary steam outlets. Likewise, the article may be passed through an enclosure of a steam-filled enclosure.

The resultant water containing dragout flowing from the article may be collected in a manner so that the dragout-containing water may be returned to the electrodeposition bath, or alternatively so that the rinse may either be subjected to a secondary concentration treatment before returning to the electrodeposition bath or, if desired, the dragout-containing rinse water may be discarded with or without preliminary treatment.

A number of electrodeposition resins are known and can be employed to provide the electrodepositable compositions which may be utilized within the scope of this invention. Virtually any water-soluble, waterdispersible, or water-emulsifiable polyacid or polybasic resinous material can be electrodeposited and, if film-forming, provides coatings which may be suitable for certain purposes. Any such electrodepositable composition is included among those which can be employed in the present invention, even though the coating obtained might not be entirely satisfactory for certain specialized uses.

Presently, the most widely used electrodeposition vehicle resins are synthetic polycarboxylic acid resinous materials. Numerous such resins are described in US. Pat. Nos. 3,441,489; 3,422,044; 3,403,088; 3,369,983 and 3,366,563, which are incorporated by reference. These include a reaction product or adduct of the drying oil or semidrying oil fatty acid ester with a dicarboxylic acid or anhydride. By drying oil or semidrying oil fatty acid esters are meant esters of fatty acids which are or can be derived from drying oils or semidrying oils, or from such sources as tall oil. Such fatty acids are characterized by containing at least a portion of polyunsatu rated fatty acids. Preferably, the drying oil or semidrying oil per se is employed.

Also included among such esters are those in which the esters themselves are modified with other acids, including saturated, unsaturated or aromatic acids or an anhydride thereof. The acid-modified esters are made by transesterification of the ester, as by forming a dior monoglyceride by alcoholysis, followed by esterification with the acid; they may also be obtained by reacting oil acids with a polyol and reacting the acid with the partial ester. In addition to glycerol, alcoholysis can be carried out using other polyols such as trimethylolpropane, pentaerythritol, sorbitol and the like. If desired, the esters can also be modified with monomers such as cyclopentadiene or styrene and the modified esters produced thereby can be utilized herein. Similarly, other esters of unsaturated fatty acids, for example, those prepared by the esterification of tall oil fatty acids with polyols, are also useful.

Also included within the term drying oil fatty acid esters" as set forth herein are alkyd resins prepared utilizing semidrying or drying oils; esters of epoxides with such fatty acids, including esters of diglycidyl ethers of polyhydric compounds as well as other mono-, diand polyepoxides, semidrying or drying oil fatty acid esters of polyols, such as butanediol, trimethylolethane, .trimethylolpropane, trimethylolhexane, pentaerythritol, and the like; and semidrying or drying fatty acid esters of resinous polyols such as homopolymers or copolymers of unsaturated aliphatic alcohols, e.g., allyl alcohol or methallyl alcohol, including copolymers of such alcohols with styrene or other ethylenically unsaturated monomers or with nonoil modified alkyd resins containing free hydroxyl groups.

Any alpha, beta-ethylenically unsaturated dicarboxylic acid or anhydride can be employed to produce the reaction products described herein. These include such anhydrides as maleic anhydride, itaconic anhydride, and other similar anhydrides. Instead of the anhydride, there may also be used ethylenically unsaturated dicarboxylic acids which form anhydrides, for example, maleic acid or itaconic acid. These acids appear to function by first forming the anhydride. Fumaric acid, which does not form an anhydride, may also be utilized, although in many instances it requires more stringent conditions than the unsaturated dicarboxylic acid anhydrides or acids which form such anhydrides. Mixtures of any of the above acids or anhydrides may also be utilized. Generally speaking, the anhydride or acid employed contains from four to 12 carbon atoms, although longer chain compounds can be used if so desired.

While the reaction products can becomprised solely of adducts of the fatty acid ester and the dicarboxylic acid or anhydride, in many instances it is desirable to incorporate into the reaction product another ethylenically unsaturated monomer. The use of such monomer often produces films and coatings which are harder and more resistant to abrasion and which may have other similardesirable characteristics.

As shown in the art, it is preferred that in certain instances the neutralization reaction can be carried out in such a manner that amide groups are attached to part of the carbonyl carbon atoms derived from the dicarboxylic acid or anhydride.

Compositions within this general class are described in U.S. Pat. Nos. 3,366,563 and 3,369,983.

Another vehicle comprises the fatty acid ester, unsaturated acid or anhydride reaction products and any additional unsaturated modifying materials (as described above) which are further reacted with the polyol.

Essentially any polyol can be employed, but diols are preferred. When higher polyols, such as trimethylolpropane, glycerol, pentaerythritol and the like are utilized, they are employed in small amounts, or in conjunction with the diol, or in the presence of a monohydric alcohol, and are used with adducts having a relatively low proportion of acidic component. Water-insoluble diols are often preferable, and especially desirable water-dispersed compositions for electrodeposition are obtained using 2,2-bis(4-hydroxycyclohexyl)propane (which has given the best results), neopentyl glycol, 1,1 isopropylidene-bis(p-phenyleneoxy)di-Z-propanol, and similar diols.

The proportions of the polyol and ester-anhydride adduct which are employed depend upon various factors, but are in general limited only by the need to avoid gelation of the product. The total functionality of the reactants is a guide to determining the optimum proportions to be employed, and in most instances should not be greater than about two.

In many instances, only part of the anhydride groups of the adduct, e.g., about percent, are reacted with the polyol. Of those anhydride groups reacted, it is preferred that only one of the carboxyl groups is esterified in each instance.

The product contains a substantial part of the original acidity derived from the dicarboxylic acid or anhydride; ordinarily the product should have an acid number of at least 20. To provide a water-dispersed product, such as is used in electrodeposition processes, at least part of the remaining acidic groups are neutralized by reaction of the partially-esterified product with a base.

The polyol reaction products and reaction conditions are more fully described in application Ser. No. 450,205, filed Apr. 22, 1965, as well as in the art cited above.

Another t of electrodepositable coating composition which gives'd'es ble results are the water-dispersible coating compositions prising at least partially neutralized interpolymers of hydroxyalkyl esters of unsaturated dicarboxylic acid, unsaturated carboxylic acids and at least one other ethylenically unsaturated monomer. These are employed in the composition along with an amine-aldehyde condensation product, with the interpolymer usually making from about 50 percent to about percent by weight of the resinous composition.

The acid monomer of the interpolymer is usually acrylic acid or methacrylic acid, but other ethylenically unsaturated monocarboxylic and dicarboxylic acids of up to about six carbon atoms can also be employed. The hydroxyalkyl ester is usually hydroxyethyl or hydroxypropyl acrylate or methacrylate, but also desirable are the various hydroxyalkyl esters of the above acids having, for example, up to about five carbon atoms in the hydroxyalkyl radical. Monoor diesters of the dicarboxylic acids mentioned are included. Ordinarily the acid and ester each comprise between about 1 percent and about 20 percent by weight of the interpolymer, with the remainder being made up of one or more other copolymerizable ethylenically unsaturated monomers. The most often used are the alkyl acrylates, such as ethyl acrylate; the alkyl methacrylates, such as methyl methacrylate; and the vinyl aromatic hydrocarbons, such as styrene, but others can be utilized.

The above interpolymer is at least partially neutralized by reaction with a base as described above; at least about 10 percent, and preferably 50 percent or more of the acidic groups are neutralized, and this can be carried out either before or after the incorporation of the interpolymer in the coating composition.

The amine-aldehyde condensation products included in these compositions are, for example, condensation products of malamine, benzoguanamine, or urea with formaldehyde, although other amine-containing amines and amides, including triazines, diazines, triazoles, guanadines, guanamines and alkyl and aryl substituted derivatives of such compounds can be employed, as can be employed, as can other aldehydes, such as acetaldehyde. The alkylol groups of the products can be etherified by reaction with an alcohol, and the products utilized can be water-soluble or organic solvent-soluble.

Electrodeposition compositions comprising the above interpolymers and an amine-aldehyde resin are more fully described in U.S. Pat. No. 3,403,088.

Still another electrodepositable composition of desirable properties comprises an alkyd-amine vehicle, that is, a vehicle containing an alkyd resin and an amine-aldehyde resin. A number of these are known in the art and may be employed. Preferred are water-dispersible alkyds such as those in which a conventional alkyd (such as a glyceryl phthalate resin), which may be modified with drying oil fatty acids, is made with a high-acid number (e.g., 50 to 70) and solubilizred with ammonia or an amine, or those in which a surface active agent, such as a polyalkylene glycol (e.g., Carbowax") is incorporated. High-acid number alkyds are also made by employing a tricarboxylic acid, such as trimellitic acid or anhydride, along with a polyol in making the alkyd.

The above alkyds are combined with an amine-aldehyde resin, such as those described hereinabove. Preferred are water-soluble condensation products of melamine or a similar triazine with formaldehyde with subsequent reaction with an alkanol. An example of such a product is hexakis(methoxymethyl)mela.mine.

The alkyd-amine compositions are dispersed in water and they ordinarily contain from about 10 percent to about 50 percent by weight of amine resin based on the total resinous components.

Yet another electrodepositable composition of desirable properties comprises mixed esters of a resinous polyol. These resin esters comprise mixed esters of an unsaturated fatty acid adduct. Generally the polyols which are utilized with these resins are essentially any polyol having a molecular weight between about 500 and about 5,000. Such resinous polyols include those resinous materials containing oxirane rings which can beopened in, prior to, or during the esterification reaction to provide an apparent hydroxy site. The vehicle resins are formed by reacting a portion of the hydroxyl groups of the polyol with the fatty acid, the ratio of the reactions being such that at least an average of one hydroxyl group per molecule of the polyol remains unreacted. The remaining functionality is then reacted with the unsaturated fatty acid adduct of an olefinically unsaturated dicarboxylic anhydride, such as maleic anhydride, this second esterification reaction being conducted under conditions so that esterification occurs through the anhydride ring, thereby introducing free acid groups into the molecule. Mixed acids of the class described are disclosed in Belgian Pat. No. 641,642, as well as in copending application Ser. No. 568,144, filed July 27, 1966.

In order to produce an electrodepositable composition, it is necessary to at least partially neutralize the acid groups present with a base in order to disperse the resin in the electrodeposition bath. Inorganic bases such as metal hydroxides, especially potassium hydroxide, can be used. There may likewise be used ammonia or organic bases, especially watersoluble amines, such as, for example, the mono-, diand trilower alkyl amines such as methylarnine, ethylamine, propylamine, butylamine, dimethylarnine, diethylarnine, dipropylamine, dibutylarnine, and m-methyl-butylamine, triethylamine, tributylarnine, methyldiethylarnine, dimethylbutylamine, and the like; cyclic amines such as morpholine, pyrrolidine, piperidine; diarnines such as hydrazine, methylhydrazine, 2,3-toluene diamine, ethyl diamine and piperizine and substituted amines such as hydroxylarnine, ethanolamine, diethanolamine, butanolamine, hexanolarnine and methyldiethanolantine, octanolamine, diglycolarnine, and other polygylcolarnines, triethanolarnine, and methylethanolamine, namino-ethanolamine and methyldiethanolarnine and polyamines such as diethylene triarnine.

There may be present in the electrodepositable composition any of the conventional types of pigments employed in the art. There is often incorporated into the pigment composition a dispersing or surface-active agent. Usually the pigment and surface-active agent, if any, are ground together in a portion of the vehicle, or alone, to make a paste and this is blended with the vehicle to produce a coating composition.

In many instances, it is preferred to add to the bath in order to aid in dispersibility, viscosity and/or film quality, a nonionic modifier or solvent. Examples of such materials are aliphatic, naphthenic and aromatic hydrocarbons or mixtures of the same; monoand dialkyl ethers of glycols, pine oil and other solvents compatible with the resin system. The presently preferred modifier is 4-methoxy-4-methyl-pentanone-2 (Pent- Oxone).

There may also be included in the coating composition, if desired, additives such as antioxidants. For example, orthoamylphenol or cresol. It is especially advantageous to include such antioxidants in coating compositions which are used in baths which may be exposed to atmospheric oxygen at elevated temperatures and with agitation over extended periods of time.

Other additives which may be included in coating compositions, if desired, include,\for example, wetting agents such as petroleum sulfonates, sulfated fatty amines, or their amides, esters of sodium isothionates, alkyl phenoxypoly-ethylene alkanols, or phosphate esters including ethoxylated alkylphenol phosphates. Other additives which may be employed include antifoaming agents, suspending agents, bactericides, and the like.

In formulating the coating composition, ordinary tap water may be employed. However, such water may contain a relatively high level of metals and cations which, while not rendering the process inoperative, may result in variations of properties of the baths when used in electrodeposition. Thus, in common practice, deionized water, i.e., water from which free ions have been removed by the passage through ion exchange resins, is invariably used to make up coating compositions of the instant invention.

In addition to the electrodepositable vehicle resins described above, there may be present in the electrodepositable composition other resinous materials which are noncarboxylic acid materials. For example, as shown above, there may be added up to about 50 percent by weight of an aminealdehyde condensation product.

Other base-solubilized polyacids which may be employed as electrodeposition vehicles include those taught in US. Pat. No. 3,392,165, which is incorporated herein by reference, wherein the acid groups rather than being solely polycarboxylic acid groups contain mineral acid groups such as phosphonic, sulfonic, sulfate and phosphate groups.

The process of the instant invention is equally applicable to cationic type vehicle resins, that is, polybases solubilized by means of an acid, for example, an amine-terminated polyamide or an acrylic polymer solubilized with acetic acid. Another case of such cationic polymers is described in copending application Ser. No. 772,366, filed Oct. 28, 1968.

In a manner similar to the anionic resins described above, the cationic resins may be formulated with adjuvants, such as pigments, solvents, surfactants, cross-linking resins, and the like.

The polyacids are anionic in nature and are dispersed or dissolved in water with alkaline materials such as amines or alkaline metal hydroxides and, when subjected to an electric current, they migrate to the anode. The polybasic resins, solubilized by acids, are cationic in character and when these resins are water-dispersed or solubilized with an acid such as acetic acid, the material deposits on the cathode under an electric current.

The invention is further described in conjunction with the following example which is to be considered illustrative rather than limiting. All parts and percentages in the example and throughout this specification are by weight unless otherwise stated.

EXAMPLE I The principle vehicle resin in this example is a maleinized tall oil fatty acid ester of a styrene-allyl alcohol copolymer of 1,100 molecular weight and 5 hydroxyl functionality, comprising 38.5 percent of the copolymer, 55 percent tall oil fatty acids and 6 percent maleic anhydride with a viscosity of 120,000 centipoises and an acid value of 41. There was also present in the composition a minor amount of bodied 20 percent maleinized linseed oil containing 3 percent cresylic acid and having a viscosity of 57,000 centipoises and an acid value of 82. The electrodepositable composition had the following composition:

The bath contained 16.3 percent solids with a pH of 8.95.

The articles coated in this example were zinc phosphate pretreated steel panels (Bonderite 40) 4X 1 2 inches dipped 8% inches. All panels were drained 1 minute after electrocoating and prior to any rinsing operation or testing. The amount of rinse employed was that minimum amount which visually, to an experienced operator, was sufficient to remove dragout. The rinse was collected in a beaker below the panel being rinsed. Rinse temperatures were measured in the rinse stream just prior to impinging on the panel. All panels were baked in a horizontal position at 360 F. for 25 minutes. The panels were checked for water or paint spotting or edge beading. The panels were coated at 420 volts for 2 minutes (75 F.).

tained 7.4 percent solids. Poor dragout removal. Baked panel showed edge beading and water spotting. Panel E panel rinsed with 200 F. tap water delivered through a paint spray gun at 60 p.s.i. open gun pressure. Temperature at panel 59 F. Rinse water contained 0.7 percent solids. Poor dragout removal. Baked panel appearance showed water spotting. Panel F Steam rinse delivered through a flexible pressure hose onefourth inch in diametertemperature at panel 140 F. Effective dragout removal. Rinse water contained 8.5 percent solids. Baked panel appearance good-no spotting. Panel G Steam rinse. Temperature at panel 104 F. Effective removal of dragout. Rinse water contained 9.3 percent solids. Baked panel appearance good. No spotting. Panel H Steam-air rinsemixture of steam and compressed air delivered through a Y-hose arrangement. Temperatures at panel 95 F. Effective removal of dragout. Rinse water contained 11.8 percent solids. Baked panel appearance good-mo spotting. Panell Steam-air rinsemixture of steam and air delivered through a Y-hose arrangement. Temperature at panel 86 F. Fair dragout removal. Rinse water contained 13.6 percent solids. Baked panel appearance fair to goodslight water spotting. Panel J Steam-air rinsemixture of steam and air delivered through a Y-hose arrangement. Temperature at panel 77 F. Incomplete dragout removal. Rinse water contained 12.5 percent solids. Water spots on baked panel.

Other electrodepositable compositions, such as those herein described, can be substituted for those exemplified. Likewise, various other means of delivering steam to the face of the article being rinsed may be employed. The steam may be of any type or from any source. Thus, various compositions and method variations may be employed to obtain the improvements hereinabove described.

According to the provisions of the patent statutes, there are described above the invention and what are now considered its best embodiments; however, within the scope of the appended claims, it is to be understood that the invention can be practiced otherwise than as specifically described.

We claim:

1. A method of removing dragout from an article electrocoated in an electrodeposition bath comprising a synthetic resin ionically solubilized in an aqueous medium which comprises employing steam as a rinsing agent.

2. A method as in claim 1 wherein the resin is a base-solubilized synthetic synthetic polyacid resin.

3. A method as in claim 1 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.

4. A method as in claim 1 wherein the rinsing agent comprises a mixture of a compressed as and steam.

5. A method as In claim 1 w erein the resultant dragoutcontaining rinse water is returned to the electrodeposition bath.

6. A method as in claim 5 wherein the resin is a base-solubilized synthetic polyacid resin.

7. A method as in claim 5 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.

8. A method as in claim 5 wherein the rinsing agent comprises a mixture of a compressed gas and steam.

9. A method as in claim 1 wherein the temperature of the rinsing agent is at least about F. at the surface of the article.

10. A method as in claim 9 wherein the resin is a base-solubilized synthetic polyacid resin.

11. A method as in claim 9 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.

12. A method as in claim 9 wherein the rinsing agent comprises a mixture of a compressed gas and steam.

13. A method as in claim 9 wherein the resultant dragoutcontaining rinse water is returned to the electrodeposition bath.

14. A method as in claim 13 wherein the resin is a base-solubilized synthetic polyacid resin.

15. A method as in claim 13 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.

16. A method as in claim 13 wherein the rinsing agent comprises a mixture of a compressed gas and steam.

Claims (15)

1. 2. A method as in claim 1 wherein the resin is a base-solubilized synthetic synthetic polyacid resin.
2. 3. A method as in claim 1 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.
3. 4. A method as in claim 1 wherein the rinsing agent comprises a mixture of a compressed gas and steam.
4. 5. A method as in claim 1 wherein the resultant dragout-containing rinse water is returned to the electrodeposition bath.
5. 6. A method as in claim 5 wherein the resin is a base-solubilized synthetic polyacid resin.
6. 7. A method as in claim 5 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.
7. 8. A method as in claim 5 wherein the rinsing agent comprises a mixture of a compressed gas and steam.
8. 9. A method as in claim 1 wherein the temperature of the rinsing agent is at least about 90* F. at the surface of the article.
9. 10. A method as in claim 9 wherein the resin is a base-solubilized synthetic polyacid resin.
10. 11. A method as in claim 9 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.
11. 12. A method as in claim 9 wherein the rinsing agent comprises a mixture of a compressed gas and steam.
12. 13. A method as in claim 9 wherein the resultant dragout-containing rinse water is returned to the electrodeposition bath.
13. 14. A method as in claim 13 wherein the resin is a base-solubilized synthetic polyacid resin.
14. 15. A method as in claim 13 wherein the resin is a synthetic polycarboxylic acid resin solubilized with a base selected from the group consisting of water-soluble amine and potassium hydroxide.
15. 16. A method as in claim 13 wherein the rinsing agent comprises a mixture of a compressed gas and steam.