JPH03281672A - Cathodic electrodeposition primer containing water-insoluble organic lead compound as corrosion inhibitor - Google Patents

Abstract

PURPOSE: To obtain a coating compsn. cured as a hard durable film excellent in corrosion resistance when bonded to a conductive substrate as a film by an aq. cathodic electrodeposition method and cured by adding a cathode electrodepositing resin compsn, a crosslinking agent and a specific organolead compd.

CONSTITUTION: A cathodic electrodeposition resinous coating compsn. contains a cathodic electrodeposition resin compsn. (e.g.; selected from an amine epoxy resin adduct and an amine functional acryl resin) (A), a crosslinking agent (e.g.; blocked polyisocyanate) (B) and an organolead compd. (e.g. lead naphthenate) (C) composed of water-insoluble lead salt of a 6 or more C aliphatic acid being liquid or becoming liquid at a time of the mixture with a suitable org. solvent or oil or becoming liquid paste at a time of the mixture with a suitable org. solvent or oil, and is cured as a hard durable film having excellent corrosion resistance when bonded to a conductive substrate by an aq. cathodic electrodeposition method without requiring any additional catalyst.

COPYRIGHT: (C)1991,JPO

Description

Detailed Description of the Invention Technical Field The technical field to which the present invention relates is an electrodepositable resin composition, more specifically an electrodepositable resin containing a crosslinking agent used in a cathodic electrodeposition coating method. It is a composition.

BACKGROUND OF THE INVENTION Electrodeposition of aqueous cathode resin compositions onto electrically conductive substrates is well known in the coatings art. BACKGROUND OF THE INVENTION Coating automobile frames and sheet metal with anticorrosive electrodeposited cathodic aqueous film-forming resin compositions that cure into hard durable protective coatings is a standard practice in automobile construction. The use of electrodeposited brimer coatings has allowed automobile manufacturers to provide long-term warranties that cover body corrosion. Additionally, these electrodeposited coatings are used by manufacturers of a variety of products including trucks, construction equipment, appliances, automotive parts, and the like.

In a typical cathodic electrodeposition process, an aqueous bath is prepared from a primary resin solution or emulsion and a pigment paste. The base resin solution or emulsion is typically an acrylic containing epoxy-amine resin adduct or amine-functional monomer that can be salted with acid to solubilize the base resin in water. Contains a polymer and a crosslinking agent. Typical crosslinkers include blocked polyisocyanates and aminoblast crosslinkers. Pigment pastes typically consist of a mixture of pigment and a specifically designed and formulated epoxy-amine resin adduct (known as a grind resin) that has been salted with an acid. The pulverized resin and pigment are pulverized together to prepare a pigment paste.

The pigment paste is mixed with the main emulsion and distilled water at the coating site to prepare an aqueous coating bath with the desired solids concentration. Aqueous coating baths are typically contained within an insulated tank having sufficient volume to completely immerse all articles to be coated.

Additives customary in the art, such as organic coalescing solvents, may be added to the bath to improve the coating properties.

The article to be coated typically consists of a conductive key material. The article is connected to a DC circuit to act as a cathode. The tank contains the anode or itself serves as the anode of the DC circuit. When an object is immersed in the coating bath (contained in the coating tank), an electric current across the object causes the main emulsion and pigment paste, along with the additives, to be deposited on the surface of the article.

Once the desired thickness of film has been deposited, the article is typically removed from the bath and optionally rinsed with distilled water. The article with the attached film is then typically placed in an oven where the film is cured into a smooth, hard, durable crosslinked coating.

Cathodic electrodepositable amine-epoxy resin adduct compositions, methods for making these cathodic electrodepositable resin compositions, aqueous cathodic electrodepositable coating baths and methods for depositing these resins from coating baths onto conductive objects are disclosed in the United States. Patent Sections 3.984,299, 3,468,770, 4.116,900, 4,093,594, 4,137,140 , Specification No. 4,104.147, Specification No. 4,225,478, Specification No. 4,419,467, Specification No. 4.432.850, Specification No. 4,575,523 , and No. 4,575,
No. 524.

Cathodically electrodeposited acrylic resin compositions, methods of preparation, aqueous cathodic coating baths, and methods of electrodepositing these compositions are described in U.S. Patent Section 3.883.
, 483 and 3.853.803.

Cathodic electrodepositable resin coatings, also known as "electrodeposits" or "E-coats," provide superior corrosion-resistant brimer coatings on metal substrates. Cationic E-coats are known to provide superior protection to steel substrates compared to anodic resin compositions. In the automotive industry, these coatings are typically overcoated with decorative protective multilayer top coatings, such as industry standard internal basecoat, external clear topcoat coating systems.

The incorporation of lead pigments, typically lead silicate, lead silicochromate and/or lead chromate into the electrodeposition coating bath is a bractis in the art. Lead is believed to serve as a corrosion inhibitor. It adheres to the cathodic E-coat and enhances the corrosion inhibiting properties of the E-coat. However, there are disadvantages currently associated with the use of lead compounds in cathodic electrodeposition.

First, lead compounds are typically introduced into the E-coat coating bath by incorporating lead pigment into the coating bath. Lead pigments tend to settle and foul bath tanks, piping, pumps, filters, and related equipment.

Sedimentation of lead pigments creates fouling in the electrodeposition film and also creates sludge buildup in tanks and process equipment. This sludge must be disposed of as waste. There have been attempts to remove lead pigments from coating baths. Cathodic coating baths containing soluble lead salts are described in U.S. Patent Section 4.11.
No. 5,226. It is difficult to control the amount of soluble lead, such as lead acetate and lead lactate, in coating baths containing soluble lead. Excess amounts of water-borne lead are typically present resulting in higher than acceptable conductivity, resulting in inadequate coating bath throwage and unacceptable coatings. Furthermore, lead pigments cannot be introduced into the coating bath as dry pigments. They must be milled with specially designed and formulated E-coat milling resins to prepare lead additive pastes or lead-containing pigment pastes. The lead additive paste is then added to the cathode E-coat coating bath. The grinding process is typically a lumpy operation and extensive environmental controls are required to prevent operator exposure to airborne lead particulates.

Tin catalysts such as dibutyltin oxide are typically
It is added to aqueous cathodic electrodeposition coating baths to catalyze the crosslinking reaction. The catalyst is a dry powder that must be added to the E-coat coating bath as part of the pigment paste. Grinding and dispersing catalysts into pigment pastes is extremely difficult.

Furthermore, it is difficult to maintain the catalyst in suspension in an aqueous coating bath and the catalyst tends to settle. Liquid type tin catalysts, e.g. dibutyltin dilaurate, are
It is thought to be a inducing agent.

What is needed in this technology are cathodic electrodeposition coating compositions, coating baths, and coating methods that do not require solid lead pigments, water-soluble lead components, or tin catalysts.

DISCLOSURE OF THE INVENTION Novel aqueous cathodically depositable resinous coating compositions are disclosed. The coating composition includes an electrodeposited exogenous resin composition, a crosslinking agent, and an organolead compound consisting of a water-insoluble lead salt of an aliphatic acid having at least 6 carbon atoms or a water-insoluble lead salt of an aromatic carboxylic acid.

As used throughout this disclosure, the term "insoluble lead salt" means a lead salt that has a solubility of less than 0.305 parts per 100 parts of water at 25°C. The coating composition is deposited as a film on a conductive substrate by aqueous cathodic electrodeposition and has excellent corrosion resistance without the need for lead pigments or tin catalysts when cured to a hard durable coating.

Another aspect of the invention is an article coated with an aqueous cathodically depositable resinous coating composition.

The coating composition includes an electrodepositable main resin composition, a crosslinking agent, and an organic lead compound consisting of a water-insoluble lead salt of an aliphatic acid having at least 6 carbon atoms or a water-insoluble lead salt of an aromatic carboxylic acid. The coating composition when deposited as a film on an article by cathodic electrodeposition has excellent corrosion resistance without the need for lead pigments or tin catalysts.

Yet another aspect of the invention is an aqueous cathodic electrodeposition coating bath. The coating bath is an organic lead compound consisting of an acid-salted electrodepositable main resin composition, a crosslinking agent, and a water-insoluble salt of an aliphatic acid having at least 6 carbon atoms or a water-insoluble salt of an aromatic carboxylic acid. including. The coating is electrolytically cured from a bath onto a substrate and hardened into a hard durable film.
Has excellent corrosion resistance without the need for lead pigments or tin catalysts.

Yet another aspect of the invention is an improved cathodic electrodeposition process for aqueous coating compositions. The essence consists of preparing an aqueous cathodic electrodeposition coating bath (the coating bath comprises an aqueous cathodic electrodeposition main resin composition and a crosslinking agent).

The bath is contained in an electrically insulating container containing the anode.

A conductive article connected to an electrical circuit to act as a cathode is then immersed in the bath and sufficient electrical power is passed across the article such that a film of coating composition is deposited on the surface of the article. The article is then removed from the coating bath and
The film cures into a hard, durable coating. The improvement consists in incorporating at least one organic lead compound into the coating bath. The organic lead compound consists of a water-insoluble lead salt of an aliphatic acid having at least 6 carbon atoms or a water-insoluble lead salt of an aromatic carboxylic acid. The resulting coatings containing organolead compounds have excellent corrosion resistance and cure to hard durable coatings without the need for lead pigments or tin catalysts.

The above features and advantages and other features and advantages of the invention will become more apparent from the description below.

DETAILED DESCRIPTION OF THE INVENTION The organic lead compounds of the present invention include water-insoluble lead salts of aliphatic acids having at least 6 carbon atoms and water-insoluble lead salts of aromatic carboxylic acids. The lead compound may be a liquid or a solid that is soluble in an organic medium or a solid that upon mixing with a suitable organic medium such as a solvent, oil, etc. prepares a liquid paste. . Particularly preferred lead salts include lead 2-ethylhexanoate, lead naphthenate, lead octoate, lead stearate, lead dodecanoate, and lead oleate.

Useful blocked polyisocyanates for use as crosslinking agents in the coating compositions of the present invention include those that are stable in dispersion at normal room temperatures and that react with the resinous products of the present invention at elevated temperatures. Can be mentioned.

Any suitable organic polyisocyanate can be used in forming the blocked organic polyisocyanate.

Typical examples are trimethylene, tetramethylene, pentamethylene, hexamethylene, 1°2-propylene, 1,2-
Aliphatic compounds such as butylene, 1,3-butylene diisocyanate: 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate; m-phenylene, p-phenylene, 4,4'-diphenyl, 1,4-
Aromatic compounds such as xylylene diisocyanate; triphenylmethane-4,4', 4'-4lysonanate, 1. ．． 3.5 ~ Benzene triisocyanate, 2
．． 4.6-) Triisocyanates such as luent isonanate; and tetraisocyanates such as 44'-diphenyldimethylmethane-2,2', 5°5'-tetraisocyanate; toluene diisocyanate dimer, trimer, etc. These include polymerized polyisocyanate, polymethylene polyphenylene polyisocyanate having 2 to 3 -N-C-0 functional groups, and the like.

In addition, organic polyisocyanates can be added to polyols such as glycols, such as ethylene glycol and propylene glycol, as well as other polyols, such as glycerol, trimethylolpropane, hexanetriol,
It can be a prepolymer derived from an alkylene oxide condensate of the foregoing, such as pentaerythritol, or monoethers such as diethylene glycol, tripropylene glycol, polyethers, or the like.

Among the alkylene oxides that may be condensed with these polyols to form polyethers are ethylene oxide, propylene oxide, butylene oxide, styrene oxide, and the like.

These are commonly referred to as hydroxy-terminated polyethers and can be linear or branched.

Particularly preferred polyether polyols include polyols,
For example, ethylene glycol, diethylene glycol,
Triethylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,6-benzenediol, and mixtures thereof; glycerol, trimethylolethane, trimethylolpropane, 1,2,6-
Hexanetriol, pentaerythritol, dipentaerythritol, tripentaerythritol, polypentaerythritol, sorbitol, methyl glucoside,
It is derived from the reaction of sucrose and the like with alkylene oxides such as ethylene oxide, propylene oxide, mixtures thereof, and the like.

Particularly preferred polyisocyanates include the reaction product of toluene diisocyanate and trimethylolpropane and the isocyanurate of hexamethylene diisocyanate (a trimer of 16-hexamethylene diisocyanate).

Blocking agents that can be used to block polyisocyanates and polyether polyol polyisocyanate adducts are known in the art. Any suitable aliphatic, cycloaliphatic, aromatic, alkyl monoalcohols and phenolic compounds and secondary amine compounds, such as methyl alcohol, ethyl alcohol, chloroethyl alcohol, propyl alcohol, butyl alcohol, amyl alcohol, hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol,
Lower aliphatic alcohols such as 3,3.5-trimethylhexyl alcohol, decyl alcohol, and lauryl alcohol; Aromatic alkyl alcohols such as phenylcarpitol and monoethyl ether, monobutyl ether, and monopropyl ether of ethylene glycol; Phenol itself, substituted Phenolic compounds, such as phenols whose substituents do not adversely affect coating operations, can also be used as blocking agents in the practice of this invention.

Examples of the latter include cresol, nitrophenol, chlorophenol, t-butylphenol, secondary amines such as dibutylamine, and hydroxy-containing esters.

Preferred blocking agents include monopropyl ether of ethylene glycol and dibutylamine. Additional blocking agents include t-hydroxylamines such as diethylethanolamine and oximes such as methyl ethyl ketoxime, acetone oxime, cyclohexanone oxime, and caprolactam. Another preferred oxime is methyl-0-amylketoxime.

The cathodically depositable primary resin composition of the present invention includes an epoxy resin that reacts with an amine to form an adduct, and an amine-functional acrylic copolymer. In some cases, epoxy resin
Chain extension may result in an increase in the molecular weight of the epoxy molecule by reaction with water-miscible or water-soluble polyols.

The epoxide used in the practice of this invention is the polyepoxide typically used in this art and consists of a resinous material containing at least one epoxy per molecule.

Aminoplast crosslinkers useful in the practice of this invention include:
The following types: highly methylated, partially methylated and containing a methylol function, methylated and containing an imino function, highly butylated,
partially butylated and containing a methylol functionality; butylated and containing an imino functionality;
mixed methylated/butylated, mixed methylated/butylated and containing a methylol function, mixed methylated/butylated and containing an imino function, or 1 to 6 moles per mole of melamine. Alkylated melamine-formaldehyde resins are mentioned, including such melamine-formaldehyde resins characterized as one of the other melamines that can be prepared by fully or partially etherifying the reaction product of formaldehyde with an alcohol. . Examples of suitable commercially available melamine-formaldehyde resins include Cymel@300, Cymel@3 from American-Cyanamide Company (Plastics Division, Wallingford, Conn. 06492);
01, Shimel o303, Shimel o350, Shimel ■32
3, Shimel ■325, Shimel o327, Shimel o370
, Shimel ■373, Shimel ■380, Shimel o385,
Schimmel o1116, Schiller o1130. Schimel @ 1133, Schimel ■]] 68, Schimel ■] 156, Schimel @ 1158 and the regimen (Resi
mene@) 891, regimen o882, regimen o
881, Regimen o879, Regimen o876, Regimen o875, Regimen ■872, Regimen o747, Regimen ■746, Regimen ■745, Regimen o74]
, Regimen o740, Regimen ■735, Regimen ■7
31, Regimen o7301 Regimen o717, Regimen ■714, Regimen o712, Regimen ■764, Regimen o755, Regimen 0753, Regimen ■750
can be mentioned. Aminoblast crosslinkers useful in the practice of this invention include those partially or fully etherified with a suitable alcohol, typically methanol or butanol or mixtures thereof and with methylol and/or imino functional groups. Also included are benzoguanamine-formaldehyde resins which may contain groups. An example of this type of crosslinker is American cyanamide.
Mention may be made of the commercial product Schimel@1.123 from the Company.

Aminoplast crosslinkers useful in the practice of this invention include those partially or fully etherified with a suitable alcohol, typically methanol or butanol or mixtures thereof, and with methylol and/or imino functional groups. Mention may also be made of glycoluril-formaldehyde resins which may also contain groups. Examples of commercially available crosslinkers of this type include Schimel 1170, Schimel@1171, and Nummel o 1172 from American Cyanamid φ Company.

Aminoblast crosslinkers useful in the practice of this invention include a suitable alcohol, typically methanol or butanol, partially or fully etherified and with methylol and/or imino functional groups. Also mentioned are urea-formaldehyde resins which may also contain urea-formaldehyde resins. Examples of commercially available crosslinkers of this type include Beetle™ from American Cyanamid Company.
) 55, Beetle ■60, Beetle o65, and Beetle o80 and Regimen ■960, Regimen ■975, Regimen 09705 from Mont Saint-Toquin Guny.
Examples include Regimen ■955, Regimen ■933, Regimen [Co., Ltd.] 9205, Regimen o918, Regimen o9]5, Regimen ■907, Regimen @90], and Regimen o980.

Aminoblast crosslinkers useful in the practice of this invention also include carboxyl-modified aminoblast resins. These crosslinkers contain carboxylic acid functional groups as well as alkoxymethyl functional groups, typically methoxymethyl, ethoxymethyl, and butoxymethyl, or mixtures thereof, and also contain methylol and/or imino functional groups. Mention may be made of melamine-formaldehyde, benzoguanamine-formaldehyde, glycoluril-formaldehyde, and urea-formaldehyde type crosslinkers, which may optionally contain melamine-formaldehyde. Examples of commercially available cross-linking agents of this type include Schimel [Co.] 14] and Schimel 1] 2 from American Cyanamid Company.
5 is mentioned.

A particularly useful type of polyepoxide is the glycidyl polyethers of polyhydric phenols. Such polyepoxide resins are derived from shrimp chlorodrin and dihydric phenol and have an epoxide equivalent weight (EEW) of about 400 to about 4,00.
has 0. Examples of shrimp halohydrin are shrimp chlorohydrin, shrimp bromohydrin and shrimp iodohydrin, with shrimp chlorohydrin being preferred. Dihydric phenols include resorcinol, hydroquinone, p.

p'-dihydroxydiphenylpropane (or bisphenol A as it is commonly called), p.

Illustrated by p'-dihydroxybenzophenone, p,p' dihydroxydiphenylethane, bis-(2-hydroxynaphthyl)methane, 1,5-dihydroxydiphenylnaphthylene, and the like, with bisphenol A being preferred. These polyepoxide resins are well known in the art and can be prepared by reacting ebihalohydrin with divalent phenols in various proportions, or by reacting dihydric phenols in various proportions, or by reacting divalent phenols with low molecular weight polyepoxides. It is produced with a desired molecular weight by reacting with a resin. Particularly preferred polyepoxide resins have an epoxide equivalent weight of about 450 to about 2,000, more typically about 800 to about 1,600, preferably about 800.
˜1.500 glycidyl polyether of bisphenol A.

The polyepoxides used in the practice of this invention have relatively high molecular weights, typically from about 1,600 to about 3.200.
, preferably about 1. ．． 600 to about 2.800.

Another quite useful class of polyepoxides is similarly produced from novolak resins or similar polyphenolic resins.

Ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, lI
4-propylene glycol, 1°5-bentanediol, 1,4-propylene glycol, 1,5-bentanediol, 1,2,6-hexanetriol, glycerol, bis(4-hydroxychlorohexyl)-2,2-
Polyepoxides consisting of similar polyglycidyl ethers of polyhydric alcohols, which may be derived from polyhydric alcohols such as propane, are also suitable. shrimp chlorohydrin or similar epoxy compounds and aliphatic or aromatic polycarboxylic acids terephthalic acid, 2,6-naphthalenecarboxylic acid,
Polyglycidyl esters of polycarboxylic acids produced by reaction with dimerized phosphoric acid and the like can also be used. Examples are glycidyl adipate and glycidyl phthalate. Polyepoxides derived from epoxidation of olefinically unsaturated alicyclic compounds are also useful. Part 1
Diepoxides including the above monoepoxides are included. These polyepoxides are non-phenolic and obtained by epoxidation of cycloaliphatic olefins. For example, it can be obtained with oxygen and catalysts of certain processes, with perbenzoic acid, with acetaldehyde monober acetate or with peracetic acid. Among such polyepoxides are the epoxy cycloaliphatic ethers and esters well known in the art.

Other epokine at-j compounds and resins include nitrogen-containing diepoxides, such as U.S. Pat. No. 3,365,4
Disclosed in Specification No. 71.

], ] 1-methylene bis-5-substituted hydantoins) (U.S. Pat. No. 3,391,097); bis-imide-containing epoxides (U.S. Pat.
450.711); epoxidized aminomethyl diphenyl oxide (U.S. Pat. No. 3,312.664); heterocyclic N,N'-diglycidyl compounds (U.S. Pat. No. 3,503.979); ); aminoepoxy phosphonates (GB 1□ 172.916); 1,3,5-triglycidyl isocyanurate, as well as other epoxy-containing materials known in the art.

Any cationic epoxy-amine resin adducts commonly known and used in cathodic electrodeposition techniques, including modified epoxy resin adducts, can be used in the practice of this invention. For example, the modified epoxy resin used in the practice of this invention is one of the epoxy resin compositions described above that has been chain extended with a water-miscible or water-soluble polyol, reacted with excess amine, and finally reacted with a fatty acid or aliphatic monoepoxide. It may contain one. These epoxy amine resin adduct compositions are described in U.S. Pat.
No. 524. However, methods known in the art, e.g., U.S. Pat. No. 3,947,339
Any epoxy-amine resin adduct produced by the diketoimine method and other methods as disclosed in the present specification may be used in the practice of the present invention.

The polyamines used in the practice of this invention to produce epoxy-amine resin adducts when using the "excess amine" method are those known in the art, such as those known in the art, such as U.S. Pat.
The polyamines disclosed in US Pat. No. 139,510 are representative.

Amine-functional acrylic copolymers useful in the practice of this invention include two or more monomers, such as droxyethyl alkylates, dimethylethylamino methacrylate, styrene, butyl acrylate, ethyl acrylate, and acrylic copolymers. Included are copolymers of other monomers typically used to form resins. Copolymer resin is
esters of methacrylic acid, copolymers of α, β-unsaturated monomers such as styrene, hydroxyl-functional esters of acrylic acid or methacrylic acid and amine-functional α, β-unsaturated monomers, or reacted with amines. It will consist of a copolymer of glycidyl methacrylate or glycidyl acrylate. The cathodic electrodepositable amine-functional acrylic composition is
Disclosed in U.S. Pat. No. 3,883,483.

A sufficient amount of blocked polyisocyanate or aminoblast crosslinking agent is included in the electrodepositable coating composition of the present invention so that the deposited coating will be completely cured upon baking. Also, the coating composition will be designed such that when using a polyisocyanate crosslinker there will be no free isocyanate groups remaining after curing.

Typically from about 10% to about 60% by weight, more typically about 20% by weight based on the total weight of the main resin composition and crosslinker.
% to about 50% by weight, preferably about 25% to about 3% by weight
5% by weight of blocked polyisocyanate is incorporated. Typically, from about 10% to about 60% by weight, preferably from about 20% to about 40% by weight, based on the combined weight of crosslinker and main resin composition, of aminoblast crosslinking agent is used. .

Blocked polyisocyanates of the present invention are prepared by adding the blocked polyisocyanate to a vessel containing the epoxy-amine resin adduct composition or amine-functional acrylic copolymer and mixing the charge for about 1/2 hour. Mix with the main resin composition, such as an epoxy-amine adduct or an amine-functional acrylic copolymer. Aminoblast crosslinkers are typically added in a similar manner.

In order to solubilize or disperse the emulsion cathodic electrodepositable resin composition, it is necessary to salinate the amine-containing resin with a water-soluble acid. Acids that can be used include those known in the art;
Examples include formic acid, acetic acid, phosphoric acid, lactic acid, and hydrochloric acid. A sufficient amount of acid is mixed with the electrodepositable resin composition to solubilize or disperse the resin composition in water. A preferred method of accomplishing the chlorination process is by charging the resin composition, acid, cosolvent, water and surfactant conventional in the art into a vessel and mixing the charges in a slow mixer.

Typically, about 0.000 g/g of solid resin. 1 Meq to about 0.8 Meq, more typically about 0.2 Meq to about 0.8 Meq.
7 Meq, preferably about O12 Meq to about 0.5 Meq
of acids are used.

The primary resin solution or emulsion is typically incorporated directly into the coating bath at the coating site. Base resin solutions or emulsions with higher or lower concentrations can be used, but typically
The main resin solution or emulsion of the present invention comprises about 10% by weight of an amine-epoxy resin adduct or an amine-functional acrylic resin.
~90% by weight, more typically from about 20% to about 30% by weight
．． 0% by weight, preferably about 22% by weight.

The concentration of the cathodically depositable main resin composition in the aqueous cathodically deposited coating bath is typically about 5f! % to about 50% by weight, more typically about 10% to about 25% by weight, preferably about 15% by weight.

It should be noted that cathodically depositable resin coating compositions are typically shipped to the user by the manufacturer as a chlorinated aqueous dispersion having a solids concentration of about 20% to about 36% by weight. .

Although unchlorinated resins can be used in baths that already contain solubilizing acids, the cathodic coating baths of the present invention typically contain the solubilized (i.e., chlorinated) cathodic coaters of the present invention in concentrated form. The resin composition is prepared by mixing with water. The electrodeposition bath may contain additional ingredients such as pigments, cosolvents, antioxidants, surfactants, etc., typically used in electrodeposition methods known in the art. The pigment composition may be of a conventional type and is one or more of pigments such as iron oxide, dyes, carbon black, titanium dioxide, talc, barium sulfate, barium yellow, cadmium red, chrome green, etc. Additionally, hydrophobic dyes such as those described in co-pending patent applications can be used.

A sufficient amount of pigment is used to achieve the desired appearance properties, such as gloss, reflection, hue, tint, and other desired properties. Typically, when pigments are used, the amount of pigment in the coating bath is expressed as a ratio of total pigment to total binder. Typically, a pigment to binder ratio of from 0.01 to about 0.95, more typically from about 0.01 to about 0.4, is used in the electrodepositable resin compositions of the present invention. . Pigments are typically added to the electrodeposition bath in paste form, ie, predispersed in a paste composition containing the conventional pigment, cathodic electrodepositable grinding composition, and surfactants and additives.

A sufficient amount of the water-insoluble organolead compound of the present invention will be incorporated into the coating composition of the present invention to provide sufficient corrosion resistance of the coated substrate. The organic lead compound may be incorporated into the main resin solution or emulsion or pigment paste. When incorporated into the base resin solution or emulsion or coating bath, the weight percent of water-insoluble organic lead relative to the base resin is typically about 0.1
% by weight to about 10% by weight, preferably about 0. 5% by weight ~
It is about 5.0% by weight. Water-insoluble organolead compounds are incorporated into the main resin or emulsion by mixing with the main resin or main resin/crosslinker mixture and dispersing in water prior to chlorination; Formulated into pigment paste by mixing with crushed resin before dispersing into pigment paste.

The electrodeposition bath may contain a coupling solvent that is a water-soluble or partially water-soluble organic solvent for the resinous vehicle used in the practice of this invention. Coupling solvents or cosolvents used in the practice of this invention are those typically used and known in the art.

The smoothness of the cured coating is a function of the "flow" of the deposited coating composition. Flow is defined as the tendency of an electrocoated coating composition to liquefy during the curing operation and form a smooth cohesive film over the surface of the coated article prior to initial crosslinking. This means that
This is achieved in part by co-solvents.

Examples of such coupling solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
Examples include diethylene glycol monobutyl ether, ethanol, isopropanol, and n-butanol. A sufficient amount of coupling solvent is optionally used so that a good emulsion resulting in a smooth adherent film is prepared.

Electrodeposition typically occurs in an electrically insulated tank containing a conductive anode attached to a direct current source. The size of the tank will depend on the size of the article to be coated.

Typically, tanks are made from stainless steel or mild steel and lined with a dielectric coating such as epoxy-impregnated fiberglass, polypropylene, or the like. The electrodepositable cathodic resinous coating composition of the present invention is typically used to coat articles such as automobile bodies, truck bodies, car parts, and electrical appliances. Typical sizes of electrodeposition bath tanks used for this purpose can range from approximately a few hundred gallons to about 120,000 gallons. However, conductive articles of any size, from fasteners such as nuts and bolts to construction equipment and structural members, may be coated with the E-coat compositions of the present invention.

Typically, the article to be coated is connected to a DC circuit such that the electrically conductive article acts as a cathode.

When the article is immersed in the coating bath, electrical current across the article produces a film of cationic electrodepositable coating composition to be deposited on the surface of the article. The E-coat composition has a net positive charge and is therefore attracted to the negative cathode surface of the conductive article to be coated.

The thickness of the coating deposited on the article during residence in the cathodic E-coat coating bath depends on the cathodic E-coat coating composition, the voltage across the article, the current flux, the pH of the coating bath, the conductivity, It is a function of residence time, etc. Sufficient voltage will be applied to the article for a sufficient period of time to obtain a coating of sufficient thickness and uniform coverage. Typically, the voltage applied across the coated article is from about 50V to about 500V, more typically about 20V.
0V to about 350V, preferably about 225V to about 300V
It is V. The current density is typically from about 0.5 A/sq ft to about 30 A/sq ft, more typically from about IA/sq ft to about 25 A/sq ft, preferably about IA/sq ft. The article typically remains in the coating bath for a sufficient time to produce a coating or film of sufficient thickness with sufficient corrosion resistance. The residence or retention time is typically on the order of a few seconds to about 3 minutes, more typically about 1 minute to about 2.5 minutes, preferably about 2 minutes. However, this will vary and depend on said parameters.

The pH of the coating bath is sufficient to produce wax coatings without breaking under the applied voltage. That is, the pH is sufficient to maintain the stability of the coating bath so that the resin does not kick out of the dispersion and to control the conductivity of the bath.Typically, the pH is from about 4 to about 7, more typically is about 5 to about 6.8
, preferably about 5.5 to about 6.5.

The conductivity of the coating bath will be sufficient to produce a coating film of sufficient thickness. Typically, the conductivity is about 800
micromhos to about 3,000 micromhos, more typically about 800 micromhos to about 2,200 micromhos, preferably about 900 micromhos to about 1,800 micromhos.

The desired coating thickness is sufficient to provide corrosion resistance while having adequate flexibility. Typically, coated objects of the present invention have a film thickness of about 0.4 mil to about 1.8 mil.

Thicker or thinner films may be applied as desired.

When the desired thickness of the coating is achieved, the coated article is removed from the electrodeposition bath and cured. Typically, the electrodeposited coating is cured in a conventional convection oven at a sufficient temperature for a sufficient time to unblock the protected polysocyanate (when a protected polysocyanate is used) and to remove the electrolyte. Enables crosslinking of adhesive resin compositions. Typically, the coated article has a temperature of about 200 below (93°C) to about 600 below (315°C).
), more typically from about 250 below (121'C) to about 39
0 below (199°C), preferably about 300 below (149°C)
It will bake at a metal temperature of ~375'F (191C). The coated article will be baked for a period of about 50 V to about 40 minutes, more typically about 50 V to about 35 minutes, preferably about 50 to about 30 minutes. It will be recognized by those skilled in the art that degrees, times and temperatures will vary.

It is contemplated that the coated articles of the present invention may be cured using radiation, steam curing, contact with heat transfer fluids, and similar methods.

It will be recognized by those skilled in the art that each of the coating parameters may vary depending on the coating composition, bath properties, article size and shape, coating performance requirements, and the like.

Typically, coated articles of the invention are made of steel, aluminum,
It will include a conductive substrate such as a metal, including brass, gold, silver, platinum, nickel, chromium, zinc, coated steel, copper, and the like. However, any conductive substrate having a conductivity similar to the metal may be used. The article to be coated may be of any shape as long as all surfaces can be wetted by the electrodeposition bath. Characteristics of the article that have an effect on coating adhesion include the shape of the article, the ability of the surface to be wetted by the coating, and the degree of shielding from the anode. Shielding is defined as the degree to which the coating composition is prevented from depositing in the shielded area by interfering with the electrogenic groups that occur between the cathode and the anode. A measure of the ability of a coating bath to coat discrete areas of an object is the uniformity of electrodeposition. Thread deposition is a function of the electrical configuration of the anode and cathode and the conductivity of the electrodeposition bath. The high conductivity produced by soluble lead is known to reduce uniformity of electrodeposition.

Soluble lead, such as lead acetate, lead lactate, and the like described in US Pat. This reduces the voltage that the article can be coated with without experiencing rupture. Fractures are coating defects that are similar to film boiling or bubbling and can result in unacceptable appearance and performance. The reduced breakdown voltage is
In part, this is in response to reduced uniformity of electrodeposition. Also, reduced voltage can reduce the maximum film thickness obtainable, which can result in poor coating performance.

The coatings of the coated articles of the present invention exhibit excellent smoothness, gloss, flexibility, durability and corrosion resistance. Smoothness and gloss are related to the flow of the electrodeposited cathode resin.

Durability, flexibility and corrosion resistance are related to the chemistry of the electrodeposited cathode E-coat composition and the smoothness of the deposited coating.

These coating compositions readily accept automotive primers or topcoats, such as industry standard internal pigmented base coats and external clear top coats.

The aqueous E-coat coating bath of the present invention does not contain water-soluble lead compounds, lead pigments or tin catalysts. Coatings without water-soluble lead compounds, lead pigments, or tin catalysts contain blocked isocyanate-type crosslinkers and do not cure into hard, solvent-resistant, durable films with acceptable corrosion performance. Surprisingly, water-insoluble organic lead compounds are similar to water-soluble lead compounds,
It can be used in aqueous E-coat baths in place of lead pigments or tin catalysts and produces a bond-cured coating with a hard, durable, solvent-resistant film with excellent corrosion resistance. Also, surprisingly, the water-insoluble organolead compounds do not reduce the breakdown voltage, do not reduce the uniformity of electrodeposition, or do not reduce the maximum film thickness that can be obtained.

It should be noted that the articles coated with the E-coat coating compositions of the present invention are typically automobile bodies that have been pretreated in a phosphating bath to remove impurities and contaminants. However, coating compositions are difficult to apply to electrically conductive substrates (
It may be used to coat virtually any object (pretreated or not).

The following examples are intended to illustrate, but not limit, the principles and practice of the invention. Parts and percentages when used are parts and percentages by weight.

Representative Examples of Typical Polymeric Materials Useful in the Invention Example 1 Ethyl cellosolve (290.0 parts by weight) and butyl cellosolve 106.0 parts are charged to a reactor equipped with a condenser, a stirrer, a thermometer, and a dropping funnel. .

The mixture is heated to 120-130°C and maintained at this temperature. This mixture was mixed with 580.0 parts of butyl acrylate, 350.0 parts of styrene, 140.0 parts of N,N-dimethylaminoethyl methacrylate, 58.0 parts of 2-hydroxyethyl methacrylate, and α,α-azobisisobutylene. A mixture with 17.0 parts of lonitrile is added over a period of 3 hours. A mixture of 2.0 parts of t-butylperoxyisoprobyl carbonate and 1.5 parts of ethyl cellosolve is then added.

After holding the reaction mixture at 120° C. for 1 hour, the second addition of said components was added and the reaction was likewise allowed to continue for 1 hour before the third and fourth additions of said components were added and the reaction was continued for 2 hours. Make time last.

Example 2 Epon@829 (727, 6 parts) and PCP in the reaction vessel
-0200 (268,1 part), and xylene 36,1
and heated to 210° C. with nitrogen sparge. The reaction mixture is held under reflux for about 1/2 hour to remove water.

The reaction mixture was cooled to 150°C and bisphenol A19
7.8 parts and 1.6 parts of benzyldimethylamine catalyst are added and the reaction mixture is heated to 150-190°C, held at this temperature for about 1.5 hours, then cooled to 130°C. Then 2.2 parts of benzyldimethylamine catalyst was added and the reduced Gardner-Hold
ot t) Viscosity (50% resin solids solution in 2-ethoxyethanol)
Hold at ℃ for 2.5 hours. Next, 73.1 parts of a diketoimine derivative derived from diethylenetriamine and methyl isobutyl ketone (73% solid content in methyl isobutyl ketone), and 39.1 parts of N-methylethanolamine.
1 part and bring the temperature of the reaction mixture to 110°C and hold at that temperature for 1 hour. To this mixture is added 76.5 parts of 2-hexoxyethanol.

Example 3 Add 115 parts of xylene to a clean, dry reactor.

Blanket the liquid mixture with pure nitrogen and heat to 42°C. Epon■100IF (EEW=520~540
) The addition of 568.1 parts is carried out at such a rate that the batch temperature does not fall below 60° C., usually over a period of 2 hours. 10
Continue heating to 0°C. At this point, add 75.9 parts of dodenlephenol and heat to 118°C. Vacuum drying by distillation of xylene is started at this temperature and continued with heating to 125°C. Pressure is 65c+ with sufficient vacuum
nHg ~69cmHg (88k P ~92k
P) should be. The drying stage should take 1.0-1.5 hours. Breaking the vacuum with pure nitrogen only. The batch was cooled and the sample at this point was 94% non-volatile.
3-95.3%) at 115° C., add 1.1 part of benzyldimethylamine. The peak exothermic temperature should reach 129-]32°C. The temperature is maintained at 128-132°C and after polymerization EEW titration is performed. Every 30 minutes, sample the reaction mixture and
It stops at the end point of W1090-1110. Typical reaction time is 3 hours. Adjustment of the amount of catalyst may be necessary if the extension time deviates by more than 3 hours to 30 minutes. In the target EEW, after adding 12.1 parts of butyl cellosolve and 74.7 parts of xylene, DE
Add 42.6 parts of OA (jetanolamine). The reaction temperature should not exceed 132°C. Cooling may be required at this point in the jacket or coil. Vacuum suction was started immediately after DEOA addition;
Reduce pressure to 18 inches Hg and hold for 5 minutes. The pressure is further reduced in 2 inch Hg increments and then held briefly until 26-2 inches Hg is achieved. The batch is then cooled to 90° C. for 1 hour before adding DEOA. To achieve this, a good reflux rate is required for DE
This should be achieved 20-25 minutes after adding the OA.

Return all solvent to the reactor. Vacuum cooling (T-90
C) After 1 hour, 40.6 parts of ethylene glycol monohexyl ether and 107.7 parts of inbutanol are added without breaking the vacuum. Cool the batch to 57-61°C under full vacuum for 35 minutes to achieve the target temperature in the specified timetable.

After a cooling period of 35 minutes, dimethylaminopropylamine (
Charge 13.3 parts of DMAPA) as quickly as possible.

The batch is held at 54-60°C for 2 hours after exotherm. The drumsticks are then heated to 90° C. for 1 hour and maintained at this temperature for 1 hour. The batch is then cooled to 80°C.

Example 4 Triethylenetetraamine 1881.7 in a suitable reactor
Add part. By applying heat and stirring, at 104°C, the solids content in ethylene glycol monomethyl ether was 5%.
Slowly add 1944.8 parts of a 9.4% epoxide resin solution (the epoxide resin is a glycidyl polyether of bisphenol A with 1895 epoxide atoms).

Epoxide resin addition is completed in 65 minutes at a temperature of 99°C
It goes down to The temperature is slowly increased to 121°C over 45 minutes and held at 121-127°C for 1 hour to complete the addition reaction. Excess unreacted amine and solvent are removed by heating the adduct solution to 232° C. under vacuum (25 mm Hg pressure). When the distillation is complete, the vacuum is released and the temperature is reduced to 182°C. Then, 700 parts of ethylene glycol monomethyl ether was added and the temperature was adjusted to about 11
Lower to 8℃. When the solution is homogeneous, mainly n-
458.3 parts of glycidyl ether of a mixed fatty alcohol containing octyl and n-decyl groups (the glycidyl ether has an epoxide equivalent weight of 229) are
Add at a temperature of 16°C. After an additional hour at 116° C., heating is stopped. The product obtained should have a solids content of 71.3% and a Gardner-Holdt viscosity of Z6 to Z7.

Example 5 A blocked isocyanate (polyurethane crosslinker, reverse order) is produced according to the following method. 291 parts of an 80/20 isomer mixture of 2.4-/2.6-toluene diisocyanate, 0.08 parts of dibutyltin dilaurate and 18 parts of methyl isobutyl ketone under stirring and in a nitrogen atmosphere.
0 parts slowly into a suitable reactor (temperature 38
). After maintaining the mixture at 38° C. for a further half hour, 75 parts of trimethylolpropane are added.

After the reaction is allowed to stir for about 1 hour, 175 parts of ethylene glycol monopropyl ether are added and the reaction mixture is maintained at 121° C. for 1.5 hours until essentially all the isocyanate groups have reacted. This depletion is visible from the infrared spectrum.

Blocked isocyanates of the usual order can be produced by modification of the above order of addition according to example 1 of German Patent No. 2.701,002.

Example 6 A blocked isocyanate crosslinker (polyurea) is produced according to the following method. A dry reactor is charged with 483 parts of triisocyanurated hexamethylene diisocyanate and 193 parts of 2-hexanone. Dibutylamine (307
part) is added slowly under a nitrogen atmosphere with stirring so that the temperature does not exceed 80°C. After all the amines have reacted, 14 parts of n-butanol and 0.2 parts of dibutyltin dilaurate are added.

Example 7 A quaternizing agent used in producing a pigment grinding resin is produced as follows. 320 parts of 2-ethylhexanol semiblocked toluene diisocyanate (95% solids in methyl isobutyl ketone) are added to 87.2 parts of dimethylethanolamine in a suitable reactor at room temperature. The mixture is exothermed and stirred at 80° C. for 1 hour. Next, lactic acid (117.6 parts of an 88% aqueous lactic acid solution) is charged, and then 39.2 parts of 2-butoxeethanol are added. The reaction mixture is stirred at 65° C. for about 1 hour to produce the desired quaternizing agent.

The pulverized resin is produced as follows. Epon ■839 (71
0 parts) and 289.6 parts of bisphenol A are charged to a suitable reaction vessel and heated to 150-160°C to initiate an exotherm. The reaction mixture is exothermed to 150-160°C for 1 hour. The reaction mixture was then cooled to 85-90°C, homogenized and then charged with 71.2 parts of deionized water, after which
Add 496.3 parts of the quaternizing agent. The temperature of the reaction mixture is maintained at 80-85° C. until an acid number of 1 is obtained.

Example 8 Diglycidyl ether of bisphenol A 2 in the reaction vessel
Charge 7.81 parts and 1.44 parts of xylene. The charge is heated to 82° C. under a dry nitrogen atmosphere. The heating is interrupted and a charge of 5.81 parts of bisphenol is added along with 0.002 parts of triphenylphosphine catalyst. Heating of the reaction vessel is then continued to a temperature of 127°C, at which temperature the reaction begins to become exothermic on its own (peak at about 150-160°C). The extension is held above 150<0>C until an EEW of 340-360 is achieved (approximately 345). −
Once the target EEW is reached, butyl cellosolve 21.08
1/2 to the reaction vessel and the reaction mixture is then cooled to 49°C. After reaching a temperature of 49 °C, 9-amino-3,6
A mixture of 7.77 parts of thioxano-tin-1-ol and 4.07 parts of dimethylaminopropylamine is added to the reaction vessel over 6 minutes, followed by pump flushing with 0.53 parts of ethylene glycol monobutyl ether.

The batch exotherms to 104-110°C and the reaction mixture is then held at ]]55°C for 1 hour. Then, 4.92 parts of butyl cellosolve was charged to the reaction vessel and the batch was
Cool to 7°C. Next, 14.9 parts of nonylphenol glycidyl ether were charged into the reaction vessel, and then 53 parts of ethylene glycol monobutyl ether were pump flushed. The batch exotherms to 88-93°C and then the batch is held at this temperature for 1 hour. Finally, 10.03 parts of butyl cellosolve are charged to the reaction vessel and the batch is cooled to 66°C. The resulting product is then filtered through a 25μ bag and drummed.

Addition of water-insoluble organic lead compound to main resin solution 9-1
5 This general method applies to Examples 9-15. Specific formulations for these examples are shown in Table 1. All amounts in Table 1 represent the weight of the non-volatile portion.

Charge crosslinking agent to a suitable mixing vessel. Optionally, if a hydrophobic dye is incorporated, the dye is added to the crosslinker with slow agitation and mixed for about 30 minutes. The plasticizer and organic solvent are then added to the mixture while continuing to stir slowly. The main resin is then added to the continuous mixed batch at 21-49°C. After 30 minutes of continuous stirring, one or more water-insoluble organic lead compounds are added. Continue mixing for 30 minutes without interruption, then add all remaining additives, flow agents, solvents, antifoam, and surfactants.

Addition of water-insoluble organic lead compound to main resin emulsion 16
~23 This -membrane property applies to Examples 16-23. Specific formulations for these examples are shown in Table 2.

First, the main resin solution containing the crosslinker, plasticizer, one or more organolead compounds and other applicable ingredients are mixed together as described in the example series (9-14) above. A solubilizing acid is then added to the main resin solution, and the resulting solubilized main resin solution is then mixed with deionized water or optionally a deionized water/surfactant mixture.

Examples of pigment pastes (with and without the inclusion of water-insoluble organic lead compounds) Example 24 In a suitable mixing vessel, 198.3 parts of the milled resin from Example 8 are mixed with 11.1 parts of acetic acid and 27.7 parts of Trisiar.
Mix with 7.0 parts antifoam (Tristar Chemical Company, Dallas, Texas) and 342.6 parts deionized water. Once homogeneous, add 12.6 parts of carbon black, 63.0 parts of clay extender and 329.7 parts of titanium dioxide.
part into the mixture. high speed cowles
Grind fineness (F, 0.0) 5 using a disperser, sand mill, ball mill, or other pigment dispersion equipment.
~7 is obtained.

Example 25 In a suitable mixing vessel, combine 226.36 parts of the milled resin from Example 7 with 388.9 parts of deionized water and 16.5 parts of carbon black.
4 parts and 564.31 parts of titanium dioxide. The mixture is ground until a Hegeman fineness of grind of 5-7 is obtained.

Example 26 In a suitable mixing vessel, 198.3 parts of the milled resin from Example 8 are mixed with 27.2 parts of lead 2-ethylhexanoate and stirred for about 30 minutes. Then, with continued mixing, acetic acid 11.1
1 part, 7.0 parts Tristar 27o antifoam and 342.6 parts deionized water. Once uniform, 2.6 parts of carbon black, 63.0 parts of clay filler and 329.7 parts of titanium dioxide are added and dispersed to a Hegeman fineness of 5-7.

Side-down of cathode paint containing water-impermeable lead compounds 27~
34 cases are prepared according to the regimen outlined in Table 3.

Although the invention has been shown and described with respect to specific embodiments, it will be understood by those skilled in the art that various changes in form and detail can be made without departing from the spirit and scope of the invention.

Claims (1)

[Scope of Claims] 1. (a) a cathodic electrodepositable resin composition; (b) a crosslinking agent; and (c) a liquid or a liquid solution when mixed with a suitable solvent or oil; Contains an organic lead compound consisting of a water-insoluble lead salt of an aliphatic acid having at least 6 carbon atoms or an insoluble lead salt of an aromatic carboxylic acid, which becomes a liquid paste when mixed with a suitable organic solvent or oil, and is conductive by aqueous cathodic electrodeposition. When deposited as a film on a plastic substrate and when cured, the composition is a cathodically depositable resinous material which is characterized by curing to a hard, durable film without the need for any additional catalyst and with excellent corrosion resistance. Coating composition. 2. Coating composition according to claim 1, characterized in that the resin composition is selected from the group consisting of amine epoxy resin adducts and amine functional acrylic resins. 3.Claim 1 or 2, wherein the crosslinking agent is selected from the group consisting of blocked polyisocyanates, blocked polyether polyol polyisocyanate adducts, alkanol-blocked melamine resins, and alkanol-blocked urea formaldehyde resins. The coating composition described in . 4. Organic lead compounds include lead 2-ethylhexanoate, lead naphthenate, lead octoate, lead dodecanoate, lead oleate,
Coating composition according to any one of claims 1 to 3, characterized in that it is selected from the group consisting of: and lead stearate. 5. Coating composition according to any one of claims 1 to 4, characterized in that it is in the form of an aqueous bath. 6. A coated article, characterized in that it is coated with the aqueous cathodic electrodepositable resinous coating composition according to any one of claims 1 to 5. 7. Prepare an aqueous cathodic electrodeposition coating bath (the coating bath includes an aqueous cathodic electrodeposition resin composition and a crosslinking agent, said bath is contained in an electrically insulating container containing an anode), and then conductive The article is connected to an electrical circuit to act as a cathode, the article is immersed in the bath, and sufficient electrical power is passed across the article such that a film of the coating composition is deposited to a sufficient thickness on the surface of the article. , then removing the article and curing the film into a hard durable coating, the process comprising cathodic electrodeposition of an aqueous coating composition, the coating bath having at least 6 carbon atoms
at least one organic lead composition consisting of an insoluble lead salt of an aliphatic acid or an insoluble lead salt of an aromatic carboxylic acid, and the resulting coating containing organic lead is characterized in that it has excellent corrosion resistance. cathodic electrodeposition of aqueous coating compositions. 8. The method according to claim 7, characterized in that the resin composition is selected from the group consisting of amine epoxy resin adducts and amine functional acrylic resins. 9. Claim 7 or 8, characterized in that the crosslinking agent is selected from the group consisting of blocked polyisocyanates, blocked polyether polyol polyisocyanate adducts, alkanol-blocked melamine resins and alkanol-blocked urea formaldehyde resins. The method described in. 10. Claims 7 to 9, characterized in that the organic lead compound is selected from the group consisting of lead 2-ethylhexanoate, lead naphthenate, lead octoate, lead dodecanoate, lead oleate, and lead stearate. The method according to any one of the above.