JP2002265880A - Cationic electrodeposition coating composition, method for cationic electrodeposition coating and coated product obtained therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrodeposition coating composition capable of improving deposited film defects in an electrodeposition step without lowering of storage stability, lowering of electrodeposition coating voltage, stickiness inhibition of the resultant film to the under film nor lowering of anticorrosion properties and having excellent environmental compatibility, a method for cationic electrodeposition coating and a coated product obtained from the method. SOLUTION: This cationic electrodeposition coating composition is characterized as comprising a resin composition having sulfonium groups and propargyl groups and a benzoin derivative in an amount of 0.1-10 pts.wt. based on 100 pts.wt. of solids in the resin composition. The method for cationic electrodeposition coating is characterized in that the cationic electrodeposition coating is the cationic electrodeposition coating composition in the method for cationic electrodeposition coating comprising carrying out electrodeposition coating of the cationic electrodeposition coating on a material to be coated. The coated product is obtained by the method for cationic electrodeposition coating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cationic electrodeposition coating composition, a cationic electrodeposition coating method, and a coating product obtained by the method, and particularly to a cationic electrodeposition coating useful for improving workability in an electrodeposition coating process. The present invention relates to a coating composition and a cationic electrodeposition coating method, and a coated product obtained by the method.

[0002]

2. Description of the Related Art Cationic electrodeposition coatings are widely used on various objects to be coated such as building materials, ships, automobile bodies and parts, general-purpose industrial parts, etc. because of their high rust and corrosion resistance. I have. In addition, since the cationic electrodeposition paint is a water-based paint, it has great environmental advantages, such as no risk of fire and a great reduction in the amount of organic solvents used.

[0003] However, such a cationic electrodeposition paint has often been regarded as a problem in workability in the electrodeposition coating process due to the inherent properties of the water-based paint. For example, if the water after washing with water is unevenly remaining on the surface of the object to be coated, and if the electrodeposition coating is performed as it is, if the electrodeposition along the uneven part called dry unevenness defect or water unevenness defect occurs. Abnormal deposition of the deposited film may occur. This is considered to be due to the fact that the remaining water film locally changes the electric resistance value and affects the electrodeposition deposition behavior.

[0004] As an improvement method for such a phenomenon,
For example, physical properties of paints are adjusted by adding a high-boiling alcohol-based or cellosolve-based organic solvent, reducing the molecular weight of the resin composition in the paint, and adding a polyoxyalkylene compound. There is a possibility that the adjustment of the coating film thickness becomes difficult due to a drastic decrease in the coating voltage, or the adhesion may be impaired when a direct coating film such as an intermediate coating or a top coating is formed after forming the electrodeposition coating film.

[0005] Japanese Patent Application Laid-Open No. 4-116197 discloses a cationic electrodeposition coating composition comprising a benzoin derivative and a resin component comprising an amine-added epoxy resin and a crosslinking agent capable of suppressing craters specifically generated on a zinc steel sheet. Is disclosed. However, all the examples in this publication use a basic silicate which is a rust preventive pigment.
The heavy metal based rust preventive pigment mainly composed of lead metal such as a basic silicate is harmful and may cause a problem of environmental pollution.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to reduce storage stability, decrease the electrodeposition coating voltage, impair the adhesion of the obtained coating film to the immediately above coating film, and reduce the corrosion resistance. In addition, an object of the present invention is to provide a cationic electrodeposition coating composition, a cationic electrodeposition coating method, and a coated article obtained therefrom, which are excellent in environmental compatibility and can improve the defects of the deposited coating film in the electrodeposition deposition step.

[0007]

The present invention provides a resin composition having a sulfonium group and a propargyl group and a benzoin derivative in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the solid content of the resin composition. A cationic electrodeposition coating composition comprising: Here, for example, the benzoin derivative is benzoin and / or an alkyl etherified product of benzoin having 1 to 10 carbon atoms.

The sulfonium group and the propargyl group have a sulfonium group content of 5 to 400 mmol and a propargyl group content of 10 to 10 mmol per 100 g of the solid content of the resin composition.
495 mmol, and the total content of sulfonium groups and propargyl groups is preferably 500 mmol or less, and 5 to 250 mmol of sulfonium groups.
And 20 to 395 mmol of propargyl groups,
Further, the total content of the sulfonium group and the propargyl group is more preferably 400 mmol or less.
Further, the resin composition preferably has an epoxy resin as a skeleton, more preferably a novolak cresol type epoxy resin or a novolak phenol type epoxy resin, and further preferably has a number average molecular weight of 700 to 5,000.

Further, the present invention provides a cationic electrodeposition coating method for electrodepositing a cationic electrodeposition paint on an object to be coated,
A cationic electrodeposition coating method, wherein the cationic electrodeposition coating composition is the above cationic electrodeposition coating composition. Furthermore, the present invention is a coated product obtained by the above-mentioned cationic electrodeposition coating method.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTSCationic electrodeposition coating composition  The cationic electrodeposition coating composition of the present invention comprises a sulfonium group and
COMPOSITION HAVING AND PROPARGYL GROUP AND THE RESIN
A benzoin derivative was added to 100 parts by weight of the solid content of the composition.
Characterized by containing 0.1 to 10 parts by weight of body
It is.

The cationic electrodeposition coating composition in the cationic electrodeposition coating of the present invention contains a resin composition having a sulfonium group and a propargyl group. The resin constituting such a resin composition may have both a sulfonium group and a propargyl group in one molecule, but it is not always necessary. For example, any one of a sulfonium group and a propargyl group in one molecule You may have only one or the other. In the latter case, the resin composition as a whole has all of these two types of curable functional groups. That is, the resin composition comprises a resin having a sulfonium group and a propargyl group, a mixture of a resin having only a sulfonium group and a resin having only a propargyl group, or a mixture of all of these. You may. The resin composition contained in the cationic electrodeposition coating composition used in the present invention has a sulfonium group and a propargyl group in the above meaning.

The above-mentioned sulfonium group is a hydrated functional group of the above-mentioned resin composition. When a voltage or current exceeding a certain level is applied in the electrodeposition coating process, the sulfonium group undergoes an electrolytic reduction reaction on the electrode, and the ionic group disappears, so that the sulfonium group can be irreversibly converted to a nonconductive state. It is considered that the cationic electrodeposition coating composition used in the present invention can exhibit a high throwing power. Also, in this electrodeposition coating process, it is considered that an electrode reaction is caused and the generated hydroxide ion is retained by the sulfonium group, so that the electrogenerated base is generated in the electrodeposited film.

The content of the sulfonium group contained in the resin composition contained in the cationic electrodeposition coating composition of the present invention is such that the content of the sulfonium group and the propargyl group described below is satisfied, and It is 5-400 mmol per 100 g of solids. 5mmol / 100g
If it is less than 3, sufficient throwing power and curability cannot be exhibited, and hydration properties and bath stability deteriorate.
If it exceeds 400 mmol / 100 g, deposition of the coating film on the surface of the article to be coated will be poor. The content of the sulfonium group, a more preferable content can be set according to the resin skeleton used, for example, in the case of novolak phenol type epoxy resin, novolak cresol type epoxy resin, per 100 g of the resin composition solid content 5-250mm
ol, more preferably 10 to 150 mmol. Further, it is considered that a propargyl group having low reactivity due to heating existing in the electrodeposited film can be converted into an allene bond having high reactivity due to heating.

The propargyl group contained in the resin composition contained in the cationic electrodeposition coating composition is converted into an allene bond by an electrogenerated base generated during the electrodeposition coating process, thereby increasing the reactivity. Thus, a curing system of the cationic electrodeposition coating composition of the present invention can be constituted. Further, for unknown reasons, the coexistence of the propargyl group and the sulfonium group can further improve the throwing power of the cationic electrodeposition coating composition.

The content of the propargyl group of the resin composition contained in the cationic electrodeposition coating composition is determined by satisfying the conditions of the sulfonium group and the propargyl group described below, and 10 to 495 mmol per 100 g. 10mmol / 100g
When the amount is less than the above, sufficient throwing power and curability cannot be exhibited. When the amount exceeds 495 mmol / 100 g, hydration stability when used as a cationic electrodeposition paint may be adversely affected. For the content of the propargyl group, a more preferable content can be set according to the resin skeleton used.For example, in the case of a novolak phenol-type epoxy resin or a novolak cresol-type epoxy resin, the resin composition has a solid content of 100 g per 100 g. 20-3
Preferably it is 95 mmol.

The resin serving as the skeleton of the resin composition contained in the cationic electrodeposition coating composition is not particularly limited, but an epoxy resin is preferably used. As the epoxy resin, those having at least two or more epoxy groups in one molecule are preferably used, and specifically,
For example, epibisepoxy resin, which is chain-extended with diol, dicarboxylic acid, diamine, etc .; epoxidized polybutadiene; novolak phenol type polyepoxy resin; novolak cresol type polyepoxy resin; polyglycidyl acrylate; aliphatic polyol or polyether Polyglycidyl ethers of polyols; polyepoxy resins such as polyglycidyl esters of polybasic carboxylic acids; Of these, novolak phenol type polyepoxy resin, novolak cresol type polyepoxy resin, and polyglycidyl acrylate are preferable because polyfunctionalization for enhancing curability is easy. Note that a part of the epoxy resin may be a monoepoxy resin.

The resin composition contained in the cationic electrodeposition coating composition comprises a resin having the epoxy resin as a skeleton, and has a number average molecular weight of 500 to 20,000. When the number average molecular weight is less than 500, the coating efficiency of the cationic electrodeposition coating becomes poor, and when it exceeds 20,000, a good film cannot be formed on the surface of the object to be coated. A more preferable number average molecular weight can be set according to the resin skeleton. For example, in the case of a novolak phenol type epoxy resin or a novolak cresol type epoxy resin, 700 to 500
It is preferably 0.

The total content of sulfonium groups and propargyl groups of the resin composition is 500 mmol or less per 100 g of solids of the resin composition. 50
If it exceeds 0 mmol, the resin may not be actually obtained or the desired performance may not be obtained. The total content of the sulfonium group and propargyl group having the resin composition can be set to a more preferable content according to the resin skeleton used, for example, in the case of novolak phenol type epoxy resin, novolak cresol type epoxy resin Is preferably 400 mmol or less.

Some of the propargyl groups of the resin composition contained in the above cationic electrodeposition coating composition may be acetylated. Acetylide is a salt-like metal acetylenide. When a part of the propargyl group of the resin composition is converted to acetylide, the content of the propargyl group is 0.1 to 100 g per 100 g of the solid content of the resin composition.
Preferably it is 1 to 40 mmol. 0.1mmo
When it is less than 1, the effect by acetylidation is not sufficiently exhibited, and when it exceeds 40 mmol, acetylidation is difficult. This content can be set in a more preferable range according to the metal used.

When a part of the above-mentioned propargyl group is acetylated, the metal contained in the acetylated propargyl group is not particularly limited as long as it exhibits a catalytic action, and examples thereof include copper, silver, barium and the like. Transition metals. Of these, copper and silver are preferable in consideration of environmental compatibility, and copper is more preferable in terms of availability. When the propargyl group is acetylated by using copper, the content of the propargyl group to be acetylated in the resin composition is 100 g of solid content of the resin composition.
More preferably, it is 0.1 to 20 mmol.

The curing catalyst can be introduced into the resin by converting some of the propargyl groups of the resin composition contained in the cationic electrodeposition coating composition to acetylide. In this manner, generally, it is not necessary to directly add an organic transition metal complex that is difficult to dissolve or disperse in an organic solvent or water to a coating material, and even a transition metal can be easily converted into acetylide and introduced. Even a poorly soluble transition metal compound can be freely used in a coating composition. Also, as in the case of using a transition metal organic acid salt,
The presence of the organic acid salt as an anion in the electrodeposition bath can be avoided, and the metal ions are not removed by ultrafiltration, facilitating bath management and designing a cationic electrodeposition paint. The resin composition contained in the cationic electrodeposition coating composition may contain a carbon-carbon double bond, if desired. Since the carbon-carbon double bond has high reactivity, curability can be further improved.

The content of the carbon-carbon double bond is preferably 10 to 485 mmol per 100 g of the solid content of the resin composition, after satisfying the conditions for the content of the propargyl group and the carbon-carbon double bond described later. 10 mmol / 1
If it is less than 00 g, sufficient curability cannot be exhibited by addition, and if it exceeds 485 mmol / 100 g, hydration stability when used as a cationic electrodeposition paint may be adversely affected. The content of the carbon-carbon double bond can be set to a more preferable content according to the resin skeleton used, for example, novolak phenol type epoxy resin, in the case of novolak cresol type epoxy resin, a resin composition 20 per 100g solids
Preferably it is ~ 375 mmol.

When the above-mentioned carbon-carbon double bond is contained,
The total content of the propargyl group and the carbon-carbon double bond is 80 to 450 per 100 g of the solid content of the resin composition.
It is preferably within the range of mmol. 80 mmol
If less than the curability may be insufficient,
If the amount exceeds 450 mmol, the content of the sulfonium group may decrease, and the throwing power may be insufficient. The total content of the propargyl group and the carbon-carbon double bond, a more preferable content can be set according to the resin skeleton used, for example, in the case of novolak phenol type epoxy resin, novolak cresol type epoxy resin , And more preferably 100 to 395 mmol.

When the above-mentioned carbon-carbon double bond is contained, the total content of the above-mentioned sulfonium group, propargyl group and carbon-carbon double bond is determined by the solid content of the resin composition.
It is preferably 500 mmol or less per 0 g.
If the amount exceeds 500 mmol, the resin may not be actually obtained or the desired performance may not be obtained. The total content of the sulfonium group, propargyl group and carbon-carbon double bond, depending on the resin skeleton used,
A more preferable content can be set. For example, in the case of a novolak phenol type epoxy resin or a novolak cresol type epoxy resin, the content is more preferably 400 mmol or less.

The resin composition contained in the above cationic electrodeposition coating composition is prepared, for example, by reacting a compound having a functional group reactive with an epoxy group and a compound having a propargyl group with an epoxy resin having at least two epoxy groups in one molecule. (I) obtaining an epoxy resin composition having a propargyl group by reacting the sulfide / acid mixture with the remaining epoxy groups in the epoxy resin composition having a propargyl group obtained in the step (i); It can be more suitably produced by the step (ii) of introducing a sulfonium group.

Compounds having a functional group and a propargyl group which react with the epoxy group (hereinafter referred to as "compound (A)"
) May be a compound containing both a functional group that reacts with an epoxy group such as a hydroxyl group and a carboxyl group and a propargyl group, and specific examples thereof include propargyl alcohol and propargylic acid. it can. Of these, propargyl alcohol is preferred in terms of availability and ease of reaction.

If the resin composition contained in the cationic electrodeposition coating composition has a carbon-carbon double bond, if necessary, in the step (i), a functional group which reacts with an epoxy group in the step (i). And a compound having a carbon-carbon double bond (hereinafter, referred to as “compound (B)”) may be used in combination with the compound (A). As the compound (B),
For example, a compound containing both a functional group that reacts with an epoxy group such as a hydroxyl group and a carboxyl group and a carbon-carbon double bond may be used. Specifically, when the group that reacts with the epoxy group is a hydroxyl group, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, allyl alcohol, methacryl alcohol And the like. When the group which reacts with the epoxy group is a carboxyl group, acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, maleic acid, phthalic acid, itaconic acid; maleic acid ethyl ester, fumaric acid ethyl ester, itaconic acid ethyl ester, succinic acid Half esters such as mono (meth) acryloyloxyethyl ethyl ester and mono (meth) acryloyloxyethyl phthalate; synthetic unsaturated fatty acids such as oleic acid, linoleic acid and ricinoleic acid; natural unsaturated acids such as linseed oil and soybean oil Saturated fatty acids and the like can be mentioned.

In the step (i), the compound (A) is reacted with the epoxy resin having at least two epoxy groups in one molecule to obtain an epoxy resin composition having a propargyl group, or The compound (A) and, if necessary, the compound (B) are reacted to obtain an epoxy resin composition having a propargyl group and a carbon-carbon double bond. In this latter case, step (i)
In the above, the compound (A) and the compound (B) may be mixed in advance and then used in the reaction, or the compound (A) and the compound (B) may be separately reacted. May be used. The functional group that reacts with the epoxy group of the compound (A) and the functional group that reacts with the epoxy group of the compound (B) may be the same or different.

In the step (i), when the compound (A) and the compound (B) are reacted, the mixing ratio of the two may be set so as to have a desired functional group content. What is necessary is just to set so that it may become content of a propargyl group and a carbon-carbon double bond mentioned above. The reaction conditions in the above step (i) are usually room temperature or 80 to 140
C. for several hours. In addition, if necessary, a known component necessary for advancing a reaction such as a catalyst or a solvent can be used. The completion of the reaction can be confirmed by measuring the epoxy equivalent, and the introduced functional group can be confirmed by measuring the nonvolatile content of the obtained resin composition or analyzing the instrument. The reaction product obtained in this manner is generally a mixture of an epoxy resin having one or more propargyl groups, or a mixture of a propargyl group and a carbon-
It is a mixture of epoxy resins having one or more carbon double bonds. In this sense, a resin composition having a propargyl group or a propargyl group and a carbon-carbon double bond can be obtained by the step (i).

In the step (ii), the step (i)
The sulfide / acid mixture is reacted with the remaining epoxy group in the epoxy resin composition having a propargyl group obtained in the above to introduce a sulfonium group. The sulfonium group can be introduced by reacting a sulfide / acid mixture with an epoxy group to introduce and sulfonate the sulfide, or after introducing the sulfide, and further adding an acid or methyl fluoride, methyl chloride, methyl bromide, or the like. By alkyl halide etc.
The sulfonation reaction of the introduced sulfide can be performed, and if necessary, anion exchange can be performed. From the viewpoint of availability of reaction raw materials, sulfide /
A method using an acid mixture is preferred.

The sulfide is not particularly limited.
For example, aliphatic sulfide, mixed aliphatic-aromatic sulfide, aralkyl sulfide, cyclic sulfide and the like can be mentioned. Specifically, for example, diethyl sulfide, dipropyl sulfide, dibutyl sulfide, dihexyl sulfide, diphenyl sulfide, ethyl phenyl sulfide, tetramethylene sulfide, pentamethylene sulfide, thiodiethanol, thiodipropanol, thiodibutanol, 1- (2 -Hydroxyethylthio) -2-propanol, 1- (2-hydroxyethylthio) -2-butanol, 1- (2-hydroxyethylthio) -3-butoxy-1-propanol and the like.

The acid is not particularly limited.
Formic acid, acetic acid, lactic acid, propionic acid, boric acid, butyric acid, dimethylolpropionic acid, hydrochloric acid, sulfuric acid, phosphoric acid, N-acetylglycine, N-acetyl-β-alanine and the like can be mentioned. Generally, the mixing ratio of the sulfide and the acid in the sulfide / acid mixture is preferably about 100/60 to 100/100 in terms of molar ratio.

The reaction of the above step (ii) is carried out, for example, by mixing the epoxy resin composition having a propargyl group obtained in the above step (i) with a predetermined amount of the above-mentioned sulfonium group. The mixture of the above-mentioned sulfide and the above-mentioned acid can be mixed with water of 5 to 10 times mol of the sulfide to be used, and the mixture can be usually stirred at 50 to 90 ° C. for several hours. The end point of the reaction may be based on the remaining acid value being 5 or less. Confirmation of sulfonium group introduction in the obtained resin composition can be performed by potentiometric titration. When a sulfonium-forming reaction is carried out after introduction of a sulfide, the reaction can be carried out according to the above. Further, by introducing the sulfonium group after introducing the propargyl group, decomposition of the sulfonium group due to heating can be prevented.

When a part of the propargyl group of the resin composition contained in the cationic electrodeposition coating composition is to be converted into acetylide, the epoxy resin composition having a propargyl group obtained in the above step (i) is added with a metal. React the compounds,
It can be carried out by a step of converting some of the propargyl groups in the epoxy resin composition to acetylide. The metal compound is preferably a transition metal compound that can be converted to acetylide, and examples thereof include a complex or a salt of a transition metal such as copper, silver, or barium. Specific examples include copper acetylacetone, copper acetate, silver acetylacetone, silver acetate, silver nitrate, barium acetylacetone, and barium acetate. Among them, a copper or silver compound is preferable from the viewpoint of environmental compatibility, and a copper compound is more preferable from the viewpoint of availability. For example, copper acetylacetone is preferable in view of ease of bath management. .

The reaction conditions for converting a part of the propargyl group to acetylide are usually several hours at 40 to 70 ° C. The progress of the reaction can be confirmed by coloring of the obtained resin composition, disappearance of methine proton by nuclear magnetic resonance spectrum, and the like. Thus, the reaction point at which the propargyl group in the resin composition is converted into acetylide at a desired ratio is confirmed, and the reaction is terminated. The resulting reaction product is generally a mixture of epoxy resins in which one or more of the propargyl groups has been acetylated. The above-obtained epoxy resin composition in which a part of the propargyl group is acetylated is subjected to the above step (ii).
Can introduce a sulfonium group. In addition, since the reaction conditions of the step of converting a part of the propargyl group of the epoxy resin composition to acetylide and the step (ii) can be set in common, both steps can be performed simultaneously. The method of performing both steps at the same time is advantageous because the manufacturing process can be simplified.

In this manner, a resin composition having a propargyl group and a sulfonium group and, if necessary, a carbon-carbon double bond and a part of the propargyl group converted into acetylide is prepared by suppressing decomposition of the sulfonium group. While it can be manufactured. Although acetylide has explosive properties in a dry state, the production method of the present invention is carried out in an aqueous medium, and the target substance can be obtained as an aqueous composition, so that there is no safety problem.

The cationic electrodeposition coating composition of the present invention contains the above resin composition. In the cationic electrodeposition coating composition of the present invention, the use of a curing agent is not necessarily required because the above-described resin composition itself has curability. However, it may be used to further improve the curability. Examples of such a curing agent include a propargyl group and a carbon-
Compounds having at least one of a plurality of carbon double bonds, for example, polyepoxides such as novolak phenol or pentaerythritol tetraglycidyl ether, etc.
Compounds having a propargyl group such as propargyl alcohol and compounds obtained by subjecting a compound having a carbon-carbon double bond such as acrylic acid to an addition reaction can be exemplified.

The cationic electrodeposition coating composition includes:
It is not necessary to use a curing catalyst. However, when it is necessary to further improve the curability depending on the curing reaction conditions, a commonly used transition metal compound or the like may be appropriately added as necessary. Such a compound is not particularly limited. For example, a compound in which a ligand such as cyclopentadiene or acetylacetone or a carboxylic acid such as acetic acid is bonded to a transition metal such as nickel, cobalt, manganese, palladium, or rhodium. And the like. The compounding amount of the curing catalyst is preferably 0.1 to 20 mmol per 100 g of the resin solid content of the cationic electrodeposition coating composition.

The cationic electrodeposition coating composition may contain an amine. The conversion of the sulfonium group to sulfide by electrolytic reduction in the electrodeposition process is increased by the addition of the amine. The amine is not particularly limited, and examples thereof include primary to tertiary monofunctional and polyfunctional aliphatic amines, alicyclic amines, and aromatic amines. Among these, water-soluble or water-dispersible ones are preferable, for example, alkylamines having 2 to 8 carbon atoms such as monomethylamine, dimethylamine, trimethylamine, triethylamine, propylamine, diisopropylamine, tributylamine; monoethanolamine; Examples include dimethanolamine, methylethanolamine, dimethylethanolamine, cyclohexylamine, morpholine, N-methylmorpholine, pyridine, pyrazine, piperidine, imidazoline, imidazole and the like. These may be used alone or in combination of two or more. Of these, hydroxyamines such as monoethanolamine, diethanolamine, and dimethylethanolamine are preferred because of their excellent water dispersion stability.

The above amine can be directly blended into the above cationic electrodeposition coating composition. In conventional neutralized amine-based cationic electrodeposition paints, the addition of a free amine results in deprivation of the neutralizing acid in the resin, significantly deteriorating the stability of the electrodeposition solution. Such inhibition of bath stability does not occur. The amount of the amine is preferably from 0.3 to 25 meq per 100 g of the resin solid content of the cationic electrodeposition coating composition. 0.3 meq / 1
If the amount is less than 00 g, a sufficient effect on throwing power cannot be obtained, and if it exceeds 25 meq / 100 g, an effect corresponding to the added amount cannot be obtained, which is uneconomical. More preferably, it is 1 to 15 meq / 100 g.

The cationic electrodeposition coating composition also includes
A resin composition having an aliphatic hydrocarbon group can be blended. By blending the resin composition having the above aliphatic hydrocarbon group, the impact resistance of the obtained coating film is improved. As the resin composition having an aliphatic hydrocarbon group, a sulfonium group of 5 to 400 mmol per 100 g of the resin composition solids,
80 to 135 mmol of an aliphatic hydrocarbon group which may have an unsaturated double bond having 8 to 24 carbon atoms in the chain, and an organic group and a propargyl group having an unsaturated double bond having 3 to 7 carbon atoms at the terminal. At least one of them is 10-315mm
ol, and a sulfonium group having 8 to 24 carbon atoms
The total content of an aliphatic hydrocarbon group which may contain an unsaturated double bond in the chain, an organic group having a terminal having an unsaturated double bond having 3 to 7 carbon atoms, and a propargyl group is as follows: One having 500 mmol or less per 100 g per minute can be mentioned.

When a resin composition having an aliphatic hydrocarbon group is blended with the above cationic electrodeposition coating composition, a sulfonium group of 5 to 400 mmol and a carbon number of 8 per 100 g of the resin solid content of the cationic electrodeposition coating composition are used. And a total of 10 to 300 mmol of an aliphatic hydrocarbon group which may have an unsaturated double bond in the chain, a propargyl group and an organic group having an unsaturated double bond having 3 to 7 carbon atoms at the terminal. 485 mmol, and a sulfonium group, an aliphatic hydrocarbon group and a propargyl group which may have an unsaturated double bond having 8 to 24 carbon atoms in the chain, and an unsaturated double group having 3 to 7 carbon atoms. When the total content of organic groups having a bond at the terminal is 10%, the resin solid content of the cationic electrodeposition coating composition is 10%.
500 mmol or less per 0 g, and the number of carbon atoms is 8
The content of the aliphatic hydrocarbon group which may contain from 24 to 24 unsaturated double bonds in the chain is preferably from 3 to 30% by weight of the resin solid content of the cationic electrodeposition coating composition.

When a resin composition having an aliphatic hydrocarbon group is blended with the above cationic electrodeposition coating composition, if the sulfonium group is less than 5 mmol / 100 g, sufficient throwing power and curability are exhibited. In addition, hydration and bath stability deteriorate. 400 mmol / 1
If it exceeds 00 g, deposition of the coating film on the surface of the article to be coated will be poor. In addition, an aliphatic hydrocarbon group having 8 to 24 carbon atoms and optionally containing an unsaturated double bond in the chain is 80 mmol / 1.
When it is less than 00 g, the improvement of impact resistance is insufficient,
If it exceeds 350 mmol / 100 g, the handleability of the resin composition becomes difficult. Propargyl group and carbon number 3-7
Of organic groups having an unsaturated double bond at the terminal
If the amount is less than 100 mol / 100 g, even when used in combination with another resin or a curing agent, sufficient curability cannot be exhibited. When the amount exceeds 315 mmol / 100 g, the impact resistance is improved. Will be insufficient. A sulfonium group, an aliphatic hydrocarbon group which may have an unsaturated double bond having 8 to 24 carbon atoms in the chain, a propargyl group, and an organic group having an unsaturated double bond having 3 to 7 carbon atoms at the terminal. The total content is 500 per 100 g of the resin composition solids.
mmol or less. If it exceeds 500 mmol, the resin may not be actually obtained or the desired performance may not be obtained.

The cationic electrodeposition coating composition further comprises:
If necessary, it may contain other components used in a general cationic electrodeposition coating. The other components are not particularly limited, and include, for example, paint additives such as a coloring pigment, a pigment-dispersed resin, a surfactant, an antioxidant, and an ultraviolet absorber. The color pigment is not particularly limited, and includes, for example, color pigments such as titanium dioxide, carbon black, red iron oxide and the like; extenders such as kaolin, clay, and talc; Can be mentioned. In addition, it may contain a rust preventive pigment in consideration of environmental aspects.

When the above-mentioned coloring pigment is used in the cationic electrodeposition coating composition of the present invention, it is preferably 50% by weight or less based on the solid content of the cationic electrodeposition coating composition. In addition, as a method of mixing the color pigment with the resin composition, for example, a method of preparing a dispersion paste in a pigment dispersion resin in advance and mixing it with the resin composition can be exemplified. .

The benzoin derivative contained in the cationic electrodeposition coating composition of the present invention is not particularly limited. Specifically, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether,
Benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, benzoin n-hexyl ether, benzoin n-octyl ether and the like can be mentioned. From the viewpoint of industrial availability, benzoin and / or carbon Alkyl ethers of Formulas 1 to 10 are preferable, and benzoin and / or alkyl ethers of benzoin having 1 to 4 carbon atoms are more preferable.

The content of the benzoin derivative contained in the cationic electrodeposition coating composition of the present invention is 0.1 to 10 parts by weight based on 100 parts by weight of the solid content of the resin composition.
The amount is preferably 0.3 to 2 parts by weight from the viewpoint of the smoothness of the obtained coating film. When the content is less than 0.1 part by weight, the effect of the present invention is insufficient. When the content is more than 10 parts by weight, the effect corresponding to the content is not obtained, and not only is it not economical, but also the storage stability of the coating material is low. There is a possibility that the property is reduced.

The cationic electrodeposition coating composition of the present invention can be obtained, for example, by mixing the above-mentioned components and dissolving or dispersing in water as required. When it is used for cationic electrodeposition coating, it is preferably prepared so as to have a bath solution having a nonvolatile content of 10 to 30%. Further, it is preferable that the content of the propargyl group, the carbon-carbon double bond and the sulfonium group in the cationic electrodeposition coating composition is adjusted so as not to deviate from the range of the above resin composition.

The curing temperature of the above cationic electrodeposition coating composition is preferably adjusted to 130 to 220 ° C. When the curing temperature is lower than 130 ° C., the smoothness of the multilayer coating film obtained by further coating the coating film obtained using the cationic electrodeposition coating composition of the present invention may be reduced. There is. When the curing temperature is higher than 220 ° C., the curability of the multilayered coating film may be reduced, thereby deteriorating the coating film performance, or the color difference of the multilayer coating film after applying the top coat may be caused. There is.

[0050]Cathodic electrodeposition coating method  In the cationic electrodeposition coating method of the present invention, the
It is characterized by electrodeposition coating of thion electrodeposition paint.
is there. Coated object in the cationic electrodeposition coating method of the present invention
Is not particularly limited, and may be iron, aluminum, copper,
Metals and alloys such as lead and tin can be exemplified.
Includes cold-rolled steel sheets, aluminum sheets, aluminum profiles,
Copper plate, galvanized steel plate, tin plate, iron-zinc plated alloy
Metal molded products such as steel sheet and zinc-aluminum alloyed steel sheet
And its plated products.
May be subjected to a surface treatment.

As a method of coating, for example, the object to be coated is immersed in the above-mentioned cationic electrodeposition coating composition to form a cathode, and a voltage of usually 50 to 450 V is applied between the coating and the anode. An example of a method for performing the method can be given. When the applied voltage is less than 50 V, electrodeposition becomes insufficient and
If the voltage exceeds 0 V, the power consumption increases, which is not economical. When a voltage is applied within the above range using the cationic electrodeposition coating composition, a uniform coating can be formed on the entire surface of the material without causing a sharp increase in the film thickness during the electrodeposition process. . The bath temperature of the cationic electrodeposition coating composition when the above voltage is applied is usually 10 to 4
5 ° C. is preferred. On the other hand, the time for applying the voltage varies depending on the electrodeposition conditions, but is generally 2 to 4 minutes. In the electrodeposition process, a voltage is applied between the object to be coated as a cathode and an anode, and the deposited film is
By further applying a voltage, the electric resistance per unit volume of the coating can be increased.

The electrodeposited film thus obtained may be used as it is or after washing with water after the completion of the electrodeposition process.
The coating can be cured by baking at 0 ° C., preferably 160-220 ° C. for 10-30 minutes to complete the coating. In addition, the intermediate coating uncured coating film is formed by so-called wet-on-wet coating the electrodeposition coating film obtained as described above without curing the electrodeposition coating film, which will be described later. It is also possible to carry out a two-coat one-bake system in which a multi-layer coating is obtained by simultaneously heating the coatings.

In the cationic electrodeposition coating method of the present invention,
The thickness of the cured electrodeposition coating film is preferably from 10 to 25 μm.
If it is less than 10 μm, the corrosion resistance and rust resistance may be insufficient, and if it is more than 25 μm, the paint is wasted and it is not economical.

The coated article of the present invention is obtained by the above-mentioned cationic electrodeposition coating method. Further, the coated article of the present invention can further form an intermediate coating film and / or a top coating film required on the surface according to the purpose.
The intermediate coating film can be formed by applying an intermediate coating material, and the top coating film can be formed by applying an upper coating material.

For example, the intermediate coating film has properties such as adhesion, smoothness, sharpness, overbake resistance, and weather resistance when the coated object is an outer panel of an automobile body. It is preferable that a thermosetting paint containing a binder and a curing agent is generally used as the intermediate paint to form such an intermediate paint film. As the above binder,
For example, acrylic resin, polyester resin, alkyd resin, and epoxy resin can be used. As the curing agent, various ones can be selected according to the curable functional group of the binder, and examples thereof include an amino resin, a blocked isocyanate compound, an aliphatic polycarboxylic acid and an anhydride thereof, and an epoxy resin. Resins and the like can be mentioned. The intermediate coating can take various forms such as a solvent, an aqueous or water-dispersed type, and a powder.

The overcoat film has a finished appearance (sharpness, smoothness, gloss, etc.), weather resistance (gloss retention, color retention, chalk resistance, etc.), chemical resistance, water resistance, moisture resistance. It is preferable to have a property excellent in properties, curability and the like. As such a top coating, a solid color paint used as a one-coat solid, a two-coat
Base paints and clear paints that can be applied by the bake coating method can be mentioned. It is preferable that these top coats are of a thermosetting type containing a binder and a curing agent. As the binder and the curing agent for the top coat, those described above for the middle coat can be used. The solid color paint contains a known inorganic or organic coloring pigment such as carbon black, phthalocyanine blue, and titanium dioxide. In addition, the base paint may contain a well-known glittering material such as aluminum flake and mica flake in addition to the inorganic or organic coloring pigment. On the other hand, the clear paint does not contain a pigment, but may contain the above-mentioned color pigment or glitter material to the extent that transparency is not impaired. These top coats may be water-based, solvent-based or powdery, but are preferably water-based or powdery from the viewpoint of environmental protection. In the case of water, for example, the carboxyl group of the binder is neutralized with an amine to give water solubility, and in the case of powder, the glass transition temperature can be made higher than room temperature to take each form. it can. The intermediate coating and the top coating may contain additives such as extenders, curing accelerators, leveling agents, ultraviolet absorbers, and light stabilizers.

For the coating of the intermediate coating and the top coating, a coating method known by those skilled in the art can be used according to the form of each coating, for example, a spray coating method, a brush coating method, and a dip coating method. , An electrostatic coating method or the like can be used. In particular, it is preferable to use an electrostatic coating method in a coating process in an automobile body manufacturing line.
As for the thickness of the intermediate coating and the top coating and the heating conditions after coating, values and conditions suitable for the respective coating types can be adopted. As described above, a multilayer coating film can be obtained by laminating the intermediate coating film and the top coating film on the electrodeposition coating film obtained by the cationic electrodeposition coating method of the present invention.

[0058]

【Example】Production Example 1 Sulfonium group and propargyl group
Of epoxy resin composition solution having  Epotote YDCN-701 having an epoxy equivalent of 200.4
(Cresol novolak epoxy tree manufactured by Toto Kasei Co., Ltd.
Fat) to 100.0 parts by weight of propargyl alcohol
6 parts by weight and 0.3 parts by weight of dimethylbenzylamine are stirred
Equipped with a thermostat, thermometer, nitrogen introduction pipe and reflux cooling pipe
Add to the flask, raise the temperature to 105 ° C, and react for 3 hours
Contains propargyl group with epoxy equivalent of 1580
To obtain a resin composition. Copper acetylacetona
2.5 parts by weight, and reacted at 90 ° C. for 1.5 hours.
Was. Proton (1H) NMR by propargyl terminal
It was confirmed that a part of hydrogen had disappeared (14 mmo).
1/100 g Resin solid content equivalent amount of acetylated
Containing a lopargyl group). To this, 1- (2-hydro
(Xyethylthio) -2,3-propanediol 10.6
Parts by weight, 4.7 parts by weight of glacial acetic acid, 7.0 parts by weight of deionized water
While keeping the temperature at 75 ° C for 6 hours,
5 or less, and then 43.8 layers of deionized water
Then, the desired resin composition solution was obtained. Of this one
The solid content is 70.0% by weight, and the sulfonium value is 28.
It was 0 mmol / 100 g varnish. Number average molecular weight
(GPC in terms of polystyrene) was 2,443.

[0059]Production Example 2 Preparation of benzoin dispersion composition solution
Made  1429.0 parts of the epoxy resin composition obtained in Production Example 1
Benzoin, 1000.0 parts by weight, deionized water 157
Add 1.0 part by weight, stir for 10 minutes with a lab mixer,
Mix to make a premix. Then premixed
Transfer to a container for dispersion, and add the same amount of zirconium beads.
After charging, keep the temperature in the container at 40 ° C for 1 hour
Disperse in a sand grind mill and grind
The process was completed when the particle size became 5 μm or less. Get
The resulting dispersion is filtered to give 50% solids benzoin by weight.
A dispersion composition solution was obtained.

[0060]Example 1 Cationic electrodeposition coating composition 1  Epoxy resin composition solution obtained in Production Example 1
568.0 parts by weight, benzoin dispersion obtained in Production Example 2
4.8 parts by weight of composition solution and 1427.2 parts deionized water
Stir and mix parts by weight and add deionized water to
For 20% by weight of form and 100 parts by weight of resin solids,
Cationic electrodeposition coating composition containing 0.3 parts by weight of benzoin
The product 1 was obtained.

[0061]Example 2 Cationic electrodeposition coating composition 2  Epoxy resin composition solution obtained in Production Example 1
548.4 parts by weight, benzoin dispersion obtained in Production Example 2
32.0 parts by weight of the composition solution and 1419. deionized water.
Stir and mix 6 parts by weight, add more deionized water,
20% by weight of solid content and 100 parts by weight of resin solid content
Electrodeposition coating containing 2.0 parts by weight of benzoin
The composition 2 was obtained.

[0062]Example 3 Cationic electrodeposition coating composition 3  Epoxy resin composition solution obtained in Production Example 1
480.0 parts by weight, benzoin dispersion obtained in Production Example 2
128.0 parts by weight of composition solution and 139 deionized water
Stir and mix 2.0 parts by weight and add deionized water
With a solid content of 20% by weight and a resin solid content of 100 parts by weight.
Cation electrodeposition containing 8.7 parts by weight of benzoin
A coating composition 3 was obtained.

[0063]Comparative Example 1 Cationic electrodeposition coating composition 4  Epoxy resin composition solution obtained in Production Example 1
571.6 parts by weight and 1428.4 parts by weight of deionized water
Is stirred and mixed, and further deionized water is added to give a solid content of 2.
0% by weight and benzoin-free cationic electrodeposition coating
Composition 4 was obtained.

[0064]Comparative Example 2 Cationic electrodeposition coating composition 5  Epoxy resin composition solution obtained in Production Example 1
457.2 parts by weight, benzoin dispersion obtained in Production Example 2
160.0 parts by weight of the composition solution and 138 deionized water
Stir and mix 2.8 parts by weight, then add deionized water
With a solid content of 20% by weight and a resin solid content of 100 parts by weight.
Cations containing 11.1 parts by weight of benzoin
A coating composition 5 was obtained.

[0065]Comparative Example 3 Cationic electrodeposition coating composition 6  Power Top U-80 (Nippon Paint Co., Ltd.
Socyanate-curable amino epoxy resin based cationic electrodeposition
Paint, solids content 20% by weight)
32.0% by weight of the benzoin dispersion composition solution obtained in Example 2
Parts and 64.0 parts by weight of deionized water, and then stirred and mixed.
And benzoin is added to 100 parts by weight of resin solids.
A cationic electrodeposition coating composition 6 containing 2.0 parts by weight was obtained.
Was.

[0066]Example 4  The cationic electrodeposition coating composition 1 obtained in Example 1 was stained with stainless steel.
And transferred to an electroless bath. Fill with deionized water
75x150x0.8mm phosphorous acid in a beaker
After fully submerging the lead-treated steel sheet, pull it up and place
As an anode and a steel plate as a cathode.
Electrodeposition coating was performed to a thickness of μm. After electrodeposition coating,
Lift the equipment from the electrodeposition bath in the stainless steel container and wash it with water
And put in a drying oven set at 180 ° C for 30 minutes to heat
Thus, a test plate 1 on which a cationic electrodeposition coating film was formed was obtained. What
The electrodeposition coating voltage was 250V.

[0067]Examples 5 and 6, and Comparative Examples 4 to 6  Instead of the cationic electrodeposition coating composition 1 obtained in Example 1
The cationic electrodeposition coating compositions 2 to 6 were used, respectively.
Test plates 2 to 6 were obtained in the same manner as in Example 4 except for the above.
The electrodeposition coating voltage was 250 V, 240 V, respectively.
245V, 240V and 235V.

[0068]Comparative Example 7  Instead of the cationic electrodeposition coating composition 1 obtained in Example 1
Example 4 except that a power top U-80 was used.
In the same manner as in the above, a test plate 7 was obtained. . The electrodeposition coating voltage
Was 230V.

<Evaluation Test> Examples 1 to 3 and Comparative Example 1
About the cationic electrodeposition coating compositions 1 to 6 obtained in Examples 1 to 3 and the power top U-80 used in Comparative Example 7, and the test plates 1 and 2 obtained in Examples 4 to 6 and Comparative Examples 4 to 7. About 7, the following items were evaluated. The evaluation results are shown in Table 1.

[0070]Environmental compatibility  In each of the obtained cationic electrodeposition coating compositions, harmful weight such as lead
It was evaluated whether metal was included. ○: Hazardous heavy metals are not contained ×: Hazardous heavy metals are contained

[0071]Storage stability  Each of the obtained cationic electrodeposition coating compositions was set at 40 ° C.
After being stored in a thermostat for 60 days, the paint condition is visually evaluated.
did. The evaluation criteria were as follows. ：: No significant change from the initial stage ×: There is a precipitate or there is a remarkable increase in viscosity
It was evaluated whether it had occurred. The evaluation results are as follows
And ：: Non-uniform part is not visually observed. Δ: Non-uniform part is visually observed, but maximum film thickness difference is 5 μm.
×: less than m: non-uniform part is visually observed and the maximum film thickness difference is 5 μm or less
Is on

[0072]Corrosion protection  Reach the substrate surface with a cutter knife on the coating surface of the obtained test plate
Into a salt spray test (5 wt% salt)
(Water, 35 ° C) for 960 hours.
The maximum tape peeling width from the cut part (one side)
evaluated. Each evaluation standard was as follows. ○: less than 2 mm ×: 2 mm or more

<Adhesiveness> Each of the obtained test plates was sprayed with Olga P-2 gray (melamine-curable acrylic resin-based intermediate paint from Nippon Paint Co., Ltd.) so as to have a dry film thickness of 35 μm. After that, the resultant was cured by heating at 140 ° C. for 30 minutes to obtain an intermediate coating plate having an intermediate coating film formed thereon.
Each of the obtained intermediate coated plates has a width of about 1.5 mm,
After inserting one cut into a bang, a 24 mm wide cellophane adhesive tape was adhered and the number of peels of the bang-like cut when strongly peeled was evaluated. Was 0.

[0074]

[Table 1]

As can be seen from Table 1, the cationic electrodeposition coating composition of the present invention was excellent in environmental compatibility and storage stability, and was able to improve water sliminess without lowering the corrosion resistance. .

[0076]

The cationic electrodeposition coating composition of the present invention is a resin composition having a sulfonium group and a propargyl group and a cationic electrodeposition coating composition containing a predetermined amount of benzoin. The film can prevent deposition film defects in the electrodeposition coating process, which is often regarded as a problem in conventional electrodeposition coatings, from reducing the storage stability of the coating and the corrosion resistance of the resulting coating, and reducing the coating voltage during electrodeposition coating. It can be improved without lowering or causing side effects such as inhibition of adhesion when directly applying a direct coating such as an intermediate coating or a top coating to the obtained electrodeposition coating film. Further, the cationic electrodeposition coating composition of the present invention does not contain harmful heavy metals such as lead, and thus does not cause environmental pollution. Furthermore, there is no need to treat wastewater containing harmful heavy metals, which is economical.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshitaka Kawanami 19-17 Ikedanakacho, Neyagawa-shi, Osaka Japan Paint Co., Ltd. (72) Inventor Ichiro Kawakami 19-17 Ikedananakacho, Neyagawa-shi, Osaka Nippon Paint F term in the company (reference) 4J038 DB031 DB071 DB091 DB201 DB221 DB311 DB331 DB351 DB401 FA012 FA251 GA01 GA13 JA19 JA33 JA37 JC17 MA14 NA03 NA23 PA04

Claims (8)

[Claims] 1. A cationic electrodeposition comprising a resin composition having a sulfonium group and a propargyl group, and 0.1 to 10 parts by weight of a benzoin derivative based on 100 parts by weight of a solid content of the resin composition. Paint composition. 2. The cationic electrodeposition coating composition according to claim 1, wherein the benzoin derivative is benzoin and / or an alkyl etherified product of benzoin having 1 to 10 carbon atoms. 3. The sulfonium group and the propargyl group have a sulfonium group content of 5 to 400 mmol and a propargyl group content of 1 to 100 mmol per 100 g of solid content of the resin composition.
The cationic electrodeposition coating composition according to claim 1, which contains 0 to 495 mmol, and has a total content of sulfonium groups and propargyl groups of 500 mmol or less. 4. The sulfonium group and the propargyl group may contain 5 to 250 mmol of a sulfonium group and 2 g of a propargyl group per 100 g of the solid content of the resin composition.
The cationic electrodeposition coating composition according to any one of claims 1 to 3, comprising 0 to 395 mmol, and having a total content of sulfonium groups and propargyl groups of 400 mmol or less. 5. The cationic electrodeposition coating composition according to claim 1, wherein the resin composition has an epoxy resin as a skeleton. 6. The epoxy resin is a novolac cresol type epoxy resin or a novolak phenol type epoxy resin, and has a number average molecular weight of 700 to 5,000.
The cationic electrodeposition coating composition according to claim 5, which is: 7. A cationic electrodeposition coating method in which a cationic electrodeposition coating is electrodeposited on an object to be coated, wherein the cationic electrodeposition coating is according to any one of claims 1 to 6. A cationic electrodeposition coating method, which is a composition. 8. A coated article obtained by the cationic electrodeposition coating method according to claim 7.