JPS6114189B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to water-soluble curable coating compositions, in particular:
The present invention relates to a composition suitable for electrodeposition coating using an object to be coated as a cathode, and a method for producing the composition. Conventionally, in water-soluble paints, especially electrodeposition paints, resins with acid groups, such as maleated oil, maleated polybutadiene, alkyd resins, or acrylic acid or methacrylic acid, are used as copolymerization components, and acrylic resins are mixed with bases such as ammonia, amines, and caustic potassium. A resin made water-soluble by neutralization is used. These resins dissociate in water and become resins with anions, so in electrodeposition coating, the object to be coated is used as an anode, and the resin with anions is precipitated at the anode. ing. However, since the anodic deposition electrodeposition coating method uses the metal to be coated as the anode, the metal to be coated is oxidized by the water electrolyzed oxygen generated at the anode, and some of it is eluted. There's a problem. Some of the eluted metals remain in the electrodeposition coating, contaminating and coloring the coating. For example, if the object to be coated is made of iron, the white paint will be colored brown, and if it is made of aluminum, it will be colored yellow. To contaminate. Further, metal ions remaining in the coating film significantly reduce the corrosion resistance of the coating film. The paint bath liquid is also contaminated by eluted ions, resulting in a significant loss of stability of the electrocoating bath. The problem of elution and contamination mentioned above is that the metal to be coated is
Not only does this occur in the case of phosphate treatment for rust prevention, but also the phosphate coating that has been painstakingly applied dissolves and significantly reduces the rust prevention effect. Furthermore,
The coating film of this type of paint does not have sufficient alkali resistance. On the other hand, if electrodeposition coating can be performed using the object to be coated as a cathode, there will be no elution of metal from the object or surface treatment film, so the coating will not be colored by eluted ions and will have good corrosion resistance. In addition, various advantages can be expected, such as the ability to perform electrodeposition coating on metals that are difficult to perform electrodeposition coating on because metals are easily eluted by the anodic electrodeposition method. In order to carry out this cathodic deposition electrodeposition coating method,
A water-soluble resin is needed that can form a cationic resin in water and deposit on the cathode. Various studies have been conducted on the production method of the cathode-deposited water-soluble resin, including modified epoxy resin (Japanese Patent Publication No. 49-23807, Japanese Patent Publication No. 49-81736), Modified acrylic resins made by radical copolymerization of acrylic monomers containing tertiary amines such as acrylic monomers, and various acrylic monomers or other monomers
12395, Special Publication No. 45-39351), etc. were proposed. However, the above-mentioned known cathodically deposited electrodeposition paints have various drawbacks such as high curing temperature and low crosslinking density, and have not yet been put into practical use industrially. Originally, water-soluble paint films are generally easily dissolved in water as they are, so they must be crosslinked and cured by some means.
It is required to be sufficiently hardened by baking for about a minute. In order to meet this requirement, conventional methods include mixing or precondensing melamine formaldehyde resins and phenol formaldehyde resins;
Alternatively, a method of changing the pressure using drying oil is used.
However, such a method is not suitable for cathodically deposited electrodeposition coating resins. This is because cathodically deposited resins do not have acid groups, so even if melamine formaldehyde resin or phenol formaldehyde resin is added, they do not cure sufficiently, or because they do not have electrophoretic copropagation properties, the coating film is difficult to form. This is because the composition may change. Furthermore, in the case of electrodeposition coating, even if a water-soluble basic resin can be synthesized and cathodically deposited by electrodeposition coating, if it shows a good coating condition and does not have excellent coating performance, the resin for electrodeposition coating cannot be used. Its practical value will be low. Furthermore, the stability of the paint must be sufficient even at low concentrations when diluted, at the paint concentration before dilution, and even during storage and running. Therefore, an object of the present invention is to provide a curable water-soluble resin suitable for cathodic deposition type electrodeposition coatings, which eliminates the above-mentioned conventional drawbacks, has improved curability, and can be easily made water-soluble. is to provide. Furthermore, it is an object of the present invention to provide a highly storage-stable material that can be provided with a corrosion-resistant coating that has excellent resistance to external mechanical forces such as impact or bending, and chemical resistance such as alkali resistance, water resistance, and solvent resistance. The present invention provides a method for producing a coating composition. As a result of intensive research in order to achieve the above object, the present inventors have discovered that conventional water-soluble paints or By reacting a secondary amine with a resin in which an epoxy group has been introduced into a high molecular weight compound containing an unsaturated group, which was known as an anodic electrodeposition coating, a cathodic deposition resin that provides excellent curability and coating properties was obtained. We have already applied for a patent. As a result of further research, the present inventors have found that by reacting a primary amine with a resin in which epoxy groups are introduced into the unsaturated group-containing high molecular weight compound, excellent curability, film properties, adhesion, and high hydrogen ion concentration can be achieved. It was discovered that a resin for cathodically deposited electrodeposition paints which can be made water-soluble can be obtained, and the present invention was achieved. That is, the object of the present invention is to provide a main chain polymeric portion (a) containing a carbon-carbon double bond with a molecular weight of 500 to 10,000 and an iodine value of 100 to 500, and a main chain polymeric portion (a) that is bonded to the main chain polymeric portion. The basic group (b) contains a water-soluble resin as a film-forming component, and the basic group has the general formula (b) in an aqueous solution.

[Formula] (In the formula, R ₁ and R ₂ are hydrogen atoms or methyl groups; R ₃
is an organic residue having ₁ to 10 carbon atoms; X represents a hydrogen atom or a _bond , and if can be formed. ), and per 100 grams of resin
It is contained in a proportion of 0.02 to 0.4 mol, and is achieved by neutralizing the resin with an organic or inorganic acid to make it water-soluble. Carbon-carbon double bond and general formula forming the coating forming component of the coating composition of the present invention

[Formula] (where R ₁ and R ₂ are hydrogen atoms or methyl groups;
R ₃ is an organic residue having 1 to 10 carbon atoms; and X is a hydrogen atom or a bond; if X is a bond,
The carbon atom attached to R ₁ and the carbon atom attached to R ₂ can both form part of the main chain. ) The resin containing the group is a new high molecular weight compound, which has (A) a molecular weight of 500 to 10,000 and a molecular weight of 100 to 10,000.
A main chain high molecular weight moiety having a carbon-carbon double bond with an iodine value of 500 and bonded to the main chain high molecular weight moiety, the general formula

[Formula] (X, R ₁ , R ₂ are the same as above) consisting of an epoxy group, and resin 100
(B) General formula

[Formula] (In the formula, R ₃ represents an organic residue having 1 to 10 carbon atoms.) A primary amine represented by the formula is reacted to produce a resin having a basic group, a hydroxyl group, and an unsaturated group, and this is mixed with an organic acid. Alternatively, it can be produced by neutralizing with an inorganic acid and making it water-soluble. The main chain portion of the resin used in the present invention is
Carbon with an iodine value of 100 to 500, preferably 200 to 450
It is derived from high molecular weight compounds having a carbon double bond and a number average molecular weight (hereinafter simply referred to as molecular weight) of 500 to 10,000. Examples of such high molecular weight compounds include low polymers of conjugated diolefins such as butadiene, isoprene and piperylene, low degree copolymers of two or more of these conjugated diolefins, and one or more of these conjugated diolefins. and vinyl monomers having ethylenic unsaturation, especially aliphatic or aromatic vinyl monomers such as isobutylene, diisobutylene, styrene, α-methylstyrene, vinyltoluene, divinylbenzene. A mixture of two or more of these can also be used. These low polymers are produced by conventionally known methods. That is, using an alkali metal or an organic alkali metal compound as a catalyst, the carbon number is 4 to 5.
conjugated diolefin alone, or together with these diolefins, or an aromatic vinyl monomer, such as styrene, α-methylstyrene, preferably in an amount of 50 mol % or less relative to the conjugated diolefin.
vinyltoluene or divinylbenzene at 0℃
A typical manufacturing method is anionic polymerization at a temperature of ~100°C. In this case, controlling the molecular weight,
In order to obtain light-colored low-polymerization with a low gel content, a chain transfer polymerization method (US Patent No. 3789090) or a living polymerization method in which a polycyclic aromatic compound such as naphthalene is used as an activator in a tetrahydrofuran solvent and an alkali metal such as sodium is used as a catalyst (Japanese Patent Publication No. 17485/1986, No. 43-27432); Polymerization method using an aromatic hydrocarbon such as toluene or xylene as a solvent, a metal dispersion such as sodium as a catalyst, and controlling the molecular weight by adding an ether such as dioxane (Japanese Patent Publication No. 32-7446, Same 33
-1245, No. 34-10188) are suitable manufacturing methods. It is also produced by coordination anionic polymerization using an acetyl acetate compound of a group 8 metal such as cobalt or nickel and an alkyl aluminum halide (Japanese Patent Publication No. 45-507
No. 46-30300) low polymers can also be used. In addition, unsaturated groups are produced by cationic polymerization of petroleum cracked fractions having 4 to 10 carbon atoms at temperatures of 0 to 100°C using Friedel-Crafts catalysts such as ammonium chloride, boron trifluoride, or their complexes. So-called petroleum resins having the above-mentioned petroleum resins, as well as butadiene-isobutylene low polymerization degree copolymers produced using the same type of catalysts, can also be used as the main chain portion of the resin used in the present invention. The low polymerization degree copolymer or copolymer of the conjugated diolefin mentioned above has a molecular weight in the range of 500 to 10,000, preferably 1,000 to 5,000. molecular weight
When the molecular weight is greater than 10,000, the solubility in water is poor, and when the molecular weight is less than 500, the strength of the coating film is so low that it cannot be used practically. The above-mentioned low degree of polymerization conjugated diolefin polymer or copolymer has an iodine value of 100 to 500, preferably 200.
~450 are used. If the iodine value is less than 100, the curability will be poor, and if it is more than 500, the storage stability will be poor, making it impractical. The iodine value used in this specification is calculated by taking approximately 0.1 g of a sample into a 500 ml iodine value measurement flask, adding 100 ml of chloroform and 100 g of p-dichlorobenzene to dissolve it, and adding 0.1 N of iodine monochloride to the sample. Add 60 ml of carbon tetrachloride solution and react by soaking at room temperature for 1 hour. Add 10 ml of 10% potassium iodide aqueous solution and soak for 5 minutes. Next, add 0.1 N thiosulfate using starch as an indicator. Titration method with aqueous sodium solution (A.Kemp and H.Peters.
Ind.Eng.Chem.Anal.Ecl.15 453 (1943)). The general formula for the above conjugated diolefin low polymer or copolymer is

[Formula] (where R ₁ and R ₂ are hydrogen atoms or methyl groups;
X represents a hydrogen atom or a bond, and when X is a bond, the carbon atom to which R ₁ is attached and the carbon atom to which R ₂ is attached can both form a part of the main chain. ) For example, 0 to
A conventionally known method of reacting peracetic acid at a temperature of 100°C can be used. (Tokuko Show 33-3239,
Special Publication 33-3240, Special Publication 37-15107) The above general formula

The amount of epoxy group represented by the formula is in the range of 0.02 to 0.4 mol, preferably 0.05 to 0.2 mol, per 100 g of resin. If the amount of the above epoxy groups is less than 0.02 mol per 100 g of resin, the general formula

When the resin obtained by reacting with the primary amine compound represented by the formula is neutralized with acid to make it water-soluble, the water solubility is poor, and when the amount of the epoxy group is more than 0.4 mole, the water solubility is poor. Because the coating is so good, it has poor water resistance and cannot be used practically when made into a coating. The above general formula used in the present invention

Examples of primary amine compounds represented by the formula are alkyl primary amines such as monomethylamine, monoethylamine, monopropylamine, monobutylamine, monomexylamine, and monooctylamine, and aromatic primary amines such as benzylamine. and primary alkanolamines such as monoethanolamine, monopropanolamine, etc. The primary amine compound used is preferably used in an equimolar amount to the epoxy group of the high molecular weight component (A), but it is also possible to use an excess of the primary amine and distill it off after the reaction. be. Also, less than equimolar amounts of primary amine may be used to leave some epoxy groups. The reaction between component (A), a polymer having an epoxy group and a carbon-carbon double bond, and component (B), a primary amine compound, is carried out at a temperature of 50 to 200°C, preferably 100 to 150°C. . The above reaction can be carried out in the presence or absence of a solvent. If the viscosity of the epoxy group- and double bond-containing polymer used in the reaction is low, it is preferable not to use a solvent, but if the component (A) compound has a high viscosity, benzene , toluene, xylene, cyclohexane, methyl cellosolve, ethyl cellosolve, propyl cellosolve, butyl cellosolve, ethyl ether, glyme, diglyme, and the like can be used. When using solvents, use e., lucerosolve, methyl cellosolve, butyl cellosolve, glyme,
It is economical and preferable to use a water-soluble solvent such as diglyme as a reaction solvent and directly make it water-soluble. Water, phenol, and an acid such as acetic acid are added as a catalyst to promote the reaction between the polymer having an epoxy group and a carbon-carbon double bond (A) and the primary amine compound (Component ₂₎ . method can also be adopted. In the present invention, in order to water-solubilize the resin having a carbon-carbon double bond and a secondary amine basic group synthesized by the reaction of a primary amine and an epoxy group-containing resin, it is necessary to A method of neutralizing with 0.2 to 1.0 molar equivalent of an inorganic acid such as hydrochloric acid or sulfuric acid or a water-soluble acid such as formic acid, acetic acid, propionic acid or lactic acid can be suitably used. The coating composition of the present invention uses the above-mentioned resin having a carbon-carbon double bond and a basic group as a film-forming component,
This can be dissolved or dispersed in water, and can also contain a water-soluble organic solvent. For example, when making the resin water-soluble, for the purpose of making it easier to make the resin water-soluble, improving the stability of the aqueous solution, improving the fluidity of the resin, and improving the smoothness of the coating film. , ethyl cellosolve, propyl cellosolve, butyl cellosolve, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diacetone alcohol, 4-methoxy-4-methyl-pentanone-, which are water-soluble and can dissolve the resin of the present invention.
It is preferable to use 100 g to 10 g of an organic solvent such as No. 2 per 100 g of resin. The amount of the coating forming component of the present invention, that is, the reaction product of component (A) and component (B) or the water-soluble chemical product thereof, contained in the coating composition of the present invention is not particularly limited, but usually this reaction Per 100 parts by weight of product or water-solubilized product, 0 to 100 parts by weight of solvent, 0 to 300 parts by weight of various pigments
parts by weight and 0 to 2000 parts by weight of water, and in the case of a water-solubilized product, the water content is preferably 50 to 1000 parts by weight. A suitable pigment such as titania, titania,
Water-soluble paints containing red iron, carbon black, etc., and anti-rust pigments such as strontium chromate are self-curing, so a multi-component resin that is mixed with other ingredients to give thermosetting properties can be electrodeposited. There is no risk of uneven bath composition, which is often a problem when used in paints, and since it is a cathodic electrodeposition coating method, there is no color contamination of the paint film, instability of the electrodeposition bath, and rust prevention ability. An extremely excellent water-soluble paint for electrodeposition can be obtained without any drawbacks such as a decrease in viscosity. In addition to electrodeposition coating, the self-curing water-soluble resin of the present invention can also be used in water-soluble paints applied by conventional methods such as spraying and dipping. Next, the present invention will be explained in more detail with reference to Examples. In addition, the physical property test of the coating film in the example was JIS-K-
5400. Example 1 Synthesized using sodium benzyl as a catalyst
1.2 Liquid polybutadiene (A) with a bond of 58%, a number average molecular weight of 800, and a viscosity of 7 voids at 25°C was epoxidized using peracetic acid, and the oxirane oxygen content was 3.0wt.
% of epoxidized polybutadiene (A') was produced. 1000 g of epoxidized polybutadiene (A'), 114 g of monoethanolamine, and 20 g of phenol were placed in a two-separable flask equipped with a reflux condenser, and after reacting at 160°C under a nitrogen stream for 6 hours, unreacted materials were removed under reduced pressure. Distilled, amine value 90, viscosity 350
Polybutadiene (A″) with amine groups was produced at 25°C. 300g of polybutadiene (A″) with amine groups was dissolved in 60g of butyl cellosolve, neutralized with 15.4g of acetic acid, and deionized water was added to solidify. An aqueous solution with a concentration of 30 wt% was prepared. 600g of the above 30wt% aqueous solution, 650g of titania, 24g of carbon black, strontium chromate
24g, aluminum silicate 100g glass beads
After putting 1000 g into two stainless steel beakers and stirring vigorously for 2 hours with a high-speed rotating mixer, the mixture was passed through glass beads to produce a pigment paste (A) with very good water dispersibility. Example 2 Synthesized using sodium benzyl as a catalyst
1.2 Liquid polybutadiene (B) with a bond of 63%, a number average molecular weight of 1400, and a viscosity of 60 poise at 25°C was epoxidized using peracetic acid to determine the oxirane oxygen content.
3.5wt% epoxidized polybutadiene (B') was produced. A separable flask equipped with a reflux condenser was charged with 200 g of epoxidized polybutadiene (B'), 40 g of butyl cellosolve, 26.7 g of monoethanolamine, and 7.9 g of water as a reaction promoter, and reacted at 130 °C for 6 hours under a nitrogen stream. After that, unreacted monoethanolamine, butyl cellosolve used as a solvent, and water used as a reaction promoter were distilled off under reduced pressure to synthesize polybutadiene (B'') having an amine group with an amine value of 81.7 (mgKOH/g). 100g of polybutadiene (B″) with amine groups
was dissolved in 20 g of butyl cellosolve, neutralized by adding 5.2 g of acetic acid, and then added with deionized water to determine the solid content concentration.
A 20wt% aqueous solution was prepared. This aqueous solution was transparent and had good storage stability. Above 20wt
% aqueous solution of the pigment paste prepared in Example 1
After adding 63.1 g and stirring thoroughly, deionized water was added to prepare an electrodeposition coating liquid with a solid content concentration of 12 wt%. Using the above coating liquid, a carbon electrode is used as an anode,
Cathode deposition type electrodeposition coating was performed using a Bonderite #3114 treated mild steel plate (manufactured by Nippon Test Panel Co., Ltd., 0.6 x 70 x 150 mm) as a cathode. The test results are shown in Table 1. Example 3 200 g of epoxidized polybutadiene (B') used in Example 2 was collected in a separable flask equipped with a reflux condenser, and 40 g of butyl cellosolve, 2 g of phenol, and 21.4 g of monoethanolamine were added.
The reaction was carried out at 150°C for 2.5 hours. Butyl cellosolve, unreacted monoethanolamine, etc. were distilled off under reduced pressure to synthesize polybutadiene (C″) with amine groups and an amine value of 44.7 (mgKOH/g). 100 g of polybutadiene (C″) with amine groups.
After dissolving in 20g of butyl cellosolve, 2.9g of acetic acid
After neutralization, add deionized water to determine the solid content concentration.
A 20wt% aqueous solution was prepared. Although this aqueous solution was milky white, it was sufficiently stable. 63.1 g of the pigment paste prepared in Example 1 was added to the above 20 wt% aqueous solution and stirred thoroughly, and then deionized water was added to prepare an electrodeposition coating liquid with a solid content concentration of 12 wt%. Using the above coating liquid, a carbon electrode is used as an anode,
Cathode deposition type electrodeposition coating was performed using a Bonderite #3114 treated mild steel plate (manufactured by Nippon Test Panel Co., Ltd., 0.6 x 70 x 150 mm) as a cathode. The test results are shown in Table 1. Example 4 Synthesized using sodium benzyl as a catalyst
1.2 Liquid polybutadiene (D) with 60% bonding, number average molecular weight 1000, and viscosity 15 poise at 25°C was epoxidized using peracetic acid to determine the oxirane oxygen content.
3.6wt% epoxidized polybutadiene (D') was produced. In a separable flask equipped with a reflux condenser, add 200 g of epoxidized polybutadiene (D'), 40 g of butyl cellosolve, and 26.7 g of monoethanolamine.
Then, 8 g of water and 0.75 g of acetic acid were charged as a reaction accelerator, and the reaction was carried out at 145°C for 8 hours under a nitrogen stream. Unreacted monoethanolamine, butyl cellosolve, etc. were then distilled off under reduced pressure. Polybutadiene having an amine group with an amine value of 78.0. (D″) was synthesized. 100g of polybutadiene (D″) with amino groups
was dissolved in 20 g of butyl cellosolve, neutralized by adding 5.0 g of acetic acid, and then added with deionized water to determine the solid content concentration.
A 20wt% aqueous solution was prepared. Next, in the same manner as in Example 2, pigments were mixed and diluted with deionized water to prepare an electrodeposition coating liquid having a solid content concentration of 12 wt%. The cathodically deposited electrodeposition paint was tested in the same manner as in Example 2. The results are shown in Table 1. Example 5 200 g of epoxidized polybutadiene (B') used in Example 2, 40 g of butyl cellosolve, 56 g of n-octylamine, and phenol as a reaction accelerator.
4 g was charged and reacted at 160°C for 4 hours under a nitrogen stream, and then unreacted amine, butyl cellosolve, etc. were distilled off to synthesize polybutadiene (E″) with an amine group and an amine value of 90. Polybutadiene with amino groups (E″) 100g
was dissolved in 20 g of butyl cellosolve, neutralized by adding 5.8 g of acetic acid, and then added with deionized water to determine the solid content concentration.
A 20wt% aqueous solution was prepared. Next, in the same manner as in Example 2, pigments were mixed and diluted with deionized water to prepare an electrodeposition coating liquid having a solid content concentration of 12 wt%. The cathodically deposited electrodeposition paint was tested in the same manner as in Example 2. The results are shown in Table 1.

【table】

Claims (1)

[Scope of Claims] 1 (A) An epoxy group-containing resin obtained by epoxidizing a conjugated diolefin polymer containing carbon-carbon double bonds with a molecular weight of 500 to 10,000 and an iodine value of 100 to 500, and Epoxy group-containing resin
An epoxy group-containing resin containing 0.02 to 0.4 moles of the epoxy group per 100 grams is added to (B) the general formula [formula] (wherein R ₃ represents an organic residue having 1 to 10 carbon atoms). ) A resin having a basic group, a hydroxyl group, and an unsaturated group is produced by reacting the primary amine shown in
0.4 mole of the resin, and the method for producing a cathodic deposition type electrodeposition coating composition comprises neutralizing the resin with an organic acid or an inorganic acid to make it water-soluble.