JPH0244849B2 - JIKOKOKASEIJUSHINOSEIZOHOHO - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for producing a water-dispersible, low-temperature-curing self-curing resin suitable for cationic electrodeposition coating.

[Conventional technology]

Cationic electrodeposition coating has superior anti-corrosion properties for coated objects compared to conventional anionic electrodeposition coating, and therefore its use has been increasing in recent years, mainly in the automotive coating field. Various resins have been proposed for use in such cationic electrodeposition coatings, one of which is disclosed in Japanese Patent Application No. 72924/1983. The invention provides the following formula by introducing an amine imide group pendant into a polyamine resin having an amino group or an imino group. After the amine imide group is thermally decomposed at a low temperature of 120°C to 170°C, preferably 140 to 160°C, the tertiary amine is eliminated by rearrangement and an isocyanate group is generated, and the generated isocyanate group is It reacts with the hydroxyl group, amino group, or imino group in the resin to form a three-dimensional structure to obtain an infusible and insoluble cured coating, and the amine imide group is neutralized with acid to become an acylhydrazinium base. In particular, by taking advantage of the fact that a stable aqueous dispersion of a cationic resin can be obtained, the resin composition is made suitable for cationic electrodeposition coating.

[Problems to be Solved by the Invention] The method for producing an amine imide group-containing amino-modified polyepoxide (hereinafter referred to as a self-curing resin) described in JP-A No. 60-72924 involves the step of manufacturing a polyepoxide and a polyepoxide in the first step. A polyamine resin is obtained by reacting with a first monoamine or a ketimine-blocked amino group-containing polyamine, and then in a second step, the polyamine resin and an ethylenically unsaturated compound having an amine imide group (hereinafter referred to as an amine imide compound) are produced.
This is done by reacting with. However, in this manufacturing process, the proportion of the polyamine resin in the first step in the self-curing resin is very large, so it is not possible to manufacture several batches of polyamine resin in advance using a manufacturing device with a fixed volume. First, it is necessary to produce polyamine resin for each batch. In addition, in order to obtain a polyamine resin, it is necessary to introduce into the resin a nitrogen-containing group having an active hydrogen that is capable of Michael-type addition. Polyamines containing blocked amino groups or mixtures thereof must be used. In this case, if the primary monoamine is used, it must be used in large excess to prevent gelation with the polyepoxide, and unreacted amine must be removed after the reaction. In addition, the ketimine-blocked amino group-containing polyamine does not gel at the stage of reaction with the epoxy group because it contains imino groups, but since the polyamine is used, the concentration of nitrogen-containing groups in the resin may be higher than necessary. There is a tendency for the coating film performance to deteriorate due to the increase in the amount of water.

[Means to solve the problem]

In order to solve the above-mentioned problems, the present inventors have conducted intensive research and have produced a Michael-type adduct of an amine imide compound and a primary monoamine, and then converted this Michael-type adduct to polyepoxide. By adding this, a self-curing resin can be easily obtained, and as a result, the manufacturing process of the self-curing resin can be simplified and shortened, and at the same time, the concentration of nitrogen-containing groups in the resin can be increased. The present inventors have discovered that since the amount does not increase beyond that level, the properties of the coating film are not adversely affected, leading to the completion of the present invention. That is, the present invention adds a primary monoamine to an ethylenically unsaturated compound having an amine imide group to form the following general formula: (In the formula, R1 represents an alkyl group, alkoxyalkyl group, alkenyl group, hydroxyalkyl group, or aryl group having 2 to 30 carbon atoms, R2, R3, R4
each represents an alkyl group or a hydroxyalkyl group having 1 to 8 carbon atoms. The present invention relates to a method for producing a self-curing resin, which is characterized by obtaining a Michael type adduct of ) and further adding the Michael type adduct to a polyepoxide to obtain an amino-modified polyepoxide containing an amine imide group. Examples of the ethylenically unsaturated compound having an amine imide group used in the present invention include 1, 1,
1-trimethylamine methacrylimide, 1,1
-dimethyl-1-ethylamine methacrylimide, 1,1-dimethyl-1-(2-hydroxypropyl)amine methacrylimide, and the like. Next, the first monoamine used in the present invention may have an alkyl group, an alkoxylalkyl group, an alkenyl group, a hydroxyalkyl group, or an aryl group having 2 to 30 carbon atoms, for example,
ethylamine, propylamine, butylamine,
1-methylbutylamine, hexylamine, 2-
Ethylhexylamine, 3-methoxypropylamine, 3-ethoxypropylamine, propoxypropylamine, butoxypropylamine, 2-
Ethylhexyloxypropylamine, decyloxypropylamine, dodecyloxypropylamine,
1-amino-2-propene, 1-amino-2-butene, 1-amino-2-pentene, oleylamine, 2-aminoethanol, 2-amino-1-propanol, 2,2-dimethyl-3-amino-propanol , phenylamine, benzylamine,
Examples include α-phenethylamine and β-phenethylamine. The primary monoamine undergoes Michael addition to the amine imide compound to form an imino group useful for subsequent reaction with the polyepoxide. The amine added to polyepoxide is
If desired, a conventionally known secondary amine may be used in combination with the Michael type adduct obtained by adding a primary monoamine to the above-mentioned amine imide compound. Such secondary amines may have one or more imino groups in one molecule, such as diethylamine, diisopropylamine, diethanolamine, methylethanolamine, diisopropanolamine, N,N'-dimethylethylenediamine, etc. Examples include secondary monoamines and polyamines produced by blocking all amino groups with ketimine. Examples of ketimine-blocked amino group-containing polyamines include monomethylaminopropylamine, diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetriamine, and other polyamines in which amino groups are combined with ketones such as acetone, methylethylketone, and methylisobutylketone. Examples include those converted to ketimine by the following reaction. Next, the polyepoxide used in the present invention is a compound having two or more 1,2 epoxy groups, such as polyglycidyl ether of polyphenol. Here, as the polyphenol, for example, bisphenol A

[2,2-bis(4-hydroxyphenyl)propane], 1,1-bis(4-hydroxyphenyl)ethane, 2-methyl-1,1-bis(4-hydroxyphenyl)propane, 2, 2
-Bis(4-hydroxy-3-t-butylphenyl)propane, bis(2-hydroxynaphthyl)
Examples include methane and 1,5-dihydroxynaphthalene. Also used are, for example, oxyalkyl adducts of polyphenols such as ethylene oxide adducts and propylene oxide adducts, and polyglycidyl ethers such as novolac type phenol resins and polyphenol resins similar to these. Next, as other polyepoxides,
Examples include epoxidized polyalkadiene resins, glycidyl acrylate copolymer resins, glycidyl methacrylate copolymer resins, polyglycidyl ethers of hydroxyl group-containing resins, and polyglycidyl esters of carboxyl group-containing resins. The polyepoxide may be further reacted to undergo chain extension to increase its molecular weight. In this case, chain extenders include active hydrogen-containing compounds that are reactive with epoxy groups, such as glycols, diamines, polyether polyols, dimer acids, hydantoins, bisphenol A, polyaminoamides, hydroxyl groups and amino groups such as amino acids, Examples include compounds containing imino groups, thiol groups, carboxyl groups, and the like. Next, a method for producing a self-curing resin, which is a feature of the present invention, will be explained. First, in the Michael type addition reaction method between a primary monoamine and an amine imide compound, the primary monoamine and an organic solvent are charged into a reaction vessel, and the mixture is stirred at an appropriate temperature, preferably 70°C or higher and 120°C or lower, under an inert gas flow. while adding the amine imide compound. The reason for keeping the temperature below 120°C is to prevent thermal decomposition of the amine imide compound during the reaction. The amine imide compound can be added by a method of adding the entire amount at once, a method of adding in several portions, a method of adding dropwise, or the like. In addition, the reaction between an amine imide compound and a primary monoamine is not possible in the presence of an acid because the acylhydrazinium base whose amine imide group is neutralized with an acid is more effective in increasing the reactivity with the primary monoamine. It is preferable to do so. The acid used for this purpose may be any conventionally known organic acid 2 useful for dispersing the self-curing resin obtained in the present invention in water, as long as it is an inorganic acid, and the amount thereof is determined per mole of the amine imide compound. It is 0.5 to 1 mole. Further, at this stage, heating, cooling, refluxing of volatile components, addition of an organic solvent, etc. can be performed. After the addition of the amine imide compound is completed, the reaction is continued at an appropriate temperature and time as necessary, and then dilution with an organic solvent, filtration, and other steps are performed to obtain a resinous solution of the Michael adduct. Here, the organic solvent is an organic solvent used in the Michael addition reaction between the primary monoamine and the amine imide compound and the subsequent addition reaction between the Michael adduct and polyepoxide; For example, alcohols such as methyl alcohol, ethyl alcohol, and isopropyl alcohol, and ether alcohols such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether are preferable, and the organic solvent used in the latter reaction is, for example, toluene, xylene, methyl isobutyl. Ketone, diisopropyl ketone, mineral spirits, ethylene glycol monoethyl ether acetate, diethylene glycol dimethyl ether, butyl acetate and the like are preferred. Next, in the method of addition reaction between the obtained Michael adduct and polyepoxide, part or all of the polyepoxide is charged into a reaction vessel and mixed under an inert gas flow to form a uniform liquid. If necessary in this step, heating, addition of a suitable organic solvent, preliminary reaction of the polyepoxide with other components such as bisphenol A, etc. can be carried out. Next, the Michael adduct is added to the homogeneous liquid while stirring the mixture at an appropriate temperature and under a stream of inert gas. Addition of the Michael type adduct can be carried out by adding the entire amount at once, adding it in several portions, dropping it, etc. Depending on the timing of the process, the type and amount of the Michael type adduct can be added. can be changed. At this stage, heating, cooling, refluxing of volatile components, addition of a portion of polyepoxide, an organic solvent, etc. can be performed. After the addition of the Michael type adduct is completed, the reaction is continued at an appropriate temperature and time as required, and then dilution with an organic solvent, distillation, filtration, etc. are performed to obtain a self-curing resin. The proportion of the Michael type adduct in the self-curing resin is preferably 5 to 35% by weight as a solid content, and if it is less than 5% by weight, it will not be curable at low temperature and the physical properties of the resulting coating will deteriorate. If the amount exceeds 35% by weight, problems will arise in the electrodeposition properties of the resulting aqueous dispersion and in the physical properties of the resulting coating film. The self-curing resin produced according to the present invention already contains an acylhydrazinium base, but if necessary, the remaining amine imide groups can also be neutralized with an acid to convert them into acylhydrazinium bases. conversion is possible and further dilution with water allows the formation of an aqueous dispersion.
Here, the acid is an organic acid or an inorganic acid, such as formic acid, acetic acid, lactic acid, phosphoric acid, and the like. In addition, the proportion of acylhydrazinium base in the self-curing resin obtained by neutralizing the amine imide group,
The structures and molecular weights of the various components must be mutually adjusted by taking into account dispersion stability, electrodepositivity, crosslinking curability, coating film performance, etc. when the self-curing resin is mixed with water. By immersing an anode and a cathode consisting of a conductive coating material in an aqueous dispersion of a self-curing resin, that is, a cationic electrodeposition paint bath, and applying a voltage between the two electrodes, the electrocoatable resin is coated. It is deposited as a film on the cathode surface. Such cationic electrodeposition coating techniques are well known in the art; however, the deposited coating can be applied to the surface of the coated material to such an extent that it is not washed off by water washing after removal from the cationic electrodeposition paint bath. It must have staying power. The self-curing resin produced in the present invention basically consists of an amino-modified polyepoxide containing an amine imide group and an acid as a neutralizing agent, and other components include those used in ordinary cationic electrodeposition coatings. plasticizer; surfactant; such as titanium dioxide, carbon black, talc, kaolin,
Pigments such as color pigments such as silica, lead silicate, basic lead chromate, and zinc phosphate, extender pigments, and antirust pigments;
For example, hydrophilic/semi-hydrophilic organic solvents such as isopropyl alcohol, butyl alcohol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diacetone alcohol;
For example, curing catalysts such as dibutyltin dilaurate, dibutyltin dioxide, diphenyltin oxide; water, etc. are added as appropriate, and are commonly used in the manufacture of paints, such as resolvers, homomixers, sand grind mills, attritors, and roll mills. The mixture is uniformly mixed and dispersed using a mixer or a dispersing machine such as the above, to form a cationic electrodeposition paint bath which is an aqueous dispersion having a resin solid content of 10 to 25% by weight.

【Example】

Next, the present invention will be explained in more detail by giving Examples and Comparative Examples. In the examples, parts are parts by weight, and % is % by weight. ◇Example 1 In a reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, a dropping funnel, and a nitrogen gas inlet, 300 parts of 2-ethylhexylamine was charged under a nitrogen gas stream, and the temperature was gradually raised to 90°C. Next, the following mixture was added dropwise over about 1 hour while maintaining the temperature at 90°C. 1,1,1-Trimetalamine methacrylimide 329 parts Acetic acid 111 parts Ethylene glycol monobutyl ether 329 parts After the dropwise addition, the reaction was continued at 90°C for 2 hours to form a pale yellow transparent Michael adduct with a solid content of 58.8%. Obtained. In addition, 950 parts of polyepoxide (trade name: Epicote 1004, manufactured by Yuka Ciel Epoxy Co., Ltd.) and 282 parts of methyl isobutyl ketone were charged into another reaction vessel similar to the above under a nitrogen gas stream, and the temperature was gradually raised to 110°C. and dissolved. Then the Michael adduct
369 parts and 38 parts of ketimine (obtained from 1 mol of monomethylaminopropylamine and 1 mol of methyl isobutyl ketone, a methyl isobutyl ketone solution with a solid content of 90.0%) were added, and the mixture was heated under a nitrogen gas stream.
The reaction was carried out at 90° C. for 2 hours to obtain a self-curing resin having a number average molecular weight of 2370 and a solid content of 73.3%. 136 parts of the obtained self-curing resin was diluted with deionized water to obtain an aqueous dispersion having a resin solid content of 10%. The obtained aqueous fraction was transferred to a polyvinyl chloride electrodeposition tank having an internal volume of about 1 liter, the temperature was adjusted to 25°C, and a zinc phosphate-treated steel plate was connected to the cathode as the object to be coated. Next, a carbon plate was inserted into the aqueous dispersion as an anode, and a cationic electrodeposition coating was performed by applying a direct current of 80 volts for 2 minutes while stirring the aqueous dispersion. After washing with water, bake at 150℃ for 30 minutes to obtain a dry film thickness.
A cured coating film of 19μ was obtained. The test results of the obtained cured coating films are shown in Table 1 below. ◇Example 2 In a reaction vessel similar to Example 1, under a nitrogen gas stream,
Prepare 150 parts of 2-amino-1-propanol,
The temperature was gradually raised to 70°C. Next, while maintaining the temperature at 70℃, add about 1 cup of the following mixture.
It took some time to drip. 1,1-Dimethyl-1-(2-hydroxypropyl)amine methacrylimide 372 parts Acetic acid 120 parts Ethylene glycol monobutyl ether 372 parts After dropping, the reaction was continued at 70°C for 1 hour to give a light yellow transparent solid content of 51.5%. Michael-shaped adducts were obtained. In addition, 950 parts of polyepoxide (trade name: Epiyute 1004 manufactured by Yuka Ciel Epoxy Co., Ltd.) and 244 parts of methyl isobutyl ketone were charged into a reaction vessel similar to that in Example 1 under a nitrogen gas stream, and the temperature was gradually raised to 110°C. and dissolved. Then the Michael adduct
506 parts were added, and the reaction was carried out at 90° C. for 2 hours under a nitrogen gas stream to obtain a self-curing resin with a number average molecular weight of 2380 and a solid content of 71.2%. 140 parts of the obtained self-curing resin was diluted with deionized water to obtain an aqueous dispersion having a resin solid content of 10%. The obtained aqueous dispersion was treated in the same manner as in Example 1,
Cationic electrodeposition painting was performed. After washing with water, bake at 150℃ for 30 minutes, dry film thickness: 19μ
A cured coating film was obtained. The test results of the obtained cured coating films are shown in Table 1 below. ◇Example 3 In a reaction vessel similar to Example 1, 534 parts of oleylamine (trade name: Amine OB, manufactured by NOF Corporation) was charged under a nitrogen gas flow, and the temperature was gradually raised to 80°C. Next, the following mixture was added dropwise over a period of about 1 hour while maintaining the temperature at 80°C. 1,1-dimethyl-1-(2-hydroxypropyl)amine methacrylimide 372 parts Acetic acid 96 parts Ethylene glycol monobutyl ether 372 parts After dropping, the reaction was continued at 80°C for 2 hours to give a yellowish brown transparent solid content of 65.9%. Michael-shaped adducts were obtained. In addition, polyepoxide (trade name: Epicoat 1004
950 parts (manufactured by Yuka Ciel Epoxy Co., Ltd.) and 244 parts of methyl isobutyl ketone were charged, and the temperature was gradually raised to 110°C to dissolve them. Then, the Michael type adduct
687 parts were added and reacted for 2 hours at 90°C under a nitrogen gas stream to obtain a self-curing resin with a number average molecular weight of 2800 and a solid content of 74.6%. 134 parts of the obtained self-curing resin was diluted with deionized water to obtain an aqueous dispersion having a resin solid content of 10%. The obtained aqueous dispersion was treated in the same manner as in Example 1,
Cationic electrodeposition coating was performed. After washing with water, bake at 150℃ for 30 minutes to obtain a dry film thickness.
A cured coating film of 20μ was obtained. The test results of the obtained cured coating films are shown in Table 1 below. ◇Comparative Example 1 In a reaction vessel similar to Example 1, 950 parts of polyepoxide (trade name Epicoat 1004 manufactured by Yuka Ciel Epoxy Co., Ltd.) and 336 parts of methyl isobutyl ketone were charged under a nitrogen gas flow, and the mixture was gradually raised to 110°C. Warm and dissolve. Next, 118 parts of propylamine was charged, and the mixture was reacted at 50° C. for 5 hours under a nitrogen gas stream. Next, the temperature was raised to 120°C and nitrogen gas was blown vigorously to remove unreacted amine, yielding a pale yellow transparent polyamine resin with a solid content of 76.6%. The following mixture was added dropwise to the resulting polyamine resin over a period of about 1 hour while maintaining the temperature at 70°C. 1,1-dimethyl-1-(2-hydroxypropyl)amine acrylamide 138 parts Ethylene glycol monobutyl ether 138 parts After dropping, the reaction was continued at 70°C for 2 hours to achieve a self-curing product with a number average molecular weight of 2200 and a solid content of 72.0%. A synthetic resin was obtained. 2 parts of acetic acid per 138 parts of the self-curing resin obtained.
After adding 1.0 parts and thoroughly mixing, the mixture was diluted with deionized water to obtain an aqueous dispersion having a resin solids content of 10%. The obtained aqueous dispersion was treated in the same manner as in Example 1,
Cationic electrodeposition coating was performed. 30 at 150℃ after washing with water
After baking for a minute, a cured coating film with a dry film thickness of 18 μm was obtained. The test results of the obtained cured coating films are shown in Table 1 below. ◇Comparative Example 2 In a reaction vessel similar to Example 1, 950 parts of polyepoxide (trade name Epicoat 1004 manufactured by Yuka Ciel Epoxy Co., Ltd.) and 355 parts of methyl isobutyl ketone were charged under a nitrogen gas flow, and the mixture was gradually heated to 110°C. It was heated and dissolved. Next, ketimine (obtained from 1 mol of monomethylaminopropylamine and 1 mol of methyl isobutyl ketone, solid content 90.0%)
Add 188 parts of methyl isobutyl ketone solution),
The reaction was carried out at 90°C for 2 hours under a nitrogen gas stream to obtain a pale yellow transparent polyamine resin with a solid content of 76.2%. While maintaining the obtained polyamine resin at 90°C, 27 parts of deionized water and 20 parts of ethylene glycol monobutyl ether were gradually added, and then the following mixture was added dropwise over about 1 hour. 1,1,1-trimethylamine acrylimide
128 parts ethylene glycol monobutyl ether 128 parts After the dropwise addition, the reaction was continued at 90°C for 2 hours to obtain a self-curing resin with a number average molecular weight of 2330 and a solid content of 65.0%. 2 parts of acetic acid per 154 parts of the self-curing resin obtained.
After adding 1.0 parts and thoroughly mixing, the mixture was diluted with deionized water to obtain an aqueous dispersion having a resin solids content of 10%. The obtained aqueous dispersion was treated in the same manner as in Example 1,
Cationic electrodeposition coating was performed. 30 at 150℃ after washing with water
After baking for a minute, a cured coating film with a dry film thickness of 19 μm was obtained. The test results of the obtained cured coating films are shown in Table 1 below. Table 1 below also shows the amine values, proportions in the self-curing resin, and manufacturing times of the electrodeposition coating films obtained in Examples 1 to 3 and Comparative Examples 1 to 2.

【table】

【table】

【Effect of the invention】

In the manufacturing process of Examples 1 to 3, the average proportion of Michael adducts in the self-curing resin was
Because it is as small as 29.2%, it is possible to manufacture and store several batches of Michael-shaped adducts in advance in a fixed-volume manufacturing device, and use a portion each time self-curing resin is manufactured. be. On the other hand, in the manufacturing process of Comparative Examples 1 and 2, the ratio of polyamine resin in the self-curing resin in the first step is as high as 81.8% on average, so the polyamine resin is prepared in advance in several batches using a manufacturing device with a fixed volume. It is not possible to produce the polyamine resin in batches, and it is necessary to produce the polyamine resin in batches. Therefore, when manufacturing the self-curing resin in Examples 1 to 3, the manufacturing time was only 3 hours, making it possible to simplify and shorten the manufacturing process, whereas in Comparative Examples 1 to 2
When manufacturing self-curing resin, the manufacturing time is 6
It takes a long time, ~9 hours. In addition, the resin produced according to the present invention can always keep the concentration of nitrogen-containing groups in the resin to the minimum necessary, so there is no drawback that the concentration of nitrogen-containing groups increases and deteriorates coating performance. There is no. In addition, electrodeposition was carried out using the cationic electrodeposition paint bath obtained according to the present invention, using the conductive object as a cathode, in the same manner as ordinary cationic electrodeposition, and after washing with water, it was heated at 130 to 160°C. A cured coating is obtained by baking for 20-40 minutes. The cured coating film thus obtained is excellent in pencil hardness, adhesion, impact resistance, flexibility, acetone rubbing resistance, water resistance, corrosion resistance, acid resistance, etc. However, in the known method of obtaining the resin by adding an amine imide compound to the polyamine resin, the cured coating film tends to be inferior in water resistance, corrosion resistance, and acid resistance due to the high amine value of the electrodeposited coating film.

Claims (1)

[Claims] 1. A first monoamine is added to an ethylenically unsaturated compound having an amine imide group to obtain the following general formula: (In the formula, R ₁ represents an alkyl group, alkoxyalkyl group, alkenyl group, hydroxyalkyl group, or aryl group having 2 to 30 carbon atoms, and R ₂ , R ₃ , R ₄
each represents an alkyl group or a hydroxyalkyl group having 1 to 8 carbon atoms. 1. A process for producing a self-curing resin, which comprises obtaining a Michael-type adduct of ) and further adding the Michael-type adduct to a polyepoxide to obtain an amino-modified polyepoxide containing an amine imide group. 2. The ethylenically unsaturated compound having an amine imide group is one in which part or all of the amine imide is neutralized with an organic acid or an inorganic acid. A method for producing a self-curing resin according to claim 1.