JPH0680153B2 - Anionic water-based coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an anionic water-based coating composition that can be electrodeposited, diped, or spray coated.

(Prior art and its problems) Electrodeposition, dips, and spray-coatable anion-based water-based paints are used for various articles, especially for automobile primer coating. In order to further improve the corrosion resistance and curability of this anionic water-based coating composition, a phenol resin may be blended. However, if phenolic hydroxyl groups remain in this phenol resin, the water resistance of the coating film will be insufficient. Therefore, it is conceivable to etherify the phenolic hydroxyl group to ensure water resistance. For example, in Shinichi Murade, "Phenolic Resin," published by Nikkan Kogyo Shimbun, Inc., 1st edition of 1965, phenol and formalin were reacted at low temperature in the presence of an alkali catalyst to produce dimethylolphenol or trimethylolphenol Na. A method of obtaining a salt and adding a chloride such as an alkyl halide, an aralkyl halide, or an epihalohydrin to the salt to carry out a desalting reaction to etherify the salt is disclosed. In this way, phenol is first methylated and then etherified, because if the hydroxyl group of phenol is etherified first, the ortho or para position of the benzene nucleus will not be activated by the hydroxyl group and it will be difficult to react with formaldehyde. Is. However, as described above, the methylol group of the methylolphenol ether which has been previously methylated and then etherified is also very stable, and even if it is heated as it is, depending on the size of the alkyl ether or aralkyl ether, it is hard to cure. However, the hardness of the coating film is insufficient.

(Details of the Invention) The present invention provides an anionic aqueous coating composition containing a phenol ether compound which does not have the above-mentioned drawbacks. That is, the present invention is the formula (A) obtained by reacting an initial reaction product of a resol type phenolic resin with a monoepoxy compound in the presence of a basic catalyst: [In the formula, R ¹ is a residue obtained by removing the phenolic hydroxyl group from the initial reaction product of the resol-type phenol resin, R ² , R ³ , R ⁴ ,
R ⁵ represents a residue obtained by removing an epoxy group from a monoepoxy compound. ] The beta-hydroxyphenol ether compound which has, and (B) anionic aqueous resin composition containing anionic aqueous resin are provided.

The β-hydroxyphenol ether compound (A) used in the present invention is obtained by reacting an initial reaction product of a resol-type phenol resin with a monoepoxy compound in the presence of a basic catalyst. The resulting compound (A) is a self-curing compound having a methylol group and a hydroxyl group at the β-position of the ether bond. The reason why the curability is improved is not particularly limited, but since there is a hydroxyl group at the β-position, the phenol ether is partially hydrolyzed, and the generated phenolic hydroxyl group activates the methylol group and It is considered that it was cured by a condensation reaction.

The initial reaction product of a resol type phenol resin is a mixture of methylolphenols obtained by reacting phenols and formaldehyde in the presence of an alkali catalyst. Phenols include 3,5-xylenol, m-
Cresol, 2,3,5-trimethylphenol, 3,4-xylenol, 2,5-xylenol, p-cresol, saligenin, o-cresol, 2,6-xylenol, pt
-Butylphenol and the like. As the initial reaction product of the resol-type phenol resin, those having a number average molecular weight of less than 300 are preferable from the viewpoint of curability, and examples thereof include Tamanol 721 and Tamanol 722 commercially available from Arakawa Chemical Co., Ltd.

The monoepoxy compound is a compound having one epoxy group in the molecule. The use of a compound having two or more epoxy groups in the molecule, such as a diepoxy compound or a triepoxy compound, is conceivable, but it cannot be actually used by gelling. Even these diepoxy compounds or triepoxy compounds can be modified with organic acids, secondary amines or the like to give monoepoxy compounds, or can be used as a mixture with monoepoxy compounds as long as they do not adversely affect the reaction. The monoepoxy compound is preferably a monoglycidyl compound.

Examples of monoglycidyl compounds include glycidyl ethers such as phenyl glycidyl ether, butyl glycidyl ether, allyl glycidyl ether, 2-ethylhexyl glycidyl ether, pt-phenyl glycidyl ether, glycidyl ether of higher aliphatic alcohol, and lauryl alcohol. Glycidyl ether of ethylene oxide adduct, glycidyl ether of ethylene oxide adduct of phenol, dibromophenyl glycidyl ether, pentyl glycidyl ether and the like; glycidyl esters such as glycidyl benzoate,
Linoleic acid, glycidyl ester of oleic acid mixture, glycidyl ester of tertiary saturated carboxylic acid, etc .; glycidyl imides, such as glycidyl phthalimide; glycidol and one of diglycidyl compound or two of triglycidyl compound modified with organic acid, etc. Examples of the compound that becomes glycidyl include monoacetate of 1,6-hexanediol diglycidyl ether.

Examples of monoepoxy compounds other than the above include styrene oxide, cyclohexene oxide, ethylene oxide, propylene oxide, butadiene monooxide, isobutylene oxide, methylstyrene oxide, vinylcyclohexene monoxide, and the like.

The amount of the initial reaction product of the resol type phenolic resin and the monoepoxy compound is 1.0 / 0.5 to 1.0 / 2.0, preferably 1.0 / 0.5, expressed as the equivalent ratio of phenolic hydroxyl group / epoxy group.
It is 0.7 to 1.0 / 1.5. If the residual amount of phenolic hydroxyl groups is large, the water resistance of the coating film tends to deteriorate, so a monoepoxy compound is often used to reduce this. Therefore, if the above ratio is less than 1.0 / 0.5, the water resistance of the coating film will decrease. When it is more than 1.0 / 2.0, the amount of the monoepoxy compound remaining is large and it reacts with the methylol group, so that the curability due to the methylol group deteriorates, which is not preferable.

The reaction is preferably carried out in a solvent to accelerate the reaction. Since the initial reaction product of the resol type phenol resin contains unreacted phenol, formaldehyde and water, a solvent having a hydrophilic group is suitable. Suitable solvents are alcoholic solvents such as methanol, ethanol, n-
Propanol, isopropanol, n-butanol, methoxybutanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, 3-pentanol, tert-amyl alcohol, n-hexanol,
Cyclohexanol, 2-methylcyclohexanol,
Benzyl alcohol, furfuryl alcohol, tetrahydrofurfuryl alcohol, abiethyl alcohol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, ethylene glycol isoamyl ether, ethylene glycol monophenyl ether ,
Ethylene glycol benzyl ether, ethylene glycol monoacetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol acetate, triethylene glycol, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, polyethylene glycol, polypropylene glycol , Propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether and the like. Of course, a non-alcohol solvent such as ketones and esters may be mixed with the above alcohol solvent. The reaction temperature is 60 to 130 ° C, preferably 70 to 125 ° C. 130
If the temperature exceeds ℃, condensation of methylol groups is rapid, which is not preferable. If the temperature is lower than 60 ° C, the reaction rate is insufficient.

The reaction is carried out with a basic catalyst such as sodium hydroxide, potassium hydroxide, amines (eg, trimethylamine, triethylamine, tri-n-butylamine, triamylamine, dimethylbenzylamine, diethylbenzylamine, dimethylaniline, diethylaniline, NNdin). -Butylaniline, NN diamylaniline, NN dit-amylaniline, triethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, n-butyldiethanolamine, di-n-butylethanolamine, triisopropanolamine, α-picoline, β-picoline, γ-picoline, 2,4-lutidine, 2,6
-Lutidine, ethylmorpholine, diethylamine, diisopropylamine, diisobutylamine, diamylamine, N-methylethanolamine, N-ethylethanolamine, diethanolamine, pyridine, lauryltrimethylammonium chloride, etc.). Preferred are amines.

As the anionic aqueous resin which is the component (B) of the present invention, various conventionally known resins can be used. Typical examples include maleated oil, vinyl-modified maleated oil, cyclopentadiene-modified maleated oil, carboxyl group-containing epoxy resin, maleated polybutadiene resin, alkyd resin, and carboxyl group-containing acrylic resin (Japanese Patent Publication No. 49-4058). , JP-B-47-21691, JP-B-48-9096, JP-A-49-41425, JP-A-49-24231) and the like. The anionic aqueous resin (B) is 3 parts by weight based on 10 parts by weight of the β-hydroxyphenol ether compound (A).
To 1000 parts by weight, preferably 10 to 200 parts by weight.
If it is less than 3 parts by weight, the stability of the coating is not sufficient, and if it exceeds 1000 parts by weight, the curability effect of the β-hydroxyphenol ether compound deteriorates.

The anionic aqueous resin is neutralized with a base to be used as a water-dispersed type or water-soluble type. Bases that can be used are ammonia, various amines (monoethylamine, diethylamine, triethylamine, n-butylamine, di-n-butylamine, N-methylethanolamine, N-ethylethanolamine, dimethylethanolamine, diethanolamine, morpholine), potassium hydroxide, Examples include sodium hydroxide and the like.

The water-based coating composition is a dispersion solution mainly composed of water, but other solvents such as hydrocarbons, alcohols, esters, ethers and ketones may be added in addition to water. The amount of these solvents is not critical, but is about 0.1% based on resin solids.
-40% by weight, preferably about 0.5-25% by weight.

If desired, the anionic aqueous coating composition of the present invention may contain a known curing agent such as a melamine resin, a urea resin, a blocked isocyanate resin or a transesterification curing agent. The β-hydroxyphenol ether compound (A) of the present invention itself has curability, but is blended when a higher degree of curing is required. The compounding amount of the curing agent is β
It is 1 to 200 parts by weight with respect to 10 parts by weight of the hydroxyphenol ether compound (A).

The anionic aqueous coating composition of the present invention may contain an organic acid salt of cobalt, manganese, iron, zinc, lead, calcium or zirconium, manganese dioxide or a mixture thereof as an oxidative polymerization curing catalyst.

Β-hydroxyphenol ether compound (A) of the present invention
It has curability itself, but is compounded when a higher degree of curing is required. The compounding amount of the curing catalyst is, in terms of metal, about 0.005 to 2.0% by weight, preferably about 0.05 to 1.0% by weight, based on the resin solid content.

The anionic aqueous coating composition of the present invention further comprises other pigments, for example, aluminum silicate, extendable barium sulfate, kaolin, extender pigments such as precipitated calcium carbonate, titanium oxide,
Coloring pigments such as carbon black, zinc white, red iron oxide, and manganese dioxide, and anticorrosion pigments such as strontium chromate, lead chromate, basic lead silicate, and aluminum phosphomolybdate may be added. These pigments are not limiting.

The anionic aqueous coating composition of the present invention may further contain other additives. Specific examples of the additives include surfactants, organic solvents such as alcohols, ketones and ethers, flow control agents, ultraviolet absorbers and surfactants.

When the anionic aqueous coating composition of the present invention is used as an electrodeposition coating composition, the aqueous coating composition of the present invention is subjected to the same electrodeposition conditions as those for general electrodeposition. The applied voltage may vary, for example from a low voltage of 1 volt to a high voltage of several thousand volts, but is typically in the range of 50-500 volts. Current densities are typically 1.0 to 15 amps per square foot, but decrease during electrodeposition. This indicates that an insulating coating is formed.

In electrodeposition, the coating composition comprises various electrically conductive supports,
In particular, it can be applied not only to metals such as steel, aluminum, copper and magnesium but also to metallized plastics and conductive carbon coatings.

The aqueous coating composition of the present invention can be used as a general aqueous coating by a general coating technique such as dipping or spraying.

(Effect of the Invention) The anionic water-based coating composition of the present invention can provide a cured coating having high corrosion resistance and high water resistance. Since the β-hydroxyphenol ether compound has a methylol group and a hydroxyl group at the β-position of the ether bond, it is self-crosslinkable by itself and acts as a curing agent for an anionic aqueous coating composition. Of course, it may be combined with other curing agents.

(Example) The present invention will be described in more detail based on an example.

Synthesis of β-hydroxyphenol ether compound A 30 g of a reaction initial condensation product of resol type phenolic resin (Tamanol 722 manufactured by Arakawa Chemical Co., Ltd.) was charged into a reaction vessel, and n
-Butanol and methoxybutanol were added by 10 g each, and further 44 g of a monoepoxy resin (commercially available as Neotote P from Toto Kasei Co., Ltd.) as an addition reaction agent was added. While uniformly stirring this, the temperature was raised to 100 ° C., and 0.4 g of dimethylbenzylamine as a catalyst was weighed and added.
After paying attention to the heat generation, the temperature was kept at 100 ° C and the epoxy group content of the reaction product was measured after 3 hours under a sufficient stirring state. It was 5% or less of the charged amount, so it was cooled. . As a result of analysis of the obtained compound, the phenolic hydroxyl group disappeared.

Example 1 <Synthesis of Maleated Polybutadiene Resin> Nisseki Polybutadiene B-1500 * ¹ ) 1000 g Antigen 6C * ² ) 10 g Maleic anhydride 250 g Deionized water 20 g Diethylamine 0.5 g Propylene glycol 100 g Ethyl cellosolve 340 g * ¹ ) Nippon Petrochemical Mn 1500, vinyl 65%, trans 14%, cis 16% * ² ) Sumitomo Chemical Co., Ltd .; N-methyl-N '-(1,3-dimethylbutyl), p-phenylenediamine cooling tube With 2l Kolben, Nisseki Polybutadiene B-1500 100
Charge 0 g and add 10 g of Antigen 6C and 250 g of maleic anhydride. While stirring, while maintaining the internal temperature at 190 to 200 ° C, the addition polymerization reaction of maleic acid to polybutadiene is carried out. About 5 hours after the temperature was raised, it was confirmed that the reaction was completed by the dimethylaniline color reaction. Then, the internal temperature is cooled to 100 ° C., and a mixture of 20 g of deionized water and 0.5 g of diethylamine is added dropwise in about 30 minutes. Continue stirring for about 1 hour after the dropping.
It was confirmed that the acid value was 140. After that, 100 g of propylene glycol was added and reacted at 110 ° C for 3 hours until the total acid value was 1
It was confirmed to be 25. After that, 340g of ethyl cellosolve
Was added and stirred at 80 ° C. for about 1 hour, and then the synthesis was completed (solid content 80%).

<Preparation of pigment paste> 125 g of the above maleated polybutadiene resin was sampled, 13 g of triethylamine was added thereto, and then 250 g of deionized water was added.
Was gradually added and dissolved uniformly to obtain a varnish having a nonvolatile content of about 26%. Next, 150 g of titanium oxide, 50 g of lead silicate, 25 g of strontium chromate and 25 g of carbon black were added, and the mixture was stirred with a disper for about 1 hour. Glass beads were added to this mixture and dispersed with SG to a particle size of 20 μm or less. After separating the glass beads by filtration, 1112 g of deionized water was added to complete the production (solid content 20%).

<Preparation of Paint> An anionic electrodeposition paint was prepared using the following components. Component Parts by weight the maleinized polybutadiene resin 63.0 beta hydroxy phenol ether compound A 67.0 Triethylamine 7.0 Newcol 710F ¹ * ³⁾ 1.0 cobalt naphthenate 1.5 Deionized water 360.5 The pigment paste 100.0 * ³⁾ manufactured by Nippon Emulsifier Co., nonionic -Based surfactant Maleated polybutadiene resin, β-hydroxyphenol ether compound A, triethylamine, Newcol
After adding 710F and cobalt naphthenate and stirring, the mixture was emulsified and dispersed with deionized water to obtain a uniform emulsion. A pigment paste was added to this emulsion to obtain an anionic electrocoating paint.

SPCC dull steel plates (manufactured by Nippon Teltopanel Co., Ltd.) degreased with this electrodeposition coating were electrodeposited to a film thickness of 25 μm. The obtained panel was cured at 160 ° C. for 20 minutes, and the obtained coating film was subjected to a salt spray test and a pencil hardness test. Table of results
Shown in 1.

Comparative Example 1 An electrodeposition coating composition was prepared in the same manner as in Example 1 using the following components. Component Parts by weight maleinized polybutadiene resin 125.0 triethylamine 14.0 Newcol 710F ¹ 1.0 pigment paste 100.0 Similar evaluation cobalt naphthenate 1.5 Deionized water 358.5 Example 1 Example 1 was carried out. The results are shown in Table-1.

Example 2 A coating material was prepared in the same manner as in Example 1 using the following components. Maleinized polybutadiene resin 75.0 Butylated of Component Parts by weight Example 1 Mechiruramin resin * ⁴⁾ 40.0 beta hydroxy phenol ether compound A 27.0 Triethylamine 8.0 Newcol 710F 1.0 cobalt naphthenate 1.5 Deionized water 347.5 Example 1 of pigment paste 100.0 * ⁴ ) Uiban 22R, manufactured by Mitsui Toatsu Chemicals, Inc. The same evaluation was performed using the obtained anion type electrodeposition coating composition. The results are shown in Table-1.

Comparative Example 2 An electrodeposition coating composition was prepared in the same manner as in Example 2 using the following components. Ingredients Parts by weight Maleated polybutadiene resin of Example 1 94.0 Butylated methylamine resin * ⁴ ) 50.0 Triethylamine 10.0 Newcol 710F 1.0 Cobalt naphthenate 1.5 Deionized water 343.5 Pigment paste of Example 1 100.0 Evaluation is performed in the same manner as Example 2. It was The results are shown in Table-1.

Claims (8)

[Claims] 1. A formula obtained by reacting (A) an initial reaction product of a resol-type phenol resin with a monoepoxy compound in the presence of a basic catalyst: [In the formula, R ¹ is a residue obtained by removing the phenolic hydroxyl group from the initial reaction product of the resol-type phenol resin, R ² , R ³ , R ⁴ ,
R ⁵ represents a residue obtained by removing an epoxy group from a monoepoxy compound. ] The anion type aqueous coating composition containing (beta) hydroxyphenol ether compound which has, and (B) anion type aqueous resin. 2. The composition according to claim 1, wherein the initial reaction product of the resol type phenolic resin has a number average molecular weight of less than 300. 3. The composition according to claim 1, wherein the epoxy compound is a monoglycidyl compound. 4. The first to third wherein the basic catalyst is an amine compound.
The composition according to any one of items. 5. The composition according to any one of claims 1 to 4, wherein the anionic aqueous resin is a maleated polybutadiene resin or a maleated oil. 6. The composition according to claim 1, wherein the anionic aqueous coating composition contains a melamine resin or a urea resin as a curing agent. 7. An anionic water-based coating composition is used as a curing catalyst, wherein an organic acid salt of cobalt, manganese, iron, zinc, lead, calcium or zirconium, manganese dioxide, or a mixture thereof is converted into a metal based on a resin solid content. Then 0.
7. The composition according to any one of items 1 to 6, which contains 005 to 2.0% by weight. 8. The composition according to claim 1, wherein the anionic water-based coating composition is for electrodeposition.