JPH0132266B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a fluorine-based matte electrodeposition coating composition that can form a matte coating film by electrodeposition. (Prior Art) Conventionally, as a matte electrodeposition paint, one made by mixing and dispersing organic or inorganic fine powder into an electrodeposition paint is known. For example, when using an electrodeposition paint in which fine silica powder is dispersed as a matting agent, the fine silica powder tends to settle in the paint, resulting in a significant difference in the degree of matting between the top and bottom surfaces of the object being coated. Moreover, there was a problem that the paint itself separated over time and became unstable. On the other hand, if a solvent-insoluble particulate polymerization reaction product is added to the paint as a matting agent, there is an advantage that the conventional mechanical refining process such as crushing or dispersion of the matting agent is not necessary. As in the case of adding a matting agent, there is an unavoidable tendency for particulate polymerization reaction products to settle in paints, and for this reason, there still remains the problem that a uniform matte coating film cannot be obtained. The present inventors have proposed a resin composition containing (a) an α,β-ethylenically unsaturated polycarboxylic acid resin and (b) an alkoxylated methylolmelamine as coating film forming components to solve the above problem. It has previously been proposed to use a composition containing a product obtained by heating an aqueous emulsion containing components (a) and (b) as a matte electrodeposition coating. (Tokuko Showa 60-
(Refer to Publication No. 19942) When this resin composition is electrodeposited, the drawbacks of conventional matte paints can be improved, but satisfactory results have not yet been obtained, especially in properties such as weather resistance, alkali resistance, and boiling water resistance. Improvement was desired. (Problems to be Solved by the Invention) The purpose of the present invention is to form a matte electrodeposition coating film having physical properties such as excellent boiling water resistance that cannot be obtained with the conventional matte coatings. An object of the present invention is to provide a fluorine-based matte electrodeposition coating composition. (Means for Solving the Problems) To summarize the present invention, the resin composition includes (a) a fluorine-containing polymer having a carboxyl group and a hydroxyl group and having an acid value of 5 to 50 and a hydroxyl value of 30 to 150; and (b) alkoxylated methylolmelamine as a coating film forming component,
This fluorine-based matte electrodeposition coating composition is characterized in that it is a composition containing a product obtained by heating an aqueous emulsion containing the components (a) and (b). According to research by the present inventors, it has a carboxyl group and a hydroxyl group and has an acid value of 5 to 50, preferably 7 to 50.
40. When a fluorine-containing polymer with a hydroxyl value of 30 to 150 and alkoxylated methylol melamine are mixed and heated, the reaction product of the fluorine-containing polymer and alkoxylated methylol melamine does not remain in a mere mixed state. It was confirmed that some parts were generated. The reason why the electrodeposition coating composition of the present invention forms a matte coating film has not yet been investigated, but as mentioned above, the high molecular weight reaction between the fluorine-containing polymer and the alkoxylated methylol melamine in the resin composition. It is presumed that the presence of the products is involved in the formation of the matte coating. Examples of the fluorine-containing polymer containing carboxyl groups and hydroxyl groups used in the present invention include those obtained by reacting a hydroxyl group-containing fluorine-containing polymer with a dibasic acid anhydride to introduce carboxyl groups. (Refer to JP-A-58-136605.) Unlike ordinary polycarboxylic acid resins, this fluorine-containing polymer has the characteristics of being easily dispersible and stable in water in the low acid value region, and the present invention So the acid value is 5~
A fluorine-containing polymer having a molecular weight of 50, preferably 7 to 40, is used as a coating film-forming component. If the acid value is less than 5, it cannot be sufficiently dispersed in water, and even if it can be dispersed, it will be unstable. On the other hand, if the acid value exceeds 50, the performance of the coating will deteriorate as described above. This is also because the appearance of the electrodeposition coating also tends to deteriorate, which is undesirable. In addition, the fluorine-containing polymer has a hydroxyl value of 30 to 150.
Use a range of . The reason for this is that if the hydroxyl value is less than 30, sufficient crosslinking reaction with the aminoplast will not occur, resulting in poor coating film performance, while if it exceeds 150, the coating will be undesirably hardened. On the other hand, the alkoxylated methylol melamine may be one in which at least a portion of the methylol group is alkoxylated with a lower alcohol. As the lower alcohol, one or more of methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, etc. is used. In the fluorine-based matte electrodeposition coating composition of the present invention, the composition ratio of the fluorine-containing polymer and alkoxylated methylolmelamine is 5 to 5.
95 parts by weight, alkoxylated methylolmelamine 95
It can be used in a range of 5 parts by weight. The matte electrodeposition coating composition of the present invention can be produced, for example, by the following method. In a reaction vessel equipped with a stirring device, a thermometer, and a reflux condenser, (a) a fluorine-containing polymer and (b) an alkoxylated methylolmelamine are mixed in the presence of an organic solvent. During or after this mixing, a hydrophilic base is added while stirring, and water is further added to form an emulsion. Next, the temperature is raised to 40°C to reflux temperature, and stirring is continued to complete the reaction. The lower the heating temperature, the longer the reaction time and/or the room temperature standing time. Examples of organic solvents include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, isobutanol,
Alcohols such as sec-butanol, t-butanol, pentanol, etc., cellosolves such as methyl cellosolve, ethyl cellosolve, isopropyl cellosolve, butyl cellosolve, sec-butyl cellosolve, etc. are used. Hydrophilic bases include ammonia, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, monoisopropylamine, diisopropylamine, monobutylamine, dibutylamine, alkylamines such as tributylamine, monoethanolamine, diethanolamine, etc. , triethanolamine, mono(2-hydroxypropyl)amine, di(2-hydroxypropyl)amine, tri(2-hydroxypropyl)amine, dimethylaminoethanol, alkanolamines such as diethylaminoethanol, ethylenediamine, propyleneamine, diethylenetriamine , alkylene imines such as alkylene polyamines such as triethylenetetramine, piperazine, morpholine, pyrazine, pyridine, and metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide. The hydrophilic base may be added in a molar ratio of 0.1 to 0.8 with respect to the carboxyl group of the fluorine-containing polymer. In the matte electrodeposition coating composition of the present invention, when an acid is added, the reaction time and coating baking time are shortened, and favorable results can be obtained. It is presumed that this is because the acid promotes the reaction of the fluorine-containing polymer and the alkoxylated methylol melamine to produce a reaction product, and also acts as a crosslinking catalyst during baking of the coating film. Acids that can be blended into the resin composition in the present invention include organic acids and/or inorganic acids. As an organic acid,
Examples include formic acid, acetic acid, oxalic acid, and sulfonic acid compounds, while examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. In the present invention, at least one type of organic acid or inorganic acid, or a mixture of an organic acid and an inorganic acid can be used. In the present invention, it is preferable to use a sulfonic acid compound because it exhibits particularly excellent effects. Sulfonic acid compounds include aliphatic sulfonic acids and aromatic sulfonic acids. Examples of aliphatic sulfonic acids include alkanesulfonic acids such as methanesulfonic acid and ethanesulfonic acid; examples of aromatic sulfonic acids include
Alkylbenzenesulfonic acids such as m-nonylbenzenesulfonic acid, p-decylbenzenesulfonic acid, p-undecylbenzenesulfonic acid, p-dodecylbenzenesulfonic acid, p-toluenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalene disulfone Acid, dialkylnaphthalenesulfonic acid or disulfonic acid such as dihexylnaphthalenedisulfonic acid, diheptylnaphthalenedisulfonic acid, dioctylnaphthalenedisulfonic acid, didecylnaphthalenedisulfonic acid, etc. is used. The acid may be added as desired, and may be added at the time of mixing the coating film-forming components or after mixing, for example, before adding the hydrophilic base. Also, when adding acid,
It may be added simultaneously or separately with the hydrophobic base,
In some cases, a salt-containing substance containing a reaction product with the base may be added, and in these cases, the same effect as the addition of acid alone can be obtained. The reason why a hydrophobic base is used to neutralize an acid in the present invention is that an acid is normally neutralized by a base and becomes water-soluble, but when a hydrophobic base is used, it becomes hydrophobic even after being neutralized. Since the neutralized product is included in the resin of the paint film forming component, it is not removed even if the paint is treated with ion exchange, and therefore even with continuous operation, the amount of acid in the paint may fluctuate. This is to keep it small. The acid or salt-containing substance is within 10% by weight, preferably within 5% by weight, based on the coating film forming components of the resin composition.
Particularly preferably, it is added in an amount of 1.0% by weight or less. This is necessary in order to preserve the excellent physical properties of the resulting matte coating. The hydrophobic base is particularly preferably one that is sparingly soluble or insoluble in water. Examples include long chain alkyl amines or amines containing aralkyl groups. The fluorine-based matte electrodeposition coating composition of the present invention can be used in a resin solid concentration range of 3 to 50% by weight, and may be used by diluting with water to an appropriate concentration by various coating means. At that time, commonly used colorants and other paint additives may be mixed and used. Furthermore, the fluorine-based matte electrodeposition coating composition of the present invention can be mixed with a coating composition that forms a coating film with excellent gloss, and the gloss of the resulting coating film can be adjusted as desired. When an object is coated with a matte paint prepared in this way, a uniform matte coating can be formed regardless of the material, shape, or size of the object. The matte electrodeposition coating composition of the present invention can be applied directly on a conventional electrodeposition coating line using the same method, or by a method using an electrodeposition coating containing a matting agent or by using a chemical agent to form an electrodeposition coating film. It has the advantage that it is always stable and can provide a uniform matte coating film with a low gloss value, which is not possible with post-treatment methods. In addition, the resulting matte coating has excellent adhesion to the object being coated, and has excellent weather resistance and
It also has excellent coating performance such as alkali resistance and boiling water resistance. Examples are shown below to explain the present invention in more detail. However, the present invention is not limited thereto. Example 1 A fluorine-containing polymer solution (trade name Lumiflon LFX-HED) having an acid value of 20 and a hydroxyl value of 80 was placed in a reaction vessel equipped with a stirring device, a thermometer, and a reflux condenser.
120 parts of Asahi Glass Co., Ltd.) and 30 parts of methoxybutoxy-mixed methylolmelamine (trade name: MX-40, manufactured by Sanwa Chemical Co., Ltd.) were charged and mixed by stirring. Then add triethylamine while continuing to stir.
After adding 4.2 parts, 150 parts of deionized water was further added to form an emulsion. The emulsion-formed contents were heated to about 90° C. and stirred for about 24 hours to complete the reaction and prepare a resin composition. Comparative Example 1 A resin composition was obtained in the same manner as in Example 1, except that after emulsion formation, stirring was performed at room temperature for 12 hours. Comparative Example 2 In the method of Example 1, ethylene glycol monobutyl ether 20
1 part and 80 parts of isopropyl alcohol, the contents were heated to about 90°C, stirred for about 12 hours, cooled to room temperature, and then triethylamine
After adding and mixing 10 parts, 150 parts of deionized water was further added to prepare a resin composition. Example 2 In the same method as in Example 1, 120 parts of a fluorine-containing polymer having an acid value of 40 and a hydroxyl value of 80 (trade name: Lumiflon FLX-HED, manufactured by Asahi Glass Co., Ltd.), methoxybutoxy mixed methylolmelamine (trade name: MX)
-40 (manufactured by Sanwa Chemical Co.)) After mixing 30 parts, p
-0.8 part of dodecylbenzenesulfonic acid was added and mixed. Next, while stirring, 2.5 parts of triethylamine was added, followed by further addition of 150 parts of deionized water to form an emulsion. The emulsion-formed contents were heated to about 90° C. and stirred for about 8 hours to complete the reaction and prepare a resin composition. Example 3 In the method of Example 2, tri-n-butylamine was added with 0.3 parts of p-dodecylbenzenesulfonic acid.
A resin composition was prepared in the same manner except that 0.2 part was added at the same time. Example 4 The method of Example 2 was repeated except that 0.5 part of a salt obtained by neutralizing p-dodecylbenzenesulfonic acid with tri-n-butylamine was added instead of p-dodecylbenzenesulfonic acid and the reaction was carried out. All resin compositions were prepared in the same manner. Comparative Example 3 In a reaction vessel equipped with a stirring device, a thermometer, and a reflux condenser, 4 parts of acrylic acid, 5 parts of 2-hydroxyethyl acrylate, 15 parts of 2-hydroxyethyl methacrylate, 10 parts of styrene, 15 parts of octyl acrylate, and butyl were added. 15 parts of acrylate, 36 parts of methyl methacrylate, 1.5 parts of azobisisobutyronitrile, 12 parts of ethylene glycol monobutyl ether, and 35 parts of isopropyl alcohol were stirred at reflux temperature (approximately 90°C) for 6 hours to form α, β-ethylenic Unsaturated polycarboxylic acid resin solution (acid value approx.
31) was prepared. In a separate reaction vessel equipped with the same stirring device, thermometer and reflux condenser as above, 100 parts of the above α,β-ethylenically unsaturated polycarboxylic acid resin solution,
After 30 parts of methoxybutoxy mixed methylolmelamine (trade name MX-40, manufactured by Sanwa Chemical Co., Ltd.) was charged and mixed, 0.8 part of P-dodecylbenzenesulfonic acid was added and mixed. Next, 2.5 parts of triethylamine was added while stirring, and then 150 parts of deionized water was added to form an emulsion. Approximately 90% of this emulsion
The temperature was raised to .degree. C., and stirring was continued for about 8 hours to complete the reaction and a resin composition was prepared. Application Example 1 The resin compositions obtained in Examples 1 to 4 and Comparative Examples 1 to 3 were adjusted to a resin solid content concentration of 10% by weight and used as a paint for electrodeposition coating. An aluminum plate that has been anodized in each paint and inorganically colored amber is used as the anode, and a stainless steel plate is connected as the cathode and immersed in the coating. A voltage of 180 volts is applied between the two electrodes, and the initial current density is
Direct current was applied at 1.0 A/dm for 2 minutes. After the electrodeposition coating was completed, each aluminum plate was taken out, thoroughly washed with water, and then dried with hot air at 150°C for 30 minutes.
As a result, the electrodeposition coating films formed on each aluminum plate were as shown in Table 1. In the example of the present invention, a uniform and fine-grained matte electrodeposition coating film was formed, whereas in Comparative Example 2, a coarse-grained electrodeposition coating film with less matte effect was formed. It was hot.

[Table] Example 5 In the same method as in Example 1, 120 parts of a fluorine-containing polymer solution (trade name Lumiflon LFX-HED manufactured by Asahi Glass Co., Ltd.), methoxy and butoxy mixed methylolmelamine (trade name MX-40 Sanwa) After mixing 30 parts of (manufactured by Chemical Co., Ltd.), 0.1 part of a salt-containing material previously obtained from p-dodecylbenzenesulfonic acid and di-n-butylamine was added and mixed. Then, while stirring, 4 parts of triethylamine were added, followed by 150 parts of deionized water to form an emulsion. The contents of this emulsion are approx.
The temperature was raised to 90°C and stirring was continued for about 4 hours to complete the reaction and a resin composition (matte resin composition) was prepared. The resin composition of Comparative Example 1 (glossy resin composition) was added to this resin composition at varying resin solid content ratios as shown in Table 2, and after thorough mixing, each resin composition had a resin solid content of 10% by weight. Application example 1 as a matte electrodeposition paint
Electrodeposition coating was performed on an anodized aluminum plate that had been subjected to inorganic electrolytic coloring using the same method as described above. As a result, the gloss values of the electrodeposited coatings were as shown in Table 2.

[Table] Comparative Examples 4 to 5 Resin compositions were obtained in the same manner as in Example 1 except that the fluorine-containing polymer was replaced with one having an acid value of 3 and 55, and the same method as in the application example was used. Electrodeposition paint was prepared using the method and electrocoating was performed. As a result, when the acid value is 3, the resin particles do not show sufficient electrophoresis, and only a non-uniform and thin electrodeposited film can be obtained, while when the acid value is 55, the appearance of the electrodeposited coating is poor. It was hot. (Effects of the Invention) As is clear from the results of the Examples, the fluorine-based matte electrodeposition coating composition of the present invention has excellent weather resistance,
A matte electrodeposition coating film with excellent coating performance such as alkali resistance and boiling water resistance is formed.

Claims (1)

[Scope of Claims] 1. The resin composition comprises (a) a fluorine-containing polymer having a carboxyl group and a hydroxyl group and having an acid value of 5 to 50 and a hydroxyl value of 30 to 150, and (b) an alkoxylated methylolmelamine. are the coating film-forming components, and these (a) components and (b)
A fluorine-based matte electrodeposition coating composition, characterized in that it is a composition containing a product obtained by heating an aqueous emulsion containing the components. 2. The resin composition is a composition containing a product obtained by adding a hydrophilic base and water during or after mixing components (a) and (b) to form an emulsion, and then heating the mixture. A fluorine-based matte electrodeposition coating composition according to claim 1. 3. After the resin composition is mixed with an inorganic acid and/or an organic acid during or after mixing components (a) and (b), and a hydrophilic base and water are added thereto to form an emulsion, The fluorine-based matte electrodeposition coating composition according to claim 1, which is a composition containing a product obtained by heating. 4 The resin composition is formed by adding and mixing an inorganic acid and/or an organic acid and a hydrophobic base during or after mixing components (a) and (b), and adding a hydrophilic base and water to this to form an emulsion. The fluorine-based matte electrodeposition coating composition according to claim 1, which is a composition containing a product obtained by heating after oxidation. 5 The resin composition is obtained by adding and mixing a salt-containing substance obtained from an inorganic acid and/or an organic acid and a hydrophobic base during or after mixing components (a) and (b), and adding and mixing a salt-containing substance obtained from an inorganic acid and/or an organic acid and a hydrophobic base. The fluorine-based matte electrodeposition coating composition according to claim 1, which is a composition containing a product obtained by adding and water to form an emulsion and then heating the product. 6. The fluorine-based matte according to any one of claims 1 to 5, wherein the resin composition is a composition containing a product obtained by heating at 40°C to reflux temperature. Electrodeposition paint composition.