JPH01301768A - Low-temperature curing type electrodeposition coating resin composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition, consisting of a polycarboxylic acid resin and a specific mixed alkyl etherified methylolmelamine resin and capable of reducing baking temperature and suppressing emission of formalin. CONSTITUTION:The objective composition obtained by blending (A) 50-95pts.wt. polycarboxylic acid resin with (B) 50-5pts.wt. mixed alkyl etherified methylolmelamine resin respectively having average <5 combined formaldehyde content, 1.0-3.5 methyl ether groups, 0.5-3.0 butyl ether groups, 0.5-3.0 imino groups and <0.5 methyol group per melamine nucleus and 1.5-3.5 average polymerization degree of the melamine nucleus with methanol, ethanol, etc., as an organic solvent, stirring and mixing the resultant blend. Furthermore, when the obtained composition is used as an electrodeposition coating, an organic amine and ammonia are added to make the polycarboxylic acid resin dispersible in water and the resultant resin is diluted with water for use.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a low-temperature curing type electrical layer coating and a resin composition.
Furthermore, the present invention relates to a low-temperature curing type paint with a mixed alkyl etherified methylol melamine side (111), which is a mixture of alkyl etherified methylol melamine.

[Conventional technology]

Electrodeposition coating has the advantage of being able to uniformly coat objects with complex shapes, offering excellent bifurcated coating efficiency and giving a beautiful appearance, and is used in many industrial fields. . As a resin composition used for electrodeposition coating, a composition of polycarbonate resin and melamine resin as a crosslinking agent has been put into practical use, and one melamine nucleus is methyl etherified methylol melamine resin or butyl etherified methylol melamine resin. Street fat is known. Furthermore, it has been proposed to use a mixed alkyl etherified methylolmemino resin in view of the co-progressivity of the cross-linking agent, and the drawback that the baking of the coating film requires a high anchorage temperature has been realized, and this problem has been completely solved. In order to do this, low-shang pottery is used as a necessary cross-linking agent for water-based paints, with an average of more than 50 formaldehyde bonds per melamine nucleus, and an average of 0.2 to 0.8 formaldehyde bonds per melamine nucleus. It has been conventionally known to use a methylol melamine resin containing free methylol and mixed alkyl etherification with metsunol and butanol (see Japanese Patent Publication No. 120641/1982).

However, when the above-mentioned mixed alkyl etherified methylol melamine resin is used as a crosslinking agent under the conditions of normal upper layer coating and baking, the hardness of the resulting coating film is still unsatisfactory if the baking temperature is less than 1501: However, since a coating film with good chemical resistance and solvent resistance cannot be obtained, and since there is a large amount of bound formaldehyde, there is a problem that a large amount of formaldehyde is generated during baking, which significantly impairs the working environment.

[Problem that the invention seeks to solve]

An object of the present invention is to provide an electrical coating resin composition that can be cured at a low temperature of less than 150° C. and forms an electrodeposition coating film with excellent physical properties.

[Means to solve all problems]

To explain the present invention in detail, the low porosity hardening type lumber paint composition of the present invention has (a) a polycarbonate resin of 50 to 95 parts, and (b) an average of less than 5 melamine nuclei per one melamine nucleus. Bound formaldehyde, methyl ether group of 10-55 solids, methyl ether group of 15-3.041 J, 0.5-
3.0 imino groups, less than 15 methylol groups' (r
7p, and the average degree of polymerization of the melamine core is 1.5 to 3.
50 to 50% of mixed alkyl etherified methylolmelamine fat.

According to research conducted by the present inventors, the baking temperature required for grading the electrolyte coating film is greatly influenced by the structure of the melamine resin used as a crosslinking agent, especially the number of imino groups per melamine nucleus. We obtained the knowledge that The present invention was made based on this knowledge, and by using the melamine resin shown below as a crosslinking agent, it has excellent low-temperature curing properties, generates less formalin when baking the paint film, and is easy to coat. This has achieved the objective of providing a ``Kame-N paint@degradable composition'' with excellent film properties.

A more detailed evaluation of the present invention reveals that (a) component polycarboxylic acid 1ηf) is usually used for electrodeposition paints as a 1ηf host.
Examples include acrylic resins, polyester resins, and polybutane-based resins having 15 to 200 carboxyl groups.

(The mixed alkyl etherified methylol melamine resin of the cutting component is characterized by a pre-occupied phase-determined structure factor,
Due to the average of less than 5 bound formaldehyde per melamine nucleus, cL5 ~ 3.0 imino groups and the average type 8 degree 15 ~ 55 correlation of the melamine nucleus, the accompanying free formaldehyde is completely reduced. , making low mold hardening possible.

In addition, the number of methyl ether groups is 1.0 to 1 per melamine nucleus.
The number of butyl ether groups is preferably 0.5 to 3.01, preferably 1.0 to 2.0.

When the number of butyl ether groups becomes more than AD.

The hydrophobicity of melamine resin becomes stronger, and the direction of separation from polycarbonate resin increases, which is undesirable due to the lack of stability of the electrodeposition bath, and furthermore, methyl When the ether group is used alone, the co-advance property becomes worse than that of the one-pile coating, and it accumulates in the bath shell, resulting in an imbalance in the bath composition. The coating film that was electrodeposited using this method has a surface V during baking.
Since rashes or craters occur, it is essential to have a degree of mixed alkyl etherification within the range shown in the figure below.

The number of imino groups is 0.5 to 3.0 per melamine nucleus, preferably 1
or 0.5 to 1.5 ([il range is appropriate,
Enables lower baking temperatures. If the number of imino groups is less than 115, it becomes difficult to lower the baking temperature.
If it exceeds 1,000,000, the physical properties such as water resistance and enemy resistance of the coating film will deteriorate, which is not preferable. The number of methylol groups is suitably less than 0.5 per melamine nucleus. When the number of methylol groups is 5 or more, a large amount of formalin is generated during coating, which is not favorable for the working environment of 7i Niji.

(1)) As a mixed alkyl etherified methylol melamine resin with a K content, a resin having a methyl ether group, a butyl ether group, an imino group, and a methylol group in one melamine nucleus in the respective numerical ranges, such as @1lii. In addition to the so-called single-batch product resin produced under conditions producing the mixed alkyl etherified methylol melamine 'fil BW, methyl etherified methylol melamine resin, butyl etherified methylol melamine resin,
It may also be a mixture with at least one pole selected from the group consisting of mixed algyl etherified methylol melamine resins outside the range specified in the present invention (however, half the amount of bound formaldehyde, methyl The number of ether groups, butyl ether groups, imino groups, methylol groups and the average electrical degree of the melamine nucleus must be within the range required by the present invention.) Also, depending on the manufacturing conditions, a mixture of mononuclear and polynuclear Even if there is, it can be used as long as it is within the waiting range.

The mixed alkyl etherified methylolmelamine street fat in the present invention is generally produced as follows.

Methylolmelamine is synthesized by heating melamine and formaldehyde under a totally basic condition.

Next, methanol and butanol are added to this to create a reaction under controlled conditions.

Another method is to add only methanol to the methylol melamine and react under hostile conditions to obtain a methyl etherified methylol melamine resin, and then to the methyl etherified methylol melamine resin by an ether exchange reaction under conditions of butanol. Manufacture.

The electrolayer coating resin composition of the present invention comprises the above-mentioned component (a) and (1)
) component and the total coating film forming component, and the mixing ratio of both is 50 to 95 M parts, preferably 60 to 95 M parts of (component).
A suitable amount of component 1) is 5 to 50 parts by weight, preferably 10 to 40 parts by weight, per 90-fold door part.

The resin composition of the present invention is prepared by putting (a) polycarbonate branched resin, (1) mixed alkyl etherified methylol melamine resin, and organic bath agent into a container equipped with a stirrer and a thermometer, and then stirring. Prepare by thoroughly mixing all steps.

Examples of bath additives include methanol, 5 ethanol, n
-Alcohols such as propanol, incrovir alcohol, n-butanol, imbutanol, 5ec-butanol, t-butanol, pentanol, etc., metelseron rub, etelseron rub, inglovir seron rub, buterseron rub, 5eC-buterseron rub, etc. I use all the seronlube etc.

When the resin composition Vl of the present invention is used as a coating material for electrolayer coating, an organic amine and/or ammonia solution is added to the polycarbonate resin τ (moisture-free)], and then the resin composition is prepared by adding water to a damp bale and adding water to the resin composition. Use by diluting to the desired amount. This organic amine and/or
Alternatively, the addition of ammonia can be carried out before, simultaneously with, or after the complete mixing of the polycarboxylic acid and the mixed alkyl etherified methylolmelamine street resin.

The ammonia or organic amine used to make the polycarboxylic acid resin water-dispersible includes ammonia, monomethylamine, dimethylamine, trimethylamine, monoetheramine, diethylamine, triethylamine, monoethanolamine, and diimpropylamine.

Alkylamines such as triethanolamine, monobutylamines, dibutylamines and tributylamine MW, monoethanolamine, jetanolamine, triethanolamine, monoimpropaturamine, diingronochunolamine, triinbanolamine, dimethyl Alkanolamines such as aminoethanol and diethylaminoethanol, alkyleneimines such as ethylenediamine, globylenediamine, diethylenetriamine and triethylenetetramine, alkyleneimines such as ethyleneimine and globyleneimine, piperazine, morpholine, pyrazine and pyridine. etc.

In addition, when preparing paints for electrodeposition coating, colorants commonly used in electrocoating, such as staining dyes, pigments, body pigments, erasing agents, and curing catalysts, and other additives, such as interfacial holding agents, oxidizing agents, etc. An inhibitor and an ultraviolet absorber may be added.

In the paint bath prepared by the above method, iron, steel, aluminum, those whose surfaces have been subjected to known chemical conversion treatments, and anodized aluminum, etc.
When the coating is applied, a uniform coating film can be obtained regardless of the shape and size of the article.

〔Example〕

Hereinafter, examples will be shown to specifically explain the five main brothers. In addition, "To" and "嘱" in Examples indicate parts by weight and weight %, respectively.

Production example of melamine resin Production shaver 1 Melamine 126 in a 1 ton four-eye flask with a thermometer, stirrer and reflux condenser. (1,0 mol) and 80
% paraform 168.75 F (4,5 mol) and methanol 520? (10,0 mol) all added, 20%
After adjusting the pH to 19.0 to 9.5 with caustic soda water fB7f, it was reacted for 60 minutes under reflux.
Cool at 0℃ and add 7926 ml of 50% IA.
The methyl etherification reaction was carried out at 35°C for 60 minutes. 20% caustic soda water bath after completion of reaction pH of liquid metalworking reaction number
was compressed to Z5 to 105, and then all methanol was distilled off under normal pressure. When the inner hood reached 80°C, it was compressed under reduced pressure to completely distill off all methanol. Next, the internal temperature was cooled to 60°C, 320y (10,0 mol) of methanol was added, kept at 35°C, 50% acetic acid was added, and the methyl etherification reaction was carried out again for 60 minutes. % caustic soda water bath, the pH of the reaction solution was adjusted to 95 to 1α5, and the same atmospheric pressure compression and vacuum compression as described above were carried out to completely distill methanol out of the thread.

Then, after cooling the inner fan at 60°C, the butano #277.
5S'(3.75%#) f7+1 was added with 4.5d of 50% while maintaining the temperature at 45°C, and an ether exchange reaction was carried out for 2 hours. After the reaction was completed, the pH'i was adjusted to 9.5 to 1 [15] due to the 20% caustic powder dissolved in water, and the neutralized salt was precipitated and the Pukunor odor was removed. Cool with reeds and dilute with ingubanol 90. Of(1,5 mol)? In addition, the neutralized salt was removed by suction filtration to obtain a mixed alkyl etherified methylolmelamine &J&(A-1)k with a nonvolatile content of 795%. The complete analysis results of this product are shown in Table 1.

Production Example 2 In Production Example 1, 80% paraform 1187.5r (5.0 mol) and diluted phase Improbanol total 114f (1.9
mol), and mixed alkyl etherified methylolmelamine at fat (A-
2) was obtained. The complete analysis results of this product are shown in Table 1.

Comparative manufacturing example 1 In Production Example 1, 80% pa2form was added for 5 oor(s).

molar) and ingubanol for dilution (i790. Of
' (1.5 mol), but in the same manner as above, another 11 batches of mixed alkyl etherified methylol melamine resin (B-1) with a yield of 85.5% was obtained. The analysis results of this product are shown in Table 1.

In a 3t flask equipped with a stirrer and a thermometer, add a commercially available acrylic thread polycarbonate 11 salt bathing liquid (sacred product name Kokunkusu WE152, made by Ishisha: solid content of fat 60%, carboxyl group) Mixed alkyl etherified methylol melamine resin (A-1-Gei-n) 38
The entire mixture was mixed uniformly by stirring at 50° C. for 60 minutes to obtain a complete electrodeposition coating resin composition. Next, deionized water 8
45 parts were added to prepare a screw paint having a resin solid content of 10 double stars.

Comparative Example 1 In the method of Example 1, mixed alkyl etherified methylol melamine resin B-
Except for changing the color to 135, all the methods were followed and all preparations were made for Tozen paint.

Ability to perform 2 Stirring % In a 3t flask equipped with a thermometer, commercially available acrylic thread polycarbonate side fat bath solution (product name Kota Sox WE152 manufactured by Toshisha Co., Ltd.) 85, mixed alkyl etherified methylol melamine (A-1 ) and 20 parts of Improvil alcohol were added and stirred at 30°C for 10 minutes, then n1 parts of deionized 7×40 parts were added and stirred for an additional 10 minutes. To this, 27 parts of titanium oxide (trade name: Kuibake CR-90, manufactured by Ishihara Sangyo Co., Ltd.) and 200 parts of glass beads were added, and after 2 hours of dispersion sound using a paint shaker, 800 parts of deionized water was added to form a white electrodeposition paint. Prepared.

Comparative f sili 2 real = 2 mixed alkyl etherified methylol melamine resin prepared in Comparative Preparation Example 1 in the method of yl12 B
- 126 parts and all the other methods were used to prepare the electric N paint. 〇Execution Series 6 In a 6t flask equipped with a stirrer and a thermometer (fl-), a commercially available acrylic thread polycarbo ) 108 parts of frost bath liquid (product name: Cortanx WE152 3i 1ll), alkynd resin (product name: Watersol VS230)
E1 (manufactured by Dainippon Ink Co., Ltd.) 19, mixed alkyl etherified metherol melami ya (fat (A-2) 3 s
HB, 10 parts of ethylene glycol monobutyl ether, and 1.5 parts of triethylamine were charged, and the mixture was heated at 50°C for 30 minutes.
The mixture was stirred for a minute and then diluted with 838 g of deionized water to prepare an electrolayer paint.

Ratio*9↑Siri 3 Mixed alkyl etherified methylolmelamine stool sebum B-1 prepared in Comparative Production Example 1 in the method of Example 5
I'i. Electrolayer paints were prepared by following the same method except that the number was changed to 36.

Implementation P2-4 In a 3-ton flask equipped with a stirrer and a temperature meter, add commercially available acrylic polycarbonate resin (trade name: Coketux W E 152, manufactured by V Company M) 1089, ? Reinated polybutadiene (trade name Nl5SO-PBC
N1010 Nippon Kaidatsha H) 20 parts, mixed alkyl etherified methylol melamine (A-11911x, 20 parts of ethylene glycol monobutyl ether and 6 parts of dimethylaminoethanolam).
After stirring for an hour, 815 parts of deionized water was diluted to n1, and then 15 parts of a carbon blank dispersion (trade name: CN LIJ Yoshoku Co., Ltd., manufactured by Yoshoku Co., Ltd.) was cooled, stirred, and dispersed throughout the entire black electrolayer paint. Prepared.

Comparative Example 4 In the method of Example 4, the mixed alkyl etherified methylol melamine resin B-11 prepared in Comparative Production Example 1
All the military layer paints were made using the same method except that the number 7 was changed.

Electron Coating Experiment Using the electrical paint gold prepared in Examples 1 to 4 and Comparative Examples 1 to 4, all electrical layer coating was carried out under the conditions shown in Tables 2 to 6. The results of measuring the physical properties are also shown in Tables 2 to 6.

However, the electrostatic coating was carried out by connecting the object to be coated to the anode and the stainless steel plate to the cathode. The objects to be coated were anodized aluminum (5) and phosphorous-treated steel sheets (1 coat of aluminum).

Coating film performance was tested according to the method of JIS H-8602. However, the bath agent resistance is determined by immersing absorbent cotton in a trench with methyl ether ketone, and rubbing the entire surface of the coating with it. Gloss retention was measured because of the water immersion test. The batters in Tables 2 to 6 were heated to 120℃ (Table 2) to adjust the effect of low-temperature baking.
140℃ (Table 6), 160℃ (No. 4 coating), 180℃ (
Table 5) and heat drying at 200°C (Table 6) and the results are shown.

〔Effect of the invention〕

The main feature of the present invention is to lower the baking temperature to less than 150 degrees Celsius, and to reduce the temperature at which the electrolytic layer coating is cured to less than 150°C. It also has the excellent effect of suppressing the energy consumption of the burner and reducing energy consumption and cost reduction.

Patent applicant: Mitsui Suiana Mint System Company: Honey Kasei Co., Ltd.

Claims (1)

[Claims] 1. (a) 50 to 95 parts by weight of polycarboxylic acid resin, and (b) an average of less than 5 bound formaldehyde per melamine nucleus, 1.0 to 3.5 methyl ether groups, 0.
It has 5 to 3.0 butyl ether groups, 0.5 to 3.0 imino groups, and less than 0.5 methylol groups, and the average degree of polymerization of the melamine core is 1.5 to 3.5. A low temperature curing electrodeposition coating resin composition comprising 50 to 5 parts by weight of a certain mixed alkyl etherified methylolmelamine resin.