JPS608059B2 - Coating composition for hot dip coating of aluminum and/or aluminum alloys - Google Patents

Description

[Detailed Description of the Invention] In recent years, aluminum and/or aluminum alloys have been increasingly used in construction and building materials such as sashes and gates.
The surface treatment is usually done by coating with a coating composition suitable for each coating method, such as electrodeposition, electrostatic coating, or heating bonding, with or without sealing using an anodizing solution. It is being done.

The present invention relates to a coating composition for aluminum and/or aluminum alloys used in the heated groove coating method among these coatings. A coating method using a heated coating composition involves humidifying a coating composition in which the coating film-forming components are dissolved in a chlorinated hydrocarbon solvent to a temperature close to the boiling point of the chlorinated hydrocarbon solvent. However, there is a generally known method in which the object to be coated is immersed in the composition and pulled up through a vapor layer of the chlorinated hydrocarbon solvent generated on the liquid surface of the composition to form a uniform coating film. There is. This coating method has many advantages, such as uniform coating thickness, no uneven coating, and no risk of fire. In order to achieve this, the above-mentioned composite is required to have long-term heat stability, that is, to have no increase in viscosity, gelation, change in hue, or deterioration in coating performance.

As compositions meeting these objectives, compositions using various synthetic resins such as thermoplastic acrylic resins, alkyd resins, and epoxy resins are known.

Also, as a composition using thermosetting acrylic resin...
1}Q,8-N- of ethylenically unsaturated carboxylic acid amide
Compositions based on methylol or alkoxymethyl derivatives (Japanese Patent Publication No. 47-45176), '2} Similar compositions having an intrinsic viscosity of 0.005 to 0.017 (Japanese Patent Publication No. 49-9082) ) etc. have been proposed. However, in these thermosetting acrylic resin compositions, the acrylic resin used is an amide type, and the functional group contained is an N-methylol group or an N-alkoxymethyl group, which has a highly reactive side chain. The use of acrylic resins made of monomers that do not contain nitrogen but contain hydroxyl groups may accelerate the decomposition of the chlorinated hydrocarbon solvents used or cause deterioration due to thermal decomposition products of the chlorinated hydrocarbons. Excluded from resin compositions. Therefore, it is necessary to increase the degree of antization when phosphorizing the paint film, and if the oxidation temperature is increased, the acrylamide resin used will yellow significantly because it contains nitrogen atoms. For this reason, it is difficult to obtain the lead hardness of the paint film required for building material use of 4 days or more, and it is low, ranging from granite to fine. It was not possible to avoid the drawback that the coating was easily damaged. In addition, a composition containing phenolic and thioether stabilizers (Japanese Patent Publication No. 52-488) was proposed as a stable composition for hot coating, and ``acrylic acid hydroxyalkyl ester resin can also be used in combination with the above stabilizers. However, the use of stabilizers increases the cost of the composition, and it has not been possible to provide a composition for inexpensive heated coating.Furthermore, these compositions have a short heating time. It becomes colored with the passage of time, and becomes colored 4 to 5 with one Gardna color, and in some cases to 6 to 7. Even when compared with the naked eye, it can be seen that the coating film that is formed is clearly colored from the beginning. In order to improve the above-mentioned drawbacks, the present inventors, as a result of research, unexpectedly found that hydroxyalkyl esters of acrylic acid and/or methacrylic acid, Q,6-ethylenically unsaturated carboxylic acid and Q, B-A composition obtained by dissolving a mixture of aminoplast and a resin obtained by copolymerizing an alkyl ester of an ethylenically unsaturated carboxylic acid as an essential component in a chlorinated carbon solvent is prepared by dissolving aluminum and/or When used for heat-curing aluminum alloy coating, it has excellent low-temperature resistance, improves the hardness of the formed coating, and improves performance such as coating hardness, weather resistance, and chemical resistance. The present invention was completed based on the discovery that it provides an excellent coating film, is stable against long-term heating, and does not exhibit significant thickening or coloration without adding a stabilizer.

The hydroxyalkyl ester of acrylic acid and/or methacrylic acid, the alkyl ester of Q'8-ethylenically unsaturated carboxylic acid and the alkyl ester of Q,3-ethylenically unsaturated carboxylic acid used in the present invention are copolymerized as essential components. The resulting resin (hereinafter referred to as hydroxyl group-containing acrylic resin) is a mixture of acrylic acid and/or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, and hydroxybutyl methacrylate. Q,8-ethylenically unsaturated carboxylic acids copolymerizable with equal ester monomers and their alkyl esters, such as unsaturated acids such as acrylic acid, methacrylic acid, fumaric acid, maleic acid, itaconic acid, acrylic acid methyl,
Methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, propyl methacrylate,
It is obtained by copolymerizing esters such as butyl acrylate, butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, ethylhexyl acrylate, and ethylhexyl methacrylate. Furthermore, if necessary, a polymerizable unsaturated monomer containing a hydroxyl group in the molecule, such as allyl alcohol or monoallyl ether of polyhydric alcohol, such as styrene or vinyltoluene, can be added. Furthermore, in the resin used in the present invention, hydroxyl groups can be introduced into the acrylic resin by polymerizing vinyl acetate with other acrylic monomers, etc., and then hydrolyzing the vinyl acetate unit. Although the amount of hydroxyl groups in the hydroxyl group-containing acrylic resin is not particularly limited, the hydroxyl value of the resin is preferably 40 to 200 from the viewpoint of heat stability, reactivity with aminoplast, and performance of the coating film formed. Further, from the viewpoint of thermal stability, the weight average molecular weight of the resin is preferably in the range of about 7,000 to about 200,000. Next, the aminoplast used in the present invention is one that coexists with the hydroxyl group-containing acrylic resin and has the effect of forming a strong coating film through reaction crosslinking during coating film formation and during competitive drying. Often, therefore, N-methylol alkyl etherified melamines, and non- or N-methylol alkyl etherified penzoguanamines, such as methoxymethylated melamine, ethoxymethylated melamine, butoxymethylated melamine, isobutoxymethylated melamine, methoxymethylated penzoguanamine Monomers such as guanamine, ethoxymethylated penzoguanamine, butoxymethylated penzoguanamine, and isobutoxymethylated penzoguanamine, dimers or higher polymers, and mixtures thereof can be used, so if only ordinary amino resins are used, The above monomers and oligomers are also included.

Preferably, mixed ether type methoxymethyl/butoxymethylated melamine, methoxymethyl/isobutoxymethylated melamine, methoxymethyl/butoxymethylated penzoguanamine, methoxymethyl/isobutoxymethylated penzoguanamine, etc. can be used. The degree of alkyl etherification of these aminoplasts is 2 to 6 per triazine ring.
It is desirable that the number of This is available on the market, such as Sumimaru M-10 ratio, N-50, M
-40 and M-30 (methylated melamine-based aminoplast resins), M-6 (mixed methylated and butylated melamine-based aminoplast resins); Nikaratsuk MW-30 and MX-40 (melamine-based Aminoplast resin); Melan 20, 22, 2 manufactured by Hitachi Chemical
5, 26, 27, 28 and 29 (butylated melamine aminoplast resin); Super manufactured by Dainippon Ink Co., Ltd.
Bethkamin J-820-60, G-821-60, L-
101-60, L-109-65 (butylated melamine aminoplast resin), Super Beckamine TD-
126 (butylated penzoguanamine-based aminoblast resin); Mitsui Tosho Co., Ltd. Yuban 2$B (butylated melamine-based aminoflast resin), Yuban 90 and 91-
55 (benzoguanamine-based aminoplast resin), Cymel 1123, 1124, and 1125 (benzoguanamine-based aminoplast resin). The mixing ratio of the hydroxyl group-containing acrylic resin and aminoplast is preferably 50 to 5 parts by weight of the aminoplast to 50 to 95 parts by weight of the hydroxyl group-containing acrylic resin. Chlorinated hydrocarbon solvents that can be used in the present invention include trichlorethylene, 1,1,1-trichloroethane, perchlorethylene, carbon tetrachloride, chloroform, ethylene dichloride, etc. whose boiling point is 50 to 130 oo. Non-flammable materials are preferred.

Preferably, the non-volatile content in the composition of the invention is between 10 and 5% by weight. The composition according to the invention has a content of 60 qo~
Even with long-term heating in the range of 12,000°C, there is no significant increase in viscosity or gelation, and it has excellent discoloration resistance compared to conventional coating compositions, and can be baked under a wide range of baking conditions from 13,000 to 23,000, from LO to 5 female. Particularly preferably 14
It is possible to apply at a relatively low temperature for 15 to 40 minutes at a temperature of 0q0 to 18000, and the hardness of the coating film that is formed is from kasu to 4 days.
In some cases, it is possible to obtain a coating film with excellent spotting.

The composition of the present invention can be used as a clear material without dispersing pigments, etc., and can also contain inorganic pigments that do not react with chlorinated hydrocarbon solvents, such as titanium oxide, iron oxide, lead oxide, zinc oxide, etc. In addition to metal oxides, silicates, talc, silica, mica, carbon, calcium carbonate, barium sulfate, etc., it can also be colored with organic pigments such as phthalocyanine compounds, or organic dyes.

Furthermore, surfactants, plasticizers, and other additives commonly used in the art may be added to improve workability, coating finish, coating performance, etc. The composition of the present invention can be used not only at high temperatures near the boiling point of the chlorinated hydrocarbon solvent used as described above, but also at lower temperatures, for example, around room temperature, depending on the case.

The aluminum and/or aluminum alloy to be coated can be processed into shapes such as window frames, plates, rods, wires, films, etc. by extrusion, rolling, drawing, etc., and can be used as is, or after degreasing or etching. , surface treatment such as chemical conversion treatment with boehmite or phosphate, or anodization treatment with one or more electrolytes such as sulfuric acid, phosphoric acid, or organic acid. After anodizing, it can be electrolytically colored with a metal chloride such as nickel or tin using direct current or alternating current, or dyed with a conventionally known inorganic or organic dye.
It is also possible to use products that have been washed with hot water, with or without containing 00 metal salts, basic substances such as amines, etc. Furthermore, in order to avoid bringing moisture into the heated coating bath, it is desirable to perform drain drying at a temperature of 80 to 150[deg.] C. after the above-mentioned pretreatment, and cool it to near the bath temperature of the coating before soaking into the coating. When hot bond coating aluminum and/or aluminum alloys using the composition of the present invention, the coating made of the composition of the present invention is heated to near the boiling point of the chlorinated hydrocarbon solvent used. The aluminum and/or aluminum alloy, surface-treated or untreated as described above, is soaked and pulled up through a vapor layer of chlorinated hydrocarbons formed on the surface of the coating, and heated at 13,000 to 230 oo for 10 to 20 minutes. This is done by attaching the light in 5 minutes.

Production Examples and Examples are given below to illustrate the production of the hydroxyl group-containing acrylic resin used in the present invention and specific examples of the present invention.

Parts and percentages are by weight. Production Example 1 A four-necked flask equipped with a broken frame vessel, a reflux condenser, a thermometer, and a dropping funnel was charged with 20 parts of isopropanol and 40 parts of xylene, and heated to reflux temperature.

Next, 3 parts of methacrylic acid, 35 parts of butyl acrylate, and 2-hydro. A mixture consisting of 15 parts of xyethyl methacrylate, 47 parts of methyl methacrylate and 12 parts of azobisisobutyronitrile is added dropwise into the flask under reflux over 4 hours. After the dropwise addition was completed, reflux was continued for another 2 hours to completely react the remaining monomers, resulting in a non-volatile content of 61.8%.
A resin liquid was obtained. The hydroxyl value of the obtained resin was 64.7,
The weight average molecular weight was about 19,000. This resin liquid was heated and depressurized to remove the polymerization solvent, and then trichlorethylene was added to obtain an acrylic resin liquid with a nonvolatile content of 70%.
Production Example 2 Using 70 parts of n-butyl alcohol as the polymerization solvent, 66 parts of methacrylic acid, 590 parts of methyl methacrylate
parts, 104 parts of styrene, 200 parts of inbutyl acrylate
A polymerization reaction was carried out in the same manner as in Production Example 1 using a composition of 157 parts of ethyl acrylate, 28 parts of 2-hydroxyethyl acrylate, and 35 parts of azobisisobutyronitrile. The resulting resin had a hydroxyl value of 96.3 and a weight average molecular weight of approximately 1.
It was 5000. Next, in the same machine of Production Example 1, the solvent was replaced with trichloroethylene to obtain an acrylic resin liquid with a non-volatile content of 70%.Production Example 3 N-butyl alcohol 20%,
Using 40 parts of xylene as a polymerization solvent, 6 parts of methacrylic acid, 30 parts of butyl acrylate, 20 parts of 2-hydroxyethyl methacrylate, 10 parts of methyl methacrylate, 10 parts of styrene, 24 parts of ethyl acrylate,
Four bales of azopisisobutyronitrile were polymerized in the same manner as in Production Example 1, and then the solvent was replaced with trichlorethylene to give a non-brightening content of 70%.

The hydroxyl value of the resin is 86.3, and the weight average molecular weight is approximately 1750.
It was 0. Production Example 4 The polymerization solvent was 25 parts of isobutyl alcohol and 45 parts of xylene, 33 parts of acrylic acid, and 4 parts of butyl acrylate.
2 foundations, 14 parts of 2-hydroxyethyl methacrylate, 637 parts of methyl methacrylate, 17 parts of styrene,
25 parts of azobisisoptylonitrile was polymerized in the same manner as in Production Example 1, and then the solvent was replaced with trichlorethylene,
The nonvolatile content was 70%.

The hydroxyl value of the resin is 44.2, and the weight average molecular weight is approximately 170.
It was 00. Production Example 5 Using 15 parts of isobutyl alcohol and 45 parts of xylene as a solvent, 110 parts of butyl acrylate, 27 parts of 2-hydroxyethyl methacrylate, 26 parts of methyl methacrylate, 20 parts of styrene, and 20 parts of ethyl acrylate.
Takubu, 10 parts of ethylhexyl methacrylate, 5 parts of acrylic acid, and 3 parts of azobisisobutyronitrile were polymerized in the same manner as in Production Example 1, and then the solvent was replaced with trichlorethylene, and the nonvolatile content was 70%. did.

The hydroxyl value of the resin is 116. Weight average molecular weight is approximately 100
It was 00. Comparative Example 1 (Production of N-methylolamide-containing acrylic resin) 60 g of n-butyl alcohol was charged into the apparatus used in Production Example 1 and heated to reflux temperature.

Next, a mixture consisting of 210 parts of N-methylol acrylamide, 28 parts of acrylic acid, 560 parts of methyl methacrylate, 14 parts of styrene, 392 parts of inbutyl acrylate, and 1 $ of azopisisobutyronitrile was refluxed for 4 hours. Drop into flask. After the completion of the dropwise addition, the refluxing state was maintained for 2 hours to allow the remaining monomers to react completely, thereby completing the polymerization. As in Production Example 1, the solvent was replaced with trichloroethylene to obtain a resin liquid with a nonvolatile content of 70%. Examples Trichloroethylene solutions of the acrylic resins obtained in Production Examples 1 to 5 and Comparative Example 1 were used to prepare clear paints with the following formulations.

Table 1 As a result, a coating composition for hot-dip coating with a non-volatile content of 21.5% was obtained.

Each of these was placed in a 1000 c round glass container with a condenser attached to the top, and 80 qo and 15
A thermal stability test was conducted during 0 loading.

The results of the thermal stability test are shown in Table 2. Furthermore, each composition was placed in a heated immersion coating apparatus equipped with a cooling device above the liquid level, and the unsealed plate obtained by anodizing 6$ aluminum was immersed by flooding to 70 to 75 qo. , pulled up through the solvent vapor layer formed on the liquid surface, and immediately baked in a hot air drying oven at 170d0 for 30 minutes for Production Examples 1 to 5, and 20 minutes at 170qo and 190d0 for Comparative Example 1. went. Table 2 shows the performance of each coating film. Furthermore, after performing a thermal stability test at 80°C for 150 hours, each composition was similarly coated on a sealed pore-treated board obtained by anodizing 6$ aluminum, and a performance test was performed. went.

The results are shown in Table 2. ship.

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As described above, the composition obtained from the present invention has excellent thermal stability compared to the comparative example used conventionally, and C
Even if it is ranked low, it has excellent pencil hardness, sulfur dioxide gas resistance, and weather resistance, and is comparable in other respects.

Third Division (Mi) Amendment pursuant to the provisions of Article 64 of the Patent Law (Zc day of month Z, Showa Raza). Published patent number et al. C-80S Onuma Wa 53 year patent face No. 159015
No. 59, Patent Publication 3'3'-1, issued on February 28, 1986.
5 (No. 456)) has been amended pursuant to the provisions of Article 64 of the Patent Law, so it is published as follows.

“Patent No. 1407029 lnt.C!.4
Identification code: Office reference number CO9D 3/81
724-4J No. 1 The “Scope of Claims” section was changed to “1
Hydroxyl value 40 obtained by copolymerizing hydroxyalkyl ester of acrylic acid and/or methacrylic acid, Q, ethylenically unsaturated carboxylic acid and 〇, alkyl ester of ethylenically unsaturated carboxylic acid as essential components. ~200 resin and aminoblast, and the ratio of the resin obtained by the above copolymerization to aminoplast is 55
~90/45''10 is dissolved in a chlorinated hydrocarbon solvent, and the non-volatile content is more than 15% by weight, for heat-immersion coating of aluminum and/or aluminum alloys. Coating composition.

” he corrected. 2 Column 4, lines 30 and 31, “200
is desirable.

'' is set to ``200.'' If the hydroxyl value is less than 0, the number of crosslinking points with aminoblast, which will be described later, will be too small, and the coating film formed will not have sufficient performance.
If the amount is exceeded, it is necessary to use a large amount of aminoblast to complete the reaction with the hydroxyl group, but this has the disadvantage that the formed purulent material becomes hard and brittle. For this reason, if the amount of aminoblast is reduced, hydroxyl group-containing acid residues will remain.
This method is not preferable because it significantly reduces the water resistance and alcohol resistance of the coating. ” he corrected. 3
Column 5, lines 32 to 34, “Hydroxy/…desirable.

” to “Hydroxyl group-containing acrylic resin 55-90
The amount of aminoblast is 45 to 10 parts by weight. If the hydroxyl group-containing acrylic resin exceeds 55 parts by weight, that is, the aminoplast exceeds 45 parts by weight, the physical properties of the resulting coating film will become rigid and brittle, unable to withstand the required impact resistance, etc., and the beauty value will be low. . Also, if the hydroxyl group-containing acrylic resin is 90 parts by weight, that is, if the aminoplast is less than 10 parts by weight. Aminov. The number of crosslinking points caused by last is too small, and although a coating film is formed, the coating film has poor durability and solvent resistance. ” he corrected. 4 Column 5, lines 40 and 41, “The present invention...
··desirable.

"The non-volatile content in the composition of the present invention is greater than 15% by weight, preferably 20 to 60% by weight. Required film thickness during coating. Chlorinated hydrocarbon The nonvolatile content should be adjusted using a solvent, but if it is less than 15% by weight, it is almost impossible to adjust, and the only way to obtain the desired film thickness is to adjust the pulling speed, which hinders production speed. In addition, the non-volatile content may exceed 60% by weight, but in this case the viscosity becomes high and the transfer time may become longer or the power cost for transfer may become large.Also, especially in winter, This is not desirable because it creates the need to keep warm." 5 Change “Table 1” to “Table 1” on page 5, line 1.
(Part 1)”.

6 Add “Table 1 (Part 2)” next to “Table 1” on page 5 o 7 Column 9, lines 9 to 10, “This resulted in...

'' to ``Thus, with the exception of Comparative Example 2, the non-volatile content was 21.5%.
A coating composition for heat-immersion coating was obtained. Furthermore, comparative example 2
The nonvolatile content of was 10.75%. Comparative examples 2 and 3
In this case, the resin obtained in Production Example 2 was used as the hydroxyl group-containing acrylic resin. In Comparative Example 3, the ratio of hydroquinyl group-containing acrylic resin/aminoplast was 45/5. ” he corrected. 8 Change “Table 2” on page 6 to “Table 2 (Part 1)”
)” is corrected.

9 On page 6, next to “Table 2”, “Table 2 (Part 2)” ” to join.

Claims (1)

[Claims] 1 A resin obtained by copolymerizing a hydroxyalkyl ester of acrylic acid and/or methacrylic acid, an α,β-ethylenically unsaturated carboxylic acid, and an alkyl ester of α,β-ethylenically unsaturated carboxylic acid as essential components, and an amino acid. 1. A coating composition for hot-dipping coating of aluminum and/or aluminum alloys, characterized in that it is prepared by dissolving a mixture of plastic and plastic in a chlorinated hydrocarbon solvent.