JPS6017390B2 - Stabilized 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
Applications for construction and building materials such as sashes and gates are increasing, and the surface treatment is usually done by anodizing and then sealing or without sealing by coating methods such as glazing, electrostatic coating, and heat dipping. Painting with a composition suitable for painting is being carried out.

The present invention relates to a stabilized coating composition for aluminum and/or aluminum alloys to be used in the heat immersion coating method among these coating methods.

As a method of painting using a heated coating composition,
A coating composition in which a coating film-forming component is dissolved in a chlorinated hydrocarbon solvent is flooded to a temperature near the boiling point of the chlorinated hydrocarbon solvent, and the object to be coated is immersed in the composition. A method is generally known in which a uniform coating film is obtained by pulling up the composition through a vapor layer of the chlorinated hydrocarbon solvent generated on the liquid surface of the composition.

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 composition 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.

Compositions using thermoplastic acrylic resins, alkyd resins, epoxy resins, etc. are known as compositions that meet these purposes, but from the viewpoint of coating performance etc., thermosetting compositions, especially thermosetting Type acrylic compositions are suitable for coating aluminum and/or aluminum alloys.

However, thermosetting acrylic compositions generally have poor thermal stability due to their nature. The present inventors have previously invented and applied for a patent for a low-temperature curable composition containing an acrylic resin and aminoplast as main components as a thermosetting acrylic composition suitable for heat-durable coating. [Tokuma Sho 53-15
No. 9015 (Mochiseki Sho 55-184369)]. The composition of the above invention is significantly improved in stability compared to the conventional heat-durable coating composition.
It is also true that further improvements are desired. As a result of further intensive research into the stabilization of thermosetting acrylic paint compositions suitable for the above-mentioned heat soak coating method, the present inventors found that
Hydroxyalkyl ester of Q,8-ethylenically unsaturated carboxylic acid dissolved in chlorinated hydrocarbon solvent, or Q
, an N-methylol or alkoxymethyl derivative of an 8-ethylenically unsaturated carboxylic acid amide; Air alkylene oxide and [B' It was discovered that the addition of acrylonitrile and/or methacrylonitrile provides excellent thermal stability as a composition for hot dip coating of aluminum and/or aluminum alloys, and there is no thickening or discoloration with long-term heating. The invention has been completed. Chlorinated hydrocarbon solvents used in the present invention include trichloroethylene, 1,1,1-trichloroethane, perchlorethylene, carbon tetrachloride, chloroform, ethylene dichloride, and other non-flammable solvents with a boiling point of 50 qo to 130 oo. can be suitably used.

Furthermore, if necessary, up to 4% by weight of the chlorinated hydrocarbon solvent can be replaced with other organic solvents such as isopropyl/ml, alcoholic solvents such as butanol, or aromatic solvents such as toluene. Further, as the composition containing an acrylic resin and aminoplast as main components (hereinafter referred to as thermosetting acrylic composition) used in the present invention, the following compositions of acrylic resin and aminoplast can be used. The acrylic resin is a hydroxyalkyl ester of Q, B-ethylenically unsaturated carboxylic acid (to introduce a functional group reactive with the aminoplast) or Q
, an N-methylol or alkoxymethyl derivative of an 8-ethylenically unsaturated carboxylic acid amide, a Q,P-ethylenically unsaturated carboxylic acid, an alkyl ester of a Q,8-ethylenically unsaturated carboxylic acid, and optionally a vinyl monoisomer. Obtained by polymerization.

Monomers that can be used include hydroxyalkyl esters of acrylic acid or methacrylic acid such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate, N-methylol acrylamide, and N-methylol methacrylamide. , amide derivatives such as N-methyltoxyacrylamide and N-methylmethoxymethacrylamide, acrylic acid, methacrylic acid, fumaric acid,
Unsaturated acids such as maleic acid and itaconic acid, methyl acrylate, methyl methacrylate, ethyl acrylate,
Examples include alkyl esters of acrylic acid or methacrylic acid such as ethyl methacrylate, butyl acrylate, and butyl methacrylate, and pinyl compounds such as styrene and vinyltoluene. As the aminoplast, N-methylol alkyl etherified melamine and/or N-methylol alkyl etherified penzoguanamine can be used. For example, methoxymethylated melamine, ethoxymethylated melamine, butoxymethylated melamine, isoptoxymethylated melamine, methoxymethylated penzoguanamine, ethoxymethylated penzoguanamine, methoxymethylated penzoguanamine, isobutoxymethylated penzoguanamine Monomers such as monomers, multimers of duplexes or higher, and mixtures thereof can be used. Furthermore, mixed cable type methoxymethyl/butoxymethylated melamine, methoxymethyl/butoxymethylated penzoguanamine, etc. can also be used. The mixing ratio of acrylic resin and aminoplast in the thermosetting acrylic composition is acrylic resin 50~
Preferably, the amount of aminoplast is 50 to 5 parts by weight per 95 parts by weight, and the nonvolatile content in the composition is preferably 10 to 5% by weight.

The composition of the present invention can be used not only at a high temperature near the boiling point of the chlorinated hydrocarbon solvent as described above, but also at room temperature.

The alkylene oxide as an essential component of the present invention is C3-
C5 alkylene oxides are preferred, such as 1,2-epoxides such as propylene oxide, butylene oxide, or 1,3- or 1,4-epoxides such as trimethylene oxide, tetrahydrofuran, tetrahydropyran.
Mono- or 1,5-eboxide can be preferably used.

However, when using alkylene oxide alone, the stability was only improved by about 50 to 10 feeding hours in a thermal stability test compared to a composition without additives, but no significant effect was obtained. On the other hand, when acrylonitrile and/or methacrylonitrile were used alone, the thermal stability deteriorated, and in some cases, the viscosity increased after 500 hours. However, it has been found that when alkylene oxide and 'B' acrylonitrile and/or methacrylonitrile are used together, the thermal stability is improved by about 100 hours or more compared to the case where no additive is used. The amount of alkylene oxide and acrylonitrile or methacrylonitrile to be added is preferably 0.1 to 5% by weight for the alkylene oxide and 0.1 to 5% by weight for acrylonitrile or methacrylonitrile based on the resin group. be. This composition can be used as a clear material without dispersing pigments, and can also be used with inorganic pigments that do not react with chlorinated hydrocarbon solvents, such as metal oxides such as titanium oxide, iron oxide, lead oxide, or katsura. It is also possible to color with organic pigments or organic dyes such as acid salts, talc, silica, mica, carbon, calcium carbonate, barium sulfate, and phthalocyanine compounds.

Furthermore, surfactants, plasticizers, and other additives commonly used in the art may be added to improve workability, coating finish, coating performance, etc. Aluminum and/or aluminum alloy as the object to be coated is processed into shapes such as window frames, plates, twills, wires, films, etc. by extrusion, rolling, drawing, etc., and can be used as is or after degreasing and etching treatment. Surface treatments such as chemical conversion treatment with boehmite, phosphate, etc., or anodization treatment in a turtle shark bath with sulfuric acid, phosphoric acid, organic acids, etc. alone or in combination with two or more are used.

After anodizing, it is further electrolytically colored with direct current or alternating current in a metal salt bath such as nickel or tin, or dyed with a case containing conventionally known inorganic or organic dyes.
It is also possible to use products that have been washed with hot water containing or not containing basic substances such as metal salts and amines. Furthermore, in order to avoid bringing moisture into the heated coating case, it is desirable to perform draining and drying at a temperature of 80 to 150 pm after the above-mentioned pretreatment, and cool it to near the normal temperature of the coating case before soaking into the coating case. . Next, the present invention will be specifically explained with reference to Examples.
Parts and percentages are by weight. Example 1 and Comparative Example 1 An acrylic resin solution consisting of 3 parts of methacrylic acid, 35 parts of butyl acrylate, 15 parts of 2-hydroxyethyl methacrylate, and 47 parts of methyl methacrylate was dissolved in trichlorethylene to prepare an acrylic resin solution with a non-volatile content of 70%. It was created.

A clear paint was prepared using this acrylic resin liquid according to the following formulation. Acrylic resin liquid 52.
Group part melamine resin (Sumimar M-10 manufactured by Sumitomo Chemical Co., Ltd. ■6.4) Trichlorethylene 141.4 Butylene oxide 1.0 Acrylonitrile 1.0 Total 202.0 Butylene oxide and acrylonitrile in the above composition Comparative Example 1 is a paint that does not contain .

Each of these was placed in a 1000 cc round glass container with a condenser attached to the top of the test flask, and heated at 80 qo for 2 hours.
A 50-hour thermal stability test was conducted.

The results are shown in Table-1. Immediately after production, each composition was placed in a heated coating device equipped with a cooling device above the liquid level, and flooded between 70 and 75 p.m. to seal the end-sealed holes obtained by anodizing 6 $ aluminum. The treatment liquid was immersed, pulled up through a vapor layer of trichloroethylene formed on the liquid surface, and immediately dried in a hot air drying oven at 170°C for 30 minutes.

Table 1 shows the performance of each coating film. Furthermore, after conducting a thermal stability test for 250 hours at 8 and 0 as described above, the composition was similarly coated on a pore-sealed board obtained by anodizing 6$ aluminum, and a performance test was conducted. .

The results are shown in Table-1. Example 2 A test similar to Example 1 was conducted using 1 part of tetrahydrofuran and 0.5 part of methacrylonitrile in place of the butylene oxide and acrylonitrile of Example 1.

The results are shown in Table 1. Example 3 and Comparative Example 2 An acrylic resin consisting of 5 parts of acrylic acid, 1 group of butyl acrylate, 27 parts of 2-hydroxyethyl methacrylate, 26 parts of methyl methacrylate, 2 parts of styrene, and 1 part of ethyl acrylate was used. A resin solution having a nonvolatile content of 70% was prepared by dissolving it in n-butyl alcohol.

A clear paint was prepared using this acrylic resin liquid according to the following formulation. Acrylic resin liquid 49.
2. Melamine resin (Sumimar M-6 porridge manufactured by Sumitomo Chemical Co., Ltd. ■8.6) Trichlorethylene 142.2 Butylene oxide 1.5 Methacrylate.

Nitrile 1.6 total 203.0 In the above composition, butylene oxide and Methac I
Comparative Example 2 is a paint that does not contain Jronitrile.

These paints were subjected to the same thermal stability test and performance test as in Example 1. The results are shown in Table-1. Example 4 and Comparative Example 3 16 parts of N-methylol acrylamide, 2 parts of methacrylic acid, 42 parts of methyl methacrylate, 1 part of styrene,
An n-butyl alcohol solution (non-volatile content: 70%) of an acrylic resin consisting of three groups of isobutyl methacrylate was prepared, and a clear paint was obtained using the following formulation.

Acrylic resin 52.2 parts Melamine resin (Sumimar M-6 manufactured by Sumitomo Chemical Co., Ltd.) Trichlorethylene 141.4 Butylene oxide 1.2 Acrylonitrile 0.6 Total 201.8 Butylene oxide in the above composition Comparative Example 3 is a paint containing no acrylonitrile.

These paints were subjected to thermal stability tests and performance tests on the same machine as in Example 1. The results are shown in Table-1. ■ A bare bonito dish that is completely requested by a sow who is about to leave the ship.

Cloth j Sentouya Lt IH 'ya D...n*nfu crotch entry L. - Kigun Thin 3) Pisaki Into R Dimension Extrusion ** As stated above, the composition obtained from the present invention has a higher level of stability compared to a comparative example that does not contain alkylene oxide and acrylonitrile and/or methacrylonitrile. It can be seen that the coating film exhibits excellent thermal stability and the performance of the resulting coating film is also excellent.

Comparative Example 4 When the same thermal stability test as in Example 1 was conducted using the paint composition used in Example 1 except for acrylonitrile, the viscosity increased to 22.6 seconds after 170 field hours.

Comparative Example 5 When the same thermal stability test as in Example 1 was conducted using the coating composition used in Example 1 except for butylene oxide, the viscosity increased to 23.6 seconds at 50°C.

Claims (1)

[Scope of Claims] 1. A hydroxyalkyl ester of an α,β-ethylenically unsaturated carboxylic acid or an N-amide of an α,β-ethylenically unsaturated carboxylic acid dissolved in a chlorinated hydrocarbon solvent.
Methylol or alkoxymethyl derivative and α,β-
A composition containing an acrylic resin and aminoplast obtained by copolymerizing ethylenically unsaturated carboxylic acid and an alkyl ester of α,β-ethylenically unsaturated carboxylic acid as main components (A) alkylene oxide and (B) A stabilized composition for hot dip coating of aluminum and/or aluminum alloys, characterized in that it contains acrylonitrile and/or methacrylonitrile.