JPH0680928A - Coating material for metallic material - Google Patents

Abstract

PURPOSE:To obtain a coating material which can be used as a primer or a sealer irrespectively of whether the topcoating material is of baking type or cold-curing type and can improve the rust-preventive power of burrs by mixing a cationic epoxy resin as a base with a pigment and other additives. CONSTITUTION:The coating material comprises an amino-modified epoxy resin as a base, a coloring pigment, a solvent, an organic acid and deionized water. The coloring pigment consists mainly of about 99wt.%, based on the coloring pigment, titanium oxide which can act also as an extender pigment and about 0.8wt.%, based on the coating material, a rust-preventive pigment (based on lead silicate).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating material for metal materials used as an undercoat or an intermediate coating.

[0002]

2. Description of the Related Art As is well known, equipment and devices made of metal materials are generally coated in order to improve rust prevention and aesthetic functions. In this coating process, pretreatment, undercoating and intermediate coating are performed. , Topcoating and drying steps. In the drying process, there are baking drying and natural drying depending on the topcoat paint. Of these, different intermediate coating paints are used for the baking finish topcoat paint and the room temperature finish topcoat (normal temperature dry paint). ing. Epoxy resin-based cationic electrodeposition coating is applied as an undercoat to the baking paint and the room temperature dry paint.

[0003]

Therefore, in conventional undercoat paints and intermediate paints, it is not possible to use the same when the top paint is a baking paint and when it is a room temperature dry paint, and different intermediate paints are used. Since the paint is required, pretreatment-primer coating-intermediate coating cannot be performed in the same step.

Therefore, for example, when there is a part in which the top coat paint is changed from the baking paint to the room temperature dry paint, the next process must be changed each time, which is not only troublesome but also the automation line becomes complicated and the process change is required. Mistakes can occur.

In addition, in the general type (including thick film type) epoxy resin type cationic electrodeposition coating, even if the top coating is applied, it is formed when the plate material is sheared. For example, in the elevator car door 10 shown in FIG. The coating formed on the outer circumference 6A of the burr portion (hereinafter referred to as a flash portion) 2 shown in FIG. 3 of the enlarged sectional view taken along the line AA is thinned by about 50% as compared with the flat portion, and the rust preventive power of this portion is reduced. Especially when installed in an environment where the sea salt particles are weak, such as outdoors near the coast, red rust may occur.

Therefore, the flash portion 2 shown in FIG. 3 is removed by sanding or sandblasting to reduce the partial shrinkage rate of the coating film formed on the outer periphery of the flash portion 2 and increase the thickness of the coating film to prevent Although a method of increasing the rust resistance is also conceivable, then not only the number of steps is increased and it is troublesome, but also the production period is lengthened, and there is a possibility that an elevator with a short delivery time may not be able to meet the limited installation date.

Therefore, the object of the present invention is to apply the top coating regardless of whether it is a baking coating or a normal temperature drying coating, as an undercoat or an intermediate coating in the preceding step, and to improve the rust preventive power of the flash portion. To obtain a paint for metal materials.

[0008]

SUMMARY OF THE INVENTION The present invention is a cationic epoxy resin coating for a metal material, which comprises an amino-modified epoxy resin as a main component and is mixed with a color pigment, a solvent, an organic acid and pure water.

[0009]

[Function] Undercoat cationic type epoxy resin paint using titanium oxide as the main pigment, four kinds of oxide yellow (mapico yellow), red iron oxide, carbon black, titanium oxide (99% or more) pigment content in the coating solid ( Resin + pigment)
35% or more, rust preventive pigment (mainly lead silicate) 8 in the pigment content
% Or more to adjust the color and gloss, and not only the plan view of the coated surface but also the shrinkage (meat thinning) that occurs during heat curing in the flash portion 2 shown in FIG. As shown in the coating 6B formed on the outer periphery of the flash portion 2 shown in the figure, a high anticorrosion performance is obtained by the synergistic effect of containing lead silicate.

The intermediate coating applied with this metallic coating as an undercoat is mainly composed of polyester resin as a resin component, and uses melamine resin and epoxy resin,
By using benzoguanamine as the functional material (group) used for the guanamine ring of the melamine resin, good adhesion can be obtained regardless of whether the topcoat paint is a thermosetting type or a room temperature curing type.

Further, the coating material for metal materials of the present invention has a sufficient anticorrosive power even when used as an undercoating coating material by incorporating an epoxy resin. Furthermore, by adjusting the blending ratio of extender pigments, in particular, the blending amount of talc (hydrous magnesium silicate) to form shaped talc, entanglement (adhesion) to abrasives such as vapor compared to flaky talc Can be reduced, and excellent polishability can be obtained.

[0012]

EXAMPLE In this example, the elevator car door shown in FIG. 2 was subjected to pretreatment, undercoating, intermediate coating and topcoating in the following coating steps as test samples. That is,
Pretreatment (degreasing to zinc phosphate treatment) -Undercoating (cationic epoxy resin electrodeposition coating) -Intermediate coating-polishing-Overcoating coating (thermosetting coating ... Melamine resin, acrylic resin, polyester resin, room temperature curing coating ... Nitrified cotton resin, polyurethane resin).

The components (% by weight) of the cationic epoxy resin coating used as the undercoat are shown in Table 1 (Note: parentheses are acceptable).

[0014]

[Table 1]

As shown in FIG. 1, after forming an epoxy resin type cationic electrodeposition coating film 3 on a metal base 1 of an elevator car door, it is heated and dried at a keeping temperature of 165 to 170 ° C. for 20 to 25 minutes. Carried out. The standard dry film thickness was 20 ± 2 μm.

Next, an intermediate coating was applied on this undercoat. Table 2 shows the components (% by weight) of the intermediate coating composition.

[0017]

[Table 2]

After forming the polyester resin / melamine resin / epoxy resin coating film 4 shown in FIG.
Heat drying was carried out at 120 to 125 ° C. for 20 to 25 minutes. The standard thickness of the dry coating film was 20 to 30 μm.

Next, polishing was carried out. Note that this polishing may aim to remove dust (impurities),
In this example, water was used to polish the surface of the elevator car door for smoothness.

After that, a top coat was applied. As thermosetting paints, melanmine resin paints, acrylic resin paints, polyester resin paints, and room temperature curing paints,
A coating film 5 shown in FIG. 1 was formed by using a nitrified cotton resin paint and a polyurethane resin paint by a method suitable for each coating condition.

As the color pigment for the undercoat cationic epoxy resin coating, titanium oxide, which also serves as an extender pigment, is mainly used (99% (% by weight in the coloring pigment)), and rust preventive pigment (lead silicate is mainly used) in the coating. By adding 0.8% and further mixing the pigment content with 40% of the solid content (resin + pigment) of the coating film, the thickness of the coating is reduced by shrinkage that occurs during heat curing in the flash portion as well as in the flat portion (meat thinning). ) Is suppressed to about 70% of the flat surface portion by titanium oxide which also serves as an extender pigment as shown in the outer periphery 6B of the coating film shown in FIG. 1, and the synergistic effect of containing lead silicate has a high anticorrosion property. Got a basket door.

The intermediate coating composition is mainly composed of polyester resin as a resin component, melamine resin and epoxy resin are used, and benzoguanamine is used as a functional material of a guanamine ring of melamine resin, thereby forming a methylol which is usually used. Unlike the melamine resin, it adheres to a nitrified cotton system, and good adhesion was obtained regardless of whether the top coating was a thermosetting type or a room temperature curing type. Moreover, it was confirmed that the epoxy resin was blended and the white pigment zinc white had sufficient rust preventive properties even as an undercoat paint.

Furthermore, the blending ratio of the extender pigment is set to 25.6%, and the main component thereof is talc (hydrous magnesium silicate).
By making the shape of the sphere spherical, the adhesion to the abrasive was reduced and good polishability was obtained as compared with the scaly talc.

Next, a JIS Z2371 neutral salt spray test was conducted on an elevator car door on which a coating film (about 20 μm) was formed with the cationic epoxy resin coating material for metal of the present invention. The results shown in are obtained.

For reference, general epoxy electrodeposition coating performance is also shown.

[0026]

[Table 3]

As shown in Table 3, the coating material for metal materials of the present invention is excellent in the anticorrosion property of the flat surface portion, but the anticorrosion power of the flash portion is particularly remarkable as compared with the conventional epoxy resin electrodeposition coating film. Was excellent. The adhesive strength is JIS K540 even after 2000 hours of the above test.
Even if the basic eye + cellotape test according to 0 is performed, 100
Of all the specimens, no peeling was observed at all, which is extremely good.

Next, after forming the above-mentioned electrodeposition coating film, it is coated with the present intermediate coating composition to form a coating film 20 to 25 μm, and a melamine resin coating film, an acrylic resin coating film, which is a thermosetting coating composition, The initial adhesive force and neutral salt spray test of a polyester resin coating film, a nitrification cotton resin coating film which is a room-temperature drying type coating film, and a polyurethane resin coating film having a thickness of 20 to 30 μm each were performed. Table 4 shows the results of the adhesion test of the sample.

[0029]

[Table 4]

As shown in Table 4, good adhesion is obtained regardless of whether the top coat is a thermosetting coating or a room temperature drying coating.

The present paint was used as an undercoat paint (no electrodeposition coating was performed), and the above various topcoat paints were used to form coating films of 20 to 30 μm each in a neutral salt spray test The results are shown in Table 5.

[0032]

[Table 5]

As shown by the test results in Table 5, the coating material for metal materials of the present invention has a sufficient rust preventive power even when used as an undercoat.

As a guide, the abrasiveness was measured by a JIS K7204 Taber abrasion test (500 g load 1000 times).
The polishing amount was 50 mg or more, and good polishing properties were obtained in actual work.

In the above-mentioned embodiment, the explanation was made when applied to the elevator car door, but it can of course be used as undercoating for distribution boards, control boards, etc., or as a one-time finishing for internal parts. Even if it is coated with mold paint, it has extremely good rust prevention. It can also be used as an intermediate coating for doors and exterior panels of elevators, switchboards, control panels, etc., and exhibits excellent rust prevention power not only for electrical equipment and control devices but also for metal products installed outdoors. be able to.

As described above, in the equipment and device undercoated / intermediately coated with the coating material for a metal material of the present invention, it has an extremely strong rust preventive power, and in particular, the flash portion of the product which has been a problem in the past. The rust preventive power of the corners and corners can be significantly increased, and
The overcoating after the intermediate coating may be a thermosetting resin or a room temperature curing resin, and an automated line can be easily constructed and good adhesion performance can be obtained. Furthermore, when the coating material for a metal material is applied as an intermediate coating material to a product where aesthetics is important, a beautiful coated product can be efficiently obtained because it has excellent abrasiveness.

[0037]

As described above, according to the present invention, since the amino-modified epoxy resin is the main component and the coloring pigment, the solvent, the organic acid and the pure water are mixed to form the cationic epoxy resin coating material for the metal material, It is possible to obtain a coating material for a metal material which can be applied as an undercoat or an intermediate coating regardless of whether the coating material to be overcoated is a baking coating material or a coating material dried at room temperature and which can also improve the rust preventive power of the flash portion.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the action of one embodiment of the coating material for metal materials of the present invention.

2A and 2B are views showing an elevator car door to which the conventional and inventive coating materials for metal materials are applied, in which FIG. 2A is a front view and FIG.
Is a side view and (c) is a rear view.

FIG. 3 is a cross-sectional view showing an example of the action of a conventional coating material for metal materials.

[Explanation of symbols]

 1 ... Metal substrate, 2 ... Burr part.

Claims (1)

[Claims] 1. A main component is an amino-modified epoxy resin,
A paint for metal materials, which is a mixture of a color pigment, a solvent, an organic acid and pure water.