JPH05200357A - Coated body of hot-dipping zinc-plated product - Google Patents

Abstract

PURPOSE:To improve adhesiveness, salt water resistance, and water resistance of a resin coating film of a coated body of hot-dipping zinc-plated product and to make the production easy by using a two-liquid reactive epoxy resin coating material containing an epoxy silane coupling agent. CONSTITUTION:A resin coating film 2 consisting of a two-liquid reactive epoxy resin coating material containing an epoxy silane coupling agent is formed on the surface of a body of hot-dipping zinc-plated metal body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coated body of a hot-dip galvanized product which is excellent not only in corrosion resistance but also in salt water resistance and water resistance.

[0002]

2. Description of the Related Art A metal body having a surface of hot-dip galvanized steel or steel products has excellent corrosion resistance. However, since zinc has a strong chemical activity, it has a drawback that it causes a chemical reaction with oxygen, carbon dioxide, water, and other corrosive factors in the air to cause a chemical reaction with them, resulting in reduced corrosion resistance. .. For this reason, recently, in order to effectively perform long-term corrosion protection, a coated body has been used in which a resin coating film is further formed on the surface that has been subjected to hot dip galvanization to prevent contact with corrosive factors. However, since zinc has poor adhesion to the resin, peeling of the resin coating film occurred in the coated body in which the resin coating film was directly formed on the surface of the hot dip galvanizing.

As a coated body for solving the above problems, conventionally, a surface of a galvanized metal body is physically or chemically roughened to improve adhesion to a resin coating film. , On the surface of the galvanized metal body,
In some cases, a room temperature dry type or high temperature baking type primer is applied in advance to form a primer coating film, and then a resin coating film is formed on the surface.

[0004]

However, in such a conventional coated body, the former is that the resin coating film is simply attached to the surface of the roughened zinc plating by the anchoring effect. It is not completely adhered to the galvanized surface, but the adhesive strength of the resin coating decreases over the long term due to differences in the thermal expansion coefficient between the resin coating and the metal body, deterioration of the resin coating, etc. Then, peeling occurred.

On the other hand, in the latter case, in the case of a coated body using a room temperature dry type primer, the primer drying time is long in the manufacturing process and the primer coating film is formed by heating in the resin coating film forming process. There is a problem of heat deterioration of the, in addition, in the case of a coated body using a high temperature baking type primer, there is a problem that the equipment is expensive, etc., because a drying oven is required to form the primer coating film, No matter which primer was used, the manufacturing process of the coated body was complicated.

In a coated body using a room temperature dry type primer, the drying time of the primer is shortened,
As for a coated body intended to solve the above-mentioned problems, for example, as described in Japanese Patent Publication No. 59-10276, a quick-drying method using an alcohol solution of a vinyl-based synthetic resin as a vehicle, which contains phosphoric acid and a chromate pigment. There is also proposed one using a wash primer which is a room temperature dry type. However, the coated body using the primer is easily affected by the environmental humidity during coating due to the non-uniformity of water content necessary for the neutralization reaction between phosphoric acid in the curing agent and zinc tetroxycyclomate in the main agent. Therefore, the primer coating film varies, and the polyvinyl butyrate resin, which is the vehicle of this primer, is a resin that is extremely weak against alkali. Was deteriorated and caused peeling.

The present invention solves the above problems and provides a coated body of a hot dip galvanized product which is excellent in adhesiveness of a resin coating film, salt water resistance and water resistance and is easy to manufacture.

[0008]

In order to achieve the above object, the present invention has the following constitution. That is,
The coated body of the hot-dip galvanized product according to the present invention has a resin coating film made of a two-component reactive epoxy resin coating material containing an epoxy-based silane coupling agent formed on the surface of a hot-dipped galvanized metal body. It is characterized by becoming.

The structure of the present invention will be described in more detail below. The material of the metal body of the present invention is preferably a steel material or a steel product, but is not particularly limited as long as it is a metal body that has been subjected to normal hot dip galvanization. The shape is a plate,
The pipe, the rod, or a shape in which they are appropriately combined is used, and the shape is not limited.

The resin coating film formed on the surface of the metal body is formed of a two-component reactive epoxy resin coating material containing an epoxy silane coupling agent. The epoxy-based silane coupling agent is one in which hydrogen of silane is replaced with functional groups of epoxy and alkoxy, and γ-glycidoxypropyltrimethoxysilane is preferably used, but it has an epoxy group and an alkoxy group. If so, the type is not particularly limited.

The main component contained in the two-component reactive epoxy resin coating material is an epoxy resin varnish, a pigment, an additive, a solvent, etc., and the curing agent is the main component epoxy resin and the epoxy group of the epoxy-based silane coupling agent. It is to be reacted with, and amines such as diethylenetriamine, triethylenetetramine, metaxylylenediamine, dimethylaminomethylphenol and polyamide resins such as polyamidoamine are generally used, but the kind is not particularly limited. ..

A method of manufacturing a coated body of a hot-dip galvanized product according to the present invention having the above-mentioned structure will be described. First, a galvanized metal body is prepared. The surface of the metal body does not need to be pretreated in particular, but the surface may be subjected to conventional pretreatment in order to further improve the adhesion to the resin coating film. As the pretreatment, the surface of the metal body is physically roughened by sandblasting, shot blasting, desk sander, wire sander, etc., and at the same time, dirt and oil are removed, or a chemical method such as acid or alkali is used for dirt and corrosion. A phosphate coating such as phosphate may be formed by removing the product or by chemical conversion treatment.

Next, a resin coating film may be formed on the surface of the metal body. The method for forming the resin coating film is such that the epoxy resin varnish, the pigment, the additive, and the epoxy-based silane coupling agent are mixed in the main component consisting of a solvent by a ball mill, a sand mill, etc. to uniformly disperse the mixture, and then the curing agent A two-component reactive epoxy resin paint is prepared by mixing as a vehicle, and the paint is formed by applying the paint to the surface of the metal body by an appropriate method such as spray coating, brush coating, roller coating, etc. and curing it. To be done. It is preferable that the mixing ratio of the epoxy silane coupling agent is 1% by weight and the film thickness of the resin coating film is about 80 μ, but the present invention is not limited to these.

[0014]

The resin coating film of the present invention comprises a two-component reactive epoxy resin coating material containing an epoxy-based silane coupling agent, and the epoxy-based silane coupling agent has functional groups of epoxy and alkoxy. Epoxy resin is an epoxy-based silane coupling agent because it reacts with the epoxy resin or curing agent of the main agent to bond with it, and one alkoxy group is replaced by a hydroxyl group by hydrolysis and then hydrogen bonds with the surface of the hot-dip galvanized layer. It is chemically bonded to the surface of the hot-dip galvanized via and is firmly adhered.

Further, since the epoxy resin forming the resin coating film is excellent in water resistance, the amount of water permeating the coating film and reaching the galvanized surface is small, and the epoxy resin is also strong against alkali. Even if an alkali is generated on the galvanized surface by the permeated water, the alkali does not deteriorate the coating film.

[0016]

EXAMPLES The present invention will be specifically described below based on examples. First, as an example of the present invention, as shown in FIG. 1, 1% by weight of an epoxy-based silane coupling agent was added to a main component composed of an epoxy resin varnish, a pigment, an additive, a solvent, etc.
A two-component reactive epoxy resin paint is mixed with a curing agent, and the paint is applied to the surface of a metal body 1 made of hot-dip galvanized steel sheet that has been degreased with xylene to form a resin coating film 2 of 80 μm. Got a painted body.

In addition, as a comparative example, a two-component reactive epoxy resin coating material was prepared by mixing the same main agent and curing agent as in the above-mentioned examples without using an epoxy silane coupling agent.
The coating is applied to the surface of a metal body similar to the above example,
A coated body on which a 80 μm resin coating film was formed was obtained.

Next, in order to examine the adhesion of the coated body according to the present invention, the coated bodies of the above-mentioned Examples and Comparative Examples were subjected to a cross-cut test and a salt spray test specified in JIS-K-5400. The results are shown in Table 1.

In the cross-cut test, a sharp knife was used to draw a cut penetrating the resin coating film to reach the hot dip galvanized surface, and 11 scoring lines were formed on the coated body at intervals of 1 mm to intersect each other. This is a method of making 100 squares of 1 mm x 1 mm, examining the extent of the spread of scratches from the cut, and evaluating the adhesion between the coating film and the metal body.

In the salt spray test, a sharp knife is used to draw a cut penetrating the resin coating film to reach the hot dip galvanized surface, and two diagonal lines intersecting the coated body are formed to obtain a test piece. This is a method in which a test piece is placed in a test room where a mist of salt water is generated, the size of blisters formed on the coating film is examined, and the adhesion between the coating film and the metal body is evaluated.

[0021]

[Table 1]

From the results of the cross-cut test, the examples were superior in adhesiveness to the comparative examples, and neither spreading of scratches nor peeling from the cuts was observed. From the results of the salt spray test, it was found that the size of the coating film of the example was smaller than that of the comparative example and the salt water resistance and the water resistance were excellent.

[0023]

As described above, the coated body of the hot-dip galvanized product according to the present invention has the resin coating film formed on the surface of the metal body which has been subjected to the hot-dip galvanization. Consisting of a two-component reactive epoxy resin coating material containing a silane coupling agent, the epoxy group of the epoxy silane coupling agent reacts and bonds with the epoxy resin or curing agent of the main component, and the alkoxy group becomes a hydroxyl group by hydrolysis. After the replacement, hydrogen bonding is performed with the surface of the hot dip galvanized layer, so that the resin coating film is chemically bonded to the surface of the hot dip galvanized layer by the epoxy-based silane coupling agent so as to be firmly adhered to the resin coating layer. Since the film is made of epoxy resin, it is a coated body with excellent salt water resistance and water resistance.

Further, in the coated body of the present invention, since the resin coating film is directly formed on the surface of the galvanized metal body, it is not necessary to form a primer coating film or the like as a previous step. When manufacturing the coated body of the invention, the manufacturing facility is simple and the manufacturing time is shortened.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a coated body according to the present invention.

[Explanation of symbols]

 1 Metal body 2 Resin coating film

Claims (1)

[Claims] 1. A coated body of a hot-dip galvanized product in which a resin coating film made of a two-component reactive epoxy resin paint containing an epoxy-based silane coupling agent is formed on the surface of a hot-dip galvanized metal body. ..