JPH01123672A - Organic coating method for metallic material - Google Patents

Abstract

PURPOSE:To eliminate the need for unnecessary heating stages and to reduce cost by subjecting the surface of a heated metallic material to multilayered coating with many kinds of thermoplastic resins having different characteristics. CONSTITUTION:The metallic material (for example, steel structure) is heated up to the baking start temp. of a 1st thermoplastic synthetic resin (characteristic satd. polyester). This metallic material is immersed into a fluidized bed coating tank to weld the 1st thermoplastic synthetic resin on the surface of the metallic material so that the surface is coated with this resin. The metallic material is then air cooled in the atm. up to the baking start temp. of the 2nd thermoplastic synthetic resin (for example, polyethylene). The metallic material is immersed into a 2nd fluidized bed coating tank to weld the 2nd thermoplastic synthetic resin having a low m.p. on the surface of the 1st thermoplastic synthetic resin so that the surface is coated with said resin. The surface of the metallic material is coated in multiple layers with the thermoplastic synthetic resins having the different characteristics in such a manner, by which the durability, impact resistance and chemical stability of the metallic material are enhanced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for organic coating of metal materials, and more particularly, to a method for coating the surface of a metal material with two or more organic materials having different properties. It is.

[Prior Art 1] Many types of resins are used for coating organic materials for the purpose of preventing corrosion of metal materials. However, depending on the usage environment of the coated metal material, it is necessary to satisfy various conditions, and coating with one type of resin often does not fully satisfy all the usage conditions.

For this reason, a method has been considered in which two or multiple layers of Z fffi or higher organic materials having different properties are coated to achieve the desired performance. In this method, a second coating layer is bonded with an adhesive onto a first coating layer coated on a metal material, a third coating layer is bonded to the second coating layer, or a third coating layer is bonded to the second coating layer, or a third coating layer is bonded to the second coating layer. The first coated layer is reheated to rejuvenate the second coated layer, the second coated layer is further heated, and the third coated layer is heated again.
A method of fusing the coating layer was used.

[Problem to be solved by the invention 1 However, in the conventional method, the metal material
Since separate steps such as heating are required to provide the above coating layer, the third coating layer, etc., the number of steps increases accordingly, resulting in an increase in cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems and provide an inexpensive organic coating method that can coat metal materials in multiple layers with two or more types of organic materials, requires fewer steps, and is inexpensive. .

[Means for Solving the Problems] In order to achieve the above object, the present invention includes the steps of: heating a metal material; coating the surface of the heated metal material with a first thermoplastic resin; The method is characterized by including a step of coating the surface of the first thermoplastic resin layer with a second thermoplastic resin having a lower melting point than the first thermoplastic resin.

[Function] According to the present invention, the residual heat immediately after coating the metal material with the first thermoplastic resin having a high melting point coats the metal material with the second thermoplastic resin having a low melting point, and if necessary, the same process is continued. By coating the third thermoplastic resin or the like with a melting point lower than that of the second thermoplastic resin using the method described above, thermal energy is saved, unlike the conventional method of coating a metal material with an organic material. Further, according to the present invention, since it is possible to perform multilayer coating using many types of thermoplastic resins having different properties, multilayer coating that takes advantage of the characteristics of each resin can be performed at low cost.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Figure 1 is a schematic process diagram showing an embodiment of the organic coating method for metal materials according to the present invention. In this example, a method of coating a steel structure with two layers of saturated polyester and polyethylene as thermoplastic resins will be described.

First, in the first step, the steel structure to be treated is subjected to pickling, water washing, and other necessary pretreatments in the usual manner.

In a second step, the pretreated steel structure is heated to 350°C, which is the starting temperature for baking saturated polyester in a heating furnace.
heated to ℃. After reaching a predetermined temperature, in the third step, the steel structure is immersed for about 1 minute in a fluidized immersion bath filled with high melting point saturated polyester powder to fuse the saturated polyester resin. After taking it out from the immersion tank, in the fourth step, it is air cooled in the atmosphere for 1 to 2 minutes until it reaches a temperature of about 200° C., which is the starting temperature for baking polystyrene. After air cooling in the atmosphere, in the fifth step, the steel structure is immersed for 2 to 3 minutes in a second fluidized immersion tank filled with low melting point polyethylene powder to fuse the polyethylene as the second tank. .

Thereafter, the steel structure to which the thermoplastic resin is fused is air-cooled.

In the third or fifth step, instead of immersing and fusing the saturated polyvarnish chill or polyethylene in a fluidized dipping tank, saturated polyester or polyethylene powder may be sprayed with an air gun or the like.

According to the method described above, in the process of baking the first layer of powder onto the steel structure made of the metal material to be treated, the most time-consuming process is the setting of the object to be treated. This is a heating process.

In embodiments of the present invention, the extra time required to coat the second layer consists of fusing the first resin, saturated polyester resin, and then soaking the second resin, polyethylene. It will take 3-5 minutes to complete. Therefore, not only is the heating time required to be less than that of conventional methods, but additional steps for heating are not required, and the cost increase is minimal.

Fig. 2 is a process schematic diagram showing a second embodiment of the present invention. In this example, a method of coating a steel wire with two layers of saturated polyester and polyethylene will be described.

First, as a first step, the steel wire 2 to be subjected to anticorrosion treatment taken out from the steel wire drum 1 is pretreated by a conventional method such as pickling and water washing. After the pretreatment, as a second step, the steel wire 2 is heated in a heating furnace to about 350° C., which is the starting temperature for baking the saturated polyester with a high melting point, which is the resin of the first layer. After heating, as a third step, the steel wire is passed through a fluidized dipping bath for a time period depending on the required film thickness. Thereafter, as a fourth step, the steel wire is passed through the atmosphere until the baking temperature of the low melting point polyethylene, which is the resin of the second layer, reaches about 200° C., which is the starting temperature. After passing through the atmosphere, as a fifth step, the line is passed through a polyethylene fluidized immersion bath for a time corresponding to the required polyethylene film thickness. Thereafter, the steel wire is wound onto the drum 3, completing the entire process.

In Examples 1 and 2, by using a saturated polyester with a high melting point in the first layer, excellent adhesion to the metal material is obtained and coating strength is also increased. Furthermore, by using polyethylene with a low melting point in the second layer, it is possible to protect against the insufficient impact resistance and alkali resistance of the saturated polyester in the first layer.

The metal material that can be coated is not limited to steel, and the organic coating layer is not limited to the examples described above. Also, the number of coating layers can be changed to 3 as necessary.
It can be a layer or more.

[Effects of the Invention] As explained above, according to the present invention, after heating a metal material, a thermoplastic resin having a high melting point is subjected to M treatment, and then a thermoplastic resin having a lower melting point than the thermoplastic resin is sequentially coated. By processing and coating in multiple layers with many types of thermoplastic resins with different properties, no extra heating process is required and costs are reduced.

Furthermore, according to the present invention, by forming the metal material coating into a multilayer structure, for example, it has durability against mechanical external force when driving an anchor into the soil, impact resistance during handling, and chemical resistance in alkaline soil. It is extremely effective in fields where stability is required.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of a first embodiment of the present invention, and FIG. 2 is a process diagram of a second embodiment of the present invention. 1... Steel wire drum, 2... Steel wire, 3... Drum.

Claims (1)

[Claims] heating a metal material; coating the surface of the heated metal material with a first thermoplastic resin; and coating the surface of the first thermoplastic resin layer with a melting point higher than that of the first thermoplastic resin. 1. An organic coating method for a metal material, comprising the step of coating a second thermoplastic resin with a low thermoplastic resin.