JPS6259035A - Composite steel plate having excellent corrosion resistance and workability and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a composite steel plate with excellent corrosion resistance and workability, and a method for manufacturing the same.

[Background of the Invention] Composite steel sheets are used in a wide range of applications, including automobile parts, electrical and mechanical parts, various covers, building materials, and structures.

On the other hand, for applications requiring corrosion resistance, a Zn-based plating layer 2 is provided on the surface as shown in FIG. 8, and a phosphate coating I! A surface-treated steel sheet having a surface-treated steel sheet having a hardness of 100 mm is used as an original sheet.

Conventionally, such composite steel plates have been manufactured by steps as shown in FIGS. 6 and 7. Namely.

-1--F Umayahara Komon is crystal bud 1 rin I scold rh fu - 1 first supplied 0 Next, heat to about 130°C.

After holding the original plate at that temperature for a certain period of time, temporary bonding is performed by pressing the original plate with a pressure roll, etc. After temporary bonding, it is heated to about 150°C and held at that temperature for a certain period of time to ripen the thermoplastic resin. After zero-water bonding, in which main bonding is performed by performing pressure bonding again, the resin is cooled to a temperature below the melting temperature of the thermoplastic resin.

By the way, many composite steel plates are used after being press-formed, but because composite steel plates have a resin in the middle layer whose deformation behavior is completely different from that of steel plates, they have poor press formability compared to single steel plates. is inferior. Therefore, the press formability of composite steel sheets is a very important property. However, when a composite steel plate is produced by a conventional manufacturing method using a phosphate-treated Zn-plated steel plate as an original plate, the press formability described above becomes extremely poor compared to a composite steel plate using a cold-rolled steel plate as an original plate.

In addition, composite steel plates are generally coated with paint after pressing.
Paint baking is performed, but composite steel plates manufactured by conventional methods also have the problem that the adhesion strength of the living room after painting baking is reduced.

The cause of the decrease in press formability is thought to be as follows.

In general, the surface composition of phosphate-treated Zn-plated steel sheets is Hovite (HOP E I TE) No.
(PO) 4H20), and depending on the heat history during the bonding process (generally 150°C or higher), it can vary from 4-wood salt to 2-hydrate salt (
Z n (P O) 2 H20) and dehydrated as crystal water, it is thought that this crystal water causes bubbles to be generated in the resin part, deteriorating adhesive strength and reducing press formability. Note that if it is dehydrated to anhydrous salt, it will change color and become unusable.

The present invention was made based on this knowledge in order to solve the above problems.

[Summary of the Invention] The first invention according to the present application is a surface treatment having a Zn-based plating layer on opposing surfaces of a steel plate or both sides of the steel plate, and further having a phosphate treatment film on the outside of the Zn-based plating layer. A composite laminated steel plate formed by thermocompression bonding with a thermoplastic resin interposed between steel plates, the composite steel plate having excellent corrosion resistance and workability, characterized in that the phosphate film is a phosphate film of 2-wood salt. It is.

A second invention according to the present application has a Zn-based plating layer on opposing surfaces of steel plates or both sides of the steel plate, and further has a thermoplastic resin interposed between the surface-treated steel plates having a phosphate treatment film to bond them by thermocompression. A method for manufacturing a composite laminated steel plate, which is characterized by preheating the surface-treated steel plate at a temperature equal to or higher than the thermo-compression bonding process temperature before the process of thermo-compression bonding the surface-treated steel plate and the resin. This is a method for manufacturing composite steel sheets with excellent properties.

Note that the resin is, for example, polyolefin resin (polypropylene, polyethylene), i! ! Vinyl chloride, modified vinyl acetate, nylon, polyvinyl butyral, acrylic resin, thermoplastic polyester, adhesive polyethylene, or modified products or composites thereof may be used.

Further, the composite steel plate to which the present invention is applied may be one in which the proportion of the steel plate is large, or a lightweight composite steel plate for the purpose of weight reduction, in which the intermediate resin layer is thicker than the steel plate.

Regardless of the type of steel plate, there is a Z mark on the opposing surface or both sides of the steel plate.
Any surface-treated steel sheet may be used as long as it has an n-based plating layer and further has a phosphate treatment film.

Any means for interposing the thermoplastic resin may be used.

For example, a film-like resin may be inserted between the surface-treated steel plates.

As a means for thermocompression bonding, for example, a hot press, a hoe, a trawl, etc. may be used.

The thermocompression bonding temperature is generally performed at a temperature higher than the melting temperature of the resin.

In the present invention, before the process of thermocompression bonding the surface treated steel plate and the resin, the surface treated steel plate is preheated at a temperature equal to or higher than the temperature of the thermocompression bonding process.

The preheating time varies depending on the preheating temperature, but for example, 1
At 50°C, it is sufficient to heat 2 to 3 molecules.

In addition, when applying paint and baking the paint after molding, if the paint baking temperature is higher than the pressure bonding temperature, preheating at a temperature higher than the paint baking temperature not only improves the adhesive strength before molding, but also improves the adhesive strength before molding. , the adhesive strength after paint baking is also improved.

In addition, if preheating is performed before the thermocompression bonding process, after preheating, it may be cooled to room temperature and then proceed to the thermocompression bonding process, or it may be directly transferred to the thermocompression bonding process without cooling to room temperature. good.

Further, the upper limit of the preheating temperature is preferably 250 to 300°C; if this temperature is exceeded, the surface of the steel plate will change color.

[Embodiments of the invention] The present invention will be explained in detail below.

(First Example) 5ECE-IO having a phosphorus coating as a surface-treated steel sheet
, 7tX 914wX 1829L is used, and the film thickness is as a thermoplastic resin? OyL thermoplastic damping resin was used.

Figure 1 and 2 are made using the above surface treated steel plate and resin.
A composite steel plate was created by the process shown in the figure. That is, first, a surface-treated steel sheet was heated to a temperature exceeding 150°C (T1), held at that temperature for 3 minutes, and then cooled to room temperature.
Next, a film made of thermoplastic resin is supplied between the surface-treated steel plates, and then heated to 130°C by hot roll passing.
Temporary bonding is performed by thermocompression bonding (step in Figure 2 (A)). After temporary bonding, heat to approximately 150°C (T2), and heat to 150°C for approximately 1
The thermoplastic resin was aged by holding for 0 minutes, and the main adhesion was performed by pressing again with a pressure roll etc. (step of Fig. 2 CB)), and then the thermoplastic resin was cooled to below the melting temperature of the thermoplastic resin (step 2). (Step in Figure 2 (C)).

The T-peel strength of the composite steel sheet manufactured as described above was tested and found to be 19.5 kgf/25 mm, which was 19.5 kgf/25 mm.
A higher peel strength was exhibited than in case L).

Also, the melting temperature! Composite steel plates were manufactured using the same process and conditions as above, except that the temperature was changed to 60°C, 180°C, and 200°C, and the peel strength was examined, and all showed a high peel strength of 20 kgF/25 mm. The results are shown graphically in Figure 4. For comparison, Figure 4 shows the case of preheating at 150°C (temperature higher than the pressure bonding process) or lower and the case of cold rolled steel plate being heated to T8. be.

When the composite steel sheet manufactured based on this example was examined by X-ray analysis, the phosphate film was found to be a dihydrate phosphate film.

(Second Example) In the second example, the same surface-treated steel plate and resin as in the first example were used.

In this example, as shown in FIG. 3, after preheating, the plate was cooled to 130° C., which is the board bonding temperature, and then the steps of temporary bonding, main bonding, and cooling were performed in the same manner as in the first example.

When the peel strength of the composite steel plate manufactured according to this example was examined, it showed high peel strength as in the first example.

Moreover, the phosphate film was a 2-Kiba phosphate film.

(Third Example) A composite steel plate was manufactured using the same surface-treated steel plate and resin as in the first example. In just one example, we set the p-thermal temperature to 15
The temperatures were 0°C and 200°C. The effect on peel strength was investigated when the composite steel sheets produced in this manner were reheated to various temperatures and subjected to paint baking. The results are shown in FIG.

As shown in Figure 5, when the preheating temperature is 150°C,
It exhibits high peel strength until the reheating temperature approaches 150°C, but as the temperature approaches 150°C, the peel strength rapidly decreases.

Also, if the preheating temperature is 200℃, the reheating temperature is 20℃.
It exhibits high peel strength up to 0°C, but as the temperature approaches 200°C, the peel strength decreases rapidly. Therefore, it can be seen that the peel strength does not decrease if the preheating temperature is lower than the reheating temperature (paint baking temperature).

[Effects of the Invention] According to the first invention of the present application, adhesive strength was significantly improved. It is possible to produce a composite steel sheet that has much higher adhesive strength than a cold-rolled original sheet and has good press formability.

According to the second invention of the present application, the adhesive strength is significantly a+
It was good. It is possible to produce a composite steel sheet that has much higher adhesive strength than a cold-rolled original sheet and has good press formability.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing an embodiment of the second invention according to the present application. FIG. 2 is a graph showing the heating process in the first embodiment according to the present application. Figure 3 is the second diagram related to this application.
It is a graph showing a heating process in a second example of the invention. FIG. 4 is a graph showing the relationship between preheating temperature and peel strength. FIG. 5 is a graph showing the relationship between reheating temperature and peel strength of composite steel plates manufactured at preheating temperatures of 150°C and 200°C. FIG. 6 is a process diagram showing the manufacturing process in a conventional example. FIG. 7 is a graph showing the heating process in the conventional example. FIG. 8 is a sectional view showing the structure of the composite steel plate. l-ψ phosphate film, 2.-Zn based make/ki layer. 3. Steel plate, 4. Resin, 5. Surface treated steel plate, 6.
Composite steel plate. Figure 1 → Time Figure 3 → @ 65W Figure 7 Time □

Claims (1)

[Scope of Claims] 1 A thermoplastic resin is interposed between surface-treated steel sheets having a Zn-based plating layer on opposing surfaces of the steel sheet or both surfaces of the steel sheet, and further having a phosphate treatment film on the outside of the Zn-based plating layer. A composite laminated steel sheet formed by thermocompression bonding, characterized in that the phosphate film is a dihydrate phosphate film, and has excellent corrosion resistance and workability. 2. In a method for manufacturing a composite laminated steel plate, which has a Zn-based plating layer on the opposing surfaces of the steel plates or both sides of the steel plate, and further includes a thermoplastic resin interposed between the surface-treated steel plates having a phosphate treatment film and bonded by thermocompression. A method for producing a composite steel sheet with excellent corrosion resistance and workability, characterized by preheating the surface-treated steel sheet at a temperature higher than the temperature of the thermo-compression bonding process before the process of thermo-compression bonding the surface-treated steel sheet and the resin. . 3. In the case where a paint is applied after molding and the paint is baked, and the paint baking temperature is higher than the compression bonding temperature, the preheating temperature is performed at a temperature higher than the paint baking temperature. An excellent method for manufacturing composite steel sheets.