JP5251247B2 - Manufacturing equipment of surface-treated steel sheet and manufacturing method thereof - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a production facility for surface-treated steel sheets used in the fields of automobiles, home appliances, building materials, containers, and the like, and particularly relates to a production facility for surface-treated steel sheets that can change the coating thickness at any position on the surface of the steel sheet and a method for producing the same. .

  Conventionally, as a steel sheet used in the fields of automobiles, home appliances, building materials, containers, etc., in order to improve corrosion resistance (white rust resistance and red rust resistance), inorganic compounds, organic compounds, organic polymer materials, or these are used. There has been proposed a surface-treated steel sheet in which a paint containing a composite material is applied to the surface by a method such as roll coater, dipping or electrolytic treatment to form a coating film. For example, Patent Document 1 and Patent Document 2 disclose a surface-treated steel sheet in which a coating film is formed by applying a paint containing an organic resin and a phosphoric acid compound, and a method for manufacturing the surface-treated steel sheet. Patent Documents 3 and 4 disclose surface-treated steel sheets in which a coating film containing an organic resin and a silane coupling agent, and further a thiocarbonyl compound, a phosphate compound, and a vanadium compound is formed. Further, Patent Document 5 discloses a surface-treated steel sheet having a two-layer coating film formed of a composite oxide layer containing a tetravalent vanadium compound and an organic resin layer containing a self-repairing phosphate. ing.

On the other hand, these surface-treated steel sheets are required to have excellent spot weldability, seam weldability, or electromagnetic wave shielding properties in addition to corrosion resistance.
JP 2000-34578 JP 2000-248380 A JP 2000-319787 A JP 2000-248384 A JP 2005-154811 A

  However, in the surface-treated steel sheets described in Patent Documents 1 to 5, from the viewpoint of corrosion resistance, a paint containing an organic resin is applied by a roll coater or dipping to form a relatively thick coating film uniformly on the steel sheet surface. For this reason, the conductivity is lowered, and spot welding and seam welding become difficult, and problems such as poor electromagnetic shielding properties arise. On the other hand, if the thickness of the coating film is reduced, the conductivity can be improved, but it is difficult to ensure the corrosion resistance. Therefore, there is a need for a means that can change the thickness of the coating only on the necessary parts such as weldability and electromagnetic shielding properties, but in the current roll coater and immersion coating, over a relatively long distance in the longitudinal direction of the steel sheet. Although it is possible to change the coating thickness by controlling the roll peripheral speed or the like, it is difficult to change the coating thickness at an arbitrary position on the surface of the steel sheet.

  An object of this invention is to provide the manufacturing equipment of the surface treatment steel plate which can change coating-film thickness in the arbitrary positions of the steel plate surface, and its manufacturing method.

As a result of intensive studies on a method for producing a surface-treated steel sheet that can change the coating thickness at an arbitrary position on the surface of the steel sheet, the present inventors have used a single inkjet device equipped with a plurality of heads, arranged along the head width direction of the steel sheet, the paint, as droplets from a plurality of heads, by changing the droplet volume in certain head, ejected so, may be formed a coating film by land on the steel sheet surface I found out.

The present invention uses a manufacturing equipment for a surface-treated steel sheet that has one ink jet device provided with a plurality of heads, and the plurality of heads provided in the ink jet device are arranged along the width direction of the steel plate. , paint, as droplets from a plurality of heads which are provided in the inkjet device, by changing the droplet volume in certain head, ejected so, any different thicknesses coating at the location of the landing is allowed in the surface of the steel sheet steel surface The manufacturing method of the surface treatment steel plate which comprises corrosion resistance and electroconductivity which forms is provided.

  In the manufacturing method of this invention, after forming a coating film, it can also heat-process a coating film.

  As the paint, for example, a paint containing an organic resin and further blended with at least one selected from a curing agent, a lubricant, a rust preventive pigment and a color pigment can be given.

  According to the present invention, a surface-treated steel sheet having a coating film thickness changed at an arbitrary position on the steel sheet surface can be produced. For this reason, it is possible to use a surface-treated steel sheet to which conductivity is imparted by reducing the thickness of the coating film only at necessary portions. Therefore, not only spot welding and seam welding are possible, but also the electromagnetic wave shielding property can be improved without substantially reducing the corrosion resistance of the product using the surface-treated steel sheet.

  An ink jet printer is a printing machine that ejects ink as fine droplets from a head having a large number of ejection openings (nozzles) by a piezo method or a thermal method and directly lands on a print medium such as paper. In the present invention, this inkjet printer technology is applied to a surface-treated steel sheet with a coating film formed mainly for the purpose of corrosion resistance, and it is possible to change the coating thickness only at the necessary site, which was impossible in the past. For example, it is characterized in that welding or electromagnetic wave shielding is made possible by imparting conductivity to a specific part.

  FIG. 1 shows an example of equipment for producing the surface-treated steel sheet of the present invention. In this example, one inkjet device (not shown) is installed, and a plurality of heads 11 provided in the inkjet device are arranged vertically above the steel plate surface along the width direction of the steel plate. Yes. At this time, the plurality of heads 11 provided in the ink jet apparatus showed the case of six heads 11a to f in FIG. 2, but it is possible to arrange them along the width direction of the steel plate 10 so that the coating thickness It is preferable in controlling. 1 and 2 show a case where a plurality of heads are arranged vertically above a substantially horizontal steel plate surface, but when the steel plate surface is substantially parallel to the vertical direction, What is necessary is just to arrange | position each head in the position where the droplet of the coating material discharged from a head lands on the steel plate surface, and can form a coating film.

  Although the same thing as a commercially available ink jet printer can be applied to the ink jet device used in the production facility of the present invention, since it is intended for coating film formation on a large area such as a surface-treated steel plate, depending on the size of the steel plate It is preferable that the capacity of the coating material supply system, the size and number of heads, and the like can be changed as appropriate.

In FIG. 1, now, when the paint 21 is discharged as droplets from the head 11 composed of the six heads 11a to 11f arranged as shown in FIG. particular head of the head 11A～f, for example the head 11e and other heads 11a-d, when changing the droplet amount ejected from f, the site has passed through the head 11e and other heads 11a-d, and f It is possible to form a coating film having a different thickness at the part that has passed. In this way, if the head for changing the droplet amount is appropriately selected over time, coating films having different thicknesses can be formed at arbitrary positions on the surface of the steel sheet. Furthermore, changing the droplet volume itself or over time for each head, it becomes possible to form a coating film having an arbitrary thickness at any position of the steel sheet surface. At this time, in order to change the droplet amount of the head, the number of nozzles used in each head and the interval (frequency) of droplets discharged from the nozzles may be changed.

  By providing a heat treatment device in combination with the ink jet device, the coating film can be subjected to heat treatment after the coating film is formed.

  Also, as shown in FIG. 3, if the direction of travel of the steel plate 10 is changed using rolls 31, 32, etc., and the heat treatment device 40 is disposed downstream of the head 11 and the position of the head, the front and back surfaces of the steel plate 10 are provided. A coating film can be formed and further heat treatment can be performed.

  The present invention can be applied to, for example, a surface-treated steel sheet that contains an organic resin, and further has a coating film formed using a paint that contains at least one selected from a curing agent, a lubricant, a rust preventive pigment, and a color pigment. . In such a surface-treated steel sheet, the coating thickness is usually 1 to 20 μm. However, in the site where welding is performed or where electromagnetic shielding is necessary, the coating thickness is reduced to 1 μm or less by the method of the present invention. You can have it.

As shown in Fig. 2, six heads 11a-f are arranged in the width direction of the steel sheet on an electrogalvanized steel sheet with a thickness of 0.7mm and a width of 200mm (plating adhesion amount per side: 20g / m ² ). Using an inkjet apparatus equipped with a head, epoxy resin [Epicoat (registered trademark) 1007 manufactured by Japan Epoxy Resin Co., Ltd.] and tolylene diisocyanate [Coronate (registered trademark) 2507 manufactured by Japan Polyurethane Industry Co., Ltd.] as a curing agent Liquid droplets of paint containing at a mass ratio of 70/30 are ejected by changing the amount of liquid droplets with the heads 11a to d, f and the head 11e, landed on the steel plate surface, and then heated to 140 ° C in a high frequency induction heating furnace. Then, surface-treated steel plates No. 1 to 7 having a coating film having a thick film portion and a thin film portion as shown in FIG. 4 were produced. At this time, the tips of the heads 11a to f are at a height of 2 mm from the steel plate surface, and the moving speed of the steel plate is 10 m / min. Each of the heads 11a to 11f is of a type that forms droplets by a piezo method, and each of 512 nozzles is arranged in a width of 36 mm with a distance between nozzles of 70.5 μm. Also, as shown in Table 1, the amount of paint droplets discharged from the nozzles of the heads 11a to d, f was 42 pL (picoliter), the frequency was changed to 0.5 to 9.5 kHz, and the thickness was 1.25 to 20 μm. Thick film part and thin film part (No.1 ~ 4) whose thickness is 0μm without discharging paint from nozzle of head 11e or droplet amount of paint discharged from nozzle of head 11e is 42pL, frequency is 0.14 A coating film comprising a thin film portion (No. 5 to 7) having a thickness of 0.3 to 0.9 μm was changed to ˜0.45 kHz.

  In addition, after applying the same paint as described above with a conventional roll coater, it was heated to 140 ° C. in a high-frequency induction heating furnace, and as shown in Table 2, a surface-treated steel sheet No. having a coating film having a thickness of 0.3 to 20 μm was formed. .8-14 were produced.

  And about the surface treatment steel plate No.8-14 produced by the thick film part and thin film part of the surface treatment steel plate No.1-7 produced by the method of the present invention, and the conventional roll coater, the coating thickness, white rust resistance The properties and conductivity were investigated by the following methods.

  Film thickness: measured by SEM observation of the film cross section.

White rust resistance: A salt spray test (JIS-Z-2371-2000) was performed on the thick film part of the surface-treated steel sheets 1 to 7 and the surface-treated steel sheets 8 to 14, and the white rust area ratio after 48 hours was measured. The evaluation was as follows.
◎: White rust generation area ratio 5% or less ○: White rust generation area ratio 5% or more and less than 10% ○-: White rust generation area ratio 10% or more and less than 25% △: White rust generation area ratio 25% or more and less than 50% ×: White rust generation area ratio of 50% or more Conductivity: For thin film part of surface-treated steel sheets 1-7 and surface-treated steel sheets 8-14, working electrode: CF type Cr-Cu electrode (tip diameter: 5.5mmφ), pressure : 196 N (200 kgf), energization time: 10 cycles / 50 Hz, welding current: 10 kA, a continuous spot weld test was performed to determine the number of continuous spots and evaluated as follows.
◎: More than 2000 points ○: More than 1000 points and less than 2000 points △: More than 500 points and less than 1000 points ×: Less than 500 points Table 1 shows the results of surface-treated steel sheets Nos. 1 to 7 produced by the method of the present invention. Table 2 shows the results of the surface-treated steel sheets No. 8 to 14 produced by the roll method. The surface-treated steel sheets Nos. 1 to 7 produced by the method of the present invention each have a thin film part excellent in conductivity and a thick film part excellent in corrosion resistance. It can be seen that the feature of the present invention that it can be changed is utilized. On the other hand, in the surface-treated steel sheets 8 to 14 produced by the conventional roll coater, the coating thickness cannot be changed at any position on the steel sheet surface, so the corrosion resistance is excellent when the thickness is thick, but the conductivity is inferior, If the thickness is small, the electrical conductivity is excellent, but the corrosion resistance is inferior, and a steel sheet having both corrosion resistance and electrical conductivity cannot be obtained.

It is explanatory drawing of the manufacturing method of the surface treatment steel plate using the inkjet apparatus which is this invention. It is a figure which shows an example of head arrangement | positioning of the inkjet apparatus which is this invention. It is a figure which shows an example of the manufacturing equipment of the surface treatment steel plate using the inkjet apparatus which is this invention. It is a figure which shows an example of the surface treatment steel plate by which the coating-film thickness was changed in the specific position of the steel plate surface manufactured by the method of this invention.

Explanation of symbols

10 Steel plate
11 heads
21 Paint
31, 32 rolls
40 Heat treatment equipment

Claims (3)

Using a surface-treated steel sheet manufacturing facility in which a plurality of heads equipped with a plurality of heads are arranged along the width direction of the steel sheet, the paint is applied, As droplets from a plurality of heads provided in the ink jet device, a specific head changes the amount of droplets to be ejected, and a conductive required portion requiring weldability and / or electromagnetic wave shielding properties is applied with a thickness of 1 μm or less. A method for producing a surface-treated steel sheet having a corrosion resistance and conductivity , wherein a film is formed and a coating film having a thickness of 1 to 20 μm is formed except for the conductive necessary portion . Using one inkjet apparatus and a heat treatment apparatus equipped with a plurality of heads, and using a facility for manufacturing a surface-treated steel sheet in which a plurality of heads equipped in the inkjet apparatus are arranged along the width direction of the steel sheet, The coating material is discharged as droplets from a plurality of heads provided in the ink jet device, and the amount of droplets is changed and discharged at a specific head, and the thickness is 1 μm at a necessary conductive part requiring weldability and / or electromagnetic wave shielding properties. A method for producing a surface-treated steel sheet having corrosion resistance and conductivity , wherein the following coating film is formed, and a coating film having a thickness of 1 to 20 μm is formed except for the necessary conductive portion , and then the coating film is subjected to heat treatment. 3. The paint according to claim 1 or 2, wherein the paint contains an organic resin and further contains at least one selected from a curing agent, a lubricant, a rust preventive pigment and a color pigment. A method for manufacturing a surface-treated steel sheet.

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