JPH0564585B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a high-grade decorative metal plate.

(Prior technology) To manufacture high-grade decorative metal plates used for food cans and other art cans, first, metal plates such as mild steel plates, various types of plated steel plates, and aluminum are coated with white to give the same effect as paper printing. A coating is applied (base coat layer) and then the design is printed in color (print layer). Finally, a transparent finishing coat (top coating layer) is applied to protect the printed surface. Sizing coating is sometimes applied before white coating to improve adhesion to the metal plate. For the white coating, for example, a finishing varnish mixed with fine powder of titanium oxide is used. Finishing varnishes used for finishing coating include alkyd resins and highly heat-resistant polyesters.

By the way, the printing layer has conventionally been formed by offset printing or gravure printing. This is because the object to be processed is a metal plate with a hard surface, making direct printing difficult. In offset printing, the drawing lines are first printed on a resilient rubber blanket sheet,
This is then transferred from the rubber blanket sheet to the metal surface. Gravure printing is intaglio printing using photolithography.

(Problems to be Solved by the Invention) However, when these printing methods are applied to the white coating of a metal plate, the color tone cannot be made clearer than a certain level. Therefore, there are difficulties in increasing the added value of products. Further, it takes a long time to heat and dry these printing inks to solidify them. Furthermore, it is necessary to make a plate for each design, and it is necessary to wash the printing machine for a long time every time the plate is changed, so it is uneconomical, inefficient, and unsuitable for printing a wide variety of products in small quantities.

(Means for Solving the Problems) The present invention has been made in view of the above circumstances, and provides clear color tones and short printing time (realistic printing).
The purpose of the present invention is to provide a high-grade decorative metal plate that can be printed in a short amount of time) and that can also be used for printing a wide variety of products in small quantities.

The high-grade decorative metal plate according to the present invention includes a mild steel plate, a white coating layer containing fine white powder that covers the base surface of the mild steel plate, and a document that is irradiated with light and the reflected light is projected onto the member to make it static. a print layer formed by forming an electrostatic latent image, developing this electrostatic latent image with a color developer, and transferring it from the member onto the white coating layer; and a print layer further formed on the print layer. a transparent top coating layer,
It is characterized by having the following. In this case, further
It is preferable to have a plating layer plated on a mild steel plate, a chemical conversion treatment layer, and a primer layer as a base for the white coating layer.

Mild steel, stainless steel, aluminum, etc. can be used for the metal plate. When mild steel is used, it may be plated with electrolytic tin or electrolytic chromate and then base coated to prevent rust.

White coating layer (white base coat)
For formation, polyester resins colored with white pigments such as titanium oxide, epoxy resins, acrylic resins, silicone-modified polyester resins, epoxyphenol resins, urethane resins, epoxyurethane resins, polyester urethane resins are used. Pre-coated steel plate paints such as those based on acrylic urethane resins or vinyl chloride resins, or hot melt adhesives colored with white pigments such as titanium oxide can be used.

In addition, base coat paints include polyester resin, epoxy resin, acrylic resin,
Paints for pre-coated steel sheets such as silicon-modified polyester resins, epoxy phenol resins, urethane resins, epoxy urethane resins, polyester urethane resins, acrylic urethane resins, and vinyl chloride resins can be used, and hot-melt adhesives can also be used. A substance having the same main ingredient as the agent can be used. Furthermore, various colors can be selected to match the printed design.

Color xerography includes those that transfer developer from a photoreceptor using electrical energy and those that transfer color ink from an ink film using thermal energy. Either method can make the color tone clearer by significantly increasing the number of tone gradations than conventional printing methods.
Since it is easy to change the plate, it is suitable for printing a wide variety of products in small quantities. Furthermore, the heating and drying time of the paint is dramatically shortened, making it possible to print in real time. When xerography is used for printing, a computer can be linked to easily create plates for designs using computer graphics, and the incorporation can be automated. In this case, it is possible to easily form a plate that expands and contracts the design after molding, such as can manufacturing, and applies it to printing on sheet metal plates.

(Function) In the case of the method of transferring images using electrical energy, a photoconductive layer sensitive to red, green and blue light is formed on the xerographic plate. For this purpose, several separate photosensitive plates or one panchromatic photosensitive plate may be used. The developer is 3
Kind is required. Xerography is a positive image process, in which the electrostatic latent image that remains after exposure through primary color filters represents the complementary color of that color. Therefore, the three-color method with direct development uses developer materials with complementary colors.

The process of creating a print layer from a transparent positive color is as follows. (See Figure 1, R, G, B and W indicate red, green, blue and white images, respectively).

1. After corona charging 4 the xerographic photosensitive plate 2 on the photosensitive drum 1, the transparent positive color image 8 is exposed to white light 10 on the photosensitive plate 2 through a red filter 6. (Figure 1a).

2 Develop the photosensitive plate 2 with the cyan developer 12 (same b).

3. Transfer the developed image 4 to the white coating layer 16 of the metal plate 18 (same c).

4 Similarly, expose with green filter 20 (d)
After that, it is developed with magenta developer 22 (see e),
Cyan image 1 in front of white coating layer 16
Copy according to 2 (f).

5. Expose and develop in the same manner using the blue filter 24 and yellow developer 26 (see g, h), and transfer in accordance with the previous two images 12 and 22 (see i).

6. Fix the final color image of the print layer using the heating drying means 28 (j).

By the way, the paint used for metal printing must not only adhere to the white coating, but also be corrosion resistant even in an industrial atmosphere, and must withstand harsh post-processing such as can manufacturing. be. Also, unlike paper, it may be exposed to sunlight, but it must not discolor even in that case. In this case, a common developer can be used.

In addition, in the case of color xerography for the sublimation type thermal transfer method, as shown in FIG. Adjust the direction. Next, the ink film 37 on which the latent image has been formed is irradiated, and the ink is sublimated by the thermal energy of the laser beam and transferred to the metal plate 40 . As shown in FIG. 3B, the ink film 37 has a structure in which an ink film base 38 is sequentially coated with a light absorption/heat generation layer 42 and a transition layer 44 coated with ink of three primary colors. When the light absorbing/heating layer 42 at the location hit by the laser beam generates heat, the ink forming the transition layer at that location sublimes and transfers to the white coating layer 46 of the metal plate 40 .

(Example) An example of the present invention will be described below with reference to the color xerography apparatus shown in FIG. FIG. 3 shows a color xerography apparatus for producing the high-grade decorative metal plate of the present invention. An optical section 51 is provided at the top of the apparatus main body 50, and projects light from a lamp 61 reflected from a document onto a photoreceptor drum 63 through a lens 62 to form a latent image. The light reflected from the original and passed through the optical section is separated into red, blue, and green light by a color separation filter 52. On the other hand, the photosensitive drum 63 is charged with a charging corotron 53 . Next, the electrostatic latent image on the drum 63 is developed in the developing section 54 using developers of three colors: cyan, magenta, and yellow. Here, the cyan toner was colored with Phthalocyanine Blue B, the magenta toner was colored with Little Maroon, and the yellow toner was colored with Hansa Yellow G. The image on drum 63 is transferred by transfer corotron 55 to mild steel plate 64 on transfer drum 56 . Mild steel plate 64
is coated with white before being put into the device main body 50. The mild steel plate 64 may be from either the upper line or the lower line. After this, the photosensitive drum 63 is cleaned by the cleaning corotron 57.
After removing the charges remaining on the transfer drum 56 and the photoreceptor drum 63, the cleaning section 58 cleans the transfer drum 56 and the photosensitive drum 63. On the other hand, the toner is fused to the mild steel plate 64 to which the image has been transferred at the fuse portion 59, thereby completing the print layer. Finally, top coating is applied using the roll coating method to complete the production of the decorative board.

Next, a description will be given of the results of an investigation into the sharpness of the color print tone of the decorative steel sheet manufactured in this manner. An electrogalvanized steel plate with a thickness of 0.5 mm and a plating amount of 20 g/m ² per side was used as the metal plate, and as a base treatment, zinc phosphate 1.
g/m ² , chromate treatment (metallic chromium adhesion amount 30
g/m ² ). On top of this, as a base coat, first apply an epoxy primer with a roll coater to a dry film thickness of 5 μm, dry and bake, and then roll coat a commercially available white polyester paint to a dry film thickness of 5 μm.
It was coated to a thickness of 15 μm, dried and baked.

After printing a pattern on this using the color xerography method, a polyester clear paint was applied to a dry film thickness of 1 μm, and then dried and baked.

A sample was taken from the steel plate (Example) produced as described above, and a sample of the steel plate (Comparative Example 1) produced in the same manner as in the Example except that there was no base coat, and a print layer was printed by offset printing. The brightness of color tone was compared and evaluated by visual appearance inspection with a sample of a steel plate (Comparative Example 2) produced in the same manner as in the example except for the above. As a result, in Comparative Example 1, the color tone is bright, but the design pattern is a little unclear, and in Comparative Example 2, the color tone is not vivid, and the design pattern is also unclear, whereas in Example, the color tone is bright and The patterns also became sharper and clearer.

The color tone of the decorative steel sheet produced as described above was clearer than that of conventional products, and the adhesion was also good and comparable to that of conventional products. Furthermore, when a decorative board was manufactured in the same manner as in the above example using a stainless steel plate, an aluminium-plated plate, or an electro-tin plated steel plate in place of the above-mentioned mild steel plate, the same results as in the above-mentioned example could be obtained.

Note that the top coating may be performed by a flow coating method. Further, the white coating and top coating may be performed continuously within the main body of the apparatus. The image can also be formed by computer graphics in conjunction with a computer instead of the original.

(Effects of the Invention) According to the present invention, high-grade printed metal plates with clear color tone and high added value can be manufactured in real time, and it is also possible to quickly respond to high-mix low-volume production.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the basic process of color xerography to transfer an electrostatic latent image, Fig. 2 is a schematic diagram of sublimation type thermal transfer color xerography, and Fig. 3 is a color diagram according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the xerography device. 6... Red filter, 20... Green filter, 24... Blue filter, 52... Color separation filter, 54... Developing section, 56... Transfer drum.

Claims (1)

[Claims] 1. A mild steel plate, a white coating layer containing fine white powder that covers the base surface of the mild steel plate, and an electrostatic latent image formed by irradiating light onto a document and projecting the reflected light onto the member. a print layer formed by forming an electrostatic latent image with a color developer and transferring it from the member onto the white coating layer; and a transparent top layer formed on the print layer. A high-grade decorative metal plate comprising a coating layer. 2. The high-grade decorative metal sheet according to claim 1, further comprising a plating layer plated on a mild steel sheet as a base for the white coating layer.