JP2522333B2 - Metal container printed on surface and method of printing metal container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metal container having a surface printed thereon and a method for printing the metal container. More specifically, the present invention relates to a method for printing a metal container using an electrophotographic method. TECHNICAL FIELD The present invention relates to a printed metal container and a printing method of a metal container, which enables efficient small-volume printing of various types and enables plateless printing.

[Conventional technology]

As a method of printing on a metal container, a lithographic offset printing method and a relief printing method have been conventionally used. In the lithographic offset printing method, ink is attached to the image area of a lithographic plate having an oleophilic image area and a hydrophilic non-image area, and then the ink on the lithographic plate is transferred to a rubber blanket, Is a method of printing the ink of the above on the printing medium, and the letterpress printing method is
Ink is adhered to the convex image area on the plate, and the ink is printed on the printing medium.

[Problems to be solved by the invention]

Although these conventional printing methods are excellent in terms of productivity during mass production, they all require plates, which requires time and labor in the plate making process prior to printing, and in multicolor printing, registration for each color is required. It has the disadvantage of requiring time and effort.

In recent years, electronics are also advancing in the field of printing, computerization using a layout scanner in the manuscript making process, and direct plate making system development in the plate making process, etc., but until the plate making process can be omitted The above-mentioned drawbacks have not been solved yet.

In addition, the demand for high-mix low-volume printing has increased with the diversification of values, and it has become difficult to deal with the conventional printing method that lacks the immediate printing function.

On the other hand, as a printing technique that does not use a printing plate, there is a so-called non-impact printing technique such as an electrophotographic method or an inkjet method when the printing medium is paper. These techniques can obtain an image directly from an image output of a computer without using a printing plate. In particular, the electrophotographic method is used in copiers, facsimiles, printers, and the like, and has attracted attention as a technology that replaces conventional printing.

In addition, as an application of the method to printing, Japanese Patent Laid-Open No.
There is a multicolor label manufacturing apparatus disclosed in Japanese Patent Publication No. 59-23355. According to the present invention, in each of a plurality of electrophotographic devices, a photoconductor is charged by a charging device, light corresponding to an original is projected on a surface of the photoconductor by an exposure device to form a charged latent image, and a toner is developed by a developing device. Manufacturing a multicolor label in which the latent image is visualized by attaching it to the surface of the photoconductor, then the transfer device visualizes the toner image on the surface of the label substrate, and finally the visualized image is fixed by the fixing device. It features a device.

However, as far as the present inventors know, printing of a metal container to which the electrophotographic method is applied has not been put into practical use.

It is an object of the present invention to provide a metal container and a printing method thereof, which solves the above problems and enables plateless printing without a printing plate.

Another object of the present invention is to provide a metal container and a printing method for the same, which enables immediate printing of image information of a document stored in a computer and enables high-mix low-volume printing.

Still another object of the present invention is to provide a metal container in which a printed surface is a curved surface and which is beautifully printed, and a printing method thereof.

Still another object of the present invention is to provide a metal container having an image resembling a silver salt photograph, which is free from image collapse due to printing pressure, which is seen in lithographic offset printing, gravure printing, and the like, and a printing method thereof. .

[Means for solving problems]

According to the present invention, there is provided a thin sheet metal in which a titanium oxide photoconductor layer having photoconductivity, a toner image layer, and a finishing varnish layer are sequentially laminated on the surface of a metal container directly or through a conductive coating layer. It

According to the present invention, further, a titanium oxide photosensitive layer having photoconductivity is laminated on the surface of the metal container directly or via a conductive coating layer, and a toner particle image is formed on the surface of the photosensitive layer by an electrophotographic method. A method of printing a metal container is provided which comprises forming, fixing the toner particle image, and applying a finishing varnish thereon.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a side view showing a partially cutaway state of the first embodiment of the present invention.

In this example, a drawn-ironing can formed by drawing, redrawing, and ironing was used as the material to be printed.

As the photoconductive layer having photoconductivity, a titanium oxide powder dispersed in an acrylic resin binder and dye-sensitized was used, and the photoconductive layer was coated with an ordinary mandrel coater.

The above-mentioned photoreceptor-coated metal container 1 is covered with a mandrel (not shown) and sent through the electrophotographic units 2, 3 and 4 by a mandrel and a mandrel feed chain, and printing is performed while temporarily stopping and rotating at various device positions. Then, after finishing varnish is applied by the mandrel coater 5, it is sent to a heating oven and dried. afterwards,
Inner spray painting and baking are performed, and neck-in processing and flange processing are performed to complete a metal can.

The electrophotographic units 2, 3 and 4 include a charging device 6 for charging a photosensitive layer on a metal container by corona charging, an exposure device 7 for scanning a laser beam on the layer, and a toner attached to a latent image obtained through the exposure device. A developing device 8 for forming an image on the metal container, a fixing device 9 for heating the metal container by induction heating to melt the toner and fix the toner on the metal container, and a cooling device 10 for cooling the metal container. ing.

The exposure device 7 is composed of a laser oscillator 11, a light modulator 12, a mirror 13, a rotary polygon mirror 14, and an fθ lens 15, and a laser beam emitted from the laser oscillator 11 is a signal from an image memory in the light modulator 12. Is modulated in accordance with the above, is focused on the metal container by the mirror 13, the rotary polygon mirror 14, and the fθ lens 15, and is scanned in the direction perpendicular to the traveling direction of the metal container.

In the present invention, in forming a multicolor image, since the electrophotographic method is used, the alignment of the images of the respective colors is detected by the detector 16 at the registration point provided on the metal can, and the detection thereof is performed. The signal synchronizes the image output from the computer to form a latent image on the metal can.

In the developing device, brush-shaped ears formed of magnetic toner rub against a photosensitive layer on a metal container on a sleeve that rotates around a permanent magnet, and are charged to a polarity opposite to that of the photosensitive layer by frictional charging. The toner present on the photosensitive layer.

In the fixing device, an overcurrent is induced in a metal container by passing it through a high frequency magnetic field generated by a heating coil through which a high frequency current flows, and Joule heat heats the metal container to a desired temperature.

According to the high frequency induction heating, it is possible to heat the metal container, which is the object to be heated, without exerting any force, the temperature can be easily controlled, and the uniform heating can be performed in a short time. The toner particles can be fused very well to the metal container without disturbing the positions of the adhered toner particles.

By the time the metal container is moved to the next electrophotographic unit, the heat of the metal container is transferred to the mandrel cooled by a cooling device (not shown). Further, it is also cooled from the surface by the cooling device 10. The thermal insulation between the mandrel and the metal container is
The metal container is designed to be sufficiently cooled before reaching the next electrophotographic unit.

In consideration of the transparency of the toner, in this example, cyan toner is used in the electrophotographic unit 2, magenta toner is used in the electrophotographic unit 3, and yellow toner is used in the electrophotographic unit 4.

The surface of the metal can thus printed with the color image is covered with the finishing varnish by the mandrel coater 5 to form a strong printed matter.

The above embodiment is configured as described above, and its operation will be described below.

In the metal container that passes through the electrophotographic unit 2, first, the photoconductor layer (photosensitive layer) is uniformly negatively corona-charged by the charging device 6.

Next, when the charged layer is exposed by the exposure device 7 corresponding to the image stored in the memory, the exposed portion becomes conductive, and the charged particles flow to the metal side to lose the charge. Negative charges remain only in the unexposed portions, and as a result, a charged latent image corresponding to the image is formed.
To the charged latent image formed in this manner, a cyan toner positively charged by frictional charging is attached by an electrostatic force by the developing device 8 to form a visible image, and then sent to the fixing device 9.

The metal container is heated by the fixing device 9 by the high frequency induction heating method, the portion of the toner in contact with the metal container is melted and becomes sticky, and the toner is fixed to the metal container.

Similarly, the electrophotographic unit 3 forms an image with magenta toner, and the electrophotographic unit 4 forms an image with yellow toner.

In this manner, the metal container on which the image is formed with the three color toners is coated with the finishing varnish by the mandrel coater 5,
It is sent to the oven for heating and baking.

FIG. 2 is a side view showing a second embodiment of the present invention,
In the second embodiment, the exposure apparatus 7 of the apparatus shown in FIG.
Are replaced by the exposure device 28 shown in FIG. In the figure, 281 is a document table on which each color document is placed, 282 is a light source lamp, and 283 is a mirror, which move at a constant speed from the position indicated by the solid line to the position indicated by the alternate long and short dash line during exposure. Mirror 28
Similarly, 4 moves from the position indicated by the solid line to the position indicated by the alternate long and short dash line.
In the second embodiment, the metal container 1 is detected by the detection device 16.
When the upper registration position is detected, the light source lamp 282 and the mirrors 283 and 284 start moving from the positions indicated by the solid lines, and the document table 281
The reflected light of the strip-shaped portion of the upper document is focused on the metal container 1 via the path on the dashed line in the figure, that is, the mirror 283, the mirror 284, the lens 285, the mirror 286, and the mirror 287. In the second embodiment, since the exposure is performed in a strip shape, the exposure time can be made shorter than that in the first embodiment in which the point-shaped exposure is performed. In the second embodiment, the same device as in the first embodiment is used for the parts other than the exposure device.

Although the developing device 8 is a device that employs a dry developing method in this embodiment, it absorbs ions and the like in an insulating liquid such as petroleum-based, hydrocarbon-based, olefin-based solvent such as isoparaffin, carbon tetrachloride, and cyclohexane. A liquid developing method in which charged toner particles are dispersed, suspended, and adhered to the photoconductor layer by Coulomb force by the latent image electric field may be used.

In this embodiment, cyan toner is used in the electrophotographic unit 2 and magenta toner is used in the electrophotographic unit 3.
Although yellow toner is used in the electrophotographic unit 4, the present invention is not limited to this embodiment and can be variously modified. For example, the electrophotographic unit 2 may use yellow toner, the electrophotographic unit 3 may use cyan toner, and the electrophotographic unit 4 may use magenta toner. If necessary, the number of electrophotographic units may be increased more than in the present example, and black toner may be added to form an image.

These toners are obtained by dispersing a colorant such as disazo yellow, benzidine yellow, sproin yellow, rhodamine, quinacdrine, carmine 6B, copper phthalocyanine, and carbon black in a binder resin.
As the binder, wax, thermoplastic resin, or thermosetting resin is used. Polystyrene resin, polyolefin resin, acrylic resin, polyester resin and the like are used as the thermoplastic resin, and epoxy resin, polyurethane resin and the like are used as the thermosetting resin. Also,
If necessary, a charge control agent, a flow improver, an antiblocking agent and the like are added.

Metal containers, particularly metal cans, are spray-coated and baked on the inner surface in the post-printing process, and the toner is required to have heat resistance. After that, neck-in processing and flange processing are performed, and workability and adhesion are also required. Furthermore, after filling the contents, steam sterilization is performed at 100 ° C or higher, and the toner is required to have hot water resistance. Therefore, a thermosetting resin such as an epoxy resin is preferable as the binder for the toner.

As the photoconductor, titanium oxide powder dispersed in acrylic resin, alkyd resin, epoxy resin, silicone resin, polyester resin or the like is used.

The photoconductor layer may be provided directly on the surface of the metal container,
A conductive coating layer may be provided in the middle. As the conductive coating layer, in a binder resin such as acrylic resin, alkyd resin, epoxy resin, polyester resin,
A material in which a conductive filler such as aluminum, nickel, copper, carbon or graphite is dispersed is used.

The finishing varnish is applied for the purpose of protecting the toner layer and providing gloss. That is, in a metal container, particularly a metal can, in the post-printing process, the toner layer is damaged due to collision between the cans due to conveyance, contact with a feed guide, and the like.
Abrasion and peeling occur. After filling the contents, steam sterilization at 100 ° C. or higher is performed, and the toner layer is softened and decolorized. For these reasons, it is necessary to apply a finishing varnish to protect the toner layer.

As the finishing varnish, acrylic resin, polyester resin, epoxy resin, alkyd resin, amino resin and the like are used, and acrylic resin and polyester resin are particularly preferable.

〔The invention's effect〕

According to the metal container and the metal container printing method of the present invention, since the electrophotographic method is used, the plate making process is not necessary, the image information of the original document stored in the computer can be printed immediately, and the register for multicolor printing can be obtained. Matching is extremely easy, color correction and the like can be easily performed, and high-mix low-volume printing can be performed in an extremely short time.

Further, since the electrophotographic method can perform printing with almost no pressure applied to the metal container, it is possible to easily perform printing on the metal container having a curved surface to be printed.

Furthermore, since the characteristics of electrophotography are used, the gradation is continuous, and an image similar to silver halide photography is printed, and since a finishing varnish is applied on this image, the printing surface becomes strong. A metal container is obtained.

[Brief description of drawings]

FIG. 1 is a side view showing a partially cutaway state of a first embodiment of the present invention, and FIG. 2 is a side view showing a second embodiment of the present invention. 1 …… Metal container, 2,3,4 …… Electrophotographic unit, 5 ……
Mandrel coater, 6 ... Charging device, 7 ... Exposure device, 8 ... Developing device, 9 ... Fixing device.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Kazuhisa Ishibashi 2-55-12-505 Sangenjaya, Setagaya-ku, Tokyo (56) References JP 60-192956 (JP, A) JP 42-18676 (JP) , B1)

Claims (2)

(57) [Claims] 1. A metal container in which a titanium oxide photoconductor layer having photoconductivity, a toner image layer, and a finishing varnish layer are sequentially laminated on the surface of the metal container directly or through a conductive coating layer. 2. A titanium oxide photosensitive layer having photoconductivity is laminated on the surface of a metal container directly or via a conductive coating layer, and a toner particle image is formed on the surface of the photosensitive layer by an electrophotographic method. Then, the toner particle image is fixed, and a finishing varnish is applied on the toner particle image, and a method for printing a metal container.