JPH03146388A - Multi-color printing method for container - Google Patents

Abstract

PURPOSE:To effect printing of products in various kinds and in small quantity with improved efficiency and with plate-making process omitted by a method wherein an electrostatic latent image is developed with a toner containing a sublimable coloring material and the toner of the developed toner image is transferred to the surface of a flexible thin membrane, and the toner image is further transferred to the surface of a container with the container stuck fast to the thin membrane and with the toner heated. CONSTITUTION:Over a photo-electroconductive layer 4 on a photosensitive drum 15 that is charged with electricity with an electrifying device 8, an electrostatic latent image is formed by operation of an exposure device 9. Liquid toner 31 is then applied to the electrostatic latent image with a development device 10, and yellow toner particles adhere there. When it reaches a transfer device 16, the toner adheres to a belt 25, making electrophoretic movement in insulating liquid 42. The yellow toner image formed on the drum 15 is then transferred with the belt 25 to a photosensitive drum 50 and magenta toner image is formed there by similar processes. The toner image thus formed is conveyed to a position in front of a turn table 3 and is adhered closely to a metal container 1 with rollers 17 and 48. As the metal container 1 is heated at a high temperature, the toner is stuck fast to the surface of the metal container 1 by sublimation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a container printing method using electrophotography, and an object of the present invention is to omit the plate-making process and efficiently perform high-mix, low-volume printing. This is a printing method for containers made with

[Conventional technology]

Conventional printing methods on the surface of containers include lithographic offset printing, letterpress printing, letterpress offset printing, and screen printing. These will be briefly explained. Lithographic offset printing is a method in which an oleophilic image area and a hydrophilic non-image area are formed on a lithographic plate, the ink adhering to the image area is transferred to a rubber blanket, and the ink is adhered from the rubber blanket to the printing material. . In letterpress printing, the image area is formed into a convex shape, ink is applied thereon, and printing is performed on a printing material. Letterpress offset printing is also called dry offset printing.
This is a method in which the image area is formed into a convex shape, and the ink attached to the image area is transferred to a rubber blanket and adhered to the printing material. Screen printing is a method in which holes through which ink passes are formed in a screen according to the shape of an image, and an ink image is formed on a printing material through the screen. In recent years, these printing methods have become more electronic, and the efficiency of printing has been improved by using layout scanners to computerize the manuscript production stage and by developing direct plate-making systems.

On the other hand, so-called non-impact printing techniques such as an electrophotographic method, an inkjet method, and a thermal transfer method are known as printing techniques that do not use a plate. These technologies are designed to obtain printed images directly from images created or read by a computer, etc., and are used in copiers, facsimile machines, printers, etc., and are attracting attention as a technology that can replace conventional printing.

[Problem to be solved by the invention]

However, the printing method using the above-mentioned plate has the disadvantage that the plate-making operation requires a very large amount of time and effort. As with electrophotography, it was not possible to change the image by simple operations such as operating a computer, and it was not possible to respond immediately to changes in demand when selling short-term products. This has become an even bigger problem as values have become more diversified and the need to print a wide variety of products in small quantities has increased.

On the other hand, when using electrophotography for containers, there were several problems such as the toner transfer process.

In the case of printing on containers, the container may have been previously formed into a cylindrical shape, so in this case, contact with the photoconductor layer is difficult and the container must be pressed against the photoconductor layer with more pressure than necessary during toner transfer. Also, if the container is made of metal such as aluminum or iron, it is less flexible, making it more difficult to completely adhere the entire side surface, making it difficult to form fine, fine-grained images. It was difficult. Furthermore, when printing a plurality of colors, it is necessary to align the container and the printing plate for each color, which is very time consuming. For these reasons, printing by electrophotography has not been applied to containers, which has the problem of increasing the cost of printing plates and increasing the printing unit price when the number of produced plates is small.

[Means to solve the problem]

In the present invention, the above problem is resolved as follows. That is, an image signal is added onto the photoconductor layer to form an electrostatic latent image of the image, and the electrostatic latent image is developed with a toner containing a sublimable colorant, and the toner of the developed toner image is made flexible. Then, on this thin film, toner of another different color toner image is sequentially transferred using the above method, and after the transfer, a container is brought into close contact with the thin film and the toner is heated to remove the toner. The toner image was transferred to the surface of the container by sublimation.

[Effect]

Toner particles of a plurality of colors are transferred from above the photoconductor layer to the surface of the thin film to form a multicolored image on the thin film with little color shift. Since the thin film is flexible, it can be easily attached to the side of the container, and since the toner has sublimation properties, it can form a beautiful multicolor image on the container surface by applying heat and sublimating it. .

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. The photoconductor drum 15 has a photoconductor layer 4 formed of vapor-deposited amorphous silicon, vapor-deposited amorphous selenium, organic photoconductor (polyvinyl carbazole, phthalocyanine, etc.) or the like laminated on the surface of a drum-shaped conductor 5. It is rotatably attached to the shaft 6. Photosensitive drum 15
A charging device 8, an exposure device 9, a developing device 10, a transfer device 16, and the like are arranged around the device, and a belt-shaped belt 25 runs on the side. The charging device 8 is a device in which a charge wire or the like is stretched along the surface of the photoreceptor drum 15.
The photosensitive drum 15 is charged with a negative charge. The exposure device 9 includes a laser oscillator 20, a light modulator 21, and a mirror 22.
The laser beam emitted from the laser oscillator 20 is modulated by the optical modulator 21 according to the signal of the image memory, and then the mirror 22, the rotating polygon mirror 23, the fθ lens 24, etc. The light is then focused on the photoconductor layer 4 and scanned in the axial direction of the photoreceptor drum 15 to form an image. The developing device 10 stores liquid toner 3.
The liquid toner 31 from the pump 32 is ejected from the nozzle 35 and rises inside the tank 30 to form a photoconductive layer. body layer 4
It is designed to come into contact with. The liquid toner 31 uses an insulating liquid such as petroleum-based or olefin-based liquid such as isoparaffin, carbon tetrachloride, fluorinated chlorinated ethylene, or cyclohexane as a solvent, and toner particles are dispersed therein in a charged state by adsorbing ions.・It is suspended. The toner particles are yellow, magenta, cyan, black, etc., and contain a sublimable coloring material in their ingredients. Examples of the sublimable coloring material include Halanyl Yellow 5RX (manufactured by BASF).
, Imicalon RED-FBL (manufactured by Sumitomo Chemical Industries, Ltd.). The transfer device 16 includes a conductive roller 11, a charging device (not shown) that charges the belt 25 wound around the conductive roller 11 to a polarity opposite to that of the toner, a photoreceptor drum 15, and the belt 25. It consists of a nozzle 46 that supplies an insulating liquid 42 into the gap formed between them, a blade 7 that scrapes off the surface of the photoreceptor drum 15, and the like. The insulating liquid 42 is an insulating liquid similar to the solvent of the liquid toner 31, and after being discharged from the nozzle 46, the insulating liquid 42 enters the lower tank 40 with the blade 7 and passes through the filter 44.
The water is filtered and sent to a nozzle 46 again by a pump 43 for circulation.

Further, above the transfer device 16, there is a detector 12 for detecting alignment marks provided on the surface of the belt-shaped belt 25.
is the provision.

The photoreceptor drums 50 and 51 are the photoreceptor drums 1'5.
It has the same structure as the photosensitive drum 15, and the devices arranged around it are also the same as the photosensitive drum 15 except that the toner color is different. For example, if the color of the toner is yellow on the photoreceptor drum 15, the color of the toner is magenta on the photoreceptor drum 50, and cyan on the photoreceptor drum 51. Also, belt-shaped belt 25
are rollers 17, 18 . Conductive roller 11.11...
and a disc-shaped roller 19.19. in contact with the outer peripheral surface. ...
It is rotated at a constant speed in the direction of the arrow by a drive device (not shown).

A circular rotary table 3 equipped with a mandrel 2 is provided at the upper right in the figure. Rotary table 3 is ldl l
The mandrel 2 is attached to a rotating mechanism (not shown) via the mandrel 4, and is rotated and temporarily stopped at a position where the mandrel 2 faces the belt-shaped belt 25.

The mandrel 2 is vertically attached to the outer peripheral portion of the rotary table 3, and an induction heating coil 47 is installed on the side thereof. The metal container 1 is placed on the mandrel 2 by a supply device (not shown). The metal container 1 is formed into a cylindrical shape and has an image receiving layer laminated on its surface, and is heated by an induction heating coil 47. Once the metal container 1 has been sufficiently heated, a pressure roller 48 is inserted inside the metal container 1. , is brought into close contact with the belt-like belt 25 in accordance with the image toner on the belt-like belt 25, and rotates once together with the belt-like belt 25. The cleaning device 26 is a cylindrical brush that is rotated to remove toner remaining on the belt-like belt 25.

Next, the main printing method using the above apparatus will be specifically explained below.

When voltage is applied to the charging device 8, the photosensitive drum 15 first
The upper photoconductor layer 4 is sequentially charged in a negative manner as it rotates.

Next, when this photoconductor layer 4 is exposed by the exposure device 9 in accordance with the image stored in the memory, an electrostatic latent image is formed in the shape of the image. And in the developing device 10,
The liquid toner 31 is applied to the electrostatic latent image thus formed, and the yellow toner particles in the liquid adhere to it due to Crohn's force caused by the electric field of the latent image. When the adhered toner reaches the transfer device 16, it is then attracted toward the belt-like belt 25, electrophoresed in the insulating liquid 42, and adheres to the belt-like belt 25, and an image of yellow toner is formed on the belt-like belt 25. It is formed. Image formation with the yellow toner is now completed, and the toner remaining on the photoreceptor drum 15 is removed by the blade 7 together with the insulating liquid 42, and the photoreceptor drum 15 is uniformly charged by the charging device 8 and the next printing is started. conduct.

The yellow toner image formed on the photoreceptor drum 15 is transferred to the adjacent photoreceptor drum 50 by the belt-shaped belt 25. On the photosensitive drum 50, a magenta toner image is formed in the same manner as the yellow toner described above.
After accurate positioning by the detector 12, magenta toner is applied to the belt-like belt 25, superimposed on the yellow toner, based on a signal from a computer or the like. Furthermore, cyan toner is similarly deposited on the photosensitive drum 51 to form a multicolor toner image on the belt-like belt 25. If necessary, black toner or the like is further applied. The formed toner image is sent to the front surface of the rotary table 3 by the belt-shaped belt 25, and is brought into close contact with the metal container 1 there by being held between the roller 17 and the pressure roller 48. Since the metal container 1 is heated to a high temperature, the toner sublimates and adheres to the surface of the metal container 1. The metal container 1 with the image printed in this way is taken out from the rotary table 3 by a take-out device (not shown) and sent to the next process. The toner remaining on the surface of the strip belt 25 is completely removed by brushing by the cleaning device 26, and new toner images are repeatedly formed by the above method.

Therefore, according to this method, since the transfer pressure between the metal container 1 and the belt-like belt 25 is small, even when printing on a thin container, the container is not damaged, and furthermore, no pixel collapse occurs, resulting in a high-quality image. is obtained. In addition, electrophotography enables thermal printing, which allows immediate printing and allows images to be easily changed by operating a computer or the like. Therefore, even when printing a wide variety of products in small quantities, costs can be kept down and changes in demand can be responded to immediately. Furthermore, since the alignment mark provided on the belt 25 is detected by the detector 12, image alignment is easy and a clear full-color image without color shift can be formed. Moreover, since the belt 25 is flexible, it can be brought into close contact with the surface of the cylindrical container.
A uniform transfer image can be formed on a cylindrical container.

It should be noted that the present invention is not limited to the above-mentioned embodiments; for example, it is possible to print on a plastic container instead of the metal container 1, and the image may be printed in one color. Furthermore, the developing device 10 is not a liquid-based medium but a dry type. [Effects of the Invention] In the container printing method according to the present invention, sublimation toner is used to thermally transfer onto the container, so a large transfer pressure is not required.
Good quality images can be obtained even in thin-walled containers without damaging the container. Further, since electrophotography is used, thermal printing without using a printing plate is possible, and image information stored in a computer or the like can be immediately printed or changed. Therefore, even when printing a wide variety of products in small quantities, the necessary costs can be kept low, and even if demand changes, it can be responded to immediately. In addition, since it is easy to align images on a thin film, it is possible to form a beautiful full-color image without any color shift on the thin film, and since it can be accurately attached to the surface of a cylindrical container, there is no color shift. A transfer image can be formed on the surface of the container.

[Brief explanation of the drawing]

The figure is a sectional view showing an example of an apparatus for carrying out the method of the present invention. DESCRIPTION OF SYMBOLS 1... Metal container, 2... Mandrel, 3... Rotating table, 4... Photoconductor layer, 5...
Conductor, 6... Shaft, 7... Blade, 8... Charging device, 9... Exposure device, 10... Developing device, 11...
... Conductive roller, 12... Detector, 14... Axis,
15... Photosensitive drum, 16... Transfer device, 17.
18...Roller, 19...Disc-shaped roller, 20...
・Laser oscillator, 21... Optical modulator, 22... Mirror 23... Rotating polygon mirror, 24... fθ lens, 2
5... Belt, 26... Cleaning device, 30...
Tank, 31...Liquid toner 32...Pump, 3
5... Nozzle, 40... Tank, 42... Insulating liquid, 43... Pump, 44... Filter 46
... Nozzle, 47... Induction heating coil, 48...
Pressure roller, 50.51...photosensitive drum.

Claims (1)

[Claims] After adding an image signal to the photoconductor layer to form an electrostatic latent image of the image, the electrostatic latent image is developed with a toner containing a sublimable colorant, and the toner of the developed toner image is exposed to the light. The conductor layer was transferred onto a flexible thin film, and then toner images of other different colors were sequentially transferred onto the thin film using the above method, and the toner of a predetermined color was transferred onto the thin film. A multicolor printing method for a container, characterized in that a rear container is brought into close contact with the thin film, and the toner image is transferred to the surface of the container by sublimation of the toner.