JPS5925216B2 - Color electrophotography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel multicolor printing method, and more particularly to a novel color electrophotographic method using transfer electrophotography.

In a conventional electrophotographic color printing device, in the direct method, photosensitive paper coated with ZnO or an organic photoconductive substance is charged first, and then a transparent filter for red, green, blue (and black if necessary) is applied. ) Color separation of the original image is performed sequentially using a filter, this is projected onto the photosensitive paper to form an electrostatic latent image, and this is then developed using a developer having a complementary color relationship to the filter to form a predetermined color image. It has gained.

Similarly, in the indirect method (transfer method), a photoreceptor containing a photoconductive material such as CdS or Se is exposed to a color-separated light image using a predetermined filter after primary charging (AC
The electrostatic latent image is formed on the photoreceptor, which is developed using a developer compatible with the filter, and then the transfer paper held on the transfer roll is exposed. , the powder image on the photoreceptor is transferred by pressurizing it synchronously with the developing image on the photoreceptor, and the above process is repeated in red, green, blue (
Repeat 3 or 4 steps (ND-filter if necessary) and apply 3 colors (4 colors if necessary) to the transfer paper on the transfer roll.
After the transfer paper is overlapped to obtain a color image, the transfer paper is separated from the transfer roll and heated to fuse and fix the color powder image on the transfer paper to obtain a color image.

However, the color images obtained in this way have the following drawbacks.

1. In either case of transfer or direct method, the image surface has many irregularities and is essentially a porous image, so the surface of the copied image reflects diffusely and the color reproducibility is not good with respect to the original image.

2. In order to compensate for the above drawbacks, a method of melting and fixing the color image on the transfer paper can be considered, but in this case it is common to pass it through a pair of heated rolls, but in that case, the offset of the powder image with respect to the rolls becomes a problem. .

3. In addition to the above-mentioned system in which each color is transferred one by one, there is a method in which each color is layered on a photoreceptor, a color image is formed thereon, and finally the color image is transferred to a transfer material at once, and one color is transferred onto the photoreceptor one after another. There is a method in which an image is developed and transferred onto a transfer roll in a superimposed manner to obtain a color image corresponding to the original image on the transfer roll, and then the color image is transferred all at once onto a transfer paper.

In these methods, the above 1. )2. In addition to the disadvantages of ), the adhesion between the photoreceptor or transfer roll and the toner or powder image is different from that between each toner or powder image. For this reason, all colors (
(3 layers or 4 layers) It is difficult to transfer uniformly, and in particular, the color on the photoreceptor or transfer roll side may partially separate and remain on the photoreceptor or transfer roll side without reaching the transfer paper. It becomes a factor that disturbs the An object of the present invention is to provide a color electrophotographic method that solves the above-mentioned drawbacks.

That is, the present invention provides a color electrophotographic method capable of obtaining images with improved color chromaticity without diffused reflection on the surface of color images. The present invention also provides a color electrophotographic method that can prevent offset of a color powder image with respect to a heated roll. Further, the present invention provides a color electrophotographic method that enables uniform transfer of color images and provides clear color images without missing parts. Furthermore, the present invention provides a color electrophotographic method that is easy to clean. An embodiment of the present invention is shown in FIGS. 1 and 2 below. In FIG. 1, before forming a color latent image on the photoreceptor 9, a corona charger 8 applies a primary charge such as e, and then a color original 5 is exposed onto the photoreceptor surface through a lens 6. . At this time, the color separation filter 7 is not operated or exposure is performed through the ND filter 1.
Thereafter, the developing device 1 is operated to form the latent image. The developing device 1 has a structure in which a magnet is placed in a non-magnetic sleeve 1a, and 1b is a stirring bar.

In this developing device, carrier iron powder and toner made of the following polymer powders are mixed. For example, as a representative substance with excellent negative polarity, as a chlorinated substance,
Polyvinyl chloride, vinyl chloride-styrene copolymer,
There are vinyl chloride acetic acid, vinyl copolymer, chlorinated polystyrene, chlorinated polyester, chlorinated polyethylene, chlorinated paraffin, etc. In addition, those showing negative polarity include phenol resin, salicylic acid resin, phenooxyacetic acid resin, rosin. Examples include modified maleic acid resin, rosin modified phenolic resin, and alkyl phenol.

These substances may be used alone or in a mixture of two or more.
Generally, when obtaining a toner with a desired polarity, there are many methods for forcibly obtaining the desired polarity using a control agent, etc. However, when dyes or pigments are used as these control agents, it is preferable for the purpose of the present invention. do not have. The non-control agent toner, that is, the toner made of the above-mentioned polymeric substance, is pulverized to 3 to 40 μm using a pulverizer that applies air pressure, and then pulverized to 3 to 40 μm using an air classifier (5 to 15 μm).
μ) Classify to obtain the desired toner. The latent image is developed with the above toner to form a transparent image corresponding to the original image. On the other hand, the color separation filter 7 is operated from the second image exposure following the end of the first image exposure, and an electrostatic latent image corresponding to the color separation components of the original image is formed on the drum.
(Cyan toner, magenta toner, yellow toner, (
Develop sequentially with light black toner)). Finally, a color image is formed on the photoreceptor, and then the transfer material 11 is placed on the transfer roll 10.
While conveying the image, the image is pressed and transferred onto the image in synchronization with the image, and after the transfer, the transfer material is separated from the transfer roll and transferred to the fixing roll pair 13.
The image is fixed by heating. As shown in the second diagram, the images formed in this manner are: an image T1 made of transparent toner; a cyan image C1 a magenta image M; a yellow image Y; Each layer of the black image (black image) is lined up, and after being transferred to the transfer material, the image formed by the transparent toner becomes the outermost layer.

Therefore, even if there is a drop in transfer efficiency, the transparent layer T on the image carrier side of the toner image. Images made of color toner can be transferred 100%, so there is no fear of missing transfers at all for color images. Furthermore, since the transparent toner melts and covers the image surface after fixing, diffused reflection on the surface can be prevented and the color quality can be improved. That is, the third
As shown in FIGS. 3-a to 3-d, an image T is also formed using transparent toner according to the density of the original, so an image C is formed using toner of each color. Not only is the transfer after formation extremely easy, but also, after fixing, a sufficient transparent layer image is formed on the transfer member P according to the image area, so that good color gloss can be easily produced. In addition, by mixing waxes, fatty acids, and fatty acid derivatives into the polymeric substances constituting the transparent toner, the surface is easily melted by heat to form a uniform film, which prevents diffused reflection and improves transparency. It is possible to obtain color images with improved surface gloss.

Furthermore, since there is no transparent layer formed by melting transparent toner in the non-image area, writing and the like can be easily performed. Furthermore, it plays a role in preventing offset during fixing with a hot roll, and further improves releasability from the photoreceptor or transfer roll. For example, when a polymer substance is used as a toner material,
When a powder image is passed through a heated roll fixing device, the toner is thermally fused to the roll surface, causing image disturbance and significantly lowering the image quality. However, if 5 to 20% of the above-mentioned waxes and other substances are mixed into the base material, no problem occurs. No such problem will occur. Waxes used in the present invention include polyethylene glycol, carnaval, paraffin, paraffin chloride, etc. Fatty acids include caproic acid, enantylic acid, pyrofuric acid, pelargonic acid, pyropuric acid, undecylic acid, lauric acid, tridecoic acid, and myristic acid. Acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, nontecylic acid, arachidic acid, behenic acid, styrigic acid, palmitoleic acid, oleic acid, ricinoleic acid, petroselinic acid, vaccenic acid, linoleic acid, linolenic acid, Metal salts of eleostearic acid, ricanic acid, valinaric acid, gadoleic acid, and arachidonic acid fatty acids include cadmium stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, and copper stearate. , strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, zinc oleate, manganese oleate, iron oleate, cobalt oleate, copper oleate, lead oleate, magnesium oleate, zinc palmitate, palmitic acid. cobalt,
These include copper palmitate, magnesium palmitate, aluminum palmitate, calcium palmitate, lead pyrofurate, lead caproate, zinc linoleate, cobalt linoleate, calcium linoleate, and the like.

FIG. 4 shows another embodiment in which an image is first formed using transparent toner on a photoreceptor 9, and then electrostatic latent images corresponding to color separation components are sequentially formed. 4 to 4, and sequentially superimposed and transferred onto the transfer roll 10.

After obtaining a color image on the surface of the transfer roll, the transfer material 11 is conveyed in synchronization with the image, the color image is transferred to the transfer material at once by the transfer corona 15, and this transfer material is transferred to the conveyor belt 11.
4, the image is sent to the fixing roll 13 and fixed. By the way, the surface of the transfer roll 10 is usually made of conductive rubber or rarely metal, but if there is transparent toner made of the above-mentioned polymeric substance, the color toner images to be superimposed thereafter will not be in direct contact with the transfer roll, so each color toner image will not be in direct contact with the transfer roll. The adhesiveness of each layer is uniform, preventing peeling off from the middle of the layer.

Therefore, even if the image formed by the transparent toner is not 100% transferred, it will not cause any trouble in the next cycle and there is no need to clean it. Also, even if the front and back of the image are slightly smudged with toner, cleaning is extremely difficult if the transfer roll 10 is made of rubber or the like, but the presence of wax or fatty acids in the transparent toner may cause the blade It has a lubricating effect on the transfer roll and has the effect of making cleaning smoother.

[Brief explanation of the drawing]

FIGS. 1 to 4 are explanatory diagrams illustrating color electrophotography of the present invention. 1...Developer containing transparent toner, 2-4...
...Developer containing cyan toner, magenta toner, and yellow toner, 6... Lens, 7...
...Color separation filter 8...Corona charger,
9...Photosensitive drum, 10...Transfer roll, 11...Transfer material, 13...Fixing roll, 15...For transfer corona.

Claims (1)

[Scope of Claims] 1 In color electrophotography, in which a color image is obtained by developing a latent image corresponding to a color separation image with a color developer, a latent image corresponding to the final image is formed on the surface of a photoreceptor, and this latent image is developed with a color developer. A step of developing the image with transparent toner, a step of superimposing an image of a different color toner on the transparent toner image, and simultaneously transferring the transparent toner and color toner images formed on the photoreceptor onto a transfer material. 1. A color electrophotographic method comprising the steps of transferring, and simultaneously fixing an image of transparent toner and color toner on the transfer material onto the transfer material. 2. In color electrophotography, in which a color image is obtained by developing a latent image corresponding to a color separation image with a color developer, a latent image corresponding to the final image is formed on the surface of a photoreceptor, and this latent image is developed with a transparent toner. Then, a step of transferring this transparent toner image to the surface of the intermediate image carrier, and then sequentially forming images with different color toners on the surface of the photoreceptor, and transferring a toner image for each color component to the surface of the intermediate image carrier. a step of sequentially transferring an image of the transparent toner and color toner transferred onto the surface of the intermediate image carrier onto a transfer material, and a step of simultaneously transferring an image of the transparent toner and color toner on the transfer material; A color electrophotographic method comprising the step of simultaneously fixing a toner image onto the transfer material.