JPS61126566A - Transfer method - Google Patents

Abstract

PURPOSE:To make possible the thorough transfer of the toner image on a photo sensitive body by superposing the toner image formed on the photosensitive body by an electrophotographic method and a transfer base having a layer consisting of a thermosetting resin and subjecting the same to thermocompres sion bonding then stripping the transfer base. CONSTITUTION:Any photosensitive body 1 is usable as far as said body is an ordinary electrophotographic sensitive body. The toner image 6 is formed on the surface of the photosensitive body 1 by the ordinary electrophotographic process. The developing method may be either dry process developing or wet process developing. The transfer base 8 provided with the thermosetting resin layer 7 is then superposed thereon and is subjected to thermocompression bonding. The base 8 which is held superposed on the body 1 is allowed to cool in this state and thereafter the base 8 is stripped from the body 1, by which the toner image 6 is transferred thereto.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to so-called transfer-type electrophotographic image formation in which an image is created on a transfer base by transferring a toner image formed by an electrophotographic process. This relates to a transfer method.

[Conventional technology]

When obtaining a transfer type image using electrophotography, a photoreceptor whose surface is uniformly charged by corona discharge is subjected to image exposure, and then toner development is performed to form an electrophotographic image. It is common to transfer the electrophotographic image electrostatically by placing, for example, paper on top of the paper and applying charges of opposite polarity from the back side of the paper.

Other methods are known, such as pressure transfer methods, but in any case, conventional transfer methods transfer images at 100%
% transfer is difficult, and a portion of the toner image remains on the photoreceptor. Therefore,
In particular, when trying to transfer a color image obtained by overlapping three colors using the above-mentioned conventional transfer method, the transfer state of the toner in the bottom layer deteriorates, causing the color balance of the image to collapse, resulting in a sharp image. It has been impossible to directly transfer a color image in one transfer, for example, because it is difficult to obtain a color image.

Therefore, it is necessary to transfer each of the three color toner images once. For example, on the photoconductor, charging - image exposure of the first color - development of the first color - transfer of the first color are performed, and then After cleaning the body, the process of charging - second color image (l exposure - second color development - second color transfer) is repeated three or more times, and the transfer medium (paper,
A color image R (multicolor image) is obtained on a film (film, etc.).

However, in this case, a difficult problem arises in positioning each color during transfer. For example, because the positional accuracy of transfer is very strict, color misregistration is likely to occur, and this also becomes a factor in increasing the size of the machine.

In addition, when transferring each color individually, it is difficult to balance each color, making it difficult to obtain high-quality color hard copies from the perspective of color tone. This inability to transfer 100% of the image results in a reduction in the density of the transferred image, that is, a reduction in the dynamic range, which is a major drawback in the field of high-quality Victorian hard copies.

[Problem that the invention seeks to solve]

As described above, in the conventional transfer method, the toner image on the photoreceptor cannot be completely transferred, and a clear transferred image cannot be obtained. In particular, when trying to transfer a color image by overlapping colors, it is difficult to transfer it in one go, and color misregistration, loss of color balance, etc. occur.

Therefore, the present invention was proposed in view of the above-mentioned conventional situation, and it is possible to almost completely transfer a toner image onto a transfer medium, and for example, a color image by overlapping colors can be transferred in one operation. It is an object of the present invention to provide a transfer method that enables transfer, and thereby to provide a clear transferred electrophotographic image with good color balance and no color shift.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention has been developed by superimposing a toner image formed on a photoreceptor by electrophotography and a transfer base having a layer made of a thermoplastic resin, and then applying thermocompression bonding. The toner image is transferred onto the transfer base by peeling the photoreceptor and the transfer base.

That is, in the present invention, a toner image formed on a photoreceptor by an electrophotographic process is 100% transferred onto a transfer base by, for example, thermocompression bonding a transfer base coated with a thermoplastic resin in advance, and peeling off after cooling. It transfers and fixes at the same time.

In this case, any electrophotographic photoreceptor may be used as long as it does not adversely affect the image by melting during thermocompression bonding, and the developing method may be dry or wet. Furthermore, not only monochrome images but also color images obtained by overlapping three or more colors can be transferred and fixed as they are.

[Effect]

As described above, in the transfer method according to the present invention, since the transfer base whose surface is coated with thermoplastic resin in advance is transferred by thermocompression bonding to the toner image, the toner is wrapped in the thermoplastic resin, The toner image on the photoreceptor can be almost completely transferred onto the transfer base. Furthermore, in this case, since the toner is encapsulated in the thermoplastic resin layer, fixing is performed at the same time as transfer.

〔Example〕

The transfer method of the present invention will be explained below with reference to the drawings.

In order to obtain a transfer-type color image, first, a photoreceptor 1 as shown in FIG. 1 is prepared.

As the photoreceptor I, any ordinary electrophotographic photoreceptor can be used, but here, for example, the conductive layer 2 such as an ITO (Indium Tin Oxide) electrode or an aluminum electrode is made of polyester. An inorganic photoconductor represented by zinc oxide, selenium, etc. or an organic conductor represented by poly-N-vinylcarbazole is contained on a conductive support 4 formed by vapor deposition on the surface of a base 3 such as a film or paper. An example in which a photoconductive layer 5 is formed will be described.

Next, as shown in FIG. 2, a toner image 6 is formed on the surface of the photoreceptor 1 by a normal electrophotographic process.

The developing method for forming the toner image 6 may be either dry development or wet development, but for example, using a photoreceptor! When three or more color toner images are to be produced thereon, wet development or mist development does not disturb the previous color image by development of the next color. In particular, if a liquid developer with very small toner particles is used, the adverse effects of trapping due to the hiding effect of the toner can be reduced. Further, by performing exposure with light having a wavelength other than the toner absorption wavelength, it is possible to prevent the filter effect from being affected. Furthermore, by performing electrical signal processing, it is also possible to cancel the effects of trapping.

For example, in laser light exposure, electrical signal processing is also possible, and exposure at wavelengths other than toner absorption wavelengths can be easily realized.

Alternatively, even in dry development, for example, if jumping development using -component magnetic toner is used, the image of the previous color will not be disturbed by the development of the next color.

As shown in FIG. 3, a transfer base 8 provided with a thermoplastic resin IW 7 is superimposed on the photoreceptor 1 on which the toner image 6 has been formed and bonded by thermocompression.

As the transfer base 8 used here, any material can be used, including paper, film, etc., as long as it can be coated with resin and bonded by thermocompression to the photoreceptor. Further, the thermoplastic resin material applied to the surface of the transfer base 8 to form the thermoplastic resin layer 7 is one having a glass transition temperature Tg sufficiently lower than the temperature of thermocompression bonding, for example, one having a relatively low molecular weight. Any type of PI resin material can be used; however, in practice, the most suitable resin material may be selected from the viewpoint of compatibility with the toner, releasability from the photoreceptor, and the like. In particular, in consideration of peelability from the photoreceptor, image fixability, etc., it is preferable that the glass transition temperature Tg is higher than room temperature and the adhesiveness at room temperature is not very high. Further, additives such as plasticizers can be added to the thermoplastic resin material as necessary, and two or more layers of resins having different properties can be applied to form a multilayer structure. These resin materials may be applied using conventionally known coating methods such as solution coating and hot melt coating.

On the other hand, the temperature conditions for the above thermocompression bonding may be set to any appropriate value depending on the properties of the resin, etc., but generally the temperature is 200°C or less, and in practical terms, the temperature is about 50 to 200°C. Often set in a range.

Alternatively, thermocompression bonding may be performed using heat generated by applying pressure without applying external heat.

The thickness of the thermoplastic resin layer 7 can be changed arbitrarily, but is generally about 2 to 30 microns. In particular, when transferring a color image by overlapping colors, the resulting toner layer is thick, so a slightly thicker resin layer 7 will yield better results.

Subsequently, as shown in FIG. 4, the transfer base 8 is placed on the photoreceptor 1 and left to cool, and then, as shown in FIG. 5, the transfer base 8 is peeled off from the photoreceptor 1. to copy the toner image 6.

Hereinafter, specific examples of the present invention will be described.

Example 1 Adhesive layer and PVK-TNF (polyvinylcarbazole-
After applying corona charging to the surface of an electrophotographic photoreceptor provided with a photosensitive layer (trinitrofluorenone) and performing image exposure using an image with halftones as a document, a toner image was formed using a black liquid developer. . On top of this, a transfer base made of glossy paper coated with modified vinyl acetate resin (manufactured by Denka Co., Ltd., ASRCH-09) in a film thickness of 10 .mu.m was layered and thermocompression bonded at 180.degree. After allowing this to cool at room temperature, the photoreceptor and transfer base were separated, and the toner image was completely transferred to the transfer base.

Furthermore, the image obtained on the transfer base was excellent in image contrast and gradation reproducibility, and was extremely clear with sufficient gloss.

Example 2 Using the same electrophotographic photoreceptor as in Example 1 above, Example 1
A color electrophotographic image was obtained by repeating the same electrophotographic process three times (yellow, magenta, cyan). On top of this, acrylic modified alkyd resin (manufactured by Hitachi Chemical Co., Ltd.) is applied on glossy paper.

A transfer base coated with Phthalkid V-913-A'') to a thickness of 20 .mu.m was placed on top of the transfer base, and thermocompression bonded at 150.degree.

After allowing this to cool at room temperature, the photoreceptor and transfer base were separated, and the toner image was completely transferred to the transfer base. In addition, the images obtained on the transfer base have excellent image contrast, gradation reproducibility, gloss, etc., as well as extremely good color balance, and the multicolor mixing effect gives the colors depth and clarity. It had a unique color.

Example 3 A color electrophotographic image was obtained on a photoreceptor by the same operation as in Example 2 above. On top of this, a transfer base made of glossy paper coated with an acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., BR-105) to which 20% of a plasticizer (dibutyl phthalate) had been added with a 20 μm thick paste was superimposed and thermocompression bonded at 150°C. After this was allowed to cool at room temperature, the photoreceptor and transfer base were peeled off.

As a result, the toner image is completely transferred to the transfer base side, showing excellent characteristics such as image contrast, gradation reproducibility, glossiness, and 9-color balance, resulting in an image with deep and vivid colors. It was done. Furthermore, due to the effect of the plasticizer, the transfer base had sufficient flexibility.

〔Effect of the invention〕

As is clear from the above description, in the present invention,
Since the toner image on the photoreceptor is transferred using a transfer base having a layer made of thermoplastic resin, the toner image on the photoreceptor can be almost completely transferred.

Therefore, the transferred image has sufficient contrast and good gradation reproducibility can be obtained. Further, the image can be fixed at the same time as the transfer, and an image with excellent gloss can be obtained.

In particular, since a color image created by overlapping colors can be transferred in one go without destroying the color balance, there is no need to align each color during transfer, and a good image without color shift can be obtained. It is also possible to increase the speed of the device.

Further, according to the present invention, since the toner image is wrapped in the thermoplastic resin, in the case of a color image, a multicolor mixing effect appears, and an image with deep and clear colors can be obtained.

[Brief explanation of the drawing]

1st V! FIGS. J to 5 are schematic cross-sectional views showing an example of the transfer method according to the present invention according to the process order. l...Photoreceptor 6...Toner image 7...Thermoplastic resin layer 8...Transfer base

Claims (1)

[Claims] A toner image formed by electrophotography on a photoreceptor and a transfer base having a layer made of a thermoplastic resin are superimposed and thermocompression bonded, and then the photoreceptor and the transfer base are peeled off. A transfer method comprising transferring the toner image onto a transfer base.