JPH0614190B2 - Color image forming method - Google Patents

Description

The present invention relates to an image forming method, and more particularly to an image forming method capable of easily forming a high quality color image.

As a method of transferring a toner image from an electrophotographic photosensitive member to a transfer target, electrostatic discharge is performed by directly attracting and transferring the toner to the transfer target by performing a direct-current corona discharge having a polarity opposite to that of the toner charge from the back surface of the transfer target. The transfer method is simple and is used in electrophotographic copying machines. This method has a problem of so-called background stain, in which toner remains on the non-image portion, or a problem of change in image density due to the toner on the photoconductor not being completely transferred at the time of transfer. Particularly in the latter case, the photoconductor needs to be cleaned, and the surface of the photoconductor is easily scratched during the cleaning. The reason why the background stain occurs and the transfer efficiency is poor is that there is a physical interaction force other than the electrostatic attraction between the photoconductor and the toner, and the toner may adhere to the non-image area. , It seems that transcription is inhibited.

Although such a defect does not cause any particular problem when copying a text original such as a document, it poses a serious problem for the purpose of obtaining a color image. That is, the background stain is observed as cloudiness of the color, and the instability of the transfer efficiency is sensitively observed as the change of the color tone. Further, after the toner is electrostatically transferred to the transfer target, the transfer target is peeled off from the photoconductor, but since it is electrostatic transfer, the physical interaction between the photoconductor and the toner and the transfer target is caused. There is also a problem that the toner and the transfer-receiving member are difficult to be separated from the photosensitive member due to the acting force. The present inventors not only do not adversely affect the performance of the electrophotographic photoconductor even if a thin layer of easily peelable material is provided on the surface of the photoconductor, but also provide an easily peelable material layer on the surface of the photoconductor. Dirt is reduced, and even if there is dirt, it can be easily removed,
In addition, the transfer efficiency during electrostatic transfer is greatly improved, the toner transfer amount is stabilized, the color tone reproducibility is improved, and the releasability of the transferred material from the photoconductor after the toner transfer can be improved. The present invention has been discovered and arrived at the present invention.

That is, in the present invention, a latent image is formed in a pattern by charging and pattern exposing an electrophotographic photoreceptor, then developing with toner, and the obtained image is electrostatically transferred to another transfer target. The gist of the image forming method is to use an electrophotographic photoreceptor having an easily peelable material layer on the surface thereof.

It is presumed that the physical interaction force between the easily peelable material layer and the toner in the present invention is smaller than the physical interaction force between the photoreceptor and the toner which are not subjected to the peeling treatment.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross section of an electrophotographic photoreceptor according to the present invention.
At least the surface of the base 1 is a conductive base, and in addition to a conductive material as a whole, such as metal, the surface of an insulating material such as paper, glass, or plastic is subjected to a conductive treatment or a conductive material is laminated. The material can be used. In any case, it is desirable that the structure is such that the ground electrode can be easily taken from the photoconductive photosensitive layer, and it may be in the shape of a plate or a cylinder.

The material of the photoconductive photosensitive layer 2 is amorphous selenium, a composition of cadmium sulfide and a resin binder, a composition of zinc oxide and a resin binder, amorphous silicon, cadmium sulfide, a composition of cadmium sulfide, cadmium carbonate and a resin binder. object,
In addition to inorganic materials such as organic photoconductors such as poly-N-vinylcarbazole, function-separated photoconductors having a multilayer structure, any known electrophotographic photoconductor having photoconductivity can be used. The contacting method, thickness and the like may be in accordance with known conditions.

The material of the easily peelable material layer 3 may be any material as long as it has a peeling property, and for example, a silicone resin, a fluororesin, an aminoalkyd resin, and casein can be used. Taking silicone resin as an example, addition type or condensation type silicone rubber for release paper cured with a curing catalyst, silicone oil containing -SiH cured with an addition type curing catalyst such as chloroplatinic acid, etc. Other than these, it is possible to use those obtained by curing various silicone resins by a known method, such as silicone vulcanized rubber, silicone rubber for release paper, and the like, which have been peroxide vulcanized. When the silicone resin is used, the silicone resin stock solution may be diluted to a concentration such that it can be easily coated, a curing agent may be added, and then the silicone resin may be coated and cured on the photoconductive photosensitive layer. It may be applied by any means as long as it is available, and wire bar coating, spin coating, roll coating, spray coating, dip coating or the like may be used. As other easily peelable materials, fluororesin, especially polytetrafluoroethylene dispersion or enamel, can be used. The peelability of the easily peelable material layer is also affected by the smoothness of the surface of the photoconductive photosensitive layer. If the surface is smooth, even a thin easily peelable material layer shows sufficient peelability, and if it is a rough surface, it is easily peeled. It is necessary to thicken the conductive material layer. However, making the easily peelable material layer unnecessarily thick causes deterioration of resolution, so the thickness of the layer is 0.01 to 5 μm.
It is preferable that From the above viewpoint, in the case of the binder dispersion type photoreceptor, it is preferable that the surface is smooth. In addition, a primer treatment may be applied to improve the adhesion between the photoconductive photosensitive layer and the easily peelable material layer.

In this case, the primer includes vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β (amino). Ethyl) γ-aminopropyltrimethoxysilane, B-β (aminoethyl) γ
-Aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltris (t-butylperoxy) silane and the like, alone or a mixture thereof, Is a partial hydrolyzate or a partial hydrolyzate thereof; titanium orthoesters such as tetraisopropyl titanate, tetrabutyl titanate and tetra-2-ethylhexyl titanate, titanium chelates such as titanium acetylacetonate and triethanolamine titanate, poly Titanium acylates such as hydroxytitanium stearate and polyisopropoxytitanium stearate, organic titanium compounds such as the above or a mixture thereof; aluminum isopropylate, Sec-Butoxyaluminum diisopropylate and other aluminum alcoholates, ethyl acetoacetate aluminum diisopropylate and other aluminum chelate compounds, the above organoaluminum compounds alone or in mixtures thereof; other organometallic compounds; the above silanes and Examples include a mixture of organometallic compounds.

The coating method may be a method capable of uniform coating such as dilution to an appropriate concentration as required, wire bar coating, spin coating, roll coating, spray coating, dip coating, and the like.

An example of electrostatic transfer after forming a toner image using the electrophotographic photosensitive member according to the present invention obtained as described above is shown in FIGS. 2 to 6. For convenience of explanation, the charge is shown as negative, but it goes without saying that the chargeability is determined by the type of photoconductive photosensitive layer used.

To the electrophotographic photoreceptor according to the present invention, a corona discharge electrode 4 is moved in the direction of the arrow by a corona discharge device 4 to give a corona discharge charge, as shown in FIG. To form an electrostatic latent image. After developing the electrophotographic photosensitive member on which the electrostatic latent image of FIG. 3 is formed by using positively charged toner, an electrophotographic photosensitive member having toner temporarily attached as shown in FIG. 4 is obtained. 8 in FIG.
By negatively charging the transferred material from the back side, the toner on the photoconductor moves to the transferred material 8 and peels off the transfer material, so that the toner is transferred onto the transferred material 8 as shown in FIG. An image 7 is obtained, and after fixing the image 7 with heat, solvent vapor, pressure, etc., a color image is obtained by performing each of the above steps a plurality of times using toner of each color. Depending on the type of toner, as shown in FIG. 4, there is a case where scumming is seen when the toner is temporarily attached. In this case, it is possible to remove the toner by removing the toner in the non-image area by applying vibration from the back surface of the photosensitive plate or blowing air from the surface. Alternatively, it can be removed by brushing with a magnetic brush containing no toner. In the case where scumming occurs using a wet toner, scumming can be removed by rinsing with a linear petroleum-based insulating solvent or the like. According to the method of the present invention described above, a high-quality image can be obtained because of less scumming and good transfer efficiency, and since there is almost no deterioration in charging characteristics due to the installation of the easily peelable material layer, the easily peelable material layer It is possible to use the same electrophotographic process as in the case of using the electrophotographic photosensitive member before the installation, and there is an advantage that no special process is required. Further charging → exposure →
A color image can be easily obtained by repeating the steps of development → fixing using toners of different colors.

Examples will be given below to more specifically describe the present invention. Hereinafter, “part” means “part by weight”.

Example 1 The solution having the above ratio was dissolved by stirring at 80 ° C., then rapidly cooled to 10 ° C. with stirring, and a linear petroleum solvent (manufactured by Exxon Chemical,
Then, 300 parts of Isopar H) was added and after decantation, 300 parts of the petroleum solvent was further added to produce a black wet toner. Also, instead of carbon black, use Sumika Print Blue GNOPP (Sumitomo Kasei KK), Seika Fast Carmine-1480 (Dainichi Seika KK), or Chromo Fine Yellow AF1100 (Dainichi Seika KK) in the above solution. In the same manner as in the addition of the amounts, cyan, magenta, and yellow wet toners were obtained.

On the other hand, the photoconductor was prepared as follows.

Zinc oxide (Sakai Chemical Industry, SAZEX # 2000) with 0.01% rose bengal admixed with silicone varnish (Shin-Etsu Chemical Industry, KR211) are mixed so that the nonvolatile content is 4: 1, and the nonvolatile content is 30% with toluene. The resulting mixture was diluted with the above solution and dispersed well with ultrasonic waves for 10 minutes, and then applied on an aluminum plate so that the dried coating film had a thickness of 15 μm and dried at 150 ° C. for 3 hours to form a photoconductive layer. Next, a curing agent (Shin-Etsu Chemical Co., Ltd., C-
2) was diluted with silicone oil (KF96L, manufactured by Shin-Etsu Chemical Co., Ltd.) to 3%, and applied on the photoconductive layer so that the dry coating film had a thickness of 3 μm.
It was heated at 2 ° C. for 2 hours for curing to obtain a photoreceptor having an easily peelable layer.

The photoreceptor obtained as described above is negatively charged by a normal process, and a yellow halftone plate obtained by color-separating a color original in advance is brought into close contact with the photosensitive member. Dish development is performed using the above to obtain an image free of background stain, and the coated paper is brought into close contact before the solvent is completely dried (note that in FIG. However, this means that the transfer target 8 and the photoconductor are brought into close contact with each other.) When the pins are aligned and negatively charged from the back side of the coated paper, almost 100% of the toner on the photoconductor is transferred onto the coated paper. The magenta image was then overlaid on the yellow image using a magenta plate and magenta toner. Similarly, cyan and black images were superposed to obtain a good color image. Since the black toner causes a slight background stain as compared with the other toners, the background stain is removed by rinsing with Isopar H before the transfer.

Example 2 Instead of the trial toner, a dry color toner manufactured by Tokyo Ink was used, and similarly, a halftone image of each color was obtained on the photosensitive plate of Example 1 after the charging exposure and the magnetic brush development method. In the case of the dry toner, background stain was generated as compared with the trial wet toner of Example 1, but the background stain could be removed by rubbing 2-3 times with a magnetic brush containing no toner. Further, the ground stains could be removed by applying vibration from the back surface. A good color image was obtained by sequentially transferring this onto coated paper with a pin system and heating and fixing.

Example 3 A ZnO powder having 0.15% of rose bengal adsorbed thereon was used to prepare a liquid having the following composition.

The liquid having the above composition was dispersed for 30 minutes using ultrasonic waves. After cooling, the mixture was filtered using a screen mesh and 6 parts of an isocyanate curing agent (Coronate 2031, made by Nippon Polyurethane) was added and mixed well. The above liquid was applied to the aluminum foil surface of a multilayer sheet obtained by dry laminating a 12 μm thick aluminum foil on a 100 μm polyester film, using a Whaler coater, to a thickness of 10 to 15 μm. After being left for 20 minutes, a solution having the following composition was used as a primer by a whaler coater and heated at 100 ° C. for 20 minutes in an oven.

Next, the following composition liquid was prepared as a release layer coating material.

The composition was coated on a sheet coated with ZnO and a primer with a whaler coater and heated in an oven at 100 ° C. for 1 hour to obtain a photoreceptor. The obtained photoconductor was negatively charged and then mounted on a laser blotter manufactured by Cytex Co., Ltd., and a halftone image was directly drawn. This was developed with the wet toner of Example 1, similarly transferred to coated paper and dried, and a good color image was obtained by repeating the above steps.

Example 4 The thickness of the coating film after drying a silicone-based primer (KBP41, manufactured by Shin-Etsu Chemical Co., Ltd.) on the surface of a cylindrical amorphous Se photoconductor was 0.1 μm.
After dip coating and drying, leave it at room temperature for 1 day, and then apply silicone for release paper (KS705F, manufactured by Shin-Etsu Chemical Co., Ltd.) so that the coating film after drying becomes 1μ. did.

The photoconductor thus obtained was positively corona-charged, developed with the negatively-charged dry color toner manufactured by Tokyo Ink Co., Ltd. by the method of Example 2, and transferred by positive corona-charging. I got a color image.

[Brief description of drawings]

FIG. 1 is a sectional view of an electrophotographic photosensitive member used in the present invention, and FIGS. 2 to 6 are sectional views showing steps of forming an image using the electrophotographic photosensitive member of FIG. . 1 ... Support 2 ... Photoconductive photosensitive layer 3 ... Release layer 4 ... Corona charging device 5 ... Electric charge 6 ... Light 7 ... Toner 8 ... Transferred material

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-150779 (JP, A) JP-A-55-17195 (JP, A) JP-A-50-98329 (JP, A) JP-A-50- 114226 (JP, A) JP-A-50-137740 (JP, A)

Claims (1)

[Claims] 1. An electrophotographic photosensitive member is charged and subjected to pattern exposure according to color separation information to form a latent image in a pattern, and then developed with toner, and the obtained image is transferred to another transfer target. In the color image forming method of electrostatically transferring to the body,
A method for forming a color image, characterized in that an electrophotographic photosensitive member having an easily peelable material layer having a film thickness of 0.01 to 5 μm provided on the surface thereof is used.