JPH08190240A - Multicolor image forming method - Google Patents

Abstract

PURPOSE: To provide a multicolor image forming method capable of obtaining an excellent image without disturbance of a multicolor image, in a multicolor image device using a belt-like transfer body having a big change in curvature. CONSTITUTION: In the multicolor image forming method for performing processes for forming a latent image corresponding to each color on a latent image carrier 3, developing the latent image thereon with a developer corresponding to the color, transferring the developed image to the belt transfer body 6 and removing toner remaining on the latent image carrier, in each color several times and then, transferring the multicolor images formed on the belt-like transfer body 6 to a second transfer body 9 all together, such developer consisting of toner grain incorporated with 5-30wt.% colorant is used. Moreover, the pile height of a toner image on the belt transfer body 6 is specified to <=0.28mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming method for forming a multicolor image by superposing toner images on a belt transfer member.

[0002]

2. Description of the Related Art Conventionally, when a multicolor image is obtained by an electrophotographic method, a method has been used in which charging, exposure, development and cleaning are repeated to sequentially superimpose each color. In the case of this method, a multicolor image is formed on the drum-shaped photosensitive member or the transfer drum, and it is possible to sufficiently carry the toner amount on such a hard drum.
There is a problem that the copying apparatus becomes large in size to accommodate the drum. In order to solve this problem, it has been attempted to downsize the copying machine by using a flexible belt-shaped transfer body. On the other hand, with respect to the toner, when forming a multicolor image, the amount of the colorant in the toner is reduced in order to improve the gradation of the color. It is necessary to use a large amount of toner, and as a result, the pile height of the toner image is increased in the above-described method of sequentially overlapping colors. However, when the pile height of the developed toner image is high, the toner layer close to the transfer member may be incompletely transferred, and the toner may remain, resulting in defective transfer, whereby the desired color tone may not be obtained. In addition, hollow images called hollow characters were often a problem. This tendency is particularly remarkable in a small-sized copying machine that uses a belt-shaped transfer body as a transfer body. Also,
When the belt-shaped transfer body rotates, there is a change in the curvature, which causes the toner particles to slip, which causes image disturbance.In addition, it affects the change in developability due to environmental changes and developer deterioration. However, there is a problem that the image is not stable during continuous transfer.

[0003]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems in the prior art. An object of the present invention is to provide a multicolor image forming method capable of obtaining a good image in a multicolor image device using a belt-shaped transfer body having a large change in curvature without disturbing the multicolor image. is there.

[0004]

The multicolor image forming method of the present invention comprises a step of forming a latent image corresponding to each color on a latent image bearing member, and developing the latent image on the latent image bearing member according to the color. The process of developing with a developing agent, the process of transferring the developed image to the belt transfer body, and the process of cleaning the residual toner on the latent image carrier are repeated multiple times for each color, and then belt-shaped transfer A multi-color image formed on a body is collectively transferred onto a second transfer body, and in one embodiment thereof, a toner containing 5 to 30% by weight of a colorant as a developer. It is characterized in that one containing particles is used. Another embodiment of the present invention is characterized in that the pile height of the toner image on the belt transfer body is set to 0.28 mm or less.

The present invention will be described in detail below.
The multicolor image forming method of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image forming apparatus for carrying out the present invention. The document on the platen is read by the reading unit 1.
Are color-separated and converted into image signals. Photoconductor 3
Is uniformly charged on the surface by the first charger 4, and then the laser beam modulated by the laser scanning optical device 2 according to the image information of the first color is applied to the photoconductor 3, whereby the photoconductor 3 is irradiated. An electrostatic latent image of the first color is formed on 3. Next, the electrostatic latent image of the first color on the photoconductor 3 is developed by the developing device 5 with the toner of the first color to be visualized, and the toner image of the first color is formed. The first-color toner image formed on the photoconductor is conveyed to the transfer portion as the photoconductor 3 rotates. At this time, the transfer belt 6 is separated from the surface of the photoconductor as shown in FIG. The image passes through without being disturbed. The fur brush 7 is also separated from the surface of the photoconductor, and the image passes without being disturbed. The photoconductor is recharged again by the first charger 4 and is developed with the second color toner by the laser scanning optical device 2 to form two color toner images on the photoconductor. Similarly, after the toner images of the third and fourth colors are formed on the photoconductor, the transfer belt 6 is brought into pressure contact with the photoconductor at the same timing as the position of the toner image and the recording material conveyance by the resist rolls 8, and the second The toner image is transferred onto the recording material 10 by the charger 9. The recording material 10 on which the toner image is transferred is conveyed while being attached to the transfer belt, separated by curvature separation, fixed by the fixing device 11, and discharged.

Next, the toner used in the developer used in the present invention will be described. The toner is mainly composed of a binder resin and a colorant. It is necessary that the colorant is contained in the toner in the range of 5 to 30% by weight. It is preferably at least 8% by weight. When the content of the colorant is lower than 5% by weight, the pile height of the toner image becomes large and the transfer failure occurs. Further, the gloss difference between the high-developed area and the low-developed area becomes large, resulting in an image having a glossy portion and a matte portion, and a calm, non-glossy image cannot be obtained. On the other hand, if it is more than 30% by weight, the manufacturability is deteriorated, the graininess in the low-developed area is lowered on the image, a clear image cannot be obtained, and the cost is increased.

The binder resin used is styrene,
Styrenes such as chlorostyrene, monoolefins such as ethylene, propylene, butylene and isobutylene, vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and other vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate. , Octyl acrylate, dodecyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, todecyl methacrylate, etc. α-methylene aliphatic monocarboxylic acid esters, vinyl methyl ether, vinyl ethyl ether, Homopolymers and copolymers of vinyl ethers such as vinyl butyl ether, vinyl methyl ketone, vinyl hexyl ketone, vinyl ketones such as vinyl isopropenyl ketone and the like can be exemplified. Are polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyethylene, polypropylene. be able to. Further, polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like can be mentioned. In particular, polyester resin is preferably used in terms of transparency.

Further, as the colorant, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, copper phthalocyanine, malachite green oxalate, lamp black, rose bengal. , C.I. I. Pigment Red 4
8: 1, C.I. I. Pigment Red 122, C.I. I.
Pigment Red 57: 1, C.I. I. Pigment Yellow 97, C.I. I. Pigment Yellow 12, C.I.
I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 etc. can be mentioned.

In addition to the above components, the toner may further contain a charge control agent, a cleaning aid, a fluidity accelerator, etc., if necessary. In the present invention, the above toner may be used as a one-component developer or may be mixed with a carrier and used as a two-component developer.

In the present invention, when the toner image is transferred onto the belt-shaped transfer material, it is preferable that the pile height is 0.28 mm or less. Pile height is 0.
If the height is higher than 28 mm, the transfer of the toner layer is incomplete and the toner remains, causing a transfer failure. In order to reduce the pile height to 0.28 mm or less, the content of the colorant in the toner may be set to 5% by weight or more, and the developing bias may be controlled during development to reduce the developing amount. Particularly preferably, it is 0.20 mm or less. An object of the present invention is to provide a developer that suppresses transfer failure and is not easily affected by fluctuations in developability.

[0011]

The pictorial color toner is used with a low colorant content in order to improve the gradation reproducibility and graininess, and causes a transfer failure at a place where the toner pile height on the transfer body is high. Although there is a problem that a desired color tone cannot be obtained, in the present invention, since the content of the colorant in the toner is in the range of 5% by weight to 30% by weight, even if an image portion having a high density is developed. The pile height of that part does not increase. Therefore, the transfer failure does not occur. Further, in developing, the absolute amount of toner to be developed can be small, and as a result, the influence of fluctuation in developability becomes smaller than in the past. Further, by increasing the content of the color material, the gloss becomes relatively low, and conventionally, the difference in gloss between the high-developed area and the low-developed area becomes small, resulting in an image having a uniform matte portion and no calm gloss. The image can be obtained.

[0012]

EXAMPLES The present invention will be described below with reference to examples.
The embodiments are not limited in any way.
In the following description, all "parts" mean "parts by weight". (Toner) (1) Polyester (terephthalic acid / bisphenol A)
Condensate) (MW = 10,000)
70, 80, 90, 95, 96, 98 parts Colorant: C.I. I. Pigment Yellow 17 30, 20, 10, 5, 4, 2 parts (2) The colorant is C.I. I. Pigment Red 57: Same as (1) except that it is changed to 57: 1. (3) The colorant is C.I. I. Pigment Blue 15: 3 Same as (1) except changed. For each of the toners (1), (2) and (3), the total amount of polyester and colorant is 100.
A toner was prepared by blending so that the amount of the toner would be 1 part. To 100 parts of the obtained toner particles having an average particle size of 7 μm, 1 part of silicon oxide fine powder was added and mixed with a Henschel mixer.

(Carrier) Styrene-butyl methacrylate copolymer (MW = 80,000) 23 parts Magnetite 75 parts Triphenylmethane dye 2 parts The above components are kneaded, ground and classified to have an average particle diameter of 46 μm.
Got a career. (Developer) The above toner and carrier were mixed in a weight ratio of 10: 100 to prepare a developer.

(Test) The developers of the respective colors obtained in the above examples were combined according to the content of the colorant, and the copying machine (A-co
A modified image of a belt transfer type of lor 635 (manufactured by Fuji Xerox Co., Ltd.) was used to produce a copy image for evaluation. The results are shown in Table 1.

[0015]

[Table 1] As shown in Table 1, according to the present invention, a good copy image can be formed.

[0016]

In the image forming method of the present invention, since a large amount of the coloring agent as described above is used as the developer, the amount of toner on the belt transfer member can be reduced and the image disturbance can be prevented. Further, even if the amount of toner is small, the density reproducibility is improved, line thickening can be prevented, and a sharp image can be obtained. Further, by setting the pile height of the toner image on the transfer member to 0.28 mm or less, it is possible to prevent bleeding on the image. Therefore, it is possible to obtain a multicolor image by using a small-sized apparatus using the belt transfer body.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus for carrying out the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reading part, 2 ... Laser scanning optical device, 3 ... Photosensitive member, 4 ... 1st charging device, 5 ... Developing device, 6 ... Transfer belt, 7
... fur brush, 8 ... resist roll, 9 ... second charging device, 10 ... recording material, 11 ... fixing device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masanori Ichimura 1600 Takematsu, Minamiashigara City, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (2)

[Claims] 1. A step of forming a latent image corresponding to each color on a latent image carrier, a step of developing the latent image on the latent image carrier with a developer corresponding to the color, and a belt of the developed image. The step of transferring onto the transfer body and the step of cleaning the residual toner on the latent image carrier are repeated a plurality of times for each color, and then the multicolor image formed on the belt-like transfer body is transferred to the second transfer. A method for forming a multicolor image in which the particles are transferred onto a body all at once, wherein a developer containing toner particles containing 5 to 30% by weight of a colorant is used. 2. The pile height of the toner image on the belt transfer member is set to 0.28 mm or less.
The multicolor image forming method described.