JP3342198B2 - Full-color image forming apparatus and full-color image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a full-color image forming apparatus and a full-color image forming method using an electrophotographic method used in copying machines and printers.

[0002]

2. Description of the Related Art Conventionally, a full-color image forming apparatus based on an electrostatographic system is known in which a color image separated into four colors, that is, three colors of yellow, magenta and cyan and black is added to a laser beam on a photosensitive drum. A color image is formed by a latent image process of exposing and drawing with a beam, a developing process of adsorbing toner on a photosensitive drum, a transfer process of transferring toner to recording paper, and a fixing process of fixing toner. For example, as an application example of such a color image forming apparatus, a color copying apparatus based on an electrostatographic method can convert a color image original into red (R), green (G),
The color separation into three colors of blue (B) is performed, read, and converted into CMY density signals, which are complementary colors of RGB, to obtain subtractive color signals by toner. Normally, the density signal YMC 3
A black (K) signal is generated to the signal, and undercolor removal for replacing black with the CMY three-color mixture by adding black further is performed, and an image is formed with four color toners of yellow, magenta, cyan, and black. You.
The effect of adding such a black toner to remove the undercolor is generally to improve the density reproducibility in the high-density area of the image, to stabilize the color reproducibility in the achromatic area of the image, to improve the sharpness of the image, and to reduce the toner consumption. It is known that running costs can be reduced.

Further, in color copiers (color printers), since the image quality such as color vividness is given priority, the melting point of the toner is set lower than that of the black and white toner. The image is a glossy image mixed well.

On the other hand, in recent offices, color copying machines and color printers have been copying (outputting) black-and-white documents and color documents in a mixed manner. (Monochrome printer) function and cost performance have been required.

A black-and-white copying machine (black-and-white printer) has a simple structure without using oil for fixing and uses a toner having a high melting point because the visibility of characters and line images and the cost performance are prioritized. By fixing the toner without sufficiently melting it, an image with reduced gloss is obtained.

In order to output images having such different characteristics, in a color copying machine (color printer), the black toner used in a conventional black-and-white copying machine (black-and-white printer) is less expensive than the color toner. In some cases.

[0007]

However, as in the above-mentioned conventional example, by using a combination of three color toners and black and white black toner, "during black and white image output" 1) Oil is consumed. 2) The heat conductivity is improved by oil at the time of fixing, the glossiness of the image is increased, and characters and the like are difficult to read. 3) At the time of outputting a color image, 3) an image having both a color area and a black and white area has a drawback similar to that of 2).

Accordingly, an object of the present invention is to output a low-gloss image at a low cost when outputting a black-and-white image, and to obtain a uniform and glossy color image region mixed within one image when outputting a color image. It is an object of the present invention to provide a full-color image forming apparatus and a full-color image forming method capable of achieving both high-quality images and easy-to-view images with reduced gloss in a black-and-white image area.

[0009]

According to the present invention, a full-color image forming apparatus or a full-color image forming apparatus using three colors of magenta, cyan and yellow toners as chromatic toners and black toner as achromatic toners is provided. In the forming method, the chromatic color toner is a wax-containing toner, and the achromatic color toner is a binder having a higher binding strength than a toner containing no wax or the chromatic color toner.
The above object can be achieved by using a toner having a low wax content per 100 parts by weight of the binder resin .

Specifically, in the case of a chromatic toner, the content of the wax is 5 to 100 parts by weight of the binder resin.
It is preferred to contain 50 parts by weight. In the case of an achromatic toner, the upper limit is preferably 30 parts by weight with respect to 100 parts by weight of the binder resin.

[0011] More preferably, the effect is further enhanced by setting the melting temperature of the achromatic toner higher than that of the chromatic toner.

Specifically, the melting temperature is preferably 50 to 80 ° C. for chromatic toners, and 55 to 95 ° C. for achromatic toners.
Is preferred.

Furthermore, more preferably, by forming an image by achromatic toners and at least one color or more chromatic toner achromatic area of the images area, the effect is increased.

[0014] Specifically, in the achromatic region in the images area for achromatic toner amount 1, the amount of chromatic toner 1
It is preferable to be above.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Example 1) "When the chromatic toner is a wax-containing toner and the achromatic toner is a toner containing no wax or a toner having a lower wax content than a chromatic toner"

The following chromatic toners were used.

Magenta: 100 parts by weight of a polyester-based binder having a number average molecular weight of about 3500 is added to a pigment C.I. I. Pigment Red 49, 15 parts by weight of paraffin wax T-550, a charge control agent (hereinafter C)
A agent) was composed of 4 parts by weight of a chromium complex of di-tert-butylsalicylic acid and 0.5 part by weight of silica as an external additive.

Cyan: 100 parts by weight of a polyester-based binder having a number average molecular weight of about 3500, 5 parts by weight of a phthalocyanine pigment, and paraffin wax T-55
0 was used as the CA agent, 4 parts by weight of a chromium complex of di-tert-butylsalicylic acid as the CA agent, and 0.5 parts by weight of silica as the external additive.

Yellow: 100 parts by weight of a polyester-based binder having a number average molecular weight of about 3500 and a pigment C.I. I. Pigment yellow, 5 parts by weight of paraffin wax T-550, and di-te as a CA agent.
A mixture comprising 4 parts by weight of a chromium complex of rt-butylsalicylic acid and 0.5 parts by weight of silica as an external additive was used.

The following achromatic toners were used.

Black: 5 parts by weight of carbon black in 100 parts by weight of a polyester-based binder having a number average molecular weight of about 3500, 4 parts by weight of a chromium complex of di-tert-butylsalicylic acid as a CA agent, and as an external additive What consisted of 0.5 part by weight of silica was used.

An image forming experiment was conducted using the above four kinds of toners as a developer in a known non-magnetic one-component developing device.

FIG. 1 is a schematic view of an experimental apparatus for experimenting the present invention.

In FIG. 1, reference numeral 10 denotes a photosensitive drum,
An OPC photosensitive drum is used. The photosensitive drum 10 is uniformly charged to −700 V by the charger 11, and first forms a magenta (M) latent image by exposure 12. In this experiment, since the reversal development method was used, the exposed portion becomes the image portion. The latent image is rotated by rotating the drum 10 in the direction of arrow A.
The developer is conveyed to the developing section where the developing device groups 21 to 24 are
(At this time, the developing device group is slid to the right and left in the figure by a driving system (not shown)). The toner developed on the drum 10 is further conveyed to the transfer unit, which is the closest part to the transfer drum 30, by rotation in the direction of arrow A, fed from the paper feed unit 51 or 52, and Is transferred onto the transfer paper by the electric field of the transfer charger 31 on the transfer paper adsorbed on the transfer paper.
The remaining latent image is erased by the pre-exposure 13 and transported to the charging section again, and the above operation is repeated in the order of cyan, yellow and black, and after the black toner is transferred, the transfer paper is separated from the transfer drum 30. Then, the image is conveyed to the conveyance unit 60 and fixed by the fixing roller 40 having a simple configuration (without an oil application mechanism), an image is finally formed, and the image is discharged to the paper discharge unit 70.

When a black and white image is output, only black is developed in the above operation.

On the other hand, in this case, unlike the other three toners, the black toner does not contain wax, so that the image portion of only the black toner has poor heat conduction to the toner in the fixing portion. As a result, the smoothness on the formed image decreases, and the glossiness decreases. Therefore, in the output of only the black-and-white image, it was possible to obtain a low-cost, easy-to-read black-and-white image with suppressed glossiness. Further, in color image output, the toner contains wax in the color area, so that heat conduction is improved, and a color image with high color gloss, which is well mixed, is obtained. It was possible to obtain a suppressed black and white image that was easy to see.

Further, by appropriately adding a small amount of wax to the black toner as compared with the other three toners,
A good image similar to the above result could be obtained.

(Example 2) "In the toner of Example 1, the melting temperature of the achromatic toner is higher than that of the chromatic toner."

Magenta, cyan, and chromatic toners
The same three toners as those of Example 1 were used for the three yellow toners, and the following black toners were used as the achromatic toners. Regarding the melting temperature, the chromatic toner is 65 ° C., and the achromatic toner is 85 ° C.

Black: 100 parts by weight of a polyester-based main binder having a number average molecular weight of about 10,000, 5 parts by weight of carbon black, and di-tert-
A mixture comprising 4 parts by weight of a chromium complex of butylsalicylic acid and 0.5 part by weight of silica as an external additive was used.

A better image was obtained than the image in Example 1, and the durability in outputting a black and white image was remarkably improved.

(Embodiment 3) "A case where an image is formed in an achromatic region of a color image region using an achromatic toner and at least one chromatic toner"

When only the achromatic toner is used in the achromatic region of the color image region, the glossiness is reduced only in that portion,
There is a case where image quality is deteriorated (for example, hair in a person image).

In this embodiment, the black toner of the second embodiment is used as an achromatic toner in order to form an image in an achromatic region of a color image region using an achromatic toner and at least one chromatic toner. Using the same color toner as in the first embodiment as the chromatic toner, the color toner (cyan + magenta +
(Yellow) was 1 or more, and an image was formed in an achromatic region.

By infiltrating the wax contained in the chromatic toner into the achromatic toner in this way, the thermal conductivity is improved, and at the same time, the chromatic toner is added between the achromatic toners. By dissolving, fixing was performed with the glossiness of the portion improved, whereby a good color image could be obtained.

(Embodiment 4) The chromatic toner in the present invention is not limited to the toner described in Embodiments 1 and 2. For example, a polymerized toner as described below may be used. .

An example of producing a cyan toner will be described as a method for producing a polymerized toner.

Styrene: 185 parts by weight n-butyl acrylate: 15 parts by weight Cyclic rubber: 10 parts by weight [Albex CK-450 (manufactured by Hoechst Japan)] Cyanine Blue 4920 (manufactured by Dainichi Seika): 20 parts by weight Paraffin wax T-550 (Nippon Seiro): 32 parts by weight Initiator [V-601 (Wako Pure Chemical Industries)]: 10 parts by weight

In this example, a monomer system was prepared by heating, dissolving or dispersing at 70 ° C. in a container according to the above-mentioned formulation. Separately, 10 g of aminoalkyl-modified colloidal silica was added to 1200 ml of ion-exchanged water.
The mixture was adjusted to pH = 6 with Cl, 1 g of Na ₂ CO ₃ was further added, the mixture was heated to 70 ° C., and dispersed at 10,000 rpm for 15 minutes using a TK homomixer M type (manufactured by Tokushu Kika Kogyo).

Further, 1.1 g of Al ₂ (SO ₄ ) ₃ was added and 1
Disperse at 0000 rpm for 15 minutes to prepare a dispersion medium,
The above monomer composition is charged and TK at 70 ° C. under a nitrogen atmosphere.
The mixture was stirred at 10,000 rpm for 60 minutes using a homomixer to granulate the monomer composition.

Then, while stirring with a paddle stirring blade, 70
Polymerization was performed at 10 ° C. for 10 minutes. After the completion of the polymerization reaction, the reaction product was cooled, NaOH was added to dissolve the dispersant, and the polymer was filtered, washed with water and dried to obtain a polymerized toner having an average particle size of about 8 μm.

By using such a polymerized toner as a chromatic toner, a structure in which the wax 101 is included in the resin 100 as shown in FIG. However, the durability was significantly improved without impairing the effects of the present invention.

Further, the achromatic toner is not limited to the toner used in the above embodiment. For example, the black toner used in the above embodiments is a non-magnetic toner, but a magnetic toner containing a magnetic material such as magnetite in a toner binder may be used instead.

Since magnetite is an unmelted substance, the melting temperature of a magnetic toner containing it is generally high. In addition, since the magnetite magnetic powder forms fine irregularities on the fixed image, the incident light is easily diffused and reflected, and the glossiness of the image surface is significantly reduced.

Therefore, the effect is more effectively exhibited.

In this embodiment, as a black toner, magnetite was added to 100 parts by weight of a polyester-based main binder having a number average molecular weight of about 10,000.
An image-drawing experiment was conducted using 0 parts by weight, 4 parts by weight of a chromium complex of di-tert-butylsalicylic acid as a CA agent, and 0.5 parts by weight of silica as an external additive.

[0048]

As described above, the chromatic toner is a wax-containing toner, and the achromatic toner is a toner containing no wax or a toner having a lower wax content than the chromatic toner. When outputting a black-and-white image, an image with reduced gloss is output at a low cost.When outputting a color image, a uniform and high-gloss image is obtained in a color image region mixed in one image, and in a black-and-white image region. An easy-to-view image with reduced gloss can be compatible.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an experimental apparatus embodying the present invention.

FIG. 2 is a sectional view of a toner showing a structure of a polymerized toner used in another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 photosensitive drum 11 primary charger 12 exposure 13 pre-exposure 21 to 24 developing device 30 transfer drum 40 fixing device 51, 52 paper feed unit 60 transport unit 70 paper discharge unit 100 resin 101 wax

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takushi Shibuya 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Osamu Iwasaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (56) References JP-A-5-249791 (JP, A) JP-A-6-19204 (JP, A) JP-A-4-204566 (JP, A) (58) Fields studied (Int. Cl. ^7, DB name) G03G 9/09 G03G 9/097

Claims (6)

(57) [Claims] 1. A full-color image forming apparatus using a magenta toner, a cyan toner, and a yellow toner as chromatic toners and a black toner as an achromatic toner, wherein the chromatic toner is a wax-containing toner, and the achromatic toner is a wax. Per 100 parts by weight of the binder resin compared to the toner not containing
A full-color image forming apparatus, wherein the toner has a low wax content. Wherein said melting temperature of achromatic toner, a full-color image forming apparatus according to claim 1, characterized in that above the melting temperature of the chromatic <br/> color toner. Wherein said achromatic toners achromatic area of the images area, full-color image formation according to claim 1 or 2, characterized by forming an image by said chromatic toner of more than at least one color apparatus. 4. An image forming method for forming a full-color image using a magenta toner, a cyan toner, and a yellow toner as chromatic toners and a black toner as an achromatic toner, wherein the chromatic toner is a wax-containing toner. The achromatic toner is a wax resin- free toner or a chromatic toner,
A full-color image forming method, wherein a toner having a low wax content per 100 parts by weight is used. Wherein said melting temperature of achromatic toner, a full-color image forming method according to claim 4, characterized in that above the melting temperature of the chromatic <br/> color toner. Said achromatic toners achromatic area of 6. images area, full-color image formation according to claim 4 or 5, characterized by forming an image by said chromatic toner of more than at least one color Method.