JPH11149193A - Color image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color image forming method enabling good coloring without causing any problem on dispersibility of coloring agents into thermoplastic resins, good in fixability and transparence, high in color reproduction performance and good in environmental stability by selecting an appropriate coloring agent. SOLUTION: The color image is formed by using plural color toners, and at least one of the plural color toners to be used contains a thermoplastic resin as a main component and specified dyes as coloring agents, and a yellow toner to be used is embodied by methine type dyes and a magenta toner and a cyan toner are embodied by anthraquinone-based dyes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method used in a color copying machine, a color printer and the like.

[0002]

2. Description of the Related Art Conventionally, as one of the color image forming methods, an electrophotographic method using a color toner has been known. 2. Description of the Related Art There is known an apparatus that reproduces color on an image recording medium such as plain paper using a color toner.

The above-mentioned electrophotography generally forms an image by the following steps.

First, an electrostatic latent image is formed on a photoreceptor made of a photoconductive material by irradiating the photoreceptor with light information according to image information by various methods.

Next, the electrostatic latent image formed on the photoreceptor is developed as a toner image with a charged toner, and the toner image is transferred to an image recording medium (such as plain paper or an intermediate transfer member). The image is transferred and the image is fixed on plain paper using a heat fixing device.

In the above-described color image forming method using electrophotography, the electrostatic latent image formed on the photoreceptor corresponds to image information separated into each of yellow, magenta, cyan, and black. And develops the toner of the same color as the respective image information. The color image is formed by repeating this developing step four times in total for each color.

In this type of color image forming method using electrophotography, it is necessary to superpose four colors on a photosensitive member or an intermediate transfer member on which an electrostatic latent image is formed. However, in any case, a photoreceptor and an intermediate transfer member are required, and it is difficult to reduce the size of the color image forming apparatus due to the necessity of a space for accommodating them.

Therefore, in order to reduce the size of the color image forming apparatus, it is necessary to print directly on plain paper or use an image forming method that does not pass through any of the photoconductor and the intermediate transfer body. As an image forming method capable of realizing this, a method of directly controlling the passage of toner in an opening having an electrode portion around the same, that is, a toner flow direct control method has been proposed.

Specifically, the toner flow direct control method is to form a plurality of fine openings (hereinafter, referred to as apertures) as toner passing portions in a flexible insulating sheet. Electrodes such as copper foil (hereinafter referred to as control electrodes)
Are formed corresponding to the respective apertures, and the voltage applied to the control electrodes is controlled in accordance with an image signal, thereby recording an image on plain paper or the like. A toner image is formed at an arbitrary position on a medium.

Further, in the above-described various color image forming methods using color toners, a total of four image forming steps are performed for each color toner, but the fixing step on plain paper is usually performed once. is there. Therefore, on the plain paper or the like on which a color image has been formed after the image forming process has been performed four times, up to four colors of color are superimposed. In order to fix such a large amount of toner satisfactorily, the fixing method, the toner material, particularly the thermoplastic resin as the main component and the material of the colorant added thereto The choice is very important.

Further, in order to make it possible to visually confirm the color of the toner in the lowermost layer, the toner of the lowermost layer among the superimposed toners is not concealed by the toner of the uppermost layer. In addition, the transparency of the fixed toner is required, and in order to maintain the color reproducibility of the document, the dispersibility and coloring power of the colorant are required.

[0012]

However, in a conventional color image forming method using a color toner,
A toner using a pigment as a colorant has been used. This type of color toner is manufactured by dispersing a pigment in a thermoplastic resin, which is the main component.However, if the dispersibility is poor, the transparency is impaired, the saturation is reduced, and the color reproducibility of the image is reduced. Inhibit. In addition, since the dispersibility of the pigment affects the triboelectric charging property of the toner, the toner having poor pigment dispersion varies in the charge amount of the toner depending on the temperature and humidity, and lacks environmental stability regarding the quality of the formed image.

Further, if the dispersibility of the pigment in the thermoplastic resin as the main component is too high, the thermal characteristics of the toner are affected, and the thermal fixability of the toner is deteriorated. That is, the original melt viscoelasticity of the thermoplastic resin, which is the main component used in the toner, is changed by making the dispersibility of the pigment too high, and the melt viscosity of the thermoplastic resin is increased. A so-called cold offset occurs at a fixing temperature (around one hundred and several tens of degrees Celsius) which is widely used in the method, and satisfactory fixing cannot be performed.
Therefore, in order to fix the image onto plain paper satisfactorily, the fixing temperature must be set much higher than that of the conventional electrophotographic method, and the manufacturing cost of the color image forming apparatus is increased.

In a color image forming apparatus, in principle, all color reproductions are performed in three colors of yellow, magenta, and cyan.
Although it can be performed by subtractive color mixing with primary colors, in reality, the color reproduction range and color are determined by the spectral characteristics when the pigment is dispersed in the thermoplastic resin and the color mixing when the toners of different colors are superimposed on each other. Since the degree is reduced, faithfully reproducing the color of the document still has many problems.

The present invention has been made in order to solve the above-mentioned problems, and enables appropriate coloring without making dispersibility in a thermoplastic resin a problem by selecting an appropriate coloring agent. It is an object of the present invention to provide a color image forming method having good fixability and transparency, high color reproducibility, and good environmental stability.

[0016]

In order to achieve this object, a color image forming method according to claim 1 of the present invention comprises:
A color image is formed using a plurality of color toners, and at least one of the plurality of color toners includes:
It is characterized by using a resin containing a thermoplastic resin as a main component and a dye as a coloring agent.

Dyes have a higher chroma than pigments, and when used as a colorant in toners, can be colored well without worrying about their dispersibility in thermoplastic resins. And the color of the document can be faithfully reproduced. Further, since good transparency can be ensured, it is suitable not only for color reproducibility but also for output to an OHP sheet or the like. Further, the thermoplastic resin, which is the main component of the toner, can be colored without applying a mechanical stress, so that the inherent viscoelasticity of the thermoplastic resin is exhibited, so that the fixing property is improved.

According to a second aspect of the present invention, there is provided a color image forming method.
Use a yellow toner, a thermoplastic resin as the main component, and a methine dye as a colorant.Magenta and cyan toners, a thermoplastic resin as the main component, and an anthraquinone It is characterized by using a dye as a colorant.

That is, by using the above-mentioned specific dye as a coloring agent, the saturation is higher than that of the pigment, the thermoplastic resin particles can be colored at a high concentration, and the amount added to the toner is smaller than that of the pigment. Therefore, a color image having a high density can be obtained, so that a clear color image can be formed and a color image forming method excellent in environmental stability can be provided.

According to a third aspect of the present invention, there is provided a color image forming method.
As the thermoplastic resin, use is made of polymer particles synthesized from a monomer and a polymerization initiator, and a toner in which the polymer particles are dyed with a colorant or a solution in which the colorant is dissolved or dispersed in a solvent. It is characterized by: That is, since a toner in which polymer particles having a very sharp particle size distribution are dyed with a specific dye is used, the charge amount distribution of the toner becomes sharp and the developability is improved. Can be formed.

According to a fourth aspect of the present invention, there is provided a color image forming method comprising:
An electrode array formed by arranging a plurality of toner passage portions on a flexible insulating sheet in a direction intersecting the conveying direction of the image recording medium and forming an electrode in each of the toner passage portions. An image forming unit comprising: a toner supply unit for supplying toner to the toner passage section; and an electrode driving circuit for individually controlling a voltage supplied to each electrode of the electrode array. A color image is formed by adhering the toner on the image recording medium using the image forming unit for each color. According to this color image forming method, since the adhesion of the toner to the image recording medium is directly controlled in accordance with the image information, the image stain on the white background and the margin is small, and a high-resolution color image with clear color development is obtained. Can be formed, and the size of the color image forming apparatus can be reduced.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

An image forming apparatus 1 shown in FIG. 1 is a color image forming apparatus using a direct toner flow control method for use in a color image forming method according to an embodiment of the present invention.

The image forming apparatus 1 includes a main body frame 2
The paper cassette accommodating section 3, the paper transport mechanism 10, the fixing mechanism 30, and four image recording units 40A to 40A
D, four sets of back electrodes 8A to 8D, and a transfer unit 8
0, and a control unit 70, and are configured to form a color image on a sheet P as an image recording medium.

A paper cassette 4 containing a plurality of papers P is removably mounted in the paper cassette housing section 3 arranged below the main frame 2.

On the upper part of the main body frame 2, there is provided a paper discharge tray 5 for receiving the paper P after image formation discharged through the paper transport mechanism 10.

The paper transport mechanism 10 includes a paper feed roller 1
1, transport rollers 12 to 15, paper guides 21 and 22, and a roller drive mechanism (not shown) for driving the paper feed roller 11 and the like. It is configured to be conveyed toward.

The fixing mechanism 30 comprises a heating roller 31 containing a halogen lamp and a pressing roller 83.

As shown in FIG. 2, the image forming apparatus 1 includes an image forming unit 40A for forming a yellow pixel using a yellow toner 6a, and a magenta toner 6a.
b. Image forming unit 40 for forming a purple-red pixel by b
B, an image forming unit 40C that forms green and blue pixels with cyan toner 6c, and an image forming unit 40D that forms black pixels with black toner 6d. The image forming units 40A and 40A
The set B and the set of image forming units 40C and 40D are symmetrically arranged via the transfer unit 80, as shown in FIG.

The transfer unit 80 is configured as follows.

Four image forming units 40A to 40D
, Four sets of back electrodes 8A to 8D are disposed so as to face the four sets of image forming units 40A to 40D with the intermediate transfer member 81 interposed therebetween.

The driving roller 82 and the pressing roller 83
Is provided with an endless belt-shaped intermediate transfer member 81 on the back electrode 8A.
To 8D. The drive roller 83 is driven by a motor (not shown),
The intermediate transfer body 81 is transported in the direction of the arrow in the figure. The pressing roller 83 and the heating roller 31 constitute the fixing mechanism 30, and pressurize the intermediate transfer body 81 and the sheet P while heating between the pressing roller 83 and the heating roller 31. Transfer the toner on the intermediate transfer member 81 to the sheet P
Can be fixed on top.

The intermediate transfer member 81 is an endless belt-shaped member made of a resin film such as polyimide or polyester, or a metal material such as nickel or stainless steel.
On its surface, a coating layer of fluorine or silicon is provided to improve the fixability of the toner to the paper P.

Next, the four image forming units 40A to 40D will be described with reference to FIG. 2. Since these have the same structure except for the toners 6a to 6d, only the image forming unit 40A will be described. The description of the other components is omitted.

The image forming unit 40A includes a toner supply mechanism 50 and an aperture electrode body 60 as an electrode array.
And the driving integrated circuit 6 connected to the aperture electrode body 60
5A.

The toner supply mechanism 50 includes a metal toner case 51, a toner container 52 formed inside the toner case 51, a toner supply roller 53, a toner transport roller 54, and a toner stirring blade 56. , And a toner regulating blade 57.

The toner case 51 is formed to be several cm wider than the maximum width of the paper P in the paper width direction (the direction perpendicular to the paper surface of FIG. 2).
A toner supply roller 53 having a length equal to or greater than the maximum width of the paper P, a toner transport roller 54, a toner stirring blade 56,
And a toner regulating blade 57.

The toner supply roller 53 is made of silicone foam, is rotatably supported via its support shaft, and comes into contact with the toner 6a in the toner container 52.
On the opposite side, it is arranged to be in contact with the toner transport roller 54, and is rotated in the direction of the arrow in synchronization with the toner transport roller 54 by a roller drive mechanism (not shown). Is frictionally charged to a negative polarity, and the charged toner 6 a is supplied to the toner transport roller 54.

The toner transport roller 54 has a structure in which a semiconductive film is provided on the entire outer peripheral surface of a metal roller member, and is rotatably supported via its support shaft. And is rotated in the direction of the arrow in synchronization with a gear or the like (not shown).

The toner 6a supplied to the toner transport roller 54 by the toner supply roller 53 and adhered in a layer on the peripheral surface thereof is formed on the peripheral surface by a toner regulating blade 57 having a predetermined thickness. (About 20 ~
50 μm).

The toner stirring blade 56 receives power from the toner conveying roller 54 by means of a gear or the like (not shown) and is driven to rotate at a low speed by reducing the speed by a reduction gear, thereby supplying the toner 6a while stirring the toner 6a. It is moved toward the roller 53.

Next, regarding the aperture electrode body 60,
This will be described with reference to FIGS.

The aperture electrode body 60 is made of synthetic resin (for example, polyimide) and has a thickness of, for example, 25 μm.
A flexible insulating sheet 61, an aperture 62 formed on the insulating sheet 61 as a plurality of minute toner passage portions, and an outer periphery of each of the apertures 62 on the surface of the insulating sheet 61. Annular control electrode 63 formed on the portion, and a plurality of conductive wires 64 provided on the surface of the insulating sheet 61 and extending from the plurality of control electrodes 63, respectively.
And an insulating coating (not shown) covering the surfaces of the plurality of control electrodes 63 and the conductive wires 64, and an antistatic coating (not shown) covering the surfaces of the insulating coating.

The aperture 62 has, for example, a diameter of 65.
a plurality of holes are formed in a row in a horizontal direction perpendicular to the direction in which the paper P is conveyed. The pitch between the apertures 62 is, for example, about 127 μm, and the width of the A4-size recording paper is (210 mm), the number of apertures 62 and the number of control electrodes 63 are both about 17
00.

The plurality of control electrodes 63 and the conducting wires 64
An electrode driving integrated circuit 65 which is formed in a copper thin film by etching and forms an electrode driving circuit for applying a voltage according to an image signal to the control electrode 63,
For example, the plurality of conducting wires 64 are divided into 19 groups so that each of the plurality of control electrodes 63 corresponds to about 90 electrodes, and a total of 19 electrode driving integrated circuits 65 are provided for each group. Is implemented.

As shown in FIG. 2, the toner case 51 has an opening for exposing a part of the peripheral surface of the toner conveying roller 54 where the toner 6a has adhered to the predetermined layer thickness. The aperture electrode body 60 a including the plurality of apertures 62 and the control electrodes 63 of the aperture electrode body 60 covers the aperture of the toner case 51 so that the aperture electrode is formed on the toner case 51. Body 60
Attach.

That is, the aperture electrode body 60 is disposed so that the peripheral surface of the toner transport roller 54 comes close to or comes into contact with the aperture 62 by the above-described configuration, and the charged toner 6a is applied to the aperture 62. Supplied to.

Also, the aperture 62 and the back electrode 8
A so that the image forming units 4
0A and the transfer unit 80 are arranged.

Next, the image forming units 40A to 40D
The means for controlling the recording will be described.

The image forming apparatus 1 is provided in a control unit 70 that receives an image signal from an external device such as a computer and controls the entire image forming apparatus based on the received signal, and in each of the image forming units 40A to 40D. A control voltage generating circuit 71 that supplies a power supply voltage of a control voltage that is a voltage applied to each control electrode to the electrode driving integrated circuits 65A to 65D, and a predetermined back voltage to each of the four sets of back electrodes 8A to 8D. The control unit 70 includes a back voltage generation circuit 72 for controlling
Are connected to the electrode driving integrated circuits 65A to 65D, respectively.

The control voltage generation circuit 71 supplies control voltage (for example, 0V and -6) to be applied to each of the control electrodes 63 corresponding to the image signal to the electrode driving integrated circuits 65A to 65D.
0V) are connected to each other via a two-core control voltage line (not shown). That is, a control voltage of −60 V is applied to the control electrode 63 on which a dot-shaped pixel is to be formed, and the control electrode 6 on which a dot-shaped pixel is not to be formed.
A voltage of 0 V is applied to 3.

On the other hand, the image forming units 40A to 40D
, The toner transport roller 54 is grounded,
The four sets of back electrodes 8A to 8D corresponding to the image forming units 40A to 40D are provided with
A common back voltage (for example, -1000 V) is supplied via the back voltage lines 75A to 75D. The control voltage generation circuit 71 and the back voltage generation circuit 72 are configured to be started by a start signal from the control unit 70 and to be stopped by a stop signal.

Next, the image forming units 40A to 40D
About the image recording operation by the image forming unit 40A
Will be described in detail with reference to an example.

As shown in FIG. 5, the positively charged toner 6a is attached to the peripheral surface of the toner conveying roller 54 in a layered manner, and a plurality of apertures 62 of the aperture electrode body 60 are formed.
Conveyed toward. Here, when −60 V is applied to the control electrode 63, the toner 6 a
And fly toward the control electrode 63 by receiving an electrostatic force due to an electric field heading toward the toner transport roller 54 from the substrate, and further fly toward the back electrode 8A by receiving an electrostatic force due to a strong electric field heading from the back electrode 8A to the control electrode 63. And the intermediate transfer member 81
Collides with and adheres to. Accordingly, dot-shaped pixels are formed on the paper P. On the other hand, 0 is applied to the control electrode 63.
When V is applied, an electric field in a direction opposite to the above is generated, so that the toner 6a does not fly toward the paper P, so that a dot-shaped pixel is formed on the paper P. There is no.

Next, a color image forming operation in the image forming apparatus 1 will be described.

The control unit 70 has four types of image signals (a yellow image signal, a magenta image signal, a cyan image signal, and a black image signal) obtained by separating a color image into four colors.
, The respective electrode driving integrated circuits 65A to 65D are controlled.

Here, on the surface of the intermediate transfer member 81,
If the position of the aperture electrode body 60 facing the aperture 62 is defined as the print position, the image forming units 40A to 40A
The image forming units 40A to 40D are arranged along the transport direction of the intermediate transfer member 81 such that four printing positions corresponding to the respective D are at a constant interval on the peripheral surface of the intermediate transfer member 81. You.

Accordingly, the transport time required to transport the intermediate transfer body 81 by the length equal to the predetermined interval is τ.
Then, after outputting the control signal based on the yellow image signal, the control unit 70 delays the time τ, 2τ, and 3τ, respectively, to control the control signal based on the magenta image signal, the control signal based on the cyan image signal, By outputting a control signal based on a black image signal, respectively, the intermediate transfer member 8 is output.
1 while being transported over one turn, the intermediate transfer member 81
A desired full-color image is recorded on the toner 6a to 6d by the transfer unit 80 and the fixing mechanism 30.
Is transferred and fixed to the paper P.

Next, the structure of the color toner used in the present invention will be described.

The minimum necessary materials for constituting the toner are a thermoplastic resin as a main component and a coloring agent added thereto. In addition to these, a charge control agent for controlling chargeability, a fluidity improver for ensuring fluidity, and the like can be appropriately used as needed.

As the thermoplastic resin, particles obtained by a pulverization method, a suspension polymerization method, an emulsion polymerization coagulation method, or the like made of polyester, styrene-acryl copolymer, etc. can be used. In order to obtain particles having a narrow distribution, it is desirable to use a method such as seed polymerization or dispersion polymerization. Dispersion polymerization is also referred to as precipitation polymerization, in which a polymerization initiator and a polymer dispersant are simultaneously dissolved in an organic solvent in which a polymerizable monomer is dissolved, and polymerization is started while maintaining the temperature at a constant temperature. Here, a surfactant or a cross-linking agent can be added as needed.

Hereinafter, a color toner mainly composed of a thermoplastic resin obtained by a dispersion polymerization method, which is most suitable for the color image forming method of the present invention, will be described as an example.

[0063]

Examples The organic solvents used for dissolving the polymerizable monomer used in this example include, for example, methanol, ethanol, isopropyl alcohol, n-butanol, s-butanol.
Butanol, t-butanol, n-amyl alcohol,
s-amyl alcohol, t-amyl alcohol, isoamyl alcohol, isobutyl alcohol, isopropyl alcohol, 2-ethylbutanol, 2-ethylhexanol, 2-octanol, n-octanol, n-decanol, cyclohexanol, n-hexanol,
-Heptanol, 3-heptanol, 3-pentanol, methylcyclohexanol, 2-methyl-2-butanol, 3-methyl-2-butanol, 3-methyl-1
-Use one or a mixture of two or more alcohols represented by butyn-3-ol, 4-methyl-2-pentanol, 3-methyl-1-pentyn-3-ol, and the like. Can be.

Examples of the organic solvent which can be used in combination with these alcohols include hydrocarbon solvents such as hexane, toluene, cyclohexane, benzene and xylene, ethylbenzyl ether, dibutyl ether and dibutyl ether. Ethers such as propyl ether, dibenzyl ether, dimethyl ether, tetrahydrofuran, vinyl methyl ether, and vinyl ethyl ether;
Examples include ketones such as acetaldehyde, acetone, acetophenone, diisobutyl ketone, diisopropyl ketone, and cyclohexanone; esters such as ethyl formate, ethyl acetate, methyl acetate, ethyl stearate, and methyl salicylate; and water. These solvents are mainly used for adjusting the SP (solubility parameter) value of the alcohols.

The weight ratio between the organic solvent and the polymerizable monomer is preferably about 100: 5 to 80: 5.

As the polymerizable monomer having a polymerizable functional group, a compound containing a vinyl group can be used. For example, styrene, methylstyrene, ethylstyrene, 2,4-dimethylstyrene, pn -Butylstyrene, styrene monomers such as pt-butylstyrene, methyl acrylate, ethyl acrylate, n
-Methyl fatty acid monocarboxylic acid esters such as -butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl vinyl ether, ethyl vinyl ether, n Vinyl ethers such as -propyl vinyl ether and n-butyl vinyl ether, and vinyl compounds such as acrylonitrile, methacrylonitrile, vinyl acetate, vinyl chloride, ethylene, propylene and chloroprene can be used alone or as a mixture of two or more.

The polymerization initiator for polymerizing the polymerizable monomer is suitably added in an amount of 0.001 to 10% by weight. For example, lauryl peroxide, benzoyl peroxide, azobisisobutyronitrile and the like are used. be able to.

In order to prevent the formed polymer particles from aggregating with each other at the same time as the polymerization starts to form particles, the dispersant is often mixed into the organic solvent from the early stage of the polymerization. The mixing amount is 0.1 parts with respect to 100 parts by weight of the mixture of the organic solvent and the polymerizable monomer.
-30 parts by weight are suitable. As the dispersant, for example, polystyrene, polyvinyl acetate, polymethyl methacrylate, polydimethylsiloxane, polyvinyl chloride,
Polyethylene, polypropylene, polylauryl methacrylate, polyoxyethylene, polyvinyl alcohol,
Polyacrylic acid, polymethacrylic acid, polyacrylamide, polyvinylpyrrolidone, polyethyleneimine, polyvinylmethylether, poly-4-vinylpyridine, polystyrenesulfonic acid, and the like can be used.

A polymerizable monomer and a dispersant are appropriately mixed in the organic solvent, and after purging with nitrogen, a polymerization initiator is added, and the temperature of the dispersion solution is raised to start polymerization. When the temperature of the mixed solution reaches 40 to 50 degrees Celsius, the mixed solution starts to become cloudy, and the fine particles of the thermoplastic resin begin to precipitate as a polymer component that cannot be dissolved in the organic solvent. Can be confirmed.

Then, while confirming the particle size distribution and the conversion, the stirring is continued while keeping the temperature constant until the polymerization reaction is completed (about 5 to 24 hours). Then, after the completion of the polymerization reaction, a series of polymerization operations is completed by lowering the temperature of the polymer particle dispersion maintained at a constant temperature to room temperature. From the thus obtained particle dispersion solution, the particles and the solution are separated by a centrifugal separator, and the obtained particles are dispersed again in a solvent in order to wash away unreacted monomers and dispersants adhered to the surface. Then, the washing operation is repeated, and the particles are dried when it is recognized that the residue on the particle surface has disappeared.

The fine particles of the thermoplastic resin synthesized in this way are dispersed again in a solvent, where dyeing is performed.

The solvent used for dyeing must be a condition that does not dissolve the fine particles of the thermoplastic resin. For example,
Methanol, ethanol, isopropyl alcohol, n
-Butanol, s-butanol, t-butanol, n-
Amyl alcohol, s-amyl alcohol, t-amyl alcohol, isoamyl alcohol, isobutyl alcohol, isopropyl alcohol, 2-ethylbutanol, 2-ethylhexanol, 2-octanol, n-
Octanol, n-decanol, cyclohexanol,
n-hexanol, 2-heptanol, 3-heptanol, 3-pentanol, methylcyclohexanol, 2
-Methyl-2-butanol, 3-methyl-2-butanol, 3-methyl-1-butyn-3-ol, 4-methyl-2-pentanol, 3-methyl-1-pentyne-3-
One of alcohols such as oar or water, or a mixture of two or more thereof can be used.

Incidentally, per 100 parts by weight of the dyeing solvent,
The thermoplastic fine particles are 1 to 50 parts by weight, and the colorant is 0.01 to
It is desirable that 10 parts by weight be mixed.

As a dye as a coloring agent used in the present invention, an anthraquinone dye is optimally used for magenta toner and cyan toner. For example, Disperse Red 4, 15, 53, 55, 59, 60, 9
1, 92, Disperse Blue 72, Disperse Violet 23, 30, 37, Solvent Violet 1
3 or the like can be used.

For the yellow toner, a methine dye is optimally used.
1, 49, 61, 73, 82, 87, 88, 89, 9
0, 91, 93, 99, 109, 116, 118, 20
1, Solvent Yellow 32, 79, 93 and the like can be used.

The solution obtained by dispersing the fine particles of the thermoplastic resin and the dye in the solvent is heated to 30 to 40 degrees Celsius, kept at a constant temperature, and stirred for 30 minutes to 2 hours. The fine particles are dyed with the dye. After completion of the dyeing, the temperature is lowered to room temperature, and the particles and the solvent are separated by a centrifuge. Further, the colored particles are washed and separated by an appropriate solvent in order to wash away the residual colorant attached to the surface thereof, and the mass of the colored particles separated from the solvent after the washing process is completed again after the washing process is completed. In order to remove the absorbed solvent, the particles are dried with a stirring dryer maintained at 30 to 40 ° C. to obtain fine particles of a dyed thermoplastic resin.

With respect to the dyed fine particles thus obtained,
In order to improve the durability and the fixability, a process of driving an external additive such as fine particles and a release agent into the surface using a machine such as a hybridizer manufactured by Nara Machinery Works, Ltd. may be performed.

Further, in order to stabilize the charge controllability of the toner, a treatment may be performed in which a charge control agent is applied to the surface of the dyed fine particles in the same manner as the external additive.
Examples of this type of charge control agent include nigrosine, azine dyes, basic dyes, lake pigments of basic dyes, metal complex salts of monoazo dyes, metal salts of dicarboxylic acids, and quaternary ammonium salts. .

Further, a fluidity improver may be added so that the toner is efficiently filled and replenished in the image forming unit by securing the fluidity of the toner powder. As this kind of fluidity improver, for example, fluorine fine powder, aliphatic metal salt, further, zinc oxide, aluminum oxide, titanium oxide, silica and the like, silicon oil, these surface-treated with a silane coupling agent An inorganic oxide fine powder or the like can be used.

According to a series of operations described above, the measured value of the particle size by a Coulter Counter Multisizer manufactured by Coulter Co., Ltd. was 3 to 15 μm in volume average particle size, and 1 in the ratio of volume average particle size to number average particle size. A dyed toner having a narrow particle size distribution, such as 0.3 or less, could be produced.

Examples of the dyed toner manufactured by the above method will be described below.

Example 1 A four-necked flask equipped with a stirring blade, a cooler, a thermometer, and a gas inlet tube was charged with 450 parts by weight of methanol and 150 parts by weight of isopropyl alcohol and mixed. (K-
30) Dissolve 20 parts by weight. To this, 160 parts by weight of styrene, 40 parts by weight of n-butyl acrylate and 2,2-
Add 8 parts by weight of azobisisobutyronitrile, stir,
A clear solution was obtained.

While the transparent solution was further stirred, the inside of the flask was replaced with nitrogen gas, the temperature was increased to 60 ° C., and the rotation speed of the stirring blade was set to 100 rpm to start polymerization. Then, it starts to become cloudy 10 minutes after heating,
While maintaining this state, polymerization was carried out for 10 hours. The polymerization is terminated by adding 200 parts by weight of a one-to-one mixed solvent of water and methanol.
This was performed by returning to room temperature while dropping over time.

The slurry obtained in this manner was
After performing the first centrifugation using a μm filter, and further redispersing in a mixed solvent of methanol and water,
Perform a second centrifugation using a 3 μm filter,
By drying for one day and night, fine powdery polymer particles were obtained.

The polymer particles have a volume average particle diameter Dv =
7.2 μm, and the ratio of volume average particle diameter Dv / number average particle diameter Dp (dispersion degree) was 1.07. The production example of the polymer particles is hereinafter referred to as Polymer Particle Production Example 1.

Then, 100 parts by weight of methanol was poured into a 300 ml beaker, and DISPERSE Y was added thereto.
Add 1 part by weight of ELLOW 82 and stir at 4 degrees Celsius
After dissolving in a 0 degree water bath to prepare a solution for dyeing, 30 parts by weight of the dried polymer particles obtained in the above-mentioned polymer particle production example 1 are dispersed, and the mixture is stirred under heating reflux for 1 hour. Yellow dyeing was carried out.

The polymer particles which have been dyed in yellow are 3
The first centrifugation is performed using a μm filter,
Further, the separated polymer particles are redispersed in 100 parts by weight of a one-to-one mixed solvent of methanol and water, and subjected to a second centrifugation. The separated particles are dried for one day to obtain yellow colored polymer particles.

The magenta colored polymer particles were prepared in the same manner as the yellow colored polymer particles by adding DISPERSE RED 4 to 0.8 parts by weight of methanol particles in 100 parts by weight of methanol. It is obtained by dyeing using a mixed dyeing solution.

In the same manner as the yellow and magenta colored polymer particles, the cyan colored polymer particles were added to the polymer particles obtained in Polymer Particle Production Example 1 by DISPERSE.
BLUE 26 is obtained by dyeing using a dyeing solution prepared by mixing 0.5 parts by weight of methanol with 100 parts by weight of methanol.

Then, with respect to 100 parts by weight of the dyed polymerized particles, hydrophobic silica fine powder (trade name: RA) was used.
200H) 1 part by weight was mixed and stirred with a mixer to obtain a positively charged dyed color toner. The charge amount was measured by using a blow-off charge amount measuring device in which 4 parts by weight of the dyed toner was mixed with 100 parts by weight of iron powder, and it was +21 μC / g for yellow color and +3 for magenta color.
It was 2 μC / g, and +35 μC / g for cyan.

The black toner is polyester resin 1
5 parts of carbon black and 2 parts of nigrosine dye are premixed with a Henschel mixer with respect to 00 parts by weight, and the temperature is set to a temperature of 80 to 110 degrees Celsius with a heating kneader, and the premixed material is melt-mixed. After cooling, it is made into a coarse pulverized product having a size of 1 to 2 mm by a cutter mill, a particle size of 20 μm or less by a fine pulverizer by an air jet method, and a particle size of 5 μm or less is adjusted to 20% or less by a classifier. The obtained black colored particles are mixed with 3 parts by weight of hydrophobic silica fine powder (trade name: RA200H) and stirred with a mixer to obtain a positively chargeable toner. The volume average particle diameter of the black toner measured by the Coulter Counter Multisizer was 9.1 μm.
When the toner was mixed with the carrier in the same manner as the dyed color toner and the amount of charge of the two components was measured, it was +23 μC / g.

These four color toners were filled in the color image forming apparatus shown in FIG. 1 to form a color image.
A color image without offset was able to be obtained even with the heat fixing device. Therefore, each color palette of yellow, magenta, cyan, and black was printed, and the density and color were measured. Table 1 shows the results.

Example 2 In Example 1 for producing polymer particles,
The same prescription and operation were carried out except that the composition of the polymerizable monomer was changed to 160 parts by weight of styrene and 40 parts by weight of ethyl acrylate, and Dv = 7.11 μm, Dv / Dp =
1.12 fine particles of a thermoplastic resin were obtained. The production example of the polymer particles is hereinafter referred to as Polymer Particle Production Example 2.

The polymer particles obtained in Polymer Particle Production Example 2 were dyed in yellow, magenta, and cyan by the same operation and composition as in Example 1. The black toner particles are SOLVE with respect to 100 parts by weight of methanol.
It is obtained by dyeing the polymer particles obtained in the above-mentioned Polymer Particle Production Example 2 under the same conditions as those for yellow and others using a dyeing solution in which 3 parts by weight of NT BLACK 3 is dissolved.

Then, hydrophobic silica fine powder (trade name: RA200H) 1 was added to 100 parts by weight of these dyed particles.
Parts by weight were mixed and stirred with a mixer to obtain a positively charged dyed toner. The charge amount was determined by mixing 4 parts by weight of the dyed toner with 100 parts by weight of iron powder and measuring with a blow-off charge amount measuring device.
/ G, magenta toner was +25 μC / g, cyan toner was +35 μC / g, and black toner was +36 μC / g.

When the dyed color toner was filled in the color image forming apparatus shown in FIG. 1 to form a color image, a color image without offset could be obtained even in the heat fixing device. Therefore, each color palette of yellow, magenta, cyan, and black was printed, and the density and color were measured. Table 1 shows the results.

Comparative Example 1 Pigment yellow 185 was added to 100 parts by weight of a polyester resin.
2 parts and 2 parts of a quaternary ammonium salt are premixed by a Henschel mixer, the temperature is set to 80 to 110 ° C. by a heating kneader, and the premixed material is melt-mixed. After cooling this melt-mixed product, it was made into a coarsely pulverized product having a size of 1 to 2 mm by a cutter mill, and further reduced to a particle size of 20 μm or less by an air jet type fine pulverizer. %.

As described above, the volume average particle diameter measured by the Coulter Counter Multisizer was 8.9 μm.
m, 17.6% of particles of 5 μm or less on a number basis
Yellow colored particles having a particle size distribution such that

Further, the pigment was changed to pigment red 1
Magenta colored particles were obtained in the same manner as in the production of the yellow colored particles except that the amount was changed to 222 parts. The volume average particle diameter of these particles measured by the Coulter Counter Multisizer is 9.1 μm, and magenta colored particles having a particle size distribution such that particles of 5 μm or less on a number basis are 18.3% are obtained.

Similarly, pigment blue 15
Cyan colored particles were obtained in the same manner as in the production conditions for yellow colored particles, except that the amount was changed to 34 parts. The volume average particle diameter of these particles measured by the Coulter Counter Multisizer is 9.0 μm, and cyan colored particles having a particle size distribution such that particles of 5 μm or less on a number basis are 16.5% are obtained.

Similarly, except that the carbon black was changed to 5 parts, the same conditions as those for producing the yellow colored particles were used.
Black particles were obtained. The volume average particle diameter of the particles measured with the Coulter Counter Multisizer was 9.9.
5 μm, and particles having a size of 5 μm or less
Black particles having a particle size distribution of 4.3% are obtained.

For 100 parts by weight of these colored particles,
One part by weight of hydrophobic silica fine powder (trade name: RA200H) was mixed and stirred with a mixer to obtain a positively chargeable toner. The charge amount was determined by mixing 4 parts by weight of toner with 100 parts by weight of iron powder and measuring with a blow-off charge amount measuring device. The yellow color was +22 μC / g and the magenta color was +23.
μC / g, cyan +25 μC / g, black +18
μC / g.

When the pulverized color toner was filled in the color image forming apparatus shown in FIG. 1 to form a color image,
A color image without offset was able to be obtained even in the heat fixing device. So, yellow, magenta, cyan,
Each black color palette was printed and measured for density and color. Table 1 shows the results.

Hereinafter, various measuring methods used in each of the above Examples and Comparative Examples will be described in detail.

(1) Measurement of Charge Amount is measured as follows using a blow-off charge amount measuring device manufactured by Toshiba Chemical.

A toner (FC6), which is a magnetite-based spherical particle having an average particle diameter of 100 μm and coated with a silicone resin, and a toner, the toner having a weight percentage of 4%
And then stir and mix for 30 minutes.
200m on a mesh of # 600 (opening diameter 38μm)
g is weighed and set in a measuring instrument, and then nitrogen gas is blown at a pressure of 0.3 kg / (cm × cm) to blow off the toner adhered to the carrier and measure the charge remaining in the Faraday cage. Then, the weight of the powder remaining on the mesh after the toner is blown off is measured and calculated with the sign opposite to that of the measured electric charge, which is defined as the amount of electric charge of the toner per unit weight.

(2) Measurement of Particle Size Distribution Measurement is performed as follows using a Coulter Counter Multisizer manufactured by Coulter Corporation.

The sample is obtained by dropping a few drops of a commercially available surfactant into an electrolyte of a 1% saline solution, mixing an appropriate amount of toner, and ultrasonically dispersing the mixture in the aqueous solution. An appropriate amount of this sample is sucked with a pipette and dropped into a measuring cell filled with an electrolyte of a 1% saline solution. Then, the measured number-based particle size distribution and the volume-based particle size distribution obtained by calculation from this are graphed, the average particle diameter is obtained from the volume-based graph, and the frequency of 5 μm or less is obtained from the number-based particle size distribution graph. Ask.

(3) Reflection Density Using a reflection densitometer RD-917 manufactured by Macbeth Co., Ltd., the density of black is a visual filter, the density of yellow is a blue filter, the density of magenta is a green filter, the density of cyan is It was measured through a red filter.

(4) L *, a *, b * Black and yellow when measured using a colorimeter MSC-1 manufactured by Suga Test Instruments and fixed at 180 degrees Celsius using an offline fixing machine. , Magenta, and cyan image forming samples are measured for X, Y, and Z stimulus values, and the values of the L *, a *, and b * color systems converted by the colorimeter are obtained from the measured values.

[0111]

[Table 1]

As is clear from the results in Table 1, Example 1
Since the color toner obtained in Example 2 uses a dye as a colorant, the color reproduction range is wider than that of a toner using a pigment as a colorant as in Comparative Example 1. .

[0113]

As is clear from the above description,
According to the color image forming method according to claim 1 of the present invention, by using a dye as a coloring agent, good coloring can be performed without concern for dispersibility in a thermoplastic resin, Since transparency can be ensured, it is possible to provide a color image forming method that enhances color reproducibility and is suitable for output to an OHP sheet.

That is, the dye has a higher saturation than the pigment, and when used as a colorant for a toner, can provide a wide color reproduction range. Therefore, a color image forming method for faithfully reproducing the color of an original is provided. can do.

Further, the dispersion of the colorant also affects the charge stability of the toner. Unlike a pigment having a different dispersibility for each toner particle, the colorant is uniformly dispersed by using a dye. Since the toner particles are held by the toner particles, it is possible to provide a color image forming method in which a clear color image can be obtained by using a toner having a uniform charge amount and little scattering on the image.

According to the color image forming method of the present invention, by using a specific dye as a coloring agent, it is possible to color the thermoplastic resin particles with a higher color saturation and a higher concentration than the pigment. It is possible to obtain a high density color image even if the amount added to the toner is smaller than the pigment,
A clear color image can be formed, and a color image forming method excellent in environmental stability can be provided.

According to the color image forming method of the present invention, since a toner in which polymer particles having an extremely sharp particle size distribution are dyed with a specific dye is used, the charge amount distribution of the toner becomes sharp and the developing property is improved. This makes it possible to form a clear and high-resolution color image which is particularly suitable for digital development.

According to the color image forming method of the present invention, since the adhesion of the toner to the image recording medium is directly controlled in accordance with the image information, the image stain on the white background portion and the blank portion is small and clear. A high-resolution color image can be formed with an appropriate color, and the size of the color image forming apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a color image forming apparatus used in a color image forming method according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the image forming apparatus.

FIG. 3 is an enlarged perspective view of an aperture electrode body used in the image forming apparatus.

FIG. 4 is an enlarged perspective view of a main part of the aperture electrode body.

FIG. 5 is an enlarged sectional view of a main part of an image forming unit constituting the image forming apparatus.

[Explanation of symbols]

 1 Image Forming Apparatus 40A Image Forming Unit 60 Aperture Electrode 62 Aperture 63 Control Electrode 80 Transfer Unit

Claims (4)

[Claims] 1. A color image forming method for forming a color image using a plurality of color toners, wherein at least one of the plurality of color toners contains a thermoplastic resin as a main component and a dye as a colorant. A color image forming method, characterized in that a color image forming method is used. 2. A yellow toner containing a thermoplastic resin as a main component and a methine dye as a colorant, and a magenta toner and a cyan toner containing a thermoplastic resin as a main component. And a colorant comprising an anthraquinone dye as a colorant.
3. The color image forming method described in 1. above. 3. As the thermoplastic resin, polymer particles synthesized from a monomer and a polymerization initiator are used, and the polymer particles are dyed with a colorant or a solution in which the colorant is dissolved or dispersed in a solvent. The color image forming method according to claim 1, wherein the toner is used. 4. The color image forming method according to claim 1, wherein a plurality of toner passage portions are provided on a flexible insulating sheet in a direction intersecting a conveying direction of the image recording medium. An electrode array formed by forming electrodes in each of the toner passage portions, a toner supply means for supplying toner to the toner passage portion, and a voltage supplied to each electrode of the electrode array. By using an image forming unit including an electrode drive circuit for individually controlling the toner, by attaching the toner of the plurality of colors on the image recording medium using the image forming unit for each of the colors, A color image forming method for forming a color image.