JP3342238B2 - Multicolor 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 multicolor image forming method using an electrostatic image developing toner for developing an electrostatic image formed in electrophotography, electrostatic printing or the like. More specifically, the present invention relates to a multicolor image forming method using an electrostatic image developing toner obtained by aqueous suspension polymerization of a monomer composition containing at least a colorant.

[0002]

2. Description of the Related Art In recent years, digital full-color copying machines and printers have been put into practical use, and high-quality images excellent in color reproducibility without color unevenness as well as in resolving power and gradation can be obtained.

In a digital full-color copying machine, a color image original is separated into colors by B (blue), G (green), and R (red) color filters, and then has a dot diameter of 20 μm to 70 μm corresponding to the original image. Latent image is Y (yellow), M (magenta), C (cyan), B
(Black) Each color developer is developed using the subtractive color mixing action. Compared to a black-and-white copying machine, it is necessary to transfer a larger amount of developer from the photoconductor to the transfer material. In order to cope with the development, it is expected that a developer having a smaller diameter corresponding to a fine dot is required to have a smaller diameter.

However, when the toner particle size is reduced in accordance with the demand for higher image quality, the resolution and the sharpness of a full-color image can be satisfactorily improved, but it has been found that fine particles have various effects. Have been.

First, when the toner particle size is reduced, there arises a problem that the charging characteristics are easily affected by the uneven distribution of the colorant. Therefore, there is a demand for a toner having better dispersion of each color of the color toner than before and having well-balanced hue and spectral reflection characteristics and sufficient saturation.

Next, when the toner particle diameter is reduced, light becomes more liable to be scattered, so that the chromaticity, lightness, density, etc. of the image change, and a color configuration different from that of the prior art is required. Problems arise. This becomes remarkable when an image is obtained in accordance with a new user orientation accompanying the spread of printers in recent years, that is, a tendency to prefer an image similar to other matte printed matter such as photoengraving printing.

That is, in the prior art, it is necessary that the fixed toner is almost completely melted so that the shape of the toner particles cannot be discriminated so that the toner does not irregularly reflect light and hinder color reproduction. In some cases, in a color image in which several types of toner layers are superimposed, it is necessary that the upper toner layer has transparency that does not interfere with the lower toner layer.

Based on this idea, Japanese Patent Laid-Open No. 59-26
As shown in JP-A-757, JP-A-63-70271, JP-A-1-2300072, JP-A-2-293860, JP-A-6-11898, etc., each yellow / magenta / cyan / black is disclosed. Various other configurations have been proposed.

However, in order to obtain an image having no difference in gloss from other printed matter such as photoengraving printing, it is necessary to fix the gloss to a value close to the glossiness of the paper. Since there is no such situation, the influence of the scattered light of the fine particle toner becomes remarkable, and the color space configuration of the present invention has become insufficient.

In the printer market, there are many opportunities to output an image in which black characters are mixed. In the prior art, however, there is a difference in the amount of toner between the black characters and the color image, so that the difference in glossiness is low. This results in a high gloss color image that appears "emerging".

Further, since light on the image surface is scattered and the image density decreases, it has been found that fog becomes noticeable when the coloring power of the toner is increased as a measure.

That is, since the portion where the toner is scattered at the time of fixing is given a relatively large amount of heat, the glossiness of the image is increased, and as a result, the image density of the scattered portion is increased. And this makes the fog noticeable.

In recent years, there has been a movement to re-transfer an image to steel or cloth as a further application of electrophotography technology. The above heat resistance and light resistance are required.

For the various problems described above,
At present, there is no full color toner that can satisfy all of them.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a multicolor image forming method capable of obtaining extremely clear colors on an image having low glossiness.

That is, an object of the present invention is to provide a multicolor image forming method using a toner having a well-balanced hue and dot fidelity in a multicolor image forming method using at least a yellow toner, a magenta toner, and a cyan toner. Is what you do.

Another object of the present invention is to provide a method for forming a multicolor image having a uniform image quality without any discomfort even in an image including black characters.

Another object of the present invention is to provide a method for forming a multicolor image using a color toner for developing an electrostatic image having excellent heat and light resistance.

[0019]

SUMMARY OF THE INVENTION The present invention relates to a multicolor image forming method for developing, transferring and fixing at least a yellow toner, a magenta toner and a cyan toner.
The weight average diameter of the yellow toner, magenta toner and cyan toner is 9 μm or less, and the glossiness of at least each monochromatic image is 50 or less, and the hue angle h of each of the yellow toner, magenta toner and cyan toner in each monochromatic image is ^* and lightness L ^{* is, 85 ≦ h * (Y)} ≦ 100,80 ≦ L * (Y) ≦ 110 345 ≦ h * (M) ≦ 359,30 ≦ L * (M) ≦ 50 245 ≦ h * ( C) A multicolor image forming method, wherein the toner satisfies ≦ 265 and 40 ≦ L ^* (C) ≦ 60.

One of the features of the present invention is that at least the glossiness of each monochrome image is suppressed to 50 or less (preferably 30 or less).

The present inventors have found that the relationship between the amount of applied toner and the glossiness is important because the uncomfortable feeling at the time of fixing a black character image and a color image is mainly due to the difference in glossiness between the images. The present invention has been made.

That is, when the glossiness is high, the glossiness of an image tends to increase as the amount of multicolor toner applied and fixed on a transfer material. Therefore, by suppressing the glossiness of each single-color image to a certain value or less, the glossiness equivalent to that of the single-color image is obtained even in an image in which the multicolor toner is applied on the transfer material, so that the discomfort on the image almost disappears.

The measurement of the image glossiness in the present invention is carried out according to JIS Z8741 Method 2. A single-color image is a sheet of 80 g / m ² paper having a gloss level of 4 to 12 as a transfer material, and the amount of toner of each single-color toner is 0.
An image is output after adjusting the concentration to 5 to 0.6 mg / cm ² , and the image density measured by a reflection densitometer RD918 (manufactured by Macbeth) falls within the range of 1.2 to 1.6.

When the glossiness exceeds 50, unnaturalness between the black character image and the color image occurs as described above, which is not preferable.

When an unfixed image in which a large amount of toner has been transferred onto a transfer material is fixed, the molten toner layer is gradually cooled and the volume of the resin shrinks. Exceeds 50, curling (winding) of the edge portion of the fixed image is likely to occur, which is disadvantageous in this respect as well.

One of the features of the present invention is to use a color toner whose hue angle and lightness of each color are within a predetermined range.

The inventors of the present invention have low glossiness as described above.
As a result of various studies on color reproducibility in images with large light scattering,
The inventors have found that fine particles can be used by adjusting the brightness of each color within a certain range and increasing the reproducibility of the red system.

That is, although the direct cause is unknown, the change in human color perception due to light scattering of the fine particle toner is particularly high with respect to the lightness L ^* and (red-magenta) color difference of each color. In order to cope with a change in the color sensation, it is only necessary to hold both of them.

In the case of a full-color image, a method of replacing the overlap of yellow, magenta, and cyan with black and reducing the amount of color toner by that amount (called UCR) is used in order to gain sharpness and consumption. At this time, the present inventors have found that the gray-tone color reproducibility of the secondary colors blue (B) and green (G) is the lightness L of each of the single colors of yellow, magenta, and cyan. ^* Found to be greatly influenced by

For this reason, according to the present invention,
The present invention has been devised based on the idea that the color tone of both yellow and magenta shifts to the red side and the gray tone is controlled in a certain range of lightness, as compared with the proposal of JP-A-70271.

The types of the yellow, magenta and cyan pigments included in the above hue angle are as follows: (Yellow) Pigment Yellow 2/3/4/5/6/7/13/9
5/174/180 (Magenta) Pigment Red 3/5/7/8/12/12/122/20
Coloring agents such as 5/207 (cyan) pigment blue 15/16/17 may be mentioned, but are not limited to known coloring agents.

In addition, a colorant that is out of the range of the present invention in a single color can be used as long as it is within the range of the present invention by combining a colorant that is a complementary color. However, considering the dispersibility problem and the decrease in transparency due to the mixing of the colorant, the method is not always preferable, and it is more preferable to use the colorant alone.

The colorant of the black toner may be a magnetic substance, carbon black, or a blend of both, but from the viewpoint of production cost, the magnetic substance-containing system, transparency / UC
From the viewpoint of R characteristics, a carbon black-containing system is preferable,
It is preferable to select an appropriate one according to the performance of the copying machine to be used.

Since the colorant within the scope of the present invention has a sufficient color developing property in the present image forming method as compared with the conventional one, not only the image forming method using a four-color toner but also a black toner The method has excellent gray tone reproducibility even in the three-color image forming method.

Since the image has a lower gloss than the conventional image, the yellow, magenta and cyan colorants are added in an amount of 1 to 100 parts by weight of the resin component in the toner in order to obtain the same image density as the conventional image. The content is preferably 15 parts by weight, and more preferably 3 to 12 parts by weight.

The method for measuring the hue angle h ^* in the present invention is as follows.
The measurement was carried out under the following conditions in the sense that the material was brought closer to a transfer material such as photolithography.

That is, 8 in the glossiness range of 3 to 15
Using a 0 g / m ² paper as a transfer material, an image is prepared in which the toner amount of each single color toner is adjusted to 0.5 to 0.6 mg / cm ² , and the reflected light is reflected by an integrating sphere spectrophotometer (Murakami Color Laboratory: CMS500 / measurement condition D-0, reference light source D65).

Another feature of the present invention is to use a toner whose shape has a smooth shape close to a true sphere.

When the toner has a smooth shape close to a true sphere as in the present invention, the fluidity improver or the like which is usually fixed and dispersed on the toner surface can be uniformly deposited without accumulating on a part of the toner surface. The addition of the compound not only sharpens the charge distribution, but also allows the transfer from the charge supporting member such as the sleeve carrier to the photoreceptor to be performed at a low potential, thereby reducing so-called "fog".

On the latent image, since the closest packing is performed, the effect of increasing the fidelity to the dot is also obtained.

For this reason, even if the coloring power of each toner is increased in order to compensate for the decrease in image density due to the scattering of light, the toner is not observed as "fog" more than before.
A homogeneous image can be obtained.

The preferred shape factor of the present invention is 10
0 ≦ SF1 ≦ 150, 100 ≦ SF2 ≦ 140,
If SF1 exceeds 150 (more preferably 140), the transfer rate, the development efficiency, and the like deteriorate, and the image quality deteriorates. Also SF
When 2 exceeds 140 (more preferably 130), the unevenness of the toner surface becomes large, so that a fluidity improver or the like accumulates in the concave portions, and the charge distribution becomes nonuniform, so that "fog" on the photoreceptor deteriorates. come.

SF1 indicating the shape factor used in the present invention
・ SF2 is FE-SEM (S-80
0), 100 toner images were randomly sampled, and the normal image method was introduced into an image analyzer (Luzex3) manufactured by Nicole via an interface and analyzed.
In the present invention, the values calculated from the following equations are defined as shape factors SF1 and SF2.

[0044]

(Equation 1) [Wherein, MXLNG indicates the absolute maximum length of the developer on the image, and AREA indicates the projected area of the developer. ]

[0045]

(Equation 2) [Where PELI indicates the peripheral length of the developer projected image on the image, and AREA indicates the projected area of the developer. ]

A further feature of the present invention is to use at least a yellow toner, a magenta toner, and a cyan toner obtained by directly polymerizing a polymerizable monomer in an aqueous medium.

The polymerization method is described, for example, in JP-B-36-1023.
No. 1, Japanese Patent Publication No. 43-10799 and Japanese Patent Publication No. 5
In the polymerization method, a polymerizable monomer, a colorant, a polymerization initiator, and, if necessary, a crosslinking agent, a charge control agent, and other additives are uniformly dissolved in a polymerization method as proposed in JP-A-1-14895. Or after dispersing into a monomer composition, this monomer composition is dispersed in a continuous phase containing a dispersion stabilizer, for example, an aqueous phase using a suitable stirrer, and simultaneously subjected to a polymerization reaction, This is a method for obtaining a developer having a desired particle size.

In general, in order to obtain the shape of the toner according to the present invention by a pulverization method, a process such as spheroidization by mechanical impact force is required as shown in JP-A-63-279864, which is complicated. Operation and cost are required.

On the other hand, in the polymerization method, the shape of the obtained particles is determined by the surface tension with water as a dispersion medium, and thus generally becomes spherical, so that the shape of the present invention can be easily obtained. Has features.

In addition, when directly polymerized in an aqueous medium, the colorant and the charge control agent are uniformly dissolved in the monomer to form a toner, so that the toner surface exhibits a more uniform charging behavior than the pulverization method. .

For the reasons described above, the effects of the present invention can be further obtained by using at least a yellow toner, a magenta toner, and a cyan toner obtained by directly polymerizing a polymerizable monomer in an aqueous medium.

In the pulverization method, as the particle size measured by a Coulter counter becomes 9 μm or less, the uniform dispersibility of the used raw materials and the highly efficient pulverizability, which have not been a problem in the past, and further develop into a sharp particle size distribution. Although it tends to be extremely difficult to classify the agent, the polymerization method also has excellent characteristics in that respect, and furthermore, a large amount of a low softening point substance that cannot be used in the conventional pulverization method is used. It is also preferable because it has characteristics such as a wider range of material choices, such as the ability to produce a material.

Further, as described above, the toner of the present invention has the effect of increasing the fidelity to the dots because of the close packing on the latent image. Due to the behavior, the electrostatic offset at the time of fixing tends to occur rather easily.

In addition, the spherical toner has a property that it is easily fixed while leaving the interface between the toners because the contact between the adjacent toners is limited to only one point. As a result, diffused reflection of light is more likely to be promoted than in the related art, and the lightness L ^* and toner transparency tend to be easily reduced even with the same glossiness.

Therefore, in the case of the toner of the present invention, in order to compensate for a decrease in fixability, lightness L ^* and transparency of the toner, it is essential to mix a molecular weight resin component as an adhesive between interfaces. In the molecular weight distribution (Mn) of the resin component, a component having a molecular weight satisfying Mn <2000 is preferably present in an amount of 0.01% by weight or more and 10% by weight or less based on the total amount of the resin.

If the component having a molecular weight that satisfies Mn <2000 is less than 0.01% by weight based on the total amount of the resin, the effects of the present invention cannot be obtained and the brightness and the transparency deteriorate. If the component having a molecular weight that satisfies Mn <2000 exceeds 10% by weight based on the total amount of the resin component, the toner is excessively plasticized, so that the durability and low-temperature fixability deteriorate.

Further, as a colorant when directly polymerizing in an aqueous medium, easy dissolution and dispersion in a monomer is required.
A further object of the present invention is to satisfy high light resistance, high coloring power, and high dispersibility corresponding to the movement of retransferring an image to a steel material or cloth in a coloring agent. As a colorant, a combination of Pigment Yellow 180, Pigment Red 122, and Pigment Blue 15 is preferable.

In the method for directly obtaining a toner by a polymerization method, a known monomer is preferably used. Specifically, styrene, o (m-, p-)-methylstyrene, m (p
-)-Styrene monomers such as ethylstyrene; (meth)
Methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate,
Octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth) acryl (Meth) acrylate monomers such as diethylaminoethyl acrylate; ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile, and acrylamide are preferably used. These may be used alone or generally in the published Polymer Handbook, 2nd Edition, III-P 139-192 (John Wire
y & Sons) theoretical glass temperature (Tg)
However, monomers are appropriately mixed and used so as to show a temperature of 40 to 85 ° C. If the theoretical glass transition temperature is less than 40 ° C,
Problems arise in terms of the storage stability of the toner and the durability stability of the toner. On the other hand, when the temperature exceeds 85 ° C., the fixation point is increased. Poor, moreover OHP
The transparency of the image is remarkably reduced, which is not preferable from the viewpoint of high image quality.

The molecular weight of the polymerized resin is measured by GPC (gel permeation chromatography). As a specific GPC measurement method, the toner is extracted in advance with a toluene solvent using a Soxhlet extractor for 20 hours, and then the toluene is distilled off with a rotary evaporator. After adding an insoluble organic solvent (eg, chloroform) and washing well, a solution dissolved in THF (tetrahydrofuran) was filtered through a solvent-resistant membrane filter having a pore diameter of 0.3 μm, and a sample manufactured by Waters Corporation was used. 150
C, and the column configuration was A-801, 80 manufactured by Showa Denko
2, 803, 804, 805, 806, and 807 are linked, and the molecular weight distribution can be measured using a standard polystyrene resin calibration curve. The number average molecular weight (Mn) of the obtained resin component is
5000 to 1,000,000, and a ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn)
Is preferably 2 to 100 for the present invention.

In the present invention, a polar resin may be further added in addition to the monomer component in order to encapsulate the low softening point substance in the resin. As the polar resin used in the present invention, a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, and an epoxy resin are preferably used.

In the present invention, a low softening point substance may be added to the resin in order to impart a releasing effect.

As the low softening point substance used in the present invention, a compound having a main peak maximum value of 50 to 180 ° C. measured according to ASTM D3418-8 is preferable.

When the maximum peak value is less than 50 ° C., the self-cohesive force of the low softening point substance becomes weak, and as a result, the high-temperature offset resistance becomes weak, which is not preferable for a full color developer. On the other hand, if the maximum peak value exceeds 180 ° C., the crystallinity and dispersibility of the softening point substance are deteriorated at present, which is not preferable in terms of fixability and transparency.

For measuring the temperature of the maximum peak value of the present invention,
For example, DSC-7 manufactured by PerkinElmer is used. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the heat quantity correction uses the heat of fusion of indium. An aluminum pan was used as a sample, an empty pan was set as a control, and the temperature was raised at a rate of 10 ° C./min. Perform the measurement with.

Specifically, paraffin wax, polyolefin wax, Fischer-Tropsch wax,
Amide waxes, ester waxes, higher fatty acids and their graft / block compounds can be used.

The charge control agents used in the present invention include:
A known charge control agent can be used, but a charge control agent which is colorless, has a high toner charging speed, and can stably maintain a constant charge amount is preferable. Further, when a direct polymerization method is used in the present invention, a charge control agent having no polymerization inhibition and having no solubilized substance in an aqueous system is particularly preferable. Specific compounds include metal compounds of salicylic acid, naphthoic acid, and dicarboxylic acid, polymer compounds having sulfonic acid and carboxylic acid in the side chain, boron compounds, urea compounds, silicon compounds, and carricks arenes as negative compounds. As the positive system, a quaternary ammonium salt, a high molecular compound having the quaternary ammonium salt in a side chain, a guanidine compound, an imidazole compound and the like are preferably used. The charge control agent is resin 10
0.5 to 10 parts by weight per 0 parts by weight is preferred. However, in the present invention, the addition of a charge control agent is not essential, and when a two-component developing method is used, the frictional charging with a carrier is used, and even when a non-magnetic one-component blade coating developing method is used, a blade is used. By positively utilizing frictional charging with the member or the sleeve member, it is not necessary to necessarily include a charge control agent in the toner.

When the direct polymerization method is used in the present invention,
As the polymerization initiator, for example, 2,2′-azobis- (2,
4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-
Azo or diazo polymerization initiators such as methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile; benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, lauroyl A peroxide-based polymerization initiator such as peroxide is used. The amount of the polymerization initiator varies depending on the desired degree of polymerization, but is generally used in an amount of 0.5 to 20% by weight based on the monomer. The type of the polymerization initiator varies slightly depending on the polymerization method, but may be used alone or in combination with reference to the 10-hour half-life temperature.

In order to control the degree of polymerization, a known crosslinking agent, chain transfer agent, polymerization inhibitor and the like can be further added and used.

When the suspension polymerization is used as the toner production method of the present invention, the dispersant used may be an inorganic compound such as tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, Examples include magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate, bentonite, silica, alumina, magnetic material, ferrite, and the like. As the organic compound, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, starch and the like can be used by dispersing them in an aqueous phase. These dispersants are used in an amount of 0.1 to 100 parts by weight of the polymerizable monomer.
It is preferred to use 2 to 2.0 parts by weight.

As these dispersants, commercially available ones may be used as they are, but in order to obtain finely dispersed particles having a uniform particle size, the inorganic compound may be produced under high-speed stirring in a dispersion medium. it can. For example, in the case of tricalcium phosphate, a dispersant suitable for suspension polymerization can be obtained by mixing an aqueous solution of sodium phosphate and an aqueous solution of calcium chloride under high-speed stirring.

In order to make these dispersants finer, the content of 0.1.
001 to 0.1 parts by weight of a surfactant may be used in combination.
Specifically, commercially available nonionic, anionic, and cationic surfactants can be used, and examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, and potassium stearate. , Calcium oleate and the like.

In the case where the direct polymerization method is used in the toner production method of the present invention, it is possible to specifically produce the toner by the following production method.

That is, a releasing agent, a colorant, a charge control agent, a polymerization initiator and other additives composed of a low softening point substance are added to the polymerizable monomer, and the mixture is uniformly mixed with a homogenizer, an ultrasonic disperser or the like. The dissolved or dispersed monomer system is dispersed in an aqueous phase containing a dispersion stabilizer using a conventional stirrer, homomixer, homogenizer, or the like. Preferably, the agitation speed and time are adjusted so that the monomer droplets have the desired size of the toner particles, and granulation is performed. Thereafter, by the action of the dispersion stabilizer, the particles may be stirred to such an extent that the particle state is maintained and the particles are prevented from settling. Polymerization temperature is 40
The polymerization is preferably carried out at a temperature of at least 50 ° C., generally from 50 to 90 ° C. Further, the temperature may be raised in the latter half of the polymerization reaction, and further, in order to remove unreacted polymerizable monomers, by-products and the like which cause odor at the time of fixing the developer, the second half of the reaction,
Alternatively, a part of the aqueous medium may be distilled off after the completion of the reaction. In the suspension polymerization method, it is generally preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer system.

Next, the multicolor image forming method of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of an electrophotographic apparatus capable of forming a full-color image according to the present invention.
In the drawing, a transfer material transport system I provided from the right side of the apparatus main body 100 (the right side in FIG. 1) to a substantially central portion of the apparatus main body 100, and the transfer material transport system I And a developing unit (that is, a rotary developing device III) disposed in close proximity to the latent image forming unit II.
They are roughly divided into The transfer material transport system I described above includes transfer material supply trays 101 and 10 which are detachable from an opening formed on the right side (the right side in FIG. 1) of the apparatus main body 100.
2, paper feed rollers 103 and 104 disposed almost directly above the trays 101 and 102, and a paper feed roller 10 disposed close to the paper feed rollers 103 and 104.
Paper feed guides 4A and 4B provided with
b, a contact roller 7, a gripper 6, a transfer material separating charger 12, and a separating claw 14 are disposed near the outer peripheral surface from the upstream side to the downstream side in the rotation direction. A transfer charger 9 and a transfer material separating charger 13 are provided on the inner peripheral side. A transfer drum 8 rotatable in the direction of the arrow in FIG. 1, a transport belt means 15 provided in proximity to the separation claw 14, and an apparatus disposed in proximity to the transport direction end end of the transport belt means 15. The apparatus comprises a discharge tray 17 which is detachable from the apparatus main body 100 and extends outside the main body 100, and a fixing device 16 which is close to the discharge tray 17.

The latent image forming section II is provided with an image carrier (that is, the photosensitive drum 2) whose outer peripheral surface is disposed in contact with the outer peripheral surface of the transfer drum 8 and is rotatable in the direction of the arrow in FIG. A static eliminator 10, a cleaning unit 11, a primary charger 3, and the photosensitive member disposed near the outer peripheral surface of the photosensitive drum 2 from the upstream side to the downstream side in the rotation direction of the photosensitive drum 2. An image exposure means such as a laser beam scanner for forming an electrostatic latent image on the outer peripheral surface of the drum 2 and an image exposure reflection means such as a polygon mirror are provided. The rotary developing device III includes a rotatable housing (hereinafter, referred to as a “rotator”) 4 a and the photoconductor at a position opposed to the outer peripheral surface of the photoconductor drum 2 mounted in the rotor 4 a. A yellow developing unit 4Y, a magenta developing unit 4M, and a cyan developing unit 4 configured to visualize (ie, develop) an electrostatic latent image formed on the outer peripheral surface of the drum 2
C and a black developing unit 4BK.

The sequence of the entire image forming apparatus having the above-described configuration will be described by taking a full color mode as an example. When the aforementioned photosensitive drum 2 rotates in the direction of the arrow in FIG. 1, the photosensitive body on the photosensitive drum 2 is uniformly charged by the primary charger 3. When the photosensitive member is uniformly charged by the primary charger 3, a document (not shown)
Image exposure is performed by the laser light E modulated by the yellow image signal of FIG. 1, an electrostatic latent image is formed on the photosensitive drum 2, and the yellow developing device 4Y previously set at the developing position by the rotation of the rotating body 4a Thereby, the electrostatic latent image is developed.

On the other hand, the paper feed guide 4A, the paper feed roller 10
6. The transfer material conveyed via the paper feed guide 4b is held by the gripper 6 at a predetermined timing.
The transfer roller 8 is electrostatically wound around the contact roller 7 and an electrode facing the contact roller 7. The transfer drum 8 rotates in the direction of the arrow in FIG. 1 in synchronization with the photosensitive drum 2, and the developed image developed by the yellow developing device 4 </ b> Y is transferred to the outer peripheral surface of the photosensitive drum 2 and the transfer drum 8.
Is transferred by the transfer charger 9 at a portion where the outer peripheral surface is in contact. The transfer drum 8 continues to rotate as it is,
Prepare for the transfer of the next color (magenta in FIG. 1).

On the other hand, the photosensitive drum 2 is discharged by the discharging charger 10 and cleaned by the cleaning means 11, and then charged again by the primary charging device 3, and the above image is formed by the next magenta image signal. Receive exposure. The rotary developing device rotates while an electrostatic latent image based on a magenta image signal is formed on the photoconductor drum 2 by the image exposure, and fixes the magenta developing device 4M at the above-described predetermined developing position. A predetermined magenta development is performed. Subsequently, the above-described process is also performed for cyan and black, respectively, and when the transfer for four colors is completed, the multicolored image formed on the transfer material is charged by each of the chargers 12 and 13. The charge is removed, the gripping of the transfer material by the gripper 6 is released, and the transfer material is separated from the transfer drum 8 by the separation claw 14, sent to the fixing device 16 by the transport belt 15, and fixed by heat and pressure. A series of full-color print sequences is completed, and a required full-color print image is formed.

The fixing device 16 includes a heat fixing roller 161 and a pressure roller 162. Heating roller 161
Preferably has a surface layer having excellent release properties. The surface layer of the pressure roller 162 is preferably formed of the same fluorine resin as the heating roller, or is formed of silicone rubber or the like.

Hereinafter, the present invention will be specifically described based on examples.

[0082]

【Example】

[Toner Production Example 1 (Production Example of Polymerization Method)] First, a cyan toner was prepared as follows. 910 parts by weight of ion-exchanged water and 0.1 mol / l-Na _{3 were} placed in a two-liter four-necked flask equipped with a high-speed stirrer TK-homomixer.
450 parts by weight of a PO ₄ aqueous solution were added, and the number of rotations was increased to 12,000.
Rotated and warmed to 65 ° C. 68 parts by weight of a 1.0 mol / liter CaCl ₂ aqueous solution was gradually added thereto to prepare a dispersion medium system containing a minute water-insoluble dispersant Ca ₃ (PO ₄ ) ₂ . On the other hand, the dispersoid system

Styrene monomer 170 parts by weight n-butyl acrylate monomer 30 parts by weight I. Pigment Blue 15: 3 14 parts by weight Saturated polyester 15 parts by weight (terephthalic acid-propylene oxide-modified bisphenol A acid value 15, peak molecular weight 6000) Salicylic acid metal compound 2 parts by weight ester wax (maximum peak value 69.4 ° C.) 40 Parts by weight After dispersing the above mixture for 3 hours using an attritor,
10 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator was added to obtain a dispersion. This was poured into the dispersion medium and granulated for 12 minutes while maintaining the rotation speed. Thereafter, the stirrer was changed from a high-speed stirrer to a propeller stirring blade, the internal temperature was raised to 80 ° C., and the polymerization was continued at 50 rotations for 10 hours. After the polymerization was completed, the slurry was cooled, and diluted hydrochloric acid was added to remove the dispersant.

By further washing and drying, the weight average diameter of the cyan particles measured by a Coulter counter is 6 μm.
m, the number variation coefficient is 28%, SF1 is 115, S
The component having a molecular weight satisfying F2 of 105 and Mn <2000 was 2.1% by weight based on the total amount of the resin.

The titanium oxide obtained by subjecting the obtained particles to hydrophobic treatment was
% To obtain a toner (C1) having excellent fluidity.

The other yellow, magenta, and black toners use C.I. I. Pigment Yellow 180,
C. I. Pigment Red 122 and graft carbon black, and SF1 is 110 to 112 in the same manner.
, Ie, a yellow toner (Y1), a magenta toner (M1) and a black toner (B1) shown in Table 1.

Pigment Yellow 17, C.I. I. Pigment Red 202
The same operation is performed except that the yellow toner (Y
2), magenta toner (M2) was obtained.

Further, each of the toners (C1, Y1, M
The initiator formulation of 1, B1) is 2,2′-azobis (2,2)
4-dimethylvaleronitrile) and toner 4 (C2, Y3, M3, B) containing a large amount of low molecular weight components, except that the parts were changed to 0.5 part by weight and 4 parts by weight of potassium persulfate.
2) was obtained.

[0089]

[Table 1]

[0090] [(preparation pulverization method) Toner Production Example 2] propoxylated bisphenol and fumaric acid, the polyester resin obtained by condensation of trimellitic acid (Mn = 250
0, Mw = 21000, Tg = 59 ° C., acid value = 9) 10
0 parts by weight, C.I. I. Pigment Blue 15:35 5 parts by weight Salicylic acid metal compound 2 parts by weight Ester wax (maximum peak value 69.4 ° C.) 2 parts by weight was added, followed by melting, kneading and pulverization to obtain cyan particles. The weight average diameter of the cyan particles is 6.5 μm and the number variation coefficient is 3
8%, SF1 was 165 and SF2 was 155.

The obtained particles were treated with hydrophobically treated titanium oxide
% To obtain a toner (C3) having excellent fluidity.

Further, the cyan particles are described in JP-A-63-279.
As shown in Japanese Patent Publication No. 864, spherical cyan particles (weight average diameter was 6.1 μm, SF1 = 145, SF2 = 135) were obtained by spheroidization by mechanical impact force (Table 2).

The obtained particles were treated with hydrophobically treated titanium oxide
% To obtain a toner (C4) having excellent fluidity.

The other yellow, magenta, and black toners use C.I. I. Pigment Yellow 180,
C. I. Pigment Red 122 and grafted carbon black, and a yellow magenta black toner (Y4 / M4 / B3) and a spherical yellow magenta black toner (Y5 / M5 / B4) were obtained in the same manner.

[0095]

[Table 2]

Examples 1 to 4 and Comparative Example 1 An image evaluation method will be described.

A developer is prepared by mixing 93 parts by weight of an acrylic resin-coated ferrite carrier with 7 parts by weight of the toner.

Using the obtained developer, the fixing temperature is made variable, and the material of the upper and lower rollers (161, 162) is made of fluorine, and the material is sequentially latent in the order of Y / M / C / Bk by the remodeling machine shown in FIG. The image was transferred onto a transfer material to obtain an image.

At this time, the fixing conditions were as follows: a transfer material used was a paper having a gloss of 4 and a basis weight of 99 g / m ^2, and the amount of applied toner was 0.5
To obtain a monochromatic solid image ~0.7mg / cm ^2, was the image to adjust the by Ujo deposition temperature at which the gloss 10-15.

The density conditions of each color were adjusted so that a gray scale and color patches manufactured by Kodak Co., Ltd. were used as a document, and the gray scale was reproduced as faithfully as possible in a full-color copy image, and yellow (Y), magenta (M), and cyan were used. (C), black (B) The maximum density of each single color copy is 1.
The concentration was adjusted to be 1 or more.

In the remodeled machine in the above state, red (R) is a superimposed image of yellow (Y) and magenta (M), magenta (M) and cyan (C), and yellow (Y) and cyan (C). ), Blue (B) and green (G) were obtained under two types of fixing conditions with gloss levels of 10 to 15 and 40 or more. At this time, evaluation was made based on the color tone difference of the overlapping portion at the maximum density of each color.

The evaluation was performed in five stages. When the chromaticity difference formula of CMC (1: 1) was introduced for the lightness L ^* , chroma C ^* , and hue angle h ^* of the image, and the value of the comparative example was set to 100. ×: ΔE> 110 Δ ×: 100 <ΔE ≦ 110 Δ: 90 <ΔE ≦ 100 ○ △: 80 <ΔE ≦ 90 ○: ΔE ≦ 80 (ΔE: chromaticity difference).

The formula of CMC is Journal of t
he Society of Dyers amd C
olourists, 100 128 (1984), which includes lightness L ^* , saturation C ^* , and hue angle h.
^The evaluation is made by adding a visual correction to ^* and is represented by the following equation.

ΔE = [(ΔL ^* / ISL) ² + (ΔC ^* /
cSc) ² + (ΔH ^* / SH) ² ] ^1/2 (ISL: correction coefficient for lightness ΔL ^* , cSc: correction coefficient for saturation ΔC ^* , SH: correction coefficient for hue angle ΔH ^* )

Also, yellow (Y), magenta (M),
Red (R), blue (B), and green (G) gray tones (gloss levels 10 to 15), which are superimposed images of magenta (M) and cyan (C), and yellow (Y) and cyan (C), respectively. And an evaluation of reproducibility with respect to the manuscript was also performed. The evaluation method is based on the evaluation method using the above-mentioned CMC equation.

Further, a full-color image of four colors was produced, and the value obtained by subtracting the reflectance when a blank sheet was measured from the reflectance of the non-image portion was evaluated as the fog reflectance and evaluated as the fog density. Here, TC-6DS (manufactured by Tokyo Denshoku) was used for measuring the reflectance.

Further, the fixing property was improved by the CLC500 modified machine.
Nip 6.5mm, process speed 120mm / se
c, a temperature adjustment is performed at 5 ° C. intervals within a temperature range of 80 ° C. to 230 ° C. to obtain a fixed image (including a low-temperature offset image), and a load of 50 g / cm ² is applied to the silk image paper [Lenz Cleaning] Paper “d
esper (R) "(Ozu Paper Co.,
[Ltd)], and the temperature at which the rate of temperature decrease before and after the rubbing is less than 10% is evaluated as the fixing start point.

Table 3 shows the combinations of the examples and the results. In Example 1, an image having a gloss level of 40 was also obtained, and the comparison was performed.

[0109]

[Table 3]

[0110]

According to the multicolor image forming method of the present invention, a full-color image having a balanced hue and dot fidelity and having a uniform image quality without any discomfort even in an image including black characters. Can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an electrophotographic apparatus suitable for the present invention.

Continuation of the front page (56) References JP-A-3-87841 (JP, A) JP-A-7-77832 (JP, A) JP-A-3-39971 (JP, A) (58) Fields studied (Int .Cl. ⁷ , DB name) G03G 9/09

Claims (6)

(57) [Claims] 1. A multicolor image forming method for developing, transferring, and fixing at least a yellow toner, a magenta toner, and a cyan toner, wherein the weight average diameter of the yellow toner, the magenta toner, and the cyan toner is 9 μm or less; The glossiness of the image is 50 or less, and the hue angle h ^* and lightness L ^* of the yellow toner, magenta toner, and cyan toner in each of the monochrome images are 85 ≦ h ^* (Y) ≦ 100, 80 ≦ L ^* ( Y) ≦ 110 345 ≦ h ^* (M) ≦ 359, 30 ≦ L ^* (M) ≦ 50 245 ≦ h ^* (C) ≦ 265, 40 ≦ L ^* (C) ≦ 60 Multicolor image forming method. 2. The multicolor image forming method according to claim 1, wherein the glossiness of at least each single color image is 30 or less. 3. The shape factor SF1 of the yellow toner, magenta toner and cyan toner measured by Luzex.
The multicolor image forming method according to claim 1, wherein each of SF1 and SF2 satisfies 100 ≦ SF1 ≦ 150 and 100 ≦ SF2 ≦ 140. 4. The toner according to claim 1, wherein said yellow toner, magenta toner and cyan toner are obtained by directly polymerizing at least a polymerizable monomer in an aqueous medium. The multicolor image forming method described in the above. 5. A molecular weight distribution (M) of a resin component in each toner.
5. A multicolor image forming method according to claim 1, wherein in n), a component having a molecular weight satisfying Mn <2000 is present in an amount of 0.01 to 10% by weight based on the total amount of the resin. . 6. The toner according to claim 1, wherein the yellow, magenta and cyan colorants are contained in an amount of 1 to 15 parts by weight based on 100 parts by weight of the resin component of the toner. Multicolor image forming method.