JP2769855B2 - Color image forming method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a color image forming method for a full-color copying machine.

[Related Art] In recent years, the development from monocolor copying to full-color copying has been rapidly progressing in copying machines and the like, and the study and commercialization of two-color copying machines and full-color copying machines have been increasing. For example, "Journal of the Society of Electrophotography" Vol22, No1 (1983)
Also, there are reports of color reproducibility and gradation reproducibility as described in the Journal of the Electrophotographic Society, Vol 25, No1, P52 (1986).

However, full color electrophotographic images that are currently in practical use are not immediately compared with the real ones such as televisions, photographs, and color prints, and for those who see color images that are more beautifully processed than the real ones, It is not always satisfactory.

Color image formation by full-color electrophotography generally reproduces all colors using three color toners of three primary colors, yellow, magenta, and cyan.

In this method, first, an electrostatic latent image is formed on a photoconductive layer by passing light from a document through a color separation light transmission filter having a complementary color relationship with the color of the toner. Next, the toner is held on a support through development and transfer steps. Next, the above-described steps are sequentially performed a plurality of times, and while the registration is being performed, the toner is superimposed on the same support, and a final full-color image is obtained by one-time fixing.

The developing method used at this time is described in U.S. Pat.
8,552, cascade development method, U.S. Pat.No. 2,874,063
The magnetic brush method described in Japanese Patent Application Laid-Open No. H11-216, and other touch-down methods.

Of these, the most commonly used method is the magnetic brush method. In this method, magnetic particles such as steel and ferrite are used as a carrier. The developer including the toner and the magnetic carrier is held by a magnet, and the developer is arranged in a brush shape by the magnetic field of the magnet. When the magnetic brush comes into contact with the electrostatic latent image surface on the photoconductive layer, only the toner is attracted from the brush to the electrostatic latent image to perform development.

However, this method has extremely low development efficiency because the ratio of the consumable toner in the magnetic brush in the developing section is small. For example, only 1 to 5% of the total developer may be used. Also, if a large amount of developer is used to increase the development efficiency, the size and weight of the developing device will be increased, which is unsuitable for reducing the size and weight of the copying machine.

In particular, since a full-color copying machine requires at least three developing units, it is impossible to reduce the size of the full-color copying machine.

In terms of image quality, traces of rubbing by the magnetic brush are generated on the developed image like sweeping, and strong mixing of toner and carrier inside the developing unit causes deterioration of charging and causes toner to adhere to non-image areas. However, there is a problem such as that is easy to come out.

In a color electrophotography method in which development is performed a plurality of times and several types of toner layers of different colors are required to be superimposed on the same support, the following items are necessary and sufficient conditions that the color toner should have. Can be

(1) The fixed toner is required to be in a state of almost complete melting such that the shape of the toner particles cannot be discriminated so as not to irregularly reflect light and hinder color reproduction. It must be a colored toner having transparency that does not interfere with the differently colored toner layers underlying the toner layer.

(2) Each of the constituent toners must have balanced hue and spectral reflection characteristics and sufficient saturation.

The electrophotographic characteristics of the toner include the following.

(3) It is necessary that the respective toners have substantially the same amount of triboelectric charging and have good charging characteristics with little environmental dependency.

(4) It is necessary to have favorable transportability and mixing properties that can be smoothly supplied from the hopper to the developing device and that can be easily mixed with the carrier and the developer.

However, at present, there is no color developing method that satisfies all of the above performances.

For example, as proposed by the present applicant in Japanese Patent Application Laid-Open No. 59-26757 or the like, there is a type which is used as a full-color toner using a color toner kit including three types of toners of three primary colors.

However, although these combinations are relatively balanced with respect to color tone reproduction, there are still points to be improved in electrophotographic characteristics, such as charging characteristics other than storage stability and durability in repeated copying. ing.

In addition, the above proposal is to obtain a black color by superimposing the three color toners, so that a subtle color tone difference between these three colors and development-transfer-
The difference in superposition at the time of fixing must be reflected in the black color tone, and the complexity of color matching of each color toner during the toner manufacturing process and the development-transfer process and the fixing process of the copying process must be highly accurate. Inevitably, the process becomes complicated and causes a cost increase.

The applicant has previously proposed a full-color toner kit and a developer, a color toner composition and an image forming method.

In this method, each of the constituent toners has a well-balanced hue and spectral reflection characteristics and sufficient saturation. However, since a magenta toner uses a dye-based colorant, a pigment-based colorant is used. Compared with the yellow toner, cyan toner, and black toner, the amount of triboelectric charge is slightly different, and the environmental dependence of the charging characteristics is also slightly different. Therefore, in a halftone image that requires a delicate color balance, the requirement has not been sufficiently satisfied.

The light resistance of the colorant is inferior to that of pigment-based coloring. Therefore,
When a full-color image is stored, only the magenta color gradually fades due to light irradiation, resulting in an image with poor color balance.

Further, if the copy image is sandwiched between the vinyl chloride mats, the adverse effect that the dye in the toner contaminates the vinyl chloride mats tends to occur. This also means that the carrier or sleeve is contaminated during development, and the developing properties of the toner are reduced, and in the fixing step of the copying machine, the so-called offset development in which the colorant adheres to the fixing roller is likely to occur. is there. Therefore, there are disadvantages that the developing characteristics are deteriorated due to carrier contamination and the fog is deteriorated, the copy image is stained by offset, and the life of the fixing roller is shortened.

Therefore, it is desirable to apply a pigment excellent in light fastness to the magenta toner. However, with a toner using only the magenta pigment, the obtained image has a saturation Color reproducibility is poor.

The pigment / dye combination type magenta toner can increase the saturation, but has a drawback due to the combination type.

Since the affinity between the dye and the pigment used is poor, they mutually repel each other in the binder resin during the dispersion step, making it difficult to make the color tone uniform. In addition, since the compatibility of each dye / pigment with the binder resin is not uniform, the two are not simultaneously in the same dispersion state, and the pigment is poorly dispersed or the dispersion time is too long. As a result, separation of the dye tends to occur. The use of a toner in which the colorant is unevenly distributed as described above results in inferior charging characteristics as an electrophotograph, causes fogging, contamination due to toner scattering inside the machine, and also reduces the translucency of an OHP image. .

That is, in a multicolor electrophotography method including magenta toner, cyan toner, yellow toner, and black toner, the hue of each toner is balanced, the saturation is sufficient, and the triboelectric charging characteristics of each toner are almost equal. At the same time, there is no color image forming method that does not lower the developing characteristics of each toner.

Further, in recent years, as disclosed in, for example, Japanese Patent Application Laid-Open No. 62-299869, it is desired to reduce the toner particle size for the purpose of improving the quality of a copied image. However, by simply reducing the toner particle size,
Although the resolution and definition of a full-color image can be increased, various problems arise due to the small particle size.

The first is the dispersion of the colorant described above. It is self-evident that the smaller the toner particle size is, the more easily the charging characteristics are affected by the uneven distribution of the colorant. Accordingly, there is a demand for a toner having well-dispersed and well-balanced hue and spectral reflection characteristics and sufficient saturation including not only magenta but also a colorant of another color.

Further, by increasing the surface area by reducing the particle size of the toner, the charging characteristics of the toner are more likely to be affected by the environment.

Further, the surface area is increased by reducing the particle size of the toner, so that the toner transportability and scattering are deteriorated. Further, fogging is worsened by reducing the particle size of the toner.

At present, there is no full-color toner capable of satisfying all of the various problems described above and a developing method therefor.

[Problems to be solved by the invention] However, an object of the present invention is to solve the above-mentioned problems,
It is another object of the present invention to provide a color image forming method capable of coping with a toner having a small particle diameter.

That is, an object of the present invention is to provide a color image forming method using a toner having a well-balanced hue and spectral reflection characteristics and sufficient saturation in magenta toner, cyan toner, yellow toner and black toner. It is.

Another object is to provide a color image forming method using a magenta toner, a cyan toner, a yellow toner, and a black toner having excellent light fastness.

Another object is to provide a color image forming method using a magenta toner, a cyan toner, a yellow toner, and a black toner having charging characteristics excellent in environmental stability.

Another object of the present invention is to provide a color image forming method using a heat roller fixing toner having good fixability and particularly good offset resistance.

Another object is to provide a color image forming method using magenta toner, cyan toner, yellow toner, and black toner having good transportability.

Still another object is to provide a color image forming method using a magenta toner, a cyan toner, a yellow toner, and a black toner with less scattering and fogging.

[Means and Actions for Solving the Problems] A feature of the present invention is a color image forming method using a multicolor electrophotography method using magenta toner, cyan toner, yellow toner and black toner. The magenta toner is a toner having polyester resin particles containing a quinacridone pigment and a xanthene dye treated with a phenolic resin and a flow improver, and the cyan toner is a polyester resin containing a copper phthalocyanine blue pigment. A toner containing particles and a flow improver, the yellow toner is a toner having polyester resin particles containing an azo yellow pigment and a flow improver, and the black toner contains carbon black as a colorant. Use of toner having polyester resin particles and a flow improver Located over the image forming method, jumping of transferring developing the color toner adhering onto the developing sleeve and the carrier surface on the photosensitive drum &
The use of a brush (J / B) development method.

The present applicant has previously shown that it is important for the color reproducibility of a full-color toner, especially for each color toner to fall within a certain chromaticity range.

In particular, magenta toner has the above-mentioned disadvantages. That is, (1) when only a pigment is used as a coloring agent, the color reproducibility does not fall within a favorable chromaticity range, and the copied image has a reduced saturation.

(2) In addition, when only a dye is used, light resistance, development characteristics, PVC resistance, fixability, and the like are poor.

(3) When the pigment-dye combination system is used, the dispersion of the colorant is poor, and the developability and the light transmission are poor.

However, as a result of intensive studies, the present inventors have prevented the migration of the dye by using a dye treated with a resin in a pigment-dye system. Further, the pigment has good light resistance, development characteristics, and resistance to PVC. It is possible to obtain a magenta toner having a good chromaticity range with good color reproducibility without deteriorating the properties and fixing properties.

 The present inventors presume the reason for this as follows.

This treated dye is obtained by including and dispersing a xanthene dye in a phenol resin with a phenol resin. The state in which these are dispersed in the toner is a form in which the xanthene dye is dissolved and dispersed in the toner as a single xanthene dye. It is considered that the dye-dispersed phenolic resin is not dispersed in the toner. In this case, the xanthene dye is wrapped and held in the phenol resin, does not migrate into the toner and does not adversely affect the developing characteristics of the toner, etc., significantly reduces the contamination of the fixing roller, and improves the PVC stain resistance. .

In particular, when a dye that is not treated with a resin is used, the xanthene dye present on the toner surface reduces the chargeability of the toner.However, when a xanthene dye treated with a phenol resin is used, the xanthene dye is added to the toner surface. Since the toner does not deteriorate the charging characteristics due to the presence of the toner, the charging property of the toner due to an environmental change is stable.

Furthermore, the present inventors have proposed using carbon black as a colorant for a full-color black toner.

The black toner using such carbon black has a high concealing property, and a portion where the four color toners overlap each other exhibits a deep black color. Therefore, in copying a photograph or the like, the color saturation increases.

 Hereinafter, the present invention will be described in detail.

An example of a full-color electronic copying machine to which the color electrophotographic method according to the present invention is applied will be described with reference to FIG.

The electrostatic latent image formed on the photosensitive drum 1 by an appropriate means is visualized by a developer in a developing unit 2-1 attached to a rotary developing unit 2 rotating in the direction of the arrow. This developing toner is transferred by a transfer charger 8 to a transfer material held on a transfer drum 6 by a gripper 7.

Next, the rotary developing unit rotates as the second color, and the developing unit
Reference numeral 2-2 faces the photosensitive drum 1. Then, the toner is developed with the developer in the developing device 2-2, and the developed toner is also transferred onto the same transfer material as above.

Further, the third color and the fourth color are similarly performed. In this manner, the transfer drum 6 rotates a predetermined number of times while holding the transfer material, and an image of a predetermined number of colors is multiplex-transferred. The transfer material subjected to the multiple transfer is separated from the transfer drum 6 by a separation charger 9 and passes through a fixing device 10 to become a final full-color copy image.

The replenishment toner supplied to the developing units 2-1 to 2-4 is supplied from a replenishment hopper 3 provided for each color by a predetermined amount based on a replenishment signal via the toner transport cable 4 to the center of the rotary development unit 2. And is sent to each developing device. This replenishment toner is uniformly mixed in advance with the developer in the developing device so as to have a predetermined developer concentration in the developing device.

Then, the supply screw 16 in the toner transport cable 4 rotates for a predetermined time in accordance with the signal from the developer concentration detector, and replenishes the toner from the replenishing hopper 3 to the developing device 2.

As a developing method, a two-component developing method may be used.
It is more preferable in the point of sweep marks.

That is, a bias electric field composed of an AC component and a DC component is applied between the developing sleeve 13 and the photosensitive drum 1 having an electrostatic latent image, and the bias electric field is applied to the volume of the space formed by the developing sleeve 13 and the photosensitive drum 1. The volume occupied by the carrier in the developing section of the developing sleeve 13 is 1.5 to 40%, preferably 2.0 to 30%.
The peak-to-peak voltage is a voltage that does not destroy the electrostatic latent image and moves the carrier between the developing sleeve 13 and the photosensitive drum 1 in the developing area. In the developing section, the toner on the developing sleeve 13 and the toner adhering to the carrier surface are transferred and developed on the photosensitive drum 1 in the developing section.

The composition of the full-color toner polyester resin used in the present invention is as follows.

That is, in such a composition, 45 to 55 mol% of all components are alcohol components, and 55 to 45 mol% are acid components.

As the alcohol component, ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol,
Triethylene glycol, 1,5-pentanediol, 1,6-
Hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, and a bisphenol derivative represented by the formula (A); (Wherein R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10) Also, diols represented by the formula (B); And polyhydric alcohols such as glycerin, sorbit and sorbitan.

The divalent carboxylic acid containing 50 mol% or more of the total acid component includes phthalic acid, terephthalic acid, isophthalic acid,
Benzenedicarboxylic acids such as phthalic anhydride or anhydrides thereof; alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid, azelaic acid or anhydrides thereof, and further, succinic acid substituted with an alkyl group having 6 to 18 carbon atoms Or anhydrides thereof; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, and itaconic acid, and anhydrides thereof; and the trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, Benzophenone tetracarboxylic acid and its anhydride are exemplified.

The alcohol component of the polyester resin particularly preferred in the practice of the present invention is a bisphenol derivative represented by the above formula (A), and the acid component is phthalic acid, terephthalic acid, isophthalic acid or anhydride thereof; succinic acid, n −
And dicarboxylic acids such as dodecenyl succinic acid or its anhydride, fumaric acid, maleic acid, and maleic anhydride, and trimellitic acid or its tricarboxylic acid anhydride.

This is because the polyester resins obtained with these acids and alcohols exhibit sharp melting properties, have good color mixing properties as toners for full-color and heat roller fixing, and have excellent offset resistance.

Furthermore, the glass transition temperature of the polyester resin obtained here is 50 to 70 ° C., preferably 55 to 65 ° C., and further, the number average molecular weight n is 1,500 to 7,000, preferably 2,000 to 5,000, and the weight average molecular weight w is 6,000 to 150,000. Is 10,000-100,0
Desirably it is 00.

The acid value is 90 or less, preferably 50 or less, the OH value is
It is desirably 50 or less, preferably 30 or less. This is because when the number of terminal groups in the molecular chain increases, the toner becomes more environmentally dependent on the charging characteristics of the toner when the toner is used.

The quinacridone pigment for magenta and the xanthene dye used in the present invention are as follows.

Representative examples of quinacridone pigments include: and so on. Among them, CI Pigment Red 122 is particularly suitable as a magenta colorant.

Also, as typical examples of the xanthene dye used in the present invention, Is mentioned.

All have a clear bluish pink color.

, Are basic dyes and therefore have some hygroscopicity. Considering the compatibility with the resin, in the present invention, CISolvent Red is oil-soluble, has excellent compatibility with the resin, and has a large coloring power. 49. is particularly suitable.

The phenolic resin for treating a xanthene dye used in the present invention includes the following as a monomer constitution.

As phenols, all known phenols such as phenol, cresol, xylate, alkylphenol, paraphenylphenol and bisphenol A, and as aldehydes such as formaldehyde, paraformaldehyde, hexamethylenetetramine and furfural can be used.

Among them, it is particularly preferable to use a phenol resin which is a condensate of tert-butylphenol and formaldehyde since the dispersion state of the dye is good.

The method of treating the xanthene dye with the phenol resin in the present invention includes: (1) a method of melt-kneading the xanthene dye and the phenol resin with a two-roll mill, a Banbury mixer, a kneader, a three-roll mill, or the like; Dissolve the phenolic resin in a suitable solvent, remove the solvent after dissolving or dispersing the xanthene dye there,
(3) a method of dissolving and dispersing a xanthene dye in a mixture of phenol and formaldehyde and adding an alkali to form a three-dimensional mixture by heating; (4) dissolving and dispersing the xanthene dye in a mixture of phenol and formaldehyde, A method in which a novolak resin is prepared in the presence of a catalyst, and hexamethylenetetramine or the like is added as a crosslinking agent to cure the resin.

The xanthene dye treated with the phenolic resin by these methods is dried and pulverized, then melt-kneaded with a polyester resin as a binder resin, and uniformly dispersed.

In the present invention, when treating a xanthene dye with a phenolic resin, the quinacridone pigment can also be dispersed and treated in the same manner as the xanthene dye.

In the present invention, the ratio of the phenolic resin for treatment to the xanthene dye is preferably from 100: 10 to 100: 200. This is the result of detailed studies by the present inventors,
When the amount of the phenol resin is less than 100: 10 with respect to the dye, the processing effects such as the effect of preventing the migration of the dye by the phenol resin as described above are almost lost. It is known that phenolic resin is originally easily discolored by heat, oxygen, etc. Conversely, if the phenolic resin is more than 100: 200, the color of the discolored phenolic resin significantly reduces the quality of the copied image . Therefore, processing within the above-mentioned use range is very effective because it has an effect of preventing dye migration without deteriorating copy image quality.

Examples of the copper phthalocyanine-based blue pigment used in the present invention include CI Pigment Blue 15, CI Pigment Blue 16,
CI pigment blue 17 or a phthalocyanine skeleton having a structure represented by the formula,
And copper phthalocyanine pigments which are individually substituted.

As the azo yellow pigment used in the present invention, CI Pigment Yellow 1, CI Pigment Yellow 2, CI Pigment Yellow 3, CI Pigment Yellow 4, CI Pigment Yellow 5, CI Pigment Yellow 6, CI Pigment Yellow 7, CI Pigment Yellow 10 CI Pigment Yellow 11, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, and CI Pigment Yellow 17.

As for the colorant content, for the yellow toner that is sensitive to the transparency of the OHP film, the binder resin
12 parts by weight or less with respect to 100 parts by weight, preferably 0.5 part
~ 7 parts by weight is desirable.

If the amount exceeds 12 parts by weight, the reproducibility of green, red, which is a mixed color of yellow, and human skin color as an image is poor.

For other magenta (the combined amount of pigment and resin-treated dye) and cyan color toner, the amount is preferably 15 parts by weight or less, more preferably 0.1 to 9 parts by weight, based on 100 parts by weight of the binder resin.

Further, in the case of magenta, in order to make use of only the advantages of the dyes and pigments described above, it is preferable that the use ratio is in the following range.

Resin-treated dye amount: pigment = 1: 100 to 10: 1, more preferably
1:50 to 5: 1 is desirable.

In particular, for a black toner using two or more colorants in combination, the addition of a total colorant amount of 20 parts by weight or more not only tends to cause spent to the carrier, but also causes a large amount of colorant to be exposed on the toner surface. As a result, the fusing of the toner to the drum and the anxiety of the fixing property also increase. Therefore, the amount of the colorant is preferably 3 to 15 parts by weight based on 100 parts by weight of the binder resin.

The particle size of the carbon black used as the colorant of the black toner is 50 to 70 mμ, preferably 50 to 60 mμ. The toner containing carbon black having a particle size of less than 50 mμ has a chromaticity that shifts to yellowish, not only does not provide a sharp black color, but also makes it extremely difficult to disperse the carbon black, and the carbon exposed on the toner surface Black becomes uneven. Therefore, the adhesion of the fluidity improver is deteriorated and the fluidity is significantly reduced, so that a good triboelectric charge cannot be obtained, resulting in fogging and toner scattering. On the other hand, when the particle size exceeds 70 μm, the blackness of the carbon black is low, and an image showing a vivid black color cannot be obtained.

The oil absorption of this carbon black is 50-100cc /
100 g, preferably 60-80 cc / 100 g. If the oil absorption exceeds 100 cc / 100 g, the structure of the carbon black becomes longer, the conductivity increases, and the triboelectric charge of the toner decreases, causing fogging and scattering. If the oil absorption is less than 50 cc / 100 g, a high image density cannot be obtained.

The carbon black contained in the resin is a binder resin
2.1 to 10.0 parts by weight based on 100 parts by weight, preferably 3.0 to 10.0 parts by weight
6.0 parts by weight. If the carbon black content is less than 2.1 parts by weight, a high image density cannot be obtained, and the uniformity of the solid portion decreases, and if it exceeds 10.0 parts by weight, a sufficient triboelectric charge cannot be obtained.

In the measurement of the physical properties of the carbon black, the particle size was measured by directly and selectively counting the particle size in a scanning electron micrograph.

 The method for measuring the oil absorption is as described below.

It is also preferable that the toner according to the present invention contains a charge control agent in order to stabilize the negative charge characteristics. In this case, a colorless or light-colored negative charge controlling agent which does not affect the color tone of the toner is preferable. Examples of the negative charge control agent include an organometallic complex such as a metal complex of an alkyl-substituted salicylic acid (for example, a chromium complex or a zinc complex of di-tert-butylsalicylic acid). When a negative charge control agent is blended in the toner, 0.1 to 100 parts by weight of the binder resin is used.
It is preferable to add 10 parts by weight, preferably 0.5 to 8 parts by weight.

Particle size distribution (colorant-containing resin particles having no flow improver such as silica, aluminum oxide, and titanium oxide described below) of the classified products of magenta toner, cyan toner, yellow toner, and black toner obtained using the above-described materials Is
Volume average particle size is 4.0 ~ 16.0μm, preferably 6.0 ~ 14.0μ
m, 50% or less of 5.04 μm or less of the number average distribution, preferably
It is 40% or less, and 20.2 μm or more of the volume average distribution is 9% or less, preferably 5% or less, and furthermore, the ratio α of volume average particle diameter to number average particle diameter (α = volume average particle diameter / number average (Particle size) is 1.7 or less, preferably 1.4 or less.

This is because, when the volume average particle size exceeds 16.0 μm and / or the volume average distribution of 20.2 μm or more exceeds 9%, so-called scattering, such as image roughness and character bleeding, tends to increase.

When the volume average particle diameter is less than 4.0 μm and / or the number average distribution of 5.04 μm or less exceeds 50%, the amount of toner scattered increases, especially in a high-temperature and high-humidity environment. This causes contamination of the fiber portion of the developer concentration detector, and furthermore, scattered matter accumulates on the sliding portion, thereby causing immobility. Further, particularly in a low-temperature and low-humidity environment, the amount of triboelectric charge per toner particle becomes very large, and as a result, the amount of toner developed on the image portion of the electrostatic latent image on the photosensitive drum becomes small. The density of the copied image is low or the color reproduction is poor. Furthermore, even if a small amount of the electrostatic latent image scatters and adheres to the non-image portion of the electrostatic latent image on the photosensitive drum, it often causes fogging and cleaning failure.

When the ratio α between the volume average particle diameter and the number average particle diameter exceeds 1.7, the particle size distribution is wide, so that the frictional charge distribution of the toner is widened, and the toner is charged in the opposite polarity (positive charge in the present invention). A lot of toner is generated. As a result, an image with poor fog is obtained.

As the flow improver used in the present invention, any one can be used as long as it can be added to the colorant-containing resin particles to increase the flowability before and after the addition.

For example, a fluorine resin powder, that is, fine powder of vinylidene fluoride, fine powder of polytetrafluoroethylene, or the like; or a fatty acid metal salt, such as zinc stearate, calcium stearate, or lead stearate; or a metal oxide,
Aluminum oxide, titanium oxide, zinc oxide powder or the like; or finely divided silica, ie, wet-process silica, dry-process silica, a silane coupling agent to the silica,
Examples include treated silica that has been surface-treated with a titanium coupling agent, silicon oil, or the like.

Preferred flow improvers are fine powders produced by vapor phase oxidation of silicon halide compounds, so-called dry silica or fumed silica,
It is manufactured by a conventionally known technique. For example, it utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows.

SiCl ₄ + 2H ₂ + O ₂ → SiO ₂ + 4HCl Preferred examples of the flow improver include aluminum oxide and titanium oxide obtained in the same manner as in the above-mentioned production process.

The particle size is preferably in the range of 0.001 to 2 μm as an average primary particle size, and particularly preferably 0.002 to 2 μm.
It is preferable to use a fine powder within a range of 0.2 μm.

Commercially available fine silica powder produced by vapor phase oxidation of a silicon halide used in the present invention includes, for example, those commercially available under the following trade names.

AEROSIL 130 200 300 380 TT600 MOX170 MOX 80 COK 84 Ca-O-SiL (CABOT Co.) M-5 MS-7 MS-75 HS-5 EH-5 Wacker HDK N 20 (WACKER-CHEMIE GMBH) V15 N20E T30 T40 DC Fine Silica (Dow Corning Co.) Fransol (Fransil) Further, a silica fine powder produced by vapor-phase oxidation of the silicon halide is used as a treated silica fine powder. Is more preferable. It is particularly preferable that the silica fine powder be treated so that the degree of hydrophobicity measured by a methanol titration test shows a value in the range of 30 to 80.

The method for imparting hydrophobicity is provided by reacting with silica fine powder or chemically treating with an organic silicon compound that physically adsorbs.

As a preferred method, silica fine powder produced by vapor phase oxidation of a silicon halide is treated with an organosilicon compound.

Examples of such organosilicon compounds are hexamethyldisilazane, trimethylsilane, trimethylchlorosilane,
Trimethylethoxysilane, dimethyldichlorosilane,
Methyltrichlorosilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α
-Chloroethyltrichlorosilane, ρ-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane,
Triorganosilyl mercaptan, trimethylsilyl mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, dimethylethoxysilane,
Dimethyldimethoxysilane, diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane, and 2 to 12 siloxane units per molecule with terminal positions For example, dimethylpolysiloxane containing a hydroxyl group bonded to one Si unit may be used for each unit. These are used alone or as a mixture of two or more.

The particle size of the treated silica fine powder is 0.003-0.1μm
It is preferable to use those in the range of Commercial products include Taranox-500 (Talco), AEROSIL R-972
(Nippon Aerosil).

The amount added to the colorant-containing resin particles, the resin particles
0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight per 100 parts by weight
Parts by weight. If it is less than 0.01 part by weight, there is no effect on improving the fluidity, and if it exceeds 10 parts by weight, fogging and bleeding of letters,
Promote in-flight scattering.

Examples of the carrier used in the present invention include, for example, surface-oxidized or unoxidized iron, nickel, copper, zinc, cobalt,
Metals such as manganese, chromium, and rare earths and alloys or oxides thereof and ferrites can be used. There is no particular restriction on the manufacturing method.

Further, a system in which the surface of the carrier is coated with a resin or the like is particularly preferable in the J / B developing method described above. As the method, any conventionally known method such as a method of dissolving or suspending a coating material such as a resin in a solvent, coating and adhering to a carrier, and a method of simply mixing with a powder can be applied.

The fixing substance on the carrier surface varies depending on the toner material, for example, polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride, silicone resin, polyester resin, metal complex of ditersharry butylsalicylic acid, styrene resin,
Acrylic resin, polyacid, polyvinyl butyral,
It is suitable to use nigrosine, amino acrylate resin, basic dyes and lakes thereof, fine silica powder, fine alumina powder or the like alone or in combination, but it is not necessarily limited thereto.

The amount of the compound to be treated may be appropriately determined so that the carrier satisfies the above conditions, but is generally desirably 0.1 to 30% by weight (preferably 0.5 to 20% by weight) based on the carrier of the present invention.

These carriers have a 250 mesh pass, 400 mesh on, 70% by weight or more, and the average particle size is
It preferably has a thickness of 10 to 100 μm, preferably 20 to 70 μm.

A particularly preferred embodiment is a ternary ferrite of Cu-Zn-Fe, the surface of which is coated with a styrene-based resin or a styrene-based resin and a fluorine-based resin. These resins have not only a high triboelectric charging ability but also a stable triboelectric charging ability that is not easily affected by the environment, with respect to the toner in the color developing method of the present invention.

As the styrene-based resin, any resin obtained using polystyrene or a monomer polymerizable with styrene can be used. Preferred resins are styrene-acrylic resins, particularly styrene-methyl methacrylate resins, and styrene-based resins. 2-ethylhexyl acrylate, styrene-2-ethylhexyl acrylate-methyl methacrylate, and the like.

As the fluorinated resin, any fluorinated vinyl resin can be used, and particularly preferred resins include polyvinylidene fluoride, polytetrafluoroethylene, and vinylidene fluoride-tetrafluoroethylene copolymer.

The coating amount of these resins on ferrite is
It is 0.01 to 10% by weight, preferably 0.05 to 5% by weight.

When a styrene-based resin and a fluorine-based resin are used in combination, the content of the fluorine-based resin in the coating agent is preferably 90% by weight or less, and more preferably 70% by weight or less.

This is because when the coating amount of the resin exceeds 10% by weight, the carrier causes agglomeration.
If it is less than, the uncoated portion increases,
This is because the amount of triboelectricity of some toners is reduced, and fog is deteriorated.

On the other hand, when the amount of the fluorine-based resin exceeds 90% by weight in the coating agent, the ferrite is not coated well and only the resin is released. Therefore, the amount of the fluororesin used is preferably 90% by weight or less in the coating agent.

The coated ferrite carrier has a sharp particle size distribution, provides favorable triboelectrification to the color toner kit of the present invention, and has the effect of improving electrophotographic properties.

When a two-component developer is prepared by mixing with the color toner according to the present invention, the mixing ratio is from 2.0% by weight to 15.0% by weight, preferably from 3.0% by weight, as the toner concentration in the developer.
Good results are usually obtained at 13.0% by weight. If the toner density is less than 2.0%, the image density is low and cannot be used practically.
If it exceeds 5%, fog and scattering in the machine are increased, and the useful life of the developer is shortened.

 Hereinafter, each measurement method in the present invention will be described.

(1) Measurement of glass transition temperature Tg In the present invention, measurement is performed using a differential thermal analysis measurement device (DSC measurement device), DSC-7 (manufactured by PerkinElmer).

The measurement sample is precisely weighed in an amount of 5 to 20 mg, preferably 10 mg.

Put this in an aluminum pan and use an empty aluminum pan as a reference.
The measurement is performed at normal temperature and normal humidity at a heating rate of 10 ° C./min.

In this heating process, an endothermic peak of a main peak in a temperature range of 40 to 100 ° C. is obtained.

The intersection of the line of the midpoint of the baseline before and after the endothermic peak appears and the differential heat curve is defined as the glass transition temperature Tg in the present invention.

(2) Measurement of molecular weight distribution In the present invention, the molecular weight distribution was measured by high performance liquid chromatography (JASCO TRI ROTAR-VI HPLC system manufactured by JASCO Corporation). The column is Toso TSK gel-2000, manufactured by Toyo Soda Industry Co., Ltd.
-3000, -4000, -5000 were used, and THF was used as a solvent. Detect
or is Shodex RISE-51 manufactured by Showa Denko KK, and the measurement conditions were as follows: Flow rate 1.0 ml / min, column temperature 40 ° C, Inj vol. 75
Performed in μl.

The molecular weight of the sample was calculated from the relationship between the logarithmic value of a calibration curve prepared from several types of monodisperse polystyrene standard samples and the count number, based on the molecular weight distribution of the sample.

As a standard polystyrene sample for preparing a calibration curve, for example, a molecular weight of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ .5.1 manufactured by Pressure Chemical Co. or Toyo Soda Industries Co., Ltd.
× 10 ⁴ , 1.1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶
It is appropriate to use at least about 10 standard polystyrene samples.

(3) Particle size distribution measurement Coulter counter TA-II type (manufactured by Coulter, Inc.) was used as the measuring device, and an interface (manufactured by Nikkaki) for outputting the number average distribution and volume average distribution, and a CX-1 personal computer (manufactured by Canon) ) Is connected, and a 1% NaCl aqueous solution is prepared as the electrolytic solution using primary sodium chloride.

As a measuring method, a surfactant as a dispersing agent, preferably 0.1 to 5 ml of an alkylbenzene sulfonate is added to the electrolytic aqueous solution of 100 to 150 ml, and a measurement sample of 0.5 to 50 mg is further added.
Add.

The electrolytic solution in which the sample was suspended was subjected to a dispersion treatment for about 1 to 3 minutes using an ultrasonic disperser.
The volume average distribution and the number average distribution are obtained by measuring the particle size distribution of the particles of up to 40 μm.

From the obtained volume average distribution and number average distribution, respective values of volume average distribution, number average particle size, 5.04 μm or less of the number average distribution, and 20.2 μm or more of the volume average distribution are obtained.

(4) Measurement of oil absorption (DBP method) Measurement of oil absorption is performed in accordance with ASTM method D 2414-79.

Operate the faucet of the absorber meter and completely fill DBP (dibutyl phthalate) so that no air bubbles remain in the automatic burette system.

Spring tension 2.68kg / cm Rotor rotation speed 125rpm Scale of torque limit switch 5 Damper valve 0.150 DBP dripping speed 4ml / min After adjusting the DBP dripping speed by actual measurement, dry a certain amount in the absorption meter mixing chamber The sample is put, the buret counter is set to 0 point, and the switch is automatically turned on to start dropping. When the torque reaches the set point (5 in this case), the limit switch is activated and the dripping stops automatically,
The scale (V) of the bullet counter at that time is read, and the oil absorption is calculated by the following equation.

OA: Oil absorption (ml / 100g) V: DBP used up to the end point (limit switch operating point) (ml) W: Weight of dried sample (g) [Examples] Will be described in detail.

Example 1 Polyester resin obtained by condensation of propoxylated bisphenol and fumaric acid (n = 3,000, w = 17,000, T
g = 57 ° C., acid value 9.0, OH value = 17) A full-color toner was obtained by using a coloring agent and a charge controlling agent in the amounts shown in Table 1 with respect to 100 parts by weight.

The production method was performed by a master batch method. First,
Melt and knead the polyester resin and the colorant in an amount 6 times the amount of the colorant with a three-roll mill.
It was crushed in the following to obtain a colored resin for a master batch. Next, the polyester resin, the charge control agent, and the colored resin for the master batch were weighed so as to have the above-mentioned predetermined amounts, and were premixed by a Henschel mixer. Thereafter, the mixture is melted and kneaded with a three-roll mill, and after cooling, about 1 to 2 mm using a hammer mill.
The mixture was coarsely pulverized to an appropriate degree, and then finely pulverized to a particle size of 30 μm or less by a pulverizer using an air jet method. Further, the obtained finely pulverized product was classified, and for the magenta toner, the volume average particle diameter was 8.20 μm and the number average particle diameter was 6.35 μm (accordingly, α
= 1.29), 30.0% for the number average distribution of 5.04 μm or less, and 0.1% for the volume average distribution of 20.2 μm or more. The particle size distributions of other toners are shown in Table 2. 0.5 parts by weight of silica fine powder treated with hexamethyldisilazane as a flow improver and 0.5 parts by weight of aluminum oxide fine powder were externally added to 100 parts by weight of each classified product to obtain a full color toner.

As a carrier, styrene-2-ethylhexyl acrylate-methyl methacrylate (copolymer weight ratio 50: 20: 3)
Using a Cu-Zn-Fe ferrite carrier coated with 0.5% by weight of (0) (average particle size 41.5μm; 150 mesh pass 400 mesh on 85.5% by weight), a developer is prepared so that the toner concentration of each color becomes 5% by weight. did.

Using these developers and toners, an image output test was performed with a full-color copying machine CLC-1 manufactured by Canon.

As a result, there was no offset to the fixing roll even after printing for 15,000 sheets in the full-color mode, and a full-color image faithfully reproducing the original color chart without fog was obtained. In addition, the black image portion had a deep black color excellent in concealment. Further, the toner transportability in the copying machine was good, and a stable image density was obtained. Even when an OHP film was used, the transparency of the toner was very favorable. Further, an image output test was conducted by changing the environment to low temperature, low humidity, and high temperature and high humidity. As a result, good results were obtained with stable image density, no fog, and almost no toner scattering.

The image obtained here was irradiated with sunlight for three months, but each color did not fade and was the same as when the image was formed.

Example 2 To 100 parts by weight of the classified product of each toner obtained in Example 1, 0.6 parts by weight of silica fine powder treated with hexamethyldisilazane and 0.2 parts by weight of titanium oxide were externally added to obtain a full-color toner. Except for this, an image output test was performed in the same manner as in Example 1 using a Canon full-color copying machine CLC-1.

As a result, no offset occurred even after 10,000 sheets of printing in the full-color mode, and a full-color image faithfully reproducing the original color chart without fog was obtained. Further, the black image portion had a deep black color excellent in concealment. Further, the toner transportability in the copying machine was good, and a stable image density was obtained. When an OHP film was used, the transmittance was good.

Further, an image output test was conducted by changing the environment to low temperature, low humidity, and high temperature and high humidity. As a result, good results were obtained without fog and little toner scattering. The image obtained here was irradiated with sunlight for three months, and the same as when the image was formed without fading of each color.

Example 3 Polyester resin obtained by condensation of propoxylated bisphenol, ethoxylated bisphenol, terephthalic acid and fumaric acid (n = 2,100, w = 18,000, Tg = 58
C., acid value = 8, OH value = 22) 100 parts by weight, using the coloring agent and the charge control agent in the above prescribed amounts (Table 3), in the same manner as in Example 1. A classified toner having the particle size distribution shown was prepared. As a flow improver, 0.5 parts by weight of silica fine powder treated with hexamethyldisilazane was externally added to 100 parts by weight of each toner classified product to obtain a full-color toner.

The carrier is vinylidene fluoride-tetrafluoroethylene copolymer (copolymerization weight ratio 8: 2) and styrene-
Cu-Zn-Fe-based ferrite carrier coated with 0.7% by weight of acrylic 2-ethylhexyl-methyl methacrylate (copolymerization ratio 45:20:35) at a weight ratio of 50:50 (average particle size)
49μm; 250 mesh pass 400 mesh on 93.5% by weight)
Was used to prepare a developer such that the toner concentration of each color became 9% by weight.

Using these developers and toners, an image output test was performed with a full-color copying machine CLC-1 manufactured by Canon.

As a result, there is no offset of the fixing roller even after endurance of 13,000 sheets in the full-color mode, and a full-color image that faithfully reproduces the original color chart without fog is obtained. It had a blackish color. Further, the toner transportability in the copying machine was good, and a stable image density was obtained. Even when the OHP film was used, the transparency of the toner was very good.

Further, an image output test was conducted by changing the environment to low temperature, low humidity, and high temperature and high humidity. As a result, good results were obtained with stable image density, no fog, and almost no toner scattering.

The image obtained here was irradiated with sunlight for three months, but each color was the same as when the image was formed without fading.

Comparative Example 1 A classified magenta toner was prepared in the same manner as in Example 1 except that 1.7 parts by weight of CI Basic Violet 10 was used as a colorant for magenta toner (volume average particle size 8.02 μm, number average particle size) 6.21μm (α = 1.29), number average distribution 5.04μm or less 28.4%, volume average distribution 20.2μm or more
0.1%). As the other-color toner classified products, those used in Example 1 were used.

Thereafter, in the same manner as in Example 1, a developer and a toner were prepared, and an image output test was performed using a Canon full-color copying machine CLC-1.

As a result, even after printing 10,000 sheets in full color mode,
A good image without fog was obtained. Further, the toner transportability in the copying machine was good, and a stable image density was obtained. Even when an OHP film was used, the transparency of the toner was good.

However, when the image was tested by changing the environment to low temperature, low humidity, and high temperature and high humidity, the magenta color slightly decreased in density at low temperature and low humidity, and a little fog (scattering of toner to non-image areas) was observed. In wet conditions, magenta toner was slightly scattered.

Further, when the image obtained here was illuminated with sunlight for three months, only the magenta color was faded, resulting in an image with poor color reproduction and low saturation.

Comparative Example 2 3.5 parts by weight of CI Pigment Red 206 as a colorant for magenta toner and not subjected to phenol resin treatment
A magenta toner classified product was prepared in the same manner as in Example 1 except that CI Solvent Red 49 (1.4 parts by weight) was used (volume average particle diameter 8.22 μm, number average particle diameter 6.35 μm (α = 1.
29), number average distribution 5.04μm or less 29.2%, volume average distribution
20.2 μm or more and 0.1%). As the other-color toner classified products, those used in Example 1 were used.

Thereafter, in the same manner as in Example 1, a developer and a toner were prepared, and an image output test was performed using a full-color copying machine CLC-1 manufactured by Canon.

As a result, when an image was displayed in the full-color mode, color reproduction was reasonable. However, when an image was output in the magenta single-color mode, the dispersion of the colorant was poor, and a lumpy pattern of the colorant appeared.

Comparative Example 3 A classified magenta toner was prepared in the same manner as in Example 1 except that only 4.4 parts by weight of CI Pigment Red 206 was used as a colorant for magenta toner (volume average particle size 8.07 μm, number average particle size). Diameter 6.30μm (α = 1.28), number average distribution 5.04μm or less 31.1%, volume average distribution 20.2μm or more
0.1%). The other-color toner classification product used in Example 1 was used.

Thereafter, in the same manner as in Example 1, a developer and a toner were prepared, and an image output test was performed using a Canon full-color copying machine CLC-1.

As a result, the obtained image was poor in color reproducibility with reduced saturation.

Comparative Example 4 A developer and a toner were prepared in the same manner as in Example 1, except that the particle sizes of the classified products of the magenta and cyan toners were adjusted as shown in Table 5.

In the same manner as in Embodiment 1, a full-color copier made by Canon
An image output test was performed using CLC-1.

As a result, the magenta toner scattered in the aircraft was very poor,
It adhered in a scattered state to the obtained image. Further, the density of the cyan toner was very low, and the fog was poor. Therefore, the obtained image had poor color reproduction and poor fog.

[Effects of the Invention] As described above, according to the color image forming method of the present invention, no offset occurs and an original color chart without fog can be faithfully produced even after an image output test, for example, after printing 15,000 sheets. A full-color image to be reproduced can be obtained.

Further, the black image portion can obtain deep black with excellent concealment.

Further, the toner transportability in the copying machine is good, a stable image density can be obtained, and a good image with little fog and toner scattering can be obtained even in a low-temperature, low-humidity, high-temperature, high-humidity environment.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a full-color electrophotographic apparatus to which a color electrophotographic method according to the present invention is applied. REFERENCE SIGNS LIST 1 photosensitive drum 2 developing device 3 supply hopper 4 toner supply cable 5 supply cylinder 6 transfer drum 7 gripper 8 transfer charger 9 separation charging Device, 10 Fixing device 13 Developing sleeve, 16 Supply screw

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Ichiro Osaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-63-301960 (JP, A) JP-A-63 -231369 (JP, A) JP-A-64-9466 (JP, A) JP-A-62-15557 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08 G03G 15/01

Claims (2)

(57) [Claims] In a color image forming method using a multicolor electrophotography using a magenta toner, a cyan toner, a yellow toner and a black toner, the magenta toner is treated with a quinacridone pigment and a phenol resin. A toner having polyester resin particles containing a xanthene dye and a flow improver, the cyan toner is a toner having polyester resin particles containing a copper phthalocyanine blue pigment and a flow improver, and the yellow toner is A toner having polyester resin particles containing an azo yellow pigment and a flow improver, wherein the black toner is a toner having polyester resin particles containing carbon black as a colorant and a flow improver. Color image forming method. 2. The method according to claim 1, wherein a jumping and brush developing method for transferring and developing the color toner adhered on the developing sleeve and the carrier surface to the photosensitive drum is used.
The color image forming method as described above.