JP2011237648A - Electrostatic charge image developing magenta toner, developer, image forming method and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide electrostatic charge image developing magenta toner, developer, an image forming method and an image forming apparatus having excellent color reproducibility and light resistance, and capable of suppressing generation of a color deviation and a decline of transfer efficiency.SOLUTION: The electrostatic charge image developing magenta toner contains resin and colorant. The magenta toner contains C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 in a weight ratio of (8:2) to (5:5) as a colorant. A time constant of the electrostatic charge image developing magenta toner is 1100-1300 m/sec.

Description

  The present invention relates to an electrostatic image developing magenta toner, a developer, an image forming method, and an image forming apparatus.

  In an image forming apparatus using an electrophotographic system, an image is formed through, for example, charging, exposure, development, transfer, fixing, cleaning, and static elimination processes. In the charging process, the surface of the photoconductor to be rotated is uniformly charged by the charging device. In the exposure process, the charged photoconductor surface is irradiated with laser light by the exposure device, and an electrostatic latent image is formed on the surface of the photoconductor. Is done. Next, in the development process, the electrostatic latent image on the surface of the photoconductor is developed with a developer by a developing device to form a toner image on the surface of the photoconductor. In the transfer step, the toner image on the surface of the photoconductor is transferred by the transfer device. Transferred onto the transfer material. Thereafter, in the fixing step, the toner image is fixed on the transfer material by being heated by a fixing device. Further, the transfer residual toner remaining on the surface of the photoconductor after the image forming operation is removed by a cleaning device in a cleaning process and collected in a predetermined recovery unit, and the residual charge on the surface of the photoconductor after cleaning is removed in a static elimination process. In order to prepare for the next image formation, the charge is removed by the charge removal device.

  In a full-color image forming apparatus, each process of charging, exposure, transfer, fixing, cleaning, and static elimination is performed three times according to three colors of yellow, magenta, and cyan. Or it is performed four times by adding black to three colors of yellow, magenta, and cyan. In the developing process, three colors of yellow, magenta, and cyan, or four colors of toner are used in which black is added to the three colors of yellow, magenta, and cyan.

  As a toner used for forming such a full-color image, a toner having excellent color reproducibility is required so that an image faithful to an original can be obtained. For example, Patent Documents 1 to 4 disclose a rhodamine-based colorant. A magenta toner containing the compound is disclosed.

  Patent Document 5 discloses a magenta toner for electrophotography including Pigment Red 48-1 as a colorant. According to the magenta toner for electrophotography disclosed in Patent Document 5, a red image recorded by an office stationery or the like can be reproduced with high saturation.

  Further, the toner is required to be capable of suppressing color misregistration and a decrease in transfer efficiency. For example, Patent Document 6 discloses at least aggregated particles composed of polymer fine particles, colorant fine particles, and release agent fine particles as toner particles. A dry toner comprising at least a quinacridone colorant and a soluble azo colorant, wherein the total content of the quinacridone colorant and the soluble azo colorant is from 1 to 20% by mass. The mass ratio is quinacridone colorant: soluble azo colorant = 10: 90 to 50:50, and in a number-based particle size frequency distribution measured with a flow particle image analyzer (Flow Particle Image Analyzer). The toner circle equivalent number average diameter is 3 to 7 μm, and the ratio of the number of toners in the range of the circle equivalent diameter of 0.6 to 2 μm is 1 to 30. Several percent toner is disclosed.

  The physical properties of the toner related to the transfer are considered to depend on the van der Waals force. Like the toner disclosed in Patent Document 6, the number of toners in the range of the circle equivalent number average diameter and the circle equivalent diameter of 0.6 to 2 μm. When the ratio is within the above range, the transferability of the transfer residual toner existing on the photoconductor is remarkably improved, so that an increase in the transfer residual toner is suppressed, and the outline portion of the image, particularly the character image and the line pattern is suppressed. Reproducibility in development can be improved.

JP 2008-287239 A JP 2009-47814 A JP 2009-58745 A JP 2009-169407 A JP-A-63-173066 JP 2004-333629 A

  With the widespread use of full-color image forming devices, there is an increasing demand for color reproducibility of stamped images due to the increase in the use of image forming devices to copy stamped documents and to form images according to image data including stamped images. Is growing. The color of the seal is a vermilion color for a seal, and is a bright vermilion with high brightness.

Vermilion is usually made by mixing yellow toner with magenta toner, but vermilion made by mixing yellow toner with magenta toner has low brightness because the color is clouded by the mixed color, and the color of vermilion cannot be reproduced sufficiently. Examples of the colorant for magenta toner include C.I. I. Pigment red 269, C.I. I. Pigment red 57-1, C.I. I. Pigment Red 122 or the like is used. The ratio of yellow toner to be mixed with magenta toner is determined by image processing technology.
The magenta toner disclosed in Patent Document 5 cannot sufficiently reproduce the color of vermilion.

  On the other hand, the magenta toner disclosed in Patent Documents 1 to 4 can sufficiently reproduce the color of vermilion. This is because the rhodamine compound is a fluorescent pigment. Rhodamine compounds are known to absorb light in the vicinity of 520 nm and emit fluorescence having a fluorescence peak wavelength in a wavelength range of 560 to 600 nm. Using a fluorescent pigment as a colorant, the brightness and saturation can be easily increased, and a bright vermilion with high brightness can be produced.

  However, since the fluorescent pigment is inferior in light resistance, there is a problem in that the imprinted image contained in the copy and the image formed product fades in a relatively fast time.

  Further, the toner disclosed in Patent Document 6 cannot sufficiently suppress the occurrence of color misregistration and the transfer efficiency.

  An object of the present invention is to provide a magenta toner for developing an electrostatic charge image, a developer, an image forming method, and an image forming apparatus, which have good color reproducibility and light fastness, and can suppress occurrence of color misregistration and transfer efficiency. Is to provide.

The present invention includes a binder resin,
C. I. Pigment red 48-3 and C.I. I. Pigment Red 48-1 and a colorant containing 8: 2 to 5: 5 by weight,
A magenta toner for developing electrostatic images, having a time constant of 1100 m / sec or more and 1300 m / sec or less.

Further, the invention is characterized in that the transmittance of light having a wavelength of 440 nm is 30% or more and 45% or less.
The present invention also provides a developer comprising the electrostatic image developing magenta toner and a carrier.

  The present invention also exposes a charged image carrier surface to form an electrostatic image on the image carrier surface, and develops the electrostatic image formed on the image carrier surface using the developer. And forming a toner image.

The present invention also provides an image carrier,
Charging means for charging the image carrier;
Exposure means for exposing the image carrier charged by the charging means to form an electrostatic image on the surface of the image carrier;
An image forming apparatus comprising: a developing unit configured to supply the electrostatic image developing magenta toner in the developer to the image carrier on which the electrostatic image is formed to develop the electrostatic image. is there.

  According to the present invention, the electrostatic image developing magenta toner includes a binder resin and a colorant. The colorant is C.I. I. Pigment red 48-3 and C.I. I. Pigment Red 48-1 is contained in a weight ratio of 8: 2 to 5: 5, and the time constant of the electrostatic image developing magenta toner is 1100 m / sec or more and 1300 m / sec or less.

  The colorant is C.I. I. Pigment red 48-3 and C.I. I. By containing CI Pigment Red 48-1 at a weight ratio of 8: 2 to 5: 5, good light resistance is ensured without using a fluorescent pigment, and color reproducibility with respect to the color of vermilion is good. And a magenta toner for developing an electrostatic image.

  Since the time constant of the electrostatic image developing magenta toner is 1100 m / sec or more and 1300 m / sec or less, the electrostatic adhesion force between the electrostatic image developing magenta toner, the intermediate transfer belt, and the recording medium before fixing is increased. An appropriate range is achieved, and the occurrence of color misregistration and a decrease in transfer efficiency are suppressed, and a high-quality image can be formed.

  According to the invention, the transmittance of light having a wavelength of 440 nm is 30% or more and 45% or less. Thereby, the color of vermilion can be reproduced stably and sufficiently.

  According to the invention, the developer includes the magenta toner for developing an electrostatic charge image of the invention and a carrier. The magenta toner for developing an electrostatic charge image of the present invention has good color reproducibility and light fastness, and can suppress occurrence of color shift and a decrease in transfer efficiency. The developer containing the carrier and the carrier can form a high-quality image that sufficiently reproduces the color of vermilion.

  According to the invention, the image forming method comprises exposing the charged image carrier surface to form an electrostatic charge image on the image carrier surface, and using the developer of the invention, Since the formed electrostatic image is developed to form a toner image, it is possible to form a high-quality image that sufficiently reproduces the color of vermilion.

  According to the invention, the image forming apparatus exposes the image carrier, the charging unit for charging the image carrier, the image carrier charged by the charging unit, and forms an electrostatic image on the surface of the image carrier. The image forming apparatus includes: an exposure unit for forming; and a developing unit for supplying the magenta toner for developing the electrostatic image in the developer of the present invention to the image carrier on which the electrostatic image is formed to develop the electrostatic image. It is possible to form a high-quality image that sufficiently reproduces the colors.

FIG. 6 is a diagram illustrating an image formed using the magenta toner according to the exemplary embodiment. FIG. 6 is a diagram illustrating a state where color misregistration and transfer failure have occurred. 1 is a schematic diagram schematically showing a configuration of an image forming apparatus 100 according to an embodiment of the present invention. FIG. 4 is a schematic view schematically showing a developing device 14 provided in the image forming apparatus 100 shown in FIG. 3.

  An electrostatic image developing magenta toner (hereinafter also simply referred to as “magenta toner”), which is an embodiment of the present invention, comprises magenta toner particles containing at least a binder resin, a magenta colorant, and a release agent.

<Binder resin>
The binder resin is not particularly limited, and a binder resin for color toners is used. Examples thereof include polyester resins, polystyrene resins such as polystyrene and styrene-acrylate copolymer resins, and polymethyl methacrylate. And acrylic resins such as polyethylene, polyolefin resins such as polyethylene, polyurethane, and epoxy resins.

  As the binder resin, a resin obtained by mixing a raw material monomer mixture with a release agent and performing a polymerization reaction may be used. In this case, the binder resin preferably includes a polyester resin. By including the polyester resin in the binder resin, the controllability of the state of dispersion of the release agent is improved, and a magenta toner having further excellent fixability can be obtained. Furthermore, excellent durability and transparency can be imparted to the magenta toner. Binder resin can be used individually by 1 type, or can also use 2 or more types together.

  The polyester resin is not particularly limited and a known one is used. For example, a polycondensation product of polybasic acids and polyhydric alcohols can be mentioned. Polybasic acids are polybasic acids and derivatives of polybasic acids such as acid anhydrides or esterified products of polybasic acids. Polyhydric alcohols are compounds containing two or more hydroxyl groups, and include both alcohols and phenols.

  As polybasic acids, those commonly used as monomers for polyester resins can be used. Examples include aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid and naphthalenedicarboxylic acid, and aliphatic carboxylic acids such as maleic anhydride, fumaric acid, succinic acid and adipic acid. used. Polybasic acids may be used alone or in combination of two or more.

  As polyhydric alcohols, those commonly used as monomers of polyester resins are used. For example, aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol and glycerin, alicyclic polyhydric alcohols such as cyclohexanediol, cyclohexanedimethanol and hydrogenated bisphenol A, bisphenol Aromatic diols such as an ethylene oxide adduct of A and a propylene oxide adduct of bisphenol A are exemplified.

  “Bisphenol A” is 2,2-bis (p-hydroxyphenyl) propane. Examples of the ethylene oxide adduct of bisphenol A include polyoxyethylene-2,2-bis-4-hydroxyphenylpropane. Examples of the propylene oxide adduct of bisphenol A include polyoxypropylene-2,2-bis4-hydroxyphenylpropane. Polyhydric alcohols may be used alone or in combination of two or more.

  The polyester resin can be synthesized by a condensation polymerization reaction. For example, it can be synthesized by polycondensation reaction, specifically dehydration condensation reaction of polybasic acids and polyhydric alcohols in the presence of a catalyst in an organic solvent or without solvent. At this time, a demethanol polycondensation reaction may be carried out using a methyl esterified product of a polybasic acid as part of the polybasic acid. The polycondensation reaction between polybasic acids and polyhydric alcohols may be terminated when the acid value and softening point of the produced polyester resin reach the values in the polyester resin to be synthesized.

  In this polycondensation reaction, by appropriately changing the reaction conditions such as the blending ratio of polybasic acids and polyhydric alcohols and the reaction rate, for example, the content of carboxyl groups bonded to the terminal of the resulting polyester resin, and thus The acid value, softening point, and other physical properties of the resulting polyester resin can also be adjusted.

  The acid value of the binder resin is preferably 5 mgKOH / g or more and 30 mgKOH / g or less. When the acid value of the binder resin is less than 5 mgKOH / g, the affinity between the binder resin and the release agent is greater than when the acid value of the binder resin is 5 mgKOH / g or more. During fixing, the release agent is less likely to elute on the surface of the magenta toner, and high temperature offset is likely to occur as a fixing failure. When the acid value of the binder resin exceeds 30 mgKOH / g, the functional value remaining on the surface of the magenta toner is increased and the moisture is more easily absorbed than when the acid value of the binder resin is less than 30 mgKOH / g. Under wet conditions, the charge amount of the magenta toner may be reduced, and charging stability may be impaired. Furthermore, since the dispersibility of the release agent in the binder resin tends to be lowered, if the kneading is insufficient during the production of the magenta toner, the dispersion diameter of the release agent on the surface of the magenta toner is increased. there is a possibility.

  When the acid value of the binder resin is 5 mgKOH / g or more and 30 mgKOH / g or less, the dispersibility of the release agent in the magenta toner is set to a desired range. Specifically, the release agent on the surface of the magenta toner The dispersion diameter of the toner can be stably less than 300 nm, the decrease in the charge amount of the magenta toner under high humidity conditions can be suppressed, and the binder resin and the release agent can be improved so that the fixing property is improved. The affinity of can be controlled.

  Therefore, the charging stability can be further improved and the fixing property can be improved, so that a high-definition and high-resolution high-quality image can be formed more stably over a long period of time. it can. The acid value of the binder resin is determined by the reaction conditions such as the blending ratio and reaction rate of polybasic acids and polyhydric alcohols in the case of a binder resin raw material monomer mixture, for example, a polyester resin. By appropriately changing the content, the content of the carboxyl group bonded to the terminal of the obtained binder resin, and thus the acid value of the obtained binder resin can be adjusted.

<Magenta colorant>
The magenta colorant contains two specific types of magenta pigments at a specific ratio.

  The two specific types of magenta pigments are C.I. I. Pigment red 48-3, C.I. I. Pigment Red 48-1. The magenta colorant is a combination of these two types of magenta pigments, C.I. I. Pigment Red 48-3, C.I. I. Pigment Red 48-1 is included as an accessory.

  C. I. Pigment Red 48-3 has characteristics such as a strong reddish transmission characteristic and a high purple transmittance. C. I. Pigment Red 48-1 has a characteristic that the transmittance of purple is low and the coloring power is weak.

  The specific ratio (mixing ratio) is C.I. when the total weight of the magenta colorant is 10. I. Pigment red 48-3: C.I. I. Pigment Red 48-1 is in the range of 8: 2 to 5: 5.

C. I. Pigment red 48-3 and C.I. I. By using a magenta colorant containing CI Pigment Red 48-1 in a weight ratio of 8: 2 to 5: 5, a yellow toner is mixed with the magenta toner of this embodiment, and a vermilion formed on a recording medium When the visible image is represented by the L ^* a ^* b ^* color system (Munsell color system) where the lightness is L ^* , the red-green hue is a ^* , and the yellow-blue hue is b ^* Can be included in the color gamut of (L ^* , a ^* , b ^* ) = (55, 62, 33) which is the color gamut of vermilion. Or the color gamut of (L ^* , C ^* ) = (55, 70) which is the color gamut of vermilion when expressed by a color system (Munsell color system) with lightness L ^* and saturation C ^* Can be included. Therefore, a magenta toner that can sufficiently reproduce the vermilion color, which is a bright vermilion with high lightness L ^* , can be obtained.

The L ^* a ^* b ^* system color system is a means that is useful for representing a color numerically. L ^{* in the} z-axis direction represents lightness, and a ^* and b ^{* on the} x-axis and y-axis ^. Both represent hue and saturation. “Lightness” refers to the relative brightness of a color, “hue” refers to a hue such as red, yellow, green, blue, and purple, and “saturation” refers to the degree of vividness of the color.

  Since yellow toner has high brightness regardless of the yellow colorant used, the color gamut of the vermilion visible image is determined by the characteristics of the magenta toner. Examples of the yellow colorant contained in the yellow toner include C.I. I. Pigment yellow 74 or C.I. I. Pigment Yellow 185 can be used.

C. I. When the weight ratio of Pigment Red 48-1 is less than 20%, C.I. I. Since the characteristics of Pigment Red 48-3 are strong, the lightness L ^* of the vermilion color does not appear, and the vermilion color cannot be reproduced sufficiently. C. I. C.I. for Pigment Red 48-3 I. As the ratio of Pigment Red 48-1 increases, the brightness L ^{* of the} visible image formed on the recording medium increases. I. When the weight ratio of CI Pigment Red 48-1 exceeds 50%, C.I. I. Due to the characteristics of the pigment red 48-1, the saturation C ^* of the vermilion color does not appear, and the vermilion color cannot be reproduced sufficiently.

  The vermilion color can be easily realized by including a fluorescent pigment in the magenta toner, but the magenta toner containing the fluorescent pigment has a problem of fading because it is inferior in light resistance. If a substance for improving light resistance is added to the magenta toner containing the fluorescent pigment in order to solve the problem of fading, a new problem may occur with respect to the color developability of the magenta toner. In addition, the development of fluorescent pigments with high light resistance is very expensive.

  The magenta colorant is preferably used as a masterbatch. The master batch can be manufactured, for example, by kneading a synthetic resin melt and a magenta colorant. As the synthetic resin, the same type of resin as the binder resin or a resin having good compatibility with the binder resin is used. The use ratio of the synthetic resin and the magenta colorant is not particularly limited, but is preferably 30 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the synthetic resin. The master batch is used after being granulated to a particle size of, for example, about 2 to 3 mm.

  The content of the magenta colorant in the magenta toner is not particularly limited, but is preferably 4 parts by weight or more and 15 parts by weight or less with respect to 100 parts by weight of the binder resin. When using a masterbatch, it is preferable to adjust the usage amount of the masterbatch so that the content of the magenta colorant in the magenta toner of this embodiment falls within the above range. By setting the content of the magenta colorant in the above range, it is possible to form a good image having sufficient image density, high color developability and excellent image quality.

<Release agent>
The release agent is not particularly limited, and known ones can be used. For example, paraffin waxes and derivatives thereof, and petroleum waxes such as microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin waxes and derivatives thereof, low molecular weight polypropylene waxes and derivatives thereof, and polyolefin polymer waxes and derivatives thereof Examples thereof include hydrocarbon synthetic waxes such as derivatives, carnauba wax and derivatives thereof, and ester waxes.

  The content of the release agent in the magenta toner is preferably 1.5% by weight to 5% by weight with respect to the total weight of the magenta toner. If the content of the release agent is less than 1.5% by weight, the releasability of the magenta toner with respect to the intermediate transfer belt is lowered, and there is a possibility that fixing offset occurs. If the content of the release agent exceeds 5% by weight, the fixing property is good, but the magenta toner aggregates due to the heat of stirring in the developing device, and a good image may not be obtained.

  The acid value of the release agent is preferably less than 4 mgKOH / g. When the acid value of the release agent is 4 mgKOH / g or more, the affinity between the release agent and the binder resin is higher than when the acid value of the release agent is less than 4 mgKOH / g. During fixing, the release agent is less likely to be eluted from the magenta toner, and high temperature offset is likely to occur.

<Charge control agent>
The magenta toner preferably contains a toner additive component such as a charge control agent in addition to the binder resin, the magenta colorant and the release agent. By including a charge control agent, it is possible to impart preferable chargeability to the magenta toner. As the charge control agent, a charge control agent for positive charge control or negative charge control is used.

  Examples of the charge control agent for controlling positive charge include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof, and triphenylmethane. Examples thereof include derivatives, guanidine salts, and amidine salts. Examples of the charge control agent for controlling the negative charge include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, naphthenic acid metal salts, metal complexes and metal salts of salicylic acid and its derivatives ( Examples of the metal include chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, and resin acid soaps. One charge control agent can be used alone, or two or more charge control agents can be used in combination.

  The content of the charge control agent is preferably 0.5 parts by weight or more and 5 parts by weight or less with respect to 100 parts by weight of the binder resin, and more preferably 0.5 parts by weight or more with respect to 100 parts by weight of the binder resin. 3 parts by weight or less. When the content of the charge control agent exceeds 5 parts by weight, the carrier is contaminated by the charge control agent detached from the magenta toner, and the magenta toner cannot be sufficiently charged, and toner scattering may occur. When the content of the charge control agent is less than 0.5 parts by weight, sufficient charging characteristics are not imparted to the magenta toner.

  Such a magenta toner of this embodiment has a time constant τ of 1100 m / sec or more and 1300 m / sec or less. The time constant τ of the magenta toner is defined as a product RC when the resistance of the magenta toner is R and the capacitance of the magenta toner is C.

The reason for this definition is described below.
First, since magenta toner is a dielectric, it has both a resistance component and a capacitance (capacitor) component. Here, when the resistance of the magenta toner is R (Ω) and the electrostatic capacity of the magenta toner is C (F), the state in which the voltage is applied to the magenta toner indicates the resistance of R (Ω) and the static of C (F). It can be compared to a circuit in which electric capacity is connected in series. A DC voltage E (V) is applied to this series circuit, the moment when the DC voltage E is applied is time 0, the current flowing through the circuit at time t is i (t) (A), and the amount of electricity stored in the capacitor is q ( C, Coulomb). At this time, the DC voltage E is represented by the following formula (1).
E = R · i (t) + q / C (1)

Here, since the current is the flow of electrons, that is, the magnitude of the time change of the charge amount, it is expressed as i (t) = dq (t) / dt, and the above equation (1) is expressed by the following equation (2). To be rewritten.
E = [(R · dq (t) / dt) + q] / C (2)

Solving the above equation (2), q (t) is expressed by the following equation (3) with respect to t.
q (t) = CE (1-exp (−t / RC)) (3)

Furthermore, if the voltage across the capacitor is ec, then q (t) = C · ec (t), so the following equation (4) is obtained.
ec (t) = E (1-exp (−t / τ)) (4)

  In the above equation (4), the product RC of R and C is the circuit time constant τ. Therefore, when the resistance of the magenta toner is R and the capacitance of the magenta toner is C, the product RC is defined as the time constant τ of the magenta toner.

  According to the above formula (4), the longer it takes for ec (t) to reach its maximum value E, the greater τ. Since the time constant τ is proportional to the resistance value R and the electrostatic capacity (charge amount) C of the magenta toner, the larger the charge amount induced by the resistance of the magenta toner or the capacitance component of the magenta toner, the more the magenta toner discharges. It takes time. That is, the decrease in frictional charging of the magenta toner is delayed.

  When the time constant τ of the magenta toner is 1100 m / sec or more and 1300 m / sec or less, the charge amount of the magenta toner charged in the development process is appropriately reduced until the transfer process is performed. Since the electrostatic adhesion force between the magenta toner, the intermediate transfer belt, and the recording medium before fixing is in an appropriate range, the occurrence of color misregistration and a decrease in transfer efficiency can be suppressed, and a high-quality image as shown in FIG. Can be formed. FIG. 1 is a view showing an image 200 formed using the magenta toner of the present embodiment. FIG. 2 is a diagram illustrating an image 201 in a state where color misregistration and transfer failure have occurred. In FIG. 2, a range surrounded by the reference symbol “a” indicates a location where color misregistration occurs, and a range surrounded by the reference symbol “b” indicates a location where transfer failure occurs. 1 and 2 are images 200 and 201 formed in vermilion color.

  If the time constant τ of the magenta toner is less than 1100 m / sec, even if the magenta toner is sufficiently charged in the development process, the amount of charge of the magenta toner is too low until the transfer process is performed. The toner charge amount is insufficient, and as shown in FIG. 2, color misregistration and transfer efficiency decrease. If the time constant τ of the magenta toner exceeds 1300 m / sec, the decrease in the charge amount of the magenta toner from the development process to the transfer process is too small, and the charge amount of the magenta toner in the transfer process becomes too large, as shown in FIG. As described above, transfer failure and transfer efficiency decrease.

  The time constant τ of the magenta toner can be adjusted by appropriately selecting the type of each component contained in the magenta toner, the content thereof, and the like. Examples of each component contained in the toner include a binder resin, a magenta colorant, a release agent, a charge control agent, and an organic inorganic additive.

The magenta toner preferably has a light transmittance of 440 nm and a wavelength of 30% to 45%. When the transmittance of light having a wavelength of 440 nm in the magenta toner is 30% or more and 45% or less, the vermilion color, which is a bright vermilion having a high lightness L ^* , can be reproduced stably and sufficiently.

When the transmittance of light having a wavelength of 440 nm in the magenta toner is higher than 45%, even if the mixing ratio of the yellow toner is devised in the image processing, the vermilion color, which is a bright vermilion color with high lightness L ^* , is sufficiently reproduced. There is a risk that it will not be possible.

  As mentioned above, C.I. I. Pigment red 48-3 and C.I. I. By setting the pigment red 48-1 to a weight ratio of 8: 2 to 5: 5, the transmittance of light having a wavelength of 440 nm can be made 30% to 45% in the magenta toner.

  The volume average particle diameter of the magenta toner is preferably 5.0 μm or more and 7.0 μm or less. Further, the content of magenta toner particles having a particle size of 5.0 μm or less in the number particle size distribution is preferably less than 40% by number of all magenta toner particles. When the particle size distribution and number distribution of the magenta toner satisfy this range, scattering of the magenta toner is suppressed, and a high-definition and high-resolution high-quality image can be formed. If the volume average particle diameter of the magenta toner is less than 5.0 μm, toner scattering may occur due to a decrease in fluidity. When the volume average particle diameter of the magenta toner exceeds 7.0 μm, a sufficiently high-definition and high-resolution image cannot be formed. When the content of magenta toner particles having a particle size of 5.0 μm or less in the number particle size distribution is 40% by number or more of all magenta toner particles, there is a possibility that toner scattering due to fluidity drop and fogging due to deterioration of transfer efficiency may occur. .

The volume average particle size (D _50V ) of the magenta toner and the content (number%) of magenta toner particles having a particle size of 5.0 μm or less in the number particle size distribution are determined by a particle size distribution measuring device “Multisizer 3” manufactured by Beckman Coulter, Inc. Measured by. The measurement conditions are shown below.
Aperture diameter: 100 μm
Measurement particle number: 50000 count Analysis software: Coulter Multisizer AccuComp version 1.19 (manufactured by Beckman Coulter, Inc.)
Electrolyte: ISOTON-II (Beckman Coulter, Inc.)
Dispersant: Sodium alkyl ether sulfate

The measurement procedure was as follows: 50 ml of electrolyte, 20 mg of sample toner and 1 ml of dispersant were added to a beaker, a dispersion sample was prepared for 3 minutes with an ultrasonic disperser, and a measurement sample was prepared. Measure. From the obtained measurement results, the volume particle size distribution and the number particle size distribution of the sample particles are obtained, and the volume average particle size (D _50V ) of the magenta toner is obtained from the volume particle size distribution. Further, the content (number%) of magenta toner particles having a particle diameter of 5.0 μm or less is determined from the number particle size distribution.

<External additive>
The magenta toner particles can be used as magenta toners as they are. For example, magenta toner particles and external additives are mixed and external additives are added to the magenta toner particles as magenta toners. Also good. By externally adding external additives, it is possible to improve powder flowability and triboelectric chargeability, to provide heat resistance, to improve long-term storage and cleaning characteristics, and to control wear on the surface of the photoreceptor. .

  Examples of the external additive include silica fine powder, titanium oxide fine powder, and alumina fine powder. One type of external additive can be used alone, or two or more types can be used in combination.

  The content of the external additive is based on 100 parts by weight of the magenta toner particles in consideration of the charging amount necessary for the magenta toner, the influence on the abrasion of the photoconductor by adding the external additive, the environmental characteristics of the magenta toner, and the like. 0.1 parts by weight or more and 10 parts by weight or less is preferable, and 2.0 parts by weight or more and less than 4.0 parts by weight is more preferable. By including 2.0 parts by weight or more and less than 4.0 parts by weight of the external additive, the fluidity is good and the charging of individual magenta toner particles can be appropriately controlled. It is possible to form a high-quality image that does not occur.

  If the content of the external additive is less than 2.0 parts by weight, sufficient fluidity cannot be imparted to the magenta toner (especially magenta toner particles having a small particle size), so that the individual magenta toner particles are sufficient. It is not charged and fogging easily occurs in the non-image area. If the content of the external additive is 4.0 parts by weight or more, the external additives tend to aggregate with each other, and the magenta toner surface cannot be efficiently covered and the fluidity cannot be improved. Magenta toner particles are not sufficiently charged, and fog is likely to occur in non-image areas.

<Method for producing magenta toner>
The magenta toner particles constituting the magenta toner of this embodiment are produced by a pulverization method, a suspension polymerization method, an emulsion polymerization method, a dissolution suspension method, an ester extension polymerization method, or the like.

  An example of a method for producing magenta toner in which magenta toner particles are produced by a pulverization method will be described below.

  A resin composition containing at least a binder resin, a magenta colorant and a release agent is dry-mixed (premixed) with a mixer and melt-kneaded with a kneader. Thereafter, the melt-kneaded product is pulverized and classified using a pulverizer and a classifier to produce magenta toner particles. Next, the magenta toner particles and the external additive are dry-mixed to obtain a desired magenta toner.

  A known mixer can be used for dry mixing. For example, a Henschel mixer (trade name: FM mixer, manufactured by Mitsui Mining Co., Ltd.), a super mixer (trade name, manufactured by Kawata Co., Ltd.) and a mechano mill (product) Name, Okada Seiko Co., Ltd. and other Henschel type mixing devices, Ongmill (trade name, manufactured by Hosokawa Micron Co., Ltd.), hybridization system (trade name, manufactured by Nara Machinery Co., Ltd.), and Cosmo System (trade name, Kawasaki) Heavy Industries, Ltd.).

  As the kneader, known ones can be used, for example, common kneaders such as a twin screw extruder, a three roll and a lab blast mill are used. More specifically, TEM-100B (trade name, 1-axis or 2-axis extruder, such as PCM-65 / 87 and PCM-30 (all are trade names, manufactured by Ikegai Co., Ltd.), Needex (trade names, manufactured by Mitsui Mining Co., Ltd.) And an open roll type kneader. Among these, an open roll type kneader is preferable. The toner raw material mixture may be melt-kneaded using a plurality of kneaders.

  For pulverization of the melt-kneaded product, for example, a jet-type pulverizer that pulverizes using a supersonic jet stream, a space formed between a rotor that is a rotor that rotates at high speed and a liner that is a stator, An impact pulverizer that introduces and pulverizes coarsely pulverized material is used.

  For classification, a known classifier capable of removing excessively pulverized toner particles and coarse toner particles by classification by centrifugal force or classification by wind force is used. For example, a swirl type wind classifier (rotary type wind classifier) or the like is used.

  The magenta toner particles may be spheroidized. As the impact spheroidizing device used for the spheroidizing treatment by mechanical impact force, a commercially available device can be used, for example, Faculty (trade name, manufactured by Hosokawa Micron Corporation) or the like is used. A commercially available device can be used as the hot air spheronizing device used for the spheroidizing treatment with hot air. For example, a surface reformer meteoreinbo (trade name, manufactured by Nippon Pneumatic Kogyo Co., Ltd.) is used.

  The spheronization treatment is preferably performed so that the circularity of the magenta toner is 0.950 or more and 0.960 or less.

  The magenta toner may have a core-shell structure in which the magenta toner particles obtained as described above are used as core particles, and the outer peripheral surface of the core particles is covered with a shell layer containing no magenta colorant.

<Developer>
The magenta toner of the present embodiment produced as described above can be used as it is as a one-component developer, or can be mixed with a carrier and used as a two-component developer. By including the magenta toner of the present exemplary embodiment, it is possible to reproduce a vermilion color which is a bright vermilion with high lightness, and it is possible to obtain a developer excellent in light resistance.

  In addition, the magenta toner of the present embodiment has good fixability and good charge stability, and can be a developer having stable characteristics over a long period of use, so that good developability is maintained. Developer that can be used.

  The developer is preferably a two-component developer comprising the magenta toner of the present invention and a carrier. Since the magenta toner of the present invention is excellent in storage stability, it is possible to obtain a two-component developer that suppresses a decrease in developer fluidity and has good charging stability and developability. By using such a two-component developer, high-definition and high-resolution high-quality images can be stably formed over a long period of time without toner scattering.

  As the carrier, magnetic particles are used. Examples of the magnetic particles include metals such as iron, ferrite and magnetite, and alloys of these metals with metals such as aluminum or lead. Among these, ferrite is preferable.

  As the carrier, a resin-coated carrier in which magnetic particles are coated with a resin, or a resin-dispersed carrier in which magnetic particles are dispersed in a resin may be used. Although there is no restriction | limiting in particular as resin used for a resin coating carrier, For example, an olefin resin, a styrene resin, a styrene acrylic resin, a silicon resin, an ester resin, a fluorine-containing polymer resin, etc. are mentioned. Moreover, although it does not restrict | limit especially as resin used for a resin dispersion type carrier, For example, a styrene acrylic resin, a polyester resin, a fluorine resin, a phenol resin, etc. are mentioned.

  The shape of the carrier is preferably a spherical shape or a flat shape. The volume average particle diameter of the carrier is not particularly limited, but considering high image quality, it is preferably 10 μm or more and 100 μm or less, and more preferably 30 μm or more and 50 μm or less. When the volume average particle diameter of the carrier is less than 10 μm, the magnetic force between the carrier and the developing roller is weaker than when the volume average particle diameter of the carrier is 10 μm or more. It becomes easy to be developed together with the toner. When the volume average particle diameter of the carrier exceeds 100 μm, there is a possibility that the individual magenta toner particles cannot be sufficiently charged.

  When the volume average particle diameter of the carrier is 10 μm or more and 100 μm or less, the chance of contact between the magenta toner and the carrier can be increased, so that charging of individual magenta toner particles is controlled and sufficient toner charging property is imparted. be able to.

  The volume average particle diameter of the carrier can be measured using a laser diffraction, scattering type particle size distribution measuring device Microtrac (trade name: Microtrac MT3000, manufactured by Nikkiso Co., Ltd.).

<Image forming apparatus>
FIG. 3 is a schematic diagram schematically showing the configuration of the image forming apparatus 100 according to the embodiment of the present invention. The image forming apparatus 100 is a multifunction machine having both a copying function, a printer function, and a facsimile function, and forms a full-color or monochrome image on a recording medium in accordance with transmitted image information. That is, the image forming apparatus 100 has three types of printing modes, ie, a copier mode (copying mode), a printer mode, and a FAX mode. Operation input from an operation unit (not shown), personal computer, portable terminal device, information A print mode is selected by a control unit (not shown) in response to reception of a print job from an external device using a recording storage medium or a memory device.

  The image forming apparatus 100 includes a photosensitive drum 11 that is an image carrier, an image forming unit 2, a transfer unit 3, a fixing unit 4, a recording medium supply unit 5, and a discharge unit 6. Each member constituting the image forming unit 2 and some members included in the transfer unit 3 are black (b), cyan (c), magenta (m) and yellow (y) included in the color image information. In order to correspond to image information, four each are provided. Here, each member provided by four according to each color is distinguished by attaching an alphabet representing each color to the end of the reference symbol, and when referring collectively, only the reference symbol is used.

  The image forming unit 2 includes a charging unit 12, an exposure unit 13, a developing device 14, and a cleaning unit 15. The charging unit 12 and the exposure unit 13 function as a latent image forming unit. The charging unit 12, the developing device 14, and the cleaning unit 15 are arranged around the photosensitive drum 11 in this order. The charging unit 12 is disposed below the developing device 14 and the cleaning unit 15 in the vertical direction.

  The photosensitive drum 11 is a roller-like member that is provided so as to be rotatable about an axis by a rotation driving unit (not shown), and on which an electrostatic latent image is formed. The rotation driving means of the photosensitive drum 11 is controlled by a control means realized by a central processing unit (CPU). The photosensitive drum 11 includes a conductive substrate (not shown) and a photosensitive layer (not shown) formed on the surface of the conductive substrate.

  The charging unit 12 faces the photosensitive drum 11 and is arranged so as to be separated from the surface of the photosensitive drum 11 along the longitudinal direction of the photosensitive drum 11 with a gap, and the surface of the photosensitive drum 11 has a predetermined polarity and Charge to potential. As the charging unit 12, a charging brush type charger, a charger type charger, a sawtooth type charger, an ion generator, or the like can be used. In the present embodiment, the charging unit 12 is provided so as to be separated from the surface of the photosensitive drum 11, but is not limited thereto. For example, a charging roller may be used as the charging unit 12, and the charging roller may be arranged so that the charging roller and the photosensitive drum are in pressure contact with each other, or a contact charging type charger such as a charging brush or a magnetic brush may be used. .

  The exposure unit 13 is arranged such that light of each color information emitted from the exposure unit 13 passes between the charging unit 12 and the developing device 14 and is irradiated on the surface of the photosensitive drum 11. The exposure unit 13 branches the image information into light of each color information of black, cyan, magenta, and yellow in the unit, and the surface of the photosensitive drum 11 charged to a uniform potential by the charging unit 12 is light of each color information. To form an electrostatic latent image on the surface. As the exposure unit 13, for example, a laser scanning unit including a laser irradiation unit and a plurality of reflecting mirrors can be used. In addition, a unit in which an LED array or a liquid crystal shutter and a light source are appropriately combined may be used.

  The cleaning unit 15 uses the developing device 14 to transfer the toner image formed on the surface of the photosensitive drum 11 to a recording medium, and then removes the toner remaining on the surface of the photosensitive drum 11 to remove the surface of the photosensitive drum 11. Clean. For the cleaning unit 15, for example, a plate-like member such as a cleaning blade is used. In the image forming apparatus of the present embodiment, an organic photosensitive drum is used as the photosensitive drum 11, and the surface of the organic photosensitive drum is mainly composed of a resin component, and thus is generated by corona discharge by a charging device. Deterioration of the surface of the organic photosensitive drum is likely to proceed due to the chemical action of ozone. However, the deteriorated surface portion is worn by receiving the rubbing action by the cleaning unit 15, and the gradually deteriorated surface portion is surely removed. Therefore, the problem of surface deterioration due to ozone or the like is practically solved, and the charging potential by the charging operation can be stably maintained over a long period of time. Although the cleaning unit 15 is provided in this embodiment, the present invention is not limited to this, and the cleaning unit 15 may not be provided.

  According to the image forming unit 2, the surface of the photosensitive drum 11 that is uniformly charged by the charging unit 12 is irradiated with signal light according to image information from the exposure unit 13 to form an electrostatic latent image. Then, the toner is supplied from the developing device 14 to form a toner image. After the toner image is transferred to the intermediate transfer belt 25, the toner remaining on the surface of the photosensitive drum 11 is removed by the cleaning unit 15. This series of toner image forming operations is repeatedly executed to form an image.

  The transfer means 3 is disposed above the photosensitive drum 11 and has four intermediate portions corresponding to the intermediate transfer belt 25, the driving roller 26, the driven roller 27, and the image information of each color of black, cyan, magenta, and yellow. A transfer roller 28, a transfer belt cleaning unit 29, and a transfer roller 30 are included. The intermediate transfer belt 25 is an endless belt-like member that is stretched around a driving roller 26 and a driven roller 27 to form a loop-shaped movement path, and is driven to rotate in the direction of an arrow B. The driving roller 26 is provided so as to be rotatable around its axis by driving means (not shown), and the intermediate transfer belt 25 is driven to rotate in the direction of arrow B by the rotational driving. The driven roller 27 is provided so as to be able to be driven and rotated by the rotational drive of the driving roller 26, and applies a certain tension to the intermediate transfer belt 25 so that the intermediate transfer belt 25 does not loosen. The intermediate transfer roller 28 is provided in pressure contact with the photosensitive drum 11 via the intermediate transfer belt 25 and capable of being driven to rotate about its axis by a driving unit (not shown). The intermediate transfer roller 28 is connected to a power source (not shown) for applying a transfer bias as described above, and has a function of transferring the toner image on the surface of the photosensitive drum 11 to the intermediate transfer belt 25.

  When the intermediate transfer belt 25 passes through the photoconductive drum 11 while being in contact with the photoconductive drum 11, the toner on the surface of the photoconductive drum 11 is transferred from the intermediate transfer roller 28 disposed opposite to the photoconductive drum 11 through the intermediate transfer belt 25. A transfer bias having a polarity opposite to the charging polarity is applied, and the toner image formed on the surface of the photosensitive drum 11 is transferred to the intermediate transfer belt 25. In the case of a full-color image, each color toner image formed on each photoconductor drum 11 is sequentially transferred onto the intermediate transfer belt 25 to form a full-color toner image.

  The transfer belt cleaning unit 29 is provided so as to face the driven roller 27 through the intermediate transfer belt 25 and to contact the outer peripheral surface of the intermediate transfer belt 25. The toner adhering to the intermediate transfer belt 25 due to contact with the photosensitive drum 11 causes the recording medium to be contaminated. Therefore, the transfer belt cleaning unit 29 removes and collects the toner on the surface of the intermediate transfer belt 25.

  The transfer roller 30 is provided in pressure contact with the drive roller 26 via the intermediate transfer belt 25, and can be driven to rotate about an axis by a drive unit (not shown). The toner image carried on the intermediate transfer belt 25 and conveyed at the pressure contact portion between the transfer roller 30 and the driving roller 26, that is, the transfer nip portion, is transferred to a recording medium fed from a recording medium supply means 5 described later. The The recording medium carrying the toner image is fed to the fixing unit 4.

  According to the transfer unit 3, the toner image transferred from the photosensitive drum 11 to the intermediate transfer belt 25 at the pressure contact portion between the photosensitive drum 11 and the intermediate transfer roller 28 rotates the intermediate transfer belt 25 in the arrow B direction. It is conveyed to a transfer nip portion by driving, and transferred to a recording medium there.

  The fixing unit 4 is provided downstream of the transfer unit 3 in the conveyance direction of the recording medium, and includes a fixing roller 31 and a pressure roller 32. The fixing roller 31 is rotatably provided by a driving unit (not shown), and fixes an unfixed toner image carried on the recording medium to the recording medium by heating and melting the constituent toner. A heating unit (not shown) is provided inside the fixing roller 31. The heating unit heats the fixing roller 31 so that the surface of the fixing roller 31 reaches a predetermined temperature (hereinafter also referred to as “heating temperature”). For example, a heater or a halogen lamp can be used as the heating means. The heating means is controlled by fixing condition control means described later. The control of the heating temperature by the fixing condition control means will be described in detail later.

  A temperature detection sensor (not shown) is provided near the surface of the fixing roller 31, and the temperature detection sensor detects the surface temperature of the fixing roller 31. The detection result by the temperature detection sensor is written in the storage unit of the control means described later. The pressure roller 32 is provided so as to be in pressure contact with the fixing roller 31 and is supported so as to be driven to rotate by the rotation drive of the pressure roller 32. When the toner is melted by heat from the fixing roller 31 and the toner image is fixed on the recording medium, the pressure roller 32 presses the toner and the recording medium to assist the fixing of the toner image onto the recording medium. A pressure contact portion between the fixing roller 31 and the pressure roller 32 is a fixing nip portion.

  According to the fixing unit 4, the recording medium onto which the toner image is transferred by the transfer unit 3 is sandwiched between the fixing roller 31 and the pressure roller 32, and the toner image is recorded under heating when passing through the fixing nip portion. By being pressed against the medium, the toner image is fixed on the recording medium and an image is formed.

  The recording medium supply unit 5 includes an automatic paper feed tray 35, a pickup roller 36, a transport roller 37, a registration roller 38, and a manual paper feed tray 39. The automatic paper feed tray 35 is a container-like member that is provided in the lower part of the image forming apparatus 100 in the vertical direction and stores a recording medium. Examples of the recording medium include plain paper, color copy paper, overhead projector sheet, and postcard. The pick-up roller 36 takes out the recording medium stored in the automatic paper feed tray 35 one by one and feeds it to the paper transport path S1. The conveyance rollers 37 are a pair of roller members provided so as to be in pressure contact with each other, and convey the recording medium toward the registration rollers 38. The registration rollers 38 are a pair of roller members provided so as to be in pressure contact with each other, and the recording medium fed from the conveyance roller 37 is used to convey the toner image carried on the intermediate transfer belt 25 to the transfer nip portion. Synchronously, it is fed to the transfer nip. The manual paper feed tray 39 is a device for taking a recording medium into the image forming apparatus 100 by a manual operation. The recording medium taken from the manual paper feed tray 39 passes through the paper conveyance path S2 by the conveyance roller 37. Then, it is fed to the registration roller 38. According to the recording medium supply means 5, the toner image carried on the intermediate transfer belt 25 is conveyed to the transfer nip portion of the recording medium supplied one by one from the automatic paper feed tray 35 or the manual paper feed tray 39. In synchronism with this, the sheet is fed to the transfer nip portion.

  The discharge unit 6 includes a conveyance roller 37, a discharge roller 40, and a discharge tray 41. The conveyance roller 37 is provided downstream of the fixing nip portion in the sheet conveyance direction, and conveys the recording medium on which the image is fixed by the fixing unit 4 toward the discharge roller 40. The discharge roller 40 discharges the recording medium on which the image is fixed to a discharge tray 41 provided on the upper surface in the vertical direction of the image forming apparatus 100. The discharge tray 41 stores a recording medium on which an image is fixed.

The image forming apparatus 100 includes a control unit (not shown). For example, the control unit is provided in an upper part of the internal space of the image forming apparatus 100 and includes a storage unit, a calculation unit, and a control unit. The storage unit of the control unit stores various setting values via an operation panel (not shown) arranged on the upper surface of the image forming apparatus 100, detection results from sensors (not shown) arranged at various locations inside the image forming apparatus 100, and external Image information from the device is input. In addition, programs for executing various means are written. Examples of the various means include a recording medium determination unit, an adhesion amount control unit, and a fixing condition control unit. As the storage unit, those commonly used in this field can be used, and examples thereof include a read only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD). As the external device, an electric / electronic device that can form or acquire image information and can be electrically connected to the image forming apparatus 100 can be used. For example, a computer, a digital camera, a television, a video recorder, a DVD recorder HD DVD, Blu-ray disc recorder, facsimile device, portable terminal device and the like. The arithmetic unit takes out various data (image formation command, detection result, image information, etc.) written in the storage unit and programs of various means, and performs various determinations. The control unit sends a control signal to the corresponding device according to the determination result of the calculation unit, and performs operation control. The control unit and the calculation unit include a processing circuit realized by a microcomputer, a microprocessor, or the like provided with a central processing unit (CPU). The control means includes a main power supply together with the processing circuit described above, and the power supply supplies power not only to the control means but also to each device in the image forming apparatus 100.

  FIG. 4 is a schematic view schematically showing the developing device 14 provided in the image forming apparatus 100 shown in FIG. The developing device 14 includes a developing tank 20 and a toner hopper 21. The developing tank 20 is disposed so as to face the surface of the photosensitive drum 11, and is a container that supplies toner to an electrostatic latent image formed on the surface of the photosensitive drum 11 and develops it to form a visible toner image. It is a shaped member. The developing tank 20 accommodates toner in its internal space and accommodates roller members such as the developing roller 50, the supply roller 51, and the stirring roller 52, and rotatably supports them. Moreover, you may accommodate a screw member instead of a roller-shaped member. The developing device 14 according to the present embodiment stores the magenta toner according to the embodiment of the present invention described above as the toner in the developing tank 20.

  An opening 53 is formed on a side surface of the developing tank 20 facing the photosensitive drum 11, and a developing roller 50 is rotatably provided at a position facing the photosensitive drum 11 through the opening 53. The developing roller 50 is a roller-like member that supplies toner to the electrostatic latent image on the surface of the photosensitive drum 11 at the pressure contact portion or the closest portion to the photosensitive drum 11. When supplying the toner, a potential having a polarity opposite to the charging potential of the toner is applied to the surface of the developing roller 50 as a developing bias voltage (hereinafter simply referred to as “developing bias”). As a result, the toner on the surface of the developing roller 50 is smoothly supplied to the electrostatic latent image. Further, by changing the developing bias value, the toner amount supplied to the electrostatic latent image, that is, the toner adhesion amount of the electrostatic latent image can be controlled.

  The supply roller 51 is a roller-like member that faces the developing roller 50 and can be driven to rotate, and supplies toner around the developing roller 50.

  The agitation roller 52 is a roller-like member provided so as to be able to be driven to rotate while facing the supply roller 51, and feeds toner newly supplied from the toner hopper 21 into the developing tank 20 to the periphery of the supply roller 51. The toner hopper 21 is provided so that a toner replenishing port 54 provided at the lower part in the vertical direction and a toner receiving port 55 provided at the upper part in the vertical direction of the developing tank 20 communicate with each other. Add toner. Further, the toner may be directly supplied from each color toner cartridge without using the toner hopper 21.

  In the image forming apparatus 100 as described above, by forming an image using the developer of the present invention, even if the image forming apparatus 100 is a high-speed machine, color reproducibility and light resistance are good, and color misregistration and A high-quality image can be stably formed without a decrease in transfer efficiency.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto.

[Molecular weight of binder resin]
The molecular weight of the binder resin was determined by GPC (gel permeation chromatography) measurement.

[Glass transition point of binder resin]
The glass transition point of the binder resin was determined by DSC (Differential Scanning Calorimetry) measurement.
The sodium sulfonate group equivalent was determined by determination of sulfur.

[Acid value of binder resin]
The acid value of the binder resin was determined by acid-base titration.

[Reduced viscosity of binder resin]
The reduced viscosity of the binder resin is obtained by dissolving 0.01 g of the binder resin in 250 cc of a mixed solvent of phenol / tetrachloroethane (weight ratio 6: 4), and measuring at 30 ° C. using an Ostwald viscometer. It was.

[Time constant τ (m / sec) of magenta toner]
The time constant τ of the magenta toner is defined as a product RC when the resistance of the magenta toner is R and the capacitance of the magenta toner is C. The resistance (R) of the magenta toner and the electrostatic capacity (C) of the magenta toner were measured using a dielectric loss measuring device (trade name: TRS-10T type, manufactured by Ando Electric Co., Ltd.).

Example 1
First, polyester resin A (binder resin) was produced as follows.

  To an autoclave equipped with a thermometer and a stirrer, 113 parts by weight of dimethyl terephthalate, 75 parts by weight of dimethyl isophthalate, 97 parts by weight of ethylene glycol, 50 parts by weight of propylene glycol and 0.1 part by weight of tetrabutoxy titanate as a catalyst were added. The reaction was allowed to stir for 120 minutes in a state heated to not lower than 230 ° C and not higher than 230 ° C. Then, it heated up to 250 degreeC, pressure-reduced the pressure of the reaction system to 1 mmHg or more and 10 mmHg or less, and it stirred for about 1 hour, and also it was made to react, and polyester resin A was obtained.

  The obtained polyester resin A had a number average molecular weight: 3200, a volume average molecular weight: 6200, a glass transition point: 63 ° C., an acid value: 2.2 mgKOH / g, and a reduced viscosity: 0.335.

  100 parts by weight of polyester resin A prepared as described above, C.I. I. Pigment red 48-3 and C.I. I. 6.8 parts by weight of Pigment Red 48-1 at a ratio of 7: 3, paraffin wax (release agent, trade name: HNP10PD, manufactured by Nippon Seiki Co., Ltd., acid value 0 mgKOH / g, melting point 75 ° C.) 5 weights A mixture was prepared by mixing 1 part by weight of an alkyl salicylic acid metal salt (charge control agent, trade name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.) for 10 minutes with a Henschel mixer. The obtained mixture was melt-kneaded with an open roll type continuous kneader (trade name: MOS320-1800, manufactured by Mitsui Mining Co., Ltd.) to prepare a melt-kneaded product.

  The melt-kneaded product was coarsely pulverized with a cutting mill (trade name: VM-16, manufactured by Ryo Kogyo Co., Ltd.) to prepare a coarsely pulverized product, and then the coarsely pulverized product was finely pulverized with a counter jet mill. After fine pulverization, the excessively pulverized toner was classified and removed by a rotary classifier, thereby producing magenta toner particles having a volume average particle diameter of about 6.7 μm.

  Magenta toner particles were spheronized using an impact spheronizing device (trade name: Faculty F-600, manufactured by Hosokawa Micron Corporation). 100 parts by weight of spherical magenta toner particles, 2.2 parts by weight of hydrophobic silica (trade name: R-974, manufactured by Nippon Aerosil Co., Ltd.) as an external additive and hydrophobic titanium (trade name: T-805, Japan) External additives are added to the magenta toner particles by mixing 3.8 parts by weight with 1.6 parts by weight (Aerosil Co., Ltd.) using a Henschel mixer (trade name: FM mixer, Mitsui Mining Co., Ltd.). A magenta toner of Example 1 was produced. The magenta colorant content in the magenta toner particles is 6.0% by weight, and the paraffin wax content is 4.2% by weight with respect to the total weight of the magenta toner.

  Here, in the magenta toner of Example 1, the content of the paraffin wax is 1.70 parts by weight (the content with respect to the total weight of the magenta toner is 1.49% by weight), and 2 parts by weight (the content with respect to the total weight of the magenta toner). 1.75% by weight) and 3.5 parts by weight (content with respect to the total weight of the magenta toner is 3.03% by weight). No aggregation of the magenta toner was observed, and a good image was obtained.

  However, when the content of paraffin wax is changed to 1 part by weight (the content with respect to the total weight of the magenta toner is 0.89% by weight), fixing offset occurs, and the content of paraffin wax is 5.5 parts by weight (magenta When the content with respect to the total weight of the toner is changed to 4.67% by weight), the fixing property is good, but the magenta toner aggregates in the developing device, and toner aggregates are observed in the image. From these facts, it can be said that the release agent content is good if it is 1.5 wt% or more and 4.8 wt% or less with respect to the total amount of magenta toner.

(Example 2)
A magenta toner of Example 2 was obtained in the same manner as in Example 1 except that the content of the magenta colorant was changed to 4.4 parts by weight. The magenta colorant content in the magenta toner particles is 4% by weight.

  Although not specifically described, as a result of repeating the experiment by further changing the content of the magenta colorant, it was found that the reproducibility was not influenced by the amount of the magenta colorant added to the binder resin. .

(Example 3)
C. I. Pigment red 48-3 and C.I. I. A magenta toner of Example 3 was obtained in the same manner as in Example 1 except that the weight ratio to Pigment Red 48-1 was changed to 8: 2.

Example 4
C. I. Pigment red 48-3 and C.I. I. A magenta toner of Example 4 was obtained in the same manner as in Example 1 except that the weight ratio with Pigment Red 48-1 was changed to 5: 5.

(Comparative Example 1)
C. I. The content of CI Pigment Red 48-3 was changed to 6.8 parts by weight. I. A magenta toner of Comparative Example 1 was obtained in the same manner as in Example 1 except that CI Pigment Red 48-1 was not used.

(Comparative Example 2)
C. I. Pigment red 48-3 and C.I. I. In place of Pigment Red 48-1, C.I. I. A magenta toner of Comparative Example 2 was obtained in the same manner as in Example 1 except that 7.3 parts by weight of Pigment Red 57-1 was added.

(Comparative Example 3)
C. I. A magenta toner of Comparative Example 3 was obtained in the same manner as Comparative Example 2 except that the content of Pigment Red 57-1 was changed to 5.4 weight.

  Using a magenta toner of Examples and Comparative Examples and a ferrite core carrier having a volume average particle size of 45 μm, a V-type mixer (trade name) is used so that the coverage of the magenta toner with respect to the carrier becomes 60%. : V-5, manufactured by Tokuju Kogyo Co., Ltd.) for 20 minutes. As a result, two-component developers each containing the magenta toners of Examples and Comparative Examples were produced.

(Evaluation)
The following evaluation was performed using a two-component developer containing magenta toners of Examples and Comparative Examples.

[Vermilion reproducibility]
The color gamut obtained when the magenta toner and the yellow toner of the example and the comparative example were respectively combined was obtained, and whether or not the color gamut contained vermilion vermilion was determined as follows. As yellow toner, C.I. I. Yellow toner using CI Pigment Yellow 74 and C.I. I. A yellow toner using CI Pigment Yellow 185 was used. The same result was obtained with either yellow toner.

Since vermilion is a color obtained by multiplying yellow and magenta, a color patch of the above two colors was output. Magenta in the main scanning direction and yellow image density changed in the sub scanning direction were multiplied. The output print sample was subjected to color measurement (L ^* , a ^* , b ^* ) using a reflection spectrodensitometer (X-Rite 939: manufactured by X-Rite Co., Ltd.). Each line of patches, L ^* a continuously paying attention to the change in L ^* and extracted data for each constant L ^* value since the change in each column. When there was no target L ^* value, it was obtained by interpolation calculation using the nearest two data. C ^* and Hab were calculated for each data obtained above. C ^* is a distance from the origin on the a ^* and b ^* planes (substitute as saturation). Hab is the angle theta ° from a ^*, the axis (+) direction on the a ^*, b ^* plane (substitute as hue). In this way, a color gamut obtained by mixing the prepared magenta toner and yellow toner was determined.

Further, L ^* a ^* b ^* of vermilion to be reproduced is measured using a reflection spectrodensitometer (X-Rite 939: manufactured by X-Rite Co., Ltd.), and whether or not this is included in the obtained color gamut, The reproducibility of vermilion was evaluated. Vermilion ink pad of L ^* a ^* b ^* is (55,62,33), the color gamut obtained magenta toners of Examples and Comparative Examples by combining yellow toner and each vermilion ink pad of L ^* a ^* It was confirmed whether b ^* (55, 62, 33) was included. If the color gamut included vermilion vermilion L ^* a ^* b ^* (55, 62, 33), it was marked with “◯”, and if not, it was marked with “X”.

[Transfer defects, transfer efficiency, color shift]
70 g of the magenta toner of Examples and Comparative Examples and 930 g of a magnetic carrier (volume average particle diameter 50 μm, silicone resin-coated carrier, manufactured by Powdertech Co., Ltd.) were respectively stirred and mixed in a V-type mixer for 30 minutes, and 1000 g of 2 A component developer was prepared. This two-component developer is filled in a developing tank of a commercially available digital color copying machine (trade name: MX-4500, manufactured by Sharp Corporation), and 30,000 sheets of a letter-size test character area ratio of 5% (Nekosa Letter) Paper) A live-action test was conducted. Note that the amount of magenta toner adhering to the photosensitive drum during the actual shooting test was set to 0.3 to 0.4 mg / cm ² . For each of 3000 actual images, transfer defects, transfer efficiency, and color misregistration were evaluated using the original image.

(Transfer defect)
If a transfer failure was not recognized through 30,000 actual shots, “◯” was given. If a transfer failure was found in the middle of 30,000 shots, “X” was given. An example of the transfer failure is shown in FIG. Note that the presence or absence of transfer failure was visually determined.

(Transfer efficiency)
If the transfer efficiency can be maintained at 95% or more through 30,000 actual shots, “◯” is given. If the transfer efficiency is less than 95%, “X” is given.
The transfer efficiency was determined as follows. The transfer residual toner on the photosensitive drum after solid image transfer is removed by taping with Mylar tape, and this Mylar tape is stuck on an unused white paper to measure the Macbeth density value, and the measured value is “C”. . A Mylar tape was attached to white paper on which a solid image was transferred and an unfixed toner image was carried, and the Macbeth density value was measured. The measured value was “E”. In addition, a Mylar tape was stuck on unused white paper, and the Macbeth density value was measured to obtain a measured value “D”. The transfer efficiency was determined using the following formula (5).
Transfer efficiency (%) = {(EC) / (ED)} × 100 (5)

(Color shift)
If no color shift was found through 30,000 shots, it was rated as “◯”, and if a color shift was found in the middle of 30,000 shots, it was marked as “X”. An example of color misregistration is shown in FIG. The presence or absence of color misregistration was determined visually.

〔Comprehensive evaluation〕
A comprehensive evaluation was performed using the above evaluation results.
When all the evaluation results were “◯”, the comprehensive evaluation result was “◯”, and when even one evaluation result was “×”, the comprehensive evaluation result was “×”.

  Table 1 shows the type, weight ratio and content of the magenta colorant used in the preparation of the magenta toners of the examples and comparative examples, the time constant of the magenta toner, the evaluation results of the above evaluation, and the overall evaluation results. “CI Pigment Red” is described as “PR”.

  As is apparent from Table 1, C.I. I. Pigment red 48-3 and C.I. I. In Examples 1-4, in which Pigment Red 48-1 was included at a weight ratio of 8: 2 to 5: 5, sufficient vermilion reproducibility could be obtained. Further, as in Examples 1 to 4, when the time constant τ of magenta toner is in the range of 1,100 (m / sec) to 1,300 (m / sec), the occurrence of color misregistration and the transfer efficiency are improved. A high-quality vermilion image without deterioration was obtained.

  In Comparative Examples 1 and 2 in which the time constant τ of magenta toner is less than 1,100 (m / sec), color misregistration occurred and transfer efficiency was lowered. In Comparative Example 3 in which the time constant τ of the magenta toner exceeds 1,300 (m / sec), transfer failure and transfer efficiency decrease. The occurrence of transfer failure and transfer efficiency decrease in Comparative Example 3 is considered to be because the electrostatic adhesion force of the magenta toner to the intermediate transfer belt is too large.

DESCRIPTION OF SYMBOLS 2 Image forming part 3 Transfer means 4 Fixing means 5 Recording medium supply means 6 Discharge means 11 Photosensitive drum 100 Image forming apparatus

Claims (5)

A binder resin,
C. I. Pigment red 48-3 and C.I. I. Pigment Red 48-1 and a colorant containing 8: 2 to 5: 5 by weight,
A magenta toner for developing electrostatic images, having a time constant of 1100 m / sec or more and 1300 m / sec or less.   2. The magenta toner for developing an electrostatic charge image according to claim 1, wherein the transmittance of light having a wavelength of 440 nm is 30% or more and 45% or less.   A developer comprising the electrostatic image developing magenta toner according to claim 1 and a carrier.   The surface of the charged image carrier is exposed to form an electrostatic image on the surface of the image carrier, and the electrostatic image formed on the surface of the image carrier is developed using the developer according to claim 3. And forming a toner image. An image carrier;
Charging means for charging the image carrier;
Exposure means for exposing the image carrier charged by the charging means to form an electrostatic image on the surface of the image carrier;
A developing means for developing the electrostatic image by supplying the electrostatic image developing magenta toner in the developer according to claim 3 to the image carrier on which the electrostatic image is formed. Image forming apparatus.