CN102243451B - Electrostatic charge image developing magenta toner, developer, image forming method, and image forming apparatus - Google Patents

Abstract

The invention provides a red toner for electrostatic charge image developing products, a developer, an image forming method and an image forming device. Color repeatability and light resistance are excellent, and color deviation and deterioration of transfer printing efficiency can be prevented. The red toner for electrostatic charge image developing products contains bonding resin and coloring agent which contains C.I. red pigment48-3 and C.I. red pigment48-3 in a ratio of 8:2-5:5. The time constant of the red toner for electrostatic charge image developing products is higher than 1100m/sec and lower than 1300m/sec.

Description

Electrostatic charge image developing magenta toner, developer, image forming method, and image forming apparatus

technical field

The present invention relates to a magenta toner for electrostatic charge image development, a developer, an image forming method and an image forming device.

Background technique

In an image forming apparatus utilizing electrophotography, an image is formed through, for example, a charging step, an exposure step, a development step, a transfer step, a fixing step, a cleaning step, and a neutralization step. In the charging step, the surface of the rotating photoreceptor is uniformly charged by the charging device. In the exposing step, the charged photoreceptor surface is irradiated with laser light by the exposure device to form an electrostatic latent image on the photoreceptor surface. Next, in the developing step, the electrostatic latent image on the surface of the photoreceptor is developed with a developer by a developing device to form a toner image on the surface of the photoreceptor, and in the transfer step, the toner on the surface of the photoreceptor is transferred to The image is transferred onto the transfer material. After that, in the fixing step, the toner image is fixed to the transfer material by heating by a fixing device. And, after the image forming operation, the residual transfer toner remaining on the surface of the photoreceptor is removed by the cleaning device in the cleaning step, and recovered to a predetermined recovery part, and the remaining toner on the surface of the photoreceptor after cleaning is Charges are eliminated by the static elimination device for the formation of the next image.

In the full-color image forming device, the charging step, exposing step, developing step, transferring step, fixing step, cleaning step and discharging step are carried out three times corresponding to the three colors of yellow, magenta and cyan. Or in addition to the three colors of yellow, magenta, and cyan, black is implemented four times. In the developing step, three-color toners of yellow, magenta, and cyan, or four-color toners in which black is added to three colors of yellow, magenta, and cyan are used.

As a toner used in this full-color image formation, in order to obtain an image faithful to the original, it is required to have good color reproducibility, for example, in JP-A-2008-287239 and JP-A-2009-47814 The gazettes, JP-A-2009-58745 and JP-A-2009-169407 disclose a magenta toner containing a rhodamine-based compound as a colorant.

Furthermore, JP-A-63-173066 discloses an electrophotographic magenta toner containing Pigment Red 48-1 as a colorant. According to the electrophotographic magenta toner disclosed in JP-A-63-173066, red images recorded on office stationery and the like can be reproduced with high chroma.

Further, the toner is required to suppress color deviation and lower transfer efficiency. For example, JP 2004-333629 discloses the following toner: a toner composed of at least polymer particles, colorant particles, and release agent particles. Aggregated particles of dry toner as toner particles contain at least a quinacridone colorant and a soluble azo colorant, and the total content of the quinacridone colorant and the soluble azo colorant is from 1 to 20% by mass, the mass ratio of the content is quinacridone-based colorant: soluble azo-based colorant = 10:90 to 50:50, and the basis of the number measured by the particle flow image analyzer (Flow Particle Image Analyzer) In the particle size frequency distribution of the toner, the number average diameter of the equivalent circle of the toner is 3 to 7 μm, and the number ratio of the toner having the equivalent circle diameter of 0.6 to 2 μm is 1 to 30 %.

Considering that the physical properties of the toner involved in the transfer depend on the Van der Waals force, as shown in the toner disclosed in JP Unexamined Publication No. 2004-333629, as in the circle equivalent number average diameter And the ratio of the number of toners in the range of 0.6 to 2 μm in circle-equivalent diameter is in the above-mentioned range, then the recyclability of the transfer residual toner existing on the photoreceptor is significantly improved, so the recovery of the transfer residual toner can be suppressed. Increase the reproducibility of the outline of the image, especially the development of character images and line graphics.

With the popularization of full-color image forming devices, the use of image forming devices to copy documents with seals or to form images corresponding to image data containing seal images has increased, and the requirements for color reproducibility of seal images Also increased. The color of the seal is the color of the vermilion ink pad used for the seal, which is bright vermilion with high brightness.

Vermilion is generally formed by mixing yellow toner into magenta toner, but the vermilion formed by mixing yellow toner into magenta toner is a mixed color, so the color is cloudy and the brightness is low, so it cannot be fully reproduced. The color of vermilion inkpad. As the colorant for the magenta toner, C.I. Pigment Red 269, C.I. Pigment Red 57-1, C.I. Pigment Red 122, and the like are used. In addition, the ratio of the yellow toner mixed into the magenta toner and the like depend on the image processing technique.

The magenta toner disclosed in JP-A-63-173066 cannot sufficiently reproduce the color of vermilion ink pad.

In contrast, the magenta toners disclosed in JP-A-2008-287239, JP-A-2009-47814, JP-A-2009-58745, and JP-A-2009-169407 can sufficiently reproduce vermilion ink pads s color. This is because the rhodamine-based compound is a fluorescent pigment. It is known that rhodamine-based compounds absorb light around 520 nm and emit fluorescence having a fluorescence peak wavelength in a wavelength range of 560 to 600 nm. When fluorescent pigments are used as colorants, brightness and chroma can be easily increased to form bright vermilion with strong brightness.

However, since fluorescent pigments are poor in light resistance, there is a problem that stamped images included in copies and image-formed products fade in a relatively short period of time.

Furthermore, in the toner disclosed in JP-A-2004-333629, occurrence of color shift and reduction in transfer efficiency cannot be sufficiently suppressed.

Contents of the invention

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 that have good color reproducibility and light fastness, and can suppress occurrence of color shift and decrease in transfer efficiency. .

The present invention is a magenta toner for electrostatic charge image development, which is characterized in that it contains: a binder resin; and a colorant containing C.I. Pigment Red 48-3 and C.I. Pigment in a weight ratio of 8:2 to 5:5. In Red 48-1, the time constant of the magenta toner for electrostatic charge image development was not less than 1100 msec and not more than 1300 msec.

According to the present invention, the electrostatic image developing magenta toner contains a binder resin and a colorant. The colorant contains C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 in a weight ratio of 8:2 to 5:5, and the magenta toner for electrostatic image development has a time constant of 1100 msec or more and 1300 msec or less.

Since the coloring agent contains C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 in a weight ratio of 8:2 to 5:5, it is possible to obtain a color that can ensure good light fastness without using fluorescent pigments, and is compatible with vermilion. An electrostatic charge image developing magenta toner with good reproducibility.

By setting the time constant of the electrostatic charge image developing magenta toner to 1100 msec to 1300 msec, the electrostatic adhesion of the electrostatic charge image developing magenta toner to the intermediate transfer belt and the recording medium before fixing becomes within an appropriate range , the occurrence of color deviation and the reduction of transfer efficiency are suppressed, and high-quality images can be formed.

In addition, in the present invention, it is preferable that the light transmittance of light having a wavelength of 440 nm is not less than 30% and not more than 45%.

According to the present invention, the transmittance of light having a wavelength of 440 nm is not less than 30% and not more than 45%. In this way, vermilion can be reproduced stably and sufficiently.

And the present invention is a developer comprising the above electrostatic charge image developing magenta toner and a carrier.

According to the present invention, the developer contains the electrostatic charge image developing magenta toner of the present invention and a carrier. The electrostatic image developing magenta toner of the present invention has good color reproducibility and light fastness, and can suppress occurrence of color shift and reduction in transfer efficiency, so the electrostatic image developing magenta toner of the present invention is contained With the carrier developer, a high-quality image that fully reproduces vermilion can be formed.

Furthermore, the present invention is an image forming method, characterized in that, exposing the charged image carrier surface to form an electrostatic charge image on the image carrier surface, and developing the electrostatic charge image formed on the image carrier surface using the above-mentioned developer. Toner image.

According to the present invention, in the image forming method, the charged image carrier surface is exposed to light to form an electrostatic charge image on the image carrier surface, and the electrostatic charge image formed on the image carrier surface is developed using the developer of the present invention to form a toner image. , so it is possible to form a high-quality image that fully reproduces vermilion.

Furthermore, the present invention is an image forming apparatus, characterized in that it includes: an image carrier; a charging device for charging the image carrier; an exposure unit for exposing the image carrier charged by the charging device to form electrostatic charges on the surface of the image carrier. an image; and a developing device that supplies an electrostatic charge image developing magenta toner among the developer to the image carrier on which the electrostatic charge image is formed, and develops the electrostatic charge image.

According to the present invention, the image forming apparatus has: an image carrier; charging means for charging the image carrier; an exposure unit for exposing the image carrier charged by the charging means to form an electrostatic charge image on the surface of the image carrier; The image carrier of the charged image provides the electrostatic charge image developing magenta toner among the developers of the present invention, and develops the electrostatic charge image, so that a high-quality image that sufficiently reproduces vermilion can be formed.

The purpose, characteristics and advantages of the present invention can be clarified by the following detailed description and accompanying drawings.

Description of drawings

FIG. 1 is a diagram showing an image formed using a magenta toner according to this embodiment.

FIG. 2 is a diagram showing a state in which color deviation and transfer failure occur.

3 is a schematic diagram schematically showing the configuration of an image forming apparatus according to an embodiment of the present invention.

4 is a schematic diagram schematically showing a developing device included in the image forming apparatus shown in FIG. 3 .

Detailed ways

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

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

(adhesive resin)

The binder resin is not particularly limited, but binder resins for color toners include, for example, polyester-based resins, styrene-based resins such as polystyrene and styrene-acrylate copolymer resins, polymethyl methacrylate Propylene-based resins such as polyethylene, polyolefin-based resins such as polyethylene, polyurethane, epoxy resin, etc.

As the binder resin, a resin obtained by mixing a release agent with a raw monomer mixture and polymerizing it can also be used. In this case, the binder resin preferably contains a polyester resin. By including the polyester resin in the binder resin, the controllability of the dispersion state of the release agent is improved, and a magenta toner having better fixability can be obtained. Further, good durability and transparency can be imparted to the magenta toner. One type of binder resin may be used alone, or two or more types may be used in combination.

It does not specifically limit as a polyester resin, A well-known thing can be used. Examples include polycondensates of polybasic acids and polyhydric alcohols. "Polyacids" are polybasic acids and derivatives thereof, for example, acid anhydrides or esterified products of polybasic acids. In addition, "polyol" is a compound containing two or more hydroxyl groups, and includes any of alcohols and phenols.

Polybasic acids commonly used as monomers of polyester resins can be used. For example: aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic anhydride, trimellitic anhydride, pyromellitic acid and naphthalene dicarboxylic acid, maleic anhydride, fumaric acid, succinic acid, adipic acid, etc. Aliphatic carboxylic acids, etc. The polybasic acid may be used alone or in combination of two or more.

Polyols commonly used as monomers of polyester resins can also be used. Examples include: aliphatic polyols such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, and glycerol, and alicyclic polyols such as cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A. Polyols, aromatic diols such as ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A, etc.

"Bisphenol A" is 2,2-bis(p-hydroxyphenyl)propane. Examples of the ethylene oxide adduct of bisphenol A include polyethylene oxide-2,2-bis-4-hydroxyphenylpropane. Examples of the propylene oxide adduct of bisphenol A include polyoxypropylene-2,2-bis-4-hydroxyphenylpropane. The polyols may be used alone or in combination of two or more.

Polyester resins can be synthesized by polycondensation reactions. For example, in an organic solvent or without a solvent, polycondensation reaction of polybasic acids and polyhydric alcohols is carried out in the presence of a catalyst, specifically, it synthesize|combines by dehydration polycondensation reaction. At this time, part of the polybasic acids can be subjected to demethanol polycondensation reaction using methylated products of polybasic acids. The polycondensation reaction of polybasic acids and polyhydric alcohols may be completed when the acid value or softening temperature of the resulting polyester resin reaches the value of the polyester resin to be synthesized.

In this polycondensation reaction, by appropriately changing the reaction conditions such as the mixing ratio and reaction rate of polybasic acids and polyhydric alcohols, for example, the content of carboxyl groups bonded to the terminal of the obtained polyester resin, the acid value of the obtained polyester resin, the Other physical properties such as softening temperature.

The acid value of the binder resin is preferably not less than 5 mgKOH/g and not more than 30 mgKOH/g. When the acid value of the binder resin is less than 5 mgKOH/g, the affinity between the binder resin and the release agent becomes greater than when the acid value of the binder resin is 5 mgKOH/g or more, so the release agent It is difficult to elute to the surface of the magenta toner, and a high-temperature deviation such as poor fixing is likely to occur. When the acid value of the binder resin exceeds 30 mgKOH/g, compared with when the acid value of the binder resin is less than 30 mgKOH/g, there are more functional groups remaining on the surface of the magenta toner, and it is easy to absorb moisture, so it is easy to absorb water under high humidity. Under these conditions, the charge amount of the magenta toner decreases, possibly deteriorating charge stability. Furthermore, the dispersibility of the release agent in the binder resin tends to decrease, so when the kneading is insufficient when producing the magenta toner, the dispersion diameter of the release agent on the surface of the magenta toner may become large .

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 can be made within a desired range. Specifically, the dispersion diameter of the release agent on the surface of the magenta toner can be stabilized to less than 300 nm, the decrease in the charge amount of the magenta toner under high-humidity conditions can be suppressed, and the adhesion can be well controlled for fixability Affinity of resin and release agent.

Therefore, charging stability can be further improved, and better fixability can be obtained, so that high-definition, high-resolution, high-quality images can be formed more stably over a long period of time. The acid value of the binder resin can be determined by appropriately changing the raw material monomer mixture of the binder resin during the synthesis of the binder resin. The reaction conditions are used to adjust the content of carboxyl groups bonded to the end of the obtained binder resin and the acid value of the obtained binder resin.

(magenta colorant)

The magenta colorant contains specific two magenta pigments in specific ratios.

Specific two magenta pigments are C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 classified by the Color Index. The magenta colorant mainly contains C.I. Pigment Red 48-3, and C.I. Pigment Red 48-1 supplementarily contains these two kinds of magenta pigments.

C.I. Pigment Red 48-3 has the characteristics that it has a strong sense of red as a transmission characteristic, and has a high purple transmittance. C.I. Pigment Red 48-1 has the following characteristics: low purple transmittance and poor tinting strength.

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

By using a magenta colorant containing C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 in a weight ratio of 8:2 to 5:5, and mixing a yellow toner with the magenta toner of this embodiment, the The vermilion visible image formed on the recording medium is represented by the L*a*b* system color system (Meng Searle color system) can be included in the color gamut of (L*, a*, b*)=(55, 62, 33) as the color gamut of vermilion ink pad. Or when it is expressed by the color system (Munsell color system) that the brightness is L* and the chroma is C*, it can be included in (L*, C*)=(55, 70) within the color gamut. Therefore, it is possible to form a magenta toner capable of sufficiently reproducing the color of vermilion ink pad which is bright in lightness L*.

The L*a*b* system color system is a useful means of numerically expressing colors. L* in the z-axis direction represents lightness, and a* and b* in the x-axis and y-axis represent hue and chroma. "Brightness" refers to the relative brightness of a color, "hue" refers to the hue of red, yellow, green, blue, purple, etc., and "saturation" refers to the vividness of a color.

In addition, since yellow toner has high brightness regardless of the yellow colorant used, the color gamut of a vermilion visible image depends on the characteristics of magenta toner. As the yellow colorant contained in the yellow toner, for example, C.I. Pigment Yellow 74 or C.I. Pigment Yellow 185 can be used.

When the weight ratio of C.I. Pigment Red 48-1 is less than 20%, the characteristics of C.I. Pigment Red 48-3 are stronger, so the high brightness L* of the color of the vermilion ink pad cannot be displayed, and the color of the vermilion ink pad cannot be fully reproduced. The higher the ratio of C.I. Pigment Red 48-1 to C.I. Pigment Red 48-3, the higher the brightness L* of the visible image formed on the recording medium. However, when the weight ratio of C.I. Pigment Red 48-1 exceeds 50%, Due to the characteristics of C.I. Pigment Red 48-1, which has weak tinting power, it cannot show the color saturation C* of vermilion ink pad, and cannot fully reproduce the color of vermilion ink pad.

In addition, the color of vermilion ink pad can be easily achieved by containing fluorescent pigments in magenta toner, but magenta toners containing fluorescent pigments have poor light fastness and thus have a problem of fading. In order to solve this fading problem, when a substance for improving light resistance is added to a magenta toner containing a fluorescent pigment, new problems arise in the color rendering property of the magenta toner. Moreover, the development of fluorescent pigments with strong light fastness requires relatively large costs.

A magenta colorant is preferably used as a masterbatch. The masterbatch can be produced by kneading, for example, a melt of a synthetic resin and a 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 usage ratio of the synthetic resin and the magenta colorant is not particularly limited, but is preferably not less than 30 parts by weight and not more than 100 parts by weight relative to 100 parts by weight of the synthetic resin. For example, the master rubber is made into a particle size of about 2-3 mm for use.

The content of the magenta colorant in the magenta toner is not particularly limited, but is preferably not less than 4 parts by weight and not more than 15 parts by weight relative to 100 parts by weight of the binder resin. When using a master batch, it is preferable to adjust the usage-amount of a master batch so that content of the magenta coloring agent in this embodiment falls within the said range. When the content of the magenta colorant is within the above range, an image having sufficient image density, strong color rendering, and good image quality can be formed.

(release agent)

It does not specifically limit as a release agent, A well-known thing can be used. Examples include: paraffin wax and its derivatives, microcrystalline wax and its derivatives and other petroleum waxes, Fischer-Tropsch wax and its derivatives, polyolefin wax and its derivatives, low molecular weight polypropylene wax and its derivatives, polyolefin Hydrocarbon synthetic waxes such as polymeric waxes and their derivatives, carnauba wax and its derivatives, ester waxes, etc.

The content of the release agent in the magenta toner may be 1.5% by weight or more and 5% by weight or less based on the total weight of the magenta toner. When 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 decreases, and fixing offset may occur. When the content of the release agent exceeds 5% by weight, although the fixability is good, 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 adhesive resin becomes stronger than when the acid value of the release agent is less than 4 mgKOH/g, so the release agent is not easy to fix. The magenta toner is eluted, and high-temperature offset tends to occur.

(charge control agent)

The magenta toner preferably contains toner additive components such as a charge control agent in addition to a binder resin, a magenta colorant, and a release agent. By containing the charge control agent, good chargeability can be imparted to the magenta toner. As the charge control agent, a charge control agent for positive charge control or negative charge control is used.

The charge control agent used for positive charge control includes, for example: nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrines, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and derivatives thereof , triphenylmethane derivatives, guanidine salts, amidine salts, etc. As the charge control agent for negative charge control, oil-soluble dyes such as petroleum carbon black and iron black (Spilon Black), metal-containing azo compounds, azo complex dyes, naphthenic acid metal salts, salicylic acid, and the like are included, for example. Metal complexes and metal salts of derivatives (metals are chromium, zinc, zirconium, etc.), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, resin acid soaps, etc. The charge control agent may be used alone or in combination of two or more.

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

The time constant τ of the magenta toner of the present embodiment is not less than 1100 msec and not more than 1300 msec. The magenta toner time constant τ is defined as the product RC when R is the resistance of the magenta toner and C is the capacitance of the magenta toner.

The reason for such definition is as follows.

First, since magenta toner is a dielectric, it has both a resistance component and an electrostatic capacity (capacitance) component. Here, when the resistance of the magenta toner is R (Ω) and the electrostatic capacitance of the magenta toner is C (F), the state of applying a voltage to the magenta toner can be regarded as a state where R (Ω) is connected in series. Ω) resistance and C (F) capacitance circuit. A DC voltage E(V) is applied to the series circuit. The moment when the DC voltage E is applied to the facility is time 0, the current flowing into the circuit at time t is i(t)(A), and the 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, the current is the electron flow, ie, the magnitude of the time change of the amount of charge, so it is expressed as i(t)=dq(t)/dt, and the above formula (1) can be rewritten as the following formula (2).

E＝[(R·dq(t)/dt)+q]/C …(2)

Solving the above formula (2), then q(t) is shown in the following formula (3) with respect to t.

q(t)＝CE(1-exp(-t/RC)) …(3)

Furthermore, assuming that the voltage across the capacitor is ec, then q(t)=C·ec(t), so the following formula (4) can be obtained.

ec(t)＝E(1-exp(-t/τ)) …(4)

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

According to the above formula (4), the larger τ is, the longer it takes for ec(t) to reach its maximum value E. Since the time constant τ is proportional to the resistance value R and the electrostatic capacity (charge) C of the magenta toner, the greater the resistance of the magenta toner or the charge induced by the capacity component of the magenta toner, The discharge of the magenta toner takes more time. That is, the reduction in triboelectric charging of the magenta toner is slowed down.

By setting the time constant τ of the magenta toner to 1100 msec or more and 1300 msec or less, the charge amount of the magenta toner charged in the developing step is appropriately reduced before the transfer step, and even in high-speed equipment, the magenta toner The electrostatic adhesion of the toner to the intermediate transfer belt and the recording medium before fixing is also within an appropriate range, so occurrence of color shift and reduction in transfer efficiency can be suppressed, and a high-quality image as shown in FIG. 1 can be formed. FIG. 1 is a diagram showing an image 200 formed using a magenta toner according to this embodiment. In addition, FIG. 2 is a diagram showing an image 201 in a state where color deviation and poor transfer have occurred. In FIG. 2 , the range surrounded by reference mark a indicates the occurrence point of color shift, and the range surrounded by reference mark b represents the occurrence point of transfer failure. 1 and 2 are images 200, 201 formed of vermilion.

When the time constant τ of the magenta toner is less than 1100 msec, even if the magenta toner is sufficiently charged in the developing step, the charge amount of the magenta toner decreases excessively until the transfer step is performed, so the time constant in the transfer step The charge amount of the magenta toner is insufficient, as shown in FIG. 2 , causing color deviation and a decrease in transfer efficiency. When the time constant τ of the magenta toner exceeds 1300 msec, the decrease in charge amount of the magenta toner from the developing step to the transfer step is too small, so the charge amount of the magenta toner in the transfer step becomes too large, As shown in FIG. 2 , poor transfer occurs and transfer efficiency decreases.

The time constant τ of the magenta toner can be adjusted by appropriately selecting the types of components contained in the magenta toner, their contents, and the like. Each component contained in the toner includes, for example, a binder resin, a magenta colorant, a release agent, a charge control agent, organic and inorganic additives, and the like.

The magenta toner preferably has a transmittance of light having a wavelength of 440 nm of not less than 30% and not more than 45%. By setting the light transmittance of light with a wavelength of 440 nm in the magenta toner to 30% or more and 45% or less, it is possible to stably and sufficiently reproduce the color of vermilion ink pad which is bright vermilion with a high brightness L*.

When the light transmittance of light with a wavelength of 440 nm in the magenta toner exceeds 45%, even if the mixing ratio of the yellow toner is adjusted in image processing, the bright vermilion with a high brightness L* cannot be fully reproduced. The color of vermilion inkpad.

As described above, by containing C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 in a weight ratio of 8:2 to 5:5, the light transmittance of light having a wavelength of 440 nm can be increased in the magenta toner. More than 30% and less than 45%.

The volume average particle diameter of the magenta toner is preferably 5.0 μm or more and 7.0 μm or less. Furthermore, it is preferable that the content of the magenta toner having a particle diameter of 5.0 μm or less in the number particle size distribution is less than 40% by number of all the magenta toner particles. By making 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, high-quality image can be formed. When the volume average particle diameter of the magenta toner is less than 5.0 μm, toner scattering occurs due to low fluidity. When the volume average particle diameter of the magenta toner exceeds 7.0 μm, it is not possible to form sufficiently high-definition and high-resolution images. When the content of magenta toner particles with a particle size of 5.0 μm or less in the number particle size distribution is 40% by number or more of all the magenta toner particles, toner scattering due to decreased fluidity occurs, and Fogging caused by deterioration of transfer efficiency.

The volume average particle diameter (D _50V ) of the above-mentioned magenta toner and the content rate (number %) of magenta toner particles with a particle diameter of 5.0 μm or less in the number particle size distribution were obtained by Beckman Coulter Co., Ltd. The particle size distribution measuring device "Multisizer 3" manufactured by the company is used for measurement. The measurement conditions are as follows.

Pore diameter: 100μm

The number of measured particles: 50,000

Analysis software: Colter Malchisa Izakyucomp version 1.19 (manufactured by Beckman Colter Co., Ltd.)

Electrolyte: ISOTON-II (manufactured by Beckman Co., Ltd.)

Dispersion liquid: sodium alkyl ether sulfate

Measurement procedure: Add 50ml of electrolyte solution, 20mg of toner as a sample, and 1ml of dispersant to a beaker, disperse in an ultrasonic disperser for 3 minutes, prepare a sample for measurement, and measure the particle size with the measuring device "Multisizer3". Determination. The volume particle size distribution and the number particle size distribution of the sample particles were obtained from the obtained measurement results, and the volume average particle diameter (D _50V ) of the magenta toner was obtained from the volume particle size distribution. Then, from the number particle size distribution, the content rate (number %) of magenta toner particles having a particle diameter of 5.0 μm or less was obtained.

(additive)

Magenta toner particles can also be used as magenta toner as they are. For example, magenta toner particles and additives can be mixed to use magenta toner particles with additives as magenta toner. . The addition of additives can improve powder fluidity and triboelectricity, generate heat resistance, improve long-term storage and cleanability, and suppress wear on the surface of the photoreceptor.

Examples of additives include silica fine powder, titanium oxide fine powder, alumina fine powder, and the like. One kind of additives may be used alone, or two or more kinds may be used together.

The content of the additives is based on 100 parts by weight of magenta toner particles in consideration of the charge amount required for the magenta toner, the effect on the wear of the photoreceptor due to the addition of the additive, the environmental characteristics of the magenta toner, etc. Preferably it is 0.1 weight part or more and 10 weight parts or less, More preferably, it is 2.0 weight part or more and 4.0 weight parts or less. When the additive is at least 2.0 parts by weight and at most 4.0 parts by weight, the fluidity can be improved and the charge of each magenta toner particle can be appropriately controlled, so that high-quality images without deteriorating fixability and fogging can be formed.

When the content of the additive is less than 2.0 parts by weight, sufficient fluidity cannot be imparted to the magenta toner (especially magenta toner particles with a small particle diameter), so that each magenta toner particle is not sufficiently charged and easily Fog in the non-image portion occurs. When the content of the additives is more than 4.0 parts by weight, the additives are likely to coagulate, the surface of the magenta toner cannot be effectively covered, and the fluidity cannot be improved. Therefore, each magenta toner particle is not sufficiently charged, and it is easy to occur in the non-image area. of gray fog.

(Manufacturing method of magenta toner)

The magenta toner particles constituting the magenta toner of the present embodiment are produced by a pulverization method, a suspension polymerization method, an emulsion polymerization method, a dissolution suspension method, an ester stretching copolymerization method, or the like.

An example of a magenta toner production method for producing magenta toner particles by a pulverization method will be described below.

A resin composition containing at least a binder resin, a magenta colorant, and a mold release agent was dry-mixed (pre-mixed) by a mixing device, and melt-kneaded by a kneader. Thereafter, the melted and kneaded product was pulverized and classified using a pulverizer and a classifier to produce magenta toner particles. Next, magenta toner particles and additives are dry mixed to obtain a desired magenta toner.

As the mixing equipment used in dry mixing, well-known ones can be used, including, for example: Henschel mixer (trade name: FM Mikisa, manufactured by Mitsui Mining Co., Ltd.), high-speed mixer (Super Mikisa) (trade name Co., Ltd. カヮタ manufacture), mechanical mill (Mekanomil, trade name, manufactured by Okada Seiko Co., Ltd.) and other Henschel-type mixing devices, Ongmill (ONGU Mill, trade name, manufactured by Hoso KahヮMicron Co., Ltd.), Hibridashi-Sion System ( Hybridization System, trade name, manufactured by Nara Machinery Manufacturing Co., Ltd.), Cosmo System (Cosmo System, trade name, manufactured by Kawasaki Heavy Industries, Ltd.), etc.

Known devices can be used as the kneading machine. For example, common kneading machines such as a biaxial extruder, a three-roll rolling mill, and a laboplast mill (laboplast mill), specifically include: TEM-100B (trade name, Toshiba Machine Co., Ltd.), PCM-65/87, PCM-30 (the above are all trade names, manufactured by Ikegai Co., Ltd.) and other single-screw or twin-screw extruders; Co., Ltd.), such as an open roll type kneading machine, etc. Among them, a kneader of an open roll type is preferable. The toner raw material mixture may also be melt-kneaded using a plurality of kneaders.

The pulverization of the molten kneaded product can use, for example, the following pulverizers: a jet pulverizer that utilizes a supersonic air jet to pulverize; a coarse material is introduced into a space formed between a rotor as a high-speed rotating rotor and a liner as a stationary member; Impact mills that pulverize and pulverize objects, etc.

For the classification, a known classifier that can remove over-crushed toner particles and coarse toner particles can be used for classification by centrifugal force or wind force. For example, use a rotary wind classifier or the like.

Magenta toner particles may also be spheroidized. As the impact-type spheroidization device used in the spheroidization process under mechanical impact force, a commercially available one can be used, for example, Facalty (trade name, manufactured by Hosokahe Micron Co., Ltd.) and the like can be used. A commercially available one can be used as the hot air type spheroidizing device used for the spheroidizing treatment under hot air. For example, a surface modifier Meteorine Bo (trade name, manufactured by Nippon New Math Industries Co., Ltd.) or the like can be used.

The spheroidization treatment is preferably performed so that the circularity of the magenta toner is not less than 0.950 and not more than 0.960.

The magenta toner may also have a core-shell structure in which the magenta toner particle obtained above is used as a core particle and the outer peripheral surface of the core particle is covered with a shell layer not containing a magenta colorant.

(developer)

The magenta toner of the present embodiment produced as described above may be used as a one-component developer as it is, or may be mixed with a carrier to be used as a two-component developer. By containing the magenta toner of the present embodiment, it is possible to reproduce the color of vermilion ink pad which is bright vermilion with high brightness, and to form a developer having good light fastness.

Furthermore, the magenta toner according to the present embodiment has good fixability and good charging stability, and is a developer whose properties are stable during long-term use, and therefore is a developer that can maintain good developability.

The developer is preferably a two-component developer composed of the magenta toner of the present invention and a carrier. Since the magenta toner of the present invention has good storage stability, a decrease in the fluidity of the developer can be suppressed, and a two-component developer having good charge stability and developability can be obtained. By using this two-component developer, high-resolution, high-quality images without toner scattering can be stably formed over a long period of time.

Magnetic particles are used as carriers. Examples of magnetic particles include metals such as iron, ferrite, and magnetite, alloys of these metals and metals such as aluminum and lead, and the like. Among them, ferrite is preferable.

A resin-coated carrier in which magnetic particles are coated with a resin, a resin-dispersed carrier in which magnetic particles are dispersed in a resin, or the like can also be used as the carrier. The resin used as the resin-coated carrier is not particularly limited, and includes, for example, olefin-based resins, styrene-based resins, styrene-acrylic resins, silicon-based resins, ester-based resins, and fluoropolymer-based resins. Furthermore, the resin used for the resin-dispersed carrier is not particularly limited, and includes, for example, styrene acrylic resins, polyester resins, fluorine-based resins, and phenolic resins.

The shape of the carrier is preferably spherical or flat. The volume average particle diameter of the carrier is not particularly limited, but it is preferably 10 μm or more and 100 μm or less, more preferably 30 μm or more and 50 μm or less in consideration of high image quality. When the volume average particle diameter of the carrier is less than 10 μm, the magnetic force between the carrier and the developing roller becomes weaker than when the volume average particle diameter of the carrier is 10 μm or more, so the carrier is easily developed together with the toner in the developing step . When the volume average particle diameter of the carrier exceeds 100 μm, each magenta toner particle may not be sufficiently charged.

By setting the volume average particle diameter of the carrier to 10 μm or more and 100 μm or less, the chance of contact between the magenta toner and the carrier increases, so that charging of each magenta toner particle can be controlled and sufficient chargeability of the toner can be imparted.

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

(image forming device)

FIG. 3 is a schematic diagram schematically showing the configuration of an image forming apparatus 100 according to an embodiment of the present invention. The image forming apparatus 100 is a multifunctional peripheral having a copying function, a printing function, and a facsimile function, and forms a full-color or monochrome image on a recording medium based on transmitted image information. That is, image forming apparatus 100 has three printing modes of copy mode, print mode, and facsimile mode. The print mode is selected by a control unit (not shown) such as receiving a print job from an external device that has a storage device.

The image forming apparatus 100 includes a photosensitive drum 11 as 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 designed to correspond to the color images of black (b), cyan (c), magenta (m), and yellow (y) contained in color image information. information, and set four each. Among them, four parts are respectively provided corresponding to each color, and letters representing each color are attached at the end of the reference numerals to distinguish them, and they are only indicated by reference numerals when they are collectively referred to.

The image forming unit 2 includes a charging device 12 , an exposure unit 13 , a developing device 14 , and a cleaning unit 15 . The charging device 12 and the exposure unit 13 function as a latent image forming unit. The charging device 12 , the developing device 14 , and the cleaning unit 15 are arranged smoothly around the photosensitive drum 11 as described above. The charging device 12 is arranged vertically below the developing device 14 and the cleaning unit 15 .

The photosensitive drum 11 is a roll-shaped member that is rotatably driven about an axis by a rotary drive unit (not shown) and forms an electrostatic latent image on its surface. The rotational driving unit of the photosensitive drum 11 is controlled by a control unit realized by a central processing unit (Central Processing Unit: CPU). The photosensitive drum 11 includes: an unillustrated conductive substrate; and an unillustrated photosensitive layer formed on the surface of the conductive substrate.

The charging device 12 faces the photosensitive drum 11 and is disposed away from the surface of the photosensitive drum 11 with a gap along the length direction of the photosensitive drum 11 to charge the surface of the photosensitive drum 11 to a predetermined polarity and potential. As the charging device 12, a charging brush type charger, a charging type charger, a sawtooth type charger, an ion generator, or the like can be used. In this embodiment, the charging device 12 is arranged apart from the photosensitive drum 11, but the present invention is not limited thereto. For example, a charging roller may be used as the charging device 12, and the charging roller and the photosensitive drum may be placed in contact with each other, or a contact charging device such as a charging brush or a magnetic brush may be used.

The exposure unit 13 is configured such that light rays of information of each color emitted from the exposure unit 13 pass between the charging device 12 and the developing device 14 to irradiate the surface of the photosensitive drum 11 . The exposure unit 13 converts the image information into light corresponding to the information of each color of black, cyan, magenta, and yellow, and exposes the surface of the photosensitive drum 11 charged to the same potential by the charging device 12 with the light corresponding to the information of each color. , forming an electrostatic latent image on its surface. As the exposure unit 13 , for example, a laser scanning unit having a laser irradiation unit and a plurality of mirrors can be used. An LED array, or a unit in which a liquid crystal barrier and a light source are appropriately combined can also be used.

The cleaning unit 15 removes the toner remaining on the surface of the photosensitive drum 11 to clean the surface of the photosensitive drum 11 after the toner image formed on the surface of the photosensitive drum 11 is transferred to the recording medium by the developing device 14 . The cleaning unit 15 uses, for example, a plate-shaped member such as a cleaning blade. In the image forming apparatus of this embodiment, an organic photosensitive drum is used as the photosensitive drum 11. The surface of the organic photosensitive drum is mainly composed of resin components, so the chemical action of ozone generated by the corona discharge of the charging device is easy to promote the organic photosensitive drum. The surface of the drum is degraded. However, the degraded surface portion is abraded by the friction of the cleaning unit 15, and is gradually and surely removed. Therefore, the problem of surface deterioration caused by ozone or the like is practically eliminated, and the charging potential generated by the charging operation can be stably maintained for a long period of time. In this embodiment, the cleaning unit 15 is provided, but it is not limited thereto, and the cleaning unit 15 may not be provided.

By the image forming part 2, on the surface of the photosensitive drum 11 which is in a uniformly charged state by the charging device 12, the signal light corresponding to the image information is irradiated from the exposure unit 13 to form an electrostatic latent image, and supplied to it from the developing device 14. The toner forms a toner image, and 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 . To form an image, this series of toner image forming operations is repeated.

The transfer unit 3 is disposed above the photosensitive drum 11 and includes: an intermediate transfer belt 25, a driving roller 26, a driven roller 27, four intermediate transfer rollers 28 corresponding to the respective colors of black, cyan, magenta and yellow, Transfer belt cleaning unit 29 , transfer roller 30 . The intermediate transfer belt 25 is an endless belt-shaped member spanning the driving roller 26 and the driven roller 27 to form an endless moving path, and is rotationally driven in the direction of the arrow B. As shown in FIG. The drive roller 26 is provided so as to be rotatable about its axis by a drive unit (not shown), and the intermediate transfer belt 25 is rotatably driven in the arrow B direction by this rotatable drive. The driven roller 27 is rotatably driven by the driving roller 26 and applies a certain tension to the intermediate transfer belt 25 so that the intermediate transfer belt 25 does not slack. The intermediate transfer roller 28 is in pressure contact with the photosensitive drum 11 via the intermediate transfer belt 25 , and is rotatably driven about its axis by a driving unit (not shown). The intermediate transfer roller 28 is connected to a power source (not shown) that applies 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 photosensitive drum 11 while being in contact with the photosensitive drum 11 , the toner on the surface of the photosensitive drum 11 is applied from the intermediate transfer roller 28 disposed opposite to the photosensitive drum 11 via the intermediate transfer belt 25 . With the transfer bias of opposite polarity, 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, the toner images of the respective colors formed by the respective photosensitive drums 11 are sequentially overlapped and transferred to the intermediate transfer belt 25 to form a full-color toner image.

The transfer belt cleaning unit 29 faces the driven roller 27 via the intermediate transfer belt 25 and is provided in contact with the outer peripheral surface of the intermediate transfer belt 25 . Toner attached to the intermediate transfer belt 25 through contact with the photosensitive drum 11 contaminates the recording medium, so the transfer belt cleaning unit 29 removes and recovers the toner on the surface of the intermediate transfer belt 25 .

The transfer roller 30 is in pressure contact with the driving roller 26 via the intermediate transfer belt 25 , and is rotatably driven about its axis by a driving unit (not shown). In the transfer nip portion where the transfer roller 30 and the drive roller 26 are pressed, the toner image carried and conveyed by the intermediate transfer belt 25 is transferred to the toner image conveyed from the recording medium supply unit 5 described below. on the medium. The recording medium carrying the toner image is conveyed to the fixing section 4 .

The toner image transferred from the photosensitive drum 11 to the intermediate transfer belt 25 in the pressure contact portion between the photosensitive drum 11 and the intermediate transfer roller 28 is transferred to the arrow B through the intermediate transfer belt 25 through the transfer section 3 . The rotational drive in the direction is transmitted to the transfer nip, where it is transferred to the recording medium.

The fixing unit 4 is provided on the downstream side in the transport direction of the recording medium compared to the transfer unit 3 , and includes a fixing roller 31 and a pressure roller 32 . The fixing roller 31 is provided rotatably driven by a driving unit not shown, heats and melts the toner constituting the unfixed toner image carried on the recording medium, and fixes it to the recording medium. An unillustrated heating unit is provided inside the fixing roller 31 . The heating unit heats the fixing roller 31 to bring the surface of the fixing roller 31 to a predetermined temperature (hereinafter referred to as “heating temperature”). As the heating unit, for example, a heater, a halogen lamp, or the like can be used. The heating part is controlled by the control unit.

An unillustrated temperature detection sensor 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 of the temperature detection sensor is written into the storage unit of the control unit described below. The pressure roller 32 is provided in pressure contact with the fixing roller 31 and supported to be rotatable driven by the rotation of the pressure roller 32 . The toner is melted by heat from the fixing roller 31, and when the toner image is fixed to the recording medium, the pressure roller 32 assists the fixing of the toner image to the recording medium by pressing the toner and the recording medium. The pressure contact portion of the fixing roller 31 and the pressure roller 32 is a fixing nip.

Passing through the fixing section 4, the recording medium on which the toner image has been transferred in the transfer section 3 is nipped by the fixing roller 31 and the pressure roller 32, and when passing through the fixing nip section, the toner image is pressed under heat. to the recording medium, so that the toner image is fixed on the recording medium to form an image.

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 provided at a vertically lower portion of the image forming apparatus 100 and is a container-shaped member that stores recording media. The recording medium includes, for example, plain paper, color copy paper, sheets for overhead projectors, postcards, and the like. The pickup roller 36 takes out the recording media stored in the automatic paper feed tray 35 sheet by sheet, and conveys them to the paper conveyance path S1. The transport rollers 37 are a pair of roller members arranged in pressure contact with each other, and transport the recording medium to the registration roller 38 . The registration roller 38 is a pair of roller members arranged in pressure contact with each other, and synchronizes the transfer of the recording medium conveyed from the conveying roller 37 and the toner image carried by the intermediate transfer belt 25 to the transfer nip, and conveys to the transfer nip. department. The manual feed tray 39 is a device for taking recording media into the image forming apparatus 100. The recording media stored in the manual feed tray 39 are different from the recording media stored in the automatic paper feed tray 35. Any size. The recording medium taken in from the manual feed tray 39 passes through the paper conveyance path S2 by the conveyance roller 37 and is conveyed to the registration roller 38 . The recording medium supplied one by one from the automatic paper feed tray 35 or the manual paper feed tray 39 is conveyed to the transfer nip by the recording medium supply unit 5 in synchronization with the transfer of the toner image carried by the intermediate transfer belt 25 , Transfer to the transfer nip.

The discharge unit 6 includes a conveying roller 37 , a discharge roller 40 , and a discharge tray 41 . The transport roller 37 is provided downstream of the fixing nip in the sheet transport direction, and transports the recording medium on which the image has been fixed by the fixing unit 4 to the discharge roller 40 . The discharge roller 40 discharges the image-fixed recording medium to a discharge tray 41 provided on the vertically upper surface of the image forming apparatus 100 . The discharge tray 41 stores the image-fixed recording medium.

Image forming apparatus 100 includes a control unit not shown. The control unit is, for example, disposed on the 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 is input with various setting values input through an unillustrated operation panel disposed on the upper surface of the image forming apparatus 100 and detections from unillustrated sensors disposed at various places inside the image forming apparatus 100 . Results, image information from external devices, etc. Also, programs for executing each unit are written. The various processing is, for example, recording medium determination processing, adhesion amount control processing, fixing condition control processing, and the like. As the storage unit, those commonly used in this field can be used, and include, for example, read only memory (ROM), random access memory (RAM), hard disk drive (HDD), and the like. The external device can be an electric or electronic device that can form or obtain image information and is electrically connected to the image forming apparatus 100, such as a computer, a digital camera, a television, a video recorder, a DVD recorder, an HD DVD recorder, and a Blu-ray disc recorder. , fax devices, mobile terminal devices, etc. The calculation unit fetches various data (image forming commands, detection results, image information, etc.) written in the storage unit and programs for various processing, and performs various judgments. The control unit sends a control signal to the device according to the determination result of the calculation unit, and performs operation control. The control section and the calculation section include a processing circuit realized by a microcomputer having a central processing unit (CPU, central processing unit), a microprocessor, or the like. The control unit includes the above-mentioned processing circuit and also includes a main power supply, and the power supply supplies power not only to the control unit but also to each device inside the image forming apparatus 100 .

FIG. 4 is a schematic diagram schematically showing a developing device 14 included in the image forming apparatus 100 shown in FIG. 3 . The developing device 14 includes a developing tank 20 and a toner hopper 21 . The developing tank 20 is a container-shaped member disposed facing the surface of the photosensitive drum 11 , supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 11 , develops it, and forms a toner image as a visible image. The developing tank 20 accommodates toner in its internal space, and accommodates roller members such as a developing roller 50 , a supply roller 51 , and an agitating roller 52 , and supports them rotatably. In addition, a screw member may be accommodated instead of a roller-shaped member. In the developing device 14 of the present embodiment, the above-described magenta toner according to one embodiment of the present invention is accommodated in the developing tank 20 as the toner.

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-shaped member that supplies toner to an electrostatic latent image on the surface of the photosensitive drum 11 at a portion in contact with the photosensitive drum 11 or a portion closest to it. When the toner is supplied, a potential having a polarity opposite to the charged potential of the toner is applied as a developing bias to the surface of the developing roller 50 . In this way, the toner on the surface of the developing roller 50 is smoothly supplied to the electrostatic latent image. Furthermore, by changing the development bias value, the amount of toner supplied to the electrostatic latent image, that is, the amount of toner attached to the electrostatic latent image can be controlled.

The supply roller 51 is a roller-shaped member rotatably provided facing the developing roller 50 , and supplies toner to the periphery of the developing roller 50 .

The agitating roller 52 is a roller-shaped member rotatably provided facing the supply roller 51 , and conveys 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 arranged so that the toner replenishing port 54 provided at the lower part thereof in the vertical direction communicates with the toner receiving port 55 provided at the upper part of the developing tank 20 in the vertical direction. Toner Consumption Replenish toner. In addition, the toner may be directly replenished from the toner cartridges of the respective colors without using the toner hopper 21 .

In the above-mentioned image forming apparatus 100, an image is formed using the developer of the present invention, so that even if the image forming apparatus 100 is a high-speed device, it is possible to stably form an image with good color reproducibility and light fastness, and no color deviation or transfer. Efficiency drops for high-quality images.

(Example)

Specific examples of the present invention are described below, 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 temperature of adhesive resin)

The glass transition temperature of the binder resin is determined by DSC (differential scanning calorimeter) measurement. The sodium sulfonate group equivalent was determined by quantifying 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 as follows: 0.01 g of the binder resin is dissolved in a mixed solvent of 250 cc of phenol/tetrachloroethane (6:4 by weight), and measured using an Ostwald viscometer. The measurement was carried out at a temperature of 30°C.

(Time constant τ(msec) of magenta toner)

The time constant τ of the magenta toner is defined as the product RC when R is the resistance of the magenta toner and C is the capacitance of the magenta toner. The resistance (R) of the magenta toner and the capacitance (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 (adhesive resin) was produced as follows.

Add 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 parts by weight of Tetrabutoxy titanate as a catalyst was stirred for 120 minutes while being heated at 150° C. to 230° C., and reacted. Thereafter, it was heated to 250° C., the pressure of the reaction system was reduced to not less than 1 mmHg and not more than 10 mmHg, and stirred for about 1 hour to further react, thereby obtaining polyester resin A.

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

With 100 parts by weight of polyester resin A, 6.8 parts by weight of C.I. pigment red 48-3 and C.I. Wax Co., Ltd., acid value 0mgKOH/g, melting point 75°C), 1 part by weight of alkyl salicylic acid metal salt (charge control agent, trade name: BONTRON E-84, manufactured by Orient Chemical Co., Ltd.), in Henschel Mix in a mixer for 10 minutes to make a mixture. The obtained mixture was melt-kneaded with an open-roll type continuous kneader (trade name: MOS320-1800, manufactured by Mitsui Mining Co., Ltd.) to produce a melt-kneaded product.

The melt-kneaded product was roughly pulverized with a cutter mill (trade name: VM-16, manufactured by Lingxing Sangyo Co., Ltd.) to produce a coarsely pulverized product, and then the coarsely pulverized product was finely pulverized with a counter-jet mill. After the fine pulverization, the over pulverized toner was classified and removed by a rolling classifier to produce magenta toner particles having a volume average particle diameter of about 6.7 μm.

The magenta toner particles were spheroidized using an impact spheroidizer (trade name: Facalty F-600 type, manufactured by Hosokahe Micro Co., Ltd.). 100 parts by weight of spheroidized magenta toner particles, 2.2 parts by weight of hydrophobic silica (trade name: R-974, manufactured by Japan Aerosil Corporation) and 1.6 parts by weight of hydrophobic titanium (trade name: R-974) as additives Name: T-805, manufactured by Nippon アェロジル Co., Ltd.) 3.8 parts by weight in total, mixed with a Henschel mixer (trade name: FM Mikisa, manufactured by Mitsui Mining Co., Ltd.), thereby adding additives to magenta toner particles, and manufacturing The magenta toner of Example 1 was obtained. The magenta colorant content in the magenta toner particles was 6.0% by weight, and the paraffin wax content was 4.2% by weight relative to the total weight of the magenta toner.

In the magenta toner of Example 1, the paraffin content was changed to 1.70 parts by weight (1.49% by weight relative to the total weight of the magenta toner), 2 parts by weight (1.49% by weight relative to the total weight of the magenta toner), When the content is 1.75% by weight) and 3.5 parts by weight (3.03% by weight relative to the total weight of the magenta toner), good fixability was obtained, and aggregation of the magenta toner in the developing device was not found. Good images can be obtained.

However, when the paraffin content was changed to 1 part by weight (0.89% by weight relative to the total weight of the magenta toner), fixation shift occurred, and the paraffin content was changed to 5.5 parts by weight (0.89% by weight relative to the total weight of the magenta toner). When the content is 4.67% by weight), the fixability is good, but the magenta developer aggregates in the developing device, and toner aggregates appear in the image. From this, it can be seen that the content of the release agent is good when it is 1.5% by weight or more and 4.8% by weight or less with respect to the total amount of the 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 content of the magenta colorant in the magenta toner particles was 4% by weight.

In addition, although not described in detail, as a result of further changing the content of the magenta colorant and conducting experiments, the reproducibility is determined by the amount of the magenta colorant added to the binder resin.

(Example 3)

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

(Example 4)

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

(comparative example 1)

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

(comparative example 2)

A magenta toner of Comparative Example 2 was obtained as in Example 1 except that 7.3 parts by weight of C.I. Pigment Red 57-1 was added instead of C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1.

(comparative example 3)

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

Using the magenta toners of Examples and Comparative Examples, and the ferrite core carrier with a volume average particle diameter of 45 μm, the magenta toner was mixed in a V-type mixer ( Product name: V-5, manufactured by Tokushou Works Co., Ltd.) and mixed for 20 minutes. Thus, two-component developers containing the magenta toners of Examples and Comparative Examples were produced.

(evaluate)

The following evaluations were performed using two-component developers containing the magenta toners of Examples and Comparative Examples.

(reproducibility of vermilion)

The color gamut obtained when the magenta toner and the yellow toner of the comparative example were combined were obtained, and whether or not the vermilion of the vermilion ink pad was contained in the color gamut was determined as follows. In addition, as the yellow toner, a yellow toner using C.I. Pigment Yellow 74 as a colorant and a yellow toner using C.I. Pigment Yellow 185 as a colorant were used. The result was the same no matter which yellow toner was used.

Vermilion is a color obtained by combining yellow and magenta, so a color patch of the above two-color combination is output. Colors in which the image density of magenta is changed in the main scanning direction and the image density of yellow in the sub-scanning direction are changed in combination. The output print samples were color-measured (L*, a*, b*) by a reflection spectrodensitometer (X-Rite 939: manufactured by Excise Light Co., Ltd.). In each row and column of the color scale, if you pay attention to the change of L*, then L* changes continuously, so the data is extracted according to a certain L* value. When there is no target L* value, it is obtained by interpolating the two closest data. C* and Hab were calculated for each data obtained above. C* is the distance from the origin on the a*, b* plane (as a chroma proxy). Hab is the a* on the a*, b* plane, the angle θ° from the axis (+) direction (as a hue substitute). In this way, the color gamut obtained by color mixing of the produced magenta toner and yellow toner is obtained.

In addition, L*a*b* of the vermilion ink pad to be reproduced is measured using a reflection spectrodensitometer (X-Rite 939: manufactured by Exxraite Co., Ltd.), and vermilion is evaluated by whether or not it is included in the obtained color gamut. reproducibility. The vermilion L*a*b* of the vermilion ink pad is (55, 62, 33). In the color gamut obtained by combining the magenta toner of the example and the comparative example with the yellow toner, it was confirmed whether Vermilion L*a*b* (55, 62, 33) with vermilion inkpad. If the vermilion L*a*b*(55, 62, 33) of the vermilion ink pad is included in the color gamut, it is marked as "○", and if it does not contain it, it is marked as "×".

(Poor transfer, transfer efficiency, color deviation)

70 g of the magenta toner of Examples and Comparative Examples, and 930 g of a magnetic carrier (volume average particle diameter of 50 μm, silicone resin-coated carrier, manufactured by Pazuda-Tec Co., Ltd.) were stirred and mixed in a V-type mixer for 30 minutes to prepare 1000g of two-component developer. This two-component developer was filled in the developing tank of a commercially available digital color copier (trade name: MX-4500, manufactured by Sharp Corporation), and a test of 30,000 sheets (Neko Saletta one paper) letter size (letter size) was carried out. Real writing test of manuscript with 5% text area ratio. In addition, the adhesion amount of the magenta toner to the photosensitive drum in the actual writing test was set at 0.3 to 0.4 mg/cm ² . 3,000 copies are actually written, and the actual written manuscripts are used to evaluate poor transfer, transfer efficiency and color deviation.

(poor transfer)

If no transfer failure is found after writing 30,000 sheets, it will be marked as "○", and if transfer failure is found in the middle of writing 30,000 sheets, it will be marked as "X". An example of poor transfer is shown in Figure 2. In addition, the presence or absence of transfer failure was judged visually.

(transfer efficiency)

By writing 30,000 sheets, if the transfer efficiency can be maintained above 95%, it will be marked as "○", and if the transfer efficiency is less than 95% once, it will be marked as "X".

The transfer efficiency was calculated as follows. The transfer residual toner on the photosensitive drum after the full image transfer is rolled up with a polyester tape and peeled off, the polyester tape is pasted on an unused white paper, and the Macbeth density value is measured, and the measured value is " C". The entire image was transferred, and a polyester tape was attached to a white paper carrying an unfixed toner image, and the Macbeth density value was measured, and the measured value was "E". Then, a polyester tape was pasted on an unused white paper, and the Macbeth concentration value was measured, and the measured value was "D". The transfer efficiency was calculated using the following formula (5).

Transfer efficiency (%)={(E-C)/(E-D)}×100 …(5)

(color deviation)

If no color deviation is found through the actual writing of 30,000 sheets, it will be marked as "○", and if color deviation is found in the middle of the actual writing of 30,000 sheets, it will be marked as "×". An example of color deviation is shown in Figure 2. In addition, the presence or absence of color shift was judged visually.

(Overview)

Comprehensive evaluation was performed using the above evaluation results.

When all the above-mentioned evaluation results are "○", the overall evaluation result is "O", and if there is only one "X" in the evaluation results, the overall evaluation result is "X".

Table 1 shows the types, weight ratios, and contents of magenta colorants used in the production of magenta toners in Examples and Comparative Examples, the time constants of magenta toners, and the evaluation results and overall evaluation results of the above evaluations. . In addition, in Table 1, "C.I. Pigment Red" is described as "P.R."

Table 1

As can be seen from Table 1, Examples 1 to 4 containing C.I. Pigment Red 48-3 and C.I. Pigment Red 48-1 in a weight ratio of 8:2 to 5:5 obtained sufficient red reproducibility. In addition, as shown in Examples 1 to 4, when the time constant τ of the magenta toner is in the range of 1100 (msec) to 1300 (msec), a high temperature with no occurrence of color shift and no decrease in transfer efficiency can be obtained. Tasteful red image.

In Comparative Examples 1 and 2 in which the time constant τ of the magenta toner was less than 1100 (msec), color deviation occurred and the transfer efficiency decreased. In Comparative Example 3 in which the time constant τ of the magenta toner exceeded 1300 (msec), poor transfer occurred and the transfer efficiency decreased. In Comparative Example 3, the poor transfer and lowered transfer efficiency occurred because the electrostatic adhesion of the magenta toner to the intermediate transfer belt was too large.

The present invention can be implemented in various ways without departing from its gist and main characteristics. Therefore, the above-described embodiment is merely an example in every respect, and the scope of the present invention is shown in the claims, and is not restricted by the text of the specification at all. Furthermore, modifications and changes within the scope of the claims are within the scope of the present invention.

Claims (5)

1. an electrostatic image development magenta toner, is characterized in that,

Contain: binder resin; With

Colorant contains C.I. pigment red 4 8-3 and C.I. pigment red 4 8-1 with the weight ratios of 8: 2～5: 5,

Electrostatic image development is more than 1100msec, below 1300msec with the time constant of magenta toner.

2. electrostatic image development magenta toner according to claim 1, is characterized in that,

Wavelength is that the transmittance of the light of 440nm is more than 30%, below 45%.

3. a developer, is characterized in that,

Contain the described electrostatic image development of claim 1 or 2 magenta toner and carrier.

4. an image forming method, is characterized in that,

Charged image carrier surface is exposed, form electrostatic image at image carrier surface, right to use requires 3 described developers to make the electrostatic image development that forms on image carrier surface and form toner image.

5. image processing system is characterized in that having:

Image-carrier;

Charging system makes above-mentioned image-carrier charged;

Exposing unit to exposing by the charged image-carrier of Charging system, forms electrostatic image at image carrier surface; And

Developing apparatus provides the magenta toner of the electrostatic image development in developer claimed in claim 3 to the image-carrier that is formed with above-mentioned electrostatic image, makes above-mentioned electrostatic image development.

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