JP7809506B2 - Cyan toner - Google Patents

Description

This disclosure relates to cyan toner used in electrophotographic image forming methods.

In recent years, electrophotographic full-color copiers have become widely used, and there is a demand for high speed, high image quality, and high productivity, all while reducing costs. To achieve such high image quality, it is known that high image density can be achieved by finely dispersing pigments in toner (Patent Document 1). Another known technology for achieving cost reduction is the use of inexpensive fillers to reduce the amount of toner raw materials used (Patent Document 2).

Japanese Patent Application Laid-Open No. 2005-099422 JP 2016-114828 A

However, the toners described in the above-mentioned documents 1 and 2 have room for improvement in terms of color stability after long-term printing in low-temperature, low-humidity environments. The present disclosure provides a toner that maintains high coloring power while achieving stable color even in low-temperature, low-humidity environments.

The present disclosure provides a toner comprising toner particles containing copper phthalocyanine and calcium carbonate particles ;
Inorganic fine particles ,
A cyan toner having
In powder X-ray diffraction measurement using the cyan toner as a sample, when the Bragg angle is θ, the peak intensity at 2θ (2θ±0.2°) of 9.0 to 9.4° is A and the peak intensity at 23.6 to 24.0° is B, the ratio B/A is 0.70 or more and 1.20 or less,
The cyan toner is characterized in that the inorganic fine particles have a volume resistivity of 2.0×10 ⁹ Ω·cm or more and 2.0×10 ¹² Ω·cm or less.

This disclosure makes it possible to provide a toner that maintains high coloring power while achieving stable color even in low-temperature, low-humidity environments.

1 is a graph showing the results of X-ray diffraction measurement of toner CT1 in Examples.

In this disclosure, unless otherwise specified, the expression "XX or greater and YY or less" representing a numerical range means a numerical range including the endpoints, that is, the lower and upper limits. When a numerical range is stated in stages, the upper and lower limits of each numerical range can be combined in any way.

The present disclosure provides a cyan toner having toner particles containing copper phthalocyanine and inorganic particulates,
In powder X-ray diffraction measurement using the toner as a sample, when the Bragg angle in CuKα characteristic X-ray diffraction is θ, the peak intensity in 2θ (2θ±0.2°) of 9.0 to 9.4° is A and the peak intensity in 2θ of 23.6 to 24.0° is B, the ratio B/A is 0.70 or more and 1.20 or less,
The cyan toner is characterized in that the inorganic fine particles have a volume resistivity of 2.0×10 ⁹ Ω·cm or more and 2.0×10 ¹² Ω·cm or less.

The following are thought to be the reasons why the above cyan toner achieves both high image density and color stability after long-term printing in low-temperature, low-humidity environments.

It has been found that if copper phthalocyanine, the colorant in cyan toner, is finely dispersed within the image layer after toner fixation, visible light is absorbed efficiently, resulting in an image with high image density. On the other hand, the finer the copper phthalocyanine, the stronger its cohesive force, making it more likely to aggregate and become unevenly distributed within or on the surface of the toner.

When this copper phthalocyanine aggregate is exposed on the surface of a toner particle, it is prone to becoming positively charged due to frictional charging with the carrier in the developer, especially in low-temperature, low-humidity environments. As a result, the chargeability of the toner particles is impaired, and color variations occur as the number of printed pages increases.

However, we have found that the cyan toner disclosed herein achieves high image density while also offering excellent color stability. We believe the reasons for this are as follows:

When the Bragg angle in CuKα characteristic X-ray diffraction of the copper phthalocyanine contained in the cyan toner of the present invention is taken as θ, the 2θ (2θ±0.2°) peak intensity between 9.0 and 9.4° is taken as A and the peak intensity between 23.6 and 24.0° is taken as B, and the ratio B/A is 0.70 or greater and 1.20 or less.

This suggests that the copper phthalocyanine crystals have an adequate number of planes with small lattice spacing, which is thought to facilitate the movement of charges on the copper phthalocyanine. Furthermore, when low-resistance external additive components are present in the vicinity of the copper phthalocyanine, charges are more easily transferred from the low-resistance external additive to the copper phthalocyanine. As a result, because the charges on the copper phthalocyanine are more easily mobile, it is possible to eliminate the positive charge on the copper phthalocyanine surface, resulting in excellent color stability.

The components of the toner are described below.

<Copper phthalocyanine>
The toner particles contain a copper phthalocyanine pigment.

Examples of copper phthalocyanine pigments include: C.I. Pigment Blue 2, 3, 15:2, 15:3, 15:4, 16, and 17; C.I. Vat Blue 6; C.I. Acid Blue 45; and copper phthalocyanine pigments in which one to five phthalimidomethyl groups are substituted on the phthalocyanine skeleton. From the standpoint of color development, C.I. Pigment Blue 15:3 is preferred.

Here, when the Bragg angle in the CuKα characteristic X-ray diffraction of copper phthalocyanine is θ, 2θ (2θ±0.2°) is A, the peak intensity between 9.0 and 9.4° is B, and the peak intensity between 23.6 and 24.0° is B, and the ratio B/A is 0.70 or greater and 1.20 or less.

This strength ratio can be controlled, for example, by kneading copper phthalocyanine with calcium carbonate particles and a resin (described below) in a twin-screw extruder under high temperature and high shear conditions. For example, by increasing the solids concentration and kneading under high shear stress, the copper phthalocyanine crystals are subjected to impact, making it possible to increase the B/A value. The preferred range for B/A is 0.78 or more and 1.10 or less.

<Binder resin>
The toner particles contain a binder resin. As the binder resin, known polymers can be used, and specifically, for example, the following polymers can be used.

Examples of suitable resins include homopolymers of styrene and its substituted derivatives, such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, and styrene-acrylonitrile-indene copolymer; and styrene-based copolymers, such as polyvinyl chloride, phenolic resin, natural resin-modified phenolic resin, natural resin-modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester resin, polyurethane resin, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone-indene resin, and petroleum-based resin. These resins may be used alone or in combination. Among these, polyester resin is preferred from the viewpoint of the chargeability of toner particles.

It is also preferable to use a crystalline polyester resin in combination with the binder resin. By using a crystalline polyester, the pigment particles tend to have more crystallites with small lattice spacing during the toner kneading process described below, improving color stability.

The content of crystalline polyester is preferably 20% by weight or more and 170% by weight or less relative to the copper phthalocyanine. If it is 20% by weight or more, the above-mentioned effects are more likely to be achieved. If it is 170% by weight or less, the positive charge generated in the copper phthalocyanine is less likely to leak throughout the toner particles, improving color stability.

The monomer unit of the crystalline polyester is not particularly limited, but it is particularly preferred that the alcohol component be ethylene glycol and the carboxylic acid component be 1,12-dodecanedicarboxylic acid. By incorporating a crystalline polyester containing such hydrophilic and hydrophobic units, the dispersibility of the pigment is improved, which tends to improve image density.

<Calcium carbonate particles>
The toner particles preferably contain calcium carbonate particles in an amount of 1.0 part by mass or more and 15.0 parts by mass or less per 100 parts by mass of the total mass of the toner particles. When calcium carbonate is contained within this range, calcium carbonate present near the copper phthalocyanine during long-term printing suppresses the copper phthalocyanine from being embedded in the cyan toner, allowing efficient transfer of charges generated from the inorganic particles and preventing the loss of color stability.

If the content of calcium carbonate particles in the cyan toner is less than 1.0 part by mass, the above-mentioned effect is unlikely to occur. If it is more than 15.0 parts by mass, the amount of calcium carbonate particles is too high, and light is scattered by the calcium carbonate particles in the cyan toner, which can easily lead to poor color development.

The above content of calcium carbonate particles in the toner particles is more preferably 1.5 parts by mass or more and 12.0 parts by mass or less, and particularly preferably 2.0 parts by mass or more and 10.0 parts by mass or less.

In addition, calcium carbonate can also be removed from toner particles or pigment master batches by reacting them with calcium chloride, water, carbon dioxide, etc. using hydrochloric acid, etc., and then rinsing with water.

When the toner is subjected to X-ray diffraction measurement using CuKα radiation, the calcium carbonate particles have peaks at 26.5±0.1 and 29.5±0.1 in 2θ (2θ±0.2°) where θ is the Bragg angle in the characteristic X-ray diffraction of CuKα,
the crystallite size of calcium carbonate calculated from a peak at 29.5±0.1° at 2θ (2θ±0.2°) when θ is the Bragg angle is 10 nm or more and 45 nm or less;
It is preferable that the ratio of the peak intensity at 26.5±0.1 to the peak intensity at 29.5±0.1 be 0.11 or more and 0.24 or less.

By creating calcium carbonate in this state, the positive charge on the calcium carbonate near the copper phthalocyanine is alleviated, allowing charge transfer from the inorganic particles to occur more efficiently, making it less likely that color stability will be compromised.

Here, the crystallite size of calcium carbonate calculated from the peak at a Bragg angle (2θ) of 29.5±0.1 can be controlled, for example, by changing the concentration of calcium carbonate or pigment in the first kneading step described below. Increasing the concentration of calcium carbonate or pigment results in kneading conditions with greater shear stress, resulting in a smaller crystallite size of calcium carbonate.

The ratio of the peak intensity at a Bragg angle (2θ) of 26.5±0.1 to the peak intensity at a Bragg angle (2θ) of 29.5±0.1 can also be controlled by changing the concentration of calcium carbonate and pigment in the first kneading process described below. Increasing the concentration of calcium carbonate and pigment results in kneading conditions with greater shear stress, increasing the ratio of the peak intensity at a Bragg angle (2θ) of 26.5±0.1 to the peak intensity at a Bragg angle (2θ) of 29.5±0.1.

<Release Agent>
If necessary, a release agent may be used to suppress the occurrence of hot offset during heat fixing of the cyan toner. Typical examples of the release agent include low-molecular-weight polyolefins, silicone wax, fatty acid amides, ester waxes, carnauba wax, and hydrocarbon waxes.

<External additives>
(Inorganic fine particles)
The cyan toner contains inorganic fine particles with a volume resistivity of 2.0× ¹⁰ Ω·cm or more and 2.0× ¹⁰ Ω·cm or less. The inclusion of inorganic fine particles with such a volume resistivity causes charge transfer to the positively charged pigment particles, thereby eliminating the positive charge and suppressing color variation. The volume resistivity can be controlled by the type of inorganic fine particles and surface treatment.

Such inorganic fine particles are preferably strontium titanate particles or titanium oxide particles, with strontium titanate particles being more preferred from the standpoint of dielectric constant.

The number-average particle size of strontium titanate is preferably 20 nm or more and 80 nm or less. This particle size range more effectively eliminates the positive charge on the copper phthalocyanine surface. The particle size of strontium titanate can be controlled by the crushing strength during production, etc.

The dielectric constant of strontium titanate is preferably 25.0 pF/m or more and 100.0 pF/m or less. By keeping the dielectric constant within this range, strontium titanate is appropriately polarized during development, more effectively eliminating the positive charge on the copper phthalocyanine surface. Factors that influence the dielectric constant include conditions and operations that disrupt particle crystallinity. For example, it is preferable to increase the concentration of the reaction solution and perform an operation that applies energy that disrupts crystal growth. A specific method is to add nitrogen microbubbling to the crystal growth process.

The amount of strontium titanate added is preferably 0.2 parts by weight or more and 1.0 parts by weight or less per 100 parts by weight of toner particles.

(Organosilicon Polymer Particles)
Furthermore, it is preferable that cyan toner contains externally added organosilicon polymer particles, which are resin particles having a main chain formed by alternating bonds between silicon and oxygen atoms having organic groups.

By adding fine particles such as organosilicon polymer particles to the cyan toner, the organosilicon polymer particles roll on the surface of the cyan toner during the charging and development process, causing the inorganic fine particles with a volume resistivity of 2.0 x ¹⁰ Ω·cm or more and 2.0 x ¹⁰ Ω·cm or less to migrate along the toner particle surface, resulting in efficient charge transfer from the inorganic fine particles to the positively charged pigment particles, thereby suppressing color variation.

The amount of organosilicon polymer particles added is preferably 0.5 parts by weight or more and 5.0 parts by weight or less per 100 parts by weight of toner particles.

If necessary, external additives may be used in combination with inorganic particles such as silica and alumina, or resin particles such as vinyl resin, polyester resin, and silicone resin.

<Manufacturing Method of Cyan Toner>
The method for producing the cyan toner is not particularly limited, and known methods such as emulsion aggregation, kneading and pulverization, and suspension polymerization can be used, but the kneading and pulverization method is preferred.

The manufacturing method using the kneading and grinding method is described below.

First, the materials that make up the toner particles, such as binder resin, pigment, calcium carbonate, and, if necessary, other ingredients such as a release agent, are weighed out in predetermined amounts, blended, and mixed. Examples of mixing devices include a double-con mixer, V-type mixer, drum mixer, super mixer, Henschel mixer, Nauta mixer, and Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.).

Next, the mixed materials are melt-kneaded. For the melt-kneading process, a batch-type kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used, but a single-screw or twin-screw extruder is preferred due to its advantage of allowing for continuous production. The melt-kneading temperature is preferably around 100 to 200°C.

The melt-kneading process may include a first kneading process in which a portion of the binder resin is melt-kneaded with copper phthalocyanine and calcium carbonate particles to obtain a pigment mixture, and a second kneading process in which the copper phthalocyanine mixture is melt-kneaded with the remainder of the binder resin.

The first kneading step can contain a high proportion of solids that do not melt during kneading, such as copper phthalocyanine and calcium carbonate particles, and can cause copper phthalocyanine to collide with other copper phthalocyanine particles or with calcium carbonate under high shear stress. Under these conditions, the crystal lattice of copper phthalocyanine changes, increasing the number of crystals with narrow lattice spacing.

Kneading equipment used includes, for example, a KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Iron Works), a twin-screw extruder (manufactured by KCK Corporation), a Co-Kneader (manufactured by Buss Corporation), and a Kneedex (manufactured by Nippon Coke and Engineering Co., Ltd.). Furthermore, the resin composition obtained by melt-kneading is rolled using a twin roll or the like, and then quenched with water or the like in a cooling process.

The cooled resin composition is then pulverized to the desired particle size in a pulverization process. In this process, the resin is coarsely pulverized using a pulverizer such as a crusher, hammer mill, or feather mill, and then further pulverized using a pulverizer such as a Kryptron System (Kawasaki Heavy Industries), a Super Rotor (Nisshin Engineering), a Turbo Mill (Turbo Kogyo), or an air jet type pulverizer.

Then, if necessary, the mixture is classified using a classifier or sieve such as the inertial classification Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), the centrifugal classification Turboplex (manufactured by Hosokawa Micron Corporation), the TSP Separator (manufactured by Hosokawa Micron Corporation), or the Faculty (manufactured by Hosokawa Micron Corporation) to obtain a classified product.

The weight average particle size of the toner particles is preferably 4 μm or more and 12 μm or less, and more preferably 5 μm or more and 8 μm or less.

The toner particles produced through the above process are mixed with inorganic fine particles, organosilicon polymer fine particles, and optionally resin fine particles such as silica, alumina, vinyl resin, or polyester resin, with a volume resistivity of 2.0×10 ⁹ Ω·cm or more and 2.0×10 ¹² Ω·cm or less, and a shear force is applied in a dry state to produce a toner.

These inorganic and resin microparticles function as external additives such as flow aids and cleaning aids.

Cyan toner can be used as a one-component developer, but it can also be mixed with a magnetic carrier to be used as a two-component developer. Examples of magnetic carriers that can be used include commonly known types such as surface-oxidized or unoxidized iron powder, metal particles such as iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, and rare earth elements, alloy particles thereof, oxide particles, and magnetic materials such as ferrite, as well as magnetic material-dispersed resin carriers (so-called resin carriers) that contain magnetic materials and a binder resin that holds the magnetic materials in a dispersed state.

When toner is mixed with a magnetic carrier to be used as a two-component developer, good results can be obtained by mixing the carrier at a ratio of 2% by weight to 15% by weight, more preferably 4% by weight to 13% by weight, in terms of toner concentration in the two-component developer.

The measurement methods for each physical property are described below.

<X-ray powder diffraction of cyan toner>
Using a measuring device "RINT-TTRII" (manufactured by Rigaku Corporation), measurements are performed using CuKα characteristic X-rays over a Bragg angle range (2θ±0.20°) of 3° to 60°, and the peak intensity at a Bragg angle (2θ) of 9.0 to 9.4° and the peak intensity at a Bragg angle (2θ) of 23.6 to 24.0° are determined from the total integrated intensity of the obtained spectrum.

The measurement conditions are as follows:
X-ray: Cu/50kV/300mA
Goniometer: Rotor horizontal goniometer (TTR-2)
Attachment: Standard sample holder Divergence slit: Open Divergence vertical limit slit: 10.00 mm
Scattering slit: open Receiving slit: open Counter: scintillation counter Scanning mode: continuous Scanning speed: 4.0000°/min.
Sampling width: 0.0200°
Scanning axis: 2θ/θ
Scanning range: 10.0000 to 40.0000°

<Volume resistivity of inorganic fine particles>
The volume resistivity of inorganic fine particles is measured as follows: A Keithley Instruments 6517 Electrometer/High Resistance System is used as the device. Electrodes with a diameter of 25 mm are connected, and inorganic fine particles are placed between the electrodes to a thickness of about 0.5 mm. A load of about 2.0 N is applied, and the distance between the electrodes is measured.

A voltage of 1,000 V is applied to the inorganic fine particles for 1 minute, and the resistance value is measured, and the volume resistivity is calculated using the following formula.
Volume resistivity (Ω・cm)=R×L
R: Resistance value (Ω)
L: Distance between electrodes (cm)

In addition, inorganic fine particles can be separated from cyan toner and measured using the following method.

200 g of sucrose (Kishida Chemical) is added to 100 mL of ion-exchanged water and dissolved over a hot water bath to prepare a concentrated sucrose solution. 31 g of the concentrated sucrose solution and 6 mL of Contaminon N (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) are placed in a centrifuge tube to prepare a dispersion. 1 g of cyan toner is added to this dispersion, and any clumps of toner are broken up using a spatula or similar tool.

The centrifuge tube is shaken for 20 minutes in a shaker (Iwaki Sangyo Co., Ltd. "KM Shaker" (model: V.SX)) at 350 reciprocations per minute. After shaking, the solution is transferred to a 50 mL glass tube for a swing rotor and centrifuged at 3,500 rpm for 30 minutes in a centrifuge. After centrifugation, the toner is present in the top layer of the glass tube, and inorganic fine particles are present in the aqueous solution below. The aqueous solution below is sampled and centrifuged to separate the sucrose and inorganic fine particles, and the inorganic fine particles are collected. Centrifugation is repeated as necessary to thoroughly separate the dispersion, after which the dispersion is dried and the inorganic fine particles are collected.

If multiple inorganic microparticles are added, they can be separated using methods such as centrifugation.

<Method for measuring the dielectric constant of inorganic fine particles>
Using a 284A Precision LCR Meter (manufactured by Hewlett-Packard), the complex dielectric constant at a frequency of 2 kHz is measured after calibration at frequencies of 1 kHz and 1 MHz. A load of 39,200 kPa (400 kg/ ^cm2 ) is applied to the sample to be measured for 5 minutes, and the sample is molded into a disk-shaped measurement sample with a diameter of 25 mm and a thickness of 1 mm or less (preferably 0.5 to 0.9 mm). This measurement sample is mounted on an ARES (manufactured by Rheometric Scientific F.E.) equipped with a 25 mm diameter dielectric constant measurement jig (electrode), and measurement is performed at a frequency of 2 kHz under a load of 0.49 N (50 g) in an atmosphere at 25°C.

If necessary, the inorganic fine particles can be extracted from the toner and the dielectric constant measured using the method for separating inorganic fine particles from cyan toner described above in the method for measuring volume resistivity.

<Method for measuring number average particle diameter of inorganic fine particles>
Using the above-described method for separating inorganic particles from cyan toner, inorganic particles are extracted from the cyan toner and observed using a Hitachi ultra-high resolution field emission scanning electron microscope (FE-SEM) S-4800 (Hitachi High-Technologies Corporation).

Measure the particle diameter of 100 inorganic microparticles and calculate the arithmetic average, which is the number-average diameter of the primary particles of the inorganic micropowder.

<Identification of Monomer Units of Crystalline Polyester>
The structure is analyzed using a pyrolysis gas chromatography mass spectrometer (GC-MS) as follows. 300 μg of crystalline polyester is embedded in Pyrofoil (F590 manufactured by Japan Analytical Industry Co., Ltd.) and introduced into a pyrolysis furnace. It is heated at 590°C for 5 seconds in an inert (helium) atmosphere, and the generated decomposition gas is introduced into the gas chromatograph inlet, and the following oven profile is performed. The column outlet is connected to an MS analyzer via a transfer line, and a total ion chromatogram (TIC) is obtained, plotting ion current on the vertical axis and retention time on the horizontal axis. Next, mass spectra are extracted for all peaks detected in the obtained chromatogram using the accompanying software, and the compounds are assigned based on the NIST-2017 database.

Alternatively, crystalline polyester can be separated from cyan toner and measured using the following method. 200 g of sucrose (Kishida Chemical) is added to 100 mL of ion-exchanged water and dissolved over a hot water bath to prepare a sucrose concentrate. 31 g of this sucrose concentrate and 6 mL of Contaminon N (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) are placed in a centrifuge tube to prepare a dispersion. 1 g of toner is added to this dispersion, and clumps of cyan toner are broken up using a spatula or similar tool.

The centrifuge tube is shaken for 20 minutes in a shaker (Iwaki Sangyo Co., Ltd. "KM Shaker" (model: V.SX)) at 350 strokes per minute. After shaking, the solution is transferred to a glass tube (50 mL) for a swing-out rotor and centrifuged at 3,500 rpm for 30 minutes in a centrifuge. After centrifugation, toner is present in the top layer of the glass tube, and inorganic fine particles are present in the lower aqueous solution layer.

The upper layer of cyan toner is separated and dissolved in toluene. The insoluble matter is then filtered off and measured using the pyrolysis gas chromatography mass spectrometer described above.

<Quantitative Determination of Organosilicon Polymer Fine Particles in Cyan Toner>
1g of cyan toner was placed in a vial and dissolved in 31g of chloroform, followed by 30 minutes of processing using an ultrasonic homogenizer to create a dispersion. The dispersion was then centrifuged to separate the organosilicon polymer microparticles from other external additives based on differences in specific gravity, yielding samples from which the organosilicon polymer microparticle content was determined.

If necessary, the structure of each sample is determined using solid-state ²⁹ Si-NMR and pyrolysis GC/MS, and the organosilicon polymer fine particles are identified.

<Identification of calcium carbonate content>
A sucrose concentrate was prepared by adding 160 g of sucrose to 100 mL of ion-exchanged water and dissolving it in a hot water bath. A centrifuge tube was charged with 31 g of the sucrose concentrate and 6 mL of nonionic surfactant to prepare a dispersion. 5.0 g of cyan toner was added to the dispersion, and the cyan toner clumps were broken down using a spatula or similar. The centrifuge tube was then shaken in a shaker. After shaking, the solution was centrifuged at 3,500 rpm for 30 minutes to remove the precipitate. The floating solids were filtered through a vacuum filter and dried in a dryer for at least one hour. 1 g of the resulting solids was dissolved in 20 mL of chloroform and centrifuged at 15,000 rpm for 180 minutes. The supernatant was discarded. Another 20 mL of chloroform was added, and the same procedure was repeated twice. The precipitated solids were dried in a dryer for at least five hours, weighed, and the calcium carbonate content was determined.

If necessary, the components of the solid obtained above can be identified using an "Axios" wavelength dispersive X-ray fluorescence analyzer (manufactured by PANalytical).

<X-ray diffraction peak measurement of calcium carbonate>
X-ray diffraction measurement of calcium carbonate contained in cyan toner is performed using a measuring device "RINT-TTRII" (manufactured by Rigaku Corporation) with CuKα characteristic X-rays, measuring at a Bragg angle (2θ±0.20°) in the range of 3° to 60°, and from the total integrated intensity of the obtained spectrum, the crystallite size of the crystals assigned to a Bragg angle (2θ) of 29.5±0.5 and the ratio of the peak intensity of the crystals assigned to a Bragg angle (2θ) of 26.5±0.5 to the peak intensity of the crystals assigned to a Bragg angle (2θ) of 29.5±0.5 are determined.

The measurement conditions are as follows:
X-ray: Cu/50kV/300mA
Goniometer: Rotor horizontal goniometer (TTR-2)
Attachment: Standard sample holder Divergence slit: Open Divergence vertical limit slit: 10.00 mm
Scattering slit: open Receiving slit: open Counter: scintillation counter Scanning mode: continuous Scanning speed: 4.0000°/min.
Sampling width: 0.0200°
Scanning axis: 2θ/θ
Scanning range: 10.0000 to 40.0000°

The present invention will be explained in more detail below using examples and comparative examples, but these should not be construed as limiting the present invention in any way.

<Production of Copper Phthalocyanine 1>
C.I. Pigment Blue 15:3 was used as it was to prepare copper phthalocyanine 1.

<Production of Copper Phthalocyanine 2>
The above materials were stirred for 4 hours at a rotation speed ^of 2 s using a Trimix (TX-15 model, manufactured by Inoue Seisakusho Co., Ltd.). The resulting mixture was washed with water, filtered, and dried to obtain copper phthalocyanine 2.

<Production of cyan pigment masterbatch CM1 (first kneading step)>
Copper phthalocyanine 1 30 parts by mass Calcium carbonate 1 (number average particle size 400 nm) 40 parts by mass Amorphous polyester resin A 27 parts by mass [Amorphous polyester resin A: composition (mol %) [polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane:isophthalic acid:terephthalic acid=100:50:50]]
Crystalline polyester C1: 3 parts by mass [Crystalline polyester C1: composition (mol %) [ethylene glycol: dodecanedioic acid = 100:100]]

(First kneading step)
The above materials were mixed using a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed ^of 20 s for a rotation time of 5 min, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) at 200 rpm and 150°C.

The resulting kneaded material was cooled and coarsely pulverized in a pin mill to a volume average particle size of 100 μm or less, yielding coarsely pulverized cyan pigment masterbatch CM1.

<Production of cyan pigment masterbatches CM2 to CM8 and CM10 to CM12>
Cyan pigment masterbatches CM2 to CM8 and CM10 to CM12 were obtained in the same manner as for cyan pigment masterbatch CM1, except that the materials and blending amounts were changed as shown in Table 1. The composition of crystalline polyester C2 used in cyan pigment masterbatch CM2 is as follows.
Crystalline polyester C2: Composition (mol %) [1,6-hexanediol:dodecanedioic acid=100:100]

<Production of cyan pigment masterbatch CM9>
A coarsely crushed cyan pigment masterbatch was obtained by manufacturing in the same manner as cyan pigment masterbatch CM1, except for the materials shown in Table 1. Subsequently, 1,000 g of acetone was added to 100 g of the coarsely crushed cyan pigment masterbatch, and then 10 g of 1 N hydrochloric acid was added. The mixture was left to stand with stirring for 6 hours to react with calcium carbonate, producing carbon dioxide, water, and calcium chloride. The resulting liquid was then dried and coarsely crushed using a pin mill to a volume average particle size of 100 μm or less, thereby obtaining cyan pigment masterbatch CM9.

<Production of Toner Particles CP1>
Amorphous polyester resin A 70.6 parts by mass Crystalline polyester C1 1.4 parts by mass Pigment masterbatch CM1 20.0 parts by mass Synthetic wax 1 8.0 parts by mass (hydrocarbon wax, maximum endothermic peak temperature 90°C)

(Second kneading step)
The above materials were mixed using a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed ^of 20 s for a rotation time of 5 min, and then kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) at 200 rpm and 120°C, and the resulting kneaded product was cooled.

The material was coarsely crushed using a pin mill to a volume average particle size of 100 μm or less, yielding a coarsely crushed product. The resulting coarsely crushed product was then finely crushed using a mechanical crusher (T-250, manufactured by Turbo Kogyo Co., Ltd.) by adjusting the rotation speed and number of passes to obtain the desired particle size.

Further classification was performed using a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) to obtain toner particles. The operating conditions of the rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) were such that the rotation speed was adjusted to obtain the desired particle size and particle size distribution, and toner particles CP1 were obtained.

<Production Example of Toner Particles CP2 to CP12>
Cyan toner particles CP2 to CP12 were obtained in the same manner as in the cyan toner particles CP1, except that the materials and blending amounts were changed as shown in Table 2.

<Production Example of Strontium Titanate 1>
Metatitanic acid produced by the sulfuric acid method was deironized and bleached, then desulfurized by adding a 3 mol/L aqueous solution of sodium hydroxide to adjust the pH to 9.0, and then neutralized to pH 5.6 with 5 mol/L hydrochloric acid, filtered, and washed with water. Water was added to the washed cake to make a slurry of 1.90 mol/L in terms of _TiO2 , and hydrochloric acid was added to adjust the pH to 1.4, which was then subjected to peptization.

1.90 moles of _TiO2 were collected from the desulfurized and peptized metatitanic acid and charged into a 3 L reaction vessel. 2.185 moles of an aqueous strontium chloride solution were added to the peptized metatitanic acid slurry so that the SrO/ _TiO2 (molar ratio) was 1.15, and the _TiO2 concentration was then adjusted to 1.039 mole/L.

Next, the mixture was heated to 90°C while stirring, and 440 mL of a 10 mol/L aqueous solution of sodium hydroxide was added over 40 minutes. Stirring was then continued at 95°C for 45 minutes, after which the mixture was poured into ice water and rapidly cooled to terminate the reaction.

The reaction slurry was heated to 70°C, 12 mol/L hydrochloric acid was added until the pH reached 5.0, and stirring was continued for 1 hour, after which the resulting precipitate was decanted.

The resulting slurry containing the precipitate was adjusted to 40°C, and hydrochloric acid was added to adjust the pH to 2.5. Subsequently, 4.0 mass% of 3,3,3-trifluoropropyltrimethoxysilane (based on the solids) as surface treatment agent 1 and 4.0 mass% of isobutyltrimethoxysilane (based on the solids) as surface treatment agent 2 were added, and the mixture was stirred for 10 hours. A 5 mol/L aqueous sodium hydroxide solution was added to adjust the pH to 6.5, and stirring was continued for 1 hour. After filtering and washing, the resulting cake was dried in air at 120°C for 8 hours to obtain strontium titanate 1.

The resulting strontium titanate 1 had a dielectric constant of 70 pF/m, a volume resistivity of 1.5×10 ¹¹ Ωcm, and a number average particle size (D1) of the primary particles of 40 nm.

<Production Examples of Strontium Titanates 2 to 9>
In the production example of strontium titanate 1, the _TiO2 concentration in the mixed solution after the addition of the strontium chloride aqueous solution, the dropping time of the sodium hydroxide aqueous solution, the stirring time after dropping, whether or not quenching was performed, and the surface treatment agent were changed as shown in Table 3. Apart from these changes, strontium titanates 2 to 9 were obtained in the same manner as in the production example of strontium titanate 1. Their physical properties are shown in Table 3.

<Production Example of Titanium Oxide 1>
Ilmenite ore containing 50% by mass of _TiO2 equivalent was used as the starting material. This raw material was dried at 150°C for 2 hours, and then sulfuric acid was added and dissolved to obtain an aqueous solution of _TiOSO2 . Sodium carbonate was added to this aqueous solution to adjust the pH to 9.0 for alkaline neutralization, and the solution was filtered to obtain a white precipitate. Pure water was added to this white precipitate, and the mixture was heated at approximately 90°C for 2.5 hours to perform hydrolysis. This was followed by repeated filtration and washing with water to obtain anatase-type titanium oxide.

The resulting anatase-type titanium oxide was sintered at a high temperature of 1100°C to obtain rutile-type titanium oxide. This rutile-type titanium oxide was then crushed in a jet mill to obtain titanium oxide microparticles. These titanium oxide microparticles were dispersed in ethanol, and 10 parts by mass (solids) of isobutyltrimethoxysilane as a hydrophobizing agent was added dropwise to 100 parts by mass of titanium oxide microparticles while stirring thoroughly to prevent particle coalescence, and the mixture was reacted to perform a hydrophobizing treatment.

The pH of the slurry was adjusted to 6.5 while stirring thoroughly. After filtering and drying, the slurry was heat-treated at 170°C for 2 hours, and then repeatedly crushed using a jet mill until no titanium oxide agglomerates remained, yielding titanium oxide 1.

Titanium oxide 1 had a volume resistivity of 2.7×10 ¹⁰ Ωcm, a dielectric constant of 25 pF/m, and a number average particle size of the primary particles of 30 nm.

<Production Example of Calcium Titanate 1>
Titanium tetraisopropoxide was used as the raw material, and was pumped little by little by a chemical pump using nitrogen gas as a carrier gas into glass wool in a vaporizer heated to about 200°C to evaporate it, and after instantaneous thermal decomposition at about 300°C in a reactor, it was rapidly cooled and the product was collected, which was then calcined at about 300°C for another 2 hours and pulverized in a jet mill to obtain titanium oxide.

52 parts by mass of the above titanium oxide and 48 parts by mass of calcium carbonate were dispersed in 100 parts by mass of water, mixed well, and heat-treated at a temperature of approximately 1000°C to obtain calcium titanate 1.

Calcium titanate 1 had a volume resistivity of 3.6×10 ¹¹ Ωcm, a dielectric constant of 30 pF/m, and a number average particle size of the primary particles of 40 nm.

<Preparation Example of Organosilicon Polymer Particles 1>
1. Hydrolysis Step 43.2 g of RO water and 0.008 g of acetic acid as a catalyst were placed in a 200 ml beaker and stirred at 45° C. 27.2 g of tetraethoxysilane and 27.2 g of dimethyldimethoxysilane were added thereto and stirred for 1.5 hours to obtain a raw material solution.

2. Condensation polymerization step: 68.8 g of RO water, 340.0 g of methanol, and 2.0 g of 25% aqueous ammonia were added to a 1000 ml beaker and stirred at 30°C to prepare an alkaline aqueous medium. The raw material solution obtained in the hydrolysis step was added dropwise to this alkaline aqueous medium over 1 minute. After the dropwise addition of this raw material solution, the mixture was stirred for 1.5 hours while maintaining the temperature at 30°C to allow the polycondensation reaction to proceed, thereby obtaining a polycondensation reaction solution.

3. Particle Formation Step: 1000 g of RO water was placed in a 2000 ml beaker, and the polycondensation reaction solution obtained in 2. Polycondensation Step was added dropwise over 10 minutes while stirring at 25° C. The polycondensation reaction solution immediately became cloudy upon mixing with the water, yielding a dispersion containing silicon polymer particles having siloxane bonds.

27.1 g of hexamethyldisilazane was added as a hydrophobizing agent to the dispersion containing the silicon polymer particles having siloxane bonds obtained in the particulation step, and the mixture was stirred for 2.5 hours at 60° C. After leaving the mixture to stand for 5 minutes, the powder that precipitated at the bottom of the solution was recovered by suction filtration and dried under reduced pressure at 120° C. for 24 hours to obtain organosilicon polymer particles 1.

<Production Example of Cyan Toner CT1>
Toner particles CP1 100 parts by mass Silica fine particles 1 1.8 parts by mass (Silica fine particles 1: silica fine particles having a specific surface area of 200 m ² /g measured by the BET method and hydrophobized with silicone oil)
Strontium titanate 1 0.5 parts by weight Organosilicon polymer particles 1 1.0 parts by weight The above materials were mixed in a Henschel mixer (FM-75, manufactured by Mitsui Mining Co., Ltd.) at a rotation speed of 30 s ⁻¹ for a rotation time of 10 minutes to obtain cyan toner CT1.

Figure 1 shows the X-ray diffraction measurement results for cyan toner CT1, and various data from the measurement results are shown in Table 4.

<Production Example of Cyan Toners CT2 to CT26>
Cyan toners CT2 to CT26 were obtained in the same manner as cyan toner CT1, except that the materials were changed to those shown in Table 4. Various data from the results of X-ray diffraction measurements are also shown.

<Production Example of Magnetic Carrier 1>
Magnetite 1 having a number average particle size of 0.30 μm (magnetization strength of 65 Am ² /kg under a magnetic field of 1000/4π (kA/m))
Magnetite 2 with a number average particle size of 0.50 μm (magnetization strength of 65 Am ² /kg under a magnetic field of 1000/4π (kA/m))
To 100 parts by mass of each of the above materials, 4.0 parts by mass of a silane compound (3-(2-aminoethylaminopropyl)trimethoxysilane) was added, and the mixture was mixed and stirred at high speed in a container at 100° C. or higher to treat each of the fine particles.
Phenol: 10% by mass
Formaldehyde solution: 6% by mass (40% by mass of formaldehyde, 10% by mass of methanol, 50% by mass of water)
Magnetite treated with the above silane compound 1: 58% by mass
Magnetite 2 treated with the above silane compound: 26% by mass
100 parts by mass of the above material, 5 parts by mass of a 28% by mass aqueous ammonia solution, and 20 parts by mass of water were placed in a flask, and the mixture was heated to 85°C over 30 minutes while stirring and mixing, and maintained at that temperature. A polymerization reaction was carried out for 3 hours, and the resulting phenolic resin was cured.

The hardened phenolic resin was then cooled to 30°C, and more water was added. The supernatant was then removed, and the precipitate was washed with water and air-dried.

This was then dried under reduced pressure (5 mmHg or less) at a temperature of 60°C to obtain spherical magnetic carrier 1 with dispersed magnetic material. The volume-based 50% particle size (D50) of magnetic carrier 1 was 34.2 μm.

<Production Example of Cyan Two-Component Developer CD1>
8.0 parts by weight of cyan toner CT1 was added to 92.0 parts by weight of magnetic carrier 1, and mixed in a V-type mixer (V-20, manufactured by Seishin Enterprises) to obtain two-component developer CD1.

<Cyan two-component developers CD2 to CD26>
Except for changing the toner shown in Table 5, the same production method as for the cyan two-component developer CD1 was carried out to obtain cyan two-component developers CD2 to CD26.

[Examples 1-21, Comparative Examples 1-5] Images obtained using each of the above developers were evaluated. The evaluation methods were as follows.

[Method for Evaluating Toner Tinting Power]
A modified full-color copying machine (product name: image RUNNER ADVANCE C5255) manufactured by Canon Inc. was used as the electrophotographic image forming apparatus, and a two-component developer was charged into the developing device of the cyan station, and evaluation was carried out.

The evaluation environment was a room temperature and humidity environment (23°C/50% RH), and the evaluation paper was plain copy paper (product name: GFC-081, A4 paper, basis weight: 81.4 g/ ^m2 , sold by Canon Marketing Japan Inc.), on which an unfixed toner image (toner loading amount 0.45 mg/ ^cm2 ) was formed. The unfixed image was fixed using a fixing unit removed from a commercially available full-color digital copier (image RUNNER ADVANCE C5255, manufactured by Canon). The image density of the resulting fixed image was measured using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite). The image density at this time was evaluated according to the following criteria:

(Evaluation Criteria for Cyan Toner)
A: 1.80 or more B: 1.70 or more but less than 1.80 C: 1.60 or more but less than 1.70 D: Less than 1.60

The evaluation results are shown in Table 6.

[Evaluation method for color stability]
A modified full-color copying machine (product name: image RUNNER ADVANCE C5255) manufactured by Canon Inc. was used as the electrophotographic image forming apparatus, and a two-component developer was charged into the developing device of the cyan station, and evaluation was carried out.

The evaluation environment was a low-temperature, low-humidity environment of 10° C. temperature and 15% relative humidity. The evaluation paper used was plain copy paper (product name: GFC-081, A4 paper, basis weight: 81.4 g/m ² , sold by Canon Marketing Japan Inc.).

A 16-level image was created by varying the amount of toner applied to the paper. The images were measured using a Spectro Scan Transmission (manufactured by Gretag Macbeth) (measurement conditions: D50, viewing angle 2°) to measure the L*, a*, and b* of the resulting image. Measurements were taken for L1*, a1*, and b1* at a toner application amount where C* = 85 on the L*-c* coordinate axis.

Next, the amount of toner applied when the image density of the FFH image (solid area) was 1.45 was determined, and the development bias was adjusted.

After adjusting the development bias, a fixed amount of toner was replenished to maintain a consistent toner density for an image with a print ratio of 1%, and 50,000 images (50k) were output.

After outputting 50,000 images, the toner amount on the paper was varied to form a 16-level image. The images were measured using a Spectro Scan Transmission (manufactured by Gretag Macbeth) (measurement conditions: D50, viewing angle 2°) to measure the L*, a*, and b* of the resulting images. Measurements were made by measuring L2*, a2*, and b2* at a toner amount where C*=85 on the L*-c* coordinate axis, and ΔE was calculated from the L*, a*, and b* values of the initial image and the image after outputting 50,000 images. The evaluation results are shown in Table 6.
ΔE={(L1*-L2*) ² + (a1*-a2*) ² + (b1*-b2*) ² } ^1/2
A: ΔE is less than 2.0 B: ΔE is 2.0 or more and less than 3.5 C: ΔE is 3.5 or more and less than 5.0 D: ΔE is 5.0 or more

Claims (9)

toner particles containing copper phthalocyanine and calcium carbonate particles ;
Inorganic fine particles ,
A cyan toner having
In powder X-ray diffraction measurement using the cyan toner as a sample, when the Bragg angle is θ, the peak intensity at 2θ (2θ±0.2°) of 9.0 to 9.4° is A and the peak intensity at 23.6 to 24.0° is B, the ratio B/A is 0.70 or more and 1.20 or less,
The cyan toner is characterized in that the inorganic fine particles have a volume resistivity of 2.0×10 ⁹ Ω·cm or more and 2.0×10 ¹² Ω·cm or less. 2. The cyan toner according to claim 1, wherein the toner particles contain the calcium carbonate particles in an amount of 1.0 part by mass or more and 15.0 parts by mass or less per 100 parts by mass of the total mass of the toner particles. The cyan toner according to claim 1 or 2, wherein the inorganic fine particles are titanium oxide particles or strontium titanate particles. The cyan toner according to any one of claims 1 to 3, wherein the inorganic fine particles are strontium titanate particles. The cyan toner according to claim 3 or 4, wherein the number-average particle size of the strontium titanate particles is 20 nm or more and 80 nm or less. 5. The cyan toner according to claim 4 , wherein the strontium titanate particles have a dielectric constant of 25.0 pF/m or more and 100.0 pF/m or less. The cyan toner according to any one of claims 1 to 6, wherein the toner particles contain crystalline polyester in an amount of 20% by mass or more and 170% by mass or less relative to the copper phthalocyanine. 8. The cyan toner according to claim 1 , wherein the cyan toner contains organosilicon polymer particles in an amount of 0.5 parts by weight to 5.0 parts by weight per 100 parts by weight of the toner particles. When X-ray diffraction measurement is performed on the toner using CuKα rays, the calcium carbonate particles have peaks at 26.5±0.1 and 29.5±0.1 in 2θ (2θ±0.2°) where θ is the Bragg angle in characteristic X-ray diffraction of CuKα,
the crystallite size of calcium carbonate calculated from a peak at 29.5±0.1° at 2θ (2θ±0.2°) when θ is the Bragg angle is 10 nm or more and 45 nm or less;
9. The cyan toner according to claim 1 , wherein the ratio of the peak intensity at 26.5±0.1 to the peak intensity at 29.5±0.1 is 0.11 or more and 0.24 or less.