JP7615567B2 - Toner set for developing electrostatic images, electrophotographic image forming method and electrophotographic image forming apparatus - Google Patents

Description

The present invention relates to a toner set for developing electrostatic images, an electrophotographic image forming method, and an electrophotographic image forming apparatus. More specifically, the present invention relates to a toner set for developing electrostatic images that can produce good images with an expanded color gamut in low-brightness areas and smooth gloss in medium-brightness areas.

In the field of print-on-demand printing, which has become increasingly popular in recent years due to the convenience and speed of data processing, there is an increasing demand for an expanded color gamut for the toners used to develop electrostatic images (hereinafter simply referred to as "toner") in order to provide printed products with higher customer satisfaction.

It is generally known that the color gamut of a toner can be expanded by increasing the colorant content in the toner particles or by increasing the dispersibility of the toner particles to obtain high saturation (see, for example, Patent Documents 1 and 2).

However, increasing the colorant content in the toner particles inevitably increases the amount of exposed colorant on the surface of the toner particles, resulting in an unstable chargeability of the toner and ultimately in the failure to form images with high stability.

In response to the above problem, a cyan toner for developing electrostatic images has been provided that provides excellent charging properties and is capable of producing a cyan color with high chroma (see, for example, Patent Document 3). However, the color gamut that can be output using only high chroma toner lacks low-lightness areas, and the low-lightness areas are supplemented with black toner. In such cases, the output product has a rough texture, and the gloss drops sharply with changes in gradation, making it unsatisfactory where the black toner is applied.

JP 2009-265227 A JP 2009-093161 A JP 2014-26066 A

The present invention was made in consideration of the above problems and circumstances, and the problem to be solved is to provide a toner set for developing electrostatic images, an electrophotographic image forming method, and an electrophotographic image forming apparatus that can obtain good images with an expanded color gamut in low-brightness areas and smooth gloss in medium-brightness areas.

In the course of investigating the causes of the above problems, the inventors discovered that the above problems could be solved by a toner set for developing electrostatic images that includes a first cyan toner and a second cyan toner that contain a specific compound, and thus arrived at the present invention.

In other words, the above problems of the present invention are solved by the following means.

〔式中、Ｚ_１、Ｚ_２ は、各々Ｒ ^１ 、Ｒ ^２ 、Ｒ ^３ が各々炭素数１～２２のアルキル基である一般式（ＩＶ）である。Ｒａ_１、Ｒａ_２、Ｒａ_３及びＲａ_４は、各々独立に、置換基を表す。ｎａ１、ｎａ２、ｎａ３及びｎａ４は、各々独立に、０～４の整数を表す。〕

〔式中、Ｒ ^１ 、Ｒ ^２ 及びＲ ^３ は、各々独立に、炭素数１～２２のアルキル基、炭素数６～１８のアリール基、炭素数１～２２のアルコキシ基、又は炭素数６～１８のアリールオキシ基を表す。なお、Ｒ ^１ 、Ｒ ^２ 及びＲ ^３ は、お互いに同じ基であっても、異なる基であってもよい。〕 1. A toner set for developing an electrostatic image, comprising at least two types of cyan toners,
The first cyan toner contains a silicon phthalocyanine compound having a structure represented by the following general formula (V),
A toner set for developing electrostatic images, wherein the second cyan toner contains a copper phthalocyanine compound.

[In the formula, Z ₁ and Z ₂ are general formula (IV) in which R ¹ , R ² and R ³ are each an alkyl group having 1 to 22 carbon atoms . Ra ₁ , Ra ₂ , Ra ₃ and Ra ₄ each independently represent a substituent. na1, na2, na3 and na4 each independently represent an integer of 0 to 4.]

[In the formula, R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 18 carbon atoms, an alkoxy group having 1 to 22 carbon atoms, or an aryloxy group having 6 to 18 carbon atoms. Note that R ¹ , R ² and R ³ may be the same group or different groups.]

2. The toner set for developing electrostatic images described in paragraph 1, characterized in that the difference in hue angle between the first cyan toner and the second cyan toner at a deposition amount of 3.4 gsm is 10° or more.

3. The toner set for developing electrostatic images according to paragraph 1 or 2, characterized in that the copper phthalocyanine compound has a neutral or basic substituent.

4. An electrophotographic image forming method having at least an image carrier charging step, an electrostatic image forming step, an electrostatic image developing step, a toner image transferring step, and a toner image fixing step,
4. An electrophotographic image forming method, comprising using the toner set for developing an electrostatic image according to any one of items 1 to 3.

5. An electrophotographic image forming apparatus comprising at least an image carrier charging means, an electrostatic image forming means, an electrostatic image developing means, a toner image transferring means, and a toner image fixing means,
4. An electrophotographic image forming apparatus, comprising the toner set for developing an electrostatic image according to any one of items 1 to 3.

The above-mentioned means of the present invention can provide a toner set for developing electrostatic images, an electrophotographic image forming method, and an electrophotographic image forming apparatus that can produce good images with an expanded color gamut in low-brightness areas and smooth gloss in medium-brightness areas.

Although the mechanism by which the effects of the present invention are expressed or acted upon has not been clarified, it is speculated as follows.

The present invention combines a high chroma cyan toner containing a compound having a structure represented by the general formula (I) with a cyan toner containing a conventional cyan pigment (copper phthalocyanine compound) as a toner set for developing electrostatic images, thereby making it possible to obtain an image in which the color gamut on the low brightness side is expanded by the copper phthalocyanine compound in addition to a high chroma image by the high chroma cyan toner in the cyan image area, and further to produce a toner set for developing electrostatic images that also enables CMYK printing.

In addition, conventionally, when a high chroma cyan toner was used, low brightness gradations were produced with black toner, resulting in a rapid loss of gloss and a lack of smoothness. However, by using a compound having a structure represented by the above general formula (I) together with a conventional cyan toner, it is possible to obtain better granularity than black toner, and furthermore, it is advantageous in that the binder resin in the cyan toner, which is not a binder resin for carbon black (CB), can increase gloss. Therefore, by using a conventional cyan toner in combination, it is possible to obtain a toner set for developing electrostatic images that can achieve gradations in the medium to low brightness range, between the high chroma cyan coloring produced by the silicon phthalocyanine compound and the black coloring, and smooth gloss.

FIG. 1 is a schematic diagram showing the structure of an electrophotographic image forming apparatus according to the present invention; Typical landscape images and CMYK manuscripts for each season used in the examples

The toner set for developing electrostatic images of the present invention is a toner set for developing electrostatic images that is composed of at least two kinds of cyan toners, and is characterized in that the first cyan toner contains a silicon phthalocyanine compound having a structure represented by the general formula ( V ) and the second cyan toner contains a copper phthalocyanine compound. This feature is a technical feature common to or corresponding to the following embodiments.

In one embodiment of the present invention, from the viewpoint of realizing the effect of the present invention, that is, a good image is obtained in terms of expanding the color gamut in the low lightness area and smoothing the gloss in the medium lightness area, it is preferable that the difference in hue angle between the first cyan toner and the second cyan toner at a deposition amount of 3.4 gsm is 10° or more.

The hue angle of the high chroma cyan toner containing a silicon phthalocyanine compound is in the range of approximately 210 to 220°, while the hue angle of the cyan toner containing a copper phthalocyanine compound, a conventional cyan pigment, is approximately 230 to 240°. Although both are cyan toners, this difference in hue angle is one of the features of the present invention.

The high chroma cyan toner containing a silicon phthalocyanine compound can develop a cyan color with a chroma C ^* of 56 to 61 in a hue angle range of 210 to 220° at a deposition amount of 3.4 gsm, thereby contributing to an expansion of the color gamut.

On the other hand, a cyan toner containing a copper phthalocyanine compound can develop a cyan color with a chroma C ^* of 60 to 70 in a hue angle range of 230 to 240° at a deposition amount of 3.4 gsm, and can therefore develop a cyan color on the low brightness side that has traditionally been expressed as a greenish color. By combining the cyan color development of the above two colors and linking these gradations, a toner set for developing electrostatic images can be created that can cover a color gamut that has not been able to be expressed before.

In addition, it is preferable that the copper phthalocyanine compound has a neutral or basic substituent, since this makes it easier to obtain the desired color gamut.

The electrophotographic image forming method (hereinafter also referred to as the image forming method) of the present invention is an electrophotographic image forming method having at least an image carrier charging step, an electrostatic image forming step, an electrostatic image developing step, a toner image transferring step, and a toner image fixing step, and is characterized by using the toner set for developing electrostatic images of the present invention.

The electrophotographic image forming apparatus of the present invention (hereinafter also referred to as an end-formation apparatus) is an electrophotographic image forming apparatus that includes at least an image carrier charging means, an electrostatic image forming means, an electrostatic image developing means, a toner image transfer means, and a toner image fixing means, and is characterized by using the toner set for developing electrostatic images of the present invention.

The present invention, its components, and the forms and modes for implementing the present invention are described in detail below. Note that in this application, "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

<<Outline of the toner set for developing electrostatic images of the present invention>>
The toner set for developing electrostatic images of the present invention is a toner set for developing electrostatic images composed of at least two kinds of cyan toners, characterized in that the first cyan toner contains a silicon phthalocyanine compound having a structure represented by the general formula ( V ) and the second cyan toner contains a copper phthalocyanine compound.

Here, the silicon phthalocyanine compound and copper phthalocyanine compound are generally referred to as "colorants," and "cyan toner" refers to a toner containing a colorant that develops a cyan color. Generally, a toner set for developing electrostatic images includes a set of toners containing colorants that develop cyan (C), magenta (M), yellow (Y), and black (Bk). The toner set for developing electrostatic images of the present invention is characterized in that it is equipped with a cyan toner that contains a specific compound as a colorant, together with toners that contain other colorants.

From the viewpoint of manifesting the effects of the present invention, it is preferable that the difference in hue angle between the first cyan toner and the second cyan toner when the adhesion amount is 3.4 gsm is 10 or more. Preferably, it is within the range of 10 to 25.

<Hue angle and saturation>
Using a commercially available full-color high-speed multifunction printer "bizhub PRO (registered trademark) C8000 (manufactured by Konica Minolta)," in an environment of 20°C temperature and 50% RH, an image (a solid image patch measuring 2 cm long x 2 cm wide) was fixed when the amount of toner attached to the paper was 3.4 gsm of cyan toner, and the color gamut was evaluated.

The transfer paper used in the evaluation is "POD gloss coated paper 128 g/m ² (manufactured by Oji Paper Co., Ltd.)." The fixing temperature is +10° C. from the minimum temperature.

The "L ^* a ^* b ^* color system" is used to calculate the hue angle and saturation. The L ^* axis indicates lightness, the a ^* axis indicates the hue in the red-green direction, and the b ^* axis indicates the hue in the yellow-blue direction. ^a* and b ^* are measured using a spectrophotometer "Gretag Macbeth Spectrolino" (manufactured by Gretag Macbeth) with a D50 light source as the light source, a measurement wavelength range of 380 to 730 nm at 10 nm intervals, a viewing angle of 2°, a UV-cut filter, and a dedicated white tile for reference alignment.

The hue angle h and chroma C ^* are calculated and evaluated according to the following formula.
h=tan-1(b ^* /a ^* )
C ^* = [(a ^* ) ² + (b ^* ) ² ] ^1/2

The toner for developing electrostatic images according to the present invention preferably contains toner base particles containing at least a binder resin and a colorant. In the present invention, the toner base particles to which an external additive has been added are referred to as toner particles, and an aggregate of toner particles is referred to as toner. Generally, the toner base particles can be used as they are as toner particles, but in the present invention, the toner base particles to which an external additive has been added are used as toner particles.

The toner base particles used in the present invention contain at least a binder resin and a silicon phthalocyanine compound and a copper phthalocyanine compound having the structure represented by the general formula (I) as colorants, and may also contain other components such as a release agent (wax) and a charge control agent, as necessary.

Hereinafter, the "toner for developing electrostatic images" according to the present invention will be simply referred to as "toner" in this specification.

[1] Toner set for developing electrostatic images The toner set for developing electrostatic images of the present invention is a toner set for developing electrostatic images that is composed of at least two types of cyan toners, in which the first cyan toner contains a silicon phthalocyanine compound having a structure represented by the following general formula (I), and the second cyan toner contains a copper phthalocyanine compound.

[1.1] First Cyan Toner The first cyan toner according to the present invention contains a silicon phthalocyanine compound having a structure represented by the following general formula (I).

[In the formula, _Z1 and _Z2 each independently represent a hydroxy group, a chlorine atom, an aryloxy group having 6 to 18 carbon atoms, an alkoxy group having 1 to 22 carbon atoms, or a group represented by the following general formula (IV). _Ra1 , _Ra2 , _Ra3 , and _Ra4 each independently represent a substituent. na1, na2, na3, and na4 each independently represent an integer of 0 to 4.]

In the general formula (I), Z ₁ and Z ₂ each independently represent a hydroxy group, a chlorine atom, an aryloxy group having 6 to 18 carbon atoms, an alkoxy group having 1 to 22 carbon atoms, or a group represented by the following general formula (IV). Ra ₁ , Ra ₂ , Ra ₃ , and Ra ₄ each independently represent a substituent, and na1, na1, na1, and na1 each independently represent an integer of 0 to 4. Preferred substituents represented by Ra ₁ , Ra ₂ , Ra ₃ , and Ra ₄ include an alkyl group (e.g., a methyl group, a trifluoromethyl group, an ethyl group, etc.), a halogen atom (e.g., F, Cl, Br, etc.), a sulfone group, etc. Particularly preferred substituents represented by _{Ra 1} , Ra ₂ , Ra ₃ , and Ra ₄ include a methyl group, a chlorine atom, a trifluoromethyl group, a sulfone group, etc. It is preferable that na1, na1, na1 and na1 are each independently 1 or 2.

[In the formula, R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 18 carbon atoms, an alkoxy group having 1 to 22 carbon atoms, or an aryloxy group having 6 to 18 carbon atoms. Note that R ¹ , R ² and R ³ may be the same group or different groups.]

R ¹ , R ² and R ³ represent an alkyl group, an aryl group, an alkoxy group or an aryloxy group having the above carbon numbers, and the carbon numbers of the alkyl group and the alkoxy group are preferably 1 to 10, more preferably 2 to 8. The carbon numbers of the aryl group and the aryloxy group are preferably 6 to 10, more preferably 6 to 8.

A preferred embodiment of the compound having the structure represented by formula (I) is a compound in which Z ₁ and Z ₂ each independently represent a group represented by formula (IV). It is also preferred that R ¹ , R ² and R ³ each represent a methyl group.

Furthermore, the compound having the structure represented by general formula (I) may form a dimer having the structure represented by the following general formula (II):

[In the formula, Z ₃ and Z ₄ each independently represent a hydroxy group, a chlorine atom, an aryloxy group having 6 to 18 carbon atoms, an alkoxy group having 1 to 22 carbon atoms, or a group represented by the above general formula (IV)]

The toner of the present invention contains a phthalocyanine compound having an axial ligand called a tetraazaporphine compound having a structure represented by the above general formula (I) in which a silicon atom is used as the central metal atom. Here, the axial ligand is represented by Z in the above general formula (I).

A toner containing a compound having a structure represented by general formula (I) exhibits better color reproducibility than a toner containing a phthalocyanine compound that does not have an axial ligand. This tendency is particularly pronounced in toners that use phthalocyanine compounds having a structure represented by general formula (I). This is presumably because the compound having a structure represented by general formula (I) has a more complex structure than a phthalocyanine compound that does not have an axial ligand, making it less likely for the compound to aggregate or crystallize. As a result, the colorant is uniformly dispersed in the toner particles and fixed images, which is presumably improving color reproducibility.

In addition, because the phthalocyanine compound has a structure that makes it less likely to aggregate or crystallize, its compatibility with the binder resin in the toner and its solubility in solvents or polymerizable monomers are improved, making it easier for the phthalocyanine compound to disperse uniformly during the toner manufacturing process, and it is believed that this results in good color reproducibility.

Furthermore, Z ₁ and Z ₂ constituting the compound having the structure represented by general formula (I) are preferably the group represented by general formula (IV) among the above-mentioned groups. R ¹ , R ² and R ³ in the group represented by general formula (IV) are preferably an alkyl group, an aryl group or an alkoxy group having 1 to 6 carbon atoms, and particularly preferably an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group or a t-butyl group. Furthermore, R ¹ , R ² and R ³ may be the same group or different groups.

In the present invention, the above phthalocyanine compounds can be used alone or in combination of two or more selected compounds. The content of the above phthalocyanine compounds in the toner is set within the range of 1 to 20% by mass, preferably 1 to 10% by mass, and more preferably 1 to 7% by mass, based on the total mass of the toner. In particular, the above compounds are expected to have high molecular absorptivity, so that even if they are added in small amounts, the effects of the present invention are expected to be achieved.

Specific examples of tetraazaporphine compounds (phthalocyanine compounds having an axial ligand) having the structure represented by general formula (I) are shown in the table below.

The compound having the structure represented by general formula (I) according to the present invention can be easily synthesized by known methods. For example, the contents described in the following patent specifications can be referred to. U.S. Pat. Nos. 5,428,152, 4,927,735, 5,021,563, 5,219,706, 5,034,309, 5,284,943, 5,075,203, 5,484,685, 5,039,600, 5,438,135, and 5,665,875.

[1.2] Second Cyan Toner The second cyan toner according to the present invention is characterized by containing a copper phthalocyanine compound.

As the copper phthalocyanine compound in the present invention, it is preferable to use an existing substituted copper phthalocyanine compound, but it is also preferable to use an unsubstituted copper phthalocyanine compound, since it is easier to obtain an image with a color in the desired color gamut (brightness and saturation).

In addition, it may contain only a substituted copper phthalocyanine compound, or it may contain both a substituted copper phthalocyanine compound and an unsubstituted copper phthalocyanine compound.

When a substituted copper phthalocyanine compound and an unsubstituted copper phthalocyanine compound are simultaneously contained, the substituted copper phthalocyanine compound becomes a part that disrupts the crystal structure of the copper phthalocyanine compound, and it becomes easier to reduce the primary particle size and control the particle size distribution when producing primary particles of the colorant (copper phthalocyanine compound) by solvent salt milling, which will be described later, and therefore it is preferable because it is easier to control the coloring power, color reproducibility, etc.

In addition, by containing a substituted copper phthalocyanine compound, the compatibility with the binder resin is improved due to the substituent (functional group) of the substituted copper phthalocyanine compound, and the compound is easily incorporated into the binder resin (the dispersibility of the cyan pigment (colorant) in the entire toner is improved). This is also advantageous.
In addition, the term "unsubstituted" as used herein means that the hydrogen atoms on the copper phthalocyanine skeleton are not substituted with a substituent. The term "substituted" means that the hydrogen atoms on the copper phthalocyanine skeleton are substituted with a substituent. In the case of "substitution", it is preferable that the substituted copper phthalocyanine compound has a neutral or basic substituent.

The unsubstituted copper phthalocyanine compound may have α, β, ε, or other crystal types, and in the present invention, the β type is preferred in terms of hue, color development, stability, and dispersibility. Specifically, examples of the β type include C.I. Pigment Blue 15:3 and C.I. Pigment Blue 15:4, examples of the α type include C.I. Pigment Blue 15, C.I. Pigment Blue 15:1, and C.I. Pigment Blue 15:2, and examples of the ε type include C.I. Pigment Blue 15:6.

The substituted copper phthalocyanine compound preferably has a structure represented by the following general formula (a) or (b):

P-(Y) _m ...(a)
P-(A-Z) _n ...(b)
[In the formula, P represents a residue obtained by removing n hydrogen atoms from a copper phthalocyanine ring. Y represents a primary to tertiary amino group, a carboxy group, a sulfonic acid group, or a salt thereof with a base or a metal. represents a divalent linking group. Z represents a residue obtained by removing at least one hydrogen atom on a nitrogen atom of a primary or secondary amino group, or at least one hydrogen atom on a nitrogen-containing heterocycle. m represents an integer of 1 to 4, and n represents an integer of 1 to 4.

Examples of the secondary and tertiary amino groups include a monomethylamino group, a dimethylamino group, a diethylamino group, etc., and examples of the base or metal that forms a salt with the carboxy group or sulfonic acid group include organic bases such as ammonia, dimethylamine, diethylamine, triethylamine, etc., and metals such as potassium, sodium, calcium, strontium, aluminum, etc. Examples of the divalent linking group for A include an alkylene group having 1 to 3 carbon atoms, -CO ₂ -, -SO ₂ -, -SO ₂ NH(CH ₂ ) _m -, etc., and examples of Z include a phthalimido group, a monoalkylamino group, a dialkylamino group, etc.

Among these, the substituted copper phthalocyanine compound is preferably substituted with a basic substituent (such as an amino group) because this generates an interaction between the basic substituent and the acid group and ester group of the crystalline polyester resin, improving the controllability of the chargeability.

The number-average major axis of the primary particles of the copper phthalocyanine compound in the toner is preferably within a range of 70 to 220 nm, more preferably within a range of 80 to 200 nm, and particularly preferably within a range of 130 to 170 nm.

When the number-average major axis of the primary particles of the copper phthalocyanine compound in the toner is 70 nm or more, aggregation of the colorant particles during toner production can be more reliably suppressed, coloring power is stronger, and light resistance is improved, which is preferable. In addition, when the average major axis is 220 nm or less, the hue angle can be prevented from becoming excessively blue, and the contact area between the colorant particles and the binder resin is increased, so that when a crystalline polyester resin is used as the binder resin, the chargeability, which is thought to be due to a change in the domain structure of the crystalline polyester resin, can be reliably controlled, which is preferable.

The content of the copper phthalocyanine compound in the toner is preferably within the range of 1.0 to 4.0% by mass, more preferably 2.0 to 3.8% by mass, and particularly preferably less than 3.6% by mass.

By keeping the content of the copper phthalocyanine compound in the toner within the range of 1.0 to 4.0% by mass, the content can be reduced without compromising coloring power even at small amounts. Furthermore, by using such a small amount, the inherent properties of the resin in the toner can be utilized, and even with the same resin composition, low-temperature fixing can be achieved by using the copper phthalocyanine compound.

Here, any known and commonly used manufacturing method can be used as the method for producing the copper phthalocyanine compound.

(Method for producing copper phthalocyanine compound)
As a method for producing a copper phthalocyanine compound, for example, a method called the Wyler method in which phthalic anhydride, urea and a metal salt are reacted to synthesize a metal phthalocyanine, or a method called the phthalonitrile method in which phthalonitrile and a metal salt are reacted to synthesize a metal phthalocyanine can be used.

It is also possible to use a method of synthesizing metal phthalocyanine by reacting phthalic anhydride, urea, and a metal salt in the presence of trimellitic acid, pyromellitic acid, or derivatives thereof such as anhydrides, imides, and esters (see JP-A-61-203175), or a method of synthesizing metal phthalocyanine by using a paraffinic hydrocarbon solvent in combination with a naphthenic hydrocarbon solvent (see JP-A-8-27388).

In another embodiment of the method for producing a copper phthalocyanine compound, the copper phthalocyanine compound is prepared by purifying a crude pigment. In other words, the copper phthalocyanine compound can be obtained by subjecting the crude pigment to a pigmentation treatment. There are no particular limitations on the pigmentation treatment method, and various pigmentation treatment methods can be used. However, it is preferable to use a solvent salt milling treatment, which suppresses significant crystal growth and makes it easier to control the aspect ratio of the copper phthalocyanine compound than a solvent treatment in which the crude pigment is heated and stirred in a large amount of organic solvent.

Solvent salt milling refers to the kneading and grinding of a crude pigment, an inorganic salt, and an organic solvent. Specifically, the crude pigment, the inorganic salt, and an organic solvent that does not dissolve them are charged into a kneading machine, and kneading and grinding are carried out in the kneading machine. For example, a kneader or a mixer can be used as the kneading machine.

As the inorganic salt, a water-soluble inorganic salt can be suitably used, and it is preferable to use inorganic salts such as sodium chloride, potassium chloride, and sodium sulfate. It is more preferable to use inorganic salts with an average particle size in the range of 0.5 to 50 μm. Such inorganic salts can be easily obtained by finely grinding ordinary inorganic salts.

The amount of inorganic salt used is preferably in the range of 6 to 20 parts by weight, and more preferably in the range of 8 to 15 parts by weight, per 1 part by weight of crude pigment.

As the organic solvent, a water-soluble organic solvent that can suppress crystal growth can be suitably used, such as diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2-(methoxymethoxy)ethanol, 2-butoxyethanol, 2-(isopentyloxy)ethanol, 2-(hexyloxy)ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol, etc.

The amount of the water-soluble organic solvent used is not particularly limited, but is preferably 0.01 to 15 parts by weight per 1 part by weight of the crude pigment.

When obtaining the copper phthalocyanine compound used in the present invention, only the crude pigment of the unsubstituted copper phthalocyanine compound may be subjected to solvent salt milling, or the crude pigment of the unsubstituted copper phthalocyanine compound may be used in combination with the substituted copper phthalocyanine compound and subjected to solvent salt milling.

The copper phthalocyanine compound obtained by solvent salt milling a crude pigment of an unsubstituted copper phthalocyanine compound in combination with a substituted copper phthalocyanine compound is a copper phthalocyanine compound containing an unsubstituted copper phthalocyanine compound and a substituted copper phthalocyanine compound. It is preferable that the overall composition including the unsubstituted copper phthalocyanine compound and the substituted copper phthalocyanine compound is within the following average aspect ratio range. Here, "average aspect ratio" refers to the ratio (Db/Da) of the number average major axis Db to the number average minor axis Da of the primary particles of the copper phthalocyanine compound.

In the present invention, the average aspect ratio is preferably within the range of 3.0 to 6.0. By having the average aspect ratio of 3.0 or more, even if the primary particle size is small, it is possible for the colorant particles to exist in a dispersed state in the raw colorant particle dispersion liquid and in the toner, and sufficient coloring power can be obtained with a small colorant content, resulting in a toner with high saturation. Furthermore, by having the average aspect ratio of 6.0 or less, it is possible to prevent the hue angle from becoming excessively blue, resulting in a toner that can ensure images of colors in the desired color gamut (brightness and saturation).

From the viewpoint of improving the coloring power of the toner, the average aspect ratio of the primary particles of the copper phthalocyanine compound in the toner is preferably within the range of 3.0 to 5.0, and more preferably within the range of 3.5 to 4.5.

The average aspect ratio can be controlled to be within the range of 3.0 to 6.0 by controlling the type of solvent, temperature, precipitation rate, dispersion, and other conditions during crystallization in the manufacturing process of the copper phthalocyanine compound.

The amount of substituted copper phthalocyanine compound that can be included in the crude pigment during solvent salt milling is usually within the range of 0.01 to 0.3 parts by mass per part by mass of the crude pigment. By adjusting the content of the substituted copper phthalocyanine compound, the average aspect ratio and the axis length of the primary particles can be controlled. For example, the greater the content of the substituted copper phthalocyanine compound, the shorter the length of the major axis and the smaller the average aspect ratio.

The temperature during solvent salt milling is preferably in the range of 30 to 150°C, more preferably in the range of 50 to 100°C, and particularly preferably in the range of 60 to 95°C. The time for solvent salt milling is preferably 5 to 20 hours, and more preferably 5 to 18 hours.

When all conditions other than the kneading time during solvent salt milling are kept constant, the aspect ratio and axis length can be controlled by adjusting the kneading time. Specifically, the longer the kneading time, the shorter the major axis length and the smaller the average aspect ratio.

[1.3] Binder Resin The binder resin constituting the toner according to the present invention preferably contains an amorphous resin and a crystalline polyester resin.

(Crystalline polyester resin)
The crystalline polyester resin is a known polyester resin obtained by polycondensation reaction of a divalent or higher carboxylic acid (polyvalent carboxylic acid component) and/or a hydroxycarboxylic acid with a divalent or higher alcohol (polyhydric alcohol component), and has a clear melting peak in differential scanning calorimetry (DSC) instead of a stepwise change in endothermic heat. Specifically, the clear melting peak means a peak whose half-width in the second heating process is within 15°C in the DSC curve obtained by differential scanning calorimetry of the above-mentioned crystalline polyester resin alone.

The melting point of the crystalline polyester resin is preferably within the range of 65 to 85°C, and more preferably within the range of 75 to 85°C. By having the melting point of the crystalline polyester resin within the above range, sufficient low-temperature fixing properties and excellent image storage properties can be obtained. The melting point of the crystalline polyester resin can be controlled by the resin composition. Here, the melting point of the crystalline polyester resin is the peak top temperature of the melting peak in the second heating process in the DSC curve obtained by differential scanning calorimetry of the above-mentioned crystalline polyester resin alone. In addition, when there are multiple melting peaks in the DSC curve, the peak top temperature of the melting peak with the largest amount of heat absorption is taken as the melting point.

The melting point (Tm) of the crystalline polyester resin is the temperature at the top of the endothermic peak, and can be measured by DSC using a Diamond DSC (manufactured by PerkinElmer). Specifically, the sample is sealed in an aluminum pan KIT No. B0143013 and set in the sample holder of a thermal analysis device Diamond DSC (manufactured by PerkinElmer), and the temperature is changed in the order of heating, cooling, and heating. In the first heating, the temperature is raised from room temperature (25°C) and in the second heating, from 0°C at a heating rate of 10°C/min to 150°C, and 150°C is held for 5 minutes. In the cooling, the temperature is lowered from 150°C to 0°C at a heating rate of 10°C/min and the temperature is held at 0°C for 5 minutes. The temperature at the top of the endothermic peak in the endothermic curve obtained in the second heating is measured as the melting point.

The polycarboxylic acid component for forming the crystalline polyester resin is a compound containing two or more carboxy groups in one molecule. Specific examples include saturated aliphatic dicarboxylic acids such as succinic acid, sebacic acid, and dodecanedioic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; trivalent or higher polycarboxylic acids such as trimellitic acid and pyromellitic acid; and anhydrides or alkyl esters having 1 to 3 carbon atoms of these carboxylic acid compounds. As the polycarboxylic acid component for forming the crystalline polyester resin, it is preferable to use saturated aliphatic dicarboxylic acids. These may be used alone or in combination of two or more.

The polyhydric alcohol component for forming the crystalline polyester resin is a compound containing two or more hydroxyl groups in one molecule. Specific examples include aliphatic diols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, neopentyl glycol, and 1,4-butenediol; and trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol. It is preferable to use an aliphatic diol as the polyhydric alcohol component for forming the crystalline polyester resin. These may be used alone or in combination of two or more.

There are no particular limitations on the method for producing the crystalline polyester resin, and it can be produced using a general polyester polymerization method in which the above-mentioned polycarboxylic acid and polyhydric alcohol are reacted in the presence of a catalyst. For example, it is preferable to produce it by using direct polycondensation or ester exchange depending on the type of monomer.

In addition, linear aliphatic hydroxycarboxylic acids can be used in combination with the polyvalent carboxylic acids and/or polyhydric alcohols. Examples of linear aliphatic hydroxycarboxylic acids for forming crystalline polyester resins include 5-hydroxypentanoic acid, 6-hydroxyhexanoic acid, 7-hydroxypentanoic acid, 8-hydroxyoctanoic acid, 9-hydroxynonanoic acid, 10-hydroxydecanoic acid, 12-hydroxydodecanoic acid, 14-hydroxytetradecanoic acid, 16-hydroxyhexadecanoic acid, 18-hydroxyoctadecanoic acid, and lactone compounds cyclized from these hydroxycarboxylic acids, or alkyl esters with alcohols having 1 to 3 carbon atoms. These may be used alone or in combination of two or more.

In addition, when forming the crystalline polyester resin, using polycarboxylic acid and polyhydric alcohol components makes it easier to control the reaction, and is therefore preferable because it makes it possible to obtain a resin with the desired molecular weight.

Catalysts that can be used in the production of crystalline polyester resins include, for example, titanium catalysts such as titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, and titanium tetrabutoxide, and tin catalysts such as dibutyltin dichloride, dibutyltin oxide, and diphenyltin oxide.

The ratio of the polycarboxylic acid component and the polyhydric alcohol component used is preferably such that the equivalent ratio [OH]/[COOH] of the hydroxyl group [OH] of the polyhydric alcohol component to the carboxyl group [COOH] of the polycarboxylic acid component is within the range of 1.5/1 to 1/1.5, and more preferably 1.2/1 to 1/1.2.

The acid value of the crystalline polyester resin is preferably within the range of 5 to 30 mgKOH/g, more preferably 10 to 25 mgKOH/g, and even more preferably 15 to 25 mgKOH/g. This acid value is the mass of potassium hydroxide (KOH) required to neutralize the acid contained in 1 g of the sample, expressed in mg units. The acid value of the resin is measured according to the following procedure in accordance with JIS K0070-1992.

(Preparation of Reagents)
Dissolve 1.0 g of phenolphthalein in 90 mL of ethyl alcohol (95% by volume), add ion-exchanged water to make 100 mL, and prepare a phenolphthalein solution. Dissolve 7 g of JIS special grade potassium hydroxide in 5 mL of ion-exchanged water, and add ethyl alcohol (95% by volume) to make 1 liter. Place in an alkali-resistant container to avoid contact with carbon dioxide, leave for 3 days, and then filter to prepare a potassium hydroxide solution. Standardization follows the description of JIS K0070-1992.

(Main test)
2.0 g of the crushed sample is accurately weighed into a 200 mL Erlenmeyer flask, and 100 mL of a mixed solution of toluene/ethanol (toluene:ethanol volume ratio 2:1) is added and dissolved over 5 hours. Next, several drops of the prepared phenolphthalein solution are added as an indicator, and titration is performed using the prepared potassium hydroxide solution. The end point of the titration is when the light red color of the indicator continues for about 30 seconds.

(Blank test)
The same procedure as in the main test described above is carried out, except that no sample is used (i.e., only a mixed solution of toluene/ethanol (toluene:ethanol in a volume ratio of 2:1) is used).

The titration results from this test and the blank test are substituted into the following formula (1) to calculate the acid value.

Formula (1) A=[(CB)×f×5.6]/S
A: Acid value (mgKOH/g)
B: Amount of potassium hydroxide solution added during blank test (mL)
C: Amount of potassium hydroxide solution added during this test (mL)
f: factor of 0.1 mol/L potassium hydroxide ethanol solution S: mass of sample (g)

The molecular weight of the crystalline polyester resin is preferably such that the weight average molecular weight (Mw) is within the range of 5,000 to 50,000 and the number average molecular weight (Mn) is within the range of 1,500 to 25,000, calculated from the molecular weight distribution measured by gel permeation chromatography (GPC).

Molecular weight measurement by GPC is carried out as follows:

That is, using the apparatus "HLC-8320" (manufactured by Tosoh Corporation) and columns "TSKgel guardcolumn SuperHZ-L" and "TSKgel SuperHZM-M" (manufactured by Tosoh Corporation), tetrahydrofuran (THF) is passed as a carrier solvent at a flow rate of 0.2 ml/min while maintaining the column temperature at 40°C. The measurement sample (crystalline polyester resin) is dissolved in tetrahydrofuran to a concentration of 1 mg/ml under dissolution conditions of processing for 5 minutes using an ultrasonic disperser at room temperature, and then processed with a membrane filter with a pore size of 0.2 μm to obtain a sample solution. 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent, detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample is calculated using a calibration curve measured using monodisperse polystyrene standard particles.

The standard polystyrene samples used for measuring the calibration curve were manufactured by Pressure Chemical Co. and had molecular weights of 6 x ¹⁰² , 2.1 x ¹⁰³ , 4 x ¹⁰³ , 1.75 x ¹⁰⁴ , 5.1 x ¹⁰⁴ , 1.1 x ¹⁰⁵ , 3.9 x ¹⁰⁵ , 8.6 x ¹⁰⁵ , 2 x ¹⁰⁶ , and 4.48 x ^106. At least 10 standard polystyrene samples were measured to create a calibration curve.

The content of the crystalline polyester resin in the binder resin is preferably within the range of 5 to 20% by mass, and more preferably within the range of 5 to 10% by mass. By having the content of the crystalline polyester resin in the binder resin be 5% by mass or more, sufficient low-temperature fixing properties can be reliably obtained. Furthermore, by having the content of the crystalline polyester resin in the binder resin be 20% by mass or less, the crystalline polyester resin can be reliably introduced into the toner during toner production.

As the crystalline polyester resin, a styrene-acrylic modified crystalline polyester resin formed by combining a styrene-acrylic polymerized segment with a crystalline polyester polymerized segment may be used.

Here, "styrene-acrylic modified crystalline polyester resin" refers to a resin composed of polyester molecules with a block copolymer structure, in which a styrene-acrylic copolymer molecular chain (styrene-acrylic polymerization segment) is chemically bonded to a crystalline polyester molecular chain (crystalline polyester polymerization segment).

The method for forming the crystalline polyester polymerized segment is not particularly limited. The specific types of polyvalent carboxylic acid and polyhydric alcohol used in forming the polymerized segment and the polycondensation conditions of these monomers are the same as those described above, so a description thereof will be omitted here.

On the other hand, the styrene-acrylic polymerized segment constituting the styrene-acrylic modified crystalline polyester resin is formed by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer. The styrene monomer and (meth)acrylic acid ester monomer used are not particularly limited, but for example, one or more types selected from the following may be used.

(1) Styrene Monomers: Styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene, and derivatives thereof;
(2) (meth)acrylic acid ester monomers: methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate (n-butyl (meth)acrylate), isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-stearyl (meth)acrylate, dodecyl (meth)acrylate, phenyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and derivatives thereof;
In this specification, the term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

The styrene-acrylic polymerized segment may be formed using the following monomers in addition to the above monomers:

(3) Vinyl esters: vinyl propionate, vinyl acetate, vinyl benzoate, and the like;
(4) Vinyl ethers such as vinyl methyl ether and vinyl ethyl ether;
(5) Vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl hexyl ketone;
(6) N-vinyl compounds such as N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone;
(7) Other Monomers Vinyl compounds such as vinylnaphthalene and vinylpyridine, acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide, and the like.

The method for forming the styrene-acrylic polymerized segment is not particularly limited, and examples of the method include a method in which polymerization is carried out by a known polymerization method such as bulk polymerization, solution polymerization, emulsion polymerization, mini-emulsion, or dispersion polymerization using any polymerization initiator that is commonly used in the polymerization of the above monomers, such as peroxides, persulfides, persulfates, or azo compounds.

The content of the crystalline polyester polymerized segment in the styrene-acrylic modified crystalline polyester resin is not particularly limited, but is preferably within the range of 60 to 99% by mass, and more preferably within the range of 70 to 98% by mass, relative to 100% by mass of the styrene-acrylic modified polyester resin.

The content ratio of styrene-acrylic polymerized segments in the styrene-acrylic modified crystalline polyester resin (hereinafter also referred to as "styrene-acrylic modification amount") is not particularly limited, but is preferably within the range of 1 to 40% by mass, and more preferably within the range of 2 to 30% by mass, relative to 100% by mass of the styrene-acrylic modified crystalline polyester resin.

The amount of styrene-acrylic modification specifically refers to the ratio of the total mass of the styrene monomer and (meth)acrylic ester monomer to the total mass of the resin material used to synthesize the styrene-acrylic modified crystalline polyester resin, that is, the total mass of the monomers used to synthesize the unmodified crystalline polyester resin that becomes the crystalline polyester polymerization segment, the styrene monomer and (meth)acrylic ester monomer that become the styrene-acrylic polymerization segment, and the bireactive monomers that bond these together.

Here, the "bireactive monomer" is a monomer that bonds a styrene-acrylic polymerization segment with a crystalline polyester polymerization segment, and has in its molecule both a group selected from a hydroxy group, a carboxy group, an epoxy group, a primary amino group, and a secondary amino group that forms a crystalline polyester polymerization segment, and an ethylenically unsaturated group that forms a styrene-acrylic polymerization segment.

Specific examples of bireactive monomers include acrylic acid, methacrylic acid, fumaric acid, maleic acid, etc., and may further be esters of these hydroxyalkyls (having 1 to 3 carbon atoms), but from the viewpoint of reactivity, acrylic acid, methacrylic acid, or fumaric acid is preferred. The styrene-acrylic polymerized segment and the crystalline polyester polymerized segment are bonded via this bireactive monomer.

From the viewpoint of improving low-temperature fixability, the amount of the bireactive monomer used is preferably within the range of 1 to 20% by mass, with the total amount of the monomers constituting the styrene-acrylic polymerized segment being 100% by mass.

There are no particular limitations on the method for producing the styrene-acrylic modified crystalline polyester resin, so long as it is a method capable of forming a polymer having a structure in which a crystalline polyester polymerized segment and a styrene-acrylic polymerized segment are chemically bonded. Specific examples of the method for producing the styrene-acrylic modified crystalline polyester resin include the methods shown below.

(A) A method of forming a styrene-acrylic polymerization segment by polymerizing a crystalline polyester polymerization segment in advance, reacting the crystalline polyester polymerization segment with a bireactive monomer, and further reacting the styrene monomer and the (meth)acrylic acid ester monomer for forming a styrene-acrylic polymerization segment;
(B) A method of forming a crystalline polyester polymer segment by polymerizing a styrene-acrylic polymer segment in advance, reacting the styrene-acrylic polymer segment with a bireactive monomer, and further reacting the styrene-acrylic polymer segment with a polyvalent carboxylic acid and a polyhydric alcohol for forming a crystalline polyester polymer segment;
(C) A method in which a crystalline polyester polymer segment and a styrene-acrylic polymer segment are polymerized in advance, and then reacted with a bireactive monomer to bond the two together.

Among the above forming methods (A) to (C), method (A) is preferred from the viewpoint of simplifying the production process, etc.

<Amorphous resin>
In the present invention, the amorphous resin may be an amorphous polyester resin or an amorphous vinyl resin.

Amorphous resins are those that do not show a clear endothermic peak in differential scanning calorimetry (DSC). In other words, they usually do not have a melting point (a clear endothermic peak in a DSC curve measured using a differential scanning calorimetry (DSC) measuring device) and have a relatively high glass transition point (Tg). More specifically, the Tg of the amorphous resin measured using a differential scanning calorimetry device is preferably in the range of 35 to 70°C, and more preferably in the range of 50 to 65°C. By having the Tg of the amorphous resin be 35°C or higher, it is possible to impart sufficient thermal strength to the toner, and sufficient heat-resistant storage properties can be obtained. Furthermore, by having the Tg of the amorphous resin be 70°C or lower, sufficient low-temperature fixability can be reliably obtained.

The Tg of the amorphous resin is measured by the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-82. That is, 4.5 mg of the measurement sample (amorphous resin) is weighed out to two decimal places, sealed in an aluminum pan, and set in the sample holder of a differential scanning calorimeter "DSC8500" (manufactured by PerkinElmer). An empty aluminum pan is used as a reference, and temperature control is performed with a measurement temperature of -10 to 120°C, a heating rate of 10°C/min, and a cooling rate of 10°C/min, with heating-cooling-heating, and analysis is performed based on the data from the second heating. The value of the intersection between the extension line of the baseline before the rise of the first endothermic peak and the tangent line showing the maximum slope from the rising part of the first endothermic peak to the peak apex is taken as the glass transition point.

The molecular weight of the amorphous resin measured by gel permeation chromatography (GPC) is preferably within the range of a number average molecular weight (Mn) of 1,500 to 25,000 and a weight average molecular weight (Mw) of 10,000 to 80,000. By having the molecular weight of the amorphous resin within the above range, sufficient low-temperature fixability and excellent heat-resistant storage stability can be reliably achieved. The molecular weight measurement of the amorphous resin by GPC is performed in the same manner as above, except that an amorphous resin is used as the measurement sample.

(Amorphous polyester resin)
The amorphous polyester resin is a polyester resin other than the crystalline polyester resin.

The acid value of the amorphous polyester resin is preferably in the range of 5 to 45 mgKOH/g, and more preferably in the range of 5 to 30 mgKOH/g. If the acid value is 45 mgKOH/g or less, it is preferable because it does not become highly hygroscopic and can prevent the chargeability from decreasing even under high humidity. If the acid value is 5 mgKOH/g or more, it is preferable because it can maintain the dispersion stability of the resin particles and facilitate toner production. The acid value can be determined in the same manner as described in the explanation of the crystalline polyester resin.

The amorphous polyester resin may be one type of amorphous polyester resin, or a mixture of two or more types of amorphous polyester resins.

As the amorphous polyester resin, a known polyester resin can be used. The amorphous polyester resin is synthesized from a polyvalent carboxylic acid component and a polyhydric alcohol component. The amorphous polyester resin may be a commercially available product or may be synthesized.

Examples of polyhydric alcohol components that can be used include diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, BPA-PO (n moles of propylene oxide adduct of bisphenol A), and BPA-EO (n moles of ethylene oxide adduct of bisphenol A). In addition, trihydric or higher alcohols such as glycerin, sorbitol, 1,4-sorbitan, and trimethylolpropane can be used. Among these, bisphenol A, hydrogenated bisphenol A, BPA-PO or BPA-EO is preferable, BPA-PO or BPA-EO is more preferable, and a propylene oxide 2-mol adduct of bisphenol A or an ethylene oxide 2-mol adduct of bisphenol A is even more preferable. These may be used alone or in combination of two or more kinds.

Examples of polycarboxylic acid components include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; aliphatic saturated dicarboxylic acids such as succinic acid, alkenylsuccinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; aliphatic unsaturated dicarboxylic acids such as maleic acid, maleic acid, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic acid, and mesaconic acid; alicyclic polycarboxylic acids such as cyclohexanedicarboxylic acid; salts, lower alkyl esters, and acid anhydrides thereof. Among these, aromatic dicarboxylic acids, salts, lower alkyl esters, and acid anhydrides thereof are preferred, and terephthalic acid, phthalic acid, salts, lower alkyl esters, and acid anhydrides thereof are more preferred. These polycarboxylic acid components may be used alone or in combination of two or more.

By including a trivalent or higher carboxylic acid as the polyvalent carboxylic acid component, the polymer chain can have a crosslinked structure, and by having this crosslinked structure, the crystalline polyester resin that has once become compatible with the amorphous polyester resin can be fixed, further providing the effect of making it difficult to separate.

Examples of trivalent or higher carboxylic acids include trimellitic acids such as 1,2,4-benzenetricarboxylic acid and 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, hemimellitic acid, trimesic acid, mellophanic acid, prenic acid, pyromellitic acid, mellitic acid, 1,2,3,4-butanetetracarboxylic acid, their salts, lower alkyl esters and acid anhydrides, etc., with trimellitic acid, its salts, lower alkyl esters and acid anhydrides being particularly preferred.

When the polycarboxylic acid component contains a dicarboxylic acid and a trivalent or higher carboxylic acid, the amount of the trivalent or higher carboxylic acid added is preferably within the range of 1 to 30 mol%, more preferably within the range of 5 to 20 mol%, and more preferably within the range of 10 to 15 mol%, based on the total number of moles of the polycarboxylic acid component.

In addition to the above-mentioned compounds, the polycarboxylic acid component may also include a dicarboxylic acid component having a sulfonic acid group.

The production of amorphous polyester resin is not particularly limited, but is preferably carried out by a polycondensation reaction between a polycarboxylic acid component and a polyhydric alcohol component at a polymerization temperature of 180 to 260°C, and if necessary, reducing the pressure in the reaction system and removing water and alcohol generated during condensation while carrying out the reaction. The polymerization time is not particularly limited, but is preferably 1 to 10 hours, and more preferably 2 to 6 hours.

If the polymerizable monomers (polycarboxylic acid component, polyhydric alcohol component) are not soluble or compatible at the reaction temperature, a high-boiling point solvent may be added as a solubilizing agent to dissolve them. The polycondensation reaction is carried out while distilling off the solubilizing agent. If a polymerizable monomer with poor compatibility is present in the copolymerization reaction, it is advisable to first condense the poorly compatible polymerizable monomer with the acid or alcohol to be polycondensed, and then polycondense with the main component.

Catalysts that can be used in the production of amorphous polyester resins include, for example, alkali metal compounds containing sodium, lithium, etc.; Group 2 metal compounds containing magnesium, calcium, etc.; metal compounds containing zinc, manganese, antimony, titanium, tin, zirconium, germanium, etc.; phosphorous compounds; phosphate compounds; and amine compounds. These may be used alone or in combination of two or more. Among these, from the viewpoint of reducing Mw/Mn, metal compounds containing zinc, manganese, antimony, titanium, tin, zirconium, germanium, etc. are preferred, and metal compounds of tin (tin-based catalysts) are more preferred. Tin-based catalysts are not particularly limited, but examples include dibutyltin oxide, etc.

The amount of catalyst added is not particularly limited, but is preferably within the range of 0.00001 to 10% by mass based on the total amount of polycarboxylic acid. Increasing the amount of catalyst added allows the reaction to proceed more reliably, while decreasing the amount of catalyst added is more economical.

The content of the amorphous polyester resin is preferably 5 to 30% by mass of the total binder resin, and more preferably 5 to 20% by mass. In this range, the resulting toner has excellent blocking resistance and low-temperature fixability.

(Amorphous vinyl resin)
The amorphous vinyl resin is not particularly limited as long as it is a polymer of a vinyl compound, and examples thereof include acrylic acid ester resin, styrene-(meth)acrylic acid ester resin, ethylene-vinyl acetate resin, etc. These may be used alone or in combination of two or more.

Among the above amorphous vinyl resins, styrene-(meth)acrylic acid ester resin (hereinafter also referred to as "styrene-acrylic resin") is preferred, taking into consideration the plasticity during thermal fixing. Therefore, styrene-acrylic resin as an amorphous vinyl resin will be described below.

Styrene-acrylic resin is formed by addition polymerization of at least a styrene monomer and a (meth)acrylic acid ester monomer. The styrene monomer referred to here includes styrene represented by the structural formula CH ₂ ═CH-C ₆ H ₅ , as well as those having a structure with a known side chain or functional group in the styrene structure. The (meth)acrylic acid ester monomer referred to here includes acrylic acid ester and methacrylic acid ester represented by the structural formula CH ₂ ═CHCOOR (R is an alkyl group), as well as esters having a known side chain or functional group in the structure of acrylic acid ester derivatives, methacrylic acid ester derivatives, etc.

Specific examples of styrene monomers and (meth)acrylic acid ester monomers capable of forming styrene-acrylic resins are shown below, but the monomers used in the present invention are not limited to the following.

Specific examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, and p-n-dodecylstyrene. These styrene monomers can be used alone or in combination of two or more.

Specific examples of (meth)acrylic acid ester monomers include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, tert-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid ester monomers such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate. These acrylic acid ester monomers or methacrylic acid ester monomers can be used alone or in combination of two or more. That is, it is possible to form a copolymer using a styrene monomer and two or more acrylic acid ester monomers, to form a copolymer using a styrene monomer and two or more methacrylic acid ester monomers, or to form a copolymer using a styrene monomer in combination with an acrylic acid ester monomer and a methacrylic acid ester monomer.

The content of structural units derived from styrene monomers in the styrene-acrylic resin is preferably within the range of 60 to 85% by mass, based on the total amount of the styrene-acrylic resin. Also, the content of structural units derived from (meth)acrylic acid ester monomers in the styrene-acrylic resin is preferably within the range of 15 to 40% by mass, based on the total amount of the styrene-acrylic resin.

In addition to the above styrene monomer and (meth)acrylic acid ester monomer, the styrene-acrylic resin may be addition polymerized with compounds having a carboxy group, such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester; and compounds having a hydroxy group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

The content of the structural units derived from the above compounds in the styrene-acrylic resin is preferably within the range of 0.1 to 15% by mass relative to the total amount of the styrene-acrylic resin.

The content of the amorphous vinyl resin is preferably within the range of 40 to 95% by mass of the total binder resin, and more preferably within the range of 60 to 90% by mass. Within this range, the resulting toner has a high degree of freedom in resin design and is easy to control the charge.

[1.4] Other components <Coloring agents>
As the colorant other than the above-mentioned cyan colorant used in the toner for developing electrostatic images of the present invention, typical examples of the colorant include colorants for each of the colors magenta (M), yellow (Y), black (Bk) and white (W).

Examples of magenta colorants include dyes such as C.I. Solvent Red 1, 49, 52, 58, 63, 111, and 122, and pigments such as C.I. Pigment Red 2, 3, 5, 6, 7, 15, 16, 48:1, 53:1, 57:1, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238 and 269.

In addition, in the present invention, the use of a colorant for high chroma magenta is a preferred embodiment for obtaining a toner set that can produce images with good color gamut expansion and smooth gloss.

As a colorant for high chroma magenta, it is preferable to use, for example, a complex compound having a structure represented by chemical formulas (3) to (6) described in JP-A-2010-007963, a complex compound having a structure represented by general formula (1) described in JP-A-2010-054799, a complex compound having a structure represented by general formula (1) described in JP-A-2010-054800, a combination of a dye compound having a structure represented by general formula (1) and a copper complex compound having a structure represented by general formula (2) described in JP-A-2015-169697, or a colorant that is a chelate compound of a complex compound having a structure represented by general formula (1) and a dye compound having a structure represented by general formula (2) described in JP-A-2016-130225.

Examples of colorants for yellow include dyes such as C.I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162, and pigments such as C.I. Pigment Orange 31, 43, C.I. Pigment Yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 155, 162, 180, and 185.

Examples of colorants for black include carbon black alone or colorants containing magnetic particles. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Examples of magnetic particles include ferromagnetic metals such as iron, nickel, and cobalt; alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite; chromium dioxide; and alloys that do not contain ferromagnetic metals but that become ferromagnetic when heat-treated. Examples of alloys that become ferromagnetic when heat-treated include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin.

White colorants include inorganic pigments (e.g., titanium white, zinc white, titanium strontium white, heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, smexite, etc.), or organic pigments (e.g., polystyrene resin particles, urea formalin resin particles, etc.).

The content of the colorant in the toner base particles can be determined appropriately and independently. For example, from the viewpoint of ensuring color reproducibility of the image, it is preferably within the range of 1 to 30% by weight, and more preferably within the range of 2 to 20% by weight.

The particle size of the colorant, in terms of volume average particle size, is preferably within the range of 10 to 1000 nm, more preferably within the range of 50 to 500 nm, and even more preferably within the range of 80 to 300 nm.

The volume average particle size may be a catalog value, and for example, the volume average particle size (volume-based median diameter) of the colorant can be measured using "UPA-150" (manufactured by Microtrack Bell Co., Ltd.).

<Release Agent>
The toner according to the present invention may contain a releasing agent. As the releasing agent, various known waxes can be used.

Specific examples include polyolefin waxes such as polyethylene wax and polypropylene wax; branched chain hydrocarbon waxes such as microcrystalline wax; long chain hydrocarbon waxes such as paraffin wax and sazol wax; dialkyl ketone waxes such as distearyl ketone; ester waxes such as carnauba wax, montan wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, and distearyl maleate; and amide waxes such as ethylenediamine behenylamide and tristearyl trimellitate.

It is preferable to use a release agent that does not have any interactions, such as being compatible with the resin that constitutes the binder resin.

Among these, from the viewpoint of releasability during low-temperature fixing, it is preferable to use a release agent with a low melting point, specifically, one with a melting point in the range of 60 to 100°C. In addition, it is preferable to use a release agent with a melting point of about (Mp1-10)°C to (Mp1+20)°C, where Mp1 is the melting point of the crystalline polyester resin that constitutes the binder resin.

The content of the release agent in the toner is preferably within the range of 1 to 20% by mass, and more preferably within the range of 5 to 20% by mass. By ensuring that the content of the release agent in the toner is within the above range, both separation and fixation properties can be reliably achieved.

Methods for introducing the release agent into the toner include a method in which particles consisting of only the release agent are aggregated and fused in an aqueous medium together with amorphous resin particles, crystalline polyester resin particles, etc. in the aggregation and fusion process of the toner manufacturing method described below. The release agent particles can be obtained as a dispersion in which the release agent is dispersed in an aqueous medium. The dispersion of the release agent particles can be prepared by heating an aqueous medium containing a surfactant to a temperature higher than the melting point of the release agent, adding the molten release agent solution, applying mechanical energy such as mechanical stirring or ultrasonic energy to finely disperse the particles, and then cooling.

In addition, when the amorphous resin is, for example, a styrene-acrylic resin, the release agent can be introduced into the toner by preliminarily mixing the release agent with the amorphous resin particles (styrene-acrylic resin particles) that are subjected to the aggregation and fusion process.

Specifically, the release agent is dissolved in a solution of polymerizable monomers for forming a styrene-acrylic resin. This solution is added to an aqueous medium containing a surfactant, and mechanical energy such as mechanical stirring or ultrasonic energy is applied to finely disperse the solution as described above. A polymerization initiator is then added and polymerization is carried out at the desired polymerization temperature. This is called mini-emulsion polymerization, and a dispersion of amorphous resin particles containing the release agent can be prepared.

<Charge Control Agent>
As the charge control agent, various known compounds can be used.

The charge control agent content in the toner is preferably within the range of 0.1 to 10% by weight, and more preferably within the range of 1 to 5% by weight.

<External Additives>
External additives are attached to the surfaces of the toner base particles for the purpose of controlling the fluidity and chargeability.

As the external additive, conventionally known metal oxide particles can be used, such as silica particles, titanium oxide particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, and boron oxide particles. These may be used alone or in combination of two or more.

Regarding the silica particles, silica particles produced by the sol-gel method can be used. Silica particles produced by the sol-gel method are characterized by a narrow particle size distribution, which is preferable in terms of suppressing variation in adhesion strength.

The number-average primary particle size of the silica particles formed by the sol-gel method is preferably within the range of 70 to 150 nm. Silica particles with a number-average primary particle size within this range have a larger particle size than other external additives, so they act as spacers and have the effect of preventing other external additives with smaller particle sizes from being embedded in the toner base particles when they are stirred and mixed in the developing machine, and also have the effect of preventing the toner base particles from fusing together.

Organic particles such as homopolymers of styrene, methyl methacrylate, etc., or copolymers thereof may also be used as external additives.

The metal oxide particles used as the external additive are preferably those that have been subjected to a hydrophobic surface treatment using a known surface treatment agent such as a coupling agent. Preferred examples of the surface treatment agent include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane.

Silicone oil can also be used as the surface treatment agent. Specific examples of silicone oil include organosiloxane oligomers, octamethylcyclotetrasiloxane, or cyclic compounds such as decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane, and linear or branched organosiloxanes. Silicone oils having high reactivity and at least terminally modified, in which modified groups are introduced into the side chain, one terminal, both terminals, one terminal of the side chain, or both terminals of the side chain, may also be used. Examples of the modified groups include, but are not limited to, alkoxy groups, carboxy groups, carbinol groups, higher fatty acid modified groups, phenol groups, epoxy groups, methacryl groups, and amino groups. Silicone oils having several modified groups, such as amino/alkoxy modified groups, may also be used.

Dimethyl silicone oil may be mixed with the modified silicone oil described above, or may be used in combination with other surface treatment agents. Examples of treatment agents that may be used in combination include silane coupling agents, titanate coupling agents, aluminate coupling agents, various silicone oils, fatty acids, fatty acid metal salts, esters thereof, rosin acid, etc.

It is also possible to use a lubricant as an external additive to further improve cleaning and transferability. Examples include metal salts of higher fatty acids such as the following: zinc, aluminum, copper, magnesium, calcium, etc. salts of stearic acid; zinc, manganese, iron, copper, magnesium, etc. salts of oleic acid; zinc, copper, magnesium, etc. salts of palmitic acid; zinc, calcium, etc. salts of linoleic acid; zinc, calcium, etc. salts of ricinoleic acid; etc. salts of ricinoleic acid.

The total amount of these external additives added is preferably in the range of 0.1 to 10% by weight, and more preferably in the range of 1 to 5% by weight, relative to 100 parts by weight of the toner base particles.

The toner according to the present invention preferably has a core-shell structure including core particles containing a binder resin and a colorant, and a shell layer covering the surface of the core particle. The shell layer is not limited to one that completely covers the core particle, and a part of the core particle surface may be exposed. The toner has a core-shell structure, which can provide charging stability and heat-resistant storage properties. The resin that constitutes the shell layer is not particularly limited, but it is preferable to use an amorphous polyester resin or an amorphous vinyl resin.

The core-shell structure can be confirmed by observing the cross-sectional structure of the toner using known means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[1.5] Toner Manufacturing Method The toner according to the present invention can be manufactured by a manufacturing method including the following procedure. However, this is merely an example, and the present invention is not limited to the following manufacturing method example.

The toner of the present invention is preferably produced by a wet method in an aqueous medium, and can be produced, for example, by an emulsion aggregation method.

The emulsion aggregation method is a method of producing toner by mixing an aqueous dispersion of resin particles that make up the binder resin with an aqueous dispersion of particles of other toner components as necessary, slowly aggregating the particles while balancing the repulsive force of the particle surface due to pH adjustment and the aggregating force due to the addition of an aggregating agent made of an electrolyte, and causing association while controlling the average particle size and particle size distribution, while at the same time heating and stirring the particles to fuse together and control the shape.

Below, we will explain an example of a toner manufacturing method in which a crystalline polyester resin and an amorphous resin are used as the binder resin.

A specific example of such a method for producing a toner is
(1) a colorant particle dispersion preparation step of dispersing a colorant in an aqueous medium to prepare a colorant particle dispersion;
(2) a crystalline polyester resin particle dispersion preparation step of dispersing a crystalline polyester resin in an aqueous medium to prepare a crystalline polyester resin particle dispersion;
(3) An amorphous resin particle dispersion preparation step of dispersing an amorphous resin (amorphous polyester resin, amorphous vinyl resin) containing toner components such as a release agent and a charge control agent as necessary in an aqueous medium to prepare an amorphous resin particle dispersion (amorphous polyester resin particle dispersion, amorphous vinyl resin particle dispersion);
(4) an aggregation and fusion step in which the amorphous resin particles, the crystalline polyester resin particles, and the colorant particles are aggregated and fused in an aqueous medium using each of the dispersions obtained in the above (1) to (3) to form aggregated particles;
(5) a maturation step of maturating the aggregated particles by thermal energy to adjust the shape thereof, thereby preparing a toner base particle dispersion liquid;
(6) A cooling step of cooling the toner base particle dispersion liquid;
(7) A process of separating the toner base particles from the cooled toner base particle dispersion liquid into a solid-liquid mixture, and filtering and washing the toner base particles to remove surfactants and the like from the surfaces of the toner base particles;
(8) A drying step of drying the washed toner base particles;
(9) An external additive treatment step of adding an external additive to the dried toner base particles;
It consists of:

In the present invention, the term "aqueous medium" refers to a medium consisting of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. It is preferable to use an alcohol-based organic solvent that does not dissolve the resulting resin.

(1) Colorant particle dispersion preparation process The colorant particle dispersion can be prepared by dispersing the colorant in an aqueous medium. The colorant dispersion is preferably carried out in an aqueous medium with a surfactant concentration equal to or higher than the critical micelle concentration (CMC) in order to disperse the colorant uniformly. As a dispersing machine used in the colorant dispersion, various known dispersing machines can be used.

(Surfactant)
Examples of the surfactant include anionic surfactants such as alkyl sulfate ester salts, polyoxyethylene (n) alkyl ether sulfate salts, alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters; amine salt-type surfactants such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; cationic surfactants of quaternary ammonium salt-type surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives; amphoteric surfactants such as alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, and N-alkyl-N,N-dimethylammonium betaine; and anionic surfactants and cationic surfactants having a fluoroalkyl group can also be used.

The dispersion diameter of the colorant particles in the colorant particle dispersion liquid prepared in this colorant particle dispersion liquid preparation process is preferably within the range of 10 to 300 nm in volume-based median diameter. The volume-based median diameter of the colorant particles in this colorant particle dispersion liquid is measured using an electrophoretic light scattering photometer "ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)."

The colorant may be introduced into the toner by dissolving or dispersing it in advance in a monomer solution for forming the amorphous resin using a mini-emulsion method in the amorphous resin particle dispersion preparation process described below.

(2) Crystalline Polyester Resin Particle Dispersion Preparation Process Methods for dispersing a crystalline polyester resin in an aqueous medium include a direct aqueous dispersion method in which a crystalline polyester resin is dispersed in an aqueous medium containing a surfactant by ultrasonic dispersion or bead mill dispersion, a dissolution-emulsification-desolvation method in which a crystalline polyester resin is dissolved in a solvent, dispersed in an aqueous medium to form emulsified particles (oil droplets), and then the solvent is removed, and a phase inversion emulsification method.

The average particle size of the crystalline polyester resin particles obtained in this crystalline polyester resin particle dispersion preparation process is preferably in the range of, for example, 50 to 500 nm in volume-based median diameter. The volume-based median diameter is measured using an "UPA-EX150" (manufactured by Microtrack Bell).

(3) Amorphous Resin Particle Dispersion Preparation Step When the amorphous resin is an amorphous polyester resin, the amorphous polyester resin particle dispersion can be prepared by dispersing the synthesized amorphous polyester resin in an aqueous medium. The method for dispersing the amorphous polyester resin in an aqueous medium can be the same as the method for dispersing the crystalline polyester resin in an aqueous medium described above.

When the amorphous resin is an amorphous vinyl resin, a polymerizable monomer for forming the amorphous vinyl resin is added to an aqueous medium containing a surfactant at a concentration equal to or higher than the critical micelle formation concentration (CMC), and a water-soluble polymerization initiator is added at a desired polymerization temperature while stirring to carry out polymerization, thereby preparing an amorphous vinyl resin particle dispersion.

Similarly, when the amorphous resin is an amorphous vinyl resin, a liquid in which toner components such as a release agent and a charge control agent are dissolved or dispersed as necessary in a polymerizable monomer for forming the amorphous vinyl resin is added to an aqueous medium containing a surfactant at a critical micelle concentration (CMC) or less, mechanical energy is applied to form droplets, and then a water-soluble radical polymerization initiator is added to cause a polymerization reaction in the droplets, thereby preparing an amorphous resin particle dispersion. The droplets may contain an oil-soluble polymerization initiator. In such an amorphous resin particle dispersion preparation process, a process of applying mechanical energy to emulsify (form droplets) is essential. Examples of means for applying such mechanical energy include a homomixer, ultrasonic wave, and a means for applying strong stirring or ultrasonic vibration energy such as a Manton-Gaulin.

The amorphous resin particles formed in this amorphous resin particle dispersion preparation process can be made to have two or more layers of resins with different compositions. In this case, a method can be adopted in which a polymerization initiator and a polymerizable monomer are added to a dispersion of resin particles prepared by a conventional emulsion polymerization process (first-stage polymerization), and the system is polymerized (second-stage polymerization, third-stage polymerization).

When a surfactant is used in this step, the surfactant may be, for example, the same as the surfactant described above.

(Polymerization initiator)
As the polymerization initiator to be used, various known polymerization initiators can be used. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert-hydroperoxide, tert-butyl performate, tert-peracetic acid, tert-butyl peroxyacetate ... peroxides such as butyl, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, and tert-butyl per-N-(3-tolyl)palmitate; and azo compounds such as 2,2'-azobis(2-amidinopropane) hydrochloride, 2,2'-azobis-(2-amidinopropane) nitrate, 1,1'-azobis(1-methylbutyronitrile-3-sodium sulfonate), 4,4'-azobis-4-cyanovaleric acid, and poly(tetraethylene glycol-2,2'-azobisisobutyrate). Of these, water-soluble polymerization initiators such as ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, 2,2'-azobis(2-amidinopropane) hydrochloride, 2,2'-azobis-(2-amidinopropane) nitrate, 1,1'-azobis(1-methylbutyronitrile-3-sodium sulfonate), and 4,4'-azobis-4-cyanovaleric acid can be preferably used.

Redox polymerization initiators such as persulfate and metabisulfite, or hydrogen peroxide and ascorbic acid can also be used as polymerization initiators.

(Chain Transfer Agent)
In the step of preparing a dispersion liquid of amorphous resin (particularly, amorphous vinyl resin), a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the amorphous resin. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptan, mercapto fatty acid ester, etc.

The average particle size of the amorphous resin particles obtained in this amorphous resin particle dispersion preparation process is preferably within the range of, for example, 50 to 500 nm in terms of volume-based median diameter. The volume-based median diameter is measured using an "UPA-EX150" (manufactured by Microtrack Bell).

(4) Aggregation and Fusion Step In this step, the colorant particles, amorphous resin particles, and crystalline polyester resin particles contained in the dispersion liquid formed in the above step are aggregated and fused in an aqueous medium. In this step, an amorphous resin particle dispersion, a crystalline polyester resin particle dispersion, and a colorant particle dispersion are added to an aqueous medium to aggregate and fuse these particles.

A specific method for aggregating and fusing colorant particles, amorphous resin particles, and crystalline polyester resin particles is to add an aggregating agent to an aqueous medium so that the aggregating agent reaches or exceeds the critical aggregating concentration, and then heat the mixture to a temperature that is equal to or higher than the glass transition point of the amorphous resin particles and equal to or higher than the melting peak temperature of the release agent and crystalline polyester resin, thereby proceeding with the salting out of particles such as colorant particles, amorphous resin particles, and crystalline polyester resin particles while simultaneously proceeding with fusion. When the particles have grown to the desired particle size, an aggregating stopper is added to stop the particle growth, and heating is continued as necessary to control the particle shape.

In this method, it is preferable to leave the mixture after adding the coagulant for as short a time as possible and quickly heat it to a temperature equal to or higher than the glass transition point of the amorphous resin particles associated with the binder resin. The reason for this is not clear, but it is because there is a concern that depending on the time the mixture is left standing after salting out, the state of particle aggregation may fluctuate, causing unstable particle size distribution or causing changes in the surface properties of the fused particles. The time required for this temperature rise is usually preferably within 30 minutes, and more preferably within 10 minutes.

The rate of temperature rise is preferably 1°C/min or more. There is no particular upper limit to the rate of temperature rise, but it is preferably 15°C/min or less from the viewpoint of suppressing the generation of coarse particles due to the rapid progress of fusion. Furthermore, after the reaction system reaches a temperature equal to or higher than the glass transition point, it is essential to continue the fusion by maintaining the temperature of the reaction system for a certain period of time. This allows the growth and fusion of the toner to proceed effectively, and improves the durability of the toner that is finally obtained.

(Flocculant)
The flocculant to be used is not particularly limited, but is preferably selected from metal salts. Examples of metal salts include monovalent metal salts such as salts of alkali metals such as sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; and trivalent metal salts such as iron and aluminum. Specific examples of metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among these, it is particularly preferable to use divalent metal salts because they can promote flocculation with a small amount and are easy to control the flocculation property. These can be used alone or in combination of two or more.

When a surfactant is used in this step, the surfactant may be, for example, the same as the surfactant described above.

(5) Aging step: This step is specifically a step of forming toner base particles by heating and stirring a system containing aggregated particles, and controlling the heating temperature, stirring speed, and heating time until the shape of the aggregated particles reaches a desired average circularity. In this step, it is preferable to control the shape of the toner base particles by thermal energy (heating).

(6) Cooling Step to (8) Drying Step The cooling step, filtration step, washing step and drying step can be carried out by adopting various known methods.

(9) External Addition Processing Step This external addition processing step is a step of adding and mixing an external additive to the dried toner base particles.

One method for adding external additives is the dry method, in which powdered external additives are added to and mixed with dried toner base particles. Mechanical mixers such as a Henschel mixer or coffee mill can be used as the mixer.

[1.6] Physical Properties of Toner <Average Particle Size of Toner>
In the toner of the present invention, the individual toner particles constituting the toner preferably have an average particle size, for example, in the range of 3 to 8 μm, more preferably 5 to 8 μm, in terms of volume-based median diameter.

When manufacturing the toner using the emulsion aggregation method described below, for example, this average particle size can be controlled by the concentration of the aggregating agent used, the amount of organic solvent added, the fusion time, the polymer composition, etc. By having the volume-based median diameter within the above range, the transfer efficiency is increased, improving the image quality of halftones and the image quality of fine lines and dots.

The volumetric median diameter of the toner is measured and calculated using a measuring device that is a "Multisizer 3" (manufactured by Beckman Coulter) connected to a computer system equipped with the data processing software "Software V3.51."

Specifically, 0.02 g of the measurement sample (toner) is added to 20 mL of surfactant solution (a surfactant solution prepared by diluting, for example, a neutral detergent containing a surfactant component with pure water by 10 times for the purpose of dispersing the toner) and allowed to mix, then ultrasonic dispersion is performed for 1 minute to prepare a toner dispersion, and this toner dispersion is poured with a pipette into a beaker containing an "ISOTONII" (manufactured by Beckman Coulter) in a sample stand until the concentration indicated on the measuring device is 8%. By setting the concentration within this range, reproducible measurement values can be obtained. Then, in the measuring device, the measurement particle count is set to 25,000 particles, the aperture diameter is set to 100 μm, and the measurement range of 2 to 60 μm is divided into 256 parts to calculate the frequency value, and the particle size with the largest volume cumulative fraction of 50% is taken as the volume-based median diameter.

<Average Circularity of Toner>
In the toner of the present invention, from the viewpoint of the stability of the charging characteristics and low-temperature fixability, the average circularity of each toner particle constituting the toner is preferably in the range of 0.930 to 1.000, and more preferably in the range of 0.950 to 0.995. By having the average circularity in the above range, the individual toner particles are less likely to be crushed, contamination of the frictional charging member is suppressed, the charging characteristics of the toner are stabilized, and the image formed has high image quality.

In the present invention, the average circularity of the toner is measured using "FPIA-3000" (manufactured by Sysmex).

Specifically, the sample (toner) is mixed in an aqueous solution containing a surfactant, and dispersed by ultrasonic dispersion processing for 1 minute. After that, an image is taken using an "FPIA-3000" (manufactured by Sysmex) under the measurement conditions of HPF (high magnification imaging) mode at an appropriate concentration of 3,000 to 10,000 HPF detections. The circularity of each toner particle is calculated according to the following formula (T), and the circularity of each toner particle is added together and divided by the total number of toner particles.

Formula (T): Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the projected particle image)

<Softening Point of Toner>
The softening point of the toner is preferably within a range of 80 to 120°C, more preferably within a range of 90 to 110°C, from the viewpoint of obtaining low-temperature fixing properties for the toner.

The softening point of the toner is measured using the flow tester shown below.

Specifically, first, in an environment of 20°C and 50% RH, 1.1 g of a sample (toner) is placed in a petri dish and leveled. After leaving it for 12 hours or more, a pressure of 3820 kg/ ^cm2 is applied for 30 seconds using a molding machine "SSP-10A" (manufactured by Shimadzu Corporation) to prepare a cylindrical molded sample with a diameter of 1 cm. Next, in an environment of 24°C and 50% RH, this molded sample is extruded from a hole (1 mm diameter x 1 mm) of a cylindrical die using a piston with a diameter of 1 cm from the end of preheating under conditions of a load of 196 N (20 kgf), a starting temperature of 60°C, a preheating time of 300 seconds, and a heating rate of 6°C/min using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation). The offset method temperature T _offset measured by a melting temperature measurement method using a heating method with an offset value set to 5 mm is regarded as the softening point.

[1.7] Developer The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may also be mixed with a carrier and used as a two-component developer.

As the carrier, magnetic particles made of conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals with metals such as aluminum and lead can be used, and among these, it is preferable to use ferrite particles. In addition, as the carrier, a coated carrier in which the surface of the magnetic particles is coated with a coating agent such as resin, or a resin dispersion type carrier in which magnetic fine powder is dispersed in a binder resin may also be used.

The carrier preferably has a volume average particle size in the range of 15 to 100 μm, and more preferably in the range of 25 to 80 μm.

[2] Electrophotographic Image Forming Method and Electrophotographic Image Forming Apparatus The electrophotographic image forming method of the present invention is an electrophotographic image forming method having at least a step of charging an image carrier, a step of forming an electrostatic image, a step of developing an electrostatic image, a step of transferring a toner image, and a step of fixing a toner image, and is characterized in that the toner set for developing an electrostatic image of at least five colors of the present invention is used.

In detail, the method includes a charging step for charging the surface of an image carrier, an electrostatic image forming step for forming an electrostatic image on the charged surface of the image carrier, a developing step for developing the electrostatic image formed on the surface of the image carrier as a toner image using at least five colors of the toner set for developing electrostatic images of the present invention, a transfer step for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step for fixing the toner image transferred to the surface of the recording medium.

(Electrifying process)
In this step, the electrophotographic photoreceptor is charged. The charging method is not particularly limited, and may be a known method such as a charging roller method in which the electrophotographic photoreceptor is charged by a charging roller.

(Step of forming electrostatic latent image)
In this process, an electrostatic latent image is formed on an electrophotographic photoreceptor (electrostatic latent image bearing member).

The electrophotographic photoreceptor is not particularly limited, but examples include drum-shaped organic photoreceptors such as polysilane or phthalopolymethine.

The electrostatic latent image is formed, for example, by uniformly charging the surface of the electrophotographic photoreceptor with a charging means and exposing the surface of the electrophotographic photoreceptor to light in an image-like manner with an exposure means. Note that the electrostatic latent image is an image formed on the surface of the electrophotographic photoreceptor by such a charging means.

There are no particular limitations on the charging means and exposure means, and any means commonly used in electrophotography can be used.

(Developing process)
The developing step is a step of developing the electrostatic latent image with toner (generally, a dry developer containing toner) to form a toner image.

The toner image is formed, for example, using a dry developer containing toner, using a developing means consisting of an agitator that charges the toner by friction agitation, and a rotatable magnet roller.

Specifically, in the developing means, for example, toner and carrier are mixed and stirred, and the toner becomes charged by friction during this process and is held on the surface of a rotating magnet roller, forming a magnetic brush. Since the magnet roller is disposed near the electrophotographic photoreceptor, a portion of the toner constituting the magnetic brush formed on the surface of the magnet roller moves to the surface of the electrophotographic photoreceptor by electrical attraction. As a result, the electrostatic latent image is developed by the toner, and a toner image is formed on the surface of the electrophotographic photoreceptor.

In this case, in the toner set according to the present invention, the amount of silicon phthalocyanine compound-containing toner and copper phthalocyanine compound-containing toner supplied to an image is preferably controlled in advance according to the density range of the image, such as by increasing the amount of copper phthalocyanine compound-containing toner supplied if the high density range of the cyan image increases, and by increasing the amount of silicon phthalocyanine compound-containing toner supplied if the low density range increases, taking color into consideration. The software is then incorporated into the image processing unit 60 of a full-color high-speed multifunction printer using toner of at least five colors, as described below, and the amount of toner supplied is controlled while detecting the image density range.

(Transferring step)
In this step, the toner image is transferred onto a recording medium.

The toner image is transferred to the recording medium by peeling and charging the toner image onto the recording medium.

Transfer means that can be used include, for example, a corona transfer device that uses corona discharge, a transfer belt, a transfer roller, etc.

The transfer process can be performed, for example, by using an intermediate transfer body, first transferring the toner image onto the intermediate transfer body, and then secondarily transferring the toner image onto the recording medium, or by directly transferring the toner image formed on the electrophotographic photoreceptor onto the recording medium.

(Fixing process)
The fixing step according to the present invention includes a step of fixing the unfixed image (toner image) formed by using toner to the recording material transferred thereto by passing the recording material between a heated fixing belt or fixing roller and a pressure member. When the fixing belt or fixing roller used is the fixing member according to the present invention, even if the paper output speed of the image forming apparatus is increased (a copy speed of 70 cpm or more, i.e., an image forming apparatus having Seg. 5 or more is used), a high fixing separation performance can be exhibited and an effect of preventing image unevenness can be obtained.

Specific examples of the fixing process include a belt fixing method or a roller fixing method that uses a fixing belt or roller as a fixing rotor and a pressure roller as a pressure member that is in pressure contact with the fixing belt or roller to form a fixing nip.

(Cleaning process)
In this step, the developer that has not been used for image formation or that has not been transferred and remains on the developer carrying member, such as the photoreceptor or intermediate transfer member, is removed from the developer carrying member.

The cleaning method is not particularly limited, but it is preferable to use a method in which a blade is used, the tip of which is in contact with the object to be cleaned, such as a photoconductor, and which scrapes the surface of the photoconductor.

In the electrophotographic image forming method of the present invention, the chromatic or black toner image is ultimately transferred and formed on a recording medium.

The recording medium is not particularly limited, and examples thereof include, but are not limited to, ordinary paper ranging from thin paper to thick paper, coated printing paper such as fine paper, art paper or coated paper, commercially available paper such as Japanese paper and postcard paper, resin films such as polypropylene (PP) film, polyethylene terephthalate (PET) film, triacetyl cellulose (TAC) film, and cloth, etc. The color of the recording medium is not particularly limited, and recording media of various colors can be used.

The electrophotographic image forming apparatus of the present invention is an electrophotographic image forming apparatus that includes at least an image carrier charging means, an electrostatic image forming means, an electrostatic image developing means, a toner image transferring means, and a toner image fixing means, and is characterized in that it uses at least five colors of the toner set for developing electrostatic images of the present invention.

In detail, the device includes an image carrier, a charging means for charging the surface of the image carrier, and an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier. It also includes a developing means for developing the electrostatic image formed on the surface of the image carrier as a toner image using the toner set for developing electrostatic images of the present invention, a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium.

The electrophotographic image forming apparatus of the present invention is, for example, a tandem type image forming apparatus in which photoreceptor drums 83Y, 83M, 83C1, 83C2, and 83K corresponding to the five colors of yellow (Y), magenta (M), cyan (C1: toner containing a silicon phthalocyanine compound/C2: toner containing a copper phthalocyanine compound), and black (Bk) are arranged in series in the running direction of the intermediate transfer body, as shown in FIG. 1.

As shown in FIG. 1, the electrophotographic image forming apparatus 1 includes a control unit (stored in an image processing unit 60: not shown) that is composed of a CPU (Central Processing Unit) and memories (not shown) such as a ROM (Read Only Memory) and a RAM (Random Access Memory), a storage unit (not shown) that is composed of a HDD (Hard Disk Drive) and an SSD (Solid State Drive), a network I/F unit (not shown) that is composed of a NIC (Network Interface Card) and a modem, a display operation unit 40 that is composed of a touch panel, an image reading unit 50 that is composed of an ADF (Auto Document Feeder) and a scanner, and a RIP (Raster Image The image processing unit 60 is made up of an image processing unit (image processor) and the like, a conveying unit 70, and an image forming unit 80. The intermediate transfer body of this embodiment is included in the image forming unit 80, which processes the paper conveyed from the conveying unit 70.

As shown in FIG. 1, the transport section 70 is composed of a paper feeder 71, a transport mechanism 72, a paper discharge device 73, etc. Paper stored in the paper feeder 71 is sent out one by one from the top and transported to the image forming section 80 by the transport mechanism 72 equipped with multiple transport rollers such as registration rollers. At this time, the registration section equipped with registration rollers corrects the inclination of the fed paper and adjusts the transport timing. Then, the paper on which an image has been formed by the image forming section 80 is discharged to a paper discharge tray outside the machine by the paper discharge device 73 equipped with paper discharge rollers.

As shown in FIG. 1, the image forming unit 80 is composed of exposure devices 81 (81Y, 81M, 81C1, 81C2, 81K), development devices 82 (82Y, 82M, 82C1, 82C2, 82K), photoconductor drums 83 (83Y, 83M, 83C1, 83C2, 83K), charging devices 84 (84Y, 84M, 84C, 84K), cleaning devices 85 (85Y, 85M, 85C1, 85C285K), primary transfer rollers 86 (86Y, 86M, 86C1, 86C2, 86K), intermediate transfer unit 87, fixing device 88, etc., which are provided corresponding to different color components Y, M, C1, C2, and K. Each element will be described below. In the following description, reference numerals excluding Y, M, C, and K will be used as necessary.

The photoconductor drums 83 for each color component Y, M, C, and K are image carriers in which an organic photoconductor layer (OPC) with an overcoat layer as a protective layer is formed on the outer periphery of a cylindrical metal base made of aluminum. The photoconductor drums 83 are grounded and rotate counterclockwise in FIG. 1, following the intermediate transfer body.

The charging device 84 for each color component Y, M, C1, C2, and K is of the Scorotron type and is disposed adjacent to the corresponding photoconductor drum 83 with its longitudinal direction aligned with the rotational axis of the photoconductor drum 83, and applies a uniform potential to the surface of the photoconductor drum 83 by corona discharge of the same polarity as the toner.

The exposure device 81 for each color component Y, M, C1, C2, and K scans parallel to the axis of rotation of the photoconductor drum 83, for example using a polygon mirror, and forms an electrostatic latent image by exposing the corresponding uniformly charged surface of the photoconductor drum 83 to image light based on image data.

The developing device 82 for each color component Y, M, C1, C2, and K contains a two-component developer consisting of small particle size toner of the corresponding color component and a magnetic material, and conveys the toner to the surface of the photoconductor drum 83, where the electrostatic latent image carried on the photoconductor drum 83 is visualized by the toner.

The primary transfer rollers 86 for each color component Y, M, C1, C2, and K press the intermediate transfer body of this embodiment against the photoconductor drum 83, and sequentially superimpose the toner images of each color formed on the corresponding photoconductor drum 83 onto the intermediate transfer body for primary transfer.

The cleaning device 85 for each color component Y, M, C1, C2, and K collects residual toner remaining on the corresponding photoconductor drum 83 after the primary transfer. In addition, a lubricant application mechanism (not shown) is provided adjacent to the cleaning device 85 downstream of the rotation direction of the photoconductor drum 83, and applies a lubricant to the photosensitive surface of the corresponding photoconductor drum 83.

The intermediate transfer unit 87 includes an endless intermediate transfer body 87a, a support roller 87b, a secondary transfer roller 87c, an intermediate transfer cleaning section 87d, and the like, and is configured by stretching the intermediate transfer body 87a over the multiple support rollers 87b. When the intermediate transfer body 87a, to which the toner images of each color are primarily transferred by the primary transfer rollers 86Y, 86M, 86C1, 86C2, and 86K, is pressed against the paper by the secondary transfer roller 87c, the toner image is secondarily transferred to the paper by the electric field acting on the toner based on the transfer voltage between the intermediate transfer body 87a and the secondary transfer roller 87c, and is sent to the fixing device 88. The intermediate transfer cleaning section 87d has a belt cleaning blade that is in sliding contact with the surface of the intermediate transfer body 87a. Any residual toner remaining on the surface of the intermediate transfer body 87a after the secondary transfer is scraped off and removed by the belt cleaning blade.

The fixing device 88 includes a heating roller 88a and a fixing roller 88b that serve as heat sources, a fixing belt 88c that is stretched over them, and a pressure roller 88d. The pressure roller 88d is pressed against the fixing roller 88b via the fixing belt 88c, and this pressure contact portion forms a nip portion. The fixing belt 88c, which is heated by the heating roller 88a, and each roller apply heat and pressure to the paper that passes through the nip portion, thereby fixing the unfixed toner image formed on the paper.

Then, the paper on which the toner image has been fixed by the fixing device 88 is discharged to a paper discharge tray outside the machine by a paper discharge device 73 equipped with a paper discharge roller.

Note that FIG. 1 is an example of the image forming device 1 of the present invention, and its structure and configuration can be modified as appropriate.

The present invention will be specifically explained below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

First, we will explain the measurement methods for various physical properties used in the examples.

[Method of measuring weight average molecular weight (Mw) and number average molecular weight (Mn)]
The Mw and Mn of the resin are determined by the following method. Using an apparatus "HLC-8320GPC" (manufactured by Tosoh Corporation) and a column "TSKguard column + TSKgel Super HZ-M triple series" (manufactured by Tosoh Corporation), tetrahydrofuran (THF) is passed as a carrier solvent at a flow rate of 0.2 mL / min while maintaining the column temperature at 40 ° C., and the measurement sample (amorphous resin (A)) is dissolved in THF to a concentration of 1 mg / mL under dissolution conditions in which the sample is treated for 5 minutes at room temperature using an ultrasonic disperser, and then treated with a membrane filter with a pore size of 0.2 μm to obtain a sample solution, and 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent, and detected using a refractive index detector (RI detector). The molecular weight distribution of the measurement sample is calculated using a calibration curve measured using 10 monodisperse polystyrene standard particles.

[Method of measuring Tg]
The glass transition point of the resin is measured by the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-82. That is, 4.5 mg of the measurement sample (amorphous resin) is precisely weighed to two decimal places, sealed in an aluminum pan, and set in the sample holder of a differential scanning calorimeter "DSC8500" (manufactured by PerkinElmer). An empty aluminum pan is used as a reference, and temperature control is performed with a measurement temperature of -10 to 120 ° C, a heating rate of 10 ° C / min, and a heating rate of 10 ° C / min, with heating-cooling-heating, and analysis is performed based on the data from the second heating. The value of the intersection between the extension line of the baseline before the rise of the first endothermic peak and the tangent line showing the maximum slope between the rising part of the first endothermic peak and the peak apex is taken as the glass transition temperature.

[Method for measuring acid value]
The acid value is the mass of potassium hydroxide (KOH) required to neutralize the acid contained in 1 g of a sample, expressed in mg units. The acid value of a resin is measured according to the following procedure in accordance with JIS K0070-1992.

(Preparation of Reagents)
Dissolve 1.0 g of phenolphthalein in 90 mL of ethyl alcohol (95% by volume), add ion-exchanged water to make 100 mL, and prepare a phenolphthalein solution. Dissolve 7 g of JIS special grade potassium hydroxide in 5 mL of ion-exchanged water, and add ethyl alcohol (95% by volume) to make 1 liter. Place in an alkali-resistant container to avoid contact with carbon dioxide, leave for 3 days, and then filter to prepare a potassium hydroxide solution. Standardization follows the description of JIS K0070-1992.

(Main test)
2.0 g of the crushed sample is accurately weighed into a 200 mL Erlenmeyer flask, and 100 mL of a mixed solution of toluene/ethanol (toluene:ethanol volume ratio 2:1) is added and dissolved over 5 hours. Next, several drops of the prepared phenolphthalein solution are added as an indicator, and titration is performed using the prepared potassium hydroxide solution. The end point of the titration is when the light red color of the indicator continues for about 30 seconds.

(Blank test)
The same procedure as in the main test described above is carried out, except that no sample is used (i.e., only a mixed solution of toluene/ethanol (toluene:ethanol in a volume ratio of 2:1) is used).

The titration results from this test and the blank test are substituted into the following formula (1) to calculate the acid value.

Formula (1) A=[(B-C)×f×5.6]/S
A: Acid value (mgKOH/g)
B: Amount of potassium hydroxide solution added during blank test (mL)
C: Amount of potassium hydroxide solution added during this test (mL)
f: factor of 0.1 mol/L potassium hydroxide ethanol solution S: mass of sample (g)

[Method of measuring Tm]
The melting point (Tm) of the crystalline polyester resin is the temperature at the top of the endothermic peak, and can be measured by DSC using a Diamond DSC (manufactured by PerkinElmer).

Specifically, the sample is sealed in an aluminum pan KIT NO. B0143013 and set in the sample holder of a thermal analysis device Diamond DSC (PerkinElmer), and the temperature is changed in the order of heating, cooling, and heating. In the first heating, the temperature is raised from room temperature (25°C), and in the second heating, from 0°C, to 150°C at a heating rate of 10°C/min and held at 150°C for 5 minutes. In the cooling, the temperature is lowered from 150°C to 0°C at a heating rate of 10°C/min and held at 0°C for 5 minutes. The temperature at the top of the endothermic peak in the endothermic curve obtained in the second heating is measured as the melting point.

Example 1
<Preparation of Colorant Dispersion>
[Preparation of Cyan Colorant Particle Dispersion [Cy]]
(Preparation of Colorant Dispersion (Water-Based Dispersion of Cyan Colorant Particles Cy1) Used in Toner Production)
13 parts by mass of sodium n-dodecyl sulfate was added to 77 parts by mass of ion-exchanged water, and dissolved and stirred to prepare a surfactant aqueous solution. 10 parts by mass of silicon phthalocyanine example compound (I-1) was gradually added to this surfactant aqueous solution as a colorant for cyan toner. After the addition was completed, a dispersion process was performed using an "SC Mill" (manufactured by Nippon Coke & Engineering Co., Ltd.) with zirconia beads (φ0.3 mm) set to a filling rate of 75%, to prepare an aqueous dispersion of cyan colorant particles Cy1. The median diameter d50 of the aqueous dispersion of cyan colorant particles Cy1 obtained was measured using a microtrack particle size distribution measuring device "UPA-150" (manufactured by Nikkiso Co., Ltd.), and was found to be 120 nm.

(Preparation of Colorant Dispersion (Water-Based Dispersion of Cyan Colorant Particles, Cy2) Used in Toner Production)
An aqueous dispersion Cy2 of cyan colorant particles was prepared in the same manner as in the preparation of the aqueous dispersion Cy1 of cyan colorant particles, except that the silicon phthalocyanine exemplary compound (I-3) was used instead of the silicon phthalocyanine exemplary compound (I-1).

(Preparation of colorant dispersion used in toner production (water-based dispersion of cyan colorant particles, Cy3))
An aqueous dispersion Cy3 of cyan colorant particles was prepared in the same manner as in the preparation of the aqueous dispersion Cy1 of cyan colorant particles, except that the silicon phthalocyanine exemplary compound (I-10) was used instead of the silicon phthalocyanine exemplary compound (I-1).

(Preparation of Colorant Dispersion (Cy4 Dispersion of Cyan Colorant Particles) Used in Toner Production)
13 parts by mass of sodium n-dodecyl sulfate was added to 77 parts by mass of ion-exchanged water, dissolved and stirred to prepare a surfactant aqueous solution. 10 parts by mass of a copper phthalocyanine compound (C.I. Pigment Blue 15:3) was gradually added to this surfactant aqueous solution as a colorant for a cyan toner. After the addition was completed, a dispersion process was performed using an "SC Mill" (manufactured by Nippon Coke & Engineering Co., Ltd.) with zirconia beads (φ0.3 mm) set to a filling rate of 75%, to prepare an aqueous dispersion of cyan colorant particles Cy4. The median diameter d50 of the aqueous dispersion of cyan colorant particles Cy4 obtained was measured using a microtrack particle size distribution analyzer "UPA-150" (manufactured by Nikkiso Co., Ltd.), and was found to be 156 nm.

(Preparation of colorant dispersion used in toner production (water-based dispersion of cyan colorant particles, Cy5))
An aqueous dispersion liquid Cy5 of cyan colorant particles was prepared in the same manner as in the preparation of the aqueous dispersion liquid Cy4 of cyan colorant particles, except that a copper phthalocyanine compound (C.I. Pigment Blue 60) was used instead of the copper phthalocyanine compound (C.I. Pigment Blue 15:3).

<Preparation of resin particles>
[Synthesis of amorphous vinyl resin V1]

(First stage polymerization)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with a solution of 8 g of sodium dodecyl sulfate dissolved in 3 L of ion-exchanged water, and the internal temperature was raised to 80° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. Thereafter, a solution of 10 g of potassium persulfate dissolved in 200 g of ion-exchanged water was added, and the liquid temperature was again raised to 80° C.

A monomer mixture prepared by mixing the following components in the amounts listed below was added dropwise to the resulting solution over a period of 1 hour, and then the mixture was heated and stirred at 80°C for 2 hours to polymerize the mixture, thereby preparing resin microparticle dispersion X1 in which resin microparticles x1 are dispersed.

Styrene 480g
n-Butyl acrylate 250g
Methacrylic acid 68g

(Second stage polymerization)
A solution of 7 g of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 1,460 mL of ion-exchanged water was placed in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, and heated to 88°C.

To the resulting solution, resin microparticle dispersion X1 was added in an amount equivalent to 80 g of resin microparticles x1, and a monomer solution at 80°C containing the following components in the amounts listed below was added to the above solution. The mixture was mixed and dispersed for 1 hour using a mechanical disperser with a circulation path, CREARMIX (manufactured by M Technique Co., Ltd., CREARMIX is a registered trademark of the company), to prepare a dispersion containing emulsified particles (oil droplets).

245g styrene
n-Butyl acrylate 95g
Methacrylic acid 35g
n-Octyl-3-mercaptopropionate 4.0g
Next, an initiator solution in which 6 g of potassium persulfate was dissolved in 200 mL of ion-exchanged water was added to the obtained dispersion, and the system was heated and stirred at 82°C for 1 hour to carry out polymerization, thereby preparing resin microparticle dispersion X2 in which resin microparticles x2 were dispersed.

(Third stage polymerization)
A solution of 11 g of potassium persulfate dissolved in 400 mL of ion-exchanged water was added to the resin particle dispersion X2, and a monomer composition containing the following components in the following amounts was added dropwise to the solution over 1 hour at a temperature of 82° C. After the dropwise addition, polymerization was carried out by heating and stirring for 2 hours. The resulting dispersion was then cooled to 28° C. In this way, amorphous vinyl resin V1, which is an amorphous vinyl resin, was prepared.

Styrene 405g
n-Butyl acrylate 160g
Methacrylic acid 33g
n-Octyl-3-mercaptopropionate 10g
The dispersion of the amorphous vinyl resin V1 was diluted with ion-exchanged water to a concentration of 30% by mass of the amorphous vinyl resin V1 to obtain an aqueous dispersion VD1. The volume-based median diameter D50z of the resin particles in the aqueous dispersion VD1 was measured to be 215 nm. The weight-average molecular weight Mw of the amorphous vinyl resin V1 was measured to be 30,800.

[Synthesis of amorphous polyester resin A1]
The following components were charged in the following amounts into a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a rectification column. "BPA-PO" represents a 2-mol propylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane, and "BPO-EO" represents a 2-mol ethylene oxide adduct of 2,2-bis(4-hydroxyphenyl)propane. Fumaric acid and terephthalic acid are polycarboxylic acids, and BPA-PO and BPO-EO are polyhydric alcohols.

Fumaric acid (FA) 1.8 parts by mass Terephthalic acid (TA) 29.2 parts by mass BPA-PO 58.2 parts by mass BPO-EO 6.7 parts by mass

The temperature of the obtained mixture was raised to 190°C over 1 hour, and after confirming that the mixture was uniformly stirred, dibutyltin oxide was added as a catalyst in an amount of 0.006% by mass relative to the total amount of polyvalent carboxylic acid. The temperature of the mixture was then raised from the same temperature to 240°C over 6 hours while distilling off the water produced. When the temperature reached 240°C, 1.6 parts by mass of trimellitic acid was added to the mixture. The dehydration condensation reaction was continued while maintaining the temperature at 240°C until the acid value of the product reached 21 mgKOH/g, thereby obtaining amorphous polyester resin A1, which is an amorphous polyester. The number average molecular weight (Mn) of the obtained amorphous polyester resin A1 was 3600, and the glass transition point (Tg) was 62°C. The acid value, Mn, and Tg of the amorphous polyester resin A1 were measured as described above.

[Preparation of Aqueous Dispersion B1 of Amorphous Polyester Fine Particles]
240 parts by mass of methyl ethyl ketone and 60 parts by mass of isopropyl alcohol (IPA) were added to a reaction vessel equipped with an anchor blade for stirring power, and nitrogen was sent into the reaction vessel to replace the air in the reaction vessel with nitrogen. Next, while the mixed liquid in the reaction vessel was heated to 60°C by an oil bath device, 300 parts by mass of amorphous polyester resin A1 was slowly added to the mixed liquid and dissolved while stirring. Next, 20 parts by mass of 10% ammonia water was added to the resulting mixed liquid, and 1500 parts by mass of deionized water was added to the resulting mixed liquid while stirring using a metering pump. It was confirmed that emulsification was performed by the fact that the resulting mixed liquid was milky white and the stirring viscosity was reduced.

Then, the obtained emulsion was pumped up by the pressure difference based on centrifugal force and transferred to a separable flask equipped with a stirring blade that forms a wetted wall on the wall surface of the reaction vessel, a reflux device, and a pressure reduction device using a vacuum pump. The wall temperature in the reaction vessel was set to 58°C, and the solvent and dispersion medium in the emulsion were distilled off while continuing to stir under reduced pressure. The end point of the distillation was the point at which the obtained dispersion reached 1,000 parts by mass. The pressure inside the reaction vessel was set to normal pressure, and the dispersion was cooled to room temperature while stirring to obtain an aqueous dispersion B1 of fine particles of amorphous polyester resin A1 with a solid content of 30% by mass.

The volume-based median diameter (D50v) of the resin microparticles dispersed in the aqueous dispersion B1 was 162 nm.

[Synthesis of crystalline polyester resin C1]
The following components were charged in the amounts shown below into a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column. Sebacic acid is a polycarboxylic acid.

Sebacic acid (SA) 205 parts by mass Ethylene glycol 61 parts by mass The temperature of the above mixture was raised to 190° C. over 1 hour, and after confirming that the mixture was uniformly stirred, Ti(OBu) ₄ was added as a catalyst to the reaction vessel in an amount of 0.006% by mass based on the total amount of polyvalent carboxylic acid. Further, while distilling off the generated water, the temperature of the above mixture was raised from the same temperature to 240° C. over 6 hours, and further, while maintaining the temperature at 240° C., the dehydration condensation reaction was continued to carry out a polymerization reaction until the acid value of the product reached 20 mgKOH/g, thereby obtaining a crystalline polyester resin C1.

[Preparation of Water-Based Dispersion D1 of Crystalline Polyester Fine Particles]
300 parts by mass of methyl ethyl ketone was added to a reaction vessel equipped with an anchor blade for stirring power, and nitrogen was sent into the reaction vessel to replace the air in the reaction vessel with nitrogen. Next, while the methyl ethyl ketone in the reaction vessel was heated to 70°C using an oil bath device, 300 parts by mass of crystalline polyester resin C1 was slowly added to the mixture and dissolved while stirring. Next, 20 parts by mass of 10% ammonia water was added to the resulting mixture, and 1500 parts by mass of deionized water was added to the resulting mixture using a metering pump while stirring. It was confirmed that emulsification had been performed by the fact that the resulting mixture was milky white and the stirring viscosity was reduced.

Then, the obtained emulsion was pumped up by the pressure difference based on centrifugal force and transferred to a separable flask equipped with a stirring blade that forms a wetted wall on the wall surface of the reaction vessel, a reflux device, and a pressure reduction device using a vacuum pump. The wall temperature in the reaction vessel was set to 58°C, and the solvent and dispersion medium in the emulsion were distilled off while continuing to stir under reduced pressure. The end point of the distillation was the point at which the obtained dispersion reached 1000 parts by mass. The pressure inside the reaction vessel was set to normal pressure, and the dispersion was cooled to room temperature while stirring to obtain an aqueous dispersion D1 of fine particles of crystalline polyester resin C1 with a solid content of 30% by mass.

[Preparation of Water-Based Dispersion W1 of Releasing Agent Fine Particles]
50 parts by weight of "Nissan Electol WEP-3" (manufactured by NOF Corporation, melting point (Tm): 73°C, "Nissan Electol" and "WEP" are both registered trademarks of the company), 5 parts by weight of sodium polyoxyethylene-2-dodecyl ether sulfate, and 195 parts by weight of ion-exchanged water were mixed, heated to 90°C, and thoroughly dispersed using a homogenizer "Ultra-Turrax T50" (manufactured by IKA Corporation), and then a dispersion process was performed using a pressure discharge type Gaulin homogenizer to prepare an aqueous dispersion W1, which is an aqueous dispersion of release agent fine particles. The volume-based median diameter D50v of the release agent fine particles in the aqueous dispersion W1 was 170 nm. "Nissan Electol WEP-3" is a refined product whose main component is behenyl behenate (BB).

<Production of Cyan Toner 1>
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with 2,333 parts by mass of an aqueous dispersion VD1 of amorphous vinyl resin microparticles (700 parts by mass in terms of solid content), a colorant microparticle dispersion Cy1 such that the amount in the toner was 3.3% by mass, 375 parts by mass of an aqueous dispersion W1 of release agent microparticles (75 parts by mass in terms of solid content), and 942 parts by mass of ion-exchanged water, and while stirring, a 5 mol/L aqueous sodium hydroxide solution was added to the resulting mixture to adjust the pH of the mixture to 10 (20° C.).

Next, an aqueous solution of 160 parts by mass of magnesium chloride dissolved in 160 parts by mass of ion-exchanged water was added to the above mixture at a rate of 10 parts by mass/min. After leaving it for 5 minutes, the temperature of the resulting mixture was raised, and the temperature was raised to 80°C over 60 minutes. After the temperature was raised, 267 parts by mass of aqueous dispersion D1 of crystalline polyester resin particles (80 parts by mass in solids) was added to the mixture left for 5 minutes at a rate of 25 parts by mass/min. After leaving it for 15 minutes, the aggregation reaction was started. After the start of this aggregation reaction, sampling was performed periodically, and the volume-based median diameter D50v of the generated aggregated particles was measured using a particle size distribution measuring device "Coulter Multisizer 3" (manufactured by Beckman Coulter, Inc.), and the stirring was continued while reducing the stirring speed as necessary until D50v became 6.3 μm, and the aggregation reaction was continued.

Then, when D50v reached 6.3 μm, the stirring speed was increased again, and 333 parts by mass of aqueous dispersion B1 of amorphous polyester resin microparticles (100 parts by mass in terms of solids) was added at a rate of 25 parts by mass/min. After periodic sampling was performed and it was confirmed that the supernatant of the centrifugation was transparent, an aqueous solution in which 300 parts by mass of sodium chloride was dissolved in 1200 parts by mass of ion-exchanged water was added to the above mixture, the temperature of the mixture was kept at 85°C, and stirring was continued. When the average circularity of the particles in the mixture reached 0.952 as measured by a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation, "FPIA" is a registered trademark of the company), the above mixture was cooled to 30°C at a rate of 6°C/min to stop the aggregation reaction, and a dispersion of toner particles was obtained. The particle size (D50v) of the toner particles after cooling was 6.3 μm, and the average circularity was 0.952.

The obtained dispersion of toner particles was subjected to solid-liquid separation using a basket-type centrifuge "MARK III Model No. 60x40" (manufactured by Matsumoto Machinery Manufacturing Co., Ltd.) to obtain a wet cake. The obtained wet cake was repeatedly washed and separated into solid and liquid using the basket-type centrifuge until the electrical conductivity of the filtrate reached 15 μS/cm, and the washed cake was fed little by little to a "Flash Jet Dryer" (manufactured by Seishin Enterprise Co., Ltd.) and dried until the moisture content was about 2.0% by mass by blowing air at a temperature of 40°C and a humidity of 20% RH, and then cooled to 24°C. The cake was then transferred to a "Vibration Fluidized Bed Device" (manufactured by Chuo Kakoki Co., Ltd.) and dried for 2 hours at a temperature of 40°C to obtain toner base particles 1X containing a silicon phthalocyanine compound with a moisture content of 0.5% or less.

1% by mass of hydrophobic silica and 1.2% by mass of hydrophobic titanium oxide were added to the obtained toner base particles 1X, and mixed for 20 minutes with a "Henschel Mixer" (manufactured by Nippon Coke & Engineering Co., Ltd.) at a rotor blade peripheral speed of 24 mm/sec., and then an external additive treatment was carried out to remove coarse particles using a 400 mesh sieve, thereby producing toner particles 1.

Furthermore, a ferrite carrier with a volume average particle size of 60 μm coated with silicone resin was added to and mixed with toner particles 1 so that the toner particle concentration was 6 mass %. In this way, cyan toner 1, a two-component developer, was produced.

<Production of Cyan Toner 2>
Cyan toner 2 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion Cy2 of cyan colorant particles was used instead of the aqueous dispersion Cy1 of cyan colorant particles.

<Production of Cyan Toner 3>
Cyan toner 3 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion Cy3 of cyan colorant particles was used instead of the aqueous dispersion Cy1 of cyan colorant particles.

<Production of Cyan Toner 4>
Cyan toner 4 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion of cyan colorant particles Cy4 was used instead of the aqueous dispersion of cyan colorant particles Cy1.

<Production of Cyan Toner 5>
Cyan toner 5 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion Cy2 of cyan colorant particles was used instead of the aqueous dispersion Cy1 of cyan colorant particles.

<<Preparation of other colorant dispersions for use in toner sets>>
[Preparation of Water-Based Dispersion Y1 of Yellow Colorant Particles]
95 parts by mass of sodium n-dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water. 250 parts by mass of C.I. Pigment Yellow 74 was gradually added to the solution while stirring, and then a dispersion treatment was performed using a stirring device "Clearmix" (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion liquid (Y1) of yellow colorant particles. The volume-based median diameter of the colorant particles in the aqueous dispersion liquid (Y1) of yellow colorant particles was 126 nm.

[Preparation of Water-Based Dispersion M1 of Magenta Colorant Particles]
95 parts by mass of sodium n-dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water. 250 parts by mass of C.I. Pigment Red 122 was gradually added to the solution while stirring, and then a dispersion treatment was performed using a stirring device "Clearmix" (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion liquid (M1) of magenta colorant particles. The volume-based median diameter of the colorant particles in the aqueous dispersion liquid M1 of magenta colorant particles was 5 nm.

[Preparation of Water-Based Dispersion M2 of Magenta Colorant Particles; High Chroma Magenta]
An aqueous surfactant solution was prepared by dissolving 63 parts by mass of sodium n-dodecyl sulfate in 880 parts by mass of ion-exchanged water with stirring. 80 parts by mass of the following complex compound 1 and 100 parts by mass of quinacridone (C.I. Pigment Red 122) were gradually added to this aqueous surfactant solution, and then a dispersion treatment was performed using "Clearmix (registered trademark) W Motion CLM-0.8" (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion M2 of magenta colorant particles with a solid content of 16% by mass in which particles of the complex compound 1 and quinacridone were dispersed.

[Preparation of Water-Based Dispersion Bk1 of Black Colorant Particles]
90 parts by mass of sodium n-dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water. While stirring this solution, 320 parts by mass of carbon black "REGAL 330R" (manufactured by Cabot Corporation) was gradually added to the solution, and then a dispersion treatment was carried out using a stirring device "CLEARMIX" (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion liquid (Bk-1) of black colorant particles. The volume-based median diameter of the colorant fine particles in the aqueous dispersion liquid Bk1 of black colorant particles was 110 nm.

<Production of Yellow Toner 1>
Yellow toner 1 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion liquid Cy1 of cyan colorant particles was replaced with the aqueous dispersion liquid Y1 of yellow colorant particles.

<Production of Magenta Toner 1>
Magenta toner 1 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion liquid M1 of magenta colorant particles was used instead of the aqueous dispersion liquid Cy1 of cyan colorant particles.

<Production of Magenta Toner 2: High Chroma Magenta Toner>
Magenta toner 2 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion liquid Cy1 of cyan colorant particles was replaced with the aqueous dispersion liquid M2 of magenta colorant particles.

<Production of Black Toner 1>
Black toner 1 was prepared in the same manner as in the preparation of cyan toner 1, except that the aqueous dispersion liquid Cy1 of cyan colorant particles was replaced with the aqueous dispersion liquid Bk1 of black colorant particles.

<<Toner set composition>>
A toner set was prepared using the toner prepared above in the configuration shown in Table I below.

<Hue angle and saturation>
Using a commercially available full-color high-speed multifunction printer "bizhub PRO (registered trademark) C8000 (manufactured by Konica Minolta)," an image (a solid image patch measuring 2 cm long x 2 cm wide) was fixed when the amount of toner attached to the paper was 3.4 gsm of cyan toner in an environment of 20°C temperature and 50% RH, and the color gamut was evaluated.

The transfer paper used in the evaluation was "POD gloss coated paper 128 g/m ² (manufactured by Oji Paper Co., Ltd.)." The fixing temperature was +10° C. from the lowest temperature.

The "L ^* a ^* b ^* color system" is used to calculate the hue angle and saturation. The L ^* axis indicates lightness, the a ^* axis indicates the hue in the red-green direction, and the b ^* axis indicates the hue in the yellow-blue direction. ^a* and b ^* were measured using a spectrophotometer "Gretag Macbeth Spectrolino" (manufactured by Gretag Macbeth) with a D50 light source as the light source, a measurement wavelength range of 380 to 730 nm at 10 nm intervals, a viewing angle of 2°, a UV-cut filter, and a dedicated white tile for reference alignment.

The hue angle h and chroma C ^* were calculated and evaluated according to the following formula.

h=tan-1(b ^* /a ^* )
C ^* = [(a ^* ) ² + (b ^* ) ² ] ^1/2
As a result of the above evaluation, cyan toners 1 to 3 were toners that developed a cyan color with a hue angle of 220° and a chroma C ^* of 56, and cyan toners 4 and 5 were toners that developed a cyan color with a hue angle of 235° and a chroma C ^* of 56. The toner developed a cyan color at an angle of 65°.

"evaluation"
The prepared toner set was used to carry out the following evaluations.

[Image clarity and smoothness of gradation]
Using a device that was modified so that it could be set to 620 mm/sec (approximately 130 sheets/min) using a five-color modified full-color high-speed multifunction printer "bizhub PRO (registered trademark) C8000 (manufactured by Konica Minolta Business Technologies)" shown in Fig. 1, two typical landscape paintings for each season shown in Fig. 2 and a CMYK original were output in an environment of 20°C temperature and 50% RH. In this case, in Examples 1 to 7 according to the present invention, the amount of silicon phthalocyanine compound-containing toner and copper phthalocyanine compound-containing toner supplied to the cyan image was increased when the high-density region of the cyan image increased, and increased when the low-density region increased, taking into consideration the color tone, and so on. Software was created to control the supply amount according to the density region of the image in advance, and was incorporated into the image processing unit 60 of the five-color modified full-color high-speed multifunction printer, and the supply amount was controlled while detecting the image density region.

The obtained images were evaluated by 79 people on a 10-point scale for image clarity and smoothness of gradation, and the average values were ranked as follows. The transfer paper used for the evaluation was "POD gloss coated paper 128 g/ ^m2 (manufactured by Oji Paper Co., Ltd.)". A higher value indicates a clearer image and smoother gradation.

(Rank evaluation)
◎: 9.0 or more ○: 7.0 or more and less than 9.0 △: 5.0 or more and less than 7.0 ×: less than 5.0

The results in Table II confirm that the toner set of the present invention is superior to the toner set of the comparative example in terms of image clarity and smoothness of gradation. In particular, Examples 4 to 7 show that the use of a high chroma magenta toner in the toner set further improves the image clarity and smoothness of gradation of each landscape and CMYK original.

1 Electrophotographic image forming apparatus 40 Display operation section 50 Image reading section 60 Image processing section 70 Conveying section 71 Paper feeder 72 Conveying mechanism 73 Paper discharge device 80 Image forming section 81, 81Y, 81M, 81C1, 81C2, 81K Exposure device 82, 82Y, 82M, 82C1, 82C2, 82K Development device 83, 83Y, 83M, 83C1, 83C2, 83K Photoconductor drum 84, 84Y, 84M, 84C1, 84C2, 84K Charging device 85, 85Y, 85M, 85C1, 85C2, 85K Cleaning device 86, 86Y, 86M, 86C1, 86C2, 86K Primary transfer roller 87 Intermediate transfer unit 87a Intermediate transfer body 87b Support roller 87c Secondary transfer roller 87d Intermediate transfer cleaning unit 88 Fixing device 88a Heating roller 88b Fixing roller 88c Fixing belt 88d Pressure roller

Claims (5)

A toner set for developing an electrostatic image, the toner set being composed of at least two kinds of cyan toners,
The first cyan toner contains a silicon phthalocyanine compound having a structure represented by the following general formula (V),
A toner set for developing electrostatic images, wherein the second cyan toner contains a copper phthalocyanine compound.

[In the formula, Z ₁ and Z ₂ are general formula (IV) in which R ¹ , R ² and R ³ are each an alkyl group having 1 to 22 carbon atoms . Ra ₁ , Ra ₂ , Ra ₃ and Ra ₄ each independently represent a substituent. na1, na2, na3 and na4 each independently represent an integer of 0 to 4.]

[In the formula, R ¹ , R ² and R ³ each independently represent an alkyl group having 1 to 22 carbon atoms, an aryl group having 6 to 18 carbon atoms, an alkoxy group having 1 to 22 carbon atoms, or an aryloxy group having 6 to 18 carbon atoms. Note that R ¹ , R ² and R ³ may be the same group or different groups.] The toner set for developing electrostatic images according to claim 1, characterized in that the difference in hue angle between the first cyan toner and the second cyan toner at a deposition amount of 3.4 gsm is 10° or more. The toner set for developing electrostatic images according to claim 1 or 2, characterized in that the copper phthalocyanine compound has a neutral or basic substituent. An electrophotographic image forming method having at least a step of charging an image carrier, a step of forming an electrostatic image, a step of developing the electrostatic image, a step of transferring a toner image, and a step of fixing the toner image,
4. An electrophotographic image forming method, comprising using the toner set for developing an electrostatic image according to claim 1. An electrophotographic image forming apparatus comprising at least an image carrier charging means, an electrostatic image forming means, an electrostatic image developing means, a toner image transferring means, and a toner image fixing means,
4. An electrophotographic image forming apparatus, comprising the toner set for developing an electrostatic image according to claim 1.

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