JP7427964B2 - Electrophotographic image forming method - Google Patents

Description

The present invention relates to an electrophotographic image forming method.

In recent years, in image forming methods using electrophotography (hereinafter also referred to as electrophotographic image forming methods), the types of recording media to be printed on have been increasing in order to add even higher added value, and market trends are increasing. There is an extremely high demand for printing machines that can handle special recording media.

Examples of the special recording medium include colored paper, aluminum vapor-deposited paper, and transparent film. Since it is not possible to obtain sufficient color development on such a recording medium using ordinary full-color toner alone, it has been proposed to print using white toner as the bottom layer (see Patent Document 1).

In this way, when forming a full-color image on non-white media using white toner in the bottom layer, it is important to provide the white toner with hiding properties. (See Patent Documents 2 and 3).

Japanese Patent Application Publication No. 2006-220694 Japanese Patent Application Publication No. 1-105962 Japanese Patent Application Publication No. 2007-33719

However, with the techniques described in Patent Documents 2 and 3, it is said that sufficient color development cannot be obtained in production printing, which requires a higher level of high image quality and high color gamut even with special recording media. There was a problem.

The present invention has been made based on the above circumstances, and its purpose is to form an electrophotographic image that can achieve excellent color development even when printing on special recording media such as colored paper. The purpose is to provide a method.

The inventors of the present invention have conducted extensive research. As a result, an electrophotographic image forming method using chromatic toners including a white toner and a cyan toner, which uses a specific phthalocyanine compound as a main component of the colorant of the cyan toner, and dispersion of the colorant in the white toner, has been developed. The inventors have discovered that the above problems can be solved by an electrophotographic image forming method in which the diameter and the dispersed diameter of the phthalocyanine compound in the cyan toner are within a specific range, and have completed the present invention.

That is, the present invention provides an electrophotographic image forming method using a white toner and a chromatic toner including a cyan toner, the white toner containing titanium oxide as a colorant, and the cyan toner containing a colored toner. Contains a phthalocyanine compound represented by the following chemical formula 1 as the main component of the agent,

In the chemical formula 1,
M is a silicon atom, a germanium atom, or a tin atom,
Ra ₁ to Ra ₄ are each independently an electron-withdrawing substituent,
na1 to na4 are each independently an integer of 0 to 4,
Z ₁ and Z ₂ are each independently a hydroxy group, 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 chemical formula 2,

In the chemical formula 2, R ₃ to R ₅ are each independently an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,
An electrophotographic image in which Dw and Dc satisfy the following formulas 1 and 2, where Dw is the average dispersion diameter of the colorant in the white toner and Dc is the average dispersion diameter of the phthalocyanine compound in the cyan toner. This is the formation method.

According to the present invention, there can be provided an electrophotographic image forming method that can achieve excellent color development even when printing on special recording media such as colored paper.

The present invention is an electrophotographic image forming method using a white toner and a chromatic toner including a cyan toner, wherein the white toner contains titanium oxide as a colorant, and the cyan toner contains a colorant containing titanium oxide. Contains a phthalocyanine compound represented by the following chemical formula 1 as a main component,

In the chemical formula 1,
M is a silicon atom, a germanium atom, or a tin atom,
Ra ₁ to Ra ₄ are each independently an electron-withdrawing substituent,
na1 to na4 are each independently an integer of 0 to 4,
Z ₁ and Z ₂ are each independently a hydroxy group, 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 chemical formula 2,

In the chemical formula 2, R ₃ to R ₅ are each independently an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,
An electrophotographic image in which Dw and Dc satisfy the following formulas 1 and 2, where Dw is the average dispersion diameter of the colorant in the white toner and Dc is the average dispersion diameter of the phthalocyanine compound in the cyan toner. This is the formation method.

According to the electrophotographic image forming method of the present invention, excellent color development can be achieved even when printing on special recording media such as colored paper.

Although the details of why the electrophotographic image forming method of the present invention achieves the above effects are unclear, the following mechanism is considered. Note that the mechanism described below is based on speculation, and the present invention is not limited to the mechanism described below.

In the white toner according to the present invention, the colorant has a dispersion diameter within the range expressed by Formula 1 above. Within this range of dispersion diameter, a white image with high light scattering intensity, low transparency, and high hiding power can be obtained.

In the cyan toner according to the present invention, the phthalocyanine compound represented by Formula 1 above has a dispersion diameter within the range represented by Formula 2 above. If the dispersion diameter is within this range, a cyan toner with excellent coloring properties can be realized.

Furthermore, the phthalocyanine compound represented by the above chemical formula 1 has axial ligands (Z ₁ and Z ₂ ) having a bulky structure. By having an axial ligand with such a bulky structure, the phthalocyanine compound is more easily dispersed evenly in the toner particles and the fixed image, and the color development of the cyan toner is further enhanced. Further, even in the superimposed image with the white toner, which is the lowest layer, the bulky phthalocyanine compound becomes difficult to move, so that color mixing between the cyan toner and the white toner is less likely to occur. Therefore, color turbidity can be suppressed and excellent color development can be achieved.

Preferred embodiments of the present invention will be described below. In this specification, "X to Y" indicating a range means "more than or equal to X and less than or equal to Y." In addition, in this specification, unless otherwise specified, operations and measurements of physical properties, etc. are performed under conditions of room temperature (20 to 25° C.)/relative humidity of 40 to 50% RH.

In the present invention, "chromatic toner" basically refers to toner having three attributes of hue, lightness, and saturation, such as yellow toner, magenta toner, and cyan toner.

The term "achromatic toner" basically refers to a toner having only lightness without hue or saturation, such as black toner, white toner (also referred to as white toner), and gray toner.

Furthermore, in this specification, "toner base particles" constitute a base of "toner particles." The "toner base particles" contain a binder resin and a colorant, and may also contain other components such as a release agent and a charge control agent, if necessary. The "toner base particles" are called "toner particles" by adding external additives. The term "toner" refers to an aggregate of "toner particles."

[White toner, chromatic toner]
The white toner and chromatic toner according to the present invention contain toner particles in which external additives are attached to toner base particles as necessary.

[Toner base particles]
The toner base particles according to the present invention contain at least a binder resin. Further, the white toner contains a coloring agent containing titanium oxide, and the chromatic toner contains a cyan toner containing a phthalocyanine compound represented by the above chemical formula 1 as a main component.

<Binder resin>
As the binder resin, conventionally known binder resins used in toners can be used. The binder resin may be a crystalline resin or an amorphous resin. In the present specification, "the binder resin contains a crystalline resin" may refer to an embodiment in which the binder resin contains the crystalline resin itself, or a crystalline polyester polymerized segment in a hybrid crystalline polyester resin or a hybrid crystalline polyester resin. Like the crystalline polyester polymerized segment in an amorphous polyester resin, it may also be an embodiment that includes a crystalline segment contained in another resin. In addition, in this specification, "the binder resin contains an amorphous resin" may mean that the binder resin contains the amorphous resin itself, or the amorphous resin in the hybrid crystalline polyester resin. It may also be an embodiment that includes an amorphous segment contained in another resin, such as a polymerized segment or an amorphous polyester polymerized segment in a hybrid amorphous polyester resin.

[Crystalline resin]
In the present invention, a crystalline resin refers to a resin that has a clear endothermic peak rather than a step-like endothermic change in a differential calorific value curve measured with a differential scanning calorimeter (DSC). Specifically, a clear endothermic peak means a peak whose half-value width is within 15° C. when measured at a temperature increase rate of 10° C./min in DSC measurement. For DSC measurement, a differential scanning calorimeter (PerkinElmer: Diamond DSC) is used. The temperature of the detection part of this device is corrected using the melting points of indium and zinc, and the heat of fusion of indium is used to correct the calorific value. Use. Regarding a resin having a structure in which other components are copolymerized with the main chain of a crystalline resin, if it shows a clear endothermic peak as described above, it corresponds to the crystalline resin in the present invention.

The total amount of the toner other than external additives, that is, the content of crystalline resin relative to the toner base particles, is preferably 1 to 40% by mass, more preferably 5 to 30% by mass, from the viewpoint of obtaining sufficient low-temperature fixability and heat-resistant storage stability. Mass%. Within this range, it is possible to improve the sharp melting properties of the binder resin and improve the low-temperature fixing properties of the toner, while suppressing a decrease in heat resistance. Further, when the binder resin includes an amorphous vinyl resin, the crystalline resin can be uniformly dispersed in the toner base particles, and crystallization can be sufficiently suppressed.

The crystalline resin preferably has a number average molecular weight (Mn) of 3,000 or more and 12,500 or less, more preferably 4,000 or more and 11,000 or less, from the viewpoint of low-temperature fixability and gloss stability. The weight average molecular weight (Mw) of the crystalline resin is preferably 10,000 or more and 100,000 or less, more preferably 15,000 or more and 80,000 or less, and even more preferably 20,000 or more and 50,000 or less. When Mw and Mn are within the above ranges, the strength of the fixed image increases and the thermal stability of the toner can also be ensured. Further, the sharp melting properties of the toner are easily developed, and the fixing temperature can be kept low. The above Mw and Mn can be determined from the molecular weight distribution measured by gel permeation chromatography (GPC) as described below.

(Method for measuring molecular weight of crystalline resin)
The sample was added to tetrahydrofuran (THF) at a concentration of 0.1 mg/mL, heated to 40°C to completely dissolve it, and then treated with a membrane filter with a pore size of 0.2 μm to remove the sample solution ( sample). Thereafter, measurements are performed under the following conditions. Specifically, using a GPC device HLC-8220GPC (manufactured by Tosoh Corporation) and a column "TSKgelSuperH3000" (manufactured by Tosoh Corporation), THF was used as a carrier solvent (eluent) at a flow rate of 0.25°C while maintaining the column temperature at 40°C. Flow at 6 mL/min. 100 μL of the prepared sample solution is injected into the GPC device together with the carrier solvent, and the sample is detected using a differential refractive index detector (RI detector). Then, the molecular weight distribution of the sample is calculated using a calibration curve measured using 10 points of monodisperse polystyrene standard particles. In addition, in data analysis, if a peak caused by the filter is confirmed, a baseline is set up to just before the peak, and the analyzed data is taken as the molecular weight of the sample.

Measurement model: Tosoh Corporation GPC device HLC-8220GPC
Column: “TSKgelSuperH3000” manufactured by Tosoh Corporation
Eluent: THF
Temperature: Column constant temperature bath 40.0℃
Flow rate: 0.6ml/min
Concentration: 0.1 mg/mL (0.1 wt/vol%)
Calibration curve: Standard polystyrene sample manufactured by Tosoh Corporation Injection volume: 100μl
Solubility: Completely dissolved (heated at 40℃)
Pretreatment: Filtration with a 0.2 μm filter Detector: Differential refractometer (RI).

The crystalline resins may be used alone or in combination of two or more. Examples of the crystalline resin according to the present invention include crystalline polyolefin resin, crystalline polydiene resin, crystalline polyester resin, crystalline polyamide resin, crystalline polyurethane resin, crystalline polyacetal resin, crystalline polyethylene terephthalate resin, crystalline Examples include polybutylene terephthalate resin, crystalline polyphenylene sulfide resin, crystalline polyetheretherketone resin, and crystalline polytetrafluoroethylene resin. Among these, crystalline polyester resins are preferred from the viewpoint of ease of use and sufficient low-temperature fixability. Crystalline polyester resin is preferable because it melts during heat fixing and acts as a plasticizer for the amorphous resin, thereby improving low-temperature fixability.

From the viewpoint of improving low-temperature fixability, it is preferable that the binder resin of the white toner and the chromatic toner includes a crystalline resin, and the crystalline resin is a crystalline polyester resin. Here, among the white toner and the chromatic toner, from the viewpoint of further improving low-temperature fixability, at least the chromatic toner contains a crystalline resin as a binder resin, and the crystalline resin is a crystalline polyester resin. It is preferable that there be. In addition, from the viewpoint of improving low-temperature fixability and heat-resistant storage stability of the toner, it is preferable to use a combination of a crystalline polyester resin and an amorphous resin as a binder resin for a chromatic toner. It is more preferable to use it in combination with resin.

<Crystalline polyester resin>
Crystalline polyester resin is a known polyester resin obtained by the polycondensation reaction of divalent or higher carboxylic acid (polyvalent carboxylic acid) and divalent or higher alcohol (polyhydric alcohol). (DSC) refers to a resin that has a clear endothermic peak rather than a step-like endothermic change. Specifically, a clear endothermic peak is one in which the half width of the endothermic peak is within 15 °C when measured at a temperature increase rate of 10 °C/min in differential scanning calorimetry (DSC) described in the examples. It means peak. Such crystalline polyester resins are easy to use and can provide sufficient low-temperature fixability. Further, since the crystalline polyester resin melts during heat fixing and acts as a plasticizer for the amorphous resin, low-temperature fixability can be improved. Further, the crystalline polyester resins may be used alone or in combination of two or more.

The crystalline polyester resin is not particularly limited as long as it is as defined above. For example, for a resin having a structure in which other components are copolymerized on the main chain of the crystalline polyester resin, a clear endothermic peak as described above may be used. If it shows this, it corresponds to the crystalline polyester resin as used in the present invention.

From the viewpoint of low-temperature fixability, the crystalline polyester resin preferably has a number average molecular weight (Mn) of 3,000 or more and 12,500 or less, more preferably 4,000 or more and 11,000 or less. The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 10,000 or more and 100,000 or less, more preferably 12,000 or more and 80,000 or less, and even more preferably 14,000 or more and 50,000 or less. Within this range, the resulting toner particles do not have a low melting point as a whole and have excellent blocking resistance and low-temperature fixability. The number average molecular weight (Mn) and weight average molecular weight (Mw) can be measured by gel permeation chromatography (GPC) in the same manner as described above.

The acid value (AV) of the crystalline polyester resin is preferably 5 to 70 mgKOH/g. The acid value can be measured according to the method described in JIS K2501:2003.

When the binder resin according to the present invention contains a crystalline polyester resin, the content of the crystalline polyester resin based on the total amount of the binder resin is preferably 2 to 20% by mass, more preferably 5 to 20% by mass, and 7 to 15% by mass. Mass % is more preferred. When the content of the crystalline polyester resin is 2% by mass or more, low-temperature fixability is excellent. If the content of the crystalline polyester resin is 20% by mass or less, the heat resistance will be excellent.

Crystalline polyester resin is formed from a polyhydric carboxylic acid component and a polyhydric alcohol component. The valences of the polyhydric carboxylic acid component and the polyhydric alcohol component are each preferably 2 to 3, particularly preferably 2.

(Polyhydric carboxylic acid)
A polyhydric carboxylic acid is a compound containing two or more carboxy groups in one molecule. Examples of polycarboxylic acids include dicarboxylic acids. These dicarboxylic acids may be used alone or in combination of two or more. The dicarboxylic acid is preferably an aliphatic dicarboxylic acid, and may further contain an aromatic dicarboxylic acid. The aliphatic dicarboxylic acid is preferably a linear type from the viewpoint of improving the crystallinity of the crystalline polyester resin.

Examples of the above aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid (hexanedioic acid), pimelic acid, suberic acid (octanedioic acid), azelaic acid, sebacic acid (decanedioic acid). n-dodecylsuccinic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (tetradecanedioic acid) ), saturated aliphatic dicarboxylic acids such as 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, lower alkyl esters of these, and Contains acid anhydrides. Among these, aliphatic dicarboxylic acids having 6 to 16 carbon atoms are preferred, and aliphatic dicarboxylic acids having 10 to 14 carbon atoms are more preferred, from the viewpoint of easily achieving both low-temperature fixability and transferability.

Examples of the aromatic dicarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, t-butyl isophthalic acid, 2,6-naphthalenedicarboxylic acid and 4,4'-biphenyldicarboxylic acid. Among these, terephthalic acid, isophthalic acid, or t-butyl isophthalic acid is preferred from the viewpoint of easy availability and emulsification.

In addition to the above, examples of polyvalent carboxylic acids include alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, trivalent or higher polyvalent carboxylic acids such as trimellitic acid, and pyromellitic acid; and anhydrides of these carboxylic acid compounds; Alternatively, alkyl esters having 1 to 3 carbon atoms may be mentioned.

The polyhydric carboxylic acids described above may be used alone or in combination of two or more.

The content of the aliphatic dicarboxylic acid-derived structural units relative to the dicarboxylic acid-derived structural units in the crystalline polyester resin is preferably 50 mol% or more from the viewpoint of ensuring sufficient crystallinity of the crystalline polyester resin. , more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%.

(Polyhydric alcohol)
A polyhydric alcohol is a compound containing two or more hydroxy groups in one molecule. Examples of polyhydric alcohol components include diols. Diols can be used alone or in combination of two or more. The diol is preferably an aliphatic diol, but may further contain other diols. The aliphatic diol is preferably a linear type from the viewpoint of improving the crystallinity of the crystalline polyester resin.

Examples of the aliphatic diols include ethylene glycol, propylene glycol (1,2-propanediol), 1,3-propanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 1, 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11 -undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol and 1,20-eicosanediol. Among these, aliphatic diols having 2 to 20 carbon atoms are preferred, and aliphatic diols having 4 to 12 carbon atoms are more preferred, from the viewpoint of easily achieving both low-temperature fixability and transferability.

Examples of other diols include diols with double bonds and diols with sulfonic acid groups. Specifically, examples of diols having double bonds include 1,4-butene diol, 2-butene-1,4-diol, 3-butene-1,6-diol and 4-butene-1,8-diol. -Contains diols.

Examples of trivalent or higher polyhydric alcohols include glycerin, pentaerythritol, trimethylolpropane, sorbitol, and the like.

Polyhydric alcohols can be used alone or in combination of two or more.

The content of aliphatic diol-derived structural units relative to diol-derived structural units in the crystalline polyester resin is preferably 50 mol% or more, and 70 mol% or more, from the viewpoint of improving the low-temperature fixing properties of the toner. is more preferable, more preferably 80 mol% or more, and particularly preferably 100 mol%.

The ratio of the above-mentioned diol and the above-mentioned dicarboxylic acid in the monomer of the crystalline polyester resin is 1.0/in the equivalent ratio [OH]/[COOH] of the hydroxy group [OH] of the diol and the carboxy group [COOH] of the dicarboxylic acid. It is preferably 2.0 to 2.0/1.0, more preferably 1.0/1.5 to 1.5/1.0, and 1.0/1.3 to 1.3. /1.0 is particularly preferred.

The monomer constituting the crystalline polyester resin preferably contains a linear aliphatic monomer in an amount of 50% by mass or more, more preferably 80% by mass or more. When an aromatic monomer is used, the melting point (temperature at the top of the endothermic peak) of the crystalline polyester resin often becomes high, and when a branched aliphatic monomer is used, the crystallinity increases. Often low. Therefore, it is preferable to use a linear aliphatic monomer as the monomer.

The crystalline polyester resin can be synthesized by polycondensing (esterifying) the polyhydric carboxylic acid and polyhydric alcohol using a known esterification catalyst.

Catalysts that can be used in the synthesis of crystalline polyester resins may be used alone or in combination; examples thereof include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum; Included are metal compounds such as zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds.

Specifically, examples of tin compounds include dibutyltin oxide, tin octylate, tin dioctylate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetra-n-butyl titanate (titanium tetrabutoxide, Ti(O-n-Bu) ₄ ), tetraisopropyl titanate, tetramethyl titanate, tetrastearyl titanate; polyhydroxy titanium stearate, etc. and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolaminate. Examples of germanium compounds include germanium dioxide, and examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributyl aluminate.

The polymerization temperature of the crystalline polyester resin is preferably 150°C or more and 250°C or less. Further, the polymerization time is preferably 0.5 hours or more and 10 hours or less. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

Note that the structure and constituent monomers of the crystalline resin affect the degree of crystallinity and heat of fusion of the crystalline resin. From the viewpoint of adjusting the degree of crystallinity of the crystalline resin to a preferable range for fixing, the crystalline resin is preferably a hybrid crystalline polyester resin described below. Hybrid crystalline polyester resins can be used alone or in combination of two or more. Further, the hybrid crystalline polyester resin may be substituted for the entire amount or a portion of the crystalline polyester resin.

(Hybrid crystalline polyester resin)
In the present invention, the crystalline resin is preferably a crystalline polyester resin. Further, the crystalline resin is preferably a hybrid crystalline polyester resin containing a structure of a crystalline polyester resin and a structure of an amorphous resin. The hybrid crystalline polyester resin has a hybrid structure, which increases its compatibility with the amorphous resin and allows it to maintain a finer dispersion state in the binder resin, which improves the sharp melting properties of the crystalline resin during fixing. and improves low-temperature fixing properties. Further, when the toner base particles have a core-shell structure, it is preferable that the core portion contains a hybrid crystalline polyester resin, since this makes it difficult for the crystalline polyester resin to be exposed on the surface of the toner particles.

A hybrid crystalline polyester resin is a resin having a structure in which a crystalline polyester polymerized segment and an amorphous polymerized segment other than the polyester polymerized segment are chemically bonded. The crystalline polyester polymerized segment means a portion derived from a crystalline polyester resin. That is, it means a molecular chain having the same chemical structure as the molecular chain constituting the crystalline polyester resin described above. Moreover, the amorphous polymerized segment means a portion derived from an amorphous resin. That is, it means a molecular chain having the same chemical structure as the molecular chain constituting the amorphous resin described later.

(Molecular weight of hybrid crystalline polyester resin)
The weight average molecular weight (Mw) of the hybrid crystalline polyester resin is preferably 20,000 or more and 50,000 or less. By setting the Mw of the hybrid crystalline polyester resin to 50,000 or less, sufficient low-temperature fixability can be obtained. On the other hand, by setting the Mw of the hybrid crystalline polyester resin to 20,000 or more, excessive compatibility between the hybrid resin and the amorphous resin during toner storage is suppressed, and images due to fusion of toner particles are suppressed. Defects can be effectively suppressed. The method for measuring the molecular weight of crystalline resins described above can be applied to such molecular weight measurement.

The number average molecular weight (Mn) of the hybrid crystalline polyester resin is preferably 3,000 or more and 12,500 or less, and 4,000 or more and 11,000 or less, from the viewpoint of reliably achieving both sufficient low-temperature fixability and excellent long-term storage stability. It is more preferable. By setting the Mn of the hybrid crystalline polyester resin to 12,500 or less, sufficient low-temperature fixability can be obtained. On the other hand, by setting the Mn of the hybrid crystalline polyester resin to 3000 or more, excessive compatibility between the hybrid resin and the amorphous resin during toner storage is suppressed, and images due to fusion of the toners are suppressed. Defects can be effectively suppressed. The method for measuring the molecular weight of crystalline resins described above can be applied to such molecular weight measurement.

When the binder resin according to the present invention includes a hybrid crystalline polyester resin, the content of the hybrid crystalline polyester resin with respect to the total mass of the binder resin is preferably 2% by mass or more and 20% by mass or less, and 5% by mass or more and 20% by mass or less. It is more preferably 7% by mass or more and 15% by mass or less. When the content of the hybrid crystalline polyester resin is 2% by mass or more, low-temperature fixability is excellent. When the content of the hybrid crystalline polyester resin is 20% by mass or less, heat resistance is excellent.

There are no particular restrictions on the chemically bonded structure, and it may be a block copolymer or a graft copolymer, but crystalline polyester polymerization with an amorphous polymer segment as the main chain A structure in which segments are grafted is preferred. That is, the hybrid crystalline polyester resin is preferably a graft copolymer having the amorphous polymer segment as a main chain and the crystalline polyester polymer segment as a side chain.

The hybrid crystalline polyester resin having such a structure will be explained below.

<Crystalline polyester polymerization segment>
The crystalline polyester polymerized segment refers to a portion derived from a crystalline polyester resin. In other words, it refers to a molecular chain with the same chemical structure as that constituting the crystalline polyester resin.

The crystalline polyester polymerization segment is similar to the above-described crystalline polyester resin, and is a portion derived from a known polyester resin obtained by the polycondensation reaction of the above-mentioned polyhydric carboxylic acid and polyhydric alcohol. The crystalline polyester polymerized segment can be synthesized from a polycarboxylic acid and a polyhydric alcohol in the same manner as the crystalline polyester resin described above. The polyhydric carboxylic acid component and polyhydric alcohol component that make up the crystalline polyester polymerized segment are the same as the "polyhydric carboxylic acid" and "polyhydric alcohol" items explained for the crystalline polyester resin above. Therefore, the explanation will be omitted.

The content of the crystalline polyester polymerized segment is preferably 80% by mass or more and 98% by mass or less, and more preferably 90% by mass or more and 95% by mass or less based on the total mass of the hybrid crystalline polyester resin. By setting it as the said range, sufficient crystallinity can be provided to hybrid crystalline polyester resin. Note that the constituent components of each segment in the hybrid crystalline polyester resin (or toner) and their contents can be determined by, for example, nuclear magnetic resonance (NMR) measurement, methylation reaction pyrolysis gas chromatography/mass spectrometry (Py-GC). /MS) and other known analysis methods.

It is preferable that the crystalline polyester polymerized segment further contains a monomer having an unsaturated bond as a monomer component from the viewpoint of introducing into the segment a chemical bonding site with the amorphous polymerized segment. Monomers having unsaturated bonds include, for example, polyhydric carboxylic acids having double bonds such as methylene succinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, and 3-octenedioic acid; 2-butene-1 , 4-diol, 3-butene-1,6-diol and 4-butene-1,8-diol. The content of the structural unit derived from the monomer having an unsaturated bond in the crystalline polyester polymerized segment is preferably 0.5% by mass or more and 20% by mass or less.

In addition, a functional group such as a sulfonic acid group, a carboxy group, or a urethane group may be further introduced into the hybrid crystalline polyester resin. The functional group may be introduced into the crystalline polyester polymerization segment or into the amorphous polymerization segment.

The hybrid crystalline polyester resin preferably has a graft copolymer structure containing an amorphous polymer segment in addition to the crystalline polyester polymer segment. This structure makes it easy to control the orientation of the crystalline polyester polymerized segment, and it is possible to impart sufficient crystallinity to the hybrid crystalline polyester resin.

<Amorphous polymerization segment>
The amorphous polymerized segment refers to a portion derived from an amorphous resin. In other words, it refers to a molecular chain with the same chemical structure as that constituting the amorphous resin. The amorphous polymer segment increases the affinity between the amorphous resin that can be included in the binder resin in the present invention and the hybrid crystalline polyester resin. This makes it easier for the hybrid resin to be incorporated into the amorphous resin, further improving the toner charging uniformity. The components of the amorphous polymerized segment and their content in the hybrid crystalline polyester resin (or toner) can be determined by, for example, nuclear magnetic resonance (NMR) measurement, methylation reaction pyrolysis gas chromatography/mass spectrometry (Py- It can be identified by using a known analysis method such as GC/MS).

An amorphous polymer segment is a polymer segment that does not have a melting point and has a relatively high glass transition temperature (Tg) when differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the segment. It is. Like the amorphous resin, the amorphous polymerized segment preferably has a glass transition temperature (Tg) of 30° C. or more and 80° C. or less, and 40° C. or more and 65° C. or less in the first temperature raising process of DSC. It is more preferable that Note that the glass transition temperature (Tg) can be measured in the same manner as the Tg of an amorphous resin.

The amorphous polymer segment is composed of the same type of resin as the amorphous resin (for example, vinyl resin) contained in the binder resin, which increases the affinity with the binder resin and improves the uniformity of toner charging. It is preferable from the viewpoint of increasing the By adopting such a form, the affinity between the hybrid crystalline polyester resin and the amorphous resin is further improved. "Resins of the same type" means resins that have characteristic chemical bonds in their repeating units.

“Characteristic chemical bonds” are “polymer According to "classification". Namely, polyacrylic, polyamide, polyanhydride, polycarbonate, polydiene, polyester, polyhaloolefin, polyimide, polyimine, polyketone, polyolefin, polyether, polyphenylene, polyphosphazene, polysiloxane, polystyrene, polysulfide, polysulfone, polyurethane, polyurea. The chemical bonds that constitute the polymers classified by a total of 22 types, including polyvinyl, polyvinyl, and other polymers, are referred to as "characteristic chemical bonds."

In addition, in the case where the resin is a copolymer, "the same type of resin" refers to the chemical structure of multiple monomer species constituting the copolymer, when the monomer species having the above chemical bond is used as a constituent unit, Refers to resins that share a common chemical bond. Therefore, even if the properties of the resins themselves are different, or the molar ratios of the monomers constituting the copolymer are different, as long as they have a characteristic chemical bond in common, the same type of Considered as resin.

For example, a resin (or polymerized segment) formed by styrene, butyl acrylate, and acrylic acid and a resin (or polymerized segment) formed by styrene, butyl acrylate, and methacrylic acid have at least the chemical bonds that constitute polyacrylic. Therefore, these are the same type of resin. To further illustrate, a resin (or polymerized segment) formed by styrene, butyl acrylate, and acrylic acid and a resin (or polymerized segment) formed by styrene, butyl acrylate, acrylic acid, terephthalic acid, and fumaric acid are mutually exclusive. As a common chemical bond, it has at least a chemical bond that constitutes polyacrylic. Therefore, these are the same type of resin.

The content of the amorphous polymer segment in the hybrid crystalline polyester resin is preferably 2% by mass or more and 20% by mass or less, and 3% by mass from the viewpoint of imparting sufficient crystallinity to the hybrid crystalline polyester resin. % or more and 15% by mass or less, further preferably 5% by mass or more and 10% by mass or less, and particularly preferably 7% by mass or more and 9% by mass or less.

The resin component constituting the amorphous polymerized segment is not particularly limited, and examples thereof include a vinyl polymerized segment, a urethane polymerized segment, a urea polymerized segment, and the like. Among these, vinyl polymerized segments are preferred because their thermoplasticity can be easily controlled. In addition, when using a vinyl polymerized segment, by using vinyl resin, which is preferable among amorphous resins, in the binder resin in such a way that it accounts for the largest proportion, the compatibility with the vinyl resin increases and can maintain a more finely dispersed state. This is preferable because the sharp melting properties of the crystalline resin are better exhibited during fixing. Vinyl polymerized segments can be synthesized in the same manner as vinyl resins.

The vinyl polymerized segment is not particularly limited as long as it is a polymerized vinyl compound, and examples thereof include acrylic ester polymerized segments, styrene-acrylic ester polymerized segments, and ethylene-vinyl acetate polymerized segments. These may be used alone or in combination of two or more.

Among the above-mentioned vinyl polymerization segments, styrene-acrylic acid ester polymerization segments (also simply referred to as styrene-acrylic polymerization segments) are preferred in consideration of plasticity during heat fixing. Therefore, below, a styrene acrylic polymerization segment will be explained as an amorphous polymerization segment.

[Styrene acrylic polymerization segment]
The styrene-acrylic polymerized segment is formed by addition polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. In addition to styrene represented by the structural formula CH ₂ ═CH—C ₆ H ₅ , the styrene monomer herein includes those having a structure having a known side chain or functional group in the styrene structure. In addition, the (meth)acrylic acid ester monomer mentioned here includes acrylic acid ester compounds represented by CH ₂ =CHCOOR (R is an alkyl group), methacrylic acid ester compounds, acrylic acid ester derivatives, and methacrylic acid ester compounds. It includes an ester compound having a known side chain or functional group in its structure, such as an acid ester derivative.

Specific examples of styrene monomers and (meth)acrylic acid ester monomers that can form styrene-acrylic polymerized segments are shown below, and those that can be used to form the styrene-acrylic polymerized segments used in the present invention are shown below. is not limited to:

(Styrene monomer)
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, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, and the like. These styrene monomers can be used alone or in combination of two or more.

((meth)acrylic acid ester monomer)
Specific examples of (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl Acrylic acid ester monomers such as acrylate, lauryl acrylate, phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate , lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and other methacrylic acid esters. Specifically, methyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate are preferred.

In addition, in this specification, "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer", for example, "(meth)acrylic acid ester monomer" ) "Methyl acrylate" is a general term for "methyl acrylate" and "methyl methacrylate."

These acrylic ester monomers or methacrylic ester monomers can be used alone or in combination of two or more. That is, forming a copolymer using a styrene monomer and two or more types of acrylic acid ester monomers, and forming a copolymer using a styrene monomer and two or more types of methacrylic acid ester monomers. It is possible to form a copolymer, or to form a copolymer by using a styrene monomer, an acrylic acid ester monomer, and a methacrylic acid ester monomer together.

The content of the structural unit derived from the styrene monomer in the styrene-acrylic polymerized segment is 40% by mass or more and 90% by mass or less based on the total mass of the styrene-acrylic polymerized segment to control the plasticity of the hybrid resin. This is preferable from the viewpoint that it is easy to do so. In addition, from the same viewpoint, the content of the structural unit derived from the (meth)acrylic acid ester monomer in the styrene-acrylic polymerization segment is 10% by mass or more and 60% by mass or less with respect to the total mass of the styrene-acrylic polymerization segment. It is preferable that

Furthermore, the styrene-acrylic polymer segment is preferably addition-polymerized with a compound for chemically bonding to the crystalline polyester polymer segment, in addition to the styrene monomer and (meth)acrylic acid ester monomer. Specifically, it is preferable to use a compound that forms an ester bond with a hydroxy group [-OH] derived from a polyhydric alcohol component or a carboxy group [-COOH] derived from a polyhydric carboxylic acid component contained in the crystalline polyester polymerization segment. . Therefore, the styrene acrylic polymerization segment is a compound that can be addition-polymerized with the above-mentioned styrene monomer and (meth)acrylic acid ester monomer and has a carboxy group [-COOH] or a hydroxy group [-OH]. It is preferable that the compound is further polymerized.

Examples of such compounds include 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; 2-hydroxy Ethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate and compounds having a hydroxy group such as polyethylene glycol mono(meth)acrylate.

The content of the structural units derived from the above compound in the styrene-acrylic polymerization segment is determined based on the total mass of the styrene-acrylic polymerization segment from the viewpoint of introducing chemical bonding sites with the crystalline polyester polymerization segment into the styrene-acrylic polymerization segment. The content is preferably 0.5% by mass or more and 20% by mass or less.

The method for forming the styrene-acrylic polymerization segment is not particularly limited, and examples thereof include a method of polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Specific examples of oil-soluble polymerization initiators include azo or diazo polymerization initiators and peroxide polymerization initiators shown below. If necessary, for example, known chain transfer agents such as n-octylmercaptan and n-octyl-3-mercaptopropionate may be used.

(Azo or diazo polymerization initiator)
Examples of azo or diazo polymerization initiators include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1 -carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, and the like.

(Peroxide polymerization initiator)
Peroxide polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxy carbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-butyl peroxypivalate. , dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, tris-(t-butylperoxy)triazine, etc. can be mentioned.

Furthermore, when forming resin particles by emulsion polymerization, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide, and the like.

The polymerization temperature varies depending on the type of monomer and polymerization initiator used, but is preferably 50 to 100°C, more preferably 55 to 90°C. Further, the polymerization time varies depending on the type of monomer and polymerization initiator used, but is preferably 1 to 12 hours, for example.

(Method for producing hybrid crystalline polyester resin)
The method for producing the hybrid crystalline polyester resin contained in the binder resin according to the present invention is capable of forming a polymer having a structure in which the crystalline polyester polymerization segment and the amorphous polymerization segment are chemically bonded. There are no particular limitations as long as it is a method. As a specific method for producing the hybrid crystalline polyester resin, for example, it can be produced by the first to third production methods shown below.

(First manufacturing method)
The first production method is a method of producing a hybrid crystalline polyester resin by performing a polymerization reaction to synthesize a crystalline polyester polymerization segment in the presence of a previously synthesized amorphous polymerization segment.

(Second manufacturing method)
The second manufacturing method is a method of manufacturing a hybrid crystalline polyester resin by forming a crystalline polyester polymerized segment and an amorphous polymerized segment, respectively, and then combining them.

(Third manufacturing method)
The third manufacturing method is a method of manufacturing a hybrid crystalline polyester resin by performing a polymerization reaction to synthesize an amorphous polymerized segment in the presence of a crystalline polyester polymerized segment synthesized in advance.

Among the first to third production methods described above, a hybrid crystalline polyester resin having a structure in which a crystalline polyester polymer chain (crystalline polyester resin chain) is grafted onto an amorphous polymer chain (amorphous resin chain) is formed. The first manufacturing method is preferable from the viewpoints of ease of production and simplification of the production process. In the first manufacturing method, since the amorphous polymerized segments are formed in advance and then the crystalline polyester polymerized segments are bonded, the orientation of the crystalline polyester polymerized segments tends to be uniform. Therefore, it is preferable from the viewpoint of reliably synthesizing a hybrid crystalline polyester resin suitable for the toner according to the present invention.

[Amorphous resin]
The white toner and chromatic toner according to the present invention preferably contain an amorphous resin as a binder resin. The amorphous resin is a resin that does not have the above-mentioned crystallinity. By including the amorphous resin in the toner, the crystalline resin and the amorphous resin are compatible with each other during heat fixing, and the low-temperature fixability of the toner is improved.

The amorphous resin does not have a melting point in the endothermic curve obtained when toner particles or the amorphous resin are subjected to differential scanning calorimetry (DSC) (i.e., the above-mentioned clear endothermic curve when the temperature is increased). It is a resin with no peaks) and a relatively high glass transition temperature (Tg).

In addition, it is preferable that Tg of the said amorphous resin is 35 degreeC or more and 80 degrees C or less, and it is more preferable that it is 45 degreeC or more and 65 degrees C or less. In particular, it is preferable for the chromatic toner to have a core-shell structure because it is possible to maintain a high balance between low-temperature fixability, hot offset resistance, and heat resistance. Furthermore, if the core of the core-shell structure contains particles of amorphous resin (e.g., amorphous vinyl resin containing a release agent) having a three-layer structure containing a release agent (wax), the outermost layer of the particles is The Tg of the amorphous resin is preferably in the range of 55° C. or more and 65° C. or less from the viewpoint of maintaining a higher balance between low-temperature fixability and hot offset resistance.

The glass transition temperature can be measured according to the method specified in ASTM D3418-82 (DSC method). For the measurement, a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer), a TAC7/DX thermal analyzer controller (manufactured by PerkinElmer), or the like can be used.

The weight average molecular weight (Mw) of the amorphous resin is preferably 20,000 or more and 150,000 or less, and more preferably 25,000 or more and 130,000 or less, from the viewpoint of easily controlling the plasticity of the amorphous resin. Further, the number average molecular weight (Mn) of the amorphous resin is preferably 5,000 or more and 150,000 or less, and more preferably 8,000 or more and 70,000 or less, from the viewpoint of easily controlling the plasticity of the amorphous resin. The molecular weight of the amorphous resin can be measured in the same manner as the method for measuring the molecular weight of the crystalline resin described above.

The mass ratio of the amorphous resin to the crystalline resin (amorphous resin/crystalline resin) is preferably from 98/2 to 80/20, more preferably from 95/5 to 80/20. . When the mass ratio is within the above range, the crystalline resin is not exposed on the surface of the toner particles to be formed, or even if it is exposed, the amount thereof is extremely small, and the amount is sufficient to achieve low-temperature fixability. of crystalline resins can be incorporated into the toner particles.

It is preferable that the amorphous resin is used as a binder resin together with the above-mentioned crystalline resin to constitute toner base particles. By including the amorphous resin, it is possible to obtain an appropriate fixed image strength and image gloss, and also to have the advantage that good charging characteristics can be imparted even in an environment where temperature and humidity fluctuate. The amorphous resin according to the present invention may be used alone or in combination of two or more. Further, as examples of the amorphous resin, amorphous vinyl resin, amorphous urethane resin, amorphous urea resin, amorphous polyester resin (including hybrid amorphous polyester resin), etc. are preferably mentioned. These amorphous resins can be obtained by known synthesis methods or commercially available products. Further, when the toner base particles according to the present invention have a core-shell structure, from the viewpoint of controllability of the dispersion state in the toner base particles and charging characteristics, an amorphous vinyl resin and a crystalline polyester resin constitute the core part. It is preferable that the hybrid amorphous polyester resin constitutes the shell layer.

In this embodiment, the amorphous resin preferably includes an amorphous vinyl resin (also simply referred to as vinyl resin) and an amorphous polyester resin from the viewpoint of easy control of thermoplasticity.

The vinyl resin and the amorphous polyester resin will be explained below.

In the present invention, it is preferable that vinyl resin is the main component in the binder resin. This is because the vinyl resin is the main component in combination with the crystalline polyester resin, making it easy to adjust whether they are compatible or incompatible. This is because a more finely dispersed state can be maintained, and the sharp melting properties of the crystalline polyester resin can be better exhibited during fixing. From this viewpoint, the content of the vinyl resin is preferably more than 50% by mass, more preferably 70% by mass or more, and even more preferably 75% by mass or more, based on the total mass of the binder resin. By using vinyl resin as the main component, it is easy to adjust the compatibility with the crystalline resin, and it is possible to maintain a high balance between low-temperature fixability and heat resistance of the toner. The upper limit of the vinyl resin content is not particularly limited, but is preferably 98% by mass or less, more preferably 95% by mass or less, and even more preferably 93% by mass of the binder resin.

In the present invention, the binder resin preferably contains a vinyl resin as a main component and contains an amorphous polyester resin. This is because when adjusting the compatibility with the crystalline resin, the inclusion of the amorphous polyester resin makes it easier to adjust the compatibility. In addition, when considering the core-shell structure, amorphous polyester resin has better heat resistance, so toner with a core-shell structure that has a shell made of amorphous polyester resin has better heat resistance and low-temperature fixing properties. It is particularly excellent in terms of compatibility with From this viewpoint, the content of the amorphous polyester resin in the toner base particles is preferably 2% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 18% by mass or less, and 4% by mass or more and 15% by mass or less. More preferred.

(vinyl resin)
In the present invention, the vinyl resin is, for example, a polymer of a vinyl compound, and examples thereof include acrylic ester resin, styrene-acrylic ester resin, ethylene-vinyl acetate resin, and the like. These may be used alone or in combination of two or more. Among these, styrene-acrylic acid ester resin (styrene acrylic resin) is preferred from the viewpoint of plasticity during heat fixing. The styrene acrylic resin will be explained below.

Styrene acrylic resin is formed by addition polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. Styrene monomers include styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ as well as styrene derivatives having known side chains and functional groups in the styrene structure.

In addition, the (meth)acrylic acid ester monomer is CH(R ¹ )=CHCOOR ² (R ¹ represents a hydrogen atom or a methyl group, and R ² represents an alkyl group having 1 to 24 carbon atoms). In addition to the expressed acrylic esters and methacrylic esters, these esters also include acrylic ester derivatives and methacrylic ester derivatives having known side chains or functional groups in their structures.

Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p- Included are tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene and pn-dodecylstyrene.

Examples of (meth)acrylic ester monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl Acrylic acid ester monomers such as acrylate and phenyl acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate , phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, and other methacrylic acid ester monomers;

The above styrene monomer and (meth)acrylic acid ester monomer may be used alone or in combination of two or more. For example, forming a copolymer using a styrene monomer and two or more types of acrylic acid ester monomers, or forming a copolymer using a styrene monomer and two or more types of methacrylic acid ester monomers. It is possible to form a copolymer, and to form a copolymer by using a styrene monomer and an acrylic ester monomer and a methacrylic ester monomer together.

From the viewpoint of controlling the plasticity of the amorphous resin, the content of structural units derived from styrene monomer in the amorphous resin is preferably 40% by mass or more and 90% by mass or less. Further, the content of structural units derived from the (meth)acrylic acid ester monomer in the amorphous resin is preferably 10% by mass or more and 60% by mass or less.

The styrene acrylic resin may further contain a structural unit derived from a monomer other than the styrene monomer and (meth)acrylic acid ester monomer. The other monomer is preferably a compound that forms an ester bond with a hydroxy group (-OH) derived from a polyhydric alcohol or a carboxy group (-COOH) derived from a polyhydric carboxylic acid. That is, the vinyl resin can be addition-polymerized to the above-mentioned styrene monomer and (meth)acrylic acid ester monomer, and is formed by further polymerizing a compound having a carboxyl group or a hydroxyl group (ampholytic compound). Preferably, it is a polymer.

Examples of the above amphoteric compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester; 2-hydroxy Ethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate , compounds having a hydroxyl group such as polyethylene glycol mono(meth)acrylate;

The content of the structural unit derived from the amphoteric compound in the styrene acrylic resin is preferably 0.5% by mass or more and 20% by mass or less.

Styrene acrylic resin can be synthesized by a method of polymerizing monomers using a known oil-soluble or water-soluble polymerization initiator. Examples of oil-soluble polymerization initiators include azo or diazo polymerization initiators and peroxide polymerization initiators. Specifically, since it is the same as the method for forming the styrene-acrylic polymerized segment described above, the explanation will be omitted here.

The weight average molecular weight (Mw) of the styrene acrylic resin is within the range of 20,000 to 150,000, and the number average molecular weight (Mn) is within the range of 5,000 to 150,000 to improve low temperature fixing properties. This is preferable from the viewpoint of achieving both hot offset resistance. The weight average molecular weight (Mw) and number average molecular weight (Mn) can be measured in the same manner as in the case of the crystalline resin.

The glass transition temperature (Tg) of the styrene acrylic resin is preferably within the range of 35° C. or higher and 80° C. or lower from the viewpoint of achieving both fixing properties and hot offset resistance. Note that the glass transition temperature of the styrene acrylic resin is the same as the method for measuring the amorphous resin described above.

(Amorphous polyester resin)
Amorphous polyester resin is a polyester resin obtained by a polycondensation reaction between a dihydric or higher carboxylic acid (polyhydric carboxylic acid component) and a divalent or higher alcohol (polyhydric alcohol component), and in DSC, A polyester resin that does not have a clear endothermic peak.

Examples of polyhydric carboxylic acid components include oxalic acid, succinic acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, Fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucilage acid, phthalic acid, Isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylene diacetic acid, m-phenylene diglycolic acid, p-phenylene diglycolic acid, o-phenylene diglycolic acid, Dicarboxylic acids such as diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, dodecenylsuccinic acid, etc. ; trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid and the like. These polyhydric carboxylic acids can be used alone or in combination of two or more.

Among these, aliphatic unsaturated dicarboxylic acids such as fumaric acid, maleic acid, and mesaconic acid, aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid, succinic acid, and trimeritic acid are preferred from the viewpoint of ease of obtaining the effects of the present invention. Preferably, acids are used.

In addition, examples of the polyhydric alcohol component include ethylene glycol, propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexanediol, cyclohexanediol, 1,8-octanediol, 1,10-decanediol, Dihydric alcohols such as 1,12-dodecanediol, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct; glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, etc. Examples include polyols having a valence of 3 or more. These polyhydric alcohol components can be used alone or in combination of two or more. Among these, dihydric alcohols such as bisphenol A ethylene oxide adduct and bisphenol A propylene oxide adduct are preferred from the viewpoint of easily obtaining the effects of the present invention.

The usage ratio of the above polyhydric carboxylic acid component and polyhydric alcohol component is the equivalent ratio of the hydroxyl group [OH] of the polyhydric alcohol component to the carboxyl group [COOH] of the polyhydric carboxylic acid component [OH]/[COOH]. ], preferably from 1.5/1 to 1/1.5, more preferably from 1.2/1 to 1/1.2. When the ratio of the polyhydric alcohol component to the polyhydric carboxylic acid component is within the above range, it becomes easier to control the acid value and molecular weight of the amorphous polyester resin.

The method for preparing the amorphous polyester resin is not particularly limited, and it can be prepared by polycondensing (esterifying) the polyhydric carboxylic acid component and the polyhydric alcohol component using a known esterification catalyst. can.

Since the catalyst that can be used in the production of the amorphous polyester resin is the same as the catalyst explained in the section of the hybrid crystalline polyester resin, the explanation thereof will be omitted here.

The polymerization temperature is not particularly limited, but is preferably 150 to 250°C. Further, the polymerization time is not particularly limited, but it is preferably 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

The glass transition temperature (Tg) of the amorphous polyester resin is preferably within the range of 30° C. or higher and 80° C. or lower from the viewpoint of achieving both fixing properties and hot offset resistance. Note that the glass transition temperature of the amorphous polyester resin is the same as the method for measuring the amorphous resin described above.

(Hybrid amorphous polyester resin)
The binder resin according to the present invention is a hybrid amorphous resin, from the viewpoints of obtaining appropriate compatibility when used in combination with an amorphous vinyl resin, and obtaining shape controllability of toner particles and image strength after fixing. It is preferable that the resin contains a polyester resin. Note that the hybrid amorphous polyester resin can also be said to be a modified amorphous polyester resin in which a portion of the amorphous polyester resin is modified.

(Molecular weight of hybrid amorphous polyester resin)
The weight average molecular weight (Mw) of the hybrid amorphous polyester resin is preferably 20,000 or more and 50,000 or less. This is because with such a molecular weight, compatibility/incompatibility and crystallization can be more easily adjusted. Further, the number average molecular weight (Mn) of the hybrid amorphous polyester resin is preferably 3,000 or more and 12,500 or less. The method for measuring the molecular weight of a crystalline resin described above can be applied to such a molecular weight measurement.

In the present invention, the hybrid amorphous polyester resin is a resin in which an amorphous polyester polymerization segment and an amorphous polymerization segment other than the amorphous polyester, preferably an amorphous vinyl polymerization segment, are chemically bonded. .

The amorphous polyester polymerized segment refers to a portion derived from an amorphous polyester resin. In other words, it refers to a molecular chain having the same chemical structure as that constituting the amorphous polyester resin. Moreover, the amorphous polymerized segment other than amorphous polyester refers to a portion derived from an amorphous resin other than an amorphous polyester resin. Examples of amorphous resins other than amorphous polyester resins include amorphous vinyl resins such as styrene acrylic resins, amorphous urethane resins, and amorphous urea resins. Amorphous polymerization segments other than the amorphous polyester resin may be used alone or in combination of two or more. A more suitable amorphous vinyl polymerization segment refers to a portion derived from an amorphous vinyl resin. In other words, it refers to a molecular chain with the same chemical structure as that constituting the amorphous vinyl resin.

A hybrid amorphous polyester resin is a block copolymer, a graft polymer, etc., as long as it contains an amorphous polyester polymerized segment and an amorphous polymerized segment other than the amorphous polyester resin, especially an amorphous vinyl polymerized segment. Although it may be in any form such as a copolymer, it is preferably a graft copolymer. By using a graft copolymer, the finally obtained toner maintains good low-temperature fixability and has improved hot offset resistance, mold releasability, and the like.

Furthermore, from the above viewpoint, it is preferable that the amorphous polyester polymerized segment has a grafted structure with an amorphous polymerized segment other than the amorphous polyester resin, particularly an amorphous vinyl polymerized segment, as the main chain. That is, a hybrid amorphous polyester resin is a graft copolymer resin having an amorphous polymer segment other than an amorphous polyester as a main chain, especially an amorphous vinyl polymer segment, and a graft copolymer having an amorphous polyester polymer segment as a side chain. Preferably, it is a combination. By adopting such a configuration, the toner finally obtained has improved hot offset resistance and mold releasability while maintaining good low-temperature fixing properties.

In the present invention, when the binder resin contains a hybrid amorphous polyester resin, the content of the hybrid amorphous polyester resin based on the total mass of the toner base particles is preferably 3% by mass or more and 20% by mass or less, and 5% by mass. The content is more preferably 15% by mass or less.

(Amorphous polyester polymerization segment)
The amorphous polyester polymerized segment is a part derived from a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid component) and a divalent or higher alcohol (polyhydric alcohol component). It refers to a polymerized segment in which no clear endothermic peak is observed in DSC.

The amorphous polyester polymerization segment is not particularly limited as long as it is as defined above. For example, for resins that have a structure in which other components are copolymerized on the main chain of an amorphous polyester polymer segment, or resins that have a structure in which an amorphous polyester polymer segment is copolymerized with a main chain consisting of other components, If a toner containing a resin does not have a clear endothermic peak as described above, the resin corresponds to a hybrid amorphous polyester resin having an amorphous polyester polymerized segment as used in the present invention.

The polyhydric carboxylic acid component and the polyhydric alcohol component that constitute the amorphous polyester polymerized segment are the same as those of the above-mentioned amorphous polyester resin, and therefore their description will be omitted here.

The method for forming the amorphous polyester polymerized segment is not particularly limited, and the polymerized segment is formed by polycondensing (esterifying) the polyhydric carboxylic acid component and the polyhydric alcohol component using a known esterification catalyst. can be formed.

Catalysts that can be used in the production of the amorphous polyester polymerized segment are the same as those described in the section regarding the crystalline resin, so their explanation will be omitted here.

Although the polymerization temperature is not particularly limited, it is preferably 150°C or more and 250°C or less. Further, the polymerization time is not particularly limited, but is preferably 0.5 hours or more and 10 hours or less. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

The content of the amorphous polyester polymerized segment in the hybrid amorphous polyester resin is preferably 50 to 99.9% by mass, and preferably 70 to 95% by mass based on the total mass of the hybrid amorphous polyester resin. It is more preferable that there be. By setting it within the above range, it is possible to achieve lower temperature fixing while maintaining heat resistance, and it is possible to obtain an advantage that it is possible to balance the affinity with the amorphous vinyl resin. The constituent components and content ratio of each polymerized segment in the hybrid amorphous polyester resin can be determined by, for example, NMR measurement or methylation reaction Py-GC/MS measurement.

Substituents such as a sulfonic acid group, a carboxy group, and a urethane group may be further introduced into the hybrid amorphous polyester resin. The above-mentioned substituent may be introduced into the amorphous polyester polymerization segment or into the amorphous vinyl polymerization segment which will be explained in detail below.

(Amorphous polymerization segment)
Amorphous polymerized segments other than amorphous polyester resins (especially amorphous vinyl polymerized segments) are hybrid amorphous polyester resins with amorphous vinyl resins when the binder resin includes amorphous vinyl resins. You can control the affinity with.

Containing an amorphous polymer segment other than an amorphous polyester in a hybrid amorphous polyester resin (furthermore, in a toner) can be determined by, for example, NMR measurement, methylation reaction Py-GC/MS measurement. This can be confirmed by specifying the chemical structure.

In addition, amorphous polymer segments other than amorphous polyester do not have a melting point when differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the polymer segment, and have a relatively high glass temperature. It is a polymerized segment that has a transition temperature (Tg). At this time, the glass transition temperature (Tg) of the resin having the same chemical structure and molecular weight as the unit is preferably 35°C or more and 80°C or less, more preferably 45°C or more and 65°C or less.

The amorphous polymerization segment other than the amorphous polyester resin is not particularly limited as long as it is as defined above. For example, resins with a structure in which other components are copolymerized on the main chain of an amorphous polymerized segment other than amorphous polyester resin, or Regarding a resin having a copolymerized structure, if this resin has an amorphous polymer segment as described above, the resin is a hybrid amorphous polyester having an amorphous polymer segment as referred to in the present invention. Applies to resin.

Examples of amorphous polymerized segments other than amorphous polyester include those obtained by polymerizing a vinyl compound, those obtained by polymerizing a polyol component and an isocyanate component, those obtained by polymerizing urea and formaldehyde, and are not particularly limited. . Among these, suitable amorphous polymerization segments include amorphous vinyl polymerization segments obtained by polymerizing vinyl compounds. Examples include acrylic ester polymerized segments, styrene-acrylic ester polymerized segments, and ethylene-vinyl acetate polymerized segments. These may be used alone or in combination of two or more.

Among the above-mentioned vinyl polymerization segments, styrene-acrylic acid ester polymerization segments (styrene-acrylic polymerization segments) are preferred in consideration of plasticity during heat fixing. Further, since the preferred form of the amorphous vinyl resin is a styrene acrylic resin, the amorphous vinyl polymerized segment is also preferably a styrene acrylic polymerized segment. Such a configuration provides the advantage that the affinity between the hybrid amorphous polyester resin and the amorphous vinyl resin is further improved, and the shape controllability of the toner particles is facilitated.

The monomers and formation method used to form the styrene-acrylic polymerized segment are the same as those in the "styrene-acrylic polymerized segment" section described in the section on the hybrid crystalline polyester resin, so their explanation will be omitted here.

The content of the amorphous polymerized segment in the hybrid amorphous polyester resin is preferably 0.1 to 50% by mass, and preferably 5 to 30% by mass, based on the total mass of the hybrid amorphous polyester resin. It is more preferable that there be. By setting the above range, when the core part contains an amorphous vinyl resin, the affinity with the amorphous vinyl resin becomes higher, and the toner finally obtained has good low temperature fixing properties and hot resistance. It is excellent in that it can maintain a higher balance between offset properties and heat resistance.

The method for producing a hybrid amorphous polyester resin includes producing a polymer having a structure in which the above-mentioned amorphous polyester polymerization segment and an amorphous vinyl polymerization segment suitable as an amorphous polymerization segment other than the amorphous polyester resin are combined. There are no particular limitations on the method as long as it is possible to form. A specific method for producing the hybrid amorphous polyester resin includes, for example, the method shown below.

(1) A method of producing a hybrid amorphous polyester resin by polymerizing an amorphous polymerized segment in advance and performing a polymerization reaction to form an amorphous polyester polymerized segment in the presence of the amorphous polymerized segment. be.

(2) A method of producing a hybrid amorphous polyester resin by forming an amorphous polyester polymerization segment and an amorphous polymerization segment, respectively, and bonding them together.

(3) A method of manufacturing a hybrid amorphous polyester resin by forming an amorphous polyester polymerized segment in advance and performing a polymerization reaction to form the amorphous polymerized segment in the presence of the amorphous polyester polymerized segment. It is.

Among the formation methods (1) to (3) above, method (1) is easy to form a hybrid amorphous polyester resin, which has a structure in which an amorphous polymerized segment is grafted with an amorphous polyester polymerized segment. The method (1) is preferable from the viewpoint of simplification of the production process.

[White toner colorant]
The white toner of the present invention includes a colorant whose average dispersion diameter Dw in the toner satisfies the following formula 1, and the colorant includes titanium oxide.

If the average dispersion diameter Dw is less than 100 nm, the light scattering intensity will be weakened and visible light will be transmitted, the transparency will be high and the hiding property will be decreased. On the other hand, if the average dispersion diameter Dw exceeds 1500 nm, the hiding property will be reduced and the desired whiteness cannot be obtained. It is preferable that the average dispersion diameter Dw satisfies the following formula 3.

The average dispersion diameter Dw can be controlled by the dispersion treatment time when dispersing the white colorant in the liquid, the intensity of the dispersion treatment (rotation speed of the equipment, etc.), the concentration of the surfactant in the dispersion, etc. .

The average dispersion diameter Dw of the colorant in the white toner can be measured according to the method shown below.

<Method for measuring average dispersion diameter of colorant in white toner>
The average dispersion diameter Dw of the colorant in the white toner can be measured from the form of the "toner". The average dispersion diameter of the colorant contained in the toner is measured by observing the cross section of the toner particles. The cross section of the toner particles can be observed using a transmission electron microscope, a scanning electron microscope, a scanning probe microscope (SPM), or the like. An example is given below, but it is not limited to this as long as equivalent observation can be made.

(Method for preparing sections of toner particles)
After adding 3 parts by mass of the produced toner particles to 35 parts by mass of a 0.2% aqueous solution of polyoxyethyl phenyl ether and dispersing them, they were sonicated at 25°C using ultrasonic waves (manufactured by Nippon Seiki Seisakusho Co., Ltd., US-1200T). The treatment is performed for 5 minutes to remove the external additive from the surface of the toner particles to obtain toner particles for observation. 1 to 2 mg of the toner particles obtained above were placed in a 10 mL sample bottle, and after staining under ruthenium tetroxide (RuO ₄ ) vapor staining conditions, the photocurable resin "D-800" (manufactured by JEOL Ltd.) was dyed. ) and photocured to form blocks. Next, after producing a thin section using the FIB processing apparatus described below, cross-sectional observation is performed.

(Ruthenium tetroxide staining conditions)
Staining is performed using a vacuum electronic staining device VSC1R1 (manufactured by Philgen Co., Ltd.). According to the device procedure, a sublimation chamber containing ruthenium tetroxide is installed in the main body of the dyeing device, and after introducing the above-mentioned toner particles into the dyeing chamber, the dyeing conditions with ruthenium tetroxide are set at room temperature (24 to 25 degrees Celsius) and at a concentration of 3. (300 Pa) for 10 minutes.

(FIB processing)
FIB processing is performed under the following equipment conditions.

Device: SMI2050 made by SII
Processing ion: (Ga 30kV)
Sample thickness: 200nm to 250nm.

(Observation of toner cross section)
The cross section of the toner is observed using a transmission electron microscope (TEM). Specifically, a cross section of the toner is photographed using a transmission electron microscope (TEM), and the dispersed diameter of white colorant particles is determined as a circular equivalent diameter using an image processing analysis device LUZEX AP (manufactured by Nireco Co., Ltd.). . 100 particles are randomly extracted and calculated as an arithmetic mean value to determine the average dispersion diameter Dw of the white colorant.

<Crystal structure of titanium oxide>
Some titanium oxides have crystal structures such as rutile type (tetragonal type), anatase type, and brookite type, but any type of crystal structure may be used as long as whiteness can be ensured.

Note that the white toner of the present invention may contain colorants other than titanium oxide. Examples of such colorants include heavy calcium carbonate, light calcium carbonate, aluminum hydroxide, titanium white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, and colloidal silica. , white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, smexite, and other inorganic pigments; polystyrene resin particles, urea-formalin resin particles, and other organic pigments. Further, pigments having a hollow structure (for example, inorganic pigments such as hollow silica), etc. can also be mentioned. Pigments other than titanium oxide may be used alone or in combination of two or more.

The white colorant may be surface-treated to impart dispersibility. In that case, the average dispersion diameter Dw in the present invention is measured including the surface treatment layer.

The content of titanium oxide in the white toner of the present invention is preferably 10 to 40% by mass, more preferably 15 to 35% by mass, based on the total mass of the white toner. Within this range, sufficient whiteness can be obtained, a decrease in the amount of charge of the white toner can be prevented, and scattering of the white toner in the apparatus can be suppressed.

The content of the colorant in the white toner is preferably 10 to 50% by weight, more preferably 15 to 40% by weight, based on the total weight of the white toner.

[Cyan toner colorant]
The chromatic toner according to the present invention includes a cyan toner, and the cyan toner contains a phthalocyanine compound represented by the following chemical formula 1 as a main component of a colorant. Note that the term "main component of the colorant" means that the colorant is contained in a content of more than 50% by mass based on the total mass of the colorant contained in the cyan toner. The content of the phthalocyanine compound is preferably 70% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, and 100% by mass, based on the total mass of the colorant contained in the cyan toner. It is particularly preferable.

In the chemical formula 1,
M is a silicon atom, a germanium atom, or a tin atom,
Ra ₁ to Ra ₄ are each independently an electron-withdrawing substituent,
na1 to na4 are each independently an integer of 0 to 4,
Z ₁ and Z ₂ are each independently a hydroxy group, 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 chemical formula 2,

In the chemical formula 2, R ₃ to R ₅ (R ₃ , R ₄ , and R ₅ ) are each independently an alkyl group having 1 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an aryl group having 1 to 18 carbon atoms. -6 alkoxy group.

The phthalocyanine compound represented by the above chemical formula 1 has axial ligands (Z ₁ and Z ₂ ) with a bulky structure. By having an axial ligand with such a bulky structure, the phthalocyanine compound can be easily dispersed more uniformly in the toner particles and the fixed image, and the coloring properties of the cyan toner can be further improved. Further, even in the superimposed image with the white toner, which is the lowest layer, the bulky phthalocyanine compound becomes difficult to move, so that color mixing between the cyan toner and the white toner is less likely to occur. Therefore, color turbidity can be suppressed and excellent color development can be achieved.

In the above chemical formula 1, M is a silicon atom (Si), a germanium atom (Ge), or a tin atom (Sn). M is preferably a silicon atom (Si) from the viewpoint of suppressing color mixing with white toner due to the bulky structure and from the viewpoint of the excellent coloring property of the compound itself.

In the above chemical formula 1, Ra ₁ to Ra ₄ (Ra ₁ , Ra ₂ , Ra ₃ , and Ra ₄ ) are each independently an electron-withdrawing substituent. Examples of electron-withdrawing substituents include chloro group (-Cl), salt halide methyl group (-CClX ₂ ), trifluoromethyl group (-CF ₃ ), nitro group (-NO ₂ ), etc. Can be mentioned. Note that "X" in the salt halogenated methyl group (-CClX ₂ ) represents a halogen atom.

In the above chemical formula 1, na1 to na4 (na1, na2, na3, and na4) are each independently an integer of 0 to 4. When na1 to na4 are integers of 0 to 4, the colorant can cover a desired color gamut.

In the chemical formula 1 above, Z ₁ and Z ₂ are each independently a hydroxy group, 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 chemical formula 2. .

Examples of the aryloxy group having 6 to 18 carbon atoms include phenoxy group, o-tolyloxy group, m-tolyloxy group, p-tolyloxy group, 2,3-xylyloxy group, 2,4-xylyloxy group, 2,5- Xylyloxy group, 2,6-xylyloxy group, 3,4-xylyloxy group, 3,5-xylyloxy group, 2,3,4-trimethylphenoxy group, 2,3,5-trimethylphenoxy group, 2,3,6- Trimethylphenoxy group, 2,4,6-trimethylphenoxy group, 3,4,5-trimethylphenoxy group, 2,3,4,5-tetramethylphenoxy group, 2,3,4,6-tetramethylphenoxy group, 2,3,5,6-tetramethylphenoxy group, pentamethylphenoxy group, ethylphenoxy group, n-propylphenoxy group, isopropylphenoxy group, n-butylphenoxy group, sec-butylphenoxy group, tert-butylphenoxy group, isobutylphenoxy group, n-pentylphenoxy group, neopentylphenoxy group, n-hexylphenoxy group, n-octylphenoxy group, n-decylphenoxy group, n-dodecylphenoxy group, n-tetradecylphenoxy group, naphthyloxy group, Examples include anthracenyloxy group.

Examples of the alkoxy group having 1 to 22 carbon atoms include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, t-butyloxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group, isohexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group , n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-octadecyloxy group, n-eicosyloxy group, n-docosyloxy group, 2-ethylhexyloxy group, 3-ethylheptyloxy group 3-ethyldecyloxy group, 2-hexyldecyloxy group, cyclopentyloxy group, cyclohexyloxy group, cycloheptyloxy group, and other linear, branched, or cyclic alkoxy groups.

Z ₁ and Z ₂ are preferably groups represented by the above chemical formula 2 from the viewpoint of suppressing color mixing with white toner due to the bulky structure and from the viewpoint of the excellent coloring property of the compound itself.

Examples of the alkyl group having 1 to 6 carbon atoms used in R ₃ to R ₅ of the above chemical formula 2 include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec -butyl group, t-butyl group, n-pentyl group, neopentyl group, n-hexyl group, etc.

Examples of the aryl group having 6 to 18 carbon atoms include phenyl group, o-, m- or p-tolyl group, 2,3-xylyl group, 2,4-xylyl group, mesityl group, naphthyl group, anthryl group. group, phenanthryl group, triphenylenyl group, tetracenyl group, chrysenyl group, pyrenyl group, pentacenyl group, picenyl group and the like.

Examples of alkoxy groups having 1 to 6 carbon atoms include methoxy group, ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, t-butyloxy group, Examples include n-pentyloxy group, neopentyloxy group, n-hexyloxy group, isohexyloxy group, and the like.

Preferred examples of the phthalocyanine compound represented by the above chemical formula 1 are shown in Table 1 below. Note that "-" in Table 1 indicates that the substituent is not present.

The phthalocyanine compounds represented by the above chemical formula 1 can be used alone or in combination of two or more.

As the phthalocyanine compound represented by the above chemical formula 1, a commercially available product or a synthetic product may be used. As the synthesis method, a known method may be used, and for example, the method described in JP-A-2011-99047 can be adopted.

In the cyan toner according to the present invention, the average dispersion diameter Dc of the compound represented by the above chemical formula 1 in the cyan toner satisfies the following formula 2.

When the average dispersion diameter Dc is less than 50 nm, visible light is easily transmitted and the light scattering intensity is weakened, resulting in a decrease in color development. On the other hand, when Dc exceeds 800 nm, the specific surface area of the phthalocyanine compound dispersed in the toner becomes small and the light scattering intensity is weakened, resulting in a decrease in color development. It is preferable that the average dispersion diameter Dc satisfies the following formula 4.

The average dispersion diameter Dc depends on the dispersion treatment time when dispersing the phthalocyanine compound represented by the above chemical formula 1 in the liquid, the intensity of the dispersion treatment (rotation speed of the equipment, etc.), the concentration of the surfactant in the dispersion, etc. can be controlled.

The average dispersion diameter Dc of the phthalocyanine compound represented by the above chemical formula 1 in the cyan toner can be measured by the same method as the above-mentioned method for measuring the average dispersion diameter Dw.

The content of the phthalocyanine compound represented by the above chemical formula 1 in the cyan toner is preferably 4 to 12% by mass, and preferably 5 to 10% by mass, based on the total mass of the cyan toner. Within this range, a cyan toner with excellent coloring properties can be obtained.

The cyan toner may contain other colorants as long as the phthalocyanine compound represented by the above chemical formula 1 is contained as a main component of the colorant. Examples of other colorants include C.I. I. Dyes such as Solvent Blue 25, Solvent Blue 36, Solvent Blue 60, Solvent Blue 70, Solvent Blue 93, and Solvent Blue 95; C.I. I. Examples include pigments such as Pigment Blue 1, Pigment Blue 7, Pigment Blue 15, Pigment Blue 15:3, Pigment Blue 60, Pigment Blue 62, Pigment Blue 66, and Pigment Blue 76.

The content of the colorant in the cyan toner is preferably 4 to 30% by weight, more preferably 5 to 20% by weight, based on the total weight of the cyan toner.

<Dw/Dc>
The ratio of the Dw to the Dc (Dw/Dc) preferably satisfies Equation 5 below.

Within this range, color mixing between white toner and chromatic toner becomes less likely to occur, color turbidity is suppressed, and color development is further improved. It is more preferable that the Dw/Dc satisfies the following formula 6.

The white toner and the chromatic toner may contain internal additives such as a release agent and a charge control agent; external additives such as inorganic fine particles, organic fine particles, and a lubricant, as necessary. The internal additives and external additives will be explained below.

(Mold release agent (wax))
It is preferable that the white toner and the chromatic toner further contain a release agent (wax). As the mold release agent, any known release agent can be used. Examples of mold release agents include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax; long chain hydrocarbon waxes such as paraffin wax, Sasol wax, and Fischer-Tropsch wax; and dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, behenyl behenate (behenyl behenate), trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate Ester waxes such as nate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, distearyl maleate, stearyl stearate, fatty acid polyglycerol ester, ethylenediamine behenylamide, trimellitic acid Includes amide waxes such as tristearylamide. The above-mentioned mold release agent is easily compatible with the vinyl resin. Therefore, due to the plasticizing effect of the release agent, the sharp melting properties of the toner can be enhanced and sufficient low-temperature fixability can be obtained. The above mold release agent is preferably an ester wax (ester compound) from the viewpoint of obtaining sufficient low-temperature fixability, and furthermore, from the viewpoint of achieving both heat resistance and low-temperature fixability, a linear ester wax ( A linear ester compound) is more preferable. These mold release agents may be used alone or in combination of two or more.

The content of the release agent in the toner is preferably in the range of 3% by mass or more and 15% by mass or less. Within this range, there are effects such as preventing hot offset, ensuring separability, and improving heat resistance.

(Charge control agent)
As the charge control agent, various known compounds can be used. Examples of charge control agents include nigrosine-based electron-donating dyes for positive charging, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salts, alkylamides, metal complexes, pigments, and fluorine treatment actives. Examples of negative charging agents include electron-accepting organic complexes, chlorinated paraffins, chlorinated polyesters, and sulfonylamines of copper phthalocyanine.

The content of the charge control agent is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the binder resin in the toner.

The toner base particles according to the present invention may have a so-called single-layer structure, or may have a core-shell structure as described above. By having a core-shell structure, it is possible to maintain a high balance between low-temperature fixing properties, hot offset resistance, and heat resistance. The core-shell structure is not limited to a structure in which the shell layer completely covers the particle surface of the core part. For example, the shell layer does not completely cover the particle surface of the core part, and some particles Including those with exposed surfaces.

Further, from the viewpoint of improving charging property, in the white toner and chromatic toner according to the present invention, the crystalline resin is not exposed on the surface and is contained inside the toner base particles, and the amorphous resin is contained inside the toner base particles. Preferably, it is exposed on the surface. The form of such a toner can be controlled by the timing of addition of each resin, etc. when producing toner base particles by an emulsion aggregation method.

Not limited to the above, the white toner and chromatic toner according to the present invention may have a multilayer structure of three or more layers, a domain-matrix structure, or the like.

The morphology of the toner (the cross-sectional structure of the core-shell structure and the location of the crystalline polyester resin) can be confirmed using known means such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM), for example. It is.

[External additive]
From the viewpoint of improving the charging performance, fluidity, or cleaning properties of the toner, known particles such as inorganic particles or organic particles, lubricants, etc. can be added to the surface of the toner base particles as external additives.

Preferred examples of the inorganic particles include inorganic particles made of silica, sol-gel silica, titania (titanium oxide), alumina (aluminum oxide), strontium titanate, and the like. These inorganic particles may be hydrophobized using a surface treatment agent such as a known silane coupling agent or silicone oil, if necessary. The size of the inorganic particles is preferably 2 nm or more and 200 nm or less, and more preferably 7 nm or more and 150 nm or less in number average primary particle size.

As the organic particles, organic particles made of homopolymers such as styrene or methyl methacrylate or copolymers thereof can be used. The size of the organic particles is preferably 10 nm or more and 2000 nm or less in number average primary particle size, and the particle shape is, for example, spherical. The number average primary particle size of inorganic particles and organic particles can be calculated using electron micrographs. For example, it can be determined by image processing of an image taken with a transmission electron microscope.

The lubricant is used for the purpose of further improving cleaning properties and transfer properties. Examples of lubricants include salts of stearic acid such as zinc, aluminum, copper, magnesium, and calcium; salts of oleic acid such as zinc, manganese, iron, copper, and magnesium; and zinc, copper, and magnesium palmitic acid. Examples include metal salts of higher fatty acids such as salts of calcium, etc., salts of linoleic acid, zinc, calcium, etc., and salts of ricinoleic acid, zinc, calcium, etc. The size of the lubricating material is preferably 0.3 μm or more and 20 μm or less, more preferably 0.5 μm or more and 10 μm or less, in volume-based median diameter (volume average particle size). The volume-based median diameter of the lubricant can be determined according to JIS Z8825-1 (2013). These external additives may be used in combination.

The content of the external additive is preferably 0.1 to 10.0 parts by weight based on 100 parts by weight of the toner base particles. The above-mentioned external additive can be attached to the surface of the toner base particles using various known mixing devices such as a turbular mixer, a Henschel mixer (registered trademark), a Nauta mixer, and a V-type mixer.

[Average circularity of toner base particles]
From the viewpoint of improving low-temperature fixability, the average circularity of the toner base particles is preferably within the range of 0.920 to 1.000, more preferably within the range of 0.940 to 0.995.

Here, the average circularity is a value measured using "FPIA-3000" (manufactured by Sysmex). Specifically, toner base particles are wetted with a surfactant aqueous solution, ultrasonic dispersion is performed for 1 minute, and after dispersion, using "FPIA-3000", measurement conditions are HPF (high magnification imaging) mode. Measurement is performed at an appropriate concentration for 4000 detections. Circularity is calculated using the following formula:
Circularity = (perimeter of a circle with the same projected area as the particle image)/(perimeter of the particle projection image).

Further, the average circularity is an arithmetic mean value obtained by adding up the circularity of each particle and dividing the sum by the total number of particles measured.

[Toner particle size]
The particle diameter of the white toner and chromatic toner according to the present invention is preferably 3 to 10 μm in volume-based median diameter (D50). By setting the volume-based median diameter within the above range, fine line reproducibility and high quality photographic images can be achieved, and toner fluidity can also be ensured. Here, the volume-based median diameter (D50) of the toner base particles is measured using, for example, a device that is connected to a "Coulter Multisizer 3" (manufactured by Beckman Coulter, Inc.) and a computer system for data processing. Calculations can be made.

The volume-based median diameter of white toner and chromatic toner depends on the concentration of the flocculant, the amount of solvent added, or the fusing time in the aggregation and fusing process during toner manufacturing, which will be described later, as well as the composition of the resin component. can be controlled.

[Colorants contained in toners other than white toner and cyan toner]
In the electrophotographic image forming method of the present invention, in addition to the white toner and cyan toner, other toners such as black toner, yellow toner, magenta toner, etc. may be used. As the colorant contained in such a toner, commonly known dyes and pigments can be used.

Examples of colorants for obtaining black toner include carbon black, magnetic materials, iron/titanium composite oxide black, etc. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black, etc. can be mentioned. Furthermore, examples of the magnetic material include ferrite and magnetite.

As a coloring agent for obtaining a yellow toner, for example, C.I. I. Dyes such as Solvent Yellow 19, Solvent Yellow 44, Solvent Yellow 77, Solvent Yellow 79, Solvent Yellow 81, Solvent Yellow 82, Solvent Yellow 93, Solvent Yellow 98, Solvent Yellow 103, Solvent Yellow 104, Solvent Yellow 112, Solvent Yellow 162; I. Examples include pigments such as Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 74, Pigment Yellow 93, Pigment Yellow 94, Pigment Yellow 138, Pigment Yellow 155, Pigment Yellow 180, and Pigment Yellow 185.

As a coloring agent for obtaining magenta toner, C.I. I. Dyes such as Solvent Red 1, Solvent Red 49, Solvent Red 52, Solvent Red 58, Solvent Red 63, Solvent Red 111, Solvent Red 122; C.I. I. Examples include pigments such as Pigment Red 5, Pigment Red 48:1, Pigment Red 53:1, Pigment Red 57:1, Pigment Red 122, Pigment Red 139, Pigment Red 144, Pigment Red 149, Pigment Red 166, Pigment Red 177, Pigment Red 178, and Pigment Red 222.

Coloring agents for obtaining toners of each color can be used alone or in combination of two or more.

The average particle size of the colorant used in toners other than white toner and cyan toner is preferably 10 to 1000 nm, more preferably 50 to 500 nm.

The amount of the colorant added is preferably from 1 to 60% by weight, more preferably from 2 to 25% by weight, based on the weight of the entire toner. Within this range, the color reproducibility of the image can be ensured.

[Toner manufacturing method]
The method for producing the white toner and chromatic toner according to the present invention is not particularly limited. For example, a toner can be obtained by melting and kneading a binder resin, a coloring agent, and if necessary a release agent, etc., and then performing pulverization, classification, etc. Other known methods include kneading and pulverization methods, suspension polymerization methods, emulsion aggregation methods, dissolution suspension methods, polyester extension methods, and dispersion polymerization methods.

Among these, it is preferable to employ the emulsion aggregation method from the viewpoints of uniformity of particle size, controllability of shape, ease of forming a core-shell structure, and the like. The emulsion aggregation method will be explained below.

<Emulsification aggregation method>
The emulsion aggregation method is as follows. That is, a dispersion of binder resin particles (hereinafter also referred to as binder resin particles) dispersed with a surfactant or a dispersion stabilizer is mixed with a dispersion of constituent components of toner base particles such as colorant particles. By adding an aggregating agent, the particles are agglomerated until a desired toner particle size is achieved. This is a method of forming toner particles by performing fusion between resin particles afterward or simultaneously with aggregation, and controlling the shape.

Here, the binder resin particles can also be composite particles formed of two or more layers made of resins having different compositions.

The binder resin particles can be produced by, for example, an emulsion polymerization method, a mini-emulsion polymerization method, a phase inversion emulsification method, or a combination of several production methods. When the binder resin particles contain an internal additive, it is preferable to use a mini-emulsion polymerization method.

When toner particles contain internal additives such as colorants and mold release agents, binder resin particles may contain the internal additives, or internal additives consisting only of the internal additives may be used. A dispersion of particles may be prepared, and the internal additive particles may be coagulated together when the binder resin particles are agglomerated.

Further, toner particles having a core-shell structure can also be obtained by using an emulsion aggregation method. Specifically, first, binder resin particles for the core part and colorant particles are agglomerated (and fused) to produce a granular core part, and then a particulate core part for the shell layer is added to the dispersion of the core part. It can be obtained by adding binder resin particles and aggregating and fusing the binder resin particles for the shell layer on the surface of the core part to form a shell layer covering the surface of the core part.

When producing a toner by an emulsion aggregation method, the toner production method according to a preferred embodiment includes preparing a crystalline resin particle dispersion, an amorphous resin particle dispersion, and a colorant particle dispersion as a binder resin particle dispersion. (hereinafter also referred to as the preparation step) (1), and the step of mixing and agglomerating and fusing the crystalline resin particle dispersion, the amorphous resin particle dispersion, and the colorant particle dispersion (hereinafter referred to as aggregation/fusion). Also referred to as a fusion step) (2).

Each step will be explained in detail below.

(1) Preparation step Step (1) more specifically includes a crystalline resin particle dispersion preparation step, an amorphous resin particle dispersion preparation step, and a colorant particle dispersion preparation step, and as necessary. This process includes a release agent particle dispersion preparation step.

(1-1) Crystalline resin particle dispersion preparation step and amorphous resin particle dispersion preparation step In the crystalline resin particle dispersion preparation step, a crystalline resin constituting toner particles is synthesized, and this crystalline resin is This is a step of preparing a dispersion of crystalline resin particles by dispersing them in particulate form in an aqueous medium. In addition, in the amorphous resin particle dispersion preparation step, an amorphous resin constituting the toner particles is synthesized, and this amorphous resin is dispersed in the form of particles in an aqueous medium to form a dispersion of amorphous resin particles. This is the process of preparing.

As a method for dispersing a crystalline resin in an aqueous medium, the crystalline resin is dissolved or dispersed in an organic solvent (solvent) to prepare an oil phase liquid, and the oil phase liquid is dispersed in an aqueous medium by phase inversion emulsification or the like. An example of this method is to disperse the organic solvent into oil droplets to form oil droplets with a controlled particle size, and then remove the organic solvent. The method for dispersing the amorphous resin in the aqueous medium may be the same as the method for dispersing the crystalline resin in the aqueous medium described above.

The organic solvent (solvent) used for preparing the oil phase liquid is preferably one with a low boiling point and low solubility in water from the viewpoint of easy removal treatment after oil droplets are formed. Specific examples include methyl acetate, ethyl acetate, methyl ethyl ketone, isopropyl alcohol, methyl isobutyl ketone, toluene, and xylene. These can be used alone or in combination of two or more.

The amount of organic solvent (solvent) used (if two or more types are used, the total amount used) is preferably 1 to 300 parts by weight, more preferably 10 to 200 parts by weight, based on 100 parts by weight of the binder resin. More preferably, it is 25 to 100 parts by mass.

Furthermore, ammonia, sodium hydroxide, etc. may be added to the oil phase liquid in order to ionically dissociate the carboxyl group and stably emulsify it in the aqueous phase, thereby facilitating the emulsification.

The amount of the aqueous medium used is preferably 50 to 2,000 parts by mass, more preferably 100 to 1,000 parts by mass, per 100 parts by mass of the oil phase liquid. By setting the amount of the aqueous medium to be used within the above range, the oil phase liquid can be emulsified and dispersed to a desired particle size in the aqueous medium.

A dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant, resin particles, etc. may be added for the purpose of improving the dispersion stability of oil droplets.

Examples of the dispersion stabilizer include inorganic compounds such as tricalcium phosphate, calcium carbonate, titanium oxide, colloidal silica, and hydroxyapatite. However, since it is necessary to remove the dispersion stabilizer from the resulting toner base particles, it is preferable to use one that is soluble in acid or alkali, such as tricalcium phosphate, or from an environmental perspective. It is preferable to use one that can be decomposed by enzymes.

Examples of the surfactant include anionic surfactants such as alkylbenzene sulfonate, α-olefin sulfonate, phosphoric acid ester, sodium alkyldiphenyl ether disulfonate, sodium polyoxyethylene lauryl ether sulfate, alkyl amine salt, amino acid ester, etc. Amine salt types such as alcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines, and quaternary ammonium salts such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride. Salt type cationic surfactants, fatty acid amide derivatives, nonionic surfactants such as polyhydric alcohol derivatives, alanine, dodecyl di(aminoethyl)glycine, di(octylaminoethyl)glycine and N-alkyl-N,N Examples include amphoteric surfactants such as -dimethylammonium betaine, and anionic surfactants and cationic surfactants having a fluoroalkyl group can also be used.

In addition, the resin particles for improving dispersion stability preferably have a particle size of 0.5 to 3 μm. Specifically, polymethyl methacrylate resin particles with a particle size of 1 μm and 3 μm, Examples include polystyrene resin particles with a particle size of 0.5 μm and 2 μm, and polystyrene-acrylonitrile resin particles with a particle size of 1 μm.

Such emulsification and dispersion of the oil phase liquid can be performed using mechanical energy, and the dispersion machine for emulsification and dispersion is not particularly limited, and may include a low-speed shear type dispersion machine, a high-speed shear type dispersion machine, etc. Examples include ultrasonic dispersion machines such as a type dispersion machine, a friction type dispersion machine, a high-pressure jet type dispersion machine, an ultrasonic dispersion machine such as an ultrasonic homogenizer, and a high-pressure impact type dispersion machine called Ultimizer.

To remove the organic solvent after the formation of oil droplets, the entire dispersion in which crystalline resin particles were dispersed in an aqueous medium was gradually heated under stirring, and strong stirring was applied within a certain temperature range. After that, it can be carried out by operations such as removing the solvent. Alternatively, it can be removed while reducing the pressure using a device such as an evaporator. For amorphous resin particles, the organic solvent can be removed after oil droplets are formed in the same manner as for the crystalline resin particles described above.

The average particle size of the crystalline resin particles (oil droplets) or amorphous resin particles (oil droplets) in the crystalline resin particle dispersion or amorphous resin particle dispersion prepared in this way is 60 to 1000 nm. The wavelength is preferably 80 to 500 nm, and more preferably 80 to 500 nm. The average particle diameters of the binder resin particles, colorant particles, mold release agent particles, etc. in the dispersion were measured using a laser diffraction/scattering particle size distribution analyzer (Microtrack particle size distribution analyzer "UPA-150" (Nikkiso)). (manufactured by Co., Ltd.)). The average particle size of the binder resin particles (oil droplets) can be controlled by the magnitude of mechanical energy during emulsification and dispersion.

Further, the content of crystalline resin particles or amorphous resin particles in the crystalline resin particle dispersion or the amorphous resin particle dispersion is preferably in the range of 10 to 50% by mass based on 100% by mass of the dispersion. The range of 15 to 40% by mass is more preferable. Within this range, broadening of the particle size distribution can be suppressed and toner properties can be improved.

(1-2) Colorant particle dispersion preparation step This colorant particle dispersion preparation step is a step in which a colorant is dispersed in the form of particles in an aqueous medium to prepare a dispersion of colorant particles.

The aqueous medium is as explained in (1-1) above, and this aqueous medium contains the surfactant and resin particles shown in (1-1) above for the purpose of improving dispersion stability. May be added.

Dispersion of the colorant can be carried out using mechanical energy, and such a dispersing machine is not particularly limited, and as mentioned above, a low-speed shearing type dispersing machine, a high-speed shearing type dispersing machine, etc. Examples include a dispersing machine, a friction dispersing machine, a high pressure jet dispersing machine, an ultrasonic dispersing machine such as an ultrasonic homogenizer, and a high pressure impact dispersing machine Ultimizer.

Further, the content of the colorant in the white colorant particle dispersion is preferably in the range of 10 to 50% by mass, more preferably in the range of 15 to 40% by mass. This range has the effect of ensuring color reproducibility. Further, the content of the colorant in the colorant particle dispersion of each chromatic color is preferably in the range of 10 to 50% by mass, more preferably in the range of 15 to 40% by mass. This range has the effect of ensuring color reproducibility.

(1-3) Release agent particle dispersion preparation step This release agent particle dispersion preparation step is a step performed as necessary when toner particles containing a release agent are desired. This is a step of preparing a dispersion of mold release agent particles by dispersing the mold agent in the form of particles in an aqueous medium.

The aqueous medium is as explained in (1-1) above, and this aqueous medium contains the surfactant and resin particles shown in (1-1) above for the purpose of improving dispersion stability. May be added.

Dispersion of the mold release agent can be carried out using mechanical energy, and examples of such a dispersion machine include, but are not particularly limited to, low-speed shear type dispersion machines, high-speed shear type dispersion machines, etc. as mentioned above. Examples include ultrasonic dispersion machines such as a type dispersion machine, a friction type dispersion machine, a high pressure jet type dispersion machine, an ultrasonic homogenizer, a high pressure impact type dispersion machine Ultimizer, and a high pressure homogenizer. In dispersing the release agent particles, heating may be performed as necessary.

The content of the release agent particles in the release agent particle dispersion is preferably in the range of 10 to 50% by mass, more preferably in the range of 15 to 40% by mass. Within this range, the effects of preventing hot offset and ensuring separability can be obtained.

(2) Agglomeration/fusion process In this aggregation/fusion process, a crystalline resin particle dispersion, an amorphous resin particle dispersion, a colorant particle dispersion, and, if necessary, a release agent particle dispersion Add and mix other ingredients such as. After that, the pH is adjusted to balance the repulsive force on the particle surface and the cohesive force caused by the addition of a flocculant made of an electrolyte body, and the particles are slowly agglomerated. At the same time, the particles are aggregated while controlling the average particle size and particle size distribution. By stirring, fine particles are fused together to control their shape. As a result, toner base particles are formed. This aggregation/fusion process can also be performed using mechanical energy or heating means, if necessary.

In the aggregation step, first, the obtained dispersions are mixed to form a mixed liquid, and the mixture is heated at a temperature equal to or lower than the glass transition temperature of the amorphous resin to cause aggregation and form agglomerated particles. The formation of aggregated particles is preferably performed by making the pH of the mixed solution alkaline while stirring. The pH is preferably in the range of 7.5 to 11. At this time, it is preferable to use a flocculant.

As the flocculant used, in addition to a surfactant having a polarity opposite to that of the surfactant used in the dispersant, an inorganic metal salt, and a complex containing a divalent or higher valent metal can be suitably used.

Examples of inorganic metal salts include metal salts such as sodium chloride, potassium chloride, lithium chloride, calcium chloride, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, copper sulfate, magnesium sulfate, aluminum sulfate, manganese sulfate, and calcium nitrate. , and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, polysilica iron, and calcium polysulfide. In order to obtain a sharper particle size distribution, it is more suitable for the valence of the inorganic metal salt to be divalent than monovalent, trivalent than divalent, and tetravalent than trivalent.

The content of divalent or higher-valent metal ions in the toner can be controlled mainly by controlling the pH of the liquid mixture in this step, the amount and type of coagulant added, and the like.

When the aggregated particles reached a desired particle size, crystalline resin particles and/or amorphous resin particles were added to coat the surface of the core aggregated particles with the crystalline resin and/or amorphous resin. A toner having a core-shell structure can be produced. In the case of additional addition, operations such as adding a flocculant or adjusting the pH may be performed before the additional addition.

It is preferable to heat and raise the temperature during aggregation. At this time, if the temperature reaches or exceeds the fusion temperature due to heating or temperature rise, the fusion process will proceed at the same time. The heating rate is preferably in the range of 0.1 to 5°C/min. Further, the heating temperature (peak temperature) is preferably in the range of 40 to 100°C.

When the aggregated particles reach a desired particle size, the aggregation of various particles in the reaction system is stopped (hereinafter also referred to as an aggregation stopping step). In order to suppress the aggregation effect of particles in the reaction system, the aggregation stopper is made of a basic compound that can adjust the pH in a direction away from the pH environment that promotes the aggregation effect of particles in the aggregation process. This is done by adding an agent. Although the average particle size of the aggregated particles is not particularly limited, it is preferably about 4.5 to 7 μm.

Examples of flocculation inhibitors include alkali metal salts such as ethylenediaminetetraacetic acid (EDTA) and its sodium salt, gluconal, sodium gluconate, potassium and sodium citrate, nitrotriacetate (NTA) salts, GLDA (commercially available L -glutamic acid-N,N-diacetic acid), humic acid and fulvic acid, maltol and ethyl maltol, pentaacetic acid and tetraacetic acid, both carboxy and hydroxy groups such as tetrasodium 3-hydroxy-2,2'-iminodisuccinate. Examples include known compounds having a functional group or salts thereof, water-soluble polymers (polymer electrolytes), sodium hydroxide, potassium hydroxide, sodium chloride, and the like. In the aggregation stopping step, stirring may be performed in the same manner as in the aggregation step.

In the fusion step, after the above-mentioned aggregation stopping step or at the same time as the aggregation step, the reaction system is heated to a desired fusion temperature to fuse each particle constituting the agglomerated particles and fuse the agglomerated particles. This is a step of forming fused particles.

The fusing temperature in this fusing step is preferably equal to or higher than the melting point of the crystalline resin, and the fusing temperature is preferably 0 to 20° C. higher than the melting point of the crystalline resin. The heating time may be long enough to achieve fusion bonding, and may be performed for about 0.5 to 10 hours.

In this agglomeration/fusion step, in order to stably disperse each particle in the system, the above (1-1) Crystalline resin particle dispersion preparation step/Amorphous resin particle dispersion preparation step is performed in an aqueous medium. A surfactant similar to the surfactant used in the process etc. may be added.

The mass ratio of amorphous resin particles/crystalline resin particles added in this aggregation/fusion step is preferably 1/1 to 1/100. Within this range, the resulting toner has excellent hot offset resistance and low-temperature fixing properties.

Note that when other internal additives are introduced into the toner base particles, an internal additive particle dispersion containing only the internal additives is prepared before this agglomeration/fusion process, and in this aggregation/fusion process, The internal additive particle dispersion may be mixed with the crystalline resin particle dispersion, the amorphous resin particle dispersion, and the colorant particle dispersion.

After fusion, it is cooled to obtain fused particles. The cooling rate is preferably 1-20°C/min.

When obtaining a toner by the emulsion aggregation method, it is preferable to include a circularity control step (3) for controlling the circularity of the toner after the above-mentioned fusion and before cooling.

(3) Circularity Control Process A specific example of the circularity control process is a heat treatment in which the particles obtained in the aggregation/fusion process are heated. Circularity can be controlled by heating temperature and holding time. The circularity can be brought closer to 1 by increasing the heating temperature or by increasing the holding time.

The heating temperature in the circularity control process is preferably 70 to 95°C. The circularity can be controlled by measuring the circularity of particles having a particle size of 2 μm or more using a circularity measuring device during heating, and appropriately determining whether the circularity is the desired circularity.

(4) Filtration/Washing Step In this filtration/washing step, the obtained dispersion of toner particles is cooled to form a cooled slurry, and the cooled dispersion of toner particles is filtered using a solvent such as water. , a filtration process in which solid-liquid separation of toner particles is performed to filter out the toner particles, and a cleaning process in which deposits such as surfactants are removed from the filtered toner particles (cake-like aggregate). . Specific solid-liquid separation and washing methods include centrifugation, vacuum filtration using an aspirator, Nutsche, etc., filtration using a filter press, etc., and are not particularly limited. . In this filtration/washing step, pH adjustment, pulverization, etc. may be performed as appropriate. Such operations may be repeated.

(5) Drying process In this drying process, the toner particles that have been washed are subjected to a drying process. Dryers used in this drying process include ovens, spray dryers, vacuum freeze dryers, vacuum dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers, and stirring dryers. Examples include dryers and the like, but these are not particularly limited. The moisture content of the dried toner particles measured by Karl Fischer coulometric titration is preferably 5% by mass or less, more preferably 2% by mass or less.

Furthermore, when the dried toner particles aggregate with each other due to weak interparticle attraction to form an aggregate, the aggregate may be subjected to a crushing treatment. As the crushing device, mechanical crushing devices such as a jet mill, Cormill, Henschel mixer (registered trademark), coffee mill, food processor, etc. can be used.

(6) External additive addition step This external additive addition step adds charge control agents, various inorganic particles, This is a step of adding organic particles or external additives such as a lubricant, and is performed as necessary. Examples of devices used for adding external additives include various known mixing devices such as a turbular mixer, a Henschel mixer (registered trademark), a Nauta mixer, a V-type mixer, and a sample mill. Further, in order to keep the particle size distribution of the toner within an appropriate range, sieve classification may be performed as necessary.

[Developer]
For example, when the white toner and chromatic toner of the present invention contain a magnetic substance and are used as a one-component magnetic toner, when mixed with a so-called carrier and used as a two-component developer, or when a non-magnetic toner is used alone. There are several cases in which it is possible to do so, and any of them can be suitably used.

As the carrier constituting the two-component developer, magnetic particles made of conventionally known materials such as metals such as iron, ferrite, and magnetite, and alloys of these metals and metals such as aluminum and lead can be used. Preferably, ferrite particles are used.

The volume-based median diameter of the carrier is preferably 15 to 100 μm, more preferably 25 to 80 μm.

As the carrier, it is preferable to use a carrier coated with resin or a so-called resin-dispersed carrier in which magnetic particles are dispersed in resin. There are no particular limitations on the resin composition for the coating, but for example, olefin resins, cyclohexyl methacrylate-methyl methacrylate copolymer resins, styrene resins, styrene acrylic resins, silicone resins, polyester resins, or fluororesins are used. In addition, the resin for forming the resin-dispersed carrier is not particularly limited and any known resin can be used. For example, acrylic resin, styrene acrylic resin, polyester resin, fluororesin, phenol resin, etc. can be used. Can be done.

The volume-based median diameter of the carrier is preferably 20 to 100 μm, more preferably 25 to 70 μm. The volume-based median diameter of the carrier can typically be measured using a laser diffraction particle size distribution analyzer "HELOS" (manufactured by SYMPATEC) equipped with a wet dispersion machine.

The amount of toner to be mixed with the carrier is preferably 2 to 10% by mass, based on the total mass of toner and carrier as 100% by mass.

[Image forming method]
The image forming method of the present invention preferably includes a step of transferring and fixing white toner and chromatic toner including cyan toner to a recording medium to form an image. In this step, a toner image made of white toner (white toner image) and a toner image made of chromatic toner (chromatic toner image) are transferred and fixed onto a recording medium to form an image. At this time, there is a method of fixing a white toner image obtained by transferring white toner onto a recording medium, and then fixing a chromatic toner image obtained by transferring chromatic toner onto a recording medium. An example of this method is to simultaneously fix a white toner image obtained by transferring a white toner image and a chromatic toner image obtained by transferring a chromatic toner image onto a recording medium. That is, as for the fixing system, white toner and chromatic toner may be transferred and fixed all at once, or images may be formed by repeating the transfer and fixing steps in stages. In order to obtain the effects of the present invention more efficiently and to speed up image formation, it is preferable to form an image by overlapping a white toner image and a chromatic toner image and fixing them simultaneously on a recording medium. In addition, in order to enhance the effect of the present invention as a fixed image, it is necessary that the white toner layer be a layer closer to the recording medium than the chromatic toner layer (in a form in which the white toner constitutes an undercoat layer). preferable.

Preferably, the electrostatic latent image electrostatically formed on the image bearing member is made visible by charging a developer with a frictional charging member in a developing device to obtain a toner image. A visible image is obtained by transferring the obtained toner image onto a recording medium, and then fixing the toner image transferred onto the recording medium to the recording material by a contact heating type fixing process.

A suitable fixing method includes a so-called contact heating method. Examples of the contact heating method include, in particular, a heat-pressure fixing method, a heat roll fixing method, and a pressure-contact heat fixing method in which fixing is performed using a rotating pressure member containing a fixedly arranged heating body.

The hot roll fixing method usually uses an upper roller that is equipped with a heat source inside a metal cylinder made of iron or aluminum whose surface is coated with fluororesin, etc., and a lower roller that is made of silicone rubber or the like. A fixing device composed of the following is used.

A linear heater is used as the heat source, and this heater heats the surface temperature of the upper roller to about 120 to 200°C. Pressure is applied between the upper roller and the lower roller, and as the lower roller is deformed by this pressure, a so-called nip is formed in this deformed portion. The width of the nip is preferably 1 to 10 mm, more preferably 1.5 to 7 mm. The fixing linear speed is preferably 40 mm/sec to 600 mm/sec.

[recoding media]
The recording medium may be one commonly used and is not particularly limited. Usable recording media include, for example, plain paper from thin paper to thick paper, high-quality paper, art paper, colored paper, coated printing paper such as coated paper, commercially available Japanese paper and postcard paper, OHP paper, etc. Examples include plastic films, cloth, paper coated with metals such as aluminum, various resin materials used in so-called flexible packaging, resin films formed from these materials, and labels.

In particular, the electrophotographic image forming method of the present invention can achieve excellent color development even when printing on special recording media such as colored paper, aluminum vapor-deposited paper, and transparent film.

[Image forming device]
An example of the structure of an image forming apparatus used in the electrophotographic image forming method of the present invention is a known image forming apparatus equipped with chromatic toners including white toner and cyan toner. An example of an image forming apparatus equipped with white toner and chromatic toner is the apparatus described in Japanese Patent Laid-Open No. 2002-328501.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various changes can be made.

The effects of the present invention will be explained using the following examples and comparative examples. However, the technical scope of the present invention is not limited only to the following examples. In the following examples, "%" and "parts" are used, but unless otherwise specified, "% by mass" and "parts by mass" are used.

<Methods for measuring various characteristics>
≪Measurement of melting point (Tm) of crystalline resin≫
The melting point (Tm) of the crystalline resin was measured by differential scanning calorimetry (DSC). Specifically, 3.0 mg of a sample of crystalline resin was placed in an aluminum pan KIT No. The sample was sealed in B0143013 and set in a sample holder of a thermal analyzer Diamond DSC (manufactured by PerkinElmer), and the temperature was varied in the order of heating, cooling, and heating. During the first and second heating, the temperature was raised from room temperature (25°C) to 150°C at a temperature increase rate of 10°C/min and held at 150°C for 5 minutes, and during cooling, the temperature was lowered at a rate of 10°C/min. The temperature was lowered from 150°C to 0°C and maintained at 0°C for 5 minutes. The temperature at the top of the endothermic peak in the endothermic curve obtained during the second heating was measured as the melting point (Tm (° C.)) of the crystalline resin.

<Measurement of recrystallization temperature (Rc) of crystalline resin>
The recrystallization temperature (Rc) of the crystalline resin is determined by differential scanning calorimetry (DSC) after measuring the melting point of the crystalline resin and setting the sample using the same equipment and sample packaging method as described above. The resin was heated from room temperature (25°C) to 100°C at a heating rate of 10°C/min, held for 1 minute, and then lowered to 0°C at a cooling rate of 0.1°C/min. The temperature at the top of the exothermic peak in the measurement curve was determined as the recrystallization temperature (Rc).

≪Measurement of glass transition temperature (Tg) of amorphous resin≫
The glass transition temperature (Tg) of the amorphous resin was measured according to the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-82. The measurements were carried out using a DSC-7 differential scanning calorimeter (manufactured by PerkinElmer), a TAC7/DX thermal analyzer controller (manufactured by PerkinElmer), and the like.

≪Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn) of each resin≫
The weight average molecular weight (Mw) and number average molecular weight (Mn) of each resin and amorphous resin were determined from the molecular weight distribution measured by gel permeation chromatography (GPC) as follows.

The sample was added to tetrahydrofuran (THF) at a concentration of 0.1 mg/mL, heated to 40°C to completely dissolve it, and then treated with a membrane filter with a pore size of 0.2 μm to remove the sample solution ( sample) was prepared. Thereafter, measurements were performed under the following conditions. Specifically, using a GPC device HLC-8220GPC (manufactured by Tosoh Corporation) and a column "TSKgelSuperH3000" (manufactured by Tosoh Corporation), THF was used as a carrier solvent (eluent) at a flow rate of 0.25°C while maintaining the column temperature at 40°C. It was flowed at 6 mL/min. 100 μL of the prepared sample solution was injected into the GPC device together with the carrier solvent, and the sample was detected using a differential refractive index detector (RI detector). Then, the molecular weight distribution of the sample was calculated using a calibration curve measured using 10 points of monodisperse polystyrene standard particles. In addition, in data analysis, if a peak caused by the filter is confirmed, a baseline was set up to just before the peak and the analyzed data was used as the molecular weight of the sample:
Measurement model: Tosoh Corporation GPC device HLC-8220GPC
Column: “TSKgelSuperH3000” manufactured by Tosoh Corporation
Eluent: THF
Temperature: Column constant temperature bath 40.0℃
Flow rate: 0.6ml/min
Concentration: 0.1 mg/mL (0.1 wt/vol%)
Calibration curve: Standard polystyrene sample manufactured by Tosoh Corporation Injection volume: 100μl
Solubility: Completely dissolved (heated at 40℃)
Pretreatment: Filtration with a 0.2 μm filter Detector: Differential refractometer (RI).

≪Measurement of volume-based median diameter of various particles≫
The volume-based median diameter of the toner base particles was measured using a measuring device in which a Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.) was connected to a computer system equipped with data processing software Software V3.51. In addition, the volume-based median diameters of various resin particles, colorant particles, core particles, toner particles, other additive particles, etc. were also measured in the same manner as above.

Specifically, 0.02 g of a sample (for example, toner base particles) is mixed with 20 mL of a surfactant solution (for the purpose of dispersing the toner base particles, for example, a neutral detergent containing a surfactant component is diluted 10 times with pure water. After adding it to a diluted surfactant solution and blending it in, ultrasonic dispersion treatment was performed for 1 minute to prepare a dispersion of toner base particles. This dispersion of toner base particles was injected into a beaker containing ISOTON II (manufactured by Beckman Coulter, Inc.) in a sample stand using a pipette until the concentration indicated on the measuring device reached 8%. By setting this concentration, reproducible measurement values can be obtained.

Then, in the measuring device, the number of particles to be measured is set to 25,000, the aperture diameter is set to 100 μm, the measurement range of 2 to 60 μm is divided into 256, and the frequency value is calculated, and the frequency value is calculated by dividing the measurement range from 2 to 60 μm into 256. % particle size was determined as a volume-based median diameter.

≪Measurement of the volume-based median diameter of the carrier≫
The volume-based median diameter of the carrier was measured using a laser diffraction particle size distribution analyzer HELOS (manufactured by SYMPATEC) equipped with a wet disperser.

<<Measurement of average circularity of toner base particles>>
The average circularity of the toner base particles was measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex), using a predetermined number (in the example, the number of HPF detections was 4000 in HPF (high magnification imaging) mode). The sum of the circularity C calculated from the following formula from the perimeter L1 of a circle having the same projected area as the particle image and the perimeter L2 of the particle projection image in the toner base particles ( It was calculated by dividing the Note that the measurement can also be performed using an apparatus similar to the flow particle image analyzer "FPIA-3000" (manufactured by Sysmex), such as FPIA-2100 (manufactured by Sysmex). Further, if the number of HPF detections is in the appropriate concentration range of 3,000 to 10,000, sufficient reproducibility can be obtained.

≪Measurement of acid value of resin≫
The acid value of the resin was measured in accordance with JIS K2501:2003.

<<Average dispersion diameter of colorant in toner (Dw, Dc)>>
(Method for preparing sections of toner particles)
After adding 3 parts by mass of the produced toner particles to 35 parts by mass of a 0.2% aqueous solution of polyoxyethyl phenyl ether and dispersing them, they were sonicated at 25°C using ultrasonic waves (manufactured by Nippon Seiki Seisakusho Co., Ltd., US-1200T). The treatment was performed for 5 minutes to remove the external additive from the surface of the toner particles to obtain toner particles for observation. 1 to 2 mg of the obtained toner particles were placed in a 10 mL sample bottle, dyed under ruthenium tetroxide (RuO ₄ ) vapor staining conditions, and then placed in a photocurable resin "D-800" (manufactured by JEOL Ltd.). and photocured to form blocks. Next, after producing a thin section using the FIB processing apparatus described below, cross-sectional observation was performed.

(Ruthenium tetroxide staining conditions)
Staining was performed using a vacuum electronic staining device VSC1R1 (manufactured by Philgen Co., Ltd.). According to the device procedure, a sublimation chamber containing ruthenium tetroxide is installed in the main body of the dyeing device, and after introducing the above-mentioned toner particles into the dyeing chamber, the dyeing conditions with ruthenium tetroxide are set at room temperature (24 to 25 degrees Celsius) and at a concentration of 3. (300 Pa) for 10 minutes.

(FIB processing)
FIB processing was performed under the following equipment conditions.

Device: SMI2050 made by SII
Processing ion: (Ga 30kV)
Sample thickness: 200nm to 250nm.

(Observation of toner cross section)
The cross section of the toner was observed using a transmission electron microscope (TEM). Specifically, a cross section of the toner was photographed using a transmission electron microscope (TEM), and the dispersed diameter of the colorant particles was determined as a circular equivalent diameter using an image processing and analysis device LUZEX AP (manufactured by Nireco Co., Ltd.). 100 particles were randomly extracted and calculated as an arithmetic mean value to determine the average dispersion diameters Dw and Dc of the colorant.

[Preparation of cyan toner 1]
<Synthesis of crystalline polyester resin and preparation of dispersion>
(Synthesis of crystalline polyester resin)
The following raw material monomers and radical polymerization initiator for styrene acrylic polymerization segment (StAc), including bireactive monomers, were placed in the dropping funnel:
Styrene (St) 36.0 parts by mass n-butyl acrylate (BA) 13.0 parts by mass Acrylic acid (Ac) (ambivalent monomer) 2.0 parts by mass Radical polymerization initiator (di-t-butylper oxide) 7.0 parts by mass.

In addition, the following raw material monomers for crystalline polyester polymerization segments (CPEs) were placed in a four-necked flask equipped with a nitrogen gas introduction tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve them. Ta:
Tetradecanedioic acid 440 parts by mass 1,4-butanediol 153 parts by mass.

Next, raw material monomers for styrene acrylic polymerized segments (StAc) were added dropwise over 90 minutes with stirring, and after aging for 60 minutes, unreacted raw material monomers were removed under reduced pressure (8 kPa). .

Note that the amount of raw material monomer removed at this time was extremely small compared to the raw material monomer charged above. Thereafter, 0.8 parts by mass of titanium tetrabutoxide (Ti(O-n-Bu) ₄ ) was added as an esterification catalyst, the temperature was raised to 235°C, and the temperature was increased for 5 hours under normal pressure (101.3 kPa). The reaction was carried out under reduced pressure (8 kPa) for 1 hour.

Next, after cooling to 200° C., the mixture was reacted for 1 hour under reduced pressure (20 kPa) to obtain a crystalline polyester resin (hybrid crystalline polyester resin). The obtained crystalline polyester resin had an acid value of 20.9 mgKOH/g, a weight average molecular weight (Mw) of 25200, a melting point (Tm) of 74.9°C, and a recrystallization temperature (Rc) of 69.7°C. there were.

(Preparation of crystalline polyester resin particle dispersion)
72 parts by mass of the crystalline polyester resin obtained above was dissolved in 72 parts by mass of methyl ethyl ketone by stirring at 70° C. for 30 minutes. Next, 3.0 parts by mass of a 25% by mass aqueous sodium hydroxide solution was added to this solution. This solution was placed in a reaction vessel equipped with a stirrer, and while stirring, 252 parts by mass of water heated to 70° C. was added dropwise and mixed over 70 minutes. During the dropping, the liquid in the container became cloudy, and after the entire amount was dropped, a uniform emulsified state was obtained.

Next, while keeping this emulsion at 70°C, the methyl ethyl ketone was distilled off by stirring under reduced pressure of 15 kPa (150 mbar) using a diaphragm vacuum pump "V-700" (manufactured by BUCHI) for 3 hours. , an aqueous dispersion of crystalline polyester resin was prepared. The particles contained in the above dispersion had a volume-based median diameter of 110 nm.

[Preparation of vinyl resin particle dispersion liquid 1 for core particles]
(1st stage polymerization)
8 parts by mass of sodium lauryl sulfate and 3,000 parts by mass of ion-exchanged water were charged into a 5 L reaction vessel equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen introduction device, and while stirring at a stirring speed of 230 rpm under a nitrogen stream, The internal temperature was raised to 80°C. After raising the temperature, a solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, the temperature was raised to 80°C again, and a mixed solution of the following monomers was added dropwise over 1 hour:
Styrene (St) 480.0 parts by mass n-butyl acrylate (BA) 250.0 parts by mass Methacrylic acid (MAA) 68.0 parts by mass.

After dropping the above liquid mixture, the monomers were polymerized by heating and stirring at 80° C. for 2 hours to prepare a vinyl resin particle dispersion (1-a).

(Second stage polymerization)
A solution of 7 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 3000 parts by mass of ion-exchanged water was charged into a 5 L reaction vessel equipped with a stirring device, a temperature sensor, a cooling pipe, and a nitrogen introduction device. Heated to 98°C. After heating, 80 parts by mass of the vinyl resin particle dispersion (1-a) prepared by the above first stage polymerization in terms of solid content, and the following monomers, chain transfer agent, and mold release agent were dissolved at 90°C. Added the mixed solution:
Styrene (St) 285.0 parts by mass n-Butyl acrylate (BA) 95.0 parts by mass Methacrylic acid (MAA) 20.0 parts by mass n-octyl-3-mercaptopropionate (chain transfer agent) 1.5 parts by mass Parts Behenylbehenate (mold release agent, melting point 73°C) 190.0 parts by mass.

Mixing and dispersion treatment was performed for 1 hour using a mechanical dispersion machine Cleamix (registered trademark) (manufactured by M Techniques) having a circulation path to prepare a dispersion containing emulsified particles (oil droplets). A polymerization initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 84°C for 1 hour to conduct polymerization. A vinyl resin particle dispersion (1-b) was prepared.

(Third stage polymerization)
After further adding 400 parts by mass of ion-exchanged water to the vinyl resin particle dispersion (1-b) obtained by the second stage polymerization and mixing well, 11 parts by mass of potassium persulfate was added to 400 parts by mass of ion-exchanged water. The dissolved solution was added. Furthermore, under a temperature condition of 82°C, a mixture of the following monomer and chain transfer agent was added dropwise over 1 hour:
Styrene (St) 454.8 parts by mass 2-ethylhexyl acrylate (2EHA) 143.2 parts by mass Methacrylic acid (MAA) 52.0 parts by mass n-octyl-3-mercaptopropionate 8.0 parts by mass.

After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, followed by cooling to 28° C. to prepare a vinyl resin dispersion liquid 1 for core particles. The weight average molecular weight (Mw) of vinyl resin 1 in the dispersion was 31,000, and the glass transition temperature (Tg) was 49°C. Furthermore, the vinyl resin particles in the dispersion had a volume-based median diameter of 230 nm.

[Synthesis of amorphous polyester resin for shell layer and preparation of its dispersion]
(Synthesis of amorphous polyester resin for shell layer)
Raw material monomers and a radical polymerization initiator for the following styrene acrylic polymerization segment (StAc), including bireactive monomers, were placed in a dropping funnel.

Styrene (St) 80.0 parts by mass n-butyl acrylate (BA) 20.0 parts by mass Acrylic acid (Ac) 10.0 parts by mass Di-t-butyl peroxide (polymerization initiator) 16.0 parts by mass.

In addition, raw material monomers for the following amorphous polyester polymerized segments (APEs) were placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve them. Ta:
Bisphenol A propylene oxide 2 mole adduct 200.0 parts by mass Bisphenol A ethylene oxide 2 mole adduct 85.7 parts by mass Terephthalic acid 66.9 parts by mass Fumaric acid 47.4 parts by mass.

While stirring, the liquid mixture placed in the dropping funnel was dropped into a four-necked flask over 90 minutes, and after aging for 60 minutes, unreacted monomers were removed under reduced pressure (8 kPa). Thereafter, 0.4 parts by mass of titanium tetrabutoxide (Ti(O-n-Bu) ₄ ) was added as an esterification catalyst, the temperature was raised to 235°C, and the temperature was raised to 235°C for 5 hours under normal pressure (101.3 kPa). Further, the reaction was carried out for 1 hour under reduced pressure (8 kPa). Next, the mixture was cooled to 200° C., reacted under reduced pressure (20 kPa), and then the solvent was removed to obtain an amorphous polyester resin for a shell layer (hybrid amorphous polyester resin). The obtained amorphous polyester resin for shell layer had an acid value of 18.8 mgKOH/g, a weight average molecular weight (Mw) of 25,000, and a glass transition temperature (Tg) of 60°C.

(Preparation of amorphous polyester resin particle dispersion for shell layer)
72 parts by mass of the shell layer amorphous polyester resin obtained above was added to 72 parts by mass of methyl ethyl ketone, and the mixture was stirred at 70° C. for 30 minutes to dissolve. Next, 3.0 parts by mass of a 25% by mass aqueous sodium hydroxide solution was added to this solution. This solution was placed in a reaction vessel equipped with a stirring device, and while stirring, 252 parts by mass of water warmed to 70° C. was added dropwise and mixed over 70 minutes. During the dropping, the liquid in the container became cloudy, and after the entire amount was dropped, a uniform emulsified state was obtained.

Next, while keeping this emulsion at 70°C, the methyl ethyl ketone was distilled off by stirring under reduced pressure of 15 kPa (150 mbar) using a diaphragm vacuum pump "V-700" (manufactured by BUCHI) for 3 hours. , an aqueous dispersion of an amorphous polyester resin was prepared. The particles contained in the above dispersion had a volume-based median diameter of 92 nm.

[Preparation of cyan colorant particle dispersion C1]
Phthalocyanine compound (cyan colorant) c1 shown in Table 1 below was synthesized according to the method described in paragraphs "0046" to "0049" of JP 2019-99047A.

While stirring a solution of 90 parts by mass of sodium lauryl sulfate added to 1,600 parts by mass of ion-exchanged water, 420 parts by mass of phthalocyanine compound c1 was gradually added. A cyan colorant particle dispersion liquid C1 was prepared by carrying out a dispersion treatment for 60 minutes using a stirrer called CLEAMIX (registered trademark) (manufactured by M Technique Co., Ltd.). The colorant particles in the dispersion had a volume-based median diameter of 110 nm.

[Manufacture of cyan toner 1]
In a reaction vessel equipped with a stirring device, a temperature sensor, and a cooling tube, 285 parts by mass of vinyl resin particle dispersion 1 for core particles (in terms of solid content), 40 parts by mass of crystalline polyester resin particle dispersion (in terms of solid content), 1% by mass (in terms of solid content) of dodecyl diphenyl ether disulfonic acid sodium salt and 2000 parts by mass of ion-exchanged water were added. At room temperature (25° C.), a 5 mol/L aqueous sodium hydroxide solution was added to adjust the pH to 10.

Furthermore, 30 parts by mass (solid content equivalent) of cyan colorant particle dispersion C1 was added, and a solution of 60 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water was heated at 30°C for 10 minutes under stirring. Added. After leaving for 3 minutes, the temperature was raised to 80°C over 60 minutes. After the liquid temperature reached 80°C, the stirring speed was adjusted so that the particle size growth rate was 0.01 μm/min, and Coulter Mulch was added. It was grown until the volume-based median diameter measured with Sizer 3 (manufactured by Beckman Coulter, Inc.) was 5.7 μm.

Next, 37 parts by mass (solid content equivalent) of an amorphous polyester resin particle dispersion for shell layer was added over 30 minutes, and when the supernatant of the dispersion (reaction liquid) became transparent, 190 parts by mass of sodium chloride was added. An aqueous solution prepared by dissolving 760 parts by mass of ion-exchanged water was added to stop the growth of particle size.

Further, by heating and stirring at 80° C., the particles are fused together, and the average circularity of the toner base particles is measured to be 0.00000000000000000000000000000000000000000. When the temperature reached 970, it was cooled to 30°C at a cooling rate of 2.5°C/min.

Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and solid-liquid separation was repeated three times for washing, followed by drying at 40° C. for 24 hours to obtain toner base particles.

To 100 parts by mass of the obtained toner base particles, 0.6 parts by mass of hydrophobic silica particles (number average primary particle diameter: 12 nm, degree of hydrophobicity: 68), hydrophobic titanium oxide particles (number average primary particle diameter: 20 nm, Hydrophobicity degree: 63) 1.0 parts by mass and 1.0 parts by mass of sol-gel silica (number average primary particle size = 110 nm) were added, and the mixture was mixed with a Henschel mixer (manufactured by Nippon Coke Kogyo Co., Ltd.) at a rotor circumferential speed of 35 mm/ and mixed for 20 minutes at 32°C. After mixing, coarse particles were removed using a 45 μm sieve to obtain cyan toner 1. Note that the volume-based median diameter of the cyan toner 1 was 5.6 μm. Further, the average dispersion diameter (Dc) of the phthalocyanine compound (cyan colorant) c1 in the cyan toner was 180 nm.

[Preparation of cyan toners 2 to 18]
Phthalocyanine compounds (cyan colorant) c2 to c13 shown in Table 2 below were synthesized according to the method described in paragraphs "0046" to "0049" of JP 2019-99047A. In Table 2 below, "C ₆ H ₅ " represents a phenyl group, "C ₁₂ H ₂₅ " represents an n-dodecyl group, and "C ₂₂ H ₄₅ " represents an n-docosyl group. Furthermore, "-" in Table 2 below indicates that the substituent is not present. Ra ₁ to Ra ₄ of phthalocyanine compound c3 are all chloro groups, and na 1 to na 4 are all 1. Phthalocyanine compound c14 is C. I. pigment blue 15:3.

Cyan toners 2 to 18 were prepared in the same manner as in the preparation of cyan toner 1, except that the type of phthalocyanine compound and the dispersion treatment time during preparation of the cyan colorant particle dispersion were changed as shown in Table 2 below. was created.

The compositions of cyan toners 1 to 18 are shown in Table 2 below. The volume-based median diameters of all cyan toners 1 to 18 were 5.6 μm.

(Preparation of cyan developers 1 to 18)
For the cyan toners 1 to 18 prepared above, a carrier coated with a silicone resin (a ferrite carrier with a volume-based median diameter of 60 μm) was added to the toner content ( Cyan developers 1 to 18 were prepared by adding and mixing so that the toner concentration was 6% by mass.

(Preparation of white toner 1)
3 parts by mass of tricalcium phosphate was added to 900 parts by mass of ion-exchanged water heated to 70° C., and the mixture was stirred at 10,000 rpm using a TK homomixer (manufactured by Primix Co., Ltd.) to obtain an aqueous medium.

Styrene (St) 80.0 parts by mass n-butyl acrylate (BA) 20.0 parts by mass Divinylbenzene 1.0 parts by mass Amorphous polyester resin 4.5 parts by mass (Combined with bisphenol A propylene oxide adduct and isophthalic acid) Polycondensate, glass transition temperature (Tg) = 65 ° C., number average molecular weight (Mn) = 17000, weight average molecular weight (Mw) / number average molecular weight (Mn) = 2.4)
Aluminum salicylate compound 1.0 parts by mass (Bontron E-88, manufactured by Orient Chemical Industry Co., Ltd.)
Titanium oxide (white colorant) 25.0 parts by mass The above materials were uniformly dispersed and mixed for 60 minutes using an attritor (manufactured by Nippon Coke Industry Co., Ltd.) to prepare a polymerizable monomer composition. The obtained polymerizable monomer composition was heated to 63° C., 9 parts by mass of an ester wax mainly composed of stearyl stearate was added thereto, mixed and dissolved, and a polymerization initiator, 2, 3 parts by mass of 2'-azobis-2-methylbutyronitrile was added and dissolved to prepare a polymerizable monomer mixture.

The polymerizable monomer mixture obtained above was put into an aqueous medium, and the mixture was stirred at 63° C. under an N ₂ atmosphere using a TK type homomixer at 10,000 rpm for 7 minutes to granulate. Thereafter, the mixture was reacted at 63° C. for 6 hours while stirring with a paddle stirring blade. Thereafter, the liquid temperature was raised to 80°C, and stirring was continued for an additional 4 hours. After the reaction was completed, the suspension was cooled to room temperature (25° C.), and then hydrochloric acid was added to dissolve the calcium phosphate salt, followed by filtration and washing with water to obtain wet toner base particles.

Next, the toner base particles were dried at 40° C. for 12 hours to obtain white toner base particles having a volume-based median diameter of 7.5 μm and an average circularity of 0.970.

A Henschel ^mixer ( (manufactured by Nippon Coke Industry Co., Ltd.) to obtain white toner 1. The dispersion diameter of the white colorant in White Toner 1 was 380 nm.

<Preparation of white toners 2 to 5>
White toners 2 to 5 were obtained in the same manner as in the preparation of white toner 1, except that the dispersion and mixing time in the attritor was changed and the colorant dispersion diameter in the white toner was changed as shown in Table 3 below.

<Production of white developers 1 to 5>
For each of white toners 1 to 5, a ferrite carrier with a volume average particle diameter of 30 μm coated with a copolymer resin of cyclohexyl methacrylate and methyl methacrylate (monomer mass ratio = 1:1) was added to the toner and carrier. White developers 1 to 5 were obtained by mixing so that the toner concentration was 6% by mass with the total mass being 100% by mass.

(Examples 1 to 19, Comparative Examples 1 to 7)
A commercially available multifunction machine "bizhub PRESS (registered trademark) C1070" (manufactured by Konica Minolta, Inc.) was loaded with cyan developer and white developer in the combinations shown in Table 4 below, and evaluated.

[Color development evaluation]
Prints are made using A4 size glossy paper "POD Gloss Coat 128 (128 g/m ² ) (manufactured by Oji Paper Co., Ltd.)" in a normal temperature and humidity (20°C, 50% RH) environment. Images were formed in the order of white and cyan in the order closest to the paper using toner of 8 g/m ² and cyan toner of 4 g/m ² and thermally fixed.

Color development was evaluated by sensory evaluation using the following criteria for a solid image sample and a 10-tone scale image sample in which the image density was changed in 10 steps. Ten evaluators were recruited to perform sensory evaluations, and their scores were added together to obtain an evaluation score. Therefore, the highest score in this evaluation is 30 points, and the lowest score is 10 points. Pass if the evaluation score is 16 points or higher:
3 points: The solid image does not appear muddy at all, and the 10-tone scale image has a clear finish with intermediate tones. 2 points: The solid image and 10-tone scale image have a slight difference compared to the 3-point image. The finish is inferior, but the color does not appear muddy. 1 point: The finish gives the impression that the color is muddy for both the solid image and the 10-tone scale image.

The results are shown in Table 4 below.

As is clear from Table 4 above, it was found that the images obtained by the image forming method of the examples were superior in color development compared to the images obtained by the image forming method of the comparative examples.

Claims (9)

An electrophotographic image forming method using a white toner and a chromatic toner including a cyan toner, the method comprising:
The white toner contains titanium oxide as a colorant,
The cyan toner contains a phthalocyanine compound represented by the following chemical formula 1 as a main component of the colorant,

In the chemical formula 1,
M is a silicon atom, a germanium atom, or a tin atom,
Ra ₁ to Ra ₄ are each independently an electron-withdrawing substituent,
na1 to na4 are each independently an integer of 0 to 4,
Z ₁ and Z ₂ are each independently an aryloxy group having 6 to 18 carbon atoms, an alkoxy group having 2 to 22 carbon atoms, or a group represented by the following chemical formula 2,

In the chemical formula 2, R ₃ to R ₅ are each independently an alkyl group having 2 to 6 carbon atoms, an aryl group having 6 to 18 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms,
When the average dispersion diameter of the colorant in the white toner is Dw, and the average dispersion diameter of the phthalocyanine compound in the cyan toner is Dc, Dw and Dc satisfy the following formulas 1 and 2 ,
An electrophotographic image forming method , wherein the ratio of the Dw to the Dc (Dw/Dc) satisfies the following formula 5' .
The electrophotographic image forming method according to claim 1, wherein the content of the titanium oxide in the white toner is 10 to 40% by mass. 3. The electrophotographic image forming method according to claim 1, wherein M in the chemical formula 1 is a silicon atom. The electrophotographic image forming method according to any one of claims 1 to 3, wherein Z ₁ and Z ₂ in the chemical formula 1 are each independently a group represented by the chemical formula 2. R in the chemical formula 2 ₃ ～R ₅ each independently consists of an ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, n-pentyl group, neopentyl group and n-hexyl group 5. The electrophotographic imaging method according to claim 4, wherein the electrophotographic imaging method is selected from the group. Z in the chemical formula 1 ₁ and Z ₂ each independently represents an ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, t-butyloxy group, n-pentyloxy group, neopentyloxy group, n-hexyloxy group, isohexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyl Oxy group, n-tetradecyloxy group, n-octadecyloxy group, n-eicosyloxy group, n-docosyloxy group, 2-ethylhexyloxy group, 3-ethylheptyloxy group, 3-ethyldecyloxy group, 2- The electrophotographic image forming method according to any one of claims 1 to 3, wherein the electrophotographic image forming method is selected from the group consisting of hexyldecyloxy group, cyclopentyloxy group, cyclohexyloxy group, and cycloheptyloxy group. The electrophotographic image forming method according to any one of claims 1 to 6 , wherein the Dw and Dc satisfy the following formulas 3 and 4.
The electrophotographic image forming method according to any one of claims 1 to 7 , wherein the chromatic toner contains a crystalline polyester resin. The electron according to any one of claims 1 to 8 , wherein the content of the phthalocyanine compound represented by the chemical formula 1 in the cyan toner is 4 to 12% by mass based on the total mass of the cyan toner. Photographic image formation method.