JP2024114426A - Resin particle, toner, method for manufacturing resin particle, toner storage unit, developer, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin particle that is excellent in low temperature fixability, heat-resistant storage properties, and electrification characteristics despite use of plant-derived resin with less environmental load.

SOLUTION: A resin particle includes at least amorphous polyester resin and crystalline polyester resin. The amorphous polyester resin includes a constitutional unit derived from a plant-derived alcohol monomer as an alcohol component. The resin particle forms a core-shell structure comprising a core layer and a shell layer. The shell layer includes at least polyester resin having a sulfonate group.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to resin particles, toner, a method for producing resin particles, a toner storage unit, a developer, an image forming apparatus, and an image forming method.

Toner is required to have small particle size to improve the quality of output images, low-temperature fixability to save energy, and heat-resistant storage properties that can withstand high temperatures and humidity during storage and transportation after production. In particular, since the power consumption during fixation accounts for a large portion of the power consumption in the image formation process, improving low-temperature fixability is extremely important.

To solve the above problems, a method for producing toner using a polymerization method has been proposed. Toner produced by a polymerization method can be easily made small in particle size, and the particle size distribution is sharper than that of toner produced by a pulverization method. A method for producing toner that includes an aging process to produce a toner binder with a stable molecular weight distribution and achieve both low-temperature fixability and high-temperature offset resistance has also been disclosed (see, for example, Patent Documents 1 and 2).

Furthermore, toners with excellent low-temperature fixing properties have various issues. One is the trade-off with heat-resistant storage properties. When even higher low-temperature fixing properties are required, a means is required that also achieves the opposing heat-resistant storage properties. Up until now, a means has been proposed in which the surface of the toner base particles is covered with a resin to ensure heat resistance (see, for example, Patent Document 3 and Patent Document 4).

The following methods have been proposed to improve charging performance.
(1) A method in which a fluorosurfactant having an opposite polarity to the surfactant used in the granulation step is added after the emulsification dispersion step, the solvent removal step, the washing step, and the redispersion step in water (see, for example, Patent Document 5)
(2) A method of obtaining fixing properties, cleaning properties, and charging performance by incorporating a modified layered inorganic mineral modified with an organic ion (see, for example, Patent Document 6)
(3) A method in which a surfactant having a sulfonic acid group is used to ensure stability during toner production, and a surfactant having a carboxyl group is used to suppress the penetration of the sulfonic acid group-containing surfactant into the inside of the aggregated particles, thereby ensuring the chargeability of the aggregated particles in the mixed dispersion during production (see, for example, Patent Document 7).

Furthermore, in recent years, toners are required to not only have high quality, but also to reduce the burden on the environment. To this end, energy reduction in the manufacturing process and the use of plant-derived resins as binder resins are being considered (see, for example, Patent Documents 8 and 9).

The toners obtained by the methods described in Patent Documents 1 and 2 do not satisfy the high level of low-temperature fixability that has been demanded in recent years.
The toners described in Patent Documents 3 and 4 have a trade-off with low-temperature fixing performance. In addition, the softness derived from the crystalline segment is not fundamentally improved, and the problem related to the mechanical durability of the toner is not solved. Therefore, there is also a problem that the softness reduces the ability to retain triboelectric charge, and toner scattering and background scumming are likely to occur.

None of the toners obtained by the methods described in Patent Documents 5 to 7 satisfy the requirements for excellent low-temperature fixing property, excellent charging performance, and heat-resistant storage stability.
The plant-derived resin in the toner obtained by the method described in Patent Documents 8 and 9 does not have an aromatic ring skeleton in its constituent monomer, so it is difficult to obtain the desired mechanical strength, and the strength of the toner is reduced, making it difficult to achieve both the low-temperature fixability and heat-resistant storage stability described above.

The present invention aims to solve the above-mentioned problems in the prior art and to achieve the following objects.
An object of the present invention is to provide resin particles that are excellent in low-temperature fixability, heat-resistant storage stability, and electrostatic chargeability even when using a plant-derived resin that places less of a burden on the environment.

The present inventors have conducted extensive research in order to solve the above problems.
The means for solving the above problems are as follows.
Resin particles containing at least an amorphous polyester resin and a crystalline polyester resin,
The amorphous polyester resin contains a structural unit derived from a plant-derived alcohol monomer,
the resin particles form a core-shell structure consisting of a core layer and a shell layer,
The resin particles, wherein the shell layer contains at least a polyester resin having a sulfonate group.

The present invention can solve the above-mentioned problems that existed in the past, and can provide resin particles that have excellent low-temperature fixability, heat-resistant storage stability, and electrostatic chargeability even when using plant-derived resins that have a low environmental impact.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an example of a process cartridge.

<Environmentally friendly resin>
Biomass-derived resin is a resin containing plant-derived compounds as raw materials, and is an environmentally friendly resin. By adjusting the ratio of petroleum-derived and plant-derived alcohol and acid components, the environmental friendliness ratio and toner quality can be adjusted. The amount of biomass resin in the present invention is calculated from the amount of monomer charged during production.

When the resin monomer composition is unknown, the amount of biomass resin can be specified by specifying the radioactive carbon isotope ¹⁴ C concentration and monomers by the method described below.

(Radiocarbon isotope ^14C concentration)
The radioactive carbon isotope ¹⁴ C concentration (hereinafter, sometimes referred to as “ ¹⁴ C concentration”) of the resin particles according to one embodiment is 10.8 pMC or more, preferably 11 pMC or more, more preferably 20 pMC or more, and more preferably 30 pMC or more. If the concentration of ^the radioactive carbon isotope C in the resin particles is less than 10.8 pMC, it is generally likely to be recognized as having a low biomass degree, which will be described later, and a reduction in the burden on the environment cannot be achieved.

¹⁴ C exists in nature (in the atmosphere) and is taken up by photosynthesis while plants are active, maintaining equilibrium (107.5 pMC) with ^{the 14} C concentration in the atmosphere. However, once a living organism ceases to function, the uptake by photosynthesis ceases and ^{the 14} C concentration decreases in accordance with the half-life of ¹⁴ C, which is 5,730 years. Fossil resources derived from living organisms have been around for tens of thousands to hundreds of millions of years since their life activities ceased, so ¹⁴ C concentrations are barely detectable.

Here, "pMC" is an abbreviation for percent modern carbon, and the ratio of ¹⁴ C to ¹² C ( ¹⁴ C/ ¹² C) in biomass in 1950 is defined as 100 pMC. However, since the current concentration of ¹⁴ C in the atmosphere is increasing year by year, it is stipulated that this value must be multiplied by a coefficient for correction. The correction coefficient to be used is the coefficient corresponding to the year.

The ¹⁴ C concentration can also be expressed as a biomass degree calculated by the following formula (1).
Biomass degree (%) = ¹⁴ C concentration (pMC) / 107.5 × 100 ... formula (1)
A ¹⁴ C concentration of 10.8 pMC or more means that the biomass ratio is 10% or more. The biomass ratio of 10% or more is a concentration desired from the viewpoint of carbon neutrality.

The method for measuring the ¹⁴ C concentration is not particularly limited and can be appropriately selected depending on the purpose, but radiocarbon dating is particularly preferred.
The measurement procedure of the radiocarbon dating method is as follows: resin particles are burned, and the carbon dioxide (CO ₂ ) is reduced to obtain graphite (C). The ¹⁴ C concentration of the graphite is measured using an accelerator mass spectrometry (AMS, manufactured by Beta Analytic). This measurement using AMS is disclosed in, for example, Japanese Patent No. 4050051.

<Resin Particles>
The resin particles of the present invention contain at least an amorphous polyester resin and a crystalline polyester resin, the alcohol component of the amorphous polyester resin contains a plant-derived alcohol monomer, the resin particles form a core-shell structure, and the shell layer contains at least a polyester resin containing a sulfonate group.
The resin particles of the present invention have a core-shell structure consisting of a core layer and a shell layer, and thus can ensure heat-resistant storage stability.

The alcohol component of the amorphous polyester resin used in the present invention contains a plant-derived alcohol monomer, which can enhance carbon neutrality. As the plant-derived alcohol monomer, it is preferable to use propylene glycol, which is a saturated aliphatic alcohol, since propylene glycol is a plant-derived alcohol component that is industrially distributed in relatively large quantities around the world. Saturated aliphatic alcohols have the effect of enhancing the recrystallization properties of crystalline polyester resins, increasing the aspect ratio of crystalline polyester resins, and improving low-temperature fixability. On the other hand, the use of aromatic alcohol components is reduced by using plant-derived alcohols, and even if they are not used at all, the toughness of the polyester resin decreases, and the heat-resistant storage stability and durability decrease.

By making the shell layer out of polyester resin containing sulfonate groups, the charge-imparting effect of the sulfonate groups can provide high charging performance. In addition, the viscoelasticity-imparting effect of the sulfonate groups can supplement the strength of the toner, making it possible to achieve both low-temperature fixing properties and storage stability while still improving carbon neutrality.

The sulfonate group content in the sulfonate group-containing polyester resin is preferably 2 mol% or more and 10 mol% or less, more preferably 4 mol% or more and 8 mol% or less, based on the total amount of the carboxylic acid monomers constituting the sulfonate group-containing polyester resin. If it is less than 2 mol%, the charging performance of the sulfonate group cannot be sufficiently obtained. If it exceeds 10 mol%, the hygroscopicity of the sulfonate group is strongly expressed, so that the charging performance is reduced. In addition, the heat-resistant storage stability is also reduced due to the moisture absorption.
The resin particles of the present invention are included in the present invention so long as they satisfy the above conditions, but the effect obtained is even greater when they are toner.

<Plant-derived resin>
The plant-derived component is not particularly limited as long as it is a component derived from a plant, and can be appropriately selected depending on the purpose, and examples thereof include monomers derived from plants or monomers that can be replaced with the plant-derived component, etc. These may be used alone or in combination of two or more kinds.

In recent years, it has become possible to replace petroleum-derived materials with plant-derived materials, and plant-derived materials such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, glycerin, succinic acid, itaconic acid, sebacic acid, and dodecanedioic acid are already being commercialized.

In the present specification, the monomer that can be replaced by the plant-derived component is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include plant-derived ethylene glycol, plant-derived propylene glycol, plant-derived 1,3-propanediol, plant-derived 1,4-butanediol, plant-derived neopentyl glycol, plant-derived glycerin, plant-derived succinic acid, plant-derived itaconic acid, plant-derived sebacic acid, and plant-derived dodecanedioic acid. These may be used alone or in combination of two or more. The monomer that can be replaced by the plant-derived component is preferably a commercially available plant-derived monomer in terms of ease of availability, but may also be one obtained by separating it from a plant as appropriate. The plant-derived component may be referred to as an "environmentally friendly component".

<Recycled resin>
The recycled resin is made by processing recycled materials, such as PET (polyethylene terephthalate) and PBT (polybutylene terephthalate), into flakes, with a weight average molecular weight (Mw) of about 30,000 to 90,000, but there are no restrictions on the molecular weight distribution, composition, manufacturing method, or form of use of the PET and PBT. There is also no restriction on recycled materials, and off-spec fiber waste or pellets may be used. By adjusting the ratio of recycled PET introduced during polyester resin synthesis, the environmental response ratio and toner quality can be adjusted.

<Core-shell structure>
The resin particles have a core-shell structure consisting of a core layer and a shell layer. The shell resin constituting the shell layer is preferably the amorphous polyester resin A described below, and the amorphous polyester resin contained in the core is preferably the amorphous polyester resin B described below.

In this specification, "having a core-shell structure" means a structure having a core layer and a shell layer, "shell layer" means a layer made of a resin present in the outermost layer of the resin particle, and "core layer" means a region within the resin particle excluding the shell layer.
The core layer and the shell layer are not completely compatible with each other and are formed inhomogeneously.
In the core-shell structure, the surface of the core layer is preferably covered with the shell layer.

In the core-shell structure, the surface of the core layer may be completely covered by the shell layer, or may not be completely covered by the shell layer. Examples of a form in which the surface of the core layer is not completely covered by the shell layer include a form in which the core layer is covered by the shell layer in a mesh-like pattern, and a form in which the core layer is partially exposed from the shell layer. Among these, from the viewpoint of heat-resistant storage stability, it is preferable that the surface of the core layer is completely covered by the shell layer.

<Amorphous Polyester Resin>
As the polyester resin containing a sulfonate group, the following amorphous polyester resin A is preferable, and as the amorphous polyester resin contained in the core of the resin particles, the below-mentioned amorphous polyester resin B is preferable.

(Amorphous polyester resin A)
A linear polyester resin is preferable as the amorphous polyester resin A. An unmodified polyester resin is preferable as the amorphous polyester resin A. The amorphous polyester resin A is a polyester resin soluble in tetrahydrofuran (THF) and chloroform.

The unmodified polyester resin is a polyester resin obtained using a polyhydric alcohol and a polycarboxylic acid or a derivative thereof, and is not modified by a compound or the like. The amorphous polyester resin A preferably does not have a urethane bond or a urea bond. By using the environmentally friendly component in at least one of the polyhydric alcohol isocyanate and the polycarboxylic acid or a derivative thereof, the amorphous polyester resin A can be the environmentally friendly component. In addition, the amorphous polyester resin A is preferably an amorphous polyester resin having a sulfonate group. By containing a sulfonate group, stability is improved when it is made into an aqueous dispersion.

-Polyhydric alcohol-
The polyhydric alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polyhydric alcohol include diols.

Examples of the diol include an alkylene (having 2 to 3 carbon atoms) oxide (average number of moles added: 1 to 10) adduct of bisphenol A, ethylene glycol, butylene glycol, propylene glycol, hydrogenated bisphenol A, and an alkylene (having 2 to 3 carbon atoms) oxide (average number of moles added: 1 to 10) adduct of hydrogenated bisphenol A.
Examples of the alkylene (having 2 to 3 carbon atoms) oxide (average number of moles added: 1 to 10) adduct of bisphenol A include polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane.

These may be used alone or in combination of two or more. Among these, the polyhydric alcohol preferably includes ethylene glycol derived from plants or from the recycled PET, butylene glycol derived from plants or from the recycled PBT, propylene glycol derived from plants, 1,3-propanediol derived from plants, 1,4-butanediol derived from plants, and neopentyl glycol derived from plants, in terms of enhancing environmental compatibility.

For the purpose of adjusting the acid value and hydroxyl value, the amorphous polyester resin A may contain a trivalent or higher alcohol at the end of the resin chain.
Examples of the trihydric or higher alcohol include glycerin, pentaerythritol, and trimethylolpropane. Use of plant-derived glycerin can improve environmental friendliness.

-Polycarboxylic acid or its derivative-
The polyvalent carboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polyvalent carboxylic acid include dicarboxylic acids.
Examples of the dicarboxylic acid include adipic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, succinic acid, sebacic acid, dodecanedioic acid, and succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms.
Examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecenylsuccinic acid and octylsuccinic acid.

The derivative of the polycarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. For example, a polycarboxylic acid anhydride or a polycarboxylic acid ester can be used.
These may be used alone or in combination of two or more.
Among these, the polycarboxylic acid preferably contains succinic acid, sebacic acid, or dodecanedioic acid, which are saturated aliphatic acids derived from plants or recycled PET or PBT, as the environmentally friendly component. By using the polycarboxylic acid derived from plants or recycled PET or PBT, environmental friendliness can be improved.

The amorphous polyester resin A preferably contains a dicarboxylic acid component as a constituent of the amorphous polyester resin A, and the dicarboxylic acid component preferably contains 50 mol % or more of terephthalic acid. This is advantageous in terms of heat resistance storage stability.

For the purpose of adjusting the acid value and hydroxyl value, the amorphous polyester resin A may contain a trivalent or higher carboxylic acid at the end of the resin chain.
Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, and acid anhydrides thereof.

- Aromatic dicarboxylic acid having a sulfonate group -
The sulfonate group-containing amorphous polyester resin is synthesized using a monomer containing a sulfonate group. Examples of the monomer containing a sulfonate group include an aromatic sulfonate group-containing monomer and an aliphatic sulfonate group-containing monomer. Among these, an aromatic sulfonate group-containing monomer having a divalent or higher carboxylic acid is preferred.

Examples of aromatic dicarboxylic acids having a sulfonate group include sulfonates of 5-sulfoisophthalic acid, 2-sulfoisophthalic acid, 4-sulfoisophthalic acid, 4-sulfo-2,6-naphthalenedicarboxylic acid, and their ester-forming derivatives [lower alkyl (C1-4) esters (methyl esters, ethyl esters, etc.), acid anhydrides, etc.].

Examples of aliphatic dicarboxylic acids having a sulfonate group include sulfosuccinic acid and sulfonates of its ester-forming derivatives [lower alkyl (C1-4) esters (methyl ester, ethyl ester, etc.), acid anhydrides, etc.].

Examples of sulfonate salts include salts of alkali metals (lithium, sodium, potassium, etc.), salts of alkaline earth metals (magnesium, calcium, etc.), ammonium salts, amine salts such as mono-, di-, and tri-amines having a hydroxyalkyl (C2-4) group (organic amine salts such as mono-, di-, and tri-ethylamine, mono-, di-, and tri-ethanolamine, diethylethanolamine, etc.), quaternary ammonium salts of these amines, and combinations of two or more of these.

Among these, 5-sulfoisophthalic acid salts are preferred, with 5-sulfoisophthalic acid sodium salt and 5-sulfoisophthalic acid potassium salt being particularly preferred. The presence of aromatic dicarboxylic acid in the monomer unit increases the rigidity of the polyester molecule, improving the mechanical strength and heat resistance of the polyester film.

The monomer containing sulfonate groups is preferably 2 to 10 mol% relative to the total monomers constituting the amorphous polyester resin. If it is less than 2 mol% relative to the total monomers, the stability of the aqueous dispersion will be reduced. If the sulfonate groups are too small, the charge that repels the resin particles against each other in the aqueous medium will be small, making the resin particles unstable. If it is more than 10 mol% relative to the total monomers, the resin particles will be prone to swelling due to high hydrophilicity, and durability will be reduced when used as a coating or a shell for a toner.

The molecular weight of the amorphous polyester resin A is not particularly limited and can be selected appropriately depending on the purpose, but it is preferably in the following range when measured by GPC.

The weight average molecular weight (Mw) of the amorphous polyester resin A is preferably from 3,000 to 10,000, and more preferably from 4,000 to 10,000.
The number average molecular weight (Mn) of the amorphous polyester resin A is preferably from 1,000 to 4,000, and more preferably from 1,500 to 3,000.
The molecular weight ratio (Mw/Mn) of the amorphous polyester resin A is preferably from 1.0 to 4.0, and more preferably from 1.0 to 3.5.
When the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the amorphous polyester resin A are equal to or greater than the lower limit of the preferred range, the heat-resistant storage stability of the resin particles and the durability against stress such as stirring in a developing machine can be prevented from decreasing. When the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the amorphous polyester resin A are equal to or less than the upper limit of the preferred range, the viscoelasticity of the resin particles when melted can be prevented from increasing, and the low-temperature fixability can be prevented from decreasing.

The acid value of the amorphous polyester resin A is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 mgKOH/g to 50 mgKOH/g, more preferably 5 mgKOH/g to 30 mgKOH/g. When the acid value of the amorphous polyester resin A is 1 mgKOH/g or more, the toner containing the resin particles is likely to be negatively charged, and further, when fixed to a recording medium such as paper, the affinity between the recording medium and the toner is improved, and low-temperature fixing properties can be improved. In addition, when the acid value of the amorphous polyester resin A is 50 mgKOH/g or less, it is possible to suppress a decrease in charging stability, particularly charging stability against environmental changes.
The acid value of the amorphous polyester resin A can be measured in accordance with the measurement method described in JIS K0070-1992.

The hydroxyl value of the amorphous polyester resin A is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 mgKOH/g or more. The upper limit of the hydroxyl value of the amorphous polyester resin B is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 30 mgKOH/g or less. The lower limit and upper limit of the hydroxyl value of the amorphous polyester resin A can be appropriately combined, and is preferably 5 mgKOH/g to 30 mgKOH/g.
The hydroxyl value of the amorphous polyester resin A can be measured in accordance with the measurement method described in JIS K0070-1966.

The glass transition temperature (Tg) of the amorphous polyester resin A is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 40°C or higher and 80°C or lower, and more preferably 50°C or higher and 80°C or lower. When the glass transition temperature (Tg) of the amorphous polyester resin A is 40°C or higher, the toner containing the resin particles has sufficient heat-resistant storage stability and durability against stress such as stirring in a developing machine, and also has good filming resistance. When the glass transition temperature (Tg) of the amorphous polyester resin A is 80°C or lower, the toner containing the resin particles is sufficiently deformed by heating and pressure during fixing, and low-temperature fixing properties are good.

The molecular structure of the amorphous polyester resin A can be confirmed by measurement using nuclear magnetic resonance spectroscopy (NMR) using a solution or solid, as well as measurement using X-ray diffraction, gas chromatography mass spectrometry (GC/MS), liquid chromatography/MS, or infrared absorption spectroscopy (IR). Among these, a method of detecting the amorphous polyester resin A that does not have absorption due to olefin δCH (out-of-plane bending vibration) at 965±10 cm ⁻¹ and 990±10 cm ⁻¹ in an infrared absorption spectrum obtained by IR can be mentioned.

The content of the amorphous polyester resin A is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 50 parts by mass or more and 90 parts by mass or less, and more preferably 60 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the resin particles.

When the content of the amorphous polyester resin A is 50 parts by mass or more relative to 100 parts by mass of the resin particles, the dispersibility of the pigment or release agent in the resin particles can be prevented from deteriorating, and the occurrence of fogging and distortion of the image can be prevented. When the content of the amorphous polyester resin A is 90 parts by mass or less relative to 100 parts by mass of the resin particles, the content of the crystalline resin can be prevented from decreasing, and the deterioration of low-temperature fixability can be prevented. When the content of the amorphous polyester resin A is in the above-mentioned more preferred range, it is advantageous in that both high image quality and low-temperature fixability are excellent.

(Amorphous polyester resin B)
A linear polyester resin is preferable, and an unmodified polyester resin is also preferable, as the amorphous polyester resin B. The amorphous polyester resin B is a polyester resin soluble in tetrahydrofuran (THF) and chloroform.
The unmodified polyester resin is a polyester resin obtained by using a polyhydric alcohol and a polycarboxylic acid or a derivative thereof, and is not modified by an isocyanate compound or the like. The amorphous polyester resin B preferably does not have a urethane bond or a urea bond. By using the environmentally friendly component in at least one of the polyhydric alcohol and the polycarboxylic acid or a derivative thereof, the amorphous polyester resin B can be the environmentally friendly component.

-Polyhydric alcohol-
The polyhydric alcohol is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polyhydric alcohol include diols.
Examples of the diol include an alkylene (having 2 to 3 carbon atoms) oxide (average number of moles added: 1 to 10) adduct of bisphenol A, ethylene glycol, butylene glycol, propylene glycol, hydrogenated bisphenol A, and an alkylene (having 2 to 3 carbon atoms) oxide (average number of moles added: 1 to 10) adduct of hydrogenated bisphenol A.
Examples of the alkylene (having 2 to 3 carbon atoms) oxide (average number of moles added: 1 to 10) adduct of bisphenol A include polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane and polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane.

These may be used alone or in combination of two or more. Among these, the polyhydric alcohol preferably contains ethylene glycol derived from plants or the recycled PET, butylene glycol derived from plants or the recycled PBT, propylene glycol derived from plants, 1,3-propanediol derived from plants, or 1,4-butanediol derived from plants, in terms of enhancing environmental compatibility.
In order to adjust the acid value and hydroxyl value, the amorphous polyester resin B may contain a trivalent or higher alcohol at the end of the resin chain.
Examples of the trihydric or higher alcohol include glycerin, pentaerythritol, and trimethylolpropane. Use of plant-derived glycerin can improve environmental friendliness.

-Polycarboxylic acid or its derivative-
The polyvalent carboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polyvalent carboxylic acid include dicarboxylic acids.

Examples of the dicarboxylic acid include adipic acid, phthalic acid, isophthalic acid, terephthalic acid, fumaric acid, maleic acid, succinic acid, sebacic acid, dodecanedioic acid, and succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms.
Examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecenylsuccinic acid and octylsuccinic acid.

The derivative of the polycarboxylic acid is not particularly limited and can be appropriately selected depending on the purpose. For example, a polycarboxylic acid anhydride or a polycarboxylic acid ester can be used.
These may be used alone or in combination of two or more.
Among these, the polycarboxylic acid preferably contains succinic acid, sebacic acid, or dodecanedioic acid, which are saturated aliphatic acids derived from plants or recycled PET or PBT, as the environmentally friendly component. By using the polycarboxylic acid derived from plants or recycled PET or PBT, environmental friendliness can be improved.

The amorphous polyester resin B preferably contains a dicarboxylic acid component as a constituent of the amorphous polyester resin B, and the dicarboxylic acid component preferably contains 50 mol % or more of terephthalic acid. This is advantageous in terms of heat-resistant storage stability.
For the purpose of adjusting the acid value and hydroxyl value, the amorphous polyester resin B may contain a trivalent or higher carboxylic acid at the end of the resin chain.
Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, and acid anhydrides thereof.

The molecular weight of the amorphous polyester resin B is not particularly limited and may be appropriately selected depending on the purpose, but it is preferably in the following range as measured by GPC.
The weight average molecular weight (Mw) of the amorphous polyester resin B is preferably from 3,000 to 10,000, and more preferably from 4,000 to 10,000.
The number average molecular weight (Mn) of the amorphous polyester resin B is preferably from 1,000 to 4,000, and more preferably from 1,500 to 3,000.
The molecular weight ratio (Mw/Mn) of the amorphous polyester resin B is preferably from 1.0 to 4.0, and more preferably from 1.0 to 3.5.

When the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the amorphous polyester resin B are equal to or greater than the lower limit of the preferred range, the heat-resistant storage stability of the resin particles and the durability against stress such as stirring in a developing machine can be prevented from decreasing. When the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the amorphous polyester resin B are equal to or less than the upper limit of the preferred range, the viscoelasticity of the resin particles when melted can be prevented from increasing, and the low-temperature fixability can be prevented from decreasing.

The acid value of the amorphous polyester resin B is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 1 mgKOH/g to 50 mgKOH/g, more preferably 5 mgKOH/g to 30 mgKOH/g. When the acid value of the amorphous polyester resin B is 1 mgKOH/g or more, the toner containing the resin particles is likely to be negatively charged, and further, when fixed to a recording medium such as paper, the affinity between the recording medium and the toner is improved, and low-temperature fixing properties can be improved. In addition, when the acid value of the amorphous polyester resin B is 50 mgKOH/g or less, it is possible to suppress a decrease in charging stability, particularly charging stability against environmental changes.
The acid value of the amorphous polyester resin B can be measured in accordance with the measurement method described in JIS K0070-1992.

The hydroxyl value of the amorphous polyester resin B is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 mgKOH/g or more. The upper limit of the hydroxyl value of the amorphous polyester resin B is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 30 mgKOH/g or less. The lower limit and upper limit of the hydroxyl value of the amorphous polyester resin B can be appropriately combined, and is preferably 5 mgKOH/g to 30 mgKOH/g.
The hydroxyl value of the amorphous polyester resin B can be measured in accordance with the measurement method described in JIS K0070-1966.

The glass transition temperature (Tg) of the amorphous polyester resin B is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 40°C or higher and 80°C or lower, and more preferably 50°C or higher and 70°C or lower. When the glass transition temperature (Tg) of the amorphous polyester resin B is 40°C or higher, the toner containing the resin particles has sufficient heat-resistant storage stability and durability against stress such as stirring in a developing machine, and also has good filming resistance. When the glass transition temperature (Tg) of the amorphous polyester resin B is 80°C or lower, the toner containing the resin particles is sufficiently deformed by heating and pressure during fixing, and has good low-temperature fixing properties.

The molecular structure of the amorphous polyester resin B can be confirmed by measurement using nuclear magnetic resonance spectroscopy (NMR) using a solution or solid, as well as measurement using X-ray diffraction, gas chromatography mass spectrometry (GC/MS), liquid chromatography/MS, or infrared absorption spectroscopy (IR). Among these, a method of detecting the amorphous polyester resin B that does not have absorption due to olefin δCH (out-of-plane bending vibration) at 965±10 cm ⁻¹ and 990±10 cm ⁻¹ in an infrared absorption spectrum obtained by IR can be mentioned.

The content of the amorphous polyester resin B is not particularly limited and can be appropriately selected according to the purpose, but is preferably 50 parts by mass or more and 90 parts by mass or less, and more preferably 60 parts by mass or more and 80 parts by mass or less, relative to 100 parts by mass of the resin particles. When the content of the amorphous polyester resin B is 50 parts by mass or more relative to 100 parts by mass of the resin particles, the dispersibility of the pigment or release agent in the resin particles can be suppressed from deteriorating, and the occurrence of fogging and disturbance of the image can be suppressed. In addition, when the content of the amorphous polyester resin B is 90 parts by mass or less relative to 100 parts by mass of the resin particles, the content of the crystalline resin can be prevented from decreasing, and the low-temperature fixability can be suppressed from decreasing. When the content of the amorphous polyester resin B is in the above-mentioned more preferred range, it is advantageous in that both high image quality and low-temperature fixability are excellent.

<Crystalline Polyester Resin>
The crystalline polyester resin is obtained from a polyhydric alcohol and a polycarboxylic acid such as a polycarboxylic acid, a polycarboxylic anhydride, or a polycarboxylic ester, or a derivative thereof. In the present invention, the crystalline polyester resin refers to a resin obtained by using a polyhydric alcohol and a polycarboxylic acid such as a polycarboxylic acid, a polycarboxylic anhydride, or a polycarboxylic ester, or a derivative thereof, as described above, and does not include a modified polyester resin, such as a prepolymer, and a resin obtained by subjecting the prepolymer to a crosslinking and/or elongation reaction.

(Polyhydric alcohol)
The polyhydric alcohol is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include diols and trihydric or higher alcohols. Examples of the diols include saturated aliphatic diols. Examples of the saturated aliphatic diols include linear saturated aliphatic diols and branched saturated aliphatic diols. Among these, linear saturated aliphatic diols are preferred, and linear saturated aliphatic diols having 2 to 12 carbon atoms are more preferred. If the saturated aliphatic diol is a branched type, the crystallinity of the crystalline polyester resin may decrease, and the melting point may decrease. In addition, if the carbon number of the saturated aliphatic diol exceeds 12, it becomes difficult to obtain a practical material.

Examples of the saturated aliphatic diol include ethylene glycol, 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, 1,14-eicosanedecanediol, etc. Among these, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred in terms of high crystallinity of the crystalline polyester resin and excellent sharp melt properties.
Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, etc. These may be used alone or in combination of two or more kinds.

(Polycarboxylic Acid)
The polyvalent carboxylic acid is not particularly limited and may be appropriately selected depending on the purpose. Examples of the polyvalent carboxylic acid include divalent carboxylic acids and trivalent or higher carboxylic acids.

Examples of the divalent carboxylic acid include saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconic acid. Further examples include anhydrides of these acids and lower (1 to 3 carbon atoms) alkyl esters of these acids.

Examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, and the like, as well as anhydrides and lower (carbon number 1 to 3) alkyl esters thereof.
These may be used alone or in combination of two or more.

The crystalline polyester resin is preferably composed of a linear saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and a linear saturated aliphatic diol having 2 to 12 carbon atoms. This results in high crystallinity and excellent sharp melting properties, allowing for excellent low-temperature fixability. In addition, methods for controlling the crystallinity and softening point of crystalline polyester resins include designing and using nonlinear polyesters in which a trivalent or higher polyhydric alcohol such as glycerin is added to the alcohol component during polyester synthesis, or a trivalent or higher polyvalent carboxylic acid such as trimellitic anhydride is added to the acid component and polycondensed.

The molecular structure of the crystalline polyester resin of the present invention can be confirmed by NMR measurement of a solution or solid, as well as X-ray diffraction, GC/MS, LC/MS, IR measurement, etc., but a simple example can be one having an absorption due to olefin δCH (out-of-plane bending vibration) at 965±10 cm ^-1 or 990±10 cm ^-1 in an infrared absorption spectrum.

Regarding the molecular weight, from the viewpoint that a low molecular weight with a sharp molecular weight distribution is excellent in low temperature fixability, and that a large amount of low molecular weight components deteriorates heat resistance storage stability, extensive investigations have revealed that, in the molecular weight distribution by GPC of the o-dichlorobenzene soluble portion, the peak position in a molecular weight distribution diagram with the horizontal axis being log(M) and the vertical axis being weight % is in the range of 3.5 to 4.0, the half width of the peak is 1.5 or less, the weight average molecular weight (Mw) is 3,000 to 30,000, the number average molecular weight (Mn) is 1,000 to 10,000, and Mw/Mn is 1 to 10.
More preferably, the weight average molecular weight (Mw) is 5,000 to 15,000, the number average molecular weight (Mn) is 2,000 to 10,000, and the Mw/Mn is 1 to 5.

From the viewpoint of affinity between paper and resin, the acid value of the crystalline polyester resin is preferably 5 mgKOH/g or more to achieve the desired low-temperature fixability, and more preferably 7 mgKOH/g or more to produce fine particles by phase inversion emulsification, while 45 mgKOH/g or less is preferable to improve hot offset properties. In addition, the hydroxyl value of the crystalline polymer is preferably 0 mgKOH to 50 mgKOH/g, more preferably 5 mgKOH/g to 50 mgKOH/g, to achieve the desired low-temperature fixability and good charging properties.

<Method of producing resin particles>
<Oil phase preparation process>
In the method for producing resin particles of the present invention, first, the above-mentioned resin, colorant, prepoly, etc. are dissolved or dispersed in an organic solvent to prepare an oil phase. The oil phase can be prepared by gradually adding the resin, colorant, etc. to an organic solvent while stirring, and dissolving or dispersing them. For dispersion, a known dispersing machine can be used, for example, a dispersing machine such as a bead mill or a disk mill.
The materials used in the oil phase preparation step will be described.

(Organic solvent)
The organic solvent is preferably volatile with a boiling point of less than 100° C., from the viewpoint of facilitating subsequent removal of the organic solvent. As such an organic solvent, for example, toluene, xylene, benzene, carbon tetrachloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloroethylidene, methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, etc. can be used alone or in combination of two or more. When the resin to be dissolved or dispersed in the organic solvent is a resin having a polyester skeleton, it is preferable to use an ester-based solvent such as methyl acetate, ethyl acetate, or butyl acetate, or a ketone-based solvent such as methyl ethyl ketone or methyl isobutyl ketone, in order to obtain a high solubility, and among these, methyl acetate, ethyl acetate, and methyl ethyl ketone, which have high solvent removability, are particularly preferable.

(Release Agent)
The release agent is not particularly limited and can be appropriately selected depending on the purpose, but a release agent having a low melting point of 50° C. to 120° C. is preferable. The release agent having a low melting point effectively acts as a release agent between the fixing roller and the toner interface by being dispersed in the resin, and as a result, the hot offset property is good even in an oil-less system (no release agent such as oil is applied to the fixing roller).

Suitable examples of the release agent include waxes. Examples of the waxes include natural waxes such as vegetable waxes such as carnauba wax, cotton wax, wood wax, and rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cerusine; and petroleum waxes such as paraffin, microcrystalline, and petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax; synthetic waxes such as esters, ketones, and ethers; and the like. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride, and chlorinated hydrocarbons; homopolymers or copolymers of polyacrylates such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate, which are low molecular weight crystalline polymer resins (for example, copolymers of n-stearyl acrylate and ethyl methacrylate); and crystalline polymers having long alkyl groups on the side chains. These may be used alone or in combination of two or more.

The melting point of the wax is not particularly limited and can be appropriately selected according to the purpose, but is preferably 50°C to 120°C, and more preferably 60°C to 90°C. If the melting point is 50°C or higher, the wax can be prevented from adversely affecting the heat-resistant storage stability, and if it is 120°C or lower, the problem of cold offset occurring during fixing at low temperatures can be effectively prevented. The melt viscosity of the wax is preferably 5 cps to 1,000 cps, and more preferably 10 cps to 100 cps, as measured at a temperature 20°C higher than the melting point of the wax. If the melt viscosity is 5 cps or higher, the release property can be prevented from decreasing, and if it is 1,000 cps or lower, the effects of hot offset resistance and low-temperature fixing property can be fully exhibited. The content of the wax in the toner is not particularly limited and can be appropriately selected according to the purpose, but is preferably 0% by mass to 40% by mass, and more preferably 3% by mass to 30% by mass. If the content is 40% by mass or less, deterioration of the toner's fluidity can be prevented.

(Coloring Agent)
As the colorant of the present invention, known dyes and pigments can be used, for example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Balkan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazan yellow BGL, isoindolinone yellow, red iron oxide, red lead, lead Vermilion, Cadmium Red, Cadmium Mercury Red, Antimony Vermilion, Permanent Red 4R, Para Red, Phaysee Red, Parachlor Orthonitroaniline Red, Lithol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Lithol Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidinema Rune, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalocyanine Blue Examples of the pigments that can be used include blue, fast sky blue, indanthrene blue (RS, BC), indigo, ultramarine blue, Prussian blue, anthraquinone blue, fast violet B, methyl violet lake, cobalt purple, manganese purple, dioxane violet, anthraquinone violet, chrome green, zinc green, chromium oxide, pyridian, emerald green, pigment green B, naphthol green B, green gold, acid green lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc oxide, lithopone, and mixtures thereof.

(Charge control agent)
A charge control agent and the like may be added to the oil phase.
Any of the known charge control agents can be used, such as nigrosine dyes, triphenylmethane dyes, chromium-containing metal complex dyes, molybdic acid chelate pigments, rhodamine dyes, alkoxy amines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, phosphorus simple substance or compounds, tungsten simple substance or compounds, fluorine-based activators, metal salicylic acid salts, and metal salts of salicylic acid derivatives.

Specifically, the nigrosine dye Bontron 03, the quaternary ammonium salt Bontron P-51, the metal-containing azo dye Bontron S-34, the oxynaphthoic acid metal complex E-82, the salicylic acid metal complex E-84, the phenol condensate E-89 (all manufactured by Orient Chemical Industry Co., Ltd.), the quaternary ammonium salt molybdenum complexes TP-302 and TP-415 (all manufactured by Hodogaya Chemical Co., Ltd.), the quaternary ammonium salt Copy Charge PSY VP2038, the triphenylmethane derivative Copy Blue PR, the quaternary ammonium salt Copy Charge NEG VP2036, and Copy Charge NX. Examples include VP434 (all manufactured by Hoechst), LRA-901, the boron complex LR-147 (manufactured by Nippon Carlit), copper phthalocyanine, perylene, quinacridone, azo pigments, and other polymeric compounds with functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.

The charge control agent may be used in an amount that allows it to exhibit its performance without interfering with fixation properties, etc. It is recommended that the toner contain 0.5 to 5% by weight, preferably 0.8 to 3% by weight.

<Phase inversion emulsification process>
Next, the oil phase obtained in the oil phase preparation step is microparticulated.
In this embodiment, the oil phase is neutralized with a neutralizing agent, and then an aqueous phase is added thereto, thereby obtaining a microparticle dispersion (microparticle dispersion) by phase inversion emulsification, in which a water-in-oil dispersion (water-in-oil emulsion) is inverted into an oil-in-water dispersion (oil-in-water emulsion).
The neutralizing agent may be either a basic inorganic compound or a basic organic compound. Examples of the basic inorganic compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, sodium carbonate, sodium hydrogen carbonate, potassium carbonate, potassium hydrogen carbonate, and ammonia. Examples of the basic organic compound include N,N-dimethylethanolamine, N,N-diethylethanolamine, triethanolamine, tripropanolamine, tributanolamine, triethylamine, n-propylamine, n-butylamine, isopropylamine, monomethanolamine, morpholine, methoxypropylamine, pyridine, vinylpyridine, and isophoronediamine.

Neutralization is performed by uniformly mixing and dispersing using a conventional stirrer or dispersing device. There are no particular limitations on the dispersing device, and examples include ultrasonic dispersers, bead mills, ball mills, roll mills, homomixers, ultra mixers, dispersing mixers, penetrating type high-pressure dispersing devices, collision type high-pressure dispersing devices, multi-hole type high-pressure dispersing devices, ultra-high-pressure homogenizers, and ultrasonic homogenizers. Conventional stirrers and dispersing devices may be used in combination.

The aqueous phase is ion-exchanged water or ion-exchanged water containing an organic solvent. Examples of organic solvents include ester-based solvents such as methyl acetate, ethyl acetate, and butyl acetate, and ketone-based solvents such as methyl ethyl ketone and methyl isobutyl ketone. From the viewpoint of granulation, it is preferable that the concentration of the organic solvent is equal to or lower than the saturation concentration in the ion-exchanged water.

A surfactant may be added to the aqueous phase to emulsify the oil phase well. There are no particular limitations on the surfactant, and it can be selected appropriately depending on the purpose. For example, anionic surfactants, cationic surfactants, nonionic surfactants, amphoteric surfactants, etc. can be used.

The anionic surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the anionic surfactant include alkyl sulfates, alkyl sulfonates, alkylbenzene sulfonates, and α-olefin sulfonates.

During emulsification, the mixture is mixed and dispersed uniformly using a conventional stirrer or dispersing device. There are no particular limitations on the dispersing device, and examples include ultrasonic dispersers, bead mills, ball mills, roll mills, homomixers, ultra mixers, dispersing mixers, penetrating type high-pressure dispersing devices, collision type high-pressure dispersing devices, multi-hole type high-pressure dispersing devices, ultra-high-pressure homogenizers, and ultrasonic homogenizers. Conventional stirrers and dispersing devices may be used in combination.

<Solvent removal process>
The organic solvent can be removed from the resulting fine particle dispersion by the following four methods.
(1) A method in which the temperature of the entire system is gradually increased while stirring, and the organic solvent in the droplets is completely removed by evaporation. (2) A method in which the obtained microparticle dispersion is sprayed into a dry atmosphere while stirring, and the organic solvent in the droplets is completely removed. (3) A method in which the microparticle dispersion is reduced in pressure while stirring, and the organic solvent is removed by evaporation. (4) A method in which the organic solvent is removed by spraying a gas onto the microparticle dispersion while stirring.
The above means (2), (3), and (4) can be used in combination with the above means (1).

The drying atmosphere into which the fine particle dispersion is sprayed generally includes air, nitrogen, carbon dioxide, heated combustion gas, etc., and among these, various air flows heated to a temperature equal to or higher than the boiling point of the highest boiling point solvent used.
The desired quality can be obtained by short-term processing using a spray dryer, belt dryer, rotary kiln, etc. The gas used for spraying can be air, nitrogen, carbon dioxide, or heated combustion gas.
By the above method, a fine particle dispersion can be obtained.

<Aggregation step>
Next, the obtained microparticle dispersion is agitated to aggregate until the desired particle size is reached. To aggregate, existing methods such as adding an aggregating agent or adjusting the pH can be used. When adding an aggregating agent, it may be added as is, but it is preferable to add the aggregating agent in an aqueous solution, since this can avoid localized high concentration. It is also preferable to gradually add the aggregating salt while monitoring the particle size.

The temperature of the dispersion liquid during aggregation is preferably close to the Tg of the resin used. If the liquid temperature is too low, aggregation does not proceed very well, resulting in poor efficiency. If the liquid temperature is too high, the aggregation rate increases, resulting in the generation of coarse particles and a deterioration in particle size distribution.

When the target particle size is reached, the aggregation is stopped by adding a salt or a chelating agent having a low ionic valence, adjusting the pH, lowering the temperature of the dispersion, adding a large amount of an aqueous medium to dilute the concentration, or the like.
By the above method, a dispersion of aggregated particles can be obtained.

In the aggregation process, wax may be added as a release agent, or a crystalline resin may be added for low-temperature fixability. In that case, a dispersion liquid in which wax is dispersed in an aqueous medium or a dispersion liquid of a crystalline resin is prepared, and mixed with the fine particle dispersion liquid before aggregation to obtain aggregated particles in which the wax and crystalline resin are uniformly dispersed.

(Flocculant)
As the flocculant, a known flocculant can be used, for example, a metal salt of a monovalent metal such as sodium or potassium, a metal salt of a divalent metal such as calcium or magnesium, or a metal salt of a trivalent metal such as iron or aluminum.

<Shelling process>
The shell forming step is a step of forming a shell layer on the aggregated particles obtained in the aggregation step.
The method for forming the shell layer is not particularly limited and can be appropriately selected depending on the purpose. For example, there can be mentioned a method in which aggregated particles having a desired particle size are produced in the aggregation step, the amorphous resin is added, and the aggregation step and a fusion step described later are repeated to form a shell layer.

<Fusing process>
Next, the obtained aggregated particles having the shell layer formed thereon are fused by heat treatment to reduce unevenness and obtain resin particles. Fusion can be performed by heating the dispersion of the aggregated particles while stirring. The temperature of the liquid is preferably near a temperature exceeding the Tg of the resin used.

<Cleaning and drying process>
The particle dispersion obtained by the above method contains sub-materials such as coagulating salts in addition to the resin particles, so washing is carried out in order to extract only the resin particles from the dispersion.
Methods for washing the resin particles include centrifugation, reduced pressure filtration, and filter press, but are not particularly limited in the present invention.

Either method will produce a cake of resin particles, but if the resin particles cannot be washed sufficiently in one operation, the cake obtained may be dispersed again in an aqueous solvent to produce a slurry, and the process of extracting the resin particles using one of the above methods may be repeated. If washing is performed by vacuum filtration or filter press, the aqueous solvent may be passed through the cake to wash away the secondary materials that are held by the colored resin particles.

The aqueous solvent used for this cleaning is water or a mixed solvent of water and an alcohol such as methanol or ethanol, but considering the cost and the environmental burden caused by wastewater treatment, it is preferable to use water.

Since the washed resin particles contain a large amount of the aqueous medium, the aqueous medium can be removed by drying to obtain only the resin particles.
As the drying method, a dryer such as a spray dryer, a vacuum freeze dryer, a reduced pressure dryer, a stationary shelf dryer, a movable shelf dryer, a fluidized bed dryer, a rotary dryer, or an agitator dryer can be used. It is preferable to dry the dried resin particles until the moisture content is finally less than 1%. In addition, if the resin particles after drying are in a soft agglomeration state and cause inconvenience in use, the soft agglomeration may be broken down using a device such as a jet mill, a Henschel mixer, a super mixer, a coffee mill, an Auster blender, or a food processor.

<Annealing step>
When a crystalline resin is added, the non-crystalline resin and the crystalline resin are phase-separated by performing an annealing treatment after drying, and the fixing property is improved. Specifically, the toner is stored at a temperature near the Tg for 10 hours or more.

<External Addition Process>
When the resin particles obtained in the present invention are used as a toner, inorganic fine particles, polymeric fine particles, cleaning aids, etc. may be added or mixed to the toner particles in order to impart fluidity, chargeability, cleaning properties, etc.
Specific mixing means include a method of applying an impact force to the mixture with a blade rotating at high speed, a method of throwing the mixture into a high-speed air current, accelerating it, and causing the particles to collide with each other or the composite particles with an appropriate collision plate, etc. Examples of equipment include an Ang Mill (manufactured by Hosokawa Micron Corporation), a modified I-type Mill (manufactured by Japan Pneumatic Co., Ltd.) with reduced grinding air pressure, a Hybridization System (manufactured by Nara Machinery Works, Ltd.), a Cryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), an automatic mortar, etc.

(External additives)
The primary particle size of the inorganic fine particles is preferably from 5 nm to 2 μm, and more preferably from 5 nm to 500 nm.
The specific surface area as measured by the BET method is preferably 20 m ² /g or more and 500 m ² /g or less.
The proportion of the inorganic fine particles used is preferably 0.01% by mass or more and 5% by mass or less of the toner. Specific examples of the inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengalla, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.
Examples of polymeric fine particles include polymer particles made of polystyrene, methacrylate or acrylate copolymers obtained by soap-free emulsion polymerization, suspension polymerization, or dispersion polymerization, or polycondensation systems such as silicone, benzoguanamine, or nylon, or polymer particles made of thermosetting resins.

Such fluidizing agents can be surface-treated to increase their hydrophobicity, thereby preventing deterioration of flow characteristics and charging characteristics even under high humidity conditions.
Examples of preferred surface treatment agents include silane coupling agents, silylating agents, silane coupling agents having a fluoroalkyl group, organic titanate coupling agents, aluminum coupling agents, silicone oil, and modified silicone oil.
Examples of cleaning improvers for removing the developer remaining on the photoconductor or primary transfer medium after transfer include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, and polymer fine particles produced by soap-free emulsion polymerization, such as polymethyl methacrylate fine particles and polystyrene fine particles.
The polymer particles preferably have a relatively narrow particle size distribution and a volume average particle size of 0.01 to 1 μm.

(Other methods for producing resin fine particles)
As a method for producing resin fine particles other than those described above, a mixture of amorphous polyester, crystalline polyester, a colorant, a release agent, etc. may be kneaded, and the kneaded mixture may be pulverized and classified to produce core particles for forming the core layer.
Thereafter, the core particles may be added to a liquid in which a shell layer forming material is dispersed or dissolved in a solvent such as water or an organic solvent, and the mixture is stirred to form a shell layer on the core layer.
Thereafter, if necessary, the <cleaning step>, <drying step>, and <annealing step> in the above-mentioned manufacturing method may be carried out.

Since the resin particles according to one embodiment have the above-mentioned properties, they can be effectively used as materials for image formation, such as toner, developer, toner set, toner storage unit, and image forming apparatus.
Other applications of the resin particles of the present invention include particles for powder coatings, spacer particles for liquid crystals, particles for cosmetic additives, particles for light diffusion, antiblocking agents and lubrication improvers for plastic films, etc.

<Toner>
The toner according to an embodiment includes the resin particles according to an embodiment, and may be made of the resin particles according to an embodiment.
By using the resin particles according to one embodiment in a toner, the environmental impact is reduced, and even if a plant-derived resin is used, it is possible to provide an image having excellent low-temperature fixing property, storage stability, and charging property, and having excellent image quality.
Furthermore, the toner according to an embodiment can be used as either a positively charged toner or a negatively charged toner.

<Developer>
The developer according to an embodiment includes the toner according to an embodiment, and may include other components, such as a carrier, which are appropriately selected as necessary. This allows the developer to have excellent transferability, chargeability, and the like, and to stably form high-quality images.
The developer may be a one-component developer or a two-component developer. However, when used in high-speed printers that correspond to the recent improvements in information processing speed, a two-component developer is preferable from the viewpoint of improving the developer life.

When the toner according to one embodiment is used in a one-component developer, even if the toner is balanced, there is little variation in the particle size of the toner, and toner filming on the developing roller and toner adhesion to components such as blades that thin the toner layer are reduced, resulting in high-quality images being obtained in the developing device.

When the developer according to the embodiment is used as a two-component developer, it can be mixed with a carrier and used as a developer. When the toner according to the embodiment is used as a two-component developer, the particle size of the toner is small even if the toner is balanced over a long period of time, and good and stable developability and images can be obtained even when the toner is stirred for a long period of time in a developing device.
The content of the carrier in the two-component developer can be appropriately selected depending on the purpose, but is preferably 90 parts by weight to 98 parts by weight, and more preferably 93 parts by weight to 97 parts by weight, based on 100 parts by weight of the two-component developer.

The developer according to one embodiment can be suitably used for image formation using various known electrophotographic methods, such as magnetic one-component development, non-magnetic one-component development, and two-component development.

[Career]
The carrier is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the carrier has a core material and a resin layer (coating layer) that coats the core material.

(Core material)
The material of the core material is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include manganese-strontium-based materials of 50 emu/g to 90 emu/g and manganese-magnesium-based materials of 50 emu/g to 90 emu/g. In order to ensure image density, it is preferable to use high magnetization materials such as iron powder of 100 emu/g or more and magnetite of 75 emu/g to 120 emu/g. In addition, it is preferable to use low magnetization materials such as copper-zinc-based materials of 30 emu/g to 80 emu/g, since this can reduce the impact of the developer in a standing state on the photoconductor and is advantageous for improving image quality. These materials may be used alone or in combination of two or more types.

The volume average particle diameter of the core material is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 10 μm or more and 150 μm or less, and more preferably 40 μm or more and 100 μm or less. If the volume average particle diameter is 10 μm or more, the problem that the amount of fine powder increases in the carrier, the magnetization per particle decreases, and the carrier may scatter can be effectively prevented. On the other hand, if it is 150 μm or less, the specific surface area decreases, the toner may scatter, and in full color with many solid areas, the problem that the reproduction of the solid areas may be poor can be effectively prevented.

(Resin Layer)
The resin layer can contain a resin and other components as necessary. The resin used in the resin layer can be a known material that can impart the necessary electrostatic property. Specifically, it is preferable to use a silicone resin, an acrylic resin, or a combination of these. In addition, the composition for forming the resin layer preferably contains a silane coupling agent.
The average thickness of the resin layer is preferably 0.05 μm or more and 0.50 μm or less.

<Measurement method>
<Volume average particle size>
The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 3 μm to 7 μm. The ratio of the volume average particle diameter to the number average particle diameter is preferably 1.2 or less. It is also preferable that the resin particles contain 1% by number to 10% by number of components having a volume average particle diameter of 2 μm or less.

<Measurement of volume average particle diameter (Dv) and number average particle diameter (Dn)>
The volume average particle diameter (Dv) and number average particle diameter (Dn) of the resin particles were measured using a particle size measuring device (Multisizer III, manufactured by Beckman Coulter) with an aperture diameter of 100 μm, and analyzed using analysis software (Beckman Coulter Multisizer 3 Version 3.51) under the following conditions. 0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate NEOGEN SC-A; Daiichi Kogyo Seiyaku) was added to a 100 ml glass beaker, 0.5 g of each toner was added, and the mixture was stirred with a micro spatula, and then 80 ml of ion-exchanged water was added. The obtained dispersion was dispersed for 10 minutes using an ultrasonic disperser (W-113MK-II, manufactured by Honda Electronics Co., Ltd.). The dispersion was measured using the Multisizer III and Isoton III (manufactured by Beckman Coulter) as a measurement solution. For the measurement, the toner sample dispersion is dropped so that the concentration indicated by the device becomes 8±2%.

<Average circularity>
In the tonerization of the resin particles, the average circularity is preferably a specific shape, and the average circularity is preferably 0.940 or more and less than 0.980. A toner having an average circularity of less than 0.940 and an indefinite shape far removed from a sphere cannot obtain a high-quality image without satisfactory transferability or dust. If the average circularity is 0.980 or more, in a system using blade cleaning, cleaning failure occurs on the photoreceptor and transfer belt, causing stains on the image.

The average circularity of the resin particles was measured using a flow type particle image analyzer ("FPIA-3000" manufactured by Sysmex Corporation) and analysis software (FPIA-3000 FLOW PARTICLE IMAGE ANALYZER version 00-11) under the following conditions.
0.1 ml to 0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate NEOGEN SC-A; Daiichi Kogyo Seiyaku) was added to a 100 ml glass beaker, 0.1 g to 0.5 g of each toner was added and stirred with a micro spatula, and then 80 ml of ion-exchanged water was added. The resulting dispersion was subjected to a dispersion treatment for 3 minutes using an ultrasonic disperser (manufactured by Honda Electronics Co., Ltd.). The shape and distribution of the resin particles in the dispersion were measured using the FPIA-3000 until a concentration of 5,000 particles/μl to 15,000 particles/μl was obtained.

<Method of Analyzing Resin Particle Constituents>
The plant-derived alcohol monomer may be calculated by any method. For example, the plant-derived alcohol monomer may be qualitatively analyzed by separating the resin particles by gel permeation chromatography (GPC) or the like and then subjecting each separated component to the analytical method described below.
In addition, gas chromatography mass spectrometry at 300° C. using a reaction reagent (10% tetramethyl ammonium hydroxide (TMAH)/methanol solution) can be used to estimate the main components from soft decomposition due to methylation of the ester bonds in the resin structure.

<Method of measuring radioisotope ^14C concentration>
The concentration of the radioactive carbon isotope ^14C in the resin particles was measured by radioactive carbon dating. The resin particles were burned, and the _CO2 (carbon dioxide) was reduced to obtain C (graphite). The ^14C concentration of the C (graphite) was measured using an AMS (Accelerator Mass Spectroscopy, manufactured by Beta Analytic).

<Confirmation of core-shell structure>
[TEM Observation and Measurement]
The prepared resin particles are embedded in an epoxy resin and hardened. Ultrathin sections (approximately 100 nm thick) of the resin particles are prepared using an ultramicrotome (ULTRACUT UCT manufactured by Leica, using a diamond knife).
The sample is exposed to ruthenium tetroxide, osmium tetroxide, or another staining agent, and the crystalline polyester resin phase is stained to distinguish it from the other parts. The exposure time is adjusted appropriately depending on the contrast during observation. The crystalline polyester resin phase is often observed as a lamellar structure. The sample is then observed with a transmission electron microscope (JEM-2100, JEOL) at an accelerating voltage of 100 kV. Depending on the composition of the crystalline polyester resin and the non-crystalline polyester resin, they may be distinguishable without staining, in which case they are evaluated without staining. It is also possible to impart compositional contrast by other means such as selective etching, and after such pretreatment, the crystalline polyester resin part may be evaluated by observing with a transmission microscope.

(Toner storage unit)
The toner storage unit in the present invention refers to a unit having a function of storing toner and storing the toner. Examples of the toner storage unit include a toner storage container, a developing unit, and a process cartridge.
The toner storage container refers to a container that stores toner.
The developing device has a means for containing toner and developing the toner.
The process cartridge is a cartridge which integrates at least an image carrier and a developing means, contains toner, and is detachably mountable to an image forming apparatus. The process cartridge may further include at least one selected from a charging means, an exposure means, and a cleaning means.

(Image forming apparatus)
Next, one embodiment of the method for forming an image by the image forming apparatus of the present invention will be described.
The following description will be given with reference to Fig. 1. Although a printer is shown as an example of the image forming apparatus of the present embodiment, the image forming apparatus is not particularly limited as long as it is capable of forming an image using toner, such as a copier, a facsimile, or a multifunction machine.
The image forming apparatus includes a paper feed section 210 , a conveying section 220 , an image creating section 230 , a transfer section 240 , and a fixing unit 250 .
The paper feed section 210 includes a paper feed cassette 211 in which the paper P to be fed is stacked, and a paper feed roller 212 that feeds the paper P stacked in the paper feed cassette 211 one sheet at a time.

The transport section 220 includes a roller 221 that transports the paper P fed by the paper feed roller 212 toward the transfer section 240, a pair of timing rollers 222 that hold the leading edge of the paper P transported by the roller 221 and wait to send the paper to the transfer section 240 at a predetermined timing, and a paper discharge roller 223 that discharges the paper P with the fixed color toner image onto the paper discharge tray 224.

The image creating section 230 includes, spaced at a predetermined interval from left to right in the figure, an image forming unit Y that forms an image using a developer containing yellow toner, an image forming unit C that uses a developer containing cyan toner, an image forming unit M that uses a developer containing magenta toner, an image forming unit K that uses a developer containing black toner, and an exposure device 233.
Incidentally, when referring to any one of the image forming units (Y, C, M, K), it is referred to as an image forming unit.

The developer includes toner and carrier.
K) are substantially identical in mechanical construction, except for the developer used.

The transfer unit 240 includes a drive roller 241, a driven roller 242, an intermediate transfer belt 243 that can rotate counterclockwise in the figure as the drive roller 241 is driven, primary transfer rollers (244Y, 244C, 244M, 244K) that are arranged opposite the photosensitive drum 231 with the intermediate transfer belt 243 in between, and secondary opposing roller 245 and secondary transfer roller 246 that are arranged opposite each other with the intermediate transfer belt 243 in between at the position where the toner image is transferred to the paper.

The fixing unit 250 has a heater installed inside and is equipped with a fixing belt 251 that heats the paper P, and a pressure roller 252 that forms a nip by applying pressure to the fixing belt 251 while rotating. This applies heat and pressure to the color toner image on the paper P, fixing the color toner image. The paper P with the fixed color toner image is discharged to the paper discharge tray 224 by the paper discharge rollers 223, completing the image formation process.

(Process cartridge)
The process cartridge according to the present invention is molded so as to be detachably mountable to various image forming apparatuses, and has at least an electrostatic latent image carrier for carrying an electrostatic latent image, and a developing means for developing the electrostatic latent image carried on the electrostatic latent image carrier with the developer of the present invention to form a toner image. The process cartridge of the present invention may further have other means as necessary.

The developing means has at least a developer container that contains the developer of the present invention, and a developer carrier that carries and transports the developer contained in the developer container. The developing means may further have a regulating member or the like for regulating the thickness of the developer carried.

Figure 2 shows an example of a process cartridge according to the present invention. The process cartridge 110 has a photosensitive drum 10, a corona charger 58, a developing device 40, a transfer roller 80, and a cleaning device 90.

Below, examples of the present invention are explained, but the present invention is not limited to these examples. In addition, in the following description, unless otherwise specified, "parts" means "parts by mass" and "%" means "% by mass".

[Production Example of Amorphous Polyester Resin A-1]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 218 parts of plant-derived propylene glycol (manufactured by Dupont), 205 parts of propylene oxide 2 mol adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 85 parts of succinic acid (manufactured by BASF), 417 parts of terephthalic acid, and 75 parts of sodium 5-sulfoisophthalate were charged, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that it was 1 mol% relative to the total resin component, and reacted at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-1].

[Production Example of Amorphous Polyester Resin A-2]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 223 parts of plant-derived propylene glycol (manufactured by Dupont), 209 parts of propylene oxide 2 mol adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 112 parts of succinic acid (manufactured by BASF), 425 parts of terephthalic acid, and 31 parts of sodium 5-sulfoisophthalate were charged, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230 ° C. for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that it was 1 mol % relative to the total resin component, and reacted at 180 ° C., normal pressure, and 3 hours to obtain [amorphous polyester resin A-2].

[Production Example of Amorphous Polyester Resin A-3]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 211 parts of plant-derived propylene glycol (manufactured by Dupont), 199 parts of propylene oxide 2 mol adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 41 parts of succinic acid (manufactured by BASF), 403 parts of terephthalic acid, and 146 parts of sodium 5-sulfoisophthalate were charged, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that it was 1 mol% relative to the total resin component, and reacted at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-3].

[Production Example of Amorphous Polyester Resin A-4]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 51 parts of plant-derived neopentyl glycol (manufactured by Perstorp), 558 parts of 2 mol propylene oxide adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 58 parts of succinic acid (manufactured by BASF), 283 parts of terephthalic acid, and 51 parts of sodium 5-sulfoisophthalate were charged, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that it was 1 mol% relative to the total resin component, and reacted at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-4].

[Production Example of Amorphous Polyester Resin A-5]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 25 parts of plant-derived neopentyl glycol (manufactured by Perstorp), 611 parts of propylene oxide 2 mol adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 78 parts of succinic acid (manufactured by BASF), 275 parts of terephthalic acid, and 10 parts of sodium 5-sulfoisophthalate were charged, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that the amount was 1 mol% relative to the total resin component, and the reaction was carried out at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-5].

[Production Example of Amorphous Polyester Resin A-6]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 19 parts of plant-derived neopentyl glycol (manufactured by Perstorp), 591 parts of 2 mol propylene oxide adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 16 parts of succinic acid (manufactured by BASF), 261 parts of terephthalic acid, and 113 parts of sodium 5-sulfoisophthalate were charged and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that it was 1 mol% relative to the total resin component, and reacted at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-6].

[Production Example of Amorphous Polyester Resin A-7]
A four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple was charged with 67 parts of propylene glycol, 503 parts of a 2 mol adduct of bisphenol A with propylene oxide (manufactured by Sanyo Chemical Industries), 42 parts of ethylene glycol, 277 parts of succinic acid (manufactured by BASF), 49 parts of terephthalic acid, and 62 parts of sodium 5-sulfoisophthalate, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and then reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that the amount was 1 mol% relative to the total resin component, and the mixture was reacted at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-7].

[Production Example of Amorphous Polyester Resin A-8]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, 25 parts of plant-derived neopentyl glycol (manufactured by Perstorp), 614 parts of propylene oxide 2 mol adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 84 parts of succinic acid (manufactured by BASF), 277 parts of terephthalic acid, and 113 parts of sodium 5-sulfoisophthalate were charged, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel so that the amount was 1 mol% relative to the total resin component, and the reaction was carried out at 180°C, normal pressure, and for 3 hours to obtain [amorphous polyester resin A-8].

[Production Example of Amorphous Polyester Resin A-9]
A four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple was charged with 69 parts of propylene glycol, 517 parts of a 2 mol propylene oxide adduct of bisphenol A (manufactured by Sanyo Chemical Industries), 44 parts of ethylene glycol, 320 parts of succinic acid (manufactured by BASF), and 50 parts of terephthalic acid, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) as a condensation catalyst at normal pressure and 230 ° C. for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. Then, trimellitic anhydride was added to the reaction vessel so that the amount was 1 mol% relative to the total resin component, and reacted at 180 ° C., normal pressure, and for 3 hours to obtain [amorphous polyester resin A-9].

The resin compositions and physical properties of the thus obtained [Amorphous Polyester Resin A-1] to [Amorphous Polyester Resin A-9] are shown in Table 1 below.
In addition, "↑" in Table 1 indicates that the contents of the column in which the arrow is written are the same as those written in the column above.

[Synthesis of amorphous polyester resin B-1]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, plant-derived propylene glycol (manufactured by DuPont), bisphenol A propylene oxide 2-mol adduct, terephthalic acid, and succinic acid were added in a molar ratio of 60/40 for propylene glycol and bisphenol A ethylene oxide 2-mol adduct (propylene glycol/bisphenol A ethylene oxide 2-mol adduct), and the molar ratio of 60/40 for terephthalic acid and succinic acid was terephthalic acid/succinic acid. The mixture was charged with 100 ppm of ethyl acetate and succinic acid (86/14) and the molar ratio of hydroxyl groups to carboxyl groups, OH/COOH, was 1.3, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin components) at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. Then, trimellitic anhydride was added to the reaction vessel in an amount of 1 mol% relative to the total resin components, and reacted at 180°C, normal pressure, for 3 hours to obtain [Amorphous Polyester Resin B-1].

[Synthesis of amorphous polyester resin B-2]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, plant-derived neopentyl glycol (manufactured by Perstorp), bisphenol A propylene oxide 2-mol adduct, terephthalic acid, and succinic acid were added in a molar ratio of 40/60 (neopentyl glycol/bisphenol A ethylene oxide 2-mol adduct) and 40/60 (terephthalic acid/succinic acid). The mixture was charged with a hydroxyl/succinic acid ratio of 86/14 and a molar ratio of OH/COOH of 1.3 between the hydroxyl groups and the carboxyl groups, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin components) at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel in an amount of 1 mol% relative to the total resin components, and reacted at 180°C, normal pressure, for 3 hours to obtain [Amorphous Polyester Resin B-2].

[Synthesis of amorphous polyester resin B-3]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, plant-derived neopentyl glycol (manufactured by Perstorp), bisphenol A propylene oxide 2-mol adduct, terephthalic acid, and succinic acid were added in a molar ratio of 90/10 (neopentyl glycol/bisphenol A ethylene oxide 2-mol adduct) and 90/10 (terephthalic acid/succinic acid). The mixture was charged with a hydroxyl/succinic acid ratio of 86/14 and a molar ratio of OH/COOH of 1.3 between the hydroxyl groups and the carboxyl groups, and reacted with titanium tetraisopropoxide (500 ppm relative to the resin components) at normal pressure and 230°C for 8 hours, and further reacted at a reduced pressure of 10 mmHg to 15 mmHg for 4 hours. After that, trimellitic anhydride was added to the reaction vessel in an amount of 1 mol% relative to the total resin components, and reacted at 180°C, normal pressure, for 3 hours to obtain [Amorphous Polyester Resin B-3].

[Synthesis of amorphous polyester resin B-4]
In a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, bisphenol A ethylene oxide 2 mole adduct, bisphenol A propylene oxide 2 mole adduct, terephthalic acid, and adipic acid were added to obtain a mixture of bisphenol A propylene oxide 2 mole adduct and bisphenol A ethylene oxide 2 mole adduct in a molar ratio (bisphenol A propylene oxide 2 mole adduct/bisphenol A ethylene oxide 2 mole adduct) of 60/40, and terephthalic acid and adipic acid. The mixture was charged with terephthalic acid and adipic acid in a molar ratio (terephthalic acid/adipic acid) of 97/3, and the molar ratio of hydroxyl groups to carboxyl groups, OH/COOH, was 1.3. The mixture was reacted with titanium tetraisopropoxide (500 ppm relative to the resin component) at normal pressure and 230°C for 8 hours, and then reacted for 4 hours at a reduced pressure of 10 mmHg to 15 mmHg. After that, trimellitic anhydride was added to the reaction vessel in an amount of 1 mol% relative to the total resin component, and the mixture was reacted at 180°C, normal pressure, and for 3 hours to obtain [Amorphous Polyester Resin B-4].

[Preparation of Crystalline Polyester Resin Dispersion C-1a]
(Synthesis of crystalline polyester resin C-1)
1,6-hexanediol and sebacic acid were charged into a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple so that the ratio of OH groups to COOH groups (OH/COOH) was 1.1. The mixture was reacted while discharging water together with 500 ppm of titanium tetraisopropoxide relative to the mass of the charged raw materials, and finally heated to 235°C and reacted for 1 hour. Then, the mixture was reacted for 6 hours under a reduced pressure of 10 mmHg or less. Then, the temperature was set to 185°C, and trimellitic anhydride was added so that the molar ratio with respect to the COOH groups was 0.053, and the mixture was reacted for 2 hours with stirring to obtain [Crystalline polyester resin C-1].
Into a four-neck flask, 55 parts of [Crystalline polyester resin C-1], 35 parts of methyl ethyl ketone, and 10 parts of 2-propyl alcohol were added, and the mixture was stirred while being heated at the melting point of the [Crystalline polyester resin C-1] to dissolve the crystalline polyester resin.

(Preparation of crystalline polyester resin dispersion C-1a)
A vessel equipped with a stirring rod and a thermometer was charged with 45 parts of [Crystalline polyester resin C-1] and 450 parts of ethyl acetate, and the temperature was raised to 80°C with stirring. The temperature was maintained at 80°C for 5 hours, and then the mixture was cooled to 30°C in 1 hour. Dispersion was carried out using a bead mill (Ultraviscomill, manufactured by Imex) under conditions of a liquid delivery rate of 1 kg/hr, a disk peripheral speed of 6 m/sec, 80 volume % filling with zirconia beads of 0.5 mm diameter, and 3 passes to obtain [Crystalline polyester resin dispersion C-1a].

[Preparation of Wax Dispersion 1]
A container equipped with a stirring rod and a thermometer was charged with 50 parts of ester wax (NOF Corp., WE-11, synthetic wax of plant-derived monomers, melting point 67°C) as a release agent and 120 parts of ethyl acetate, and the mixture was heated to 80°C with stirring and maintained at 80°C for 5 hours. The mixture was then cooled to 30°C over 1 hour and dispersed using a bead mill (Ultraviscomill, Imex Corp.) under conditions of a liquid feed rate of 1 kg/hr, a disk peripheral speed of 6 m/sec, 80% by volume of 0.5 mm diameter zirconia beads, and 3 passes to obtain [WAX Dispersion W-1].

[Preparation of Masterbatch (MB)]
1,200 parts of water, 400 parts of carbon black (Printex 35 manufactured by Dexa) [DBP oil absorption = 42 mL/100 mg, pH = 9.5], and 600 parts of polyester resin 1 were mixed in a Henschel mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), and the mixture was kneaded using two rolls at 150°C for 30 minutes, rolled and cooled, and pulverized with a pulverizer to obtain [Masterbatch MB-1].

[Example 1]
<Preparation of core emulsion>
(Preparation of Oil Phase)
[Amorphous polyester resin B-1] 51.1 parts, [Crystalline polyester resin dispersion C-1a] 64 parts, [WAX dispersion W-1] 20 parts, [Master batch MB-1] 22.5 parts, and ethyl acetate 14.4 parts were placed in a container and mixed at 5,000 rpm for 60 minutes using a TK homomixer (manufactured by Primix Corporation) to obtain [Oil phase 1]. The solid content of the obtained oil phase was 50%. The above blending amounts indicate the blending amounts of solids in each raw material.

(Preparation of aqueous phase)
990 parts of water, 20 parts of sodium dodecyl sulfate, and 90 parts of ethyl acetate were mixed and stirred to obtain a milky white liquid, which was designated as [core aqueous phase 1].

(Preparation of Core Emulsion 1)
While stirring 703 parts of [oil phase 1] with a TK homomixer at a rotation speed of 8,000 rpm, 5.1 parts of 28% ammonia water was added so that the neutralization rate with respect to the acid value of [amorphous polyester resin B-1] was 100%, and after mixing for 10 minutes, 1,197 parts of [core aqueous phase 1] was gradually added dropwise, and the phase-inversion emulsion of [oil phase 1] was further desolvated with an evaporator to obtain [core emulsion 1].

<Preparation of Shell Emulsion 1>
(Preparation of shell resin solution)
200 parts of [amorphous polyester resin A-1] and 200 parts of methyl ethyl ketone were placed in a container and mixed with a TK homomixer (manufactured by Primix Corporation) at 5,000 rpm for 60 minutes to obtain [shell resin solution 1]. The solid content of the obtained oil phase was 50%.

(Preparation of aqueous phase)
468 parts of water and 132 parts of methyl ethyl ketone were mixed and stirred. This was designated as [Shell aqueous phase 1].

(Shell emulsion emulsification)
While stirring 400 parts of [Shell Resin Solution 1] with a TK homomixer at a rotation speed of 8,000 rpm, 5.9 parts of 28% ammonia water was added so that the neutralization rate with respect to the acid value of [Amorphous Polyester Resin A-1] was 100%, and after mixing for 10 minutes, 600 parts of [Shell Water Phase 1] was gradually added dropwise to phase-inversion emulsify [Shell Resin Solution 1]. Furthermore, the phase-inversion emulsion of [Shell Resin Solution 1] was desolvated with an evaporator to obtain [Shell Emulsion 1].

<Aggregation and shell formation process>
100 parts of [Core Emulsion 1] and 300 parts of ion-exchanged water were placed in a container and stirred for 1 minute.
Next, 6.3 parts of a 20% aqueous magnesium sulfate solution was added dropwise, and the mixture was stirred for an additional 5 minutes, and then heated to 55°C.
Thereafter, when the particle size reached 5.0 μm, 18.3 parts of [Shell Emulsion 1] diluted with 30 parts of water was added, and 15 parts of a 20% aqueous magnesium sulfate solution was added dropwise and stirred for another 10 minutes, after which the temperature was raised to 65° C. and stirring was continued for 30 minutes.

<Fusing and stopping process>
29 parts of sodium sulfate was added, and the mixture was heated to 70° C., and cooled when the desired circularity of 0.957 to 0.962 was reached, to obtain [toner dispersion 1].

<Cleaning, drying and annealing processes>
[Toner Dispersion Liquid 1] was stored at 45° C. for 10 hours and then filtered under reduced pressure to obtain a filter cake.
The filter cake was washed and dried as follows.
(1): 100 parts of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (at 12,000 rpm for 10 minutes), and then filtered.
(2): 900 parts of ion-exchanged water was added to the filter cake of (1), and the mixture was mixed with a TK homomixer while applying ultrasonic vibration (at a rotation speed of 12,000 rpm for 30 minutes), and then filtered under reduced pressure. This operation was repeated until the electrical conductivity of the reslurry liquid became 10 μC/cm or less, and then the mixture was filtered to obtain [Filter cake 1].
The [filter cake 1] was dried in a circulating air dryer at 45° C. for 48 hours and sieved through a 75 μm mesh to obtain [resin particles 1].
<External Addition Process>
2.5 parts of inorganic fine particles TS530 manufactured by Cabosil Corporation were added to 100 parts of the [Resin Particles 1], and mixed for 10 minutes at 40 m/s using a Henschel mixer to obtain [Toner 1].

[Example 2]
[Toner 2] was obtained in the same manner as in [Example 1] except that in (Preparation of shell resin solution) of [Example 1], [Amorphous polyester resin A-1] was changed to [Amorphous polyester resin A-2] to produce [Shell resin solution 2], and in (Shell emulsion emulsification), [Shell resin solution 1] was changed to [Shell resin solution 2] to produce [Shell emulsion 2].

[Example 3]
[Toner 3] was obtained in the same manner as in [Example 1] except that in (Preparation of shell resin solution) of [Example 1], [Amorphous polyester resin A-1] was changed to [Amorphous polyester resin A-3] to produce [Shell resin solution 3], and in (Shell emulsion emulsification), [Shell resin solution 1] was changed to [Shell resin solution 3] to produce [Shell emulsion 3].

[Example 4]
[Toner 4] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-2] to obtain [oil phase 4], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 4] to obtain [core emulsion 4], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-4] to produce [shell resin solution 4], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 4] to produce [shell emulsion 4], and so forth.

[Example 5]
[Toner 5] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-3] to obtain [oil phase 5], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 5] to obtain [core emulsion 5], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-4] to produce [shell resin solution 5], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 5] to produce [shell emulsion 5], and so forth.

[Example 6]
[Toner 6] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-3] to obtain [oil phase 6], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 6] to obtain [core emulsion 6], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-5] to produce [shell resin solution 6], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 6] to produce [shell emulsion 6], and so forth.

[Example 7]
[Toner 7] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-3] to obtain [oil phase 7], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 7] to obtain [core emulsion 7], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-6] to produce [shell resin solution 7], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 7] to produce [shell emulsion 7], and so forth.

[Comparative Example 1]
[Toner 8] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-4] to obtain [oil phase 8], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 8] to obtain [core emulsion 8], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-7] to produce [shell resin solution 8], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 8] to produce [shell emulsion 8], and thus [toner 8] was obtained.

[Comparative Example 2]
[Toner 9] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-3] to obtain [oil phase 9], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 9] to obtain [core emulsion 9], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-8] to produce [shell resin solution 9], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 9] to produce [shell emulsion 9], and thus [toner 9] was obtained.

[Comparative Example 3]
[Toner 10] was obtained in the same manner as in [Example 1], except for the steps of adding [Shell Emulsion 1] and the aqueous magnesium sulfate solution in the (aggregation and shell formation step) of [Example 1], adding 68 parts of sodium sulfate and then raising the temperature to 65° C., and excluding the step of adding sodium sulfate in the (fusion and stopping step).

[Comparative Example 4]
[Toner 11] was obtained in the same manner as in [Example 1], except that in (preparation of oil phase) of [Example 1], [amorphous polyester resin B-1] was changed to [amorphous polyester resin B-4] to obtain [oil phase 11], in (preparation of core emulsion 1), [oil phase 1] was changed to [oil phase 11] to obtain [core emulsion 11], in (preparation of shell resin solution), [amorphous polyester resin A-1] was changed to [amorphous polyester resin A-9] to produce [shell resin solution 11], and in (shell emulsion emulsification), [shell resin solution 1] was changed to [shell resin solution 11] to produce [shell emulsion 11], and so forth.

[Comparative Example 5]
In (Preparation of oil phase) of [Example 1], [Amorphous polyester resin B-1] was changed to [Amorphous polyester resin B-4] to obtain [Oil phase 12], in (Preparation of core emulsion 1), [Oil phase 1] was changed to [Oil phase 12] to obtain [Core emulsion 12], and in (Aggregation and shell formation step), except for the step of adding [Shell emulsion 1] and an aqueous magnesium sulfate solution, adding 68 parts of sodium sulfate and then raising the temperature to 65° C., and in (Fusion and termination step), except for the step of adding sodium sulfate, a procedure similar to that of [Example 1] was repeated to obtain [Toner 12].

The components of the toners of the examples and comparative examples are shown in Table 2 below.
Table 3 also shows the sulfonate group content, 14 C concentration, and the presence or absence of a monomer constituent unit derived from a plant in the resin of the shell layer of the toner in the examples and comparative examples.

<Preparation of carrier>
To 100 parts of toluene, 100 parts of silicone resin (organo straight silicone), 5 parts of γ-(2-aminoethyl)aminopropyltrimethoxysilane, and 10 parts of carbon black were added, and dispersed for 20 minutes using a homomixer to prepare a resin layer coating liquid.
Using a fluidized bed type coating device, the resin layer coating liquid was applied to the surface of 1,000 parts of spherical magnetite having a volume average particle size of 50 μm to prepare a [carrier].

<Preparation of Developer>
Each of the [developers] was prepared by mixing 5 parts of each of the [toners] and 95 parts of the [carrier] using a ball mill.
Next, the various properties of each of the toners and developers obtained were evaluated as follows. The results are shown in Table 4.

<Evaluation of low temperature fixability>
The composite resin particles are uniformly placed on the paper surface to a density of 0.8 mg/ ^cm2 . The powder is placed on the paper surface using a printer without a thermal fixing device. Other methods may be used as long as the powder can be uniformly placed at the above weight density.
The paper was passed through a pressure roller at a fixing speed (heat roller peripheral speed) of 213 mm/sec and a fixing pressure (pressure roller pressure) of 10 kg/cm ² , and the temperature at which cold offset occurred (MFT) was measured.
The measurement results were evaluated according to the following criteria.
Those rated as .circle-solid., .smallcircle., and .DELTA. are at a level that poses no practical problems.
The lower the temperature at which cold offset occurs, the better the low-temperature fixing property.
[Cold offset evaluation criteria]
◎: The minimum fixing temperature is 130° C. or less. ○: The minimum fixing temperature is greater than 130° C. and less than 135° C. △: The minimum fixing temperature is greater than 135° C. and less than 140° C. ×: The minimum fixing temperature is greater than 140° C.

<Evaluation of heat resistance storage stability>
The toner was filled into a 50 mL glass container and left in a thermostatic chamber at 50° C. for 24 hours, and then cooled to 24° C. Next, the penetration [mm] was measured by a penetration test (JIS K2235-1991), and the heat-resistant storage stability was evaluated according to the following evaluation criteria.
Those rated as .circle-solid., .smallcircle., and .DELTA. are at a level that poses no practical problems.
[Evaluation Criteria]
◎: Penetration of 20 mm or more ○: Penetration of 15 mm or more and less than 20 mm △: Penetration of 10 mm or more and less than 15 mm ×: Penetration of less than 10 mm

<Evaluation of electrostatic charge>
6 g of two-component developer was weighed and placed in a sealable metal cylinder, stirred at a stirring speed of 280 rpm, and the charge amount was measured by the blow-off method. The stirring time was 15 seconds (TA15), 60 seconds (TA60), and 600 seconds (TA600). TEFV200/300 (manufactured by Powder Tech Co., Ltd.) was used as the carrier.
The measurement results were evaluated according to the following criteria.
Those rated as .circle-solid., .smallcircle., and .DELTA. are at a level that poses no practical problems.
[Evaluation Criteria]
◎: 36 or more ○: 33 or more and less than 36 △: 30 or more and less than 33 ×: Less than 30

<Evaluation of environmental friendliness>
Environmental compatibility was evaluated based on the concentration of radioactive carbon isotope ^14C . The evaluation criteria are as follows:
[Evaluation Criteria]
○: Radioactive carbon isotope ^14C concentration is 10.8 pMC or more △: Radioactive carbon isotope ^14C concentration is 0.1 or more and less than 10.8 pMC ×: Radioactive carbon isotope ^14C concentration is less than 0.1

The results shown in Table 4 show that Examples 1 to 7 of the present invention exhibit excellent performance in terms of low-temperature fixability, heat-resistant storage stability, chargeability, and environmental compatibility.

The aspects of the present invention include, for example, the following.
(1) Resin particles containing at least an amorphous polyester resin and a crystalline polyester resin,
The amorphous polyester resin contains a structural unit derived from a plant-derived alcohol monomer,
the resin particles form a core-shell structure consisting of a core layer and a shell layer,
The resin particles, wherein the shell layer contains at least a polyester resin having a sulfonate group.
(2) The resin particles according to (1) above, wherein the sulfonate group content in the polyester resin having a sulfonate group is 2 mol % or more and 10 mol % or less based on the total amount of constituent units derived from carboxylic acid monomers constituting the sulfonate group-containing polyester resin.
(3) The resin particles according to (1) or (2) above, having a radioactive carbon isotope ^14C concentration of 10.8 pMC or more.
(4) The resin particles according to any one of (1) to (3) above, wherein the alcohol monomer of the amorphous polyester resin contains propylene glycol derived from plants.
(5) A toner comprising the resin particles according to any one of (1) to (4) above.
(6) an oil phase preparation step of preparing an oil phase in which a crystalline polyester resin and an amorphous polyester resin containing a structural unit derived from a plant-derived alcohol monomer are dissolved or dispersed in an organic solvent;
a phase inversion emulsification step in which the oil phase is neutralized with a neutralizing agent, and then an aqueous phase containing water is added thereto, thereby obtaining a microparticle dispersion by phase inversion emulsification in which the water-in-oil dispersion is inverted into an oil-in-water dispersion;
a desolvation step of removing an organic solvent from the fine particle dispersion;
an aggregating step of aggregating the fine particle dispersion from which the solvent has been removed to obtain aggregated particles;
a shelling step of forming a shell layer on the aggregated particles, the shell layer including a polyester resin having a sulfonate group;
a fusion step of fusing the aggregated particles having the shell layer formed thereon;
a washing and drying step of washing and drying the fused particles;
an annealing step of subjecting the washed and dried particles to an annealing treatment;
A method for producing resin particles having the formula:
(7) A toner storage unit, characterized in that it stores the toner described in (5) above.
(8) A developer comprising the toner described in (5) above and a carrier.
(9) an electrostatic latent image carrier;
an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearing member;
a developing unit having a toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a visible image,
10. An image forming apparatus, comprising the toner according to claim 9, wherein the toner is the toner according to claim 8.
(10) a step of forming an electrostatic latent image on an electrostatic latent image carrier;
a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier with a toner to form a toner image,
The image forming method according to the present invention, wherein the toner is the toner described in (5) above.

10 photoconductor drum 40 developing device 58 corona charger 80 transfer roller 90 cleaning device 110 process cartridge 210 paper feed section 211 paper feed cassette 212 paper feed roller 220 transport section 221 roller 222 timing roller 223 paper discharge roller 224 paper discharge tray 230 imaging section 231 photoconductor drum 233 exposure device 240 transfer section 241 drive roller 242 driven roller 243 intermediate transfer belt 244 primary transfer roller 245 secondary opposing roller 246 secondary transfer roller 250 fixing device 251 fixing belt 252 pressure roller L exposure P paper

Patent No. 2579150 JP 2001-158819 A Patent No. 6024276 Patent No. 4873734 Patent No. 3793920 Patent No. 5008129 JP2008-076519A JP 2015-102842 A JP 2014-098149 A

Claims (10)

Resin particles containing at least an amorphous polyester resin and a crystalline polyester resin,
The amorphous polyester resin contains a structural unit derived from a plant-derived alcohol monomer,
the resin particles form a core-shell structure consisting of a core layer and a shell layer,
The resin particles, wherein the shell layer contains at least a polyester resin having a sulfonate group. The resin particles according to claim 1, wherein the sulfonate group content in the polyester resin having the sulfonate group is 2 mol% or more and 10 mol% or less with respect to the total amount of the constituent units derived from the carboxylic acid monomer that constitutes the sulfonate group-containing polyester resin. 3. The resin particles according to claim 1 or 2, having a concentration of radioactive carbon isotope ^14C of 10.8 pMC or more. The resin particles according to claim 1 or 2, wherein the alcohol monomer of the amorphous polyester resin contains plant-derived propylene glycol. A toner comprising the resin particles according to claim 1 or 2. an oil phase preparation step of preparing an oil phase in which a crystalline polyester resin and an amorphous polyester resin containing a structural unit derived from a plant-derived alcohol monomer are dissolved or dispersed in an organic solvent;
a phase inversion emulsification step in which the oil phase is neutralized with a neutralizing agent, and then an aqueous phase containing water is added thereto, thereby obtaining a microparticle dispersion by phase inversion emulsification in which the water-in-oil dispersion is inverted into an oil-in-water dispersion;
a desolvation step of removing an organic solvent from the fine particle dispersion;
an aggregating step of aggregating the fine particle dispersion from which the solvent has been removed to obtain aggregated particles;
a shelling step of forming a shell layer on the aggregated particles, the shell layer including a polyester resin having a sulfonate group;
a fusion step of fusing the aggregated particles having the shell layer formed thereon;
a washing and drying step of washing and drying the fused particles;
an annealing step of subjecting the washed and dried particles to an annealing treatment;
A method for producing resin particles having the formula: A toner storage unit containing the toner according to claim 5. A developer comprising the toner according to claim 5 and a carrier. An electrostatic latent image carrier;
an electrostatic latent image forming means for forming an electrostatic latent image on the electrostatic latent image bearing member;
a developing unit having a toner for developing the electrostatic latent image formed on the electrostatic latent image carrier to form a visible image,
6. An image forming apparatus, comprising the toner according to claim 5. an electrostatic latent image forming step of forming an electrostatic latent image on an electrostatic latent image carrier;
a developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier with a toner to form a toner image,
6. An image forming method, comprising the toner according to claim 5.

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