Method for producing resin microparticles, resin microparticles, toner, and distillation apparatus

Abstract

To provide a method for producing resin microparticles that can suppress the adhesion of resin microparticles to the container wall due to poor granulation of resin microparticles and the inclusion of resin microparticles with deteriorated surface properties. [Solution] A method for producing resin fine particles, comprising: a resin dispersion preparation step of preparing a resin dispersion containing an organic solvent, water, a resin, and a surfactant; and a distillation step of removing the organic solvent from the resin dispersion by distillation, wherein the mass ratio of the resin to the surfactant in the resin dispersion is 1:1 to 1:2.

Description

Technical Field

[0001] The present invention relates to a method for producing resin fine particles, resin fine particles, toner, and a distillation apparatus.

Background Art

[0002] Generally, in a method for producing resin fine particles, a chemical reaction, an emulsification reaction, etc. are carried out under temperature control or pressure control, and the resin fine particles are produced through steps of recovering the resin fine particles and removing an organic solvent. In this production process, as the reaction progresses, there is a problem that resin fine particles adhere to the reaction tank wall surface due to poor granulation of the resin fine particles and mixing of resin fine particles with deteriorated surface properties, resulting in a decrease in the yield during the recovery of the resin fine particles.

[0003] In a conventional method for recovering an organic solvent in an emulsification reaction, the organic solvent and the aqueous medium evaporate, increasing the solid content concentration of the resin fine particles in the liquid, causing the resin fine particles to adhere to the reaction tank wall surface, and resulting in a decrease in the yield of the resin fine particles. In contrast, in Patent Document 1, as a device configuration that enables reduced pressure, a method is proposed in which water is added during distillation under reduced pressure to prevent an increase in the solid content concentration of the resin fine particles in the reaction tank. However, in Patent Document 1, there are problems such as an increase in the amount of energy required for distillation due to an increase in the amount of water, and it is inevitable that the solid content concentration increases when the liquid amount decreases, resulting in a decrease in the yield due to the adhesion of the resin fine particles to the reaction tank wall surface.

[0004] On the other hand, with respect to the problem that the amount of energy required for distillation increases due to an increase in the amount of water in the recovery of the organic solvent, Patent Document 2 proposes a method of preventing adhesion to the reaction tank wall surface by azeotropy by adding organic solvents having different boiling points. However, in Patent Document 2, there is a problem that the added organic solvent causes another reaction with the resin fine particles, adversely affecting the function of the resin fine particles.

[0005] In Patent Document 3, as a method other than adding moisture or an organic solvent, a method for suppressing the expansion of the particle size distribution of resin fine particles by controlling the vacuum pressure has been proposed. However, in Patent Document 3, there are problems such as adhesion to the reaction tank wall surface due to the properties of the resin fine particle surface, and it is inevitable that the yield decreases.

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a method for producing resin fine particles capable of suppressing the adhesion of resin fine particles to the container wall surface due to poor granulation of resin fine particles and the mixing of resin fine particles with deteriorated surface properties.

Means for Solving the Problems

[0007] The method for producing resin fine particles of the present invention as a means for solving the above problems includes a resin dispersion liquid preparation step of preparing a resin dispersion liquid containing an organic solvent, water, a resin, and a surfactant, and a distillation step of removing the organic solvent from the resin dispersion liquid by distillation. In the resin dispersion liquid, the mass ratio of the resin to the surfactant is 1:1 to 1:2.

Effects of the Invention

[0008] According to the present invention, it is possible to provide a method for producing resin fine particles capable of suppressing the adhesion of resin fine particles to the container wall surface due to poor granulation of resin fine particles and the mixing of resin fine particles with deteriorated surface properties.

Brief Description of the Drawings

[0009] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of a distillation apparatus according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0010] (Method for Producing Resin Fine Particles, and Resin Fine Particles) The present invention provides a method for producing resin fine particles, comprising a resin dispersion preparation step of preparing a resin dispersion containing an organic solvent, water, a resin, and a surfactant, and a distillation step of removing the organic solvent from the resin dispersion by distillation, and optionally including other steps.

[0011] The resin microparticles of the present invention contain a resin, a colorant, a mold release agent, and a surfactant, and optionally contain other components. The resin microparticles of the present invention are preferably manufactured by the method for manufacturing resin microparticles of the present invention. The resin microparticles of the present invention can avoid adhesion of resin microparticles to the container wall due to poor granulation and the inclusion of resin microparticles with deteriorated surface properties. Furthermore, by controlling the surface properties of the resin microparticles, they can be used as a component material for toners for developing electrostatic images in electrophotography, electrostatic recording, electrostatic printing, etc., not limited to polymerization or pulverization methods, and contribute to improving image density stability. The application range of the resin microparticles with controlled surface properties obtained by the present invention is not limited to toners, but is extremely useful for materials where resin functionality is required, such as paints, inks, recording materials, colorants such as fiber colorants, cosmetics, and other materials where surface properties affect color reproduction and skin feel.

[0012] <Resin particulate material> First, the materials of the resin microparticles will be described. The resin microparticles contain a resin, a mold release agent, a colorant, and a surfactant, and optionally other components such as a charge control agent, an active hydrogen group-containing compound, and a polymer that can react with the active hydrogen group-containing compound. In the production of resin microparticles, it is preferable to react the above materials to prepare an adhesive substrate.

[0013] <<Adhesive base material>> The adhesive substrate exhibits adhesion to recording media such as paper, and includes an adhesive polymer obtained by reacting the active hydrogen group-containing compound and a polymer reactive with the active hydrogen group-containing compound in an aqueous medium, and may further include a resin appropriately selected from known resins.

[0014] There are no particular restrictions on the weight-average molecular weight of the adhesive substrate, and it can be appropriately selected depending on the purpose. For example, it is preferably 1,000 or more, more preferably 2,000 to 10,000,000, and particularly preferably 3,000 to 1,000,000. If the weight-average molecular weight is less than 1,000, the resistance to hot offset may deteriorate.

[0015] There are no particular restrictions on the storage modulus of the adhesive substrate, and it can be appropriately selected depending on the purpose, but for example, 10,000 dyne / cm at a measurement frequency of 20 Hz. 2 The temperature at which (TG') becomes poise is usually 100°C or higher, and preferably 110°C to 200°C. If (TG') is below 100°C, the hot offset resistance may deteriorate. The viscosity of the adhesive substrate is not particularly limited and can be appropriately selected according to the purpose, but for example, the temperature at which poise is 1,000 at a measurement frequency of 20 Hz (Tη) is usually 180°C or lower, and preferably 90°C to 160°C. If (Tη) exceeds 180°C, the low-temperature fixing performance may deteriorate. Therefore, from the viewpoint of achieving both hot offset resistance and low-temperature fixing performance, it is preferable that (TG') is higher than (Tη). That is, the difference between (TG') and (Tη) (TG'-Tη) is preferably 0°C or higher, more preferably 10°C or higher, and even more preferably 20°C or higher. The larger the difference, the better. Furthermore, from the viewpoint of achieving both low-temperature fixation and heat-resistant storage, the (TG'-Tη) range is preferably 0°C to 100°C, more preferably 10°C to 90°C, and even more preferably 20°C to 80°C.

[0016] There are no particular limitations on the specific adhesive substrate, and it can be appropriately selected depending on the purpose, but polyester resins are particularly preferred. There are no particular limitations on the polyester resin, and it can be appropriately selected depending on the purpose, but for example, urea-modified polyester resins are particularly preferred. The urea-modified polyester resin is obtained by reacting an amine (B) as the active hydrogen group-containing compound and an isocyanate group-containing polyester prepolymer (A) as a polymer that can react with the active hydrogen group-containing compound in the aqueous medium. The urea-modified polyester resin may contain urethane bonds in addition to urea bonds, and in this case, there are no particular limitations on the molar ratio of urea bonds to urethane bonds (urea bonds / urethane bonds), and it can be appropriately selected depending on the purpose, but 100 / 0 to 10 / 90 is preferred, 80 / 20 to 20 / 80 is more preferred, and 60 / 40 to 30 / 70 is even more preferred. If the aforementioned molar ratio (urea bond / urea bond) is less than 10 / 90, the resistance to hot offset may deteriorate.

[0017] Preferred specific examples of the urea-modified polyester resin are (1) to (10) below. (1) A mixture of a polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct and isophthalic acid with isophorone diisocyanate, which has been ureated with isophorone diamine, and a polycondensate of bisphenol A ethylene oxide 2 molar adduct and isophthalic acid; (2) A mixture of a polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct and isophthalic acid with isophorone diisocyanate, which has been ureated with isophorone diamine, and a polycondensate of bisphenol A ethylene oxide 2 molar adduct and terephthalic acid; (3) A mixture of a polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct / bisphenol A propylene oxide 2 molar adduct and terephthalic acid with isophorone diisocyanate, which has been ureated with isophorone diamine, and a polycondensate of bisphenol A ethylene oxide 2 molar adduct / bisphenol A propylene oxide 2 molar adduct and terephthalic acid; (4) (5) A polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct / bisphenol A propylene oxide 2 molar adduct and terephthalic acid with isophorone diisocyanate, which is then urea-treated with isophorone diamine, and a mixture of a polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct and terephthalic acid with isophorone diisocyanate. - A mixture of a product urea-treated with hexamethylenediamine and a polycondensate of bisphenol A ethylene oxide 2 molar adduct and terephthalic acid, (6) A polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct and terephthalic acid with isophorone diisocyanate, which is then urea-treated with hexamethylenediamine and a mixture of a product urea-treated with hexamethylenediamine and a polycondensate of bisphenol A ethylene oxide 2 molar adduct / bisphenol A propylene oxide 2 molar adduct and terephthalic acid,(7) A polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct and terephthalic acid with isophorone diisocyanate, which is then ureated with ethylenediamine, and a mixture of this and the polycondensate of bisphenol A ethylene oxide 2 molar adduct and terephthalic acid; (8) A polyester prepolymer obtained by reacting a polycondensate of bisphenol A ethylene oxide 2 molar adduct and isophthalic acid with diphenylmethane diisocyanate, which is then ureated with hexamethylenediamine, and a mixture of this and the polycondensate of bisphenol A ethylene oxide 2 molar adduct and isophthalic acid; (9) Bisphenol A ethylene oxide 2 molar adduct / bisphenol (10) A polyester prepolymer obtained by reacting a 2-mol adduct of bisphenol A propylene oxide and a polycondensate of terephthalic acid / dodecenyl succinic anhydride with diphenylmethane diisocyanate, which is then ureated with hexamethylenediamine, and a mixture of this and a 2-mol adduct of bisphenol A ethylene oxide / 2-mol adduct of bisphenol A propylene oxide and a polycondensate of terephthalic acid; (10) A polyester prepolymer obtained by reacting a 2-mol adduct of bisphenol A ethylene oxide and a polycondensate of isophthalic acid with toluene diisocyanate, which is then ureated with hexamethylenediamine, and a mixture of this and a 2-mol adduct of bisphenol A ethylene oxide and a polycondensate of isophthalic acid.

[0018] <<<Compounds containing active hydrogen groups>>> The active hydrogen group-containing compound acts as an extension agent, crosslinking agent, etc., when a polymer reactable with the active hydrogen group-containing compound undergoes an extension reaction, crosslinking reaction, etc., in the aqueous medium. The active hydrogen group-containing compound is not particularly limited as long as it has an active hydrogen group, and can be appropriately selected according to the purpose. For example, when the polymer reactable with the active hydrogen group-containing compound is the isocyanate group-containing polyester prepolymer (A), the amines (B) are preferred because they can be increased in molecular weight through reactions such as extension reactions and crosslinking reactions with the isocyanate group-containing polyester prepolymer (A). The active hydrogen group is not particularly limited and can be appropriately selected according to the purpose. Examples include hydroxyl groups (alcoholic hydroxyl groups or phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups, etc. These may be used individually or in combination of two or more. Among these, hydroxyl groups are preferred, and alcoholic hydroxyl groups are particularly preferred.

[0019] There are no particular restrictions on the amines (B), and they can be appropriately selected depending on the purpose. Examples include diamines (B1), polyamines with a valency of 3 or higher (B2), amino alcohols (B3), amino mercaptans (B4), amino acids (B5), and B1 to B5 with the amino group blocked (B6). These may be used individually or in combination of two or more. Among these, diamines (B1) and mixtures of diamines (B1) and a small amount of polyamines with a valency of 3 or higher (B2) are particularly preferred.

[0020] Examples of the diamine (B1) include aromatic diamines, alicyclic diamines, and aliphatic diamines. Examples of aromatic diamines include phenylenediamine, diethyltoluenediamine, and 4,4'-diaminodiphenylmethane. Examples of alicyclic diamines include 4,4'-diamino-3,3'dimethyldicyclohexylmethane, diaminecyclohexane, and isophorone diamine. Examples of aliphatic diamines include ethylenediamine, tetramethylenediamine, and hexamethylenediamine. Examples of the aforementioned polyamines with a valency of 3 or higher (B2) include diethylenetriamine and triethylenetetramine. Examples of the amino alcohol (B3) include ethanolamine and hydroxyethylaniline. Examples of the amino mercaptan (B4) include aminoethyl mercaptan and aminopropyl mercaptan. Examples of the aforementioned amino acid (B5) include aminopropionic acid and aminocaproic acid. Examples of (B6) obtained by blocking the amino group of B1 to B5 include ketimine compounds and oxazolizone compounds obtained from any of the amines (B1) to (B5) and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.).

[0021] Furthermore, a reaction inhibitor can be used to stop the extension reaction, crosslinking reaction, etc., between the active hydrogen group-containing compound and the polymer that can react with the active hydrogen group-containing compound. Using such a reaction inhibitor is preferable because it allows the molecular weight of the adhesive substrate to be controlled within a desired range. Examples of such reaction inhibitors include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.) or compounds that block these (ketimine compounds).

[0022] The mixing ratio of the amines (B) and the isocyanate group-containing polyester prepolymer (A) is such that the equivalent ratio of the isocyanate group [NCO] in the isocyanate group-containing prepolymer (A) to the amino group [NHx] in the amines (B) ([NCO] / [NHx]) is preferably 1 / 3 to 3 / 1, more preferably 1 / 2 to 2 / 1, and particularly preferably 1 / 1.5 to 1.5 / 1. If the equivalent ratio ([NCO] / [NHx]) is less than 1 / 3, the low-temperature fixability may decrease, and if it exceeds 3 / 1, the molecular weight of the urea-modified polyester resin may decrease, and the hot offset resistance may deteriorate.

[0023] <<<Polymers that can react with active hydrogen group-containing compounds>>> The polymer that can react with the active hydrogen group-containing compound (hereinafter sometimes referred to as "prepolymer") is not particularly limited as long as it has at least a site that can react with the active hydrogen group-containing compound, and can be appropriately selected from known resins, etc. Examples include polyol resins, polyacrylic resins, polyester resins, epoxy resins, and derivative resins thereof. These may be used individually or in combination of two or more. Among these, polyester resins are particularly preferred in terms of high fluidity and transparency when melted.

[0024] There are no particular limitations on the reactable sites in the prepolymer with the active hydrogen group-containing compound, and they can be appropriately selected from known substituents, such as isocyanate groups, epoxy groups, carboxylic acids, and acid chloride groups. These may be present individually or in groups of two or more. Among these, isocyanate groups are particularly preferred.

[0025] Among the aforementioned prepolymers, urea bond-forming group-containing polyester resin (RMPE) is particularly preferred because it allows for easy adjustment of the molecular weight of the polymer component and ensures good oil-free low-temperature fixing characteristics in the toner composition, especially good release and fixing properties even without a release oil application mechanism to the fixing heating medium. Examples of the urea bond-forming group include isocyanate groups. When the urea bond-forming group in the urea bond-forming group-containing polyester resin (RMPE) is an isocyanate group, the isocyanate group-containing polyester prepolymer (A) is particularly preferred as the polyester resin (RMPE).

[0026] The isocyanate group-containing polyester prepolymer (A) is not particularly limited and can be appropriately selected depending on the purpose. Examples include polycondensates of polyol (PO) and polycarboxylic acid (PC), which are obtained by reacting the active hydrogen group-containing polyester resin with polyisocyanate (PIC).

[0027] There are no particular restrictions on the polyol (PO), and it can be appropriately selected depending on the purpose. Examples include diols (DIO), trivalent or higher polyols (TO), and mixtures of diols (DIO) and trivalent or higher polyols (TO). These may be used individually or in combination of two or more. Among these, diols (DIO) alone, or mixtures of diols (DIO) and a small amount of trivalent or higher polyols (TO), are preferred.

[0028] Examples of the diol (DIO) include alkylene glycol, alkylene ether glycol, alicyclic diol, alkylene oxide adduct of alicyclic diol, bisphenols, and alkylene oxide adducts of bisphenols. Preferably, the alkylene glycol has 2 to 12 carbon atoms, and examples include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 1,6-hexanediol. Examples of the alkylene ether glycol include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether glycol. Examples of the alicyclic diol include 1,4-cyclohexanedimethanol and hydrogenated bisphenol A. Examples of the alkylene oxide adduct of the alicyclic diol include those obtained by adducting an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the alicyclic diol. Examples of the bisphenols include bisphenol A, bisphenol F, and bisphenol S. Examples of alkylene oxide adducts of the bisphenols include those obtained by adducting ethylene oxide, propylene oxide, butylene oxide, and other alkylene oxides to the bisphenols. Among these, alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols are preferred, and mixtures of alkylene oxide adducts of bisphenols and alkylene glycols having 2 to 12 carbon atoms are particularly preferred.

[0029] The aforementioned polyols with a valency of 3 or higher (TO) are preferably 3 to 8 or higher, and examples include polyhydric aliphatic alcohols with a valency of 3 or higher, polyphenols with a valency of 3 or higher, and alkylene oxide adducts of polyphenols with a valency of 3 or higher. Examples of polyhydric aliphatic alcohols with a valency of 3 or higher include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and sorbitol. Examples of polyphenols with a valency of 3 or higher include trisphenol PA, phenol novolac, and cresol novolac. Examples of alkylene oxide adducts of polyphenols with a valency of 3 or higher include those obtained by adducting an alkylene oxide such as ethylene oxide, propylene oxide, or butylene oxide to the aforementioned polyphenols with a valency of 3 or higher.

[0030] In the mixture of the diol (DIO) and the trivalent or higher polyol (TO), the mixed mass ratio (DIO:TO) of the diol (DIO) and the trivalent or higher polyol (TO) is preferably 100:0.01 to 100:10, and more preferably 100:0.01 to 100:1.

[0031] There are no particular restrictions on the polycarboxylic acid (PC), and it can be appropriately selected depending on the purpose. Examples include dicarboxylic acid (DIC), trivalent or higher polycarboxylic acid (TC), and mixtures of dicarboxylic acid (DIC) and trivalent or higher polycarboxylic acid. These may be used individually or in combination of two or more. Among these, dicarboxylic acid (DIC) alone or a mixture of DIC and a small amount of trivalent or higher polycarboxylic acid (TC) is preferred. Examples of the dicarboxylic acid include alkylenedicarboxylic acid, alkenylenedicarboxylic acid, and aromatic dicarboxylic acid. Examples of alkylenedicarboxylic acid include succinic acid, adipic acid, and sebacic acid. As for the alkenylenedicarboxylic acid, those with 4 to 20 carbon atoms are preferred, such as maleic acid and fumaric acid. As for the aromatic dicarboxylic acid, those with 8 to 20 carbon atoms are preferred, such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid. Among these, alkenylenedicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms are preferred.

[0032] The aforementioned polycarboxylic acid (TO) with a valency of 3 to 8 or higher is preferred, and examples include aromatic polycarboxylic acids. The aforementioned aromatic polycarboxylic acid has 9 to 20 carbon atoms, and examples include trimellitic acid and pyromellitic acid.

[0033] As the polycarboxylic acid (PC), any acid anhydride or lower alkyl ester selected from the dicarboxylic acid (DIC), the trivalent or higher polycarboxylic acid (TC), and a mixture of the dicarboxylic acid (DIC) and the trivalent or higher polycarboxylic acid may be used. Examples of the lower alkyl ester include methyl esters, ethyl esters, isopropyl esters, and the like.

[0034] There are no particular restrictions on the mixed mass ratio (DIC:TC) of the dicarboxylic acid (DIC) and the trivalent or higher polycarboxylic acid (TC) in the mixture of the dicarboxylic acid (DIC) and the trivalent or higher polycarboxylic acid (TC), and it can be appropriately selected depending on the purpose. For example, 100:0.01 to 100:10 is preferred, and 100:0.01 to 100:1 is more preferred.

[0035] There are no particular restrictions on the mixing ratio when polyol (PO) and polycarboxylic acid (PC) are polycondensed, and can be appropriately selected depending on the purpose. For example, the equivalent ratio ([OH] / [COOH]) of hydroxyl groups [OH] in the polyol (PO) to carboxyl groups [COOH] in the polycarboxylic acid (PC) is preferably 2 / 1 to 1 / 1, more preferably 1.5 / 1 to 1 / 1, and particularly preferably 1.3 / 1 to 1.02 / 1.

[0036] There are no particular restrictions on the content of the polyol (PO) in the isocyanate group-containing polyester prepolymer (A), and it can be appropriately selected depending on the purpose. For example, 0.5% to 40% by mass is preferred, 1% to 30% by mass is more preferred, and 2% to 20% by mass is particularly preferred. If the content is less than 0.5% by mass, the hot offset resistance deteriorates, making it difficult to achieve both heat preservation and low-temperature fixation. If the content exceeds 40% by mass, the low-temperature fixation may deteriorate.

[0037] There are no particular restrictions on the polyisocyanate (PIC), and it can be appropriately selected depending on the purpose. Examples include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, isocyanurates, phenol derivatives thereof, oximes, caprolactams, etc. Examples of aliphatic polyisocyanates include tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethylcaproate, octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, trimethylhexane diisocyanate, and tetramethylhexane diisocyanate. Examples of alicyclic polyisocyanates include isophorone diisocyanate and cyclohexylmethane diisocyanate. Examples of the aromatic diisocyanates include tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, diphenylene-4,4'-diisocyanate, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 3-methyldiphenylmethane-4,4'-diisocyanate, and diphenyl ether-4,4'-diisocyanate. Examples of the aromatic aliphatic diisocyanates include α,α,α',α'-tetramethylxylylene diisocyanate. Examples of the isocyanurates include tris-isocyanatoalkyl-isocyanurate and triisocyanatocycloalkyl-isocyanurate. These can be used individually or in combination of two or more.

[0038] When reacting the polyisocyanate (PIC) with the active hydrogen group-containing polyester resin (e.g., hydroxyl group-containing polyester resin), the mixing ratio of isocyanate groups [NCO] in the polyisocyanate (PIC) to hydroxyl groups [OH] in the hydroxyl group-containing polyester resin ([NCO] / [OH]) is preferably 5 / 1 to 1 / 1, more preferably 4 / 1 to 1.2 / 1, and particularly preferably 3 / 1 to 1.5 / 1. If the isocyanate group [NCO] exceeds 5, low-temperature fixability may deteriorate, and if it is less than 1, offset resistance may deteriorate.

[0039] There are no particular restrictions on the content of the polyisocyanate (PIC) in the isocyanate group-containing polyester prepolymer (A), and it can be appropriately selected depending on the purpose. For example, 0.5% to 40% by mass is preferred, 1% to 30% by mass is more preferred, and 2% to 20% by mass is even more preferred. If the content is less than 0.5% by mass, the hot offset resistance deteriorates, making it difficult to achieve both heat resistance and low-temperature fixation. If the content exceeds 40% by mass, the low-temperature fixation may deteriorate.

[0040] The average number of isocyanate groups per molecule of the isocyanate group-containing polyester prepolymer (A) is preferably 1 or more, more preferably 1.2 to 5, and even more preferably 1.5 to 4. If the average number of isocyanate groups is less than 1, the molecular weight of the polyester resin (RMPE) modified with the urea bond-forming group will decrease, which may worsen the hot offset resistance.

[0041] The weight-average molecular weight (Mw) of the polymer reactable with the active hydrogen group-containing compound is preferably 1,000 to 30,000, and more preferably 1,500 to 15,000, based on the molecular weight distribution of the tetrahydrofuran (THF)-soluble component by GPC (gel permeation chromatography). If the weight-average molecular weight (Mw) is less than 1,000, the heat-resistant storage properties may deteriorate, and if it exceeds 30,000, the low-temperature fixability may deteriorate.

[0042] The measurement of the molecular weight distribution by the gel permeation chromatography (GPC) can be carried out, for example, as follows. That is, first, the column is stabilized in a heat chamber at 40°C. At this temperature, tetrahydrofuran (THF) is flowed as a column solvent at a flow rate of 1 ml per minute, and a 50 μl to 200 μl of a tetrahydrofuran sample solution of a resin with the sample concentration adjusted to 0.05 mass% to 0.6 mass% is injected for measurement. When measuring the molecular weight of the sample, the molecular weight distribution of the sample is calculated from the relationship between the logarithmic value of the calibration curve created by several monodisperse polystyrene standard samples and the count number. As the standard polystyrene sample for creating the calibration curve, those having molecular weights of 6×10 2 、2.1×10 2 、4×10 2 、1.75×10 4 、1.1×10 5 、3.9×10 5 、8.6×10 5 、2×10 6 、and 4.48×10 6 manufactured by Pressure Chemical Co. or Toyo Soda Industry Co., Ltd. are used, and it is preferable to use at least about 10 standard polystyrene samples. In addition, an RI (refractive index) detector can be used as the detector.

[0043] <<Resin>> The aforementioned resin is not particularly limited and can be appropriately selected depending on the purpose, but examples include polyester resin, polystyrene, poly-p-chlorostyrene, polymers of styrene or its substituted derivatives such as polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethacrylate copolymer, Examples include styrene-acrylonitrile copolymers, styrene-vinyl methyl ketone copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers, styrene-maleic acid copolymers, styrene-maleic acid ester copolymers, and other styrene copolymers; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resins, epoxy polyol resins, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resins, rosin, modified rosin, terpene resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffin, and paraffin wax. These may be used individually or in combination of two or more. Among these, polyester resins are particularly preferred due to their high solubility in organic solvents.

[0044] The polyester resin is typically obtained by condensation polymerization of an alcohol and a carboxylic acid. Examples of the alcohol include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol; etherified bisphenols such as 1,4-bis(hydroxymethyl)cyclohexane and bisphenol A; other divalent alcohol monomers; and trivalent or higher polyvalent alcohol monomers. Examples of carboxylic acids include divalent organic acid monomers such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid; and trivalent or higher polyvalent carboxylic acid monomers such as 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxypropane, and 1,2,7,8-octanetetracarboxylic acid.

[0045] <<Coloring agent>> There are no particular restrictions on the coloring agent, and it can be appropriately selected from known dyes and pigments depending on the purpose. Examples include carbon black, naphthol yellow S, cadmium red, phthalocyanine blue, cobalt purple, chrome green, etc. These may be used individually or in combination of two or more.

[0046] The content of the coloring agent is not particularly limited and can be appropriately selected depending on the purpose, but 1% to 15% by mass is preferred, and 3% to 10% by mass is more preferred. If the content of the coloring agent is less than 1% by mass, a decrease in coloring power will be observed, and if the content exceeds 15% by mass, poor dispersion of the pigment may occur, leading to a decrease in coloring power and a decrease in electrical properties.

[0047] The coloring agent may be used as a masterbatch compounded with a resin. The resin is not particularly limited and can be appropriately selected from known resins depending on the purpose. Examples include polymers of styrene or its substituted derivatives, styrene copolymers, polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, aliphatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin, etc. These may be used individually or in combination of two or more.

[0048] Examples of polymers of styrene or its substituted counterparts include polyester resins, polystyrene, poly-p-chlorostyrene, and polyvinyltoluene. Examples of styrene-based copolymers include styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, and styrene-maleic acid ester copolymer.

[0049] The masterbatch can be manufactured by mixing or kneading the masterbatch resin and the colorant under high shear force. In this case, it is preferable to add an organic solvent to enhance the interaction between the colorant and the resin. The so-called flushing method is also preferable because it allows the use of the wet cake of the colorant as is and does not require drying. This flushing method is a method in which an aqueous paste containing water of the colorant is mixed or kneaded together with the resin and an organic solvent, and the colorant is transferred to the resin side to remove the water and organic solvent components. For the mixing or kneading, a high-shear dispersion device such as a three-roll mill is preferably used.

[0050] <<Release agent>> There are no particular restrictions on the mold release agent, and it can be appropriately selected from known ones depending on the purpose. For example, waxes are preferred. Examples of waxes include carbonyl group-containing waxes, polyolefin waxes, and long-chain hydrocarbons. These may be used individually or in combination of two or more. Among these, carbonyl group-containing waxes are preferred. Examples of carbonyl group-containing waxes include polyalkanoates, polyalkanols, polyalkanoamides, polyalkylamides, and dialkylketones. Examples of polyalkanoates include carnauba wax, montane wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, and 1,18-octadecanediol distearate. Examples of polyalkanols include tristearyl trimellitate and distearyl maleate. Examples of the polyalkanoamide include dibehenylamide. Examples of the polyalkylamide include trimellitic tristearylamide. Examples of the dialkylketone include distearyl ketone. Among these carbonyl group-containing waxes, polyalkanoates are particularly preferred. Examples of the polyolefin wax include polyethylene wax and polypropylene wax. Examples of the long-chain hydrocarbon include paraffin wax and sazole wax.

[0051] There are no particular restrictions on the melting point of the release agent, and it can be appropriately selected depending on the purpose, but 40°C to 160°C is preferred, 50°C to 120°C is more preferred, and 60°C to 90°C is particularly preferred. If the melting point of the release agent is less than 40°C, the wax may adversely affect the heat resistance of the toner composition, and if it exceeds 160°C, cold offset may easily occur during fixing at low temperatures. The melt viscosity of the release agent, measured at a temperature 20°C higher than the melting point of the wax, is preferably 5 cps to 1,000 cps, and more preferably 10 cps to 100 cps. If the melt viscosity is less than 5 cps, the release properties may decrease, and if it exceeds 1,000 cps, the improvement in hot offset resistance and low-temperature fixing properties may not be obtained.

[0052] There are no particular restrictions on the content of the release agent, and it can be appropriately selected depending on the purpose, but 0% to 40% by mass is preferred, and 3% to 30% by mass is more preferred. If the content of the release agent exceeds 40% by mass, the fluidity may deteriorate. The intensity ratio of the absorption spectral peaks obtained by the FTIR-ATR mapping on the surface of the resin fine particles and the ratio of said intensity ratio can be measured by the following method.

[0053] <Measurement of the intensity ratio of absorption spectral peaks and the percentage of said intensity ratio by FTIR-ATR mapping on the surface of resin microparticles> Three grams of the aforementioned resin fine particles are pressed for one minute under a load of 6 tons using an automatic pellet molding machine Type M No. 50 BRP-E (manufactured by MAEKAWA TESTING MACHINE) to produce pellets. The pellets are then FTIR-ATR mapped using a Spotlight400 infrared imaging system (manufactured by Perkin Elmer) under the conditions of a measurement range of 50 μm × 50 μm and a pixel size of 1.56 μm × 1.56 μm (1,024 divisions), resulting in a toner pellet with a diameter of 40 mm and a thickness of approximately 2 mm, at a wavenumber of 828 cm⁻¹. -1 The intensity of the absorption spectral peak P 828 And, wave number 2,850cm -1 The intensity of the absorption spectral peak P2850 We find P. 828 This is the intensity of the peak originating from the resin, P 2850 Since this is the intensity of the peak derived from the release agent, the intensity ratio (P 2850 / P 828 ) represents the relative amount of release agent near the surface of the resin microparticles. Strength ratio (P 2850 / P 828 The average value of ) is for an infrared incident angle of 41.5° and a resolution of 4cm. -1 The measurement is taken 20 times for cumulative measurement, and then the measurement is taken 100 times and the average is calculated.

[0054] The aforementioned resin nanoparticles were found to have a wavenumber of 828 cm² as determined by FTIR-ATR mapping. -1 The intensity of the absorption spectral peak P 828 For a wave number of 2,850 cm -1 The intensity of the absorption spectral peak P 2850 The intensity ratio (P 2850 / P 828 The average value of (P) is preferably 0.20 or more and 0.40 or less, more preferably 0.25 or more and 0.35 or less, and even more preferably 0.27 or more and 0.33 or less. 2850 / P 828 If the average value of ) is 0.20 or higher, the resistance to hot offset is improved, and if it is 0.40 or lower, a decrease in yield due to adhesion to the reaction vessel wall can be prevented. Strength ratio (P) of the resin fine particles 2850 / P 828 The percentage of those with a strength ratio (P) of 0.40 or higher is preferably 10% to 50%, more preferably 20% to 40%, even more preferably 25% to 35%, and particularly preferably 27% to 33%. 2850 / P 828 If the amount is 10% or more, the resistance to hot offset is improved, and if it is 50% or less, it is possible to prevent a decrease in yield due to adhesion to the reaction vessel wall.

[0055] <<Static Control Agent>> There are no particular limitations on the charge control agent, and it can be appropriately selected from known materials depending on the purpose. However, since the color tone may change if colored materials are used, colorless or nearly white materials are preferred. Examples include triphenylmethane dyes, molybdate chelate pigments, rhodamine dyes, alkoxyamines, quaternary ammonium salts (including fluorine-modified quaternary ammonium salts), alkylamides, elemental phosphorus or its compounds, elemental tungsten or its compounds, fluorine-based surfactants, metal salts of salicylic acid, and metal salts of salicylic acid derivatives. These may be used individually or in combination of two or more. The aforementioned charge control agent may be a commercially available product, such as Bontron P-51, a quaternary ammonium salt; E-82, an oxynaphthoic acid-based metal complex; E-84, a salicylic acid-based metal complex; and E-89, a phenolic condensate (all manufactured by Orient Chemical Industry Co., Ltd.); TP-302 and TP-415, quaternary ammonium salt molybdenum complexes (both manufactured by Hodogaya Chemical Co., Ltd.); Copy Charge PSYVP2038, a quaternary ammonium salt; Copy Blue PR, a triphenylmethane derivative; Copy Charge NEGVP2036 and Copy Charge NXVP434, quaternary ammonium salts (all manufactured by Hoechst); LRA-901; LR-147, a boron complex (manufactured by Nippon Carlit Co., Ltd.); quinacridone; azo pigments; and other polymer compounds having functional groups such as sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. The charge control agent may be melt-kneaded together with the masterbatch and then dissolved or dispersed, or it may be added directly to the organic solvent when dissolving or dispersing together with each component of the resin fine particles, or it may be fixed to the surface of the resin fine particles after manufacturing.

[0056] The content of the charge control agent varies depending on the type of resin, the presence or absence of additives, the dispersion method, etc., and cannot be specified in general terms. However, for example, 0.1 to 10 parts by mass, and more preferably 0.2 to 5 parts by mass, per 100 parts by mass of the resin. If the content is less than 0.1 parts by mass, charge control may not be obtained, and if the content of the charge control agent exceeds 10 parts by mass per 100 parts by mass of the resin, the electrostatic charge may become too high, reducing the effect of the main charge control agent and leading to a decrease in fluidity.

[0057] <<Other ingredients>> The aforementioned other components are not particularly limited and can be appropriately selected depending on the purpose. Examples include inorganic fine particles, flow improvers, cleaning improvers, magnetic materials, metal soaps, emulsifying aids, and the like.

[0058] The inorganic fine particles are not particularly limited and can be appropriately selected from known ones depending on the purpose. Examples 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, red iron oxide, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride, etc. These may be used individually or in combination of two or more. The primary particle size of the inorganic fine particles is preferably 5 nm to 2 μm, and more preferably 5 nm to 500 nm. The specific surface area of ​​the inorganic fine particles by the BET method is 20 m². 2 / g~500m 2 The amount per g is preferred. The content of the inorganic fine particles is preferably 0.01% to 5.0% by mass, and more preferably 0.01% to 2.0% by mass.

[0059] The aforementioned fluidity improver refers to an agent that can be surface-treated to increase hydrophobicity and prevent deterioration of the toner composition's fluidity and electrostatic properties even under high humidity conditions. Examples include silane coupling agents, silylation agents, silane coupling agents having alkyl fluoride compounds, organic titanate coupling agents, aluminum coupling agents, silicone oils, and modified silicone oils. The aforementioned cleaning properties improver includes, for example, fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, polymer fine particles produced by soap-free emulsion polymerization such as polymethyl methacrylate fine particles and polystyrene fine particles. The polymer fine particles are preferably those with a relatively narrow particle size distribution, and those with a volume-average particle size of 0.01 μm to 1 μm are preferred. The magnetic material is not particularly limited and can be appropriately selected from known materials depending on the purpose. Examples include iron oxides such as magnetite, hematite, and ferrite, metals such as iron, cobalt, and nickel, or alloys and mixtures thereof of these metals such as aluminum, cobalt, copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium. Magnetite is particularly preferred in terms of magnetic properties. These ferromagnetic materials preferably have an average particle size of 0.1 μm to 2 μm, and the amount to be included in the toner composition is preferably 15 to 200 parts by mass, and more preferably 20 to 100 parts by mass, per 100 parts by mass of the resin component.

[0060] The emulsifying agent is not particularly limited as long as it is a resin capable of forming an aqueous dispersion in an aqueous medium, and can be appropriately selected from known resins according to the purpose. It may be a thermoplastic resin or a thermosetting resin, and examples include vinyl resins, polyurethane resins, epoxy resins, polyester resins, polyamide resins, polyimide resins, silicon resins, phenolic resins, melamine resins, urea resins, aniline resins, ionomer resins, and polycarbonate resins, but among these, vinyl resins are particularly preferred. These may be used individually or in combination of two or more. Among these, it is preferable that the mixture be formed from at least one selected from vinyl resins, polyurethane resins, epoxy resins, and polyester resins, as this makes it easier to obtain a fine spherical aqueous dispersion. The vinyl resin is a polymer obtained by homopolymerizing or copolymerizing vinyl monomers, and examples include styrene-(meth)acrylic acid ester resins, styrene-butadiene copolymers, (meth)acrylic acid-acrylic acid ester polymers, styrene-acrylonitrile copolymers, styrene-maleic anhydride copolymers, and styrene-(meth)acrylic acid copolymers. Furthermore, a copolymer comprising a monomer having at least two unsaturated groups can also be used as the emulsifying aid. There are no particular restrictions on the monomer having at least two unsaturated groups, and it can be appropriately selected depending on the purpose. Examples include the sodium salt of ethylene oxide adduct sulfate methacrylate ("Eleminol RS-30", manufactured by Sanyo Chemical Industries, Ltd.), divinylbenzene, and 1,6-hexanediol acrylate.

[0061] The emulsifying agent can be obtained by polymerization according to a known method appropriately selected according to the purpose, but it is preferable to obtain it as an aqueous dispersion of the emulsifying agent. Methods for preparing the aqueous dispersion of the emulsifying agent include, for example, (1) in the case of vinyl resin, a method of directly producing an aqueous dispersion of resin fine particles by a polymerization reaction selected from suspension polymerization, emulsion polymerization, seed polymerization and dispersion polymerization, using vinyl monomer as a starting material; (2) in the case of polyaddition or condensation resins such as polyester resin, polyurethane resin, and epoxy resin, a method of producing an aqueous dispersion of the emulsifying agent by dispersing a precursor (monomer, oligomer, etc.) or its solvent solution in an aqueous medium in the presence of a suitable dispersant, and then heating or curing by adding a curing agent; (3) in the case of polyaddition or condensation resins such as polyester resin, polyurethane resin, and epoxy resin, a precursor (monomer, oligomer, etc.) or its solvent solution (preferably a liquid).(4) A method of obtaining an emulsifying agent by dissolving a suitable emulsifying agent in a solution (which may be liquefied by heating), then adding water to perform phase inversion emulsification; (5) A method of obtaining an emulsifying agent by grinding a resin prepared in advance by a polymerization reaction (which may be any polymerization reaction mode such as addition polymerization, ring-opening polymerization, polyaddition, addition condensation, or condensation polymerization) using a mechanical rotary or jet type fine grinder, then classifying the resin, and then dispersing the emulsifying agent in water in the presence of a suitable dispersant; (6) A method of obtaining an emulsifying agent by spraying a resin solution obtained by dissolving a resin prepared in advance by a polymerization reaction (which may be any polymerization reaction mode such as addition polymerization, ring-opening polymerization, polyaddition, addition condensation, or condensation polymerization) in a solvent in a mist form, and then dispersing the emulsifying agent in water in the presence of a suitable dispersant; (7) A method of obtaining an emulsifying agent by spraying a resin solution obtained by dissolving a resin prepared in advance by a polymerization reaction (which may be any polymerization reaction mode such as addition polymerization, ring-opening polymerization, polyaddition, addition condensation, or condensation polymerization) in a solvent in a mist form, and then dispersing the emulsifying agent in water in the presence of a suitable dispersant; (i) A resin solution prepared by dissolving the resin prepared by (i) in a solvent is dissolved in a resin solution to which a poor solvent is added, or an emulsifying agent that has been preheated and dissolved in a solvent is cooled to precipitate the emulsifying agent, then the solvent is removed to obtain the emulsifying agent, and the emulsifying agent is dispersed in water in the presence of a suitable dispersant. (7) A resin solution prepared by dissolving the resin prepared by a polymerization reaction (addition polymerization, ring-opening polymerization, polyaddition, addition-condensation, condensation polymerization, etc.) in a solvent is dispersed in an aqueous medium in the presence of a suitable dispersant, and then the solvent is removed by heating or reduced pressure. (8) A resin solution prepared by dissolving the resin prepared by a polymerization reaction (addition polymerization, ring-opening polymerization, polyaddition, addition-condensation, condensation polymerization, etc.) in a solvent is dissolved in a resin solution to which a suitable emulsifying agent is dissolved, and then water is added to perform phase inversion emulsification. These are some of the preferred methods.

[0062] <Resin dispersion preparation process> In the resin dispersion preparation process, a resin dispersion containing an organic solvent, water, resin, and surfactant is prepared. Methods for preparing resin dispersions include, for example, known suspension polymerization methods, emulsification flocculation methods, and emulsification dispersion methods, but the following methods are preferred. First, the resin fine particle material, which includes an active hydrogen group-containing compound and a polymer reactive with the active hydrogen group-containing compound, is dissolved in an organic solvent to prepare an oil phase containing the resin. Next, the oil phase is dispersed in an aqueous medium containing a surfactant, and then the active hydrogen group-containing compound and the polymer reactive with the active hydrogen group-containing compound are reacted in the aqueous medium to produce an adhesive substrate in particulate form, thereby preparing a resin dispersion.

[0063] In the process of manufacturing resin microparticles, the resin microparticles are granulated by either the resin dispersion preparation process or the distillation process described later. Accordingly, the particle size and material arrangement of the constituent materials of the granulated resin microparticles are determined by the mass ratio of resin to surfactant in the resin dispersion. If the surfactant content is low, the particle size distribution of the resin microparticles deteriorates. On the other hand, if the surfactant content is excessively high, the concentration of surfactant on the surface of the resin microparticles increases, leading to adhesion to the reaction vessel wall due to deterioration of surface properties and a decrease in the yield due to a decrease in the recovery rate when the resin microparticles are recovered.

[0064] The organic solvent is not particularly limited as long as it is a solvent capable of dissolving or dispersing the resin, and can be appropriately selected according to the purpose. For example, volatile solvents with a boiling point of less than 150°C are preferred in terms of ease of removal. Examples include 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, and methyl isobutyl ketone. Among these, toluene, xylene, benzene, methylene chloride, 1,2-dichloroethane, chloroform, and carbon tetrachloride are preferred, and ethyl acetate is particularly preferred because it has a low boiling point, is easy to distill from mixed solutions, and minimizes azeotrope with other materials. These may be used individually or in combination of two or more. There are no particular restrictions on the amount of the organic solvent used, and it can be appropriately selected depending on the purpose. For example, 40 to 300 parts by mass, more preferably 60 to 140 parts by mass, and even more preferably 80 to 120 parts by mass, per 100 parts by mass of the resin fine particles. The concentration of the organic solvent can be measured, for example, by a gas chromatograph-mass spectrometer.

[0065] The aqueous medium contains at least water and may further contain a solvent miscible with water. The solvent miscible with water is not particularly limited as long as it is miscible with water, and examples include alcohols, dimethylformamide, tetrahydrofuran, cellosolves, and lower ketones. Examples of alcohols include methanol, isopropanol, and ethylene glycol. Examples of lower ketones include acetone and methyl ethyl ketone. These may be used individually or in combination of two or more.

[0066] Examples of the aforementioned surfactants include anionic surfactants, cationic surfactants, nonionic surfactants, and amphoteric surfactants.

[0067] Examples of the anionic surfactant include alkylbenzene sulfonates (sodium dodecyldiphenyl ether disulfonate), α-olefin sulfonates, phosphate esters, etc., and those having a fluoroalkyl group are preferred. Examples of anionic surfactants having a fluoroalkyl group include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms or their metal salts, disodium perfluorooctanesulfonyl glutamate, sodium 3-[omega-fluoroalkyl (carbon 6 to 11) oxy]-1-alkyl (carbon 3 to 4) sulfonate, sodium 3-[omega-fluoroalkanoyl (carbon 6 to 8)-N-ethylamino]-1-propanesulfonate, fluoroalkyl (carbon 11 to 20) carboxylic acids or their metal salts, perfluoroalkyl Examples include perfluorocarboxylic acids (7-13 carbon atoms) or their metal salts, perfluoroalkyl (4-12 carbon atoms) sulfonic acids or their metal salts, perfluorooctanesulfonic acid diethanolamide, N-propyl-N-(2-hydroxyethyl)perfluorooctanesulfonamide, perfluoroalkyl (6-10 carbon atoms) sulfonamide propyltrimethylammonium salt, perfluoroalkyl (6-10 carbon atoms)-N-ethylsulfonylglycine salt, and monoperfluoroalkyl (6-16 carbon atoms) ethyl phosphate esters. Examples of commercially available surfactants having the fluoroalkyl group include Surflon S-111, S-112, S-113 (manufactured by Asahi Glass Co., Ltd.); Florad FC-93, FC-95, FC-98, FC-129 (manufactured by Sumitomo 3M Co., Ltd.); Unidyne DS-101, DS-102 (manufactured by Daikin Industries, Ltd.); Megafac F-110, F-120, F-113, F-191, F-812, F-833 (manufactured by Dainippon Ink and Chemicals, Inc.); Extop EF-102, 103, 104, 105, 112, 123A, 123B, 306A, 501, 201, 204 (manufactured by Tochem Products Co., Ltd.); and Futergent F-100, F150 (manufactured by Neos Co., Ltd.).

[0068] Examples of the cationic surfactants include amine salt type surfactants and quaternary ammonium salt type cationic surfactants. Examples of the amine salt type surfactants include alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazoline. Examples of the quaternary ammonium salt type cationic surfactants include alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride. Among these cationic surfactants, examples include aliphatic primary, secondary, or tertiary amine acids having a fluoroalkyl group, aliphatic quaternary ammonium salts such as perfluoroalkyl (6 to 10 carbon atoms) sulfonamidopropyltrimethylammonium salt, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts. Examples of commercially available cationic surfactants include Surflon S-121 (manufactured by Asahi Glass Co., Ltd.), Florad FC-135 (manufactured by Sumitomo 3M Co., Ltd.), Unidyne DS-202 (manufactured by Daikin Industries, Ltd.), Megafac F-150, F-824 (manufactured by Dainippon Ink and Chemicals, Inc.), Extop EF-132 (manufactured by Tochem Products Inc.), and Futergent F-300 (manufactured by Neos Corporation).

[0069] Examples of the nonionic surfactant include fatty acid amide derivatives and polyhydric alcohol derivatives.

[0070] Examples of the aforementioned amphoteric surfactants include alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, and N-alkyl-N,N-dimethylammonium betaine.

[0071] These may be used individually or in combination of two or more. Among these, sodium dodecyldiphenyl ether disulfonate is particularly preferred due to its ease of granulation of resin fine particles from the resin and other materials, and its dispersibility in resin dispersions. The surfactant content can be measured, for example, by liquid chromatography-mass spectrometry.

[0072] The mass ratio of the resin to the surfactant is 1:1 to 1:2, and preferably 1:1.3 to 1:1.7. In the above mass ratio, if the mass ratio of surfactant to 1 part by mass of resin is less than 1 part by mass, resin microparticles with poor granulation and deteriorated surface properties will be mixed in, causing resin microparticles to form on the reaction vessel wall and reducing the yield when recovering the resin microparticles. In the above mass ratio, if the mass ratio of surfactant to 1 part by mass of resin exceeds 2 parts by mass, the surfactant will cover the surface of the resin microparticles, making granulation of the resin microparticles impossible, resulting in clumps with a particle size exceeding 30 μm that cannot be discharged from the reaction vessel.

[0073] The resin dispersion is preferably prepared by dispersing the resin in the aqueous medium while stirring. There are no particular restrictions on the dispersion method, and a known stirrer, disperser, etc., can be appropriately selected. Examples of such stirrers include a self-supporting type with a movable stirring tank, a suspended type with a fixed stirring tank, and a tank mixer type in which the stirring tank and drive unit are integrated. Among these, a suspended type heat transfer accelerating stirrer with a fixed stirring tank is preferred because it can control the particle size of the resin fine particles (oil droplets) to 10 μm to 30 μm and can maintain a constant heat transfer area on the reaction tank wall.

[0074] When using this heat transfer-enhancing type agitator, there are no particular restrictions on conditions such as rotation speed, stirring time, and stirring temperature, and these can be appropriately selected according to the purpose. For example, the rotation speed can be 0.1 rpm to 1,000 rpm (i.e., 1.118 × 10) for a rotation radius of 1 mm to 10,000 mm. -8 A range of ×g to 11,180×g is preferred, and for a turning radius of 10mm to 5,000mm, the rotation speed is 1rpm to 500rpm (i.e., 1118×10 -5A ratio of 89.44 × g to 1397.5 × g is more preferable, and a rotation speed of 200 rpm to 300 rpm (i.e., 89.44 × g to 301.86 × g) is even more preferable for a turning radius of 2,000 mm to 3,000 mm. The stirring time is preferably 0.1 minutes to 1,440 minutes (24 hours) in the case of a batch system. The stirring temperature is preferably 0°C to 150°C under pressure, and more preferably 40°C to 98°C.

[0075] Examples of the aforementioned dispersers include low-speed shear dispersers, high-speed shear dispersers, friction dispersers, high-pressure jet dispersers, and ultrasonic dispersers. Among these, high-speed shear dispersers are preferred because they can control the particle size of the resin fine particles (oil droplets) to 10 μm to 30 μm. When using the high-speed shear disperser, there are no particular restrictions on conditions such as rotation speed, dispersion time, and dispersion temperature, and these can be appropriately selected according to the purpose. For example, the rotation speed is preferably 1,000 rpm to 30,000 rpm, and more preferably 5,000 rpm to 20,000 rpm. The dispersion time is preferably 0.1 minutes to 5 minutes in the case of a batch system. The dispersion temperature is preferably 0°C to 150°C under pressure, and more preferably 40°C to 98°C. Generally, higher stirring temperatures and dispersion temperatures facilitate dispersion.

[0076] As an example of a method for producing the resin fine particles, a method for obtaining resin fine particles by generating the adhesive substrate in particulate form is shown below. In the method for granulating resin fine particles by generating the adhesive substrate in particulate form, for example, preparation of an aqueous medium phase, preparation of the oil phase, preparation of the resin dispersion, addition of the aqueous medium, and other steps (synthesis of a polymer (prepolymer) that can react with the active hydrogen group-containing compound, synthesis of the active hydrogen group-containing compound, etc.) are performed.

[0077] The aqueous medium phase can be prepared, for example, by dispersing the resin in the aqueous medium. The amount of resin added to the aqueous medium can be appropriately selected depending on the purpose. The mixed solution can be prepared by dissolving or dispersing materials such as the active hydrogen group-containing compound, the polymer reactable with the active hydrogen group-containing compound, the colorant, the mold release agent, the charge control agent, and the unmodified polyester resin in the organic solvent. In addition, among the resin fine particle material, components other than the polymer (prepolymer) reactable with the active hydrogen group-containing compound may be added and mixed into the aqueous medium when dispersing the resin fine particles in the aqueous medium during the preparation of the aqueous medium phase, or they may be added to the aqueous medium phase together with the mixed solution when adding the mixed solution containing the resin fine particles to the aqueous medium phase.

[0078] The resin dispersion can be prepared by emulsifying or dispersing the previously prepared oil phase in the previously prepared aqueous medium phase. During this emulsification or dispersion, the active hydrogen group-containing compound and a polymer reactive with the active hydrogen group-containing compound undergo an extension reaction or crosslinking reaction to generate the adhesive substrate.

[0079] The adhesive substrate (for example, the urea-modified polyester resin) may be produced by, for example, (1) emulsifying or dispersing an oil phase containing a polymer reactable with the active hydrogen group-containing compound (for example, the isocyanate group-containing polyester prepolymer (A)) together with the active hydrogen group-containing compound (for example, the amines (B)) in an aqueous medium phase to form a dispersion, and then causing an extension reaction or crosslinking reaction between the two in the aqueous medium phase; (2) emulsifying or dispersing the oil phase in an aqueous medium to which the active hydrogen group-containing compound has been previously added to form a dispersion, and then causing an extension reaction or crosslinking reaction between the two in the aqueous medium phase; or (3) adding and mixing the mixed solution in the aqueous medium, then adding the active hydrogen group-containing compound to form a dispersion, and then causing an extension reaction or crosslinking reaction between the two from the particle interface in the aqueous medium phase. In the case of (3), the modified polyester resin is preferentially formed on the surface of the resin microparticles, and a concentration gradient can be provided in the resin microparticles.

[0080] The reaction conditions for producing the adhesive substrate by the emulsification or dispersion described above are not particularly limited and can be appropriately selected depending on the combination of the polymer that can react with the active hydrogen group-containing compound and the active hydrogen group-containing compound. The reaction time is preferably 10 minutes to 40 hours, more preferably 2 hours to 24 hours, and the reaction temperature is preferably 0°C to 150°C, more preferably 40°C to 98°C.

[0081] A method for stably forming the dispersion containing a polymer (for example, the isocyanate group-containing polyester prepolymer (A)) that can react with the active hydrogen group-containing compound in the aqueous medium phase is to add the mixed solution, prepared by dissolving or dispersing the polymer (for example, the isocyanate group-containing polyester prepolymer (A)), the colorant, the mold release agent, the charge control agent, and the resin fine particle material such as the unmodified polyester resin in the organic solvent, to the aqueous medium phase and disperse by shear force. Details of the dispersion method are as described above.

[0082] The concentration of the surfactant on the surface of the resin microparticles can be measured by the following method.

[0083] <Measurement of surfactant concentration on the surface of resin microparticles> 0.1 g of resin fine particles are mixed with 10 mL of methanol and subjected to ultrasonic irradiation for 30 minutes. The dispersion after ultrasonic irradiation is filtered through a 2 μm mesh filter to obtain a surfactant extract. The obtained surfactant extract is used as the measurement sample. The measurement sample is analyzed using the surfactant as a standard under the following analytical conditions by the absolute calibration curve method. The surfactant concentration is determined from the maximum peak detected in the measurement sample. <Analysis conditions> • Measuring device: LCMS-8030 (manufactured by Shimadzu Corporation) • Column: InertSustain® Swift C18 (particle size: 2 μm, inner diameter: 2.1 mm, length: 100 mm, manufactured by GL Sciences Co., Ltd.) Mobile phase: Solution A: 0.5 vol% ammonium acetate aqueous solution / methanol = 80% / 20% (v / v) Solution B: methanol • Gradient program: A / B = 0% / 100% (v / v) → A / B = 100% / 0% (v / v) (10 minutes, hold for 5 minutes) → A / B = 0% / 100% (v / v) (15 minutes, hold for 5 minutes) ·Flow rate: 0.3mL / min ·Injection volume: 0.2μL

[0084] The concentration of surfactant on the surface of the resin microparticles obtained by the above method is not particularly limited, but is preferably 500 ppm to 1,000 ppm, and more preferably 700 ppm to 800 ppm. When the concentration of surfactant on the surface of the resin microparticles is 500 ppm or higher, aggregation of particles due to contact with each other is less likely to occur, and granulation to the desired particle size becomes possible. Furthermore, when the concentration of surfactant on the surface of the resin microparticles is 1,000 ppm or lower, it is possible to prevent a decrease in the function of the resin microparticles due to the effects of the hygroscopicity of the surfactant, etc., which can occur when an excess of surfactant is present.

[0085] In preparing the resin dispersion, dispersants other than surfactants may be used as needed. There are no particular restrictions on the dispersants other than surfactants; they can be appropriately selected depending on the purpose. Examples include poorly water-soluble inorganic compound dispersants, polymer-based protective colloids, and the like. These may be used individually or in combination of two or more.

[0086] Examples of poorly water-soluble inorganic compound dispersants include tricalcium phosphate, calcium carbonate, titanium dioxide, colloidal silica, and hydroxyapatite. Examples of polymeric protective colloids include acids, (meth)acrylic monomers containing hydroxyl groups, vinyl alcohol or ethers of vinyl alcohol, esters of vinyl alcohol and compounds containing carboxyl groups, amide compounds or methylol compounds thereof, chlorides, homopolymers or copolymers having a nitrogen atom or its heterocycle, polyoxyethylenes, celluloses, etc. Examples of acids include acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid, and maleic anhydride. Examples of the (meth)acrylic monomers containing the hydroxyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, β-hydroxypropyl acrylate, β-hydroxypropyl methacrylate, γ-hydroxypropyl acrylate, γ-hydroxypropyl methacrylate, 3-chloro-2-hydroxypropyl acrylate, 3-chloro-2-hydroxypropyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerin monoacrylate, glycerin monomethacrylate, N-methylolacrylamide, and N-methylolmethacrylamide. Examples of the vinyl alcohol or ethers of vinyl alcohol include vinyl methyl ether, vinyl ethyl ether, and vinyl propyl ether. Examples of esters of vinyl alcohol and compounds containing a carboxyl group include vinyl acetate, vinyl propionate, and vinyl butyrate. Examples of the amide compounds or methylol compounds thereof include acrylamide, methacrylamide, diacetoneacrylamide, or methylol compounds thereof. Examples of the aforementioned chlorides include acrylate chloride and methacrylate chloride.Examples of homopolymers or copolymers having a nitrogen atom or its heterocycle include vinylpyridine, vinylpyrrolidone, vinylimidazole, and ethyleneimine. Examples of polyoxyethylene-based materials include polyoxyethylene, polyoxypropylene, polyoxyethylene alkylamine, polyoxypropylene alkylamine, polyoxyethylene alkylamide, polyoxypropylene alkylamide, polyoxyethylene nonylphenyl ether, polyoxyethylene laurylphenyl ether, polyoxyethylene stearylphenyl ester, and polyoxyethylene nonylphenyl ester. Examples of cellulose-based materials include methylcellulose, hydroxyethylcellulose, and hydroxypropylcellulose.

[0087] In preparing the resin dispersion, a dispersion stabilizer may be used as needed. Examples of such dispersion stabilizers include those soluble in acids and alkalis, such as calcium phosphate. When such a dispersion stabilizer is used, the calcium phosphate can be removed from the fine particles by dissolving it with an acid such as hydrochloric acid and then washing with water, or by decomposition using enzymes.

[0088] In preparing the resin dispersion, the catalyst for the extension reaction or the crosslinking reaction can be used. Examples of such catalysts include dibutyltin laurate and dioctyltin laurate.

[0089] <Distillation Process> In the distillation process, the organic solvent is removed from the resin dispersion by distillation.

[0090] In this invention, removing the organic solvent means that the concentration of the organic solvent in the resin dispersion is less than 0.1% by mass. The residual organic solvent concentration in the resin dispersion is measured by gas chromatography (GC) under the analytical conditions described in the examples.

[0091] The removal of organic solvents is preferably carried out under at least one of the following conditions: reduced pressure and heating. This increases the evaporation rate of the organic solvent, improving productivity, and also allows for control of the particle size of resin microparticles by manipulating the evaporation rate through the degree of reduced pressure. Furthermore, since resins may be soluble in organic solvents, rapidly removing the organic solvent by reduced pressure suppresses the fusion of resins and prevents damage to the surface quality of the resin microparticles. The heating is preferably carried out by passing either hot air or steam from a heat pump through a jacket provided on the outer circumference of the distillation tank, or by heating the storage tank containing the organic solvent with a heater. Among these, hot air from a heat pump is particularly preferred due to its temperature stability and the ability to reduce CO2 emissions.

[0092] Any known container equipped with a stirrer and a heating element (jacket or heater) for heating the container wall can be used to remove the organic solvent from the resin dispersion. However, considering the efficient removal of organic solvents, a container with a heat pump connected to the heating element, a vacuum system, or the ability to blow in compressed air or nitrogen is preferred.

[0093] In the removed organic solvent, the surfactant concentration is preferably 0.1 ppm to 300 ppm, and more preferably 0.1 ppm to 10 ppm. Below 0.1 ppm, the purification process for components other than the organic solvent may span multiple steps, which is preferable in terms of the amount of organic solvent recovered and the recovery cost. Above 300 ppm, it is undesirable because the hygroscopicity of the organic solvent surfactant can lead to a decrease in the functionality of the organic solvent.

[0094] The concentration of the surfactant in the organic solvent can be measured by the following method.

[0095] <Measurement of surfactant concentration in organic solvents> 0.5 g of organic solvent is mixed with 10 mL of methanol, and ultrasonic irradiation is performed for 30 minutes to prepare the sample for measurement. The sample for measurement is analyzed using the surfactant as a standard, under the following analytical conditions, by the absolute calibration curve method. The concentration of the surfactant in the organic solvent is determined from the maximum peak detected in the sample for measurement. <Analysis conditions> • Measuring device: LCMS-8030 (manufactured by Shimadzu Corporation) • Column: InertSustain® Swift C18 (particle size: 2 μm, inner diameter: 2.1 μm, length: 100 μm, manufactured by GL Sciences Co., Ltd.) Mobile phase: Solution A: 0.5 vol% ammonium acetate aqueous solution / methanol = 80% / 20% (v / v) Solution B: methanol • Gradient program: A / B = 0% / 100% (v / v) → A / B = 100% / 0% (v / v) (10 minutes, hold for 5 minutes) → A / B = 0% / 100% (v / v) (15 minutes, hold for 5 minutes) ·Flow rate: 0.3mL / min ·Injection volume: 0.2μL

[0096] Once the organic solvent is removed, resin fine particles are obtained. These resin fine particles can be washed, dried, and further classified as desired. This classification can be performed, for example, by removing the fine particles in a liquid using a cyclone, decanter, or centrifugation, or the classification operation may be performed after obtaining the powder after drying.

[0097] In this way, the resin fine particles obtained can be mixed with particles such as the colorant, release agent, and charge control agent, and further, by applying a mechanical impact force, it is possible to prevent the release agent and other particles from detaching from the surface of the resin fine particles. Examples of methods for applying the mechanical impact force include applying an impact force to the mixture with a blade rotating at high speed, and introducing the mixture into a high-speed airflow to accelerate it and cause the particles or composite particles to collide with a suitable impact plate. Examples of equipment used in this method include an Ongmill (manufactured by Hosokawa Micron Corporation), a modified I-type mill (manufactured by Nippon Pneumatics Co., Ltd.) with reduced grinding air pressure, a hybridization system (manufactured by Nara Machine Works), a Cryptron system (manufactured by Kawasaki Heavy Industries, Ltd.), and an automatic mortar and pestle.

[0098] The resin fine particles preferably have the following characteristics: volume average particle diameter (Dv), volume average particle diameter (Dv) / number average particle diameter (Dn), average circularity, etc.

[0099] The particle size of the resin microparticles is a characteristic value that defines the granulation properties. The volume-average particle size and the ratio of the volume-average particle size to the number-average particle size (Dv / Dn) can be measured, for example, using a Beckman Coulter Multisizer 4e particle size analyzer. Specifically, 0.1 ml to 5 ml of alkylbenzene sulfonate surfactant is added to 100 ml to 150 ml of ISOTON-II electrolyte (Beckman Coulter), then 2 mg to 20 mg of resin microparticles are added and dispersed for approximately 1 to 3 minutes using an ultrasonic disperser. Next, the volume-average particle size of the resin microparticles is determined using a 100 μm aperture in a Multisizer 4e precision particle size distribution analyzer (Beckman Coulter). Here, 13 channels are used, with particle sizes ranging from 2.00 μm to less than 2.52 μm; 2.52 μm to less than 3.17 μm; 3.17 μm to less than 4.00 μm; 4.00 μm to less than 5.04 μm; 5.04 μm to less than 6.35 μm; 6.35 μm to less than 8.00 μm; 8.00 μm to less than 10.08 μm; 10.08 μm to less than 12.70 μm; 12.70 μm to less than 16.00 μm; 16.00 μm to less than 20.20 μm; 20.20 μm to less than 25.40 μm; 25.40 μm to less than 32.00 μm; and 32.00 μm to less than 40.30 μm.

[0100] The volume-average particle size (Dv) of the resin fine particles is preferably 10 μm or more and 30 μm or less, more preferably 15 μm or more and 25 μm or less, and even more preferably 17 μm or more and 23 μm or less. If the volume-average particle size is 10 μm or more, it leads to an improvement in yield by improving the recovery rate when the resin fine particles are recovered. If the volume-average particle size is 30 μm or less, it is possible to prevent a decrease in yield due to adhesion to the container wall.

[0101] The ratio (Dv / Dn) of the volume-average particle diameter (Dv) to the number-average particle diameter (Dn) in the resin fine particles is preferably 1.25 or less, more preferably 1.00 to 1.20, and even more preferably 1.10 to 1.20. When the ratio (Dv / Dn) of the volume-average particle diameter to the number-average particle diameter is 1.25 or less, the particle size distribution of the resin fine particles is relatively sharp, and the yield is improved. When the ratio (Dv / Dn) is 1.00 or more, it is possible to prevent the resin fine particles from fusing to the container wall during long-term stirring, which would reduce the yield, and when it is 1.20 or less, it is possible to suitably obtain high-resolution and high-quality images when used as toner.

[0102] The average circularity is the value obtained by dividing the circumference of an equivalent circle with the same shape and projected area as the resin fine particles by the circumference of the actual particles, and is preferably 0.94 to 0.99, and more preferably 0.95 to 0.98. It is preferable that 15% or less of the particles have an average circularity of less than 0.94. If the average circularity is less than 0.94, the resin fine particles may fuse to the container wall during long-term stirring, reducing the yield. The average circularity can be measured, for example, by an optical detection band method in which a suspension containing resin fine particles is passed through an imaging detection band on a flat plate, and the particle image is optically detected and analyzed with a CCD camera. For example, it can be measured using a flow-type particle image analyzer FPIA-2100 (manufactured by Sysmex Corporation).

[0103] (Distillation apparatus) The distillation apparatus of the present invention is a distillation apparatus for removing an organic solvent from a resin dispersion containing an organic solvent, water, a resin, and a surfactant by distillation, and comprises a distillation tank and a heating unit, and may further comprise other components as needed.

[0104] The distillation apparatus of the present invention will be described with reference to Figure 1. Figure 1 is a schematic diagram showing an example of the configuration of a distillation apparatus according to one embodiment of the present invention. The distillation apparatus 1 comprises a distillation tank 10, a stirrer 11, a heating unit 20, a heat pump 21, a heating control unit 22, a condenser 31, a recovery container 32, a vacuum pump 33, a pressure control unit 34, and the like. The distillation apparatus 1 removes an organic solvent from a resin dispersion containing an organic solvent, water, resin, and a surfactant by distillation.

[0105] The distillation tank 10 is a container for holding a resin dispersion and performing distillation. A jacket-shaped heating section 20 is provided on the outer circumference of the distillation tank 10, which can heat the walls of the distillation tank 10, thereby heating the resin dispersion contained within. The distillation tank 10 is also connected to a vacuum pump 33 through piping and a condenser 31, and the inside of the distillation tank 10 can be depressurized by driving the vacuum pump 33. Distillation may be performed by heating by the heating section 20 and depressurization by the vacuum pump 33, or by performing both.

[0106] The agitator 11 stirs the resin dispersion contained in the distillation tank 10 by the rotation of a stirring blade 11a fixed to the tip of the stirring shaft. In Figure 1, a paddle blade is shown as an example of a stirring blade 11a, but there are no particular restrictions on the shape of the stirring blade 11a, and it can be appropriately selected according to the viscosity of the resin dispersion, etc. Examples include turbine blades, propeller blades, ribbon blades, anchor blades, etc.

[0107] The heating unit 20 is connected to the heat pump 21, and by passing hot air through the jacket, the walls of the distillation tank 10 can be heated. Heating with hot air from the heat pump 21 has the advantage of making it easier to stabilize the temperature inside the distillation tank 10 and reducing CO2 emissions.

[0108] The heat pump 21 is connected to the heating control unit 22 and its operation is controlled according to signals from the heating control unit 22. The heating control unit 22 monitors the temperature inside the distillation tank 10 and can change the temperature inside the distillation tank 10 in stages by controlling the operation of the heat pump 21.

[0109] By driving the vacuum pump 33 to reduce the pressure inside the distillation tank 10, the volatile components contained in the resin dispersion vaporize and reach the condenser 31 through the piping. The condenser 31 is equipped with a cooling mechanism, and the vaporized volatile components condense upon cooling. The condensed volatile components are then collected in a recovery container 32 located below.

[0110] The vacuum pump 33 is connected to the pressure control unit 34, and its operation is controlled according to signals from the pressure control unit 34. The pressure control unit 34 monitors the pressure inside the distillation tank 10 and can change the pressure inside the distillation tank 10 in steps by controlling the operation of the vacuum pump 33.

[0111] The distillation apparatus 1 allows for gradual changes in the internal temperature of the distillation tank 10, enabling rapid distillation while avoiding bumping.

[0112] (toner) The toner of the present invention contains the resin fine particles of the present invention, and may further contain other components commonly used in toners, if necessary.

[0113] There are no particular restrictions on the content of resin microparticles in the toner; the toner itself may consist of resin microparticles.

[0114] Because the toner of the present invention contains the resin fine particles of the present invention, it can improve image density stability. [Examples]

[0115] The embodiments of the present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the embodiments shown below.

[0116] <Synthesis of polyester resin A1> In a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, 690 parts by mass of bisphenol A ethylene oxide 2 molar adduct and 335 parts by mass of terephthalic acid were added, and a condensation reaction was carried out at 210°C for 10 hours under atmospheric pressure and a nitrogen stream. Next, the reaction was continued for 5 hours under reduced pressure of 10 mmHg to 15 mmHg while dehydrating, and then cooled to obtain [Polyester Resin A1]. The weight-average molecular weight of the obtained [Polyester Resin A1] was 6,000, the acid value was 10 mgKOH / g, and the glass transition temperature was 48°C.

[0117] The acid value of polyester resin A1 was measured according to the method specified in JIS K0070:1992. The solvent used for measuring the acid value was a mixed solvent of acetone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), methanol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and toluene (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) (acetone:methanol:toluene = 12.5:12.5:75 (volume ratio)). The weight-average molecular weight of polyester resin A1 was measured by the aforementioned GPC.

[0118] The glass transition temperature of polyester resin A1 was measured using a DSC system (differential scanning calorimeter) according to the following procedure. 5.0 mg of polyester resin A1 was placed in an aluminum sample container, which was then placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, it was heated from -80°C to 150°C at a heating rate of 10°C / min (first heating). Subsequently, it was cooled from 150°C to -80°C at a cooling rate of 10°C / min, and then heated again to 150°C at a heating rate of 10°C / min (second heating). For both the first and second heating cycles, a DSC curve was measured using a differential scanning calorimeter (Q-200, TA Instruments Inc.). From the obtained DSC curves, the DSC curve for the first heating cycle was selected using the analysis program in the Q-200 system, and the glass transition temperature of polyester resin A1 at the first heating cycle was determined. Similarly, the DSC curve during the second heating cycle was selected, and the glass transition temperature of polyester resin A1 during the second heating cycle was determined. The glass transition temperature (Tg) of polyester resin A1 represents the glass transition temperature during the second heating cycle.

[0119] <Synthesis of Styrene Acrylic Resin A2> In a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet tube, 160 parts by mass of N,N-dimethylformamide was added under atmospheric pressure and a nitrogen stream, and the liquid temperature was heated to 90°C. While maintaining the liquid temperature at 90°C, 190 parts by mass of styrene monomer was added, followed by 10 parts by mass of acrylonitrile. In a separate container, a mixture of 0.8 g of azobisisobutyronitrile and 40 g of N,N-dimethylformamide was added dropwise over 10 hours using a titration funnel. From there, the condensation reaction was carried out while maintaining the liquid temperature at 90°C and stirring for 2 hours. Next, the reaction was continued for 2 hours under reduced pressure of 10 mmHg to 15 mmHg while dehydrating, and then cooled to obtain [styrene-acrylic resin A2]. The weight-average molecular weight of the obtained [styrene-acrylic resin A2] was 5,500. The weight-average molecular weight of styrene-acrylic resin A2 was measured by the GPC method described above.

[0120] <Synthesis of Prepolymer B> In a reaction vessel equipped with a condenser, a stirrer, and a nitrogen inlet, 795 parts by mass of a 2-mol bisphenol A ethylene oxide adduct made from polyester, 200 parts by mass of isophthalic acid, 65 parts by mass of terephthalic acid, and 2 parts by mass of dibutyltin oxide were added, and a condensation reaction was carried out at 210°C for 8 hours under atmospheric pressure and a nitrogen stream. Next, the reaction was continued for 5 hours under reduced pressure of 10 mmHg to 15 mmHg while dehydrating, and then cooled to 80°C. The mixture was then reacted with 170 parts by mass of isophorone diisocyanate in ethyl acetate for 2 hours to obtain [prepolymer B]. The weight-average molecular weight of the obtained [prepolymer B] was 5,000. The weight-average molecular weight of prepolymer B was measured by the GPC method described above.

[0121] (Example 1) <Preparation of the oil phase> In the reaction vessel, 170 parts by mass of ethyl acetate dispersion of 35% by mass carnauba wax, 120 parts by mass of [polyester resin A1], 20 parts by mass of CIPY155 (yellow pigment, manufactured by Clariant), 70 parts by mass of ethyl acetate, 2 parts by mass of isophorone diamine, 25 parts by mass of [prepolymer B], and 25 parts by mass of ethyl acetate were added, and the mixture was stirred for 4 hours to dissolve and mix, yielding [oil phase 1] containing an organic solvent and resin.

[0122] <Preparation of aqueous media phase> In a separate reaction vessel, 945 parts by mass of water, 40 parts by mass of a 20% aqueous dispersion of styrene-methacrylate-butyl acrylate copolymer, 435 parts by mass of a 50% aqueous dispersion of N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant), and 90 parts by mass of ethyl acetate were added and mixed and stirred to obtain [Aqueous Medium Phase 1].

[0123] <Preparation of resin dispersion> Next, [Aqueous medium phase 1] was added to [Oil phase 1], and continuous stirring was performed for 2 hours at a rotation speed of 250 rpm using a fixed-tank, suspended, heat-transfer-accelerating type agitator (rotation radius 2,500 mm) to disperse resin fine particles in the aqueous medium. This process prepared [Resin dispersion 1] containing an organic solvent, water, resin, and surfactant.

[0124] <Distillation Process> The obtained [resin dispersion 1] was placed into the distillation tank 10 of the distillation apparatus 1 having the configuration shown in Figure 1. The tank walls were heated with hot air from a heat pump 21, and distillation was performed under reduced pressure conditions of -90kPa, gradually reducing the pressure while avoiding bumping, with a turning radius of 2,500mm, a stirring speed of 250rpm, and a jacket temperature of 40°C for the heating section 20. Here, the organic solvent concentration before the start of distillation was used as the starting point. The organic solvent concentration was determined by measuring the residual organic solvent concentration in [resin dispersion 1] at regular intervals using gas chromatography (GC-2010, Shimadzu Corporation) according to the measurement method described below. The organic solvent concentration at the starting point was 18.8% by mass. Finally, distillation was carried out continuously for 2 hours until the organic solvent concentration in [resin dispersion 1] was less than 0.1% by mass, and the organic solvent was removed from [resin dispersion 1].

[0125] <Method for measuring residual organic solvent concentration> The residual organic solvent concentration was measured by gas chromatography (GC) under the following conditions, and calculated using a calibration curve method from the obtained peak area values. Here, the residual organic solvent concentration represents the ratio (mass%) of the organic solvent to the mass of the sample [resin dispersion 1], specifically the mass of ethyl acetate in Example 1. Under the following conditions, a peak was observed at approximately 2.8 min for ethyl acetate. -Analysis conditions- • Measuring device: GC-2010 (manufactured by Shimadzu Corporation) • Detector: Flame ionization detector (FID) • Column: DB-WAX column (length 30m, inner diameter 0.530mm, film thickness: 1.00μm, manufactured by Agilent Technologies) • Column temperature: After injection at a constant temperature of around 50°C, it was maintained for 5 minutes, then the temperature was increased at 10°C per minute to 180°C, and maintained at 180°C for 5 minutes. ·Inlet temperature: 200℃ Detector temperature: 200℃ Carrier gas: Helium Column pressure: 3.1 psi

[0126] <Recovery of resin microparticles> Subsequently, the [resin dispersion 1] from which the organic solvent had been removed was filtered, washed, and dried. It was then classified into fine powder (F powder) less than 10 μm (Elbow Jet Classifier EJ-150, manufactured by Matsubo Co., Ltd.), fine powder (M powder) between 10 μm and 30 μm (G powder), and coarse powder (G powder) greater than 30 μm, and the fine resin particles were recovered.

[0127] The obtained resin fine particles were analyzed using the method described above to determine the volume-average particle size, the surfactant concentration on the surface, and the intensity ratio (P 2850 / P 828 ) Average value, intensity ratio (P 2850 / P 828 The percentage of samples with a ratio of 0.40 or higher, and the yield were calculated. In addition, the surfactant concentration in the organic solvent recovered during the distillation process was calculated.

[0128] (Example 2) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant), and the organic solvent was changed from ethyl acetate to methyl ethyl ketone.

[0129] (Example 3) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant), and polyester resin A1 was changed to styrene acrylic resin A2.

[0130] (Example 4) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant) and wall heating was not performed in the distillation process.

[0131] (Example 5) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant) and no reduced pressure was applied during the distillation process.

[0132] (Example 6) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant), and the wall surface was heated with steam instead of hot air from a heat pump.

[0133] (Example 7) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant).

[0134] (Comparative Example 1) Resin fine particles were obtained in the same manner as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant), and the amount of surfactant added was changed from 217.5 parts by mass to 43.5 parts by mass.

[0135] (Comparative Example 2) The procedure was the same as in Example 1, except that the surfactant was changed from N-alkyl-N,N-dimethylammonium betaine (amphoteric surfactant) to sodium dodecyldiphenyl ether disulfonate (negative surfactant), and the amount of surfactant added was changed from 217.5 parts by mass to 507.5 parts by mass. However, in Comparative Example 2, resin fine particles could not be obtained due to poor granulation.

[0136] Table 1 shows the composition of the resin fine particles and the distillation process for Examples 1-7 and Comparative Examples 1-2. In Table 1, EA represents ethyl acetate and MEK represents methyl ethyl ketone.

[0137] [Table 1]

[0138] The methods for producing resin fine particles in the examples and comparative examples were evaluated based on the following criteria. The evaluation results are shown in Table 2.

[0139] <Granulation property> The volume-average particle size of the obtained resin microparticles was evaluated according to the following criteria. △, ○, and ◎ were considered acceptable. [Evaluation Criteria] ◎: 17μm or more and 23μm or less. ○: 15 μm or more and less than 17 μm, or greater than 23 μm and 25 μm or less. △: 10 μm or more and less than 15 μm, or greater than 25 μm and 30 μm or less. ×: Less than 10 μm or greater than 30 μm (including cases where measurement is not possible).

[0140] <Recyclability of organic solvents> The surfactant concentration in the organic solvent recovered during the distillation process was evaluated according to the following criteria. △, ○, and ◎ were considered acceptable. [Evaluation Criteria] ◎: 10ppm or less. ○: Higher than 10 ppm and below 100 ppm. △: Higher than 100 ppm and below 300 ppm. ×: Higher than 300 ppm.

[0141] <Wall mounting> The walls of the distillation tanks were visually inspected after the distillation process was completed and evaluated according to the following criteria. △, ○, and ◎ were considered passing grades. [Evaluation Criteria] ◎: There is almost no residue adhering to the walls of the distillation tank. ○: A small amount of deposit is present on the wall of the distillation tank. △: A deposit is adhering to the wall of the distillation tank as a surface. ×: Solid deposits are adhering to the wall of the distillation tank, creating an uneven surface.

[0142] <Yield> The yield of the obtained resin fine particles was evaluated according to the following criteria. △, ○, and ◎ were considered acceptable. [Evaluation Criteria] ◎: 98% or higher. ○: 90% or more but less than 98%. △: 75% or more but less than 90%. ×: Less than 75%.

[0143] [Table 2]

[0144] The results shown in Table 2 indicate that the resin microparticle manufacturing methods of Examples 1 to 7, with a resin-to-surfactant mass ratio of 1:1 to 1:2, can suppress the adhesion of resin microparticles to the container wall due to poor granulation and the inclusion of resin microparticles with deteriorated surface properties. Furthermore, the resin microparticle manufacturing methods of Examples 1 to 7 also have the advantage of high recyclability of the organic solvent recovered by distillation and low environmental impact. On the other hand, in the resin microparticle manufacturing methods of Comparative Examples 1 and 2, the mass ratio of resin to surfactant was not in the range of 1:1 to 1:2, resulting in poor granulation of the resin microparticles or the inclusion of resin microparticles with deteriorated surface properties, which led to problems with the resin microparticles adhering to the container walls.

[0145] Next, the suitability of the resin microparticles in the examples and comparative examples was evaluated based on the following items. The evaluation results are shown in Table 3. Note that the applications of the resin microparticles are not particularly limited, and the present invention is not limited to the examples shown below.

[0146] <Granulation property> The volume-average particle size of the obtained resin microparticles was evaluated according to the following criteria. △, ○, and ◎ were considered acceptable. [Evaluation Criteria] ◎: 17μm or more and 23μm or less. ○: 15 μm or more and less than 17 μm, or greater than 23 μm and 25 μm or less. △: 10 μm or more and less than 15 μm, or greater than 25 μm and 30 μm or less. ×: Less than 10 μm or greater than 30 μm (including cases where measurement is not possible).

[0147] <Surfactant concentration on the surface of resin microparticles> The surfactant concentration on the surface of the obtained resin microparticles was evaluated according to the following criteria. △, ○, and ◎ were considered acceptable. [Evaluation Criteria] ◎: 700 ppm to 800 ppm. ○: 600 ppm or more but less than 700 ppm, or higher than 800 ppm but 900 ppm or less. △: 500 ppm or more but less than 600 ppm, or higher than 900 ppm but 1,000 ppm or less. ×: Less than 500 ppm or greater than 1,000 ppm.

[0148] <Average amount of surface release agent> Analysis of the obtained resin nanoparticles using FTIR-ATR (Total Reflectance Absorption Infrared Spectroscopy) revealed that at wavenumber 828 cm⁻¹, -1 The intensity of the absorption spectral peak P 828 For a wave number of 2,850 cm -1 The intensity of the absorption spectral peak P 2850 The intensity ratio (P 2850 / P 828 The average value of ) was calculated and evaluated according to the following criteria: Intensity ratio (P 2850 / P 828 The average value of ) is for an infrared incident angle of 41.5° and a resolution of 4cm. -1 Measurements were taken 20 times for cumulative measurement, and then the average was calculated from 100 measurements. △, ○, and ◎ were considered passing grades. [Evaluation Criteria] ◎: Strength ratio (P 2850 / P 828 The average value of ) is between 0.27 and 0.33. 〇: Intensity ratio (P 2850 / P 828 The average value of ) is 0.25 or higher but less than 0.27, or greater than 0.33 and 0.35 or lower. △: Intensity ratio (P 2850 / P 828 The average value of ) is 0.20 or higher but less than 0.25, or greater than 0.35 but 0.40 or lower. ×: Intensity ratio (P 2850 / P 828 The average value of ) is less than 0.20 or greater than 0.40.

[0149] <Amount (percentage) of surface release agent> The obtained resin fine particles were analyzed using FTIR-ATR (Total Reflectance Absorption Infrared Spectroscopy) and the results of 100 measurements were obtained, and the intensity ratio (P 2850 / P 828 The percentage of those with a score of 0.40 or higher was calculated and evaluated according to the following criteria. △, ○, and ◎ were considered passing grades. [Evaluation Criteria] ◎: Strength ratio (P 2850 / P 828 The percentage of those with a score of 0.40 or higher is between 27% and 33%. 〇: Intensity ratio (P 2850 / P 828 The percentage of people whose score is 0.40 or higher is 20% or more but less than 27%, or more than 33% but 40% or less. △: Intensity ratio (P 2850 / P 828 The percentage of people whose ratio is 0.40 or higher is 10% or more but less than 20%, or more than 40% but 50% or less. ×: Intensity ratio (P 2850 / P 828 The percentage of those with a score of 0.40 or higher is less than 10%, or more than 50%.

[0150] <Overall Rating> As resin microparticles, the following criteria were used to evaluate their versatility, considering their suitability for various applications, based on granulation properties (being fine particles) and their ability to function as a resin (having minimal component imbalance and easy mixing with other constituent materials). △, ○, and ◎ were considered passing grades. [Evaluation Criteria] ◎: Suitable for a wide range of applications. ○: While some usage restrictions are necessary, it is generally suitable. △: The range of suitability is limited, but within acceptable limits. ×: Not compatible.

[0151] [Table 3]

[0152] The results shown in Table 3 indicate that the resin microparticles obtained in Examples 1 to 7 exceeded the acceptance criteria in all aspects, including volume-average particle size, surface surfactant concentration, and release agent amount, demonstrating their high versatility. On the other hand, in Comparative Examples 1 and 2, all items fell below the passing criteria, indicating that the resin microparticles were not highly versatile.

[0153] The embodiments of the present invention are, for example, as follows. <1> A resin dispersion preparation step involves preparing a resin dispersion containing an organic solvent, water, resin, and surfactant. A distillation step to remove the organic solvent from the resin dispersion by distillation, Includes, The present invention relates to a method for producing resin fine particles, characterized in that the mass ratio of the resin to the surfactant in the resin dispersion is 1:1 to 1:2. <2> The resin fine particles are characterized in that their volume-average particle size is 10 μm or more and 30 μm or less. <1> This is a method for producing resin fine particles as described above. <3> The surfactant is characterized by being sodium dodecyldiphenyl ether disulfonate. <1> from <2> This is a method for producing resin fine particles as described in any one of the items. <4> The aforementioned organic solvent is characterized by containing ethyl acetate. <1> from <3> This is a method for producing resin fine particles as described in any one of the items. <5> Resin microparticles containing resin, a colorant, a release agent, and a surfactant, The aforementioned resin contains polyester resin, The volume-average particle size of the resin fine particles is 10 μm or more and 30 μm or less. The concentration of the surfactant on the surface of the resin fine particles is 500 ppm or more and 1,000 ppm or less. FTIR-ATR mapping, wavenumber 828cm -1 The intensity of the absorption spectral peak P 828 For a wave number of 2,850 cm -1 The intensity of the absorption spectral peak P 2850 The intensity ratio (P 2850 / P 828 The average value of ) is between 0.20 and 0.40, The intensity ratio (P 2850 / P 828 The resin fine particles are characterized in that the proportion of those with a ratio of 0.40 or higher is 10% to 50%. <6> The aforementioned <5> This toner contains the resin microparticles described above. <7> A distillation apparatus for removing an organic solvent from a resin dispersion containing an organic solvent, water, a resin, and a surfactant by distillation, The apparatus comprises a distillation tank for containing the resin dispersion and a heating unit for heating the wall surface of the distillation tank, The heating unit is capable of gradually changing the temperature inside the distillation tank. The distillation apparatus is characterized in that the heating section is connected to a heat pump. [Explanation of symbols]

[0154] 1. Distillation apparatus 10 distillation tanks 11. Agitator 11a Agitator blade 20 Heating section 21 Heat pump 22 Heating control unit 31 Condenser 32 Collection containers 33 Vacuum pump 34 Pressure Control Unit [Prior art documents] [Patent Documents]

[0155] [Patent Document 1] Japanese Patent Publication No. 2022-150039 [Patent Document 2] Japanese Patent Application Publication No. 10-137503 [Patent Document 3] Japanese Patent Publication No. 2015-175950

Claims

1. A resin dispersion preparation step involves preparing a resin dispersion containing an organic solvent, water, resin, and surfactant. A distillation step to remove the organic solvent from the resin dispersion by distillation, Includes, A method for producing resin fine particles, characterized in that the mass ratio of the resin to the surfactant in the resin dispersion is 1:1 to 1:

2.

2. The method for producing resin fine particles according to claim 1, characterized in that the volume-average particle diameter of the resin fine particles is 10 μm or more and 30 μm or less.

3. The method for producing resin fine particles according to claim 1, characterized in that the surfactant is sodium dodecyldiphenyl ether disulfonate.

4. The method for producing resin fine particles according to claim 1, characterized in that the organic solvent contains ethyl acetate.

5. Resin microparticles containing resin, a colorant, a release agent, and a surfactant, The aforementioned resin contains polyester resin, The volume-average particle diameter of the resin fine particles is 10 μm or more and 30 μm or less. The concentration of the surfactant on the surface of the resin fine particles is 500 ppm or more and 1,000 ppm or less. FTIR-ATR mapping, wavenumber 828 cm －１ The intensity of the absorption spectral peak P ８２８ For a wavenumber of 2,850 cm －１ The intensity of the absorption spectral peak P ２８５０ The intensity ratio (P ２８５０ / P ８２８ The average value of ) is between 0.20 and 0.40, The intensity ratio (P ２８５０ / P ８２８ Resin fine particles characterized in that the proportion of those with a ratio of 0.40 or higher is 10% or more and 50% or less.

6. Toner containing resin fine particles as described in claim 5.

7. A distillation apparatus for removing an organic solvent from a resin dispersion containing an organic solvent, water, a resin, and a surfactant by distillation, The apparatus comprises a distillation tank for containing the resin dispersion and a heating unit for heating the wall surface of the distillation tank, The heating unit is capable of gradually changing the temperature inside the distillation tank. The distillation apparatus is characterized in that the heating section is connected to a heat pump.

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