Method for producing a resin particle dispersion, and method for producing toner particles

Abstract

To provide a method for producing a resin particle dispersion that has a low environmental impact and suppresses the generation of coarse particles. [Solution] a) A step of preparing an oil phase by dissolving a binder resin containing at least polyethylene terephthalate or polybutylene terephthalate in an organic solvent, b) A step of adding a neutralizing agent to the oil phase of step a to prepare a neutralizing agent mixture, c) The process includes adding water to the neutralizing agent mixture in step b and performing phase inversion emulsification to obtain a resin particle dispersion, The stirring conditions during the mixing of the neutralizing agent in step b above are as follows: Using a rotating stirring blade, satisfying the following equation, TIFF2026055991000008.tif27169 A method for producing a resin particle dispersion, characterized by stirring under the aforementioned stirring conditions for at least 5 minutes after adding a neutralizing agent.

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin particle dispersion and a method for producing toner. [Background technology]

[0002] To reduce the environmental impact of toner used in image forming devices such as multifunction printers (MFPs) and printers, various measures are being considered, such as reducing power consumption by improving the low-temperature fixing properties of the toner itself, reducing the energy used in the toner manufacturing process, and using recycled resins for the binder resin. For example, Patent Document 1 proposes a toner resin using polyethylene terephthalate, which is a recycled resin, from the viewpoint of effective resource utilization.

[0003] Another method for reducing the amount of chemicals used in toner manufacturing is the phase inversion emulsification method, which can reduce the amount of surfactants. Patent Document 2 discloses a method for producing a resin particle dispersion, comprising the steps of: neutralizing a resin by adding a neutralizing agent to a resin solution obtained by dissolving a resin having an acid value in an organic solvent; adding an aqueous medium to emulsify the resin in phase to obtain a phase-inverted emulsion; and removing the organic solvent from the phase-inverted emulsion, wherein the maximum stirring power value when stirring the resin solution after adding the aqueous medium to obtain the phase-inverted emulsion is 0.4 W or more and 20 W or less per unit mass (kg) of resin. [Overview of the project] [Problems that the invention aims to solve]

[0004] One aspect of the present invention aims to provide a method for producing a resin particle dispersion that uses a resin with low environmental impact and suppresses the generation of coarse particles. [Means for solving the problem]

[0005] A method for producing a resin particle dispersion according to one aspect of the present invention, which solves the above problems, is: a) A step of preparing an oil phase by dissolving a binder resin containing at least polyethylene terephthalate or polybutylene terephthalate in an organic solvent, b) A step of adding a neutralizing agent to the oil phase of step a to prepare a neutralizing agent mixture, c) The process includes adding water to the neutralizing agent mixture in step b and performing phase inversion emulsification to obtain a resin particle dispersion, The stirring conditions during the mixing of the neutralizing agent in step b above are as follows:

number

[0006] One aspect of the present invention provides a resin particle dispersion that uses a resin with a low environmental impact and suppresses the generation of coarse particles. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram showing an example of a stirring tank using anchor blades, which is suitably used in a method for producing a resin particle dispersion according to an embodiment of the present invention. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described in detail below. However, the embodiments are not limited by the following description and can be modified as appropriate without departing from the spirit of the invention. Furthermore, in this specification, the "~" indicating a numerical range means that the values ​​before and after it are included as the lower and upper limits, respectively, unless otherwise specified.

[0009] The present invention is a method for producing a resin particle dispersion, comprising the following steps. a) A step of preparing an oil phase by dissolving a binder resin containing at least polyethylene terephthalate or polybutylene terephthalate in an organic solvent, b) A step of adding a neutralizing agent to the oil phase in step a) to prepare a neutralizing agent mixture; c) A step of adding water to the neutralizing agent mixture in step b) to perform phase inversion emulsification to obtain a resin particle dispersion liquid, including; The stirring condition during the mixing of the neutralizing agent in step b) uses a rotary stirring blade. [Number] That is, it is stirred under the stirring condition for at least 5 minutes after the addition of the neutralizing agent. The details will be described below.

[0010] (Method for manufacturing a neutralizing agent mixture) As one factor for the generation of coarse particles in phase inversion emulsification, if the neutralization treatment is insufficient, the mixing of the oil phase and the water phase becomes insufficient, and it is considered that the particle size variation becomes large and coarse particles are generated. Regarding the large variation in particle size and the generation of coarse particles, it has been found that by setting the stirring condition to [Number] for at least 5 minutes after the addition of the neutralizing agent, the insufficiency of the mixing of the oil phase and the water phase can be improved.

[0011] In addition, regarding the viscosity of the neutralizing agent mixture, by appropriately adjusting it, the balance between the aggregation of resin particles due to shear force and the disintegration of aggregated particles is controlled, and the sharpness of the particle size distribution of the resin particles can be further improved.

[0012] [Neutralizing agent] In the oil phase preparation step, after dissolving the masterbatch in an organic solvent to obtain an oil phase, the oil phase is neutralized with an alkaline aqueous solution. The neutralizing agent is not particularly limited, and examples include aqueous ammonia solution, sodium hydroxide, etc. By neutralizing the oil phase, the water dispersibility of the resin is improved, and the advantage of facilitating phase inversion emulsification is obtained.

[0013] [Neutralization rate] The neutralization rate is calculated by measuring the actual acid value of the polyester before neutralization and adding the required amount of base in molar ratio to that acid value to achieve the desired neutralization rate. Here, the acid value refers to the number of milligrams of potassium hydroxide required to neutralize 1 gram of resin. Furthermore, in the production of resin particle dispersions, the particle size distribution of the resin particles is controlled by adjusting the neutralization rate according to the physical properties of the resin. For this reason, it is preferable that the neutralization rate in the oil phase preparation process be 30% or higher.

[0014] <Agitator> There are no particular restrictions on the agitator in the mixing tank, but for example, paddle blades, anchor blades, helical ribbon blades, screw blades, MAXBLEND (manufactured by Sumitomo Heavy Industries Process Equipment Co., Ltd.), Supermix (manufactured by Satake Chemical Machinery Industry Co., Ltd.), and Fullzone (manufactured by Kobe Steel Environmental Solutions Co., Ltd.) can be used.

[0015] <Agitator blade diameter> The impeller converts the rotational energy from the motor into two actions: a "discharge action" that forms a circulating flow throughout the tank, and a "shear action" that provides localized shear force. The impeller diameter is the diameter of the impeller, that is, the maximum diameter that lies perpendicular to the drive shaft.

[0016] Figure 1 is a schematic diagram showing an example of a stirred tank configuration when anchor blades are used as stirring blades. 1 represents the rotating shaft, 2 represents the impeller, 3 represents the agitated tank, and D represents the diameter of the impeller.

[0017] <Binding resin> The binder resin contains polyethylene terephthalate (PET) or polybutylene terephthalate (PBT). There are no particular restrictions on PET or PBT, and they can be appropriately selected depending on the purpose. For example, recycled materials, off-spec fiber waste, or pellets can be used, but from the standpoint of reducing environmental impact, it is preferable to use recycled materials (hereinafter sometimes referred to as "recycled resin") that have been processed into flake form.

[0018] There are no particular restrictions on the weight-average molecular weight (Mw) of PET or PBT, and it can be appropriately selected depending on the purpose, but 30,000 to 100,000 is preferred.

[0019] The analytical method and calculation method for the PET or PBT content in resin particles are not particularly limited, and general methods for calculating the amount of PET can be used. As an analytical method and calculation method for the PET or PBT content, for example, the components can be separated from the resin particles by gel permeation chromatography (GPC), and the mass ratio of the constituent components of the resin particles can be calculated by using the analytical methods described below for each separated component.

[0020] Furthermore, quantitative analysis can also be performed by estimating the main components from the soft decomposition of ester bonds in resin particles by methylation using gas chromatography-mass spectrometry (GC / MS) at 300°C with a reaction reagent (10% tetramethylammonium hydroxide (TMAH) / methanol solution), and by drawing a calibration curve of total ion current chromatogram (TICC) intensity.

[0021] The separation of each component by GPC can be performed, for example, by the following method. In GPC measurements using tetrahydrofuran (THF) as the mobile phase, the eluate is separated using a fraction collector or similar device, and the fraction corresponding to the desired molecular weight portion of the total integral of the elution curve is collected.

[0022] After concentrating and drying the collected eluate using an evaporator or the like, the solid components are dissolved in a deuterated solvent such as deuterated chloroform or deuterated THF, and 1H-NMR measurements are performed. The ratio of constituent monomers of the resin in the eluted components is calculated from the integral ratio of each element.

[0023] Another method involves concentrating the eluate, hydrolyzing it with sodium hydroxide or the like, and then qualitatively and quantitatively analyzing the decomposition products using high-performance liquid chromatography (HPLC) or similar methods to calculate the constituent monomer ratios.

[0024] There are no particular restrictions on the content of PET or PBT, and it can be appropriately selected depending on the purpose, but it is preferably 5 to 70 parts by mass, and more preferably 10 to 50 parts by mass, per 100 parts by mass of resin particles. If the content of PET or PBT is 70 parts by mass or less per 100 parts by mass of resin particles, low-temperature fixation properties can be achieved. If the content of PET or PBT is 5 parts by mass or more per 100 parts by mass of resin particles, the effect of reducing environmental impact can be achieved, and the resin particles can have an excellent particle size distribution. When the content of PET or PBT is within the above more preferred range, it is advantageous in that it can achieve both a reduction in the environmental impact of the resin particles and an improvement in the particle size distribution.

[0025] This section details an example of a method for separating the various components contained in resin particles when analyzing them. First, 1 g of resin particles is placed in 100 mL of THF, and a solution is obtained by stirring for 30 minutes at 25°C until the soluble components are dissolved. The solution is filtered through a membrane filter with a mesh size of 0.2 μm to obtain the THF-soluble components in the resin particles. Next, this is dissolved in THF to prepare a sample for GPC measurement and injected into the GPC used for molecular weight measurement of each resin as described above. Meanwhile, a fraction collector is placed at the eluate outlet of the GPC, and the eluate is collected at predetermined count intervals, obtaining eluate at 5% area percentage intervals from the start of elution (rise of the curve) on the elution curve. Next, for each eluate, 30 mg of the sample is dissolved in 1 mL of deuterated chloroform, and 0.05 volume% of tetramethylsilane (TMS) is added as a reference substance. The solution is packed into a 5 mm diameter glass tube for NMR measurement, and a nuclear magnetic resonance spectrometer (JEOL Ltd. JNM-AL400) is used to perform 128 integrations at a temperature of 23°C to 25°C to obtain the spectrum. The monomer composition and proportions of PET resin and other materials contained in the resin particles can be determined from the peak integration ratio of the obtained spectrum.

[0026] Therefore, the resin particles can reduce environmental impact and have an excellent particle size distribution.

[0027] As described above, the resin particles preferably contain at least one of amorphous resin, amorphous resin, and crystalline resin in addition to PET or PBT, and more preferably contain amorphous resin, amorphous resin, and crystalline resin.

[0028] The total content of PET or PBT relative to the total mass of resin particles is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. A resin ratio of 30% by mass or more of recycled PET and PBT in the resin particles indicates a high level of environmental friendliness.

[0029] In addition to PET or PBT, it is preferable to include at least one of amorphous resins, amorphous resins, and crystalline resins. Examples include polystyrene, styrene-acrylic copolymer, polyvinyl chloride, polyvinyl acetate, polymethacrylate, methyl polyacrylate, polyacrylic acid ester, polyacrylonitrile, epoxy resin, polyethylene, polyurethane, polyester, polyethylene terephthalate, polyamide, paraffin wax, etc. These may be used individually or in combination. From the viewpoint of obtaining good fixation properties, polyester resin is preferred.

[0030] <Polyester resin> When used as a toner for developing electrostatic latent images in electrophotography, good fixation can be obtained by using a resin having a polyester backbone. Examples of resins having a polyester backbone include polyester resin and block polymers of polyester and other resins having a backbone. Among these, the use of polyester resin is preferred because it improves the uniformity of the resulting colored resin particles.

[0031] Examples of polyester resins include ring-opening polymers of lactones, condensation polymers of hydroxycarboxylic acids, and polycondensates of polyol (1) and polycarboxylic acid (2). From the viewpoint of design flexibility, polycondensates of polyol and polycarboxylic acid are preferred.

[0032] The weight-average molecular weight of polyester resin is typically 1,000 to 30,000, preferably 3,000 to 15,000, and more preferably 5,000 to 12,000. Below 1,000, heat resistance may deteriorate, and above 30,000, good low-temperature fixation may not be obtained.

[0033] The glass transition temperature (Tg) of the polyester resin is preferably 35 to 80°C, more preferably 40 to 70°C, and even more preferably 45 to 65°C. Below 35°C, the resulting colored resin particles may deform or stick together when exposed to high-temperature environments such as midsummer, potentially preventing them from behaving as intended. Above 80°C, good fixation may not be achieved.

[0034] -Polyol- Polyol (1) includes diols (1-1) and polyols with a valentity of 3 or more (1-2). Examples include (1-1) alone, or a mixture of (1-1) and a small amount of (1-2).

[0035] Examples of diols (1-1) include alkylene glycols (ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, etc.); alkylene ether glycols (diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, etc.); alicyclic diols (1,4-cyclohexanedimethanol, hydrogenated bisphenol A, etc.); bisphenols (bisphenol A, bisphenol F, bisphenol S, etc.); alkylene oxide adducts (ethylene oxide, propylene oxide, butylene oxide, etc.) of the above alicyclic diols; 3,3'-difluoro-4,4'-dihydroxyb Examples include phenyl and other 4,4'-dihydroxybiphenyls; bis(hydroxyphenyl)alkanes such as bis(3-fluoro-4-hydroxyphenyl)methane, 1-phenyl-1,1-bis(3-fluoro-4-hydroxyphenyl)ethane, 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, 2,2-bis(3,5-difluoro-4-hydroxyphenyl)propane (also known as tetrafluorobisphenol A), and 2,2-bis(3-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane; bis(4-hydroxyphenyl) ethers such as bis(3-fluoro-4-hydroxyphenyl) ethers; and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above bisphenols.

[0036] Of these, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, with particular preference being alkylene oxide adducts of bisphenols and combinations thereof with alkylene glycols having 2 to 12 carbon atoms.

[0037] Examples of polyols with a valency of 3 or higher (1-2) include polyhydric aliphatic alcohols with a valency of 3 to 8 or higher (glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, sorbitol, etc.); phenols with a valency of 3 or higher (trisphenol PA, phenol novolac, cresol novolac, etc.); and alkylene oxide adducts of the above polyphenols with a valency of 3 or higher.

[0038] -Polycarboxylic acid- Examples of polycarboxylic acid (2) include dicarboxylic acid (2-1) and polycarboxylic acid (2-2) with a valentity of 3 or more. (2-1) alone or a mixture of (2-1) and a small amount of (2-2) is preferred.

[0039] Dicarboxylic acids (2-1) include alkylenedicarboxylic acids (succinic acid, adipic acid, sebacic acid, etc.); alkenylenedicarboxylic acids (maleic acid, fumaric acid, etc.); aromatic dicarboxylic acids (phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, etc.), 3-fluoroisophthalic acid, 2-fluoroisophthalic acid, 2-fluoroterephthalic acid, 2,4,5,6-tetrafluoroisophthalic acid, 2,3,5,6-tetrafluoroterephthalic acid, and 5-trifluoro Examples include methyl isophthalic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 2,2-bis(3-carboxyphenyl)hexafluoropropane, 2,2'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 3,3'-bis(trifluoromethyl)-4,4'-biphenyldicarboxylic acid, 2,2'-bis(trifluoromethyl)-3,3'-biphenyldicarboxylic acid, and hexafluoroisopropylidene diphthalic anhydride. Of these, preferred are alkenylenedicarboxylic acids having 4 to 20 carbon atoms and aromatic dicarboxylic acids having 8 to 20 carbon atoms.

[0040] Examples of polycarboxylic acids with a valency of 3 or higher (2-2) include aromatic polycarboxylic acids with 9 to 20 carbon atoms (such as trimellitic acid and pyromellitic acid).

[0041] Furthermore, as the polycarboxylic acid (2), an acid anhydride or a lower alkyl ester (such as a methyl ester, ethyl ester, or isopropyl ester) of the above-mentioned polycarboxylic acid may be reacted with the polyol (1).

[0042] The ratio of polyol to polycarboxylic acid is typically 2 / 1 to 1 / 2, preferably 1.5 / 1 to 1 / 1.5, and more preferably 1.3 / 1 to 1 / 1.3, expressed as the equivalent ratio of hydroxyl groups [OH] to carboxyl groups [COOH] [OH] / [COOH].

[0043] To efficiently refine the material, it is preferable that the rotor peripheral speed exceeds 12 m / s for fine dispersion by shearing. Furthermore, for crushing by impact, it is preferable that the disc peripheral speed be 6 m / s or higher, and more preferably 10 m / s to 12 m / s. In crushing by impact, if the disc peripheral speed is less than 6 m / s, sufficient crushing energy from impact cannot be obtained, and uneven distribution of beads occurs, resulting in insufficient dispersion. Conversely, if the disc peripheral speed is increased too much, there is a risk of increased liquid temperature and re-aggregation due to over-dispersion.

[0044] <Coloring agent> Known dyes and pigments can be used as colorants in the present invention, for example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, yellow ochre, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), permanent yellow (NCG), Vulcan fast yellow (5G, R), tartrazine lake, quinoline yellow lake, anthrazane yellow BGL, etc. Soindrinon Yellow, Bengara, Red Lead, Red Lead, Cadmium Red, Cadmium Mercury Red, Antimony Red, Permanent Red 4R, Para Red, Faise Red, Parachlor-Orthonitroaniline Red, Risol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Risol Rubin GX, Permanent Red F5R, Brillia Bon Maroon 6B, Pogment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake, Rhodamine Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oil Red, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinon Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkali Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal-free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine, Prussian Blue, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Chromium Oxide, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Acid Green Lake,Malachite green lake, phthalocyanine green, anthraquinone green, titanium dioxide, zinc oxide, lithobone, and mixtures thereof can be used.

[0045] Regarding the coloring agent, a masterbatch may be prepared by kneading the coloring agent with the resin, and then dissolving or dispersing it together with the binder resin in an organic solvent to prepare an oil phase.

[0046] The resin used in the preparation of the masterbatch can be selected as appropriate, but it is preferable that it is soluble in organic solvents and insoluble or practically insoluble in water. Examples of resins that can be used include polystyrene, styrene-acrylic copolymer, polyvinyl chloride, polyvinyl acetate, polymethacrylate, methyl polyacrylate, polyacrylic acid ester, polyacrylonitrile, epoxy resin, polyethylene, polyurethane, polyester, polyethylene terephthalate, polyamide, paraffin wax, etc. These may be used individually or in combination. From the viewpoint of obtaining good fixation properties, polyester resin is preferred.

[0047] The masterbatch can be prepared by kneading the above-mentioned colorant and resin. For example, general kneaders such as twin-screw extruders, three-roll kneaders, and lab blast mills can be used for the kneading process. Internal additives may also be added during the kneading process. Heating is preferable during kneading, and the heating conditions can be set as appropriate.

[0048] The ratio of resin to colorant in the preparation of the masterbatch can be selected as appropriate.

[0049] To ensure constant-temperature fixation, crystalline polyester may be dissolved in the oil phase.

[0050] <Crystalline polyester resin> Crystalline polyester resins are obtained from polyhydric alcohols and polyhydric acids or their derivatives, such as polyhydric carboxylic acids, polyhydric carboxylic acid anhydrides, and polyhydric carboxylic acid esters.

[0051] In this invention, crystalline polyester resin refers to a resin obtained using a polyhydric alcohol and a polyhydric carboxylic acid such as a polyhydric carboxylic acid, polyhydric carboxylic acid anhydride, or polyhydric carboxylic acid ester, or a derivative thereof, as described above. Modified polyester resins, such as prepolymers, and resins obtained by crosslinking and / or stretching the prepolymer are not included in the definition of crystalline polyester resin.

[0052] -Polyhydric alcohols- There are no particular restrictions on the polyhydric alcohols, and they can be appropriately selected depending on the purpose. Examples include diols and alcohols with a hydride of three or more.

[0053] Examples of the diol include saturated aliphatic diols. Examples of saturated aliphatic diols include linear saturated aliphatic diols and branched saturated aliphatic diols, but among these, linear saturated aliphatic diols are preferred, and linear saturated aliphatic diols with 2 to 12 carbon atoms are more preferred. If the saturated aliphatic diol is branched, the crystallinity of the crystalline polyester resin may decrease, and the melting point may decrease. Furthermore, if the number of carbon atoms in the saturated aliphatic diol exceeds 12, it becomes difficult to obtain practical materials.

[0054] Examples of saturated aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosandecanediol. Among these, ethylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol are preferred because they exhibit high crystallinity in the crystalline polyester resin and excellent sharp-melt properties.

[0055] Examples of trivalent or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. These may be used individually or in combination of two or more.

[0056] -Polyhydric carboxylic acids- There are no particular restrictions on the polycarboxylic acid, and it can be appropriately selected depending on the purpose. Examples include divalent carboxylic acids and trivalent or higher carboxylic acids.

[0057] Examples of the aforementioned divalent carboxylic acids include saturated aliphatic dicarboxylic acids such as oxalic acid, succinic acid, glutaric acid, adipic acid, superiric acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, and mesaconic acid; and moreover, their anhydrides and lower (1-3 carbon atoms) alkyl esters.

[0058] Examples of the carboxylic acids with a valency of 3 or higher include 1,2,4-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, and their anhydrides and lower (1-3 carbon atoms) alkyl esters. These may be used individually or in combination of two or more types.

[0059] The crystalline polyester resin is preferably composed of a linear saturated aliphatic dicarboxylic acid having 4 to 12 carbon atoms and a linear saturated aliphatic diol having 2 to 12 carbon atoms. This results in high crystallinity and excellent sharp melt properties, enabling excellent low-temperature fixation.

[0060] Furthermore, methods for controlling the crystallinity and softening point of crystalline polyester resins include designing and using nonlinear polyesters produced by condensation polymerization by adding trivalent or higher polyhydric alcohols such as glycerin to the alcohol component during polyester synthesis, or trivalent or higher polycarboxylic acids such as trimellitic anhydride to the acid component.

[0061] The molecular structure of the crystalline polyester resin in this embodiment can be confirmed by NMR measurements in solution and solid state, as well as by X-ray diffraction, GC / MS, LC / MS, IR measurements, etc. A simpler method is infrared absorption spectroscopy, which can be used to determine the molecular structure at 965±10 cm⁻¹. -1 Alternatively, 990±10cm -1 δ of olefin CH Examples include systems that have absorption based on (out-of-plane angular bending vibration).

[0062] Regarding molecular weight, after careful consideration, it was found that a sharp molecular weight distribution and low molecular weight components exhibit excellent low-temperature fixation, while a high proportion of low molecular weight components worsen heat-resistant storage. As a result, the following is preferable: In the molecular weight distribution of the soluble components of o-dichlorobenzene by GPC, the peak position of the molecular weight distribution graph, with log(M) on the x-axis and weight% on the y-axis, is in the range of 3.5 to 4.0, the full width at half maximum of the peak is 1.5 or less, the weight-average molecular weight (Mw) is preferably 3,000 to 30,000, the number-average molecular weight (Mn) is preferably 1,000 to 10,000, and the Mw / Mn ratio is preferably 1 to 10. Furthermore, it is preferable that the weight-average molecular weight (Mw) is 5,000 to 15,000, the number-average molecular weight (Mn) is preferably 2,000 to 10,000, and the Mw / Mn ratio is preferably 1 to 5.

[0063] From the viewpoint of affinity between paper and resin, the acid value of crystalline polyester resin is preferably 5 mg KOH / g or higher in order to achieve the desired low-temperature fixation properties. Furthermore, for the production of fine particles by the phase inversion emulsification method, it is more preferable that the acid value be 7 mg KOH / g or higher. On the other hand, to improve hot offset properties, it is preferable that the acid value be 45 mg KOH / g or lower. In addition, for the hydroxyl value of crystalline polymer, it is preferably 0 to 50 mg KOH / g, and more preferably 5 to 50 mg KOH / g, in order to achieve the predetermined low-temperature fixation properties and good electrostatic properties.

[0064] <Release agent> Wax can be used as a release agent. There are no particular restrictions on the wax, and it can be appropriately selected depending on the purpose, but a low-melting-point release agent with a melting point of 50°C to 120°C is preferred. The low-melting-point release agent, when dispersed with the resin, works effectively as a release agent between the fixing roller and the toner interface, thereby providing good hot offset even in an oil-free (no release agent such as oil is applied to the fixing roller) environment.

[0065] Suitable release agents include, for example, waxes and other waxes. Examples of waxes and other waxes include natural waxes such as carnauba wax, cotton wax, wood wax, and rice wax; animal waxes such as beeswax and lanolin; mineral waxes such as ozokerite and cerucine; and petroleum waxes such as paraffin, microcrystalline, and petrolatum. In addition to these natural waxes, synthetic hydrocarbon waxes such as Fischer-Tropsch wax and polyethylene wax, and synthetic waxes such as esters, ketones, and ethers can also be used. Furthermore, fatty acid amides such as 12-hydroxystearic acid amide, stearic acid amide, phthalic anhydride, and chlorinated hydrocarbons; homopolymers or copolymers of polyacrylates such as poly-n-stearyl methacrylate and poly-n-lauryl methacrylate, which are low molecular weight crystalline polymer resins (for example, copolymers of n-stearyl acrylate and ethyl methacrylate); and crystalline polymers having long alkyl groups in their side chains may also be used. These may be used individually or in combination of two or more types.

[0066] There are no particular restrictions on the melting point of the wax, and it can be appropriately selected depending on the purpose, but 50°C to 120°C is preferred, and 60°C to 90°C is more preferred. If the melting point is 50°C or higher, it is possible to prevent the wax from adversely affecting its heat resistance during storage, and if it is 120°C or lower, it is possible to effectively prevent the problem of cold offset occurring during fixing at low temperatures.

[0067] The melt viscosity of the wax is preferably 5 cps to 1,000 cps, and more preferably 10 cps to 100 cps, measured at a temperature 20°C higher than the melting point of the wax. If the melt viscosity is 5 cps or higher, a decrease in release properties can be prevented, and if it is 1,000 cps or lower, the effects of hot offset resistance and low-temperature fixing can be fully exhibited.

[0068] There are no particular restrictions on the wax content in the toner, 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 is 40% by mass or less, deterioration of the toner's fluidity can be prevented.

[0069] (Oil phase) The oil phase is prepared by dissolving the binder resin in an organic solvent. In addition to the above, colorants and other substances may be used in the oil phase.

[0070] The oil phase can be prepared by gradually adding resins, colorants, etc., to an organic solvent while stirring, and dissolving or dispersing them. Known methods can be used for dispersion, such as dispersers like bead mills or disc mills.

[0071] The organic solvent can be selected as appropriate, and for example, a volatile organic solvent with a boiling point of less than 100°C is preferred because it can be easily removed in a later step. Examples of such organic solvents 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, methyl isobutyl ketone, methanol, ethanol, and isopropyl alcohol. These can be used individually or in combination of two or more.

[0072] When the resin to be dissolved or dispersed in an organic solvent is a resin having a polyester skeleton, it is preferable to use an ester-based solvent such as methyl acetate, ethyl acetate, or butyl acetate, or a ketone-based solvent such as methyl ethyl ketone or methyl isobutyl ketone. In this case, solubility can be increased. Among these, methyl acetate, ethyl acetate, and methyl ethyl ketone are more preferable due to their high solvent removal properties. Among these, using ethyl acetate as the organic solvent is even more preferable because it improves the selectivity of materials when preparing the masterbatch or oil phase.

[0073] (Phase inversion emulsification) In phase inversion emulsification, an aqueous medium is added to the dissolution to perform phase inversion emulsification and produce an oil-in-water dispersion. By adding an aqueous phase to the dissolution and inverting the phase from a water-in-oil dispersion to an oil-in-water dispersion, it becomes possible to reduce the amount of surfactant used in granulation.

[0074] The aqueous medium is not particularly limited as long as phase inversion emulsification occurs, and can be appropriately selected depending on the purpose. Examples include water, a solvent miscible with water, and mixtures thereof. These may be used individually or in combination of two or more. Among these, water is preferred. The solvent miscible with water is not particularly limited as long as phase inversion emulsification occurs, and can be appropriately selected depending on the purpose. 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.

[0075] (Solvent removal) In this embodiment, desolvation may be performed during phase inversion emulsification. The desolvation step may be included in the emulsification phase inversion step, or it may be performed separately.

[0076] To remove organic solvents from oil-in-water dispersions (also called particulate dispersions or colored particulate dispersions), one method is to gradually increase the temperature while stirring the entire system, thereby evaporating and removing the organic solvent from the droplets. Alternatively, the resulting colored particulate dispersion can be sprayed into a dry atmosphere while stirring to completely remove the organic solvent from the droplets. Another method involves reducing the pressure while stirring the colored particulate dispersion, thereby evaporating and removing the organic solvent. The latter two methods can also be used in combination with the first method.

[0077] The drying atmosphere in which the colored particulate dispersion is sprayed generally consists of various gases heated to a temperature above the boiling point of the maximum boiling point solvent used, such as air, nitrogen, carbon dioxide, or combustion gas. With such methods, the desired quality can be obtained with short processing times using a spray dryer, belt dryer, rotary kiln, etc.

[0078] (agglomeration) In this embodiment, flocculation may be performed. In flocculation, the oil-in-water dispersion is flocculated after the phase inversion emulsification. For example, the particle size can be adjusted to any desired size by flocculating the oil-in-water dispersion while stirring. In the flocculation process, methods such as adding a flocculant or adjusting the pH can be used. When adding a flocculant, it may be added as is, but it is preferable to use an aqueous solution of the flocculant to avoid localized high concentrations. Furthermore, it is preferable to add the flocculating salt gradually while observing the particle size of the colored particles.

[0079] The temperature of the dispersion during aggregation is preferably near the glass transition temperature (Tg) of the resin used. If the liquid temperature is too low, aggregation will not proceed well, which may reduce efficiency. If the liquid temperature is too high, the aggregation rate will be too fast, which may lead to a deterioration of the particle size distribution, such as the generation of coarse particles.

[0080] In the coagulation process, coagulation is stopped once the target particle size is reached. Methods for stopping coagulation include adding a salt or chelating agent with a low ionic charge, adjusting the pH, lowering the temperature of the dispersion, or diluting the concentration by adding a large amount of aqueous medium. By these methods, a dispersion of colored coagulated particles can be obtained. The dispersion obtained by the coagulation process may be called a coagulated particle dispersion, a colored coagulated particle dispersion, etc. The particles in these dispersions may also be called coagulated particles, etc.

[0081] <Agglutinant> Known coagulants can be used. For example, metal salts of monovalent metals such as sodium and potassium, metal salts of divalent metals such as calcium and magnesium, and metal salts of trivalent metals such as iron and aluminum can be used. There are no particular restrictions on the amount of coagulant to be added, and it can be selected as appropriate.

[0082] (Fusion) In this embodiment, fusion bonding may be performed. In fusion bonding, the aggregated particles obtained by aggregation are fused together by heat treatment, thereby reducing irregularities. Fusion bonding can be performed by heating the dispersion of colored aggregated particles while stirring. The temperature of the liquid is preferably near the temperature exceeding the glass transition temperature Tg of the resin being used.

[0083] (Washing or drying) In this embodiment, washing or drying may be performed. Since the toner particle dispersion obtained by the above method may contain auxiliary materials such as agglutinating salts in addition to toner particles, it is preferable to wash the dispersion in order to separate only the toner particles.

[0084] Methods for washing toner particles include, for example, centrifugal separation, vacuum filtration, and filter pressing, but are not particularly limited in this invention. A cake of toner particles can be obtained by any of these methods, but if the toner particles cannot be sufficiently washed in one operation, the obtained cake may be dispersed again in an aqueous solvent to form a slurry, and the process of extracting the toner particles using one of the above methods may be repeated. Alternatively, if washing is performed by vacuum filtration or filter pressing, a method may be adopted in which the aqueous solvent is passed through the cake to wash away any auxiliary materials embedded in the colored resin particles. The aqueous solvent used for this washing can be water or a mixed solvent of water with an alcohol such as methanol or ethanol. Considering the cost and environmental impact due to wastewater treatment, it is preferable to use water.

[0085] Since the washed toner particles contain a large amount of water-based media, drying them to remove the water-based media will allow you to obtain only the toner particles. Drying methods that can be used include spray dryers, vacuum freeze dryers, reduced pressure dryers, stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers, and agitated dryers.

[0086] It is preferable to dry the dried toner particles until the moisture content is less than 1%. In addition, the colored resin particles may be soft and aggregated after drying. If this causes problems during use, the particles may be crushed and the aggregated particles may be broken up using equipment such as a jet mill, Henschel mixer, super mixer, coffee mill, Auster blender, or food processor.

[0087] (annealing) In this embodiment, annealing may be performed. When a crystalline resin is added, performing an annealing treatment after drying causes phase separation between the amorphous resin and the crystalline resin, improving the fixation properties. Specifically, storage at a temperature near the glass transition temperature Tg of the resin for 10 hours or more is sufficient.

[0088] (external attachment) In this embodiment, external additives may be used. In order to give the toner particles obtained in this embodiment fluidity, electrostatic properties, cleaning properties, etc., inorganic fine particles, polymer fine particles, cleaning aids, etc., may be added and mixed. Specific mixing methods include applying impact force to the mixture with a high-speed rotating blade, or introducing the mixture into a high-speed airflow, accelerating it, and causing the particles or composite particles to collide with a suitable impact plate.

[0089] Examples of equipment include the Ongmill (manufactured by Hosokawa Micron Corporation), a modified I-type mill (manufactured by Nippon Pneumatic Co., Ltd.) with reduced grinding air pressure, a hybridization system (manufactured by Nara Machine Works Co., Ltd.), a cryptron system (manufactured by Kawasaki Heavy Industries Co., Ltd.), and an automatic mortar and pestle.

[0090] <External additives> The primary particle size of the inorganic fine particles is preferably 5 nm to 2 μm, and particularly preferably 5 nm to 500 nm. Furthermore, the specific surface area calculated by the BET method is 20 to 500 m². 2 It is preferable that the amount is / g. The proportion of these inorganic fine particles used is preferably 0.01 to 5% by mass of the toner.

[0091] Specific examples of inorganic fine particles include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, pengala, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, and silicon nitride.

[0092] Examples of polymer-based microparticles include polymer particles made from polystyrene obtained by soap-free emulsion polymerization, suspension polymerization, or dispersion polymerization, as well as polymer particles made from polycondensation systems such as methacrylic acid esters and acrylic acid ester copolymers, silicon, benzoguanamine, and nylon, and thermosetting resins.

[0093] Such external additives can be used for surface treatment to increase hydrophobicity and prevent deterioration of flow and electrostatic properties even under high humidity conditions. For example, silane coupling agents, silylation agents, silane coupling agents having alkyl fluoride compounds, organic titanate coupling agents, aluminum coupling agents, silicone oil, and modified silicone oil are examples of preferred surface treatment agents.

[0094] In addition to the above, cleaning agents may also be used as external additives. Examples of cleaning agents for removing residual developer after transfer from the photoreceptor and primary transfer medium include fatty acid metal salts such as zinc stearate, calcium stearate, and stearic acid, as well as polymer microparticles produced by soap-free emulsion polymerization, such as polymethyl methacrylate microparticles and polystyrene microparticles. Polymer microparticles with a relatively narrow particle size distribution and a volume-average particle size of 0.01 μm to 1 μm are preferred.

[0095] (measurement) <Particle size measurement of dispersions> The particle size of the resin dispersion in this invention can be measured, for example, using a laser diffraction / scattering particle size distribution analyzer (LA-960, manufactured by Horiba, Ltd.). Specifically, the measurement method involves using a flow cell, placing the dispersion medium in the sample bath, circulating it, removing air bubbles, and adjusting the optical axis. The circulation speed is increased, and the resin microparticle dispersion is added to the sample bath so that the transmittance is in the range of 85-90%. After sonication for 5 minutes, the optical axis is adjusted again, and the measurement is performed with 10-15 data acquisitions. The particle size of the resin microparticles used was the median diameter, which corresponds to the particle size of 50% cumulatively.

[0096] <Method for measuring melting point and glass transition temperature (Tg)> The glass transition temperature Tg in this invention can be measured, for example, using a DSC system (differential scanning calorimeter) ("Q-200", manufactured by TA Instruments). Specifically, the melting point and glass transition temperature of the target sample can be measured using the following procedure. First, approximately 5.0 mg of the target sample is placed in an aluminum sample container, which is then placed on a holder unit and set in an electric furnace. Next, under a nitrogen atmosphere, the sample is heated from -80°C to 150°C at a heating rate of 10°C / min (first heating pass). After that, it is 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 pass). During both the first and second heating passes, a differential scanning calorimeter ("Q-200", manufactured by TA Instruments Inc.) is used to measure the DSC curve. From the obtained DSC curves, the analysis program in the Q-200 system can be used to select the DSC curve for the first heating cycle and determine the glass transition temperature of the target sample during the first heating cycle. Similarly, the DSC curve for the second heating cycle can be selected to determine the glass transition temperature of the target sample during the second heating cycle. In this invention, Tg refers to the glass transition temperature during the second heating step.

[0097] <Molecular weight> Unless otherwise specified, the molecular weight of the polyester resins, vinyl copolymer resins, etc. used shall be measured by GPC (gel permeation chromatography) under the following conditions. • Equipment: HLC-8220GPC (manufactured by Tosoh Corporation) • Column: TSKgel SuperHZM-Mx3 ·Temperature: 40℃ • Solvent: THF (tetrahydrofuran) ·Flow rate: 0.35mL / min • Sample: Inject 0.01 mL of a sample with a concentration of 0.05-0.6%. The weight-average molecular weight Mw is calculated from the molecular weight distribution of the toner resin measured under the above conditions, using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample. For monodisperse polystyrene standard samples, 5.8 × 10⁻⁶ 2 , 1.085 × 10 4 , 5.95×10 4 , 3.2×10 5 , 2.56 × 106 , 2.93×10 3 , 2.85×10 4 , 1.48×10 5 , 8.417×10 5 , 7.5×10 6 of these were used 10 times.

Example

[0098] Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

[0099] <Preparation of polyester resin> Into a four-necked flask equipped with a nitrogen inlet tube, a dehydrating tube, a stirrer and a thermocouple, bisphenol A ethylene oxide 2 mol adduct, bisphenol A propylene oxide 2 mol adduct, terephthalic acid and adipic acid were charged so that the molar ratio of bisphenol A propylene oxide 2 mol adduct to bisphenol A ethylene oxide 2 mol adduct was 60 / 40, the molar ratio of terephthalic acid to adipic acid was 97 / 3, and the molar ratio of hydroxyl group to carboxyl group OH / COOH was 1.3. React at normal pressure and 230 °C for 8 hours together with titanium tetraisopropoxide (500 ppm based on the resin component). After further reacting for 4 hours under a reduced pressure of 10 mmHg to 15 mmHg, trimellitic anhydride was added to the reaction vessel to be 1 mol% based on the total resin component, and reacted at 180 °C, normal pressure for 4 hours to obtain a polyester resin. The glass transition temperature (Tg) of the obtained polyester resin was 65 °C, and the weight average molecular weight (Mw) was 9,000.

[0100] (Preparation of wax dispersion liquid) 720 parts of deionized water were mixed with 180 parts of ester wax (manufactured by NOF Corporation, WE-11, a synthetic wax derived from plant monomers, melting point 67°C) and 17 parts of an anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen SC, sodium dodecylbenzenesulfonate). This mixture was dispersed in a homogenizer while being heated to 90°C to obtain a wax dispersion. The volume-average particle size of the obtained wax particles was 250 nm, and the solid content concentration of the resin particles was 25%.

[0101] (Masterbatch preparation) 1,200 parts water, 500 parts carbon black (Dexa, Printex35) [DBP oil absorption = 42 mL / 100 mg, pH = 9.5], and 500 parts amorphous polyester resin (B-1) were added and mixed in a Henschel mixer (Nippon Coke Industries Co., Ltd.). The mixture was kneaded at 150°C for 30 minutes using two rolls, then rolled and cooled, and pulverized in a pulperizer to obtain a masterbatch.

[0102] (Preparation of crystalline polyester resin dispersion) In a stirring tank equipped with a nitrogen inlet tube, a dehydration tube, and a thermocouple, 1,6-hexanediol and sebacic acid were charged so that the ratio of OH groups to COOH groups (OH / COOH) was 1.1. The mixture was reacted with 500 ppm titanium tetraisopropoxide relative to the mass of the charged raw materials, while water was being discharged. Finally, the temperature was raised to 235°C and the reaction was carried out for 1 hour. After that, the reaction was carried out under reduced pressure of 10 mmHg or less for 6 hours. Then, the temperature was set to 185°C, trimellitic anhydride was added so that the molar ratio of COOH groups was 0.053, and the reaction was carried out with stirring for 2 hours to obtain a crystalline polyester resin. 55 parts by weight of crystalline polyester resin, 40 parts by weight of methyl ethyl ketone, and 5 parts by weight of 2-propyl alcohol were added to a stirring tank. The mixture was then heated to the melting point of the crystalline polyester resin while stirring to dissolve it. Next, a 28% by mass aqueous ammonia solution was added to achieve a neutralization rate of 400%. The neutralization rate was calculated from the acid value of the crystalline polyester resin. Furthermore, 130 parts by mass of deionized water was gradually added to perform phase inversion emulsification, followed by desolvation. Finally, deionized water was added to adjust the solid content concentration (concentration of crystalline polyester resin) to 25% by mass, obtaining a crystalline polyester resin dispersion, which is a binder resin dispersion for toner. The particle size of the crystalline polyester resin in the dispersion was 200 nm.

[0103] (Example 1)

[0104] <Introduction of polyethylene terephthalate (PET)> Flake-shaped recycled PET was mixed with the polyester resin mentioned above in the proportion of solids shown in Table 1.

[0105] <Oil phase preparation process and aqueous phase preparation process> In an emulsification tank equipped with a stirrer having anchored impeller blades, 500 parts by weight of polyester resin, 100 parts by weight of masterbatch, and 650 parts by weight of ethyl acetate were added and stirred to dissolve or disperse. Then, while stirring, 28 parts by weight of a 28% by mass aqueous ammonia solution was added to prepare an oil phase with a neutralization rate of 80%. An aqueous phase was prepared by adding a surfactant, ABS (alkylbenzene sulfonate), to 1,600 parts by weight of deionized water to a concentration of 1% relative to the deionized water.

[0106] <Phase inversion emulsification process> The oil phase was added to the agitated tank, and the aqueous phase was gradually added to the oil phase to perform phase inversion emulsification. After phase inversion emulsification, the solvent was removed to obtain a resin particle dispersion. The solid content concentration was then adjusted to 20%.

[0107] (Examples 2-10 and Comparative Examples 1-7) Except for the changes made to the stirrer, blade diameter, rotation speed, stirring time, neutralization rate, amount of polyester resin added, amount of PET added, and amount of crystalline polyester dispersion added as shown in Table 1, the resin particle dispersions of Examples 2 to 10 and Comparative Examples 1 to 7 were produced in the same manner as in Example 1.

[0108] [Table 1]

[0109] Toner was prepared using the resin particle dispersions from each example as follows.

[0110] <Agglomeration process and fusion process> 100 parts by weight of resin particle dispersion, 5.0 parts by weight of crystalline polyester resin dispersion, 5.0 parts by weight of wax dispersion, and 300 parts by weight of deionized water were placed in a container and stirred for 1 minute. Next, 20 parts by weight of 5% magnesium chloride solution were added dropwise to the solid content and stirred for a further 5 minutes, after which the temperature was raised to 60°C. After that, when the particle size reached 5.0 μm, 40 parts by weight of sodium chloride was added to complete the flocculation process and obtain a flocculated slurry. The flocculated slurry was then heated to 70°C while stirring, and when the desired circularity of 0.96 was achieved, it was cooled to obtain a toner dispersion.

[0111] <Washing and drying process> (1): 100 parts of deionized water were added to the filter cake, mixed with a TK homomixer (at a rotation speed of 12,000 rpm for 10 minutes), and then filtered. (2): 900 parts of deionized water were added to the filtration cake from (1), and the mixture was mixed in a TK homomixer with ultrasonic vibration (at a rotation speed of 12,000 rpm for 30 minutes), followed by vacuum filtration. This operation was repeated until the electrical conductivity of the slurry was 10 μC / cm or less, and then filtered to obtain a washed filtration cake. The washed filtration cake was dried in a circulating air dryer at 45°C for 72 hours, and sieved with a 75 μm mesh to obtain colored resin particles.

[0112] <External attachment> 2.5 parts by weight of TS530, an inorganic fine particle manufactured by Cabosil, was added to 100 parts by weight of colored resin particles, and the mixture was treated in a Henschel mixer at 40 m / s for 10 minutes to obtain the toner of Example 1.

[0113] (evaluation) <Coarse particle quantity> The resin dispersion was evaluated in four stages according to the percentage of 2 μm particles measured using a laser diffraction particle size analyzer (LA-960).

[0114] [Evaluation Criteria] Resin dispersions with a particle size of 2 μm or more were evaluated as failing (×). ◎: Less than 1% ○: 3% or less △: 5% or less ×: 6% or more

[0115] <Low temperature retention> Using the fuser unit of a color multifunction printer (imagio MP C4500, manufactured by Ricoh), 0.6 mg / cm² of ink was applied to plain paper. 2 Unfixed black images were formed, and then fixed at different fixing temperatures. The temperature at which cold offset occurred was measured and evaluated on a four-point scale.

[0116] [Evaluation Criteria] We evaluated the product as unsatisfactory (×) if the temperature at which cold offset occurred was 130°C or higher. ◎: Below 120℃ ○: 120℃ or higher, but less than 125℃ △: 125℃ or higher and less than 130℃ ×: Above 130℃

[0117] <Environmental compatibility> The environmental friendliness of the toner was evaluated based on the ratio of environmentally friendly resins in the toner, according to the following evaluation criteria. [Evaluation Criteria] Based on the percentage of recycled PET resin shown in Table 1, environmental friendliness was evaluated as failing (C) if the recycled resin content was less than 30%. A: More than 50% recycled resin B: Recycled resin is between 30% and less than 50% C: Less than 30% recycled resin

[0118] Table 2 shows the evaluation results of the toners in the examples and comparative examples.

[0119] [Table 2] [Explanation of Symbols]

[0120] 1. Axis of rotation 2. Agitator blades 3. Agitation tank D. Diameter of the stirring blade [Prior art documents] [Patent Documents]

[0121] [Patent Document 1] Patent No. 3693334 [Patent Document 2] Japanese Patent Publication No. 2022-151291

Claims

1. a) A step of preparing an oil phase by dissolving a binder resin containing at least polyethylene terephthalate or polybutylene terephthalate in an organic solvent, b) A step of adding a neutralizing agent to the oil phase of step a to prepare a neutralizing agent mixture, c) The step of adding water to the neutralizing agent mixture in step b and performing phase inversion emulsification to obtain a resin particle dispersion, The stirring conditions during the mixing of the neutralizing agent in step b above are as follows: [Math 1] And, A method for producing a resin particle dispersion, characterized by stirring under the aforementioned stirring conditions for at least 5 minutes after adding a neutralizing agent.

2. The method for producing a resin particle dispersion according to claim 1, characterized in that the binder resin in step a contains 30% by weight or more of polyethylene terephthalate or polybutylene terephthalate.

3. A method for producing a resin particle dispersion according to claim 1 or 2, wherein the binder resin in step a comprises a polyester resin.

4. A method for producing a resin particle dispersion according to claim 1 or 2, characterized in that the neutralization rate in step b is 30% or more.

5. A method for producing a resin particle dispersion according to claim 1 or 2, characterized in that a crystalline polyester is dissolved in step a.

6. A method for producing toner particles, comprising the step of agglomerating the resin particles of a resin particle dispersion obtained by the method for producing a resin particle dispersion according to claim 1 or 2 to form toner particles.

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