Toner for developing electrostatic images and method for manufacturing electrostatic image developing toner

Abstract

The object of the present invention is to provide a toner for electrostatic image development and a method for manufacturing an electrostatic image development toner that can obtain a desired amount of charge even in a high-temperature, high-humidity environment, prevent hot offset, and achieve low-temperature fixing properties. [Solution] The electrostatic image developing toner of the present invention is characterized in that the aromatic compound content is 0.1 to 30 mg / kg. Furthermore, the method for producing the electrostatic image developing toner of the present invention comprises the step of introducing an aqueous dispersion containing at least resin particles and a surfactant into a reaction vessel and agglomerating and fusing the resin particles, wherein in the agglomerating and fusing step, after introducing the aqueous dispersion into the reaction vessel, the pressure inside the reaction vessel is reduced, the resin particles are agglomerated and fusing under reduced pressure, and the vapor pressure of the gas phase inside the reaction vessel is set to be lower than the saturated vapor pressure of the liquid temperature inside the reaction vessel by 0.01 to 8 kPa.

Description

[Technical Field]

[0001] The present invention relates to a toner for developing electrostatic images and a method for manufacturing an electrostatic image developing toner. In particular, the present invention relates to an electrostatic image developing toner that can obtain a desired amount of charge even in high temperature and high humidity environments, and that can achieve both resistance to hot offset and low temperature fixing performance. [Background technology]

[0002] To address energy-saving requirements, there is a demand for toners that can be fixed at lower temperatures to reduce power consumption during the fixing process, thus exhibiting excellent low-temperature fixing properties. Therefore, toners incorporating acrylic / methacrylic ester-derived structures with high plasticizing effects into the resin have been proposed. However, the high affinity of the ester group portion for water sometimes worsened the electrostatic properties. Furthermore, as disclosed in Patent Document 1, toners using crystalline polyester have also been proposed. However, because crystalline polyester is prone to crystallization, when the toner is left in a high-temperature, high-humidity environment for a long period of time, the crystalline polyester is exposed on the toner surface, resulting in so-called blooming. As a result, charge leakage occurs, and the desired amount of charge cannot be obtained. In addition, because the amount of aromatic compounds in the toner is greater than that of ester compounds, and heat is not easily transferred due to the lack of interaction, so-called hot offset, where the toner adheres to the paper and contaminates it, was also a problem. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2016-033648 [Overview of the project] [Problems that the invention aims to solve]

[0004] This invention has been made in view of the above-mentioned problems and circumstances. The problem to be solved by this invention is to provide an electrostatic image developing toner and a method for manufacturing an electrostatic image developing toner that can obtain a desired amount of charge even in a high-temperature, high-humidity environment and achieve both resistance to hot offset and low-temperature fixing. [Means for solving the problem]

[0005] The inventors of the present invention investigated the causes of the above problems in order to solve them. The inventors of the present invention discovered that by keeping the content of aromatic compounds in the toner within a specific range, the desired amount of charge can be obtained even in high temperature and high humidity environments, and both hot offset resistance and low temperature fixing performance can be achieved, leading to the present invention. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0006] 1. The aromatic compound content is 0.1 to 30 mg / kg. A toner for developing electrostatic images, characterized by the following features.

[0007] 2. The aromatic compound is at least one of benzene, styrene, ethylbenzene, naphthalene, toluene, cumene, and α-methylstyrene. When the aromatic compound is considered as 1, the ester compound is contained in a mass ratio within the range of 0.08 to 0.40. The electrostatic image developing toner according to the first paragraph, characterized in that...

[0008] 3. Contains styrene-acrylic resin as a binder. A toner for developing electrostatic images according to paragraph 1 or 2, characterized by the above.

[0009] 4. Contains polyester resin as a binder. A toner for developing electrostatic images according to paragraph 1 or 2, characterized in that...

[0010] 5. A method for manufacturing the electrostatic image developing toner described in paragraph 1 or 2, An aqueous dispersion containing at least resin particles and a surfactant is charged into a reaction vessel, and the resin particles are aggregated and fused. In the step of aggregating and fusing, after the aqueous dispersion is charged into the reaction vessel, the inside of the reaction vessel is depressurized, and the resin particles are aggregated and fused under the depressurized state. A method for producing a toner for electrostatic charge image development, characterized in that the vapor pressure of the gas phase in the reaction vessel is set to be lower than the saturation vapor pressure of the liquid temperature in the reaction vessel by 0.01 to 8 kPa.

[0011] 6. A colorant particle dispersion is charged into the reaction vessel. The method for producing a toner for electrostatic charge image development according to claim 5, characterized in that.

[0012] 7. Detect the boiling state in the reaction vessel and control the vapor pressure of the gas phase. The method for producing a toner for electrostatic charge image development according to claim 5, characterized in that.

[0013] 8. As a means for detecting the boiling state, bubbles generated by depressurization are detected, and the depressurization in the reaction vessel is released.​​​​​​​​​​​​​​​​​​​​By the above means of the present invention, it is possible to provide an electrostatic charge image developing toner capable of obtaining a desired charge amount even in a high-temperature and high-humidity environment and achieving both hot offset resistance and low-temperature fixing property, and a method for manufacturing the electrostatic charge image developing toner. Although the mechanism of expression or the mechanism of action of the effects of the present invention is not clear, it is speculated as follows. According to the present invention, by containing an aromatic compound in the toner at 0.1 to 30 mg / kg, the polarity difference from the ester resin can be reduced. Since the polarity difference is small, the aromatic compound and the ester resin are likely to be mixed, thereby preventing the movement of the ester resin to the toner surface. As a result, charge leakage is unlikely to occur, and a desired charge amount can be expressed. Furthermore, it is possible to prevent hot offset and obtain a toner excellent in low-temperature fixing property. When no aromatic compound is added, the hot offset resistance is good, but the fixing temperature is high. On the other hand, if too much aromatic compound is added, low-temperature fixing property is exhibited, but the hot offset resistance deteriorates.

Embodiments for Carrying Out the Invention

[0017] The electrostatic charge image developing toner of the present invention is characterized in that the content of the aromatic compound is 0.1 to 30 mg / kg. This feature is a technical feature common or corresponding to each of the following embodiments.

[0018] As an embodiment of the present invention, the aromatic compound is at least one of benzene, styrene, ethylbenzene, naphthalene, toluene, cumene, and α-methylstyrene, and when the aromatic compound is taken as 1, it is preferable to contain an ester compound in the range of 0.08 to 0.40 in terms of mass ratio. By setting the mass ratio of the ester compound to 0.08 or more, the ester compound and the aromatic compound interact with each other, and the hot offset property becomes good. By setting the mass ratio of the ester compound to 0.40 or less, the ratio of the ester compound does not become too large, so the affinity with water becomes good and the charge amount also becomes good.

[0019] The inclusion of styrene-acrylic resin as a binder resin is preferable because it allows for uniform dispersion of the wax and reduces environmental dependence during electrostatic charging. The inclusion of polyester resin as the binder resin is preferable in terms of low-temperature fixation because it has sharp-melt properties, meaning it melts rapidly above a certain temperature.

[0020] A method for producing a toner for developing electrostatic images according to the present invention, comprising the step of introducing an aqueous dispersion containing at least resin particles and a surfactant into a reaction vessel and agglomerating and fusing the resin particles, wherein in the agglomerating and fusing step, after introducing the aqueous dispersion into the reaction vessel, the pressure inside the reaction vessel is reduced, the resin particles are agglomerated and fusing under reduced pressure, and the vapor pressure of the gas phase inside the reaction vessel is set to be lower than the saturated vapor pressure of the liquid temperature inside the reaction vessel by 0.01 to 8 kPa. By adding the aqueous dispersion to the reaction vessel and adjusting the vapor pressure of the gas phase within the reaction vessel to the aforementioned range during the reaction, the aromatic compound and the ester compound are obtained in an appropriate composition ratio. As a result, the aromatic compound and the ester resin mix easily, preventing the migration of the ester resin to the toner surface. Consequently, electrolysis leakage is less likely to occur, and the desired amount of charge can be achieved. Furthermore, both resistance to hot offset and low-temperature fixing can be achieved.

[0021] In the aforementioned depressurization step, it is preferable to introduce the colorant particle dispersion into the reaction vessel in order to uniformly incorporate the colorant particles into the toner matrix particles.

[0022] In the process of reducing the pressure, it is preferable to detect the boiling state in the reaction vessel and control the vapor pressure of the gas phase. As a means for detecting the boiling state, it is preferable to detect the bubbles generated in the depressurization step and release the depressurization in the reaction vessel, as this allows for easy and accurate control of the degree of depressurization. In the aforementioned depressurization step, detecting the temperature of the gas phase and releasing the depressurization in the reaction vessel is preferable because it allows for easy and accurate control of the degree of depressurization. It is preferable to control the pressure inside the reaction vessel by introducing air into the reaction vessel, as this allows for easy and accurate control of the degree of pressure reduction. In addition to controlling the degree of vacuum by detecting the boiling state, the degree of vacuum can also be controlled by continuously blowing in a constant flow rate of air. This also allows for an efficient reduction of VOC components.

[0023] The present invention, its components, and embodiments for carrying out the present invention will be described below. In this application, "~" is used to mean that the numerical values ​​written before and after it are included as the lower limit and upper limit.

[0024] [Overview of the method for manufacturing electrostatic image developing toner according to the present invention] The electrostatic image developing toner of the present invention is characterized by having an aromatic compound content of 0.1 to 30 mg / kg. Hereinafter, the toner for developing electrostatic images will also be simply referred to as "toner." In this invention, "toner" refers to an aggregate of "toner particles." Furthermore, toner particles contain at least toner matrix particles, and toner particles refer to the toner matrix particles themselves or toner matrix particles to which at least an external additive has been added. The aromatic compound is contained in a range of 0.1 to 30 mg / kg. That is, the aromatic compound is contained in a range of 0.1 to 30 mg per 1 kg of toner. In particular, it is preferable that the aromatic compound be contained in a range of 10 to 25 mg per 1 kg of toner.

[0025] <Aromatic compound content> To adjust the amount of aromatic compounds to the aforementioned range, one method is to perform the coagulation and fusion process under reduced pressure during toner manufacturing. The amount of aromatic compounds can also be adjusted by increasing the drying conditions in the airflow drying process after the coagulation and fusion process, but this results in the toner particles remaining coagulated without breaking apart, leading to image defects such as fogging. On the other hand, reducing the pressure during toner association can remove aromatic compounds without affecting the toner dispersion state. Therefore, it is preferable to reduce the pressure during aggregation and fusion. In this invention, as described later, in the flocculation and fusion process, the vapor pressure of the gas phase in the reaction vessel is set to be 0.01 to 8 kPa lower than the saturated vapor pressure of the liquid temperature in the reaction vessel. This maintains the liquid in the reaction vessel in the boiling region. During this time, the amount of aromatic compounds and ester compounds in the liquid can be adjusted. Furthermore, under reduced pressure, foaming occurs in water containing surfactants, but by maintaining the vapor pressure of the gas phase in the reaction vessel within the aforementioned range, foaming is contained within a certain range and no foam leaks from the reaction vessel. In addition, the rise in the foam level does not increase the amount of residue adhering to the reaction vessel wall, which does not adversely affect image quality.

[0026] <Preferred range of vapor pressure> The vapor pressure of the gas phase in the reaction vessel is preferably set lower than the saturated vapor pressure at the liquid temperature by 0.01 to 8 kPa, and more preferably lower by 0.01 to 5 kPa. By setting the temperature within the above range, the liquid will be maintained in the boiling region, during which time the volatilization of VOC components (volatile organic compounds) in the liquid will be promoted, enabling efficient removal of VOC components. If the vapor pressure is 0.01 kPa or more higher than the saturated vapor pressure of the liquid temperature, the liquid will reach the boiling region, and the VOC components will volatilize to a moderate degree. If the vapor pressure is 8 kPa or less higher than the saturated vapor pressure of the liquid temperature, excessive foaming will not occur, and foam leakage from the reaction vessel can be prevented. In addition, the rise in the foam level reduces the amount of residue adhering to the reaction vessel walls, preventing adverse effects on image quality. Examples of the volatile organic compounds include aromatic compounds and ester compounds.

[0027] The saturated vapor pressure of the liquid temperature refers to the saturated vapor pressure of all the liquids introduced into the reaction vessel. Specifically, as described later, it refers to the saturated vapor pressure at the liquid temperature of the liquid containing all the materials that were added to the reaction vessel from the start of heating to the end of maturation, such as resin particle dispersion, colorant particle dispersion, flocculant, sodium hydroxide aqueous solution, magnesium chloride aqueous solution, etc.

[0028] <Aromatic compounds and ester compounds> The aromatic compounds and ester compounds mentioned above are present in the toner due to materials used in the polymerization process. In other words, the aromatic compounds and ester compounds are present due to residues and impurities from the raw materials used in polymerization. The aforementioned aromatic compounds refer to compounds having monocyclic or polycyclic aromatic rings, and in this invention, those having 6 to 20 carbon atoms are targeted. Among these, those having 6 to 11 carbon atoms are preferred. In the case of aromatic compounds with 20 or fewer carbon atoms, the dispersion forces (π-π interactions) acting between aromatic rings do not stabilize the aromatic compounds in a stacked structure. Therefore, they readily interact with ester compounds, and a plasticity effect is exhibited. Consequently, they exhibit good low-temperature fixation properties. Furthermore, for ester compounds, those with a molecular weight similar to that of aromatic compounds are preferable because they interact more easily with aromatic compounds; therefore, those with 20 or fewer carbon atoms are preferred.

[0029] The aromatic compound is preferably at least one of the following: benzene, styrene, ethylbenzene, naphthalene, toluene, cumene, α-methylstyrene, acetophenone, and benzaldehyde. In particular, the aromatic compound is preferably at least one of the following: benzene, styrene, ethylbenzene, naphthalene, toluene, cumene, and α-methylstyrene.

[0030] Examples of the ester compounds include butyl acetate, butyl 2-propenoate, butyl propanoate, butyl butanoate, 9-octadecenoic acid (Z)-phenylmethyl ester, and n-butyl ester. In particular, it is preferable that the ester compound contains at least one of butyl acetate, butyl 2-propenoate, butyl propanoate, and butyl butanoate.

[0031] <Mass ratio of aromatic compounds and ester compounds> The toner of the present invention preferably contains an ester compound in a mass ratio of 0.08 to 0.40, and particularly preferably in a mass ratio of 0.10 to 0.36, with the aromatic compound being 1. By containing the ester compound within this range, the toner exhibits good affinity between the ester compound and water, resulting in good charge distribution. It also exhibits excellent resistance to hot offset.

[0032] The content of aromatic compounds and ester compounds is quantified by the following headspace method. (i) Sample collection A 100 mg toner sample was collected in a 10 mL headspace vial (AGILENT vial). The sample was weighed to the nearest 0.1 mg. The vial was sealed at the septum using a dedicated crimper.

[0033] (ii) Heating of the sample and injection into the gas chromatograph The vial containing the sample was placed in a heating furnace / autosampler (Hewlett-Packard HEAD SPACE SAMPLER HP7694). The sample was placed upright in the 170°C heating furnace, and after 10 minutes, 5 μL of the gas phase from the vial was sampled and injected into a gas chromatograph.

[0034] (iii) Setting the chromatographic isolation state A J&W GC column DB-624 (length 30 m, inner diameter 0.25 mm, film thickness 1.40 μm) manufactured by Agilent Technologies was used as the separation column. The separation column was mounted on a gas chromatograph (Hewlett-Packard 5890 SERIES II) and He was flowed through it at a rate of 2 ml / min. After holding the separation column temperature at 40°C for 2 minutes, measurements were taken while increasing the temperature to 230°C at a rate of 10°C / min. The injection temperature was 230°C and the FID detection side temperature was 230°C.

[0035] (iv) Creation of a calibration curve Toluene-acetone solutions prepared to 1000 ppm were collected in 0, 1, 2, 4, 10, 20, and 25 μL portions using a syringe and divided into 10 ml vials. Analysis was performed in the same manner as in (ii) and (iii) above, and calibration curves were created for the amount of toluene injected and the peak area.

[0036] (v) calculation The amounts of aromatic compounds and ester compounds in the toner were calculated by converting the total area of ​​the peaks detected between the retention times of n-hexane and n-hexadecane using the toluene calibration curve described above.

[0037] (vi) The following apparatus configuration is preferred. However, it is not limited to this configuration as long as the column and apparatus have equivalent performance. (a) Headspace conditions Headspace device: S-trap HS (manufactured by JEOL Ltd.) Temperature conditions: Transfer line: 180℃ Loop temperature: 180℃ Sample volume: 100 mg / 20 mL vial

[0038] (b)GC / MS conditions GC:7890B (manufactured by Agilent) MS:JMS-Q1500GC (manufactured by JEOL Ltd.) Column: SH-I-624Sil (manufactured by SHIMADZU, 30m x inner diameter 0.25mm) Oven temperature Initial temperature: 40℃ (holding time 2 minutes) Heating rate: 10°C / min Achieved temperature: 230℃ (holding time 14 minutes) m / z acquisition range: 20-300

[0039] The content of the aromatic compound in the toner particles can be controlled by adjusting the reduced pressure inside the reaction vessel during the toner manufacturing process, as described later. Similarly, the mass ratio of the ester compound can also be controlled by adjusting the reduced pressure inside the reaction vessel.

[0040] [Toner Configuration] <Toner matrix particles> The binder resin contained in the toner matrix particles according to the present invention preferably contains both an amorphous resin and a crystalline resin. In addition, the toner matrix particles may contain other components as needed, such as a colorant, a mold release agent (wax), a charge control agent, and a surfactant. By using a mixture of crystalline and amorphous resins in the toner matrix particles, the crystalline and amorphous resins become compatible during heat fixing. As a result, toner can be fixed at lower temperatures, leading to energy savings.

[0041] <Amorphous resin> Conventional amorphous resins are used as amorphous resins. In particular, amorphous resins that include amorphous vinyl resins are preferred. Styrene-acrylic copolymer resins formed using styrene monomers and (meth)acrylic acid ester monomers or acrylic acid are especially preferred. By emulsifying and agglomerating the styrene-acrylic resin to form toner, the moisture content of the toner is appropriately increased, improving the adhesion of the toner to the photoreceptor. As a result, the toner is less likely to detach from the photoreceptor, and scavenging can be suppressed. One or more vinyl monomers selected from the following may be used to form amorphous vinyl resins.

[0042] (1) Styrene monomers Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, and their derivatives.

[0043] (2) (meth)acrylic acid ester monomers Examples of (meth)acrylic acid ester monomers include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, phenyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, and their derivatives.

[0044] (3) Vinyl esters Examples of vinyl esters include vinyl propionate, vinyl acetate, and vinyl benzoate. (4) Vinyl ethers Examples of vinyl ethers include vinyl methyl ether and vinyl ethyl ether. (5) Vinyl ketones Examples of vinyl ketones include vinyl methyl ketone, vinyl ethyl ketone, and vinyl hexyl ketone. (6) N-vinyl compounds Examples of N-vinyl compounds include N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone.

[0045] (7) Others Vinyl compounds such as vinylnaphthalene and vinylpyridine, as well as acrylic acids or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide, can also be used.

[0046] Furthermore, as vinyl monomers, it is preferable to use monomers having ionic dissociation groups such as carboxyl groups, sulfonic acid groups, and phosphate groups. Specifically, the following can be mentioned. Examples of monomers containing a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, monoalkyl maleic acid, and monoalkyl itaconic acid. Examples of monomers having a sulfonic acid group include styrenesulfonic acid, allylsulfosuccinic acid, and 2-acrylamido-2-methylpropanesulfonic acid. Examples of monomers containing a phosphate group include acidophosphooxyethyl methacrylate.

[0047] Furthermore, polyfunctional vinyls can be used as vinyl monomers, and amorphous vinyl resins can be made to have a cross-linked structure. Examples of polyfunctional vinyls include divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, and neopentyl glycol diacrylate. Although vinyl resins have been described in detail as a preferred form of amorphous resin, the invention is not limited to vinyl resins, and amorphous polyester resins and other materials may also be used as amorphous resins.

[0048] <Crystalline resin> Crystalline resins are resins that exhibit a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). Specifically, a clear endothermic peak means a peak whose full width at half maximum (FWHM) is within 15°C when measured at a heating rate of 10°C / min in differential scanning calorimetry (DSC).

[0049] As long as the crystalline resin has the above-mentioned properties, there are no particular restrictions, and conventionally known crystalline resins in this art can be used. Specific examples include crystalline polyester resin, crystalline polyurethane resin, crystalline polyurea resin, crystalline polyamide resin, and crystalline polyether resin. The crystalline resin can be used alone or in combination of two or more types.

[0050] In particular, the crystalline resin is preferably a crystalline polyester resin. Here, "crystalline polyester resin" refers to a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and its derivatives and a divalent or higher alcohol (polyvalent alcohol) and its derivatives, which satisfies the above endothermic properties.

[0051] The melting point of the crystalline polyester resin is not particularly limited, but is preferably 55 to 90°C. A melting point within this range ensures sufficient low-temperature fixability. From this viewpoint, it is more preferably 60 to 85°C. The melting point of the crystalline polyester resin can be controlled by the resin composition. In this specification, the melting point of the resin is determined by the method used in the examples.

[0052] The valencies of the polycarboxylic acid and polyol constituting the crystalline polyester resin are preferably 2 to 3, and particularly preferably 2. Therefore, the following will focus on the case where the valency is 2 (i.e., the dicarboxylic acid component and the diol component).

[0053] As the dicarboxylic acid component, an aliphatic dicarboxylic acid is preferred, and an aromatic dicarboxylic acid may be used in combination if necessary. A linear aliphatic dicarboxylic acid is preferred, as using a linear type offers the advantage of improved crystallinity. The dicarboxylic acid component may be used alone or in combination of two or more types. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid (dodecanediic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (tetradecanediic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. As for the dicarboxylic acid component, among the above aliphatic dicarboxylic acids, it is preferable to have an aliphatic dicarboxylic acid having 6 to 14 carbon atoms, and more preferably an aliphatic dicarboxylic acid having 8 to 14 carbon atoms.

[0054] Aromatic dicarboxylic acids that can be used with aliphatic dicarboxylic acids include, for example, phthalic acid, terephthalic acid, isophthalic acid, orthophthalic acid, t-butyl isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid. Among these, terephthalic acid, isophthalic acid, and t-butyl isophthalic acid are preferred from the viewpoint of availability and ease of emulsification. In addition to the dicarboxylic acids mentioned above, other polycarboxylic acids with a valency of 3 or higher, such as trimellitic acid and pyromellitic acid, as well as anhydrides of the above carboxylic acid compounds, or alkyl esters having 1 to 3 carbon atoms, may also be used.

[0055] The dicarboxylic acid component for forming the crystalline polyester resin preferably contains 50 mol% or more of aliphatic dicarboxylic acid. More preferably, the aliphatic dicarboxylic acid content is 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%. By having an aliphatic dicarboxylic acid content of 50 mol% or more in the dicarboxylic acid component, the crystallinity of the crystalline polyester resin can be sufficiently ensured.

[0056] Furthermore, it is preferable to use an aliphatic diol as the diol component, and other diols may be used in combination as needed. It is preferable to use a linear aliphatic diol, as this improves crystallinity. The diol component may be used alone or in combination of two or more.

[0057] Examples of aliphatic diols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol.

[0058] As for the diol component, among the aliphatic diols mentioned above, it is preferable that it be an aliphatic diol having 2 to 12 carbon atoms, and more preferably an aliphatic diol having 3 to 10 carbon atoms. Examples of diols that can be used with aliphatic diols include diols having double bonds and diols having sulfonic acid groups. Specifically, examples of diols having double bonds include 1,4-butenediol, 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octen-1,8-diol. Other examples include polyhydric alcohols with a valency of 3 or higher, such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol.

[0059] The diol component for forming the crystalline polyester resin preferably contains 50 mol% or more of aliphatic diol. More preferably, the aliphatic diol content is 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 100 mol%. By having an aliphatic diol content of 50 mol% or more in the diol component, the crystallinity of the crystalline polyester resin can be ensured, and a toner with excellent low-temperature fixation properties can be obtained.

[0060] The weight-average molecular weight (Mw) of the crystalline polyester resin is preferably 3,000 to 100,000, from the viewpoint of reliably achieving both sufficient low-temperature fixability and excellent long-term heat-resistant storage stability. The weight-average molecular weight is more preferably 4,000 to 50,000, and particularly preferably 5,000 to 20,000. The ratio of the diol component to the dicarboxylic acid component used is preferably such that the ratio [OH] / [COOH] of the equivalent amount of hydroxyl group [OH] of the diol component to the equivalent amount of carboxyl group [COOH] of the dicarboxylic acid component is 1.5 / 1 to 1 / 1.5, and more preferably 1.2 / 1 to 1 / 1.2.

[0061] The method for producing crystalline polyester resin is not particularly limited, and it can be produced by polycondensing (esterifying) the above-mentioned dicarboxylic acid and dialcohol using a known esterification catalyst. Examples of catalysts that can be used in the production of crystalline polyester resins include alkali metal compounds such as sodium and lithium; compounds containing group 2 elements such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphite compounds; phosphate compounds; and amine compounds. Specifically, examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and their salts. Examples of titanium compounds include titanium alkoxides such as tetran-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine. Examples of germanium compounds include germanium dioxide. Examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminate. These may be used individually or in combination of two or more.

[0062] The polymerization temperature is not particularly limited, but is preferably 150 to 250°C. The polymerization time is also not particularly limited, but is preferably 0.5 to 15 hours. During polymerization, the reaction system may be subjected to reduced pressure as needed. When the binder resin contains a crystalline resin (preferably a crystalline polyester resin), the content of the crystalline resin in the binder resin is not particularly limited, but it is preferably less than 50% by mass of the total amount of the binder resin. The content of the crystalline resin is more preferably 30% by mass or less, and particularly preferably 10% by mass or less, of the total amount of the binder resin. When the crystalline resin is a crystalline polyester resin, the environmental dependence of the charge amount due to the hygroscopicity of the crystalline polyester resin can be reduced by limiting its content to less than 50% by mass. On the other hand, there is no particular lower limit to the content, but when the binder resin contains a crystalline resin (preferably a crystalline polyester resin), it is preferable that it be 5% by mass or more. If the crystalline resin content is 5% by mass or more relative to the total amount of the binder resin, a toner with excellent low-temperature fixation properties can be obtained.

[0063] <Coloring agent> As coloring agents, carbon black, magnetic materials, dyes, pigments, etc., can be used as desired. Examples of carbon black used include channel black, furnace black, acetylene black, thermal black, or lamp black. As magnetic materials, ferromagnetic metals such as iron, nickel, or cobalt, alloys containing these metals, ferrite, or compounds of ferromagnetic metals such as magnetite can be used.

[0064] As dyes, CI Solvent Red 1, 49, 52, 58, 63, 111, 122; CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162; CI Solvent Blue 25, 36, 60, 70, 93, 95, etc. can be used, and mixtures of these can also be used. Pigments such as CI Pigment Red 5, 48:1, 48:3, 53:1, 57:1, 81:4, 122, 139, 144, 149, 166, 177, 178, 222, CI Pigment Orange 31, 43, CI Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, CI Pigment Green 7, CI Pigment Blue 15:3, 15:4, or 60 can be used, and mixtures of these can also be used.

[0065] <Release agent> Various known waxes can be used as release agents. Examples of waxes include polyolefin waxes such as polyethylene wax and polypropylene wax, branched hydrocarbon waxes such as microcrystalline wax, long-chain hydrocarbon waxes such as paraffin wax and sazole wax, dialkylketone waxes such as distearyl ketone, carnauba wax, montane wax, behenyl behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, ester waxes such as tristearyl trimellitate and distearyl maleate, and amide waxes such as ethylenediamine behenylamide and tristearyl trimellitate.

[0066] The release agent content is preferably 0.1 to 30 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of the binder resin. These can be used individually or in combination of two or more types. Furthermore, the melting point of the release agent is preferably 50 to 95°C from the viewpoint of low-temperature fixation and release properties of toner in electrophotography.

[0067] <Charge control agent> As the charge control agent, known charge control agent particles that can be dispersed in an aqueous medium can be used. Specifically, these include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts, or metal complexes thereof.

[0068] <Surfactants> Examples of surfactants include anionic surfactants, cationic surfactants, and nonionic surfactants, and these may be present in one or more forms.

[0069] Examples of anionic surfactants include sulfate esters, sulfonates, and phosphate esters. Specifically, examples include sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, sodium alkylnaphthalenesulfonate, and sodium dialkylsulfosuccinate.

[0070] Examples of cationic surfactants include amine salts and quaternary ammonium salts. Specifically, examples include alkylbenzenedimethylammonium chloride, alkyltrimethylammonium chloride, and distearylammonium chloride.

[0071] Examples of nonionic surfactants include polyethylene glycol-based surfactants, alkylphenol ethylene oxide adduct-based surfactants, and polyhydric alcohol-based surfactants. Specifically, examples include polyoxyethylene alkyl ethers, glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and polyoxyethylene fatty acid esters.

[0072] <External additives> To improve the fluidity, electrostatic properties, and cleaning properties of the toner, it is preferable to add external additives such as fluidizers and cleaning aids, which are so-called post-treatment agents, to the surface of the toner matrix particles.

[0073] The external additive may be one or more types. The external additive is not particularly limited and known additives can be used, for example, silica particles, titania particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, and boron oxide particles can be used.

[0074] The external additive more preferably contains silica particles produced by the sol-gel method. Silica particles produced by the sol-gel method are preferable because they have a narrow particle size distribution, which suppresses variations in the adhesion strength of the external additive to the toner matrix particles.

[0075] Furthermore, the number-average primary particle diameter of the silica particles is preferably 70 to 200 nm. Silica particles with a number-average primary particle diameter within this range are larger than those of other external additives. Therefore, it acts as a spacer in a two-component developer. Thus, it is preferable from the viewpoint of preventing smaller external additives from becoming embedded in the toner matrix particles when the two-component developer is being agitated in the developing device. It is also preferable from the viewpoint of preventing the toner matrix particles from fusing together.

[0076] The number-average primary particle size of an external additive can be determined, for example, by image processing of images taken with a transmission electron microscope, and can be adjusted, for example, by classification or mixing of classified products.

[0077] The external additive is preferably subjected to a hydrophobic treatment on its surface. A known surface treatment agent can be used for this hydrophobic treatment. The surface treatment agent may be one or more types, and examples include silane coupling agents, silicone oil, titanate coupling agents, aluminate coupling agents, fatty acids, fatty acid metal salts, their esterified products, and rosinic acid.

[0078] Examples of silane coupling agents include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane. Examples of silicone oils include cyclic compounds and linear or branched organosiloxanes. More specifically, these include organosiloxane oligomers, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane.

[0079] Examples of silicone oils include highly reactive silicone oils in which modifying groups are introduced into the side chains, one or both ends, one or both ends of the side chain, or both ends of the side chain, and at least the ends are modified. The type of modifying group may be one or more, and examples include alkoxy, carboxyl, carbinol, higher fatty acid modification, phenol, epoxy, methacrylic, and amino.

[0080] The amount of external additive added is preferably 0.1 to 10.0% by mass, and more preferably 1.0 to 3.0% by mass, relative to the total toner matrix particles.

[0081] [Physical properties of toner particles] <Structure of toner particles> The toner matrix particles according to the present invention may have a single-layer structure, but it is preferable that they have a core-shell structure. This allows for better low-temperature fixation and heat-resistant storage properties.

[0082] Toner matrix particles having a core-shell structure refer to toner matrix particles having a multilayer structure comprising a core particle and a shell that covers its surface. The shell does not necessarily cover the entire surface of the core particles; the core particles may be partially exposed. The cross-section of the core-shell structure can be confirmed by known observation methods, such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[0083] In the case of a core-shell structure, the core particles and the shell can have different properties such as glass transition temperature, melting point, and hardness, allowing for the design of toner particles tailored to specific purposes. For example, a shell can be formed by aggregating and fusing a resin with a relatively high glass transition temperature onto the surface of core particles containing a binder resin, colorant, and release agent, which have a relatively low glass transition temperature. Among the amorphous resins that constitute the core particles, vinyl resin is preferred, and styrene-acrylic resin is preferred. Furthermore, amorphous resins are preferred as the resins that constitute the shell layer, amorphous polyester resins and vinyl resins are more preferred, and amorphous polyester resin is particularly preferred.

[0084] <Volume-average particle size of toner particles> The volume-average particle size of the toner particles, that is, the particles after the addition of the external additive, is preferably 4.0 μm or more and 10.0 μm or less. Having the volume-average particle size within this range improves the fluidity of the toner particles and suppresses a decrease in the rise of the toner particle charge and a decrease in image quality. More preferably, the volume-average particle size of the toner particles is 4.5 μm or more and 8.0 μm or less, and even more preferably 5.0 μm or more and 7.5 μm or less. The volume-average particle size of toner particles is specifically the volume-based median diameter (D) measured by the following method. 50 ) shall be adopted.

[0085] (Measurement method) Median diameter (D) of toner particles based on volume 50 This can be measured and calculated using a device that connects a data processing computer system to a "Multisizer 3 (manufactured by Beckman Coulter)". The measurement procedure involves mixing 0.02 g of toner particles with 20 mL of surfactant solution, followed by ultrasonic dispersion for 1 minute to prepare a toner particle dispersion. The surfactant solution is, for example, a solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water, for the purpose of dispersing the toner particles. The toner particle dispersion is pipetted into a beaker containing the ISOTON II (manufactured by Beckman Coulter) in the sample stand until the concentration reaches a range of 5-10%, and the measurement is performed with the instrument count set to 25,000.

[0086] Note that the aperture diameter of the Multisizer 3 is set to 100 μm. The measurement range of 1 to 30 μm is divided into 256 sections, and the frequency count is calculated. The particle size of the 50% with the largest volume integral fraction is used as the volume-based median diameter (D 50 ) The volume-average particle size of toner particles can be controlled by controlling the concentration of the flocculant, the amount of organic solvent added, or the fusion time.

[0087] <Average circularity of toner particles> The average circularity of the toner particles is preferably 0.98 or less, more preferably 0.97 or less, and even more preferably within the range of 0.93 to 0.97. An average circularity within this range results in toner particles that are more easily charged. The average circularity can be measured, for example, using a flow-type particle image analyzer "FPIA-3000" (manufactured by Sysmex). Specifically, the average circularity can be measured using the following method.

[0088] (Measurement method) Toner particles are moistened with a surfactant aqueous solution and subjected to ultrasonic dispersion for 1 minute. After dispersion, measurements are taken using the "FPIA-3000" in HPF (high magnification imaging) mode at an appropriate concentration within the range of 3000 to 10000 HPF detection points. Within this range, reproducible measurements can be obtained. Circularity is calculated using the following formula. Circularity = (Perimeter of a circle with the same projection area as the particle image) / (Perimeter of the particle projection image) The average circularity is the arithmetic mean obtained by summing the circularity of each particle and dividing by the total number of particles measured. The average circularity of the toner particles can be controlled by controlling the temperature, time, etc., during the maturation process in the manufacturing method described above.

[0089] <Softening point of toner particles> From the viewpoint of low-temperature fixation, the softening point of the toner particles is preferably 80 to 120°C, more preferably 95 to 105°C, and particularly preferably 97 to 103°C. The softening point is measured using the flow tester shown below. Specifically, first, 1.1 g of the sample (toner particles) is placed in a petri dish and leveled in an environment of 20°C and 50% RH, and left for 12 hours or more. Subsequently, the molding machine "SSP-10A" (manufactured by Shimadzu Corporation) was used to process the material at 3820 kg / cm². 2 A cylindrical molded sample with a diameter of 1 cm is prepared by applying pressure of 3.75 MPa for 30 seconds. Next, this molded sample is extruded from a cylindrical die hole (1 mm diameter x 1 mm) using a 1 cm diameter piston from the end of preheating, under the conditions of a load of 196 N (20 kgf), a starting temperature of 60 °C, a preheating time of 300 seconds, and a heating rate of 6 °C / min, in an environment of 24 °C and 50 RH using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation). The softening point is defined as the offset method temperature Toffset, measured using the heating method with an offset value of 5 mm.

[0090] [Toner manufacturing method] The toner manufacturing method of the present invention comprises the steps of introducing an aqueous dispersion containing at least resin particles and a surfactant into a reaction vessel and agglomerating and fusing the resin particles, wherein, after introducing the aqueous dispersion into the reaction vessel, the pressure inside the reaction vessel is reduced, the resin particles are agglomerated and fused under reduced pressure, and the vapor pressure of the gas phase inside the reaction vessel is set to be lower than the saturated vapor pressure of the liquid temperature inside the reaction vessel by 0.01 to 8 kPa. The aforementioned aqueous dispersion refers to a resin particle dispersion prepared in the polymerization process (first to third stage polymerization) described later. Since the toner manufacturing method of the present invention sets the vapor pressure inside the reaction vessel within the aforementioned range, it is preferable to employ an emulsification and coagulation method.

[0091] The emulsification and coagulation method involves mixing a dispersion of binder resin particles, dispersed with surfactants and dispersion stabilizers, with a dispersion of colorant particles as needed, and coagulating the mixture until the desired toner particle size is achieved. Furthermore, the shape is controlled by fusing the binder resin particles together to produce toner particles. Here, the binder resin particles are also called binder resin particles, and the colorant particles are also called colorant particles. The binder resin particles may optionally contain release agents, charge control agents, etc. An example of a method for producing toner according to the present invention, in which toner particles having a core-shell structure are obtained using an emulsification agglutination method, is shown below.

[0092] (1) A step of preparing a coloring agent particle dispersion in which coloring agent particles are dispersed in an aqueous medium. (2) A step of preparing a resin particle dispersion (for core / shell resin particle dispersion) in which binder resin particles containing a surfactant and, if necessary, an internal additive are dispersed in an aqueous medium. (3) A process in which a colorant particle dispersion and a core resin particle dispersion are placed in a reaction vessel, the inside of the reaction vessel is depressurized after placement, and under depressurized conditions, the colorant particle dispersion and the core resin particle dispersion are mixed to form a flocculation resin particle dispersion, in the presence of a flocculant, to flocculate and fuse the colorant particles and binding resin particles to form flocculated particles as core particles (flocculation and fusion process). (4) A process (aggregation and fusion process) in which, under reduced pressure, a dispersion of shell resin particles containing binder resin particles for the shell layer is added to a dispersion containing core particles, and the shell layer particles are aggregated and fused to the surface of the core particles to form toner matrix particles with a core-shell structure. (5) A step to filter out toner matrix particles from the toner matrix particle dispersion (toner matrix particle dispersion) and remove surfactants, etc. (washing step) (6) Drying process for toner matrix particles (drying process) (7) The process of adding an external additive to the toner matrix particles (external additive treatment process).

[0093] In the present invention, the aggregation and fusion steps (3) and (4) are performed under reduced pressure. Specifically, in the aggregation and fusion step (3), the colorant particle dispersion and the core resin particle dispersion introduced into the reaction vessel are mixed to obtain the aggregation resin particle dispersion, and then the reaction vessel is depressurized to produce core-shell particles under reduced pressure. In addition, in the aggregation and fusion step (4), while maintaining the reduced pressure in the reaction vessel, the shell resin particle dispersion containing binder resin particles for the shell layer is added to the dispersion containing the core particles, causing the shell layer particles to aggregate and fuse to the surface of the core particles to form core-shell structured toner matrix particles.

[0094] By reducing the pressure, the gas phase within the reaction vessel is depressurized, reducing the amount of aromatic and ester compounds dissolved in the resin particle dispersion for flocculation. The reduced pressure also causes the aromatic compounds and water to volatilize simultaneously. A heat exchanger condenses only the water, returning it to the reaction vessel as reflux water, thus making the shell particle flocculation and fusion process the same as at atmospheric pressure. The aromatic compound components are thermally decomposed and exhausted in a clean state.

[0095] The vapor pressure of the gas phase inside the reaction vessel is set to be 0.01 to 8 kPa lower than the saturated vapor pressure of the flocculating resin particle dispersion at its liquid temperature, preferably in the range of 0.01 to 5 kPa. By setting it within this range, the flocculating resin particle dispersion is maintained in the boiling region. Therefore, while the flocculating resin particle dispersion is maintained in the boiling region, the volatilization of VOC (volatile organic compound) components in the liquid is promoted, enabling efficient removal of VOC components. In other words, aromatic compounds and ester compounds are removed.

[0096] If the vapor pressure of the gas phase inside the reaction vessel is less than 0.01 kPa relative to the saturated vapor pressure of the liquid temperature (0 to less than 0.01 kPa), the liquid will not reach the boiling region, and the degree of volatilization of VOC components will be small. If the vapor pressure inside the reaction vessel is greater than 8 kPa above the saturated vapor pressure at the liquid temperature, significant foaming will occur, which cannot be suppressed, and the foam will leak out of the reaction vessel. In addition, as the foam level rises, the amount of residue adhering to the walls of the reaction vessel increases, negatively affecting image quality. Furthermore, carrier air can be introduced into the reaction vessel, and aromatic compounds can be efficiently removed by continuously blowing in a constant amount. Furthermore, during depressurization, foaming may occur on the surface of the flocculating resin particle dispersion inside the reaction vessel, resulting in the formation of bubbles. If these bubbles become excessive, they may leak from the reaction vessel, and the residue inside the vessel will also increase, leading to a deterioration of image quality. Therefore, it is necessary to suppress foaming. Therefore, a thermocouple is installed at the top of the reaction vessel to detect bubbles based on the difference between the gas phase temperature inside the reaction vessel and the temperature of the resin particle dispersion for flocculation. Bubbles are then broken by blowing air into the top of the reaction vessel to reduce the degree of reduced pressure.

[0097] In the present invention, "aqueous medium" refers to a medium consisting of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. It is preferable to use an alcohol-based organic solvent that does not dissolve the resulting resin. The following explains steps (1) through (7).

[0098] (1) Step of preparing a coloring agent particle dispersion A dispersion of colorant particles can be prepared by dispersing a colorant in an aqueous medium. The dispersion of the colorant is preferably carried out in an aqueous medium with a surfactant concentration equal to or greater than the critical micelle concentration (CMC) to ensure uniform dispersion of the colorant. Various known dispersers can be used for the dispersion of the colorant.

[0099] (Surfactants) Examples of surfactants include anionic surfactants such as alkyl sulfate esters, polyoxyethylene (n) alkyl ether sulfates, alkylbenzene sulfonates, α-olefin sulfonates, and phosphate esters; amine salts such as alkylamine salts, amino alcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; cationic surfactants of the quaternary ammonium salt type such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives; and amphoteric surfactants such as alanine, dodecyldi(aminoethyl)glycine, di(octylaminoethyl)glycine, and N-alkyl-N,N-dimethylammonium betaine. In addition, anionic surfactants and cationic surfactants having fluoroalkyl groups can also be used.

[0100] In this colorant particle dispersion preparation process, the dispersion diameter of the colorant particles in the prepared colorant particle dispersion is preferably in the range of 10 to 300 nm in terms of volume-based median diameter. The volume-based median diameter of the colorant particles in this colorant particle dispersion is measured using an electrophoretic light scattering photometer "ELS-800 (manufactured by Otsuka Electronics Co., Ltd.)".

[0101] (2) Steps to prepare resin particle dispersions (for core / shell) Methods for dispersing the binder resin in an aqueous medium include direct aqueous dispersion, dissolution-emulsification-desolvation, and transfer emulsification. The aforementioned aqueous direct dispersion method involves dispersing the binder resin in an aqueous medium to which a surfactant has been added, using methods such as ultrasonic dispersion or bead mill dispersion. The aforementioned dissolution-emulsification-desolvation method involves dissolving a binder resin in a solvent, dispersing it in an aqueous medium to form emulsion particles (oil droplets), and then removing the solvent.

[0102] In this binder resin particle dispersion preparation process, the average particle size of the binder resin particles obtained is preferably in the range of 50 to 500 nm in terms of volume-based median diameter. The volume-based median diameter was measured using "UPA-EX150" (manufactured by Microtrac-Bell).

[0103] A dispersion of binder resin particles for the core can be prepared by polymerization treatment as follows. Specifically, first, an aqueous medium containing a surfactant at or below the critical micelle concentration (CMC) is prepared. Next, a solution is added to the aqueous medium in which polymerizable monomers for forming the binder resin are dissolved or dispersed, along with toner components such as release agents and charge control agents as needed. Then, mechanical energy is applied to form droplets. After that, a water-soluble radical polymerization initiator is added to allow the polymerization reaction to proceed within the droplets, thereby preparing a resin particle dispersion for the core. Furthermore, the droplets may contain an oil-soluble polymerization initiator. In such a core resin particle dispersion preparation process, a process of applying mechanical energy to emulsify (form droplets) is essential. Examples of means for imparting mechanical energy include homomixers, ultrasonic devices, and means for imparting strong stirring or ultrasonic vibration energy such as mantongorin.

[0104] The binder resin particle dispersion for the shell can be prepared by polymerization treatment in the same manner as the binder resin particle dispersion for the core.

[0105] In the preparation process for the resin particle dispersion for the core / shell, the surfactant used can be, for example, the same surfactant as described above.

[0106] (Polymerization initiator) Various known polymerization initiators can be used as polymerization initiators in this process. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetraline hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetate-tert-hydroperoxide, tert-butyl performate, tert-peracetic acid Examples include peroxides such as butyl, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, and tert-butyl perN-(3-toluyl)palmitate; and azo compounds such as 2,2′-azobis(2-amidinopropane) hydrochloride, 2,2′-azobis-(2-amidinopropane) nitrate, 1,1′-azobis(1-methylbutyronitrile-3-sodium sulfonate), 4,4′-azobis-4-cyanovaleric acid, and poly(tetraethylene glycol-2,2′-azobisisobutyrate). Among these, water-soluble polymerization initiators such as ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, 2,2′-azobis(2-amidinopropane) hydrochloride, 2,2′-azobis-(2-amidinopropane) nitrate, 1,1′-azobis(1-methylbutyronitrile-3-sodium sulfonate), and 4,4′-azobis-4-cyanovaleric acid can be preferably used.

[0107] Additionally, redox polymerization initiators such as persulfates and metabisulfites, or hydrogen peroxide and ascorbic acid can be used as polymerization initiators.

[0108] (Chain transfer agent) The chain transfer agent is not particularly limited and examples include alkyl mercaptans and mercapto fatty acid esters.

[0109] (3) A process to form aggregated particles as core particles by mixing a colorant particle dispersion and a core resin particle dispersion under reduced pressure to obtain an agglomeration resin particle dispersion, and agglomerating and fusing the colorant particles and core resin particles in the presence of a flocculant (aggregation and fusing process). This process, as described above, involves agglomerating and fusing the colorant particles and core resin particles contained in the dispersion formed in the previous process in an aqueous medium under reduced pressure. In this process, the core resin particle dispersion and the colorant particle dispersion are added to the aqueous medium to agglomerate and fuse these particles.

[0110] The specific method for agglomerating and fusing the colorant particle dispersion and the core resin particle dispersion is as follows: A flocculant is added to an aqueous medium to a concentration above the critical flocculation concentration. Next, the medium is heated to a temperature above the glass transition temperature of the core resin particles and above the melting peak temperature of the release agent. This promotes salting out of the colorant particles and the core resin particles while simultaneously promoting fusion. When the particles have grown to the desired size, a flocculation inhibitor is added to stop particle growth, and heating is continued as needed to control the particle shape.

[0111] (Flocculant) The flocculant used is not particularly limited, but one selected from metal salts is preferably used. Examples of metal salts include monovalent metal salts such as alkali metal salts like sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; and trivalent metal salts such as iron and aluminum. Specific examples of metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among these, divalent metal salts are particularly preferred because they can promote aggregation even in small amounts and their aggregation properties are easily controlled. These can be used individually or in combination of two or more.

[0112] If a surfactant is used in this process, for example, one similar to the surfactant described above can be used.

[0113] (4) A process (aggregation and fusion process) in which a dispersion of shell resin particles containing binding resin particles for the shell is added to a dispersion containing core particles under reduced pressure, and the shell particles are aggregated and fused to the surface of the core particles to form toner matrix particles with a core-shell structure. This process, similar to the process in (3) in which colorant particles and core resin particles are aggregated and fused together in the presence of a flocculant to form aggregated particles as core particles (aggregation and fusion process), involves aggregating and fusing shell particles onto the surface of the core particles under reduced pressure to form toner matrix particles with a core-shell structure.

[0114] (5) A process to filter out toner matrix particles from the toner matrix particle dispersion (toner matrix particle dispersion) and remove surfactants, etc. (filtration and washing process) (6) Drying process for toner matrix particles (drying process) The filtration, washing, and drying processes can be carried out using various known methods.

[0115] (7) External additive treatment process A mechanical mixing device can be used in this process. Examples of mechanical mixing devices include Henschel mixers, Nauter mixers, and Turbuler mixers. Among these, a mixing device that can apply shear force to the particles being processed, such as a Henschel mixer, can be used, and the mixing process can be performed by increasing the mixing time or increasing the rotational speed of the stirring blades. Furthermore, when using multiple types of external additives, all external additives may be mixed with the toner matrix particles at once, or they may be mixed in multiple stages depending on the type of external additive. The method for mixing external additives allows for the control of the degree of disintegration and adhesion strength of the external additives by controlling the mixing intensity, i.e., the peripheral speed of the stirring blades, mixing time, or mixing temperature, using the mechanical mixing device described above. [Examples]

[0116] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, the operations were carried out at room temperature (25°C). Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively.

[0117] [Preparation of materials] <Preparation of colorant particle dispersion [Bk]> 90 parts by mass of n-dodecyl sodium sulfate were dissolved by stirring in 1600 parts by mass of deionized water, and while stirring this solution, 420 parts by mass of carbon black "Mogul L" (manufactured by Cabot, pH 2, room temperature 25°C) were gradually added. Next, the mixture is dispersed using the "Creamix" stirring device (manufactured by M-Technique Co., Ltd.). This process prepared a dispersion of colorant microparticles [Bk] in which carbon black particles were dispersed. The particle size of the colorant microparticles in this dispersion was measured using a Microtrac particle size distribution analyzer "UPA-150" (manufactured by Nikkiso Co., Ltd.), and the median diameter based on volume was 85 nm.

[0118] <Preparation of a dispersion of crystalline polyester resin fine particles [1]> (Synthesis of crystalline polyester resin (1)) In a 5L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen introduction device, 153g of dodecanediol as a polycarboxylic acid and 60g of 1,4-butanediol as a polyhydric alcohol were charged. Next, the internal temperature was raised to 190°C over one hour while stirring. After confirming that the mixture was uniformly stirred, Ti(OBu)4 was added as a catalyst in an amount of 0.003% by mass relative to the amount of polycarboxylic acid charged. Next, while distilling off the generated water, the internal temperature was raised from 190°C to 240°C over 6 hours, and the dehydration condensation reaction was continued at 240°C for another 6 hours to polymerize and obtain crystalline polyester resin (1). Crystalline polyester resin (1) had a melting point of 72°C and a weight-average molecular weight (Mw) of 15,000.

[0119] (Weight average molecular weight measurement) Using a GPC instrument "HLC-8220" (manufactured by Tosoh Corporation) and a column "TSKguardcolumn+TSKgelSuperHZM-M3" (manufactured by Tosoh Corporation), tetrahydrofuran (THF) was flowed at a rate of 0.2 mL / min as a carrier solvent while maintaining the column temperature at 40°C. 10 μL of the sample solution was injected into the instrument, detected using a refractive index detector (RI detector), and the molecular weight distribution of the sample was determined by calculating it using a calibration curve measured with monodisperse polystyrene standard particles.

[0120] (Measuring the melting point of crystalline resins) The melting point of the crystalline resin was measured using a differential scanning calorimetry system "Diamond DSC" (manufactured by PerkinElmer). Specifically, 3.0 mg of the sample was sealed in an aluminum pan and set in a holder, with an empty aluminum pan set as a reference. A DSC curve was obtained under the following measurement conditions (heating and cooling conditions): a first heating process where the temperature was raised from 0°C to 200°C at a heating rate of 10°C / min, a cooling process where the temperature was cooled from 200°C to 0°C at a cooling rate of 10°C / min, and a second heating process where the temperature was raised from 0°C to 200°C at a heating rate of 10°C / min. Based on this DSC curve, the endothermic peak top temperature derived from the crystalline polyester during the first heating process was defined as the melting point.

[0121] (Preparation of a dispersion of crystalline polyester resin fine particles [1]) 200 g of crystalline polyester resin (1) was dissolved in 200 g of ethyl acetate. While stirring this solution, an aqueous solution prepared by dissolving sodium polyoxyethylene lauryl ether sulfate in 800 g of deionized water to a concentration of 1% by mass was slowly added dropwise. After removing the ethyl acetate from this solution under reduced pressure, the pH was adjusted to 8.5 with ammonia. Next, by adjusting the solid content concentration to 20% by mass, a crystalline polyester resin fine particle dispersion [1] was prepared in which fine particles of crystalline polyester resin (1) were dispersed in an aqueous medium. The volume-based median diameter of the fine particles in crystalline polyester resin (1) was 200 nm.

[0122] <Preparation of Styrene-Acrylic Resin Fine Particle Dispersion [A]> A dispersion of styrene-acrylic resin fine particles [A], in which binder resin fine particles containing an internal additive are dispersed, was prepared by the following first-stage polymerization to third-stage polymerization.

[0123] (1) First-stage polymerization In a 5L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device, 4g of sodium polyoxyethylene(2) dodecyl ether sulfate and 3000g of deionized water were charged. The resulting mixture was heated to 80°C while being stirred at a rate of 230 rpm under a nitrogen stream. After heating, a solution of 10g of potassium persulfate dissolved in 200g of deionized water was added to the mixture to bring the mixture temperature to 75°C. A monomer mixture of the following composition was then added dropwise to the mixture over 1 hour. Subsequently, the mixture was heated and stirred at 75°C for 2 hours to polymerize the monomers and prepare a dispersion of resin particles [a1]. Styrene 486g Methacrylic acid 76g 2-ethylhexyl acrylate 181g

[0124] (2) Second stage polymerization A 5L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device was charged with a solution of 2g of sodium polyoxyethylene(2) dodecyl ether sulfate dissolved in 3000g of deionized water, and the resulting mixture was heated to 80°C. On the other hand, a solution was prepared by dissolving monomers with the following composition at 80°C. Resin particles [a1] 42g (based on solid content) Behenyl behenate 70g Styrene 195g n-butyl acrylate 91g Methacrylic acid 20g n-octyl mercaptan 3g

[0125] Subsequently, the solution was added to the above mixture, and the mixture was mixed and dispersed for 1 hour using a mechanical disperser "CLEARMIX" (manufactured by M-Technique Co., Ltd.) with a circulation path, thereby preparing a dispersion containing emulsion particles (oil droplets). Next, an initiator solution was prepared by dissolving 5 g of potassium persulfate in 100 g of deionized water, and this was added to the dispersion. The resulting dispersion was heated and stirred at 80°C for 1 hour to polymerize the monomer, thereby preparing a dispersion of resin particles [a2].

[0126] (3) Third-stage polymerization To the dispersion of the resin particles [a2] described above, a solution of 10 g of potassium persulfate dissolved in 200 g of deionized water was added. The resulting dispersion was maintained at 80°C, and a monomer mixture of the following composition was added dropwise to the dispersion over 1 hour. After the addition was complete, the monomers were polymerized by heating and stirring the resulting dispersion for 2 hours. Subsequently, the dispersion was cooled to 28°C to prepare a styrene-acrylic resin fine particle dispersion [A] as a dispersion of resin fine particles for the core. Styrene 298g n-butyl acrylate 137g n-stearyl acrylate 50g Methacrylic acid 64g n-octyl mercaptan 6g

[0127] <Preparation of Styrene-Acrylic Resin Fine Particle Dispersion [B]> Styrene-acrylic resin fine particle dispersion [B] was prepared in the same manner as the first polymerization step of the preparation of styrene-acrylic resin fine particle dispersion [A], except that the following changes were made to the formulation. Styrene 486g n-butyl acrylate 265g

[0128] Preparation of Styrene-Acrylic Resin Fine Particle Dispersion [C] Styrene-acrylic resin fine particle dispersion [C] was prepared in the same manner as the first polymerization step of the preparation of styrene-acrylic resin fine particle dispersion [A], except that the following changes were made to the formulation. Styrene 568g n-butyl acrylate 164g Methacrylic acid 68g

[0129] <Preparation of amorphous polyester resin fine particle dispersion [A]>: Preparation of resin fine particle dispersion for shells (Synthesis of amorphous polyester resin) The raw material monomers and radical polymerization initiators for the following addition polymerization resin (styrene-acrylic resin: StAc), which contain both reactive monomers, were placed in a dropper funnel. 80 parts by mass of styrene n-butyl acrylate 20 parts by mass Acrylic acid 10 parts by mass Polymerization initiator (di-t-butyl peroxide) 16 parts by mass

[0130] Furthermore, the raw material monomers for the polycondensation resin (amorphous polyester resin) described below were placed in a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve them. Bisphenol A propylene oxide 2-mol adduct 285.7 parts by mass Terephthalic acid 66.9 parts by mass Fumaric acid 47.4 parts by mass

[0131] Next, while stirring the dispersion containing the polycondensation resin, the raw material monomers for the addition polymerization resin (StAc) were added dropwise over 90 minutes, and after aging for 60 minutes, unreacted addition polymerization monomers were removed under reduced pressure (8 kPa). Subsequently, 0.4 parts by mass of Ti(OBu)4 were added as an esterification catalyst, the temperature was raised to 235°C, and the reaction was carried out under normal pressure (101.3 kPa) for 5 hours, followed by a further reaction under reduced pressure (8 kPa) for 1 hour. Next, after cooling to 200°C, the reaction was carried out under reduced pressure (20 kPa) until the desired softening point was reached. Next, the solvent was removed to obtain an amorphous resin, the shell layer resin (s1). The obtained amorphous polyester resin for the shell layer (s1) had a glass transition temperature (Tg) of 65°C and a weight-average molecular weight (Mw) of 35,000.

[0132] (Preparation of amorphous polyester resin fine particle dispersion) 100 parts by mass of the obtained amorphous polyester resin for the shell layer (s1) was dissolved in 400 parts by mass of ethyl acetate (manufactured by Kanto Chemical Co., Ltd.) and mixed with 638 parts by mass of a 0.26% by mass sodium lauryl sulfate solution. The mixture was ultrasonically dispersed for 30 minutes at V-LEVEL 300 μA using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho) while stirring. Then, with the mixture heated to 40°C, ethyl acetate was completely removed under reduced pressure for 3 hours using a diaphragm vacuum pump "V-700" (manufactured by BUCHI). This prepared an amorphous polyester resin fine particle dispersion [A] for shells with a solid content of 13.5% by mass. At this time, the median diameter of the particles contained in the amorphous polyester resin fine particle dispersion [A] was 140 nm by volume.

[0133] <Preparation of amorphous polyester resin fine particle dispersion [B]>: Preparation of resin fine particle dispersion for shells The following materials were placed in a 10-liter four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and a condensation polymerization reaction was carried out at 230°C for 8 hours. Bisphenol A propylene oxide 2-mol adduct 250 parts by mass Terephthalic acid 58.5 parts by mass Fumaric acid 41.5 parts by mass Esterification catalyst (tin octylate) 1 part by mass Furthermore, the reaction was carried out at 2 kPa for 2 hours and cooled to 160°C to obtain a binder resin made of polyester resin. The obtained binder resin was dissolved in 50 parts by mass and 200 parts by mass of ethyl acetate (manufactured by Kanto Chemical Co., Ltd.). Then, it was mixed with 319 parts by mass of a pre-prepared 0.26% by mass sodium lauryl sulfate solution and ultrasonically dispersed for 30 minutes at V-LEVEL 300 μA using an ultrasonic homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho) while stirring. Subsequently, the ethyl acetate was completely removed by stirring under reduced pressure for 3 hours using a diaphragm vacuum pump "V-700" (manufactured by BUCHI Co., Ltd.) while the mixture was heated to 40°C. This prepared a dispersion of binder resin particles (amorphous polyester resin fine particle dispersion [B]) with a solid content of 13.5% by mass. At this time, the particles contained in amorphous polyester resin fine particle dispersion [B] had a median diameter of 160 nm by volume.

[0134] [Toner production] <Preparation of core-shell particles [1] (aggregation and fusion process)> A 5L reaction vessel was prepared, equipped with a stirrer, temperature sensor, cooling tube, vacuum pump (BUCHI V-700 diaphragm pump), and air introduction device. For the temperature sensor, a Toyo Technica PT-100 platinum temperature resistance sensor was installed at the bottom of the reaction vessel, and a thermocouple was installed at the top of the reaction vessel. As a method for controlling the reduced pressure, a PLC was used to monitor the gas phase temperature at the top of the reaction vessel. When a predetermined temperature was reached, air was introduced, and the introduction of air was stopped when the vapor pressure inside the reaction vessel became 3 kPa higher than the vapor pressure at the liquid temperature. This process was repeated throughout the reaction. In addition, air was continuously blown into the reaction vessel. This allowed for an efficient reduction in the amount of aromatic compounds. The amount of air continuously supplied to the reaction vessel was 1.0 m³. 3 I used / s. Vacuum control was performed from the start of heating until the end of maturation, except when the materials were added to the reaction vessel. Specifically, as described below, vacuum control was started from the point when heating began after the addition of the magnesium chloride aqueous solution. Vacuum control was also terminated when the average circularity of the core-shell particles [1] reached 0.960 (end of maturation). In the preparation of core-shell particles [1], the vapor pressure of the gas phase inside the reaction vessel was controlled to be 8 kPa lower than the saturated vapor pressure at the liquid temperature. The specific procedure for the aggregation and fusion process is shown below.

[0135] 360 g (based on solid content) of styrene-acrylic resin fine particle dispersion [A] (resin fine particle dispersion for cores), 45 g of crystalline polyester resin fine particle dispersion [1], 1100 g of ion-exchanged water, and 40 g of colorant fine particle dispersion [Bk] were charged into a reaction vessel. After adjusting the temperature of the resulting dispersion to 30°C, a 5N sodium hydroxide aqueous solution was added to the dispersion to adjust the pH to 10 at room temperature of 25°C. Next, an aqueous solution prepared by dissolving 60 g of magnesium chloride in 60 g of deionized water was added to the dispersion under stirring at 30°C for 10 minutes. After adding the dispersion, the dispersion was held at 30°C for 3 minutes before the temperature was increased. The dispersion was heated to 85°C over 60 minutes, and the particle growth reaction was continued while maintaining the temperature of the dispersion at 85°C to prepare the core particle dispersion. 45 g (based on solid content) of amorphous polyester resin fine particle dispersion [A] (resin fine particles for shells) was added to the core particle dispersion, and stirring was continued at 80°C for 1 hour. The resin fine particles for shells were fused to the surface of the core particles [1] to form a shell layer and obtain resin particles [1]. Here, an aqueous solution of 150 g of sodium chloride dissolved in 600 g of deionized water was added to the obtained dispersion, and the mixture was aged at a liquid temperature of 80°C. When the average circularity of the core-shell particles [1] reached 0.960, the mixture was cooled to 30°C to obtain core-shell particles [1]. The volume-based median diameter of the core-shell particles [1] after cooling was 5.5 μm.

[0136] (Measurement of median diameter based on the number of core-shell particles) The median diameter based on the number of core-shell particles is the median diameter in the particle size distribution. This median diameter can be measured and calculated using a device that connects a data processing computer system to a "Multisizer 3 (manufactured by Beckman Coulter)". The measurement procedure involves mixing 0.02 g of core-shell particles with 20 mL of surfactant solution, followed by ultrasonic dispersion for 1 minute to prepare a core-shell particle dispersion. The surfactant solution is, for example, a surfactant solution obtained by diluting a neutral detergent containing surfactant components 10 times with pure water, for the purpose of dispersing the core-shell particles.

[0137] The aforementioned core-shell particle dispersion was pipetteed into a beaker containing the ISOTON II (Beckman Coulter) in the sample stand until the concentration reached 5-10%. This concentration range ensures reproducible measurements. The particle count was then set to 25,000, the aperture diameter of the Multisizer 3 (Beckman Coulter) was set to 100 μm, and the frequency was calculated by dividing the measurement range of 1-30 μm into 256 sections. The particle size representing the 50% largest cumulative particle fraction was used as the median diameter based on particle count.

[0138] (Average circularity of core-shell particles) The average circularity of core-shell particles was measured using the flow-type particle image analyzer "FPIA-3000" (Sysmex). Specifically, core-shell particles were wetted in an aqueous surfactant solution and dispersed by ultrasonic dispersion for 1 minute. Then, measurements were taken using the "FPIA-3000" in HPF (high magnification imaging) mode at an appropriate concentration with an HPF detection count of 3000 to 10000 particles. Reproducible measurements can be obtained within this range. Circularity was calculated using the following formula. Formula: Circularity of core-shell particle = (Perimeter of a circle with the same projection area as the particle image) / (Perimeter of the particle projection image) Here, the average circularity is the arithmetic mean obtained by summing the circularity of each particle and dividing by the total number of particles measured.

[0139] <Preparation of toner matrix particles [1] (washing and drying process)> The dispersion of core-shell particles [1] generated in the aggregation and fusion process was separated into solid and liquid components using a centrifuge to form a wet cake of core-shell particles [1]. The wet cake was washed with deionized water at 35°C using the centrifuge until the electrical conductivity of the filtrate was 5 μS / cm. Then, it was transferred to a "Flash Jet Dryer" (manufactured by Seishin Corporation) and dried until the moisture content was 0.8% by mass to produce toner matrix particles [1].

[0140] <Preparation of toner [1] (external additive treatment process)> To the obtained toner matrix particles [1], 1% by mass of hydrophobic silica particles and 1.2% by mass of hydrophobic titanium oxide particles were added. The mixture was mixed for 20 minutes using a Henschel mixer at a rotor blade speed of 24 m / s, and the external additive was added by passing the mixture through a 400-mesh sieve. The hydrophobic silica particles have a number-average secondary particle size of 30 μm and a number-average primary particle size of 50-200 nm. The hydrophobic titanium oxide particles have a number-average secondary particle size of 20 μm and a number-average primary particle size of 50-200 nm.

[0141] <Preparation of toner [2]> Toner [2] was produced in the same manner as toner [1], except that in the aggregation and fusion process of toner [1], the vapor pressure of the gas phase inside the reaction vessel was changed to be 3 kPa lower than the saturated vapor pressure at the liquid temperature.

[0142] <Preparation of toner [3]> In the preparation of toner [1], 450 g (solid content equivalent) of styrene-acrylic resin fine particle dispersion [B] was used as the core resin fine particle dispersion instead of 360 g (solid content equivalent) of styrene-acrylic resin fine particle dispersion [A]. Furthermore, crystalline polyester resin fine particle dispersion [1] and amorphous polyester resin fine particle dispersion [A], which is the resin fine particle for the shell, were not used as shown in Table I below. Furthermore, toner [3] was produced in the same manner as toner [1], except that in the aggregation and fusion process of toner [1], the vapor pressure of the gas phase inside the reaction vessel was changed to be 3 kPa lower than the saturated vapor pressure at the liquid temperature.

[0143] <Preparation of toner [4]> In the preparation of toner [1], styrene-acrylic resin fine particle dispersion [C] was used instead of styrene-acrylic resin fine particle dispersion [A] as the core resin fine particle dispersion. Furthermore, amorphous polyester resin fine particle dispersion [B] was used instead of amorphous polyester resin fine particle dispersion [A] as the shell resin fine particle dispersion. The amount of amorphous polyester resin fine particle dispersion [B] added was as shown in Table I below. Furthermore, toner [4] was produced in the same manner as toner [1], except that in the aggregation and fusion process of toner [1], the vapor pressure of the gas phase inside the reaction vessel was changed to be 3 kPa lower than the saturated vapor pressure at the liquid temperature.

[0144] <Preparation of toner [5]> In the preparation of toner [1], the amounts of styrene-acrylic resin fine particle dispersion [A] and crystalline polyester resin fine particle dispersion [1] added were as shown in Table I below. Furthermore, amorphous polyester resin fine particle dispersion [B] was used instead of amorphous polyester resin fine particle dispersion [A] as the resin fine particle dispersion for the shell, with the same amount added. Furthermore, toner [5] was produced in the same manner as toner [1], except that in the aggregation and fusion process of toner [1], the vapor pressure of the gas phase inside the reaction vessel was changed to be 3 kPa lower than the saturated vapor pressure at the liquid temperature.

[0145] <Preparation of toner [6]> Toner [6] was produced in the same manner as toner [1], except that in the aggregation and fusion process of toner [1], the vapor pressure of the gas phase inside the reaction vessel was changed to be 0.01 kPa lower than the saturated vapor pressure at the liquid temperature.

[0146] <Preparation of toner [7]> Toner [7] was manufactured in the same manner as above, except that the following washing and drying steps were performed as part of the washing and drying process, without applying reduced pressure during the aggregation and fusion process of toner [1]. (Washing and drying process) The dispersion of core-shell particles generated in the aggregation and fusion process was separated into solid and liquid components using a centrifuge to form a wet cake of core-shell particles. The wet cake was washed with deionized water at 35°C using a centrifuge until the electrical conductivity of the filtrate was 5 μS / cm. After that, it was placed in a shelf dryer and left to dry for 12 hours.

[0147] <Preparation of toner [8]> Toner [8] was produced in the same manner as toner [1], except that the vapor pressure of the gas phase inside the reaction vessel was changed to be 5 kPa lower than the saturated vapor pressure at liquid temperature during the aggregation and fusion process of toner [1]. The amount of air continuously supplied to the reaction vessel was 1.0 m³. 3 / s to 1.6m 3 Changed to / s

[0148] <Preparation of toner [9]> Toner [7] was prepared in the same manner as toner [9], except that the drying time was changed from 12 hours to 1 hour.

[0149] <Preparation of toner

[10] > Toner

[10] was produced in the same manner as toner [1], except that in the aggregation and fusion process of toner [1], the vapor pressure of the gas phase inside the reaction vessel was changed to be 8.1 kPa lower than the saturated vapor pressure at the liquid temperature.

[0150] <Preparation of toner

[11] > Toner

[11] was prepared in the same manner as in the aggregation and fusion process of toner [1], except that the pressure was not reduced.

[0151] <Preparation of developer [1] to

[11] > Two-component developers [1] to

[11] were prepared for toners 1 to 11 prepared as described above, as shown below. A ferrite carrier with a volume-average particle size of 40 μm was prepared by coating it with a copolymer resin of cyclohexyl methacrylate and methyl methacrylate (monomer mass ratio = 1:1). Next, the two components of the toner were mixed in a ratio of 6 parts by mass to 100 parts by mass of the carrier to prepare two-component developers [1] to

[11] . The mixing was carried out for 30 minutes using a V-type mixer.

[0152] [Content of aromatic compounds and ester compounds] The aromatic compounds and ester compounds in the toner obtained above were quantified using the headspace method described above. The quantification results are shown in the table below. The aromatic compound content shown in the table below is the sum of the content of benzene, styrene, ethylbenzene, naphthalene, toluene, cumene, α-methylstyrene, acetophenone, and benzaldehyde. The ester compound content shown in the table below is the sum of the content of butyl acetate, butyl 2-propenoate, butyl propanoate, butyl butanoate, 9-octadecenoic acid (Z)-phenylmethyl ester, and n-butyl ester. (i) Sample collection A 100 mg toner sample was collected in a 10 mL headspace vial (AGILENT vial). The sample was weighed to the nearest 0.1 mg. The vial was sealed at the septum using a dedicated crimper.

[0153] (ii) Heating of the sample and injection into the gas chromatograph The vial containing the sample was placed in a heating furnace / autosampler (Hewlett-Packard HEAD SPACE SAMPLER HP7694). The sample was placed upright in the 170°C heating furnace, and after 10 minutes, 5 μL of the gas phase from the vial was sampled and injected into a gas chromatograph.

[0154] (iii) Setting the chromatographic isolation state A J&W GC column DB-624 (length 30 m, inner diameter 0.25 mm, film thickness 1.40 μm) manufactured by Agilent Technologies was used as the separation column. The separation column was mounted on a gas chromatograph (Hewlett-Packard 5890 SERIES II) and He was flowed through it at a rate of 2 ml / min. After holding the separation column temperature at 40°C for 2 minutes, measurements were taken while increasing the temperature to 230°C at a rate of 10°C / min. The injection temperature was 230°C and the FID detection side temperature was 230°C.

[0155] (iv) Creation of a calibration curve Toluene-acetone solutions prepared to 1000 ppm were collected in 0, 1, 2, 4, 10, 20, and 25 μL portions using a syringe and divided into 10 ml vials. Analysis was performed in the same manner as in (ii) and (iii) above, and calibration curves were created for the amount of toluene injected and the peak area.

[0156] (v) calculation The amounts of aromatic compounds and ester compounds in the toner were calculated by converting the total area of ​​the peaks detected between the retention times of n-hexane and n-hexadecane using the toluene calibration curve described above.

[0157] (vi) The following equipment configuration was used. (a) Headspace conditions Headspace device: S-trap HS (manufactured by JEOL Ltd.) Temperature conditions: Transfer line: 180℃ Loop temperature: 180℃ Sample volume: 100 mg / 20 mL vial

[0158] (b)GC / MS conditions GC:7890B (manufactured by Agilent) MS:JMS-Q1500GC (manufactured by JEOL Ltd.) Column: SH-I-624Sil (manufactured by SHIMADZU, 30m x inner diameter 0.25mm) Oven temperature Initial temperature: 40℃ (holding time 2 minutes) Temperature increase rate: 10°C / min Reached temperature: 230°C (holding time 14 min) m / z capture range: 20 - 300

[0159] [Evaluation] Using a commercially available multifunction machine, printing was performed using the above toner, and evaluation was conducted on low-temperature fixing property, hot offset resistance, image quality, and charge amount change after standing in a high-temperature and high-humidity environment.

[0160] [Low-temperature fixing property (tape peeling test)] A solid image with a toner adhesion amount of 10.0 mg / 10 cm was output onto a biaxially stretched polypropylene film with a thickness of 40 μm. 2 After leaving the obtained printed matter for 1 day, cellophane tape cut into 1 cm×1 cm strips was attached to the printed surface at 3 cm intervals. The state of the appearance of the toner image layer when this cellophane tape was rapidly peeled off, that is, the remaining rate of the toner image layer, was determined as follows. In the following criteria, "A", "B", and "C" were considered to have no problems in use (passing criteria). The remaining rate of the toner image layer was calculated from the density difference of the photographed image by photographing the toner image layer after peeling the cellophane tape with respect to the entire area where the cellophane tape was attached. [Criteria] A: 90% or more and 100% or less of the toner image layer remained on the film B: 80% or more and less than 90% of the toner image layer remained on the film C: 60% or more and less than 80% of the toner image layer remained on the film D: Less than 60% of the toner image layer remained on the film[[ID=3...]]

[0161] [Hot offset resistance] Two solid images were output, and the two obtained fixed images were overlapped with the image parts facing each other so that the non-image part and the image part overlapped. For the overlapped part, 8... 2Weights were placed on top to achieve a suitable level, and the images were left in a constant temperature and humidity chamber at 60°C and 50% humidity for three days. After this period, the two stacked fixed images were separated, and the degree of image loss was categorized according to the evaluation criteria below. This was used to evaluate the document offset resistance. In the criteria below, images rated "A" and "B" are considered to have document offset resistance and are judged to be acceptable. (standard) A: No image loss or image migration is observed in either the image or non-image areas. B: When separating the two overlapping images, there is a crisp sound and slight image transfer is visible in the non-image areas, but there is no image loss and it is at a level that does not pose any problems. C: When separating two superimposed images, image distortion and gloss reduction occur on the surface of each fixed image. A transition is observed in the non-image area.

[0162] <Image Quality> Evaluation paper: POD glossy paper 128g / m² 2 A test image consisting of a gradient image chart ranging from a 100% solid image patch (2 x 5 cm) to a 10% solid image patch was printed on a sheet of paper (manufactured by Nippon Paper Industries). This test image was captured as electronic data using a scanner "ES8500" (manufactured by Epson Corporation) and "Adobe Photoshop 6.0". The GI value (Graniness Index) was then calculated using the granularity measurement software "GI-es-8500AAC". Furthermore, a lower GI value indicates higher image quality, and in this invention, a value of 0.25pt or less is considered acceptable and practically acceptable. Here, "pt" represents the unit of the GI value calculated using the above-mentioned granularity software and is referred to as "points." (standard) A: GI value of 0.22 or less B: GI value between 0.23 and 0.25 C:GI value of 0.26 or higher

[0163] <Changes in electrostatic charge after being left unattended in a high-temperature, high-humidity environment (HH environment)> Under high temperature and high humidity conditions (temperature 30°C, humidity 80%RH), 20g of developer was placed in a 20mL glass container. After standing at room temperature for one week, the glass container was shaken for one minute at 200 times per minute, with a shaking angle of 45° and an arm length of 50cm. Then, 1g of developer was taken and its charge was measured by the blow-off method. This value was designated as Q1. Subsequently, the developer was placed in a vacuum dryer set to 50°C and left for 5 days to perform an accelerated test. After that, the developer was removed and its charge after the accelerated test was measured by the blow-off method. This value was designated as Q2. The rate of decrease in the Q / M retention rate before and after the accelerated test was calculated using the following formula. The obtained Q / M retention rate was evaluated according to the following evaluation criteria. "A" and "B" in the following criteria were considered passing levels. • Q / M maintenance rate (%) = (Q2 / M) / (Q1 / M) × 100 (standard) A: Maintenance rate of 95% or higher B: Maintenance rate is between 90% and 95% C: Maintenance rate less than 90%

[0164] [Table 1]

[0165] [Table 2]

[0166] As shown in the results above, the toner of the present invention is superior to the toner of the comparative example in terms of low-temperature fixing properties and resistance to hot offset, produces high image quality, and can obtain the desired charge amount even in high-temperature and high-humidity environments.

Claims

1. The aromatic compound content is 0.1 to 30 mg / kg. A toner for developing electrostatic images, characterized by the following features.

2. The aromatic compound is at least one of benzene, styrene, ethylbenzene, naphthalene, toluene, cumene, and α-methylstyrene. When the aromatic compound is considered as 1, the ester compound is contained in a mass ratio within the range of 0.08 to 0.

40. The electrostatic image developing toner according to feature 1.

3. It contains styrene-acrylic resin as a binder. A toner for developing electrostatic images according to claim 1 or 2.

4. It contains polyester resin as a binder. A toner for developing electrostatic images according to claim 1 or claim 2, characterized in that...

5. A method for manufacturing a toner for electrostatic image development according to claim 1 or claim 2, The process includes a step of introducing an aqueous dispersion containing at least resin particles and a surfactant into a reaction vessel, and causing the resin particles to aggregate and fuse together. In the step of agglomeration and fusion, after the aqueous dispersion is introduced into the reaction vessel, the inside of the reaction vessel is depressurized, and the resin particles are agglomerated and fused under depressurized conditions. The vapor pressure of the gas phase in the reaction vessel is set to be 0.01 to 8 kPa lower than the saturated vapor pressure of the liquid temperature in the reaction vessel. A method for manufacturing toner for electrostatic image developing, characterized by the features described above.

6. A dispersion of colorant particles is added to the reaction vessel. A method for manufacturing toner for electrostatic image developing according to feature 5.

7. The boiling state in the reaction vessel is detected, and the vapor pressure of the gas phase is controlled. A method for manufacturing toner for electrostatic image developing according to feature 5.

8. As a means for detecting the boiling state, bubbles generated by reduced pressure are detected, and the reduced pressure in the reaction vessel is released. A method for manufacturing toner for electrostatic image developing according to feature 7.

9. As a means for detecting the boiling state, the temperature of the gas phase is detected and the pressure inside the reaction vessel is released. A method for manufacturing toner for electrostatic image developing according to feature 7.

10. By introducing air into the reaction vessel, the pressure inside the reaction vessel is controlled. A method for manufacturing toner for electrostatic image developing according to feature 7.

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