toner

Abstract

To provide a toner that improves the charge build-up speed in high-humidity environments while maintaining improved image quality by suppressing electrostatic adhesion in low-humidity environments. [Solution] A toner comprising toner particles containing amorphous polyester and barium titanate particles present on the surface of the toner particles, The amorphous polyester has a carboxyl group, The barium titanate particles are (i) comprising a barium titanate core and a fatty acid having 6 or more carbon atoms fixed to the surface of the barium titanate core, (ii) The amount of hydroxyl groups measured by titration is 15 μmol / g or more and 1300 μmol / g or less.

Description

[Technical Field]

[0001] The present disclosure relates to a toner for use in electrophotography, electrostatic recording, and the like. [Background Art]

[0002] In image formation by electrophotography, a toner containing toner particles is used, and the toner is used as a one-component developer or mixed with a carrier to form a two-component developer. Toner particles include, for example, toner base particles and an external additive attached to the surface of the toner base particles. As the external additive, for example, barium titanate particles are used. Barium titanate exhibits, for example, a function of stabilizing the charge amount of toner particles in a low-humidity environment. Accordingly, a toner using barium titanate particles can improve image quality after endurance by suppressing an increase in electrostatic adhesive force under a low-humidity environment. Patent Document 1 discusses suppression of excessive charging of an electrostatic charge image developing toner in a low-temperature and low-humidity environment, in a toner including lanthanum-containing barium titanate subjected to hydrophobic treatment as an external additive. Patent Document 2 discusses improvement of fluidity and electrical properties in a toner including, as an external additive, barium titanate produced by reacting titanium hydroxide with a barium compound, performing heat treatment, and then passing through a hydrophobization step. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2021-131520 [Patent Document 2] International Publication No. WO2007 / 086451 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, the aforementioned toner, which uses barium titanate particles as an external additive, had the problem of a slow charge rise rate and a large change in image density under high humidity conditions. [Means for solving the problem]

[0005] This disclosure provides a toner that improves the charge rise speed in high-humidity environments while maintaining improved image quality by suppressing electrostatic adhesion in low-humidity environments. This disclosure relates to a toner comprising toner particles containing amorphous polyester and barium titanate particles present on the surface of the toner particles, The amorphous polyester has a carboxyl group, The barium titanate particles are (i) comprising a barium titanate core and a fatty acid having 6 or more carbon atoms fixed to the surface of the barium titanate core, (ii) The amount of hydroxyl groups measured by titration is between 15 μmol / g and 1300 μmol / g. This relates to a toner characterized by the following features. [Effects of the Invention]

[0006] According to this disclosure, it is possible to provide a toner that can suppress image density changes by improving the charge rise speed in high humidity environments, while maintaining improved image quality by suppressing electrostatic adhesion in low humidity environments. [Brief explanation of the drawing]

[0007] [Figure 1] This is an explanatory diagram of a triboelectric charge measuring device used to measure the charge amount of toner. [Modes for carrying out the invention]

[0008] In this disclosure, unless otherwise specified, the expressions "greater than or equal to XX and less than or equal to XX" or "XX to XX" refer to a numerical range that includes the lower and upper limits. Furthermore, a monomer unit refers to the reacted form of monomer material in a polymer. In addition, toner particles may be referred to as toner matrix particles or toner matrix.

[0009] [Features of this disclosure] The inventors believe the mechanism by which the effects of this disclosure manifest themselves is as follows:

[0010] Our inventors' research has revealed that in order to improve the charge rise at high humidity, it is necessary for the external additive to become charged and for the generated charge to be quickly transferred to the toner matrix.

[0011] However, with conventional barium titanate, the low resistance resulted in a greater effect of charge leakage than charge generation. As a result, charge generation was difficult, and improving the charge rise time was challenging.

[0012] Furthermore, with conventional barium titanate particles, the generated charge is difficult to transfer, resulting in localized charging. This makes it difficult to improve the charging process, as it takes time for the charge to saturate.

[0013] As a result of diligent research by the present inventors, it was discovered that by incorporating amorphous polyester containing a carboxylic acid into the toner matrix particles, and by having a fatty acid with 6 or more carbon atoms and barium titanate having hydroxyl groups of 15 μmol / g to 1300 μmol / g on the toner surface, it is possible to achieve both suppression of electrostatic adhesion in low humidity environments and improvement of charge rise speed in high humidity environments, leading to this disclosure.

[0014] Although the mechanism thereof is not clear, it is believed that an appropriate amount of hydroxy groups present on the surface of barium titanate generates electric charge, and the low resistance of the barium titanate core diffuses the electric charge to toner base particles, thereby improving charging rise in high-humidity environments. Furthermore, it is speculated that allowing a fatty acid to be present on barium titanate and allowing an amorphous polyester having a carboxylic acid to be present in the toner base particles facilitates retention of electric charge in the toner base particles via the interaction between the fatty acid of barium titanate and the carboxylic acid of the toner base particles, thereby improving charging rise in high-humidity environments.

[0015] Additionally, it is believed that in low-humidity environments, since barium titanate has a high dielectric constant, its dielectric relaxation speed is high, and suppressing the apparent charge amount makes it possible to suppress electrostatic adhesion in low-humidity environments.

[0016] The barium titanate particles used in the present disclosure have a fatty acid having 6 or more carbon atoms fixed to the surface of the barium titanate core. When the content falls within the above range, the interaction with the carboxylic acid of the amorphous polyester in the toner base particles improves charging rise in high-humidity environments. When the content falls outside the above range, the interaction with the carboxylic acid of the amorphous polyester decreases, so the effect of the present disclosure cannot be obtained.

[0017] The amount of hydroxy groups in barium titanate, as measured by titration, is 15 µmol / g or more and 1300 µmol / g or less. When the amount falls within the above range, both suppression of electrostatic adhesion in low-humidity environments and improvement of charging rise in high-humidity environments can be achieved.

[0018] When the amount of hydroxy groups is less than 15 µmol / g, electric charge is less likely to be generated in high-humidity environments, so the effect of the present disclosure cannot be obtained. When the amount of hydroxy groups is more than 1300 µmol / g, excessive charging occurs in low-humidity environments, which increases electrostatic adhesion, so the effect of the present disclosure cannot be obtained.

[0019] To reduce the amount of hydroxyl groups, methods include increasing the reaction temperature in the reaction process for the production of barium titanate and increasing the amount of fatty acid added in the fatty acid surface treatment process. To increase the amount of hydroxyl groups, methods include lowering the reaction temperature in the reaction process for the production of barium titanate and decreasing the amount of fatty acid added in the fatty acid surface treatment process.

[0020] [Barium titanate particles] Next, the barium titanate particles used in this disclosure will be described in detail.

[0021] The number-average particle size of the barium titanate particles is preferably between 0.02 μm and 0.12 μm. When the number-average particle size of the barium titanate particles is within the above range, the barium titanate particles and carrier particles come into contact easily, and the effect of improved charge rise is easily obtained. If the number-average particle size of the barium titanate particles is less than 0.02 μm, the barium titanate particles and carrier particles come into contact less easily, and the effect of improved charge rise is difficult to obtain. Also, if the number-average particle size exceeds 0.12 μm, the barium titanate particles may easily detach from the toner matrix particles. The number-average particle size of the barium titanate particles can be reduced by shortening the reaction time in the reaction process for manufacturing barium titanate. Also, the number-average particle size of the barium titanate particles can be increased by lengthening the reaction time in the reaction process for manufacturing barium titanate particles.

[0022] The amount of hydroxyl groups in barium titanate particles, as measured by titration, is between 15 μmol / g and 1300 μmol / g, preferably between 120 μmol / g and 450 μmol / g. When the amount of hydroxyl groups is within this range, it improves the charge rise in high-humidity environments and makes it easier to suppress electrostatic adhesion in low-humidity environments. Furthermore, the amount of hydroxyl groups in barium titanate particles can be increased in the surface treatment process during manufacturing by reducing the amount of surface treatment agent added, lowering the reaction temperature, and shortening the reaction time. Conversely, the amount of hydroxyl groups in barium titanate particles can be decreased in the surface treatment process during manufacturing by increasing the amount of surface treatment agent added, raising the reaction temperature, and lengthening the reaction time.

[0023] Barium titanate particles preferably have a fatty acid with 6 or more carbon atoms attached to the surface of the barium titanate core particles. More preferably, the fatty acid has 12 to 24 carbon atoms, and even more preferably, the fatty acid is stearic acid. Within this range, the interaction with the carboxylic acid of the amorphous polyester increases, improving the charge rise in high humidity environments. When the fatty acid is stearic acid, the interaction is greatest, resulting in an even greater improvement in charge rise in high humidity environments.

[0024] Examples of fatty acids with 6 or more carbon atoms include the following:

[0025] Caproic acid, heptanoic acid, caprylic acid, nonanoic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), nonadecanoic acid, arachidic acid (eicosanic acid), henicosanoic acid, behenic acid (docosanoic acid), tricosanic acid and tetracosanic acid.

[0026] The barium titanate particles preferably contain 0.50% to 5.00% by mass of fatty acids. When the fatty acids contained in the barium titanate particles are within the above range, the interaction with the carboxylic acid of the amorphous polyester increases, allowing for the appropriate generation of charge in a high-humidity environment and improving the charge rise time.

[0027] The fatty acid content of barium titanate particles can be reduced in the fatty acid surface treatment process during the production of barium titanate particles by reducing the amount of fatty acid added, lowering the reaction temperature, and shortening the reaction time. Conversely, the fatty acid content of barium titanate particles can be increased in the fatty acid surface treatment process during the production of barium titanate particles by increasing the amount of fatty acid added, raising the reaction temperature, and lengthening the reaction time.

[0028] When the amount of hydroxyl groups in barium titanate particles is A (μmol / g) and the amount of carboxyl groups of fatty acids fixed to the surface of barium titanate core particles is B (μmol / g), it is preferable that the ratio A / B is between 0.7 and 30.0. Within this range, it is easier to suppress electrostatic adhesion in low humidity environments and to achieve a positive charge build-up effect in high humidity environments.

[0029] The method for producing barium titanate particles used in this disclosure is not particularly limited, but it is preferable to use a wet method such as hydrothermal synthesis that does not involve a calcination step at 100°C or higher. If a calcination step is included, it becomes difficult to achieve a hydroxyl group concentration of 15 μmol / g to 1300 μmol / g.

[0030] The following describes an example of a method for producing barium titanate particles. First, a product obtained by disaccadicating a titanium source with mineral acid (hereinafter sometimes referred to as the disaccadic titanium source product) is mixed with a barium compound. Next, while heating the resulting mixture to a temperature of 50°C or higher, an alkaline aqueous solution is added to the mixture. Then, the mixture with the added alkaline aqueous solution is held at a temperature of 50°C or higher for a predetermined time (for example, 30 minutes to 2 hours). After cooling the resulting product, hydrochloric acid is added to the product to obtain a precipitate. Next, the obtained precipitate is washed and filtered (solid-liquid separation), and the resulting solid is dried to obtain barium titanate particle powder.

[0031] This section describes an example of a method for treating the surface of barium titanate particles with fatty acids. Fatty acids are dissolved in an organic solvent such as toluene, and barium titanate particles are added while stirring. By drying this mixture and evaporating the organic solvent, barium titanate particles with fatty acids adhering to their surface can be obtained.

[0032] The amount of fatty acids adhering to the surface of the barium titanate core can be adjusted, for example, by changing the amount of fatty acids added relative to the mass of the barium titanium particles.

[0033] The barium titanate particle content is preferably 0.10 parts by mass or more and 5.00 parts by mass or less per 100 parts by mass of toner particles. With the above content, the amount of barium titanate particles present on the toner matrix particles becomes appropriate, making it difficult for charge leakage to occur, and thus making it difficult to obtain the effect of improving charge rise at high humidity.

[0034] [Toner particles] Next, the composition of toner particles to which barium titanate particles are added will be described in detail. The toner particles contain a binder resin, and optionally a colorant, wax, etc.

[0035] <Binding resin> The toner particles of this disclosure contain amorphous polyester as a binder resin. In addition to amorphous polyester, the following polymers or resins can also be used.

[0036] For example, monopolymers of styrene and its substituted products such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene-acrylic acid ester copolymers, styrene-methacrylic acid ester copolymers, styrene-α-chloromethacrylate methyl copolymers, styrene-acrylonitrile copolymers, styrene-vinyl methyl ether copolymers, styrene-vinyl ethyl ether copolymers, styrene-vinyl methyl ketone copolymers, and styrene-acrylonitrile-indene copolymers can be used. Polyvinyl chloride, phenolic resins, naturally modified phenolic resins, naturally modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyesters, polyurethanes, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, and petroleum-based resins can be used. Among these, polyester is preferred from the viewpoint of electrostatic stability.

[0037] <Amorphous polyester> The amorphous polyester used in this disclosure must have carboxyl groups from the viewpoint of charge build-up in high humidity environments. The amount of carboxyl groups can be controlled by the acid value in the resin. Preferably, an acid value in the range of 5 mg KOH / g to 20 mg KOH / g is more preferable from the viewpoint of charge build-up in high humidity environments. The acid value can be controlled by the ratio of polycarboxylic acid and polyhydric alcohol and the molecular weight, as described later.

[0038] Amorphous polyesters are obtained by copolymerization of polycarboxylic acids and polyhydric alcohols. Examples of polycarboxylic acids used include the following:

[0039] Examples of divalent carboxylic acids include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, and malonic acid. Of these, maleic acid, fumaric acid, and terephthalic acid are preferred.

[0040] Examples of trivalent or higher carboxylic acids include the following:

[0041] 1,2,4-Benzenetricarboxylic acid, 2,5,7-Naphthalentricarboxylic acid, 1,2,4-Naphthalentricarboxylic acid, 1,2,4-Butanetricarboxylic acid, 1,2,5-Hexanetricarboxylic acid, 1,3-Dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-Cyclohexanetricarboxylic acid, Tetra(methylenecarboxyl)methane, 1,2,7,8-Octanetetracarboxylic acid, Pyromellitic acid, Empol trimeric acid, and their acid anhydrides or their lower alkyl esters, etc.

[0042] Of these, 1,2,4-benzenetricarboxylic acid (i.e., trimellitic acid) or its derivatives are preferred because they are inexpensive and easy to control the reaction.

[0043] These divalent carboxylic acids and trivalent or higher carboxylic acids can be used individually or in combination of two or more.

[0044] Furthermore, amorphous polyesters are preferably capped at the molecular chain ends with a monoalcohol or monocarboxylic acid.

[0045] Furthermore, the molecular chain ends include the ends of branched chains if the amorphous polyester has branched chains. Of the monoalcohols and monocarboxylic acids, linear alkyl monoalcohols and linear alkyl monocarboxylic acids are more preferred from the viewpoint of charge build-up in high humidity environments.

[0046] Examples of linear alkyl monocarboxylic acids include the following:

[0047] Palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), nonadesylic acid, arachidic acid (eicosanoic acid), henicosyl acid, behenic acid (docosanoic acid), tricosanoic acid, and tetracosanoic acid.

[0048] Examples of linear alkyl monoalcohols include the following:

[0049] Palmityl alcohol (hexadecanol), heptadecanol, stearyl alcohol (octadecanol), nonadecanol, arachidyl alcohol (icosanol), heneicosanol, behenyl alcohol, lignoceryl alcohol, tricosanol, and tetracosanol.

[0050] The number-average molecular weight of amorphous polyester is preferably between 2,000 and 10,000 from the viewpoint of controlling the acid value. The number-average molecular weight of amorphous polyester can be controlled by the reaction time, reaction temperature, amount of catalyst, and degree of reduced pressure in the polyester manufacturing method described later.

[0051] Amorphous polyesters can be produced according to conventional polyester synthesis methods.

[0052] For example, the above carboxylic acid component and alcohol component are subjected to an esterification or transesterification reaction. Subsequently, a condensation polymerization reaction is carried out under reduced pressure or by introducing nitrogen gas according to a conventional method to obtain the desired polyester.

[0053] However, when a linear alkyl monocarboxylic acid or alkyl monoalcohol is present simultaneously during the reaction between the carboxylic acid component and the alcohol component, the linear alkyl compound forms the molecular chain end. Therefore, it can act like an end cap, potentially causing the molecular chain to become extremely short. For this reason, it is preferable to add the linear alkyl compound to the reaction system in the later stages of the reaction.

[0054] Esterification or transesterification reactions can be carried out using conventional esterification or transesterification catalysts such as sulfuric acid, titanium butoxide, dibutyltin oxide, tin 2-ethylhexanoate, manganese acetate, or magnesium acetate, as needed. Furthermore, condensation polymerization reactions can be carried out using conventional polymerization catalysts, such as known catalysts like titanium butoxide, dibutyltin oxide, tin 2-ethylhexanoate, tin acetate, zinc acetate, tin disulfide, antimony trioxide, or germanium dioxide. The polymerization temperature and catalyst amount are not particularly limited and can be determined as appropriate.

[0055] <Crystalline polyester> The toner of this disclosure preferably contains a crystalline polyester. When a crystalline polyester is included, the barium titanate and the crystalline polyester exchange charge, causing moderate charge leakage, which allows the amount of charge to be maintained at an appropriate level in a low-humidity environment.

[0056] The components used in the synthesis of crystalline polyesters include polyhydric alcohols (dihydric or trihydric or higher alcohols), polyhydric carboxylic acids (dihydric or trihydric or higher carboxylic acids), their acid anhydrides, or their lower alkyl esters. The main chain of the crystalline polyester is preferably a condensed polymer of an aliphatic dicarboxylic acid and an aliphatic diol.

[0057] Examples of polyhydric alcohols used in the synthesis of crystalline polyesters include the following. While the polyhydric alcohol is not particularly limited, it is preferably a linear (more preferably straight-chain) aliphatic diol, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,4-butadiene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, nonamethylene glycol, decamethylene glycol, and neopentyl glycol. Among these, linear aliphatic and α,ω-diols such as ethylene glycol, diethylene glycol, 1,4-butanediol, and 1,6-hexanediol are particularly preferred examples.

[0058] Other polyhydric alcohols besides those listed above can also be used. Examples of dihydric alcohols include aromatic alcohols such as polyoxyethylene-modified bisphenol A and polyoxypropylene-modified bisphenol A; and 1,4-cyclohexanedimethanol. Examples of trihydric or higher polyhydric alcohols include aromatic alcohols such as 1,3,5-trihydroxymethylbenzene; and aliphatic alcohols such as pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, and trimethylolpropane.

[0059] The following polycarboxylic acids can be used as polycarboxylic acids in crystalline polyesters. The polycarboxylic acid is not particularly limited, but it is preferably a linear (more preferably linear) aliphatic dicarboxylic acid. Specific examples include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, superiric acid, glutaconic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, and itaconic acid, and also includes hydrolyzed acid anhydrides or lower alkyl esters of these acids.

[0060] Other polycarboxylic acids besides those listed above can also be used. Among the other polycarboxylic acids, divalent carboxylic acids include aromatic carboxylic acids such as isophthalic acid and terephthalic acid; aliphatic carboxylic acids such as n-dodecylsuccinic acid and n-dodecenylsuccinic acid; and alicyclic carboxylic acids such as cyclohexanedicarboxylic acid. These also include their acid anhydrides or lower alkyl esters.

[0061] Furthermore, among other carboxylic acid monomers, polycarboxylic acids with a valency of 3 or higher include aromatic carboxylic acids such as 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalentricarboxylic acid, 1,2,4-naphthalentricarboxylic acid, and pyromellitic acid, as well as aliphatic carboxylic acids such as 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, and 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane. These also include derivatives such as acid anhydrides or lower alkyl esters.

[0062] Furthermore, it is more preferable, from the viewpoint of controlling electrostatic adhesion in low-humidity environments, for the crystalline polyester to contain modified crystalline polyester whose ends are modified with aliphatic monoalcohols or aliphatic monocarboxylic acids. The interaction between the ends of the crystalline polyester and the fatty acids of barium titanate facilitates charge exchange between barium titanate and the crystalline polyester, and moderate charge leakage occurs, allowing the amount of charge to be maintained at an appropriate level in low-humidity environments.

[0063] The molecular chain ends include the ends of branched chains if the amorphous polyester has branched chains. Of the monoalcohols and monocarboxylic acids, linear alkyl monoalcohols and linear alkyl monocarboxylic acids are more preferred from the viewpoint of charge build-up in high humidity environments.

[0064] Examples of linear alkyl monocarboxylic acids include the following:

[0065] Palmitic acid (hexadecanoic acid), margaric acid (heptadecanoic acid), stearic acid (octadecanoic acid), nonadesylic acid, arachidic acid (eicosanoic acid), henicosyl acid, behenic acid (docosanoic acid), tricosanoic acid, and tetracosanoic acid.

[0066] Examples of linear alkyl monoalcohols include the following:

[0067] Palmityl alcohol (hexadecanol), heptadecanol, stearyl alcohol (octadecanol), nonadecanol, arachidyl alcohol (icosanol), heneicosanol, behenyl alcohol, lignoceryl alcohol, tricosanol, and tetracosanol.

[0068] The number-average molecular weight of the crystalline polyester is preferably between 2,000 and 10,000. The number-average molecular weight of the crystalline polyester can be controlled by the reaction time, reaction temperature, amount of catalyst, and degree of reduced pressure in the polyester manufacturing method described later.

[0069] Crystalline polyesters can be produced according to conventional polyester synthesis methods. For example, crystalline polyesters can be obtained by esterifying or transesterifying the aforementioned carboxylic acid monomer and alcohol monomer, followed by a polycondensation reaction under reduced pressure or by introducing nitrogen gas, according to conventional methods. Subsequently, the desired crystalline polyester can be obtained by adding the above-mentioned aliphatic compound and carrying out an esterification reaction.

[0070] The above esterification or transesterification reactions can be carried out using conventional esterification or transesterification catalysts such as sulfuric acid, titanium butoxide, dibutyltin oxide, manganese acetate, or magnesium acetate, as needed.

[0071] Furthermore, the above polycondensation reaction can be carried out using conventional polymerization catalysts, such as known catalysts like titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, and germanium dioxide. The polymerization temperature and catalyst amount are not particularly limited and can be determined as appropriate.

[0072] In esterification, transesterification, or polycondensation reactions, methods such as charging all monomers at once to increase the strength of the resulting crystalline polyester, or first reacting divalent monomers and then adding trivalent or higher monomers to reduce the amount of low molecular weight components, may be used.

[0073] In the synthesis of crystalline polyesters, including modified crystalline polyesters, it is preferable to condense at least one selected from the group consisting of aliphatic monocarboxylic acids and aliphatic monoalcohols (preferably the aliphatic monocarboxylic acid), as well as aliphatic diols and aliphatic dicarboxylic acids. The proportion of aliphatic diols is preferably 30 mol% to 50 mol%, more preferably 35 mol% to 45 mol%, and the proportion of aliphatic dicarboxylic acids is preferably 5 mol% to 45 mol%, more preferably 10 mol% to 35 mol%. Furthermore, the proportion of at least one selected from the group consisting of aliphatic monocarboxylic acids and aliphatic monoalcohols (preferably the aliphatic monocarboxylic acid) is preferably 15 mol% to 60 mol%, more preferably 20 mol% to 30 mol%.

[0074] In crystalline polyester, the total content of monomer units consisting of aliphatic monocarboxylic acids and aliphatic monoalcohols in the terminally modified structure is preferably 1.0% by mass or more and 30.0% by mass or less, and more preferably 2.0% by mass or more and 25.0% by mass or less.

[0075] The crystalline polyester content in the toner particles is preferably 1.0 part by mass or more and 15.0 parts by mass or less per 100 parts by mass of binder resin, and more preferably 3.0 parts by mass or more and 15.0 parts by mass or less from the viewpoint of suppressing electrostatic adhesion in low humidity environments.

[0076] <Coloring agent> Colorants may be used in the toner particles as needed. Examples of colorants include the following:

[0077] Examples of black colorants include carbon black and black colorants prepared by mixing yellow, magenta, and cyan colorants. While pigments may be used alone as colorants, using dyes and pigments in combination is preferable from the standpoint of full-color image quality to improve clarity.

[0078] The following are examples of pigments used for magenta toner: CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48:2, 48:3, 48:4, 49, 50, 51, 52, 53, 54, 55, 57:1, 58, 60, 63, 64, 68, 81:1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 146, 147, 150, 163, 184, 202, 206, 207, 209, 238, 269, 282; CI Pigment Violet 19; CI Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

[0079] Examples of dyes for magenta toner include: oil-soluble dyes such as CI Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121; CI Disperse Red 9; CI Solvent Violet 8, 13, 14, 21, 27; CI Disperse Violet 1; and basic dyes such as CI Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40; and CI Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, 28.

[0080] Examples of pigments for cyan toner include: CI Pigment Blue 2, 3, 15:2, 15:3, 15:4, 16, 17; CI Bat Blue 6; CI Acid Blue 45; and copper phthalocyanine pigments in which phthalimidomethyl groups are substituted onto the phthalocyanine skeleton.

[0081] CI Solvent Blue 70 is a dye used for cyan toner.

[0082] The following pigments are used for yellow toner: CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 62, 65, 73, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185; CI Bat Yellow 1, 3, 20.

[0083] CI Solvent Yellow 162 is a dye used for yellow toner.

[0084] The coloring agent content is preferably 0.1 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of the binder resin.

[0085] <wax> Wax may be used in the toner particles as needed. Examples of waxes include the following:

[0086] Hydrocarbon waxes such as microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; oxides of hydrocarbon waxes such as oxidized polyethylene wax or block copolymers thereof; waxes mainly composed of fatty acid esters such as carnauba wax; and deoxidized fatty acid esters such as deoxidized carnauba wax, which have been partially or completely deoxidized.

[0087] Furthermore, the following can be listed: saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; saturated alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; polyhydric alcohols such as sorbitol; esters of fatty acids such as palmitic acid, stearic acid, behenic acid, and montanic acid with alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylenebisstearate amide, ethylenebiscaprate amide, ethylenebislaurate amide, and hexamethylene Saturated fatty acid bisamides such as bis-stearamide; unsaturated fatty acid amides such as ethylenebisoleamide, hexamethylenebisoleamide, N,N'dioleyladipamide, and N,N'dioleylsebacamide; aromatic bisamides such as m-xylenebis-stearamide and N,N'distearylisophthalamide; aliphatic metal salts (commonly known as metal soaps) such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; waxes grafted onto aliphatic hydrocarbon waxes with vinyl monomers such as styrene or acrylic acid; partially esterified fatty acids and polyhydric alcohols such as behenic acid monoglyceride; and methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils.

[0088] The wax content is preferably 2.0 parts by mass or more and 30.0 parts by mass or less per 100 parts by mass of the binder resin.

[0089] <Charge control agent> Toner particles may contain charge control agents as needed. While known charge control agents can be used in toner, aromatic carboxylic acid metal compounds that are colorless, have a fast charging speed for the toner, and can stably maintain a constant charge are particularly preferred.

[0090] Examples of negative charge control agents include salicylate metal compounds, naphthoate metal compounds, dicarboxylic acid metal compounds, polymer compounds having sulfonic acid or carboxylic acid as a side chain, polymer compounds having sulfonate or sulfonic acid ester as a side chain, polymer compounds having carboxylate salt or carboxylic acid ester as a side chain, boron compounds, urea compounds, silicon compounds, and calixarenes. The charge control agent may be added internally or externally to the toner particles.

[0091] The amount of charge control agent added is preferably 0.2 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of binder resin.

[0092] [Inorganic microparticles (other external additives)] The toner of this disclosure has the aforementioned barium titanate attached to the surface of the toner particles, and other inorganic fine particles may be used in combination as needed. The other inorganic fine particles may be internally added to the toner particles or mixed with the toner mother particles as an external additive. As an external additive, inorganic fine particles such as silica are preferred. The inorganic fine particles are preferably hydrophobized with a hydrophobic agent such as a silane compound, silicone oil, or a mixture thereof.

[0093] It is preferable that the inorganic fine particles have a number-average particle size smaller than that of the barium titanate particles. If the number-average particle size is larger than that of the barium titanate particles, it becomes difficult for the barium titanate particles and carriers to come into contact, making it difficult to obtain the effects of this disclosure.

[0094] Inorganic fine particles are preferably used in amounts of 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of toner particles. Meeting this range makes it easier to obtain the effect of electrostatic stability.

[0095] As inorganic fine particles, strontium titanate particles or calcium titanate particles with a number-average particle size of 0.02 μm or more and 0.12 μm or less are preferred. High temperature and low humidity environments tend to increase the amount of charge and thus the electrostatic adhesion force, but by having strontium titanate particles or calcium titanate particles on the surface of the toner particles, the accumulation of charge can be suppressed. As a result, the effect of suppressing electrostatic adhesion force can be obtained even in high temperature and low humidity environments.

[0096] When the number-average particle size of strontium titanate particles or calcium titanate particles is within the above range, the strontium titanate particles or calcium titanate particles and barium titanate come into contact more easily, allowing for easier charge flow, thus effectively suppressing electrostatic adhesion. When the number-average particle size of barium titanate is S (μm) and the number-average particle size of strontium titanate particles or calcium titanate particles is M (μm), a ratio S / M of 0.5 to 4.0 is preferable from the viewpoint of suppressing electrostatic adhesion because it facilitates contact and charge flow more easily.

[0097] It is preferable to use strontium titanate particles or calcium titanate particles in an amount of 0.1 parts by mass or more and 10.0 parts by mass or less per 100 parts by mass of toner particles. Meeting this range makes it easier to obtain the effect of electrostatic stability.

[0098] [Developer] The toner of this disclosure can be used as a one-component developer, but it is preferable to mix it with a magnetic carrier and use it as a two-component developer in order to further improve dot reproduction and to supply stable images over a long period of time.

[0099] As magnetic carriers, generally known materials can be used, such as iron powder with an oxidized surface, or iron powder without oxidation, or magnetic materials such as metal particles like iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, chromium, and rare earth elements, or their alloy particles, oxide particles, or ferrite, or magnetic material dispersion resin carriers (so-called resin carriers) containing a magnetic material and a binder resin that holds the magnetic material in a dispersed state.

[0100] When toner is mixed with a magnetic carrier and used as a two-component developer, the mixing ratio is preferably 2% by mass or more and 15% by mass or less, and more preferably 4% by mass or more and 13% by mass or less, as the toner concentration in the two-component developer.

[0101] [Method for manufacturing toner particles and method for manufacturing toner] There are no particular limitations on the method for producing toner particles, and conventionally known production methods such as suspension polymerization, emulsification and agglomeration, melt kneading, and dissolution and suspension can be employed.

[0102] The resulting toner particles are mixed with barium titanate particles and, if necessary, other external additives. Mixing of the toner particles, barium titanate particles, and other external additives can be done using mixing equipment such as a double-con mixer, V-type mixer, drum-type mixer, super mixer, Henschel mixer, Nauta mixer, Mechanohybrid (manufactured by Nippon Coke Industries Co., Ltd.), or Novilta (manufactured by Hosokawa Micron Corporation).

[0103] [Methods for measuring various physical properties] The following describes methods for measuring various physical properties.

[0104] <Separation of external additives and toner particles> The external additive containing barium titanate particles can also be separated and measured from the toner using the following method.

[0105] Add 200g of sucrose (manufactured by Kishida Chemical Co., Ltd.) to 100mL of deionized water and dissolve it over a water bath to prepare a concentrated sucrose solution. Place 31g of this concentrated sucrose solution and 6mL of Contaminon N (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) into a centrifuge tube to prepare a dispersion. Add 1g of toner to this dispersion and break up any clumps of toner with a spatula or similar tool.

[0106] The centrifugation tube is shaken in the shaker described above at a rate of 350 strokes per minute for 20 minutes. After shaking, the solution is transferred to a 50 mL glass tube for a swing rotor and centrifuged in a centrifuge at 3500 rpm for 30 minutes. After centrifugation, toner is present in the uppermost layer of the glass tube, and inorganic fine particles are present in the lower aqueous solution layer. The lower aqueous solution is collected and centrifuged to separate the sucrose from the inorganic fine particles, and the inorganic fine particles are collected. If necessary, centrifugation is repeated to ensure sufficient separation, then the dispersion is dried and the inorganic fine particles are collected.

[0107] When multiple inorganic microparticles are added, barium titanate particles can be separated using methods such as centrifugation.

[0108] <Method for measuring the number-average particle size of primary barium titanate particles, strontium titanate particles, and calcium titanate particles> The number-average particle size of barium titanate particles, strontium titanate particles, and calcium titanate particles is measured using a scanning electron microscope "Ultra Plus" (product name; manufactured by Zeiss). Identification of hydrophobic treated alumina fine particles is performed by the above-mentioned SEM-EDS analysis.

[0109] The toner was observed under the following conditions, and the longest diameter of the primary particles was measured for 100 particles of each type. The average of the obtained longest diameters was defined as the number-average particle size. The observation magnification was adjusted as appropriate depending on the size of the barium titanate particles, strontium titanate particles, and calcium titanate particles.

[0110] (SEM observation conditions) Sample pretreatment; toner fixed with carbon tape and Pt coating. SEM acceleration voltage: 2.0kV WD; 2.8mm Detector; SE2 resolution: 1024 x 768 pixels Observation magnification: 5,000 to 50,000 times

[0111] <Method for measuring the amount of hydroxyl groups A in barium titanate particles> The amount of hydroxyl groups A (μmol / g) in barium titanate particles can be determined by titration. Specifically, a 4% by mass solution was prepared by dispersing dried barium titanate particles in ethanol. Next, the tip of the probe of an ultrasonic disperser was immersed in the above solution, and dispersion 1 was obtained by ultrasonic dispersion at an output of 20W for 15 minutes. To this dispersion, three times the volume of ethanol, a 20% sodium chloride aqueous solution was added, and the tip of the probe of the ultrasonic disperser was immersed in the above solution, and dispersion 2 was obtained by ultrasonic dispersion at an output of 20W for 15 minutes. Hydrogen chloride solution was added to dispersion 2 until the pH was 5.0, and the titration volume (mol) at the inflection point of the titration curve was divided by the mass of the barium titanate particles used to obtain the amount of hydroxyl groups A (μmol / g).

[0112] <Method for identifying surface treatment agents for barium titanate particles> The surface treatment agent for barium titanate is analyzed by pyrolysis GC-MS (gas chromatography-mass spectrometry).

[0113] The measurement conditions are as follows: Equipment: GC6890A (Agilent), pyrolysis unit (Nippon Analytical Engineering Co., Ltd.) Column: HP-5ms 30m Thermal decomposition temperature: 590℃ By identifying the position of each peak in the profile obtained through measurement using a standard sample, the surface treatment agent of the external additive is identified.

[0114] <Amount of surface treatment material for barium titanate particles> Barium titanate particles were measured using a thermogravimetric / differential thermal analyzer (Rigaku Corporation, differential thermal balance TG-DTA, ThermoPlusTG8120). The temperature was increased from 25°C to 400°C at a rate of 10°C / min, and the amount of surface treatment agent was determined from the change in mass.

[0115] <Method for measuring the acid value of polyester> Acid value is the amount of potassium hydroxide (in mg) required to neutralize the acidic components, such as free fatty acids and resin acids, contained in 1 g of sample. Acid value is measured according to JIS-K0070-1992 as follows.

[0116] (1) Reagents Dissolve 1.0 g of phenolphthalein in 90 mL of ethyl alcohol (95% by volume), add deionized water to make a total volume of 100 mL, and obtain a phenolphthalein solution.

[0117] Dissolve 7 g of special grade potassium hydroxide in 5 mL of water and add ethyl alcohol (95 vol%) to make 1 L. Place the solution in an alkali-resistant container, taking care not to allow it to come into contact with carbon dioxide, etc., and leave it for 3 days. After filtration, obtain the potassium hydroxide solution. Store the obtained potassium hydroxide solution in an alkali-resistant container. The factor of the potassium hydroxide solution is determined by taking 25 mL of 0.1 mol / L hydrochloric acid into an Erlenmeyer flask, adding a few drops of the phenolphthalein solution, titrating with the potassium hydroxide solution, and determining the amount of potassium hydroxide solution required for neutralization. The 0.1 mol / L hydrochloric acid used should be prepared in accordance with JIS K 8001-1998.

[0118] (2) Operation (A) Main examination 2.0 g of the pulverized sample is accurately weighed into a 200 mL Erlenmeyer flask, and 100 mL of a toluene / ethanol (2:1) mixture is added. The sample is dissolved over 5 hours. Then, a few drops of the phenolphthalein solution are added as an indicator, and the sample is titrated with the potassium hydroxide solution. The titration endpoint is reached when the indicator turns a pale pink color for approximately 30 seconds. (B) Blank test The titration procedure is the same as described above, except that no sample is used (i.e., only a mixed solution of toluene / ethanol (2:1) is used).

[0119] (3) Substitute the obtained results into the following formula to calculate the acid value. A = [(CB) × f × 5.61] / S Here, A: acid value (mgKOH / g), B: volume of potassium hydroxide solution added in the blank test (mL), C: volume of potassium hydroxide solution added in the main test (mL), f: factor of the potassium hydroxide solution, and S: mass of the sample (g).

[0120] <Method for measuring the amount of carboxyl groups B in fatty acids on the surface of barium titanate particles> The amount of carboxyl groups B (μmol / g) of fatty acids on the surface of barium titanate particles was measured in the same manner as the method for measuring the acid value of polyester described above. The unit of the acid value finally calculated (mgKOH / g) was converted to (μmol / g) to obtain the amount of carboxyl groups B (μmol / g) of fatty acids on the surface of barium titanate particles.

[0121] <Measurement of the acid value of polyester from toner> The following method can be used to measure the acid value of polyester from toner. Separate the polyester from the toner using the following method, and then measure the acid value.

[0122] The toner is dissolved in tetrahydrofuran (THF), and the solvent is removed from the resulting soluble matter under reduced pressure to obtain the tetrahydrofuran (THF) soluble component of the toner.

[0123] The tetrahydrofuran (THF)-soluble component of the obtained toner is dissolved in chloroform to prepare a sample solution with a concentration of 25 mg / ml.

[0124] The obtained sample solution (3.5 ml) is poured into the apparatus described below, and under the conditions described below, components with a molecular weight of 2000 or more are separated as resin components. Preparative GPC device: Preparative HPLC LC-980 model manufactured by Japan Analytical Industry Co., Ltd. Preparative column: JAIGEL 3H, JAIGEL 5H (manufactured by Japan Analytical Industry Co., Ltd.) Eluent: Chloroform Flow rate: 3.5ml / min After separating the high molecular weight components derived from the resin, the solvent is removed by distillation under reduced pressure, and the mixture is then dried under reduced pressure in a 90°C atmosphere for 24 hours. The above procedure is repeated until approximately 2.0 g of the resin component is obtained. The acid value of the obtained sample is measured according to the procedure described above.

[0125] <Measurement of number-average molecular weight of amorphous and crystalline polyesters> The number-average molecular weight of the resin is measured by gel permeation chromatography (GPC) as follows.

[0126] (Amorphous polyester) First, the sample (resin) is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. Then, the resulting solution is filtered through a solvent-resistant membrane filter, "Maeshori Disc" (manufactured by Tosoh Corporation), with a pore diameter of 0.2 μm, to obtain the sample solution. The sample solution is adjusted so that the concentration of solvent-soluble components is approximately 0.8% by mass. This sample solution is then used for measurement under the following conditions. Equipment: HLC8120GPC (Detector: RI) (Manufactured by Tosoh Corporation) Columns: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko) Eluent: Tetrahydrofuran (THF) Flow rate: 1.0ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml To calculate the molecular weight of the sample, a molecular weight calibration curve prepared using standard polystyrene is used.

[0127] (Crystalline polyester) First, the sample (resin) is dissolved in hexafluoroisopropanol (HFIP) at room temperature for 24 hours. Then, the resulting solution is filtered through a solvent-resistant membrane filter, "Maeshori Disc" (manufactured by Tosoh Corporation), with a pore diameter of 0.2 μm, to obtain the sample solution. The sample solution is adjusted so that the concentration of solvent-soluble components is approximately 0.8% by mass. This sample solution is then used for measurement under the following conditions. Equipment: HLC8120GPC (Detector: RI) (Manufactured by Tosoh Corporation) Columns: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko) Eluent: Hexaflooroisopropanol (HFIP) Flow rate: 1.0mL / min Oven temperature: 40.0℃ Sample injection volume: 0.10 mL To calculate the molecular weight of the sample, a molecular weight calibration curve prepared using standard polymethyl methacrylate resin is used.

[0128] <Method for measuring the weight-average particle size (D4) of toner particles> The weight-average particle size (D4) of toner particles is measured using the "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter), a precision particle size distribution analyzer using the pore electrical resistance method with a 100 μm aperture tube, and the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting measurement conditions and analyzing measurement data, with an effective measurement channel count of 25,000. The measurement data is then analyzed and calculated.

[0129] The electrolytic aqueous solution used for measurement is prepared by dissolving special grade sodium chloride in deionized water to a concentration of approximately 1% by mass; for example, "ISOTON II" (manufactured by Beckman Coulter) can be used.

[0130] Before performing measurements and analysis, configure the dedicated software as follows.

[0131] In the "Change Standard Measurement Method (SOM)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "standard particle 10.0 μm" (manufactured by Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the box for flushing the aperture tube after measurement.

[0132] In the dedicated software's "Pulse to Particle Size Conversion Settings Screen," set the bin spacing to logarithmic particle size, the particle size bins to 256 particle size bins, and the particle size range to 2 μm or more and 60 μm or less.

[0133] The specific measurement method is as follows: (1) Pour approximately 200 ml of the electrolytic solution into a 250 ml round-bottom glass beaker specifically designed for the Multisizer 3, set it on the sample stand, and stir the mixture with the stirrer rod at 24 revolutions per second in a counterclockwise direction. Then, use the "Aperture Tube Flash" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) Place approximately 30 ml of the electrolytic aqueous solution into a 100 ml flat-bottomed glass beaker, and add approximately 0.3 ml of a diluted solution of "Contaminon N" (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted three times by mass with deionized water as a dispersant. (3) Two oscillators with an oscillation frequency of 50 kHz are built in with their phases shifted by 180 degrees, and a predetermined amount of deionized water is placed in the water tank of an ultrasonic dispersion device called "Ultrasonic Dispersion System Tetora150" (manufactured by Nikko Bios Co., Ltd.) with an electrical output of 120 W. Approximately 2 ml of the aforementioned Contaminon N is added to this water tank. (4) Place the beaker from (2) into the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic aqueous solution inside the beaker is maximized. (5) While irradiating the electrolytic aqueous solution in the beaker described in (4) with ultrasound, add approximately 10 mg of toner to the electrolytic aqueous solution in small amounts and disperse it. Continue the ultrasonic dispersion treatment for another 60 seconds. During ultrasonic dispersion, adjust the water temperature in the tank to be between 10°C and 40°C as appropriate. (6) Using a pipette, the electrolytic aqueous solution (5) containing the dispersed toner is dropped into the round-bottom beaker (1) placed in the sample stand, and the concentration is adjusted to approximately 5%. The measurement is then continued until the number of particles measured reaches 50,000. (7) The measurement data is analyzed using the dedicated software attached to the device, and the weight-average particle size (D4) is calculated. Note that the "Average Diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen when the dedicated software is set to Graph / Volume % is the weight-average particle size (D4).

[0134] [Configuration included in the embodiment of the invention] This embodiment includes the following configuration. (Configuration 1) A toner comprising toner particles containing amorphous polyester and barium titanate particles present on the surface of the toner particles, The amorphous polyester has a carboxyl group, The barium titanate particles are (i) comprising a barium titanate core and a fatty acid having 6 or more carbon atoms fixed to the surface of the barium titanate core, (ii) The amount of hydroxyl groups measured by titration is between 15 μmol / g and 1300 μmol / g. A toner characterized by the following features. (Configuration 2) The toner according to Configuration 1, wherein the number-average particle size of the barium titanate particles is 0.02 μm or more and 0.12 μm or less. (Configuration 3) The toner according to Configuration 1 or 2, wherein the barium titanate particles have a hydroxyl group content measured by titration of 120 μmol / g or more and 450 μmol / g or less. (Configuration 4) The toner according to any one of Configurations 1 to 3, wherein the content of barium titanate particles per 100 parts by mass of toner particles is 0.10 parts by mass or more and 5.00 parts by mass or less. (Configuration 5) The toner according to any one of Configurations 1 to 4, wherein the number of carbon atoms in the fatty acid is 12 or more and 24 or less. (Composition 6) The toner according to any one of Compositions 1 to 5, wherein the fatty acid is stearic acid. (Configuration 7) The toner particles are the toner according to any one of Configurations 1 to 6, which includes a crystalline polyester. (Configuration 8) The toner according to Configuration 7, wherein the crystalline polyester comprises a modified crystalline polyester whose terminals are modified with an aliphatic monoalcohol or an aliphatic monocarboxylic acid. (Configuration 9) The toner according to any one of Configurations 1 to 8, wherein the barium titanate particles contain 0.50% by mass or more and 5.00% by mass or less of the fatty acid. (Configuration 10) The toner according to any one of Configurations 1 to 9, comprising, as an external additive, strontium titanate particles with a number average particle size of 0.02 μm or more and 0.12 μm or less, or calcium titanate particles with a number average particle size of 0.02 μm or more and 0.12 μm or less. (Configuration 11) A toner according to any one of Configurations 1 to 10, wherein the ratio A / B of the amount of hydroxyl groups A (μmol / g) of the barium titanate particles to the amount of carboxyl groups B (μmol / g) of the fatty acid is 0.7 or more and 30.0 or less. [Examples]

[0135] This disclosure will be specifically illustrated by the following examples. However, these examples are not intended to limit this disclosure in any way. Unless otherwise specified, all "parts" in the following formulations refer to mass.

[0136] <Example of production of barium titanate particles 1> (1) Preparation steps for the reaction A sodium hydroxide aqueous solution was added to a metatitanic acid dispersion to adjust the pH to 9.0. The resulting solution was desulfurized, and then hydrochloric acid was added to adjust the pH to 5.7. Next, the solution adjusted to pH 5.7 was filtered, and the resulting solid was washed with water. Then, deionized water was added to the washed solid to obtain a slurry with a Ti concentration of 2.12 mol / L. Hydrochloric acid was added to the obtained slurry to perform a gelatinization treatment. Next, an aqueous solution of barium chloride, equivalent to 2.1590 mol of Ba, was added to the gelatinized slurry.

[0137] (2) Reaction process The slurry obtained by the above procedure was stirred while the internal temperature of the reaction vessel was raised to 90°C. Then, 550 mL of sodium hydroxide aqueous solution (10 mol / L) was added to the reaction vessel at a constant rate over 2 hours. Next, the internal temperature of the reaction vessel was raised to 90°C and stirred for 2 hours while maintaining the temperature at 90°C. Then, the contents of the vessel were cooled to 50°C, and hydrochloric acid was added until the pH was 5.0. Next, the mixture was stirred for 1 hour while maintaining the temperature at 50°C to obtain a precipitate.

[0138] The obtained precipitate was washed by decantation and filtered. The resulting solid was then dried in air at 90°C for 10 hours to obtain barium titanate core A powder.

[0139] (3) Fatty acid surface treatment process The following materials were placed in a Henschel mixer and stirred at 2000 rpm for 2 minutes. Then, the mixture was stirred at 100 rpm for 10 minutes while the temperature was increased to 90°C to obtain barium titanate particles 1. The physical properties of barium titanate particles 1 are shown in Table 1. • Barium titanate core: 100.00 units Stearic acid (18 carbon atoms): 4.12 parts

[0140] <Example of production of barium titanate particles 2> Barium titanate particles 2 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 1.02 parts.

[0141] <Example of production of barium titanate particles 3> Barium titanate particles 3 were obtained with the physical properties shown in Table 1, using the same method as in the production example of barium titanate particles 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 0.90 parts.

[0142] <Example of manufacturing barium titanate particles 4> Barium titanate particles 4 were obtained with the physical properties shown in Table 1, using the same method as in the production example of barium titanate particles 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 0.50 parts.

[0143] <Example of manufacturing barium titanate particles 5> Barium titanate particles 5 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 5.00 parts, in the same manner as the production example of barium titanate particles 1.

[0144] <Example of manufacturing barium titanate particles 6> Barium titanate particles 6 were obtained with the physical properties shown in Table 1, using the same method as the production example of barium titanate particles 1, except that stearic acid was replaced with lauric acid (12 carbon atoms) in the fatty acid surface treatment process.

[0145] <Example of manufacturing barium titanate particles 7> Barium titanate particles 7 were obtained with the physical properties shown in Table 1, using the same method as in the production example of barium titanate particles 1, except that stearic acid was replaced with lignoceric acid (24 carbon atoms) in the fatty acid surface treatment process.

[0146] <Example of manufacturing barium titanate particles 8> Barium titanate particles 8 were obtained with the same properties as shown in Table 1, except that stearic acid was replaced with capric acid (10 carbon atoms) in the fatty acid surface treatment process.

[0147] <Example of manufacturing barium titanate particles 9> Barium titanate particles 9 were obtained with the physical properties shown in Table 1, using the same method as in the production example of barium titanate particles 1, except that stearic acid was replaced with cerotic acid (26 carbon atoms) in the fatty acid surface treatment process.

[0148] <Example of manufacturing barium titanate particles 10> Barium titanate particles 10 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 4.84 parts.

[0149] <Example of manufacturing barium titanate particles 11> Barium titanate particles 11 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 3.51 parts.

[0150] <Example of manufacturing barium titanate particles 12> Barium titanate particles 12 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 4.92 parts.

[0151] <Example of manufacturing barium titanate particles 13> Barium titanate particles 13 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 3.31 parts.

[0152] <Example of manufacturing barium titanate particles 14> Barium titanate particles 14 were obtained with the same properties as shown in Table 1, except that the time spent adding the sodium hydroxide aqueous solution in the reaction process was changed to 1 hour.

[0153] <Example of manufacturing barium titanate particles 15> Barium titanate particles 15 were obtained with the same properties as shown in Table 1, except that the time spent adding the sodium hydroxide aqueous solution in the reaction process was changed to 2 hours and 30 minutes.

[0154] <Example of manufacturing barium titanate particles 16> Barium titanate particles 16 were obtained with the same properties as shown in Table 1, except that the time spent adding the sodium hydroxide aqueous solution in the reaction process was changed to 30 minutes.

[0155] <Example of manufacturing barium titanate particles 17> Barium titanate particles 17 were obtained with the same properties as shown in Table 1, except that the time spent adding the sodium hydroxide aqueous solution in the reaction process was changed to 3 hours.

[0156] <Example of manufacturing barium titanate particles 18> Barium titanate particles 18 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 5.26 parts.

[0157] <Example of manufacturing barium titanate particles 19> Barium titanate particles 19 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 0.10 parts.

[0158] <Example of manufacturing barium titanate particles 20> Barium titanate particles 20 were obtained with the same properties as shown in Table 1, except that stearic acid was replaced with caproic acid (6 carbon atoms) in the fatty acid surface treatment process.

[0159] <Example of manufacturing barium titanate particles 21> Barium titanate particles 21 were obtained with the physical properties shown in Table 1, using the same method as the production example of barium titanate particles 1, except that the fatty acid surface treatment step was eliminated.

[0160] <Example of manufacturing barium titanate particles 22> Barium titanate particles 22 were obtained with the same properties as shown in Table 1, except that stearic acid was replaced with pentanoic acid (5 carbon atoms) in the fatty acid surface treatment process.

[0161] <Example of manufacturing barium titanate particles 23> Barium titanate particles 23 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 5.30 parts, in the same manner as the production example of barium titanate particles 1.

[0162] <Example of manufacturing barium titanate particles 24> Barium titanate particles 24 were obtained with the same properties as shown in Table 1, except that the amount of stearic acid added in the fatty acid surface treatment process was changed to 0.05 parts, in the same manner as the production example of barium titanate particles 1.

[0163] <Example of manufacturing barium titanate particles 25> To 600 parts of pure water, 285 parts of the reagent barium hydroxide octahydrate were added, and the mixture was heated while stirring to prepare an aqueous solution at 80°C (Solution A).

[0164] In separate reaction vessels, 560 parts of n-butanol and 220 parts of the reagent tetra-n-butoxytitanium were charged, and while stirring, 200 parts of pure water were gradually added to hydrolyze the mixture, preparing a titanium hydroxide slurry at 25°C (Solution B).

[0165] To the aforementioned solution B, solution A was quickly added, and the mixture was heated under reflux at a rate of 30°C per hour to 90°C, and then aged at 90°C for 1 hour.

[0166] After cooling, suction filtration was performed to obtain a cake of precipitated crystals. 300 parts of a 3% aqueous acetic acid solution were added to the separated cake, and the washing and filtration process was repeated twice. The resulting cake was then dried at 105°C for 24 hours to obtain barium titanate precursor powder.

[0167] The barium titanate precursor powder was crushed using a roll mill, and then calcined at 850°C for 4 hours. Aggregated particles were removed using a jet mill and used as a sample.

[0168] Next, a fatty acid surface treatment process similar to that used in the production example of barium titanate particle 1 was performed with 4.10 parts of stearic acid per 100.00 parts of the above sample to obtain barium titanate particles. The obtained material was designated as barium titanate particle 25, and its composition and physical properties are shown in Table 1.

[0169] <Example of manufacturing barium titanate particles 26> In a nitrogen atmosphere, 75 parts of barium isopropoxide and 92 parts of titanium tetraisopropoxide were dissolved in 275 parts of isopropyl alcohol and heated under reflux for 2 hours. Next, while continuing to heat under reflux, 65 parts of distilled water were added dropwise to the solution over 1 hour to hydrolyze the isopropoxide. After cooling to 25°C, water was added to adjust the slurry concentration to 0.5 mol / L in terms of barium titanate. This slurry was heated to boiling point over 1 hour, and then heated under reflux for 3 hours. After cooling to 25°C, decantation was repeated, followed by washing with water, filtration, washing with water, drying at 105°C, and crushing to obtain barium titanate particles. The obtained material was designated as barium titanate particles 26, and its composition and properties are shown in Table 1.

[0170] <Example of manufacturing strontium titanate particles 1> Metatitanic acid produced by the sulfuric acid method was subjected to iron removal and bleaching treatment, then desulfurized by adding a 3 mol / L sodium hydroxide aqueous solution to bring the pH to 9.0, followed by neutralization to pH 5.6 with 5 mol / L hydrochloric acid and rinsing with filtered water. Water was added to the washed cake to form a 1.90 mol / L slurry of TiO2, and then hydrochloric acid was added to bring the pH to 1.4 for disaccharification treatment.

[0171] 1.90 mol of desulfurized and disintegrated metatitanic acid was collected as TiO2 and placed in a 3 L reaction vessel. To the disintegrated metatitanic acid slurry, 2.185 mol of strontium chloride aqueous solution was added to achieve a SrO / TiO2 (mol ratio) of 1.15, and the TiO2 concentration was adjusted to 1.039 mol / L.

[0172] Next, the mixture was heated to 90°C while stirring, then 440 mL of 10 mol / L sodium hydroxide aqueous solution was added over 40 minutes. After that, stirring was continued at 95°C for 45 minutes, and then the mixture was rapidly cooled in ice water to terminate the reaction.

[0173] The reaction slurry was heated to 70°C, 12 mol / L hydrochloric acid was added until the pH reached 5.0, and stirring was continued for 1 hour. The resulting precipitate was then decanted.

[0174] The slurry containing the obtained precipitate was adjusted to 40°C, and hydrochloric acid was added to adjust the pH to 2.5. Then, 4.0% by mass of 3,3,3-trifluoropropyltrimethoxysilane (as surface treatment agent 1) and 4.0% by mass of isobutyltrimethoxysilane (as surface treatment agent 2) were added relative to the solid content, and the mixture was stirred for 10 hours. A 5 mol / L aqueous sodium hydroxide solution was added to adjust the pH to 6.5, and stirring was continued for 1 hour. After filtration and washing, the resulting cake was dried in air at 120°C for 8 hours to obtain strontium titanate particles 1. The number-average particle size of the primary particles of the obtained strontium titanate particles 1 was 40 nm.

[0175] <Example of calcium titanate particle production> Titanium tetraisopropoxide was used as the raw material. Using a chemical pump, small amounts were sent to glass wool in a vaporizer heated to approximately 200°C, with nitrogen gas as the carrier gas, and evaporated. After instantaneous thermal decomposition at approximately 300°C in the reactor, the material was rapidly cooled and the product was collected. This was then calcined at approximately 300°C for about 2 hours, and pulverized in a jet mill to obtain titanium oxide.

[0176] 52 parts titanium dioxide and 48 parts calcium carbonate were dispersed in 100 parts water, thoroughly mixed, and heat-treated at a temperature of approximately 1000°C to obtain calcium titanate particles 1. The number-average particle size of the primary particles of the obtained calcium titanate particles 1 was 40 nm.

[0177] [Table 1]

[0178] <Example of Amorphous Polyester 1 Production> Polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane: 71.3 parts (0.155 mol parts) Terephthalic acid: 24.1 parts (0.145 mol parts) Titanium tetrabutoxide: 0.6 parts The above materials were placed in a 4-liter, four-necked glass flask, and a thermometer, stirring rod, condenser, and nitrogen inlet tube were attached and placed inside a mantle heater. Next, the flask was purged with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was then reacted at 200°C for 2 hours while stirring. After that, 5.8 parts (0.030 mol) of trimellitic anhydride was added, and the mixture was reacted at 180°C for 10 hours to obtain amorphous polyester 1. The number-average molecular weight of amorphous polyester 1 was 6000, and the acid value was 10 mgKOH / g.

[0179] <Example of Amorphous Polyester 2 Production> Polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane: 96.6 parts (0.210 mol parts) Terephthalic acid: 24.1 parts (0.145 mol parts) Titanium tetrabutoxide: 0.6 parts The above materials were placed in a 4-liter, four-necked glass flask, and a thermometer, stirring rod, condenser, and nitrogen inlet tube were attached and placed inside a mantle heater. Next, the flask was purged with nitrogen gas, and the temperature was gradually increased while stirring. The reaction was carried out at 200°C with stirring for 2 hours, and then at 180°C for 10 hours to obtain amorphous polyester 2. The number-average molecular weight of this amorphous polyester 2 was 3000, and the acid value was 5 mgKOH / g.

[0180] <Example of Amorphous Polyester 3 Production> In the example of producing amorphous polyester 1, the reaction was carried out in the same manner except that the amount of polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane added was changed to 76.9 parts, the amount of titanium tetrabutoxide added to 0.5 parts, and the amount of trimellitic anhydride added to 5.3 parts, to obtain amorphous polyester 3. The number-average molecular weight of amorphous polyester 3 was 4500, and the acid value was 30 mgKOH / g.

[0181] <Example of Amorphous Polyester 4 Production> Polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane: 60.0 parts Terephthalic acid: 35.0 parts Titanium tetrabutoxide (esterification catalyst): 0.5 parts The above materials were placed in a 4-liter, four-necked glass flask, and a thermometer, stirring rod, condenser, and nitrogen inlet tube were attached. The flask was then placed inside a mantle heater. Next, the flask was purged with nitrogen gas, and the temperature was gradually increased while stirring. The mixture was then reacted at 200°C for 2 hours while stirring. Furthermore, the pressure in the reaction vessel was reduced to 8.3 kPa and maintained for 1 hour, after which it was cooled to 160°C and returned to atmospheric pressure.

[0182] after that, • Stearic acid: 5.0 parts The reaction was stopped by adding the following: reducing the pressure in the reaction vessel to 8.3 kPa, maintaining the temperature at 200°C for 2 hours, then lowering the temperature to obtain amorphous polyester 4. The number-average molecular weight of this amorphous polyester 4 was 3100, and the acid value was 10 mg KOH / g.

[0183] <Example of Amorphous Polyester 5 Production> In the example of producing amorphous polyester 1, the amount of polyoxypropylene (2,2)-2,2-bis(4-hydroxyphenyl)propane added was changed to 96.6 parts, the amount of terephthalic acid added to 18.0 parts, and the amount of trimellitic anhydride added to 6.0 parts. The reaction was carried out in the same manner except that titanium tetrabutoxide was not used, and amorphous polyester 5 without carboxyl groups was obtained. The number average molecular weight of this amorphous polyester 5 was 6200, and the acid value was 0 mgKOH / g.

[0184] <Example of Styrene Acrylic Resin 1 Production> 850 parts of xylene were placed in a 2-liter four-necked glass flask equipped with a thermometer, stainless steel stirring rod, a fall-flow condenser, and a nitrogen inlet tube. After purging with nitrogen, the flask was heated to 150°C.

[0185] • Styrene: 800 copies n-butyl acrylate: 1000 copies • Monobutyl acrylate: 50 units • Dicumyl peroxide: 80 units Subsequently, the mixture of the above materials was added dropwise from a dropping funnel over a period of 4 hours, and the mixture was reacted at 150°C for 4 hours. After that, the temperature was raised to 200°C, and xylene was removed by distillation under reduced pressure to obtain styrene-acrylic resin 1. The acid value of this styrene-acrylic resin 1 was 0 mgKOH / g.

[0186] <Example of manufacturing crystalline polyester 1> • Ethylene glycol: 22.0 parts Dodecanediol: 68.0 parts Behenic acid: 10.0 parts • Tin 2-ethylhexanoate: 0.5 parts The above materials were weighed into a reaction vessel equipped with a condenser, stirrer, nitrogen inlet tube, and thermocouple. After replacing the inside of the flask with nitrogen gas, the temperature was gradually increased while stirring, and the reaction was carried out for 3 hours at a temperature of 140°C while stirring.

[0187] Subsequently, the pressure in the reaction vessel was reduced to 8.3 kPa, and the reaction was carried out for 4 hours while maintaining the temperature at 200°C to obtain crystalline polyester 1. The physical properties are shown in Table 2.

[0188] <Examples of manufacturing crystalline polyester 2-8> Crystalline polyesters 2 to 8 were obtained by carrying out the reaction in the same manner as in the example of producing crystalline polyester 1, except that the monomer used was changed as shown in Table 2. The physical properties of the obtained crystalline polyesters 2 to 8 are shown in Table 2.

[0189] [Table 2]

[0190] <Example of toner particle 1 manufacturing> Amorphous polyester 1 100.0 parts Crystalline polyester 1 6.0 parts • Fischer-Tropsch wax (peak temperature of maximum endothermic peak: 78°C) 5.0 parts CI Pigment Blue 15:3 5.0 parts The raw materials shown in the above formula were mixed using a Henschel mixer (FM-75 model, manufactured by Nippon Coke Industries Co., Ltd.) at a rotation speed of 20 seconds. -1 After mixing for 5 minutes, the mixture was kneaded in a twin-shaft kneader (PCM-30 model, manufactured by Ikegai Co., Ltd.) set to a temperature of 125°C and a rotation speed of 300 rpm. The resulting mixture was cooled and coarsely ground to a diameter of 1 mm or less using a hammer mill to obtain coarse material. The obtained coarse material was finely ground using a mechanical pulverizer (T-250, manufactured by Freund Turbo Co., Ltd.). Further classification was performed using a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) to obtain toner particles 1. The operating conditions for the rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) were a classification rotor rotation speed of 50.0 s. -1Classification was performed. The resulting toner particles 1 had a weight-average particle size (D4) of 5.9 μm.

[0191] <Manufacturing example of toner particles 2-9> In the example of manufacturing toner particle 1, toner particles 2 to 9 were obtained in the same manner, except that the type of crystalline polyester was changed as shown in Table 3.

[0192] <Example of toner particle manufacturing (10-13 particles)> In the example of manufacturing toner particle 1, toner particles 10 to 13 were obtained in the same manner, except that the type of amorphous polyester was changed as shown in Table 3.

[0193] <Example of toner particle 14 manufacturing> In the example of manufacturing toner particles 1, toner particles 14 were obtained in the same manner except that 100 parts of styrene acrylic resin 1 were used instead of amorphous polyester.

[0194] [Table 3] *Toner particles 14 use styrene-acrylic resin instead of amorphous polyester.

[0195] <Example of Toner 1 manufacturing> • Toner particles 1 100.00 parts Barium titanate particles 1 1.50 parts • Strontium titanate particles 1 0.40 parts The above ingredients were mixed in a Henschel FM-10C mixer (manufactured by Mitsui Miike Chemical Machinery) at a rotation speed of 30 seconds. -1 The mixture was then mixed for a rotation time of 10 minutes to obtain toner 1.

[0196] <Examples of Toner 2-3 manufacturing> Toner 2 and 3 were obtained by manufacturing in the same manner as in the example of Toner 1, except that the type of barium titanate particles was changed as shown in Table 4.

[0197] <Example of Toner 4 manufacturing> Toner 4 was obtained by manufacturing in the same manner as in the example of toner 1, except that strontium titanate particles 1 were replaced with calcium titanate particles 1.

[0198] <Example of Toner 5 production> Toner 5 was obtained by manufacturing in the same manner as in the example of toner 1, except that strontium titanate was not added.

[0199] <Manufacturing examples for toners 6-48> In the manufacturing example of toner 1, the toner was manufactured in the same manner as shown in Table 4, except that the type of toner particles, the type and amount of barium titanate particles were changed. Toners 6 to 48 were obtained.

[0200] [Table 4]

[0201] <Example of manufacturing for Carrier 1> • Number-average particle size 0.30 μm, magnetization strength 65 Am under a magnetic field of (1000 / 4π (kA / m)) 2 100 parts of magnetite (1 / kg) were mixed with 4.0 parts of a silane compound (3-(2-aminoethylaminopropyl)trimethoxysilane), and the mixture was rapidly mixed and stirred in a container at over 100°C to perform surface treatment. The resulting particles were designated as magnetite A. • Number-average particle size 0.50 μm, magnetization strength 65 Am under a magnetic field of (1000 / 4π (kA / m)) 2 100 parts of magnetite (1 / kg) were mixed with 4.0 parts of a silane compound (3-(2-aminoethylaminopropyl)trimethoxysilane), and the mixture was rapidly mixed and stirred in a container at over 100°C to perform surface treatment. The resulting particles were designated as magnetite B.

[0202] • Phenolic: 10% by mass Formaldehyde solution: 6% by mass (40% formaldehyde by mass, 10% methanol by mass, 50% water by mass) • Magnetite A: 58% by mass • Magnetite B: 26% by mass The above materials, along with 5 parts of a 28% by mass aqueous ammonia solution and 20 parts of water, were placed in a flask. The mixture was stirred and heated to 85°C for 30 minutes, and maintained therefor. Polymerization was carried out for 3 hours to cure the resulting phenolic resin. The cured phenolic resin was then cooled to 30°C, water was added, the supernatant was removed, the precipitate was washed with water, and the mixture was air-dried. This was then dried under reduced pressure (5 mmHg or less) at a temperature of 60°C to obtain spherical carrier 1 with magnetic dispersion. The volume-based 50% particle size (D50) was 34.2 μm.

[0203] <Example of manufacturing a two-component developer 1> 92.0 parts of carrier 1 and 8.0 parts of toner 1 were added and mixed using a V-type mixer (V-20, manufactured by Seishin Corporation) to obtain a two-component developer 1.

[0204] <Manufacturing examples of two-component developers 2-48> In the example of manufacturing two-component developer 1, the manufacturing process was carried out in the same manner except that toners 2 to 48 were used, thereby obtaining two-component developers 2 to 48.

[0205] [Example 1] <Toner Evaluation Method> The following evaluations were performed using a two-component developer 1.

[0206] A Canon imagePress C800 full-color copier was used as the image forming apparatus. Two-component developer 1 was placed in the cyan developer of the image forming apparatus, and the above toner was placed in the cyan toner container, and the evaluation described below was performed. The modification was the removal of the mechanism that discharges excess magnetic carriers from inside the developer. The evaluation paper was plain paper GF-C081 (A4, basis weight 81.4 g / m²). 2 (Sold by Canon Marketing Japan Inc.)

[0207] (1) Evaluation of charge rise time - 1: Time constant In an imagePress C800, with toner supply cut off, the developer containing a two-component developer 1 was rotated at 500 rpm for 2 hours without printing any images. During this time, the developer was sampled at 20, 50, 90, 180, 300, 600, 1200, 2400, 5400, and 7200 seconds, and the amount of charge was measured.

[0208] The amount of charge (mC / kg) is measured as follows. In the triboelectric charge measuring device shown in Figure 1, 0.15 g of the mixture is placed in a metal measuring container 2A with a 635 mesh screen 3A at the bottom, and a metal lid 4A is placed on top. The mass of the entire measuring container 2A at this time is weighed and recorded as W1 (g). Next, using the suction device 1A (at least the part in contact with the measuring container 2A is an insulator), suction is made from the suction port 7A, and the airflow control valve 6A is adjusted to set the pressure of the vacuum gauge 5A to 1.5 kPa. Suction is performed in this state for 2 minutes to remove the developer by suction. The potential of the potentiometer 9A at this time is recorded as V (volts). Here, 8A is a capacitor with capacitance C (μF). The mass of the entire measuring device after suction is weighed and recorded as W2 (g). The amount of triboelectric charge q (mC / kg) of the sample is calculated as shown in the following formula. q = CV / (W1 - W2)

[0209] The above test was conducted in a high-humidity environment (temperature 30°C / humidity 80%RH). The time constant τ(s) was determined by fitting the results to the following model equation for charge amount q with respect to time t(s). Hereinafter, Q is the saturation charge amount (mC / kg) and q0 is the initial charge amount (mC / kg). Qq = (Q - q0) (1 - exp(t / τ))

[0210] The calculated time constants τ were ranked according to the following criteria. A smaller time constant τ indicates a shorter time to reach saturation charging, and a smaller time constant τ is preferable. The evaluation results are shown in Table 5. (Evaluation Criteria) AA:τ is less than 30(s) A: τ is 30 or more and less than 100(s) B: τ is 100 or more and less than 200(s) C:τ is between 200 and 500(s) D:τ is 500 or more

[0211] (2) Evaluation method for charge rise time - 2: Image output test The charge rise time was evaluated by measuring the change in density when outputting images with different image print ratios. After outputting an image with a low image ratio to saturate the charge of the toner in the developing machine, an image with a high image ratio was output. This resulted in a change in density due to the difference in charge between the saturated toner in the developing machine and the newly supplied toner. Toner with a fast charge rise time saturates immediately after being supplied to the developing machine, resulting in less change in density. On the other hand, toner with a slow charge rise time takes longer to saturate after being supplied to the developing machine, causing the overall charge of the toner to decrease and resulting in a change in density.

[0212] An image output test was conducted with 1000 images at an image ratio of 1%. During the continuous feeding of 1000 images, the same development and transfer conditions (no calibration) as the first image were used. Subsequently, an image output test was conducted with 1000 images at an image ratio of 80%. During the continuous feeding of 1000 images, the same development and transfer conditions (no calibration) as the first image were used. The image density of the 1000th image printed at an image ratio of 1% was used as the initial density, and the density of the 1000th image printed at an image ratio of 80% was measured and evaluated according to the following evaluation criteria. The above tests were conducted in a high-humidity environment (temperature 30°C / humidity 80%RH). (Measurement of image density change) An X-Rite color reflectance densitometer (500 series: manufactured by X-Rite) was used to measure the density of the initial density and the 1000th image printed at an image ratio of 80%, and the difference in image density was ranked according to the following criteria. The evaluation results are shown in Table 5. (Evaluation criterion: concentration difference Δ) AA: Less than 0.02 A: 0.02 or higher, less than 0.05 B: 0.05 or higher, less than 0.10 C: 0.10 or higher, less than 0.15 D: 0.15 or more

[0213] (3) Evaluation of electrostatic adhesive force The electrostatic adhesive force of toner was evaluated by measuring flight property (%). The measurement was performed using an electric field separation type charge quantity measuring apparatus (manufactured by Etwas Higashiosaka Research Institute Co., Ltd.). Although the above apparatus is a charge quantity measuring apparatus, the flight property of the toner was evaluated by causing the toner in the two-component developer coated on an inner sleeve to fly to an outer sleeve using an electric field during the measurement process, and calculating the proportion of the flying toner.

[0214] The flight property is measured by the following method. Using two-component developer 1, an image output test of 1000 sheets was performed at an image ratio of 1%. During continuous paper feeding of 1000 sheets, paper feeding was performed under the same development conditions and transfer conditions as the first sheet (without calibration). Thereafter, an image output test of 1000 sheets was performed at an image ratio of 80%. During continuous paper feeding of 1000 sheets, paper feeding was performed under the same development conditions and transfer conditions as the first sheet (without calibration). Thereafter, the developing device was taken out, the two-component developer was sampled from the developing sleeve, and 1 g of the sampled developer was separated into toner and magnetic carrier using the electric field separation type charge quantity measuring apparatus under the conditions of an applied voltage of 3 kV, a time of 60 sec, a rotation speed of 50 rpm, and a gap of 3 mm between the inner sleeve and the outer sleeve. When t (g) represents the mass of the toner adhering to the outer sleeve, and d (g) represents the mass of the toner contained in the sampled two-component developer (= mass of the two-component developer × toner proportion (mass%)), the toner flight property E can be calculated by the following formula. Flight property E (%) = t / d × 100

[0215] The toner flight property E was used as an index of electrostatic adhesive force, and ranked according to the following criteria. The above evaluation was performed in a low-temperature low-humidity environment (temperature 15°C / humidity 5%RH) and a high-temperature low-humidity environment (temperature 32.5°C / humidity 5%RH), respectively. The evaluation results are shown in Table 5. (Evaluation Criteria) A: Flight property E is 85% or more B: Flight property E is 75% or more and less than 85% C: Flight property E is 65% or more and less than 75% D: Flight property E is less than 65%

[0216] (4) Evaluation of charge amount in low-humidity environment The toner deposition amount on paper was adjusted to 0.35 mg / cm 2 . The toner deposition amount on paper was adjusted by the DC voltage VDC of the developer carrier, the charging voltage VD of the electrostatic latent image carrier, and the laser power. A 2 cm × 5 cm image arranged at the center of the A4 sheet was used as the evaluation image, and the process speed was set to 377 mm / sec.

[0217] The triboelectric charge amount of the toner was calculated by suction-collecting the toner on the electrostatic latent image carrier using a metal cylindrical tube and a cylindrical filter. Specifically, the triboelectric charge amount of the toner on the electrostatic latent image carrier was measured with a Faraday-Cage.

[0218] A Faraday cage is a coaxial double cylinder, and the inner cylinder and the outer cylinder are insulated from each other. Assuming a charged body with a charge amount Q is placed in the inner cylinder, electrostatic induction causes a state equivalent to the presence of a metal cylinder having a charge amount Q. The induced charge amount was measured with an electrometer (Keithley 6517A, manufactured by Keithley Instruments), and [Q / M] (mC / kg), which is obtained by dividing the charge amount Q (mC) by the toner mass M (kg) in the inner cylinder, was defined as the triboelectric charge amount of the toner. Triboelectric charge amount of toner (mC / kg) = Q / M

[0219] The above test was performed in a normal temperature and low humidity environment (temperature 23°C / humidity 5%RH).

[0220] First, the evaluation image was formed on the electrostatic latent image carrier. Before transfer to the intermediate transfer member, rotation of the electrostatic latent image carrier was stopped, the toner on the electrostatic latent image carrier was suction-collected by a metal cylindrical tube and a cylindrical filter, [Q / M] (mC / kg) was measured, and judgment was made according to the following criteria. The evaluation results are shown in Table 6. (Evaluation Criteria) A: [Q / M] is less than 55 mC / kg B: [Q / M] is 55 mC / kg or more and less than 60 mC / kg C: [Q / M] is 60 mC / kg or more and less than 65 mC / kg D: [Q / M] is 65 mC / kg or more

[0221] [Examples 2-39] The evaluation was carried out in the same manner as in Example 1, except that two-component developers 2 to 39 were used. The evaluation results for Examples 2 to 39 are shown in Table 5.

[0222] [Comparative Examples 1-9] The evaluation was carried out in the same manner as in Example 1, except that two-component developers 40-48 were used. The evaluation results for Comparative Examples 1-9 are shown in Table 5.

[0223] [Table 5]

Claims

1. A toner comprising toner particles containing amorphous polyester and barium titanate particles present on the surface of the toner particles, The amorphous polyester has a carboxyl group, The barium titanate particles are (i) comprising a barium titanate core and a fatty acid having 6 or more carbon atoms fixed to the surface of the barium titanate core, (ii) The amount of hydroxyl groups measured by titration is 15 μmol / g or more and 1300 μmol / g or less. A toner characterized by the following features.

2. The toner according to claim 1, wherein the number-average particle size of the barium titanate particles is 0.02 μm or more and 0.12 μm or less.

3. The toner according to claim 1, wherein the barium titanate particles have a hydroxyl group content measured by titration of 120 μmol / g or more and 450 μmol / g or less.

4. The toner according to claim 1, wherein the content of barium titanate particles per 100 parts by mass of toner particles is 0.10 parts by mass or more and 5.00 parts by mass or less.

5. The toner according to claim 1, wherein the number of carbon atoms in the fatty acid is 12 or more and 24 or less.

6. The toner according to claim 1, wherein the fatty acid is stearic acid.

7. The toner according to claim 1, wherein the toner particles include crystalline polyester.

8. The toner according to claim 7, wherein the crystalline polyester comprises a modified crystalline polyester whose terminals are modified with an aliphatic monoalcohol or an aliphatic monocarboxylic acid.

9. The toner according to claim 1, wherein the barium titanate particles contain 0.50% by mass or more and 5.00% by mass or less of the fatty acid.

10. The toner according to claim 1, wherein the toner comprises, as an external additive, strontium titanate particles having a number average particle size of 0.02 μm or more and 0.12 μm or less, or calcium titanate particles having a number average particle size of 0.02 μm or more and 0.12 μm or less.

11. The toner according to claim 1, wherein the ratio A / B of the amount of hydroxyl groups A (μmol / g) of the barium titanate particles to the amount of carboxyl groups B (μmol / g) of the fatty acid is 0.7 or more and 30.0 or less.

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