Toner and method for manufacturing toner

Abstract

To provide a toner can resolve trade-off between prevention of image stripes and prevention of black dots even after endurance use by an image forming apparatus with an extended life.SOLUTION: A toner contains a toner particle containing a binder resin and an external additive on the surface of the toner particle. The binder resin contains resin having an ester linkage. In the ATR method, in ATR-IR analysis on the toner particle using germanium as an ATR crystal, a peak corresponding to boric acid is detected. Desorption processing A is performed of shaking a fluid dispersion obtained by dispersing the toner in an aqueous solution containing surfactant in a shaker for 300 seconds, and when the external additive desorbed from the toner through the desorption processing A is defined as an external additive A, the amount of electrification using a standard carrier (F81) of the external additive A is -0.5 μC / g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This disclosure relates to toner (hereinafter sometimes simply referred to as "toner") used in electrophotography, electrostatic recording, and toner jet recording methods, and to a method for manufacturing the toner. [Background technology]

[0002] In recent years, there has been a widespread demand for even faster process speeds and longer lifespans in electrophotographic image forming equipment. In this context, we recognize the need for technological development to stabilize the toner's charging performance through extended use, in order to maintain the quality of electrophotographic images.

[0003] To increase the speed of printers, it is necessary to quickly charge the toner, and one method for doing so is to fix a negative external additive. For example, Patent Document 1 discloses treating an external additive using a fluorine-containing silane coupling agent and a hydrophobic treatment agent other than a fluorine-containing silane coupling agent in combination. Patent Document 2 also discloses titania surface-treated with a hydrophobic agent and a fluorine-based silane coupling agent as an external additive.

[0004] However, in printers with longer lifespans, the external additives can become embedded during prolonged use, potentially leading to localized charge buildup in the embedded areas after extended use. Additionally, the migration of the external additives during prolonged use can cause the toner's charge to become more widespread. In other words, as printer process speeds become faster and lifespans increase, the stress on the toner increases, but it is necessary to stabilize the state of the external additives on the surface of the toner particles. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2008-158176 [Patent Document 2] Japanese Patent Application Publication No. 08-248670 [Patent Document 3] Japanese Patent Publication No. 2020-106816 [Overview of the project] [Problems that the invention aims to solve]

[0006] Our research has shown that using an external additive for strong negative processing, as described in Patent Documents 1 and 2, can produce toner with excellent charge build-up. However, we recognize that there is still room for improvement in terms of further increasing process speed and extending lifespan. Specifically, we found that as the strong negative external additive wears off in the latter half of durable use, the toner's charge becomes broad, resulting in image streaks.

[0007] To suppress the detachment of external additives during the latter half of durable use, there is a method, as described in Patent Document 3, to embed the external additives into the toner particles by applying strong force. However, it has been found that the embedded parts locally charge up after durable use, and the charged-up toner is printed on the white areas of the image, resulting in black spots. This disclosure provides a toner that can eliminate the trade-off between suppressing image streaks and suppressing black spots, even after extended use in image forming apparatuses with longer lifespans. [Means for solving the problem]

[0008] This disclosure relates to a toner containing a binder resin in toner particles and an external additive on the surface of the toner particles, The binder resin contains a resin having ester bonds, In the ATR method, in ATR-IR analysis of toner particles using germanium as the ATR crystal, a peak corresponding to boric acid was detected. Desorption treatment A is performed by dispersing the toner in an aqueous solution containing a surfactant and shaking the dispersion for 300 seconds using a shaker, and the external additive detached from the toner by desorption treatment A is referred to as external additive A. 、 The toner is dispersed in an aqueous solution containing a surfactant, and the dispersion is subjected to desorption treatment B by shaking it in a shaker for 30 seconds. The external additive desorbed from the toner by desorption treatment B is designated as external additive B.When said external additive A no Ki has a charge amount measured using a carrier (F81) of -30.0μC / g or more -5.0 μC / g or less the law of nature, The content of the external additive A is 0.20 parts by mass or more and 10.00 parts by mass or less per 100 parts by mass of the toner particles. The amount of external additive B relative to external additive A is 80% by mass or less. In the X-ray fluorescence measurement of the toner particles, the intensity of boron derived from the boric acid is 0.10 kcps or more and 0.60 kcps or less. relates to a toner.

[0009] Further, the present disclosure relates to a method for producing the toner described above, wherein the method comprises: (1) a dispersion step of preparing a dispersion of binder resin fine particles containing the binder resin; (2) an aggregation step of aggregating the binder resin fine particles contained in the dispersion of binder resin fine particles to form an aggregate; and (3) a fusing step of heating and fusing the aggregate the method comprises a boric acid source is added to the dispersion in at least any one of the steps (2) and (3).

Effects of the Invention

[0010] According to the present disclosure, there can be provided a toner that can resolve the trade-off between suppression of image streaks and suppression of black spots even after durable use of an image forming apparatus having a longer service life.

Brief Description of Drawings

[0011] [Figure 1] Schematic diagram of a charge amount measuring apparatus

Mode for Carrying Out the Invention

[0012] In the present disclosure, unless otherwise specified, the descriptions "from XX to YY" and "XX~YY" representing numerical ranges mean a numerical range including the lower limit and the upper limit, which are the endpoints. When numerical ranges are described stepwise, the upper limit and lower limit of each numerical range can be combined arbitrarily.

[0013] This disclosure relates to a toner containing a binder resin in toner particles and an external additive on the surface of the toner particles, The binder resin contains a resin having ester bonds, In the ATR method, in ATR-IR analysis of toner particles using germanium as the ATR crystal, a peak corresponding to boric acid was detected. When the dispersion, in which the toner is dispersed in an aqueous solution containing a surfactant, is subjected to a desorption treatment A by shaking it in a shaker for 300 seconds, and the external additive desorbed from the toner by desorption treatment A is referred to as external additive A, External additive A no Ki This relates to toner with a charge amount of -0.5 μC / g or less using a carrier (F81).

[0014] The inventors have discovered that by incorporating boric acid into toner particles and using the above-mentioned specific external additive, the trade-off between suppressing image streaks and black spots can be eliminated even after prolonged use. The inventors believe this is because the hardness near the surface of the toner particles suppresses the embedding of the negatively treated external additive, while the electron imbalance in the BO bond of boric acid causes the negatively treated external additive to remain fixed by electrical action.

[0015] The toners described in Patent Documents 1 and 2 are intended to further increase process speed and extend lifespan. In contrast, the inventors speculate that the reason why image streaks after durable use cannot be sufficiently suppressed is as follows: These toners, by having a negative external additive, have been found to improve the initial charge rise, resulting in a good starting speed and initial density for the main unit. However, in main units that are even faster and have a longer lifespan, when the negative external additive migrates, delamination charging occurs with the toner, and the toner's charge broadens after durable use. Therefore, the coating state of the electrostatic latent image carrier by the toner becomes uneven, and the parts where the toner does not completely fly off as an image become streaks.

[0016] On the other hand, the inventors speculate that the toner described in Patent Document 3 cannot sufficiently suppress black spots after durable use when the process speed is further increased or the lifespan is extended, as follows: It has been found that this toner suppresses image streaks by strongly fixing a negative external additive to the toner, thereby suppressing the migration of the external additive after durable use. However, in a printer with even higher speed and a longer lifespan, the embedding of the negative external additive into the toner is accelerated after durable use, causing toner charge-up. As a result, it is believed that several toner particles that have been charged up are scattered together in the white areas, causing black spots.

[0017] Therefore, in printers with even faster process speeds and longer lifespans, it has been difficult to achieve both rapid charging using negative external additives and suppression of image streaks and black spots after durability.

[0018] Here, we investigated a method for maintaining a fixed state even when external additives are not embedded in the toner particle surface. Generally, electrostatic adhesion is the force that causes external additives to adhere to the toner particle surface. In order to fix negative external additives without embedding them, we considered it important to focus on the electrostatic adhesion force acting between the toner particle surface and the external additive and to keep it within an appropriate range. Based on the above considerations, after further investigation, we found that the toner disclosed herein can well meet the above requirements.

[0019] The toner of this disclosure contains toner particles containing a binder resin and an external additive. The dispersion, in which the toner is dispersed in an aqueous solution containing a surfactant, is subjected to a desorption treatment A by shaking the dispersion in a shaker for 300 seconds, and the external additive desorbed from the toner by desorption treatment A is referred to as external additive A. no Ki The charge amount using Carrier (F81) is characterized by being -0.5 μC / g or less. External additive A no Ki The charge amount using Carrier (F81) is preferably -30.0 μC / g or more and -1.0 μC / g or less, and more preferably -25.0 μC / g or more and -5.0 μC / g or less. External additive A no KiBy keeping the charge amount using the carrier (F81) within the above range, the toner's charge rise time can be accelerated, resulting in a good initial density.

[0020] Furthermore, in the toner containing the above-mentioned external additive A, a resin having ester bonds is included as a binder resin, and the detection of boric acid is controlled in IR analysis (crystal: Ge) of toner particles by the ATR method. It was found that this achieves both suppression of image streaks and black spots after extended use. The reason why the detection of boric acid enables both suppression of image streaks and black spots after extended use is hypothesized as follows.

[0021] In the ATR method, germanium (Ge) is used as the ATR crystal, and the incident angle is 45° under conditions of 4000 cm². -1 From 650cm -1 When measuring the absorption spectrum in the range of 1380 cm⁻¹, -1 An absorption peak indicates that boric acid is present at a depth of approximately 0.3 μm. In other words, the detection of a peak corresponding to boric acid in toner particles using germanium-based ATR-IR analysis means that boric acid is present near the surface of the toner particles.

[0022] By placing boric acid near the surface of the toner particles, the electron imbalance caused by the BO bond of boric acid and the electrostatic adhesion force generated by the negative properties of external additive A are thought to create an appropriate adhesion state. As a result, even when the process speed is further increased and the lifespan is extended, it is possible to suppress both image streaks and black spots after durable use, and to stably form high-quality electrophotographic images.

[0023] The binder resin contains a resin that includes ester bonds. Due to the interaction with boric acid caused by the ester-bonded resin, the area near the surface of the toner particles has appropriate hardness, thereby suppressing the embedding of external additives. There are no particular restrictions on the binder resin containing ester bonds, but it is preferable to select from the group consisting of styrene-acrylic resin, polyester resin, and mixed resins and composite resins thereof, in order to ensure appropriate hardness near the surface. Examples of composite resins include hybrid resins having a styrene-acrylic resin portion and a polyester resin portion. Polyester resin is more preferable for controlling the adhesion rate of external additives.

[0024] It is preferable that the external additive A in the toner is surface-treated with a fluorine-containing silane coupling agent. no Ki The amount of charge using the carrier (F81) can be easily adjusted to an appropriate range. Furthermore, the amount of charge of external additive A can also be controlled using modified silicone oil, etc.

[0025] The amount of external additive A in the toner is preferably 0.10 parts by mass or more, more preferably 0.20 parts by mass or more, and even more preferably 0.50 parts by mass or more, per 100 parts by mass of toner particles. By including external additive A within the above range, the charging rise of the toner can be accelerated and the initial density can be improved. While there is no particular upper limit, the content of external additive A is preferably 10.00 parts by mass or less, more preferably 5.00 parts by mass or less, and even more preferably 2.50 parts by mass or less, per 100 parts by mass of toner particles. By keeping the upper limit within the above range, contamination of key parts within the cartridge can be suppressed. Preferably, the content of external additive A is 0.10 parts by mass or more and 10.00 parts by mass or less, per 100 parts by mass of toner particles.

[0026] The external additive can satisfy the above charge amount when it desorbs to become external additive A, but it is preferably inorganic fine particles of about 10 nm to 300 nm. The number-average particle size of the external additive or external additive A is more preferably 20 nm to 100 nm, and even more preferably 30 nm to 50 nm. Examples include silica fine particles, alumina fine particles, titanium oxide fine particles, and strontium titanate fine particles. Among these, it is preferable that the external additive contains strontium titanate fine particles. By including strontium titanate fine particles, the electrostatic adhesion to the toner is increased, so material contamination can be further suppressed.

[0027] Desorption treatment B is performed by shaking a dispersion of toner in an aqueous solution containing a surfactant for 30 seconds using a shaker, and the external additive detached from the toner by desorption treatment B is referred to as external additive B. At this time, the amount of external additive B relative to external additive A is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. By being within the above range, the amount of external additive that is easily embedded can be reduced, and thus black spots after durability can be further suppressed.

[0028] Furthermore, the amount of external additive B relative to external additive A is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less. By being within the above range, the amount of easily transferable external additives can be reduced, thereby further suppressing image streaks after durable use. The amount of external additive B relative to external additive A is preferably 20% by mass or more and 80% by mass or less. The amount of external additive B relative to external additive A can be controlled by the particle size, hardness, quantity, or application time and intensity of the external additives.

[0029] The content of external additive B in the toner is preferably 0.05 parts by mass or more, more preferably 0.10 parts by mass or more, and even more preferably 0.40 parts by mass or more, per 100 parts by mass of toner particles. Within this range, image streaks after extended use can be further suppressed. Furthermore, the content of external additive B in the toner is preferably 5.00 parts by mass or less, more preferably 2.00 parts by mass or less, and even more preferably 1.50 parts by mass or less, per 100 parts by mass of toner particles. Within this range, contamination of components within the cartridge can be improved, and fogging can be further suppressed through extended use.

[0030] Furthermore, the amount of external additives in the toner is preferably 0.10 parts by mass or more and 10.00 parts by mass or less per 100 parts by mass of toner particles, more preferably 0.20 parts by mass or more and 5.00 parts by mass or less, and even more preferably 0.50 parts by mass or more and 2.50 parts by mass or less.

[0031] Of the external additives in the toner, the content of external additive A that is detached from the toner by detachment treatment A is preferably 50% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less.

[0032] The means by which boric acid is incorporated into toner particles are not particularly limited. For example, boric acid can be incorporated into toner particles by internally adding it to the toner particles or by using it as a flocculant in a flocculation method. Adding boric acid as a flocculant makes it easier to introduce boric acid near the surface of the toner particles. When used as a raw material, it may be used in the form of organic boric acid, borate, borate ester, etc. When toner particles are manufactured in an aqueous medium, it is preferable to add it as a borate from the viewpoint of reactivity and manufacturing stability. Specifically, examples include sodium tetraborate and ammonium borate, and borax is particularly preferred.

[0033] Borax is represented as sodium tetraborate (Na2B4O7) decahydrate and changes to boric acid in acidic aqueous solutions. Therefore, borax is preferred when used in an acidic environment within an aqueous medium.

[0034] Furthermore, in the X-ray fluorescence measurement of toner particles, the intensity of boron derived from boric acid is preferably between 0.10 kcps and 0.60 kcps, and more preferably between 0.10 kcps and 0.30 kcps. By controlling it within this range, it is easier to achieve both improved toner chargeability and prevention of peeling charge during the removal of external additives.

[0035] Means for controlling the boron strength within the above range include, for example, adjusting the amount of boric acid source added during toner particle manufacturing, and it is preferable to control the boric acid content in the toner particles to between 0.1% by mass and 10.0% by mass. More preferably, the boric acid content in the toner particles is between 0.4% by mass and 5.0% by mass, and even more preferably between 0.8% by mass and 2.0% by mass.

[0036] This section will provide a more detailed explanation of each component that makes up the toner and the toner manufacturing method. <Binding resin> The toner particles contain a binder resin. Preferably, the binder resin content is 50% by mass or more of the total amount of resin components in the toner particles. The binder resin is not particularly limited and can contain any resin having an ester bond. Known resins can be used. Styrene-acrylic resins and polyester resins are preferred. Polyester resins are more preferred. Polyester resins are obtained by selecting and combining suitable polycarboxylic acids, polyols, hydroxycarboxylic acids, etc., and synthesizing them using known methods such as transesterification or polycondensation. Preferably, the polyester resin contains a condensation polymer of dicarboxylic acids and diols.

[0037] Polycarboxylic acids are compounds that contain two or more carboxyl groups in one molecule. Among these, dicarboxylic acids are compounds that contain two carboxyl groups in one molecule and are preferably used.

[0038] For example, oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid, malonic acid, pimelic acid, superiric acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediacetic acid, o-phenylenediacetic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, cyclohexanedicarboxylic acid, and the like can be listed.

[0039] Other polycarboxylic acids besides the dicarboxylic acids mentioned above include, for example, trimellitic acid, trimesic acid, pyromellitic acid, naphthalentricarboxylic acid, naphthalenetetracarboxylic acid, pyrentricarboxylic acid, pyrenetetracarboxylic acid, itaconic acid, glutaconic acid, n-dodecylsuccinic acid, n-dodecenylsuccinic acid, isododecylsuccinic acid, isododecenylsuccinic acid, n-octylsuccinic acid, and n-octenylsuccinic acid. These may be used individually or in combination of two or more.

[0040] Polyols are compounds that contain two or more hydroxyl groups in one molecule. Among these, diols are compounds that contain two hydroxyl groups in one molecule and are preferably used.

[0041] Specifically, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,14-eicosandec Examples include bisphenol diol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-butenediol, neopentyl glycol, polytetramethylene glycol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and alkylene oxide adducts (ethylene oxide, propylene oxide, butylene oxide, etc.) of the above bisphenols.

[0042] Of these, preferred are alkylene glycols having 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, with particular preference being alkylene oxide adducts of bisphenols and combinations thereof with alkylene glycols having 2 to 12 carbon atoms. It is used. Examples of alkylene oxide adducts of bisphenol A include the compound shown in the following formula (A). [ka]

[0043] (In formula (A), R is independently either an ethylene group or a propylene group, x and y are integers greater than or equal to 0, and the average value of x + y is between 0 and 10.) The alkylene oxide adduct of bisphenol A is preferably a propylene oxide adduct and / or an ethylene oxide adduct of bisphenol A. More preferably, it is a propylene oxide adduct. Furthermore, the average value of x+y is preferably between 1 and 5.

[0044] Examples of trivalent or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, trisphenol PA, phenol novolac, cresol novolac, and alkylene oxide adducts of the above trivalent or higher polyphenols. These may be used individually or in combination of two or more.

[0045] Examples of styrene-acrylic resins include homopolymers composed of the following polymerizable monomers, copolymers obtained by combining two or more of these monomers, and mixtures thereof.

[0046] Styrene monomers such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, and p-phenylstyrene;

[0047] Methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethyl phosphate ethyl (meth)acrylate, diethyl phosphate ethyl (meth)acrylate, dibutyl phosphate ethyl (meth)acrylate, and 2-benzoyloxyethyl (meth)acrylate, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, maleic acid, and other (meth)acrylic monomers;

[0048] Vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone, and vinyl isopropenyl ketone; Polyolefins such as ethylene, propylene, and butadiene.

[0049] Styrene acrylic resin can use polyfunctional polymerizable monomers as needed. Examples of polyfunctional polymerizable monomers include diethylene glycol di(meth)acrylic. Examples include triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-(meth)acryloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

[0050] Furthermore, known chain transfer agents and polymerization inhibitors can be added to control the degree of polymerization. Examples of polymerization initiators for obtaining styrene-acrylic resin include organic peroxide-based initiators and azo-based polymerization initiators. Examples of organic peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1,1-bis(t-butylperoxy)cyclododecane, t-butylperoxymaleic acid, bis(t-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl peroxycarbonate, cumenehydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butyl-peroxypivalate.

[0051] Examples of azo polymerization initiators include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonnitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile and azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0052] Furthermore, a redox initiator, which combines an oxidizing substance and a reducing substance, can also be used as a polymerization initiator. Examples of oxidizing substances include hydrogen peroxide, inorganic peroxides such as persulfates (sodium, potassium, and ammonium salts), and oxidizing metal salts of tetravalent cerium salts. Examples of reducing substances include reducing metal salts (divalent iron salts, monovalent copper salts, and trivalent chromium salts), ammonia, lower amines (amines with approximately 1 to 6 carbon atoms, such as methylamine and ethylamine), amino compounds such as hydroxylamine, reducing sulfur compounds such as sodium thiosulfate, sodium hydrosulfite, sodium bisulfite, sodium sulfite, and sodium formaldehyde sulfoxylate, lower alcohols (with 1 to 6 carbon atoms), ascorbic acid or its salts, and lower aldehydes (with 1 to 6 carbon atoms).

[0053] Polymerization initiators are selected based on their 10-hour half-life temperature and are used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but generally, 0.5 to 20 parts by mass are added per 100.0 parts by mass of polymerizable monomer.

[0054] <Release agent> A known wax can be used as a release agent for the toner. Specifically, these include paraffin wax, microcrystalline wax, petroleum-based waxes such as petrolatum and their derivatives, montan wax and its derivatives, hydrocarbon waxes and their derivatives produced by the Fischer-Tropsch process, polyolefin waxes such as polyethylene and their derivatives, carnauba wax, and candelilla wax. Examples include natural waxes and their derivatives, the derivatives of which include oxides, block copolymers with vinyl monomers, and graft-modified products. Other examples include alcohols such as higher aliphatic alcohols; fatty acids such as stearic acid and palmitic acid, or their acid amides, esters, and ketones; hydrogenated castor oil and its derivatives; plant waxes; and animal waxes. These can be used alone or in combination.

[0055] Among these, polyolefins, hydrocarbon waxes produced by the Fischer-Tropsch process, or petroleum-based waxes tend to improve developability and transferability, making them preferable. These waxes may also contain antioxidants to the extent that they do not affect the toner's effectiveness. Furthermore, from the viewpoint of phase separation properties with respect to the binder resin or crystallization temperature, higher fatty acid esters such as behenyl behenate and dibehenyl sebacate are suitable examples.

[0056] Furthermore, the release agent content is preferably 1.0 part by mass or more and 30.0 parts by mass or less per 100.0 parts by mass of the binder resin. The melting point of the release agent is preferably 30°C to 120°C, and more preferably 60°C to 100°C. By using a release agent exhibiting the above thermal properties, the release effect is efficiently achieved, and a wider fixing area is secured.

[0057] <Plasticizer> Toner particles may contain crystalline plasticizers to improve sharp meltability. The plasticizer is not particularly limited, and known plasticizers used in toners, such as those listed below, can be used.

[0058] Specifically, esters of monohydric alcohols and aliphatic carboxylic acids, such as behenyl behenate, stearyl stearate, and palmityl palmitate; esters of dihydric alcohols and aliphatic carboxylic acids, such as ethylene glycol distearate, dibehenyl sebacate, and hexanediol dibehenate; esters of trihydric alcohols and aliphatic carboxylic acids, such as glycerol tribehenate; and pentaerythritol tetras Esters of tetrahydric alcohols and aliphatic carboxylic acids, such as theate and pentaerythritol tetrapalmitate, or esters of tetrahydric carboxylic acids and aliphatic alcohols; esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of hexahydric carboxylic acids and aliphatic alcohols; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerin behenate, or esters of polyhydric carboxylic acids and aliphatic alcohols; natural ester waxes, such as carnauba wax and rice wax. These can be used alone or in combination.

[0059] <Coloring agent> Toner particles may contain a colorant. Known pigments and dyes can be used as the colorant. Pigments are preferred as the colorant due to their excellent weather resistance. Examples of cyanide-based colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, the following are listed: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0060] Examples of magenta-based colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolon compounds, thioindigo compounds, and perylene compounds. Specifically, the following are listed: CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254, and CI Pigment Violet 19.

[0061] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specifically, the following are listed: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, and 194.

[0062] Examples of black colorants include those formulated to produce black using the above-mentioned yellow, magenta, and cyan colorants, as well as carbon black. These colorants can be used individually, in mixtures, or in solid solution form. Preferably, the colorant is used in an amount of 1.0 part by mass to 20.0 parts by mass per 100.0 parts by mass of the binder resin.

[0063] <Charge control agents and charge control resins> Toner particles may contain a charge control agent or a charge control resin. Known charge control agents can be used, and those with a fast triboelectric charging speed and the ability to stably maintain a constant triboelectric charge are particularly preferred. Furthermore, when toner particles are manufactured by suspension polymerization, charge control agents with low polymerization inhibitory properties and substantially no solubilizers in aqueous media are particularly preferred.

[0064] Examples of materials that control the toner's charge characteristics include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid compounds, metal-containing naphthoic acid compounds, boron compounds, quaternary ammonium salts, calixarenes, and charge-controlling resins.

[0065] Examples of charge-controlled resins include polymers or copolymers having sulfonic acid groups, sulfonic acid bases, or sulfonic acid ester groups. Among polymers having sulfonic acid groups, sulfonic acid bases, or sulfonic acid ester groups, polymers containing 2% by mass or more of a sulfonic acid group-containing acrylamide monomer or a sulfonic acid group-containing methacrylamide monomer in copolymerization ratio are particularly preferred, and more preferably polymers containing 5% by mass or more.

[0066] Preferably, the charge-controlled resin has a glass transition temperature (Tg) of 35°C to 90°C, a peak molecular weight (Mp) of 10,000 to 30,000, and a weight-average molecular weight (Mw) of 25,000 to 50,000. When this is used, desirable triboelectric properties can be imparted without affecting the thermal properties required for toner particles. Furthermore, if the charge-controlled resin contains sulfonic acid groups, for example, the dispersibility of the charge-controlled resin itself in polymerizable monomer compositions, as well as the dispersibility of colorants, can be improved, further enhancing coloring power, transparency, and triboelectric properties.

[0067] These charge control agents or charge control resins may be added individually or in combination of two or more types. The amount of charge control agent or charge control resin added is preferably 0.01 parts by mass or more and 20.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 10.0 parts by mass or less, per 100.0 parts by mass of the binder resin.

[0068] <Toner manufacturing method> The method for producing toner is not particularly limited, and known methods such as grinding, suspension polymerization, dissolution-suspension, emulsification-coagulation, and dispersion polymerization can be used. In any such method for producing toner particles, it is preferable to obtain toner particles by adding a boric acid source when mixing the raw materials. Here, it is preferable that the toner be produced by the method shown below. That is, it is preferable that the toner be produced by the emulsification-coagulation method.

[0069] Preferably, the toner manufacturing method is the following steps (1) to (3) (1) Dispersion step to prepare a dispersion of binder resin fine particles containing a binder resin, (2) An aggregation step in which the binder resin fine particles contained in the dispersion of the binder resin fine particles are aggregated to form aggregates, and (3) Fusion process of heating and fusing the aggregate It has, In at least one of steps (2) and (3), a boric acid source is added to the dispersion.

[0070] When toner is manufactured by the emulsification and agglutination method, it is preferable because the shape of the toner can be easily controlled and boric acid is easily dispersed uniformly near the surface of the toner particles. The details of the emulsification and agglutination method are described below.

[0071] <Emulsification aggregation method> The emulsification and agglutination method is a method for producing toner particles by first preparing an aqueous dispersion of fine particles made from the constituent materials of toner particles, which are sufficiently smaller than the target particle size, agglutinating these fine particles in an aqueous medium until they reach the particle size of toner particles, and then fusing them with resin by heating or other means. In other words, the emulsification agglutination method involves a dispersion step to prepare a dispersion of fine particles made from the constituent materials of the toner particles, an agglutination step to agglutinate the fine particles made from the constituent materials of the toner particles and control the particle size until it reaches the particle size of the toner particles, a fusion step to fuse the resin contained in the obtained agglutinated particles, a spheroidization step to control the surface shape of the toner by further melting it by heating, a subsequent cooling step, a metal removal step to filter the obtained toner and remove excess polyvalent metal ions, a filtration and washing step to wash with ion-exchanged water, and a step to remove moisture from the washed toner particles and dry them, thereby producing toner particles.

[0072] <Process for preparing a resin fine particle dispersion (dispersion process)> Resin fine particle dispersions can be prepared by known methods, but are not limited to these methods. Known methods include, for example, emulsion polymerization, self-emulsification, phase inversion emulsification, in which a resin is emulsified by adding an aqueous medium to a resin solution dissolved in an organic solvent, or forced emulsification, in which the resin is emulsified by high-temperature treatment in an aqueous medium without using an organic solvent. Specifically, the binder resin is dissolved in an organic solvent capable of dissolving it, and then a surfactant and a basic compound are added. If the binder resin is a crystalline resin with a melting point, it can be dissolved by heating it above its melting point. Next, while stirring with a homogenizer or the like, an aqueous medium is slowly added to precipitate the resin fine particles. After that, the solvent is removed by heating or reducing the pressure to prepare an aqueous dispersion of the resin fine particles. Any organic solvent capable of dissolving the resin can be used, but using an organic solvent that forms a homogeneous phase with water, such as toluene, is preferable from the viewpoint of suppressing the generation of coarse powder.

[0073] The surfactant used in the emulsification process described above is not particularly limited, but examples include sulfate esters, sulfonates, carboxylates, phosphates, and soaps. Examples include anionic surfactants; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol-based, alkylphenol ethylene oxide adduct-based, and polyhydric alcohol-based surfactants. These surfactants may be used individually or in combination of two or more types. Examples of basic compounds used in the dispersion process include inorganic bases such as sodium hydroxide and potassium hydroxide; and organic bases such as ammonia, triethylamine, trimethylamine, dimethylaminoethanol, and diethylaminoethanol. These basic compounds may be used individually or in combination of two or more. Furthermore, the 50% particle size (D50) of the volume distribution of the binder resin fine particles in an aqueous dispersion of resin fine particles is preferably 0.05 μm to 1.0 μm, and more preferably 0.05 μm to 0.4 μm. By adjusting the 50% particle size (D50) of the volume distribution to the above range, it becomes easy to obtain toner particles with a volume average particle size of 3 μm to 10 μm, which is appropriate for toner particles. For measuring the 50% particle size (D50) based on volume distribution, a dynamic light scattering particle size analyzer, NanoTrac UPA-EX150 (manufactured by Nikkiso), is used.

[0074] <Colorant particle dispersion> The colorant particle dispersion, which may be used as needed, can be prepared by the following known methods, but is not limited to these methods. This can be prepared by mixing a colorant, an aqueous medium, and a dispersant using a known mixer such as a stirrer, emulsifier, or disperser. Known dispersants such as surfactants and polymeric dispersants can be used. Both surfactants and polymer dispersants can be removed in the cleaning process described later, but surfactants are preferred from the viewpoint of cleaning efficiency. Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, nonionic surfactants or anionic surfactants are preferred. Nonionic surfactants and anionic surfactants may also be used in combination. The surfactant may be used alone or in combination of two or more. The concentration of the surfactant in the aqueous medium is preferably 0.5% to 5% by mass.

[0075] There are no particular restrictions on the content of colorant microparticles in the colorant microparticle dispersion, but it is preferably 1% to 30% by mass relative to the total mass of the colorant microparticle dispersion. Furthermore, from the viewpoint of the dispersibility of the colorant in the final toner, the 50% particle size (D50) based on the volume distribution is preferably 0.5 μm or less. Similarly, for the same reason, the 90% particle size (D90) based on the volume distribution is preferably 2 μm or less. The dispersed particle size of the colorant fine particles dispersed in the aqueous medium is measured using a dynamic light scattering particle size analyzer (NanoTrack UPA-EX150: manufactured by Nikkiso). Known mixers such as stirrers, emulsifiers, and dispersers used when dispersing colorants in an aqueous medium include ultrasonic homogenizers, jet mills, pressure homogenizers, colloid mills, ball mills, sand mills, and paint shakers. These may be used individually or in combination.

[0076] <Release agent (aliphatic hydrocarbon compound) fine particle dispersion> A release agent dispersion may be used if necessary. The release agent dispersion can be prepared by the following known methods, but is not limited to these methods. The mold release agent dispersion is made by adding a mold release agent to an aqueous medium containing a surfactant, and the melting point of the mold release agent The material can be produced by heating it as described above, dispersing it into particulates using a homogenizer with strong shearing capability (for example, M-Technic's "Creamix W Motion") or a pressure discharge type disperser (for example, Gorin's "Gorin Homogenizer"), and then cooling it to below its melting point. In an aqueous dispersion of the release agent, the particle size of the release agent dispersion is preferably 0.03 μm to 1.0 μm, and more preferably 0.1 μm to 0.5 μm, with a 50% particle size (D50) based on the volume distribution. It is also preferable that no coarse particles of 1 μm or larger are present. By ensuring that the particle size of the release agent dispersion is within the above range, it becomes possible to finely disperse the release agent within the toner, maximizing the bleed-out effect during fixing and achieving good separation. The particle size of the release agent dispersion dispersed in an aqueous medium can be measured using a dynamic light scattering particle size analyzer (NanoTrac UPA-EX150: manufactured by Nikkiso).

[0077] <Mixing process> In the mixing step, a mixture is prepared by mixing a resin microparticle dispersion with, if necessary, at least one of a mold release agent microparticle dispersion and a colorant microparticle dispersion. This can be done using known mixing equipment such as a homogenizer and a mixer.

[0078] <Process for forming aggregated particles (aggregation process)> In the coagulation process, the fine particles contained in the mixed liquid prepared in the mixing process are coagulated to form aggregates of the desired particle size. At this time, a coagulant is added and mixed, and if necessary, heating and at least one of mechanical power are appropriately applied to form aggregates of resin fine particles and, if necessary, at least one of mold release agent fine particles and coloring agent fine particles.

[0079] Examples of flocculants include organic flocculants such as quaternary salt cationic surfactants and polyethyleneimine; inorganic metal salts such as sodium sulfate, sodium nitrate, sodium chloride, calcium chloride, and calcium nitrate; inorganic ammonium salts such as ammonium sulfate, ammonium chloride, and ammonium nitrate; and inorganic flocculants such as divalent or higher metal complexes. It is also possible to add acid to lower the pH and induce soft flocculation; for example, sulfuric acid or nitric acid can be used.

[0080] The flocculant may be added in either the form of a dry powder or an aqueous solution dissolved in an aqueous medium, but it is preferable to add it in the form of an aqueous solution to induce uniform flocculation. Furthermore, it is preferable to add and mix the flocculant at a temperature below the glass transition temperature or melting point of the resin contained in the mixture. Mixing under these temperature conditions allows for relatively uniform flocculation. The flocculant can be mixed into the mixture using known mixing devices such as homogenizers and mixers. The flocculation process is a process of forming aggregates the size of toner particles in an aqueous medium. The volume-average particle size of the aggregates produced in the flocculation process is preferably 3 μm to 10 μm. The volume-average particle size can be measured using a particle size distribution analyzer (Coulter Multisizer III: manufactured by Coulter) using the Coulter method.

[0081] <Process for obtaining a dispersion containing toner particles (fusion process)> In the fusion process, the dispersion containing the aggregates obtained in the agglutination process is first subjected to agglutination cessation under the same stirring conditions as in the agglutination process. Aggregation cessation is achieved by adding a flocculant such as a pH-adjusting base, chelating compound, or inorganic salt compound such as sodium chloride. After the dispersion of aggregated particles in the dispersion is stabilized by the action of the anti-aggregation agent, the binder resin is heated to a temperature above its glass transition temperature or melting point to fuse the aggregated particles and adjust them to the desired particle size. The volume-based 50% particle size (D50) of the toner particles is 3 μm to 10 μm. preferable.

[0082] <Cooling process> If necessary, during the cooling process, the temperature of the dispersion containing the toner particles obtained in the fusion process may be cooled to a temperature lower than at least one of the crystallization temperature and glass transition temperature of the binder resin.

[0083] <Post-processing steps> In the toner manufacturing method, post-processing steps such as a washing step, a solid-liquid separation step, and a drying step may be performed after the cooling step, and by performing the post-processing steps, dried toner particles can be obtained.

[0084] <External addition process> In the external additive process, the toner particles obtained in the drying process are treated with an external additive. The external additive may be external additive A or B. The external additive preferably contains inorganic fine particles. Specifically, examples of external additives include inorganic fine particles such as silica fine particles, alumina fine particles, titanium oxide fine particles, and strontium titanate fine particles, as well as resin fine particles such as vinyl resin, polyester resin, and silicone resin. It is preferable to add these external additives by applying shear force, for example, in a dry state.

[0085] The external additive is preferably at least one inorganic fine particle selected from the group consisting of silica fine particles, alumina fine particles, titanium oxide fine particles, strontium titanate fine particles, etc. The external additive preferably contains strontium titanate fine particles. Furthermore, the external additive preferably contains strontium titanate fine particles and silica fine particles. The content of strontium titanate fine particles in the external additive is preferably 5% to 70% by mass, and more preferably 10% to 55% by mass. The content of silica fine particles in the external additive is preferably 30% to 95% by mass, and more preferably 45% to 90% by mass.

[0086] The method for producing inorganic fine particles such as strontium titanate fine particles is not particularly limited and can be produced by known methods described in Japanese Patent Application Publication No. 2015-84095, etc.

[0087] The external additive may be surface-treated with a silane coupling agent or silicone oil treatment. From the viewpoint of charge amount, it is preferable that the external additive contains inorganic fine particles surface-treated with a fluorine-containing surface treatment agent such as a fluorine-containing silane coupling agent or fluorine-modified silicone oil. It is more preferable that the external additive contains inorganic fine particles surface-treated with a fluorine-containing silane coupling agent. It is even more preferable that the external additive contains inorganic fine particles surface-treated with a fluorine-containing silane coupling agent and a fluorine-free silane coupling agent.

[0088] Examples of fluorine-containing silane coupling agents include 3,3,3-trifluoropropylmethyldimethoxysilane, 3,3,3-trifluoropropylmethyldiethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, perfluorooctylethyltriethoxysilane, and 1,1,1-trifluorohexyldiethoxysilane.

[0089] Examples of fluorine-free silane coupling agents include methyltrimethoxysilane, ethyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, propyltrimethoxysilane, isobutyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, propyltriethoxysilane, and isobutyltriethoxysilane.

[0090] The surface treatment method is not particularly limited and can be manufactured by known methods. For example, inorganic fine particles are placed in a container equipped with a stirring device such as a Henschel mixer, stirred under nitrogen purging, a surface treatment agent is sprayed and mixed with the inorganic fine particles, and then heated to cause a reaction. The type and amount of surface treatment agent can be appropriately changed according to the desired charge level. Approximately 2 to 10 parts by mass of surface treatment agent per 100 parts by mass of inorganic fine particles is preferred. It is particularly preferable to use 3,3,3-trifluoropropylmethyldimethoxysilane and isobutyltrimethoxysilane.

[0091] In a method for producing toner particles, it is preferable to have a shell formation step in which, after obtaining toner particles (core particles) by the above-described arbitrary production method, resin fine particles containing a shell resin are further added to an aqueous medium in which the core particles are dispersed, and the resin adheres to the core particles to form a shell. In a method for producing toner by emulsification agglutination, it is preferable to have a shell formation step in which, after forming agglutinated particles (core particles) by an agglutination step, resin fine particles containing a shell resin are further added, and the resin adheres to the core particles to form a shell. That is, it is preferable that the toner particles have core particles containing a binder resin and a shell on the surface of the core particles. The resin for the shell may be the same resin as the binder resin, or a different resin may be used. The amount of resin to be added for the shell is preferably 1 to 10 parts by mass, more preferably 2 to 7 parts by mass, per 100 parts by mass of binder resin contained in the core particles.

[0092] In this case, the toner manufacturing method preferably has the following steps. (1) Dispersion step to prepare a dispersion of binder resin fine particles containing a binder resin, (2-1) An aggregation step in which the binder resin fine particles contained in the dispersion of the binder resin fine particles are aggregated to form an aggregate, (2) A shell forming step in which resin fine particles containing a resin for the shell are further added to a dispersion containing the aggregate and attached to the aggregate to form an aggregate having a shell, and (3) Fusion process of heating and fusing the aggregate in which the shell has been formed

[0093] Furthermore, in order to facilitate the inclusion of boric acid near the surface of the toner particles, it is preferable to add the boric acid source together with the resin fine particles containing the shell resin in step (2-2) to the dispersion containing the aggregate.

[0094] The boric acid source can be boric acid itself, or a compound that can be converted into boric acid during toner manufacturing by pH control or other means. For example, at least one selected from the group consisting of boric acid, borax, organic boric acid, borate salts, boric acid esters, etc. For example, the boric acid source can be added and controlled so that boric acid is contained in the aggregates. Preferably, the pH is controlled to acidic conditions in the aggregation step of (2-1), and the shell formation step is carried out.

[0095] Boric acid may be present in the aggregate in an unsubstituted state. The boric acid source is preferably at least one selected from the group consisting of boric acid and borax. When toner is manufactured in an aqueous medium, it is preferable to add it as a borate from the viewpoint of reactivity and manufacturing stability. Specifically, the boric acid source more preferably contains at least one selected from the group consisting of sodium tetraborate, borax, ammonium borate, etc., and even more preferably borax.

[0096] Borax, represented as sodium tetraborate (Na2B4O7) decahydrate, is preferable when used in an acidic environment with an aqueous medium, as it converts to boric acid in an acidic aqueous solution. It can be added as a dry powder or as an aqueous solution dissolved in an aqueous medium, but it is preferable to add it as an aqueous solution to ensure uniform aggregation. The concentration of the aqueous solution can be appropriately adjusted according to the concentration to be included in the toner, for example, 1 to 20% by mass. To convert it to boric acid, it is preferable to maintain an acidic pH before, during, or after addition. For example, 1.5 to 5.0, preferably 2.0 to 4. It is sufficient to control the pH to 0. Preferably, the pH is controlled before the aggregation step in which aggregates are formed. That is, it is preferable to control the pH to acidic conditions in the mixing step, which is before the aggregation step, in which the dispersion of binder resin fine particles and, if necessary, other dispersions such as a release agent fine particle dispersion are mixed.

[0097] Next, we will describe the measurement methods for each physical property.

[0098] The boric acid content in toner particles is measured using X-ray fluorescence and determined by a calibration curve. The measurement of boron using X-ray fluorescence conforms to JIS K 0119-1969, and is specifically as follows: The measurement equipment used is the wavelength-dispersive X-ray fluorescence analyzer "Axios" (PANalytical), and its accompanying dedicated software "SuperQ ver.4.0F" (PANalytical) for setting measurement conditions and analyzing measurement data. Rh is used as the anode of the X-ray tube, the measurement atmosphere is vacuum, the measurement diameter (collimator mask diameter) is 27 mm, and the measurement time is 10 seconds. Furthermore, when measuring the light element boron, it is detected using a proportional counter (PC). For the measurement sample, 4g of toner particles were placed in a dedicated aluminum ring for pressing and leveled. Using a tablet molding and compression machine "BRE-32" (manufactured by Maekawa Testing Machinery Co., Ltd.), the pellets were pressurized at 20MPa for 60 seconds to form pellets with a thickness of approximately 2mm and a diameter of approximately 39mm. The count rate (unit: cps) of B-Kα rays observed at a diffraction angle (2θ) = 41.75° when PET is used as the spectroscopic crystal was measured. In this case, the acceleration voltage and current values ​​of the X-ray generator will be set to 32kV and 125mA, respectively. Furthermore, the amount of boric acid (mass %) in the toner particles is determined from a separately created calibration curve for boric acid.

[0099] Measurement can also be performed using toner particles from which external additives have been removed using the method described below. Add 160g of sucrose (manufactured by Kishida Chemical Co., Ltd.) to 100mL of deionized water and dissolve it while heating in a water bath to prepare a concentrated sucrose solution. Add 31g of the above concentrated sucrose solution and 6mL of Contaminon N (a 10% by mass aqueous solution of 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.) to a centrifuge tube (capacity 50mL). Add 1.0g of toner and break up any clumps of toner with a spatula or similar tool. Shake the centrifuge tube in a shaker (AS-1N, sold by AS ONE Corporation) at 300 spm (strokes per min) for 20 minutes. After shaking, transfer the solution to a glass tube for a swing rotor (50mL) and separate it using a centrifuge (H-9R, manufactured by Kokusan Co., Ltd.) at 3500 rpm for 30 minutes. This operation separates the toner particles from the external additive. Visually confirm that the toner particles and aqueous solution are sufficiently separated, and collect the toner particles separated to the top layer using a spatula or similar tool. Filter the collected toner particles using a vacuum filter, then dry them in a dryer for at least one hour to obtain a sample for measurement. Repeat this operation multiple times to obtain the required amount.

[0100] <Identification and quantification of boric acid contained in toner particles> The identification and measurement of boric acid content in toner particles are performed by the following method. Alternatively, toner particles obtained by removing the external additives from the toner using the method described above can also be used as a sample. IR analysis is performed using a Fourier transform infrared spectrometer (Spe) equipped with a Universal ATR Sampling Accessory. Measurements will be taken using the ATR method with a ctrum One (manufactured by PerkinElmer). The general measurement procedure is as follows: The incident angle of infrared light (λ=5μm) is set to 45°. The ATR crystal used is Ge's AT. An R crystal (refractive index = 4.0) is used. Other conditions are as follows: Range Starting height: 4000cm-1 End :650cm -1 (Ge ATR crystal) Duration Scan number :16 Resolution :4.00cm -1 Advanced :with CO2 / H2O correction (1) Mount a Ge ATR crystal (refractive index = 4.0) on the apparatus. (2) Set the scan type to Background and units to EGY, then measure the back ground. (3) Set the scan type to Sample and units to A. (4) Accurately weigh 0.01 g of toner particles onto the ATR crystal. (5) Press the sample with a pressure arm. (Force Gauge is 90) (6) Measure the sample. Check 1380 cm in the absorption spectrum -1 If an absorption peak is detected at 1380 cm -1 , it is determined that a peak corresponding to boric acid has been detected. In addition, elemental analysis can be performed by energy-dispersive X-ray spectroscopy (EDX) using a transmission electron microscope (TEM) to confirm whether boron derived from boric acid is present in the observation area of the cross-section.

[0101] <Toner Detachment Treatment A> Weigh 20 g of "Contaminon N" (a 10 mass% aqueous solution of a neutral detergent for precision measuring instrument cleaning with pH 7, consisting of a nonionic surfactant, an anionic surfactant and an organic builder) into a 50 mL vial, and mix with 1 g of toner. Set the vial on "KM Shaker" (model: V.SX) manufactured by Iwaki Industry Co., Ltd., set the speed to 50, and shake for 300 seconds. The external additive that detaches from the toner and transfers to the liquid side thereby is external additive A. Thereafter, a centrifuge (H-9R; manufactured by Kokusan Co., Ltd.) (16.67S -1After 5 minutes, the toner and external additive A, which has migrated to the supernatant liquid, are separated. The settled toner is removed, and the mixture is dried under vacuum (40°C / 24 hours) to obtain only external additive A.

[0102] <Toner detachment process B> Weigh 20g 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) into a 50mL vial and mix with 1g of toner. The product is placed in an Iwaki Sangyo Co., Ltd. "KM Shaker" (model: V.SX), and the speed is set to 50 and shaken for 30 seconds. The external additive that detaches from the toner and migrates to the liquid side is external additive B. Subsequently, a centrifugal separator (H-9R; manufactured by Kokusan Co., Ltd.) (16.67S) -1 After 5 minutes, the toner and external additive B, which has migrated to the supernatant liquid, are separated. The settled toner is removed, and the mixture is dried under vacuum (40°C / 24 hours) to obtain only external additive B.

[0103] <Contents of external additives A and B, and the proportion of external additive B> As described above, desorption treatments A and B are performed, and based on the amounts of external additives A and B obtained, the content of external additives A and B, and the ratio (mass%) of external additive B to external additive A are calculated.

[0104] <External additive A> no Ki Measurement of charge amount using Carrier (F81) External additive A and Carrier (F81) Place 0.10g of external additive A and 1.90g of F81 into a plastic bottle with a lid, and leave it in an environment with a temperature of 23.0℃ and a relative humidity of 50% for 5 days. The lid of the plastic bottle containing the carrier and external additive A is closed, and the mixture of the carrier and external additive A is charged by shaking it for 1 minute at a speed of 4 reciprocations per second using a shaker (YS-LD, manufactured by Yayoi Co., Ltd.). Figure 1 shows a schematic diagram of the electrostatic charge measuring device. 0.3 g of a triboelectrically charged mixture is placed in a metal measuring container 2, which has a screen 3 with a mesh size of 20 μm at the bottom, and a metal lid 4 is placed over it. The total mass of the measuring container 2 at this time is accurately weighed and recorded as W1 (g). Next, using the suction device 1 (the part in contact with the measuring container 2 is at least an insulator), suction is initiated from the suction port 7, and the airflow control valve 6 is adjusted to set the pressure of the vacuum gauge 5 to 2.5 kPa within 10 seconds. The time from measuring W1 to starting suction should be within 30 seconds. Suction is performed in this state for 2 minutes to remove the external additive A. Let the amount of charge accumulated in the capacitor 8 at this time be Q (μC). 9 is a potentiometer. The total mass of the measuring container after suction is accurately weighed and set to W2 (g). The charge amount of external additive A (μC / g) is calculated as shown in the formula below. External additive A no Ki Charge amount using Carrier (F81) = Q / (W1-W2)

[0105] <Method for measuring the number-average particle size of external additives> The particle size of external additives is measured using a scanning electron microscope "S-4800" (product name; manufactured by Hitachi, Ltd.). The major axis of the primary particles of the external additive is measured in a field of view magnified up to 200,000 times, and the number-average particle size is determined. The observation magnification is adjusted as appropriate depending on the size of the external additive.

[0106] <Measurement of weight-average particle size (D4) and number-average particle size (D1) of toner or toner particles> The weight-average particle size (D4) and number-average particle size (D1) of toner or toner particles are 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. 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. Before performing measurements and analysis, configure the dedicated software as follows.

[0107] 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. 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. The specific measurement method is as follows:

[0108] (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 or toner particles to the electrolytic aqueous solution in small amounts and disperse them. 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 toner or toner particles 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 reaches 50,000. (7) The measurement data is analyzed using the dedicated software provided with the device to calculate the weight-average particle size (D4). Note that when the dedicated software is set to graph / volume% the "average diameter" on the analysis / volume statistics (arithmetic mean) screen is the weight-average particle size (D4), and when the dedicated software is set to graph / number% the "average diameter" on the analysis / number statistics (arithmetic mean) screen is the number-average particle size (D1). [Examples]

[0109] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. Unless otherwise specified, the parts used in the formulations of the examples are by mass.

[0110] <Example of toner particle 1 manufacturing> "Synthesis of polyester resin 1" • 9 mol parts of bisphenol A ethylene oxide 2 molar adduct • 95 mol parts of bisphenol A propylene oxide 2 molar adduct 50 mol parts of terephthalic acid • 30 mol parts of fumaric acid • 25 mol parts of dodecenyl succinate The above monomers were placed in a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column, and the temperature was raised to 195°C in 1 hour to confirm that the reaction system was uniformly stirred. 1.0 part of tin distearate was added to 100 parts of these monomers. The temperature was then raised from 195°C to 250°C over 5 hours while the generated water was removed by distillation, and the dehydration condensation reaction was carried out at 250°C for a further 2 hours. As a result, a polyester resin 1 was obtained with a glass transition temperature of 60.2°C, an acid value of 16.8 mg KOH / g, a hydroxyl value of 28.2 mg KOH / g, a weight-average molecular weight of 11200, and a number-average molecular weight of 4100.

[0111] "Synthesis of polyester resin 2" • 48 mol parts of bisphenol A-ethylene oxide 2 molar adduct • 48 mol parts of bisphenol A-propylene oxide 2 molar adduct • 65 mol parts of terephthalic acid • 30 mol parts of dodecenyl succinate The above monomers were placed in a flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and rectification column, and the temperature was raised to 195°C over 1 hour to confirm that the reaction system was uniformly stirred. 0.7 parts of tin distearate were added to 100 parts of these monomers. The temperature was then raised from 195°C to 240°C over 5 hours while distilling off the generated water, and the dehydration condensation reaction was carried out at 240°C for a further 2 hours. Next, the temperature was lowered to 190°C, 5 moles of trimellitic anhydride were gradually added, and the reaction was continued at 190°C for 1 hour. As a result, polyester resin 2 was obtained with a glass transition temperature of 55.2°C, an acid value of 14.3 mg KOH / g, a hydroxyl value of 24.1 mg KOH / g, a weight-average molecular weight of 43,600, and a number-average molecular weight of 6,200.

[0112] "Preparation of Resin Particle Dispersion 1" • Polyester resin 1 100 pieces • Methyl ethyl ketone 50 parts Isopropyl alcohol 20 parts Methyl ethyl ketone and isopropyl alcohol were added to a container. Then, the resin was gradually added and stirred to completely dissolve it and obtain a polyester resin 1 solution. The container containing this polyester resin 1 solution was set to 65°C, and while stirring, a 10% ammonia aqueous solution was gradually added dropwise until it reached a total of 5 parts. Then, 230 parts of deionized water were gradually added dropwise at a rate of 10 ml / min to induce phase inversion emulsification. Finally, the solvent was removed by reducing the pressure with an evaporator to obtain a polyester resin 1 resin particle dispersion 1. The volume-average particle size of this resin particle was 135 nm. The solid content of the resin particles was adjusted to 20% with deionized water.

[0113] "Preparation of Resin Particle Dispersion 2" • Polyester resin 2 100 pieces • Methyl ethyl ketone 50 parts Isopropyl alcohol 20 parts Methyl ethyl ketone and isopropyl alcohol were added to a container. Then, the above materials were gradually added and stirred to completely dissolve them and obtain a polyester resin 2 solution. The container containing this polyester resin 2 solution was set to 40°C, and while stirring, a 10% ammonia aqueous solution was gradually added dropwise until the total volume reached 3.5 parts. Then, 230 parts of deionized water were gradually added dropwise at a rate of 10 ml / min to induce phase inversion emulsification. Further desolvation was performed by reducing the pressure to obtain a polyester resin 2 resin particle dispersion 2. The volume-average particle size of the resin particles was 155 nm. The solid content of the resin particles was adjusted to 20% with deionized water.

[0114] "Preparation of a dispersion of coloring agent particles" • Copper phthalocyanine (pigment blue 15:3) 45 parts • Ionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 units • Ion-exchanged water (190 units) The above components were mixed and dispersed for 10 minutes using a homogenizer (IKA Ultra-Turrax). Then, the mixture was dispersed for 20 minutes at a pressure of 250 MPa using an ultimateizer (opposing impact type wet pulverizer: Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion with a volume average particle size of 120 nm and a solid content of 20%.

[0115] "Preparation of mold release agent particle dispersion" • Release agent (hydrocarbon wax, melting point: 79°C) 15 parts • Ionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 2 parts • Ion-exchanged water (240 units) The above mixture was heated to 100°C, thoroughly dispersed in an IKA Ultra-Turrax T50, then heated to 115°C in a pressure-discharge type Gorin homogenizer for 1 hour, and the dispersion treatment was performed, followed by volume averaging. A dispersion of release agent particles with a particle size of 160 nm and a solid content of 20% was obtained.

[0116] "Manufacturing of toner particles 1" ·Resin particle dispersion 1 500 parts ·Resin particle dispersion 2 400 parts • Dispersion of coloring agent particles (50 units) • Release agent particle dispersion 80 parts First, as a core formation step, the aforementioned materials were placed in a round stainless steel flask and mixed. Next, the mixture was dispersed for 10 minutes at 5000 r / min using a homogenizer Ultra-Turrax T50 (manufactured by IKA). After adding a 1.0% aqueous nitric acid solution and adjusting the pH to 3.0, the mixture was heated to 58°C in a heating water bath using a stirring blade, adjusting the rotation speed as needed to ensure the mixture was stirred. The volume-average particle size of the formed aggregated particles was checked as needed using a Coulter Multisizer III, and when aggregated particles (cores) with a size of 5.0 μm were formed, the following materials were added as a shell formation step and stirred for a further hour to form the shell. ·Resin particle dispersion 1 40 parts 300 bottles of deionized water ·19 parts of 10.0% by mass borax aqueous solution (Borax; manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., sodium tetraborate decahydrate)

[0117] Subsequently, the pH was adjusted to 9.0 using a 5% sodium hydroxide aqueous solution, and the mixture was heated to 89°C while continuing to stir. Heating was stopped when the desired surface shape was obtained, and the mixture was cooled to 25°C. After filtration and solid-liquid separation, the mixture was washed with deionized water. After washing, the mixture was dried using a vacuum dryer to obtain toner particles 1 with a weight-average particle size (D4) of 6.8 μm. The physical properties of the obtained toner particles 1 are shown in Table 1.

[0118] <Manufacturing examples of toner particles 2-6 and 11> Toner particles 2-6 and 11 were obtained using the same method as for toner 1, except for changes to the formulation and conditions shown in Table 1. The physical properties of these particles are shown in Table 1.

[0119] <Example of toner particle 7 manufacturing> ·Resin particle dispersion 1 350.0 parts • Release agent particle dispersion 50.0 parts • Dispersion of coloring agent particles: 80.0 parts • Ion-exchanged water 160.0 parts The aforementioned materials were placed in a round stainless steel flask and mixed. The mixture was then dispersed for 10 minutes at 5000 r / min using an IKA Ultra-Turrax T50 homogenizer. A 1.0% nitric acid aqueous solution was added to adjust the pH to 3.0. The mixture was then heated to 58°C in a heating water bath, using a stirring blade to maintain a constant rotation speed. The volume-average particle size of the formed aggregated particles was checked periodically using a Coulter Multisizer III. When aggregated particles of 4.0 μm were formed, 19.0 parts of a 10.0% by mass borax aqueous solution were added. After adding the borax, 150.0 parts of resin particle dispersion 1 were added, and the volume-average particle size of the aggregated particles was checked again. When aggregated particles of 6.0 μm were formed, the pH was adjusted to 9.0 using a 5% sodium hydroxide aqueous solution. The mixture was then heated to 75°C while continuing to stir. Finally, the aggregated particles were fused by holding the mixture at 75°C for 1 hour. Subsequently, the polymer crystallization was promoted by cooling to 50°C and holding the temperature for 3 hours. The mixture was then cooled to 25°C, filtered, and separated into solid and liquid components, followed by washing with deionized water. After washing, the mixture was dried using a vacuum dryer to obtain toner particles 7. The physical properties are shown in Table 1.

[0120] <Example of toner particle 8 manufacturing> In the example of producing toner particle 1, toner particle 8 was obtained in the same manner as in the example of producing toner particle 1, except that the borax aqueous solution was replaced with 12.0 parts of a 10.0% by mass boric acid aqueous solution (boric acid; boric acid H3BO3 manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The physical properties are shown in Table 1.

[0121] <Example of toner particle 9 manufacturing> 710 parts of deionized water and 850 parts of a 0.1 mol / liter Na3PO4 aqueous solution were added to a four-necked container, and the mixture was stirred at 12,000 rpm using a TK homomixer while maintaining the temperature at 60°C. Then, 68 parts of a 1.0 mol / liter CaCl2 aqueous solution were gradually added to prepare an aqueous dispersion medium containing fine, poorly water-soluble dispersion stabilizer Ca3(PO4)2. • Styrene 76 parts n-butyl acrylate 24 parts • CIPigment Blue 15:3: Manufactured by Dainichi Seika Co., Ltd. 6.5 parts • Polyester resin (1) 5 parts (Terephthalic acid-propylene oxide modified bisphenol A (2 molar adduct) (molar ratio = 51:50), acid value = 10 mg KOH / g, glass transition temperature = 70°C, Mw = 10500, Mw / Mn = 3.20) • Load electrical control agent (aluminum compound of 3,5-di-tert-butylsalicylic acid) 0.4 parts Fischer-Tropsch wax (maximum endothermic peak temperature = 75°C) 7.5 parts ·10.0% by mass borax aqueous solution 19.0 parts The above materials were stirred for 3 hours using an attritor to disperse each component in polymerizable monomers, thereby preparing a monomer mixture. 10.0 parts of 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate (50% toluene solution), a polymerization initiator, were added to the monomer mixture to prepare a polymerizable monomer composition. The polymerizable monomer composition was placed in an aqueous dispersion medium and granulated for 5 minutes while maintaining the stirrer speed at 10,000 rpm. Subsequently, the high-speed stirrer was replaced with a propeller-type stirrer, the internal temperature was raised to 70°C, and the mixture was reacted for 6 hours with slow stirring. Next, the temperature inside the container was raised to 80°C and maintained for 4 hours, after which it was gradually cooled to 30°C at a cooling rate of 1°C per minute to obtain a slurry. Dilute hydrochloric acid was added to the container containing the slurry to remove the dispersion stabilizer. Furthermore, the slurry was filtered, washed, and dried to obtain toner particles 9. The physical properties of the toner particles 9 are shown in Table 1.

[0122] <Example of toner particle manufacturing 10> • Polyester resin 1 60.0 parts • Polyester resin 2 40.0 parts • Copper phthalocyanine pigment (pigment blue 15:3) 6.5 parts • Release agent (hydrocarbon wax, melting point: 79°C) 5.0 parts • Plasticizer (ethylene glycol distearate) 15.0 parts • Boric acid powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) 1.5 parts The above materials were pre-mixed in an FM mixer (manufactured by Nippon Coke Industries Co., Ltd.), and then melt-kneaded using a twin-screw kneading extruder (PCM-30 model, manufactured by Ikegai Iron Works Co., Ltd.). The resulting mixture was cooled, coarsely ground in a hammer mill, then 130 parts of ethyl acetate were added, the mixture was heated to 80°C, stirred at 5000 rpm for 1 hour in a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and then cooled to 30°C to obtain the solution. In a separate container, 400 parts water and 5 parts Eleminor MON-7 (manufactured by Sanyo Chemical Industries, Ltd.) were added and heated to 30°C. Then, 100 parts of the above solution were added while stirring at 13,000 rpm using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), and the mixture was stirred for a further 20 minutes to obtain a slurry. The obtained slurry was desolvented for 8 hours at 30°C under reduced pressure while being gently stirred. After that, the toner particles 10 were obtained by aging at 45°C for 4 hours, followed by washing, filtering, and drying processes.

[0123] The physical properties of the obtained toner particles are shown in Table 1. [Table 1] ATR-IR analysis using germanium on toner particles 1-10 detected a peak corresponding to boric acid. This peak was not detected in toner particle 11.

[0124] <Example of strontium titanate particle production> Metatitanic acid produced by the sulfuric acid method was subjected to iron removal and bleaching treatment, then desulfurization treatment was performed 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 filtration and washing. Water was added to the washed cake to form a slurry with a TiO2 concentration of 1.90 mol / L, and then hydrochloric acid was added to bring the pH to 1.4 and perform gelatinization treatment. 1.90 moles of desulfurized and disintegrated metatitanic acid were taken as TiO2 and placed in a 3 L reaction vessel. To the disintegrated metatitanic acid slurry, 2.185 moles of strontium chloride aqueous solution were added to achieve a SrO / TiO2 (molar ratio) of 1.15, and the TiO2 concentration was adjusted to 1.039 mol / L. 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. 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 decanted to obtain a slurry containing strontium titanate.

[0125] <Examples of silica particle manufacturing> Silica microparticles (fumed silica; primary particle volume average particle size of 60 nm) were placed in an autoclave equipped with a stirrer and heated to 200°C while being stirred to a fluid state. The autoclave was sealed after replacing the inside with nitrogen gas, and 10 parts hexamethyldisilazane (HMDS) was sprayed into the autoclave for every 100 parts silica microparticles to fluidize the microparticles, and the surface was treated with a silane compound. This reaction was continued for 60 minutes, after which the reaction was terminated. After the reaction was complete, the autoclave was depressurized and washed with a nitrogen gas stream to remove excess hexamethyldisilazane and by-products from the hydrophobic silica microparticles.

[0126] <Manufacturing example of external additive 1> The obtained slurry containing strontium titanate was adjusted to 40°C, and hydrochloric acid was added to adjust the pH to 2.5. Then, 4.5 parts of 3,3,3-trifluoropropylmethyldimethoxysilane and 4.5 parts of isobutyltrimethoxysilane were added per 100 parts of solids, 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. Subsequently, it was subjected to grinding to obtain external additive 1.

[0127] <Manufacturing examples of external additives 2-9> Except for changing the conditions in Table 2, the manufacturing procedure was the same as for external additive 1, and external additives 2 to 9 were obtained.

[0128] [Table 2]

[0129] <Example of Toner 1 manufacturing> Toner particles 1 were subjected to external additives. 100.0 parts of toner particles 1, 0.5 parts of external additive 1, and 1.0 part of external additive 9 were dry-mixed for 7 minutes at a peripheral speed of 38 m / sec using a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) to obtain toner 1. The physical properties of the obtained toner 1 are shown in Table 4.

[0130] <Manufacturing examples for toners 2-25> Except for changing the conditions in Table 3, the manufacturing process was the same as for Toner 1, and Toners 2-25 were obtained. The physical properties of the toner are shown in Table 4.

[0131] [Table 3]

[0132] [Table 4] The amounts of external additive A and external additive B are expressed as parts by mass per 100 parts by mass of toner particles. The proportion of external additive B is expressed as a mass % relative to external additive A.

[0133] <Example 1> (Toner evaluation) The following real-world evaluation was performed using Toner 1. The evaluation results are shown in Table 5. A modified Canon LBP7600C laser beam printer was used. The modifications involved changing the gears and software of the evaluation unit to set the developing roller rotation speed to twice that of the drum. In addition, the pre-exposure unit inside the laser beam printer was removed. By making these modifications, the migration of external additives from the toner is promoted, resulting in a more stringent mode for evaluating image density changes, scratches on the electrostatic latent image carrier, and the level of contamination of charged components.

[0134] Next, the electrophotographic apparatus and process cartridge were left in an environment of 23°C and 50% RH for 48 hours to allow them to acclimate to the measurement environment. After this period, the equipment was subjected to further testing in the same normal temperature and humidity environment (23°C / 50% RH) using letter-sized Business 4200 paper (Xerox, 75 g / m²). 2 ) Leave a 50mm margin on both sides and print an image with a 4.0% print density horizontally in the center, up to 20,000 copies, after printing 10 copies, 1,000 copies, and 20,000 copies. Evaluation was performed after the number of printouts was completed.

[0135] <Post-durability image streak evaluation> Image streaks were evaluated as follows: First, a drum unit for image checking and a drum unit for durability testing were prepared. The durability drum unit was installed, and the above 20,000 printouts were performed. Next, a toner evaluation electrostatic roller was attached to the drum unit for image checking, and image output was performed. Toner amount: 0.25 mg / cm² 2 Halftone images were output and evaluated according to the following criteria. A score of C or higher was considered good. (Evaluation Criteria) A: No vertical streaks of white are visible in the image. B: One or two vertical streaks of white are visible on the image. C: Three to four vertical, streaky white areas are visible on the image. D: Five or more vertical streaks of white are visible in the image. It is known that when the charge is broad, streaky density variations can occur in halftone images.

[0136] <Durability evaluation (black dots)> After printing 20,000 images, 10 consecutive solid white images were printed and evaluated according to the following criteria. A score of C or higher was considered good. (Evaluation Criteria) A: No black dots are visible on the 10 images. B: One or two black dots can be seen on the 10 images. C: Three to five black dots can be seen on 10 images. D: Six or more black dots are visible on 10 images. It is known that when the toner charges up, localized printing occurs on white areas, resulting in black spots.

[0137] <Evaluation of component contamination (cover after durability)> After printing 10 images and then 1000 images, nine images with a solid 3cm vertical band in the center and one white image using paper with a sticky note attached to the center of the printed surface for masking were printed consecutively, and the density of the white image was evaluated. The evaluation criteria were as follows, with C or higher being considered good. The haze density was measured using a digital white photometer (TC-6D model, manufactured by Tokyo Denshoku Co., Ltd., using a green filter) to determine the reflectance (%). For the white image, after removing the sticky notes, the reflectance (%) was measured at 5 points in both the area with the sticky note and the area without the sticky note. The average value was then calculated, and the difference between these average values ​​was used as the haze density. A: The difference in fringe density between the time after printing 10 sheets and the time after printing 1000 sheets is 0.20 or less. B: The difference in fringe density between the printout of 10 sheets and the printout of 1000 sheets is between 0.21 and 0.50. C: The difference in fringe density between the printout of 10 sheets and the printout of 1000 sheets is between 0.51 and 0.80. D: The difference in fringe density between the time of printing 10 sheets and the time of printing 1000 sheets is 0.81 or more. It is known that when outputting a series of vertical band images, if the charging roller is contaminated, toner remaining on the drum can appear on the white areas, causing fogging.

[0138] <Initial concentration evaluation> After printing 10 images and again after printing 1000 images, solid images were printed, and the difference between the initial density and the density after durability was evaluated according to the following criteria, with a score of C or higher being considered good. For measuring image density, a "Macbeth RD918 reflectance densitometer" (manufactured by Macbeth Corporation) is used. Then, the relative density of the white background area with a document density of 0.00 relative to the printout image was measured. The results were evaluated using the arithmetic mean of the image density at any five points in the solid image. A: The difference in solid color density between the print run of 10 sheets and the print run of 1000 sheets is 0.03 or less. B: The difference in solid color density between the print run of 10 sheets and the print run of 1000 sheets is between 0.04 and 0.06. C: The difference in solid color density between the print run after 10 copies and the print run after 1000 copies is between 0.07 and 0.09. D: The difference in solid color density between the print run of 10 sheets and the print run of 1000 sheets is 0.10 or more. It is also known that toners with good charge build-up tend to have an initial density close to that during the durability period.

[0139] <Examples 2-21 and Comparative Examples 1-4> The same evaluation as in Example 1 was performed using toners 2-25. The evaluation results for Examples 2-21 and Comparative Examples 1-4 are shown in Table 5. Examples 6, 8, 9, 11, 15-17, and 21 were evaluated as reference examples.

[0140] [Table 5] [Explanation of symbols]

[0141] 1: Suction device, 2: Measuring container, 3: Screen, 4: Lid, 5: Vacuum gauge, 6: Air volume control valve, 7: Suction port, 8: Condenser, 9: Potential meter

[0142] This disclosure relates to the following configuration and method. (Composition 1) Toner particles containing a binder resin, and External additive on the surface of the toner particles A toner containing, The binder resin contains a resin having ester bonds, In the ATR method, in ATR-IR analysis of toner particles using germanium as the ATR crystal, a peak corresponding to boric acid was detected. When the dispersion, in which the toner is dispersed in an aqueous solution containing a surfactant, is subjected to a desorption treatment A by shaking it in a shaker for 300 seconds, and the external additive desorbed from the toner by desorption treatment A is referred to as external additive A, External additive A no Ki A toner characterized by having a charge amount of -0.5 μC / g or less when using a carrier (F81). (Configuration 2) The toner according to configuration 1, wherein the external additive includes inorganic fine particles. (Composition 3) The toner according to configuration 1 or 2, wherein the external additive comprises inorganic fine particles surface-treated with a fluorine-containing silane coupling agent. (Composition 4) The toner according to configuration 3, wherein the external additive further comprises inorganic fine particles surface-treated with a silane coupling agent that does not contain fluorine. (Composition 5) The toner according to configuration 3 or 4, wherein the inorganic fine particles surface-treated with the fluorine-containing silane coupling agent are strontium titanate fine particles surface-treated with the fluorine-containing silane coupling agent. (Composition 6) The toner according to any one of configurations 1 to 4, wherein the external additive comprises strontium titanate fine particles. (Composition 7) The toner according to any one of configurations 1 to 6, wherein, in the X-ray fluorescence measurement of the toner particles, the intensity of boron derived from the boric acid is 0.10 kcps or more and 0.60 kcps or less. (Composition 8) The toner according to any one of configurations 1 to 7, wherein the resin having the ester bond is at least one selected from the group consisting of styrene acrylic resin, polyester resin, mixed resins thereof, and composite resins thereof. (Composition 9) The toner according to any one of configurations 1 to 8, wherein the resin having the ester bond is a polyester resin. (Composition 10) The toner according to any one of configurations 1 to 9, wherein the content of the external additive A is 0.10 parts by mass or more and 10.00 parts by mass or less per 100 parts by mass of the toner particles. (Composition 11) When the dispersion, in which the toner is dispersed in an aqueous solution containing a surfactant, is subjected to a desorption treatment B by shaking it in a shaker for 30 seconds, and the external additive desorbed from the toner by this desorption treatment B is referred to as external additive B, The toner according to any one of configurations 1 to 10, wherein the amount of external additive B relative to external additive A is 20% by mass or more and 80% by mass or less. (Method 12) A method for manufacturing toner as described in any of configurations 1 to 11, (1) A dispersion step to prepare a dispersion of binder resin fine particles containing the binder resin, (2) an aggregation step in which the binder resin fine particles contained in the dispersion of the binder resin fine particles are aggregated to form aggregates, and (3) Fusion process of heating and fusing the aggregates It has, A method for producing toner, characterized in that a boric acid source is added to the dispersion in at least one of steps (2) and (3). (Method 13) A method for manufacturing toner as described in any of configurations 1 to 11, (1) A dispersion step to prepare a dispersion of binder resin fine particles containing the binder resin, (2-1) An aggregation step in which the binder resin fine particles contained in the dispersion of the binder resin fine particles are aggregated to form aggregates, (2) A shell forming step in which resin fine particles containing a resin for the shell are further added to a dispersion containing the aggregate and attached to the aggregate to form an aggregate having a shell, and (3) Fusion process of heating and fusing the aggregate in which the shell has been formed It has, A method for producing toner, characterized in that, in step (2-2), a boric acid source is added to the dispersion containing the aggregate together with resin fine particles containing the resin for the shell.

Claims

1. Toner particles containing a binder resin, and External additive on the surface of the toner particles A toner containing, The binder resin contains a resin having ester bonds, In the ATR method, in ATR-IR analysis of toner particles using germanium as the ATR crystal, a peak corresponding to boric acid was detected. A dispersion is prepared by dispersing the toner in an aqueous solution containing a surfactant, and the dispersion is shaken in a shaker for 300 seconds in a desorption process A. The external additive desorbed from the toner by desorption process A is referred to as external additive A. When the toner is dispersed in an aqueous solution containing a surfactant, and the dispersion is shaken in a shaker for 30 seconds in a desorption treatment B, and the external additive detached from the toner by desorption treatment B is referred to as external additive B, The amount of charge of the external additive A using the carrier (F81) is -30.0 μC / g or more and -5.0 μC / g or less. The amount of external additive A is 0.20 parts by mass or more and 10.00 parts by mass or less per 100 parts by mass of toner particles. The amount of external additive B relative to external additive A is 80% by mass or less. In the X-ray fluorescence measurement of the toner particles, the intensity of boron derived from the boric acid is 0.10 kcps or more and 0.60 kcps or less. A toner characterized by the following features.

2. The toner according to claim 1, wherein the external additive comprises inorganic fine particles.

3. The toner according to claim 1 or 2, wherein the external additive comprises inorganic fine particles surface-treated with a fluorine-containing silane coupling agent.

4. The toner according to claim 3, further comprising inorganic fine particles surface-treated with a silane coupling agent that does not contain fluorine, as the external additive.

5. The inorganic fine particles surface-treated with the fluorine-containing silane coupling agent are fluorine-containing silane coupling agents. The toner according to claim 3, which is strontium titanate fine particles surface-treated with a coupling agent.

6. The toner according to claim 1 or 2, wherein the external additive comprises strontium titanate fine particles.

7. The toner according to claim 1 or 2, wherein the resin having an ester bond is at least one selected from the group consisting of styrene acrylic resin, polyester resin, mixed resins thereof, and composite resins thereof.

8. The toner according to claim 1 or 2, wherein the resin having the ester bond is a polyester resin.

9. The toner according to claim 1 or 2, wherein the amount of external additive B relative to external additive A is 20% by mass or more and 80% by mass or less.

10. A method for manufacturing toner according to claim 1 or 2, (1) A dispersion step to prepare a dispersion of binder resin fine particles containing the binder resin, (2) an aggregation step in which the binder resin fine particles contained in the dispersion of the binder resin fine particles are aggregated to form aggregates, and (3) Fusion process of heating and fusing the aggregates It has, A method for producing toner, characterized in that a boric acid source is added to the dispersion in at least one of steps (2) and (3).

11. A method for manufacturing toner according to claim 1 or 2, (1) A dispersion step to prepare a dispersion of binder resin fine particles containing the binder resin, (2-1) Agglomeration step of agglomerating the binder resin fine particles contained in the dispersion of the binder resin fine particles to form aggregates, (2) A shell forming step in which resin fine particles containing a resin for the shell are further added to a dispersion containing the aggregate and attached to the aggregate to form an aggregate having a shell, and (3) Fusion process of heating and fusing the aggregate on which the shell has been formed. It has, A method for producing toner, characterized in that, in step (2-2), a boric acid source is added to the dispersion containing the aggregate together with resin fine particles containing the resin for the shell.

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