Toner and Method for Producing Toner

Abstract

The present invention relates to a toner and a method for producing the toner. A toner includes toner particles each including a toner base particle and an outermost layer present on the surface of the toner base particle, the toner base particle including a binder resin, wherein a plurality of recesses are formed on the surface of the toner particle, and when T (nm) is the average thickness of the outermost layer in the cross-sectional analysis of the toner particle observed by TEM, and when measuring the recesses on the toner particle from the outermost surface of the outermost layer toward the center of the toner particle using SPM, when a (nm) is the major axis of each recess, b (nm) is the minor axis of each recess, and d (nm) is the depth of each recess, when "n" represents the number of recesses satisfying a specific relationship on the surface of the toner particle per 1 μm<supgt;2< / supgt;, n is from 30 to 200.

Description

Technical Field

[0001] The present disclosure relates to a toner used in a recording method using an electrophotographic method, an electrostatic recording method, or a toner jet system recording method, and also relates to a method for producing the toner. Background Art

[0002] For energy saving, efforts have been made for copiers and printers using the electrophotographic method to reduce the heat required for the fixing device, that is, to improve low-temperature fixability. In addition, for such devices, it is necessary to increase the toner cartridge print volume in order to improve its maintenance characteristics by reducing the toner cartridge replacement frequency. Therefore, in addition to low-temperature fixability, the toner is also required to have durability to stably provide high-quality images even during long-term use. In addition to these, another requirement for the toner is storage stability such that the toner is not affected even in a harsh environment where the temperature and humidity change drastically after production and during transportation to the user.

[0003] In order to achieve these simultaneously, a toner having a core / shell structure has been proposed, in which a shell resin covers the surface of the resin forming the toner core.

[0004] Japanese Patent Application Laid-Open No. 2015-11077 discloses a toner in which the surface of toner core particles is covered with a shell layer formed of a resin containing units derived from monomers for thermosetting resins and units derived from thermoplastic resins.

[0005] Japanese Patent Application Laid-Open No. 2015-141221 discloses a toner showing both excellent fixability and excellent storage properties. In this toner, a shell layer is formed on the surface of the toner core, and in this shell layer, a plurality of recesses each exposing the core are formed.

[0006] Japanese Patent Application Laid-Open No. 2017-116712 discloses a toner having excellent storage properties and excellent low-temperature fixability. This toner has a plurality of recesses on the surface of the toner core, and a shell layer existing on the surface region of the toner core is present in both the region inside the recesses and the region outside the recesses. Summary of the Invention

[0007] However, as a result of the study by the present inventors, it has been found that for the toner described in Japanese Patent Application Laid-Open No. 2015-11077, since the shell layer covers the entire surface of the toner particles, there is room for improvement in low-temperature fixability. It has also been found that the ability to hold external additives may decrease during long-term use.

[0008] Regarding the toner described in Japanese Patent Application Laid-Open No. 2015-141221, it is considered that the hardness distribution of the toner particles is controlled by forming a plurality of recesses exposing the core in the shell layer. However, it has been found that the number of recesses in the shell layer is insufficient, and similar to the toner described in Japanese Patent Application Laid-Open No. 2015-11077, there is room for improvement in low-temperature fixability. In addition, Japanese Patent Application Laid-Open No. 2015-141221 does not solve the storage stability in a harsh environment where temperature and humidity change rapidly.

[0009] It has been found that the toner described in Japanese Patent Application Laid-Open No. 2017-116712 has neither satisfactory storage properties nor satisfactory durability. It has been found that in the toner according to Japanese Patent Application Laid-Open No. 2017-116712, the shell layer exists in both the region inside the recess and the region outside the recess. However, the coverage of the toner particles is uneven and there are many regions where the toner core is exposed over a wide range. It is speculated that this may cause unsatisfactory storage properties and unsatisfactory external additive retention ability. In addition, Japanese Patent Application Laid-Open No. 2017-116712 does not solve the storage stability in a harsh environment where temperature and humidity change rapidly.

[0010] Therefore, as described above, there are still problems in simultaneously achieving low-temperature fixability, storage properties in a harsh environment, and excellent durability during long-term use.

[0011] In view of the above problems, the present disclosure is dedicated to providing a toner that exhibits excellent low-temperature fixability, excellent storage properties in a harsh environment, and excellent durability, and also provides a method for producing the toner.

[0012] The toner of the present disclosure is a toner including toner particles, the toner particles including toner base particles and an outermost layer present on the surface of the toner base particles, the toner base particles including a binder resin, wherein

[0013] a plurality of recesses are formed on the surface of the toner particles, and

[0014] when T (nm) is the average thickness of the outermost layer in the cross-sectional analysis of the toner particles observed by a transmission electron microscope, and

[0015] when measuring the recesses on the toner particles by using a scanning probe microscope from the outermost surface of the outermost layer toward the center of the toner particles, a (nm) is the major axis of each recess, b (nm) is the minor axis of each recess, and d (nm) is the depth of each recess,

[0016] when "n" represents per 1 μm 2When the number of recesses on the surface of the toner particles satisfies the following formulas (1) to (3), "n" satisfies the following formula (4):

[0017] 50.0 ≤ a ≤ 200.0 (1)

[0018] 10.0 ≤ b ≤ 70.0 (2)

[0019] 0.7×T ≤ d ≤ 1.5×T (3)

[0020] 30 ≤ n ≤ 200 (4).

[0021] The method for producing a toner according to the present disclosure is a method for producing a toner including toner particles including toner base particles and an outermost layer covering the surface of the toner base particles, and the toner base particles include a binder resin. The production method includes:

[0022] Attaching particles of a dispersant to the surface of the toner base particles;

[0023] After attaching the particles of the dispersant, forming the outermost layer on the surface of the toner base particles; and

[0024] After forming the outermost layer, removing the particles of the dispersant from the surface of the toner base particles.

[0025] According to the present disclosure, a toner and a method for producing a toner can be provided that exhibit excellent low-temperature fixability, excellent storage stability under harsh environments, and excellent durability.

[0026] With reference to the accompanying drawings, further features of the present invention will become apparent from the following description of exemplary embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Is a time chart of a thermal cycle. DETAILED DESCRIPTION

[0028] Unless otherwise specified, the phrases "from XX to YY" and "XX to YY" indicating a numerical range in the present disclosure refer to a numerical range including the lower limit and the upper limit as endpoints.

[0029] The toner of the present disclosure is a toner including toner particles including toner base particles and an outermost layer present on the surface of the toner base particles, and the toner base particles include a binder resin, wherein

[0030] A plurality of recesses are formed on the surface of the toner particles, and

[0031] When T (nm) is the average thickness of the outermost layer in the cross-sectional analysis of the toner particles observed with a transmission electron microscope, and

[0032] When measuring the recesses on the toner particles from the outermost surface of the outermost layer toward the center of the toner particles using a scanning probe microscope, when a (nm) is the major axis of each recess, b (nm) is the minor axis of each recess, and d (nm) is the depth of each recess,

[0033] When "n" represents the number of recesses per 1 μm 2 on the surface of the toner particles that satisfy the following formulas (1) to (3), "n" satisfies the following formula (4):

[0034] 50.0 ≤ a ≤ 200.0 (1)

[0035] 10.0 ≤ b ≤ 70.0 (2)

[0036] 0.7 × T ≤ d ≤ 1.5 × T (3)

[0037] 30 ≤ n ≤ 200 (4).

[0038] The present inventors conducted research and found that when the outermost layer exists on the toner particles, the area where the toner base particles are exposed on the surface of the toner particles is small, the contact between the toner base particles and the toner base particles between the toner particles is suppressed, and the storage stability under harsh environments is improved. It was also found that the charging characteristics are improved by increasing the area where the outermost layer exists on the surface of the toner particles.

[0039] On the other hand, it was also found that when the area where the outermost layer exists on the surface of the toner particles increases, the low-temperature fixability may be impaired. When the outermost layer exists on the surface of the toner base particles, the thermal stability of the toner particles tends to increase. Thus, when the area where the outermost layer exists on the surface of the toner particles increases, the outermost layer has a large influence on the thermal properties of the toner base particles, and then a decrease in the low-temperature fixability exhibited by the toner base particles may occur.

[0040] When the present inventors conducted in-depth research to overcome this phenomenon, the present inventors found that by providing the outermost layer of the toner base particles with recesses, the structure of the outermost layer and the toner base particles at the surface of the toner particles can be better controlled than before, and the storage stability under harsh environments can coexist with excellent low-temperature fixability and durability.

[0041] The recesses on the surface of the toner particles indicate areas where the toner base particles are exposed or areas where the thickness of the outermost layer is thinned, and it is speculated that they function to reduce the area where the outermost layer exists on the surface of the toner particles. A new effect has also been found: when recesses are formed on the surface of the toner particles, external additives are fixed in the recesses and tend to show stabilized chargeability and fluidity even during long-term use. The present inventors believe that by controlling the size and number of the recesses, it is possible to make the storage property under harsh environments coexist with the suppression of the impairment of low-temperature fixability, and thus achieve the present disclosure.

[0042] More specifically, when T (nm) is the average thickness of the outermost layer in the cross-sectional analysis of the toner particles observed by a transmission electron microscope, and

[0043] when measuring the recesses on the toner particles by using a scanning probe microscope from the outermost surface of the outermost layer toward the center of the toner particles, when a (nm) is the major axis of each recess, b (nm) is the minor axis of each recess, and d (nm) is the depth of each recess,

[0044] when "n" represents the number of recesses on the surface of the toner particles that satisfy the following formulas (1) to (3) per 1 μm 2 "n" satisfies the following formula (4):

[0045] 50.0 ≤ a ≤ 200.0 (1)

[0046] 10.0 ≤ b ≤ 70.0 (2)

[0047] 0.7 × T ≤ d ≤ 1.5 × T (3)

[0048] 30 ≤ n ≤ 200 (4).

[0049] When "n" represents the number of recesses on the surface of the toner particles that satisfy the following formulas (1) to (3) per 1 μm 2 "n" is 30 to 200.

[0050] When the number "n" of the recesses is less than 30, low-temperature fixability is not obtained and storage property under harsh environments is not obtained. In addition, when the number "n" of the recesses is greater than 200, storage property under harsh environments is not obtained. From the viewpoints of low-temperature fixability, durability, and storage property under harsh environments, the number "n" of the recesses is preferably 60 to 180 and more preferably 100 to 150.

[0051] The number "n" of the recesses can be controlled by the concentration of the dispersant particles attached to the toner base particles during the formation of the outermost layer and by the heating temperature during the formation of the outermost layer. Specifically, the number "n" of the recesses increases as the concentration of the dispersant particles increases and increases as the heating temperature during the formation of the outermost layer rises.

[0052] Provided by measuring the recesses in the toner particle surface using a scanning probe microscope (hereinafter also referred to as SPM), the major axis "a" of the recesses is preferably from 50.0 nm to 200.0 nm and more preferably from 80.0 nm to 170.0 nm. The minor axis "b" of the recesses provided by the same measurement is preferably from 10.0 nm to 70.0 nm and more preferably from 20.0 nm to 45.0 nm.

[0053] When the major axis "a" of the recesses is 50.0 nm or more, the low-temperature fixability tends to be more improved. When the minor axis "b" of the recesses is 10.0 nm or more, the low-temperature fixability also tends to be more improved.

[0054] On the other hand, when the major axis "a" of the recesses is 200.0 nm or less, the storage stability under harsh environments tends to be more improved. When the minor axis "b" of the recesses is 70.0 nm or less, the storage stability under harsh environments also tends to be more improved.

[0055] The major axis "a" of the recesses and the minor axis "b" of the recesses can be controlled by the major axis and the minor axis of the dispersant particles attached to the toner base particles when forming the outermost layer, and the major axis and the minor axis of these dispersant particles can be controlled by, for example, the reaction temperature and the shear conditions during the production of the dispersant particles. Specifically, during the production of the dispersant particles, the higher the reaction temperature and the stronger the shear conditions tend to provide a smaller major axis "a" and a smaller minor axis "b" of the recesses.

[0056] The following formula is preferably satisfied by the average thickness "T" of the outermost layer in the toner cross-section analysis observed by a transmission electron microscope (hereinafter also denoted by TEM), and the depth "d" of the recesses obtained by measuring the recesses on the toner particle surface from the outermost surface of the outermost layer toward the center of the toner particle using a scanning probe microscope.

[0057] 0.7×T ≤ d ≤ 1.5×T

[0058] The "d" is more preferably from 0.8×T (nm) to 1.1×T (nm).

[0059] When "d" is 0.7×T or more, the area of the toner base particles appearing in the recesses is large, and as a result, the low-temperature fixability tends to be more improved. On the other hand, when "d" is 1.5×T or less, the recesses are not too deep, and as a result, the occurrence of surface strain in the outermost layer and the occurrence of embedding of external additives are suppressed and the durability tends to be more improved.

[0060] The depth d of the recess can be controlled, for example, by the concentration of the dispersant particles attached to the toner base particles when forming the outermost layer and by the addition amount of the material for forming the outermost layer. Specifically, the depth d of the recess tends to increase as the concentration of the dispersant particles increases and as the addition amount of the material for forming the outermost layer increases.

[0061] When "N" represents the number of recesses (hereinafter, such recesses are also particularly referred to as large recesses) satisfying both of the following formulas (5) and (6) on the surface of the toner particles per 1 μm 2 "N" is 10 or less. This N is more preferably 5 or less. In addition, the number "N" of the large recesses is preferably 0 or more. Any combination of these numerical ranges can be used.

[0062] 250.0 < a (5)

[0063] 100.0 < b (6)

[0064] When per 1 μm 2 When the number "N" of the large recesses having a major axis a greater than 250.0 nm and a minor axis b greater than 100.0 nm on the surface of the toner particles is 10 or less, the contact between the toner base particles in a harsh environment is suppressed, and the storage property in a harsh environment tends to be more improved.

[0065] The number "N" of the large recesses having a major axis a greater than 250.0 nm and a minor axis b greater than 100.0 nm can be adjusted, for example, by the concentration of the dispersant particles attached to the toner base particles during the formation of the outermost layer. Specifically, as the concentration of the dispersant particles decreases, the number "N" of the large recesses having a major axis a greater than 250.0 nm and a minor axis b greater than 100.0 nm tends to decrease.

[0066] The average thickness T (nm) of the outermost layer is preferably 5.0 nm to 100.0 nm.

[0067] When the average thickness T (nm) of the outermost layer is 5.0 nm or more, the durability and the storage property in a harsh environment tend to be more improved. On the other hand, when the average thickness T (nm) of the outermost layer is 100.0 nm or less, the low-temperature fixability tends to be more improved.

[0068] The average thickness T (nm) of the outermost layer can be controlled, for example, by the addition amount of the material for forming the outermost layer. Specifically, the average thickness T (nm) of the outermost layer tends to increase as the addition amount of the material for forming the outermost layer increases.

[0069] From the viewpoint of achieving coexistence among low-temperature fixability, durability, and storage stability under harsh environments, the average thickness T (nm) of the outermost layer is more preferably from 10.0 nm to 60.0 nm.

[0070] <Outermost layer>: The outermost layer preferably contains a thermoplastic resin. The content of the thermoplastic resin in the outermost layer can be, for example, from 50% by mass to 100% by mass.

[0071] Examples of the thermoplastic resin include the following resins: styrene resins, acrylic resins (e.g., acrylate polymers and methacrylate polymers), olefin resins (e.g., polyethylene resins and polypropylene resins), vinyl chloride resins, polyvinyl alcohol, vinyl ether resins, N-vinyl resins, polyester resins, polyamide resins, and polyurethane resins.

[0072] Copolymers of these resins can also be used, that is, copolymers provided by introducing freely selected repeating units into the above resins (e.g., styrene-acrylic resins and styrene-butadiene resins).

[0073] The thermoplastic resin preferably includes a styrene-acrylic resin. A copolymer of one or more styrene monomers and one or more (meth)acrylic monomers is also a preferred embodiment of the styrene-acrylic resin.

[0074] For example, the following styrene monomers and (meth)acrylic monomers can be advantageously used to synthesize the styrene-acrylic resin.

[0075] Advantageous examples of the styrene monomer are styrene, alkylstyrenes (e.g., α-methylstyrene, p-ethylstyrene, and 4-tert-butylstyrene), p-hydroxystyrene, m-hydroxystyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, and p-chlorostyrene.

[0076] Advantageous examples of the (meth)acrylic monomer are (meth)acrylic acid, (meth)acrylonitrile, (meth)acrylic acid alkyl esters, and (meth)acrylic acid hydroxyalkyl esters.

[0077] Advantageous examples of the (meth)acrylic acid alkyl ester are methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isobutyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0078] Advantageous examples of the (meth)acrylic acid hydroxyalkyl ester are 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0079] In another preferred embodiment, the outermost layer comprises a thermosetting resin. The content of the thermosetting resin in the outermost layer is, for example, 50% by mass to 100% by mass.

[0080] Preferable examples of the thermosetting resin are melamine resins, urea-formaldehyde resins, and glyoxal resins.

[0081] The thermosetting resin preferably comprises a melamine resin. The melamine resin is, for example, a condensate of melamine and formaldehyde, and the monomers used to form the melamine resin are, for example, melamine.

[0082] <Binder resin>: The binder resin preferably comprises a styrene-acrylic resin (more preferably a styrene-alkyl acrylate resin). The content of the styrene-acrylic resin in the binder resin can be, for example, 50% by mass to 100% by mass.

[0083] The same monomers as the above-mentioned styrene monomers and (meth)acrylic acid monomers used for synthesizing the thermoplastic resin in the outermost layer can be suitably used as the monomers for synthesizing the styrene-acrylic resin.

[0084] In another preferred embodiment, the binder resin comprises a polyester resin. The content of the polyester resin in the binder resin can be, for example, 1% by mass to 10% by mass or 50% by mass to 100% by mass.

[0085] The polyester resin can be obtained by polycondensation or co-polycondensation of a hitherto known dibasic or tribasic or higher carboxylic acid component and a dibasic or tribasic or higher alcohol component.

[0086] For example, derivatives of esters (e.g., acyl halides, acid anhydrides, and lower alkyl esters) can be used as the dibasic or tribasic or higher carboxylic acid component. The lower alkyl here means an alkyl having 1 to 6 carbon atoms.

[0087] For example, the following can be used as the dibasic carboxylic acid component: dibasic acids such as succinic acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, malonic acid, and dodecenylsuccinic acid and their acid anhydrides and lower alkyl esters, and aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid.

[0088] For example, 1,2,4-benzenetricarboxylic acid and 1,2,5-benzenetricarboxylic acid and their lower alkyl esters can be used as the tribasic or higher carboxylic acid component.

[0089] These carboxylic acid components can be used alone, or two or more of these can be used in combination.

[0090] Preferable examples of the dibasic or tribasic or higher alcohol component are diols, bisphenols, and tribasic or higher alcohols.

[0091] The diol component can be exemplified by the following compounds: alkylene diols (ethylene glycol, 1,2 - propylene glycol, and 1,3 - propylene glycol), alkylene ether diols (polyethylene glycol and polypropylene glycol), alicyclic diols (1,4 - cyclohexanedimethanol), bisphenols (bisphenol A), and alkylene oxide (ethylene oxide or propylene oxide) adducts of alicyclic diols.

[0092] The alkyl moieties of the alkylene diols and alkylene ether diols can be straight - chain or branched. It is also preferable to use alkylene diols having a branched structure.

[0093] The polyhydric alcohol component having three or more hydroxyl groups can be exemplified by the following compounds: glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0094] These alcohol components can be used individually or two or more of them can be used in combination.

[0095] For the purpose of adjusting the acid value or hydroxyl value, monobasic acids such as acetic acid or benzoic acid and monohydric alcohols such as cyclohexanol or benzyl alcohol can also be used as needed.

[0096] There is no particular limitation on the method for synthesizing the polyester resin. For example, the transesterification method or the direct polycondensation method can be used as such or in combination.

[0097] <Wax>: The toner base particles can contain wax.

[0098] Known waxes can be used as the wax.

[0099] Specific examples are as follows: petroleum waxes represented by paraffin wax, microcrystalline wax, and petrolatum, and their derivatives; montan wax and its derivatives; hydrocarbon waxes provided by the Fischer - Tropsch method, and their derivatives; polyolefin waxes represented by polyethylene, and their derivatives; and natural waxes represented by carnauba wax and candelilla wax, and their derivatives. These derivatives also include oxides and block copolymers and graft - modified products with vinyl monomers.

[0100] Alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid, and their amides, esters, and ketones, hydrogenated castor oil and its derivatives, vegetable waxes, and animal waxes can also be used.

[0101] These waxes can be used individually or two or more of them can be used in combination.

[0102] Among the above, when using polyolefins, hydrocarbon waxes provided by the Fischer - Tropsch method, or petroleum waxes, there is a tendency to show enhanced developability and transferability, and thus these are preferred.

[0103] Antioxidants can be added to these waxes within the range that does not affect the effects of the toner according to the present disclosure.

[0104] The content of wax is preferably 1.0 to 30.0 parts by mass relative to 100.0 parts by mass of the binder resin. The melting point of the wax is preferably 30°C to 120°C, and more preferably 60°C to 100°C.

[0105] The wax preferably contains an ester compound.

[0106] Examples of the ester compound include esters between a monohydric alcohol and an aliphatic carboxylic acid or esters between a monocarboxylic acid and an aliphatic alcohol, such as behenyl behenate, stearyl stearate, and palmitin; esters between a dihydric alcohol and an aliphatic carboxylic acid and esters between a dicarboxylic acid and an aliphatic alcohol, such as ethylene glycol distearate, behenic acid dodecyl ester, and hexanediol dibehenate; esters between a trihydric alcohol and an aliphatic carboxylic acid and esters between a tricarboxylic acid and an aliphatic alcohol, such as glyceryl tribehenate; esters between a tetrahydric alcohol and an aliphatic carboxylic acid and esters between a tetracarboxylic acid and an aliphatic alcohol, such as pentaerythritol tetrastearate and pentaerythritol tetrapalmitate; esters between a hexahydric alcohol and an aliphatic carboxylic acid and esters between a hexacarboxylic acid and an aliphatic alcohol, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate; and esters between a polyhydric alcohol and an aliphatic carboxylic acid and esters between a polycarboxylic acid and an aliphatic alcohol, such as polyglyceryl behenate.

[0107] Due to the plasticizing effect on the toner particles caused by using these ester compounds, the low-temperature fixability is further improved. Among the above, from the viewpoint of the balance between durability and low-temperature fixability, the wax more preferably contains an ester compound represented by Formula (7) or Formula (8).

[0108]

[0109] In Formulas (7) and (8), R 1 represents an alkylene group having 1 to 6 carbons (preferably 2 to 6 and more preferably 2 to 4), and R 2 and R 3 each independently represent an alkyl group having 11 to 26 carbons (preferably 11 to 25 and more preferably 16 to 22). The alkyl group may be a straight-chain alkyl group or a branched alkyl group, but a straight-chain alkyl group is preferred.

[0110] Among the ester compounds represented by Formulas (7) and (8), ethylene glycol distearate in which R 1 is a C2 alkylene group and R 2 and R 3 are C 17 straight-chain alkyl groups is more preferred.

[0111] The content of the wax ester compound is preferably from 50% by mass to 100% by mass, and more preferably from 70% by mass to 100% by mass. When the content of the wax ester compound is within the above range, it is easier to achieve the coexistence between durability and low-temperature fixability.

[0112] <Colorant>: The toner base particles may contain a colorant. Known pigments and dyes can be used as the colorant. From the viewpoint of providing excellent weather resistance, pigments are preferably used as the colorant.

[0113] Examples of cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds.

[0114] Specific examples are as follows: C.I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0115] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

[0116] Specific examples are as follows: C.I. 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 C.I. Pigment Violet 19.

[0117] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methylene compounds, and allylamide compounds.

[0118] Specific examples are as follows: C.I. 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.

[0119] Examples of black colorants include carbon black and black colorants provided by mixing the colors of the above yellow colorants, magenta colorants, and cyan colorants to give black.

[0120] These colorants can be used individually or a mixture of two or more of these can be used. These can also be used in the form of a solid solution.

[0121] The content of the colorant is preferably 1.0 to 20.0 parts by mass relative to 100.0 parts by mass of the binder resin.

[0122] <Charge control agent and charge control resin>: The toner base particles may contain at least one selected from the group consisting of a charge control agent and a charge control resin.

[0123] Known charge control agents can be used as the charge control agent, and a charge control agent that provides a fast triboelectric charging speed and can maintain a definite and stable triboelectric charge amount is particularly preferred. When producing toner particles by suspension polymerization, a charge control agent that exhibits low polymerization inhibition and is substantially free of materials soluble in the aqueous medium is particularly preferred.

[0124] Charge control agents include charge control agents that control the toner to be negatively charged and charge control agents that control the toner to be positively charged.

[0125] Examples of the charge control agent that controls the toner to be negatively charged include monoazo metal compounds; acetylacetone-metal compounds; metal compounds of aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, hydroxycarboxylic acids, and dicarboxylic acids; aromatic hydroxycarboxylic acids, aromatic monocarboxylic acids, and aromatic polycarboxylic acids and their metal salts, acid anhydrides, and 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 control resins.

[0126] Examples of the charge control agent that controls the toner to be positively charged include the following: guanidine compounds; imidazole compounds; quaternary ammonium salts such as 1-hydroxy-4-naphthalenesulfonic acid tributylbenzylammonium salt and tetrabutylammonium tetrafluoroborate, and their analogs such as phosphonium salts, and their lake pigments; triphenylmethane dyes and their lake pigments (examples of the lake agent include phosphotungstic acid, phosphomolybdic acid, phosphomolybdotungstic acid, tannic acid, lauric acid, gallic acid, ferricyanide, and ferrocyanide); metal salts of higher fatty acids; and charge control resins.

[0127] Among these charge control agents, metal-containing salicylic acid compounds are preferred, and metal-containing salicylic acid compounds in which the metal is aluminum or zirconium are particularly preferred.

[0128] Examples of the charge control resin include polymers and copolymers having a sulfonic acid group, a sulfonate group, or a sulfonate ester group. Particularly preferred polymers having a sulfonic acid group, a sulfonate group, or a sulfonate ester group are polymers containing 2% by mass or more of a sulfonic acid group-containing acrylamide monomer or a sulfonic acid group-containing methacrylamide monomer in the copolymerization ratio, and more preferably polymers containing 5% by mass or more of the above monomers.

[0129] The glass transition temperature (Tg) of the charge control resin is preferably from 35°C to 90°C, the peak molecular weight (Mp) is preferably from 10,000 to 30,000, and the weight average molecular weight (Mw) is preferably from 25,000 to 50,000. When it is used, preferable triboelectric charging characteristics can be imparted without exerting an influence on the thermal characteristics required for toner particles. Further, since the charge control resin contains a sulfonic acid group, for example, in a polymerizable monomer composition, the dispersibility of the charge control resin itself and the dispersibility of, for example, a colorant and the like are improved, and thus the coloring strength, transparency, and triboelectric charging characteristics can be further improved.

[0130] These charge control agents or a single one of the charge control resins can be used alone, or two or more of these can be used in combination.

[0131] The content of the charge control agent or the charge control resin is preferably from 0.01 parts by mass to 20.0 parts by mass and more preferably from 0.5 parts by mass to 10.0 parts by mass with respect to 100.0 parts by mass of the binder resin.

[0132] <Inorganic particles such as silica used as an external additive>: The toner particles can be used as a toner as they are, but are usually used as a toner after optionally being mixed with, for example, an external additive or the like and attached to the surface.

[0133] On the toner surface, the presence of silica particles having a number average particle diameter (D1) of the primary particles of 40.0 nm or more (preferably 80.0 nm or more) is preferable. The D1 can be, for example, 200 nm or less. Any combination of these numerical ranges can be used.

[0134] The content of the silica particles having a D1 of the primary particles of 40.0 nm or more is preferably from 0.1 parts by mass to 4.0 parts by mass and more preferably from 0.2 parts by mass to 3.5 parts by mass with respect to 100 parts by mass of the toner particles.

[0135] The fluidity and chargeability can be improved by adding silica particles as an external additive to the toner particles. Further, by making the primary particle diameter of the external additive 40.0 nm or more, the inorganic particles are fixed in the recesses in the outermost layer, and stabilization of the chargeability and fluidity is obtained even during long-term use.

[0136] Inorganic particles other than the above-described silica particles can be present on the toner surface. Such inorganic particles can be exemplified by titanium oxide particles, aluminum oxide particles, silica particles having a primary particle diameter of less than 40.0 nm, and the aforementioned composite oxide particles.

[0137] Silica particles can be exemplified by dry silica and fumed silica produced by the gas-phase oxidation of silicon halides, and wet silica produced from water glass. Dry silica is preferred because dry silica contains almost no silanol groups on the surface and inside of the silica particles and contains almost no Na2O and SO3. 2- . Dry silica can be composite fine particles of silica and other metal oxides produced by being used in combination with metal halide compounds such as aluminum chloride or titanium chloride, for example, in the production process of silicon halide compounds.

[0138] From the viewpoints of the charge amount on the toner, environmental stability, properties in a high-humidity environment, developability, transferability, and the like, it is more preferable to use hydrophobized silica particles (also referred to as hydrophobic silica) as the silica particles.

[0139] Examples of the treating agent for the hydrophobization treatment of silica particles can be unmodified silicone varnishes, various modified silicone varnishes, unmodified silicone oils, various modified silicone oils, silane compounds, silane coupling agents, other silicone compounds, and organotitanium compounds. These treating agents can be used alone, or two or more of these can be used in combination.

[0140] Among the above, silica particles treated with silicone oil are preferred. From the viewpoints of maintaining a high charge amount on the toner particles even in a high-humidity environment and reducing selective development, hydrophobic silica provided by hydrophobizing silica particles with a silane coupling agent and then treating with silicone oil simultaneously or after the treatment is more preferred.

[0141] The BET retention rate of the toner measured by the method described later is preferably 65% to 100% and more preferably 67% to 100%.

[0142] When the BET retention rate of the toner is in the range of 65% to 100%, the durability during long-term use tends to be more improved. The low-temperature fixability and the storage property under harsh environments can also be further improved.

[0143] The BET retention rate of the toner can be controlled by, for example, adding inorganic particles having a D1 of 40.0 nm or more for the primary particles and by the attachment conditions (temperature, time) of the external additive.

[0144] The production method of the toner includes the following steps.

[0145] (a) Attaching particles of a dispersant to the surface of toner base particles.

[0146] (b) After attaching the particles of the dispersant, forming an outermost layer on the surface of the toner base particles.

[0147] (c) After forming the outermost layer, the particles of the dispersant are removed from the surface of the toner base particles.

[0148] The production method according to the present disclosure will be described in detail below.

[0149] According to the operations in (a) to (c), the dispersant particles adhere to the surface of the toner base particles, the material for forming the outermost layer is added to the dispersion liquid containing the toner base particles, and the outermost layer is formed on the surface of the toner base particles. From the viewpoint of preventing the components contained in the toner base particles from dissolving into the medium, the medium used during the formation of the outermost layer is preferably an aqueous medium.

[0150] In step (a), the dispersant particles are adhered to the surface of the toner base particles. The following are examples of methods for adhering the dispersant particles to the surface of the toner base particles: after mechanically dispersing the toner base particles in an aqueous medium using a device with strong stirring ability, the dispersant is added; the toner base particles are added to the aqueous medium containing the dispersant. Among them, it is preferable to add the toner base particles to the aqueous medium containing the dispersant because this enables the toner base particles to be uniformly dispersed in the aqueous medium with less power.

[0151] For example, a polymer dispersant, a surfactant, resin particles, or inorganic particles can be used as the dispersant without particular limitation. Among them, from the viewpoints of preventing surface modification of the surface of the toner base particles and causing the toner base particles to be highly dispersed in the medium (especially an aqueous medium), it is preferable to use inorganic particles. Particles of an inorganic compound such as sodium phosphate or calcium chloride can be used as the inorganic particles.

[0152] The number average particle diameter of the dispersant particles is preferably from 30 nm to 350 nm and more preferably from 50 nm to 200 nm. The amount of the dispersant particles used is preferably from 0.3 parts by mass to 30 parts by mass and more preferably from 0.5 parts by mass to 10.0 parts by mass relative to 100 parts by mass of the toner base particles.

[0153] Due to the uniform dispersion of the dispersant particles in the aqueous medium containing the dispersant particles, the dispersant particles can be adhered to the surface of the toner base particles by introducing the toner base particles and mechanically mixing them with a stirring device.

[0154] When the toner base particles are produced by suspension polymerization, an aqueous dispersion liquid of the toner base particles with the dispersant particles adhered to the surface is produced during the production process, and as a result, the aqueous dispersion liquid of the toner base particles can also be used as it is as the toner base particle dispersion liquid. That is, in the production step of the toner base particles, a step of adhering the dispersant particles to the surface of the toner base particles can be included.

[0155] In step (b), an outermost layer is formed on the surface of the toner base particles. For example, the outermost layer can be formed on the surface of the toner base particles by adding the material of the outermost layer to the dispersion of the toner base particles.

[0156] For example, the above-mentioned thermoplastic resin and the above-mentioned thermosetting resin can be used as the material of the outermost layer. When the thermoplastic resin is used as the material of the outermost layer, the outermost layer can be formed, for example, by mixing the dispersion of the thermoplastic resin with the toner base particles to attach the thermoplastic resin to the surface of the toner base particles in the aqueous dispersion and then heating. When the thermosetting resin is used as the material of the outermost layer, the outermost layer can be formed by mixing the monomers constituting the thermosetting resin with the toner base particles and carrying out the reaction at the surface of the toner base particles in the aqueous medium by heating.

[0157] The outermost layer covers the area to which the dispersant particles attached in step (a) are attached and is formed in a film shape on all or part of the surface of the toner base particles.

[0158] The temperature during the formation of the outermost layer is preferably 40°C to 90°C and more preferably 50°C to 80°C. By carrying out the formation of the outermost layer within this temperature range, the formation of the outermost layer proceeds well.

[0159] In step (c), after the outermost layer is formed, the dispersant particles are removed from the surface of the toner base particles. When the dispersant particles are inorganic particles, for example, the removal from the surface of the toner base particles can be carried out by dissolving the inorganic particles using an acid and then filtering. The removal of the dispersant particles enables the shape of the dispersant particles to be formed into a concave shape in the outermost layer.

[0160] Subsequently, dispersion in water and filtration are repeated as needed to obtain toner particles having concave portions on the surface.

[0161] The measurement methods for the values of the respective physical properties are described below.

[0162] <Measurement method for the major axis of each concave portion, the minor axis of each concave portion, the depth of each concave portion, and the number of concave portions on the toner particle surface>

[0163] The concave portions on the surface of the toner particles are observed using a scanning probe microscope (SPM) and the following method.

[0164] SI-DF20 (Al-coated back) from Seiko Instruments Inc. is used for the measurement of the cantilever and is operated in the dynamic force mode. After pre-measuring the detection accuracy in the depth direction using a pattern sample (100 nm ± 5 nm) for precision detection, the SPM is used.

[0165] First, a conductive double-sided tape is pasted onto the sample stage, and toner particles are sprayed thereon. The excess toner particles are removed from the sample stage by blowing air. Using this sample, the surface of the toner particles is magnified to 1 μm × 1 μm using an SPM (trade name: E-sweep, Hitachi High-Tech Science Corporation), and the recesses in the outermost layer are observed.

[0166] After measurement, the obtained 1 μm × 1 μm measurement data is subjected to tilt correction and then the average surface roughness is calculated. The average surface roughness refers to the arithmetic mean of the recess depths in a 1 μm × 1 μm measurement from the outermost surface of the outermost layer towards the center of the toner particle, and is designated as the depth d1 (nm) of the recess in the outermost layer in the present disclosure. By this method, for 50 toner particles, the depths d1 to d of the recesses are measured. 50 and the arithmetic mean of d1 to d 50 is taken as the depth d (nm) of the recess.

[0167] The number "n" of recesses and the number "N" of large recesses that satisfy formulas (1) to (3) are measured as follows. The tilt-corrected measurement data provided by the above measurement is output; the major axis a (nm) of the recess, the minor axis b (nm) of the recess, and the depth d (nm) of the recess in a 1 μm × 1 μm are viewed; and the number "n1" of recesses and the number "N1" of large recesses that satisfy formulas (1) to (3) on the surface of each 1 μm × 1 μm toner particle are counted in each case. By this method, for 50 toner particles, the numbers n1 to n of recesses that satisfy formulas (1) to (3) are counted. 50 and the numbers N1 to N of large recesses 50 and their arithmetic means are respectively designated as the number "n" of recesses and the number "N" of large recesses.

[0168] The major axis a and the minor axis b of the recess are measured as follows. The tilt-corrected measurement data provided by the above measurement is output; the arithmetic means of the major axis and the minor axis of the recess on the surface of each 1 μm × 1 μm toner particle are measured and are respectively designated as the major axis a1 and the minor axis b1 of the recess. By this method, for 50 toner particles, the major axes a1 to a of the recesses are measured. 50 and the minor axes b1 to b of the recesses 50 and their arithmetic means are respectively designated as the major axis a and the minor axis b of the recess.

[0169] <Method for obtaining toner particles by removing external additives from toner>

[0170] When measuring the recesses on the surface of a toner with an external additive attached to the surface, the following operation is used to remove the external additive and measure the recesses on the resulting toner particles by the above method.

[0171] A 61.5% sucrose aqueous solution was prepared by adding 160 g of sucrose (Kishida Chemical Co., Ltd.) to 100 mL of deionized water and dissolving it while heating in a water bath. 31.0 g of this sucrose concentrate and 6 g of Contaminon N (trade name) (a 10% aqueous solution of a neutral pH 7 detergent for cleaning precision measuring instruments, which includes a nonionic surfactant, an anionic surfactant, and an organic builder, Wako Pure Chemical Industries, Ltd.) were introduced into a centrifuge tube to prepare a dispersion. 1.0 g of toner was added to this dispersion, and the agglomerates of the toner were broken up using, for example, a spatula.

[0172] The centrifuge tube was shaken with a shaker at 350 strokes per minute (spm) for 20 minutes. After shaking, the solution was transferred to a glass tube (50 mL) for a swinging rotor, and separation was carried out using a centrifuge under the conditions of 3,500 rpm and 30 minutes.

[0173] The satisfactory separation of the toner particles from the aqueous solution was visually inspected, and the toner particles separated into the uppermost layer were recovered using, for example, a spatula. The recovered toner particles were filtered using a vacuum filter, and then dried in a dryer for 1 hour or more. The dried product was broken up with a spatula to obtain toner particles.

[0174] <Method for measuring the average thickness T of the outermost layer>

[0175] Using a transmission electron microscope (TEM), the cross-section of the toner particles was observed using the following method.

[0176] First, the toner particles were sufficiently dispersed in a room temperature curable epoxy resin, and then cured in an atmosphere at 40 °C for 2 days. A thin sample with a thickness of 50 nm was cut out from the resulting cured material using a microtome equipped with a diamond blade, and ruthenium staining was carried out using a vacuum staining device (Filgen, Inc.). Then, the resulting sample was magnified 100,000 times using a TEM (trade name: Tecnai TF20XT electron microscope, FEI Company). The thickness (unit: nm) of the outermost layer was measured at four randomly selected positions on a single toner particle.

[0177] The cross-section was inspected on 50 toner particles using this method, and the arithmetic mean of a total of 200 positions was used as the average thickness T (nm).

[0178] <Method for Measuring Weight-Average Particle Diameter (D4) and Number-Average Particle Diameter (D1)>

[0179] The weight-average particle diameter (D4) and number-average particle diameter (D1) of the toner, toner particles, and toner base particles (hereinafter also referred to as, for example, toner) are determined as follows.

[0180] The measuring instrument used is a precision particle size distribution measuring instrument "Coulter Counter Multisizer 3" (registered trademark, Beckman Coulter, Inc.) that operates based on the pore resistance method and is equipped with a 100 μm aperture tube.

[0181] Using the attached dedicated software, namely, "Beckman Coulter Multisizer 3 Version 3.51" (Beckman Coulter, Inc.), the measurement conditions are set and the measurement data is analyzed. The measurement is performed in 25,000 effective measurement channels.

[0182] The electrolyte aqueous solution for measurement is prepared by dissolving special grade sodium chloride in deionized water to provide a concentration of 1.0%, and for example, "ISOTON II" (Beckman Coulter, Inc.) can be used.

[0183] Before measurement and analysis, the dedicated software is set as follows.

[0184] In the "Change Standard Operating Method (SOMME)" interface in the dedicated software, the total count in the control mode is set to 50,000 particles; the number of measurements is set to 1 time; and the Kd value is set to the value obtained using "Standard Particle 10.0 μm" (Beckman Coulter, Inc.). The threshold and noise level are automatically set by pressing the "Threshold / Noise Level Measurement Button". Additionally, the current is set to 1,600 μA; the gain is set to 2; the electrolyte solution is set to ISOTON II; and "Post-measurement aperture tube rinse" is input.

[0185] In the "Pulse-to-Particle Size Conversion Setting" interface in the dedicated software, the element interval is set to logarithmic particle size; the particle size element is set to 256 particle size elements; and the particle size range is set to 2 μm to 60 μm.

[0186] The specific measurement steps are as follows.

[0187] (1) Introduce 200.0 mL of an aqueous electrolyte solution into a 250-mL round-bottom glass beaker dedicated to the Multisizer 3, place it on the sample stage, and stir counterclockwise with a stir bar at 24 revolutions per second. Initially remove dirt and air bubbles inside the mouthpiece tube through the "mouthpiece tube rinsing" function of the dedicated software.

[0188] (2) Introduce 30.0 mL of the aqueous electrolyte solution into a 100-mL flat-bottom glass beaker. Add 0.3 mL of a dilution prepared by diluting "Contaminon N" (a 10% aqueous solution of a neutral pH 7 detergent for cleaning precision measuring instruments, including nonionic surfactant, anionic surfactant, and organic co-builders, from Wako Pure Chemical Industries, Ltd.) three times (by mass) with deionized water as a dispersant.

[0189] (3) Prepare an "Ultrasonic Dispersion System Tetora 150" (Nikkaki Bios Co., Ltd.); it is an ultrasonic disperser with an electrical output of 120 W and equipped with two oscillators (oscillation frequency = 50 kHz) set to have a 180° phase shift. Introduce 3.3 L of deionized water into the water tank of the ultrasonic disperser, and add 2.0 mL of Contaminon N to this water tank.

[0190] (4) Set the beaker described in (2) in the beaker holding hole on the ultrasonic disperser, and start the ultrasonic disperser. Adjust the vertical position of the beaker in such a way that the resonance state of the liquid level of the aqueous electrolyte solution in the beaker is maximized.

[0191] (5) While irradiating the aqueous electrolyte solution in the beaker placed according to (4) with ultrasonic waves, add 10 mg of, for example, toner in small equal portions to the aqueous electrolyte solution and disperse it. Continue the ultrasonic dispersion treatment for another 60 seconds. During the ultrasonic dispersion, appropriately control the water temperature in the water tank to 10 °C to 40 °C.

[0192] (6) Using a pipette, drip the aqueous electrolyte solution prepared in (5) and containing, for example, dispersed toner into the round-bottom beaker set on the sample stage in (1) above, and adjust to provide a measurement concentration of 5%. Then, perform the measurement until the number of measured particles reaches 50,000.

[0193] (7) Analyze the measurement data through the dedicated software set in the instrument, and calculate the weight-average particle diameter (D4) and the number-average particle diameter (D1). When the dedicated software is set to Chart / Volume%, the "Average Diameter" on the "Analysis / Volume Statistical Value (Arithmetic Mean)" interface is the weight-average particle diameter (D4). When the dedicated software is set to Chart / Number%, the "Average Diameter" on the "Analysis / Number Statistical Value (Arithmetic Mean)" interface is the number-average particle diameter (D1).

[0194] <Method for Measuring the Volume-Average Diameter of Particles in a Thermoplastic Resin Dispersion>

[0195] The volume-average diameter of particles in a thermoplastic resin dispersion is measured using a Zetasizer Nano-ZS (Malvern Instruments Ltd.).

[0196] First, prepare a measurement sample by diluting the thermoplastic resin dispersion to be measured with water to a solid-liquid ratio of 0.10 mass% (±0.02 mass%), and introduce it into a quartz cell installed in the measurement section. For the measurement conditions, input the refractive index of the thermoplastic resin, the refractive index and viscosity of the dispersion medium, and perform the measurement in the range of 0.3 nm to 10.0 μm.

[0197] <Method for Measuring the Glass Transition Temperature (Tg)>

[0198] For example, the glass transition temperature (Tg) of toner base particles or the outermost layer material is measured using a "Q1000" differential scanning calorimeter (TA Instruments) according to ASTM D 3418-82.

[0199] Use the melting points of indium and zinc for temperature calibration of the instrument detection section, and use the heat of fusion of indium for heat calibration.

[0200] Specifically, accurately weigh out 10 mg of the measurement sample and introduce it into an aluminum pan; use an empty aluminum pan for reference. Perform the measurement at a heating rate of 10 °C / min in the temperature range of 30 °C to 200 °C.

[0201] During the measurement, heat to 200 °C, then cool to 30 °C at a cooling rate of 10 °C / min, and then heat again.

[0202] During this second heating process, obtain the specific heat change in the temperature range of 40 °C to 100 °C. Take the glass transition temperature (Tg) as the intersection point between the differential thermal curve and the line connecting the midpoints of the baselines before and after the appearance of the specific heat change.

[0203] <Measurement of the BET Specific Surface Area of Toner>

[0204] The BET specific surface area of the toner is measured according to JIS Z 8830 (2001). The specific measurement steps are as follows.

[0205] Use the "TriStar 3000 (Shimadzu Corporation) automatic specific surface area / pore size distribution analyzer", which uses the constant volume gas adsorption method as its measurement principle, as the measurement instrument. Use the dedicated software "TriStar 3000 Version 4.00" attached to this instrument to set the measurement conditions and analyze the measurement data. Connect the vacuum pump, nitrogen pipeline, and helium pipeline to the instrument. The value calculated by the BET multi-point method using nitrogen as the adsorption gas is used as the BET specific surface area in this disclosure.

[0206] The BET specific surface area is determined as follows.

[0207] First, adsorb nitrogen on the sample (toner) and measure the equilibrium pressure P (Pa) in the sample chamber and the nitrogen adsorption amount Va (mol·g -1 ) of the sample at this time. The adsorption isotherm uses the relative pressure Pr as the horizontal axis and the nitrogen adsorption amount Va (mol·g -1 ) as the vertical axis to obtain, and the relative pressure Pr is the value provided by dividing the equilibrium pressure P (Pa) in the sample chamber by the saturated vapor pressure Po (Pa) of nitrogen. Then use the BET formula provided below to obtain the monolayer adsorption amount Vm (mol·g -1 ), which is the adsorption amount required to form a monolayer on the surface of the sample.

[0208] Pr / Va(1 - Pr) = 1 / (Vm×C) + (C - 1)×Pr / (Vm×C)

[0209] Here, C is the BET parameter and is a variable that changes with the type of the measured sample, the type of the adsorption gas, and the adsorption temperature.

[0210] The BET formula can be presented as a straight line with a slope of (C - 1) / (Vm×C) and an intercept of 1 / (Vm×C) by using Pr as the X-axis and Pr / Va(1 - Pr) as the Y-axis. This straight line is called the BET plot.

[0211] Slope of the straight line = (C - 1) / (Vm×C)

[0212] Intercept of the straight line = 1 / (Vm×C)

[0213] The value of the slope of this straight line and the value of its intercept can be calculated by plotting the measured values of Pr and Pr / Va(1 - Pr) on a graph and generating a straight line by the least squares method. Using these values, Vm and C can be calculated by solving the simultaneous equations of the above slope and intercept.

[0214] Then, using the following formula, the Vm calculated as above, and the molecular cross-sectional area of nitrogen molecules (0.162 nm 2 ) to calculate the BET specific surface area S (m 2 ·g -1 ) of the sample.

[0215] S = Vm × N × 0.162 × 10 -18

[0216] Here, N is Avogadro's constant (mol -1 ).

[0217] The following describes the calculation process of Vm. The process of measuring Vm using this instrument is carried out according to the "TriStar3000 Instruction Manual V4.0" attached to this instrument, and the measurement is specifically carried out using the following steps.

[0218] Thoroughly clean and dry the glass sample chamber (rod diameter = 3 / 8 inch, volume = approximately 5 mL) attached to the instrument, and then accurately weigh it to determine the tare weight. Introduce the sample into this sample chamber using a funnel. The sample amount is appropriately adjusted according to the specific gravity and particle size of the sample; for toner, approximately 1.0 g is introduced.

[0219] Set the sample chamber containing the sample in the "Vacuprep 061 pretreatment equipment" (Shimadzu Corporation) connected to the vacuum pump and nitrogen gas pipeline, and continue vacuum degassing at 23°C for approximately 10 hours. This vacuum degassing is carried out by gradually degassing while adjusting the valve to avoid sucking the sample into the vacuum pump. The pressure in the chamber is gradually reduced as the degassing progresses, and finally reaches approximately 0.4 Pa (approximately 3 mTorr). After completing the vacuum degassing, gradually introduce nitrogen gas and restore the inside of the sample chamber to atmospheric pressure and remove the sample chamber from the pretreatment equipment. Accurately weigh the mass of the sample chamber, and calculate the accurate mass of the toner from the difference from the tare weight. Seal the sample chamber with a rubber stopper during weighing to prevent contamination of the sample in the sample chamber by, for example, moisture in the atmosphere.

[0220] Then measure the free space in the sample chamber including the connection fixture. For the free space, measure the volume of the sample chamber using helium gas at 23°C; then, after cooling the sample chamber with liquid nitrogen, similarly measure the volume of the sample chamber using helium gas; and convert the difference between these volumes to calculate the free space. In addition, the saturated vapor pressure Po (Pa) of nitrogen gas is automatically measured separately using the Po tube built into the instrument.

[0221] Then, after internally vacuum degassing the sample chamber, while continuing the vacuum degassing, the sample chamber is cooled with liquid nitrogen. After that, nitrogen gas is introduced into the sample chamber in stages, and nitrogen molecules are adsorbed onto the sample. At this time, if necessary, the above adsorption isotherm is obtained by measuring the equilibrium pressure P (Pa), and this adsorption isotherm is converted into a BET graph. The relative pressure Pr points for data collection are set to a total of six points, namely, 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30. A straight line is generated from the obtained measurement data by the least squares method, and Vm is calculated from the slope and intercept of this straight line. Using the value of Vm, the BET specific surface area of the toner is calculated as described above.

[0222] <Method for identifying the resin type of the resin in the outermost layer>

[0223] For the resin in the outermost layer, the type of the resin is identified using a time-of-flight secondary ion mass spectrometer (TOF-SIMS).

[0224] Measuring instrument: TRIFT IV TOF-SIMS (Ulvac-Phi, Inc.)

[0225] Primary ion species: gold ions (Au + )

[0226] Primary ion acceleration voltage: 30 keV

[0227] Primary ion current value: 2 pA

[0228] Analysis area: 300×300 μm 2

[0229] Number of pixels: 256×256 pixels

[0230] Analysis time: 3 minutes

[0231] Repetition frequency: 8.2 kHz

[0232] Charge neutralization: on

[0233] Secondary ion polarity: positive

[0234] Secondary ion mass range (m / z): 0.5 to 1,850

[0235] <Method for identifying the resin type of the binder resin and the structure of the ester wax compound in the wax>

[0236] The resin type of the binder resin and the structure of the ester wax compound in the wax are identified using nuclear magnetic resonance spectroscopy ( 1 H-NMR) [400 MHz, CDCl3, room temperature (25 °C)] or pyrolysis GCMS.

[0237] (Measurement conditions in nuclear magnetic resonance spectroscopy 1 H-NMR)

[0238] Measuring instrument: JNM-EX400 FT-NMR instrument (JEOL Ltd.)

[0239] Measuring frequency: 400 MHz

[0240] Pulse condition: 5.0 μs

[0241] Frequency range: 10,500 Hz

[0242] Number of scans: 64 times

[0243] Solvent: Appropriately use a deuterated solvent that dissolves the toner.

[0244] (Pyrolysis GCMS measurement conditions)

[0245] Measuring instrument: Pyrolysis GCMS instrument

[0246] Pyrolysis instrument: JPS700 Curie point pyrolyzer (Japan Analytical Industry Co., Ltd.)

[0247] Pyrofoil: F590 (Curie point is 590 °C)

[0248] GCMS: Focus GC / ISQ (Thermo Fisher Scientific K.K.)

[0249] Carrier gas: He gas (purity is 99.99995%)

[0250] Column: HP-5MS (30 m, inner diameter is 0.25 mm, film thickness is 0.25 μm)

[0251] Inlet temperature: 280 °C, MS transfer temperature: 280 °C, ion source temperature: 250 °C

[0252] Oven temperature: Start from 50 °C and hold for 3 minutes; then heat to 300 °C at 10 °C / minute; then hold for 30 minutes

[0253] Helium flow rate: 1.2 mL / minute, constant flow control, split ratio: 20

[0254] MS ion source: EI, MS detection range (m / z): 25 to 800

[0255] Database: NIST

[0256] Under the above measurement conditions, 0.5 mg of the toner and 5 μL of the methylation reagent (10% methanol solution of tetramethylammonium hydroxide) were added to Pyrofoil and analyzed.

[0257] <Method for Measuring the Number-Average Primary Particle Size of External Additives>

[0258] The number-average primary particle size of the external additive is measured using a scanning electron microscope (SEM).

[0259] Measuring instrument: SEM (JSM-7800F, JEOL Ltd.)

[0260] Accelerating voltage: 1.0 kV

[0261] Magnification: 100,000 times

[0262] The surface of the toner is observed under these conditions, and the particle size of the external additive is measured. This process is repeated and the arithmetic mean of 200 is determined.

[0263] Embodiment

[0264] The toner and toner production method according to the present disclosure are described more specifically by the examples provided below. However, these in no way limit the present disclosure. Unless otherwise specifically stated, "parts" in all cases in the examples and comparative examples are based on mass.

[0265] <Preparation of the Outermost Layer Material: Production Example of Thermoplastic Resin Dispersion Liquid 1>

[0266] 5.0 parts of sodium dodecyl sulfate and 1,000.0 parts of deionized water were introduced into a beaker equipped with a stirrer, and stirring was continued at 25 °C until complete dissolution occurred to prepare an aqueous solution. Then the following materials were mixed to prepare a polymerizable monomer composition.

[0267]

[0268] The polymerizable monomer composition was cooled to 15 °C, and then 6.0 parts of tert-butyl peroxyneodecanoate as a polymerization initiator were mixed and added to the above aqueous solution. The emulsion of the polymerizable monomer composition was prepared by exposing it to ultrasonic waves from a high-output ultrasonic homogenizer (VCX-750) for 13 minutes (1-second interval, maintained at 25 °C).

[0269] The emulsion was put into a four-necked flask heated and dried; while stirring the emulsion at 200 rpm, nitrogen was bubbled through for 30 minutes; and then stirring was carried out at 70 °C for 6 hours. Then, in order to stop the reaction, the emulsion was air-cooled while stirring, whereby a thermoplastic resin dispersion 1 of a styrene-acrylic resin that would provide the outermost layer material was obtained. Then, the thermoplastic resin dispersion 1 was separated at 16,500 rpm for 1 hour using a centrifuge, and the supernatant was removed. The dispersion with newly added deionized water and the separation using a centrifuge were repeated three times, and then deionized water was added to prepare a thermoplastic resin dispersion 1 with a solid content concentration of 20.0 mass%. The volume average diameter of the particles in the thermoplastic resin dispersion 1 was measured to be 25 nm, and the Tg was 69 °C.

[0270] <Production Example of Thermoplastic Resin Dispersion 2>

[0271] Except for changing the amount of sodium dodecyl sulfate as shown in Table 1 and changing the composition of the polymerizable monomer composition as shown below, the thermoplastic resin dispersion 2 was produced as carried out in the production method of the thermoplastic resin dispersion 1. The volume average diameter and Tg of the particles in the thermoplastic resin dispersion 2 are given in Table 1.

[0272]

[0273] <Production Example of Thermoplastic Resin Dispersion 3>

[0274] Except for changing the amount of sodium dodecyl sulfate in the production method of the thermoplastic resin dispersion 1 as shown in Table 1, the thermoplastic resin dispersion 3 was produced as carried out in the production method of the thermoplastic resin dispersion 1. The volume average diameter and Tg of the particles in the thermoplastic resin dispersion 3 are given in Table 1.

[0275] [Table 1]

[0276]

[0277] <Production Example of Toner Base Particle Dispersion 1>

[0278] In a reactor equipped with a condenser, a stirrer, and a nitrogen inlet line, the following materials were mixed, heated, and maintained at 180 °C while stirring.

[0279]

[0280] Styrene-acrylic resin 1 was synthesized by continuously dropping a xylene solution of 50.0 parts of 2.0% tert-butyl hydroperoxide into the system over 4.5 hours, and after cooling, the solvent was separated and removed. The weight average molecular weight Mw was 14,500, and the Tg was 65 °C.

[0281] In a reactor equipped with a condenser, a stirrer, and a nitrogen introduction line, the following materials are mixed.

[0282]

[0283] The system is purged with nitrogen through a pressure reduction process, and then heated to 210 °C, and the reaction is carried out for 5 hours while introducing nitrogen and removing the generated water. Then, while continuing stirring, the temperature is gradually raised to 230 °C under reduced pressure, and polyester resin 1 is synthesized by reacting for another 3 hours. The weight-average molecular weight Mw is 9,500, and the Tg is 68 °C.

[0284] The following materials are thoroughly mixed using an FM mixer (Nippon Coke & Engineering Co., Ltd.), and then melt-kneaded using a twin-screw kneader (Ikegai Ironworks Corporation) with the temperature set at 100 °C.

[0285]

[0286] The obtained kneaded material is cooled and coarsely pulverized to less than 1 mm using a hammer mill to obtain a coarsely pulverized product.

[0287] Then, a finely pulverized product of about 5 μm is obtained from the obtained coarsely pulverized product using a Turbo Mill from Turbo Kogyo Co., Ltd., and then the fine powder and the coarse powder are separated using a multi-stage classifier based on the Coandă effect to obtain toner base particles 1.

[0288] The number-average particle diameter (D1) of the toner base particles 1 is 5.4 μm, the weight-average particle diameter (D4) is 6.8 μm, and the Tg is 58 °C.

[0289] 15.0 parts of sodium phosphate (dodecahydrate) are put into 390.0 parts of deionized water in a reactor, and it is kept at 65 °C for 1.0 hour while purging with nitrogen.

[0290] Stirring is carried out at 12,000 rpm using a T.K. homogenizer (Tokushu Kika Kogyo Co., Ltd.). While maintaining the stirring, an aqueous calcium chloride solution prepared by dissolving 9.0 parts of calcium chloride (dihydrate) in 10.0 parts of deionized water is entirely put into the reactor at once to prepare an aqueous medium containing inorganic fine particles as a dispersant. 1.0 mol / L hydrochloric acid is put into the aqueous medium in the reactor to adjust the pH to 6.0, and aqueous medium 1 is provided.

[0291] 200.0 parts of toner base particles 1 were put into aqueous medium 1 and dispersed at a temperature of 40 °C for 30 minutes while rotating at 7,000 rpm using a T.K. homogenizer. Deionized water was added to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby providing toner base particle dispersion 1.

[0292] <Production Examples of Toner Base Particle Dispersions 2 to 5>

[0293] Except for changing the amounts of sodium phosphate and calcium chloride used for aqueous medium 1 in the production method of toner base particle dispersion 1 as shown in Table 2, aqueous media 2 to 5 and toner base particle dispersions 2 to 5 were produced as in the production method of toner base particle dispersion 1.

[0294] <Production Example of Toner Base Particle Dispersion 6>

[0295] The following materials were thoroughly mixed using an FM mixer (Nippon Coke & Engineering Co., Ltd.), and then melt-kneaded using a twin-screw kneader (Ikegai Ironworks Corporation) with the temperature set at 100 °C.

[0296]

[0297] The obtained kneaded material was cooled and coarsely pulverized to less than 1 mm using a hammer mill to obtain a coarsely pulverized product.

[0298] Then, a finely pulverized product of about 5 μm was obtained from the obtained coarsely pulverized product using a Turbo Mill from Turbo Kogyo Co., Ltd., and then the fine powder and the coarse powder were separated using a multi-stage classifier based on the Coanda effect to obtain toner base particles 2.

[0299] The number average particle diameter (D1) of the toner base particles 2 was 5.6 μm, the weight average particle diameter (D4) was 7.0 μm, and the Tg was 60 °C.

[0300] 200.0 parts of toner base particles 2 were put into aqueous medium 1 and dispersed at a temperature of 40 °C for 30 minutes while rotating at 7,000 rpm using a T.K. homogenizer. Deionized water was added to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby providing toner base particle dispersion 6.

[0301] <Production Example of Toner Base Particle Dispersion 7>

[0302] 14.0 parts of sodium phosphate (dodecahydrate) were charged into 390.0 parts of deionized water in a reactor, and it was maintained at 65 °C for 1.0 hour while purging with nitrogen.

[0303] Stirring was carried out at 12,000 rpm using a T.K. homogenizer (Tokushu Kika Kogyo Co., Ltd.). While maintaining the stirring, an aqueous calcium chloride solution prepared by dissolving 9.2 parts of calcium chloride (dihydrate) in 10.0 parts of deionized water was charged into the reactor all at once to prepare an aqueous medium containing inorganic fine particles as a dispersant. 1.0 mol / L hydrochloric acid was charged into the aqueous medium in the reactor to adjust the pH to 6.0, and aqueous medium 6 was provided.

[0304] Preparation of Polymerizable Monomer Composition 1

[0305] · 60.0 parts of styrene

[0306] · 6.3 parts of C.I. Pigment Blue 15:3

[0307] These materials were charged into a grinder (Nippon Coke & Engineering Co., Ltd.), and dispersed for 5.0 hours at 220 rpm using zirconia particles with a diameter of 1.7 mm to prepare a colorant dispersion liquid in which the pigment was dispersed.

[0308] Then the following materials were added to the colorant dispersion liquid.

[0309] · 18.0 parts of styrene

[0310] · 20.0 parts of n-butyl acrylate

[0311] · 5.0 parts of polyester resin a

[0312] (Condensation polymer of 2 mol adduct of propylene oxide of terephthalic acid and bisphenol A, weight average molecular weight Mw = 10,000)

[0313] · 6.0 parts of HNP9 (melting point: 76 °C, Nippon Seiro Co., Ltd.)

[0314] · 15.0 parts of ethylene glycol distearate

[0315] Then the material was maintained at 65 °C and dissolved and dispersed to homogeneity at 500 rpm using a T.K. homogenizer to prepare Polymerizable Monomer Composition 1.

[0316] (Granulation Step)

[0317] While maintaining the temperature of the aqueous medium 6 at 70 °C and the rotation speed of the stirrer at 12,000 rpm, the polymerizable monomer composition 1 was introduced into the aqueous medium 6, and 7.0 parts of the polymerization initiator tert-butyl peroxypivalate were added. Granulation was carried out for 10 minutes under these conditions while maintaining 12,000 rpm with the stirrer.

[0318] (Polymerization step)

[0319] The high-speed stirrer was replaced with a stirrer equipped with a propeller impeller, and polymerization was carried out for 5.0 hours while maintaining 70 °C and stirring at 150 rpm. Another polymerization reaction was carried out by raising the temperature to 85 °C and heating for 2.0 hours. Deionized water was added to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby obtaining a toner base particle dispersion 7 in which the toner base particles 3 were dispersed.

[0320] The number average particle diameter (D1) of the toner base particles 3 was 5.4 μm, the weight average particle diameter (D4) was 6.2 μm, and the Tg was 56 °C.

[0321] <Production example of toner base particle dispersion 8>

[0322] The reactor containing 400.0 parts of deionized water was maintained at 30 °C, and then dilute hydrochloric acid was added to adjust the pH of the aqueous medium to 4.0. After adjusting the pH, the following materials were introduced and dissolved to obtain an aqueous medium 7.

[0323] · 0.6 part of Mirbane Resin SM-607 hydroxymethylmelamine aqueous solution (solid content concentration 80%)

[0324] · 5.0 parts of polyacrylamide aqueous solution (BECKAMINE A-1 thermoplastic resin dispersion (DIC Corporation), aqueous solution with a solid content concentration of 11% by mass)

[0325] 200.0 parts of toner base particles 1 were added to the aqueous medium 7, and the reactor was stirred at a speed of 200 rpm for 1 hour. Then, deionized water was added to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby obtaining a toner base particle dispersion 8 in which the toner base particles 1 were dispersed.

[0326] <Production example of toner base particle dispersion 9>

[0327] The reactor containing 400.0 parts of deionized water was maintained at 30 °C, and then dilute hydrochloric acid was added to adjust the pH of the aqueous medium to 4.0. After adjusting the pH, the following materials were introduced to obtain an aqueous medium 8.

[0328] · 5.0 parts of thermoplastic resin dispersion liquid 1

[0329] 200.0 parts of toner base particles 1 were added to 8 parts of an aqueous medium, and the reactor was stirred at a speed of 200 rpm for 1 hour. Then, deionized water was added to adjust the concentration of the toner base particles in the dispersion liquid to 20.0%, thereby obtaining a toner base particle dispersion liquid 9 in which the toner base particles 1 were dispersed.

[0330] <Production example of toner base particle dispersion liquid 10>

[0331] A reactor containing 400.0 parts of deionized water was maintained at 30 °C, and then dilute hydrochloric acid was added to adjust the pH of the aqueous medium to 4.0. After adjusting the pH, the following materials were added to obtain an aqueous medium 9.

[0332] · 3.0 parts of thermoplastic resin dispersion liquid 3

[0333] 200.0 parts of toner base particles 1 were added to the aqueous medium 9, and the reactor was stirred at a speed of 200 rpm for 1 hour. Then, deionized water was added to adjust the concentration of the toner base particles in the dispersion liquid to 20.0%, thereby obtaining a toner base particle dispersion liquid 10 in which the toner base particles 1 were dispersed.

[0334] <Production example of toner base particle dispersion liquid 11>

[0335] A reactor containing 400.0 parts of deionized water was maintained at 30 °C, and then dilute hydrochloric acid was added to adjust the pH of the aqueous medium to 4.0. After adjusting the pH, the following materials were added and dissolved to obtain an aqueous medium 10.

[0336] · 1.2 parts of Mirbane Resin SM-607 hydroxymethyl melamine aqueous solution (solid content concentration 80%)

[0337] 200.0 parts of toner base particles 2 were added to the aqueous medium 10, and the reactor was stirred at a speed of 200 rpm for 1 hour. Then, deionized water was added to adjust the concentration of the toner base particles in the dispersion liquid to 20.0%, thereby obtaining a toner base particle dispersion liquid 11 in which the toner base particles 2 were dispersed.

[0338] <Production example of toner base particle dispersion liquid 12>

[0339] (Previously externally added to toner base particles 2)

[0340] Using a mixer (FM-10B Henschel mixer obtained from Nippon Coke & Engineering Co., Ltd.), the toner base particles 2 and acrylic monodisperse particles (MP-1451, Soken Chemical & Engineering Co., Ltd., volume average diameter = 200 nm) were mixed at 4,000 rpm for 5 minutes to obtain toner base particles 4 in which the acrylic monodisperse particles had been externally added in advance to the surface of the toner base particles 2.

[0341] 200.0 parts of the toner base particles 4 were added to 10 parts of an aqueous medium, and the reactor was stirred at a speed of 200 rpm for 1 hour. Then, deionized water was added to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby obtaining a toner base particle dispersion 12 in which the toner base particles 4 were dispersed.

[0342] <Production Example of Toner Base Particle Dispersion 13>

[0343] 15.3 parts of magnesium chloride were put into and dissolved in 350.0 parts of deionized water in the reactor, and then it was maintained at 65 °C for 1.0 hour while purging with nitrogen.

[0344] Using a T.K. homomixer (Tokushu Kika Kogyo Co., Ltd.), stirring was carried out at 12,000 rpm. While maintaining the stirring, an aqueous sodium hydroxide solution in which 10.8 parts of sodium hydroxide were dissolved in 50.0 parts of deionized water was entirely added to the reactor at once to prepare an aqueous medium containing a dispersion stabilizer. 1.0 mol / L hydrochloric acid was added to the aqueous medium in the reactor to adjust the pH to 6.0, and an aqueous medium 11 was provided.

[0345] (Granulation Step)

[0346] While maintaining the temperature of the aqueous medium at 70 °C and the rotation speed of the stirrer at 12,000 rpm, the polymerizable monomer composition 1 was added to the aqueous medium 11, and 7.0 parts of a polymerization initiator, tert-butyl peroxypivalate, were added. Granulation was carried out under these conditions for 10 minutes while maintaining 12,000 rpm with the stirrer.

[0347] (Polymerization Step)

[0348] Replace the high-speed stirrer with a stirrer equipped with a propeller-type impeller, and carry out the polymerization reaction at 80 °C while stirring at 150 rpm. After the polymerization conversion rate reaches about 100%, while maintaining the same polymerization temperature, add 2.0 parts of methyl methacrylate as the outermost layer polymerizable monomer and 0.1 part of 2,2-azobis(2-methyl-N-(2-hydroxyethyl)propionamide) (VA086, Wako Pure Chemical Industries, Ltd.) dissolved in 10.0 parts of deionized water. Then raise the temperature to 90 °C and carry out the polymerization reaction while heating for 3.0 hours. Add deionized water to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby obtaining a toner base particle dispersion liquid 13 in which the toner base particles 5 are dispersed.

[0349] The number average particle diameter (D1) of the toner base particles 5 is 5.6 μm, the weight average particle diameter (D4) is 6.4 μm, and the Tg is 57 °C.

[0350] <Production Example of Toner Base Particle Dispersion Liquid 14>

[0351] In a reactor equipped with a condenser, a stirrer, and a nitrogen inlet line, the following materials are mixed.

[0352]

[0353] The system is purged with nitrogen through a pressure reduction process, and then heated to 210 °C, and the reaction is carried out for 5 hours while introducing nitrogen and removing the generated water. Then, while continuing to stir, the temperature is gradually raised to 230 °C under reduced pressure, and polyester resin 2 is synthesized by reacting for another 3 hours. The weight average molecular weight Mw is 8,200, and the Tg is 54 °C.

[0354] In a reactor equipped with a condenser, a stirrer, and a nitrogen inlet line, the following materials are mixed.

[0355]

[0356] The system is purged with nitrogen through a pressure reduction operation, and then heated to 210 °C, and the reaction is carried out for 5 hours while introducing nitrogen and removing the generated water. Then, while continuing to stir, the temperature is gradually raised to 230 °C under reduced pressure, and polyester resin 3 is synthesized by reacting for another 3 hours. The weight average molecular weight Mw is 7,800, and the Tg is 40 °C.

[0357] Using an FM mixer (Nippon Coke & Engineering Co., Ltd.), the following materials were thoroughly mixed, and then melt-kneaded using a twin-screw kneader (Ikegai Ironworks Corporation) with the temperature set at 100 °C.

[0358]

[0359] The resulting kneaded material was cooled and coarsely pulverized to less than 1 mm using a hammer mill to obtain a coarsely pulverized product.

[0360] Then, a finely pulverized product of approximately 5 μm was obtained from the resulting coarsely pulverized product using a Turbo Mill from Turbo Kogyo Co., Ltd., and then the fine powder and the coarse powder were separated using a multi-stage classifier based on the Coandă effect to obtain toner base particles 6.

[0361] The number average particle diameter (D1) of the toner base particles 6 was 5.8 μm, the weight average particle diameter (D4) was 7.1 μm, and the Tg was 62 °C.

[0362] 200.0 parts of the toner base particles 6 were put into an aqueous medium 8 and dispersed at a temperature of 40 °C for 30 minutes while rotating at 7,000 rpm using a T.K. homogenizer. Deionized water was added to adjust the concentration of the toner base particles in the dispersion to 20.0%, thereby providing a toner base particle dispersion 14.

[0363] <Production Example of Toner Base Particle Dispersion 15>

[0364] Except for not using ethylene glycol distearate, toner base particles 7 were obtained as in the case of toner base particles 1. Then, a toner base particle dispersion 15 was obtained as in the case of toner base particle dispersion 1.

[0365] <Production Example of Toner Base Particle Dispersion 16>

[0366] Except for using 1,6-hexanediol dilaurate instead of ethylene glycol distearate, toner base particles 8 were obtained as in the case of toner base particles 1. Then, a toner base particle dispersion 16 was obtained as in the case of toner base particle dispersion 1.

[0367] <Production Example of Toner Base Particle Dispersion 17>

[0368] Except for using CH3(CH2) 25 COO(CH2)2COO(CH2) 25Instead of the ester compound given by CH3 replacing ethylene glycol distearate, toner base particles 9 were obtained by proceeding as with toner base particles 1. Then, toner base particle dispersion liquid 17 was obtained by proceeding as with toner base particle dispersion liquid 1.

[0369] [Table 2]

[0370]

[0371] *: The amount that makes the toner base particle concentration 20.0%.

[0372] <Production Example of Toner Particle 1>

[0373] The following samples were weighed into a reactor and mixed using a propeller impeller.

[0374] · 500.0 parts of toner base particle dispersion liquid 1

[0375] · 10.0 parts of thermoplastic resin dispersion liquid 1

[0376] Then, the pH of the resulting mixture was adjusted to 7.0 using a 1 mol / L aqueous NaOH solution, and the temperature of the mixture was made 30 °C and then maintained for 1.0 hour while mixing at 200 rpm using a propeller impeller. Then, while stirring with a propeller impeller, the temperature was raised to 80 °C at a rate of 1 °C per minute and maintained for 2 hours.

[0377] Thereafter, the temperature of the content was cooled to room temperature (about 25 °C); then the pH was adjusted to 1.5 using 1 mol / L hydrochloric acid and stirred for 1.0 hour; and while washing with deionized water, it was filtered, and then toner particle 1 having a styrene-acrylic thermoplastic resin in the outermost layer was obtained.

[0378] <Production Examples of Toner Particles 2 to 12 and 14 to 20>

[0379] Except that the types and amounts of the toner base particle dispersion liquid and the thermoplastic resin dispersion liquid in the production example of toner particle 1 were changed as shown in Table 3, toner particles 2 to 12 and 14 to 20 were produced by proceeding as in the production example of toner particle 1.

[0380] <Production Example of Toner Particle 13>

[0381] The following samples were weighed into a reactor and mixed using a propeller impeller.

[0382] · 500.0 parts of toner base particle dispersion liquid 1

[0383] · 0.6 part of Mirbane Resin SM-607, an aqueous solution of hydroxymethyl melamine (solid content concentration: 80%)

[0384] Then, the temperature of the mixture was set at 30 °C and then maintained for 1.0 hour while mixing at 200 rpm using a propeller impeller. Then, while stirring with a propeller impeller, the temperature was raised to 80 °C at a rate of 1 °C / minute and maintained for 2 hours. Subsequently, the pH of the resulting mixture was adjusted to 7.0 using a 1 mol / L aqueous NaOH solution.

[0385] Thereafter, the temperature of the content was cooled to room temperature (about 25 °C); then the pH was adjusted to 1.5 using 1 mol / L hydrochloric acid and stirred for 1.0 hour; and while washing with deionized water, filtration was carried out, and then toner particles 13 having a melamine-based thermosetting resin in the outermost layer were obtained.

[0386] <Production Example of Toner Particles 21>

[0387] 500.0 parts of a toner base particle dispersion 8 was put into a reactor and heated to 80 °C at a rate of 1 °C / minute while stirring at 100 rpm. After the temperature was raised, stirring was continued for 2 hours under the conditions of 80 °C and 100 rpm. Then, the pH of the resulting mixture was adjusted to 7.0 using a 1 mol / L aqueous NaOH solution.

[0388] After the temperature of the content was cooled to room temperature (about 25 °C), filtration and washing were carried out five times to obtain toner particles 21 having a thermoplastic resin and a thermosetting resin in the outermost layer.

[0389] <Production Examples of Toner Particles 22 to 24 and 26>

[0390] Except that the types and amounts of the toner base particle dispersions and the production temperatures in the production example of toner particles 21 were changed as shown in Table 3, toner particles 22 to 24 and 26 were produced as in the production example of toner particles 21.

[0391] <Production Example of Toner Particles 25>

[0392] 500.0 parts of the toner base particle dispersion 12 was put into a reactor and heated to 80 °C at a rate of 1 °C / min while stirring at 100 rpm. After the heating, stirring was continued for 2 hours under the conditions of 80 °C and 100 rpm. Then, the pH of the resulting mixture was adjusted to 7.0 using a 1 mol / L aqueous NaOH solution. After cooling the temperature of the content to room temperature (about 25 °C), filtration and washing were carried out five times to obtain toner particles 25 having a melamine-based thermosetting resin in the outermost layer and acrylic-based monodisperse particles externally added in advance fixed on the surface.

[0393] Then, the acrylic-based monodisperse particles externally added in advance on the surface of the toner base particles were removed. The melamine-based thermosetting resin formed in the outermost layer was firmly fixed to the surface of the toner base particles, while the acrylic-based monodisperse particles externally added in advance were fixed to the surface by a weak force. As a result, even after the formation of the outermost layer, the externally added particles in advance could be removed by applying an external force.

[0394] In this case, first, the toner particles 25 were dispersed in a mixed aqueous solution including a 61.5% sucrose aqueous solution and a 10.0% neutral detergent aqueous solution including a nonionic surfactant and an anionic surfactant for cleaning precision measuring instruments. Then, a treatment of shaking 300 times in 1 minute was carried out using a shaker. After that, the toner particles 25 treated thereby were dispersed in the aforementioned mixed aqueous solution, and a treatment of applying ultrasonic waves at an electrical output of 120 W for 10 minutes was carried out. After carrying out this treatment, filtration and washing were carried out five cycles to obtain toner particles 25 having a melamine-based thermosetting resin in the outermost layer and from which the acrylic-based monodisperse particles were removed.

[0395] <Production Example of Toner Particles 27>

[0396] 500.0 parts of the toner base particle dispersion 14 was put into a reactor and heated to 70 °C at a rate of 1 °C / min while stirring at 100 rpm. During the heating process, immediately after the temperature in the reactor reached 55 °C, the pH of the toner base particle dispersion 14 was adjusted to 9.0 by adding a 1 mol / L aqueous NaOH solution to the reactor. Subsequently, stirring was continued for 2 hours under the conditions of 70 °C and 100 rpm.

[0397] After cooling the temperature of the content to room temperature (about 25 °C), filtration and washing were carried out five cycles to obtain toner particles 27 having a thermoplastic resin in the outermost layer.

[0398] [Table 3]

[0399]

[0400] The properties of the obtained toner particles 1 to 27 are given in Table 4.

[0401] [Table 4]

[0402]

[0403] In Table 4, “Y” in the cell reporting the presence state of the recess indicates that the recess is formed on the surface of the toner particle, and “N” in the cell reporting the presence state of the recess indicates that the recess is not formed on the surface of the toner particle. In other cells, “Y” indicates that the value is within the specified range, and “N” indicates that the value is not within the specified range.

[0404] <Production Example of Toner>

[0405] <Toner 1>

[0406] The following external additives are added to 100 parts of the toner particles 1, and mixed for 10 minutes at a circumferential speed of 32 m / s using an FM mixer (Nippon Coke & Engineering Co., Ltd.); Toner 1 is obtained by removing coarse particles using a sieve with a pore size of 45 μm.

[0407] · 0.8 part of hydrophobic silica with a number average particle size of 12 nm

[0408] · 0.5 part of hydrophobic silica with a number average particle size of 100 nm

[0409] <Toner 2 to 18 and 21 to 27>

[0410] Toner 2 to 18 and 21 to 27 are produced as in the production example of Toner 1.

[0411] <Toner 19>

[0412] The following external additives are added to 100 parts of the toner particles 19, and mixed for 10 minutes at a circumferential speed of 32 m / s using an FM mixer (Nippon Coke & Engineering Co., Ltd.); Toner 19 is obtained by removing coarse particles using a sieve with a pore size of 45 μm.

[0413] · 0.8 part of hydrophobic silica with a number average particle size of 12 nm

[0414] <Toner 20>

[0415] The following external additives shown below were added to 100 parts of toner particles 20, and mixed using an FM mixer (Nippon Coke & Engineering Co., Ltd.) at a circumferential speed of 32 m / s for 10 minutes; the toner 20 was obtained by removing coarse particles using a sieve with a pore size of 45 μm.

[0416] · 0.8 part of hydrophobic silica with a number average particle diameter of 12 nm

[0417] · 0.5 part of hydrophobic silica with a number average particle diameter of 40 nm

[0418] <Examples 1 to 18 and Comparative Examples 1 to 9>

[0419] The following evaluations were performed using toners 1 to 27. The results of the evaluations are given in Table 5.

[0420] The following describes the evaluation methods and evaluation criteria used in the present disclosure.

[0421] A modified machine of a commercially available LBP-712Ci (Canon, Inc.) laser printer was used as the image forming apparatus.

[0422] For the modification, the potentials in charging and transfer, etc. were made reversible by connecting to an external high voltage power supply, and thus image formation could be performed using the positively charged or negatively charged toner generated in this case. The processing speed was also made 210 mm / second.

[0423] A commercially available 040H (cyan) toner cartridge (Canon, Inc.) was used as the processing cartridge. The product toner was taken out from the inside of the processing cartridge; cleaned with a hair dryer; and 165 g of the above toner was loaded.

[0424] The product toner was taken out at each yellow, magenta, and black station, and evaluated using the installed yellow, magenta, and black cartridges with the residual toner amount detection mechanism deactivated.

[0425] <Storage test under harsh environments>

[0426] For each of the obtained toners 1 to 27, approximately 100 g was introduced into a 1,000 mL plastic cup, and it was placed in a low temperature and low humidity environment (15°C, 10% RH) for 24 hours, and then changed to a high temperature and high humidity environment (55°C, 95% RH) within 24 hours. It was placed in the high temperature and high humidity environment for 24 hours, and then changed back to the low temperature and low humidity environment (15°C, 10% RH) within 24 hours. After performing this process three cycles on the toner, it was taken out and aggregation was checked. The time chart of the thermal cycle is given in Figure 1 and the results of the evaluation are given in Table 5.

[0427] (Evaluation criteria)

[0428] A: There is no aggregation at all, and the state is roughly the same as at the beginning.

[0429] B: There is some aggregation behavior, but this is the case where it is broken by gently shaking the plastic cup about five times; it is not a special problem.

[0430] C: There is aggregation behavior, but this is the case where it is easily broken by fingers.

[0431] D: Severe aggregation occurs and it cannot be broken.

[0432] (Evaluation of durability)

[0433] Output an image with a printing rate of 1% continuously in a low-temperature and low-humidity environment with a temperature of 15 °C and a humidity of 10% RH. After every 500 prints, output a solid image and a halftone image, and visually check whether there is the occurrence of vertical stripes caused by toner melting and adhering to the control member, that is, the occurrence of developing stripes. Finally, output 20,000 images. The evaluation results are given in Table 5.

[0434] (Evaluation criteria)

[0435] A: Even at 20,000 sheets, no developing stripes occur

[0436] B: Developing stripes occur between 18,001 and 20,000 sheets

[0437] C: Developing stripes occur between 16,001 and 18,000 sheets

[0438] D: Developing stripes occur below 16,000 sheets

[0439] In addition, in the paper passing durability evaluation, the BET retention rate is calculated using the following formula, where V ini is the BET specific surface area before the paper passing durability test evaluation, and V end is the BET specific surface area after 20,000 sheets of paper passing durability test, and the BET retention rate is used to evaluate the toner durability.

[0440] BET retention rate (%) = V end / V ini × 100

[0441] (Evaluation of low-temperature fixing property)

[0442] Remove the fixing unit from a modified LBP-712Ci laser printer (Canon, Inc.). Using the loaded toner, then form an unfixed toner image with a length of 2.0 cm × a width of 15.0 cm (0.9 mg / cm 2 ) at a position 1.0 cm from the leading edge with respect to the paper feed direction on an image receiving paper (Office Planner 64 g / m 2 , Canon, Inc.). Then modify the removed fixing unit so that the fixing temperature and the processing speed can be adjusted. Use it to conduct a fixing test on the unfixed image.

[0443] First, set the processing speed to 210 mm / s and the fixing line pressure to 27.4 kgf, and operate in a normal temperature and normal humidity environment (23 °C, 60% RH). Measure the low-temperature side fixing start point by fixing the unfixed image at each temperature starting from an initial temperature of 110 °C and sequentially increasing the set temperature at intervals of 5 °C.

[0444] The following gives the evaluation criteria for low-temperature fixability. The evaluation results are shown in Table 5.

[0445] This low-temperature side fixing start point is the lowest temperature at which when rubbing the surface of the fixed image five times at a speed of 0.2 m / s with a lens cleaning paper (Dusper K-3) carrying a load of 4.9 kPa (50 g / cm 2 ), there are three or fewer image peelings with a diameter of 150 μm or more. When strong fixing is not performed, this image peeling shows an increasing tendency.

[0446] The evaluation criteria are as follows.

[0447] A: The low-temperature side fixing start point is less than 120 °C

[0448] B: The low-temperature side fixing start point is 120 °C or more and less than 130 °C

[0449] C: The low-temperature side fixing start point is 130 °C or more and less than 140 °C

[0450] D: The low-temperature side fixing start point is 140 °C or more

[0451] [Table 5]

[0452]

[0453] In the table, "*" indicates the number of printed sheets with developing streaks.

[0454] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications as well as equivalent structures and functions.

Claims

1. A toner comprising toner particles, the toner particles comprising a toner base particle and an outermost layer present on the surface of the toner base particle, the toner base particle comprising a binder resin, characterized in that A plurality of recesses are formed on the surface of the toner particles, and T is the average thickness of the outermost layer in the cross-sectional analysis of the toner particles observed by a transmission electron microscope, and By using a scanning probe microscope to measure the recesses on the toner particles from the outermost surface of the outermost layer toward the center of the toner particles, a is the major axis of each recess, b is the minor axis of each recess, and d is the depth of each recess, where the units of a, b, d, and T are all nm, "n” represents per 1 μm 2 The number of the recessed portions satisfying the following formulas (1) to (3) on the surface of the toner particles, "n” satisfies the following formula (4): 50.0 nm ≤ a ≤ 200.0 nm (1) 10.0 nm ≤ b ≤ 70.0 nm (2) 0.7×T ≤ d ≤ 1.5×T (3) 30≤n≤200 (4)， where the average thickness T of the outermost layer is 5.0 nm to 100.0 nm, The method for measuring the average thickness T of the outermost layer is as follows: Using a transmission electron microscope (TEM), magnify the sample of toner particles by 100,000 times, measure the thickness of the outermost layer at four randomly selected positions on a single toner particle, use this method to perform cross-sectional inspection on 50 toner particles, and use the arithmetic mean of a total of 200 positions as the average thickness T; The method for measuring the major axis a of the recess, the minor axis b of the recess, the depth d of the recess, and the number n of the recesses is as follows: Using a scanning probe microscope (SPM), magnify the surface of the toner particles to 1 μm × 1 μm, and observe the recesses in the outermost layer. After measurement, perform tilt correction on the obtained 1 μm × 1 μm measurement data and then calculate the average surface roughness. The average surface roughness refers to the arithmetic mean of the recess depths in 1 μm × 1 μm for the measurement from the outermost surface of the outermost layer of the toner particles toward the center of the toner particles, that is, the depth d1 of the recesses in the outermost layer; use the above method to measure the depths d1 to d50 of the recesses for 50 toner particles, and use the arithmetic mean of d1 to d50 as the depth d of the recesses; Output the tilt-corrected measurement data provided by the above measurement, measure the arithmetic means of the major axis and the minor axis of the recesses on the surface of each 1 μm × 1 μm toner particle, and respectively designate them as the major axis a1 of the recess and the minor axis b1 of the recess. Use the above method to measure the major axes a1 to a50 of the recesses and the minor axes b1 to b50 of the recesses for 50 toner particles, and respectively designate their arithmetic means as the major axis a of the recess and the minor axis b of the recess; Output the tilt-corrected measurement data provided by the above measurement; check the major axis a, the minor axis b, and the depth d of the recesses in 1 μm × 1 μm; and count the number "n1" of the recesses that satisfy formulas (1) to (3) on the surface of each 1 μm × 1 μm toner particle in each case. Use the above method to count the numbers n1 to n50 of the recesses that satisfy formulas (1) to (3) for 50 toner particles, and designate their arithmetic mean as the number "n" of the recesses, The outermost layer contains a thermoplastic resin or a thermosetting resin. The thermoplastic resin contains a styrene-acrylic resin, and the thermosetting resin contains a melamine resin.

2. The toner according to claim 1, wherein "N" represents a number per 1 μm 2 The number of the concave portions on the surface of the toner particles that satisfy both the following formulas (5) and (6), "N", is 10 or less: 250.0nm 100.0nm The method for measuring the number N of the concave portions is as follows: The toner particle surface is magnified to 1 μm×1 μm using a scanning probe microscope SPM, and the concave portions in the outermost layer are observed. After the measurement, the obtained 1 μm×1 μm measurement data is subjected to tilt correction. Output the tilt-corrected measurement data provided by the above measurement; check the major diameter a and the minor diameter b of the concave portion in 1μm×1μm; and count the number "N1" of coarse concave portions satisfying the formulas (5)-(6) on the surface of each 1μm×1μm colorant particle in each case, count the number N1 to N50 of coarse concave portions satisfying the formulas (5)-(6) for 50 colorant particles using the above method, and designate their arithmetic average as the number "N" of coarse concave portions.

3. The toner according to claim 1 or 2, wherein ​​The styrene-acrylic resin is a polymer of one or more styrene monomers and one or more (meth)acrylic monomers.

4. The toner according to claim 1 or 2, wherein the binder resin contains a styrene-acrylic resin.

5. The toner according to claim 1 or 2, wherein the binder resin contains a polyester resin.

6. The toner according to claim 1 or 2, wherein the toner base particles further contain wax, and the wax contains an ester compound represented by the following formula (7) or (8): wherein, R 1 represents an alkylene having 1 to 6 carbons and R 2 and R 3 each independently represents an alkyl having 11 to 26 carbons.

7. The toner according to claim 1 or 2, wherein silica particles having a number average primary particle diameter of 40.0 nm or more are present on the surface of the toner.

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