Toner and Method for Producing the Same

Abstract

The present invention relates to a toner and a method for producing the same. There is provided a toner having both low-temperature fixability and heat stain resistance and excellent rub resistance of a fixed image. A toner comprising toner particles containing a binder resin, a crystalline polyester, and calcium carbonate particles, wherein the crystalline polyester includes units derived from an aliphatic diol and units derived from an aliphatic dicarboxylic acid, the ester group concentration Ec of the crystalline polyester is 27% by mass or more and 50% by mass or less, the content Ma of the calcium carbonate particles contained in the toner particles is 3% by mass or more and 40% by mass or less, and the ratio (Ma / Mc) of the content Ma of the calcium carbonate particles contained in the toner particles to the content Mc (mass%) of the crystalline polyester contained in the toner particles is 0.2 or more and 20 or less.

Description

Technical Field

[0001] The present invention relates to a toner for an electrophotographic image forming method and a method for producing the same. Background Art

[0002] In recent years, there has been an increasing demand for higher printing speeds, and in order to meet this demand, the development of toners with excellent low-temperature fixability has been carried out. In Japanese Patent Application Laid-Open No. 2017-90489, in order to achieve a toner with excellent low-temperature fixability, the development of a toner using a crystalline resin with excellent rapid meltability has been carried out. In addition, in Japanese Patent Application Laid-Open No. 2016-114828, the development of a toner containing calcium carbonate particles has been carried out to improve the deterioration of transferability caused by the use of a crystalline resin.

[0003] According to the research of the present inventors, it has been found that since the viscosity of the toner using a crystalline polyester as described in Japanese Patent Application Laid-Open No. 2017-90489 decreases at high temperatures, the heat-resistant stain resistance is reduced.

[0004] To solve this problem, by adding an inorganic filler such as calcium carbonate as described in Japanese Patent Application Laid-Open No. 2016-114828, the viscosity of the toner is improved, and the heat-resistant stain resistance can be improved. However, the present inventors have found that depending on the types of the crystalline polyester and the inorganic filler, the effect on the heat-resistant stain resistance is insufficient. In addition, the present inventors have also found that the presence of the inorganic filler in the toner reduces the rub resistance of the fixed image.

[0005] The present invention has been completed in view of the above problems and provides a toner having both low-temperature fixability and heat-resistant stain resistance and excellent rub resistance of the fixed image. Summary of the Invention

[0006] As a result of earnest research by the present inventors, it has been found that the above problems can be solved by allowing a crystalline polyester having a specific structure and calcium carbonate to be present in the toner particles in a specific quantitative ratio.

[0007] The crystalline polyester has a high ester group concentration Ec. The presence of calcium carbonate particles in the toner particles allows the ester groups of the crystalline polyester to interact with the calcium atoms of the calcium carbonate. Due to this interaction, the filler effect is strongly exerted and the cohesive force in the toner particles is improved. As a result, the heat-resistant stain resistance of the toner and the rub resistance of the fixed matter are improved. In addition, since the crystalline polyester has a flexible carbon skeleton by having a structure derived from an aliphatic diol and a structure derived from an aliphatic dicarboxylic acid as constituent units, the crystalline polyester easily contacts the calcium carbonate particles, and the ester groups and the calcium carbonate particles easily interact with each other.

[0008] It is considered that the interaction between the ester groups of the crystalline polyester and the calcium atoms of calcium carbonate is weakened because, when the ester group concentration Ec of the crystalline polyester is too low, the number of interaction points with the calcium atoms decreases. On the other hand, when the ester group concentration Ec of the crystalline polyester is too high, the chain length of the aliphatic groups will inevitably be shortened, and the molecular mobility of the crystalline polyester will be reduced. Therefore, it is considered that it is less likely for the ester groups to come into contact with the calcium atoms to reduce the interaction. Therefore, it is considered that, as defined in the present invention, when the toner particles contain a crystalline polyester having a specific ester group concentration Ec range and calcium carbonate, the effects of the present invention are exhibited.

[0009] That is, the toner according to one aspect of the present invention is a toner including toner particles containing a binder resin, a crystalline polyester, and calcium carbonate particles, wherein the crystalline polyester includes units derived from an aliphatic diol and units derived from an aliphatic dicarboxylic acid, the ester group concentration Ec of the crystalline polyester is 27% by mass or more and 50% by mass or less, when the content of the calcium carbonate particles contained in the toner particles is represented by Ma (% by mass) and the content of the crystalline polyester contained in the toner particles is represented by Mc (% by mass), Ma is 3% by mass or more and 40% by mass or less, and the ratio (Ma / Mc) is 0.2 or more and 20 or less.

[0010] With reference to the accompanying drawings, further features of the present invention will become apparent from the following description of exemplary embodiments. Description of the Drawings

[0011] Figure 1 It is a schematic diagram of an apparatus for heat-treating the surface of toner particles. Detailed Description

[0012] Unless otherwise specified, the description of "XX to YY" representing a numerical range means a numerical range including the lower limit and the upper limit as endpoints.

[0013] The toner according to the present invention includes toner particles, and the toner particles contain a binder resin, a crystalline polyester, and calcium carbonate. Hereinafter, each component will be described.

[0014] <Binder Resin>

[0015] Known polymers can be used as the binder resin contained in the toner particles, and specifically, for example, the following polymers can be used.

[0016] Examples of the polymer include: homopolymers of styrene and substituted styrenes, such as polystyrene, poly(p-chlorostyrene), and poly(vinyltoluene); styrene copolymers, such as styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene-methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, and styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, phenolic resin modified with natural resin, maleic resin modified with natural resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester, polyurethane, polyamide, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone-indene resin, and petroleum resin. These resins can be used alone or in combination of two or more.

[0017] Among them, from the viewpoint of low-temperature fixability, a polyester having high compatibility with the crystalline polyester described later is preferred.

[0018] The content of the binder resin contained in the toner particles is preferably 40% by mass to 90% by mass, and more preferably 50% by mass to 80% by mass.

[0019] <Crystalline polyester>

[0020] The crystalline polyester contained in the toner particles includes units derived from an aliphatic diol and units derived from an aliphatic dicarboxylic acid.

[0021] The crystalline polyester is preferably a condensate of an alcohol containing an aliphatic diol having 2 or more and 15 or less carbon atoms and a carboxylic acid containing an aliphatic dicarboxylic acid having 3 or more and 17 or less carbon atoms.

[0022] The crystalline polyester is more preferably a condensate of the following alcohol and the following carboxylic acid. The alcohol contains an aliphatic diol having 4 or more and 12 or less carbon atoms in an amount of 80 mol% or more and 100 mol% or less (more preferably 85 mol% or more and 100 mol% or less) relative to the total amount of the alcohols constituting the crystalline polyester, and the carboxylic acid contains an aliphatic dicarboxylic acid having 4 or more and 17 or less carbon atoms in an amount of 80 mol% or more and 100 mol% or less (more preferably 85 mol% or more and 100 mol% or less) relative to the total amount of the carboxylic acids constituting the crystalline polyester.

[0023] The aliphatic diol is preferably a linear aliphatic diol, and examples of the aliphatic diol include 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, and their derivatives. There is no particular limitation on the derivatives as long as the crystalline polyester can be obtained by polycondensation. For example, derivatives obtained by esterifying the diol can be mentioned.

[0024] The aliphatic dicarboxylic acid is preferably a linear aliphatic dicarboxylic acid, and examples of the aliphatic dicarboxylic acid include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, pentenedioic acid, azelaic acid, sebacic acid, hexadecanedioic acid, icosanedioic acid, and their derivatives. There is no particular limitation on the derivatives as long as a similar resin structure can be obtained by polycondensation. Examples include derivatives such as acid anhydrides of dicarboxylic acids, alkyl esters of dicarboxylic acids, and acid chlorides of dicarboxylic acids.

[0025] On the other hand, as the carboxylic acid, carboxylic acids other than aliphatic dicarboxylic acids can also be used in combination.

[0026] In the present invention, the ester group concentration Ec of the crystalline polyester refers to the value representing the ratio of the mass of the ester group [-C(=O)O-] to the mass of 1 mol of the crystalline polyester, and specifically, the value represented by the formula (1).

[0027] Ester group concentration Ec (mass%) = [(N × 44) / (1 × number average molecular weight)] × 100... Formula (1)

[0028] Here, in the formula (1), N represents the average number of ester groups contained in one molecule of the crystalline polyester, 44 represents the formula weight of the ester group [-C(=O)O-], and the number average molecular weight represents the number average molecular weight of the crystalline polyester.

[0029] The ester group concentration Ec of the crystalline polyester is 27 mass% or more and 50 mass% or less, and preferably 27 mass% or more and 40 mass% or less. Within the above range, the interaction with calcium carbonate described later becomes appropriate, and the heat stain resistance of the toner is improved.

[0030] On the other hand, when the ratio of the mass of the ester group [-C(=O)O-] to the mass of 1 mol of the binder resin is the ester group concentration Ea of the binder resin, the ratio (Ea / Ec) of the ester group concentration Ea of the binder resin to the ester group concentration Ec of the crystalline polyester is preferably 0.5 or more and 0.7 or less. Within the above range, the low-temperature fixability of the toner is improved. When Ea / Ec is higher than 0.7, since the interaction between the binder resin and the calcium carbonate particles is too strong, the compatibility between the binder resin and the crystalline polyester decreases and the low-temperature fixability decreases. When Ea / Ec is less than 0.5, since the interaction between the crystalline polyester and the calcium carbonate particles is too strong, the compatibility between the crystalline polyester and the binder resin decreases and the low-temperature fixability decreases.

[0031] From the viewpoint of low-temperature fixability, the acid value of the crystalline polyester is preferably 0 mgKOH / g or more and 10 mgKOH / g or less, and more preferably 0 mgKOH / g or more and 5 mgKOH / g or less.

[0032] The content Mc (mass%) of the crystalline polyester contained in the toner particles is preferably 0.1 mass% or more and 5.0 mass% or less. When the content of the crystalline polyester is within the above range, the binder resin exhibits sufficient plasticity, and the crystalline polyester is easily finely dispersed in the toner particles, which further improves the low-temperature fixability.

[0033] <Calcium carbonate particles>

[0034] The toner particles contain calcium carbonate particles.

[0035] As the calcium carbonate particles, for example, light calcium carbonate and colloidal calcium carbonate can be used.

[0036] The content Ma of the calcium carbonate particles contained in the toner particles is 3 mass% or more and 40 mass% or less, and preferably 10 mass% or more and 33 mass% or less. Within the above range, the interaction with the crystalline polyester becomes appropriate, the heat-resistant stain resistance of the toner is improved, and the wiping resistance of the fixed image is also improved.

[0037] The ratio (Ma / Mc) of the content Ma of the calcium carbonate particles contained in the toner particles to the content Mc (mass%) of the crystalline polyester contained in the toner particles is 0.2 or more and 20 or less, preferably 1 or more and 10 or less, and more preferably 5 or more and 10 or less. Within the above range, the filler effect is effectively exerted and the heat-resistant stain resistance of the toner is improved.

[0038] In the cross-section of the toner particles observed using a transmission electron microscope, the average aspect ratio (major axis / minor axis) of the calcium carbonate particles is preferably 1.5 or more and 6.0 or less, more preferably 1.8 or more and 2.7 or less, and even more preferably 2.0 or more and 2.5 or less. Within the above range, the heat-resistant stainability and low-temperature fixability of the toner are improved. When the aspect ratio is less than 1.5, the specific surface area of the calcium carbonate particles decreases, and the filler effect is reduced. Therefore, the heat-resistant stainability is reduced. When the aspect ratio is greater than 3.0, the filler effect is excessively exerted, and thus, the low-temperature fixability is reduced.

[0039] In the cross-section of the toner particles observed using a transmission electron microscope, the standard deviation of the aspect ratio of the calcium carbonate particles is preferably 1.3 or less and more preferably 1.0 or less. When the standard deviation of the aspect ratio is greater than 1.3, it is considered that there is a distribution of regions where the interaction between the crystalline polyester and the calcium carbonate particles is strong and regions where the interaction is weak, and the heat-resistant stainability of the toner is reduced.

[0040] In the cross-section of the toner particles observed using a transmission electron microscope, the number average particle diameter of the calcium carbonate particles is preferably 100 nm or more and 600 nm or less, and more preferably 300 nm or more and 400 nm or less. Within the above range, the interaction between the ester groups of the crystalline polyester and the calcium carbonate particles is improved, and the rub resistance of the fixed image is improved.

[0041] In contrast, when the number average particle diameter of the calcium carbonate particles is less than 100 nm, the interaction between the ester groups of the crystalline polyester and the calcium carbonate particles is weak, and the rub resistance of the fixed image cannot be improved. Further, when the number average particle diameter of the calcium carbonate particles is greater than 600 nm, the interaction between the ester groups of the crystalline polyester and the calcium carbonate particles is large, and the dispersibility of the calcium carbonate particles in the binder resin deteriorates. Therefore, the rub resistance of the fixed image cannot be improved.

[0042] The abundance A of calcium atoms measured by X-ray photoelectron spectroscopy using the toner as a sample is preferably 0 atomic % or more and 0.5 atomic % or less, and more preferably 0 atomic % or more and 0.3 atomic % or less. Within the above range, the interaction between the ester groups of the crystalline polyester and the calcium carbonate particles is improved, the filler effect is effectively exerted, and the heat-resistant stainability of the toner and the rub resistance of the fixed image are improved. When the abundance A is higher than the above range, in the toner layer formed on the paper, there are a large number of calcium carbonate particles between the toner particles, that is, the dispersibility of the calcium carbonate particles deteriorates, thereby reducing the filler effect. Therefore, the heat-resistant stainability is reduced. The abundance A of calcium atoms on the toner surface can be controlled by the hot air temperature in the hot air treatment step described later.

[0043] <Polymer a>

[0044] From the viewpoint of the heat-resistant stain resistance of the toner, the toner particles preferably contain a graft polymer a having a polyolefin as a trunk and a styrene-acrylic resin as a branch. When the toner particles do not contain the polymer a, the interaction between the calcium carbonate particles and the polymer a does not occur, and there is a risk that the dispersibility of the calcium carbonate particles in the binder resin may deteriorate. In this case, since the filler effect is reduced, there is a risk that the heat-resistant stain resistance of the toner may be reduced.

[0045] There is no particular limitation on the polyolefin, and examples of the polyolefin include low molecular weight polyethylene, low molecular weight polypropylene, alkylene copolymers, microcrystalline wax, ester wax, paraffin wax, and Fischer-Tropsch wax. Further, from the viewpoint of the reactivity during the production of the polymer a, the polymer preferably has a branched structure such as polypropylene.

[0046] In the present invention, there is no particular limitation on the method for grafting the styrene-acrylic resin onto the hydrocarbon compound, and known methods can be used. In the polymer a of the present invention, the styrene-acrylic resin more preferably has a structural moiety derived from a saturated alicyclic compound. For example, an aspect in which the styrene-acrylic resin has a monomer unit represented by the formula (A) can be mentioned.

[0047]

[0048] In the formula (A), R 1 represents a hydrogen atom or a methyl group, and R 2 represents a saturated alicyclic group.

[0049] As the saturated alicyclic group represented by R 2 , a saturated alicyclic hydrocarbon group is preferred, a saturated alicyclic hydrocarbon group having 3 or more and 18 or less carbon atoms is more preferred, and a saturated alicyclic hydrocarbon group having 4 or more and 12 or less carbon atoms is even more preferred. Saturated alicyclic hydrocarbon groups include cycloalkyl groups, fused polycyclic hydrocarbon groups, bridged cyclic hydrocarbon groups, and spiro hydrocarbon groups, etc.

[0050] Examples of the saturated alicyclic group include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, tricyclodecyl, decahydro-2-naphthyl, tricyclo[5.2.1.02,6]decane-8-yl, pentacyclopentadecyl, bicyclo[2.2.1]heptane-2-yl, adamantyl, dicyclopentyl, and tricyclopentyl. Further, the saturated alicyclic group may also have an alkyl group, a halogen atom, a carboxyl group, a carbonyl group, or a hydroxyl group, etc. as a substituent. As the alkyl group, an alkyl group having 1 to 4 carbon atoms is preferred.

[0051] Among these saturated alicyclic groups, cycloalkyl groups, fused polycyclic hydrocarbon groups, and bridged cyclic hydrocarbon groups are preferred, cycloalkyl groups having more than 3 and less than 18 carbon atoms, substituted or unsubstituted dicyclopentyl groups, and substituted or unsubstituted tricyclopentyl groups are more preferred, cycloalkyl groups having more than 4 and less than 12 carbon atoms are even more preferred, and cycloalkyl groups having more than 6 and less than 10 carbon atoms are particularly preferred.

[0052] In addition, the position and number of substituents are arbitrary, and when there are two or more substituents, the substituents may be the same as or different from each other.

[0053] The styrene acrylic resin may be a homopolymer of a vinyl monomer (a) having a structural moiety derived from a saturated alicyclic compound, or may be a copolymer with other monomers (b).

[0054] Examples of the vinyl monomer (a) having a structural moiety derived from a saturated alicyclic compound include, for example, cyclopropyl acrylate, cyclobutyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, cycloheptyl acrylate, cyclooctyl acrylate, cyclopropyl methacrylate, cyclobutyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, cyclooctyl methacrylate, dicyclopentadienyl diethyl acrylate, dicyclopentyl acrylate, and dicyclopentyl methacrylate, and combinations of these monomers. Among them, from the viewpoint of hydrophobicity, cyclohexyl acrylate, cycloheptyl acrylate, cyclooctyl acrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, and cyclooctyl methacrylate are preferred.

[0055] Examples of other monomers (b) include: styrene monomers such as styrene, α-methylstyrene, p-methylstyrene, m-methylstyrene, p-methoxystyrene, p-hydroxystyrene, p-acetoxystyrene, vinyltoluene, ethylstyrene, phenylstyrene, and benzylstyrene; alkyl esters of unsaturated carboxylic acids (the alkyl group has more than 1 and less than 18 carbon atoms) such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate; vinyl ester monomers such as vinyl acetate; vinyl ether monomers such as vinyl methyl ether; vinyl monomers containing a halogen element such as vinyl chloride; olefin monomers such as butadiene and isobutene; and combinations of these monomers.

[0056] The ratio (Mo / Mc) of the content Mo (mass %) of polymer a contained in the toner particles to the content Mc (mass %) of the crystalline polyester contained in the toner particles is preferably 0.3 or more and 25 or less, and more preferably 0.4 or more and 15 or less. The ratio (Mo / Ma) of the content Mo (mass %) of polymer a contained in the toner particles to the content Ma (mass %) of the calcium carbonate particles contained in the toner particles is preferably 0.08 or more and 6 or less, and more preferably 0.1 or more and 4 or less. Within the above ranges, the interaction between polymer a and the calcium carbonate particles is improved, and the wiping resistance of the fixed image is improved.

[0057] <Release agent>

[0058] The toner particles may contain a release agent. Examples of the release agent include: low molecular weight polyolefins such as polyethylene; silicones having a melting point; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide, and stearic acid amide; ester waxes such as stearyl stearate; vegetable waxes such as carnauba wax, rice wax, candelilla wax, Japan wax, and jojoba oil; animal waxes such as beeswax; mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and ester wax; and modified products of the above substances.

[0059] The release agent may be used alone or as a mixture of two or more. The melting point of the release agent is preferably 150 °C or lower, more preferably 40 °C or higher and 130 °C or lower, and even more preferably 40 °C or higher and 110 °C or lower. The content of the release agent is preferably 1 part by mass or more and 30 parts by mass or less relative to 100 parts by mass of the binder resin.

[0060] <Colorant>

[0061] The toner particles may contain a colorant. Examples of the colorant include known organic pigments or oil dyes, carbon black, and magnetic substances.

[0062] Examples of cyan-based colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specific examples of cyan-based colorants include C.I. Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0063] Examples of magenta-based colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples of magenta-based colorants include C.I. Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, and 254, and C.I. Pigment Violet 19.

[0064] Examples of yellow-based colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methylene compounds, and allylamide compounds.

[0065] Specific examples of yellow-based colorants include 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, 191, and 194.

[0066] Examples of black-based colorants include carbon black, magnetic substances, and those obtained by toning to black using the above yellow-based colorants, magenta-based colorants, and cyan-based colorants.

[0067] The colorants can be used singly or as a mixture of two or more. In addition, these colorants can also be used in a solid solution state. The colorants can be selected from the viewpoints of hue angle, chroma, brightness, lightfastness, OHP transparency, and dispersibility in toner particles. The content of the colorant is preferably 1 part by mass or more and 20 parts by mass or less relative to 100 parts by mass of the binder resin.

[0068] <External Additive>

[0069] The toner can contain inorganic fine particles as needed. The inorganic fine particles can be added internally to the toner particles or can be mixed with the toner particles as an external additive.

[0070] When inorganic fine particles are included as an external additive, inorganic fine particles such as silica fine particles, titanium oxide fine particles, and alumina fine particles are preferred. Preferably, a hydrophobizing agent such as a silane compound, silicone oil, or a mixture of these compounds is used to hydrophobize the inorganic fine particles. When the inorganic fine particles are used to improve the fluidity of the toner, the specific surface area is preferably 50 m 2 / g or more and 400 m 2 / g or less. On the other hand, when inorganic fine particles are used to improve the durability of the toner, the specific surface area is preferably 10 m 2 / g or more and 50 m 2 / g or less. In order to achieve both the improvement of fluidity and the improvement of durability, inorganic fine particles having a specific surface area within the above range can be used in combination. When inorganic fine particles are included as an external additive, the amount of the inorganic fine particles is preferably 0.1 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the toner particles. For the mixing of the toner particles and the inorganic fine particles, a known mixer such as a Henschel mixer can be used.

[0071] <Method for producing toner>

[0072] There is no particular limitation on the method for producing the toner, and known methods such as an emulsion aggregation method, a pulverization method, and a suspension polymerization method can be used. Preferably, the method for producing the toner includes a step of melt-kneading a mixture including a binder resin, a crystalline polyester, calcium carbonate particles, and a colorant to obtain a melt-kneaded product, and a step of pulverizing the melt-kneaded product to obtain toner particles. By performing melt-kneading, the crystalline polyester and the calcium carbonate particles are dispersed in the binder resin, the interaction between the crystalline polyester and the calcium carbonate particles is improved, the filler effect is exerted, and the heat stain resistance of the toner is improved.

[0073] Hereinafter, as an example, the production process of a toner including pulverized toner particles obtained by using the pulverization method will be described.

[0074] First, as materials constituting the toner particles, for example, a predetermined amount of a binder resin, a crystalline polyester, calcium carbonate particles, a pigment, and other components such as a release agent and a charge control agent as required are weighed, compounded, and mixed. Examples of the mixing device include a double cone mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechano Hybrid.

[0075] Next, the mixed materials are melt-kneaded. In the melt-kneading step, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader such as a single-screw extruder or a twin-screw extruder can be used, and from the viewpoint of the superiority enabling continuous production, a single-screw extruder or a twin-screw extruder is preferred. The temperature for melt-kneading is preferably about 100°C to 200°C. Examples of twin-screw extruders include the KTK type twin-screw extruder (manufactured by Kobe Steel, Ltd.), the TEM type twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), the PCM mixer (manufactured by Ikegai Corp.), the twin-screw extruder (manufactured by KCK Co., Ltd.), the Ko-kneader (manufactured by Buss Corp.), and the Kneadex (manufactured by Nippon Coke & Engineering Co., Ltd.). Further, the resin composition obtained by melt-kneading is rolled using a two-roll mill or the like, and rapidly cooled with water or the like in the cooling step.

[0076] Then, the cooled product of the resin composition is pulverized to a desired particle size in the pulverization step. In the pulverization step, the cooled product of the resin composition is roughly pulverized using a pulverizer such as a crusher, a hammer mill, or a cutter mill, and then further finely pulverized using, for example, the Kryptron system (manufactured by Kawasaki Heavy Industries Ltd.), the Super Rotor (manufactured by Nisshin Engineering Inc.), the Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.), or a fine pulverizer using an air jet system.

[0077] Subsequently, if necessary, the pulverized product is classified using a classifier or a sieve in such a manner as the ElbowJet (manufactured by Nittetsu Mining Co., Ltd.) using an inertial classification system, the Turbo Plex (manufactured by Hosokawa Micron Corporation) using a centrifugal force classification system, the TSP separator (manufactured by Hosokawa Micron Corporation), or the Faculty (manufactured by Hosokawa Micron Corporation) to obtain pulverized toner particles as the classified product.

[0078] <Surface treatment with hot air>

[0079] For toner particles, it is desirable to treat the surface of the toner particles with hot air. By treating the surface of the toner particles with hot air, the shape of the obtained classified product can be adjusted and surface treatment can be performed. The temperature of the hot air is preferably 100 °C or higher and 450 °C or lower. Within the above range, the abundance A of calcium atoms on the surface of the toner can be controlled within the above range.

[0080] Figure 1 An example of a surface treatment apparatus is shown. In Figure 1 the mixture quantitatively supplied by the raw material metering unit 1 is introduced into the introduction pipe 3 mounted on the central axis of the processing chamber 6 by the compressed gas regulated by the compressed gas regulating unit 2. The mixture passing through the introduction pipe 3 is uniformly dispersed by the conical raised member 4 provided at the central portion of the introduction pipe 3, and then introduced into the supply pipe 5 extending in eight radial directions, and then introduced into the processing chamber 6 in which heat treatment is performed from the powder particle supply port 14.

[0081] At this time, the flow rate of the mixture supplied to the processing chamber 6 is adjusted by the regulating unit 9 for regulating the flow rate of the mixture provided in the processing chamber 6. Therefore, the mixture supplied to the processing chamber 6 is heat-treated while swirling in the processing chamber 6, and then cooled by the cold air supplied from the cold air supply unit 8 (cold air supply unit 8-1, cold air supply unit 8-2, and cold air supply unit 8-3).

[0082] The hot air for heat-treating the supplied mixture is supplied from the hot air inlet portion 11 of the hot air supply unit 7, and is introduced into the processing chamber 6 by swirling spirally by means of the swirling member 13 for swirling the hot air. As a configuration, the swirling member 13 for swirling the hot air has a plurality of blades and can control the swirling of the hot air according to the number and angle of the blades. At this time, the deflection of the hot air to be swirled can be reduced by means of the substantially conical distribution member 12.

[0083] The temperature of the hot air at the hot air outlet portion 10 of the hot air supply unit 7 in the processing chamber 6 is preferably 100 °C or higher and 300 °C or lower. When the temperature of the hot air at the hot air outlet portion 10 of the hot air supply unit 7 is within the above range, while preventing the fusion and coalescence of the toner particles due to overheating of the mixture, the toner particles can be uniformly spheroidized.

[0084] The toner particles obtained through the above steps can be used as-is for the toner. If necessary, external additives can be externally added to the surface of the toner particles to obtain the toner. As a method for performing the external addition treatment using external additives, the following method can be used: Mix a predetermined amount of toner particles and various known external additives, and use a mixing device such as a double-cone mixer, V-type mixer, drum mixer, super mixer, Henschel mixer, Nauta mixer, Mechano mixer (manufactured by Nippon Coke & Engineering Co., Ltd.) or Nobilta (manufactured by Hosokawa Micron Corporation) as the external addition machine to stir and mix the materials.

[0085] The volume-based median particle diameter of the toner is preferably 3.0 μm or more and 30.0 μm or less, and more preferably 4.0 μm or more and 20.0 μm or less.

[0086] Hereinafter, methods for measuring physical properties related to the present invention will be described.

[0087] [Measurement of Acid Value of Resin]

[0088] The acid value of the resin is the number of milligrams (mg) of potassium hydroxide required to neutralize acid components such as free fatty acids or resin acids contained in 1 g of the sample. The acid value is measured in accordance with JIS K 0070-1992, and the specific procedure is as follows.

[0089] (1) Reagent Preparation

[0090] Dissolve 1.0 g of phenolphthalein in 90 mL of ethanol (95% by volume), and add ion-exchanged water to make the volume 100 mL to obtain a phenolphthalein solution. Dissolve 7 g of special grade potassium hydroxide in 5 mL of water, and add ethanol (95% by volume) to make the volume 1 L. Place the resulting solution in an alkali-resistant container and leave it for 3 days without contacting carbon dioxide gas, etc., and then filter to obtain a potassium hydroxide solution. Store the obtained potassium hydroxide solution in an alkali-resistant container. The factor of the potassium hydroxide solution is determined as follows: Place 25 mL of 0.1 mol / L hydrochloric acid in a conical flask, add a few drops of the phenolphthalein solution, titrate the solution with the potassium hydroxide solution, and calculate the factor from the amount of the potassium hydroxide solution required for neutralization. The above 0.1 mol / L hydrochloric acid is prepared in accordance with JIS K 8001-1998.

[0091] (2) Procedure

[0092] (A) Main Test

[0093] Precisely weigh 2.0 g of the pulverized sample in a 200 mL conical flask, add 100 mL of a mixed solution of toluene and ethanol (2:1) thereto, and dissolve the mixture for 5 hours. Then, add a few drops of phenolphthalein solution as an indicator, and titrate the resulting mixture with a potassium hydroxide solution. In addition, the end point of the titration is set to the time when the light red color of the indicator persists for about 30 seconds.

[0094] (B) Blank test

[0095] Except for not using the sample (i.e., only using the mixed solution of toluene and ethanol (2:1)), titration is carried out in the same manner as the above operation.

[0096] (3) Calculate the acid value by substituting the obtained results into the following formula.

[0097] A = [(C - B) × f × 5.61] / 2.0

[0098] In the formula, A represents the acid value of the resin (mgKOH / g), B represents the amount of potassium hydroxide solution added in the blank test (mL), C represents the amount of potassium hydroxide solution added in the main test (mL), and f represents the factor of the potassium hydroxide solution.

[0099] [Surface composition analysis by X-ray photoelectron spectroscopy (ESCA)]

[0100] The abundance A of calcium atoms on the surface of the toner is calculated by performing surface composition analysis by means of X-ray photoelectron spectroscopy (ESCA). The ESCA equipment and measurement conditions are as follows.

[0101] Equipment used: PHI 5000 VersaProbe II scanning XPS microprobe, manufactured by Physical Electronics Industries, INC. (PHI)

[0102] Measurement conditions:

[0103] X-ray source: AlKα (100 μ25W 15KV)

[0104] Angle: 45°

[0105] Pass energy: 58.70 eV

[0106] From the peak intensities of the respective elements measured under the above conditions, the surface atomic concentration (atomic %) is calculated using the relative sensitivity factor provided by PHI. The surface atomic concentration of calcium atoms is defined as the abundance A.

[0107] As the elements to be measured, five elements of C, O, Si, Ti, and Ca are measured, and the ratio of calcium atoms among these five elements is calculated. For each atom, the peak intensity based on the orbits of C: 1s, O: 1s, Si: 2p, Ca: 2p, and Ti: 2p is referred to.

[0108] [Aspect ratio of calcium carbonate particles]

[0109] Observation of the cross-section of the toner and evaluation of the aspect ratio of calcium carbonate particles can be carried out by observing the cross-section as follows.

[0110] A cross-section of the toner particle can be prepared by placing the toner particle in the shape of a carbon ribbon, sputtering PtPd for 60 seconds, and irradiating with an argon ion beam to scrape off the excess material. A cross-sectional image of the toner particle can be obtained by the reflection electron imaging method using Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (manufactured by Hitachi High-Technologies Corp.). By observing the cross-section of the toner, calcium carbonate particles are obtained as clear reference objects. The particles in the cross-sectional image of the toner particle are identified using an energy dispersive X-ray spectrometer (EDAX), etc.

[0111] The aspect ratio of calcium carbonate particles is defined by the major axis / minor axis of the calcium carbonate particles. When the calcium carbonate particle is regarded as a rectangular parallelepiped, the major axis of the calcium carbonate particle can be measured as the length along the length direction (the length of the long side). In addition, when the calcium carbonate particle is regarded as a rectangular parallelepiped, the minor axis of the calcium carbonate particle can be measured as the length along the latitude direction (the length of the short side). The aspect ratio is measured for 100 calcium carbonate particles to obtain the average value and standard deviation.

[0112] [Particle size of calcium carbonate particles]

[0113] The number average particle size of calcium carbonate particles means the number average value of the major axis of calcium carbonate primary particles. The number average particle size of calcium carbonate particles can be measured from the reflection electron image of calcium carbonate particles obtained by photographing the cross-section of the toner particle with the above-mentioned S-4800. Specifically, the major axis is measured for 100 calcium carbonate particles to obtain the average value.

[0114] [Measurement method of the content Mc of crystalline polyester and the ester group concentration Ec of crystalline polyester]

[0115] 160 g of sucrose (manufactured by Kishida Chemical Co., Ltd.) was added to 100 mL of ion-exchanged water and dissolved with stirring in a hot water bath to prepare a thick sucrose solution. 31 g of the thick sucrose solution and 6 mL of Contaminon N (a 10 mass% aqueous solution of a neutral cleaner for precision measuring instruments with a pH of 7 containing a nonionic surfactant, an anionic surfactant, and an organic co-washing agent, manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a centrifuge tube to prepare a dispersion. 1.0 g of toner was added to this dispersion, and the lumps of the toner were broken using a spatula or the like. Next, the centrifuge tube was shaken in a shaker. After shaking, the solution was transferred to a glass tube (50 mL) for a swing rotor and separated in a centrifuge at 3500 rpm for 30 minutes.

[0116] This operation is used to separate the toner particles from the detached external additives. It was confirmed by visual observation that the toner particles were completely separated from the aqueous solution, and the toner particles were collected, filtered with a pressure-reducing filter, and then dried in a dryer for at least 1 hour to obtain toner particles separated from the external additives. The weight of the obtained toner particles was measured.

[0117] The binder resin and polymer a were dissolved from the toner particles from which the external additives were separated by the above method with methyl ethyl ketone at 23°C and filtered to obtain filtrate 1 and residue 1.

[0118] After drying residue 1, the crystalline polyester and the release agent were dissolved with heated methyl ethyl ketone at 100°C and filtered to obtain filtrate 2 and residue 2. After drying filtrate 2, the crystalline polyester was dissolved with chloroform and filtered to obtain filtrate 3 and residue 3. By concentrating and drying filtrate 3, the content Mc of the crystalline polyester was measured based on the weight of the toner particles.

[0119] The ester group concentration Ec of the obtained crystalline polyester can be measured using GPC and gas chromatography (GS / MS).

[0120] For example, the ester group concentration Ec of the crystalline polyester can be calculated by formula (1).

[0121] Ester group concentration Ec (mass%) = [(N × 44) / (1 × number average molecular weight Mn)] × 100 Formula (1)

[0122] In formula (1), N represents the average value of the number of ester groups contained in one molecule of the crystalline polyester, 44 represents the formula weight of the ester group, and the number average molecular weight Mn represents the number average molecular weight of the crystalline polyester.

[0123] The number-average molecular weight Mn of the crystalline polyester can be calculated using a GPC measurement system, and, for example, the number-average molecular weight can be calculated by a method using the following equipment. First, using a GPC measurement system (manufactured by Shimadzu Corporation) in which a column (trade name: PLgel 5μm Guard 50×7.5mm, manufactured by Agilent Technologies) is used as a guard column and two columns (trade name: PLgel Mixed C, manufactured by Agilent Technologies) are connected in series, standard polystyrenes (trade names: TSK standard polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, and A-500, all manufactured by Tosoh Corporation) are measured, and a calibration curve is created from the peaks detected by an RI detector to obtain the molecular weight distribution. Next, 50 mg of the obtained crystalline polyester is dissolved in 5 mL of chloroform and allowed to stand for about 5 hours to obtain a solution. This solution is filtered through a solvent-resistant membrane filter with a pore size of 0.5 μm (trade name: MaishoridiskH-25-5, manufactured by Tosoh Corporation) to obtain a sample solution. The obtained sample solution is measured under the same conditions as the measurement of the standard polystyrene, and the molecular weight corresponding to the obtained peak is obtained from the calibration curve, thereby calculating the number-average molecular weight Mn of the crystalline polyester.

[0124] The alcohols containing aliphatic diols and the carboxylic acids containing aliphatic dicarboxylic acids contained in the crystalline polyester can be identified by, for example, pyrolysis gas chromatography. Approximately 200 μg of the crystalline polyester added with 1 μL of tetramethylammonium hydroxide as a pyrolysis aid is used as a sample. The sample is wrapped in Pyrofoil F590 and heated at 590 °C for 5 seconds using a thermal decomposition device (e.g., trade name: JPS-900, manufactured by Japan Analytical Industry Co., Ltd.) to decompose the crystalline polyester. The alcohols containing aliphatic diols and the carboxylic acids containing aliphatic dicarboxylic acids contained in the crystalline polyester and the peak areas derived from the alcohols and carboxylic acids are identified from the following mass spectrum, which is obtained by analyzing the gas generated by the decomposition of the crystalline polyester using a precision mass spectrometer provided in a GC / MS measurement system (trade name: Accurate-Mass Q-TOF GC / MS7200, manufactured by Agilent Technologies) equipped with a column (trade name: HP-5MS, manufactured by Agilent Technologies) and a detector (trade name: JPS-900, manufactured by Japan Analytical Industry Co., Ltd.).

[0125] Next, the number of moles of the monomers is obtained using the peak areas derived from the respective monomers and the calibration curve obtained by pyrolysis gas chromatography in which a calibration curve is created using the standards of the identified monomers. In this way, the molar ratio of the alcohols containing aliphatic diols and the carboxylic acids containing aliphatic dicarboxylic acids that constitute the crystalline polyester (a, b,... x, y... in the following compositional formula) is obtained.

[0126] (Carboxylic acid A)a(Carboxylic acid B)b...(Alcohol X)x(Alcohol Y)y...

[0127] When the molecular weights of carboxylic acid A, carboxylic acid B... are M A 、M B ... and the molecular weights of alcohol X, alcohol Y... are M X 、M Y ... respectively, Equation (2) holds, where the number-average molecular weight of the crystalline polyester is Mn. In Equation (2), n represents a positive number.

[0128] Mn = {(M A + M B +... M X + M Y +...)-(a + b +... x + y +... - 1)×18}×n Equation (2)

[0129] From Equation (2), the value of n is obtained, and the average value N of the number of ester groups contained in one molecule of the crystalline polyester can be obtained from Equation (3).

[0130] N = (a + b +... x + y +... - 1) × n Equation (3)

[0131] By substituting the number-average molecular weight Mn of the obtained crystalline polyester and the average value N of the number of ester groups contained in one molecule of the crystalline polyester resin into Equation (1), the ester group concentration Ea can be obtained.

[0132] <Method for Measuring the Ester Group Concentration Ea of the Binder Resin>

[0133] After drying the filtrate 1, the binder resin (non-crystalline polyester) is dissolved in ethyl acetate to obtain a filtrate 4 and a residue 4. The filtrate 4 is concentrated and dried to obtain the binder resin. The ester group concentration Ea of the obtained binder resin can be measured using GPC and gas chromatography (GS / MS). Measuring the ester group concentration Ea of the binder resin using GPC and gas chromatography (GS / MS) can be carried out in the same manner as measuring the ester group concentration Ec of the crystalline polyester.

[0134] <Method for Measuring the Content Ma of Calcium Carbonate>

[0135] After centrifuging the residue 2 and then concentrating and drying the residue 2, the content Ma of calcium carbonate is measured based on the weight of the toner particles.

[0136] <Method for Measuring the Content Mo of Polymer a>

[0137] By drying the residue 4, the content Mo of polymer a is measured based on the weight of the toner particles. The structure of polymer a is measured using nuclear magnetic resonance spectroscopy (NMR) and infrared spectroscopy (IR).

[0138] [Examples]

[0139] Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but these are not intended to limit the present invention in any way. In the following examples, parts are by mass.

[0140] <Production Example of Binder Resin A1>

[0141] · Fumaric acid: 54.3 parts

[0142] · Ethylene oxide adduct of bisphenol A (BPA-EO): 22.0 parts

[0143] · Propylene glycol: 23.8 parts

[0144] · Tin 2-ethylhexanoate (esterification catalyst): 0.5 part

[0145] Weigh the above materials in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple.

[0146] Purge the reaction vessel with nitrogen, gradually raise the temperature with stirring, and carry out the reaction at 140 °C for 3 hours with stirring.

[0147] Next, reduce the pressure inside the reaction vessel to 8.3 kPa, raise the temperature to 200 °C with stirring, and carry out the reaction for 4 hours (reaction step 1).

[0148] Thereafter, reduce the pressure inside the reaction vessel to below 5 kPa again, and carry out the reaction at 200 °C for 3 hours to obtain the binder resin A1 (reaction step 2).

[0149] <Production examples of binder resins A2 to A11>

[0150] Binder resins A2 to A11 are obtained by carrying out the same operations as in the production example of binder resin A1, except that the types of carboxylic acid and alcohol are changed as shown in Table 1.

[0151] [Table 1]

[0152]

[0153] BPA-PO: Bisphenol A propylene oxide adduct

[0154] BPA-EO: Bisphenol A ethylene oxide adduct

[0155] * For the alcohol component and the carboxylic acid component, the numbers in parentheses represent the molar ratio (%) of each component.

[0156] <Production example of crystalline polyester C1>

[0157] · Adipic acid: 40.9 parts

[0158] (0.31 mol; total molar amount of alcohol is 100.0 mol%)

[0159] · 1,5-Pentanediol: 59.1 parts

[0160] (0.31 mol; total molar amount of carboxylic acid is 100.0 mol%)

[0161] · Tin 2-ethylhexanoate: 0.5 part

[0162] Weigh the above materials in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple.

[0163] The reaction vessel was purged with nitrogen, the temperature was gradually increased with stirring, and the reaction was carried out at 140 °C with stirring for 3 hours. Next, the pressure inside the reaction vessel was reduced to 8.3 kPa, the temperature was increased to 200 °C with stirring, and the reaction was carried out for 1 hour to obtain crystalline polyester C1. The ester group concentration Ec of the obtained crystalline polyester C1 was measured as described above. The results are shown in Table 2.

[0164] <Production Examples of Crystalline Polyesters C2 to C8>

[0165] Except that the conditions were appropriately changed so that the types of aliphatic dicarboxylic acids and aliphatic diols were changed as shown in Table 2, crystalline polyesters C2 to C8 were obtained by performing the same operations as in the production example of crystalline polyester C1. The ester group concentration Ec of each of the obtained crystalline polyesters was measured as described above. The results are shown in Table 2.

[0166] [Table 2]

[0167]

[0168] <Production Example of Polymer a1>

[0169] In an autoclave reaction vessel equipped with a thermometer and a stirrer, 300.0 parts of xylene and 10.0 parts of polypropylene (melting point: 90 °C) were placed and dissolved thoroughly. The reaction vessel was purged with nitrogen, and a mixed solution of 68.0 parts of styrene, 5.0 parts of methacrylic acid, 5.0 parts of cyclohexyl methacrylate, 12.0 parts of butyl acrylate, and 250.0 parts of xylene was added dropwise at 180 °C for 3 hours to carry out polymerization. Further, after maintaining the mixture at this temperature for 30 minutes, the solvent was removed to obtain polymer a1.

[0170] <Production Example of Toner 1>

[0171] ·Binder resin A1: 100 parts

[0172] ·Crystalline polyester C1: 2 parts

[0173] ·Calcium carbonate particles -1: 15 parts (500 nm, aspect ratio: 3.0)

[0174] ·Fischer-Tropsch wax 1: 6 parts

[0175] (Hydrocarbon wax, melting point: 90 °C)

[0176] ·Colorant 1 (C.I. Pigment Blue 15:3) 7 parts

[0177] ·Polymer a1: 20 parts

[0178] Mix the above materials using a Henschel mixer (model: FM-75, manufactured by Mitsui Mine Co., Ltd.) at a rotational speed of 20 s -1 and a rotational time of 5 min. Thereafter, use a twin-screw kneader (model: PCM-30, manufactured by Ikegai Corp.) set to a temperature of 130 °C to knead the mixture. Cool the obtained kneaded product and coarsely crush it with a hammer mill to less than 1 mm to obtain a coarsely crushed product. Use a mechanical grinder (T-250 manufactured by Turbo Kogyo Co., Ltd.) to finely crush the obtained coarsely crushed product. In addition, use a Faculty F-300 (manufactured by Hosokawa Micron Corporation) to classify the finely crushed product. For the operating conditions of the Faculty F-300, set the rotational speed of the classification rotor to 130 s -1 and set the rotational speed of the dispersion rotor to 120 s -1 .

[0179] With the aid of Figure 1 the surface treatment equipment shown in, perform heat treatment on the classified particles. For the operating conditions, set the feed rate to 3 kg / hr, set the hot air temperature to 130 °C, set the hot air flow rate to 6 m 3 / min, set the cold air temperature to -5 °C, set the cold air flow rate to 4 m 3 / min, set the blower air volume to 20 m 3 / min, and set the jet air flow rate to 1 m 3 / min. By performing heat treatment, toner particles 1 with an average circularity of 0.96 are obtained.

[0180] Mix 100 parts of the obtained toner particles, 1.0 part of hydrophobic silica fine particles (BET: 200 m -1 / g) hydrophobized with hexamethyldisilazane, and 1.0 part of titanium oxide fine particles (BET: 80 m 2 / g) surface-treated with isobutyltrimethoxysilane using a Henschel mixer (model: FM-75, manufactured by Mitsui Miike Chemical Engineering Machinery, Co., Ltd.) at a rotational speed of 30 s 2 and a rotational time of 10 min to obtain toner 1. The volume average particle diameter of toner 1 is 6.5 μm.

[0181] <Production Examples of Toners 2 to 21>

[0182] Except for changing the binder resin, crystalline polyester, calcium carbonate particles, polymer a, and heat treatment temperature in the production example of toner 1 as shown in Table 3, toners 2 to 21 were obtained in the same manner as in the production example of toner 1.

[0183] <Production Examples of Toners 22 and 24 to 41 and Comparative Toners 1 to 12>

[0184] Except for changing the binder resin, crystalline polyester, and calcium carbonate particles in the production example of toner 1 as shown in Table 3 and not performing heat treatment, toners 22 and 24 to 41 and comparative toners 1 to 12 were obtained in the same manner as in the production example of toner 1.

[0185] <Production Example of Toner 23>

[0186] Toner 23 was prepared by the emulsion aggregation method for toner particles.

[0187] Preparation of Dispersions

[0188] (Binder Resin A8 Dispersion)

[0189] Regarding binder resin A8, with the pH adjusted to 8.5 with ammonia and under the conditions of a rotation speed of 4000 rpm and a temperature of 100 °C by heating, a super high-speed stirrer T.K. Robomix (manufactured by PRIMIX Corporation) was operated at a composition ratio of 80% ion-exchanged water and 20% binder resin (by concentration), and as a result, a binder resin A8 dispersion (solid content: 20%) was obtained.

[0190] (Crystalline Polyester C4 Dispersion)

[0191] 80 parts of crystalline polyester C4 and 720 parts of ion-exchanged water were each placed in a stainless steel beaker, and the mixture was heated to 100 °C. When crystalline polyester C4 melted, it was stirred at 4000 rpm using a super high-speed stirrer T.K. Robomix (manufactured by PRIMIX Corporation). Next, 1.0 part of an anionic surfactant (NEOGEN RK, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) was added dropwise, and then, emulsion dispersion was carried out to obtain a crystalline polyester C4 dispersion (solid content: 10%).

[0192] (Calcium Carbonate Particle-1 Dispersion)

[0193] Calcium carbonate particle-1: 200 parts

[0194] Anionic surfactant (NEOGEN RK, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 10 parts

[0195] Ion-exchanged water: 790 parts

[0196] The above materials were mixed and stirred at 7000 rpm using a high-speed stirrer T.K. Robomix (manufactured by PRIMIX Corporation). Further, the mixture was dispersed at a pressure of 200 MPa using a high-pressure impact disperser Nanomizer (manufactured by Yoshida Kikai Co., Ltd.) to prepare a calcium carbonate particle-1 dispersion (concentration: 20% by mass).

[0197] (Preparation of colorant dispersion)

[0198] Colorant 1: 100 parts

[0199] Anionic surfactant (NEOGEN RK, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 10 parts

[0200] Ion-exchanged water: 890 parts

[0201] The above materials were mixed and stirred at 7000 rpm using a high-speed stirring device T.K. Robomix (manufactured by PRIMIX Corporation). Further, the mixture was dispersed at a pressure of 200 MPa using a high-pressure impact disperser Nanomizer (manufactured by Yoshida Kikai Co., Ltd.) to prepare a colorant 1 dispersion (concentration: 10% by mass).

[0202] (Preparation of mold release agent dispersion)

[0203] Fischer-Tropsch wax 1: 200 parts

[0204] Anionic surfactant (NEOGEN RK, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 10 parts

[0205] Ion-exchanged water: 790 parts

[0206] Put the above materials into a mixing container equipped with a stirrer, then heat to 90 °C, and while circulating to CLEARMIX W-MOTION (manufactured by M Technique Co., Ltd.), stir at a rotor rotation speed of 19,000 rpm and a screen rotation speed of 19,000 rpm at a shear stirring part where the outer diameter of the rotor is 3 cm and the gap is 0.3 mm, and perform a dispersion treatment for 60 minutes. Thereafter, cool to 40 °C under the cooling treatment conditions of a rotor rotation speed of 1,000 rpm, a screen rotation speed of 0 rpm, and a cooling rate of 10 °C / min to obtain a release agent dispersion (concentration: 20% by mass).

[0207] (Production of Toner 23)

[0208] · Dispersion of Binder Resin A8: 100 parts

[0209] · Dispersion of Crystalline Polyester C4: 4 parts

[0210] · Dispersion of Calcium Carbonate Particles - 1: 15 parts

[0211] · Dispersion of Colorant: 14 parts

[0212] · Dispersion of Release Agent: 6 parts

[0213] · Polyaluminum Chloride: 0.2 part

[0214] Put the above materials into a homogenizer (Ultra Turrax T50, manufactured by IKA) and disperse to prepare a slurry.

[0215] Put the slurry into a stirrer equipped with a mantle heater, and heat to 60 °C while adjusting the rotation speed of the stirrer to stir the slurry sufficiently. After keeping the slurry at 60 °C for 15 minutes, while increasing the temperature at a rate of 0.05 °C / min, measure the particle size of the particles generated by Coulter Multisizer III (aperture diameter: 50 μm, manufactured by Beckman Coulter, Inc.) every 10 minutes, and when the volume average particle size is 6.5 μm, adjust the pH to 9.0 using a 5% aqueous sodium hydroxide solution. Then, while adjusting the pH to 9.0 every 5 °C, raise the temperature to 96 °C at a heating rate of 1 °C / min, and keep the temperature at 96 °C. As a result of observing the particle shape and surface properties with an optical microscope and a scanning electron microscope (FE-SEM) every 30 minutes, when the average circularity reaches 0.960, lower the temperature to 20 °C at a rate of 1 °C / min to solidify the particles.

[0216] Thereafter, the reaction product was filtered, thoroughly washed with ion-exchanged water, and then dried using a vacuum dryer to obtain toner particles.

[0217] Using a Henschel mixer (model: FM-75, manufactured by Mitsui Miike Chemical Engineering Machinery, Co., Ltd.), 100 parts of the obtained toner particles, 1.0 part of hydrophobic silica fine particles (BET: 200 m -1 / g) hydrophobized with hexamethyldisilazane, and 1.0 part of titanium oxide fine particles (BET: 80 m 2 / g) surface-treated with isobutyltrimethoxysilane were mixed at a rotational speed of 30 s 2 and a rotational time of 10 min to obtain Toner 23. The volume average particle diameter of the toner particles in Toner 23 was 6.6 μm.

[0218] [Table 3]

[0219]

[0220]

[0221] The analysis results of the toner are shown in Table 4.

[0222] [Table 4]

[0223]

[0224]

[0225] The following evaluation tests were conducted using each toner.

[0226] [Production Example of Magnetic Core Particles]

[0227] · Step 1 (Weighing and Mixing Step)

[0228] Fe2O3: 62.7 parts

[0229] MnCO3: 29.5 parts

[0230] Mg(OH)2: 6.8 parts

[0231] SrCO3: 1.0 part

[0232] The above materials were weighed, pulverized, and mixed for 5 hours using a dry vibration mill with 1 / 8-inch diameter stainless steel beads to obtain a pulverized mixture.

[0233] · Step 2 (Pre-firing Step)

[0234] The obtained crushed mixture was prepared into pellets with a size of about 1 mm × 1 mm using a roll press. Coarse powder was removed from the pellets using a vibrating sieve with an opening of 3 mm, and then fine powder was removed using a vibrating sieve with an opening of 0.5 mm. The product was fired in a burner-type firing furnace at a temperature of 1000 °C for 4 hours in a nitrogen atmosphere (oxygen concentration: 0.01 vol%) to prepare the calcined ferrite.

[0235] The composition of the obtained calcined ferrite is as follows.

[0236] (MnO) 0.257 (MgO) 0.117 (SrO) 0.007 (Fe2O3) 0.393

[0237] · Step 3 (Crushing step)

[0238] After the obtained calcined ferrite was crushed to about 0.3 mm using a crusher, 30 parts of water was added to 100 parts of the calcined ferrite, and it was crushed for 1 hour using a wet ball mill with zirconia beads having a diameter of 1 / 8 inch. The obtained slurry was crushed for 4 hours using a wet ball mill with alumina beads having a diameter of 1 / 16 inch to obtain a ferrite slurry (fine crushed product of the calcined ferrite).

[0239] · Step 4 (Granulation step)

[0240] To the ferrite slurry, 1.0 part of ammonium polycarboxylate as a dispersant and 2.0 parts of polyvinyl alcohol as a binder were added based on 100 parts of the calcined ferrite, and granulation was carried out into spherical particles by spray drying using a spray dryer (manufactured by Ohkawara Kakohki Co., Ltd.).

[0241] The particle size of the obtained particles was adjusted, and then the particles were heated at 650 °C for 2 hours using a rotary furnace to remove the organic components of the dispersant and the binder.

[0242] · Step 5 (Firing step)

[0243] To control the firing atmosphere, in a nitrogen atmosphere (oxygen concentration: 1.00 vol%), the temperature was raised from room temperature to 1300 °C in 2 hours using an electric furnace, and then the spherical particles were fired at a temperature of 1150 °C for 4 hours. Thereafter, the temperature of the electric furnace was lowered to 60 °C over 4 hours, the atmosphere was restored from the nitrogen atmosphere to the atmosphere, and the spherical particles were taken out at a temperature below 40 °C.

[0244] · Step 6 (Sorting step)

[0245] After crushing the spherical particles aggregated in the firing step, the low-magnetic products are cut by magnetic separation, and coarse particles are removed by sieving with a 250-μm opening mesh screen to obtain magnetic core particles 1 with a 50% particle size (D50) of 37.0 μm based on volume distribution.

[0246] <Preparation of Coating Resin 1>

[0247] · Cyclohexyl methacrylate monomer: 26.8% by mass

[0248] · Methyl methacrylate monomer: 0.2% by mass

[0249] · Methyl methacrylate macromonomer: 8.4% by mass

[0250] (Macromonomer having a methacryloyl group at one end and a weight-average molecular weight of 5000)

[0251] · Toluene: 31.3% by mass

[0252] · Methyl ethyl ketone: 31.3% by mass

[0253] · Azobisisobutyronitrile: 2.0% by mass

[0254] Put the above materials into a four-neck separable flask equipped with a reflux condenser, thermometer, nitrogen inlet tube, and stirrer. Introduce nitrogen to create a sufficient nitrogen atmosphere, and then raise the temperature to 80 °C.

[0255] Thereafter, add 2.0% by mass of azobisisobutyronitrile, and reflux the mixture for 5 hours to polymerize.

[0256] Inject hexane into the obtained reaction product, and precipitate and separate the copolymer. Separate the precipitate by filtration and dry it under vacuum to obtain coating resin 1.

[0257] Dissolve 30 parts of the obtained coating resin 1 in 40 parts of toluene and 30 parts of methyl ethyl ketone to obtain polymer solution 1 (resin solid content concentration: 30% by mass).

[0258] <Preparation of Coating Resin Solution 1>

[0259] · Polymer solution 1 (resin solid content concentration: 30% by mass): 33.3% by mass

[0260] · Toluene: 66.4% by mass

[0261] · Carbon black (Regal 330; manufactured by Cabot Corporation): 0.3% by mass

[0262] (Primary particle size is 25 nm, nitrogen adsorption specific surface area is 94 m2 / g, the DBP oil absorption is 75 ml / 100 g)

[0263] Disperse the above materials for 1 hour using a paint stirrer with zirconia beads having a diameter of 0.5 mm. Filter the obtained dispersion through a 5.0 μm membrane filter to obtain Coating Resin Solution 1.

[0264] <Production Example of Magnetic Carrier 1>

[0265] (Resin Coating Step)

[0266] Add Coating Resin Solution 1 as a resin component to a vacuum degassing type kneader maintained at room temperature in an amount of 2.5 parts relative to 100 parts of Magnetic Core Particle 1.

[0267] After the addition, stir the mixture at a rotational speed of 30 rpm for 15 minutes. After volatilizing the solvent to a level above a predetermined level (80% by mass), while raising the temperature to 80 °C, mix the product under reduced pressure, then distill off toluene over 2 hours, and cool the mixture.

[0268] Separate the low magnetic force products from the obtained magnetic carrier by magnetic separation, pass it through a sieve with an opening of 70 μm, and classify it using an air classifier to obtain Magnetic Carrier 1 with a 50% particle size (D50) based on volume distribution of 38.2 μm.

[0269] <Production Example of Two-Component Developer 1>

[0270] Add 8.0 parts of Toner 1 to 92.0 parts of Magnetic Carrier 1 and mix using a V-type mixer (V-20, manufactured by Seishin Enterprise Co., Ltd.) to obtain Two-Component Developer 1.

[0271] <Production Examples of Two-Component Developers 2 to 39 and Comparative Two-Component Developers 1 to 12>

[0272] Except for combining the toners and Magnetic Carrier 1 shown in Table 5, obtain Two-Component Developers 2 to 39 and Comparative Two-Component Developers 1 to 12 by performing the same operations as in the production example of Two-Component Developer 1.

[0273] [Table 5]

[0274]

[0275] As an image forming apparatus, a modified machine of a digital commercial printing printer (trade name: imageRUNNER (registered trademark) ADVANCE C9075 PRO, manufactured by Canon Inc.) is used, and the following evaluation is performed by the following operations: A two-component developer is placed in the developer unit at the cyan position, and the DC voltage V of the developer carrier member is adjusted DC , the charging voltage V of the electrostatic latent image holding member D and the laser power, so as to obtain a desired toner loading amount on the paper or the electrostatic latent image holding member. The printer is modified so that the fixing temperature and the processing speed can be freely set.

[0276] Test Example 1 [Evaluation of Low Temperature Fixing Property]

[0277] After adjusting the DC voltage V of the developer carrier member DC , the charging voltage V of the electrostatic latent image holding member D and the laser power so that the toner loading amount on the evaluation paper (trade name: CF-C104, A4 paper, basis weight: 104.0 g / m 2 , manufactured by Canon Marketing Japan Inc.) is 0.90 mg / cm under a low temperature and low humidity environment (temperature: 15 °C / humidity: 10% RH) 2 , the processing speed is set to 300 mm / sec, and the fixing temperature is set to 130 °C. Under the above conditions, an image with a center print size of 25 cm 2 is printed on the evaluation paper, and the low temperature fixing property of the image is evaluated. The image density reduction rate value is used as an evaluation index for the low temperature fixing property, and an X-Rite color reflection densitometer (500 series: manufactured by X-Rite Co.) is used to measure the image density reduction rate. First, the image density at the center part is measured. Then, a load of 4.9 kPa (50 g / cm 2 ) is applied to the part where the image density is measured, the fixed image is rubbed with a cleaning paper (repeated 5 times), and the image density is measured again. Then, the reduction rate (%) of the image density before and after rubbing is measured. A grade of C or above is determined to be good. The evaluation results are shown in Table 6.

[0278] The evaluation criteria are as follows.

[0279] A: The density reduction rate is less than 1.0%.

[0280] B: The density reduction rate is 1.0% or more and less than 5.0%.

[0281] C: The density reduction rate is 5.0% or more and less than 10.0%.

[0282] D: The density reduction rate is 10.0% or more.

[0283] Test Example 2 [Evaluation of Heat Resistance and Stain Resistance of Toner]

[0284] Toner loading on paper: 0.60 mg / cm 2

[0285] The reflectance of the evaluation paper before imaging (product name: CF-C104, A4 paper, basis weight: 104.0 g / m 2 , manufactured by Canon Marketing Japan Inc.) was measured using a reflectometer (product name: REFLECTOMETER MODEL TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.), and the average value obtained by measuring the reflectance at 5 positions was set as DA (%). When changing the fixing temperature of the fixing unit of the image forming apparatus and performing image printing so that the toner loading on the paper reaches 0.60 mg / cm 2 At each fixing temperature, the reflectance of the part other than the image forming section was measured using a reflectometer, and the maximum value was set as DB (%). Then, the highest fixing temperature at which the difference between DA (%) and DB (%) does not exceed 0.5% was set as the upper limit fixing temperature. For the upper limit fixing temperature, the heat resistance and stain resistance of the toner were evaluated based on the following criteria. A rating of C or higher was determined to be good. The evaluation results are shown in Table 6.

[0286] (Evaluation Criteria)

[0287] A: 200 °C or higher

[0288] B: Higher than 190 °C and lower than 200 °C

[0289] C: Higher than 180 °C and lower than 190 °C

[0290] D: Higher than 170 °C and lower than 180 °C

[0291] E: Lower than 170 °C

[0292] Test Example 3 [Evaluation of Rub Resistance of Fixed Image]

[0293] On the evaluation paper (product name: OK Top Coat+, basis weight: 127 g / m 2, a halftone image with an image density of 0.20 or more and 0.25 or less is printed on the evaluation paper (manufactured by Oji Paper Co., Ltd.) and used as the evaluation image. Using a "Macbeth Reflection Densitometer RD918" (manufactured by Gretag Macbeth), in accordance with the attached manual, the image density of the evaluation image is measured by measuring the relative density with respect to the white background part of the image with an image density of 0.00 and taking the obtained relative density as the image density value.

[0294] The rub resistance test is carried out by placing the evaluation paper on the evaluation image and placing a 500 g weight on the evaluation paper so that the grounding area is 12.6 cm 2 and rubbing the paper 10 times. Thereafter, within the area of 12.6 cm 2 (within the area where the weight is placed), the toner attached to the paper is measured using a haze meter, and the obtained haze value is evaluated based on the following criteria. A grade of D or above is determined to be good. The evaluation results are shown in Table 6.

[0295] (Evaluation criteria)

[0296] A: The haze value is less than 2%.

[0297] B: The haze value is 2% or more and less than 5%.

[0298] C: The haze value is 5% or more and less than 10%.

[0299] D: The haze value is 10% or more and less than 15%.

[0300] E: The haze value is 15% or more.

[0301] [Table 6]

[0302]

[0303]

[0304] As described above, according to the present invention, a toner having both low-temperature fixability and heat stain resistance and excellent rub resistance of the fixed image can be provided.

[0305] Although the present invention has been described with reference to the exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims is to be accorded the broadest interpretation so as to cover all such modifications as well as equivalent structures and functions.

Claims

1. A toner, comprising: Toner particles containing a binder resin, a crystalline polyester, and calcium carbonate particles, characterized in that the crystalline polyester includes units derived from an aliphatic diol and units derived from an aliphatic dicarboxylic acid, the ester group concentration Ec of the crystalline polyester is 27% by mass or more and 50% by mass or less, when the content of the calcium carbonate particles contained in the toner particles is represented by Ma in mass%, and the content of the crystalline polyester contained in the toner particles is represented by Mc in mass%, the Ma is 3% by mass or more and 40% by mass or less, and the ratio Ma / Mc is 5 or more and 10 or less.

2. The toner according to claim 1, wherein in the cross-section of the toner particles, the average aspect ratio of the calcium carbonate particles observed by a transmission electron microscope, that is, the average value of the major axis / minor axis is 1.5 or more and 6.0 or less.

3. The toner according to claim 1 or 2, wherein the number average particle diameter of the calcium carbonate particles is 100 nm or more and 600 nm or less.

4. The toner according to claim 1 or 2, wherein the acid value of the crystalline polyester is 0 mgKOH / g or more and 10 mgKOH / g or less.

5. The toner according to claim 1 or 2, wherein the content Mc is 0.1% by mass or more and 5.0% by mass or less.

6. The toner according to claim 1 or 2, wherein the abundance A of calcium atoms measured by X-ray photoelectron spectroscopy using the toner as a sample is 0 atomic% or more and 0.5 atomic% or less.

7. The toner according to claim 1 or 2, wherein the ester group concentration Ec is 27% by mass or more and 40% by mass or less.

8. The toner according to claim 1 or 2, wherein the ratio Ea / Ec of the ester group concentration Ea of the binder resin to the ester group concentration Ec is 0.5 or more and 0.7 or less.

9. The toner according to claim 1 or 2, wherein the toner particles contain a graft polymer a having a polyolefin as a main chain and a styrene-acrylic resin as a branch.

10. The toner according to claim 9, wherein the ratio Mo / Mc of the content Mo in mass% of the graft polymer a contained in the toner particles to the content Mc is 0.3 or more and 25 or less, and the ratio Mo / Ma of the content Mo to the content Ma is 0.08 or more and 6 or less.

11. The toner according to claim 1 or 2, wherein the toner particles are pulverized toner particles.

12. A method for producing a toner, It is characterized in that the toner being the toner according to any one of claims 1 to 11, wherein the method for producing the toner includes heat-treating the surface of the toner particles with hot air.

13. The method for producing a toner according to claim 12, wherein the temperature of the hot air is 100°C or more and 450°C or less.

Images