Toner

Abstract

To provide a toner which offers superior low-temperature fixability and superior storage stability in thermal cycling environments.SOLUTION: A toner provided herein comprises toner particles containing a binder resin, crystalline material, and silica particles with a number average particle diameter D1 in a range of 400 to 3000 nm, inclusive, each particle having pointed portions. The crystalline material contains a compound having an ester group.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a toner used in a recording method using an electrophotographic method or the like.

Background Art

[0002] In recent years, image forming apparatuses such as copiers and printers have been diversified in usage purposes and usage environments, and further demanded for higher speed, higher image quality, and higher stability. At the same time, in copiers and printers, miniaturization and energy saving of the apparatuses have been progressing, and a magnetic one-component development method using a magnetic toner, which is advantageous in these respects, is preferably used.

[0003] In the electrophotographic method, there are a charging step of charging an electrostatic latent image carrier (hereinafter referred to as a photoreceptor) by a charging means, an exposure step of exposing the charged photoreceptor to form an electrostatic latent image, and a developing step of developing the electrostatic latent image with toner to form a toner image. Next, the toner image is transferred to a recording material with or without an intermediate transfer member in a transfer step, and is output as an image through a fixing step of heat-press fixing by passing the recording material carrying the toner image through a nip portion formed by a pressure member and a rotatable image heating member.

[0004] In order to meet the recent demand for energy saving and further to cope with use in a wide variety of environments, in addition to performing sufficient fixing at low temperature, higher storage stability than before becomes important. Regarding the improvement of fixability, many techniques have been disclosed in the past, and among them, there are many disclosures regarding plasticizers such as hydrocarbon waxes, ester waxes, and crystalline polyesters.

[0005] However, adding a plasticizer often reduces storage stability. Especially in an environment where the temperature repeatedly rises and falls, such as in a heat cycle, the toner physical properties are likely to vary because the plasticizer repeatedly melts and precipitates. Specifically, phenomena such as the plasticizer seeping out to the toner surface and being more compatible with the resin may occur, affecting the chargeability and fluidity of the toner, and further manifesting as image streaks and density unevenness. Also, since adding a plasticizer reduces the resin viscosity, the hot offset resistance is likely to decrease.

[0006] Regarding these problems, heretofore, for example, in Patent Document 1, attempts have been made to improve storage stability by adding fatty acid amide-treated silica as a crystal nucleating agent inside. Also, in Patent Document 2, a technique for improving filming resistance by incorporating pearl necklace-type silica into core particles is disclosed. Further, in Patent Document 3, a technique for improving low-temperature fixability and productivity by adding inorganic fine particles during melt kneading is also disclosed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, it has been found that the techniques in the above documents are not sufficient from the viewpoint of storage stability in a heat cycle environment. The present disclosure provides a toner that is excellent in low-temperature fixability and also excellent in storage stability in a heat cycle environment.

Means for Solving the Problems

[0009] The present disclosure relates to a toner having toner particles containing a binder resin, a crystalline material, and silica particles, wherein the number average particle diameter D1 of the silica particles is 400 nm or more and 3000 nm or less, the silica particles have pointed portions, In the cross-sectional observation of the toner particles by a transmission electron microscope, (i) the silica particles having the pointed portions are present in an average of 1.0 to 20.0 per one cross-section of the toner particle, (ii) the ratio of the number of cross-sections of the toner particles containing the silica particles having the pointed portions to the number of cross-sections of the observed toner particles is 80% or more, and the crystalline material contains a compound having an ester group. and the toner particle contains a colorant, the colorant contains a magnetic material as a main component

Advantages of the Invention

[0010] According to the present disclosure, it is possible to provide a toner having excellent low-temperature fixability and excellent storage stability in a heat cycle environment.

Brief Description of the Drawings

[0011] [Fig. 1] A diagram for explaining pointed portions

Modes for Carrying Out the Invention

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

[0013] The present disclosure relates to a toner having toner particles containing a binder resin, a crystalline material, and silica particles, wherein the number average particle diameter D1 of the silica particles is 400 nm or more and 3000 nm or less, the silica particles have pointed portions, and the crystalline material contains a compound having an ester group.

[0014] ​The toner contains a compound having an ester group (hereinafter also referred to as an ester compound) as a crystalline material. Generally, a crystalline material having an ester group as described above has high compatibility with a binder resin. For example, when compared with a hydrocarbon wax, the ester compound can bend starting from the ester group, so it has high mobility and excellent plasticity with respect to the binder resin, and is particularly effective in improving low-temperature fixability.

[0015] On the other hand, when simply using a crystalline material having an ester group, the storage stability often decreases. This is considered to be because, due to the high mobility caused by the ester group as described above, molecular motion starts from a relatively low temperature below the melting point, and a part of the crystalline material begins to melt. Furthermore, when the temperature changes from high to low, the melted ester compound crystallizes. Therefore, when high and low temperatures are repeated, melting and crystallization are repeated, and the existing position in the binder resin may gradually change. As a result, the ester compound may move to the toner surface and bleed out, changing the chargeability of the toner and the developability.

[0016] Such a phenomenon becomes prominent in a heat cycle environment where the temperature change is large and the rise and fall of the temperature are repeated. The inventors of the present invention have intensively studied to improve the storage stability in a heat cycle environment for a toner having excellent fixability using a crystalline material having an ester group. As a result, it has been found that the storage stability can be significantly improved by using silica particles having a relatively large particle size and pointed portions.

[0017] Hereinafter, the toner will be described. The above-mentioned "silica particles" are included in the toner particles and refer to those internally added to the binder resin in the toner manufacturing process. That is, the silica particles are mixed with the binder resin in the toner manufacturing process and are in a state of being internally added inside the toner particles when they become toner. For example, the silica particles are dispersed in the binder resin It is as follows. Hereinafter, the silica particles contained in the toner particles are also referred to as internally added silica particles. In the present disclosure, the silica particles refer to particles having silicon dioxide as a main component, and the main component refers to a component constituting 80% by mass or more of the silica particles. According to the study by the present inventors on silica particles, for example, even when a composite compound such as talc is used as a compound containing silica, the effects of the present application were not achieved. It is considered that this is due to the low ratio of silicon dioxide in talc, and it is considered important to use silica particles having a high component ratio of silicon dioxide as described above. In addition, a crystalline material refers to a material having an endothermic peak when measured in accordance with ASTM D3418-82 using a differential scanning calorimeter (for example, "Q1000" (manufactured by TA Instruments) etc.).

[0018] In a heat cycle environment, as described above, a crystalline material having an ester group alternates between a dissolved state and a crystalline state. According to the study by the present inventors, it has been found that internally added silica particles having pointed portions act as a crystal nucleating agent for the ester compound, and the maintenance of the crystalline state of the ester compound is remarkably exhibited.

[0019] Regarding this, the considerations of the present inventors will be described. First, the state of the ester compound during toner production will be described by taking the case including a melt-kneading step as an example. When the binder resin and the ester compound are melt-kneaded at a temperature equal to or higher than the melting point of the ester compound, the ester compound is dissolved in the binder resin. At this time, when silica particles having pointed portions are present in the binder resin, it is considered that the movement of the ester compound is disturbed at the pointed portions, and thus the density distribution of the ester compound is disturbed. Considering in light of the nucleation theory, when there is a non-uniform state, nucleation is likely to occur from there, and the same phenomenon also occurs in the toner, and it is considered that the formation of crystal nuclei is likely to occur due to the pointed portions.

[0020] In addition, according to the study by the present inventors, since silica particles having pointed portions have an effect of promoting the crystallization of the ester compound, rapid crystal formation of the ester compound occurs at the pointed portions, and it is considered that there are many ester compounds in the crystalline state.

[0021] Next, consider the case when exposed to a heat cycle environment. The crystals of the ester compound present at the pointed parts start molecular motion as described above with the increase in temperature and try to dissolve in the binder resin. However, due to the effect of promoting crystallization by the pointed parts of the silica particles, it is considered that nucleation occurs immediately even when melted and recrystallization occurs. Therefore, it is considered that it is possible to prevent the crystals from becoming compatible with the binder resin or further seeping out to the toner surface.

[0022] The pointed parts of the internally added silica particles refer to the parts where the angle shown in Fig. 1 is 90 degrees or less in the cross-sectional observation of the toner. The internally added silica particles having pointed parts refer to silica particles having one or more parts with an angle of 90 degrees or less. A specific method for determining whether the silica particles have pointed parts will be described later. In the cross-sectional observation of the toner by a transmission electron microscope, the number of pointed parts in the internally added silica particles is preferably 1 to 50, more preferably 1 to 20 per internally added silica particle.

[0023] Regarding the toner particles containing silica particles having pointed parts, it means that the toner particles containing the internally added silica particles having pointed parts are 70% or more of the number of observed toner cross-sections in the cross-sectional observation of the toner by a transmission electron microscope. In the cross-sectional observation of the toner by a transmission electron microscope, the ratio (number%) of the toner particles containing silica particles having pointed parts among the number of observed toner particle cross-sections is preferably 80% or more, more preferably 90% or more, and still more preferably 93% or more. The upper limit is not particularly limited, but is preferably, for example, 100% or less, 99% or less. Also, in the cross-sectional observation of the toner by a transmission electron microscope, it is preferable that 1.0 to 30.0 silica particles having pointed parts are present per one cross-section of the toner particle. More preferably, it is 1.0 to 20.0, and still more preferably 1.0 to 10.0.

[0024] In addition, the internally added silica particles may be surface-treated. From the perspective of storage stability in a heat cycle environment, it is preferably not surface-treated with fatty acid amide.

[0025] The number average diameter (D1) of the internally added silica particles is 400 nm or more and 3000 nm or less. When within the above range, the storage stability is enhanced without fixing inhibition. The D1 of the internally added silica particles is preferably 600 nm to 2500 nm, more preferably 1000 nm to 2000 nm.

[0026] Also, the content of the internally added silica particles contained in the toner particles is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, further preferably 0.9 part by mass or more, and even more preferably 1.5 part by mass or more with respect to 100 parts by mass of the binder resin. On the other hand, the upper limit is preferably 10.0 parts by mass or less, more preferably 8.0 parts by mass or less, further preferably 5.0 parts by mass or less, even more preferably 3.0 parts by mass or less, and most preferably 2.5 parts by mass or less.

[0027] Note that the particles internally added to the toner particles need to be silica. According to the study by the present inventors, since silica has the effect of promoting the crystallization of the ester compound, the above effect can be obtained by providing the silica with pointed portions. No effect is observed with other inorganic oxides such as alumina and titania, and the above problems cannot be solved.

[0028] Controlling the quantitative ratio between the compound having an ester group, which is a crystalline material, and the internally added silica particles is also preferable in order to enhance the above effect. Specifically, the value of the ratio on a mass basis of the content of the compound having an ester group in the toner particles to the content of the internally added silica particles contained in the toner particles (silica particles / ester compound) is preferably 1.0 to 20.0, more preferably 2.0 to 11.0, and further preferably 2.5 to 5.0. When within the above range, the effect of the crystalline material having an ester group being crystallized by the internally added silica particles is more sufficiently exerted.

[0029] The method for producing internally-doped silica particles is not particularly limited, and known methods can be used. Methods for producing internally-doped silica particles include a gas-phase method in which silicon compounds such as metal silicon, silicon halides, and silane compounds are reacted in the gas phase, and a wet method in which silane compounds such as alkoxysilanes are hydrolyzed and subjected to a condensation reaction. The production method for internally-doped silica particles can be selected without restriction as long as they have a pointed portion. For the production of relatively large silica particles with diameters of 400 nm to 3000 nm, a gas-phase oxidation method is preferably used in which a powder raw material is directly oxidized with a chemical flame consisting of oxygen and hydrogen. The gas-phase oxidation method makes it possible to instantaneously raise the temperature inside the reaction vessel above the melting point of the inorganic fine powder, making it a preferred method for obtaining large silica particles.

[0030] For example, silica particles having a diameter of about 3000 to 5000 nm can be produced by the gas-phase oxidation method described above, and then pulverized by a known method to obtain internally added silica particles having a sharp portion. For example, a pulverizer or a jet mill, which has a high pulverizing capacity, can be used as a pulverizer to easily control the shape and particle size. Furthermore, the particle size distribution can be adjusted using a known classification device, as appropriate.

[0031] In particular, in order to form pointed portions on silica particles, it is preferable to include a pulverization step in the production of silica particles. Note that, according to the studies of the present inventors, it is difficult to form pointed portions using production methods such as ordinary fumed silica and sol-gel silica. The internally added silica particles preferably contain SiO2 in an amount of 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less. It is more preferable that the content be 98% by mass or more and 100% by mass or less, and it is even more preferable that the content be 98% by mass or more and 100% by mass or less.

[0032] The toner particles may contain a colorant. The colorant is not particularly limited, such as known pigments and magnetic materials. It is preferable that the toner particles contain a magnetic material as the colorant. Further, it is preferable that the colorant contains a magnetic material as the main component. This can impart rigidity to the entire toner, and the developability tends to increase. "Containing a magnetic material as the main component" means that the content ratio of the magnetic material in the colorant is 50% by mass to 100% by mass, preferably 80% by mass to 100% by mass, more preferably 90% by mass to 100% by mass.

[0033] Examples of the magnetic material include iron oxides such as magnetite, maghemite, and ferrite; metals such as iron, cobalt, and nickel; or alloys of these metals with metals such as aluminum, copper, magnesium, tin, zinc, beryllium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

[0034] Examples of the shape of the magnetic material include octahedron, hexahedron, spherical, needle-like, and flaky, and any of them can be used. Preferably, it is a polyhedron with 4 or more faces, and more preferably, it is a polyhedron structure with 8 or more faces.

[0035] The number average particle diameter (D1) of the primary particles of the magnetic material is preferably 100 nm or more and 350 nm, more preferably 100 nm or more and 300 nm or less, and even more preferably 110 nm or more and 300 nm or less.

[0036] The method for manufacturing magnetic iron oxide particles as the magnetic material is not particularly limited, and for example, it can be manufactured by the following method. An alkali such as sodium hydroxide equivalent to or more than the iron component is added to an aqueous solution of ferrous salt to prepare an aqueous solution containing ferrous hydroxide. While maintaining the pH of the prepared aqueous solution at pH 7 or more, air is blown in, and the oxidation reaction of ferrous hydroxide is carried out while heating the aqueous solution to 70 °C or more to first generate seed crystals that form the core of the magnetic iron oxide particles.

[0037] Next, an aqueous solution containing about 1 equivalent of ferrous sulfate is added based on the amount of alkali previously added to the slurry-like liquid containing the seed crystal. While maintaining the pH of the liquid at 5 to 10, air is blown in to proceed with the reaction of ferrous hydroxide, and magnetic iron oxide is grown with the seed crystal as the core. At this time, by selecting arbitrary pH, reaction temperature, and stirring conditions, and adding additives as necessary, it is possible to control the shape and magnetic properties of the magnetic iron oxide particles. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but it is preferably not less than 5. The magnetic iron oxide particles thus obtained can be obtained by filtering, washing, and drying by a conventional method.

[0038] In addition, the content of the magnetic substance is preferably 50 parts by mass or more and 150 parts by mass or less, more preferably 60 parts by mass or more and 120 parts by mass or less, based on 100 parts by mass of the binder resin.

[0039] Also, when adjusting the ratio of the number average particle diameter of the internally added silica particles to the number average diameter of the magnetic substance, the above effects are more easily achieved. Specifically, the number average particle diameter D1 of the silica particles contained in the toner particles is preferably 2 times or more, more preferably 3 times or more, and even more preferably 5 times or more the number average particle diameter of the magnetic substance. Also, it is preferably 20 times or less, more preferably 15 times or less, and even more preferably 11 times or less.

[0040] The toner contains a binder resin. The binder resin is not particularly limited, and known materials such as vinyl resins and polyester resins can be used. Specifically, polystyrene, styrene-propylene copolymer, styrene-vinyltoluene Styrene copolymers such as styrene-acrylic acid methyl copolymer, styrene-acrylic acid ethyl copolymer, styrene-acrylic acid butyl copolymer, styrene-acrylic acid octyl copolymer, styrene-methacrylic acid methyl copolymer, styrene-methacrylic acid ethyl copolymer, styrene-methacrylic acid butyl copolymer, styrene-methacrylic acid octyl copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer, polyacrylic acid esters, polymethacrylic acid esters, polyvinyl acetate, etc. can be used, and these can be used alone or in combination of multiple types.

[0041] Examples of the polymerizable monomers of vinyl resins include the following. Styrene monomers such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene; acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; and other monomers such as acrylonitrile, methacrylonitrile, acrylamide. These monomers can be used alone or in mixture.

[0042] The binder resin is preferably an amorphous resin. As the binder resin, a styrene copolymer and a polyester resin are preferred in terms of development characteristics, fixability, etc. The polyester resin is preferably an amorphous polyester resin. The binder resin more preferably contains a styrene-acrylic resin. The styrene-acrylic resin is preferred from the viewpoint of suppressing development streaks after exposure to a heat cycle environment. The styrene-acrylic resin is preferably a copolymer of styrene and at least one selected from the group consisting of acrylic acid esters and methacrylic acid esters.

[0043] The amorphous polyester resin may be a conventional one composed of an alcohol component and an acid component, and examples of both components are given below. Examples of the dihydric alcohol component include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol, cyclohexanedimethanol, butenediol, octenediol, cyclohexenedimethanol, hydrogenated bisphenol A, or a bisphenol derivative represented by formula (A); a hydrogenated product of the compound represented by formula (A), a diol represented by formula (B), or a diol of a hydrogenated product of the compound of formula (B).

[0044] [ka] [In the formula, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x+y is 2 to 10.]

[0045] [ka]

[0046] Examples of the divalent acid component include benzenedicarboxylic acids or their anhydrides such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride; alkyldicarboxylic acids or their anhydrides such as succinic acid, adipic acid, sebacic acid, and azelaic acid; succinic acid or its anhydride substituted with an alkyl or alkenyl group having 6 to 18 carbon atoms; and unsaturated dicarboxylic acids or their anhydrides such as fumaric acid, maleic acid, citraconic acid, and itaconic acid. Furthermore, examples of the alcohol component having a trivalent or higher valence include glycerin, pentaerythritol, sorbitol, sorbitan, and oxyalkylene ethers of novolak-type phenol resins. Examples of the acid component having a trivalent or higher valence include trimellitic acid, pyromellitic acid, 1,2,3,4-butanetetracarboxylic acid, benzophenonetetracarboxylic acid, and their anhydrides.

[0047] A charge control agent may be added to the toner. As the charge control agent for negative charging, organometallic complex compounds and chelate compounds are effective, and examples include monoazo metal complex compounds; acetylacetone metal complex compounds; metal complex compounds of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids. Specific examples of commercially available products include Spilon Black TRH, T-77, T-95 (Hodogaya Chemical Co., Ltd.), and BONTRON (registered trademark) S-34, S-44, S-54, E-84, E-88, E-89 (Orient Chemical Industries).

[0048] The toner particles contain a crystalline material, and the crystalline material contains a compound having an ester group. The compound having an ester group refers to a compound having one or more ester groups in one molecule. Examples include ester waxes such as behenyl behenate and behenyl stearate, and crystalline polyesters that are condensates of diols and dicarboxylic acids.

[0049] From the perspective of low-temperature fixability, the melting point of the compound having an ester group is preferably 60 °C or higher, more preferably 63 °C or higher. Further, the melting point is preferably 150 °C or lower, more preferably 115 °C or lower, still more preferably 85 °C or lower, and even more preferably 80 °C or lower.

[0050] As the ester wax, known ones can be used. Specifically, natural waxes such as montan wax and its derivatives, carnauba wax, candelilla wax and their derivatives, and waxes mainly composed of fatty acid esters can be used. It is preferably at least one selected from the group consisting of fatty acid ester wax and carnauba wax, and more preferably at least one selected from the group consisting of monofunctional fatty acid ester wax. The "wax mainly composed of fatty acid ester" refers to a wax in which the content ratio of fatty acid ester is 50% by mass to 100% by mass, preferably 80% by mass to 100% by mass, and more preferably 90% by mass to 100% by mass.

[0051] The peak molecular weight of the ester wax is preferably 2000 or less, preferably 1500 or less, and more preferably 1000 or less. The lower limit is not particularly limited, but is preferably 200 or more, and more preferably 400 or more.

[0052] The compound having an ester group is preferably a wax mainly composed of fatty acid ester (hereinafter referred to as aliphatic ester wax). Preferred aliphatic ester waxes are listed below. The functionality indicates the number of ester groups contained in one molecule. For example, behenyl behenate is a monofunctional ester wax, and dipentaerythritol hexa behenate is a hexafunctional ester wax.

[0053] As the monofunctional aliphatic ester wax, condensates of monocarboxylic acids having 4 to 28 carbon atoms and monohydric alcohols having 4 to 28 carbon atoms can be used. For example, at least one selected from the group consisting of stearyl stearate, behenyl stearate, stearyl behenate, and behenyl behenate is preferable, and at least one selected from the group consisting of behenyl behenate and behenyl stearate is more preferable.

[0054] As the bifunctional aliphatic ester wax, condensates of dicarboxylic acids and monohydric alcohols or condensates of diols and monocarboxylic acids can be used. Examples of the dicarboxylic acid include adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, and dodecanedioic acid. Examples of the diol include 1,6 - hexanediol, 1,7 - heptanediol, 1,8 - octanediol, 1,9 - nonanediol, 1,10 - decanediol, 1,11 - undecanediol, and 1,12 - dodecanediol.

[0055] As the monohydric alcohol to be condensed with the dicarboxylic acid, aliphatic alcohols are preferable. Specifically, tetradecanol, pentadecanol, hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, docosanol, tricosanol, tetracosanol, pentacosanol, hexacosanol, octacosanol, etc. can be mentioned. Among them, docosanol is preferable from the viewpoints of fixing property and developability.

[0056] Examples of the monocarboxylic acid to be condensed with the diol include lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, tuberculostearic acid, arachidic acid, behenic acid, lignoceric acid, and cerotic acid. Among them, behenic acid is preferable from the viewpoints of fixing property and developability. Here, linear fatty acids and linear alcohols are exemplified, but those having a branched structure may also be used.

[0057] Ester waxes with three or more functional groups can also be used. Here, examples of aliphatic ester waxes with three or more functional groups will be given. Examples of trifunctional ester waxes include condensates of glycerin compounds and monofunctional aliphatic carboxylic acids. Examples of tetrafunctional ester waxes include condensates of pentaerythritol and monofunctional aliphatic carboxylic acids, and condensates of diglycerin and aliphatic carboxylic acids. Examples of pentafunctional ester waxes include condensates of triglycerin and monofunctional aliphatic carboxylic acids. Examples of hexafunctional ester waxes include condensates of dipentaerythritol and monofunctional aliphatic carboxylic acids, and condensates of tetraglycerin and monofunctional aliphatic carboxylic acids.

[0058] Next, the crystalline polyester will be specifically described. As long as it has a crystalline structure, the crystalline polyester can be selected without particular limitation. It is preferable to use a condensate of an aliphatic diol and an aliphatic dicarboxylic acid as the crystalline polyester because it is excellent in crystallization in the binder resin and plasticizing ability during fixing. It is preferable that the aliphatic diol and the aliphatic dicarboxylic acid have 4 to 16 carbon atoms because it is easy to balance the fixing property and the storage stability.

[0059] The weight average molecular weight of the crystalline polyester is preferably 10,000 to 50,000 or less, more preferably 10,000 to 40,000 or less.

[0060] As the crystalline polyester, those produced by known synthesis methods can be used. For example, it can be obtained by subjecting a dicarboxylic acid component and a diol component to an esterification reaction or a transesterification reaction, and then performing a polycondensation reaction under reduced pressure or by introducing nitrogen gas according to a conventional method.

[0061] In the esterification or transesterification reaction, ordinary esterification catalysts or transesterification catalysts such as sulfuric acid, tertiary butyl titanate, dibutyltin oxide, manganese acetate, magnesium acetate, etc. can be used as necessary. Regarding polymerization, ordinary polymerization catalysts, for example, known ones such as tertiary butyl titanate, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, germanium dioxide, etc. can be used. The polymerization temperature and the amount of catalyst are not particularly limited and can be arbitrarily selected as necessary.

[0062] In the toner, the content of the compound having an ester group is preferably 1.0 part by mass or more and 40.0 parts by mass or less, more preferably 3.0 parts by mass or more and 35.0 parts by mass or less, still more preferably 3.0 parts by mass or more and 20.0 parts by mass or less, and even more preferably 5.0 parts by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the binder resin.

[0063] In the toner, for improving the fixability, a crystalline material such as a hydrocarbon wax may be further blended as necessary. As the release agent, all known release agents can be used. Specifically, petroleum waxes such as paraffin wax, microcrystalline wax, petrolactam and their derivatives, hydrocarbon waxes and their derivatives by the Fischer-Tropsch method, polyolefin waxes such as polyethylene and polypropylene and their derivatives, etc.

[0064] The toner may contain toner particles and an external additive on the surface of the toner particles. Examples of the external additive include known ones. Examples of the external additive include metal oxide fine particles (inorganic fine particles) such as silica fine particles, alumina fine particles, titania fine particles, zinc oxide fine particles, strontium titanate fine particles, cerium oxide fine particles, and calcium carbonate fine particles.

[0065] In the toner, other additives can be further used within a range that does not substantially have an adverse effect, such as lubricant powders such as fluororesin powder, zinc stearate powder, and polyvinylidene fluoride powder; abrasive agents such as cerium oxide powder, silicon carbide powder, and strontium titanate powder; fluidity imparting agents such as titanium oxide powder and aluminum oxide powder; anti-caking agents; or a small amount of organic fine particles and inorganic fine particles with opposite polarity can also be used as a developing property improver. It is also possible to use these additives after hydrophobizing the surface thereof.

[0066] The weight average particle diameter (D4) of the toner is preferably 3.0 μm or more and 12.0 μm or less, more preferably 4.0 μm or more and 10.0 μm or less. When the weight average particle diameter (D4) is within the above range, good fluidity can be obtained and development can be faithfully performed on the latent image.

[0067] The method for manufacturing the toner is not particularly limited, and a known manufacturing method can be adopted. Examples of the method for manufacturing the toner include a pulverization method, a polymerization method, such as a dispersion polymerization method, an association aggregation method, a dissolution suspension method, a suspension polymerization method, and an emulsion aggregation method. Hereinafter, a pulverization method for manufacturing a toner through a melt kneading step and a pulverization step will be specifically exemplified, but it is not limited thereto.

[0068] For example, a binder resin, a crystalline material, and silica particles, and, if necessary, a colorant, a release agent, a charge control agent, and other additives are sufficiently mixed by a mixer such as a Henschel mixer or a ball mill (mixing step). The obtained mixture is melt kneaded using a heat kneader such as a twin-screw kneading extruder, a heating roll, a kneader, or an extruder (melt kneading step).

[0069] After cooling and solidifying the obtained melt kneaded product, it is pulverized using a pulverizer (pulverization step) and classified using a classifier (classification step) to obtain toner particles. The toner particles may be used as the toner as they are. If necessary, the toner particles and an external additive may be mixed by a mixer such as a Henschel mixer to obtain a toner.

[0070] Examples of the mixer include the following: FM mixer (manufactured by Nippon Coke & Engineering Co., Ltd.); Super mixer (manufactured by Kawata); Ribocone (manufactured by Okawara Seisakusho); Nauta mixer, Turbulizer, Cyclomix (manufactured by Hosokawa Micron Corporation); Spiral Pin Mixer (manufactured by Taiheiyo Kiko Co., Ltd.); Lodige mixer (manufactured by Matsubo).

[0071] Examples of the heat kneader include the following: KRC kneader (manufactured by Kurimoto Iron Works Co., Ltd.); Buss co-kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine Co., Ltd.); TEX twin-screw kneader (manufactured by Nippon Steel Corporation); PCM kneader (manufactured by Ikegai Iron Works Co., Ltd.); Three-roll mill, Mixing roll mill, Kneader (manufactured by Inoue Seisakusho); Needex (manufactured by Mitsui Mining Co., Ltd.); MS type pressure kneader, Nidaluder (manufactured by Moriyama Seisakusho); Banbury mixer (manufactured by Kobe Steel, Ltd.).

[0072] Examples of the pulverizer include the following: Counter jet mill, Micron jet, Inomizer (manufactured by Hosokawa Micron Corporation); IDS type mill, PJM jet pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); Cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); Ulmax (manufactured by Nippon Catalytic Chemical Industries, Ltd.); SK jet or mill (manufactured by Seishin Enterprise Co., Ltd.); Cryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo mill (manufactured by Turbo Industry Co., Ltd.); Super rotor (manufactured by Nisshin Engineering Co., Ltd.).

[0073] Examples of the classifier include the following: Classier, Micron classifer, Spedic classifier (manufactured by Seishin Enterprise Co., Ltd.); Turbo classifier (manufactured by Nisshin Engineering Co., Ltd.); Micron separator, Turbo Preplex (ATP), TSP separator (manufactured by Hosokawa Micron Corporation); Elbow jet (manufactured by Nippon Steel Mining Co., Ltd.), Dispersion separator (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); YM micro cut (manufactured by Yaskawa Shoji Co., Ltd.).

[0074] In addition, the following screening devices may be used to separate coarse particles: Ultrasonic (manufactured by Koyo Sangyo Co., Ltd.); Resonancy, Gyro Shifter (manufactured by Tokuju Kousakusho Co., Ltd.); Vibra Sonic System (manufactured by Dalton Co., Ltd.); Sonic Cleaner (manufactured by Shin-Tokyo Kogyo Co., Ltd.); Turbo Screener (manufactured by Turbo Kogyo Co., Ltd.); Micro Shifter (manufactured by Makino Sangyo Co., Ltd.); Circular Vibrating Screen.

[0075] Next, the measurement methods for each physical property will be described. <Measurement Method for Number-Average Particle Size of Internally Added Silica Particles and Magnetic Bodies> Internally added silica particles refer to the silica particles contained in toner particles before undergoing the external addition process. Whether it is silica particles can be confirmed by an energy dispersive X-ray analyzer (EDX). The number-average particle size of the internally added silica particles means the number-average value of the major axis lengths of the internally added silica particles based on the cross-sectional image of the toner particles observed with a transmission electron microscope (TEM). The cross-sectional image of the toner particles by transmission electron microscope (TEM) is prepared as follows.

[0076] Using an osmium plasma coater (filgen, OPC80T), a protective film and apply an Os film (5 nm) and a naphthalene film (20 nm) to the toner, embed it with a photocurable resin D800 (JEOL Ltd.), and then use an ultrasonic ultramicrotome (Leica, UC7) to prepare a cross-section of the toner particles with a film thickness of 60 nm (or 70 nm) at a cutting speed of 1 mm / s. Perform STEM observation on the obtained cross-section using the STEM function of a TEM (JEOL, JEM2800). The probe size of the STEM is 1 nm, and the image size is acquired at 1024×1024 pixels. Among the cross-sections of the toner particles, select the cross-section with a diameter that is 0.9 times to 1.1 times the weight-average particle size.

[0077] For the obtained image, the major axis of the internally added silica particles is determined using the image processing software "Image-Pro Plus ver.4.0 (manufactured by Media Cybernetics)". In calculating the number average diameter, the cross-sections of 100 toner particles are observed. The presence or absence of internally added silica particles with a size of 400 nm or more and 3000 nm or less is discriminated, and the obtained number average value is defined as the number average particle diameter D1 of the internally added silica particles.

[0078] Furthermore, in the image where the silica particles are observed, the angle of the end portion is calculated using the image processing software "Image-Pro Plus ver.4.0 (manufactured by Media Cybernetics)". Specifically, as shown in Fig. 1, the end portion of the silica particle 1 is detected by the Edge Detector of the above software. A circle with a radius of 200 nm centered on the detected end portion (the circle indicated by 2 in the figure) is drawn. Two straight lines are drawn connecting the intersection of the circle and the silica particle contour and the end portion, and lines with a width of 50 nm centered on the straight lines (the two lines extending from the center of the circle 2 to the contour of the circle 2 in the figure) are drawn. What shows the contour line of the silica particle 1 included in the two lines with a width of 50 nm is the "enlarged view of the line portion" in the figure. Here, if the contour line of the silica particle does not fit within a width of 50 nm, the end portion is not analyzed. The angle (3 in the figure) formed by the two lines with a width of 50 nm is analyzed by the above software, and if the angle is 90 degrees or less, it is determined that the silica particle has a pointed portion. The cross-sections of 100 toner particles are observed, and the number of pointed portions per silica particle, the number of silica particles having pointed portions per cross-section of the toner particle, and the percentage of toner particles containing silica particles having pointed portions among the number of observed cross-sections of the toner particles are calculated.

[0079] Regarding the number average particle diameter of the magnetic substance, similar to the case of the above silica particles, in the cross-section observation of 100 toner particles, the number average particle diameter of the magnetic substance is obtained by taking the number average value of the major axis of the magnetic substance. The discrimination of the magnetic substance can also be performed with an energy dispersive X-ray analyzer (EDX).

[0080] <Method for Measuring Melting Point of Compound Having Ester Group> The melting point of a compound having an ester group as a crystalline material is measured in accordance with ASTM D3418-82 using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments). For the temperature correction of the apparatus detection part, the melting points of indium and zinc are used, and for the correction of the calorific value, the heat of fusion of indium is used.

[0081] Specifically, 10 mg of a compound having an ester group is precisely weighed, placed in an aluminum pan, and an empty aluminum pan is used as a reference. Measurement is carried out at a heating rate of 10 °C / min within a measurement temperature range of 30 to 200 °C. In the measurement, the temperature is first raised to 200 °C, then cooled to 30 °C at 10 °C / min, and then heated again at 10 °C / min. The peak temperature of the endothermic peak is determined from the DSC curve in the temperature range of 30 to 200 °C during this second heating process. The peak temperature of the above endothermic peak is taken as the melting point.

[0082] <Measurement of Weight Average Particle Size (D4) and Number Average Particle Size (D1) of Toner (Particles)> The weight average particle size (D4) and number average particle size (D1) of toner (particles) are measured and calculated using a precision particle size distribution measuring device "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter) equipped with a 100 μm aperture tube and the dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) attached for setting measurement conditions and analyzing measurement data, with an effective number of measurement channels of 25,000 channels. The electrolytic aqueous solution used for measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of about 1% by mass. For example, "ISOTON II" (manufactured by Beckman Coulter) can be used. Before measurement and analysis, the settings of the dedicated software are made as follows.

[0083] On the "Standard Measurement Method (SOM) Change Screen" of the dedicated software, set the total count number of the control mode to 50,000 particles, set the number of measurements to 1 time, and set the Kd value to the value obtained using "Standard Particle 10.0μm" (manufactured by Beckman Coulter). Press the measurement button for the threshold / noise level to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the flash of the aperture tube after measurement. On the "Conversion Setting Screen from Pulse to Particle Size" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range to 2 μm or more and 60 μm or less.

[0084] The specific measurement method is as follows. (1) Pour about 200 ml of the electrolytic aqueous solution into a 250 ml round-bottom glass beaker dedicated to Multisizer 3, set it on the sample stand, and stir with a stirrer rod counterclockwise at 24 revolutions per second. Then, use the "Flash of Aperture Tube" function of the dedicated software to remove dirt and bubbles in the aperture tube. (2) Pour about 30 ml of the electrolytic aqueous solution into a 100 ml flat-bottom glass beaker, and add about 0.3 ml of a dilution obtained by diluting "Contaminon N" (a 10% by mass aqueous solution of a neutral detergent for precision measuring instrument cleaning with pH 7 composed of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) 3 times by mass with ion-exchanged water as a dispersant. (3) Put a predetermined amount of ion-exchanged water into the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and built-in two oscillators with an oscillation frequency of 50 kHz and a phase shift of 180 degrees, and add about 2 ml of the Contaminon N to this water tank. (4) Set the beaker in (2) in the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height position of the beaker so that the resonance state of the liquid level of the electrolytic aqueous solution in the beaker is maximized. (5) With the ultrasonic wave irradiating the electrolytic aqueous solution in the beaker of (4), add about 10 mg of toner (particles) little by little to the electrolytic aqueous solution and disperse it. Then, continue the ultrasonic dispersion treatment for another 60 seconds. In ultrasonic dispersion, appropriately adjust so that the water temperature in the water tank is 10°C or higher and 40°C or lower. (6) Using a pipette, drop the electrolytic aqueous solution of (5) in which the toner (particles) is dispersed into the round-bottom beaker of (1) installed in the sample stand, and adjust so that the measured concentration becomes about 5%. Then, perform the measurement until the number of measured particles reaches 50,000. (7) Analyze the measurement data with the dedicated software attached to the device to calculate the weight average particle size (D4). When set to graph / volume% in the dedicated software, the "average diameter" on the "analysis / volume statistical value (arithmetic mean)" screen is the weight average particle size (D4), and when set to graph / count% in the dedicated software, the "average diameter" on the "analysis / count statistical value (arithmetic mean)" screen is the number average particle size (D1).

[0085] <Composition Analysis of Binder Resin> · Separation Method of Binder Resin Dissolve 100 mg of toner in 3 ml of chloroform. Then, remove the insoluble matter by suction filtration with a syringe equipped with a sample treatment filter (pore size 0.2 μm or more and 0.5 μm or less, for example, using Microlidisk H-25-2 (manufactured by Tosoh Corporation), etc.). Introduce the soluble matter into preparative HPLC (device: LC-9130 NEXT preparative column [60 cm] manufactured by Japan Analytical Industry Co., Ltd., exclusion limit: 20,000, two connected with 70,000) and send the chloroform eluent. When a peak can be confirmed by the display of the obtained chromatograph, fractionate the retention time with a monodisperse polystyrene standard sample so that the molecular weight is 2,000 or more. Dry and solidify the solution of the obtained fraction to obtain the binder resin.

[0086] · Identification of Components and Measurement of Weight Ratio of Binder Resin by Nuclear Magnetic Resonance Spectroscopy (NMR) Add 1 mL of deuterated chloroform to 20 mg of toner and measure the NMR spectrum of the protons of the dissolved binder resin. From the obtained NMR spectrum, the molar ratio and mass ratio of each monomer can be calculated, and the content of the constituent monomer units of the binder resin such as styrene acrylic resin can be determined. For example, in the case of a styrene acrylic copolymer, the composition ratio and mass ratio can be calculated based on the peak around 6.5 ppm derived from the styrene monomer and the peak around 3.5 - 4.0 ppm derived from the acrylic monomer. In addition, in the case of a copolymer of polyester resin and styrene acrylic resin, the molar ratio and weight ratio are also calculated together from the peaks derived from each monomer constituting the polyester resin and the peaks derived from the styrene acrylic copolymer, and the content of the monomer units of the polyester resin is determined. NMR apparatus: JEOL RESONANCE ECX500 Observed nucleus: Proton Measurement mode: Single pulse Reference peak: TMS

[0087] <Measurement of weight average molecular weight Mw, number average molecular weight Mn, and peak molecular weight> The molecular weight distribution (weight average molecular weight Mw, number average molecular weight Mn, peak molecular weight) of crystalline materials and resins, etc., is measured by gel permeation chromatography (GPC) as follows. First, dissolve the sample in tetrahydrofuran (THF) over 24 hours at room temperature. Then, filter the obtained solution through a solvent-resistant membrane filter "Micron Disc" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. Note that the sample solution is adjusted so that the concentration of the components soluble in THF is 0.8 mass%. Using this sample solution, the measurement is carried out under the following conditions. Apparatus: HLC8120GPC (Detector: RI) (manufactured by Tosoh Corporation) · Column: Seven columns of Shodex KF-801, 802, 803, 804, 805, 806, 807 (manufactured by Showa Denko KK) Eluent: Tetrahydrofuran (THF) · Flow rate: 1.0 ml / min · Oven temperature: 40.0 °C ·Sample injection volume: 0.10 ml When calculating the molecular weight of the sample, a molecular weight calibration curve prepared using a standard polystyrene resin (for example, 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, A-500", manufactured by Tosoh Corporation) is used.

Example

[0088] Hereinafter, the present invention will be described more specifically with reference to production examples and examples, but these do not limit the present invention in any way. All parts in the following formulations represent parts by mass.

[0089] <Production Example of Silica Particles 1>[ A mixed gas with a volume ratio of argon to oxygen of 3:1 was introduced into the reaction vessel and replaced with air. In this reaction vessel, oxygen gas was supplied at 40 (m 3 / hr) and hydrogen gas was supplied at 20 (m 3 / hr), and a combustion flame composed of oxygen - hydrogen was formed using an ignition device. Then, the raw material metal silicon powder was introduced into this combustion flame with a hydrogen carrier gas at a pressure of 147 kPa (1.5 kg / cm 2 ) to form a dust cloud. This dust cloud was ignited by the combustion flame to cause an oxidation reaction by dust explosion. After the oxidation reaction, the inside of the reaction vessel was cooled to obtain silica powder with a number average particle size of 2.67 μm. This silica powder was pulverized using a pulverizer (manufactured by Hosokawa Micron Corporation) to obtain silica particles 1 with a number average particle size of 1520 nm.

[0090] <Production Examples of Silica Particles 2 - 4, 6, 8>[ In the production example of silica particles 1, while adjusting the pulverization intensity of the pulverizer, pulverization was carried out to obtain silica particles 2 - 4, 6, 8.

[0091] <Production Examples of Silica Particles 5, 7, 9>[ A mixed gas with a volume ratio of argon to oxygen of 3:1 was introduced into the reaction vessel and replaced with air. In this reaction vessel, oxygen gas was supplied at 40 (m3 / hr) and hydrogen gas were supplied at 20 (m 3 / hr), and a combustion flame composed of oxygen - hydrogen was formed using an ignition device. Next, hydrogen carrier gas at a pressure of 0.5 kg / cm 3 was introduced into this combustion flame, and the raw material metal silicon powder was fed to form a dust cloud. This dust cloud was ignited by the combustion flame to cause an oxidation reaction due to dust explosion. After the oxidation reaction, the inside of the reaction vessel was cooled to obtain silica powder with a number - average particle size of 3.44 μm. This silica powder was pulverized using a parabolizer while adjusting the pulverization strength to obtain silica particles 5, 7. Also, those without pulverization by the parabolizer were designated as silica particles 9.

[0092] The silica particles are shown in Table 1. As silica particles 10, silica particles RY200 manufactured by Nippon Aerosil Co., Ltd. were used.

Table 1

[0093] <Production Example of Magnetic Substance 1> Into an aqueous solution of ferrous sulfate, a caustic soda solution in an amount of 1.00 to 1.10 equivalents with respect to iron element, P2O5 in an amount of 0.15 mass% in terms of phosphorus element with respect to iron element, and SiO2 in an amount of 0.50 mass% in terms of silicon element with respect to iron element were mixed to prepare an aqueous solution containing ferrous hydroxide. The pH of the aqueous solution was adjusted to 8.0, and an oxidation reaction was carried out at 85 °C while blowing air to prepare a slurry liquid having seed crystals.

[0094] Next, an aqueous solution of ferrous sulfate was added to this slurry liquid so as to be 0.90 to 1.20 equivalents with respect to the initial alkali amount (sodium component of caustic soda). Then, the slurry liquid was maintained at pH 7.6, and the oxidation reaction was continued while blowing air to obtain a slurry liquid containing iron oxide. The generated magnetic iron oxide particles were filtered using a filter press, washed with a large amount of water, and then dried at 120 °C for 2 hours. The obtained particles were crushed to obtain Magnetic Substance 1 with a number - average particle size of 150 nm. Note that Magnetic Substance 1 was in an octahedral shape.

[0095] <Manufacturing Examples of Magnetic Bodies 2 to 4> In the manufacturing example of magnetic body 1, magnetic bodies 2 to 4 described in Table 2 were obtained by adjusting the oxidation reaction at 85°C and the holding time at pH 7.6. Note that magnetic bodies 2 to 4 had an octahedral shape.

Table 2

[0096] <Compound Having an Ester Group> In the examples described later, the materials in Table 3 were used as the compound having an ester group, which is a crystalline material.

Table 3

[0097] <Manufacturing Example of Toner 1> ·Binder resin A: 100.0 parts (Styrene acrylic resin with a mass ratio of styrene and n-butyl acrylate of 78:22; Mw = 8500, Tg = 58°C) ·Behenyl behenate (melting point 75°C): 7.0 parts ·Silica particles 1: 2.0 parts ·Iron complex of monoazo dye (manufactured by Hodogaya Chemical Co., Ltd., T-77): 2.0 parts ·Magnetic body 1: 100 parts Using a Henschel mixer (FM-75 type, manufactured by Mitsui Mining Co., Ltd.), the above materials were mixed at a rotation speed of 20 s -1 and a rotation time of 5 min, and then kneaded with a twin-screw kneader (PCM-30 type, manufactured by Ikegai Corporation) set at a temperature of 130°C. The obtained kneaded product was cooled to 25°C and roughly pulverized to 1 mm or less with a hammer mill to obtain a rough pulverized product. The obtained rough pulverized product was finely pulverized with a mechanical pulverizer (T -250, manufactured by Turbo Industry Co., Ltd.). Classification was performed using a multi-stage classifier utilizing the Coanda effect to obtain toner particles 1 with a weight-average particle diameter (D4) of 8.4 μm.

[0098] To 100 parts of the obtained toner particles, 1.5 parts of hydrophobic silica fine powder with a number average particle diameter of primary particles of 10 nm was mixed for 5 minutes under the condition of a rotation speed of 3000 rpm using a Henschel mixer (manufactured by Mitsui Mining) to obtain a toner mixture. Thereafter, coarse particles were removed using a 300-mesh (aperture 48 μm) sieve to obtain Toner 1. The weight average particle diameter of Toner 1 was 8.4 μm. The formulation and physical properties of Toner 1 are shown in Table 4.

[0099]

Table 4

[0100] <Production Examples of Toner 2 to 5> In the production example of Toner 1, Toner 2 to 5 were obtained in the same manner except that the materials described in Table 4 were used. The formulation and physical properties are shown in Table 4.

[0101] <Production Example of Toner 6> In the production example of Toner 5, Toner 6 was obtained in the same manner except that the binder resin A was changed to the following binder resin B. The formulation and physical properties are shown in Table 4. Binder resin B; composition (mol%) [polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane: terephthalic acid: trimellitic acid = 80:20:85:15], Mw = 152,000

[0102] <Production Examples of Toner 7 to 17> In the production example of Toner 6, Toner 7 to 17 were obtained in the same manner except that the materials described in Table 4 were used. The formulation and physical properties are shown in Table 4.

[0103] <Comparative Example> <Production Examples of Toner 18 to 22> In the production example of Toner 1, Toners 18 to 22 were obtained in the same manner except that the materials described in Table 4 were used. The formulations and physical properties are shown in Table 4. HNP-9 is paraffin wax (manufactured by Nippon Seiro Co., Ltd.). In addition, in the obtained Toners 1 to 22, the number average particle diameter of the silica particles observed with a transmission electron microscope was the same as that of the added silica particles.

[0104] <Evaluation of Rubbing Fixing Property> Regarding the HP LaserJet Enterprise M609dn, in consideration of the fixing property evaluation at high speed, the process speed was modified to 500 mm / sec, and the fixing temperature control was lowered by 25°C from the setting to evaluate the rubbing fixing property. The evaluation of the rubbing fixing property was carried out by outputting a solid black image in a normal temperature and humidity environment and evaluating it based on the degree of soiling of the silver paper (manufactured by Nikon Corporation) before and after rubbing. The paper used was OCE RED LABEL (basis weight: 80 g / m 2 ). For the fixed image, after rubbing 10 back and forth with a load of 100 g / cm 2 using silver paper (manufactured by Nikon Corporation), it was evaluated based on the density of the soiling of the silver paper. The soiling was evaluated by the numerical value of the density difference between before use and the soiled part using a Macbeth reflection densitometer (manufactured by Macbeth), and A to C were judged as good. The evaluation results are shown in Table 5. A: Density difference is 0 to 0.02 B: Density difference is 0.03 to 0.05 C: Density difference is 0.06 to 0.09 D: Density difference is 0.10 or more

[0105] <Evaluation of Storage Stability in High Temperature Environment> 10 g of toner was put into a 100 ml glass bottle and left in a constant temperature bath at 50°C for 24 hours. After that, the toner was sieved with a 400-mesh ultrasonic sieve for 1 minute, and the presence or absence of agglomerated toner was confirmed and evaluated according to the following criteria. The evaluation results are shown in Table 5. A: No lumps are visible. B: There are some lumps, but they break apart immediately when touched. C: There are lumps that do not break apart even when touched.

[0106] <Evaluation of Storage Stability in Heat Cycle Environment> The toner was placed in a resin cup and left under the conditions described in the following heat cycle environment. Then, three solid black images were continuously output in the same manner as the evaluation of rubbing and fixing properties. When a crystalline material having an ester group oozes out due to the heat cycle, the chargeability of the toner may change or the fluidity may decrease. As an index for observing the change in chargeability, the density unevenness in the solid black image was evaluated. The density unevenness is evaluated as the difference between the maximum value and the minimum value of the density in the solid black image, and the first one of the three solid black images was used. As an index related to fluidity, the development streaks were visually evaluated. Since the development streaks often decrease as the output continues, all three solid black images were observed and evaluated including whether they recover or not. The image density was measured using a Macbeth reflection densitometer (manufactured by Macbeth). The evaluation results are shown in Table 5.

[0107] [Heat Cycle Environment] The evaluation of the heat cycle environment was performed using a thermostatic chamber capable of controlling temperature and humidity. Note that the heat cycle is an evaluation method with a different perspective from the storage stability in the aforementioned high-temperature environment, assuming a case where the temperature and humidity change significantly and are repeated. The heat cycle environment was set to the following conditions. 1. After maintaining and leaving it in the following Environment A for 12 hours, it was changed from Environment A to Environment B over 2 hours. At that time, the temperature was controlled to vary linearly. 2. After maintaining it in Environment B for 2 hours, it was changed from Environment B to Environment A over 2 hours. The above controls 1 and 2 were repeated 40 times. The evaluation results are shown in Table 5. Environment A: Temperature 25°C, Humidity 50% Environment B: Temperature 50°C, Humidity 50%

[0108] [[ID=(29)]] [Index of Density Unevenness] A: Density difference is 0.02 or less B: Density difference is 0.03 - 0.04 C: Density difference is 0.05 - 0.06 D: The concentration difference is 0.07 to 0.08 E: The concentration difference is 0.09 or more [Index of developing streaks] A: No streaks in all images B: Slight streak-like density unevenness is observed in one image C: Slight streak-like density unevenness is observed in two out of three images D: Slight streak-like density unevenness is observed in all three images E: White streaks are observed in one or more images

[0109] <Examples 1 to 17, Comparative Examples 1 to 5> Toner 1 to 17 were used as Examples 1 to 17, and toner 18 to 22 were used as Comparative Examples 1 to 5 for the above evaluation. The results are shown in Table 5

[0110]

Table 5

Explanation of symbols

[0111] 1: Silica particles, 2: Circle, 3: Angle formed by two lines with a width of 50 nm

Claims

1. A toner having toner particles containing a binder resin, a crystalline material, and silica particles, wherein the number average particle diameter D1 of the silica particles is 400 nm or more and 3000 nm or less, the silica particles have pointed portions, in cross-sectional observation of the toner particles by a transmission electron microscope, (i) an average of 1.0 to 20.0 of the silica particles having the pointed portions are present per cross-section of the toner particles, (ii) the ratio of the number of cross-sections of the toner particles containing the silica particles having the pointed portions to the total number of observed cross-sections of the toner particles is 80% or more by number, the crystalline material contains a compound having an ester group, the toner particles contain a colorant, and the colorant contains a magnetic material as a main component. A toner characterized by this.

2. A toner having toner particles containing a binder resin, a crystalline material, and silica particles, wherein the number average particle diameter D1 of the silica particles is 400 nm or more and 3000 nm or less, the silica particles have pointed portions, in cross-sectional observation of the toner particles by a transmission electron microscope, (i) an average of 1.0 to 20.0 of the silica particles having the pointed portions are present per cross-section of the toner particles, (ii) the ratio of the number of cross-sections of the toner particles containing the silica particles having the pointed portions to the total number of observed cross-sections of the toner particles is 80% or more by number, the crystalline material contains a compound having an ester group, and the binder resin is a styrene acrylic resin. A toner characterized by this.

3. The toner according to claim 1, wherein the number average particle diameter D1 of the silica particles contained in the toner particles is 2 times or more and 20 times or less the number average particle diameter of the magnetic material.

4. The toner according to any one of claims 1 to 3, wherein the melting point of the compound having an ester group is 60°C or more and 150°C or less.

5. The toner according to any one of claims 1 to 4, wherein the compound having an ester group is an ester wax.

6. The toner according to any one of claims 1 to 5, wherein the content of the silica particles contained in the toner particles is 0.1 part by mass or more and 10.0 parts by mass or less with respect to 100 parts by mass of the binder resin.

7. The toner according to any one of claims 1 to 6, wherein the value of the mass ratio of the content of the compound having an ester group in the toner particles to the content of the silica particles contained in the toner particles is 1.0 to 20.

0.

8. In the cross-sectional observation of the toner by a transmission electron microscope, the ratio of the number of cross-sections of the toner particles containing the silica particles having the pointed portions to the number of cross-sections of the observed toner particles is 90% or more by number. The toner according to any one of claims 1 to 7.

9. The toner according to any one of claims 1 to 8, wherein the content of the compound having an ester group is 3.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the binder resin.

10. The number average particle diameter D1 of the silica particles is 410 nm or more and 2930 nm or less, In the cross-sectional observation of the toner particles by a transmission electron microscope, (i) The silica particles having the pointed portions are present in an average of 1.1 to 18.0 per one cross-section of the toner particles, (ii) The ratio of the toner particles containing the silica particles having the pointed portions to the number of cross-sections of the observed toner particles is 90% or more by number. The toner according to any one of claims 1 to 9.

Images