Toner

Abstract

The present invention relates to a toner. A toner includes toner particles, the toner particles comprising: a binder resin, non-magnetic inorganic oxide particles A, and magnetic iron oxide particles B, wherein the softening point of the chloroform-soluble component of the toner particles is 90° C. or less; the non-magnetic inorganic oxide particles A and the magnetic iron oxide particles B are internally added to the toner particles; the non-magnetic inorganic oxide particles A contain at least one element selected from the group consisting of Si, Mg, Al, Ti, and Sr as its main component; the ratio of inorganic oxide particles having a long diameter of a specific length is within a specific range; and the ratio of the number average particle diameter of the long diameter of the non-magnetic inorganic oxide particles A to the number average particle diameter of the long diameter of the magnetic iron oxide particles B is 5 to 30.

Description

Technical Field

[0001] The present disclosure relates to a toner used in a recording method utilizing, for example, an electrophotographic system or the like. Background Art

[0002] In recent years, image forming apparatuses such as copiers and printers have been increasing in terms of the diversification of intended applications and use environments, and demands have been made for higher speed, higher image quality, and higher stability. In the field of copiers and printers, machine miniaturization and enhanced energy saving have been progressing simultaneously, and the use of a magnetic single-component development system (which uses a magnetic toner that is advantageous in these considerations) is preferred. In addition, it is also necessary to adapt to special media encountered during various intended applications in printing and to flexibly respond to different needs.

[0003] The electrophotographic method is performed by the following steps: a charging step in which an electrostatic latent image bearing member (hereinafter referred to as a photosensitive member) is charged by a charging means; an exposure step in which the charged photosensitive member is exposed to form an electrostatic latent image; and a developing step in which the electrostatic latent image is developed with a toner to form a toner image. Image output is then performed by the following steps: a transfer step in which the toner image is transferred to a recording material with or without an intervening intermediate transfer member, and a fixing step in which the recording material bearing the toner image is fixed by applying heat and pressure by passing through a nip portion formed by a pressing member and a rotatable image heating member.

[0004] In order to cope with the demand for more energy conservation and to adapt to the very diverse expected applications in recent years, satisfactory fixing at low temperatures is necessary, and in addition, toners with properties suitable for individual use environments and purposes are required. In the case of monochrome printing, high frequency text printing occurs, and thus, low reflective matte quality is preferred for printed materials. In addition, the ability to adapt to the diversity of expected applications requires toners that can provide low gloss, high quality text printing even on smooth media such as posters, labels and films. This requires low temperature fixability to coexist with low gloss in a good balance.

[0005] To date, a large number of technologies for improving fixing performance have been disclosed. Within this field, there are many technologies related to plasticizers, the most prominent of which are hydrocarbon waxes, ester waxes and crystalline polyesters. Plasticizers achieve low-temperature fixing by promoting the melting of toner binders; however, due to melting and viscosity reduction at low temperatures, the surface of the printed image tends to become flat and smooth, and increased gloss tends to occur. Generally, when the low-temperature fixing property of the toner is improved, it is conducive to a greater viscosity reduction when heating is applied, whereby the surface of the printed image has a strong tendency to become flat and smooth and the gloss is improved. In order to make low-temperature fixing property coexist with low gloss, the technical problem is that this relationship between viscosity reduction and high gloss must be eliminated.

[0006] Hitherto, as related technologies, technologies for improving image quality by adding inorganic particles such as silica and adjusting toner viscosity are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 2011-039382, 2009-042386, and 2004-309517. Summary of the invention

[0007] Problem that the invention aims to solve

[0008] However, this technology is not sufficient to suppress the smoothing of the toner that exhibits reduced viscosity due to enhanced low-temperature fixability, and there is room for improvement, especially for a medium with a smooth printing surface, in order to produce coexistence of low-temperature fixability and low gloss. The present disclosure provides a toner that exhibits excellent low-temperature fixability and enables low-gloss matte printing even on a medium with a smooth printing surface.

[0009] Solutions for solving problems

[0010] The present disclosure relates to a toner, comprising toner particles, the toner particles comprising:

[0011] Binder resin,

[0012] non-magnetic inorganic oxide particles A, and

[0013] Magnetic iron oxide particles B, wherein

[0014] The softening point of the chloroform-soluble component of the toner particles is 90° C. or less;

[0015] Non-magnetic inorganic oxide particles A and magnetic iron oxide particles B are internally added to toner particles;

[0016] The non-magnetic inorganic oxide particles A contain at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr as a main component thereof;

[0017] Among the non-magnetic inorganic oxide particles A having a major diameter of 100 nm or more, the proportion of particles having a major diameter of 400 to 3,000 nm is 70% by number or more,

[0018] Among the magnetic iron oxide particles B, the proportion of particles having a major diameter of 50 to 350 nm is 70% by number or more; and

[0019] The ratio of the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A to the number average particle diameter of the major axis of the magnetic iron oxide particles B (non-magnetic inorganic oxide particles A / magnetic iron oxide particles B) is 5-30.

[0020] Effects of the Invention

[0021] Therefore, according to the present disclosure, it is possible to provide a toner which exhibits excellent low-temperature fixability and enables low-gloss matte printing even on a medium having a smooth printing surface.

[0022] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A graph providing a description of the softening point. DETAILED DESCRIPTION

[0024] Unless otherwise specifically stated, in the present disclosure, the expressions "from XX to YY" and "XX to YY" indicating a numerical range refer to a numerical range including the lower limit and the upper limit as endpoints. When a numerical range is provided in segments, the upper and lower limits of each numerical range can be arbitrarily combined.

[0025] The present disclosure relates to a toner, comprising toner particles, the toner particles comprising:

[0026] Binder resin,

[0027] non-magnetic inorganic oxide particles A, and

[0028] Magnetic iron oxide particles B, wherein

[0029] The softening point of the chloroform-soluble component of the toner particles is 90° C. or less;

[0030] Non-magnetic inorganic oxide particles A and magnetic iron oxide particles B are internally added to toner particles;

[0031] The non-magnetic inorganic oxide particles A contain at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr as a main component thereof;

[0032] Among the non-magnetic inorganic oxide particles A having a major diameter of 100 nm or more, the proportion of particles having a major diameter of 400 to 3,000 nm is 70% by number or more,

[0033] Among the magnetic iron oxide particles B, the proportion of particles having a major diameter of 50 to 350 nm is 70% by number or more; and

[0034] The ratio of the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A to the number average particle diameter of the major axis of the magnetic iron oxide particles B (non-magnetic inorganic oxide particles A / magnetic iron oxide particles B) is 5-30.

[0035] The present inventors have conducted intensive studies to achieve coexistence between the conflicting properties of fixing at a relatively low temperature accompanied by reduced viscosity of the toner and low gloss in monochrome printing.

[0036] For example, a binder resin having a low softening temperature may be introduced to achieve low temperature fixability of the toner. In addition, a crystalline material such as an ester compound may be introduced as a plasticizer to lower the softening point of the binder resin. Such low softening point toner particles will melt at a lower temperature and will exhibit excellent low temperature fixability due to the reduced viscosity.

[0037] However, the toner particles with reduced viscosity are highly responsive to pressure during fixing and are easy to spread, so they are easy to present a smooth surface during fixing. For rubber materials such as tires, it is known that fine particles such as carbon, etc., which are mixed as fillers, are used to increase viscosity and increase strength. Similarly, for toners, as described in the above-mentioned references, the viscosity of toners can be increased and their strength can be increased by introducing inorganic fine particles such as silicon dioxide. However, the fixing performance is impaired to the same extent. Therefore, a technical problem of achieving low-temperature fixing by reducing the softening point of toner particles and also reducing gloss to maintain monochrome printing quality has arisen.

[0038] The present inventors have found that both low-temperature fixing and gloss reduction can be achieved simultaneously by introducing two kinds of particles, namely, non-magnetic inorganic oxide particles having a large particle size and magnetic iron oxide particles which are smaller than the non-magnetic inorganic oxide particles but are relatively large nanoparticles.

[0039] The following describes the toner. The toner particles contain non-magnetic inorganic oxide particles A and magnetic iron oxide particles B. The non-magnetic inorganic oxide particles A contain at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr as its main component. The non-magnetic inorganic oxide particles A and magnetic iron oxide particles B are contained in the toner particles. Therefore, these particles are mixed with a binder during the toner production process, and when the toner is formed, they are in a state of being internally added to the inside of the toner particles. For example, the non-magnetic inorganic oxide particles A and the magnetic iron oxide particles B are dispersed in a binder resin. The internally added particles are preferably uniformly dispersed in the inside of the toner particles.

[0040] From the viewpoint of low-temperature fixability, the softening point of the chloroform-soluble component of the toner particles must be 90°C or lower. The softening point is preferably 55 to 85°C, more preferably 60 to 80°C.

[0041] The toner particles having a softening point of chloroform-soluble components of 90°C or less can be fixed at low temperatures during the fixing process, but the viscosity thereof is promoted to decrease, so that the fixed image exhibits high gloss. As a result, the ratio of the number average particle diameter of the major diameter (non-magnetic inorganic oxide particles A / magnetic iron oxide particles B) is 5 to 30. In addition, 70% by number or more of the non-magnetic inorganic oxide particles A having a major diameter of 100 nm or more are non-magnetic inorganic oxide particles A having a major diameter of 400 to 3,000 nm, and 70% by number or more of the magnetic iron oxide particles B are magnetic iron oxide particles B having a major diameter of 50 to 350 nm. By thus finding, it is possible to reduce the gloss of the fixed image while maintaining low-temperature fixability.

[0042] The inventor's idea for this will be described. For example, herein, particles having a particle size of less than about 50 nm are designated as small-diameter particles, particles having a particle size of about 50 nm or more and less than 400 nm are designated as medium-diameter particles, and particles having a particle size of 400 nm or more are referred to as large-diameter particles. As described above, during the fixing process, the toner undergoes a viscosity reduction and is easily spread and becomes flowable. The fluidity of the toner binder is inhibited by the presence of medium-diameter magnetic iron oxide particles in the toner. In addition, since large-diameter non-magnetic inorganic oxide particles are introduced into the toner, convex portions are formed in the fixed image starting from these large-diameter particles. Due to these convex portions, the image surface is in a rough state, and since the gloss is reduced due to light scattering, a matte texture can be obtained.

[0043] In order to exhibit a satisfactory viscosity suppression effect and not impair fixation, the proportion of particles having a major diameter of 50 to 350 nm in the magnetic iron oxide particles B is 70% by number or more. In addition, due to the effect of the residual magnetization from the magnetic iron oxide particles, the particles attract each other by a slight force, so fluidization can be effectively suppressed and fixation is not suppressed.

[0044] The proportion of particles having a major diameter of 50 to 350 nm in the magnetic iron oxide particles B is preferably 75 to 100 number%, more preferably 78 to 90 number%, and even more preferably 78 to 85 number%. The number% of particles having a major diameter of 50 to 350 nm in the magnetic iron oxide particles B can be controlled by adjusting the reaction conditions during the oxidation reaction in the production process of the iron oxide particles.

[0045] The non-magnetic inorganic oxide particles A are oxide particles having at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr as their main component, which substantially avoids damaging the electrophotographic performance. Here, "main component" refers to more than 50 atomic % of the atoms (excluding carbon and oxygen) contained in the inorganic oxide. Examples are at least one selected from the group consisting of SiO2, TiO2, MgO, Al2O3 and SrTiO3. Si-containing oxide particles are preferred. Among them, silica particles are more preferred. Silica particles do not damage electrophotographic performance, and the exposure of silica particles on the surface of the fixed image is suppressed by the intermolecular force between the resin and the surface hydroxyl group.

[0046] In order to achieve low gloss by forming convex portions in a fixed image while maintaining excellent low-temperature fixability, the proportion of particles having a major diameter of 400 to 3,000 nm in the non-magnetic inorganic oxide particles A of 100 nm or more is 70% by number or more.

[0047] Among the non-magnetic inorganic oxide particles A having a length of 100 nm or more, the proportion of particles having a major diameter of 400 to 3,000 nm is preferably 75 to 100 number%, more preferably 80 to 98 number%, and even more preferably 85 to 97 number%. The number% of particles having a major diameter of 400 nm to 3,000 nm can be controlled by adjusting the pulverization force and time in the particle pulverization step.

[0048] More preferably, in order to effectively form the convex portions, for the non-magnetic inorganic oxide particles A of 100 nm or more, the proportion of particles having a major diameter of 800 to 3,000 nm is preferably 70% by number or more. For the non-magnetic inorganic oxide particles A of 100 nm or more, the proportion of particles having a major diameter of 800 to 3,000 nm is preferably 75 to 100% by number, more preferably 80 to 95% by number, and even more preferably 85 to 92% by number.

[0049] The number % of particles having a major diameter of 800 to 3,000 nm can be controlled by adjusting the pulverization force and time in the particle pulverization step.

[0050] In addition, it is optimal for not impairing fixation and effectively forming convex portions to make the ratio of the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A to the number average particle diameter of the major axis of the magnetic iron oxide particles B (non-magnetic inorganic oxide particles A / magnetic iron oxide particles B) 5 to 30. The ratio is preferably 7 to 25, more preferably 8 to 20.

[0051] The number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A is preferably 400 to 3,000 nm, more preferably 800 to 2,800 nm, and even more preferably 1,200 to 2,600 nm. In addition, the number average particle diameter of the major axis of the magnetic iron oxide particles B is preferably 50 to 350 nm, more preferably 100 to 250 nm, and even more preferably 120 to 200 nm.

[0052] The softening point of the chloroform soluble component of the toner is a softening point measured using a thermomechanical analysis method (hereinafter referred to as TMA). The toner particles are obtained by removing the external additives on the toner through ultrasonic dispersion in an aqueous surfactant solution. The toner particles are dissolved in chloroform; the magnetic iron oxide particles are removed using a magnet; the chloroform insoluble matter is separated and removed using a centrifugal separator to obtain a chloroform solution. The chloroform is removed using an evaporator, and the chloroform is completely removed using a vacuum dryer to obtain the chloroform soluble matter in the toner.

[0053] Using 5 kN, 20 mg of the obtained chloroform-soluble material was converted into a The TMA measurement was performed using a Q400 from TA Instruments and using the conditions of 0.1 N and a heating rate of 10°C / min and The probe diameter was measured from 30°C to 150°C. Using the displacement curve data obtained, the softening point was taken as the intersection of the original baseline and the tangent line after displacement ( Figure 1 ). The softening point can be achieved by optimizing the molecular weight of the binder resin. In particular, the softening point can be lowered by introducing a large amount of low molecular weight components.

[0054] The means for removing external additives from the toner to produce toner particles is as follows. First, a dispersion medium is prepared by introducing 6 mL of Contaminon N (a 10% by mass aqueous solution of a pH 7 neutral detergent for washing precision instruments including a nonionic surfactant, an anionic surfactant and an organic builder, from Wako Pure Chemical Industries, Ltd.) into 100 mL of deionized water. 5 g of toner is added to the dispersion medium and dispersed for 5 minutes using an ultrasonic disperser (VS-150, As One Corporation). Afterwards, it is placed in a "KM Shaker" (model: V.SX) from Iwaki Industry Co., Ltd. and vibrated for 20 minutes at 350 strokes per minute. The toner particles are then collected and recovered using a neodymium magnet.

[0055] The particle size of the magnetic iron oxide particles B is measured as follows. The toner particles are obtained by removing the external additives on the toner as described above. The toner particles are dissolved in chloroform and the magnetic iron oxide particles are recovered using a magnet. The obtained magnetic iron oxide particles are heated at 800°C for 30 minutes using an electric furnace or TGA to decompose the residual organic components. The residual magnetic iron oxide particles are recovered and subjected to SEM observation and EDX analysis. Observation was performed at an observation magnification of 10,000X; EDX analysis confirmed that the particles contained iron and oxygen; and the long diameters of these particles were determined using image processing software. 200 particles were measured, the major diameter distribution was presented, and the number of particles present in the range of 50 to 350 nm was calculated. In addition, the number average particle size was calculated from the average value of 200 major diameters. The details are described later.

[0056] The particle size of the non-magnetic inorganic oxide particles A is measured as follows. The toner particles are obtained by removing the external additives on the toner as described above. The toner particles are dissolved in chloroform, and the magnetic iron oxide particles are removed using a magnet. The chloroform is removed with an evaporator, and the resulting solid material is heated at 800°C for 30 minutes with an electric furnace or TGA to decompose the residual organic components. The residual non-magnetic inorganic oxide particles A are recovered, and SEM observation and EDX analysis are performed. Observation was performed at an observation magnification of 10,000X; EDX analysis confirmed that the particles contained oxygen and at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr; and the major diameter of these particles was determined using image processing software. 50 particles were measured, and the major diameter distribution was presented, and the number % of particles existing in the range of 400 to 3,000nm and the number % of particles existing in the range of 800 to 3,000nm were calculated. In addition, the number average particle size was calculated from the average value of 50 major diameters. Details are described later.

[0057] There is no particular limitation on the production method of the non-magnetic inorganic oxide particles A, and a known method can be used. In particular, the production method of the silica particles includes the following: a gas phase method in which silicon metal or a silicon compound such as a silicon halide or a silane compound reacts in a gas phase; and a wet method in which a silane compound such as an alkoxysilane is subjected to a hydrolysis and condensation reaction. The production method of the silica particles can be selected without restriction. The gas phase oxidation method of directly oxidizing the powder raw material in an oxygen-hydrogen chemical flame is preferably used for the production of relatively large silica particles with a long diameter of 400 to 3,000 nm. The gas phase method can make the inside of the reaction vessel instantly reach above the melting point of the inorganic fine powder, and is a preferred method for obtaining large silica particles.

[0058] For example, silica particles of about 3,000 to 5,000 nm can be produced by the aforementioned gas phase oxidation method, and silica particles having a target size and shape can be obtained by pulverizing by a known method. For example, when a device with a high pulverizing capacity such as a pulverizer or a jet mill is used, it is easy to control the shape and particle size. In addition, the particle size distribution can also be appropriately adjusted using a known classifier.

[0059] Similarly, in the case of Mg, Al, Ti and Sr oxide particles, the production method can also be selected without limitation. For example, the oxides can be prepared by synthesis or purification from mineral raw materials, and the desired size and shape can be adjusted using pulverization and / or classification as needed.

[0060] The production method of the magnetic iron oxide particles B is not particularly limited, and the following method can be used. A base such as sodium hydroxide is added to an aqueous solution of a ferrous salt in an amount equivalent to or greater than the iron component to prepare an aqueous solution containing ferrous hydroxide. Air is blown into the prepared aqueous solution while maintaining the pH of the aqueous solution at 7 or greater, and the ferrous hydroxide is subjected to an oxidation reaction while the aqueous solution is heated to 70° C. or greater to preliminarily produce seed crystals, which will form the cores of the magnetic iron oxide particles.

[0061] Then, an aqueous solution containing about 1 equivalent of ferrous sulfate based on the previously added alkali is added to the slurry containing the seed crystals. While the pH of the liquid is maintained at 5 to 10 and air is blown in, the reaction of ferrous hydroxide is carried out so that the seed crystals are used as nuclei to grow magnetic iron oxide. At this time, the shape and magnetic properties of the magnetic iron oxide particles can be controlled by freely selecting pH, reaction temperature and stirring conditions and by adding additives as needed. As the oxidation reaction proceeds, the pH of the liquid shifts to the acidic side, but the pH of the liquid is preferably not reduced to less than 5. The magnetic iron oxide particles thus obtained are filtered, washed and dried by standard methods to obtain magnetic iron oxide particles.

[0062] Magnetic iron oxide particles can be exemplified by magnetite, hematite and ferrite; alloys thereof with metals such as silicon dioxide, aluminum, copper, magnesium, tin, zinc, beryllium, calcium, manganese, selenium, titanium, tungsten and vanadium; and mixtures of the foregoing.

[0063] The shape of the magnetic iron oxide particles may be octahedral, hexahedral, spherical, needle-like, flake-like, etc. Although any shape may be used, polyhedrons of tetrahedron or higher are preferred, and polyhedral structures of octahedron or higher are more preferred.

[0064] In order to optimally maintain the electrophotographic performance, the content of the magnetic iron oxide particles B is preferably 50 to 150 parts by mass, more preferably 60 to 120 parts by mass, relative to 100 parts by mass of the binder resin.

[0065] The content of the non-magnetic inorganic oxide particles A is preferably 0.1 to 5.0 parts by mass, more preferably 0.3 to 3.0 parts by mass, and even more preferably 0.5 to 2.5 parts by mass relative to 100 parts by mass of the binder resin.

[0066] In addition, it is preferable to adjust the residual magnetization (σr) as the magnetic property of the magnetic iron oxide particles B. The residual magnetization (σr) of the magnetic iron oxide particles B is preferably 2 to 24Am 2 / kg, more preferably 4 to 18Am 2 / kg, even more preferably 6 to 10Am 2 / kg. By adjusting σr downward, the toner undergoes thorough dispersion during development and has an influence on low-temperature fixing due to scattering. Adding Si can be used as a method for adjusting σr. The Si content in the magnetic iron oxide particles B is preferably 0.5 to 3 mass % to establish an optimal σr.

[0067] In addition, when the ratio between the content of the magnetic iron oxide particles B and the content of the non-magnetic inorganic oxide particles A is adjusted, low-temperature fixability and low gloss are easily achieved. Specifically, in transmission electron microscope observation of a cross section of the toner provided by slicing with a microtome, the ratio of the number of magnetic iron oxide particles B to the number of non-magnetic inorganic oxide particles A present in the cross section of the toner particles (magnetic iron oxide particles B / non-magnetic inorganic oxide particles A) is preferably 50 to 500. 100 to 400 is more preferred, and 150 to 300 is more preferred.

[0068] Furthermore, in transmission electron microscope observation of a cross section of the toner provided by slicing with a microtome, 0.5 to 5.0 non-magnetic inorganic oxide particles A are preferably present per 1 cross section of the toner. 0.7 to 3.0 are more preferred, and 0.8 to 1.5 are further more preferred. As a result, projections are effectively formed on the fixed image surface, so that low-temperature fixability and low gloss are even more easily achieved. In addition, by specifying 5.0 or less, it is easy to suppress fixed image defects due to detachment of projections.

[0069] Furthermore, in transmission electron microscope observation of a toner cross section provided by slicing with a microtome, the number of magnetic iron oxide particles B present per 1 toner cross section is preferably 100 to 500, more preferably 120 to 450, still more preferably 200 to 400.

[0070] Regarding the particle shape, the non-magnetic inorganic oxide particles A preferably have an irregular shape, while the magnetic iron oxide particles B are preferably spherical or have a shape approximately spherical, such as an octahedron or a hexahedron. Specifically, in transmission electron microscope observation of a cross section of a toner provided by slicing with a microtome, the shape factor SF1 of the non-magnetic inorganic oxide particles A is preferably 140 or more, and the shape factor SF1 of the magnetic iron oxide particles B is preferably 110 or less. The shape factor SF1 of the non-magnetic inorganic oxide particles A is more preferably 143 to 160, still more preferably 147 to 155. The shape factor SF1 of the magnetic iron oxide particles B is more preferably 100 to 109, still more preferably 102 to 107.

[0071] By controlling the shape in this way, it is easier to demonstrate the effect on low temperature fixability and low gloss. Therefore, for the magnetic iron oxide particles B present on or on the top of the non-magnetic inorganic oxide particles A, the non-magnetic inorganic oxide particles A are made to have an irregular shape for suppressing the magnetic iron oxide particles B from falling below the non-magnetic inorganic oxide particles A by catching them in the concave and convex parts during the fixing step, so that the resin-encapsulated protrusions can be formed in this way. This can provide suppression of the non-magnetic inorganic oxide particles A being exposed on the fixed image and suppression of fixing defects caused by peeling from the non-magnetic inorganic oxide particles A. The shape factor SF1 of the non-magnetic inorganic oxide particles A can be controlled by adjusting the pulverizing force and time in the particle pulverizing step. The shape factor SF1 of the magnetic iron oxide particles B can be controlled by adjusting the reaction conditions related to the oxidation reaction during the production of the iron oxide particles.

[0072] 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.

[0073] Specifically, the following can be used: polystyrene; styrene copolymers such as styrene-propylene copolymer, styrene-vinyl toluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-octyl methacrylate copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer and styrene-maleic acid ester copolymer; and polyacrylate, polymethacrylate, and polyvinyl acetate, etc. One of these can be used alone, or a plurality of them can be used in combination.

[0074] The binder resin preferably contains a non-crystalline polyester resin. This makes it relatively easy to design a material that supports low-temperature fixing, and also facilitates the interaction between the resin and the non-magnetic inorganic oxide particles A for the formation of protrusions on the image surface. In addition, the content of the non-crystalline polyester resin in the binder resin is preferably 50% by mass or more, more preferably 75 to 100% by mass, and even more preferably 90 to 100% by mass. This serves to further promote the above-mentioned effect.

[0075] A general non-crystalline polyester resin composed of an alcohol component and an acid component may be used as the non-crystalline polyester resin, and examples of the two components are provided below.

[0076] Examples of the diol 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, butene glycol, octenyl glycol, cyclohexenedimethanol, hydrogenated bisphenol A, bisphenol derivatives represented by formula (A), and hydrides of the compounds represented by formula (A), diols represented by formula (B), and hydrides of diols represented by formula (B).

[0077]

[0078] [In the formula, R is an ethylene group or a propylene group, x and y are each an integer greater than or equal to 1, and the average value of x+y is 2 to 10.]

[0079]

[0080] (wherein, R' is -CH2CH2-, )

[0081] The dibasic acid component can be exemplified by dicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride, and their anhydrides; alkyl dicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, and their anhydrides; succinic acid substituted with an alkyl group having 6 to 18 carbon atoms or with an alkenyl group having 6 to 18 carbon atoms, and their anhydrides; unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, and itaconic acid, and their anhydrides.

[0082] The trivalent or higher alcohol component may be exemplified by glycerin, pentaerythritol, sorbitol, sorbitan, and oxyalkylene ethers of novolac type phenol resins, and the trivalent or higher acid component may be exemplified by trimellitic acid, pyromellitic acid, 1,2,3,4-butanetetracarboxylic acid, benzophenonetetracarboxylic acid, and anhydrides thereof.

[0083] The softening point of the chloroform soluble matter of the toner particles can be controlled by the design of the binder resin. For example, the softening point can be controlled by adjusting the crosslinking density and / or controlling the molecular weight, but it is preferred to control the softening point using the content of the low molecular weight component. The low molecular weight component can be detected using the number average molecular weight (Mn) obtained by GPC measurement. In order to achieve a more thorough manifestation of low temperature fixability, the number average molecular weight (Mn) of the binder resin is preferably 1,000 to 5,000 and more preferably 1,300 to 3,000. In addition, the weight average molecular weight (Mw) of the binder resin is preferably 30,000 to 80,000 and more preferably 45,000 to 60,000.

[0084] Charge control agents can be added to toners. Organic metal complexes and chelate compounds are effective as negatively charged charge control agents, and examples include monoazo metal complexes, acetylacetone-metal complexes, and metal complexes of aromatic hydroxycarboxylic acids or aromatic dicarboxylic acids. Specific examples of commercial products are Spilon Black TRH, T-77 and T-95 (Hodogaya Chemical Co., Ltd.) and BONTRON (registered trademark) S-34, S-44, S-54, E-84, E-88 and E-89 (Orient Chemical Industries Co., Ltd.).

[0085] The toner may contain a crystalline material such as an ester wax and a hydrocarbon wax as a release agent. The crystalline material also acts as a plasticizer to help improve the fixing performance. Any known release agent may be used as the release agent.

[0086] The following are specific examples of the hydrocarbon wax: mineral oil-based waxes such as paraffin wax, microcrystalline wax, and vaseline, and derivatives thereof; hydrocarbon waxes provided by the Fischer-Tropsch process and derivatives thereof; and polyolefin waxes represented by polyethylene and polypropylene, and derivatives thereof.

[0087] Other examples are natural waxes such as montan wax and its derivatives, carnauba wax and candelilla wax and their derivatives, and ester waxes in which the main component is a fatty acid ester. In addition to monofunctional ester waxes, multifunctional ester waxes can also be used, the most prominent being difunctional esters, as well as tetrafunctional ester waxes and hexafunctional ester waxes.

[0088] Specific examples are diesters between saturated aliphatic dicarboxylic acids such as dibehenyl sebacate, distearyl dodecanedioate and distearyl octadecanediol and saturated aliphatic alcohols; diesters between saturated aliphatic diols such as nonanediol dibehenate and dodecanedioyl distearate and saturated fatty acids; triesters between triols such as glyceryl tribehenate and glyceryl tristearate and saturated fatty acids; and partial esters between triols such as glyceryl monobehenate and glyceryl dibehenate and saturated fatty acids.

[0089] The release agent is preferably at least one selected from the group consisting of hydrocarbon waxes and ester waxes. In order to optimally maintain low temperature fixability, the content of the release agent is preferably 3 to 20 parts by mass, and more preferably 5 to 15 parts by mass relative to 100 parts by mass of the binder resin.

[0090] The toner particles preferably contain a crystalline polyester resin as a plasticizer to improve the fixing performance. Crystalline polyester has high compatibility with the binder resin and quickly reduces the viscosity of the toner at low temperatures. From the perspective of crystallization in the binder resin and plasticizing properties during fixing, aliphatic diol / aliphatic dicarboxylic acid condensates are preferred for the crystalline polyester resin. The aliphatic diol and aliphatic dicarboxylic acid can be selected from those having 4 to 16 carbons. Doing so helps to achieve a balance between fixing performance and storage stability. The content of the crystalline polyester resin is preferably 1 to 10 parts by mass relative to 100 parts by mass of the binder resin, and more preferably 2 to 8 parts by mass.

[0091] A crystalline polyester resin produced by a known synthesis method can be used as the crystalline polyester resin. For example, it can be synthesized by performing an esterification reaction or an ester exchange reaction between a dicarboxylic acid component and a diol component, and then performing a polycondensation reaction under reduced pressure or under the introduction of nitrogen according to a common method.

[0092] In the esterification or transesterification reaction, a commonly used esterification catalyst or transesterification catalyst can be used as required, such as sulfuric acid, tert-butyl titanium butoxide, dibutyltin oxide, manganese acetate, and magnesium acetate, etc. Conventional known polymerization catalysts can be used during polymerization, such as tert-butyl titanium butoxide, dibutyltin oxide, tin acetate, zinc acetate, tin disulfide, antimony trioxide, and germanium dioxide, etc. There are no particular restrictions on the polymerization temperature and the amount of the catalyst, and they can be freely selected as required.

[0093] The toner may include toner particles and an external additive on the surface of the toner particles. The external additive may be a known external additive.

[0094] The external additive can be exemplified by 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.

[0095] Other additives may also be used in small amounts in the toner as developing performance enhancers within a range that does not substantially exert a negative effect, for example, lubricant powders such as fluorine resin powders, zinc stearate powders, and polyvinylidene fluoride powders; abrasives such as cerium oxide powders, silicon carbide powders, and strontium titanate powders; fluidity imparting agents such as titanium oxide powders and aluminum oxide powders; anti-caking agents; and reverse polarity organic fine powders and inorganic fine powders. These additives may also be used after the surfaces of the additives are hydrophobized.

[0096] The weight average particle diameter (D4) of the toner is preferably 3.0 to 12.0 μm, more preferably 4.0 to 10.0 μm. When the weight average particle diameter (D4) is within the above range, excellent fluidity and faithful latent image development can be obtained.

[0097] In addition, the ratio of the weight average particle diameter of the toner to the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A (toner / non-magnetic inorganic oxide particles A) is preferably 2 to 15, more preferably 2 to 10, and even more preferably 3 to 7. By adhering to this range, the formation of protrusions on the image surface during fixing can be more effectively achieved while keeping the influence on the properties affecting the electrophotographic properties such as the charging properties and the developing properties including the fixing properties to be minimized.

[0098] There is no particular limitation on the production method of the toner, and a known production method can be used. The production method of the toner can exemplify 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.

[0099] A pulverization method for producing a toner through a melt-kneading step and a pulverizing step is provided below as a specific example, but is not limited thereto or thereby.

[0100] For example, the binder resin, the magnetic iron oxide particles B and the non-magnetic inorganic oxide particles A, and optionally a colorant, a release agent, a charge control agent and other additives are fully mixed with a mixer such as a Henschel mixer or a ball mill (mixing step). The resulting mixture is melt-kneaded using a heating kneading machine such as a twin-screw kneading extruder, a hot roll, a kneader or an extruder (melt-kneading step).

[0101] After the obtained melt-kneaded material is cooled and solidified, it is pulverized by using a pulverizer (pulverization step) and classified by using a classifier (classification step) to obtain toner particles. The toner particles can be used as a toner as they are. The toner can be optionally obtained by mixing the toner particles with an external additive using a mixer such as a Henschel mixer.

[0102] The mixer can be exemplified by the following: FM mixer (Nippon Coke & Engineering Co., Ltd.); Supermixer (Kawata Mfg. Co., Ltd.); Ribocone (Okawara Corporation); Nauta mixer, Turbulizer and Cyclomix (Hosokawa Micron Corporation); Screw pin mixer (Pacific Machinery & Engineering Co., Ltd.); and Loedige mixer (Matsubo Corporation).

[0103] Heating kneaders can be exemplified by the following: KRC kneader (Kurimoto, Ltd.); Buss Ko-kneader (Buss Corp.); TEM extruder (Toshiba Machine Co., Ltd.); TEX twin-screw kneader (The Japan SteelWorks, Ltd.); PCM kneader (Ikegai Ironworks Corporation); three-roll mill, mixing roll mill and kneader (Inoue Manufacturing Co., Ltd.); Kneadex (Mitsui Mining Co., Ltd.); Model MS pressure kneader and Kneader-Ruder (Moriyama Mfg. Co., Ltd.); and Banbury mixer (Kobe Steel, Ltd.).

[0104] Examples of pulverizers include Counter jet mill, Micron Jet and Inomizer (Hosokawa Micron Corporation); IDS grinder and PJM jet mill (Nippon Pneumatic Mfg. Co., Ltd.); Cross jet mill (Kurimoto, Ltd.); Ulmax (Nisso Engineering Co., Ltd.); SK Jet-O-Mill (Seishin Enterprise Co., Ltd.); Kryptron (Kawasaki Heavy Industries, Ltd.); Turbo mill (Turbo Kogyo Co., Ltd.); and Super rotor (Nisshin Engineering Inc.).

[0105] The classifiers include, for example, Classiel, micron classifier, and special classifier (Seishin Enterprise Co., Ltd.); turbo classifier (Nisshin Engineering Inc.); micron separator, Turboplex (ATP), and TSP separator (Hosokawa Micron Corporation); Elbow Jet (Nittetsu Mining Co., Ltd.); dispersion separator (Nippon Pneumatic Mfg. Co., Ltd.); and YM Microcut (Yasukawa Shoji Co., Ltd.).

[0106] In addition, the following screening devices can be used to screen out coarse particles: Ultrasonic (Koei Sangyo Co., Ltd.), Rezona sieve and Gyro-Sifter (Tokuju Corporation), vibration system (Dalton Co., Ltd.), Soniclean (Sintokogio, Ltd.), turbine screener (Turbo Kogyo Co., Ltd.), micro sieve machine (Makino Mfg. Co., Ltd.), and circular vibrating screen.

[0107] The measurement methods of each property are described below.

[0108] <Method for measuring the softening point of chloroform-soluble substances>

[0109] The toner particles are obtained by removing the external additives on the toner using the above method. The toner particles are dissolved in chloroform; the magnetic iron oxide particles are removed using a magnet; and the insoluble matter is separated and removed using a centrifugal separator to obtain a chloroform solution of the toner particles. The chloroform is removed using an evaporator, and the chloroform is completely removed using a vacuum dryer to obtain a chloroform-soluble matter in the toner particles. 20 mg of the obtained chloroform-soluble matter is converted into a 5 kN particle with a diameter of 1. The TMA measurement was performed using a Q400 from TA Instruments, and the conditions of a heating rate of 0.1 N and 10 °C / min and a diameter of The probe was measured from 30°C to 150°C. Using the displacement curve data obtained, the softening point was taken as the intersection of the original baseline and the tangent line after displacement ( Figure 1 ).

[0110] <Composition Analysis and Particle Size Measurement of Magnetic Iron Oxide Particles B>

[0111] The particle size measurement of the magnetic iron oxide particles B is performed as follows.

[0112] The toner particles are obtained by removing the external additives on the toner as described above. The toner particles are dissolved in chloroform and the magnetic iron oxide particles are recovered using a magnet. The obtained iron oxide particles are heated at 800°C for 30 minutes with an electric furnace to decompose the residual organic components. The residual iron oxide particles are recovered and observed and analyzed by scanning electron microscopy (SEM) using an energy dispersive X-ray analyzer (EDX). The observation is performed at an observation magnification of 10,000; the particles are confirmed to contain iron and oxygen (may contain trace elements, such as trace amounts of Si) by EDX analysis; and the long diameter of these particles is determined using image processing software. 200 particles are measured, the major diameter distribution is presented, and the number of particles present in the range of 50 to 350 nm is calculated. In addition, the number average particle size is calculated from the average value of 200 particles.

[0113] SEM: JSM7800, JEOL Ltd.

[0114] EDX: Talos F200X Thermo Fisher Scientific Inc.

[0115] Image processing software: Image Analyzer (Luzex AP), Nireco Corporation

[0116] <Composition Analysis and Particle Size Measurement of Non-magnetic Inorganic Oxide Particles A>

[0117] The particle size of the non-magnetic inorganic oxide particles A is measured as follows.

[0118] The toner particles are obtained by removing the external additives on the toner as described above. The toner particles are dissolved in chloroform, and the magnetic iron oxide particles are removed using a magnet. The chloroform is removed with an evaporator, and the resulting solid material is heated at 800°C for 30 minutes with an electric furnace to decompose the residual organic components. The residual non-magnetic inorganic oxide particles A are recovered, and SEM observation and EDX analysis are performed. The observation is performed at an observation magnification of 10,000 times, and the particles are confirmed to contain oxygen and at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr by EDX analysis. In addition, when the peaks of these elements in the EDX spectrum exceed 50 atomic % relative to the sum of the peaks (excluding carbon and oxygen), these elements are confirmed as the main components. The major diameter of the confirmed particles is determined using image processing software.

[0119] 50 particles were measured to show the major diameter distribution, and the number % of particles with a major diameter of 400 nm to 3,000 nm and the number % of particles with a major diameter of 800 nm to 3,000 nm among particles with a major diameter of 100 nm or more were calculated. In addition, the number average particle size was calculated from the average value of 50 particles. The confirmation of the oxide of at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr was also qualitatively performed using an X-ray diffractometer (XRD).

[0120] SEM:JSM7800,JEOL Ltd.

[0121] EDX: Talos F200X Thermo Fisher Scientific Inc.

[0122] Image processing software: Image Analyzer (Luzex AP), Nireco Corporation

[0123] XRD: RINT-TTR III, Rigaku Corporation

[0124] <Method for measuring the number and shape factor of non-magnetic inorganic oxide particles A and magnetic iron oxide particles B>

[0125] At the time point before the external addition step is performed, the non-magnetic inorganic oxide particles A and the magnetic iron oxide particles B are internally added particles introduced into the toner particles. The externally added particles can be removed by the above method. The number of non-magnetic inorganic oxide particles A and the number of magnetic iron oxide particles B represent the number calculated based on the image of the cross section of the toner particles observed with a transmission electron microscope (TEM), and the calculation of the shape factor is also performed based on the image. The image of the cross section of the toner particles obtained with a transmission electron microscope (TEM) is prepared as follows.

[0126] An Os film (5 nm) and a naphthalene film (20 nm) were formed as protective films on the toner using an osmium plasma coater (OPC80T, Filgen, Inc.) After embedding with a D800 photocurable resin (JEOL Ltd.), a toner particle cross section with a film thickness of 60 nm (or 70 nm) was prepared using an ultrasonic ultramicrotome (UC7, Leica) at a slicing rate of 1 mm / s.

[0127] The obtained cross section was subjected to STEM observation using the STEM function of TEM (JEM 2800, JEOL Ltd.). Acquisition was performed at a STEM probe size of 1 nm and an image size of 1024×1024 pixels. Among the toner particle cross sections, the cross sections with a diameter of 0.9X to 1.1X the weight average particle diameter were selected.

[0128] The obtained image was analyzed by inputting into image processing software in an image analyzer (Luzex AP) from Nireco Corporation, and the number and shape factor of nonmagnetic inorganic oxide particles A and magnetic iron oxide particles B were calculated. The shape factor SF1 is a value obtained by calculation using the following formula (1).

[0129] SF1=(L 2 / A)×(π / 4)×100(1)

[0130] Wherein, L represents the absolute maximum length of the particle (the length of the circumscribed circle), P represents the perimeter of the particle, and A represents the projected area of ​​the particle.

[0131] The number and shape factor were calculated by observing and analyzing the cross-sections of 100 toner particles. In each case, the arithmetic mean value was used for the shape factor, the number of non-magnetic inorganic oxide particles A per toner, and the number of magnetic iron oxide particles B per toner. EDX analysis can be used to distinguish between non-magnetic inorganic oxide particles A and magnetic iron oxide particles B.

[0132] <Measurement of Weight Average Particle Diameter (D4) and Number Average Particle Diameter (D1) of Toner (Particles)>

[0133] The weight average particle diameter (D4) and number average particle diameter (D1) of the toner (particles) are determined by performing measurement in 25,000 effective measurement channels using a precision particle size distribution analysis instrument "Coulter Counter Multisizer 3" (registered trademark, Beckman Coulter, Inc.) operated based on the pore resistance method and equipped with a 100 μm aperture tube and using attached dedicated software for setting measurement conditions and analyzing measurement data, i.e., "Beckman Coulter Multisizer 3 Version 3.51" (Beckman Coulter, Inc.) and performing analysis of the measurement data.

[0134] The electrolyte aqueous solution used for measurement is prepared by dissolving special grade sodium chloride in ion exchange water to obtain a concentration of about 1 mass %, and for example, "ISOTON II" (Beckman Coulter, Inc.) can be used.

[0135] Prior to measurement and analysis, the dedicated software was set as follows.

[0136] In the "Change Standard Operating Method (SOM)" screen of the dedicated software, the total count of the control mode was set to 50,000 particles; the number of measurements was set to 1; and the Kd value was set to the value obtained using "Standard Particles 10.0 μm" (Beckman Coulter, Inc.). The threshold and noise level were automatically set by pressing the Threshold / Noise Level Measurement button. In addition, the current was set to 1600 μA; the gain was set to 2; the electrolyte solution was set to ISOTON II; and the rinse port tube after measurement was checked.

[0137] In the "Pulse to Size Conversion Settings" screen of the dedicated software, set the element spacing to logarithmic size; set the size elements to 256 size elements; and set the size range to 2 μm to 60 μm.

[0138] The specific measurement process is as follows.

[0139] (1) About 200 ml of the above electrolyte aqueous solution was introduced into a 250 mL round-bottom glass beaker dedicated to Multisizer 3, and the beaker was set on the sample stage and stirred counterclockwise with a stirring rod at 24 revolutions per second. Dirt and bubbles in the nozzle were preliminarily removed by the "swept nozzle flushing" function of the dedicated software.

[0140] (2) About 30 mL of the aqueous electrolyte solution was introduced into a 100 mL flat-bottom glass beaker, and about 0.3 mL of a dilution prepared by diluting "Contaminon N" (a 10% by mass aqueous solution of a pH 7 neutral detergent including a nonionic surfactant, an anionic surfactant and an organic builder for washing precision instruments, from Wako Pure Chemical Industries, Ltd.) three times by mass with deionized water was added thereto as a dispersant.

[0141] (3) A predetermined amount of deionized water was introduced into a water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora 150" (Nikkaki Bios Co., Ltd.) having a power output of 120 W and equipped with two oscillators (oscillation frequency = 50 kHz) set 180 degrees apart in phase, and about 2 ml of Contaminon N was added to the water tank.

[0142] (4) The beaker in (2) is placed in the beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is started. The vertical position of the beaker is adjusted so that the resonance state of the liquid surface of the aqueous electrolyte solution in the beaker is maximized.

[0143] (5) While irradiating the electrolyte aqueous solution in the beaker set according to (4) above with ultrasonic waves, about 10 mg of the toner (particles) is added little by little to the electrolyte aqueous solution and dispersed. The ultrasonic dispersion treatment is continued for another 60 seconds. During the ultrasonic dispersion, the water temperature of the water tank is appropriately controlled to 10° C. to 40° C.

[0144] (6) The electrolyte aqueous solution containing the dispersed toner (particles) in (5) is added dropwise to the round bottom beaker placed in the sample stage using a pipette to set the measurement concentration to about 5%. Then, measurement is performed until the number of particles measured reaches 50,000.

[0145] (7) The measurement data is analyzed by the aforementioned dedicated software equipped with the instrument, and the weight average particle diameter (D4) is calculated. When the dedicated software is set to graph / volume %, the "average diameter" in the analysis / volume statistics (arithmetic mean) screen is the weight average particle diameter (D4), and when the dedicated software is set to graph / number %, the "average diameter" in the "analysis / number statistics (arithmetic mean)" screen is the number average particle diameter (D1).

[0146] <Composition Analysis of Binder Resin>

[0147] ·Binder resin separation method

[0148] 100mg toner is dissolved in 3mL chloroform. Then, insoluble matter is removed by suction filtration using a syringe fixed with a sample treatment filter (pore size of 0.2μm to 0.5μm, for example, using H-25-2 sample pretreatment filter cartridge (Tosoh Corporation)). Soluble matter is introduced into a preparative HPLC (instrument: LC-9130NEXT, Japan AnalyticalIndustry Co., Ltd, preparative column [60cm], exclusion limit: 20000, 70000, 2 columns), and the chloroform eluent is transported. Once the peak can be confirmed by the display of the obtained chromatogram, the retention time of a molecular weight of at least 2,000 provided as a monodisperse polystyrene reference material is graded. The solution of the obtained fraction is dried and solidified to obtain a binder resin.

[0149] Component identification and weight ratio measurement of binder resins using nuclear magnetic resonance spectroscopy (NMR)

[0150] 1mL of deuterated chloroform is added to 20mg of toner, and the proton NMR spectrum of the dissolved binder resin is measured. The molar ratio and mass ratio of each monomer are calculated from the obtained NMR spectrum, and then the content of the constituent monomer units of the binder resin, such as non-crystalline polyester resin, can be determined. For example, in the case of styrene-acrylic copolymers, the composition ratio and mass ratio can be calculated based on the peak near 6.5ppm derived from styrene monomers and the peak near 3.5 to 4.0ppm derived from acrylic monomers. In the case of polyester resins and styrene-acrylic resin copolymers, the molar ratio and weight ratio are calculated using the peaks derived from the monomers constituting the polyester resin and the peaks derived from the styrene-acrylic copolymers, and then the content of each monomer unit in the polyester resin is obtained.

[0151] NMR instrument: RESONANCE ECX500, JEOL Ltd.

[0152] Measuring nuclei: protons

[0153] Measurement mode: Single pulse

[0154] Reference peak: TMS

[0155] <Measurement of σr and Si Amount of Magnetic Iron Oxide Particles B>

[0156] The measurement of σr and the amount of Si of the magnetic iron oxide particles B was performed as follows.

[0157] The external additives on the toner were removed using the aforementioned method to obtain toner particles. The toner particles were dissolved in chloroform and the magnetic iron oxide particles B were collected using a magnet. The magnetic iron oxide particles B were washed by performing the following process 3 times: the obtained iron oxide particles B were immersed in chloroform and collected using a magnet.

[0158] The obtained magnetic iron oxide particles B and SMP-1-10 (Toei Industry Co., Ltd.) vibration magnetometer were used to measure the σr of the magnetic iron oxide particles B at an external magnetic field of 795.8 kA / m and a room temperature of 25°C. In addition, 200 mg of the obtained magnetic iron oxide particles B were introduced into a liquid sample measurement cup in the fluorescent X-ray measurement and spread evenly over the entire bottom surface. The amount of Si in the iron oxide was quantified by the fundamental parameter method in a He atmosphere using an Axios (PANalytical) fluorescent X-ray analyzer and the "SuperQ ver.4.0F" (PANalytical) software equipped with the instrument.

[0159] <Measurement of Weight Average Molecular Weight Mw and Number Average Molecular Weight Mn of Binder Resin>

[0160] The molecular weight distribution (weight average molecular weight Mw, number average molecular weight Mn) of the binder resin is measured by gel permeation chromatography (GPC) as follows.

[0161] First, the sample was dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The obtained solution was filtered using a "sample pretreatment filter cartridge" (Tosoh Corporation) solvent-resistant membrane filter with a pore size of 0.2 μm to obtain a sample solution. The sample solution was adjusted so that the concentration of the THF soluble component was 0.8% by mass. The sample solution was used for measurement under the following conditions.

[0162] Instrument: HLC8120GPC (detector: RI) (Tosoh Corporation)

[0163] ·Column: Shodex KF-801, 802, 803, 804, 805, 806 and 807 7-column (Showa DenkoKabushiki Kaisha)

[0164] Eluent: Tetrahydrofuran (THF)

[0165] Flow rate: 1.0mL / min

[0166] Oven temperature: 40.0℃

[0167] Sample injection volume: 0.10mL

[0168] The molecular weight of the sample is determined using a molecular weight calibration curve constructed using polystyrene resin standards (e.g., product name "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", Tosoh Corporation).

[0169] Example

[0170] The present invention is described more specifically below using Production Examples and Examples, but the present invention is by no means limited to or by these. The parts in the following compositions are parts by mass in all cases.

[0171] <Production Example of Non-Magnetic Inorganic Oxide Particles A1>

[0172] The atmosphere in the reaction vessel was replaced by introducing a mixture of argon and oxygen in a volume ratio of 3:1. Oxygen was introduced at 40 m 3 / hr was supplied to the reaction vessel, and hydrogen was supplied at 20m 3 / hr supply, using an igniter to form an oxygen-hydrogen combustion flame. Then, by using a pressure of 147kPa (1.5kg / cm 2 ) is used to introduce the raw silicon metal powder into the combustion flame to form a dust cloud. The dust cloud is ignited by the combustion flame, and an oxidation reaction occurs through dust explosion. After the oxidation reaction, the interior of the reaction container is cooled to obtain a silicon dioxide powder with a number average particle size of 2.67 μm.

[0173] The silica powder was pulverized using a pulverizer (Hosokawa Micron Corporation) to obtain non-magnetic inorganic oxide particles A1 having a number average particle diameter of 1,520 nm.

[0174] <Production Example of Non-magnetic Inorganic Oxide Particles A4, A5 and A11>

[0175] Non-magnetic inorganic oxide particles A4, A5 and A11 were obtained according to the production example of the silica particles 1 by pulverizing while adjusting the pulverizing force of the pulverizer.

[0176] <Production Example of Non-Magnetic Inorganic Oxide Particles A2, A3, A6 and A12>

[0177] The atmosphere in the reaction vessel was replaced by introducing a mixture of argon and oxygen in a volume ratio of 3:1. Oxygen was introduced at 40 m 3 / hr was supplied to the reaction vessel, and hydrogen was supplied at 20m 3 / hr supply, using an igniter to form an oxygen-hydrogen combustion flame. Then, by using a pressure of 0.5kg / cm 2 The raw silicon metal powder is introduced into the combustion flame by a hydrogen carrier gas to form a dust cloud. The oxidation reaction occurs by a dust explosion generated by igniting the dust cloud by the combustion flame. After the oxidation reaction, the inside of the reaction vessel is cooled to obtain a silicon dioxide powder with a number average particle size of 3.44 μm.

[0178] The silica powder was pulverized while adjusting the pulverizing force of the pulverizer to obtain non-magnetic inorganic oxide particles A2, A3 and A6. The silica powder that was not pulverized by the pulverizer was referred to as non-magnetic inorganic oxide particle A12.

[0179] <Production Example of Non-Magnetic Inorganic Oxide Particles A7>

[0180] The ilmenite ore is dried and crushed, and digested / extracted by treating with concentrated sulfuric acid. After removing the unreacted ore, the ferric sulfate is decrystallized. By adding an aqueous sodium hydroxide solution to the obtained titanyl sulfate, the pH is made to reach 9.0, and desulfurization is performed, then, neutralized to pH 5.8 with hydrochloric acid, filtered and washed. After roasting in a heating furnace, it is crushed while adjusting the crushing force of the pulverizer to obtain titanium oxide called non-magnetic inorganic oxide particles A7.

[0181] <Production Example of Non-Magnetic Inorganic Oxide Particles A8>

[0182] While adjusting the pulverizing force, magnesium oxide powder (Pyrokisuma 3320, Kyowa Chemical Industry Co., Ltd.) was pulverized using a pulverizer to obtain magnesium oxide particles referred to as non-magnetic inorganic oxide particles A8.

[0183] <Production Example of Non-Magnetic Inorganic Oxide Particles A9>

[0184] Alumina is obtained by refining bauxite raw materials using the Bayer process. Sodium hydroxide is added to bauxite, and thermal decomposition is performed at 250°C. After removing insoluble matter by filtration, aluminum hydroxide as a solid is recovered by cooling. The aluminum hydroxide is heated and dehydrated at 1050°C to obtain aluminum oxide. It is pulverized with a pulverizer while adjusting the pulverizing force, thereby obtaining aluminum oxide particles called non-magnetic inorganic oxide particles A9.

[0185] <Production Example of Non-magnetic Inorganic Oxide Particles A10>

[0186] The ilmenite ore is dried and crushed, and digested / extracted by treatment with concentrated sulfuric acid. After removing the unreacted ore, the ferric sulfate is decrystallized. By adding an aqueous sodium hydroxide solution to the obtained titanyl sulfate, the pH is reached to 9.0, and a desulfurization treatment is performed, then, neutralized to pH 5.8 with hydrochloric acid, filtered and washed. Water is added to the washed filter cake to make a slurry of 1.5 mol / L in terms of TiO2, and hydrochloric acid is added to make the pH to 1.5, and a deflocculation treatment is performed. The desulfurized / deflocculated metatitanic acid is collected as TiO2 and introduced into a 3-L reaction vessel. An aqueous strontium chloride solution is added to the deflocculated metatitanic acid slurry so that the SrO / TiO2 molar ratio reaches 1.18, and then the TiO2 concentration is adjusted to 0.9 mol / L.

[0187] Then, after heating to 90°C while stirring and mixing, 444mL of a 10mol / L sodium hydroxide aqueous solution was added over 50 minutes while slightly bubbling with nitrogen at 600mL / min; then stirred at 95°C for 1 hour while slightly bubbling with nitrogen at 400mL / min. Then, while stirring and injecting 10°C cooling water into the jacket of the reaction vessel, the reaction slurry was quenched to 12°C; neutralized by adding hydrochloric acid under stirring for 1 hour; then filtered and separated. After roasting in a heating furnace, it was pulverized with a pulverizer while adjusting the pulverizing force to obtain strontium titanate called non-magnetic inorganic oxide particles A10.

[0188] [Table 1]

[0189]

[0190] <Production Example of Magnetic Iron Oxide Particles B1>

[0191] An aqueous solution containing ferrous hydroxide is prepared by mixing the following into an aqueous solution of ferrous sulfate: a sodium hydroxide solution in an amount of 1.00 to 1.10 equivalents relative to elemental iron, P2O5 in an amount providing 0.15 mass % of elemental phosphorus relative to elemental iron, and SiO2 in an amount providing 1.50 mass % of elemental silicon relative to elemental iron. The pH of the aqueous solution is made 8.0, and an oxidation reaction is carried out at 85° C. while bubbling with air to prepare a slurry containing seed crystals.

[0192] Then, an aqueous solution of ferrous sulfate was added to the slurry to give an initial amount of 0.90 to 1.20 equivalents relative to the alkali (sodium component in the sodium hydroxide solution), after which the slurry was maintained at pH 7.6, and an oxidation reaction was performed while bubbling with air to obtain a slurry containing iron oxide. The produced magnetic iron oxide particles were filtered on a filter press and washed with a large amount of water, and then dried at 120° C. for 2 hours; the resulting particles were crushed to obtain magnetic iron oxide particles B1 having a volume average particle diameter of 150 nm. The magnetic iron oxide particles B1 had a spherical shape.

[0193] <Production Example of Magnetic Iron Oxide Particles B2 to B6>

[0194] Magnetic iron oxide particles B2 to B6 shown in Table 2 were obtained according to the production example of magnetic iron oxide particle B1 except that the mixing amount of SiO2 was 0.3 mass % and the oxidation reaction was performed at 85°C and the retention time at pH 7.6 was adjusted.

[0195] [Table 2]

[0196]

[0197] <Binder Resin>

[0198] Table 3 shows materials used as binder resins in the following examples.

[0199] [Table 3]

[0200]

[0201] The composition of the binder resin A-4 is as follows.

[0202] Binder resin A-4: molecular weight different from that of binder resin A-1 ([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])

[0203] <Production Example of Toner 1>

[0204] Binder resin A-1: ​​100.0 parts

[0205] ([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])

[0206] Paraffin wax (HNP9: Nippon Seiro Co., Ltd.): 6.0 parts

[0207] Non-magnetic inorganic oxide particles A1: 2.0 parts

[0208] Iron complex of monoazo dye (T-77, Hodogaya Chemical Co., Ltd.): 2.0 parts

[0209] Magnetic iron oxide particles B1: 100 parts

[0210] Crystalline polyester resin A: 5 parts

[0211] (1:1 condensation product of sebacic acid and dodecanediol)

[0212] These materials were mixed using a Henschel mixer (Model FM-75, Mitsui Mining Co., Ltd.) for 20 s. -1 The mixture was mixed at a rotation speed of 1000rpm and a rotation time of 5 minutes, and then kneaded using a twin-screw kneader (model PCM-30, Ikegai Corporation) set at a temperature of 130°C. The obtained kneaded product was cooled to 25°C and coarsely pulverized to less than 1 mm using a hammer mill to obtain a coarse pulverized product. The obtained coarse pulverized product was finely pulverized using a mechanical pulverizer (T-250, Turbo Kogyo Co., Ltd.). Classification was performed using a multi-stage classifier based on the wall effect to obtain a toner particle 1 having a weight average particle size (D4) of 7.5 μm.

[0213] A toner mixture was obtained by mixing 100 parts of the obtained toner particles with 1.5 parts of hydrophobized silica fine particles having a number average primary particle size of 10 nm; mixing was performed using a Henschel mixer (Mitsui Mining Co., Ltd.) at a rotation speed of 3,000 rpm for 5 minutes.

[0214] Coarse particles were then removed using a 300-mesh screen (opening 48 μm) to obtain Toner 1. The weight average particle size of Toner 1 was 7.5 μm. The formulation of Toner 1 is given in Table 4.

[0215] [Table 4]

[0216]

[0217] <Production Example of Toner 2>

[0218] Toner 2 was obtained in the same manner as in the production example of Toner 1 except that the magnetic iron oxide particles B1 were changed to magnetic iron oxide particles B2, and the types and parts of the materials were changed as shown in Table 4.

[0219] <Production Example of Toner 3>

[0220] Toner 3 was obtained in the same manner as in the production example of Toner 1 except that the following changes were made: crystalline polyester resin A was not added, and for the wax, behenyl stearate was used, and the types and parts of materials were changed as shown in Table 4.

[0221] <Production Example of Toner 4>

[0222] Toner 4 was obtained in the same manner as in the production example of Toner 3 except that the following changes were made in the production example of Toner 3: Binder Resin A-1 was changed to Binder Resin A-2 having the composition given below, and the types and parts of materials were changed as shown in Table 4.

[0223] Binder resin A-2: styrene-acrylic resin-polyester resin hybrid resin (mass ratio: styrene-acrylic resin / polyester resin = 60 / 40)

[0224] (Mass ratio [polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane:polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane:terephthalic acid:trimellitic acid:acrylic acid=90:10:92:3:10, styrene:butyl acrylate=90:40])

[0225] <Production Example of Toners 5 to 18>

[0226] Toners 5 to 18 were obtained in the same manner as in the production example of Toner 3 except that the following changes were made in the production example of Toner 3: Binder resin A-2 was changed to Binder resin A-3 having a composition given below, and the types and parts of materials were changed as shown in Table 4. The weight average particle diameter was appropriately controlled to the values ​​in Table 5 by adjusting the micro-pulverization force and classification conditions.

[0227] Binder resin A-3: styrene-acrylic resin

[0228] (Mass ratio, styrene: n-butyl acrylate = 78:22)

[0229] <Comparative Example>

[0230] <Production Examples of Toners 19 to 25>

[0231] Toners 19 to 25 were obtained in the same manner as in the production example of Toner 1 except that the following changes were made in the production example of Toner 1: The types and parts of the materials were changed as shown in Table 4.

[0232] The properties of the obtained toner are given in Table 5.

[0233] [Table 5]

[0234]

[0235] The particle diameter in the table is the weight average particle diameter (D4). The "A / B average diameter ratio" is the ratio of the number average particle diameter of the long diameter of the non-magnetic inorganic oxide particles A to the number average particle diameter of the long diameter of the magnetic iron oxide particles B. The "B / A number ratio" is the ratio of the number of magnetic iron oxide particles B contained in the cross section of the toner particles relative to the number of non-magnetic inorganic oxide particles A contained in the cross section of the toner particles. The "toner / A average diameter ratio" is the ratio of the weight average particle diameter of the toner to the number average particle diameter of the long diameter of the non-magnetic inorganic oxide particles A. The A number % is the "proportion of particles with a long diameter of 400nm to 3,000nm in the non-magnetic inorganic oxide particles A with a long diameter of 100nm or more", and the B number % is the "proportion of particles with a long diameter of 50nm to 350nm in the magnetic iron oxide particles B".

[0236] <Evaluation of Friction Fixability>

[0237] To evaluate the fixability in a high-speed machine, friction fixability evaluation was conducted using an HP LaserJet Enterprise M609dn with the process speed modified to 500 mm / sec and the fixing temperature controlled to be reduced by 25° C. from the setting.

[0238] The fixability was evaluated by the degree of contamination of lens cleaning paper (Silbon Paper, Nikon) before and after rubbing a solid black image output under normal temperature and humidity. OCE RED LABEL (area weight: 80 g / m 2 ) is used as paper.

[0239] Use lens cleaning paper at 100g / cm 2 After rubbing the fixed image with a back and forth stroke under a load of , the contamination density of the lens cleaning paper (Silbon Paper, Nikon) was evaluated. The contamination was evaluated using a MacBeth reflection densitometer (MacBeth Corporation) using the numerical value of the difference in density between the contaminated area and before use, and grades A to C were considered good. The evaluation results are given in Table 6.

[0240] A: Concentration difference is 0 to 0.02

[0241] B: Concentration difference is 0.03 to 0.05

[0242] C: Concentration difference is 0.06 to 0.09

[0243] D: Concentration difference is 0.10 or more

[0244] <Evaluation of Glossiness of Plain Paper>

[0245] To evaluate printing in a high-speed machine, gloss evaluation was performed using an HP LaserJet Enterprise M609dn with the process speed modified to 500 mm / sec and the fixing temperature controlled to be lowered by 25° C. from the setting.

[0246] OCE RED LABEL (area weight: 80g / m 2 ) was used as paper, and 9 square images (20 × 20 mm) arranged in 3 rows and 3 columns were printed (toner loading: 0.6 mg / cm 2 ). The gloss of the image was measured using a light incident angle condition of 75° and using a Glossmeter PG-3D handheld gloss meter (Tokyo Denshoku Co., Ltd.), and the average gloss value of 9 squares was found.

[0247] Higher gloss values ​​represent an image with a smoother, glossier image surface, while lower gloss values ​​represent a matte image with a cooler impression.

[0248] A: Gloss less than 15

[0249] B: Gloss is 15 or more and less than 25

[0250] C: Gloss 25 or more and less than 35

[0251] D: Gloss is 35 or more and less than 40

[0252] E: Glossiness is 40 or above

[0253] <Evaluation of glossiness of glossy paper>

[0254] When glossy paper having a smooth surface is used, this contributes to improved fixing gloss and contributes to reduced black image quality, and therefore a particularly strict evaluation is performed.

[0255] To evaluate printing in a high-speed machine, gloss evaluation was performed using an HP LaserJet Enterprise M609dn with the process speed modified to 500 mm / sec and the fixing temperature controlled to be reduced by 50° C. from the setting.

[0256] Image Coat Gloss 100 glossy paper (area weight: 100g / m 2, Canon Marketing Japan Inc.) was used as paper, and 9 square (20×20 mm) images arranged in 3 rows and 3 columns were printed (toner load: 0.6 mg / cm 2 ). The gloss of the image was measured using a light incident angle condition of 75° and using a Glossmeter PG-3D handheld gloss meter (Tokyo Denshoku Co., Ltd.), and the average gloss value of 9 squares was found.

[0257] A: Gloss less than 20

[0258] B: Gloss is 20 or more and less than 30

[0259] C: Gloss is 30 or more and less than 40

[0260] D: Gloss is 40 or more and less than 50

[0261] E: Glossiness is 50 or above

[0262] [Table 6]

[0263] The sheen of glossy paper Plain paper gloss Evaluation of fixability Example 1 Toner 1 A A A Example 2 Toner 2 A A B Example 3 Toner 3 A A B Example 4 Toner 4 A A B Example 5 Toner 5 B A B Example 6 Toner 6 B A C Example 7 Toner 7 B B B Example 8 Toner 8 B B B Example 9 Toner 9 C B B Example 10 Toner 10 C B B Embodiment 11 Toner 11 C B B Example 12 Toner 12 D C B Example 13 Toner 13 D C C Embodiment 14 Toner 14 D D B Embodiment 15 Toner 15 D D B Example 16 Toner 16 D D B Embodiment 17 Toner 17 D D B Embodiment 18 Toner 18 D D D Comparative Example 1 Toner 19 E E A Comparative Example 2 Toner 20 A A E Comparative Example 3 Toner 21 E C C Comparative Example 4 Toner 22 D B E Comparative Example 5 Toner 23 E D B Comparative Example 6 Toner 24 A A E Comparative Example 7 Toner 25 E D E

[0264] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A toner comprising toner particles, wherein the toner particles comprise: Binder resin, non-magnetic inorganic oxide particles A, and Magnetic iron oxide particles B, characterized in that The softening point of the chloroform-soluble component of the toner particles is 90° C. or less; The non-magnetic inorganic oxide particles A and the magnetic iron oxide particles B are internally added to the toner particles; The non-magnetic inorganic oxide particles A contain at least one element selected from the group consisting of Si, Mg, Al, Ti and Sr as a main component thereof; Among the non-magnetic inorganic oxide particles A having a major diameter of 100 nm or more, the proportion of particles having a major diameter of 400 to 3,000 nm is 70% by number or more, Among the magnetic iron oxide particles B, the proportion of particles having a major diameter of 50 to 350 nm is 70% by number or more; and The ratio of the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A to the number average particle diameter of the major axis of the magnetic iron oxide particles B, ie, non-magnetic inorganic oxide particles A / magnetic iron oxide particles B, is 5 to 30.

2. The toner according to claim 1, wherein In transmission electron microscope observation of a cross section of the toner provided by slicing with a microtome, The ratio of the number of the magnetic iron oxide particles B to the number of the non-magnetic inorganic oxide particles A present in the cross section of the toner particle, ie, magnetic iron oxide particles B / non-magnetic inorganic oxide particles A, is 50 to 500.

3. The toner according to claim 1 or 2, wherein In transmission electron microscope observation of a cross section of the toner provided by slicing with a microtome, The non-magnetic inorganic oxide particles A exist in a range of 0.5 to 5.0 per one cross section of the toner.

4. The toner according to claim 1 or 2, wherein In transmission electron microscope observation of a cross section of the toner provided by slicing with a microtome, The shape factor SF1 of the non-magnetic inorganic oxide particles A is greater than 140, and The shape factor SF1 of the magnetic iron oxide particles B is 110 or less.

5. The toner according to claim 1 or 2, wherein Among the non-magnetic inorganic oxide particles A having a major diameter of 100 nm or more, the proportion of particles having a major diameter of 800 nm to 3,000 nm is 70% by number or more.

6. The toner according to claim 1 or 2, wherein The ratio of the weight average particle diameter of the toner to the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A, ie, the weight average particle diameter of the toner / the number average particle diameter of the major axis of the non-magnetic inorganic oxide particles A, is 2 to 15.

7. The toner according to claim 1 or 2, wherein The non-magnetic inorganic oxide particles A are silicon dioxide particles.

8. The toner according to claim 1 or 2, wherein The binder resin includes a non-crystalline polyester resin.

9. The toner according to claim 8, wherein The content of the non-crystalline polyester resin in the binder resin is 50% by mass or more.

10. The toner according to claim 1 or 2, wherein The binder resin has a number average molecular weight Mn of 1,000 to 5,000.

11. The toner according to claim 1 or 2, wherein The residual magnetization intensity σr of the magnetic iron oxide particles B is 4 to 18Am 2 / kg.

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