Electrophotographic toner manufacturing method

Abstract

To provide an electrophotographic toner with an excellent photoluminescent property, and a method for manufacturing the toner.SOLUTION: The electrophotographic toner of the present invention is an electrophotographic toner including toner mother particles containing a resin and an electrophotographic pigment, the resin coating the photoluminescent pigment. The thickness from an arbitrary point on the outline of the outermost surface of the toner mother particles to the surface of the photoluminescent pigment in the cross section of the image of the toner mother particles is small and uneven, and the photoluminescent pigment is flat.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a toner for electrophotography and a method for producing the same, and more particularly to a toner for electrophotography having excellent brightness and a method for producing the same. [Background technology]

[0002] In recent years, in image formation using electrophotographic processes, there has been a demand for output of high-value-added images similar to those seen in the commercial printing field in response to various customer needs. For example, images output by electrophotography may be required to have a brilliance comparable to that of metallic paper made of metallized paper. In electrophotographic image formation, formation of brilliance images is carried out using an electrophotographic brilliance toner (hereinafter also simply referred to as "brilliance toner"), which is an electrophotographic toner containing a brilliance pigment.

[0003] Regarding glitter toners, for example, Patent Document 1 discloses a toner technology that suppresses the decrease in glitter (glitter) in images that occurs under conditions in which continuous image formation is performed in a low-temperature, high-humidity environment. However, the demand for glitter is increasing, and further improvements in glitter are required. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-54739 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above problems and circumstances, and an object of the present invention is to provide an electrophotographic toner having excellent brightness and a method for producing the same. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the present inventors have investigated the causes of the above-mentioned problems, and as a result have found that in an electrophotographic toner containing toner base particles containing at least a resin and a glittering pigment, the resin coats the glittering pigment, the thickness from any point on the outline of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the glittering pigment is thin and uniform, and the glittering pigment is flat, thereby achieving excellent glittering properties, thereby arriving at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0007] 1. A method for producing an electrophotographic toner, which comprises producing an electrophotographic toner containing toner base particles containing at least a resin and a photoluminescent pigment, the resin coats the bright pigment; The bright pigment is flat, When the bright pigment is placed on a smooth surface and the surface visible from above is the surface of the bright pigment, an average thickness from a point on the contour of the outermost surface of the toner base particle to the surface of the bright pigment in a cross-sectional image of the toner base particle is within a range of 0.1 to 1.5 μm; a coefficient of variation in thickness from a point on the contour of the outermost surface of the toner base particle to the surface of the bright pigment in a cross-sectional image of the toner base particle is within a range of 1.0 to 5.0; The content of the bright pigment is 25 to 140 parts by mass relative to 100 parts by mass of the resin, The resin and additives a step of preparing resin particles containing The resin particles and the bright pigment are mixed. death, Heating the resin to melt the resin within the resin particles; Mechanical impact force The surface of the bright pigment is coated with the resin. The toner base particles are prepared by and 1. A method for producing a toner for electrophotography, comprising:

[0010] 2 The average major axis diameter of the bright pigment is within the range of 3 to 30 μm. The first feature is In the section A method for producing the electrophotographic toner described above. [Effects of the Invention]

[0012] According to the above-mentioned means of the present invention, it is possible to provide an electrophotographic toner having excellent brightness and a method for producing the same.

[0013] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0014] Many of the conventionally used bright pigments are thin and flat, i.e., flaky (scale-like), and this shape allows the direction of reflected light from the surface of the bright pigment to be aligned, thereby producing brightness. Therefore, in order to improve the brightness of the resulting image, it is preferable that the direction of reflected light from the surface of the bright pigment be aligned, and it is preferable that the bright pigment be aligned (oriented) parallel to the surface of the recording medium.

[0015] Because a glitter pigment cannot be fixed to a recording medium by itself, it can be fixed to the recording medium by coating the glitter pigment with a binder resin to form toner particles (described in detail below). However, if the thickness of the resin coating the glitter pigment is relatively thick, the glittering property will be reduced because the light incident on the toner particles and the light reflected from the glitter pigment are refracted or absorbed in or on the surface of the resin. Furthermore, if the thickness is uneven, the glittering pigment in the toner particles will not be aligned parallel to the surface of the recording medium, resulting in reduced glittering property. Therefore, it is preferable to make the thickness of the coating resin relatively thin and reduce thickness unevenness.

[0016] In the kneading and grinding method, which is commonly used to manufacture toner, resins, pigments, and other additives are heated, melted, and kneaded, then rolled and cooled, and then ground and classified to obtain the toner. With this method, it is difficult to control the thickness of the resin that coats the photoluminescent pigment, i.e., to make it relatively thin and reduce thickness variations. In addition, in some cases, the photoluminescent pigment may bend during grinding and classification, causing the direction of reflected light from the photoluminescent pigment surface to become misaligned, resulting in a decrease in photoluminescence (see Figure 1).

[0017] Furthermore, even with the polymerization method commonly used to manufacture toner, it is difficult to control the thickness of the resin that coats the photoluminescent pigment, i.e., to make it relatively thin and reduce thickness variations. As a result, when the toner particles adhere to the recording medium, the photoluminescent pigment in the toner particles is not aligned parallel to the surface of the recording medium, resulting in reduced photoluminescence (see Figure 2).

[0018] The inventors have conducted extensive research into methods for controlling the thickness of the resin coating on the photoluminescent pigment, and have found that by using a dry coating method and appropriately adjusting the amount of resin added and the stirring and mixing time, it is possible to coat the photoluminescent pigment with a relatively thin and uniform layer of resin (see Figure 3). [Brief explanation of the drawings]

[0019] [Figure 1] Mechanism of the decrease in brightness of toner particles produced by the kneading and pulverizing method [Figure 2] Mechanism of the decrease in brightness of toner particles produced by polymerization method [Figure 3] Mechanism for improving the brightness of the toner particles of the present invention [Figure 4] Cross-sectional view of a toner base particle according to the present invention [Figure 5] Cross-sectional schematic diagram showing an example of a high-speed agitation mixer [Figure 6] A cross-sectional schematic diagram showing an example of a drum tandem type image forming apparatus DETAILED DESCRIPTION OF THE INVENTION

[0020] The electrophotographic toner of the present invention is an electrophotographic toner comprising toner base particles containing at least a resin and a photoluminescent pigment, wherein the resin coats the photoluminescent pigment, the thickness from any point on the outline of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the photoluminescent pigment is thin and uniform, and the photoluminescent pigment is flat. This feature is a technical feature common to or corresponding to the following embodiments.

[0021] In an embodiment of the present invention, from the viewpoint of excellent brilliance, it is preferable that the coefficient of variation in thickness from any point on the contour of the outermost surface of the toner base particle to the surface of the brilliance pigment in a cross-sectional image of the toner base particle is within a range of 1.0 to 5.0.

[0022] From the viewpoint of excellent brilliance, it is preferable that the average thickness from any point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the brilliance pigment is within the range of 0.1 to 1.5 μm.

[0023] In addition, from the viewpoint of excellent brilliance, the average major axis diameter of the bright pigment is preferably within the range of 3 to 30 μm.

[0024] The method for producing an electrophotographic toner of the present invention is characterized by comprising a step of coating the bright pigment with the resin by a dry coating method to form a resin portion.

[0025] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0026] <<Outline of Electrophotographic Toner>> The electrophotographic toner of the present invention (also referred to as "toner for developing electrostatic images") is an electrophotographic toner comprising toner base particles containing at least a resin and a photoluminescent pigment, characterized in that the resin coats the photoluminescent pigment, the thickness from any point on the outline of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the photoluminescent pigment is thin and uniform, and the photoluminescent pigment is flat.

[0027] In this specification, the electrophotographic toner is also simply referred to as "toner," and the electrophotographic toner containing a photoluminescent pigment is also referred to as "photoluminescent toner." The toner of the present invention contains toner base particles containing at least a resin and a photoluminescent pigment. It is also preferable that an external additive be attached to the surface of the toner base particles.

[0028] In this specification, "toner base particles" refer to the base of "toner particles." The "toner base particles" according to the present invention contain at least a resin and a photoluminescent pigment, and may contain other components such as wax and a charge control agent as necessary. The "toner base particles" are called "toner particles" when an external additive is added. The term "toner" refers to an aggregate of toner particles.

[0029] 4 shows a cross-sectional view of a toner base particle 10 according to the present invention. The toner base particle 10 is composed of at least a photoluminescent pigment 1 and a resin portion 2, and the resin portion 2 coats the photoluminescent pigment 1. The resin portion 2 may contain additives in addition to the resin, and may be a single layer or two or more layers.

[0030] In the toner base particles according to the present invention, the flat shape of the luster pigment ensures that the direction of reflected light from the surface of the luster pigment is uniform, thereby achieving excellent luster. Furthermore, the thickness from any point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the luster pigment, i.e., the thickness of the resin portion, is thin and uniform, thereby minimizing the unevenness of the direction of reflected light caused by refraction of light incident on the toner particle or light reflected from the luster pigment at the surface of the resin portion, and also facilitating the alignment of the luster pigment parallel to the surface of the recording medium, thereby improving luster.

[0031] Regarding brilliance, the color is quantified as L * a * b * In the coordinate values ​​of the color system, L * It can be evaluated by calculating the value of L *The larger the value, the more excellent the brilliance.

[0032] <Configuration of electrophotographic toner> [1 Toner base particles] The toner base particles according to the present invention contain at least a resin and a glittering pigment. The toner base particles are composed of at least the glittering pigment and a resin portion, and the resin portion coats the glittering pigment. The resin portion may contain additives in addition to the resin, and may be a single layer or two or more layers. In the present invention, the "resin portion" refers to the entire portion of the toner base particle excluding the luster pigment.

[0033] [1.1 Photoluminescent pigments] Since the toner base particles according to the present invention contain a glittering pigment, when an image is formed using the toner of the present invention, a glittering image can be obtained. Furthermore, since the glittering pigment has a flat shape, the direction of the reflected light reflected on the surface of the glittering pigment is aligned, thereby achieving excellent glittering.

[0034] In the present invention, the term "flat" refers to a shape that has a predetermined thickness, in which dimensions in at least two directions along a plane direction perpendicular to the thickness direction are greater than the thickness dimension, and that can be placed stably on a flat surface, and is, for example, a shape that resembles a three-dimensional shape such as a sphere or a rectangular parallelepiped that has been crushed in one direction, and includes shapes such as flakes, scales, and plates. Specifically, in a bright pigment, a shape can be said to be flat when the number-average equivalent circle diameter is longer than the number-average maximum thickness.

[0035] The number average equivalent circular diameter and the number average maximum thickness are measured by the following method. The photoluminescent pigment is placed on a smooth surface and vibrated to disperse evenly. For 1,000 particles of photoluminescent pigment, the maximum thickness C and the equivalent circular diameter D of the surface as viewed from above are measured at 1,000x magnification using a color laser microscope "VK-9700" (manufactured by Keyence Corporation), and the arithmetic mean value of these is calculated.

[0036] Examples of constituent materials of the luster pigment include metals (including alloys), metal compounds, glass, crystalline compounds, minerals, etc. Specific examples of the luster pigment include metal powders such as aluminum, brass, bronze, nickel, stainless steel, zinc, copper, silver, gold, and platinum; mica coated with titanium oxide or yellow iron oxide; coated flaky inorganic crystalline substrates such as barium sulfate, layered silicates, and layered aluminum silicates; single-crystal plate-like titanium oxide; basic carbonates; bismuth oxychloride; natural guanine; flaky glass powder; and flaky glass powder vapor-deposited with metal. These may be used alone or in combination of two or more. In addition, various coloring materials such as dyes and pigments may be used in combination to adjust the color tone.

[0037] Among these, from the viewpoints of cost, stability, availability, and brilliance, metal flakes are preferred, aluminum flakes are more preferred, and metal flakes of aluminum metal alone are even more preferred.

[0038] Examples of metal flakes include those obtained by peeling off a thin metal film formed by vacuum-depositing a metal or alloy onto a plastic film, and then crushing and stirring the peeled thin metal film, and those obtained by mixing a metal or alloy powder with a solvent and spreading and / or crushing the powder using a media stirring mill, ball mill, attritor, etc.

[0039] Furthermore, the surface may be treated, and the material may be coated with various surface treatment agents, silane coupling agents, titanate coupling agents, fatty acids, silica particles, acrylic resins, polyester resins, or the like.

[0040] Furthermore, commercially available aluminum flakes may be used, such as Alpaste (registered trademark) WXM-0630, EMERAL (registered trademark) EMR-D5660, and WJC-U75C (all manufactured by Toyo Aluminum K.K.), METALURE (registered trademark) W-52012 IL, and Ultravario Aqua PG-24001 (all manufactured by ECKART), and LG (registered trademark) neo Silver#500 (silver) and Gold#500 (gold) (all manufactured by Oike Kogyo Co., Ltd.).

[0041] The average major axis diameter of the bright pigment is preferably within a range of 3 to 30 μm, and more preferably within a range of 5 to 15 μm.

[0042] The larger the area occupied by the luster pigment on the recording medium, and the more uniformly and parallel the luster pigment surface is to the recording medium surface, the more light can be reflected. Therefore, it is preferable to arrange the toner particles according to the present invention without gaps at the image formation location on the recording medium.

[0043] However, if the particle size of the toner particles is too large, gaps are likely to occur between the toner particles, and if the particle size of the toner particles is too small, the shape of the toner particles becomes closer to a sphere, making it difficult for the glitter pigment to be aligned parallel to the surface of the recording medium. Therefore, it is preferable to adjust the particle size of the toner particles within an appropriate range, and it is preferable to set the average major axis diameter of the glitter pigment within the above range.

[0044] When the average major axis diameter is 3 μm or more, the toner particles tend to be aligned parallel to the surface of the recording medium, and good brilliance can be obtained. By setting the average major axis diameter to 30 μm or less, gaps are less likely to form between the toner particles when they are arranged on the surface of a recording medium, resulting in good glitter. In addition, the glitter pigment is less likely to deform even when subjected to external forces during toner particle production or image formation.

[0045] The average major axis diameter of the bright pigment can be measured by the following method. The major axis diameter is measured in an electron micrograph taken using a scanning electron microscope (SEM) "JSM-7401F" (manufactured by JEOL Ltd.), and the number-average major axis diameter for 1,000 particles of the bright pigment is calculated.

[0046] The average thickness of the luster pigment is preferably within a range of 25 to 500 nm, and more preferably within a range of 80 to 350 nm. When the average thickness is 25 nm or more, light incident on the surface of the luster pigment is less likely to pass through the luster pigment and is more likely to be reflected from the surface, resulting in good luster. Furthermore, the luster pigment is less likely to deform even when subjected to external forces during toner particle production or image formation. On the other hand, when the average thickness is 500 nm or less, the luster pigment is more likely to be aligned parallel to the surface of the recording medium, resulting in good luster.

[0047] When the bright pigment is aluminum flakes, the average thickness is the water surface diffusion area WCA (m 2 / g) and calculate it by the following formula. (Formula 1) Average thickness t(nm)=400 / [WCA(m 2 / g)] The method for calculating the average thickness is described, for example, in Aluminum Paint and Powder, JD Edwards & RI Wray, 3rd Edition, Reinhold Publishing Corp., New York, pages 16-22.

[0048] The "water surface diffusion area" refers to the area occupied by aluminum powder per unit mass when dried aluminum flakes are uniformly diffused on the water surface using the leafing phenomenon, covering it without any gaps. The "leafing phenomenon" refers to a phenomenon in which, when a coating film is produced using aluminum flakes as a vehicle to form a coating, aluminum powder floats up and is arranged on the surface of the coating film.

[0049] The water surface diffusion area can be determined according to JIS K 5906-1998 after a certain pretreatment. In the present invention, the aluminum flakes may be either leafing or non-leafing. For non-leafing types, the procedure is the same as for leafing types, except that the sample is pretreated with a 5% stearic acid solution in mineral spirits. The pretreatment of the sample is described in Journal of Paint Materials, Vol. 156, pp. 2-16 (published by Asahi Chemical Industry Co., Ltd. on September 1, 1980).

[0050] From the viewpoint of glittering, the content of the glittering pigment is preferably in the range of 25 to 140 mass %, more preferably in the range of 40 to 120 mass %, based on the total mass of the binder resin.

[0051] [1.2 Resin] The glitter pigment according to the present invention cannot be fixed on a recording medium by itself, so it can be fixed on a recording medium by forming toner base particles in which the glitter pigment is coated with a binder resin.

[0052] In the present invention, the "resin portion" refers to the entire portion of the toner base particle excluding the glitter pigment, and the glittering property is improved when the thickness of the resin portion is thin and uniform.

[0053] The resin according to the present invention (hereinafter also referred to as "binder resin") is not particularly limited, and binder resins that are commonly used in known electrophotographic toners can be used. Specific examples include polyester, vinyl resins such as styrene-acrylic resin, epoxy resin, polycarbonate, polyurethane, and composite resins containing two or more of these resins. In the present invention, from the viewpoint of achieving both low-temperature fixability, durability, and storage stability, it is preferable that the binder resin contains polyester.

[0054] (polyester) The polyester is preferably a polycondensate of an alcohol component containing a divalent or higher alcohol and a carboxylic acid component containing a divalent or higher carboxylic acid compound.

[0055] Examples of dihydric alcohols include aliphatic diols, alkylene oxide adducts of bisphenol A represented by the following formula (I), bisphenol A, and hydrogenated bisphenol A. These may be used alone or in combination of two or more.

[0056] The aliphatic diol preferably has a carbon number in the range of 2 to 20, more preferably 2 to 15. Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol.

[0057] Also preferred is an alkylene oxide adduct of bisphenol A represented by the following formula (I).

[0058] [ka]

[0059] In formula (I), OR and RO are oxyalkylene groups, R is an ethylene and / or propylene group, and x and y are positive numbers indicating the average number of moles of alkylene oxide added. The sum of x and y is preferably 1 or more, more preferably 1.5 or more. It is also preferably 16 or less, more preferably 8 or less, even more preferably 6 or less, and particularly preferably 4 or less.

[0060] The content of the alkylene oxide adduct of bisphenol A represented by formula (I) is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 100% by mass, based on the total mass of the alcohol component.

[0061] Examples of dicarboxylic acid compounds include dicarboxylic acids, dicarboxylic acid anhydrides, and alkyl ester derivatives in which the alkyl group has 1 to 3 carbon atoms.

[0062] The dicarboxylic acid preferably has a carbon number in the range of 3 to 30, more preferably 3 to 20, and even more preferably 3 to 10. Examples of dicarboxylic acids include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid, and aliphatic dicarboxylic acids such as fumaric acid, maleic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, and succinic acid substituted with an alkyl group having from 1 to 20 carbon atoms or an alkenyl group having from 2 to 20 carbon atoms.

[0063] From the viewpoint of achieving both low-temperature fixability, durability, and storage stability, the carboxylic acid component preferably contains terephthalic acid or fumaric acid. The content of terephthalic acid or fumaric acid is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more, based on the total mass of the carboxylic acid component. When terephthalic acid and fumaric acid are used in combination, the total mass of both preferably falls within the above range.

[0064] Examples of trivalent or higher carboxylic acid compounds include trivalent or higher carboxylic acids, anhydrides of trivalent carboxylic acids, and derivatives of alkyl esters in which the alkyl group has 1 to 3 carbon atoms.

[0065] The trivalent or higher carboxylic acid preferably has a carbon number in the range of 4 to 20, more preferably in the range of 7 to 15, even more preferably in the range of 8 to 12, and particularly preferably in the range of 9 to 10. Examples of trivalent or higher carboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid) and 1,2,4,5-benzenetetracarboxylic acid (pyromellitic acid).

[0066] From the viewpoint of high-temperature offset resistance, the content of the trivalent or higher carboxylic acid compound is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, based on the total mass of the carboxylic acid components. From the viewpoint of low-temperature fixability, it is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0067] The alcohol component may contain a monohydric alcohol, and the carboxylic acid component may contain a monocarboxylic acid compound, as appropriate, from the viewpoint of adjusting the molecular weight and softening point of the polyester.

[0068] From the viewpoint of adjusting the softening point of the polyester, the mass ratio of the carboxylic acid component to the alcohol component (COOH groups / OH groups) is preferably within a range of 0.6 to 1.1, more preferably within a range of 0.7 to 1.05, and even more preferably within a range of 0.75 to 1.05.

[0069] The polyester can be produced, for example, by polycondensing an alcohol component and a carboxylic acid component under an inert gas atmosphere. An esterification catalyst, an esterification promoter, a polymerization inhibitor, etc. may be used as needed. The temperature condition during polycondensation is preferably within a range of 130 to 250°C, and more preferably within a range of 170 to 240°C.

[0070] Examples of the esterification catalyst include tin compounds such as dibutyltin oxide and tin(II) 2-ethylhexanoate, and titanium compounds such as titanium diisopropylate bistriethanolamine, and among these, tin compounds are preferred.

[0071] The amount of the esterification catalyst used is preferably within a range of 0.01 to 1.5% by mass, more preferably within a range of 0.1 to 1% by mass, based on the total mass of the alcohol component and the carboxylic acid component.

[0072] The esterification promoter may, for example, be gallic acid. The amount of the esterification promoter used is preferably within a range of 0.001 to 0.5% by mass, more preferably within a range of 0.01 to 0.1% by mass, based on the total mass of the alcohol component and the carboxylic acid component.

[0073] Examples of the polymerization inhibitor include t-butylcatechol. The amount of the polymerization inhibitor used is preferably within a range of 0.001 to 0.5% by mass, more preferably within a range of 0.01 to 0.1% by mass, based on the total mass of the alcohol component and the carboxylic acid component.

[0074] In the present invention, the polyester may be modified to such an extent that its properties are not substantially impaired. Examples of modified polyesters include polyesters grafted or blocked with phenol, urethane, epoxy, or the like by the methods described in JP-A Nos. 11-133668, 10-239903, and 8-20636. Among these, urethane-modified polyesters in which polyester is urethane-extended with a polyisocyanate compound are preferred.

[0075] (styrene resin) Styrene resins are addition polymers of raw material monomers containing at least styrene or styrene derivatives such as α-methylstyrene and vinyltoluene (hereinafter, styrene and styrene derivatives are collectively referred to as "styrene compounds").

[0076] The content of the styrene compound is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, based on the total mass of the raw material monomers, from the viewpoint of improving the dispersibility of the wax, and is preferably 95% by mass or less, more preferably 93% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of improving the low-temperature fixability.

[0077] The styrene resin is preferably a styrene-acrylic resin containing, as a raw material monomer, a (meth)acrylic acid alkyl ester in which the alkyl ester has 7 or more carbon atoms. Examples of the (meth)acrylic acid alkyl ester include 2-ethylhexyl (meth)acrylate, (iso)octyl (meth)acrylate, (iso)decyl (meth)acrylate, (iso)stearyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0078] In this specification, "(iso)" means both the case where this group is present and the case where it is not present, and when this group is not present, it indicates normal. Furthermore, "(meth)acrylic acid" refers to acrylic acid, methacrylic acid, or both.

[0079] The number of carbon atoms in the alkyl ester of (meth)acrylic acid is preferably 7 or more, more preferably 8 or more, from the viewpoint of improving low-temperature fixability, and is preferably 12 or less, more preferably 10 or less, from the viewpoint of storage stability. The "number of carbon atoms in the alkyl ester" refers to the number of carbon atoms derived from the alcohol component that constitutes the ester.

[0080] The content of the (meth)acrylic acid alkyl ester is preferably 5% by mass or more, more preferably 7% by mass or more, and even more preferably 10% by mass or more, based on the total mass of raw material monomers, from the viewpoint of improving low-temperature fixability, and is preferably 50% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of improving wax dispersibility.

[0081] The raw material monomers for the styrene-acrylic resin may include raw material monomers other than styrene compounds and (meth)acrylic acid alkyl esters, for example, ethylenically unsaturated monoolefins such as ethylene and propylene; diolefins such as butadiene; halovinyls such as vinyl chloride; vinyl esters such as vinyl acetate and vinyl propionate; ethylenic monocarboxylic acid esters such as dimethylaminoethyl (meth)acrylate; vinyl ethers such as methyl vinyl ether; vinylidene halides such as vinylidene chloride; and N-vinyl compounds such as N-vinylpyrrolidone.

[0082] The addition polymerization reaction of raw material monomers for the styrene resin can be carried out in the presence of, for example, a polymerization initiator such as dicumyl peroxide, a polymerization inhibitor, a crosslinking agent, etc., in the presence of an organic solvent or without a solvent. The temperature condition during the addition polymerization reaction is preferably within a range of 110 to 200°C, more preferably within a range of 140 to 170°C.

[0083] Examples of organic solvents include xylene, toluene, methyl ethyl ketone, acetone, etc. The amount of organic solvent used is preferably within a range of 10 to 50% by mass based on the total mass of the raw material monomers.

[0084] (composite resin) In the present invention, from the viewpoint of achieving a balance between low-temperature fixability, durability, and storage stability, the binder resin is preferably a composite resin in which a polyester resin and a styrene resin are chemically bonded via a bireactive monomer that can react with both the raw material monomers of the polyester resin and the raw material monomers of the styrene resin.

[0085] The bireactive monomer preferably has an ethylenically unsaturated bond and one or more functional groups in the molecule, such as a hydroxy group, a carboxy group, an epoxy group, a primary amino group, and a secondary amino group, and among these, a hydroxy group or a carboxy group is preferred, and a carboxy group is more preferred.

[0086] Examples of the bireactive monomer include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride. From the viewpoint of reactivity in polycondensation reactions and addition polymerization reactions, acrylic acid, methacrylic acid, or fumaric acid is preferred. These may be used alone or in combination of two or more.

[0087] However, when used together with a polymerization inhibitor, a polycarboxylic acid compound having an ethylenically unsaturated bond such as fumaric acid functions as a raw material monomer for a polyester resin, rather than as a bireactive monomer.

[0088] The bireactive monomer is preferably a (meth)acrylic acid ester having an alkyl group with 6 or less carbon atoms, and these may be used alone or in combination of two or more.

[0089] From the viewpoint of reactivity in the transesterification reaction, the (meth)acrylic acid ester is preferably a (meth)acrylic acid alkyl ester, and the number of carbon atoms in the alkyl group is preferably within a range of 2 to 6, more preferably within a range of 3 to 4. The alkyl group may have a substituent such as a hydroxy group.

[0090] From the viewpoint of enhancing the dispersibility of the styrene resin and the polyester resin and improving the durability of the toner, the content of the bireactive monomer is preferably 1 mol% or more, more preferably 2 mol% or more, based on the total moles of the alcohol component of the polyester resin, and from the viewpoint of low-temperature fixability, it is preferably 30 mol% or less, more preferably 20 mol% or less.

[0091] From the viewpoint of enhancing the dispersibility of the styrene resin and the polyester resin and improving the durability of the toner, the content of the bireactive monomer is preferably 1% by mass or more, more preferably 2% by mass or more, based on the total mass of the raw material monomers of the styrene resin. Furthermore, from the viewpoint of low-temperature fixability, it is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. The total mass of the raw material monomers of the styrene resin also includes the mass of the polymerization initiator.

[0092] The composite resin obtained by using the bireactive monomer can be prepared, for example, by the following method: From the viewpoint of improving the durability, low-temperature fixability, and heat-resistant storage stability of the toner, the bireactive monomer is preferably used together in the addition polymerization reaction of the raw material monomers of the styrene resin.

[0093] The composite resin can be produced, for example, by a method including a step (A) of polycondensation reaction of raw material monomers of polyester resin and a step (B) of addition polymerization reaction of raw material monomers of styrene resin and a bireactive monomer.

[0094] It is possible to carry out step (B) after step (A), step (A) after step (B), or step (A) and step (B) simultaneously, and it is particularly preferable to carry out step (B) after step (A). It is also preferable that step (A) and step (B) are carried out in the same vessel.

[0095] Instead of carrying out the polycondensation reaction in step (A), a prepolymerized polycondensation resin may be used. When steps (A) and (B) are carried out in parallel, a mixture containing raw material monomers for the styrene resin may be added dropwise to a mixture containing raw material monomers for the polyester resin, and the reaction may be carried out.

[0096] From the viewpoint of durability, the composite resin is preferably a wax-containing composite resin in which wax is previously contained in the composite resin, which can be obtained by carrying out a polycondensation reaction of raw material monomers for a polyester resin or an addition polymerization reaction of raw material monomers for a styrene resin in the presence of wax.

[0097] As the wax, the same waxes as those described below can be used, but paraffin wax is preferred from the viewpoint of low-temperature fixability.

[0098] The wax content in the composite resin is preferably within a range of 0.5 to 15 mass %, more preferably within a range of 1 to 10 mass %, and even more preferably within a range of 1.5 to 7 mass %, relative to the total mass of the raw material monomers of the polyester resin, the raw material monomers of the styrene resin, and the bireactive monomer.

[0099] When wax is used in the preparation of the composite resin, it is preferable to carry out the polycondensation reaction in the presence of wax. For example, it is preferable to add wax together with the raw material monomers of the polyester resin during step (A) and carry out the polycondensation reaction.

[0100] The mass ratio of the styrene resin to the polyester resin in the composite resin (styrene resin / polyester resin) is preferably 3 / 97 or more, more preferably 7 / 93 or more, and even more preferably 10 / 90 or more, from the viewpoint of wax dispersibility. Also, from the viewpoint of achieving both durability, low-temperature fixability, and storage stability, it is preferably 45 / 55 or less, more preferably 35 / 65 or less, even more preferably 30 / 70 or less, and particularly preferably 25 / 75 or less.

[0101] In the above calculations, the mass of the polyester resin is the total mass of the raw material monomers of the polyester resin, and the mass of the bireactive monomer is included in the total mass of the raw material monomers of the polyester resin. The mass of the styrene resin is the total mass of the raw material monomers of the styrene resin, and the mass of the polymerization initiator is included in the total mass of the raw material monomers of the styrene resin.

[0102] In the binder resin, the content of polyester is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass, relative to the total mass of the binder resin.

[0103] From the viewpoints of durability and high-temperature offset resistance, the softening point of the binder resin is preferably 100° C. or higher, more preferably 105° C. or higher, and even more preferably 110° C. or higher. Furthermore, from the viewpoint of suppressing destruction of the bright pigment during melt-kneading, the softening point is preferably 135° C. or lower, more preferably 130° C. or lower, and even more preferably 125° C. or lower.

[0104] The softening point of the binder resin can be measured, for example, by the following method. Using a flow tester "CFT-500D" (Shimadzu Corporation), a 1g sample of binder resin is heated at a temperature increase rate of 6°C / min, while a load of 1.96 MPa is applied by the plunger, and the sample is extruded from a nozzle 1mm in diameter and 1mm in length. The plunger depression distance of the flow tester is plotted against the temperature, and the temperature at which half of the sample flows out is taken as the softening point.

[0105] From the viewpoint of storage stability, the glass transition temperature of the binder resin is preferably 40° C. or higher, and more preferably 50° C. or higher, and from the viewpoint of low-temperature fixability, it is preferably 80° C. or lower, and more preferably 70° C. or lower.

[0106] The glass transition temperature of the binder resin can be measured, for example, by the following method. Using a differential scanning calorimeter "Q-100" (manufactured by TA Instruments Japan), 0.01 to 0.02 g of a binder resin sample is weighed into an aluminum pan, heated to 200°C, and cooled from that temperature to 0°C at a rate of 10°C / min. Next, the sample is heated at a rate of 10°C / min, and the endothermic peak is measured. The glass transition temperature is the temperature at the intersection of an extension of the baseline below the highest endothermic peak temperature and a tangent line showing the maximum slope from the rising part of the peak to the peak apex.

[0107] From the viewpoint of charge buildup, the acid value of the binder resin is preferably 1 mgKOH / g or more, more preferably 5 mgKOH / g or more, and even more preferably 10 mgKOH / g or more, and from the viewpoint of moisture absorption, it is preferably 25 mgKOH / g or less, and more preferably 22 mgKOH / g or less.

[0108] The acid value of the binder resin can be measured, for example, according to the method of JIS-K-0070-1992, except that the measurement solvent is changed from the ethanol and ether mixed solvent specified in JIS-K-0070-1992 to an acetone and toluene mixed solvent (acetone:toluene = 1:1 (volume ratio)).

[0109] When the binder resin is made of a plurality of resins, it is preferable that the weighted average value of the physical properties of each resin falls within the above range.

[0110] (Resin part) The toner base particles according to the present invention are characterized in that the resin coats the luster pigment, and the thickness from any point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the luster pigment is thin and uniform. As mentioned above, in the present invention, all parts of the toner base particle excluding the luster pigment are referred to as the "resin part," and hereinafter, "the thickness from any point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the luster pigment" is also referred to as "the thickness of the resin part."

[0111] Because the thickness of the resin portion covering the flat luster pigment is thin and uniform, the direction of reflected light from the luster pigment is not uniform due to refraction of light in the resin portion, and light loss due to absorption is minimized.In addition, the luster pigment is easily aligned parallel to the surface of the recording medium, and the reflected light from the luster pigment can be uniform across the entire paper surface, thereby improving luster.

[0112] In the present invention, the "thickness from any point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the luster pigment" refers to the length of a perpendicular line from any point on the contour of the outermost surface of the toner base particle to the surface of the luster pigment in a cross-sectional image of the toner base particle obtained by a measurement method using a scanning electron microscope, which will be described later. The toner base particles according to the present invention are composed of at least a photoluminescent pigment and a resin portion, and the resin portion may be a single layer or two or more layers.

[0113] In the present invention, the phrase "the thickness from any point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the luster pigment is thin and uniform" means that the thickness of the resin portion according to the present invention is thin and uniform overall, compared to the resin portion in conventional toner particles. Specific details will be described later, but it is preferable that the average thickness of the resin portion is within the range of 0.1 to 1.5 μm, and the coefficient of variation in the thickness of the resin portion is within the range of 1.0 to 5.0.

[0114] The method for measuring the thickness of the resin part is not particularly limited, but it is preferable to measure it by the following method. In addition, by calculating the coefficient of variation in thickness, it can be determined whether the thickness is uniform.

[0115] The thickness and thickness variation coefficient of the resin portion in the present invention can be measured by the following method.

[0116] A sample of toner base particles is stained with 3% ruthenium tetroxide (RuO4) vapor for 10 minutes (room temperature) using a vacuum electronic staining device "VSC1R1" (Filgen Co., Ltd.), and the stained sample is dispersed in a photocurable resin "D-800" (JEOL Ltd.) and hardened, and the sample is embedded in the photocurable resin.

[0117] The embedded sample is processed onto a flat plate using a razor, fixed to an ion milling sample holder using thermoplastic wax, and subjected to ion milling using an ion milling device "SM-09010" (manufactured by JEOL Ltd.) to prepare a sample for cross-sectional observation. Acceleration voltage: 5.0 kV, beam current: 60 μA, set time: 12 hours, ion species: Ar + Ion milling is performed under the following conditions.

[0118] The cross-section of the dyed cross-section sample is observed using an ultra-high resolution field emission scanning electron microscope "S-4800" (manufactured by Hitachi High-Technologies Corporation). One hundred toner base particle cross-sections to be observed are selected and photographed, with the diameter being within ±3.0 μm of the mass average particle diameter of the toner base particles.

[0119] The obtained cross-sectional image is photographed at 5000x magnification under conditions of an acceleration voltage of 1.0 kV and WD / 3.0 mm, and the photographic image is used with the image processing and analysis device "LUZEX-AP" (manufactured by Nireco Corporation) to measure the thickness of the resin portion covering the lustrous pigment.

[0120] In the obtained cross-sectional image, the resin portion where the binder resin is present is observed as colored black (or gray), but the photoluminescent pigment and embedding resin (photocurable resin) are observed as white, without color, and therefore the presence of a resin portion between the photoluminescent pigment and the embedding resin can be confirmed by their contrast. Furthermore, if the resin portion contains wax, the wax is also observed as white, without color, but the particle size of the wax is smaller than that of the photoluminescent pigment, and the photoluminescent pigment and wax in the toner base particle can be distinguished by their sizes, and it can be confirmed that the white portion with the largest size in the major axis direction in the toner base particle corresponds to the photoluminescent pigment.

[0121] The "thickness of the resin portion" refers to the length of a perpendicular line from any point on the contour of the outermost surface of a toner base particle to the surface of the luster pigment in a cross-sectional image of the toner base particle obtained by a measurement method using a scanning electron microscope. In the present invention, the thickness of the resin portion is measured at 20 arbitrary points on the contour of the outermost surface of the toner base particle. Note that the distance between each of the 20 arbitrary points must be at least 100 nm, and points where the resin has peeled off from the luster pigment and the luster pigment is exposed (i.e., a thickness of 0 nm) are excluded from the arbitrary points.

[0122] In the present invention, the "average thickness of the resin portion" refers to the arithmetic mean value of the thickness of the resin portion at any 20 points on each toner base particle, which is further calculated as the arithmetic mean value for 100 toner base particles.

[0123] From the viewpoint of brilliance, the thinner the thickness of the resin portion, the better. However, since many brilliance pigments are electrically conductive, if the thickness of the resin portion is too thin, the brilliance pigment is likely to be exposed, which can easily cause poor charging.

[0124] From this perspective, the average thickness of the resin portion measured at any 20 points on the contour of the outermost surface of the toner base particle by the above-mentioned method is preferably within a range of 0.1 to 1.5 μm, more preferably within a range of 0.1 to 0.6 μm, and even more preferably within a range of 0.1 to 0.35 μm.

[0125] In the present invention, the "coefficient of variation in thickness of the resin portion" refers to the thickness of the resin portion at any 20 points on each toner base particle, which are sorted in descending order, with the average of the top five values ​​being the "maximum value" of thickness and the average of the bottom five values ​​being the "minimum value" of thickness, and the coefficient of variation in thickness is calculated using the following formula, and the arithmetic average value for 100 toner base particles is then calculated. (Equation 2) Variation coefficient = maximum value / minimum value

[0126] The smaller the coefficient of variation (closer to 1), the less variation and unevenness there is in the thickness of the resin portion, meaning that the resin is more uniformly coated on the photosensitive pigment, which can prevent a decrease in photosensitiveness. Also, if there is some variation in the thickness of the resin portion, unevenness will form on the surface of the toner base particles, making cleaning defects less likely to occur.

[0127] From this viewpoint, the coefficient of variation is preferably within the range of 1.0 to 5.0, more preferably within the range of 1.3 to 3.0, and even more preferably within the range of 1.3 to 2.0.

[0128] The variation in the thickness of the resin portion can also be determined by the standard deviation, and the standard deviation of the thickness of the resin portion at any 20 points is preferably within the range of 10 to 80 nm, and more preferably within the range of 10 to 35 nm.

[0129] The method for producing the toner of the present invention is not particularly limited. When the toner is produced by the dry coating method described below, the thickness of the resin portion and the coefficient of variation in thickness can be appropriately adjusted by the amount of resin added and the stirring and mixing time.

[0130] (Structure of the resin part) The structure of the resin portion is not particularly limited, and may be a single layer or a multi-layer structure of two or more layers. Examples of multi-layer structures with two or more layers include a core-shell structure and a multi-layer structure.

[0131] [1.3 Wax] The toner base particles according to the present invention may contain wax as needed. By containing wax, for example, when forming an image using an image forming apparatus described below, the toner image transferred onto the intermediate transfer body can be transferred onto a recording medium, and toner particles can be prevented from remaining on the intermediate transfer body. As the wax, various known waxes can be used.

[0132] Examples of waxes include hydrocarbon waxes such as polypropylene wax, polyethylene wax, polypropylene-polyethylene copolymer wax, microcrystalline wax, paraffin wax, Fischer-Tropsch wax, and Sasol wax, and oxides thereof; ester waxes such as carnauba wax, montan wax, and deacidified waxes thereof, and fatty acid ester wax; fatty acid amides, fatty acids, higher alcohols, and fatty acid metal salts. Among these, carnauba wax is preferred from the viewpoint of durability. These may be used alone or in combination of two or more.

[0133] From the viewpoint of toner transferability, the melting point of the wax is preferably 60° C. or higher, and more preferably 70° C. or higher. From the viewpoint of low-temperature fixability, the melting point is preferably 160° C. or lower, more preferably 140° C. or lower, even more preferably 130° C. or lower, and particularly preferably 120° C. or lower.

[0134] The melting point of the wax can be measured, for example, by the following method. Using a differential scanning calorimeter "Q-100" (TA Instruments Japan), 0.01-0.02 g of wax sample is weighed into an aluminum pan, heated to 200°C at a rate of 10°C / min, and cooled to -10°C at a rate of 5°C / min. The sample is then heated to 180°C at a rate of 10°C / min and measured. The highest endothermic peak temperature observed in the resulting melting endothermic curve is taken as the melting point of the wax.

[0135] From the viewpoint of the low-temperature fixability and offset resistance of the toner, and also the dispersibility of the wax in the binder resin, the content of the wax is preferably within a range of 0.5 to 15% by mass, more preferably within a range of 1 to 10% by mass, and even more preferably within a range of 1.5 to 7% by mass, relative to the total mass of the binder resin.

[0136] [1.4 Other additives] The toner base particles according to the present invention may contain other additives as needed. Examples of the other additives include charge control agents, magnetic powders, flowability improvers, conductivity adjusters, reinforcing fillers such as fibrous substances, antioxidants, and cleaning improvers. The toner base particles according to the present invention may also contain a colored colorant other than the above-mentioned luster pigment.

[0137] (charge control agent) Examples of positively chargeable charge control agents include nigrosine dyes such as Nigrosine Base EX, Oil Black BS, Oil Black SO, Bontron N-01, Bontron N-04, Bontron N-07, Bontron N-09, and Bontron N-11 (all manufactured by Orient Chemical Industries, Ltd.); triphenylmethane dyes containing a tertiary amine as a side chain, quaternary ammonium salt compounds such as Bontron P-51 (manufactured by Orient Chemical Industries, Ltd.), cetyltrimethylammonium bromide, and COPYCHARGEPXVP435 (manufactured by Clariant); polyamine resins such as AFP-B (manufactured by Orient Chemical Industries, Ltd.); imidazole derivatives such as PLZ-2001 and PLZ-8001 (manufactured by Shikoku Chemical Industries, Ltd.); and styrene-acrylic resins such as FCA-701PT (manufactured by Fujikura Chemical Industries, Ltd.).

[0138] Examples of negatively chargeable charge control agents include metal-containing azo dyes such as Varifast Black 3804, Bontron S-31, Bontron S-32, Bontron S-34, and Bontron S-36 (all manufactured by Orient Chemical Industry Co., Ltd.), Aizenspiron Black TRH and T-77 (all manufactured by Hodogaya Chemical Co., Ltd.), and metal compounds of benzilic acid compounds such as LR-147 and LR-297 (all manufactured by Nippon Carlit Co., Ltd.). ) etc.; metal compounds of salicylic acid compounds, for example, Bontron E-81, Bontron E-84, Bontron E-88, Bontron E-304 (all manufactured by Orient Chemical Industry Co., Ltd.), TN-105 (manufactured by Hodogaya Chemical Co., Ltd.), etc.; copper phthalocyanine dyes; quaternary ammonium salts, for example, COPYCHARGENXVP434 (manufactured by Clariant), nitroimidazole derivatives, etc.; organometallic compounds, etc.

[0139] From the viewpoint of charging stability, the content of the charge control agent is preferably in the range of 0.01 to 10 mass %, more preferably in the range of 0.2 to 5 mass %, even more preferably in the range of 0.2 to 3 mass %, and particularly preferably in the range of 0.2 to 2 mass %, relative to the total mass of the binder resin.

[0140] (coloring agent) The toner base particles according to the present invention may further contain an optional colorant. As the colorant, known inorganic or organic colorants such as those listed below can be used depending on the color of the toner. The content of the colorant is preferably within a range of 1 to 30% by mass, more preferably within a range of 2 to 20% by mass, based on the total mass of the binder resin.

[0141] Specific examples of the colored colorant include a yellow colorant, a magenta colorant, a cyan colorant, a black colorant, a white colorant, etc. These may be used alone or in combination of two or more.

[0142] The yellow colorant may be a known yellow colorant commonly used in yellow toners. Specific examples of the yellow colorant include dyes such as CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162, and pigments such as CI Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, and 185. Mixtures of these may also be used.

[0143] The magenta colorant may be any known magenta colorant commonly used in magenta toners. Specific examples include dyes such as CI Solvent Red 1, 49, 52, 58, 63, 111, and 122, and pigments such as CI Pigment Red 5, 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, and 222. Mixtures of these may also be used.

[0144] The cyan colorant may be any known cyan colorant commonly used in cyan toners. Specifically, dyes such as CI Solvent Blue 25, 36, 60, 70, 93, and 95 may be used, and pigments such as CI Pigment Blue 1, 7, 15, 60, 62, 66, 76, and 15:3 may be used, and mixtures thereof may also be used.

[0145] As the black colorant, known black colorants commonly used in black electrophotographic toners can be used. Specific examples include carbon black, magnetic materials, titanium black, etc. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, lamp black, etc. Examples of magnetic materials include ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these ferromagnetic metals, ferromagnetic metal compounds such as ferrite and magnetite, and alloys that do not contain ferromagnetic metals but exhibit ferromagnetism upon heat treatment. Examples of alloys that exhibit ferromagnetism upon heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

[0146] The white colorant may be an inorganic or organic compound. Examples of inorganic compounds include heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, and smexite. Examples of organic compounds include polystyrene resin particles and urea formalin resin particles.

[0147] [1.5 Shape of toner base particles] (Particle size of toner base particles) The particle size of the toner base particles is preferably in the range of 5 to 50 μm, more preferably in the range of 10 to 30 μm, and even more preferably in the range of 12 to 30 μm, in terms of volume-based median particle size (D50). In the present invention, the volume-based median particle size (D50) means the particle size at which the cumulative volume frequency calculated by volume fraction is 50% calculated from the smallest particle size.

[0148] The volume-based median particle size (D50) can be measured, for example, using the following measuring device as follows.

[0149] Measuring device: Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) Aperture diameter: 100 μm Analysis software: Coulter Multisizer AccuComp version 1.19 (Beckman Coulter, Inc.) Electrolyte: Isoton II (Beckman Coulter, Inc.) Dispersion liquid: Emulgen 109P (Kao Corporation, polyoxyethylene lauryl ether, HLB (Griffin): 13.6) dissolved in the electrolyte to adjust the concentration to 5% by mass

[0150] Dispersion conditions: 10 mg of toner particle sample is added to 5 mL of the above dispersion liquid, and dispersed for 1 minute using an ultrasonic disperser (machine name: US-1 manufactured by SND Corporation, output: 80 W), after which 25 mL of the above electrolyte solution is added, and further dispersed for 1 minute using the ultrasonic disperser to prepare a sample dispersion liquid.

[0151] Measurement conditions: The above sample dispersion is added to 100 mL of the above electrolyte to achieve a concentration that allows the particle size of 30,000 particles to be measured in 20 seconds, and the volume-based median particle size (D50) is determined from the particle size distribution.

[0152] [2 External additives] The toner particles of the present invention preferably further have an external additive attached to the surface of the toner base particles, which can control the chargeability, fluidity, antiblocking properties, etc. of the toner.

[0153] The external additive may be inorganic fine particles or organic fine particles. Examples of inorganic fine particles include silica, alumina, titania, zirconia, tin oxide, zinc oxide, stearic acid compounds such as aluminum stearate and zinc stearate, and titanic acid compounds such as strontium titanate and zinc titanate.

[0154] Examples of organic fine particles include fine particles of resin such as melamine resin and polytetrafluoroethylene resin, and fine particles made of homopolymers such as styrene and methyl methacrylate, or copolymers thereof. These may be used alone or in combination of two or more.

[0155] Among these, silica is preferred, and from the viewpoint of toner transferability, hydrophobic silica that has been subjected to a hydrophobic treatment is more preferred.

[0156] Examples of hydrophobic treatment agents for hydrophobizing the surfaces of silica particles include hexamethyldisilazane (HMDS), dimethyldichlorosilane (DMDS), silicone oil, octyltriethoxysilane (OTES), and methyltriethoxysilane.

[0157] From the viewpoint of the chargeability, fluidity and transferability of the toner, the average particle size of the external additive is preferably within a range of 10 to 250 nm, more preferably within a range of 15 to 200 nm, and even more preferably within a range of 15 to 90 nm.

[0158] The average particle size is a number-average particle size, which is determined by measuring the particle sizes (average values ​​of major and minor axes) of 500 particles in a scanning electron microscope (SEM) photograph and calculating the number average value thereof.

[0159] From the viewpoint of the chargeability, fluidity, and transferability of the toner, the content of the external additive in the toner particles is preferably in the range of 0.05 to 5 mass %, more preferably in the range of 0.1 to 3 mass %, and even more preferably in the range of 0.3 to 3 mass %, relative to the total mass of the toner before treatment with the external additive.

[0160] From the viewpoint of toner fluidity and durability, the coverage of the toner base particles with the external additive is preferably 50% or more, more preferably 80% or more, even more preferably 90% or more, and particularly preferably 95% or more. From the viewpoint of preventing the external additive from migrating to the photoreceptor, the coverage is preferably 200% or less, more preferably 170% or less, and even more preferably 150% or less.

[0161] The coverage of the toner base particles with the external additive can be calculated by the following formula: When two or more types of external additives are used in combination, the total coverage with the external additives is the sum of the coverages calculated for each external additive.

[0162] (Formula 3) Coverage rate (%)=(√3 / 2π)×{(D·ρt) / (d·ρs)}×C×100 In the formula, D is the volume-based median particle diameter of the toner base particles (D 50 ) [μm], d is the number average particle size of the external additive [μm], ρt is the specific gravity of the toner base particles, ρs is the specific gravity of the external additive, and C is the mass ratio of the external additive to the toner base particles (external additive / toner base particles).

[0163] <Method for manufacturing electrophotographic toner> The method for producing an electrophotographic toner of the present invention is characterized by comprising a step of coating a photoluminescent pigment with a resin by a dry coating method to form a resin portion.

[0164] Compared with conventional toner manufacturing methods (kneading and pulverization methods and polymerization methods), the dry coating method makes it possible to make the thickness of the resin portion in the toner base particles thinner and more uniform, thereby improving brilliance. Note that the thickness of the resin portion and the coefficient of thickness variation can be appropriately adjusted by the amount of resin added and the stirring and mixing time.

[0165] In the present invention, the "dry coating method" refers to a method in which, without using a solvent, resin particles are used as a coating resin, the resin particles are mixed with a luster pigment, and then the mixture is heated to melt the coating resin, thereby coating the surface of the luster pigment with the resin.

[0166] When additives such as wax and charge control agents are used, it is preferable to prepare resin particles consisting of the resin and the additives, and then coat the resin on the bright pigment by a dry coating method.

[0167] Examples of equipment for manufacturing toner using the dry coating method include a heated kneader, a heated Henschel mixer, a heated UM mixer, a planetary mixer, a heated fluidized bed, a heated kiln, a high-speed agitator mixer, etc. The heating temperature varies depending on the resin, but a temperature above the melting point or glass transition point is required. For thermosetting resins, condensation crosslinking resins, etc., it is necessary to raise the temperature to a temperature at which curing proceeds sufficiently.

[0168] A preferred high-speed agitating mixer (see FIG. 5) will be described below. As shown in FIG. 5, the main body upper cover 111 is provided with a raw material inlet 112, an inlet valve 113, a filter 114, and an inspection port 115.

[0169] A predetermined amount of photoluminescent pigment and resin particle aggregates are added through raw material inlet 112, and the added raw materials are agitated by horizontal rotor 118 driven by motor 122. Agitation blades 118a, 118b, and 118c are attached to horizontal rotor 118, which are arranged at angular intervals of 120° relative to center 118d of the rotor, and these blades are attached at an angle of 35° relative to the surface of bottom 110a.

[0170] Therefore, when the stirring blades 118a, 118b, and 118c are rotated at high speed, the raw material is scraped upward, collides with the upper inner wall of the main container 110, and falls, but on the way down it collides with the vertical rotating body 119, so the raw material can be stirred efficiently.

[0171] When a high-speed agitator mixer is used to coat a luster pigment with a resin to form a resin portion, in order to better prevent breakage of luster pigments due to collisions between them and to form a resin portion that is uniform and has excellent adhesion, it is preferable to include the following steps (a), (b), (c), and (ii), and it is preferable to set the processing conditions for each step as follows.

[0172] (a) Pre-mixing process Cooling water in the range of 10 to 15°C is passed through jacket 117, and stirring blades 118a, 118b, and 118c are rotated at a peripheral speed of 1 m / sec or less, the temperature inside container 110 is set to the Tg of the resin particles or less, usually 50°C or less, and the charged raw materials are stirred and mixed within the range of 1 to 2 minutes.

[0173] (b) Intermediate formation process Cooling water in the range of 10 to 15°C is passed through jacket 117, and stirring blades 118a, 118b, and 118c are rotated at a peripheral speed of 10 m / sec or less, the temperature inside container 110 is set to the Tg of the resin particles or less, usually 50°C or less, and the charged raw materials are stirred and mixed within the range of 10 to 20 minutes.

[0174] (c) Film formation process The stirring blades are rotated at a peripheral speed equal to or higher than that of the mixing step (b), and warm water is passed through the jacket 117 to raise the temperature to a temperature equal to or higher than the Tg of the resin particles, and the mixture is stirred and mixed.

[0175] (d) Post-film formation process Cooling is performed by passing cooling water in the range of 10 to 15°C through jacket 117. During this time, the peripheral speed of the stirring blade is set to the peripheral speed in the film-forming process or slower to stir and cool the material, and when the temperature drops below the Tg of the resin particles, usually below 70°C, discharge valve 121 is opened and the resulting toner base particles are discharged from outlet 120.

[0176] <Two-component developer> The toner of the present invention can be used, for example, as a two-component developer for electrophotography containing the toner of the present invention and carrier particles, and the two-component developer can be obtained by mixing the toner of the present invention with the following carrier particles.

[0177] The mixing device used for mixing is not particularly limited, but examples thereof include a Nauta mixer, a W-cone mixer, a V-type mixer, etc. The toner content (toner concentration) in the two-component developer is not particularly limited, but is preferably in the range of 4.0 to 12.0 mass %.

[0178] (carrier particles) The carrier particles are composed of at least a magnetic material, and known carrier particles can be used, such as coated carrier particles in which the surface of core particles made of at least a magnetic material is coated with a resin, and dispersed carrier particles in which magnetic material fine powder is dispersed in a resin.

[0179] The average particle size of the carrier particles is preferably in the range of 10 to 500 μm, more preferably 30 to 100 μm, in terms of volume-based median particle size (D50) measured in the same manner as for the toner base particles.

[0180] The carrier particles are preferably coated carrier particles from the viewpoint of suppressing adhesion of the carrier particles to the photoreceptor. Hereinafter, coated carrier particles will be described.

[0181] (Core particles) The core particles in the coated carrier particles are composed of at least a magnetic material, for example, a material that is strongly magnetized in a direction by a magnetic field. Examples of magnetic materials include ferromagnetic metals such as iron, nickel, and cobalt, alloys or compounds containing these metals, and alloys that become ferromagnetic when heat-treated. These magnetic materials may be used alone or in combination of two or more.

[0182] Examples of ferromagnetic metals and alloys or compounds containing these metals include iron, ferrite represented by the following formula (a), and magnetite represented by the following formula (b). M in formulas (a) and (b) represents a monovalent or divalent metal, and specific examples include Mn, Fe, Ni, Co, Cu, Mg, Sr, Zn, Cd, and Li. These metals may be used alone or in combination of two or more. Formula (a): MO·Fe2O3 Formula (b): MFe2O4

[0183] Examples of alloys that become ferromagnetic upon heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide.

[0184] The magnetization of the core particles that make up the carrier particles is 30 to 75 A·m 2 / kg, and residual magnetization is 5.0 A m 2 By using core particles having such magnetic properties, partial aggregation of the carrier particles is prevented and the two-component developer is uniformly dispersed on the surface of the developer transport member, so that a uniform, high-resolution toner image can be formed without uneven density.

[0185] The magnetic material used for the core particles is preferably ferrite, from the viewpoint of obtaining favorable magnetic properties. Furthermore, the ferrite is preferably a porous particle having pores, and the pores are preferably filled with resin. By adopting such a configuration, the specific gravity can be made relatively small, which can prevent the carrier from cracking or chipping due to the impact force of stirring in the developing machine, thereby obtaining a carrier with excellent durability.

[0186] (Carrier coating resin) As the coating resin constituting the coated carrier particles, known resins used for coating core particles of carrier particles can be used. From the viewpoint of reducing the moisture adsorption of the carrier particles and increasing the adhesion of the coating layer to the core particles, the coating resin is preferably a resin having a cycloalkyl group.

[0187] Examples of the cycloalkyl group include a cyclohexyl group, a cyclopentyl group, a cyclopropyl group, a cyclobutyl group, a cycloheptyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group. Among these, a cyclohexyl group or a cyclopentyl group is preferred, and a cyclohexyl group is more preferred from the viewpoint of adhesion between the coating resin layer and the core particles (e.g., ferrite particles).

[0188] The coating resin can be obtained, for example, by polymerizing a polymerizable compound containing a monomer having a cycloalkyl group. As the monomer having a cycloalkyl group, a cycloalkyl ester of methacrylic acid is preferably used. The coating resin may also be a copolymer of the monomer and a monomer not having a cycloalkyl group, for example, an alkyl ester of methacrylic acid (but not having a cyclic structure).

[0189] The weight average molecular weight (Mw) of the coating resin can be measured by gel permeation chromatography (GPC) and is preferably within the range of 10,000 to 800,000, and more preferably within the range of 100,000 to 750,000, based on polystyrene standards.

[0190] The cycloalkyl group content in the coating resin is preferably within the range of 10 to 90% by mass. The cycloalkyl group content in the coating resin can be determined, for example, by pyrolysis-gas chromatography / mass spectrometry (P-GC / MS) or 1H-NMR.

[0191] From the viewpoint of achieving both durability and low electrical resistance of the carrier, the thickness of the coating resin layer on the carrier particles is preferably within the range of 0.05 to 4.0 μm, and more preferably within the range of 0.2 to 3.0 μm. By keeping the thickness within the above range, it is possible to set the chargeability and durability within preferred ranges.

[0192] ≪Image forming method≫ An image forming method using the electrophotographic toner of the present invention will be described. The electrophotographic toner of the present invention is used in an image forming method using a known electrophotographic system. Specifically, it is preferably used in an image forming method having the following steps:

[0193] 1) An electrostatic image forming process in which an electrostatic image is formed on the surface of an image carrier. 2) A developing step in which the electrostatic image formed on the surface of the image carrier is developed with a photoluminescent toner to form a photoluminescent toner image. 3) a transfer step of transferring the glossy toner image onto a transfer-receiving material; 4) a fixing step of fixing the glossy toner image transferred onto the surface of the transfer medium;

[0194] The transfer step 3) may use an intermediate transfer member that mediates the transfer of the glitter toner image from the image carrier to the transfer-receiving member. The method may further include a cleaning step of removing residual toner from the surface of the image carrier after transfer.

[0195] The image obtained by this image forming method is preferably an image having a color toner image formed with at least a yellow toner, a magenta toner, a cyan toner, and a black toner, on top of a glossy toner image formed with the toner of the present invention. Furthermore, it is more preferable that the image has a color metallic color, having a color toner image formed with at least a color toner, on top of a glossy toner image formed with the glossy toner. Because the glossy toner image formed with the toner of the present invention has high gloss, even when used as a lower layer of a color toner image, the glossiness is fully exhibited in the image, and a good color metallic image is particularly suitably formed.

[0196] The recording medium (also referred to as "media," "recording material," "recording paper," "recording paper," etc.) can be any commonly used recording medium, and is not particularly limited as long as it can hold a toner image formed by a known image forming method using an image forming apparatus or the like. Examples of recording media include coated printing paper such as plain paper ranging from thin paper to thick paper, high-quality paper, art paper, and coated paper, commercially available Japanese paper and postcard paper, plastic film for overhead projectors, cloth, soft transparent film, and synthetic paper such as Yupo paper. The present invention is particularly effective when outputting onto special recording media such as colored paper, black paper, and transparent film.

[0197] <Image forming device> An image forming apparatus used when forming an image using the electrophotographic toner of the present invention will be described.

[0198] An example of an image forming apparatus is a drum tandem type in which an image forming unit having a developing machine and a photosensitive member is installed for each toner (the toner of the present invention and colored toner), and the toner images formed on each photosensitive member are sequentially transferred onto an intermediate transfer member and superimposed, and then transferred all at once onto a recording medium, fixed using a heat roller system, and a visible image (fixed image) is formed.

[0199] Fig. 6 is a schematic cross-sectional view showing an example of a drum tandem type image forming apparatus suitable for use in the present invention. Fig. 6 shows an example in which the toner of the present invention and color toners including yellow toner (By), magenta toner (Bm), cyan toner (Bc), and black toner (Bk) are used.

[0200] The image forming apparatus GS shown in Figure 6 is what is called a tandem color image forming apparatus. In the image forming apparatus GS, image forming units that form toner images using photoluminescent toner and color toner (yellow, magenta, cyan, and black) are arranged along the direction of movement of an intermediate transfer body 36, and the photoluminescent toner images and color toner images formed on the photosensitive bodies of the image forming units are multiple-transferred and superimposed onto the intermediate transfer body, and then transferred collectively onto a recording medium.

[0201] 6, an original image placed on the image reading device SC is scanned and exposed by an optical system and read into a line image sensor CCD. An analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in an image processing section, and then an image data signal is sent to an exposure optical system 33 as an image writing means.

[0202] There are no particular restrictions on the intermediate transfer body 36, and a drum type or an endless belt type can be used. The following describes the case where an endless belt type is used.

[0203] 6, five process units 100 are provided around the periphery of intermediate transfer body 36 for forming toner images of each color, yellow (Y), magenta (M), cyan (C), black (K), and a glossy toner image (W). The process units 100, as means for forming color toner images and glossy toner images, are arranged in a vertical column along intermediate transfer body 36 with respect to the rotation direction of intermediate transfer body 36, which is the vertical direction indicated by the arrow in the figure, and are arranged in the following order: process unit Y for yellow (Y), process unit M for magenta (M), process unit C for cyan (C), process unit K for black (K), and process unit W for glossy toner image (W).

[0204] All five process units 100 have a common structure, and each comprises a photosensitive drum 31, a charger 32 as a charging means, an exposure optical system 33 as an image writing means, a developing device (developing machine) 34, and a photosensitive cleaning device 190 as a photosensitive cleaning means.

[0205] Photosensitive drum 31 is, for example, a cylindrical substrate made of a metal member such as aluminum and having an outer diameter of about 40 to 100 mm, on the outer periphery of which a photosensitive layer having a layer thickness (film thickness) of about 20 to 40 μm is formed. Photosensitive drum 31 rotates in the direction of the arrow with the substrate grounded by power from a drive source (not shown), at a linear velocity of, for example, about 80 to 280 mm / s, preferably 220 mm / s.

[0206] An image forming unit consisting of a charger 32 as a charging means, an exposure optical system 33 as an image writing means, and a developing device (developing machine) 34 is arranged around the photosensitive drum 31 in the direction of rotation of the photosensitive drum 31 as indicated by the arrow in the figure.

[0207] The charger 32 serving as charging means is attached in close proximity to and facing the photosensitive drum 31 in a direction parallel to the rotation axis of the photosensitive drum 31. The charger 32 has a discharge wire as a corona discharge electrode that applies a predetermined potential to the photosensitive layer of the photosensitive drum 31, and performs charging (negative charging in this embodiment) by corona discharge of the same polarity as the toner, thereby applying a uniform potential to the photosensitive drum 31.

[0208] The exposure optical system 33, which is an image writing means, rotates and scans laser light emitted from a semiconductor laser (LD) light source (not shown) in the main scanning direction using a rotating polygonal mirror (no symbol), and exposes (writes an image) the photosensitive drum 31 using an electrical signal corresponding to the image signal via an fθ lens (no symbol), a reflecting mirror (no symbol), etc., thereby forming an electrostatic charge image corresponding to the original image on the photosensitive layer of the photosensitive drum 31.

[0209] The developing device 34 as a developing means contains two-component developers of the colors yellow (Y), magenta (M), cyan (C), and black (K), and the glossy toner image (W), which are charged to the same polarity as the charging polarity of the photosensitive drum 31. The two-component developers of the respective colors contain yellow toner (By), magenta toner (Bm), cyan toner (Bc), and black toner (Bk), as well as the glossy toner of the present invention, corresponding to the yellow (Y), magenta (M), cyan (C), and black (K) colors, and the glossy toner image (W).

[0210] The developing device 34 includes a developing roller 34a, which is a cylindrical developer carrier made of non-magnetic stainless steel or aluminum material, having a thickness of, for example, 0.5 to 1 mm and an outer diameter of 15 to 25 mm. The developing roller 34a is kept out of contact with the photosensitive drum 31 by abutting rollers (not shown), with a predetermined gap, for example, 100 to 1000 μm, between the developing roller 34a and the photosensitive drum 31, and rotates in the same direction as the rotation of the photosensitive drum 31. During development, a DC voltage of the same polarity as the toner (negative polarity in this embodiment) or a developing bias voltage consisting of an AC voltage superimposed on a DC voltage is applied to the developing roller 34a, thereby performing reversal development on the exposed portion on the photosensitive drum 31.

[0211] It is preferable to use a resin belt as the intermediate transfer body 36. The resin belt used has a volume resistivity of 1.0×10 7 ~1.0×10 9 It is preferable that the surface resistivity is in the range of Ω·cm, and the surface resistivity is 1.0×10 10 ~1.0×10 12 It is preferably in the range of Ω / □.

[0212] The resin belt is preferably a semiconductive resin film in which a conductive material is dispersed in engineering plastic such as modified polyimide, thermosetting polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, or nylon alloy, and the thickness of the resin film is preferably within the range of 0.05 to 0.5 mm.

[0213] Alternatively, the resin belt may be a semi-conductive rubber belt made of silicone rubber, urethane rubber, or the like with a conductive material dispersed therein, and the thickness of the rubber belt is preferably within the range of 0.5 to 2 mm.

[0214] The intermediate transfer member 36 is wound around a plurality of roller members including a tension roller 36a and a backup roller 36B facing the secondary transfer member, and is supported so as to be rotatable in the vertical direction.

[0215] The primary transfer roller 37, which serves as the first transfer means for each color, is made of a roller-shaped conductive member made of foamed rubber such as silicone or urethane, and is disposed opposite the photosensitive drum 31 for each color with the intermediate transfer body 36 sandwiched therebetween, pressing against the back surface of the intermediate transfer body 36 to form a transfer area between the roller and the photosensitive drum 31. A DC constant current of the opposite polarity to that of the toner (positive polarity in this embodiment) is applied to the primary transfer roller 37 by constant current control, and the toner image on the photosensitive drum 31 is transferred onto the intermediate transfer body 36 by a transfer electric field formed in the transfer area.

[0216] The toner image transferred onto the intermediate transfer body 36 is transferred onto a recording medium P. A detection sensor 38 is provided on the periphery of the intermediate transfer body 36 to measure the density of the patch image toner.

[0217] In addition, a cleaning device 190A is provided to clean residual toner on the intermediate transfer body .

[0218] Furthermore, a secondary transfer device 70 is provided to clean the patch image toner on the secondary transfer member 37A.

[0219] Next, an image forming method using the image forming apparatus shown in FIG. 6 will be described.

[0220] When image recording starts, a photosensitive drum drive motor (not shown) starts, the yellow (Y) photosensitive drum 31 rotates in the direction indicated by the arrow in the figure, and the Y charger 32 applies a potential to the Y photosensitive drum 31.

[0221] After a potential is applied to the Y photoconductor drum 31, the Y exposure optical system 33 performs exposure (image writing) using an electrical signal corresponding to a first color signal, i.e., Y image data, and an electrostatic charge image corresponding to a yellow (Y) image is formed on the Y photoconductor drum 31. This electrostatic charge image is reverse-developed by the Y developing device 34, and a toner image (By) made of yellow toner (By) is formed on the Y photoconductor drum 31. The Y toner image (By) formed on the Y photoconductor drum 31 is transferred onto the intermediate transfer body 36 by a primary transfer roller 37 serving as primary transfer means.

[0222] Next, a potential is applied to the M photoconductor drum 31 by the magenta (M) charger 32. After the M photoconductor drum 31 has been applied with a potential, it is exposed (image written) by the M exposure optical system 33 using an electrical signal corresponding to a first color signal, i.e., M image data, and an electrostatic charge image corresponding to the magenta (M) image is formed on the M photoconductor drum 31. This electrostatic charge image is reverse-developed by the M developing device 34, and a toner image (Bm) made of magenta toner (Bm) is formed on the M photoconductor drum 31. The M toner image (Bm) formed on the M photoconductor drum 31 is transferred onto the intermediate transfer body 36 by the primary transfer roller 37, which serves as primary transfer means, so as to be superimposed on the Y toner image (By).

[0223] By a similar process, a toner image (Bc) made of cyan toner (Bc) formed on the cyan (C) photosensitive drum 31 and a toner image (Bk) made of black toner (Bk) formed on the black (K) photosensitive drum 31 are sequentially superimposed on the intermediate transfer body 36, and a superimposed color toner image made of toner image (By), toner image (Bm), toner image (Bc) and toner image (Bk) is formed on the peripheral surface of the intermediate transfer body 36.

[0224] Next, the photosensitive drum 31 for the glossy toner image (W) is rotated in the direction shown by the arrow in the figure, and a potential is applied to the W photosensitive drum 31 by the W charger 32. After the W photosensitive drum 31 has been applied with a potential, it is exposed (image written) by the W exposure optical system 33 using an electrical signal corresponding to the first color signal, i.e., the W image data, and an electrostatic charge image corresponding to the glossy toner image (W) is formed on the W photosensitive drum 31. This electrostatic charge image is reverse-developed by the W developing device 34, and a glossy toner image made of glossy toner is formed on the W photosensitive drum 31.

[0225] The glossy toner image formed on the W photosensitive drum 31 is transferred onto the intermediate transfer body 36 by a primary transfer roller 37 serving as a primary transfer means. As a result, a superimposed color toner image consisting of a toner image (By), a toner image (Bm), a toner image (Bc), and a toner image (Bk) is formed on the circumferential surface of the intermediate transfer body 36, and a glossy toner image is further formed on the color toner image.

[0226] Any toner remaining on the circumferential surface of each photosensitive drum 31 after transfer is cleaned off by a cleaning blade of a photosensitive drum cleaning device 190 .

[0227] Meanwhile, recording media P as recording paper stored in paper feed cassettes 50A, 50B, and 50C are fed by a feed roller 51 and a feed roller 52A provided in each of the paper feed cassettes 50A, 50B, and 50C. The recording media P are transported on a transport path 52 by transport rollers 52B, 52C, and 52D, and are transported via a registration roller 53 to a secondary transfer member 37A as a secondary transfer means to which a voltage of the opposite polarity to that of the toner (positive polarity in this embodiment) is applied.

[0228] In the transfer region of the secondary transfer member 37A, the superimposed color toner image formed on the intermediate transfer body 36 and the glossy toner image on the color toner image are transferred together onto the recording medium P with the glossy toner image facing the recording medium P. This results in an image in which the glossy toner image and the color toner image are layered in that order on the recording medium.

[0229] The recording medium P onto which the image in which the color toner image is layered in that order on top of the glossy toner image has been transferred is heated and pressurized in a nip formed by the heating roller 47a and pressure belt 47b of the fixing device 47, and is then sandwiched between paper discharge rollers 54 and placed on a paper discharge tray 55 outside the machine. The toner is fixed to the recording medium P by being heated and pressurized in the nip.

[0230] After a glossy toner image (e.g., a solid glossy toner image) and a color toner image are transferred onto the recording medium P by the secondary transfer member 37A as a secondary transfer means, the residual toner on the intermediate transfer body 36 from which the recording medium P has been separated by curvature is removed by the intermediate transfer body cleaning device 190A.

[0231] Furthermore, the patch image toner on the secondary transfer member 37A is cleaned by a cleaning blade 71 of the secondary transfer device . [Example]

[0232] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass." In the following examples, unless otherwise specified, all operations were carried out at room temperature (25°C).

[0233] [Preparation of Toner Particles 1] <Preparation of Resin Particles α> (Binder resin A: Polyester synthesis) The following components were placed in a 10 L four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and reacted at 230°C for 8 hours, and then at 8.3 kPa for 1 hour.

[0234] Bisphenol A-PO adduct (BPA-PO) 4900 parts by mass Bisphenol A-EO adduct (BPA-EO) 1950 parts by mass Terephthalic acid 1,328 parts by mass Tin(II) 2-ethylhexanoate 40 parts by mass Gallic acid 1 part by mass

[0235] Then, the temperature was lowered to 210° C., and the following components were further added, and the reaction was continued until the desired softening point was reached, thereby obtaining a binder resin A (polyester).

[0236] Trimellitic anhydride 5 parts by mass Fumaric acid 5 parts by mass Tertiary butyl catechol 5 parts by mass

[0237] (Preparation of Resin Particles α) The following components were premixed for 1 minute using a Henschel mixer, and then melt-kneaded using a twin-screw extruder (PCM-87, manufactured by Ikegai Iron Works).

[0238] Binder resin A 100 parts by mass Charge control agent (negative charge control agent, Bontron E-304, manufactured by Orient Chemical Industries Co., Ltd.) 0.5 parts by mass Wax (paraffin wax, melting point: 79°C, HNP-9, manufactured by Nippon Seiro Co., Ltd.) 3 parts by mass

[0239] The melt-kneading conditions were as follows: the feed rate of the raw materials was 3.0 kg / min, the screw rotation speed of the kneading section was set to 200 rpm, and the barrel temperature was set to 170°C so that the temperature of the kneaded material measured at the discharge section was 160°C.

[0240] The obtained kneaded mixture was cooled to 20° C. or less while being rolled with a cooling roll, and the cooled molten kneaded mixture was coarsely pulverized to about 3 mm using a Rotoplex (manufactured by Toa Kikai Co., Ltd.).

[0241] The obtained coarsely crushed material was coarsely crushed using a cutter mill (manufactured by Nara Machinery Works) to a volume median particle size (D50) in the range of 1.5 to 2.5 mm, and then finely crushed using a collision plate jet mill (model I-20, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain resin particles α.

[0242] <Preparation of Toner Base Particles 1> The following components were placed in a high-speed mixer equipped with a stirring blade and mixed with stirring at 120°C for 1 hour, to obtain toner base particles 1 in which a glittering aluminum pigment was coated with a resin by a dry coating method using the action of mechanical impact force.

[0243] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 100 parts by mass

[0244] <Preparation of Toner Particle 1 (External Addition Treatment)> The following components were placed in a Henschel mixer (FM20C / I, manufactured by Nippon Coke & Engineering Co., Ltd.), and the rotation speed was set so that the blade tip peripheral speed was 50 m / s. Toner particles 1 were obtained by stirring for 20 minutes.

[0245] Toner base particles 1 100 parts by mass Silica fine particles 1 0.8 parts by mass

[0246] [Preparation of toner particles 2] <Preparation of Resin Particles β> (Binder resin B: Synthesis of styrene-acrylic resin) (First stage polymerization) The following components were placed in a reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen inlet, and dissolved to prepare an aqueous surfactant solution. The anionic surfactant was sodium dodecyl sulfate (C 10 H 21 (OCH2CH2)2SO3Na).

[0247] Anionic surfactant 4 parts by mass Ion-exchanged water 3040 parts by mass

[0248] The following components were dissolved to prepare a polymerization initiator solution, which was then added to the above aqueous surfactant solution, and the liquid temperature was raised to 75°C.

[0249] Potassium persulfate (KPS) 10 parts by mass Ion-exchanged water 400 parts by mass

[0250] Next, a polymerizable monomer solution prepared by mixing the following components was added dropwise to this solution over 1 hour. After the addition, the mixture was heated and stirred at 75°C for 2 hours to carry out polymerization (first-stage polymerization), thereby preparing a dispersion of styrene-acrylic resin microparticles (1).

[0251] Styrene 532 parts by mass n-Butyl acrylic acid 200 parts by mass Methacrylic acid 68 parts by mass n-Octyl mercaptan 16.4 parts by mass

[0252] The mass average molecular weight (Mw) of the styrene-acrylic resin microparticles (1) in the dispersion was 16,500. The mass average molecular weight (Mw) of the resin was determined from the molecular weight distribution measured by gel permeation chromatography (GPC). Hereinafter, the mass average molecular weight (Mw) of the resin is the Mw measured by the same method.

[0253] Specifically, the sample was added to tetrahydrofuran (THF) to a concentration of 1 mg / mL, dispersed for 5 minutes using an ultrasonic disperser at room temperature, and then filtered through a 0.2 μm pore membrane filter to prepare the sample solution. Using a GPC system "HLC-8120GPC" (manufactured by Tosoh Corporation) and a column "TSKguard column + TSKgel Super HZ-m triple column" (manufactured by Tosoh Corporation), tetrahydrofuran was used as the carrier solvent at a flow rate of 0.2 mL / min while the column temperature was maintained at 40°C.

[0254] 10 μL of the prepared sample solution was injected into the GPC system together with the carrier solvent, and the sample was detected using a refractive index detector (RI detector). The molecular weight distribution of the sample was calculated using a calibration curve measured using monodisperse polystyrene standard particles. The calibration curve was used to calculate the molecular weight distribution of the sample. 2 , 2.1×10 3 , 4×10 3 , 1.75×10 4 , 5.1×10 4 , 1.1×10 5 , 3.9 × 10 5 , 8.6×10 5 , 2 × 10 6 , 4.48×10 6 The measurement was made by measuring 10 polystyrene standard particles (manufactured by Pressure Chemical Co.).

[0255] (Second stage polymerization) The following components were placed in a flask equipped with a stirrer and mixed to prepare a polymerizable monomer solution.

[0256] Styrene 101.1 parts by mass n-Butyl acrylic acid 62.2 parts by mass Methacrylic acid 12.3 parts by mass n-Octyl mercaptan 1.75 parts by mass

[0257] Furthermore, the following components were added and dissolved by raising the liquid temperature to 90°C to prepare a monomer solution (m). Paraffin wax HNP-57 (manufactured by Nippon Seiro Co., Ltd.) 93.8 parts by mass

[0258] The following components were placed in a separate container and dissolved to prepare an aqueous surfactant solution. The liquid temperature was then raised to 98° C. However, the same anionic surfactant as in the first polymerization step was used.

[0259] Anionic surfactant 3 parts by mass Ion-exchanged water 1560 parts by mass

[0260] The following components were added to the above surfactant aqueous solution, and mixed and dispersed for 8 hours using a mechanical disperser, Clearmix (manufactured by M Technique), which has a circulation path, to prepare a dispersion of emulsified particles (oil droplets) with a particle size of 340 nm.

[0261] Dispersion of styrene-acrylic resin particles (1) (solid content) 32.8 parts by mass Monomer solution (m) 271.15 parts by mass

[0262] To this dispersion, a polymerization initiator solution prepared by dissolving the following components was added, and polymerization (second-stage polymerization) was carried out by heating and stirring at 98°C for 12 hours to prepare a dispersion of styrene-acrylic resin microparticles (2). The mass average molecular weight (Mw) of the styrene-acrylic resin microparticles (2) in the dispersion was 23,000.

[0263] Potassium persulfate 6 parts by mass Ion-exchanged water 200 parts by mass

[0264] (Third stage polymerization) To the dispersion of styrene-acrylic resin fine particles (2) obtained in the second polymerization step, a polymerization initiator solution prepared by dissolving the following components was added.

[0265] Potassium persulfate 5.45 parts by mass Ion-exchanged water 220 parts by mass

[0266] A polymerizable monomer solution prepared by dissolving the following components was then added dropwise to this dispersion over a period of 1 hour at a temperature of 80°C. After the completion of the addition, polymerization (third-stage polymerization) was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28°C to obtain a dispersion of styrene-acrylic resin microparticles (3). The mass average molecular weight (Mw) of the styrene-acrylic resin microparticles (3) in the dispersion was 26,800. The obtained polymer was washed and dried to obtain binder resin B (styrene-acrylic resin).

[0267] Styrene 293.8 parts by mass n-Butylacrylic acid 154.1 parts by mass n-Octyl mercaptan 7.08 parts by mass

[0268] (Binder resin C: synthesis of crystalline polyester) The following components were placed in a heated and dried Erlenmeyer flask, and the air inside the vessel was removed by reducing the pressure. The atmosphere was then replaced with nitrogen gas to create an inert atmosphere, and the mixture was refluxed at 180°C for 5 hours with mechanical stirring. The temperature was gradually increased while maintaining the inert atmosphere, and stirring was continued at 200°C for 3 hours to obtain a viscous liquid product. The molecular weight of this product was measured by GPC while air-cooling, and when the weight average molecular weight (Mw) reached 15,000, the pressure was released to terminate the polycondensation reaction, yielding a crystalline polyester.

[0269] Dodecanedioic acid (1,10-1,10-decanedicarboxylic acid) 355.8 parts by mass 1,9-nonanediol 254.3 parts by mass Stannous octoate 3.21 parts by mass

[0270] An appropriate amount of methyl ethyl ketone and isopropyl alcohol was added to a reaction vessel equipped with an anchor blade to provide stirring power. The above crystalline polyester, coarsely ground using a hammer mill, was gradually added and stirred until completely dissolved, yielding a polyester solution that became an oil phase. A small amount of dilute aqueous ammonia was added dropwise to the stirred oil phase, and then this oil phase was added dropwise to ion-exchanged water to cause phase inversion emulsification. The solvent was then removed under reduced pressure using an evaporator. Crystalline polyester microparticles were dispersed in the reaction system, and ion-exchanged water was added to the dispersion to adjust the solids content to 20% by mass, yielding crystalline polyester microparticle dispersion (1). The resulting crystalline polyester was washed and dried to obtain binder resin C (crystalline polyester).

[0271] (Binder resin D: synthesis of amorphous polyester) The following components were added to a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a temperature sensor and a rectification column.

[0272] Terephthalic acid 139.5 parts by mass Isophthalic acid 15.5 parts by mass 2,2-bis(4-hydroxyphenyl)propane propylene oxide 2-mol adduct (molecular weight = 460) 290.4 parts by mass 2,2-bis(4-hydroxyphenyl)propane ethylene oxide 2-mol adduct (molecular weight 404) 60.2 parts by mass

[0273] The temperature of the reaction system was raised to 190°C over 1 hour, and after confirming that the reaction system was uniformly stirred, the following catalyst was added. While distilling off the produced water, the temperature of the reaction system was raised from the same temperature to 240°C over 6 hours, and the dehydration condensation reaction was continued for 6 hours while maintaining the temperature at 240°C, yielding an amorphous polyester. The obtained amorphous polyester had a mass average molecular weight (Mw) of 15,000. Stannous octoate 3.21 parts by mass

[0274] The obtained amorphous polyester was subjected to the same procedure as in the preparation of the dispersion of crystalline polyester microparticles to prepare a dispersion of amorphous polyester microparticles (1) with a solid content of 20 mass %. The obtained amorphous polyester was washed and dried to obtain binder resin D (amorphous polyester).

[0275] (Preparation of Resin Particles β) The following components were premixed for 1 minute using a Henschel mixer, and then melt-kneaded using a twin-screw extruder (PCM-87, manufactured by Ikegai Iron Works).

[0276] Binder resin B (styrene-acrylic resin) 200 parts by mass Binder resin C (crystalline polyester) 20 parts by mass Binder resin D (amorphous polyester) 30 parts by mass Charge control agent (negative charge control agent, Bontron E-304, manufactured by Orient Chemical Industries Co., Ltd.) 0.2 parts by mass

[0277] The melt-kneading conditions were as follows: the feed rate of the raw materials was 3.0 kg / min, the screw rotation speed of the kneading section was set to 200 rpm, and the barrel temperature was set to 170°C so that the temperature of the kneaded material measured at the discharge section was 160°C.

[0278] The obtained kneaded mixture was cooled to 20° C. or less while being rolled with a cooling roll, and the cooled molten kneaded mixture was coarsely pulverized to about 3 mm using a Rotoplex (manufactured by Toa Kikai Co., Ltd.).

[0279] The obtained coarsely crushed material was coarsely crushed using a cutter mill (manufactured by Nara Machinery Works) to a volume median particle size (D50) in the range of 1.5 to 2.5 mm, and then finely crushed using a collision plate jet mill (model I-20, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain resin particles β.

[0280] <Preparation of Toner Base Particles 2> The following components were placed in a high-speed mixer equipped with a stirring blade and mixed with stirring at 120°C for 1 hour, to obtain toner base particles 2 in which a glittering aluminum pigment was coated with a resin by a dry coating method using the action of mechanical impact force.

[0281] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 100 parts by mass

[0282] <Preparation of Toner Particles 2 (External Addition Treatment)> The following components were placed in a Henschel mixer (FM20C / I, manufactured by Nippon Coke & Engineering Co., Ltd.), and the rotation speed was set so that the blade tip peripheral speed was 50 m / s. Toner particles 1 were obtained by stirring for 20 minutes.

[0283] Toner base particles 2 100 parts by mass Silica fine particles 1 0.8 parts by mass

[0284] [Preparation of Toner Particles 3] Toner particles 3 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0285] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 200 parts by mass

[0286] [Preparation of Toner Particle 4] Toner particles 4 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0287] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 200 parts by mass

[0288] [Preparation of Toner Particles 5] Toner particles 5 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0289] Aluminum pigment 2 (average major axis diameter 32 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 150 parts by mass

[0290] [Preparation of Toner Particles 6] Toner particles 6 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0291] Aluminum pigment 2 (average major axis diameter 32 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 150 parts by mass

[0292] [Preparation of Toner Particles 7] Toner particles 7 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0293] Aluminum pigment 3 (average major axis diameter 2.8 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 60 parts by mass

[0294] [Preparation of Toner Particles 8] Toner particles 8 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0295] Aluminum pigment 3 (average major axis diameter 2.8 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 60 parts by mass

[0296] [Preparation of Toner Particles 9] Toner particles 9 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0297] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 35 parts by mass

[0298] [Preparation of Toner Particles 10] Toner particles 10 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0299] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 35 parts by mass

[0300] [Preparation of Toner Particles 11] Toner particles 11 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0301] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 500 parts by mass

[0302] [Preparation of Toner Particles 12] Toner particles 12 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0303] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 500 parts by mass

[0304] [Preparation of Toner Particles 13] Toner particles 13 were prepared in the same manner as toner particles 1, except that the mixture was placed in a high-speed mixer equipped with a stirring blade and stirred and mixed at 120° C. for 1 hour and 30 minutes.

[0305] [Preparation of Toner Particles 14] Toner particles 14 were prepared in the same manner as toner particles 2, except that the mixture was placed in a high-speed mixer equipped with a stirring blade and stirred and mixed at 120° C. for 1 hour and 30 minutes.

[0306] [Preparation of Toner Particles 15] Toner particles 15 were prepared in the same manner as toner particles 1, except that the mixture was placed in a high-speed mixer equipped with a stirring blade and stirred and mixed at 120° C. for 25 minutes.

[0307] [Preparation of Toner Particles 16] Toner particles 16 were prepared in the same manner as toner particles 2, except that the mixture was placed in a high-speed mixer equipped with a stirring blade and stirred and mixed at 120° C. for 25 minutes.

[0308] [Preparation of Toner Particles 17] Toner particles 17 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0309] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 25 parts by mass

[0310] [Preparation of Toner Particles 18] Toner particles 18 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0311] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 25 parts by mass

[0312] [Preparation of Toner Particles 19] Toner particles 19 were prepared in the same manner as toner particles 1, except that the components added were changed to the following components.

[0313] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle α 550 parts by mass

[0314] [Preparation of Toner Particles 20] Toner particles 20 were prepared in the same manner as toner particles 2, except that the components added were changed to the following components.

[0315] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 50 parts by mass Resin particle β 550 parts by mass

[0316] [Preparation of Toner Particles 21] Toner particles 21 were prepared in the same manner as toner particles 1, except that the mixture was placed in a high-speed mixer equipped with a stirring blade and stirred and mixed at 120° C. for 15 minutes.

[0317] [Preparation of Toner Particles 22] Toner particles 22 were prepared in the same manner as toner particles 2, except that the mixture was placed in a high-speed mixer equipped with a stirring blade and stirred and mixed at 120° C. for 15 minutes.

[0318] [Preparation of Toner Particles 23] The following components were premixed for 1 minute using a Henschel mixer, and then melt-kneaded using a twin-screw extruder (PCM-87, manufactured by Ikegai Iron Works).

[0319] Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 100 parts by mass Binder resin α 100 parts by mass Charge control agent (negative charge control agent, Bontron E-304, manufactured by Orient Chemical Industries Co., Ltd.) 0.5 parts by mass Wax (paraffin wax, melting point: 79°C, HNP-9, manufactured by Nippon Seiro Co., Ltd.) 3 parts by mass

[0320] The melt-kneading conditions were as follows: the feed rate of the raw materials was 3.0 kg / min, the screw rotation speed of the kneading section was set to 200 rpm, and the barrel temperature was set to 170°C so that the temperature of the kneaded material measured at the discharge section was 160°C.

[0321] The obtained kneaded mixture was cooled to 20° C. or less while being rolled with a cooling roll, and the cooled molten kneaded mixture was coarsely pulverized to about 3 mm using a Rotoplex (manufactured by Toa Kikai Co., Ltd.).

[0322] The obtained coarsely crushed material was coarsely crushed using a cutter mill (manufactured by Nara Machinery Works) to a volume median particle size (D50) in the range of 1.5 to 2.5 mm, and then finely crushed using a collision plate type jet mill (model I-20, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) The crushed material was then classified using an air classifier (model DSF, manufactured by Nippon Pneumatic Mfg. Co., Ltd.) to obtain toner base particles 23. Then, in the same manner as in the case of the toner particles 1, external addition treatment was carried out to obtain toner particles 23.

[0323] [Preparation of Toner Particles 24] <Preparation of Resin Particles γ> (Synthesis of binder resin E) The following components were placed in a heated and dried two-necked flask, and nitrogen gas was introduced into the vessel to maintain an inert atmosphere. The temperature was raised while stirring, and then a polycondensation copolymerization reaction was carried out at 160°C for 7 hours. Thereafter, the pressure was gradually reduced to 1.3 kPa (10 Torr), and the temperature was raised to 220°C, and maintained at this temperature for 4 hours.

[0324] Bisphenol A-EO adduct 216 parts by mass Ethylene glycol 38 parts by mass Tetrabutoxy titanate 0.037 parts by mass

[0325] The pressure was returned to normal pressure once, 9 parts by mass of trimellitic anhydride was added, and the pressure was gradually reduced again to 1.3 kPa (10 Torr), and the mixture was kept at 220° C. for 1 hour to obtain binder resin E.

[0326] (Preparation of Resin Particle γ Dispersion) The following components were placed in a 1000 mL separable flask, heated to 70° C., and stirred with a Three-One Motor (manufactured by Shinto Scientific Co., Ltd.) to prepare a resin mixture.

[0327] Binder resin E 160 parts by mass Ethyl acetate 233 parts by mass Sodium hydroxide aqueous solution (0.3mol / L) 0.1 part by mass

[0328] While further stirring this resin mixture, 373 parts by mass of ion-exchanged water was gradually added to cause phase inversion emulsification, and the solvent was removed to obtain a resin particle γ dispersion (solid content concentration: 30%).

[0329] (Preparation of release agent dispersion) The following components were mixed and heated to 95°C, and dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA). After that, a dispersion treatment was carried out for 360 minutes using a Manton-Gaulin high-pressure homogenizer (Gaulin), to prepare a release agent dispersion liquid (solid concentration: 20%) in which release agent particles having a volume average particle size of 0.23 µm were dispersed.

[0330] Carnauba wax (RC-160, manufactured by Toa Kasei Co., Ltd.) 50 parts by weight Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1 part by mass Ion-exchanged water 200 parts by mass

[0331] <Preparation of Toner Particles 24> The following components were placed in a 2 L cylindrical stainless steel container and dispersed and mixed for 10 minutes using a homogenizer (Ultra Turrax T50, manufactured by IKA) at a rotation speed of 4000 rpm while applying shear force.

[0332] Resin particle γ dispersion liquid 450 parts by mass Release agent dispersion 50 parts by mass Aluminum pigment 1 (average major axis diameter 12 μm, average thickness 0.3 μm) 21.74 parts by mass Nonionic surfactant (IGEPAL (registered trademark) CA897, Sigma-Aldrich) 1.4 parts by mass

[0333] Next, the following component was gradually added dropwise as a flocculant, and the homogenizer was rotated at 5000 rpm for 15 minutes to disperse and mix the mixture, thereby obtaining a raw dispersion liquid. 1.75 parts by mass of 10% by mass aqueous solution of polyaluminum chloride in nitric acid

[0334] The raw material dispersion was then transferred to a polymerization vessel equipped with a thermometer and a stirrer using two paddle stirring blades to form a laminar flow, and heated with a mantle heater at a stirring speed of 810 rpm to promote the growth of aggregated particles at 54° C. The pH of the raw material dispersion was adjusted to a range of 2.2 to 3.5 using 0.3 mol / L nitric acid and 1.0 mol / L aqueous sodium hydroxide solution.

[0335] Next, the following components were further added, the temperature was raised to 56° C., and particles of binder resin E were adhered to the surfaces of the aggregated particles while the particle size and shape were confirmed with an optical microscope and Multisizer II. Resin particle γ dispersion liquid 100 parts by mass

[0336] The pH was then adjusted to 8.0, and the temperature was raised to 67.5°C to fuse the aggregated particles. After confirming that the aggregated particles had fused using an optical microscope, the pH was adjusted to 6.0 while maintaining the temperature at 67.5°C. After one hour, heating was stopped and the mixture was cooled at a rate of 1.0°C / min. The mixture was then sieved through a 20 μm mesh, repeatedly washed with water, and dried in a vacuum dryer to obtain toner base particles 24. The volume average particle size of the obtained toner base particles was 12.2 μm. Then, in the same manner as in the case of the toner particles 1, external addition treatment was carried out to obtain toner particles 24.

[0337] [evaluation] <Average major axis diameter of photoluminescent pigment> The average major axis diameter of the bright pigment was measured in an electron micrograph taken using a scanning electron microscope (SEM) "JSM-7401F" (manufactured by JEOL Ltd.), and the number-average major axis diameter for 1,000 bright pigment particles was calculated.

[0338] <Resin part thickness and thickness variation coefficient> A sample of the toner base particles was stained with 3% ruthenium tetroxide (RuO4) vapor for 10 minutes (room temperature) using a vacuum electron staining device "VSC1R1" (Filgen Co., Ltd.), and the stained sample was dispersed in a photocurable resin "D-800" (JEOL Ltd.) and hardened, and the sample was embedded in the photocurable resin.

[0339] The embedded sample was processed onto a flat plate using a razor and fixed to an ion milling sample holder using thermoplastic wax. The cut surface was then ion milled using an ion milling device "SM-09010" (manufactured by JEOL Ltd.) to prepare a sample for cross-sectional observation. Acceleration voltage: 5.0 kV, beam current: 60 μA, set time: 12 hours, ion species: Ar + Ion milling was carried out under the following conditions.

[0340] The cross-sections of the dyed cross-section samples were observed using an ultra-high resolution field emission scanning electron microscope "S-4800" (manufactured by Hitachi High-Technologies Corporation). 100 cross-sections of the toner base particles were selected for observation and photographed, with the cross-sections being within ±3.0 μm of the mass average particle diameter of the toner base particles.

[0341] The obtained cross-sectional images were photographed at 5000x magnification under conditions of an acceleration voltage of 1.0 kV and WD / 3.0 mm, and the photographic images were used with the image processing and analysis device "LUZEX-AP" (manufactured by Nireco Corporation) to measure the thickness of the resin portion covering the lustrous pigment.

[0342] In the clarified cross-sectional image, the thickness of the resin portion, i.e., the length of the perpendicular line from any point on the contour of the outermost surface of the toner base particle to the surface of the bright pigment, was measured at 20 arbitrary points on the contour of the outermost surface of the toner base particle. Note that the distance between each of the 20 arbitrary points was set to at least 100 nm, and points where the resin had peeled off from the bright pigment and the bright pigment was exposed (i.e., where the thickness was 0 nm) were excluded from the arbitrary points.

[0343] The average value of the thickness of the resin portion at any 20 points on each toner base particle was calculated, and the arithmetic mean value of the thickness of 100 toner base particles was also calculated. Furthermore, the thicknesses of the resin portions at any 20 points were sorted in descending order, and the average of the top five values ​​was taken as the "maximum" thickness, and the average of the bottom five values ​​was taken as the "minimum" thickness. The thickness variation coefficient was calculated for each toner base particle using the following formula, and the arithmetic average value of 100 toner base particles was also calculated. (Equation 2) Variation coefficient = maximum value / minimum value

[0344] <Glitter> The toner was placed in a commercially available color multifunction printer (bizhub PRO C6500, manufactured by Konica Minolta), and an A4-size sheet of fine paper (65 g / m 2 ) on a 2cm x 2cm square patch image (adhesion amount 5g / m 2 A toner image having the above characteristics was output at a fixing temperature of 180°C.

[0345] The resulting toner image was measured using a goniometer (a variable-angle spectral reflectance measuring instrument, Goniophotometer GP-5, manufactured by Murakami Color Research Institute) to measure the brightness L of specular reflection light at a reflection angle of 60° reflected from the surface of the toner image at an incident angle of 60°. * was measured. The calibration is performed with the incident angle set at 60° and the brightness of the specular reflected light at a reflection angle of 60° reflected on the surface of the standard white plate set at 100. * A value of 300 or more was considered to have good brilliance.

[0346] The evaluation results are shown in Table I below. However, for toners 17 and 18, the brightness L * was not measurable.

[0347] [Table 1]

[0348] From the above results, it can be seen that the toner having a relatively thin average thickness of the resin portion of the toner base particle and a relatively small coefficient of variation in thickness is L * It is clear that the toner has excellent brightness, with a value of 300 or more. It is also clear that the toner can be produced by a dry coating method.

[0349] A comparison of toners 1 to 16 and 17 to 24 (examples of the present invention and comparative examples) shows that the resin portion has excellent brilliance because the thickness variation coefficient is in the range of 1.0 to 5.0 and the average thickness is in the range of 0.1 to 1.5 μm (100 to 1500 nm).

[0350] A comparison of toners 1 to 4 and 5 to 8 reveals that when the average major axis diameter of the glitter pigment is in the range of 3 to 30 μm, the glitter is even more excellent. [Explanation of symbols]

[0351] 1. Photoluminescent pigments 2 Resin part 10 Toner base particles 31 Photosensitive drum 32 Charger 33 Exposure Engineering 34 Developing device 36 Intermediate transfer body 37 Primary transfer roller 37A Secondary transfer member 47 Fixing device 70 Secondary transfer device 71 Cleaning blade 100 process units 110 Container 112 Raw material input port 117 Jacket 118 Horizontal Rotating Body 119 Vertical Rotating Body 120 Outlet 122 Motor 190 Photoconductor cleaning device 190A Intermediate transfer body cleaning device GS image forming device SC Image Reader

Claims

1. A method for producing an electrophotographic toner including toner base particles containing at least a resin and a photoluminescent pigment, comprising: the resin coats the bright pigment; The bright pigment is flat, When the bright pigment is placed on a smooth surface and the surface visible from above is the surface of the bright pigment, an average thickness from a point on the contour of the outermost surface of the toner base particle in a cross-sectional image of the toner base particle to the surface of the bright pigment is within a range of 0.1 to 1.5 μm; a coefficient of variation in thickness from a point on the contour of the outermost surface of the toner base particle to the surface of the bright pigment in a cross-sectional image of the toner base particle is within a range of 1.0 to 5.0; The content of the bright pigment is 25 to 140 parts by mass relative to 100 parts by mass of the resin, preparing resin particles containing the resin and additives; a step of mixing the resin particles and the bright pigment, heating the mixture to melt the resin in the resin particles, and coating the resin on the surface of the bright pigment by a mechanical impact force to prepare the toner base particles, 1. A method for producing a toner for electrophotography, comprising:

2. The average major axis diameter of the bright pigment is in the range of 3 to 30 μm.

2. The method for producing a toner for electrophotography according to claim 1.

Images