Image forming method

Abstract

To provide an image forming method with which it is possible to achieve excellent fixability to a recording medium long in a sheet conveyance direction such as a long-sized paper and stabilize transferability at front and rear ends, and to form an image with uniform image density and glossiness at the front and rear ends.SOLUTION: Provided is an image forming method for forming an image on at least a long-sized paper by using a toner containing at least a binder resin, wax, and an external additive. The binder resin is a mixture of at least a crystalline polyester resin and an amorphous polyester resin. The content of a saturated hydrocarbon compound having 16-35 carbon atoms in the toner is 1-1000 mass ppm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an image forming method, and more particularly to an image forming method for forming an image on at least a long sheet of paper using toner. [Background technology]

[0002] In recent years, the diversification of work styles has led to a general demand for compact, high-performance printers for telecommuting and small offices. High performance includes higher speeds, energy savings, and media compatibility, and demands on toner are also increasing. In particular, to handle long paper in a small printer, the paper must be transported in a limited space, so machine design is focused on smooth paper feeding (see, for example, Patent Document 1). Long paper refers to special-size paper whose length in the paper transport direction is longer than the paper feed tray, such as roll paper and continuous paper. Hereinafter, long paper will also be referred to as long paper.

[0003] On the other hand, toner for long paper needs to have excellent fixability from the leading edge to the trailing edge of the paper. It is generally well known that a crystalline resin is used as the binder resin for the toner to achieve excellent fixability. Furthermore, when forming an image on continuous paper, the image may be rubbed off when the paper is wound up after fixing. For this reason, excellent image strength is required, and a technique using two types of resins as the binder resin for the toner has been proposed (see, for example, Patent Document 2). For example, Patent Document 2 reports that by using two types of resins as the binder resin as described above, it is possible to achieve high hardness on the image surface.

[0004] It has also been reported that toners for printing on continuous paper need not only excellent fixability but also the associated suppression of toner filming (see, for example, Patent Document 3). For example, Patent Document 3 discloses a technique for adjusting the amounts of crystalline polyester, wax, and external additives blended into the toner. The technique described in Patent Document 3 is said to be able to achieve both good fixability and good filming resistance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-115588 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-117586 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-086642 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in order to print on long paper, in addition to the excellent fixability described above, characteristics for suppressing transfer defects at the trailing edge of the image are required, and there has been a problem in that sufficient image stability cannot be achieved with the above-described invention alone. In other words, when printing on long paper, there has been a problem in that transfer is difficult to stabilize at the trailing edge of the image, making transfer defects more likely to occur.

[0007] The present invention has been made in consideration of the above problems and circumstances. The problem to be solved by the present invention is to provide an image forming method that can form an image with excellent fixation on a recording medium that is long in the paper transport direction, such as long paper, with stable transferability at the leading and trailing edges, and with uniform image density and gloss at the leading and trailing edges. [Means for solving the problem]

[0008] To solve the above-mentioned problems, the inventors conducted extensive research, focusing on the electrical resistance of long paper when printing on long paper. As a result, they discovered that when printing on long paper, the electrical resistance of the paper changes at the leading edge of the image due to the fixed toner image. They also found that this influence causes the electrostatic capacitance of the paper to change at the trailing edge of the image that is not yet fixed during transfer, making discharge more likely to occur and resulting in transfer failures. They discovered that, to address such transfer failures, the transferability of the leading and trailing edges of the toner image can be stabilized by suppressing the increase in resistance of the toner image printed on long paper, and thus arrived at the present invention. In other words, the above-mentioned problems of the present invention are solved by the following means.

[0009] 1. An image forming method for forming an image on at least a long sheet of paper using a toner containing at least a binder resin, a wax, and an external additive, The image forming method is characterized in that the binder resin is a mixture of at least a crystalline polyester resin and an amorphous polyester resin, and the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms in the toner is 1 to 1000 ppm by mass.

[0010] 2. The image forming method according to claim 1, wherein the length of the long paper is 900 mm or more.

[0011] 3. The image forming method according to claim 2, wherein the length of the long paper is 1300 mm or more.

[0012] 4. The image forming method according to item 1 or 2, wherein the wax contains at least a hydrocarbon wax.

[0013] 5. The image forming method according to item 1 or 2, wherein the content of the saturated hydrocarbon compound having 16 to 35 carbon atoms in the toner is 100 to 700 ppm by mass.

[0014] 6. The image forming method according to item 1 or 2, wherein the toner is charged on the surface of the developing roller using a regulating blade.

[0015] 7. The image forming method according to item 1 or 2, wherein the amorphous polyester resin comprises an amorphous polyester resin having a vinyl resin segment containing at least a structural unit derived from a vinyl monomer.

[0016] 8. The external additive contains at least fine particles A having a particle diameter of 80 nm or more and less than 200 nm as confirmed by a scanning electron microscope of the toner, 3. The image forming method according to item 1 or 2, wherein the average coverage of the toner with the fine particles A is 5 area % or more and 40 area % or less, as determined by image analysis of the toner using a scanning electron microscope.

[0017] 9. The external additive contains at least fine particles B having a particle diameter of 200 nm or more and 500 nm or less as confirmed by a scanning electron microscope of the toner, 3. The image forming method according to item 1 or 2, wherein the average coverage of the toner with the fine particles B, as determined by image analysis of the toner using a scanning electron microscope, is 0.1 area % or more and 5 area % or less.

[0018] 10. The image forming method according to item 1 or 2, wherein the circularity of the toner is 0.950 to 0.990.

[0019] 11. The image forming method according to item 1 or 2, wherein the content of the crystalline polyester resin in the toner is 2 to 20% by mass. [Effects of the Invention]

[0020] The above-mentioned means of the present invention provide excellent fixation to recording media that are long in the paper transport direction, such as long paper, as well as stable transferability at the leading and trailing ends, making it possible to form images with uniform image density and gloss at the leading and trailing ends.

[0021] 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.

[0022] To stabilize the transferability of a toner image printed on long paper at its leading and trailing edges, it is necessary to prevent the toner image from becoming too resistive. Crystalline resins are used as binder resins in toner to ensure toner fixability. Such crystalline resins have lower resistance than other amorphous resins, and therefore can function as conductive paths in the toner image.

[0023] Incidentally, toner containing wax may be used in, for example, electrophotographic image formation. This wax melts from the toner when heated during fixing and seeps out onto the surface of the paper. For example, if wax 220 is contained in toner image 210 as shown in FIG. 3, during fixing, wax 220 in toner image 210 may melt and seep out onto surface 210A of toner image 210 as shown in FIG. 4. Here, FIGS. 3 and 4 are schematic diagrams illustrating the behavior of wax during fixing of a toner image formed by a conventional image forming method.

[0024] However, as shown in FIG. 4, if highly hydrophobic wax 220 is present on surface 210A of toner image 210, it inhibits moisture adsorption from surface 210A into toner image 210, making it difficult to reduce the resistance of toner image 210.

[0025] Therefore, the present inventors incorporated a small amount of a short-chain saturated hydrocarbon compound into a toner and used the toner to form an image. When forming an image using such a toner, during fixing, first, as shown in FIG. 5, a short-chain saturated hydrocarbon compound 130 with low melt viscosity melts and exudes onto the surface 110A of the toner image 110. Then, the wax 120 in the toner image 110 melts and exudes onto the surface 110A of the toner image 110. However, as shown in FIG. 6, when the wax 120 exudes onto the surface 110A of the toner image 110, it is localized to the area where the short-chain saturated hydrocarbon compound 130 with similar polarity is present. This makes it possible to suppress the exudation of the wax 120 onto the surface 110A of the toner image 110. As a result, it is possible to suppress the increase in the resistance of the toner image 110. Here, FIGS. 5 and 6 are schematic diagrams illustrating the behavior of the wax during fixing of a toner image formed by the image forming method of the present invention.

[0026] When a saturated hydrocarbon compound having 16 to 35 carbon atoms was used as the short-chain saturated hydrocarbon compound 130, it was possible to effectively suppress the exudation of the wax 120 and prevent the toner image 110 from becoming high in resistance. For example, saturated hydrocarbon compounds having 16 or more carbon atoms are unlikely to exude onto the surface 110A of the toner image 110 and are not sublimated by the fixing heat, which is presumably why the above-mentioned desired effect can be effectively achieved. Furthermore, saturated hydrocarbon compounds having 35 or fewer carbon atoms have low viscosity, allowing the wax 120 to be locally deposited on the surface 110A of the toner image 110 before it melts. Furthermore, when the content of the saturated hydrocarbon compound having 16 to 35 carbon atoms in the toner is 1 to 1,000 ppm by mass, it was possible to effectively suppress the exudation of the wax 120 and prevent the toner image 110 from becoming high in resistance. For example, it is presumed that when the content of the saturated hydrocarbon compound having 16 to 35 carbon atoms is 1 ppm by mass or more, a sufficient amount of the saturated hydrocarbon compound is present, thereby achieving the desired effect. When the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms is 1000 mass ppm or less, the wax 120 is appropriately and locally arranged, and it is presumed that the desired effect can be achieved. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of the configuration of an image forming apparatus. [Figure 2] FIG. 2 is a cross-sectional view illustrating an example of the configuration of a developing cartridge for a one-component developer. [Figure 3] 1A and 1B are schematic diagrams for explaining the behavior of wax when a toner image formed by a conventional image forming method is fixed. [Figure 4] 1A and 1B are schematic diagrams for explaining the behavior of wax when a toner image formed by a conventional image forming method is fixed. [Figure 5] 3A and 3B are schematic diagrams for explaining the behavior of wax during fixing of a toner image formed by the image forming method of the present invention. [Figure 6] 3A and 3B are schematic diagrams for explaining the behavior of wax during fixing of a toner image formed by the image forming method of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] An embodiment of the image forming method of the present invention is an image forming method in which an image is formed on at least long paper using a toner containing at least a binder resin, a wax, and an external additive. The image forming method of this embodiment is characterized in that the binder resin is a mixture of at least a crystalline polyester resin and an amorphous polyester resin, and the toner contains 1 to 1,000 ppm by mass of saturated hydrocarbon compounds having 16 to 35 carbon atoms. This image forming method provides excellent fixation to a recording medium that is long in the paper transport direction, such as long paper, and stable transferability at both the leading and trailing edges, resulting in the formation of an image with uniform image density and gloss at both the leading and trailing edges.

[0029] In the image forming method of this embodiment, long paper refers to special-size paper whose length in the paper transport direction is longer than the paper feed tray. Long paper also includes rolled continuous paper. Hereinafter, the length of long paper in the transport direction may be simply referred to as the "length of long paper." There are no particular restrictions on the length of long paper; for example, it is preferable that the length of long paper is 900 mm or more, and it is even more preferable that the length of long paper is 1300 mm or more. The longer the length of long paper as a recording material, the more effectively it can suppress high resistance due to the fixed toner image, making it easier to achieve the effects of the present invention described above.

[0030] The wax contained in the toner preferably contains at least a hydrocarbon wax, which has a molecular structure similar to that of a saturated hydrocarbon compound having 16 to 35 carbon atoms, and has the advantage of making the saturated hydrocarbon compound easily compatible with the release agent.

[0031] The content of saturated hydrocarbon compounds having carbon atoms of 16 to 35 in the toner is preferably 100 to 700 ppm by mass. By configuring in this way, it is expected that the toner image will not become highly resistive, and that the toner will have a predetermined degree of enhanced releasability from fixing members and the like.

[0032] From the viewpoint of miniaturization of the image forming apparatus, it is preferable that the toner is charged onto the surface of the developing roller using a regulating blade. Developing devices are broadly classified into two types: two-component development systems that perform development using a two-component developer mainly consisting of toner and carrier, and one-component development systems that perform development using a one-component developer that does not contain carrier. In developing devices using the one-component development system, the toner is charged by a regulating member such as a blade contacting the toner layer instead of the carrier. To miniaturize the device, it is preferable to adopt one-component development.

[0033] The amorphous polyester resin preferably contains an amorphous polyester resin having a vinyl resin segment containing at least a structural unit derived from a vinyl monomer. By containing such an amorphous polyester resin, the toner image is prevented from increasing in resistance because it has high hydrophilicity and can adsorb moisture in the air more effectively, and the affinity between the resin and the wax is further reduced, allowing the wax to be locally arranged.

[0034] The external additive may contain at least fine particles A having a particle diameter of 80 nm or more and less than 200 nm as confirmed by scanning electron microscopy of the toner. When the external additive contains such fine particles A, it is preferable that the average coverage of the toner by the fine particles A, as determined by image analysis of the toner using a scanning electron microscope, is 5 area % or more and 40 area % or less. Such fine particles A do not become embedded in the surface of the toner matrix, but act as spacers between the toner and the photoreceptor, improving transferability and reducing the likelihood of transfer defects.

[0035] The external additive may contain at least fine particles B having a particle diameter of 200 nm to 500 nm as determined by scanning electron microscopy of the toner. When the external additive contains such fine particles B, it is preferable that the average coverage of the toner by the fine particles B, as determined by scanning electron microscopy image analysis of the toner, is 0.1 area % to 5 area %. Adding a small amount of fine particles B can enhance the spacer effect and improve transferability.

[0036] The circularity of the toner is preferably 0.950 to 0.990. By configuring in this way, it is possible to ensure good transferability of the toner, and also to ensure appropriate adhesive force, thereby obtaining good transferability.

[0037] From the viewpoint of excellent fixability and suppressing the toner from becoming highly resistive, the content of the crystalline polyester resin in the toner is preferably 2 to 20% by mass.

[0038] The present invention, its components, and embodiments and modes for carrying out the present invention will be described in detail below. In this application, the symbol "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower limit and upper limit.

[0039] [1. Overview of image formation method] One embodiment of the image forming method of the present invention will be described below, but the present invention is not limited thereto. The image forming method of this embodiment is an image forming method in which an image is formed on at least long paper using a toner containing at least a binder resin, a wax, and an external additive. The image forming method of this embodiment is characterized in that the binder resin contained in the toner is a mixture of at least a crystalline polyester resin and an amorphous polyester resin, and the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms in the toner is 1 to 1,000 ppm by mass. This image forming method has excellent fixability to a recording medium that is long in the paper transport direction, such as long paper, and stable transferability at both the leading and trailing edges, making it possible to form an image with uniform image density and gloss at both the leading and trailing edges.

[0040] [2. Long Paper] Long paper is special size paper whose length in the paper transport direction is longer than the paper feed tray. There are no particular restrictions on the length of long paper in the transport direction. For example, the length of long paper in the transport direction may be 900 mm or more, or even 1300 mm or more. Hereinafter, the length of long paper in the transport direction may be simply referred to as the "length of long paper." Long paper also includes rolled continuous paper.

[0041] The image forming method of this embodiment can effectively suppress high resistance caused by the fixed toner image, especially when the length of the long sheet is longer. Therefore, the image forming method of this embodiment, particularly when forming an image on long sheet using toner, is likely to achieve the effects of excellent fixability and stable transferability at the leading and trailing edges, and of forming an image with uniform image density and gloss at the leading and trailing edges.

[0042] [3. Toner] The toner used in the image forming method of this embodiment contains at least a binder resin, a wax, and an external additive. The binder resin contained in the toner is a mixture of at least a crystalline polyester resin and an amorphous polyester resin. The toner contains saturated hydrocarbon compounds having 16 to 35 carbon atoms in an amount of 1 to 1,000 ppm by mass. Hereinafter, the saturated hydrocarbon compounds having 16 to 35 carbon atoms contained in the toner used in the image forming method of this embodiment may be referred to as "specific saturated hydrocarbon compounds." That is, in the image forming method of this embodiment, it is preferable to form an image at least on long paper using a toner containing specific saturated hydrocarbon compounds in an amount of 1 to 1,000 ppm by mass.

[0043] In the present invention, "toner" refers to an aggregate of toner particles. The toner particles may be composed of only toner base particles, or may be composed of toner base particles and external additives attached to the surfaces of the toner base particles. "Toner base particles" are particles that form the base of the toner particles. Examples of toner include electrostatic image developing toners for developing electrostatic images (electrostatic latent images) formed on an image carrier such as a photoreceptor.

[0044] <Binder resin> Known polymers can be used for the binder resin contained in the toner particles, and specifically, for example, the following polymers can be used. Polymers that can be used for the binder resin include homopolymers of styrene and its substitution products, such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, and styrene-acrylonitrile-indene copolymer; polyvinyl chloride, phenolic resin, natural resin-modified phenolic resin, natural resin-modified maleic acid resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester, polyurethane, polyamide, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone-indene resin, and petroleum-based resin. These resins may be used alone or in combination of two or more.

[0045] (amorphous polyester resin) The binder resin contains an amorphous polyester resin. Amorphous polyester resins are obtained by polycondensation reaction using polycarboxylic acid monomers (derivatives) and polyhydric alcohol monomers (derivatives) as raw materials, and do not have a clear melting point. Amorphous polyester resins are highly hydrophilic and adsorb moisture from the air, effectively suppressing high resistance in toner images and further reducing the affinity between the resin and wax, allowing for localized placement of the wax.

[0046] The amorphous polyester resin is preferably contained in an amount of 60% by mass or more, and more preferably 80% by mass or more, based on the total mass of the binder resin.

[0047] Furthermore, the amorphous polyester resin is preferably an amorphous polyester resin having a vinyl resin segment containing at least a structural unit derived from a vinyl monomer. The presence of the vinyl resin segment improves the dispersibility of the wax in the toner, thereby suppressing the increase in the resistance of the toner image due to wax domains. The wax domain refers to a wax domain phase in a phase-separated structure in which the wax domain phase is dispersed in a resin matrix phase.

[0048] Examples of vinyl monomers include styrene-based monomers and (meth)acrylic acid ester-based monomers. In addition to the above-mentioned monomers, examples of vinyl monomers include olefins, vinyl esters, vinyl ethers, vinyl ketones, and N-vinyl compounds. Examples of olefins include ethylene, propylene, and isobutylene. Examples of vinyl esters include vinyl propionate, vinyl acetate, and vinyl benzoate. Examples of vinyl ethers include vinyl methyl ether and vinyl ethyl ether. Examples of vinyl ketones include vinyl methyl ketone, vinyl ethyl ketone, and vinyl hexyl ketone. Examples of N-vinyl compounds include N-vinylcarbazole, N-vinylindole, and N-vinylpyrrolidone. Other examples of vinyl monomers include vinyl compounds such as vinylnaphthalene and vinylpyridine, and acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile, and acrylamide.

[0049] Examples of styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof.

[0050] Examples of the (meth)acrylic acid ester monomer include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

[0051] The styrene-based monomers and (meth)acrylic acid ester-based monomers explained above can each be used alone or in combination of two or more.

[0052] The polyester resin having a vinyl resin segment may be one in which the vinyl resin segment is bonded to a polyester polymerization segment. The vinyl resin segment may be bonded as a branched chain in the chain of the polyester polymerization segment, or may be bonded to form a straight chain. When the vinyl resin segment forms a straight chain, it may be bonded either at the middle or at the end of the straight chain.

[0053] A bireactive monomer may be used to bond the polyester polymerized segment and the vinyl resin segment. The bireactive monomer may be a monomer having a polymerizable unsaturated group and a group capable of reacting with a polycarboxylic acid monomer and / or a polyhydric alcohol monomer for forming the polyester polymerized segment. Specific examples of the bireactive monomer include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride.

[0054] The softening point of the amorphous polyester is preferably 70°C or higher and 140°C or lower, and even more preferably 90°C or higher and 120°C or lower. If the softening point is higher than 70°C, the specific hydrocarbon compound contained in the toner is likely to be located on the surface of the toner image. If the softening point is lower than 140°C, excellent fixability is achieved, and differences in image gloss between the leading and trailing ends of long paper are unlikely to occur.

[0055] The glass transition temperature of the amorphous polyester is preferably 30°C or higher and 70°C or lower, and more preferably 40°C or higher and 60°C or lower. When the glass transition temperature is higher than 30°C, the occurrence of toner filming can be effectively suppressed even when printing is performed continuously on long-length paper for a long period of time. When the glass transition temperature is lower than 70°C, excellent fixability is achieved, and image gloss difference between the leading and trailing ends of long-length paper is unlikely to occur.

[0056] (Crystalline polyester resin) The binder resin contains a crystalline polyester resin. The inclusion of the crystalline polyester resin contributes to excellent fixability and suppression of high resistance in toner images. Crystalline polyester resins are obtained by a dehydration condensation reaction between a polycarboxylic acid and a polyhydric alcohol. "Crystalline" means having a melting point. In other words, "crystalline" means having a clear endothermic peak during heating in an endothermic curve obtained by differential scanning calorimetry (DSC). "Clear endothermic peak" means a peak with a half-width of 15°C or less in an endothermic curve when heated at a heating rate of 10°C / min.

[0057] The polycarboxylic acid may be a divalent or higher carboxylic acid, such as trimellitic acid or pyromellitic acid. Among these, dicarboxylic acids are preferred from the viewpoint of enhancing excellent fixability. Examples of dicarboxylic acids include aliphatic carboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid, as well as aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid.

[0058] Among these polycarboxylic acids, aliphatic carboxylic acids are preferred because they tend to provide excellent fixability. The aliphatic carboxylic acids preferably have a linear hydrocarbon group having 6 to 16 carbon atoms, and more preferably have a linear hydrocarbon group having 10 to 14 carbon atoms. The hydrocarbon structure of the aliphatic carboxylic acid may be partially branched.

[0059] The polyhydric alcohol may be a dihydric or higher alcohol, such as glycerin, pentaerythritol, trimethylolpropane, sorbitol, etc. Among these, dihydric alcohols are preferred from the viewpoint of increasing the crystallinity of the crystalline polyester. Examples of the dihydric alcohol include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol; diols having an unsaturated double bond such as 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octene-1,8-diol; and diols having a sulfonic acid group.

[0060] The content of the crystalline polyester resin is preferably 2% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, relative to the total mass of the binder resin. If the content of the crystalline polyester resin is 2% by mass or more, a sufficient amount is present in the binder resin, and excellent fixability and the effect of suppressing high resistance of the toner image are more effectively exhibited. If the content of the crystalline polyester resin exceeds 20% by mass, the exudation of the specific hydrocarbon compound is inhibited, and the intended effect is not fully exhibited.

[0061] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 5,000 or more and 50,000 or less. The number average molecular weight (Mn) of the crystalline polyester resin is preferably 2,000 or more and 10,000 or less. When the weight average molecular weight (Mw) and number average molecular weight (Mn) of the crystalline polyester resin are in the above-mentioned numerical ranges, the fixing property is improved. The weight average molecular weight (Mw) and number average molecular weight (Mn) can be measured by gel permeation chromatography (GPC).

[0062] The melting point of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower. It is even more preferably 60°C or higher and 80°C or lower. When the melting point of the crystalline polyester resin is higher than 50°C, the specific hydrocarbon compound is more likely to be located on the surface of the toner image. For example, since the specific hydrocarbon compound is more likely to be located on the surface of the toner image, it is expected that the wax will be less likely to volatilize during fixing. Excessive volatilization of wax during fixing and its microparticulation is undesirable from the standpoint of environmental impact. Furthermore, when the melting point of the crystalline polyester resin is lower than 100°C, the fixability is improved.

[0063] <Wax> The toner used in the image forming method of this embodiment contains a wax. The wax is not particularly limited, but examples thereof include hydrocarbon waxes such as low-molecular-weight polyethylene wax, low-molecular-weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax; dialkyl ketone waxes such as distearyl ketone; carnauba wax; montan wax; ester waxes such as behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, tristearyl trimellitate, and distearyl maleate; and amide waxes such as ethylenediamine dibehenylamide and tristearyl trimellitate amide. These waxes may be used alone or in combination. Among these, hydrocarbon wax is preferred because it has a molecular structure similar to that of the specific saturated hydrocarbon compound having 16 to 35 carbon atoms and is easy to make the specific saturated hydrocarbon compound compatible with the release agent (i.e., wax). When the specific saturated hydrocarbon compound and wax are well compatible with each other, the wax can be locally arranged on the surface of the toner image, and high resistance can be suppressed.

[0064] The melting point of the wax is preferably 50°C or higher and 100°C or lower, and even more preferably 60°C or higher and 90°C or lower. If the melting point of the wax is higher than 50°C, the wax does not ooze excessively onto the image surface during fixing, and high resistance can be suppressed. If the melting point of the wax is lower than 90°C, the wax melts and the ability to separate from the fixing member can be ensured.

[0065] The wax content is preferably 2 to 20% by mass, more preferably 3 to 10% by mass, based on the total amount of binder resin. If the wax content is 2% by mass or more, a sufficient amount is present, ensuring separation performance from the fixing member. If the wax content is 20% by mass or less, high resistance of the toner image can be more effectively suppressed.

[0066] <Saturated hydrocarbon compounds with carbon numbers of 16 to 35 (specific saturated hydrocarbon compounds)> In the image forming method of this embodiment, the content of the saturated hydrocarbon compound having 16 to 35 carbon atoms in the toner is 1 to 1,000 ppm by mass. The saturated hydrocarbon compound having 16 to 35 carbon atoms suppresses the toner image from becoming highly resistive due to the above-described action. On the other hand, the saturated hydrocarbon compound having 16 to 35 carbon atoms also has the effect of enhancing the releasability of the toner from a fixing member or the like to a predetermined extent. Therefore, the wax (releasing agent) contained in the toner described above may be used as the first releasing agent, and the saturated hydrocarbon compound having 16 to 35 carbon atoms may be contained in the toner base particles as the second releasing agent. For example, when the wax contained in the toner described above is used as the first releasing agent, it is preferable that the wax serving as the first releasing agent does not contain a saturated hydrocarbon compound having 16 to 35 carbon atoms.

[0067] The content of the saturated hydrocarbon compound having 16 to 35 carbon atoms is 1 ppm or more and 1000 ppm or less relative to the total mass of the toner (mass including toner base particles and external additives). The content of the saturated hydrocarbon compound having 16 to 35 carbon atoms is preferably 50 ppm or more and 900 ppm or less, and more preferably 100 ppm or more and 700 ppm or less, relative to the total mass of the toner. By making it 1 ppm or more, a sufficient amount is present, and the target effect can be exerted. By making it 1000 ppm or less, the wax is appropriately locally arranged, and the target effect can be exerted.

[0068] The saturated hydrocarbon compound having 16 to 35 carbon atoms may be, for example, a linear saturated hydrocarbon compound having 16 to 35 carbon atoms, or may be a saturated hydrocarbon compound having 16 to 35 carbon atoms and containing a branched structure. Furthermore, the saturated hydrocarbon compound having 16 to 35 carbon atoms may contain a cyclic structure.

[0069] The content of saturated hydrocarbon compounds having 16 to 35 carbon atoms (hereinafter also referred to as "specific saturated hydrocarbon compounds") can be determined by the following method. First, the specific saturated hydrocarbon compounds are separated from the toner using a solvent that dissolves the specific saturated hydrocarbon compounds. Then, the specific saturated hydrocarbon compounds separated into the solvent are qualitatively analyzed by gas chromatography mass spectrometry (GC-MS). Furthermore, the specific saturated hydrocarbon compounds separated into the solvent are quantified by gas chromatography with flame ionization detection (GC-FID) using a flame ionization detector (FID) as the detector. Since the extract from the toner may also contain unsaturated hydrocarbon compounds, after extraction, polar groups can be added to the unsaturated bonds, and only the saturated hydrocarbons can be separated by column separation utilizing the polarity difference.

[0070] At this time, multiple internal standards may be added (dissolved) in the solvent to determine whether the quantification and pretreatment have been carried out appropriately. The concentration of the internal standards to be added may be set according to the amount of saturated hydrocarbon compounds having 16 to 35 carbon atoms (the estimated amount obtained by provisional measurement, etc.).

[0071] The internal standard is preferably a saturated hydrocarbon compound that is not normally contained in toner. For example, using n-undecane or n-tridecane makes it easy to detect the loss of saturated hydrocarbon compounds due to volatilization during pretreatment, or to use it as a guide for the elution time of the target saturated hydrocarbon compound during analysis by solid-phase extraction or GC-FID. Furthermore, bicyclohexyl is less likely to overlap with the elution time of specific saturated hydrocarbon compounds, making it easier to improve detection accuracy.

[0072] Extraction from the toner can be performed by a conventionally known method such as a solid-liquid extraction method, a method of separating the toner by centrifugal separation after dissolving or swelling the toner, a Soxhlet extraction method, a high-speed solvent extraction method, etc. A method may be selected from these methods depending on the expected carbon number of the specific saturated hydrocarbon compound and the type of compound that will become an impurity component such as a binder resin.

[0073] The solvent used for extraction is not particularly limited, but n-hexane, which has a high solubility for specific saturated hydrocarbon compounds, is preferred. Depending on the type of binder resin, polar solvents such as dichloromethane and ethanol may be used in combination to swell the binder resin.

[0074] There are no particular limitations on the method for introducing polar groups into unsaturated hydrocarbon compounds contained in the extract. For example, methods for introducing polar groups into unsaturated hydrocarbon compounds include epoxidation with metachloroperbenzoic acid (mCPBA), addition of hydrogen halide, addition of water or alcohol using an acid catalyst, and derivatization into alcohol by oxidation after hydroboration. Among these, epoxidation using mCPBA is preferred because of its high reactivity and reaction selectivity. In this case, for example, 1 The progress of the reaction can be confirmed by confirming the disappearance of the double bond peak by H-NMR measurement. Note that, if sufficient detection accuracy can be ensured depending on the type of saturated hydrocarbon compound or unsaturated hydrocarbon compound, the addition of a polar group may be omitted.

[0075] Separation utilizing the difference in polarity can be performed by known methods such as solid-phase extraction, online or offline GC, etc. When it is expected that a large amount of impurities will be contained, separation by solid-phase extraction is preferable.

[0076] When separating by solid-phase extraction, n-hexane is preferably used as the solvent for both conditioning and extraction of saturated hydrocarbon compounds. In this case, a polar solvent may also be used depending on the type of contaminants expected. After collecting a fraction containing saturated hydrocarbon compounds with 16 to 35 carbon atoms, it is preferable to increase the polarity of the solvent to collect the fraction and then perform qualitative analysis using GC / MS or the like to confirm that the fraction does not contain saturated hydrocarbon compounds.

[0077] The solid phase for solid-phase extraction can be a highly polar solid phase used in normal-phase separations using polar interactions. Examples of such solid phases include silica gel, silica gel activated with polar substances such as anhydrous sodium sulfate and silver nitrate, diol, cyanopropyl silica, magnesium silicate, etc. Among these, activated silica activated with silver nitrate is preferred. It is preferable not to use alumina, as it specifically retains long-chain n-alkanes.

[0078] The fraction containing saturated hydrocarbon compounds extracted by solid-phase extraction is preferably concentrated or diluted to a concentration appropriate for qualitative and quantitative analysis by gas chromatography. The method for concentrating the fraction containing the extracted saturated hydrocarbon compounds is not particularly limited, but examples thereof include vacuum concentration using an evaporator and concentration using a nitrogen gas stream. The concentration conditions should be such that the internal standard does not disappear due to the concentration of low-boiling point components.

[0079] The fraction after solid phase extraction can be subjected to GC-FID under the following conditions, for example, to quantify saturated hydrocarbon compounds having 16 to 35 carbon atoms.

[0080] (GC conditions) Equipment used: Shimadzu GC-2010 Plus Injection volume: 1 μL, saturated hydrocarbon concentration: 500 to 1000 mg / L Guard column: Restek MXT Siltek (10 m x 0.53 mm id) Column: Restek MTX-1 (15 m x 0.25 mm id) x 0.1 μm df) Carrier gas: Helium

[0081] The quantification of saturated hydrocarbon compounds having 16 to 35 carbon atoms may be carried out using an instrument having the same performance as the above instrument and a column having the same performance as the above column, as long as the same results as those obtained under the above conditions are obtained.

[0082] At this time, the elution times of n-alkanes (number of carbon atoms: 10, 16, 24, 35, and 50) measured under the same conditions are measured in advance. In addition, n-hexane alone is injected into the above-mentioned device to prepare a blank chromatogram.

[0083] A blank chromatogram obtained by measuring only the solvent is subtracted from the chromatogram obtained for the toner to determine the baseline. It is preferable that a horizontal line baseline can be created at the lowest point before and after the peak derived from the saturated hydrocarbon compound. However, if a horizontal line baseline cannot be created even after subtracting the blank chromatogram due to column bleed or the like, the baseline can be set as follows: That is, the baseline can be set as a horizontal line from the elution time of the C10 compound to the elution time of the C50 compound, starting from the lower signal intensity of the C10 compound or the C50 compound.

[0084] Then, vertical lines are drawn on the chromatogram at positions corresponding to the elution times of the compounds with 16 and 35 carbon atoms, and the area of ​​the chromatogram above the baseline enclosed by these vertical lines is calculated. Peaks that are confirmed not to be saturated hydrocarbon compounds are excluded from the calculation. The mass of the saturated hydrocarbon compounds with 16 to 35 carbon atoms can be calculated from this area. When an internal standard is used, the mass of the saturated hydrocarbon compounds with 16 to 35 carbon atoms can be calculated from the ratio of the above area to the area of ​​the compound added as the internal standard. The obtained mass of the saturated hydrocarbon compounds with 16 to 35 carbon atoms is then divided by the mass of the toner to calculate the amount of the saturated hydrocarbon compounds with 16 to 35 carbon atoms in the toner.

[0085] <External additives> The toner used in the image forming method of this embodiment contains an external additive. By containing the external additive, the fluidity, chargeability, and cleanability of the toner can be improved. The external additive is attached to the surface of the toner base particles, for example, as a post-treatment agent.

[0086] The external additive may be a conventional metal oxide particle. Examples include silica particles, titania particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, and boron oxide particles. The external additive may also contain organic fine particles such as homopolymers of styrene, methyl methacrylate, and the like, or copolymers thereof. Furthermore, the external additive may also contain organic fine particles such as melamine-based resin fine particles, polytetrafluoroethylene resin fine particles, and the like.

[0087] The external additive preferably contains at least fine particles A having a particle diameter of 80 nm or more and less than 200 nm as determined by scanning electron microscopy of the toner.More preferably, the average coverage of the fine particles A of the toner, as determined by image analysis of the toner using a scanning electron microscope, is 5 area % or more and 40 area % or less.

[0088] By including fine particles A having a particle diameter of 80 nm or more but less than 200 nm, the transferability of the toner is improved, making transfer failure less likely to occur. That is, when the particle diameter of fine particles A is 80 nm or more, they do not become embedded in the surface of the toner matrix, but act as spacers between the toner and the photoreceptor, improving transferability and making transfer failure less likely to occur. Furthermore, when the particle diameter of fine particles A is less than 200 nm, the fine particles A are less likely to detach from the toner surface, making it possible to stably achieve the desired effect. It is more preferable that the particle diameter of fine particles A is 90 nm or more but less than 150 nm.

[0089] Furthermore, when the average coverage of the toner particles A is 5% or more by area, the particles A are distributed evenly over the surface of the toner matrix, and the effect can be effectively exhibited. On the other hand, when the average coverage of the toner particles A is 40% or less by area, the aggregation of the particles A is easily broken down, and the particles A can be distributed evenly over the surface of the toner matrix. It is more preferable that the average coverage of the toner particles A is 20 to 30% by area.

[0090] The type of the fine particles A as the external additive is not particularly limited, and any of the particles that can be used as the external additive described above can be used. In particular, silica particles having a specific gravity similar to that of the resin constituting the toner can be more preferably used as the fine particles A as the external additive, from the viewpoint of suppressing embedding in the resin constituting the toner and preventing separation under stress.

[0091] The external additive may also contain at least fine particles B having a particle diameter of 200 nm to 500 nm as determined by scanning electron microscopy of the toner. The average coverage of the fine particles B on the toner, as determined by scanning electron microscopy image analysis of the toner, is preferably 0.1 area % to 5 area %. By incorporating a small amount of fine particles B having a particle diameter of 200 nm to 500 nm relative to the fine particles A, the above-mentioned spacer effect is more readily achieved, further improving transferability. For example, by having a particle diameter of 200 nm or more, the fine particles B are not embedded in the surface of the toner matrix, allowing their effect to be effectively exerted. Furthermore, by having a particle diameter of 500 nm or less, the fine particles B are less likely to detach from the surface of the toner matrix, allowing the desired effect to be stably exerted. Furthermore, when the average coverage of the fine particles B on the toner is 0.1 area % or more, the fine particles B are evenly distributed on the surface of the toner matrix, allowing their effect to be exerted. On the other hand, when the average coverage of the toner with the fine particles B is 5% or less by area, the aggregation of the fine particles B is easily broken down, allowing the fine particles B to be evenly distributed on the surface of the toner matrix. It is more preferable that the average coverage of the toner with the fine particles B is 1 to 3% by area.

[0092] The type of the fine particles B as the external additive is not particularly limited, and the particles that can be used as the external additive described above can be used. The fine particles B are preferably organic fine particles in order to improve affinity with the toner and prevent separation.

[0093] (Method for measuring particle size of external additives) The particle diameter of the particles constituting the external additive (hereinafter also referred to as "external additive fine particles") can be measured by the following method. A scanning electron microscope (SEM) "JEM-7401F" (manufactured by JEOL Ltd.) is used to take an SEM photograph of the toner magnified 50,000 times. The SEM photograph of the toner taken is observed, and the particle diameter (Ferret diameter) of the primary particles of the external additive fine particles is measured and determined. The same procedure is performed for 30 toner particles. Of the external additive fine particles whose particle diameters have been measured in this way, those with a particle diameter of 80 nm or more and less than 200 nm are referred to as "fine particles A" as described above. Furthermore, of the external additive fine particles whose particle diameters have been measured, those with a particle diameter of 200 nm or more and 500 nm or less are referred to as "fine particles B" as described above.

[0094] (Method of calculating the average coverage of external additive particles in toner) The average coverage of the toner's external additive fine particles (fine particles A or fine particles B) can be determined by the following method. First, using an SEM photograph obtained by the above-mentioned method for measuring the particle diameter of the external additive, the coverage area SA of fine particles A and the coverage area SB of fine particles B are calculated by image processing using image processing software. "ImageJ" (open source) is used as the image processing software. Specifically, fine particles with a particle diameter corresponding to fine particles A are manually surrounded using the "Polygon selections tool" in "ImageJ" to calculate the coverage area SA of fine particles A. Similarly, fine particles with a particle diameter corresponding to fine particles B are manually surrounded using the above tool to calculate the coverage area SB of fine particles B. Furthermore, the toner surface area S is also calculated in a similar manner. The coverage (area %) of the toner's fine particles A can be calculated by SA / S × 100%. Furthermore, the coverage (area %) of the toner's fine particles B can be calculated by SB / S × 100%. Then, the same operation is performed for 30 toner particles, and the coverage (area %) of fine particle A and the coverage (area %) of fine particle B are calculated for each of the 30 toner particles. The average of the coverage (area %) of fine particle A for the 30 toner particles is then taken as the average coverage (area %) of fine particle A for the toner. Similarly, the average of the coverage (area %) of fine particle B for the 30 toner particles is taken as the average coverage (area %) of fine particle B for the toner.

[0095] (Toner circularity) The circularity of the toner is preferably 0.950 to 0.990. That is, the circularity of the toner base particles is preferably 0.950 or more and 0.990 or less, and more preferably 0.960 or more and 0.980 or less. By making the circularity of the toner base particles 0.950 or more, transferability can be ensured. By making the circularity of the toner base particles 0.990 or less, appropriate adhesive force can be ensured, and good transferability can be obtained.

[0096] (Method for measuring circularity of toner) The circularity of the toner can be measured using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation). Specifically, the toner particles are wetted in a surfactant aqueous solution, ultrasonically dispersed for 1 minute, and then measured using an "FPIA-3000" under the measurement conditions of HPF (high magnification imaging) mode at an appropriate concentration of 3,000 to 10,000 HPF detection particles. Within this range, reproducible measurements can be obtained.

[0097] The circularity is calculated by the following formula. Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the projected particle image) The average circularity is an arithmetic mean value obtained by adding up the circularity of each particle and dividing the sum by the total number of particles measured.

[0098] (Toner particle size) The toner base particles preferably have a volume-based average particle diameter (volume average particle diameter) of 3.0 μm or more and 10.0 μm or less, more preferably 4.0 μm or more and 8.0 μm or less, and even more preferably 4.0 μm or more and 7.0 μm or less. By making the volume-based average particle diameter of the toner base particles 3.0 μm or more, appropriate adhesive force is ensured and good transferability is obtained. On the other hand, by making the volume-based average particle diameter of the toner base particles 10.0 μm or less, it is possible to facilitate the exudation of saturated hydrocarbon compounds having 16 to 35 carbon atoms.

[0099] The volume-average particle size of toner base particles can be measured using a particle size distribution analyzer (Beckman Coulter, Coulter Multisizer 3) connected to a computer system equipped with data processing software V3.51. Specifically, 0.02 g of sample (toner base particles) is added to 20 mL of surfactant solution, mixed, and then ultrasonically dispersed for 1 minute to prepare a toner base particle dispersion. For example, the surfactant solution used can be a surfactant solution prepared by diluting a neutral detergent containing surfactant components 10 times with pure water for the purpose of dispersing the toner base particles. The dispersion prepared as described above is pipetted into a beaker containing electrolyte (Beckman Coulter, ISOTON II) in a sample stand until the concentration indicated on the analyzer reaches 8%. This concentration ensures reproducible measurements. Then, in the measuring device, the number of measured particles is set to 25,000, the aperture diameter is set to 100 μm, the measurement range of 2 to 60 μm is divided into 256 parts to calculate the frequency value, and the volume-based average particle diameter is calculated based on this.

[0100] <Other ingredients> The toner may contain a colorant, a charge control agent, and the like.

[0101] (coloring agent) The colorant may be a dye or a pigment. When the toner is a color toner that imparts a predetermined color tone to an image, the toner base particles may contain a colorant such as yellow, magenta, cyan, or black, depending on the color tone to be exhibited by the color toner. The toner base particles may contain only one type of colorant, or a combination of multiple types of colorants.

[0102] Examples of yellow colorants include yellow dyes, including CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162. Further, examples of yellow colorants include yellow pigments, including CI Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, and 185.

[0103] Examples of magenta colorants include magenta dyes such as CI Solvent Red 1, 49, 52, 58, 63, 111, and 122. Additionally, examples of magenta colorants include magenta pigments such as CI Pigment Red 5, 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, and 222.

[0104] Examples of cyan colorants include cyan dyes such as CI Solvent Blue 25, 36, 60, 70, 93, and 95, and cyan pigments such as CI Pigment Blue 1, 7, 15, 15:3, 60, 62, 66, and 76.

[0105] Examples of black colorants include carbon blacks such as channel black, furnace black, acetylene black, thermal black, and lamp black, magnetic materials such as ferrite and magnetite, and iron-titanium composite oxides.

[0106] The content of the colorant is preferably 0.5% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less, relative to the total mass of the toner base particles. When the toner is a clear toner, the toner base particles preferably do not substantially contain a colorant, and the content of the colorant relative to the total mass of the toner base particles is preferably 0.1% by mass or less.

[0107] (charge control agent) The charge control agent can adjust the chargeability of the toner base particles.

[0108] Examples of the charge control agent include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, metal salicylate salts, or metal complexes thereof.

[0109] The content of the charge control agent is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less, based on the total mass of the binder resin. Attempting to control the chargeability of the toner by adding an excessive amount of charge control agent may significantly change other properties of the toner base particles. By adjusting the chargeability of the toner with strontium titanate, the chargeability of the toner can be adjusted to a desired level while satisfying other required properties.

[0110] (Other external additives) The external additive may contain other known external additives in addition to the fine particles A and fine particles B described above. Examples of known external additives that can be used include inorganic fine particles, organic fine particles, and lubricants, which will be described later.

[0111] As other external additives, conventionally known metal oxide particles can be used for the purpose of controlling fluidity and chargeability. Examples include silica particles, titania particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, and boron oxide particles. These may be used alone or in combination of two or more. In addition, the external additive may contain organic fine particles such as homopolymers of styrene, methyl methacrylate, etc., or copolymers thereof.

[0112] The shape of the external additive is not limited, and may be any of spherical, flat, plate-like, and needle-like. From the viewpoint of imparting fluidity, the particle size of these external additives is preferably 3 to 200 nm, and more preferably 10 to 80 nm.

[0113] The metal oxide particles used as an external additive are preferably those whose surfaces have been subjected to a hydrophobic treatment using a known surface treatment agent such as a coupling agent, etc. Examples of the surface treatment agent include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, and decyltrimethoxysilane.

[0114] Silicone oils can also be used as the surface treatment agent. Specific examples of silicone oils include cyclic compounds and linear or branched organosiloxanes. More specific examples include organosiloxane oligomers, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, and tetravinyltetramethylcyclotetrasiloxane. Highly reactive silicone oils, at least terminally modified, may also be used, in which modified groups are introduced into the side chain, one end, both ends, one end of the side chain, or both ends of the side chain. Examples of such modified groups include, but are not limited to, alkoxy groups, carboxyl groups, carbinol groups, higher fatty acid modified groups, phenol groups, epoxy groups, methacrylic groups, and amino groups. Silicone oils having several modified groups, such as amino / alkoxy modified groups, may also be used. Dimethylsilicone oil, the modified silicone oils described above, and other surface treatment agents may also be mixed or used in combination. Examples of the treating agent to be used in combination include silane coupling agents, titanate coupling agents, aluminate coupling agents, various silicone oils, fatty acids, fatty acid metal salts, esters thereof, and rosin acid.

[0115] To further improve cleaning properties and transfer properties, a lubricant can be used as an external additive. Examples of lubricants include metal salts of higher fatty acids such as those listed below. Examples of metal salts of higher fatty acids include zinc, aluminum, copper, magnesium, calcium, and other salts of stearic acid, and zinc, manganese, iron, copper, and magnesium, and other salts of oleic acid. Examples of metal salts of higher fatty acids include zinc, copper, magnesium, calcium, and other salts of palmitic acid, zinc, calcium, and other salts of linoleic acid, and zinc, calcium, and other salts of ricinoleic acid. The total amount of these external additives added is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, per 100 parts by weight of the toner base particles.

[0116] <Toner manufacturing method> There are no particular limitations on the method for producing the toner, and it can be produced by, for example, a pulverization method, an emulsion dispersion method, a suspension polymerization method, a dispersion polymerization method, an emulsion polymerization method, an emulsion polymerization aggregation method, or the like. Among these, the pulverization method is more preferable. Toner base particles produced by the pulverization method are excellent for dispersing multiple materials such as a charge control agent, a pigment, and a crystalline polyester. In particular, the pulverization method is preferable for one-component development, since it contains a charge control agent.

[0117] In the pulverization method, a binder resin and a colorant are melt-kneaded, and then cooled to obtain a resin composition, which is then pulverized to obtain toner base particles. Furthermore, after the pulverization process, classification and drying may be performed as necessary. A method for producing a toner using the pulverization process will now be described.

[0118] (Mixing / melting and kneading) First, the materials constituting the toner base particles are mixed. Mixing can be performed using a mixing device such as a double cone mixer, V-type mixer, drum mixer, super mixer, Henschel mixer, Nauta mixer, or Mechano Hybrid. Materials constituting the toner base particles include a binder resin, a wax release agent, and optional additional materials (e.g., colorants). If the wax release agent contains a saturated hydrocarbon compound having 16 to 35 carbon atoms, it is preferable to use one with a known content. Alternatively, a predetermined amount of a saturated hydrocarbon compound having 16 to 35 carbon atoms may be added to the materials constituting the toner base particles so that the content of the saturated hydrocarbon compound having 16 to 35 carbon atoms in the toner falls within a specific range. In this case, it is preferable to use a wax release agent that does not contain a saturated hydrocarbon compound having 16 to 35 carbon atoms, or, if a saturated hydrocarbon compound having 16 to 35 carbon atoms is contained, one with a known content.

[0119] Next, the mixed materials are melt-kneaded. For melt-kneading, a batch kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader, can be used. For continuous production, it is preferable to use a single-screw extruder or a twin-screw extruder. Examples of twin-screw extruders include a KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), a TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), a PCM kneader (manufactured by Ikegai Corporation), a twin-screw extruder (manufactured by KCK Corporation), a Ko-Kneader (manufactured by Buss Co., Ltd.), and a Kneadex (manufactured by Nippon Coke and Engineering Co., Ltd.). The melt-kneading temperature is preferably about 100 to 200°C. The resin composition obtained by melt-kneading is rolled using a twin roll or the like and quenched with water or the like to form a solid.

[0120] (Crushing) The resulting resin composition is pulverized to a desired particle size. For example, the resin composition may be coarsely pulverized using a pulverizer such as a crusher, hammer mill, or feather mill, and then finely pulverized using a fine pulverizer or an air jet pulverizer. Examples of fine pulverizers that can be used include the Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Inc.), and Turbo Mill (manufactured by Freund Turbo Corporation).

[0121] (classification) Thereafter, the pulverized resin composition is classified as needed using a classifier or sieving machine such as an inertial classification type Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), a centrifugal classification type Turboplex (manufactured by Hosokawa Micron Corporation), a TSP Separator (manufactured by Hosokawa Micron Corporation), or a Faculty (manufactured by Hosokawa Micron Corporation).

[0122] (Dry) Furthermore, the resin composition after classification may be dried as necessary. The drying method is not particularly limited, and examples thereof include methods using an oven, a spray dryer, a vacuum freeze dryer, a reduced pressure dryer, a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary dryer, an agitator dryer, etc. In this manner, toner base particles can be produced by a pulverization method.

[0123] (Addition of external additives) The obtained toner base particles are subjected to external addition treatment with an external additive. The external addition treatment can be performed by blending a predetermined amount of the toner base particles and the external additive, and stirring and mixing them using a mixer. Examples of the mixer include a double con mixer, a V-type mixer, a drum mixer, a super mixer, a Henschel mixer, a Nauta mixer, Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.), and a Nobilta (manufactured by Hosokawa Micron Corporation).

[0124] [4. Image forming method and image forming apparatus] An image forming apparatus that can be used in the image forming method of this embodiment will be described below. Examples of image forming apparatuses include those used in general electrophotographic image forming methods. Examples of image forming apparatuses include those having a photoreceptor (electrostatic latent image carrier), a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit. The charging unit applies a uniform potential to the surface of the photoreceptor by corona discharge of the same polarity as the toner or discharge by a roller brush. The exposure unit forms an electrostatic latent image on the uniformly charged surface of the photoreceptor by image exposure based on image data. The developing unit transports toner to the surface of the photoreceptor to visualize the electrostatic latent image and form a toner image. The transfer unit transfers the toner image formed by the developing unit to a transfer material via an intermediate transfer member as necessary. The fixing unit fixes the toner image on the transfer material. An example of such an image forming apparatus is the image forming apparatus shown in FIG. 1. FIG. 1 is a schematic diagram showing an example of the configuration of an image forming apparatus used in the image forming method. FIG. 1 is an explanatory cross-sectional view showing an example of the configuration of a full-color image forming apparatus that uses toner as a non-magnetic one-component developer.

[0125] 1, a charging brush 111, which is a charging means for uniformly charging the surface of the photosensitive drum 10 to a predetermined potential, is provided around the photosensitive drum 10, which is driven to rotate. Also, a cleaner 112 is provided around the photosensitive drum 10 to remove toner remaining on the photosensitive drum 10.

[0126] Also provided is a laser scanning optical system 20, which is an exposure means that scans and exposes the photosensitive drum 10, which has been charged by the charging brush 111, with a laser beam. This laser scanning optical system 20 is a well-known system that incorporates a laser diode, a polygon mirror, and an fθ optical element, and its control unit receives print data for yellow, magenta, cyan, and black from a host computer. This laser scanning optical system 20 then outputs laser beams in sequence based on the print data for each color, scanning and exposing the photosensitive drum 10, thereby sequentially forming electrostatic latent images for each color on the photosensitive drum 10.

[0127] Further, a full-color developer cartridge 30 is provided as a developing means for supplying toner of each color to the photosensitive drum 10 on which the electrostatic latent image is formed, thereby performing full-color development. The full-color developer cartridge 30 has four color-specific developer cartridges 31Y, 31M, 31C, and 31Bk, each containing non-magnetic single-component toner of yellow, magenta, cyan, and black, arranged around a support shaft 33. The full-color developer cartridge 30 rotates around the support shaft 33, and each developer cartridge 31Y, 31M, 31C, and 31Bk is guided to a position facing the photosensitive drum 10.

[0128] In each of the developer cartridges 31Y, 31M, 31C, and 31Bk in the full-color developer cartridge 30, as shown in FIG. 2, a toner regulating member (e.g., a regulating blade) is pressed against (contacts) the outer peripheral surface of the developer carrier (developing roller) 25, which rotates to transport toner. This toner regulating member regulates the amount of toner transported by the developing roller 25 and also charges the transported toner. For example, in the image forming method of this embodiment, it is preferable that the toner be charged on the surface of the developing roller using a regulating blade.

[0129] As described above, the full-color developer cartridge 30 is configured to rotate about the support shaft 33 each time an electrostatic latent image of each color is formed on the photosensitive drum 10 by the laser scanning optical system 20. This allows the developer cartridges 31Y, 31M, 31C, and 31Bk containing toner of the corresponding color to be sequentially guided to a position facing the photosensitive drum 10. Then, the developing roller 25 of each developer cartridge 31Y, 31M, 31C, and 31Bk is brought into contact with the photosensitive drum 10 or not, and charged toner of each color is sequentially supplied onto the photosensitive drum 10 on which the electrostatic latent images of each color have been formed sequentially as described above, thereby performing development.

[0130] Furthermore, a rotationally driven endless intermediate transfer belt 40 is provided as an intermediate transfer body downstream of the full-color developer cartridge 30 in the rotation direction of the photosensitive drum 10. The intermediate transfer belt 40 is rotated in synchronization with the photosensitive drum 10. The intermediate transfer belt 40 is pressed by a rotatable primary transfer roller 41 so as to come into contact with the photosensitive drum 10. A secondary transfer roller 43 is rotatably provided at a portion of a support roller 42 that supports the intermediate transfer belt 40, and a transfer material S, such as recording paper, is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43.

[0131] Furthermore, a cleaner 50 for scraping off residual toner on the intermediate transfer belt 40 is provided in the space between the full-color developing cartridge 30 and the intermediate transfer belt 40 so as to be movable toward and away from the intermediate transfer belt 40 .

[0132] Furthermore, paper feed means 60 that guides transfer material S to intermediate transfer belt 40 is composed of a paper feed tray 61 that stores transfer material S, a paper feed roller 62, and a timing roller 63. The paper feed roller 62 is for feeding the transfer material S stored in the paper feed tray 61 one sheet at a time. The timing roller 63 is for feeding the fed transfer material S in synchronization with the image formed on the intermediate transfer belt 40, between the intermediate transfer belt 40 and secondary transfer roller 43. Then, the transfer material S sent between the intermediate transfer belt 40 and the secondary transfer roller 43 is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43, so that the toner image from the intermediate transfer belt 40 is pressed and transferred onto the transfer material S.

[0133] Meanwhile, the transfer material S onto which the toner image has been pressed and transferred as described above is guided to fixing means 70 by conveying means 66 formed of an air suction belt or the like. The toner image transferred by this fixing means 70 is fixed onto the transfer material S, and then the transfer material S is discharged onto the top surface of the apparatus main body 100 through a vertical conveying path 80.

[0134] Next, the operation of forming a full-color image using this full-color image forming apparatus will be specifically described.

[0135] First, the photosensitive drum 10 and the intermediate transfer belt 40 are rotated in their respective directions at the same peripheral speed, and the photosensitive drum 10 is charged to a predetermined potential by the charging brush 111 .

[0136] The thus-charged photosensitive drum 10 is then exposed to a yellow image by the laser scanning optical system 20, forming an electrostatic latent image of the yellow image on the photosensitive drum 10. Thereafter, yellow toner charged by the toner regulating member is supplied from the developing cartridge 31Y containing yellow toner to the photosensitive drum 10, thereby developing the yellow image. Then, the intermediate transfer belt 40 is pressed against the photosensitive drum 10 on which the yellow toner image has been formed by the primary transfer roller 41, and the yellow toner image formed on the photosensitive drum 10 is primarily transferred to the intermediate transfer belt 40.

[0137] After the yellow toner image has been transferred to the intermediate transfer belt 40 in this manner, the full-color developer cartridge 30 is rotated about the support shaft 33, and the developer cartridge 31M containing magenta toner is brought into a position facing the photosensitive drum 10. Then, as with the yellow image, a magenta image is exposed to the photosensitive drum 10 charged by the laser scanning optical system 20 to form an electrostatic latent image, and this electrostatic latent image is developed by the developer cartridge 31M containing magenta toner. The developed magenta toner image is then primarily transferred from the photosensitive drum 10 to the intermediate transfer belt 40. Thereafter, the cyan and black images are exposed, developed, and primarily transferred in the same manner, in order, and the yellow, magenta, cyan, and black toner images are sequentially superimposed on the intermediate transfer belt 40 to form a full-color toner image.

[0138] Then, when the final black toner image has been primarily transferred onto the intermediate transfer belt 40, the transfer material S is sent between the secondary transfer roller 43 and the intermediate transfer belt 40 by the timing roller 63, and the transfer material S is pressed against the intermediate transfer belt 40 by the secondary transfer roller 43. In this way, the full-color toner image formed on the intermediate transfer belt 40 is secondarily transferred onto the transfer material S.

[0139] Then, once the full-color toner image has been secondarily transferred onto the transfer material S in this manner, the transfer material S is guided to the fixing means 70 by the conveying means 66, and the transferred full-color toner image is fixed onto the transfer material S by the fixing means 70. Thereafter, the transfer material S is discharged onto the top surface of the apparatus main body 100 through the vertical conveying path 80.

[0140] 2 is an explanatory cross-sectional view showing an example of the configuration of a developer cartridge for a one-component developer. The developer cartridge 31 shown in FIG. 2 has at least a developer roller 25 and a regulating blade 28, and is used as a developing device for a non-magnetic one-component toner.

[0141] The developing cartridge 31 has a buffer chamber 26 adjacent to the developing roller 25 and a hopper 27 adjacent to the buffer chamber 26 .

[0142] A regulating blade 28, which is a toner regulating member, is disposed in the buffer chamber 26 while being pressed against (in contact with) the developing roller 25. The regulating blade 28 regulates the charge amount and adhesion amount (transport amount) of toner on the developing roller 25. It is also possible to further provide an auxiliary blade 29 downstream of the regulating blade 28 in the direction of rotation of the developing roller 25 to assist in regulating the charge amount and adhesion amount of toner on the developing roller 25.

[0143] A supply roller 34 is pressed against the developing roller 25. The supply roller 34 is driven to rotate in the same direction as the developing roller 25 (counterclockwise in the figure) by a motor (not shown). The supply roller 34 has a conductive cylindrical base and a foam layer made of urethane foam or the like on the outer periphery of the base.

[0144] Hopper 27 contains toner T, a non-magnetic single-component developer. Hopper 27 is also provided with a rotor 35 that agitates toner T. A film-like transport blade is attached to rotor 35, and toner T is transported by rotation of rotor 35 in the direction of the arrow. Toner T transported by the transport blade is supplied to buffer chamber 26 through passage 32 provided in a partition wall separating hopper 27 from buffer chamber 26. The transport blade is shaped so that as rotor 31 rotates, it bends while transporting toner T in the forward direction of the blade's rotation, and then returns to a straight state when it reaches the left end of passage 32. In this way, the blade supplies toner T to passage 32 by changing its shape from a curved state to a straight state again.

[0145] Furthermore, a valve 321 that closes the passage 32 is provided in the passage 32. This valve 321 is a film-like member, and one end is fixed to the upper right side of the passage 32 of the partition wall. When toner T is supplied from the hopper 27 to the passage 28, this valve 321 is pushed to the right by the pressing force of the toner T, thereby opening the passage 32. As a result, toner T is supplied into the buffer chamber 26.

[0146] In the developer cartridge 31, during image formation, the developer roller 25 rotates in the direction of the arrow, and the rotation of the supply roller 34 supplies toner from the buffer chamber 26 onto the developer roller 25. The toner T supplied onto the developer roller 25 is charged and thinned by the regulating blade 28 and auxiliary blade 29, and then transported to the area facing the image carrier to develop the electrostatic latent image on the image carrier. Toner not used for development is neutralized by the charge eliminating blade 24 as the developer roller 25 rotates. After the electrostatic adhesion between the developer roller 25 and the toner is reduced, the toner is scraped off from the developer roller 25 by the supply roller 34 and collected.

[0147] The regulating blade 28 shown in FIG. 3 is installed in the developing cartridge 31 for the purpose of uniformly forming a thin layer of toner on the surface of the developing roller 25 and uniformly charging the toner.

[0148] The regulating blade 28 can be made of phosphor bronze, which has spring elasticity that can uniformly thin and charge non-magnetic one-component toner and control the average contact pressure on the developing roller within a specified range. Phosphor bronze can impart a stable charge to non-magnetic one-component toner compared to other metallic elastic materials (e.g., stainless steel). This is presumably because the charge sequence of phosphor bronze is more positive than that of stainless steel, allowing it to impart a more stable charge to non-magnetic one-component toner than stainless steel.

[0149] The regulating blade 28 is fixed by a holder, and is attached to the developing cartridge 31 while being fixed to the holder. [Example]

[0150] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%", "ppm", and "parts" mean "% by mass", "ppm by mass", and "parts by mass", respectively.

[0151] [Preparing materials] <Saturated hydrocarbon compounds with carbon numbers of 16 to 35> Saturated hydrocarbons with carbon numbers of 20, 26, 30, and 34 (manufactured by GL Sciences) were dispensed in a mass ratio of 20:30:30:20 and melt-mixed at 80° C. The melt-mixed saturated hydrocarbons were then cooled and solidified to obtain saturated hydrocarbon compounds with carbon numbers of 16 to 35.

[0152] <Wax (mold release agent)> (Hydrocarbon wax (microcrystalline wax)) A microcrystalline wax with a melting point of 82 ° C was prepared by solvent crystallization and filtration from the residual oil obtained by vacuum distillation. This microcrystalline wax was repeatedly subjected to molecular distillation until the average carbon number was 41 and components with a carbon number of 16 to 35 were no longer detectable, thereby obtaining a microcrystalline wax as a release agent. The molecular distillation was carried out at a temperature of 240 ° C and a pressure of 0.2 Pa to remove low molecular weight components, followed by removal of other components at a temperature of 400 ° C and a pressure of 0.2 Pa. The carbon number was qualitatively analyzed by GC-MS and quantitatively detected by GC-FID. The melting point of the obtained microcrystalline wax was 73 ° C.

[0153] (Ester wax (behenic acid behenate)) Commercially available behenic acid behenate was used as the release agent.

[0154] <Toner> (Synthesis of amorphous polyester resin A1) Terephthalic acid: 40.2 parts by mass Propylene oxide adduct of bisphenol A (BPA-PO): 29.0 parts by mass Dipropanol: 30.8 parts by mass Tin 2-ethylhexanoate (esterification catalyst): 0.5 parts by mass The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. After the atmosphere in the reaction vessel was replaced with nitrogen gas, the temperature was gradually raised with stirring, and the mixture was allowed to react at 140°C for 3 hours with stirring.

[0155] Next, the pressure inside the reaction vessel was reduced to 8.0 kPa, and the temperature was raised to 200°C with stirring, and the reaction was carried out for 4 hours.

[0156] Thereafter, the pressure in the reaction vessel was reduced to 5 kPa or less again, and the mixture was reacted at 200°C for 3 hours to obtain amorphous polyester resin A1. The amorphous polyester resin had a glass transition temperature of 52°C and a softening point of 110°C.

[0157] (Synthesis of crystalline polyester resin B1) ·Adipic acid: 40.9 parts by mass 1,5-pentanediol: 59.1 parts by mass Tin 2-ethylhexanoate: 0.50 parts by mass The above materials were placed in a reaction vessel equipped with a cooling tube, a stirrer, a nitrogen inlet tube, and a thermocouple. The atmosphere in the reaction vessel was then replaced with nitrogen gas, and the temperature was gradually increased while stirring. The materials were reacted at 140°C for 3 hours while stirring.

[0158] Next, the pressure in the reaction vessel was reduced to 8.3 kPa, and the temperature was raised to 200°C with stirring, and the reaction was carried out for 1 hour to obtain crystalline polyester B1. The melting point of the crystalline polyester resin was 65°C.

[0159] (Production of toner base 1) Amorphous polyester resin A1: 88.2 parts by mass Crystalline polyester B1: 11.8 parts by mass Hydrocarbon wax: 5.0 parts by mass Saturated hydrocarbon compounds having 16 to 35 carbon atoms: 0.05 parts by mass Charge control agent (salicylic acid metal complex): 1.0 parts by mass Colorant: 12 parts by weight The following pigments were used as colorants: A yellow pigment (Pigment Yellow 74) was used to prepare a yellow toner; a magenta pigment (Quinacridone) was used to prepare a magenta toner; a cyan pigment (Phthalocyanine Blue (CI Pigment Blue 15:3)) was used to prepare a cyan toner; and a black pigment (Carbon Black) was used to prepare a black toner.

[0160] The above materials were mixed in a Henschel mixer at 40 m s -1The mixture was mixed at a speed of 1000 kJ / min for a rotation time of 5 min. The mixture was then kneaded in a twin-screw kneader set at a temperature of 130°C. The resulting mixture was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product. The resulting coarsely pulverized product was then finely pulverized using a mechanical pulverizer. The pulverized precursor was then classified using an air classifier to obtain particles with a volumetric median diameter of 6.4 μm.

[0161] The particles that had been classified were dried using an airflow dryer. The operating conditions were a hot air temperature of 130°C and a drying time of 30 minutes to obtain toner particles 1. The circularity of the toner was 0.96.

[0162] (Production of toner bases 2 to 9) Toner bases 2 to 9 were prepared in the same manner as in the production of toner base 1, except that the amount of the saturated hydrocarbon compound having 16 to 35 carbon atoms was changed as shown in Table 1.

[0163] (Production of toner bases 10 to 14) Toner base particles 10 to 14 were prepared in the same manner as in the production of toner base particle 1, except that the temperature and time of the drying treatment were changed so as to obtain the circularity shown in Table 1.

[0164] (Production of toner base 15) Toner base 15 was prepared in the same manner as in the production of toner base 1, except that the hydrocarbon wax was changed to an ester wax as shown in Table 1.

[0165] (Production of toner base 16) Toner base 16 was prepared in the same manner as toner base 1, except that, as shown in Table 1, the hydrocarbon wax was changed to 3.5 parts by mass of hydrocarbon wax and 1.5 parts by mass of ester wax.

[0166] (Production of toner bases 17 to 23) Toner base materials 17 to 23 were prepared in the same manner as in the production of toner base material 1, except that the amount of crystalline polyester was changed as shown in Table 1.

[0167] (Synthesis of amorphous polyester resin A2 having vinyl resin segments) A mixture of the following vinyl resin monomer, a monomer having a substituent reactive with both the amorphous polyester resin and the vinyl resin, and a polymerization initiator was placed in a dropping funnel. Styrene: 80.0 parts by mass n-Butyl acrylate: 20.0 parts by mass Acrylic acid: 10.0 parts by mass Di-t-butyl peroxide (polymerization initiator): 16.0 parts by mass

[0168] Furthermore, the following monomers for the amorphous polyester resin were placed in a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve them. Bisphenol A ethylene oxide 2 mole adduct: 59.1 parts by mass Bisphenol A propylene oxide 2 mole adduct: 281.7 parts by mass Terephthalic acid: 63.9 parts by mass Succinic acid: 48.4 parts by mass

[0169] The mixture in the dropping funnel was added dropwise to a four-neck flask over 90 minutes while stirring, and after aging for 60 minutes, unreacted monomer was removed under reduced pressure (8 kPa). 0.4 parts by mass of Ti(OBu)4 was then added as an esterification catalyst, and the mixture was heated to 235°C and reacted under normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0170] The mixture was then cooled to 200°C and reacted under reduced pressure (20 kPa), after which the solvent was removed to obtain an amorphous polyester resin having a vinyl resin segment. The obtained amorphous polyester resin had a glass transition temperature (Tg) of 60°C.

[0171] (Production of toner base 24) Toner base 24 was prepared in the same manner as toner 1, except that in the production of toner base 1, amorphous polyester resin A1 was changed to amorphous polyester resin A2 having a vinyl resin segment as shown in Table 1.

[0172] (Synthesis of styrene acrylic resin C1) Styrene: 80.0 parts by mass Butyl acrylate: 20.0 parts by mass Di-tert-butyl peroxide (NOF Corporation, Perbutyl D): 1.00 parts by mass 100 parts by mass of propylene glycol monomethyl ether was heated while purging with nitrogen and refluxed at a temperature of 120°C or higher, to which the mixture of materials described above was added dropwise over 3 hours. After the addition was completed, the solution was stirred for 3 hours and then distilled under atmospheric pressure while raising the temperature to 170°C. After the temperature reached 170°C, the solvent was removed by distillation under reduced pressure at 1 hPa for 1 hour to obtain a resin solid. This resin solid was dissolved in tetrahydrofuran and reprecipitated with n-hexane. The precipitated solid was filtered to obtain styrene acrylic resin C1.

[0173] (Toner base 25 production) Toner base 25 was prepared in the same manner as toner 1, except that in the production of toner base 1, the amorphous polyester resin A1 was changed to styrene acrylic resin C1 as shown in Table 1.

[0174] (Production of toner base 26) Toner base 26 was prepared in the same manner as toner 1, except that in the production of toner base 1, the amorphous polyester resin A1 was changed to 80 parts by mass and the styrene acrylic resin C1 was changed to 8.2 parts by mass, as shown in Table 1.

[0175] (Toner 1 production) To 100 parts by mass of particles of toner base 1, the following external additives A, B, and C were added and mixed for 1 minute using a Henschel mixer at a peripheral speed of 35 m / s. The Henschel mixer was then stopped and mixing was continued for an additional 5 minutes. The mixture was sieved using a mesh with 43 μm openings to obtain toner particles 1. External additive A (R972 (manufactured by Nippon Aerosil Co., Ltd.)): 1.0 parts by mass External additive B (X24-9600A (Shin-Etsu Chemical Co., Ltd.)): 1.5 parts by mass External additive C (Eposter S (Nippon Shokubai)): 0.4 parts by mass

[0176] (Toner 2-14, 25-36 production) In the production of Toner 1, Toners 2 to 14 and 25 to 36 were prepared in the same manner as Toner 1, except that the toner base was changed as shown in Table 1.

[0177] The "Binder Resin" column in the "Toner Base" section of Table 1 indicates the type of resin used as the binder resin. The "Crystalline Pes" column in the "Toner Base" section indicates whether or not crystalline polyester B1 was used, and the "Binder Resin" column indicates the type of resin other than crystalline polyester B1 used as the binder resin. Here, in the "Binder Resin" column, "Pes" indicates that amorphous polyester resin A1 was used as the binder resin. Similarly, hereinafter, in the same column, "Vinyl Pes" indicates that amorphous polyester resin A2 having a vinyl resin segment was used as the binder resin. "Pes / StAc" indicates that amorphous polyester resin A1 and styrene acrylic resin C1 were used as the binder resin. "StAc" indicates that styrene acrylic resin C1 was used as the binder resin. When crystalline polyester B1 was used as the binder resin, "Yes" is entered in the "Crystalline Pes" column. On the other hand, when the crystalline polyester B1 was not used as the binder resin, "none" is entered in the "Crystalline Pes" column.

[0178] (Toner 15-24 production) Toners 15 to 24 were prepared in the same manner as Toner 1, except that the added parts of External Additive B and External Additive C were changed as shown in Table 1 in the production of Toner 1.

[0179] (Content of saturated hydrocarbon compounds with carbon numbers of 16 to 35 in toner) For toners 1 to 36, the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms in the toner was measured by the following method. First, the saturated hydrocarbon compounds were separated from the toner using a solvent that dissolves the saturated hydrocarbon compounds. Then, the saturated hydrocarbon compounds separated in the solvent were qualitatively analyzed by gas chromatography mass spectrometry (GC-MS). Furthermore, the specific saturated hydrocarbon compounds separated in the solvent were quantified by gas chromatography with flame ionization detection (GC-FID) using a flame ionization detector (FID) as the detector. The specific methods for qualitatively and quantitatively analyzing the saturated hydrocarbon compounds were performed in accordance with the measurement methods described in this embodiment. The results are shown in the column "C16 to C35 hydrocarbons (ppm by mass)" in Table 1.

[0180] (Average coverage of external additives (particles A and B) in toner) For toners 1 to 36, the average coverage (area %) of toner particle A was determined by image analysis using a scanning electron microscope, and the average coverage (area %) of toner particle A was determined. Note that particle A is a particle with a particle diameter of 80 nm or more and less than 200 nm as observed using a scanning electron microscope. Particle B is a particle with a particle diameter of 200 nm or more and 500 nm as observed using a scanning electron microscope. Note that the particle diameters of the particles constituting the external additives and the calculation of the average coverage (area %) of particle A and particle B were performed using the same method as described in the image forming method of this embodiment. The average coverage (area %) of toner particle A is shown in the "Average coverage (area %)" column for "Particle A" in Table 2. The average coverage (area %) of toner particle B is shown in the "Average coverage (area %)" column for "Particle A" in Table 2.

[0181] [Evaluation method (image formation)] Using commercially available printers "COREFIDO C844dnw" (manufactured by Oki Electric Industry Co., Ltd.) and "PLAVI Pro1040" (manufactured by Oki Electric Industry Co., Ltd.) as image forming devices, printing was performed to form a full-page solid image on one sheet under the following conditions: The printer was set to a room temperature and humidity environment (temperature 20°C, humidity 50% RH) with 4.0 g of yellow toner and 4.0 g of cyan toner. Then, as a test image, printing was performed to form a full-page solid image on one sheet with solid images printed in yellow (Y), cyan (C), and green (G).

[0182] The recording media used in the printing to form the images are as follows. Long paper 1: 297 x 900 mm, high-quality paper (Nakagawa Seisakusho, basis weight 128 g·m 2 ) Long paper 2: 297 x 1200 mm, high-quality paper (Nakagawa Seisakusho, basis weight 128 g·m 2 ) Roll paper: npi wood-free paper (Nippon Paper Industries, basis weight 127.9 g·m 2 )

[0183] (Evaluation of image density difference between leading and trailing edges) The output (printed) test image was measured using a Spectrolina / Scan Bundle (manufactured by Gretag Macbeth) under the following conditions: <Measurement conditions> Light source: D50 light source Field of view: 2° Concentration: ANSI T White standard: ABS Filter: UV Cut Measurement mode: Reflectance Language:Japanese

[0184] In the above measurement, the difference in image density (ID) between a solid image of cyan (C) at the leading edge of the image and the same image at the trailing edge of the image was calculated. Then, the image density difference between the leading edge and the trailing edge was evaluated using the following evaluation criteria. In the evaluation criteria below, evaluation A indicates the smallest image density difference between the leading edge and the trailing edge, and is good. The image density difference between the leading edge and the trailing edge increases in the order of evaluation B, evaluation C, and evaluation D. In the evaluation of the image density difference between the leading edge and the trailing edge, evaluations A to C were considered acceptable. -Evaluation criteria- A: The image density difference is 0 to 0.03. B: The image density difference is 0.04 to 0.10. C: The image density difference is 0.11 to 0.20. D: The image density difference is 0.21 or more.

[0185] (Evaluation of transfer failure occurrence) The output (printed) test image was visually checked for the occurrence of transfer defects, and the occurrence of transfer defects was evaluated according to the following evaluation criteria. The occurrence of transfer defects was checked for discharge noise and insufficient transfer of yellow from green, and if no transfer defects occurred, it was considered good and rated A. On the other hand, if the occurrence of discharge noise was confirmed, the L * a * b * The color difference (ΔEab) between the leading edge and the trailing edge was calculated and evaluated according to the following evaluation criteria. In the evaluation of the occurrence of transfer defects, a rating of A to B was considered acceptable. -Evaluation criteria- A: No transfer defects occurred and transfer was good. B: The color difference (ΔEab) between the leading edge and trailing edge is 5 or less. C: The color difference (ΔEab) between the leading edge and the trailing edge is more than 5.

[0186] (Filming evaluation) As a test image, a cyan (C) solid image was printed over the entire surface, and the presence or absence of toner filming on the photoreceptor was visually confirmed. Visual confirmation was continued up to 50 consecutive prints, and filming was evaluated according to the following evaluation criteria. In the filming evaluation, a rating of A to B was considered acceptable. -Evaluation criteria- A: Even when the number of continuous prints reached 50, no toner filming occurred and printing was performed satisfactorily. B: Although slight toner filming occurs within 50 consecutive prints, there is no practical problem if no image defects result from it. C: Image defects occurred before 50 sheets were continuously printed.

[0187] [Table 1]

[0188] [Table 2]

[0189] [Table 3]

[0190] (result) The images formed in Examples 1 to 32 showed good results in the evaluation of the difference in image density between the leading edge and the trailing edge, the occurrence of transfer defects, and filming. On the other hand, the images formed in Comparative Examples 1 to 4 showed an extremely large difference in image density between the leading edge and the trailing edge, and also failed the evaluation of the occurrence of transfer defects. Furthermore, the image formed in Comparative Example 3 also showed image defects in the evaluation of filming before the number of continuous prints reached 50. [Industrial Applicability]

[0191] According to the present invention, it is possible to provide an image forming method for forming an image on at least a long sheet of paper using toner. [Explanation of symbols]

[0192] 10 Photosensitive drum 20 Laser scanning optical system 24 Anti-static blade 25 Developing roller 26 Buffer Room 27 Hopper 28 Regulatory Blade 29 Auxiliary Blade 30 Full color developing cartridge 31 Developer cartridge 32 Passage 33 Spindle 34 Supply roller 35 Rotating Body 40 Intermediate transfer belt 41 Primary transfer roller 42 Support roller 43 Secondary transfer roller 50 Cleaner 60 Paper feeding means 61 Paper tray 62 Paper feed roller 63 Timing roller 66 Transportation 70 Fixing Method 80 Vertical conveyor 100 Device body 110, 210 Toner image 110A, 210A surface 111 Charging Brush 112 Cleaner 120, 220 wax 130 Short-chain saturated hydrocarbon compounds 321 Valve S Transfer material T Toner

Claims

1. 1. An image forming method for forming an image on at least a long sheet of paper using a toner containing at least a binder resin, a wax, and an external additive, comprising: the binder resin is a mixture of at least a crystalline polyester resin and an amorphous polyester resin, and the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms in the toner is 1 to 1,000 ppm by mass.

2. 2. The image forming method according to claim 1, wherein the length of the long paper is 900 mm or more.

3. 3. The image forming method according to claim 2, wherein the length of the long paper is 1300 mm or more.

4. 3. The image forming method according to claim 1, wherein the wax contains at least a hydrocarbon wax.

5. 3. The image forming method according to claim 1, wherein the content of the saturated hydrocarbon compound having 16 to 35 carbon atoms in the toner is 100 to 700 ppm by mass.

6. 3. The image forming method according to claim 1, wherein the toner is charged onto the surface of the developing roller using a regulating blade.

7. 3. The image forming method according to claim 1, wherein the amorphous polyester resin comprises an amorphous polyester resin having a vinyl resin segment containing at least a structural unit derived from a vinyl monomer.

8. the external additive contains at least fine particles A having a particle diameter of 80 nm or more and less than 200 nm as confirmed by a scanning electron microscope of the toner, 3. The image forming method according to claim 1, wherein the average coverage of the toner with the fine particles A determined by image analysis of the toner using a scanning electron microscope is 5 area % or more and 40 area % or less.

9. the external additive contains at least fine particles B having a particle diameter of 200 nm or more and 500 nm or less as confirmed by a scanning electron microscope of the toner, 3. The image forming method according to claim 1, wherein an average coverage of the toner with the fine particles B determined by image analysis of the toner using a scanning electron microscope is 0.1 area % or more and 5 area % or less.

10. 3. The image forming method according to claim 1, wherein the circularity of the toner is 0.950 to 0.

990.

11. 3. The image forming method according to claim 1, wherein the content of the crystalline polyester resin in the toner is 2 to 20% by mass.

Images