Image forming method and image forming system

Abstract

To provide an image forming method and an image forming system excellent in blocking resistance and coating properties of varnish in an image using a resin-made recording medium.SOLUTION: An image forming method of the present invention is an image forming method of an electrophotographic system including a step of fixing toner for electrostatic charge image development to a resin-made recording medium to form an image. The content of a saturated hydrocarbon compound having 16 or more and 35 or less carbon atoms is 1000 mass ppm or less relative to the total mass of the toner for electrostatic charge image development. When an image with a coating weight of 4 g / m2 or more is formed on the resin-made recording medium, the apex density Spd of peaks on a surface of the image is 5000 mm-2 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming method and an image forming system, and more particularly to an image forming method and the like that is excellent in blocking resistance and varnish coatability in images formed on a resin recording medium. [Background technology]

[0002] As recording media have become more diverse in recent years, there has been an increasing demand for printing on film, which is a resin recording medium. Resin recording media are used in roll-to-roll printing and processing technology. In this printing and processing technology, a roll of resin recording media is passed through a conveyor line equipped with processing devices for printing, coating, and heat treatment, and finally wound up on a take-up roll at the end of the line. Images printed on resin recording media using this process have several issues with image durability. The toner disclosed in Patent Document 1 contains a constituent part derived from a polypropylene resin in the binder resin, but there is a problem with adhesion to a recording medium due to the unevenness of the image surface.

[0003] Therefore, in order to improve the quality and durability of images printed by the roll-to-roll method using a resin recording medium, a varnish coating is sometimes applied to part or the entire surface of the image. The varnish used in the varnish coat has low affinity with the wax contained in the toner as a release agent, which causes problems such as the varnish coat being easily repelled during application and poor adhesion between the coated image and the varnish. To solve these problems, Patent Document 2 discloses that a varnish, which is an overcoat composition containing a specific polymerizable compound, is used, thereby suppressing varnish repellency and improving adhesion. Patent Document 2 also discloses that when using the varnish, it is preferable to use isoparaffin as a toner release agent. Patent Document 3 discloses a method for producing a printed matter in which an image is formed on the surface of the image on which a specific amount of wax is distributed at a specific uneven distribution rate. The method describes that by appropriately unevenly distributing the wax on the image surface, the proportion of toner that comes into contact with the varnish is increased, thereby improving adhesion between the varnish and the toner image. The method also describes that by appropriately unevenly distributing the wax on the image surface, the proportion of toner that comes into contact with the varnish is increased, thereby improving adhesion between the varnish and the toner image.

[0004] However, the adhesion between the varnish and the toner image was still insufficient in the techniques of Patent Documents 2 and 3. In addition, when resin recording media on which an image has been formed are stacked, there is a problem of blocking, in which the image is transferred to the back surface of the resin recording media due to contact between the back surface of the resin recording media and the image. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-204030 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-078565 [Patent Document 3] Japanese Patent Publication No. 2021-036298 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above problems and circumstances, and its problem to be solved is to provide an image forming method and image forming system that have excellent blocking resistance and varnish applicability for images formed using a resin recording medium. [Means for solving the problem]

[0007] The present inventors have investigated the causes of the above problems in order to solve the above problems, and have found that when an image is formed using a toner containing a specific amount or less of saturated hydrocarbon compounds having a carbon number of 16 to 35, by setting the peak density Spd on the image surface within a specific range, blocking resistance and varnish coatability can be improved in images formed on resin recording media. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1. An electrophotographic image forming method including a step of fixing an electrostatic image developing toner on a resin recording medium to form an image, the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms is 1000 ppm by mass or less relative to the total mass of the toner for developing electrostatic images, The resin recording medium was applied with a deposition amount of 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 That's all An image forming method comprising:

[0009] 2. The content of the saturated hydrocarbon compound is 1 ppm by mass or more relative to the total mass of the toner for developing electrostatic images. 2. The image forming method according to claim 1,

[0010] 3. The resin recording medium is a continuous-feed medium. 2. The image forming method according to claim 1,

[0011] 4. The thickness of the resin recording medium is 75 μm or less. 2. The image forming method according to claim 1,

[0012] 5. The resin recording medium is a polyethylene terephthalate film having a thickness of 50 μm. 2. The image forming method according to claim 1,

[0013] 6. The electrostatic image developing toner contains a binder resin, The binder resin contains at least an amorphous polyester and a crystalline polyester. 2. The image forming method according to claim 1,

[0014] 7. The content of the amorphous polyester in the binder resin is within the range of 5 to 80 mass %. 7. The image forming method according to claim 6, wherein

[0015] 8. The polyhydric alcohol of the amorphous polyester is an aliphatic polyhydric alcohol or an alicyclic polyhydric alcohol. 7. The image forming method according to claim 6, wherein

[0016] 9. The polyhydric alcohol is an acyclic aliphatic polyhydric alcohol having 5 or more carbon atoms. 9. The image forming method according to claim 8, wherein

[0017] 10. The binder resin contains an amorphous resin having a weight-average molecular weight in the range of 50,000 to 500,000. 7. The image forming method according to claim 6.

[0018] 11.Having a process of applying varnish 2. The image forming method according to claim 1,

[0019] 12. An electrophotographic image forming system having a toner for developing an electrostatic image and a means for fixing the toner for developing an electrostatic image to form an image, the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms is 1000 ppm by mass or less relative to the total mass of the toner for developing electrostatic images, The resin recording medium was applied with a deposition amount of 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 That's all An image forming system comprising: [Effects of the Invention]

[0020] The above-described means of the present invention can provide an image forming method and an image forming system that are excellent in blocking resistance and varnish applicability in images formed using a resin recording medium. 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. According to the image forming method of the present invention, the adhesion amount of 4 g / m2 to the resin recording medium is 2 When the above image is formed, the peak density Spd on the image surface is set to 5000 mm -2 As a result, when a load is applied, as shown in Figure 1, the peaks Pb of the image peaks are more likely to come into contact with the back surface Ra of the resin recording medium R than the smooth surface Pa of the image P (areas other than the peaks of the image). As a result, when the recording media on which the image is formed are superimposed, the back surface Ra of the recording medium R and the image P come into point contact, which suggests that the amount of image transfer to the recording medium R is small. On the other hand, the peak density Spd is set to 5000 mm -2 When a load is applied, the rear surface Ra of the recording medium R and the smooth surface Pa of the image P (area other than the ridges) tend to come into contact, as shown in Figure 2. Therefore, when recording media on which an image has been formed are superimposed, the rear surface Ra of the recording medium R and the image P come into surface contact, which is presumably why the amount of image transferred to the recording medium R increases.

[0021] However, when applying varnish to an image with a high peak density (Spd), the image surface has many peaks, i.e., a fractal structure with many irregularities. This means that the varnish droplets are easily repelled and do not spread over the image surface, which leads to a problem of poor varnish application. On the other hand, saturated hydrocarbon compounds with carbon atoms of 16 to 35 do not have a very high affinity with varnish. Also, due to their short chain length, the saturated hydrocarbon compounds ooze out onto the image surface during heat fixation, covering the image surface and making it more likely to repel varnish. Therefore, since a fractal structure with a large peak density Spd and many irregularities is a structure that easily repels varnish, by setting the content of the saturated hydrocarbon compound to 1000 mass ppm or less, it is possible to suppress varnish repelling even in the case of a fractal structure. In addition, saturated hydrocarbon compounds with a carbon number of 15 or less are low molecular weight and low viscosity components, so they are easily sublimated and do not pose a problem, so the content of saturated hydrocarbon compounds with a carbon number of 16 to 35 is specified. From the above, the density of peaks on the image surface, Spd, is set to 5000 mm -2 By setting the above content and keeping the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms in the toner to 1000 mass ppm or less, it is presumed that blocking resistance and varnish coatability can be achieved at the same time in images formed on resin recording media. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 10 is a diagram for explaining the contact state between the back surface of the recording medium and the image when the peak density Spd is 5000 mm-2 or more. [Figure 2] FIG. 10 is a diagram for explaining the contact state between the back surface of the recording medium and the image when the peak density Spd is less than 5000 mm [Figure 3] FIG. 1 is a diagram showing an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 4] A diagram showing the main parts of a control system of an image forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0023] The image forming method of the present invention is an electrophotographic image forming method including a step of fixing an electrostatic image developing toner on a resin recording medium to form an image, wherein the content of saturated hydrocarbon compounds having from 16 to 35 carbon atoms is 1000 mass ppm or less with respect to the total mass of the electrostatic image developing toner, and the amount of adhesion to the resin recording medium is 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 The present invention is characterized in that: The above features are technical features common to or corresponding to the following embodiments.

[0024] In an embodiment of the present invention, the content of the saturated hydrocarbon compound is preferably 1 ppm by mass or more relative to the total mass of the electrostatic image developing toner. That is, by adding a small amount of the saturated hydrocarbon compound having a short chain length, the saturated hydrocarbon compound acts as a crystal nucleating agent, and crystallization of the crystalline material including the release agent progresses, resulting in hardening. Therefore, the heat-resistant storage stability of the toner is improved.

[0025] It is preferable that the resin recording medium is a continuous medium, since this can be applied to roll-to-roll printing processing technology and can improve production efficiency. The thickness of the resin recording medium is preferably 75 μm or less. The thicker the resin recording medium, the less the influence of temperature and pressure from the recording medium side during fixing, making fixing failure more likely to occur. Therefore, if the thickness of the resin recording medium is 75 μm or less, it is possible to cover general-purpose recording media and obtain images without fixing failure. In particular, a polyethylene terephthalate film having a thickness of 50 μm is preferred as the resin recording medium in terms of fixability and adhesiveness.

[0026] It is preferable that the electrostatic image developing toner contains a binder resin, and that the binder resin contains at least an amorphous polyester and a crystalline polyester, thereby improving the melting property of the toner and facilitating the formation of an image with excellent fixability and adhesiveness.

[0027] The content of the amorphous polyester in the binder resin is preferably within a range of 5 to 80% by mass. By setting the content of the amorphous polyester within this range, the melting property of the resin is improved (molecular chains are easily entangled), and the surface roughness Spd is reduced to 5000 mm -2 As a result, the saturated hydrocarbon compound can be effectively precipitated during fixing, and both improved blocking resistance and varnish coatability can be easily achieved.

[0028] The polyhydric alcohol component of the amorphous polyester is preferably an aliphatic polyhydric alcohol component or an alicyclic polyhydric alcohol component. Acyclic aliphatic polyhydric alcohol components have a highly flexible skeleton (molecular chains rotate easily), which increases the melting ability of the resin (molecular chains become entangled easily), making it easier to achieve a surface roughness Spd within the specified range. The linearity of the acyclic aliphatic polyhydric alcohol component is thought to bring its molecular structure and polarity closer to those of the crystalline polyester, which facilitates effective precipitation of the saturated hydrocarbon compound during fixing, favoring both blocking resistance and varnish coatability.

[0029] The polyhydric alcohol component is preferably an acyclic aliphatic polyhydric alcohol having 5 or more carbon atoms. Acyclic aliphatic polyhydric alcohols have a highly flexible skeleton (molecular chains are easily rotated), which increases the melting property of the resin (molecular chains are easily entangled), making it easier to achieve a surface roughness Spd within the specified range. Furthermore, the linear molecular structure is thought to result in a molecular structure and polarity similar to that of crystalline polyester. This facilitates effective precipitation of the saturated hydrocarbon compound during fixing, which is preferable for achieving both blocking resistance and varnish coatability. Furthermore, if the acyclic aliphatic polyhydric alcohol has 5 or more carbon atoms, the hydrophobicity of the resin increases, which is preferable in that the hydrophobic interaction with the resin recording medium increases and good image strength (adhesion) can be obtained.

[0030] It is preferable that the binder resin contains an amorphous resin having a weight-average molecular weight in the range of 50,000 to 500,000, since this allows the peak density SPd to be controlled to a low value. That is, an amorphous resin having a weight-average molecular weight of 50,000 to 500,000 is a highly elastic component, which causes the resin to recover elasticity after separation from the belt during image formation. As a result, the number of traces (peaks) formed on the image due to separation can be reduced, and the peak density Spd can be reduced.

[0031] The image forming method of the present invention preferably includes a step of applying a varnish, as this improves image quality and durability, thereby enabling the effects of the present invention to be realized.

[0032] The image forming system of the present invention is an electrophotographic image forming system having an electrostatic image developing toner and a means for fixing the electrostatic image developing toner to form an image, wherein the content of saturated hydrocarbon compounds having a carbon number of 16 to 35 is 1000 mass ppm or less with respect to the total mass of the electrostatic image developing toner, and the amount of adhesion to the resin recording medium is 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 As a result, it is possible to achieve both blocking resistance and varnish coatability in images formed using a resin recording medium.

[0033] The present invention, its components, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0034] 1. Overview of the image forming method of the present invention The image forming method of the present invention is an electrophotographic image forming method including a step of fixing an electrostatic image developing toner on a resin recording medium to form an image, wherein the content of saturated hydrocarbon compounds having from 16 to 35 carbon atoms is 1000 mass ppm or less with respect to the total mass of the electrostatic image developing toner, and the amount of adhesion to the resin recording medium is 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 The present invention is characterized in that:

[0035] Hereinafter, "toner for developing electrostatic images" will also be referred to simply as "toner." "Saturated hydrocarbon compounds having 16 to 35 carbon atoms" will also be referred to simply as "C16-35 saturated compounds." The toner includes toner particles having toner base particles and an external additive disposed on the surface of the toner base particles. "Toner base particles" are particles that constitute the base of "toner particles." The "toner base particles" according to the present invention contain at least a binder resin, and may contain other components such as a colorant, a release agent (wax), and a charge control agent, as necessary. "Toner base particles" become "toner particles" when external additives are added. "Toner" refers to an aggregate of toner particles. The term "toner image" refers to a state in which toner is collected in an image form.

[0036] <Resin recording medium> The resin recording medium used in the present invention is transparent and flexible, and is made of a resin such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), or polyolefin (PO). The resin recording medium may be a single layer or a multi-layered resin recording medium in which two or more layers are united via an adhesive layer. The surface of the resin recording medium may not be subjected to corona treatment, plasma treatment, or the like, but is preferably subjected to corona treatment, plasma treatment, or the like from the viewpoint of adhesiveness.

[0037] The resin recording medium is preferably a continuous medium, since it can be applied to roll-to-roll printing processing technology and can improve production efficiency. Examples of continuous media include continuous forms and roll paper. The thickness of the resin recording medium is preferably 75 μm or less, since this covers all general-purpose recording media and allows for the production of images without poor fixing.The thickness of the resin recording medium is more preferably within the range of 50 to 75 μm. In particular, in the present invention, it is preferable that the resin recording medium is a polyethylene terephthalate film having a thickness of 50 μm in terms of fixability and adhesiveness.

[0038] <Mountain peak density Spd> In the present invention, the reason why the peak density Spd is defined as the surface roughness of the image surface is as follows. Surface roughness can be broadly divided into two categories: "line roughness" and "area roughness." While the line roughness (contour curve) method provides two-dimensional information, the area roughness (three-dimensional) method provides three-dimensional information, which is overwhelmingly richer in information. The measuring instrument, filter processing to be used, measurement conditions, etc. must be determined according to the roughness information you wish to obtain. It is known that the surface of a printed image is made up of numerous irregularities. In order to control the state of these irregularities, we thought it would be better to use "area roughness" which is made up of three-dimensional information with a richer amount of information than "line roughness measurement", which is prone to variations in results depending on the measurement location and the scanning direction. There are several main parameters for "surface roughness." Specifically, surface roughness can be categorized into height parameters, spatial parameters, composite parameters, parameters related to function, and shape parameters. When actual images are observed in three dimensions using an optical microscope or scanning electron microscope, the size and distribution of irregularities can be visually determined. The blocking property, which is our main concern here, is affected by the number of contact points between the convex parts of the image and the back surface of the recording medium, while the varnish applicability is affected by the number of convex parts of the image, which changes the wetting and spreading properties of the varnish. Therefore, in terms of blocking property and varnish applicability, we found that the number of convex parts that form the image surface is an appropriate roughness parameter to express the state of contact when something else comes into contact with the image surface. The number of convexities is expressed as the "peak density Spd," which refers to the number of peaks per unit area.

[0039] In the image forming method of the present invention, the resin recording medium is coated with a coating amount of 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 In particular, when a polyethylene terephthalate film having a thickness of 50 μm is used as the resin recording medium, the adhesion amount is 4 g / m 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 It is preferable that this is equal to or greater than this. The peak density Spd is 10,000 to 100,000 mm -2This range is preferable in that blocking resistance and varnish coatability are easily achieved at the same time. The peak density (Spd) represents the number of peaks per unit area. Only peaks with a height greater than 5% of the maximum amplitude of the contour curve of the image are counted. It is calculated by dividing the number of peaks by the projected area of ​​the contour curve. Spd can be measured using a non-contact surface roughness measuring device.

[0040] (Measurement method) A resin recording medium with an image formed on it was placed on the stage of a laser microscope (VKX-250, Keyence Corporation) with the toner layer facing up. The toner layer surface was focused on using a 10x lens (1425 μm × 1069 μm), and the original surface was subjected to surface filtering to determine the base surface and measurement surface. The base surface is the surface that serves as a reference for the measurement surface (reference surface). An evaluation area (total area 1425 μm x 1425 μm) is specified for the measurement surface, and surface shape correction (waviness removal) is performed on the reference surface corresponding to the measurement surface. The filter type is set to Gaussian, with S filter, F operation, no L filter, and edge hardening correction turned on, and the peak density Spd is measured. Spd is measured 10 times while randomly changing the observation location, and the average value is calculated. Note that Spd measured using the laser microscope counts peaks that are greater than 5% of the maximum amplitude (maximum peak height) of the contour curved surface. Therefore, when measuring using a device other than the laser microscope, the threshold is cut off to the lower limit of less than 5%.

[0041] As means for setting the density Spd of peaks on the image surface within the above range, for example, the following means (i) and (ii) can be mentioned.

[0042] (i) The polyhydric alcohol component of the amorphous polyester contained in the toner base particles is a linear or alicyclic polyhydric alcohol component. In other words, it is preferable that the polyhydric alcohol component does not contain a structural unit derived from bisphenol A or a bisphenol A derivative. By using a linear or alicyclic polyhydric alcohol component in the amorphous polyester, the amorphous polyester has a flexible skeleton. This increases the resin's meltability (lower viscosity). This makes the molten resin more susceptible to tension after separation from the belt during image formation, presumably resulting in many tension marks (mountains) left on the image. As a result, the peak density Spd of the resulting image can be controlled to be high.

[0043] (ii) In the above (i), an amorphous polyester made of a linear or alicyclic polyhydric alcohol is used as the polyhydric alcohol component, and a highly elastic component is added to the toner base particles. Examples of the highly elastic component include an amorphous resin (high molecular weight material) having a weight average molecular weight in the range of 50,000 to 500,000. By including an amorphous resin with a weight-average molecular weight of 50,000 to 500,000 in the toner base particles, the peak density SPd of the image surface can be controlled to a low level. That is, an amorphous resin with a weight-average molecular weight of 50,000 to 500,000 is a highly elastic component, which causes the resin to recover elasticity after separation from the belt during image formation. As a result, the number of traces (peaks) formed on the image due to separation can be reduced, and the peak density Spd can be controlled to a low level.

[0044] <Saturated hydrocarbon compounds with 16 to 35 carbon atoms (C16-35 saturated compounds)> The toner used in the present invention has a content of saturated hydrocarbon compounds having 16 to 35 carbon atoms of 1000 mass ppm or less relative to the total mass of the toner. The content of C16-C35 or less compounds may be 0 mass ppm relative to the total mass of the toner. The content of C16-C35 or less compounds is preferably 1 mass ppm or more relative to the total mass of the toner. The reason why the present invention focuses on C16-35 compounds is as follows. As mentioned above, when applying varnish to an image with a high peak density Spd, the image surface has many peaks, i.e., a fractal structure with many irregularities. This makes it easier for the varnish droplets to be repelled, preventing them from spreading over the image surface, which leads to a problem of poor varnish application.

[0045] On the other hand, C16-35 saturated compounds do not have a very high affinity with varnish. Also, due to their short chain length, C16-35 saturated compounds tend to bleed onto the image surface during heat fixing, covering it and repelling varnish. Therefore, if the toner contains an excessive amount of C16-35 saturated compounds and the image surface becomes densely coated with C16-35 saturated compounds, it is thought that the adhesion of the varnish will decrease. Therefore, from the viewpoint of suppressing varnish repellency, the content of C16-35 saturated compounds is set to 1000 ppm by mass or less relative to the total mass of the toner. In view of the heat-resistant storage stability of the toner, the content of C16-35 saturated compounds is preferably 1 ppm by mass or more relative to the total mass of the toner, and is in the range of 10 to 950 ppm by mass. The "total mass of the toner" refers to the mass including the toner base particles and external additives. Furthermore, if the carbon number is 15 or less, the compound will have a low molecular weight and low viscosity, making it more likely to sublimate. If the carbon number is 36 or more, the compound will be a long-chain hydrocarbon saturated compound, making it more difficult to orient to the image surface. Therefore, the content of the 16-35 saturated compound is specified as above. In addition, since the C16-35 saturated compound has a wax-like structure, it also has the effect of increasing the releasability of the toner from fixing members and the like to a certain extent.

[0046] 2. Toner The composition of the toner will be described below. The toner contains toner base particles and an external additive, and the content of C16-35 saturated compounds is 10,000 ppm by mass or less relative to the total mass of the toner. The toner base particles may contain other components such as a binder resin, a release agent, a colorant, and a charge control agent, as required.

[0047] [Toner base particles] <Binder resin> The toner base particles according to the present invention preferably contain a binder resin, which allows the toner to be fixed onto a resin recording medium. The binder resin according to the present invention preferably contains at least an amorphous polyester and a crystalline polyester. Furthermore, the binder resin according to the present invention preferably contains, in addition to the amorphous polyester and the crystalline polyester, an amorphous resin having a weight-average molecular weight in the range of 50,000 to 500,000. If necessary, the binder resin may contain an amorphous resin and a crystalline resin other than the amorphous polyester and the crystalline polyester.

[0048] (Method for analyzing resin composition) The composition of each resin contained in the toner base particles can be analyzed by, for example, pyrolysis gas chromatography mass spectrometry (GC / MS). Specifically, using a column and detector that have been confirmed to be able to detect monomers with specific structures, quantification can be performed using the standard addition method.

[0049] An example of detailed pyrolysis conditions and GC / MS measurement conditions is shown below. (Pyrolysis conditions) Measurement device: PY-2020iD (Frontier Labs) Measurement mass: 0.1 mg Heating temperature: 550℃ Heating time: 0.5 minutes

[0050] (GC / MS measurement conditions) Measuring device: QP2010 (Shimadzu Corporation) Column: UltraALLOY-5 (inner diameter: 0.25 mm, length: 30 m, thickness: 0.25 μm, manufactured by Frontier Labs) Temperature range: 40℃ to 320℃ (maintain at 320℃) Heating rate: 20°C / min

[0051] (amorphous resin) In the present invention, "exhibiting amorphousness" means that an endothermic curve obtained by differential scanning calorimetry (DSC) has a glass transition temperature (Tg) but does not have a melting point, i.e., a clear endothermic peak during heating. A clear endothermic peak means an endothermic peak with a half-width of 15°C or less in an endothermic curve obtained when the temperature is increased at a heating rate of 10°C / min.

[0052] <Amorphous polyester> From the viewpoint of low-temperature fixability, the toner base particles according to the present invention preferably contain an amorphous polyester. "Amorphous polyester" refers to a polyester that exhibits amorphous properties and is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) monomer and a divalent or higher alcohol (polyalcohol) monomer. Amorphous polyester can be synthesized by polycondensing (esterifying) the polycarboxylic acid monomer and the polyalcohol monomer using a known esterification catalyst.

[0053] A polycarboxylic acid is a compound containing two or more carboxy groups in one molecule. Examples of polycarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, naphthalene-2,6-dicarboxylic acid, malonic acid, mesaconic acid, dimethyl isophthalate, fumaric acid, dodecenylsuccinic acid, 1,10-dodecanedicarboxylic acid, etc. Among these, dimethyl isophthalate, terephthalic acid, dodecenylsuccinic acid, and trimellitic acid are preferred. These may be contained alone or in combination of two or more.

[0054] A polyhydric alcohol is a compound that contains two or more hydroxy groups in one molecule. Examples of polyhydric alcohols include dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, pentanediol, neopentyl glycol, hexanediol, heptanediol, cyclohexanediol, octanediol, decanediol, and dodecanediol; trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine; and ester compounds thereof; and hydroxycarboxylic acid derivatives. These may be contained alone or in combination of two or more.

[0055] In addition, because bisphenols can be esterified like alcohols, in the present invention, the "polyhydric alcohol" includes bisphenol A or a derivative of bisphenol A. Examples of the derivative of bisphenol A include an ethylene oxide adduct of bisphenol A (BPA-EO) and a propylene oxide adduct of bisphenol A (BPA-PO).

[0056] Among these, the polyhydric alcohol is preferably an aliphatic polyhydric alcohol or an alicyclic polyhydric alcohol. In particular, the polyhydric alcohol is preferably an acyclic aliphatic polyhydric alcohol having 5 or more carbon atoms, and most preferably an aliphatic polyhydric alcohol having 5 to 7 carbon atoms. Aliphatic polyhydric alcohols with 5 to 7 carbon atoms have a relatively small bulk, making it easy to make the bond distances between ester bonds uniform in the polyester obtained by synthesis. Furthermore, areas with high localized ester group density are unlikely to form. Specifically, the hydrophilic moieties derived from ester bonds and the hydrophobic moieties derived from hydrocarbon groups are appropriately dispersed, which is thought to suppress charge leakage.

[0057] In particular, aliphatic polyhydric alcohols having 5 to 7 carbon atoms are smaller in bulk than bisphenol A or bisphenol A derivatives, and therefore it is believed that aliphatic polyhydric alcohols having 5 to 7 carbon atoms can suppress charge leakage more effectively than bisphenol A or bisphenol A derivatives.

[0058] Examples of the aliphatic polyhydric alcohol having 5 to 7 carbon atoms include pentanediol, neopentyl glycol, hexanediol, heptanediol, and cyclohexanediol.

[0059] From the viewpoint of suppressing charge leakage, the proportion of bisphenol A or a bisphenol A derivative in the polyhydric alcohol is preferably low. In the present invention, the content of structural units derived from bisphenol A or bisphenol A derivatives relative to the total number of moles of structural units derived from polyhydric alcohols is 10 mol % or less, which is believed to suppress charge leakage and reduce uneven density in the formed image.

[0060] The content of structural units derived from bisphenol A or bisphenol A derivatives relative to the total number of moles of structural units derived from polyhydric alcohols is preferably as low as possible, specifically, preferably 5 mol % or less, and more preferably 1 mol % or less. The structural units derived from polyhydric alcohol may not contain any structural units derived from bisphenol A or bisphenol A derivatives.

[0061] Examples of the esterification catalyst include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous compounds; phosphoric acid compounds; and amine compounds.

[0062] The polymerization temperature is not particularly limited, and is preferably within the range of, for example, 150 to 250° C. The polymerization time is also not particularly limited, and is preferably within the range of, for example, 0.5 to 10 hours. During the polymerization, the reaction system may be reduced in pressure, if necessary.

[0063] The content of the amorphous polyester is preferably in the range of 5 to 80% by mass, more preferably in the range of 10 to 50% by mass, based on the total mass of the binder resin. The content of the amorphous polyester is preferably 10% by mass or more, and more preferably 40% by mass or more, based on the total mass of the toner base particles.

[0064] <Hybrid amorphous polyester> The amorphous polyester may be a hybrid crystalline polyester in which an amorphous polyester polymer segment and an amorphous polymer segment other than the amorphous polyester are chemically bonded.

[0065] <Amorphous resin with a weight-average molecular weight in the range of 50,000 to 500,000> The binder resin preferably contains an amorphous resin in addition to at least an amorphous polyester and a crystalline polyester. The amorphous resin may be an amorphous resin having a weight-average molecular weight (Mw) of 10,000 to 40,000, or an amorphous resin (high molecular weight substance) having a weight-average molecular weight in the range of 50,000 to 500,000. In the present invention, it is preferable that the binder resin contains both the amorphous resin having a weight-average molecular weight of 10,000 to 40,000 and the high molecular weight amorphous resin. The content of the amorphous resin having a weight-average molecular weight of 10,000 to 40,000 is preferably within a range of 1 to 90% by mass with respect to the total mass of the binder resin. The content of the high molecular weight amorphous resin is preferably in the range of 0 to 1% by mass based on the total amount of the binder resin. The weight average molecular weight of the amorphous resin having a weight average molecular weight of 10,000 to 40,000 and the high molecular weight amorphous resin can be measured in the same manner as the weight average molecular weight of the crystalline resin described below. The amorphous resin having a weight average molecular weight of 10,000 to 40,000 and the amorphous resin having a high molecular weight are preferably, for example, vinyl resin, urethane resin, urea resin, etc. In the present invention, the amorphous resin having a weight average molecular weight of 10,000 to 40,000 is preferably, for example, vinyl resin, urethane resin, urea resin, etc. of As the amorphous resin and the high molecular weight amorphous resin, a vinyl resin is particularly preferred.

[0066] The vinyl resin is a resin obtained by polymerization using at least a vinyl monomer. Specific examples of amorphous vinyl resins include acrylic resins and styrene-acrylic resins, etc. Among these, styrene-acrylic resins formed using styrene-based monomers and (meth)acrylic acid ester-based monomers are preferred as amorphous vinyl resins. Specific examples of styrene monomers and (meth)acrylic acid ester monomers that can be used to form styrene-acrylic resins are shown below, but the styrene-acrylic resins that can be used in the present invention are not limited to those shown below.

[0067] <Styrene-based monomers> Examples of styrene-based monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, and derivatives thereof. These styrene-based monomers can be used alone or in combination of two or more.

[0068] (Meth)acrylic acid ester monomer Examples of the (meth)acrylic acid ester monomer include acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, and phenyl acrylate; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

[0069] The content of the styrene-acrylic resin is preferably 70% by mass or more of the total amount of the binder resin, which is sufficient to achieve the effect of improving the chargeability.

[0070] In addition to the above, a third polymerizable monomer can also be used as the polymerizable monomer. Examples of the third polymerizable monomer include acid monomers such as acrylic acid, methacrylic acid, maleic anhydride, and vinylacetic acid. Examples of the third polymerizable monomer include acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone, and butadiene. The third polymerizable monomer may further be a polyfunctional vinyl monomer, such as diacrylates of ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, etc., and dimethacrylates and trimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane.

[0071] Glass transition temperature From the viewpoint of achieving both sufficient low-temperature fixability and heat-resistant storage stability, the glass transition temperature (Tg) of the amorphous resin is preferably within a range of 30 to 70°C, and more preferably within a range of 40 to 65°C.

[0072] For example, differential scanning calorimetry (DSC) was performed using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi) and a thermal analyzer controller (AS3 / DX, manufactured by Hitachi). Specifically, 5 mg of sample was placed in a sample container for the AL autosampler (φ6.8 mm, H2.5 mm, manufactured by Hitachi) and a cover for the AL autosampler (manufactured by Hitachi). This was then placed in the sample holder of the AS3 / DX, and the temperature was cycled in the following order: heating, cooling, and heating again. During the first and second heating cycles, the temperature was increased from 0°C to 150°C at a rate of 10°C / min and held at 150°C for 1 minute. During cooling, the temperature was decreased from 150°C to 0°C at a rate of 10°C / min and held at 0°C for 1 minute. A baseline shift was observed in the measurement curve obtained during the second heating cycle. The intersection of the extension of the baseline before the shift and the tangent line showing the maximum slope of the shifted portion of the baseline is taken as the glass transition temperature (Tg). An empty aluminum pan is used as a reference.

[0073] (crystalline resin) The toner base particles according to the present invention preferably contain a crystalline resin, which allows the crystalline portion to melt when the temperature exceeds the melting point, thereby compatibilizing the crystalline resin and the amorphous resin, thereby improving low-temperature fixability.

[0074] In the present invention, "exhibiting crystallinity" means that an endothermic curve obtained by DSC (differential scanning calorimetry) has a clear endothermic peak rather than a stepwise endothermic change at the melting point, i.e., during heating. A clear endothermic peak is 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.

[0075] As the crystalline resin, it is preferable to use a known crystalline resin, such as a crystalline polyester or a crystalline polyurethane. In particular, from the viewpoint of sharp melting during melting and compatibility with the binder resin, a crystalline polyester is preferable. That is, it is preferable that the portion having a crystalline structure contains a crystalline polyester. The content of the crystalline polyester is preferably in the range of 0.1 to 15% by mass with respect to the total mass of the binder resin.

[0076] <Crystalline polyester> The term "crystalline polyester" refers to a known polyester that exhibits crystallinity and is obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyalcohol).

[0077] The crystalline polyester preferably has structural units derived from an aliphatic diol and structural units derived from an aliphatic carboxylic acid, and more preferably has only structural units derived from an aliphatic diol and structural units derived from an aliphatic carboxylic acid.

[0078] The number of carbon atoms in the aliphatic diol or aliphatic carboxylic acid is more preferably within a range of 6 to 10. By making the crystalline polyester have a relatively non-bulky structure, it is thought that the ester groups can be prevented from becoming locally highly dense, thereby suppressing charge leakage.

[0079] A polycarboxylic acid is a compound containing two or more carboxy groups in one molecule. Examples of polycarboxylic acids include oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecylsuccinic acid, nonanedicarboxylic acid, and decanedicarboxylic acid. Examples of the crystalline polyester include saturated aliphatic dicarboxylic acids such as undecanedicarboxylic acid, dodecanedicarboxylic acid (dodecanedioic acid), and tetradecanedicarboxylic acid (tetradecanedioic acid); alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid; and anhydrides of these carboxylic acid compounds. Other examples include alkyl esters having 1 to 3 carbon atoms. The crystalline polyester may contain one or more of these compounds.

[0080] A polyhydric alcohol is a compound that contains two or more hydroxy groups in one molecule. Examples of polyhydric alcohols include aliphatic diols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, dodecanediol, neopentyl glycol, and 1,4-butenediol; and trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol. The crystalline polyester may contain one or more of these.

[0081] The method for synthesizing the crystalline polyester is not particularly limited, and it can be synthesized by polycondensing (esterifying) the polyhydric alcohol component and the polycarboxylic acid component using a known esterification catalyst.

[0082] The ratio of the polyhydric alcohol component to the polycarboxylic acid component is not particularly limited. For example, the equivalent ratio of the hydroxyl groups of the polyhydric alcohol component to the carboxyl groups of the polycarboxylic acid component is preferably within a range of 1.5 / 1 to 1 / 1.5, and more preferably within a range of 1.2 / 1 to 1 / 1.2.

[0083] Catalysts that can be used in the synthesis of crystalline polyesters include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphorous compounds; phosphoric acid compounds; and amine compounds.

[0084] Specific examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetra-normal-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolaminate.

[0085] Germanium compounds include germanium dioxide. Examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminate. These may be used alone or in combination of two or more. The polymerization temperature and polymerization time are not particularly limited, and the pressure in the reaction system may be reduced during the polymerization, if necessary.

[0086] Melting Point From the viewpoint of low-temperature fixability and hot offset resistance, the melting point (Tm) of the crystalline resin is preferably within a range of 55 to 90° C., and more preferably within a range of 60 to 85° C. The melting point of the crystalline resin can be controlled by the resin composition. When the crystalline resin is a crystalline polyester, the melting point of the crystalline polyester is preferably 75° C. or lower.

[0087] The melting point (Tm) is the temperature at the top of the endothermic peak, and can be measured by DSC (differential scanning calorimetry). For example, differential scanning calorimetry (DSC) was performed using a differential scanning calorimeter (DSC7000X, manufactured by Hitachi) and a thermal analyzer controller (AS3 / DX, manufactured by Hitachi). Specifically, 5 mg of sample was placed in a sample container for the AL autosampler (φ6.8 mm, H2.5 mm, manufactured by Hitachi) and a cover for the AL autosampler (manufactured by Hitachi). This was then placed in the sample holder of the AS3 / DX, and the temperature was cycled in the following order: heating, cooling, and heating again. During the first and second heating cycles, the temperature was increased from 0°C to 150°C at a rate of 10°C / min and held at 150°C for 1 minute. During cooling, the temperature was decreased from 150°C to 0°C at a rate of 10°C / min and held at 0°C for 1 minute. The melting point was determined as the temperature at the top of the endothermic peak in the endothermic curve obtained during the second heating cycle.

[0088] 《Weight average molecular weight》 The weight-average molecular weight of the crystalline resin is not particularly limited, but from the viewpoints of suppressing tacking and low-temperature fixability, it is preferably within a range of 1,000 to 29,000, more preferably within a range of 1,000 to 20,000, and even more preferably within a range of 1,000 to 15,000.

[0089] The weight average molecular weight of the crystalline resin can be measured by the following method. For example, a gel permeation chromatography system "HLC-8320GPC" (manufactured by Tosoh Corporation) is used, which is connected to one column "TSKgel guard column SuperHZ-L" and three columns "TSKgel SuperHZM-M" (all manufactured by Tosoh Corporation).

[0090] The column (TSK-) was stabilized at 40°C, and tetrahydrofuran (THF) was applied as a carrier solvent at a flow rate of 0.35 mL / min. A THF sample solution containing the resin sample, adjusted to a sample concentration of 1 mg / mL, was processed for 10 minutes at room temperature using a roll mill. The solution was filtered through a membrane filter with a pore size of 0.2 μm to obtain a sample solution. 10 μL of this sample solution was injected into the instrument along with the carrier solvent and detected using a refractive index detector (RI detector).

[0091] A calibration curve is created using a polystyrene standard sample with a monodisperse molecular weight distribution. The molecular weight distribution of the measurement sample is calculated based on this calibration curve. The calibration curve is created using "polystylene standard sample TSK standard" manufactured by Tosoh Corporation: "A-500" and "F-1 The data are collected at 300 ms intervals during sample analysis.

[0092] Alternatively, as described below, the crystalline resin and the release agent in the toner may be separated, and then the weight average molecular weight of the crystalline resin may be calculated by the above-mentioned measurement method.

[0093] <Separation of crystalline resin> An example in which the crystalline resin is a crystalline polyester will be described. First, the toner is dispersed in ethanol, which is a poor solvent for the toner, and the resulting dispersion is heated to a temperature exceeding the melting points of the crystalline polyester and the release agent. Pressure may be applied if necessary. At this point, the crystalline polyester and the release agent, which have exceeded their melting points, are melted in the ethanol. Then, a mixture of the crystalline polyester and the release agent can be extracted from the toner by solid-liquid separation. The mixture can be separated by molecular weight to separate the crystalline polyester and the release agent from the toner.

[0094] <Acid value of crystalline resin> From the viewpoint of low temperature fixability and fold fixability, the acid value of the crystalline resin is preferably within a range of 9 to 30 mgKOH / g, and more preferably within a range of 15 to 23 mgKOH / g.

[0095] The acid value of a crystalline polyester is expressed as the number of milligrams of potassium hydroxide required to neutralize the carboxyl groups present in 1 g of the resin (mgKOH / g). Specifically, it is determined by the following method in accordance with JIS K0070-1992.

[0096] (1) Preparation of reagents (a) Phenolphthalein solution 1.0 g of phenolphthalein is dissolved in 90 mL of ethyl alcohol (95% by volume), and ion-exchanged water is added to make the total volume 100 mL to obtain a phenolphthalein solution.

[0097] (b) Potassium hydroxide solution Dissolve 7 g of special-grade potassium hydroxide in 5 mL of ion-exchanged water and add ethyl alcohol (95% by volume) to make 1 L. Place this solution in an alkali-resistant container to avoid contact with carbon dioxide, etc., and leave it for 3 days. Then filter to obtain potassium hydroxide solution. Store the resulting potassium hydroxide solution in an alkali-resistant container.

[0098] (c) Factor of potassium hydroxide solution Place 25 mL of 0.1 mol / L hydrochloric acid in an Erlenmeyer flask and add a few drops of the phenolphthalein solution. Then, titrate this with potassium hydroxide solution. Calculate the potassium hydroxide factor from the amount of potassium hydroxide solution required for neutralization.

[0099] (d) Hydrochloric acid solution 0.1 mol / L hydrochloric acid prepared in accordance with JIS K8001-1998 is used.

[0100] (2) Operation (a) Main test Accurately weigh 2.0 g of toner into a 200 mL Erlenmeyer flask, add 100 mL of a toluene:ethanol (2:1) mixed solution to the Erlenmeyer flask, and dissolve for 5 hours. Next, add a few drops of phenolphthalein solution to the Erlenmeyer flask as an indicator, and titrate with potassium hydroxide solution. The titration endpoint is when the indicator's light red color lasts for approximately 30 seconds.

[0101] (b) Blank test The titration is carried out in the same manner as in the main test above, except that no sample is used, i.e., only a mixture of toluene:ethanol (2:1) is used.

[0102] (3) Substitute the obtained results into the following formula to calculate the acid value. A=[(CD)×f×5.611] / S Here, the symbols and numbers are as follows: A: Acid value (mgKOH / g) C: Amount of potassium hydroxide solution added in this test (mL) D: Amount of potassium hydroxide solution added for blank test (mL) f: Factor of 0.1 mol / L potassium hydroxide ethanol solution 5.611: Molar mass of potassium hydroxide 56.11 (g / mol) × (1 / 10) S: mass of sample (g)

[0103] <Release agent> The release agent is not particularly limited, and various known release agents can be used. The release agent is preferably a wax. Examples of wax release agents include hydrocarbon waxes such as polyethylene wax, paraffin wax, microcrystalline wax, and Fischer-Tropsch 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, trimellitate tristearyl, and distearyl maleate; and amide waxes such as ethylenediamine dibehenylamide and trimellitate tristearylamide. Of these, hydrocarbon waxes are preferred because they have a similar molecular structure to C16-35 saturated compounds and are easy to dissolve in the release agent. When C16-35 saturated compounds are well dissolved, they tend to disperse more finely and uniformly in the toner base particles, and they also tend to precipitate from the toner base particles together with the wax during fixing, which tends to improve the coatability of the varnish. As the hydrocarbon wax, for example, microcrystalline wax is preferable.

[0104] The release agent, which is a wax, may be a C16-35 saturated compound, or a different hydrocarbon wax having from 36 to 76 carbon atoms. Since the amount of the C16-35 saturated compound in the toner base particles is extremely small, in order to achieve both the effect of the C16-35 saturated compound in improving the varnish coatability and the effect of the release agent in improving the releasability, it is preferable that the toner base particles contain a C16-35 saturated compound and another release agent, and it is preferable that the toner base particles contain both a C16-35 saturated compound and a hydrocarbon wax having from 36 to 76 carbon atoms.

[0105] The hydrocarbon wax preferably has a melting point of 50 to 95°C. When the melting point of the hydrocarbon wax is 50°C or higher, the hydrocarbon wax exuded from the toner particles is likely to crystallize, and the release effect and the abrasion resistance of the formed image are likely to increase. When the melting point of the hydrocarbon wax is 95°C or lower, the hydrocarbon wax is likely to exude from the toner base particles during fixing, and the release effect and the abrasion resistance of the formed image are likely to increase. Further, when the melting point of the hydrocarbon wax is 95°C or lower, the toner base particles are likely to melt during fixing, and the low-temperature fixing property of the toner is likely to be enhanced. From the above viewpoints, the melting point of the hydrocarbon wax (particularly a hydrocarbon wax having 36 to 76 carbon atoms) is more preferably 80 to 90°C.

[0106] The content of the release agent is preferably 3 to 20% by mass, more preferably 5 to 15% by mass, based on the total mass of the toner base particles. When the content of the release agent is 3% by mass or more, the release property of the toner from the fixing member is sufficiently enhanced. When the content of the release agent is 20% by mass or less, a sufficient amount of the binder resin can be contained in the toner base particles, so that the fixing property of the image is sufficiently enhanced.

[0107] <C16-35 saturated compound> The C16-35 saturated compound enhances the coating property of the varnish by the above-described action. The content of the C16-35 saturated compound is 1000 ppm by mass or less based on the total mass of the toner. The content of the C16-35 saturated compound may be 0 ppm by mass, but the lower limit of the content is preferably 1 ppm by mass. Further, the content of the C16-35 saturated compound is preferably 50 to 950 ppm by mass, more preferably 100 to 900 ppm by mass. By setting the content of the C16-35 saturated compound to 1000 ppm by mass or less, the coating property and the adhesion of the varnish can be made compatible. The total mass of the toner means the sum of the mass of the toner base particles and the mass of the external additive.

[0108] The content of the C16-35 saturated compound is quantified as follows. First, the C16-35 saturated compounds are separated from the toner using a solvent that dissolves them, and then the hydrocarbons with these carbon numbers are qualitatively analyzed by gas chromatography-mass spectrometry (GC-MC).Then, the amount of these hydrocarbons is quantified using a flame ionization detector (GC-FID) as the detector for gas chromatography. It should be noted that the extract extracted from the toner may also contain unsaturated hydrocarbons, so after extraction, polar groups may be added to the unsaturated bonds, and only saturated hydrocarbons may be separated by column separation utilizing the difference in polarity.

[0109] In this case, multiple internal standards may be added (dissolved) in the solvent to determine whether the quantification and pretreatment were performed properly. The concentrations of the internal standards to be added may be determined according to the amount of C16-35 saturated compounds (estimated amount obtained by provisional measurement, etc.).

[0110] The internal standard is preferably a saturated hydrocarbon compound not normally found in toner. For example, using n-undecane or n-tridecane can detect the loss of saturated hydrocarbon compounds due to volatilization during pretreatment, and can serve as a guide for the elution time of the target saturated hydrocarbon compound during solid-phase extraction or GC-FID analysis. Furthermore, bicyclohexyl is less likely to overlap with the elution time of C16-35 saturated compounds, making it easier to improve detection accuracy.

[0111] Extraction from the toner can be performed by a conventionally known method such as a solid-liquid extraction method, a method in which the toner is dissolved or swelled and then separated by centrifugation, a Soxhlet extraction method, a high-speed solvent extraction method, etc. A method can be selected from these methods depending on the expected carbon number of the C16-35 saturated compound and the type of compound that will become a contaminant component such as a binder resin.

[0112] The solvent used for extraction is not particularly limited, but n-hexane, which has high solubility for C16-35 saturated 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.

[0113] The method for introducing polar groups into unsaturated hydrocarbons contained in the extract is not particularly limited. Examples of the introduction method include epoxidation using 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 due to 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 the addition of polar groups may be omitted if sufficient detection accuracy can be ensured depending on the type of saturated hydrocarbon or unsaturated hydrocarbon.

[0114] 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.

[0115] The solvent used for solid-phase extraction is preferably n-hexane for both conditioning and extraction of saturated hydrocarbons. Depending on the type of contaminants expected, a polar solvent may also be used. After collecting the fraction containing the C16-35 saturated compounds, it is preferable to increase the polarity of the solvent and collect the fraction, and then perform qualitative analysis using GC / MS or other methods to confirm that the fraction does not contain saturated hydrocarbon components.

[0116] As the solid phase for solid-phase extraction, a highly polar solid phase used in normal-phase separation using polar interactions can be used. Examples of the solid phase include silica gel, silica gel activated with polar substances such as anhydrous sodium sulfate and silver nitrate, diol, cyanopropyl, magnesium silicate, etc. Among these, activated silica activated with silver nitrate is preferred. Note that alumina is preferably not used because it specifically retains long-chain n-alkanes.

[0117] The fraction containing saturated hydrocarbons extracted by solid-phase extraction is preferably concentrated or diluted to a concentration appropriate for qualitative and quantitative analysis by gas chromatography by a method such as vacuum concentration using an evaporator or concentration using a nitrogen stream, etc. The concentration conditions should be such that the internal standard does not disappear due to the concentration of low-boiling point components. The fractions after solid phase extraction can be subjected to GC-FID under the following conditions, for example, to quantify the C16-35 saturated compounds.

[0118] (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

[0119] 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.

[0120] 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 baseline be created at the lowest point before and after the peak derived from the saturated hydrocarbon compound. However, if a horizontal baseline cannot be created even after subtracting the blank chromatogram due to column bleeding or other reasons, the baseline can be set by a horizontal line from the elution time of the C10 compound to the elution time of the C50 compound, whichever has the lower signal intensity.

[0121] 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 C16-35 saturated compound can be calculated from this area. When an internal standard is used, the mass of the C16-35 saturated compound can be calculated from the ratio of the above area to the area of ​​the compound added as the internal standard. The amount of the C16-35 saturated compound in the toner can then be calculated by dividing the obtained mass of the C16-35 saturated compound by the mass of the toner.

[0122] <Coloring agent> The colorant is not particularly limited, and various known dyes and pigments can be used. Examples of colorants for obtaining black toner include carbon black such as furnace black and channel black; magnetic materials such as magnetite and ferrite; dyes; and inorganic pigments including non-magnetic iron oxide.

[0123] Colorants for obtaining color toners include known dyes and organic pigments. Examples of organic pigments include CI Pigment Red 5, 48:1, 53:1, 57:1, 81:4, 122, 139, 144, 149, 166, 177, 178, 222, 238, 269, CI Pigment Yellow 14, 17, 74, 93, 94, 138, 155, 180, 185, CI Pigment Orange 31, 43, CI Pigment Blue 15:3, 60, 76, and the like.

[0124] Examples of dyes include CI Solvent Red 1, 49, 52, 58, 68, 11, and 122; CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162; and CI Solvent Blue 25, 36, 69, 70, 93, and 95.

[0125] The colorant for obtaining the toner of each color may be contained either alone or in combination of two or more. The content of the colorant should be within the range of 1 to 10% by mass relative to the total mass of the binder resin. It is preferable that the content is in the range of 2 to 8 mass %.

[0126] <Charge control agent> The charge control agent may be any of various known compounds. The content of the charge control agent is preferably within the range of 0.1 to 5.0% by mass relative to the total mass of the binder resin.

[0127] [External additives] The toner according to the present invention may further contain an external additive added to the toner base particles, which can further improve the fluidity, chargeability, cleaning properties, etc. of the toner.

[0128] Examples of external additives include inorganic oxide fine particles such as silica fine particles, alumina fine particles, and titanium oxide fine particles; inorganic stearic acid compound fine particles such as aluminum stearate fine particles and zinc stearate fine particles; and inorganic titanic acid compound fine particles such as strontium titanate and zinc titanate. These may be used alone or in combination of two or more.

[0129] From the viewpoint of heat-resistant storage property and environmental stability, it is preferable to subject these inorganic fine particles to a hydrophobic treatment using a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil or the like.

[0130] The total amount of external additives added is preferably within a range of 0.05 to 5% by mass, and more preferably within a range of 0.1 to 3% by mass, based on the total mass of the toner.

[0131] 3. Toner properties [Toner particle size] The average particle size of the toner particles is, for example, preferably in the range of 3 to 10 μm, more preferably in the range of 4 to 8 μm, in terms of volume-based median diameter (D50). The average particle size of the toner particles can be controlled by the concentration of the coagulant used during production, the amount of organic solvent added, the fusion time, the composition of the binder resin, and the like. By ensuring that the volume-based median diameter (D50) is within the above range, extremely fine dot images at the 1200 dpi level can be faithfully reproduced.

[0132] The volume-based median diameter (D50) of toner particles is measured and calculated using a measuring device that is a "Multisizer 3" (manufactured by Beckman Coulter) connected to a computer system equipped with data processing software "Software V3.51."

[0133] Specifically, first, a toner sample to be measured is added to a surfactant solution, and the solution is mixed with the surfactant solution, diluted with pure water, and then ultrasonically dispersed to prepare a toner particle dispersion. For the surfactant solution, an anionic surfactant such as sodium polyoxyethylene lauryl ether sulfate is preferably used for the purpose of dispersing the toner particles.

[0134] This toner particle dispersion is pipetted into a beaker containing "ISOTON II" (manufactured by Beckman Coulter) in the sample stand until the concentration displayed on the measuring device reaches 6-8%. By setting this concentration, highly reproducible measurement values ​​can be obtained.

[0135] The measurement device is then set to a particle count of 25,000 and an aperture diameter of 100 μm. The toner particle size measurement range of 2 to 60 μm is divided into 256 parts, and the frequency value of the toner particle size is calculated. The particle size of the largest 50% of the volume cumulative fraction is taken as the volume-based median diameter (D50).

[0136] [Average circularity of toner particles] From the viewpoint of the stability of charging characteristics and low-temperature fixability, the average circularity of the toner particles is preferably within a range of 0.930 to 1.000, and more preferably within a range of 0.950 to 0.995.

[0137] When the average circularity is within the above range, both the transferability and cleaning performance of the toner can be achieved, and the chargeability of the toner is stable, allowing high-quality images to be formed.

[0138] The average circularity of the toner particles can be measured using, for example, a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation).

[0139] Specifically, the toner sample to be measured is added to a surfactant solution, allowed to infuse, diluted with pure water, and then ultrasonically dispersed to prepare a toner particle dispersion. An anionic surfactant, such as sodium polyoxyethylene lauryl ether sulfate, is preferably used as the surfactant solution for the purpose of dispersing the toner particles. Then, using a flow particle image analyzer, for example, the "FPIA-3000" (manufactured by Sysmex Corporation), images are taken at an appropriate concentration with a HPF (high magnification imaging) mode measurement condition and an HPF detection count of 3,000 to 10,000 particles.

[0140] The circularity of each toner particle is calculated according to the following formula: The circularity of each toner particle is then added together and divided by the total number of toner particles to calculate the average circularity. High reproducibility can be achieved if the HPF detection number is within the above range. Formula: Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle's projected image)

[0141] [Toner glass transition temperature] From the viewpoint of achieving both sufficient low-temperature fixability and heat-resistant storage stability, the glass transition temperature (Tg) of the toner is preferably within a range of 15 to 40° C., and more preferably within a range of 20 to 35° C. The glass transition temperature can be measured by the method described above.

[0142] [Core-shell structure] The toner base particles may have a multi-layer structure, such as a core-shell structure comprising a core particle and a shell layer covering the surface of the core particle.

[0143] The shell layer does not need to cover the entire surface of the core particle, and the core particle may be partially exposed. The cross section of the core-shell structure can be confirmed by known observation means, for example, a transmission electron microscope (TEM) or a scanning probe microscope (SPM).

[0144] When the toner base particles have a core-shell structure, the core particles and the shell layer can be differentiated in properties such as glass transition temperature, melting point, and hardness depending on the purpose. For example, core particles containing a binder resin, a colorant, a release agent, etc. and having a relatively low glass transition temperature (Tg) are prepared. Then, a resin with a relatively high glass transition temperature (Tg) is aggregated and fused to the core particles to form a shell layer. The shell layer preferably contains an amorphous resin. This configuration allows for both low-temperature fixability and heat-resistant storage stability. Furthermore, good charge retention performance is obtained.

[0145] 4. Toner manufacturing method The toner can be produced in the same manner as known toners by a pulverization method, an emulsion polymerization aggregation method, an emulsion aggregation method, a suspension polymerization method, a solution suspension method, or the like. Of these, the pulverization method, emulsion polymerization flocculation method, emulsion flocculation method or suspension polymerization method is preferred, and the pulverization method or emulsion polymerization flocculation method is more preferred.

[0146] In the emulsion aggregation method, first, an aqueous dispersion of amorphous polyester fine particles, an aqueous dispersion of crystalline polyester fine particles, an aqueous dispersion of amorphous vinyl resin fine particles, and, if necessary, an aqueous dispersion of a C16-35 saturated compound, a release agent, a colorant, fine particles of a high molecular weight amorphous vinyl resin, etc. are mixed together, and then these fine particles are aggregated to form wet toner base particles. In the present invention, the wet toner base particles are then dried under specific conditions to prepare toner base particles.

[0147] Here, "aqueous dispersion" refers to a dispersion (particles) dispersed in an aqueous medium. Also, an aqueous medium refers to a medium in which the main component, i.e., a component that accounts for 50% by mass or more, is water.

[0148] Components other than water contained in the aqueous medium include water-soluble organic solvents. Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Among these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol are preferred from the viewpoint of not dissolving the resin.

[0149] As an example of a method for producing a toner, a method for producing a toner containing a C16-35 saturated compound will be described below, but the present invention is not limited to this. (1) A step of synthesizing amorphous polyester and preparing a dispersion of amorphous polyester microparticles (2) A step of synthesizing crystalline polyester and preparing a dispersion of crystalline polyester microparticles (3) A step of synthesizing an amorphous vinyl resin having a weight-average molecular weight of 10,000 to 40,000 and preparing a dispersion of the amorphous vinyl resin fine particles. (4) A step of synthesizing a high molecular weight amorphous vinyl resin having a weight average molecular weight of 50,000 to 500,000 and preparing a dispersion of the high molecular weight amorphous vinyl resin fine particles. (5) A step of preparing a dispersion of colorant particles (6) A process of aggregating amorphous polyester particles, crystalline polyester particles, amorphous vinyl resin particles having a weight-average molecular weight of 10,000 to 40,000, high-molecular-weight amorphous vinyl resin particles, C16-35 saturated compound, release agent, and colorant particles to form toner base particles. (7) A process of ripening toner base particles and controlling their shape using thermal energy (8) Step of cooling the dispersion of toner base particles (9) A process of filtering the toner base particles from the aqueous medium, washing the toner base particles to remove surfactants, etc., and obtaining wet toner base particles. (10) Step of removing solvent from wet toner base particles (11) A process of drying the wet toner base particles by airflow in the dryer. (12) Step of adding external additives to the dried toner base particles

[0150] (1) A step of synthesizing amorphous polyester and preparing a dispersion of amorphous polyester microparticles In this step, an amorphous polyester is synthesized by a conventionally known method, and the amorphous polyester is dispersed in the form of fine particles in an aqueous medium to prepare a dispersion of amorphous polyester fine particles.

[0151] Specifically, an amorphous polyester is first dissolved or dispersed in an organic solvent to prepare an oil phase liquid. The oil phase liquid is then dispersed in an aqueous medium by phase inversion emulsification or the like to form oil droplets with a desired particle size. The organic solvent is then removed to prepare an aqueous dispersion of amorphous polyester microparticles.

[0152] The amount of the aqueous medium used is preferably within a range of 50 to 2000% by mass, more preferably within a range of 100 to 1000% by mass, based on the total mass of the oil phase liquid. From the viewpoint of dispersion stability of the oil droplets, a surfactant or the like may be added to the aqueous medium. Examples of the surfactant include various conventionally known anionic surfactants, cationic surfactants, nonionic surfactants, etc.

[0153] From the viewpoint of removal treatment after the formation of oil droplets, the organic solvent used for preparing the oil phase liquid is preferably one having a low boiling point and low solubility in water, such as methyl acetate, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, and xylene. These may be used alone or in combination of two or more.

[0154] The amount of the organic solvent used is preferably within a range of 1 to 300% by mass based on the total mass of the amorphous polyester. The emulsification and dispersion of the oil phase liquid can be carried out by utilizing mechanical energy.

[0155] The average particle size of the amorphous polyester fine particles is preferably in the range of 100 to 400 nm in terms of volume-based median diameter (D50). The volume-based median diameter (D50) can be measured using, for example, a "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

[0156] (2) A step of synthesizing crystalline polyester and preparing a dispersion of crystalline polyester microparticles The aqueous dispersion of crystalline polyester fine particles can be prepared in the same manner as the aqueous dispersion of amorphous polyester fine particles, and it is preferable to adjust the temperature during dispersion as necessary.

[0157] (3) A process of synthesizing an amorphous vinyl resin having a weight-average molecular weight of 10,000 to 40,000 and preparing a dispersion of amorphous vinyl resin fine particles. In this step, an amorphous vinyl resin having a weight-average molecular weight of 10,000 to 40,000 is synthesized by a conventionally known method, and the amorphous vinyl resin is dispersed in the form of fine particles in an aqueous medium to prepare a dispersion of amorphous vinyl resin fine particles.

[0158] (4) A step of synthesizing a high molecular weight amorphous vinyl resin having a weight average molecular weight of 50,000 to 500,000 and preparing a dispersion of high molecular weight amorphous vinyl resin fine particles. In this process, the high molecular weight amorphous vinyl resin is synthesized by a conventionally known method, and the amorphous vinyl resin is dispersed in the form of fine particles in an aqueous medium to prepare a dispersion of high molecular weight amorphous vinyl resin fine particles.

[0159] The toner base particles may contain internal additives such as a release agent, a charge control agent, etc., as needed. Such internal additives may be incorporated into the toner base particles by, for example, dissolving or dispersing them in advance in a monomer solution for synthesizing the amorphous polyester, crystalline polyester, or amorphous vinyl resin. In addition, when a release agent is not dissolved or dispersed in advance in a monomer solution for synthesizing an amorphous polyester, a crystalline polyester, or an amorphous vinyl resin, a dispersion of release agent fine particles may be separately prepared, and the dispersion of release agent fine particles may be added together with other resin particle dispersions to aggregate the particles as described below. Similarly to the release agent, the C16-35 saturated compound may be introduced into the toner base particles by dissolving or dispersing it in advance in a monomer solution for synthesizing the amorphous polyester, crystalline polyester, or amorphous vinyl resin.

[0160] When preparing a dispersion of fine particles of a release agent, the aqueous dispersion of fine particles of the release agent can be prepared by dispersing the release agent in an aqueous medium to which a surfactant has been added at a critical micelle concentration (CMC) or higher. The release agent can be dispersed by utilizing mechanical energy. The dispersing machine is not particularly limited, and examples thereof include ultrasonic dispersing machines, mechanical homogenizers, pressure dispersing machines such as Manton-Gaulin and pressure homogenizers, and media-type dispersing machines such as sand grinders and diamond fine mills.

[0161] The release agent fine particles preferably have a volume-based median diameter (D50) in the dispersed state of 10 to 300 nm, more preferably 100 to 200 nm, and particularly preferably 100 to 150 nm. The volume-based median diameter (D50) of the release agent fine particles can be measured, for example, using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).

[0162] (5) A step of preparing a dispersion of colorant particles The aqueous dispersion of colorant particles can be prepared in the same manner as the aqueous dispersion of release agent particles. The release agent particles are preferably dispersed by heating to a temperature equal to or higher than the melting point, but the colorant particles do not necessarily need to be heated.

[0163] (6) A process of aggregating amorphous polyester particles, crystalline polyester particles, amorphous vinyl resin particles having a weight-average molecular weight of 10,000 to 40,000, high-molecular-weight amorphous vinyl resin particles, C16-35 saturated compound, release agent, and colorant particles to form toner base particles. In this process, a C16-35 saturated compound, a release agent, and a flocculant at a concentration equal to or greater than the critical flocculation concentration are added to the aqueous dispersion in which the above-mentioned fine particles are dispersed, and after they are flocculated to a certain extent, an additional binder resin particle dispersion that does not contain a C16-36 saturated compound is further added.Then, the shape of the toner base particles is controlled by fusing the fine particles together.

[0164] The flocculant is not particularly limited, and is preferably, for example, a metal salt such as an alkali metal salt or an alkaline earth metal salt. Examples of the metal salt include monovalent metal salts such as sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; and trivalent metal salts such as iron and aluminum.

[0165] Specific examples of metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, manganese sulfate, aluminum chloride, aluminum sulfate, polyaluminum chloride, polyaluminum hydroxide, etc. Among these, trivalent metal salts are preferred from the viewpoint of promoting aggregation with smaller amounts. These may be used alone or in combination of two or more.

[0166] (7) A process of ripening toner base particles and controlling their shape using thermal energy This step is carried out as necessary when the toner base particles are aged by thermal energy to control their shape. Specifically, in the aging treatment, the dispersion of the toner base particles is heated and stirred by adjusting the heating temperature, stirring speed, heating time, etc. so that the circularity of the toner base particles reaches a desired value.

[0167] (8) Step of cooling the dispersion of toner base particles In this step, the dispersion of toner base particles is cooled. The cooling rate is preferably within the range of 1 to 20°C / min. The specific cooling method is not particularly limited. Examples include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, a method of cooling by directly adding cold water to the reaction system, and a method of cooling using a heat exchanger.

[0168] (9) A process of filtering the toner base particles from the aqueous medium, washing the toner base particles to remove surfactants, etc., and obtaining wet toner base particles. In this process, the toner base particles are separated from the cooled dispersion liquid of the toner base particles by solid-liquid separation. The resulting toner cake is then washed to remove any adhering substances such as surfactants and aggregating agents, thereby obtaining wet toner base particles. Note that the term "toner cake" used here refers to a cake-like aggregate of toner base particles in a wet state.

[0169] The method for solid-liquid separation is not particularly limited, and examples thereof include centrifugation, vacuum filtration using a Nutsche filter, etc., and filtration using a filter press, etc. In addition, in washing, it is preferable to wash with water until the electrical conductivity of the filtrate becomes 10 μS / cm or less.

[0170] (10) Step of removing solvent from wet toner base particles This step is carried out as necessary when the amount of solvent contained in the wet toner base particles is to be reduced. By performing the solvent removal treatment, the amount of solvent contained in the obtained wet toner base particles can be reduced. In addition, by adjusting the time, rotation conditions, pressure conditions, etc., during the solvent removal treatment, the amount of solvent contained in the obtained wet toner base particles can be adjusted.

[0171] (11) Step of drying the wet toner base particles In this step, the wet toner base particles that have been washed and, in some cases, further treated to remove the solvent are dried in a dryer. Examples of the dryer include a spray dryer, a vacuum freeze dryer, a reduced pressure dryer, etc. In particular, it is preferable to use a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary dryer, an agitator dryer, etc. The moisture content of the dried toner base particles is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the dried toner base particles are aggregated by weak inter-particle attractive forces, the aggregates may be subjected to a crushing treatment. As the crushing treatment device, a mechanical crushing device such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

[0172] The drying temperature is preferably within a range of 10 to 45° C., and particularly preferably within a range of 20 to 40° C. If the drying temperature is higher than 45° C., the crystalline components in the toner will be in a molten state, which is thought to make it difficult to control the structure.

[0173] (12) Step of adding external additives to the dried toner base particles This step is carried out as necessary when an external additive is added to the toner base particles. The toner base particles can be used as they are as toner. Furthermore, from the viewpoints of fluidity, chargeability, cleaning properties, etc., external additives such as so-called fluidizing agents and cleaning aids may be added to the toner base particles. Examples of the mixing device for the external additive include mechanical mixers such as a Henschel mixer and a coffee mill.

[0174] The above steps (1) to (12) are an example of a method for producing toner base particles, and the present invention is not limited thereto. The toner base particles according to the present invention may have a core-shell structure. The toner base particles have a shell layer, which allows both low-temperature fixability and heat resistance to be achieved. When a shell layer is formed, it is preferable to form the shell layer after forming the core particles in step (6). The shell layer is preferably made of an amorphous resin. The method for forming the shell layer is not particularly limited, and any conventionally known method can be used.

[0175] 5. Developer The toner can be used as a magnetic or non-magnetic one-component developer, or may be mixed with a carrier to form a two-component developer.

[0176] When the toner is used as a two-component developer, the carrier may be magnetic particles made of a conventionally known material. Examples of materials for the magnetic particles include metals such as iron, ferrite, and magnetite; alloys of these metals with aluminum; and alloys of metals such as lead. Among these, ferrite particles are preferred.

[0177] The carrier may be a coated carrier in which the surfaces of magnetic particles are coated with a coating agent such as resin, or a dispersion type carrier in which magnetic fine powder is dispersed in a binder resin.

[0178] The volume-based median diameter (D50) of the carrier is preferably within a range of 20 to 100 μm, and more preferably within a range of 25 to 80 μm. The volume-based median diameter (D50) of the carrier can be measured, for example, using a laser diffraction particle size distribution analyzer "HELOS" (manufactured by SYMPATEC) equipped with a wet disperser.

[0179] The mixing device used to mix the toner and carrier is not particularly limited, and examples thereof include a Nauta mixer, a W-cone mixer, and a V-type mixer.

[0180] The toner content in the developer is preferably within a range of 4.0 to 8.0% by mass relative to the total mass of the developer.

[0181] 6. Image forming system and image forming apparatus As described above, the image forming system of the present invention comprises a toner containing toner base particles in which the content of C16-35 saturated compounds is 1000 mass ppm or less relative to the total mass of the toner, and a means for fixing the toner to form an image. As the means for forming the image, it is preferable to use an electrophotographic image forming apparatus as shown below. The toner is then fixed to a resin recording medium in an amount of 4 g / m. 2 When the above image is formed, the peak density Spd on the image surface is 5000 mm -2 That's all.

[0182] The electrophotographic image forming method preferably includes a step of adhering the toner to a recording medium and a step of fixing the adhered toner to the recording medium. The image forming method also preferably includes a step of applying varnish to the surface of the toner image formed by fixing the toner to form a varnish coat, in terms of improving image quality and durability. The image forming method of the present invention is suitable for an image forming apparatus for continuous media that forms an image on continuous media as a resin recording medium, but may also be applied to an image forming apparatus that forms an image on a sheet of paper.

[0183] An example of an electrophotographic image forming apparatus will be described below, but the present invention is not limited to this. FIG. 3 is a diagram showing an example of the overall configuration of an image forming apparatus according to this embodiment. The image forming apparatus 100 shown in FIG. 3 is an apparatus that forms an image on a continuous medium such as roll paper or continuous forms as a recording medium. Image forming apparatus 100 is configured such that, from the upstream side along the transport direction (paper transport direction) of continuous media M, a paper feeder (paper feed section) 1, a main body section 2, and a winding device (winding section) 3 are connected. Note that, although Fig. 3 shows a case in which paper feeder 1 and winding device 3 are configured separately from main body section 2, they may also be configured integrally.

[0184] The paper feeder 1 is a device that feeds continuous media M to the main body 2. Driven by a motor (not shown), the paper feeder 1 transports the continuous media M wound around a support shaft X at a constant speed to the main body 2. The operation of the motor of the paper feeder 1 is controlled by a control unit 10 provided in the main body 2. The paper feeder 1 is also provided with a tension applying mechanism 101 that applies tension to the continuous media M. The tension applying mechanism 101 is configured to include driven rollers 101a and 101b, a dancer roller 101c, a weight 101d, etc. The fed continuous media M is wound around the driven roller 101a, the dancer roller 101c, and the driven roller 101b and passed through the main body 2.

[0185] The main body 2 forms an image on the continuous sheet of media M fed from the paper feeder 1 by an intermediate transfer method using electrophotography. Fig. 4 is a diagram showing the main parts of the control system of the image forming apparatus 100. As shown in Fig. 4, the main body 2 includes a control unit 10, a storage unit 20, an operation display unit 30, an image forming unit 40, a paper conveying unit 50, a fixing unit 60, a communication unit 70, etc.

[0186] The control unit 10 includes a CPU (Central Processing Unit) 10a, a ROM (Read Only Memory) 10b, a RAM (Random Access Memory) 10c, etc. The CPU 10a reads a program corresponding to the processing content from the ROM 10b, loads it into the RAM 10c, and works with the loaded program to centrally control the operations of each part of the main body 2, the paper feeder 1, the winder 3, etc.

[0187] The storage unit 20 is configured by, for example, a non-volatile semiconductor memory (so-called flash memory), a hard disk drive, etc. Input document data, various setting information, image data, etc. are stored in the storage unit 20. Note that these data, etc. may also be stored in the RAM 10c of the control unit 10.

[0188] The operation display unit 30 is configured, for example, by a liquid crystal display (LCD) with a touch panel, and functions as a display unit 31 and an operation unit 32. The display unit 31 displays various operation screens, image states, operation statuses of various functions, etc. in accordance with a display control signal input from the control unit 10. The operation unit 32 includes various operation keys such as a numeric keypad and a start key, and receives various input operations from the user and outputs operation signals to the control unit 10.

[0189] The image forming unit 40 forms (prints) an image by forming toner images of each color, Y (yellow), M (magenta), C (cyan), and K (black), on the photosensitive drums 41Y, 41M, 41C, and 41K based on image data input from an external device (such as a personal computer) via the communication unit 70, and then sequentially transferring the images to the intermediate transfer belt 42 to superimpose the four color toner images, and then performing a second transfer onto the continuous feed media M fed from the paper feed device 1 using the transfer roller 43.

[0190] The paper transport section 50 includes a paper path 52 equipped with a plurality of transport rollers. The paper transport unit 50 transports the continuous sheet of media M transported from the paper feeder 1 to the main body 2 under the control of the control unit 10 to the image forming unit 40, and transports the continuous sheet of media M on which a toner image has been formed in the image forming unit 40 to the fixing unit 60. The continuous sheet of media M on which the toner image has been fixed in the fixing unit 60 is then transported to the winding device 3.

[0191] At least one pair of nip rollers 53 is provided on the paper path 52 upstream of the fixing unit 60 and downstream of the paper feeder 1. At least one pair of nip rollers 54 is provided downstream of the fixing unit 60 and upstream of the winding device 3. The nip rollers 53, 54 can be pressed together and separated by a pressure drive mechanism. By pressing both nip rollers 53, 54 together while tension is being applied to the continuous media M by the tension application mechanism 101 and the tension application mechanism 301, it is possible to maintain the tension applied to the continuous media M between the nip rollers 53, 54 even when the roller rotation is stopped and the tension application by the tension application mechanisms 101, 301 is released.

[0192] The fixing unit 60 fixes the toner image to the continuous medium M by applying heat and pressure to the continuous medium M on which the toner image has been formed in a fixing nip. The fixing unit 60 includes a heating roller 61, a heat source 62 for heating the heating roller 61, an upper pressure roller 63, an endless fixing belt 64 stretched between the heating roller 61 and the upper pressure roller 63, and a lower pressure roller 65. The heating roller 61 to the fixing belt 64 are provided on the fixing surface side of the continuous medium M, and the lower pressure roller 65 is provided opposite the fixing belt 64 across the paper path 52 of the continuous medium M (i.e., on the back side of the continuous medium M). A heat source for heating the lower pressure roller 65 may be provided.

[0193] The lower pressure roller 65 is configured to be movable, and the upper pressure roller 63 and the lower pressure roller 65 can be pressed against and separated from each other by driving a pressure drive mechanism (not shown). The upper pressure roller 63 and the lower pressure roller 65 are pressed against and separated from each other, thereby enabling the fixing belt 64 and the lower pressure roller 65 to be pressed against and separated from each other. The fixing belt 64 and the lower pressure roller 65 are pressed against each other to form a fixing nip that sandwiches and transports the continuous sheet of media M. The continuous sheet of media M is heated and pressurized as it passes through the fixing nip formed by the fixing belt 64, which has been heated by the heat source 62, and the lower pressure roller 65, and the toner image is fixed thereto.

[0194] The communication unit 70 is configured by a communication control card such as a LAN (Local Area Network) card, and transmits and receives various data to and from an external device (such as a personal computer) connected to a communication network such as a LAN or WAN (Wide Area Network).

[0195] The winding device 3 is a device that winds up the continuous web of media M that has been transported from the main body 2. Driven by a motor (not shown), the winding device 3 winds up the continuous web of media M that has been transported from the main body 2 onto the support shaft Y at a constant speed. The winding operation of the winding device 3 is controlled by a control unit 10 provided in the main body 2. The winding device 3 is also provided with a tension applying mechanism 301 that applies tension to the continuous web of media M. The tension applying mechanism 301 is configured with driven rollers 301a and 301b, a dancer roller 301c, a weight 301d, etc. The continuous web of media M transported from the main body 2 is wound around the driven rollers 301a, 301c, and 301b, tension is applied to the continuous web of media M, and the continuous web of media M is transported to the support shaft Y.

[0196] In this embodiment, the tension applying mechanism is provided in the paper feeder 1 and the winder 3, but it may be provided in only one of them. The above-described apparatus configuration and image forming method are exemplary embodiments for carrying out the present invention, and the present invention is not limited to these.

[0197] [Formation of varnish coat] It is preferable to apply a varnish to the image formed by the above-described image forming method to form a varnish coat. When forming the varnish coat, for example, a photocurable varnish containing a photopolymerizable compound is applied to the image formed in the image forming process described above and cured to form a varnish layer. The photocurable varnish may be applied to cover the entire image or only a portion of the image.

[0198] The method for applying the photocurable varnish onto the image is not particularly limited as long as it allows the photocurable varnish to be applied uniformly. Examples of coating devices include liquid film coating devices including varnish coaters, roll coaters, foxo coaters, rod coaters, blades, wire bars, air knives, curtain coaters, slide coaters, doctor knives, screen coaters, gravure coaters (e.g., offset gravure coaters), slot coaters, and extrusion coaters, etc. These can be used in well-known types such as forward and reverse roll coating, offset gravure, curtain coating, lithographic coating, screen coating, and gravure coating.

[0199] Here, the photocurable varnish to be applied onto the image need only contain a photopolymerizable compound (polymerizable monomer for varnish), but typically contains a polymerization initiator (sensitizer) in addition to the photopolymerizable compound.

[0200] The photopolymerizable compound may be a monomer, an oligomer, or a polymer, provided that it contains at least a diol di(meth)acrylate having a linear hydrocarbon structure. When the photocurable varnish contains this diol di(meth)acrylate, the affinity with the crystalline polyester in the toner particles described above is increased, the wettability of the photocurable varnish to the image is improved, and the adhesion between the resulting varnish layer and the image is also improved.

[0201] Here, a diol di(meth)acrylate having a linear hydrocarbon structure is a monomer obtained by dehydration assembly of an aliphatic diol and two (meth)acrylic acids. The hydrocarbon structure of the diol di(meth)acrylate may be partially branched. In this case, the hydrocarbon chain sandwiched between two oxygen atoms derived from the diol is specified as the linear hydrocarbon structure.

[0202] The number of carbon atoms in the linear hydrocarbon structure of the diol di(meth)acrylate is preferably 4 to 12, more preferably 6 to 10, and even more preferably 6 to 9. When the number of carbon atoms in the linear hydrocarbon structure of the diol di(meth)acrylate is within this range, the viscosity of the photocurable varnish falls within an appropriate range, which tends to improve coatability. Furthermore, the affinity with the crystalline polyester in the toner particles also tends to improve.

[0203] Specific examples of diol di(meth)acrylate include hexanediol diacrylate, nonanediol diacrylate, decanediol diacrylate, etc., and among these, hexanediol diacrylate is particularly preferred.

[0204] The amount of diol di(meth)acrylate having a linear hydrocarbon structure is preferably 10 to 80% by mass, more preferably 20 to 65% by mass, based on the total mass of the photopolymerizable compound. When the amount of diol di(meth)acrylate is within this range, good adhesion between the image and the varnish layer is achieved.

[0205] Examples of photopolymerizable compounds other than diol di(meth)acrylates include polymerizable oligomers and polymers such as acrylic resins, vinyl acrylic resins, acrylic esters of polyhydric alcohols, epoxy acrylates, urethane acrylates, polyester acrylates, polyether acrylates, acrylate alkyds, and melamine acrylates, as well as (meth)acrylate monomers such as trimethylolpropane (meth)acrylate and phenoxyethyl (meth)acrylate, and tri(meth)acrylate monomers. The amount and type of photopolymerizable compound other than diol di(meth)acrylate are selected appropriately depending on the curing properties, viscosity, surface tension, etc. of the photocurable varnish.

[0206] Examples of the polymerization initiator (sensitizer) include known anthraquinone-based initiators, benzophenone-based initiators, 2-ethylanthraquinone-based initiators, acylphosphine oxide-based initiators, and alkylphenone-based photopolymerization initiators. The amount of the polymerization initiator is preferably 5 to 25% by mass relative to the total mass of the photocurable varnish. When the amount of the polymerization initiator is within this range, the photocurable varnish has good curability.

[0207] Furthermore, the light-curable varnish may contain a surfactant. Examples of surfactants include anionic surfactants, nonionic surfactants, silicone surfactants, and fluorosurfactants. Examples of anionic surfactants include sulfosuccinates, disulfonates, phosphates, sulfates, sulfonates, and the like. Examples of nonionic surfactants that can be used include polyvinyl alcohol, polyacrylic acid, isopropyl alcohol, acetylenic diol, ethoxylated octylphenol, ethoxylated branched secondary alcohol, perfluorobutane sulfonate, and alkoxylated alcohol. Examples of silicone surfactants include polyether-modified polydimethylsiloxanes and the like. Examples of fluorosurfactants include ethoxylated nonylphenol and the like. When the photocurable varnish contains a surfactant, it improves the adhesion between the image and the varnish layer, and also adjusts the surface tension of the photocurable varnish, thereby improving the wettability of the photocurable varnish.

[0208] The surface tension of the photocurable varnish at 25° C. is preferably 10 to 50 mN / m, more preferably 15 to 45 mN / m, and even more preferably 20 to 40 mN / m. When the surface tension of the photocurable varnish is within this range, the photocurable varnish easily wets and spreads over the image. The surface tension of the photocurable varnish is measured by the plate method using a KYOWA DY300 (manufactured by Kyowa Interface Science Co., Ltd.).

[0209] On the other hand, the viscosity of the photocurable varnish at 25°C, measured after 30 seconds by immersing the vibrator in the liquid using a vibration viscometer, is preferably 100 to 800 mPa·s. The viscosity is more preferably 150 to 700 mPa·s or less, and even more preferably 200 to 600 mPa·s. When the viscosity of the photocurable varnish falls within this range, it is easier to apply using the method described above.

[0210] After the photocurable varnish is applied, light energy is irradiated to cure the photocurable varnish. The type of light energy to be irradiated is appropriately selected depending on the type of the polymerization initiator, etc., but can usually be ultraviolet light, visible light, etc. Examples of light sources for light energy include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, carbon arc lamps, metal halide lamps, fluorescent lamps, tungsten lamps, and LEDs, and the light intensity, irradiation time, etc. are selected as appropriate.

[0211] The varnish coat may be formed by applying a solvent-based varnish and then drying the solvent, in addition to the photocurable varnish described above. [Example]

[0212] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass," respectively.

[0213] <Saturated hydrocarbon compounds [H]> Saturated hydrocarbons with carbon numbers of 20, 26, 30, and 34 (manufactured by GL Sciences Inc.) were separated in a mass ratio of 20:30:30:20. The mixture was then melted and mixed at 80°C, and then cooled and solidified to obtain a saturated hydrocarbon compound [H] with a carbon number of 16 to 35.

[0214] <Preparation of Amorphous Vinyl Resin Particle Dispersion [B1]> Styrene: 432.0 parts by mass n-Butyl acrylate: 225.0 parts by mass Methacrylic acid: 61.2 parts by mass A 5 L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water. Under a nitrogen stream, the liquid temperature was raised to 80°C while stirring at a stirring speed of 230 rpm. After the temperature was raised, a solution of 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water was added, and the liquid was heated again to 80°C, and the monomer mixture was added dropwise over 1 hour. After the dropwise addition, the liquid temperature was raised to 80°C, and polymerization was carried out by stirring for 2 hours, thereby preparing a vinyl resin particle dispersion liquid [b1].

[0215] Styrene: 256.5 parts by mass 2-Ethylhexyl acrylate: 85.5 parts by mass Methacrylic acid: 18.0 parts by mass n-Octyl-3-mercaptopropionate (chain transfer agent): 5.40 parts by mass Release agent [W1] (microcrystalline wax): 135.0 parts by mass Saturated hydrocarbon compounds (H) with 16 to 35 carbon atoms: 3.00 parts by mass A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with 7 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate and 3,000 parts by mass of ion-exchanged water, and heated to 80° C. After heating, 80 parts by mass, calculated as solid content, of the vinyl resin particle dispersion liquid [b1] and a mixed liquid prepared by dissolving the above-mentioned monomer, chain transfer agent, release agent [W1], and saturated hydrocarbon compound [H] at 90° C. were added thereto. Then, a mixing and dispersion process was carried out for 1 hour using a mechanical disperser with a circulation path (CLEARMIX, manufactured by M Technique Co., Ltd.) to prepare a dispersion containing emulsified particles (oil droplets). Next, an initiator aqueous solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 84°C for 1 hour, thereby polymerizing the monomers to prepare a vinyl resin particle dispersion [b2]. To the vinyl resin particle dispersion liquid [b2], 400 parts by mass of ion-exchanged water was added. Then, a solution of 11 parts by mass of potassium persulfate dissolved in 400 parts by mass of ion-exchanged water was added. Furthermore, at a temperature of 82°C, a mixed solution of the following monomers was added dropwise over one hour.

[0216] Styrene: 330.3 parts by mass n-Butyl acrylate: 148.5 parts by mass Methacrylic acid: 49.5 parts by mass n-Octyl-3-mercaptopropionate: 7.2 parts by mass After the dropwise addition was completed, the mixture was heated and stirred for 2 hours to polymerize the monomers, and then cooled to 28° C. to obtain an amorphous vinyl resin particle dispersion liquid [B1]. The amorphous vinyl resin particle dispersion liquid [B1] had a solid content of 30 mass %, and the weight average molecular weight (Mw) of the amorphous vinyl resin particles was 30,500.

[0217] <Preparation of amorphous vinyl resin particle dispersions [B2] to [B10]> Amorphous vinyl resin particle dispersions [B2] to [B10] were obtained, except that the type of release agent and the amount of saturated hydrocarbon compound [H] were changed as shown in the following Table I. The amorphous vinyl resin particles dispersed in these amorphous vinyl resin particle dispersions [B1] to [B10] have a weight-average molecular weight in the range of 10,000 to 40,000. In Table I below, the "parts by mass" of the saturated hydrocarbon compound represents the amount added when preparing the amorphous vinyl resin particle dispersion. Furthermore, in Tables VI to VIII below, the "ppm by mass" of the saturated hydrocarbon compound represents the content relative to the total mass of the toner. The "total mass of the toner" refers to the mass including the toner base particles and external additives.

[0218] [Table 1]

[0219] <Preparation of amorphous vinyl resin particle dispersion [S1] (preparation of high molecular weight substance)> A 5L reaction vessel equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet was prepared. A mixture of 1,100 parts by weight of ion-exchanged water and the following monomers, chain transfer agent, and release agent was dissolved in this reaction vessel at 85°C. The mixture was mixed and dispersed for 10 minutes using a CLEARMIX mechanical disperser (M-Technique Co., Ltd.) with a circulation path to prepare a dispersion containing emulsified particles (oil droplets). This dispersion was then added to the 5L reaction vessel, followed by a polymerization initiator solution consisting of 5.4 parts by weight of potassium persulfate dissolved in 103 parts by weight of ion-exchanged water. The system was heated and stirred at 87°C for 1 hour to polymerize, producing amorphous vinyl resin particle dispersion [S1]. The resulting amorphous vinyl resin particle dispersion liquid [S1] had a solid content of 30 mass % and a weight average molecular weight (Mw) of 310,000. Styrene (St): 256.5 parts by mass 2-Ethylhexyl acrylate (2-EHA): 95.3 parts by mass Methacrylic acid (MAA): 38.2 parts by mass n-Octyl-3-mercaptopropionate (NOM, chain transfer agent): 2.0 parts by mass

[0220] <Preparation of amorphous vinyl resin particle dispersions [S2] to [S4] (preparation of high molecular weight compounds)> Amorphous vinyl resin particle dispersions [S2] to [S4] were synthesized in the same manner as in the preparation of the amorphous vinyl resin particle dispersion [S1], except that the components were changed to those shown in the table below.

[0221] [Table 2]

[0222] <Preparation of amorphous polyester [a2]> The following amorphous polyester monomers other than trimellitic acid were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and the temperature was raised to 235°C. (Polyhydric alcohol) Pentanediol: 66.0 parts by mass Ethylene glycol: 35.0 parts by mass (Polycarboxylic Acid) Terephthalic acid: 100.0 parts by mass Dodecenyl succinic acid: 130.0 parts by mass Trimellitic acid: 15.0 parts by mass Next, the inside of the reaction vessel was purged with dry nitrogen gas, and 0.3 mass % of tin dioctanoate was added based on the total mass of the above monomer components. The above monomers were polycondensed under a nitrogen gas flow for 5 hours, and then reacted under a reduced pressure of 8 kPa for 1 hour.

[0223] Styrene (St): 73.0 parts by mass n-Butyl acrylate (BA): 15.0 parts by mass Acrylic acid (AA): 7.3 parts by mass Di-t-butyl peroxide (polymerization initiator): 7.5 parts by mass After cooling the reaction vessel to 170°C, the mixture of the vinyl resin monomer, bireactive monomer, and polymerization initiator was added dropwise to the dropping funnel over 1 hour. The mixture was then maintained at 170°C for 1 hour to allow addition polymerization, then heated to 200°C and reacted under a reduced pressure of 8 kPa for 1 hour. Trimellitic acid was then added and reacted at 210°C for 1 hour. The volume-based median diameter (D50) of the resulting amorphous polyester [a2] was 150 nm and the weight-average molecular weight was 30,500.

[0224] <Preparation of Amorphous Polyester Resin Particle Dispersion [A2]> The following components were placed in a reaction vessel equipped with a stirrer and dissolved at 75°C. Amorphous polyester [a2]: 100.0 parts by mass Methyl ethyl ketone: 60.0 parts by mass Isopropyl alcohol: 15.0 parts by mass The reaction vessel was then cooled to 70°C, and the following ingredients were added: 10% ammonia aqueous solution: 3.5 parts by weight Ion-exchanged water: 300.0 parts by mass The above components were then added dropwise to the reaction vessel over a period of 3 hours. Next, methyl ethyl ketone and isopropyl alcohol were removed using an evaporator to obtain an amorphous polyester resin particle dispersion liquid [A2]. The solid content of the obtained amorphous polyester resin particle dispersion liquid [A2] was 25% by mass. The volume-based median diameter (D50) of the amorphous polyester [a2] in the amorphous polyester resin particle dispersion liquid [A2] was 140 nm.

[0225] <Preparation of Amorphous Polyester Resin Particle Dispersions (A1, A3 to A7)> Amorphous polyesters [a1] and [a3] to [a7] were obtained in the same manner as in the synthesis example of amorphous polyester [a2], except that the type and parts by mass of the alcohol monomer and the parts by mass of the vinyl monomer were changed as shown in the table below. Next, amorphous polyester resin particle dispersions [A1] and [A3] to [A7] were obtained in the same manner as in the synthesis example of amorphous polyester resin particle dispersion [A2], except that the amorphous polyester [a2] was changed to [a1] and [a3] to [a7].

[0226] [Table 3]

[0227] <Preparation of crystalline polyester [c1]> (hybrid of styrene-acrylic resin and crystalline polyester) The following crystalline polyester monomers were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and the temperature was raised to 235°C. (Polycarboxylic Acid) Tetradodecanedioic acid 400 parts by mass (Polyhydric alcohol) 1,4-butanediol 130 parts by mass Next, the atmosphere in the reaction vessel was replaced with dry nitrogen gas, and 0.3 mass % of tin dioctanoate was added based on the total mass of the monomer components. The monomers were polycondensed under a nitrogen gas flow for 5 hours, and then reacted under a reduced pressure of 8 kPa for 1 hour. Styrene (St) 40 parts by mass n-Butyl acrylate (BA) 16 parts by mass Acrylic acid (AA) 3.5 parts by weight Polymerization initiator (di-t-butyl peroxide) 8 parts by mass After cooling the reactor to 170°C, the mixture of the vinyl resin monomer, bireactive monomer, and polymerization initiator was added dropwise to the dropping funnel over 1 hour, and the mixture was then maintained at 170°C for 1 hour for addition polymerization. The mixture was then heated to 200°C and reacted under a reduced pressure of 8 kPa for 1 hour. The weight-average molecular weight of the resulting crystalline polyester [c1] was 8,500.

[0228] <Preparation of crystalline polyester [c2]> The following crystalline polyester monomers were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and the temperature was raised to 235°C. (Polycarboxylic Acid) Tetradodecanedioic acid 390.0 parts by mass (Polyhydric alcohol) 1,4-butanediol 140.0 parts by mass Next, the atmosphere in the reaction vessel was replaced with dry nitrogen gas, and 0.3% by mass of tin dioctanoate was added based on the total mass of the above monomer components. The above monomers were polycondensed under a nitrogen gas flow for 5 hours, and then reacted under a reduced pressure of 8 kPa for 1 hour. The weight-average molecular weight of the resulting crystalline polyester [c2] was 9,500.

[0229] [Table 4]

[0230] <Preparation of cyan colorant particle dispersion [P1]> Cyan pigment (Dainichi Seikagaku Co., Ltd., Pigment Blue 15:3 (copper phthalocyanine)) 45.0 parts by mass Anionic surfactant "Neogen (registered trademark) R" (Dai-ichi Kogyo Seiyaku Co., Ltd.) 2.0 parts by mass Ion-exchanged water 250.0 parts by mass The above components were mixed and dispersed using a high-pressure impact disperser, Ultimizer HJP30006 (manufactured by Sugino Machine Co., Ltd.), to obtain a cyan colorant dispersion liquid [P1]. The volume-based median diameter (D50) of the resulting colorant particles was 150 nm.

[0231] <Preparation of toner base particles [1]> ≪Agglomeration / fusion process≫ The following materials were placed in a 4-liter reaction vessel equipped with a thermometer, pH meter, and stirrer, and 1.0% nitric acid was added at 25°C to adjust the pH to 3.0. Then, while dispersing at 3000 rpm using a homogenizer (ULTRA-TURRAX T50, manufactured by IKA), 100 parts by mass of a 2% aqueous aluminum sulfate (flocculant) solution was added over 30 minutes. After the dropwise addition was complete, the mixture was stirred for 10 minutes to thoroughly mix the raw materials and flocculant. Amorphous vinyl resin particle dispersion [B1] 932 parts by mass Amorphous vinyl resin particle dispersion [S1] 14 parts by mass Amorphous polyester resin particle dispersion [A1] 61 parts by mass Crystalline polyester resin particle dispersion [C1] 135.2 parts by mass Cyan colorant particle dispersion [P1] 155.0 parts by mass Anionic surfactant (Dowfax2A1 20% aqueous solution) 40 parts by mass Ion-exchanged water 1200 parts by weight A stirrer and mantle heater were then installed in the reaction vessel, and the temperature was increased at a rate of 0.2°C / min up to 40°C, and then at a rate of 0.05°C / min after the temperature exceeded 40°C, while the stirrer rotation speed was adjusted to ensure sufficient stirring of the slurry. Particle size was measured every 10 minutes using a Coulter Multisizer 3. The Coulter Multisizer 3 has an aperture diameter of 100 μm and is manufactured by Beckman Coulter. When the volume average particle size reached 5.8 μm, the temperature was maintained, and the following mixed liquid, which had been mixed in advance, was added over 20 minutes. Amorphous polyester resin particle dispersion (A1) 209 parts by mass Anionic surfactant (Dowfax2A1 20% aqueous solution) 15 parts by mass Next, after maintaining the temperature at 50°C for 30 minutes, 8 parts by mass of a 20% solution of EDTA (ethylenediaminetetraacetic acid) was added to the reaction vessel, and then a 1 mol / L aqueous solution of sodium hydroxide was added to control the pH of the raw material dispersion to 9.0. Thereafter, the temperature was increased to 85°C at a rate of 1°C / min while adjusting the pH to 9.0 every 5°C, and the temperature was maintained at 85°C.

[0232] ≪Cooling process≫ Thereafter, using the "FPIA-3000," the mixture was cooled at a rate of 10°C / min when the shape factor reached 0.965, yielding toner base particle dispersion liquid [1]. The volume-based median diameter (D50) of the particles in toner base particle dispersion liquid [1] was 6.2 μm, and the average circularity was 0.966.

[0233] <Filtration, washing and drying processes> Thereafter, the toner base particle dispersion liquid [1] was filtered, thoroughly washed with ion-exchanged water, and then dried at 40° C. to obtain toner base particles [1].

[0234] <Preparation of toner base particles [2] to

[25] > Toner base particles [2] to

[25] were prepared in the same manner as in the preparation of toner base particles [1], except that the amount (mass%) of each resin particle dispersion was changed as shown in Table V below. In Table V below, the amount (mass %) of each resin particle dispersion represents the amount (mass %) of each resin particle dispersion relative to the total mass of the binder resin (the total mass of the amorphous vinyl resin particle dispersion, the amorphous polyester resin particle dispersion, and the crystalline polyester resin particle dispersion).

[0235] <Preparation of Toner [1]> The following toner base particles and fine particles were mixed in a Henschel mixer (FM-75, manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotation speed of 30 s -1 The mixture was mixed for 10 minutes to obtain toner [1]. Toner base particles [1] 100 parts by mass Hydrophobic silica particles (BET specific surface area: 200 m) hydrophobized with hexamethyldisilazane 2 / g) 1.0 parts by mass Titanium oxide particles (BET specific surface area: 80 m) surface-treated with isobutyltrimethoxysilane 2 / g) 1.0 parts by mass

[0236] <Preparation of Toners [2] to

[25] > Toners [2] to

[25] were obtained in the same manner as in the preparation of toner [1], except that the toner base particles used were changed to toner base particles [2] to

[25] , respectively.

[0237] <Preparation of developer> 100 parts by mass of ferrite particles (volume-based median diameter: 50 μm (manufactured by Powder Tech Co., Ltd.)) and 4 parts by mass of methyl methacrylate-cyclohexyl methacrylate copolymer resin (volume-based median diameter of primary particles: 85 nm) were placed in a high-speed mixer with horizontal mixing blades and mixed for 15 minutes at a mixing blade peripheral speed of 8 m / s and a temperature of 30°C. The mixture was then heated to 120°C and stirred for 4 hours. The mixture was then cooled, and fragments of the methyl methacrylate-cyclohexyl methacrylate copolymer resin were removed using a 200-mesh sieve to produce a resin-coated carrier. This resin-coated carrier was mixed with each of the above toners so that the toner concentration was 7% by mass relative to the total mass of the toner and carrier, to prepare two-component developers [2] to

[25] , respectively.

[0238] [Table 5]

[0239] [evaluation] <Blocking resistance> As the image forming apparatus, a color copying machine bizhub PRESS C71cf (manufactured by Konica Minolta, Inc.) was prepared, which was modified so that the fixing temperature, toner adhesion amount, and system speed could be freely set. Using the image forming apparatus and each of the developers prepared above, a toner adhesion amount of 10 g / m was formed on a resin recording medium. 2 An unfixed image of a solid patch measuring 100 mm square was formed. Image formation was performed in an environment of normal temperature and humidity (temperature 20°C, humidity 50% RH), with a fixing temperature of 150°C and a system speed of 270 mm / sec. In this image forming apparatus, the resin recording medium was transported through the image forming apparatus in a rolled state, and after the toner image was formed, it was rolled up again. In this way, an image was formed on the resin recording medium that was installed in a rolled state and then rolled up again and stored after printing. Corona-treated polyethylene terephthalate films with the thicknesses shown in the table below were used as the resin recording media in Examples 1 to 20, Examples 22 to 24, and Comparative Examples 1 and 2. In Example 21, a 50 μm-thick, non-corona-treated polyethylene terephthalate film was used as the resin recording media. After printing, the image was left in a rolled state for 24 hours, and then the image was slowly peeled off from the recording medium with a constant force of 2 N. The rate of image transfer to the recording medium was visually evaluated and ranked. Ranks A to C were considered acceptable. (standard) Rank A: Image transfer rate not confirmed (0%) Rank B: The image transfer rate was greater than 0% and less than 20%. Rank C: The image transfer rate was 20% or more but less than 40%. Rank D: Image transfer rate was 40% or more

[0240] <Varnish application> (Image creation) As the image forming apparatus, a color copying machine bizhub PRESS C71cf (manufactured by Konica Minolta, Inc.) was prepared, which was modified so that the fixing temperature, toner adhesion amount, and system speed could be freely set. Using the image forming apparatus and each of the developers prepared above, a toner adhesion amount of 8 g / m was recorded on evaluation paper. 2 An unfixed image of a solid patch measuring 30 mm x 90 mm was formed. The image was formed in an environment of normal temperature and humidity (temperature 20°C, humidity 50% RH), with a fixing temperature of 150°C and a system speed of 270 mm / sec. The evaluation paper used was POD-157 gloss coated paper (manufactured by Oji Paper Co., Ltd.). (Applying varnish) The image was coated with a varnish (UV VECTA Coat Varnish PC-3KW2, manufactured by T&K Corporation) using a bar coater to a thickness of 5 μm. After that, a high-pressure mercury lamp was used to apply a cumulative light intensity of 120 to 130 mJ / cm 2 to the image surface. 2 The varnish was cured by irradiating it with ultraviolet light so that the varnish layer was formed. The varnish used contained a polymerizable monomer for varnish having a polymerizable functional group containing an ethylenic double bond and a photopolymerization initiator (radical polymerization initiator). (Evaluation of Coatability) The surface of the varnish layer on the obtained image was visually inspected to see if the varnish was clearly repelled. If it was not repelled, the number of pinholes within a 10 cm x 10 cm area was counted. Based on these results, the varnish applicability was evaluated according to the following evaluation criteria. Ranks A to C were considered acceptable. (standard) Rank A: No pinholes were found within a 10cm x 10cm area Rank B: There were 1 to 2 tiny pinholes within a 10cm x 10cm area. Rank C: 3 to 10 tiny pinholes in a 10cm x 10cm area Rank D: There were 11 or more pinholes or cracks in an area of ​​10 cm x 10 cm.

[0241] <Heat-resistant storage stability> Two grams of toner was placed in a 10 ml glass bottle with an inner diameter of 21 mm, the lid closed, and shaken 600 times at room temperature using a Tap Denser KYT-2000 (Seishin Enterprise Co., Ltd.). The bottle was then left with the lid removed in an environment of 55°C and 35% RH for two hours. The sample was then removed and the mass of the aggregated toner was measured to evaluate its heat-resistant storage stability. The sample was then transferred onto a 42-mesh sieve, taking care to minimize structural damage, and shaken for 30 seconds using a REOSTAT powder analyzer (Hosokawa Micron Co., Ltd.) with the vibration intensity set to 4.5. The mass of the toner remaining on the sieve was then measured and used as the mass of the aggregated toner. The toner aggregation rate (mass%) was calculated from the mass of the aggregated toner and the mass of the sample. The toner storage stability was evaluated using the following four-point scale. (standard) A: Toner cohesion rate is less than 15% by mass (the toner has excellent storage stability and no problems during image formation) B: Toner cohesion rate is 15 to 45% by mass (the toner has good storage stability and no problems during image formation) C: Toner cohesion rate is 46 to 60% by mass (the storage stability of the toner is somewhat poor, causing some problems during image formation, but is within the acceptable range for use) D: The toner cohesion rate exceeds 60% by mass (the toner has poor storage stability and causes problems during image formation, making it unusable)

[0242] <Mountain peak density Spd> In the evaluation of the blocking resistance described above, the density of peaks Spd on the surface of the formed image was measured as follows. The recording medium on which the image was formed was placed with the toner layer side facing up on the stage of a laser microscope (VKX-250, manufactured by Keyence Corporation). The toner layer surface was focused using a 10x lens, and the original surface was subjected to surface filtering to determine the base surface and measurement surface. An evaluation area (total area 1425 μm × 1425 μm) was designated for the measurement surface, a reference surface corresponding to the measurement surface was determined, and Spd (peak density) was measured. Spd (peak density) was measured 10 times while randomly changing the observation location, and the average value was calculated.

[0243] [Table 6]

[0244] [Table 7]

[0245] [Table 8]

[0246] As shown in the above results, the content of C16-35 saturated compounds is kept below a specific amount, and the peak density Spd is 5000 mm -2 It can be seen that the image-forming method of the present invention, in which images are formed as described above, has superior blocking resistance and varnish coatability compared to the comparative example. It can also be seen that the inclusion of even a small amount of a C16-35 saturated compound improves heat-resistant storage stability. [Explanation of symbols]

[0247] R Resin recording medium Ra Back side of resin recording medium P Image Smooth surface of the Pa image Peak of the mountain in the Pb image 100 Image forming device 1 Paper feeder 101 Tensioning mechanism 101a, 101b driven rollers 101c Dancer Roller 101d weight 2 Main body 10 Control Unit 20 Memory section 30 Operation display section 31 Display section 32 Operation section 40 Image forming unit 50 Paper transport section 60 Fixing unit 61 Heating roller 62 Heating source 63 Upper pressure roller 64 Fixing belt 65 Lower pressure roller 70 Communications Department 3 Winding device 301 Tensioning mechanism 301a, 301b driven rollers 301c Dancer Roller 301d weight

Claims

1. An electrophotographic image forming method including a step of fixing an electrostatic image developing toner on a resin recording medium to form an image, the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms is 1000 ppm by mass or less relative to the total mass of the toner for developing electrostatic images, The resin recording medium was applied with a deposition amount of 4 g / m ２ When the above image is formed, the peak density Spd of the mountains on the surface of the image is 5000 mm －２ That's all An image forming method comprising:

2. The content of the saturated hydrocarbon compound is 1 ppm by mass or more based on the total mass of the toner for developing electrostatic images.

2. The image forming method according to claim 1.

3. The resin recording medium is a continuous-feed medium.

2. The image forming method according to claim 1.

4. The thickness of the resin recording medium is 75 μm or less.

2. The image forming method according to claim 1.

5. The resin recording medium is a polyethylene terephthalate film having a thickness of 50 μm.

2. The image forming method according to claim 1.

6. the toner for developing electrostatic images contains a binder resin, The binder resin contains at least an amorphous polyester and a crystalline polyester.

2. The image forming method according to claim 1.

7. The content of the amorphous polyester in the binder resin is within a range of 5 to 80% by mass.

7. The image forming method according to claim 6.

8. The polyhydric alcohol of the amorphous polyester is an aliphatic polyhydric alcohol or an alicyclic polyhydric alcohol.

7. The image forming method according to claim 6.

9. The polyhydric alcohol is an acyclic aliphatic polyhydric alcohol having 5 or more carbon atoms.

9. The image forming method according to claim 8.

10. The binder resin contains an amorphous resin having a weight average molecular weight in the range of 50,000 to 500,000.

7. The image forming method according to claim 6.

11. A step of applying varnish 2. The image forming method according to claim 1.

12. An electrophotographic image forming system having a toner for developing an electrostatic image and a means for fixing the toner for developing an electrostatic image to form an image, the content of saturated hydrocarbon compounds having 16 to 35 carbon atoms is 1000 ppm by mass or less relative to the total mass of the toner for developing electrostatic images, The resin recording medium was applied with a deposition amount of 4 g / m ２ When the above image is formed, the peak density Spd of the mountains on the surface of the image is 5000 mm －２ That's all An image forming system comprising:

Images