Image forming method

Abstract

To provide an image forming method capable of improving application properties to a liquid fixed image and adhesive properties to the liquid fixed image, while using a toner containing a conventional amount of mold release agent.SOLUTION: An image forming method has a step of forming an image on a recording medium by using a toner for electrostatic charge image development. The toner for electrostatic charge image development includes toner base particles containing a mold release agent. A polar component γp of surface energy of the image is 5 mN / m2 or more, and a dispersion component γd of surface energy of the image is 20 mN / m2 or more.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming method, and more particularly to an image forming method that can improve the coatability of a liquid material onto a fixed image and the adhesiveness of the liquid material to the fixed image while using a toner containing a conventional amount of release agent. [Background technology]

[0002] In the PP (production print) and IP (industrial printing) markets, electrophotographic image formation methods are sometimes used because they allow the required number of prints to be produced on demand and do not require printing plates.

[0003] In an electrophotographic image forming method, a toner image is thermally fixed onto a recording medium using a toner for developing an electrostatic image. Hereinafter, "toner for developing an electrostatic image" will be simply referred to as "toner," and "a toner image or an image formed by thermally fixing the toner image" will also be referred to as "fixed image."

[0004] Fixed images are required to be of higher quality, and in order to improve the image quality and durability of the fixed images, post-press processing is generally performed. Conventionally, the fixed images have been subjected to surface treatment before post-press processing to modify the surface of the fixed images. This has resulted in the formation of high-quality fixed images that are easy to process with post-press processing.

[0005] Examples of post-press processing include varnishing, laminating, gluing, and processing for supplying a decorative agent such as foil, etc. Techniques for forming high-quality fixed images that are easy to apply post-press processing have been disclosed.

[0006] For example, in the technology disclosed in Patent Document 1, a high-quality fixed image is formed by subjecting the fixed image to a discharge treatment (plasma) before post-press processing, and then performing surface treatment on the fixed image to reduce the water contact angle of the fixed image to 90 degrees or less, thereby providing excellent applicability to liquid substances such as varnish.

[0007] However, the liquid substance such as varnish applied to the fixed image formed by this technique has poor adhesiveness to the fixed image, and there is still room for improvement. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-59575 Summary of the Invention [Problem to be solved by the invention]

[0009] Incidentally, solids and liquids have finite surface energy, which affects mechanical work such as deformation and cracking, and is also consumed in chemical reactions such as oxidation and contamination. The surface energy of the fixed image is closely related to the applicability of a liquid substance such as varnish to the fixed image and the adhesiveness of the liquid substance to the fixed image after application. Hereinafter, "liquid substance such as varnish" will also be simply referred to as "liquid body."

[0010] In this specification, "applicability" refers to the degree of wettability of a liquid material to a fixed image. Furthermore, "adhesion" refers to the degree of adhesion of the liquid material after it has been applied to a fixed image. Furthermore, "liquid material" includes materials that have low fluidity and are semi-solid. Examples of semi-solid materials include adhesives. Therefore, the definition of "liquid material" includes not only "liquid materials such as varnishes" but also "semi-solid materials such as adhesives."

[0011] Here, the toner used in forming the fixed image may contain a widely used release agent to improve offset resistance and toner releasability from the fixed image. Hereinafter, "toner releasability from the fixed image" may also be simply referred to as "fixing separability."

[0012] In particular, release agents such as wax have low affinity with liquid substances such as general varnishes that have polar groups due to their nature. When a toner contains a low surface energy component such as wax as a release agent, when a liquid is applied to a fixed image, the fixed image tends to repel the liquid, making it difficult for the liquid to wet the image uniformly. In other words, when wax is present on the surface of the fixed image, the surface energy of the fixed image decreases, making it difficult to apply a liquid to the fixed image.

[0013] A reduction in the surface energy of a fixed image means that the surface of the fixed image is stabilized, but a fixed image with low surface energy is accompanied by various difficulties that arise during post-press processing. For example, when a liquid is applied to a fixed image formed using a toner containing wax as part of post-press processing, the liquid is repelled by the fixed image, resulting in poor applicability of the liquid. Furthermore, even after the liquid is applied to the fixed image, the adhesion is poor due to the poor compatibility between the fixed image with low surface energy and the liquid.

[0014] An example of a method for modifying the surface of the fixed image before post-press processing is to subject the fixed image to a surface treatment that increases the surface energy of the fixed image and controls the surface energy within an appropriate range.

[0015] Conventional techniques using the above-mentioned surface treatment methods include, for example, techniques using corona treatment and plasma treatment. However, although the fixed image formed by these techniques has excellent liquid applicability, there is a problem in that the adhesiveness between the liquid and the fixed image is poor after the liquid has wetted and spread. In other words, when post-press processing is performed on the fixed image, if the content of the release agent in the toner used in forming the fixed image is the same as in the past, there is a problem in that the adhesiveness is poor during post-press processing.

[0016] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved is to provide an image forming method that can improve the application property of a liquid material to a fixed image and the adhesion property of the liquid material to the fixed image while using a toner containing the same amount of release agent as conventional toners. [Means for solving the problem]

[0017] In order to solve the above-mentioned problems, the inventors have investigated the causes of the above-mentioned problems and have found that the above-mentioned problems can be solved by controlling the dispersive component and polar component of the surface energy of the image within a certain range while using a toner containing a conventional amount of release agent when forming a fixed image, and have arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0018] 1. An image forming method having a step of forming an image on a recording medium using a toner for developing an electrostatic image, the toner for developing an electrostatic image contains toner base particles containing a release agent, The polar component γ of the surface energy of the image p But 5mN / m 2 And, The dispersion component γ of the surface energy of the image d But 20mN / m 2 That's all An image forming method comprising:

[0019] 2. The polar component γ of the surface energy of the imagep But 30mN / m 2 is less than or equal to, and The dispersion component γ of the surface energy of the image d But 30mN / m 2 is 2. The image forming method according to claim 1,

[0020] 3. The toner base particles contain a crystalline polyester, The content of the crystalline polyester is in the range of 0.5 to 3.0% by mass. 2. The image forming method according to claim 1,

[0021] 4. The toner base particles contain at least an ester wax as the releasing agent. 2. The image forming method according to claim 1,

[0022] 5. In the process of forming an image on a recording medium using a toner for developing an electrostatic image, Uses a three-axis belt type fixing device 2. The image forming method according to claim 1,

[0023] 6. After the step of forming an image on the recording medium using the toner for developing an electrostatic image, The recording medium is wound into a roll. 2. The image forming method according to claim 1, [Effects of the Invention]

[0024] By the above-mentioned means of the present invention, it is possible to provide an image forming method that can improve the application property of the liquid material to the fixed image and the adhesion property of the liquid material to the fixed image while using a toner containing a conventional amount of release agent.

[0025] 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.

[0026] The image forming method of the present invention is an image forming method having a step of forming an image on a recording medium using a toner for developing an electrostatic image, wherein the toner for developing an electrostatic image contains toner base particles containing a release agent, and a polar component γ of the surface energy of the image is p But 5mN / m 2 or more, and the dispersion component γ of the surface energy of the image d But 20mN / m 2 The present invention is characterized in that:

[0027] Conventionally, corona treatment, plasma treatment, etc. have been applied to the surface of a fixed image to increase the surface energy of the fixed image and make it high quality, but although these treatments can form a fixed image with excellent liquid application properties, they do not provide excellent adhesion.

[0028] Therefore, in order to provide a fixed image of higher quality, it is necessary to improve the surface energy of the fixed image to enhance the coatability, while also improving the adhesiveness.

[0029] Here, the surface energy can be expressed as the sum of a dispersive component and a polar component, and the dispersive component γ d and the polar component γ p reflects the chemical properties of the surface.

[0030] “Dispersion component γ d " is a physical quantity that reflects the density, molecular weight, hardness, etc. of a substance, and "polar component γ p " is a physical quantity that directly reflects the density and activity of polar groups on the surface. Note that the dispersion components of solids and liquids will never be "zero," but the polar components can become "zero."

[0031] The fixed image formed by the image forming method of the present invention has a polar component γ of the surface energy of the image. p But 5mN / m 2 That's all. In this way, the variance component γ d When the charge distribution of the molecules in the image is large, the force of mutual attraction between the liquid and the fixed image in terms of charge increases, improving the coating properties.

[0032] Furthermore, the fixed image formed by the image forming method of the present invention has a dispersion component γ of the surface energy of the image. d But 20mN / m 2 That's all. In this way, the variance component γ d When the surface tension is large, the force of attraction between the polar molecules present in the liquid and the polar molecules present on the surface of the fixed image increases, improving the adhesiveness.

[0033] When a fixed image is formed using a toner for developing electrostatic images containing a conventional amount of release agent, it is difficult to achieve both improved application properties of the liquid material to the fixed image and improved adhesion properties of the liquid material to the fixed image.

[0034] However, by controlling the dispersive and polar components of the surface energy of the image within a certain range while using a toner containing the same amount of release agent as before when forming a fixed image, it is possible to achieve both improved application of the liquid to the fixed image and improved adhesion of the liquid to the fixed image, and it is thought that this will enable the formation of a high-quality fixed image that is easier to apply post-press processing. [Brief explanation of the drawings]

[0035] [Figure 1] An example of a schematic diagram illustrating the difference between conventional toner base particles and the toner base particles according to the present invention. [Figure 2] An example of a schematic diagram illustrating the difference between a conventional fixed image and a fixed image formed by the image forming method of the present invention. [Figure 3] An example of a cross-sectional schematic diagram of peripheral members of a fixing image forming portion in a biaxial belt type image forming apparatus [Figure 4] An example of a cross-sectional schematic diagram of peripheral members of a fixing image forming portion in a triaxial belt type image forming apparatus [Figure 5] An example of the configuration of an image forming apparatus equipped with a system for winding a recording medium into a roll DETAILED DESCRIPTION OF THE INVENTION

[0036] The image forming method of the present invention is an image forming method having a step of forming an image on a recording medium using a toner for developing an electrostatic image, wherein the toner for developing an electrostatic image contains toner base particles containing a release agent, and a polar component γ of the surface energy of the image is p But 5mN / m 2 or more, and the dispersion component γ of the surface energy of the image d But 20mN / m 2 The present invention is characterized in that: This feature is a technical feature common to or corresponding to each of the following embodiments (modes).

[0037] In one embodiment of the present invention, the polar component γ of the surface energy of the image p But 30mN / m 2 and the dispersion component γ of the surface energy of the image d But 30mN / m 2 The following conditions are preferred from the viewpoint of improving the coating properties of the liquid material onto the fixed image and the adhesive properties of the liquid material to the fixed image.

[0038] It is preferable that the toner base particles contain a crystalline polyester, and that the content of the crystalline polyester is within a range of 0.5 to 3.0% by mass, from the viewpoint of improving the adhesiveness of the liquid material to the fixed image.

[0039] It is preferable that the toner base particles contain at least an ester wax as the releasing agent, from the viewpoint of improving the toner releasability.

[0040] In the process of forming an image on a recording medium using a toner for developing an electrostatic image, it is preferable to use a fixing device of a triaxial belt type from the viewpoint of dispersing the pressure applied to the recording medium during image formation.

[0041] After forming an image on a recording medium using the electrostatic image developing toner, it is preferable that the recording medium is wound up in a roll, from the viewpoint of dispersing the pressure applied to the recording medium during image formation.

[0042] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0043] However, advantages and features provided by one or more embodiments of the present invention will be more fully understood from the following detailed description and the accompanying drawings, which are for illustrative purposes only and are not intended to define the limits of the invention.

[0044] [Image forming method] The image forming method of the present invention is an image forming method having a step of forming an image on a recording medium using a toner for developing an electrostatic image, wherein the toner for developing an electrostatic image contains toner base particles containing a release agent, and a polar component γ of the surface energy of the image is p But 5mN / m 2 or more, and the dispersion component γ of the surface energy of the image d But 20mN / m 2 The present invention is characterized in that:

[0045] The toner used in the image forming method of the present invention contains a release agent to improve offset resistance, fixation separation properties, etc. As described above, if the release agent is a wax, which is a low surface energy component, the surface energy of the fixed image will be low, and the application properties of the liquid to the fixed image will be poor.

[0046] Furthermore, although it has been possible to increase the surface energy of a fixed image by subjecting the image to corona treatment, plasma treatment, etc., as in the past, and thereby improve the applicability of a liquid material to the fixed image, the adhesiveness of the liquid material to the fixed image has not been excellent.

[0047] Therefore, in order to provide higher quality images, it is necessary to improve not only the applicability of the liquid to the fixed image but also the adhesiveness of the liquid to the fixed image.

[0048] 1. Surface energy of the image (1.1) Polar and dispersive components The surface energy can be expressed as the sum of a dispersive component and a polar component, and the dispersive component γ d and the polar component γ p The chemical properties of the surface are reflected in the toner surface. In the present invention, when forming a fixed image, the dispersive component and polar component of the surface energy of the image are controlled within a specific range while using a toner containing a conventional amount of release agent. This makes it possible to improve both the applicability of the liquid to the fixed image and the adhesion between the liquid and the fixed image.

[0049] “Dispersion component γ d " is a physical quantity that reflects the density, molecular weight, hardness, etc. of a substance, and "polar component γ p " is a physical quantity that directly reflects the density and activity of polar groups on the surface. Note that the dispersion components of solids and liquids will never be "zero," but the polar components can become "zero."

[0050] The fixed image formed by the image forming method of the present invention has a polar component γ of the surface energy of the image. p But 5mN / m 2 That's all. In this way, the variance component γ d When the charge distribution of the molecules in the image is large, the charge distribution of the molecules in the image becomes large, the force of attraction between the liquid and the fixed image becomes large, and the applicability of the liquid to the fixed image improves.

[0051] Furthermore, the fixed image formed by the image forming method of the present invention has a dispersion component γ of the surface energy of the image. d But 20mN / m 2 That's all. In this way, the variance component γ d When the surface tension is large, the force of attraction between the polar molecules present in the liquid and the polar molecules present on the side of the fixed image becomes large, improving the adhesiveness between the liquid and the fixed image.

[0052] In addition, since the fixed image formed by the image forming method of the present invention is an image before the liquid is applied, the above-mentioned "adhesion between the liquid and the fixed image" can also be rephrased as "adhesion of the fixed image to the liquid."

[0053] Dispersion component of the surface energy of the image γ d When the charge distribution is large, the charge distribution of the molecules constituting the image becomes large, and the charge distribution of the liquid applied to the fixed image becomes large, which improves the applicability of the liquid to the fixed image. In other words, the liquid spreads onto the fixed image.

[0054] When the polar component of the surface energy of the image is large, the charge bias of the polar molecules becomes large, and the attractive force between the polar molecules present on the surface of the fixed image and the polar molecules constituting the liquid increases, thereby improving the adhesion of the liquid to the fixed image after application.

[0055] The dispersion component of the surface energy of the aforementioned image, γ d and polar component γ p Basically, the larger the value of is, the more the adhesiveness of the liquid to the fixed image improves.

[0056] However, the surface energy present in solids and liquids is consumed as mechanical work such as deformation and cracking, and also as chemical reactions such as oxidation and contamination.

[0057] Therefore, the aforementioned polar component γ p But 30mN / m 2 and the variance component γ d But 30mN / m 2 When the surface energy is well balanced, the liquid has good coating properties and the liquid has good adhesive properties to the fixed image.

[0058] (1.2) Control method of surface energy of image As a method for controlling the surface energy of an image according to the present invention, for example, the following methods (1) to (4) can be mentioned. (1) A method of changing the types and amounts of components contained in the toner base particles contained in the toner used for forming a fixed image. (2) A method in which the toner base particles contained in the toner used in forming a fixed image have a core-shell structure, and the particle size of the resin particles that make up the shell is changed. (3) A method of changing the particle size of release agent particles contained in toner base particles contained in the toner used in forming a fixed image. (4) A method of suppressing bleeding out of the release agent contained in the toner base particles in the toner by dispersing the pressure applied to the fixed image during the formation of the fixed image.

[0059] Method (1) includes, for example, a method in which the resin contained in the toner base particles is a crystalline polyester and the content of the crystalline polyester is reduced below normal levels, or a method in which an ester wax is contained as a release agent.

[0060] As an example of method (2), when the resin particles constituting the shell are made of amorphous polyester, the particle size of the amorphous polyester can be increased. This makes it difficult for the release agent contained in the toner base particles to be exposed on the surface of the fixed image. This reduces the polar component γ of the surface energy of the image. p becomes larger.

[0061] In other words, if the particle size of the resin particles that make up the shell is increased, the polar component γ of the surface energy of the image p The polar component γ of the surface energy of the image can be increased by reducing the particle size of the resin particles. p can be made smaller.

[0062] As the method (3), for example, when the release agent contained in the toner base particles is wax, a method of reducing the particle size of the wax particles can be mentioned. According to this method, the dispersion component γ of the surface energy of the image can be reduced. d In other words, if the particle size of the release agent particles contained in the toner base particles is made smaller, the dispersion component γ of the surface energy of the image will be dThe dispersion component γ of the surface energy of the image can be increased by increasing the particle size of the release agent particles contained in the toner base particles. d can be made smaller.

[0063] Method (4) can be exemplified by increasing the number of shafts in the image forming apparatus used for forming the fixed image. Specifically, the image forming apparatus typically forms a fixed image using a two-shaft belt system, but the image can be formed using a three-shaft belt system, which allows for better pressure distribution during image formation. Alternatively, the recording medium on which the fixed image has been formed can be wound into a roll, which allows for better pressure distribution, and the image is formed while being wound.

[0064] (1.3) Measurement of the surface energy of an image Polar component γ of the surface energy of the fixed image p and variance component γ d can be measured and calculated, for example, as follows.

[0065] Water, diiodomethane, and n-hexadecane are applied to the fixed image as liquids. The contact angles of the fixed image are measured for each liquid using a fully automatic contact angle meter "DMo-701" manufactured by Kyowa Interface Science Co., Ltd., and each component of the surface energy is calculated based on the measurement results for each liquid using the Kitazaki-Hata theoretical formula.

[0066] 2. Toner base particle structure The electrostatic image developing toner according to the present invention contains toner base particles having a core-shell structure. The "core-shell structure" refers to a form in which a resin that forms a shell layer on the surface of a core particle is aggregated and fused. The shell layer does not have to cover the entire surface of the core particle, and the core particle may be partially exposed.

[0067] It is preferable that the toner base particles according to the present invention have a core-shell structure, in which the core particle contains a crystalline resin and an amorphous resin, and the shell layer contains an amorphous polyester.

[0068] It is also preferred that the toner base particles according to the present invention have a core-shell structure, and that the shell layer in the core-shell structure is a hybrid amorphous polyester, which is a resin in which a vinyl-based polymer segment and a polyester-based polymer segment are bonded.

[0069] The term "vinyl polymer segment" refers to a portion derived from a vinyl resin, i.e., a molecular chain having the same chemical structure as the molecular chain constituting the vinyl resin.

[0070] The term "polyester-based polymer segment" refers to a portion derived from polyester, i.e., a molecular chain having the same chemical structure as the molecular chain constituting polyester.

[0071] The influence of the structure of the toner base particles according to the present invention on the present invention will now be described. Fig. 1 is an example of a schematic diagram illustrating the difference between conventional toner base particles and the toner base particles according to the present invention.

[0072] In Figure 1, "T1" represents conventional toner base particles, and "T2" represents toner base particles according to the present invention. The symbols used for T1 and T2 are the same, and "C" represents core particles, "WAX" represents wax, "Apes" represents amorphous polyester, "Cpes" represents crystalline polyester, and "StAc" represents styrene-acrylic resin.

[0073] First, the structure of toner base particles contained in a normal toner produced by a conventional, publicly known method will be described. Hereinafter, "normal toner produced by a conventional, publicly known method" will also be simply referred to as "conventional toner," and "toner base particles contained in a conventional toner" will also be simply referred to as "conventional toner base particles."

[0074] In the following description, for convenience, the structure of conventional toner base particles and the structure of the toner base particles according to the present invention are limited to a core-shell structure, and the constituent components are also limited, but the structure of the toner base particles according to the present invention is not limited thereto.

[0075] Here, the affinity between the amorphous polyester Apes used in the shell and the wax WAX can be said to be considerably lower in terms of solubility parameter than the affinity between the crystalline polyester Cpes, one of the components of the core particle C, and the wax WAX.

[0076] Therefore, when the core particle C contains wax WAX, it is thought that as the particle size of the wax WAX increases or the content increases, the amorphous polyester Apes, which is the shell, becomes less compatible with the core particle C.

[0077] The toner used in the image forming method of the present invention has excellent fixing and separation properties while having the same wax content as conventional toners. Furthermore, the toner has undergone component and structure adjustment to provide a fixed image with excellent application properties of the liquid to the fixed image and excellent adhesive properties to the liquid toner.

[0078] In the toner base particles T2 according to the present invention, the wax content is the same as in the conventional toner base particles T1, but the particle size of the wax is smaller than that of the conventional toner base particles T1, and the particle size of the amorphous polyester Apes is larger. This reduces the adverse effect of the wax WAX, which has low affinity with the amorphous polyester Apes, on the toner base particles, and also increases the area of ​​the amorphous polyester Apes attached to the core particles C.

[0079] Here, when the core particle C of the toner base particle T2 is composed of styrene-acrylic resin StAc, the amorphous polyester Apes used in the shell has a high affinity with the styrene-acrylic resin StAc, so the shell easily blends with the core particle C.

[0080] The content of the crystalline polyester Cpes can be reduced compared to that of the conventional toner base particles T1 by the amount that the shell is more compatible with the core particles C. In the toner base particles T2 according to the present invention, the portion of the amorphous polyester Apes used in the shell that is exposed on the surface of the core particles C is increased in accordance with the amount of the reduced crystalline polyester Cpes.

[0081] When a toner containing toner base particles in which the amorphous polyester Apes is exposed on the surface of the core particle C more than in conventional toner base particles T1, such as the toner base particles T2 according to the present invention, is used for image formation, the amorphous polyester Apes is less likely to be embedded in the toner image.

[0082] Figure 2 is an example of a schematic diagram illustrating the difference between a conventional fixed image and a fixed image formed by the image forming method of the present invention. In Figure 2, "P" indicates a recording medium, "TP1" indicates a conventional fixed image, and "TP2" indicates a fixed image according to the present invention. Note that the "conventional fixed image" refers to a fixed image formed by using a conventional toner, and the "fixed image according to the present invention" refers to a fixed image formed by using the toner according to the present invention.

[0083] Compared with the conventional fixed image TP1, in the fixed image TP2 according to the present invention, the amorphous polyester Apes is less likely to be buried in the fixed image TP2 and is exposed on the surface.

[0084] A case where the fixed image TP2 according to the present invention has a smaller content of the crystalline polyester Cpes than the conventional fixed image TP1 will be described.

[0085] The polar molecules in the amorphous polyester Apes in the fixed image TP2 according to the present invention are more likely to be oriented toward the outside of the fixed image than in the conventional fixed image TP1 due to the small amount of the crystalline polyester Cpes. Note that the "outside of the fixed image" refers to the opposite side of the recording medium P from the fixed image in FIG. 2.

[0086] During image formation, the wax WAX, which exists in a finely dispersed state in the fixed image, passes through the styrene-acrylic resin StAc and tries to come out to the surface of the fixed image through the gaps between the amorphous polyester Apes. As a result, the wax WAX becomes scattered among the amorphous polyester Apes.

[0087] Since the wax WAX is present on the entire surface of the fixed image in both fixed images T1 and T2, the fixation separation properties are the same between the conventional fixed image T1 and the fixed image T2 of the present invention. However, since the particle size of the amorphous polyester Apes in the fixed image T2 of the present invention is larger than that of the amorphous polyester Apes contained in the conventional fixed image T1, the wax WAX does not appear on the surface of the fixed image T2.

[0088] Therefore, the fixed image T2 according to the present invention has more amorphous polyester Apes and styrene-acrylic resin StAc on the surface of the fixed image than the conventional fixed image T1, which results in more functional groups of the amorphous polyester and styrene-acrylic resin being oriented on the surface of the image, increasing the dispersion component and polar component.

[0089] Alternatively, if the wax is dispersed on the surface of the image rather than existing in an island-like form, the functional groups of the amorphous polyester or styrene-acrylic resin will be more oriented on the surface of the image, increasing the dispersed and polar components.

[0090] The physical properties of the surface of such a fixed image T2 are represented by the surface energy of the image, and the polar component γ of the surface energy of the image is p But 5mN / m2 or more, and the dispersion component γ of the surface energy of the image d But 20mN / m 2 That's all.

[0091] (Method for observing the cross section of a core-shell structure) The cross section of the core-shell structure can be observed using known observation methods such as a transmission electron microscope (TEM) or a scanning probe microscope (SPM). Note that "TEM" is an abbreviation for Transmission Electron Microscope, and "SPM" is an abbreviation for Scanning Probe Microscope.

[0092] (Toner manufacturing method) When the toner base particle has a core-shell structure, the core particle and the shell layer can have different properties such as glass transition point, melting point, and hardness, making it possible to design toner particles according to the purpose.

[0093] When producing a toner, for example, a binder resin, a colorant, a release agent, etc. are contained in toner base particles, and then, it is preferable to form a shell layer on the surface of core particles having a relatively low glass transition temperature (Tg) by aggregating and fusing a resin having a relatively high glass transition temperature (Tg).

[0094] As a reference for a method for producing a toner containing toner base particles having a core-shell structure, for example, JP 2016-161780 A can be mentioned.

[0095] Toner base particles having a core-shell structure can be obtained, for example, by emulsion aggregation, which involves preparing toner base particles in the following manner.

[0096] Core particles are produced by aggregating and fusing binder resin particles, crystalline substances, and colorants for the core particles. Next, a dispersion of the core particles is prepared, and binder resin particles for the shell layer are added to the dispersion of the core particles. The binder resin particles for the shell layer are aggregated and fused to the surface of the core particles to form a shell layer that covers the surface of the core particles. This produces toner base particles with a core-shell structure.

[0097] The toner base particles according to the present invention may have a domain-matrix structure. The "domain-matrix structure," also known as an "island-sea structure," refers to a structure in which island-shaped dispersed phases (domains) with closed interfaces exist within the continuous phase (matrix) of the toner base particles. The "matrix" corresponds to the "sea" in the "island-sea structure." The "closed interface" is the "boundary between phases."

[0098] Toner base particles having a domain-matrix structure may have, for example, a portion in which an amorphous polyester resin or a hybrid amorphous polyester resin is incompatible with an amorphous resin. Note that the toner base particles according to the present invention contain a release agent such as wax in addition to the resin in the domain or matrix.

[0099] The "domain" may contain a lamellar crystal structure, and the structure of the toner base particle can be observed using an electron microscope "JSM-7401F" manufactured by JEOL Ltd. under the following conditions. <Condition> Sample: Section of toner particles stained with ruthenium tetroxide (RuO4) (section thickness: 60-100 nm) Accelerating voltage: 30 kV Magnification: 50000x Observation conditions: transmission electron detector, bright field image

[0100] When the toner base particles have a domain-matrix structure, the average diameter of the domains is preferably within a range of 50 to 150 nm. Note that the "average diameter of the domains" here refers to the average value of the major axes of the domains.

[0101] The average diameter of the domains can be measured by observing and analyzing, with an electron microscope and an image processing analyzer, domains stained by the method described in the conditions for observing the structure of the toner base particles with the above-mentioned electron microscope "JSM-7401F."

[0102] An example of the electron microscope and image processing analysis device is "LUZEX (registered trademark) AP" manufactured by Nireco Corporation.

[0103] 3. Components of toner base particles The toner for developing electrostatic images according to the present invention includes toner base particles containing at least a release agent. The toner base particles may contain other components such as a binder resin, a colorant, and a charge control agent in addition to the release agent. The toner according to the present invention includes toner particles having the toner base particles and an external additive disposed on the surface of the toner base particles.

[0104] In this specification, "toner base particles" refer to the base of "toner particles." "Toner base particles" are called "toner particles" when an external additive is added. "Toner" refers to an "aggregate of toner particles."

[0105] (3.1) Release agent A release agent is contained in the toner used in forming a fixed image in order to improve offset resistance and fixation separation properties. When a release agent is contained in the toner base particles, the release agent oozes out from the toner base particles during fixed image formation. This improves the toner release properties during fixed image formation, allowing for the production of higher quality images.

[0106] In particular, release agents such as wax have low affinity for liquid substances (liquid bodies) such as general varnishes that have polar groups. When a toner contains a low surface energy component such as wax as a release agent, when a liquid body is applied to a fixed image, the fixed image formed using the toner tends to repel the liquid body, making it difficult for the liquid body to wet evenly. In other words, the liquid body's applicability to the image deteriorates, causing the wax to bleed onto the surface of the fixed image, resulting in the formation of a fixed image with low surface energy.

[0107] Wax is used as the release agent in the present invention. Examples of wax include ester waxes and hydrocarbon waxes. These waxes may be used in combination and contained in the toner base particles. Furthermore, the toner base particles may further contain a release agent other than those mentioned above, such as an amide wax.

[0108] It is preferable that the toner base particles contain an ester wax as a release agent from the viewpoint of improving the toner releasability from a fixed image. In this case, the toner base particles do not contain a hydrocarbon wax as a release agent, thereby improving the toner releasability.

[0109] Therefore, it is preferable that the ester wax is contained alone in the toner base particles without using the ester wax and the hydrocarbon wax in combination, from the viewpoint of improving the toner releasability from the fixed image.

[0110] (3.1.1) Ester wax The toner base particles according to the present invention preferably contain an ester wax as a release agent from the viewpoint of improving the toner releasability from fixed images. Because ester wax has polar molecules, the toner base particles containing an amorphous polyester as the binder resin have a higher affinity and are more compatible with the ester wax than the toner base particles containing a styrene-acrylic resin as the binder resin.

[0111] Therefore, when the toner base particles contain an amorphous polyester as a binder resin, the ester wax tends to be uniformly scattered on the surface of the fixed image, and therefore, the toner releasability, which is an advantage of the wax, can be maximized with a smaller amount.

[0112] Therefore, even if the amount of wax used when forming a fixed image is the same, the use of ester wax can ensure better fixing separation properties than the use of wax other than ester wax.

[0113] The ester wax is not particularly limited, and examples thereof include monoester wax, diester wax, triester wax, tetraester wax, and waxes having five or more ester bonds.

[0114] Examples of ester-based waxes include behenyl behenate, triglycerol behenate, pentaerythritol tetrastearate, stearyl stearate, pentaerythritol tetrabehenate, ethylene glycol stearate, ethylene glycol behenate, neopentyl glycol stearate, neopentyl glycol behenate, 1,6-hexanediol stearate, 1,6-hexanediol behenate, glycerin stearate, glycerin behenate, stearyl citrate, behenyl citrate, stearyl phosphate, and behenyl phosphate.

[0115] The ester wax may be a natural wax such as carnauba wax.

[0116] (3.1.2) Hydrocarbon wax The hydrocarbon wax is not particularly limited, and examples thereof include polyolefin waxes such as polyethylene wax and polypropylene wax, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax.

[0117] (3.1.3) Melting Point The melting point of the wax is preferably 60° C. or higher, more preferably 70° C. or higher, and preferably 140° C. or lower, more preferably 120° C. or lower, and even more preferably 100° C. or lower. This ensures a good balance between heat-resistant storage stability and fixability, as well as toner manufacturability. When two or more waxes are used in combination, it is preferable that the melting points of the respective waxes be within the above ranges.

[0118] (3.1.4) Content The content of the wax in the toner base particles is preferably within a range of 0.5 to 6 parts by mass relative to the binder resin.

[0119] Since wax tends to appear on the image surface during toner fixing, when wax is contained in the toner base particles contained in the toner used during image formation, the fixing separation property is improved, but the surface energy of the image is reduced. However, in the present invention, by increasing the surface energy of the image and controlling it within a certain range, it is possible to form a high-quality image.

[0120] (3.2) Binder resin The term "binder resin" refers to a resin that is used as a medium or matrix (parent body) for dispersing and retaining the internal and external additives contained in the toner particles, and that has the function of adhering to the recording medium during the fixing process of the toner image. Examples of internal additives include release agents, charge control agents, and colorants. Examples of external additives include silica and titanium oxide.

[0121] As the binder resin contained in the toner base particles according to the present invention, a conventionally known binder resin can be used, and examples of the binder resin include crystalline resins and amorphous resins.

[0122] (3.2.1) Crystalline resin A "crystalline resin" refers to a resin that exhibits a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC). Specifically, a "clear endothermic peak" refers to a peak whose half-width is 15°C or less when measured at a heating rate of 10°C / min in differential scanning calorimetry (DSC).

[0123] The content of the crystalline resin relative to the toner base particles is preferably within a range of 1 to 40% by mass, more preferably within a range of 7 to 15% by mass, from the viewpoint of obtaining sufficient low-temperature fixability. The crystalline resin may be one type or two types.

[0124] When the content of the crystalline resin is 0.5% by mass or more, a sufficient plasticizing effect is obtained, resulting in sufficient low-temperature fixability, and when the content of the crystalline resin is 20% by mass or less, the toner has sufficient thermal stability and stability against physical stress.

[0125] The crystalline resin is not particularly limited, but examples thereof include polyolefin, polydiene, polyester, etc. Among these, crystalline polyester is preferred from the viewpoint of being able to obtain sufficient low-temperature fixability and gloss uniformity, and being easy to use.

[0126] The number average molecular weight (Mn) of the crystalline resin is preferably within the range of 2,500 to 5,000, and more preferably within the range of 3,000 to 4,500.

[0127] From the viewpoint of low-temperature fixability and gloss stability, the number average molecular weight (Mn) of the crystalline resin is preferably within a range of 3,000 to 12,500, and more preferably within a range of 4,000 to 11,000.

[0128] The weight average molecular weight (Mw) of the crystalline resin is preferably within a range of 10,000 to 100,000, more preferably within a range of 15,000 to 80,000, and even more preferably within a range of 20,000 to 50,000.

[0129] When the weight-average molecular weight (Mw) and number-average molecular weight (Mn) are within the above ranges, it is easy to achieve a balance between fixability and heat resistance. Furthermore, sufficient strength is obtained in fixed images. Furthermore, in the production of the toner, the crystalline resin is not pulverized during emulsion stirring, and the glass transition temperature (Tg) of the toner is maintained constant, thereby maintaining the thermal stability of the toner.

[0130] The weight average molecular weight (Mw) and number average molecular weight (Mn) can be determined from the molecular weight distribution measured by the above-mentioned gel permeation chromatography (GPC).

[0131] (crystalline polyester) Crystalline polyesters are obtained by a polycondensation reaction between a divalent or higher carboxylic acid (a polycarboxylic acid) and a divalent or higher alcohol (a polyhydric alcohol).

[0132] The polycarboxylic acid for obtaining the crystalline polyester may be a divalent or higher carboxylic acid, for example, a trivalent or higher carboxylic acid such as trimellitic acid or pyromellitic acid. From the viewpoint of the crystallinity of the crystalline polyester, a dicarboxylic acid is preferred. Examples of the dicarboxylic acid include an aliphatic carboxylic acid and an aromatic dicarboxylic acid.

[0133] Examples of aliphatic carboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid. Other examples include 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (dodecanedioic acid), and 1,13-tridecanedicarboxylic acid. Other examples include 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid.

[0134] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, orthophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid.

[0135] The crystalline polyester may contain only one structural unit derived from the above-mentioned aliphatic carboxylic acids or aromatic dicarboxylic acids, or may contain structures derived from two or more carboxylic acids.

[0136] From the viewpoint of exerting the effects of the present invention, aliphatic carboxylic acids are preferred. The number of carbon atoms in the linear hydrocarbon structure of the aliphatic carboxylic acid is preferably in the range of 6 to 16, more preferably in the range of 10 to 14. The hydrocarbon structure of the aliphatic carboxylic acid may be partially branched. In this case, the hydrocarbon chain sandwiched between two carboxy groups is specified as the linear hydrocarbon structure.

[0137] The polyhydric alcohol for obtaining the crystalline polyester may be a dihydric or higher alcohol, and may be a trihydric or higher alcohol such as glycerin, pentaerythritol, trimethylolpropane, sorbitol, etc. From the viewpoint of the crystallinity of the crystalline polyester, a dihydric alcohol is preferred.

[0138] Examples of dihydric alcohols include aliphatic diols, diols having an unsaturated double bond, and diols having a sulfonic acid group.

[0139] Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, and 1,8-octanediol. Also included are 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, and 1,13-tridecanediol. Also included are 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol.

[0140] Examples of diols having an unsaturated double bond include 2-butene-1,4-diol, 3-hexene-1,6-diol, and 4-octene-1,8-diol.

[0141] [Crystalline polyester content] The content of the crystalline polyester is preferably in the range of 0.5 to 5.0% by mass from the viewpoint of improving the adhesiveness of the liquid to the fixed image, and more preferably in the range of 0.5 to 3.0% by mass from the same viewpoint.

[0142] The content of crystalline polyester contained in the toner base particles contained in the toner according to the present invention is lower than that contained in ordinary toners. As a result, when amorphous polyester is present on the image surface, polar molecules of the amorphous polyester tend to orient toward the outside of the fixed image surface, improving the adhesiveness of the liquid to the fixed image.

[0143] [Melting point] The melting point of the crystalline polyester is preferably in the range of 50 to 85°C from the viewpoint of sufficiently softening the toner particles and ensuring sufficient low-temperature fixability, and more preferably in the range of 60 to 80°C from the viewpoint of improving various properties in a balanced manner.

[0144] The melting point of the crystalline polyester can be controlled by the structure of the resin (for example, the type of monomer).

[0145] [Molecular weight] The weight average molecular weight (Mw) of the crystalline polyester is preferably within a range of 5,000 to 50,000, and the number average molecular weight (Mn) is preferably within a range of 2,000 to 10,000. When the weight average molecular weight (Mw) and number average molecular weight (Mn) of the crystalline polyester are within the above ranges, the low temperature fixability is improved.

[0146] [Manufacturing method] The crystalline polyester can be produced by polycondensing (esterifying) the above polycarboxylic acid and polyhydric alcohol using a known esterification catalyst.

[0147] The catalyst used in the production of the crystalline polyester may be one or more. Examples of the catalyst include alkali metal compounds such as sodium and lithium, and compounds containing Group 2 elements such as magnesium and calcium. Other examples include metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium, phosphorous compounds, phosphoric acid compounds, and amine compounds.

[0148] The polymerization temperature for the crystalline polyester is preferably within a range of 150 to 250° C. The polymerization time is preferably within a range of 0.5 to 10 hours. During the polymerization, the pressure in the reaction system may be reduced as necessary.

[0149] (hybrid crystalline polyester) When the toner base particles according to the present invention contain a crystalline polyester, the crystalline polyester may be a hybrid crystalline polyester. When the crystalline polyester is a hybrid crystalline polyester, the affinity with the amorphous resin used in combination is improved, and the low-temperature fixability of the toner to an image is improved. Furthermore, the dispersibility of the crystalline resin in the toner is improved, thereby suppressing the bleed-out of the crystalline resin onto the surface of the fixed image.

[0150] Hereinafter, the "hybrid crystalline polyester" may also be simply referred to as "hybrid resin."

[0151] The hybrid resin may be one or more kinds. The hybrid resin may replace all or part of the crystalline polyester, or may be used in combination with the crystalline polyester.

[0152] The hybrid resin is a resin in which a crystalline polyester polymer segment and an amorphous polymer segment are chemically bonded.

[0153] The term "crystalline polyester polymer segment" refers to a portion derived from a crystalline polyester, that is, a molecular chain having the same chemical structure as the molecular chain constituting the above-mentioned crystalline polyester.

[0154] The term "amorphous polymer segment" refers to a portion derived from an amorphous resin, i.e., a molecular chain having the same chemical structure as the molecular chain constituting the amorphous resin described below.

[0155] The constituent components and content of each polymer segment in the toner can be identified by using known analytical methods such as nuclear magnetic resonance (NMR) and methylation reaction pyrolysis gas chromatography / mass spectrometry (Py-GC / MS).

[0156] [Weight average molecular weight] The weight average molecular weight (Mw) of the hybrid resin is preferably in the range of 5,000 to 100,000, more preferably in the range of 7,000 to 50,000, and even more preferably in the range of 8,000 to 20,000, from the viewpoint of reliably achieving both sufficient low-temperature fixability and excellent long-term storage stability.

[0157] By setting the weight average molecular weight (Mw) of the hybrid resin to 100,000 or less, sufficient low-temperature fixability can be obtained. On the other hand, by setting the weight average molecular weight (Mw) of the hybrid resin to 5,000 or more, excessive progress of compatibility between the hybrid resin and the amorphous resin during toner storage can be suppressed, and image defects due to fusion of toner particles can be effectively suppressed.

[0158] [Crystalline polyester polymer segment] The crystalline polyester polymer segment may be, for example, a resin having a structure in which other components are copolymerized into a main chain of a crystalline polyester polymer segment, or a resin having a structure in which a crystalline polyester polymer segment is copolymerized into a main chain made of other components. The crystalline polyester polymer segment can be produced from the above-mentioned polycarboxylic acid and polyhydric alcohol in the same manner as the above-mentioned crystalline polyester.

[0159] The constituent components and content of the crystalline polyester polymer segment in the hybrid resin (or in the toner) can be identified using known analytical methods such as NMR, methylation reaction Py-GC / MS, etc.

[0160] [Amorphous Polymer Segment] The amorphous polymer segment enhances the affinity between the amorphous resin constituting the binder resin and the hybrid resin, which makes it easier for the hybrid resin to be incorporated into the amorphous resin, further improving the uniformity of toner charging.

[0161] The amorphous polymer segment is preferably composed of the same type of resin as the amorphous resin contained in the binder resin, from the viewpoint of increasing affinity with the binder resin and improving the charging uniformity of the toner. By adopting such a form, the affinity between the hybrid resin and the amorphous resin is further improved, and "same type of resin" means resins having characteristic chemical bonds in the repeating units.

[0162] The "characteristic chemical bonds" are based on the "polymer classification" listed in the National Institute for Materials Science (NIMS) Materials Database (http: / / polymer.nims.go.jp / PoLyInfo / guide / jp / term_polymer.html). Specifically, the chemical bonds that make up polymers classified into 22 types, including polyacrylic, polyamide, polyanhydride, polycarbonate, polydienes, polyesters, polyhaloolefins, polyimides, polyimines, polyketones, polyolefins, polyethers, polyphenylenes, polyphosphazenes, polysiloxanes, polystyrenes, polysulfides, polysulfones, polyurethanes, polyureas, polyvinyls, and other polymers, are called "characteristic chemical bonds."

[0163] Furthermore, when the resin is a copolymer, "same type of resin" refers to resins that share a characteristic chemical bond when the monomer species having the above-mentioned chemical bond are used as constituent units in the chemical structures of the multiple monomer species that make up the copolymer. Therefore, even if the properties exhibited by the resins themselves are different from each other or the molar ratios of the monomer species that make up the copolymer are different from each other, they are considered to be the same type of resin as long as they share the characteristic chemical bond.

[0164] For example, a resin (or a polymerized segment) formed from styrene, butyl acrylate, and acrylic acid and a resin (or a polymerized segment) formed from styrene, butyl acrylate, and methacrylic acid have at least a chemical bond constituting polyacrylic. Therefore, they are the same type of resin. For example, a resin (or a polymerized segment) formed from styrene, butyl acrylate, and acrylic acid and a resin (or a polymerized segment) formed from styrene, butyl acrylate, acrylic acid, terephthalic acid, and fumaric acid have at least a chemical bond that constitutes polyacrylic as a common chemical bond. Therefore, they are the same type of resin.

[0165] Examples of the amorphous polymer segment include a vinyl polymer segment, a urethane polymer segment, and a urea polymer segment. Among them, a vinyl polymer segment is preferred from the viewpoint of easy control of thermoplasticity. The vinyl polymer segment can be synthesized in the same manner as the vinyl resin according to the present invention.

[0166] The constituent components and content of the amorphous polymerized segment in the hybrid resin (or in the toner) can be identified by using known analytical methods such as NMR, methylation reaction Py-GC / MS, and the like.

[0167] [Manufacturing method] The hybrid resin can be produced, for example, by the production methods (1) to (3) shown below. For details of the production methods, reference can be made to paragraphs 0088 to 0099 of JP 2020-197711 A. (1) A method for producing a hybrid resin by carrying out a polymerization reaction to synthesize a crystalline polyester polymer segment in the presence of a previously synthesized amorphous polymer segment. (2) A method in which a crystalline polyester polymer segment and an amorphous polymer segment are formed in advance and then bonded to produce a hybrid resin. (3) A method for producing a hybrid resin by carrying out a polymerization reaction to synthesize an amorphous polymer segment in the presence of a crystalline polyester polymer segment.

[0168] (3.2.2) Amorphous resin The toner base particles according to the present invention preferably contain an amorphous resin, and it is preferable that the amorphous resin is a styrene-acrylic resin from the viewpoint of the balance of thermal properties, exudation of the release agent, and compatibility with additives.

[0169] An "amorphous resin" is a resin that does not have crystallinity, and is a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) in differential scanning calorimetry (DSC).

[0170] The glass transition temperature (Tg) of the amorphous resin is preferably within the range of 35 to 80°C, and particularly preferably within the range of 45 to 65°C.

[0171] The glass transition temperature (Tg) can be measured according to the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-82. For measuring the glass transition temperature (Tg), a DSC-7 Differential Scanning Calorimeter (manufactured by PerkinElmer), a TAC7 / DX Thermal Analysis Device Controller (manufactured by PerkinElmer), or the like can be used.

[0172] The amorphous resin may be one or more types, and examples of the amorphous resin include vinyl resin, urethane resin, urea resin, and amorphous polyester such as styrene-acrylic modified polyester.

[0173] From the viewpoint of easy control of thermoplasticity, the amorphous resin preferably contains a vinyl resin as the main component of the binder resin, and also preferably contains an amorphous polyester.

[0174] The number average molecular weight (Mn) of the amorphous resin is preferably within a range of 5000 to 150000, and more preferably within a range of 8000 to 70000. The molecular weight of the amorphous resin can be measured in the same manner as the above-mentioned method for measuring the molecular weight distribution.

[0175] (vinyl resin) Examples of vinyl resins include acrylate resins, styrene-acrylate resins, ethylene-vinyl acetate resins, etc. Among these, styrene-acrylate resins (styrene-acrylic resins) are preferred from the viewpoint of plasticity during thermal fixing.

[0176] [Styrene-acrylic resin] Styrene-acrylic resins are formed by addition polymerization of at least styrene monomer and (meth)acrylic acid ester monomer. Styrene monomers include styrene, represented by the structural formula CH2=CH-C6H5, as well as styrene derivatives with known side chains or functional groups in the styrene structure.

[0177] The (meth)acrylic acid ester monomer includes not only acrylic acid esters and methacrylic acid esters represented by CH(R1)=CHCOOR2 (where R1 represents a hydrogen atom or a methyl group, and R2 represents an alkyl group having 1 to 24 carbon atoms), but also acrylic acid ester derivatives and methacrylic acid ester derivatives having known side chains or functional groups in the structure of these esters.

[0178] Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, and 2,4-dimethylstyrene, as well as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, and pn-dodecylstyrene.

[0179] Examples of the (meth)acrylic acid ester monomer include acrylic acid ester monomers and methacrylic acid esters.

[0180] Examples of acrylic acid ester monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, and n-octyl acrylate. Other examples include 2-ethylhexyl acrylate (2EHA), stearyl acrylate, lauryl acrylate, and phenyl acrylate.

[0181] Examples of methacrylic acid esters include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and n-octyl methacrylate, as well as 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, and dimethylaminoethyl methacrylate.

[0182] In this specification, the term "(meth)acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer," and means one or both of them. For example, "methyl (meth)acrylate" means one or both of "methyl acrylate" and "methyl methacrylate."

[0183] The (meth)acrylic acid ester monomer may be one or more types. For example, a copolymer can be formed using a styrene monomer and two or more types of acrylic acid ester monomers. Also, a copolymer can be formed using a styrene monomer and two or more types of methacrylic acid ester monomers. Also, a copolymer can be formed using a styrene monomer in combination with an acrylic acid ester monomer and a methacrylic acid ester monomer.

[0184] Styrene-acrylic resins can be synthesized by polymerizing monomers using known oil-soluble or water-soluble polymerization initiators, such as azo-based initiators, diazo-based initiators, and peroxide-based initiators.

[0185] Examples of azo polymerization initiators and diazo polymerization initiators include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azobis(cyclohexane-1-carbonitrile), as well as 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile.

[0186] Examples of peroxide polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, and t-butyl hydroperoxide. Other examples include di-t-butyl peroxide, dicumyl peroxide, and 2,4-dichlorobenzoyl peroxide. Other examples include lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine.

[0187] When synthesizing styrene-acrylic resin particles using emulsion polymerization, water-soluble radical polymerization initiators can be used. Examples of water-soluble polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate. Other examples include azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0188] The amorphous resin may further contain structural units derived from other monomers besides the styrene monomer and (meth)acrylic acid ester monomer. The other monomer is preferably a compound that forms an ester bond with a hydroxy group (-OH) derived from a polyhydric alcohol or a carboxy group (-COOH) derived from a polycarboxylic acid. That is, the amorphous resin is preferably a polymer that is addition polymerizable with the styrene monomer and (meth)acrylic acid ester monomer and is further polymerized with a compound (amphoteric compound) having a carboxy group or a hydroxy group.

[0189] Examples of the amphoteric compound include compounds having a carboxy group and compounds having a hydroxy group.

[0190] Examples of compounds having a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl esters, and itaconic acid monoalkyl esters.

[0191] Examples of compounds having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate, as well as 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and polyethylene glycol mono(meth)acrylate.

[0192] (amorphous polyester) When toner base particles have a core-shell structure, amorphous polyester is preferably used as the shell because it has excellent heat resistance without impairing fixability. Amorphous polyester is a polyester resin that has no melting point and a relatively high glass transition temperature (Tg) when subjected to differential scanning calorimetry (DSC). The monomers that make up amorphous polyester are different from those that make up crystalline polyester, so it can be distinguished from crystalline polyester by analysis such as NMR.

[0193] Amorphous polyesters are obtained by a polycondensation reaction between a divalent or higher carboxylic acid (a polycarboxylic acid) and a divalent or higher alcohol (a polyhydric alcohol). There are no particular limitations on the amorphous polyester, and any amorphous polyester known in the art can be used.

[0194] The specific method for producing the amorphous polyester is not particularly limited, and the resin can be produced by polycondensing (esterifying) a polycarboxylic acid and a polyhydric alcohol using a known esterification catalyst.

[0195] The catalyst that can be used in the production, the temperature of polycondensation (esterification), and the time of polycondensation (esterification) are not particularly limited, and are the same as those for the crystalline polyester described above.

[0196] (3.3) Other (coloring agent) The colorant contained in the toner base particles according to the present invention is not particularly limited, and for example, various known pigments and dyes can be used, and these may also be used in combination.

[0197] The colorant may be one or more kinds. Typical colorants include, for example, a colorant for magenta, a colorant for yellow, a colorant for cyan, and a colorant for black.

[0198] Examples of magenta colorants include CI Pigment Red 2, 3, 5, 6, 7, 15, 16, 48:1, 53:1, 57:1, 60, 63, 64, 68, 81, 83, 87, 88, 89, and 90. Other examples include CI Pigment Red 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, and 269.

[0199] Examples of yellow colorants include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, CI Pigment Yellow 155, CI Pigment Yellow 162, CI Pigment Yellow 180, and CI Pigment Yellow 185.

[0200] Examples of colorants for cyan include CI Pigment Blue 2, 3, 15, 15:2, 15:3, 15:4, 16, 17, 60, 62, 66, and CI Pigment Green 7.

[0201] Examples of black colorants include carbon black and magnetic particles.

[0202] Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black.

[0203] Examples of the magnetic material of the magnetic particles include ferromagnetic metals such as iron, nickel, and cobalt. Also included are alloys containing these metals. Also included are ferromagnetic metal compounds such as ferrite and magnetite. Also included are chromium dioxide and alloys that do not contain ferromagnetic metals but exhibit ferromagnetism upon heat treatment.

[0204] Examples of alloys that exhibit ferromagnetism upon heat treatment include Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin.

[0205] The content of the colorant in the toner base particles can be determined appropriately and independently. For example, from the viewpoint of ensuring color reproducibility of the image, it is preferably in the range of 1 to 30% by mass, and more preferably in the range of 2 to 20% by mass.

[0206] The particle size of the colorant is, for example, preferably in the range of 10 to 1000 nm, more preferably in the range of 50 to 500 nm, and even more preferably in the range of 80 to 300 nm, in terms of volume average particle size.

[0207] The volume average particle size may be a catalog value, and for example, the volume average particle size (volume-based median diameter) of the colorant can be measured using "UPA-150" (manufactured by Microtrack Bell Co., Ltd.).

[0208] (charge control agent) The charge control agent to be contained in the toner base particles according to the present invention is not particularly limited, and various known compounds can be used, such as nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, and alkoxylated amines. Other examples include quaternary ammonium salt compounds, azo metal complexes, and metal salicylates.

[0209] The content of the charge control agent is usually in the range of 0.1 to 10% by mass relative to the toner base particles finally obtained, and the preferred content of the charge control agent is in the range of 0.5 to 5% by mass.

[0210] The size of the charge control agent particles is usually within the range of 10 to 1000 nm in terms of number average primary particle diameter, and preferably within the range of 50 to 500 nm, and more preferably within the range of 80 to 300 nm.

[0211] (external additives) The toner particles can be used as they are, but may be treated with external additives such as a fluidizing agent and a cleaning aid in order to improve the flowability, chargeability, cleaning properties, and the like.

[0212] Examples of the external additive include inorganic oxide fine particles, inorganic stearic acid compound fine particles, and inorganic titanic acid compound fine particles, which may be used alone or in combination of two or more.

[0213] Examples of inorganic oxide fine particles include silica fine particles, alumina fine particles, and titanium oxide fine particles.

[0214] Examples of inorganic stearic acid compound fine particles include aluminum stearate fine particles and zinc stearate fine particles.

[0215] Examples of inorganic titanate compound fine particles include strontium titanate and zinc titanate.

[0216] From the viewpoint of improving heat-resistant storage stability and environmental stability, it is preferable that these external additives are surface-treated with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like.

[0217] The amount of the external additive added is preferably within a range of 0.05 to 5 parts by mass, and more preferably within a range of 0.1 to 3 parts by mass, relative to the toner base particles.

[0218] 4. Physical properties of toner particles (Toner particle size) The average particle size of the toner particles is the volume-based median diameter (d 50 ) is preferably in the range of 3 to 15 μm, and more preferably in the range of 4 to 8 μm. If the average particle size of the toner particles is within this range, high reproducibility can be obtained even for extremely fine dot images at the 1200 dpi level. 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, etc.

[0219] The volume-based median diameter of the toner particles (d 50 For example, a measuring device consisting of a Beckman Coulter "Multisizer 3" connected to a computer system equipped with data processing software V3.51 can be used to measure . The successor to the "Multisizer 3," the "Multisizer IV," may also be used.

[0220] The average particle size of the toner particles can be measured, for example, as follows.

[0221] The measurement sample (toner) is added to a surfactant solution, and after being mixed, ultrasonic dispersion is performed to prepare a toner particle dispersion. Note that the surfactant solution may be, for example, a surfactant solution prepared by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing the toner particles.

[0222] The above toner particle dispersion is pipetted into a beaker containing ISOTON II (manufactured by Beckman Coulter) in a sample stand until the concentration indicated on the measuring device reaches 8%. By achieving this concentration, reproducible measurement values ​​can be obtained.

[0223] Next, in the measurement device, the number of particles measured was set to 25,000, the aperture diameter was set to 100 μm, and the measurement range of 2 to 60 μm was divided into 256 parts to calculate the frequency value. Then, the particle diameters of the 50% with the largest volume cumulative fraction were calculated as the volume-based median diameter (d 50 ) is obtained.

[0224] (Average circularity of toner particles) From the viewpoint of improving the stability of charging characteristics and low-temperature fixability, the toner particles preferably have an average circularity in the range of 0.930 to 1.000, more preferably in the range of 0.950 to 0.995.

[0225] If the average circularity is within the above range, the individual toner particles are less likely to be crushed, which can suppress contamination of the frictional charging member, stabilize the chargeability of the toner, and improve the quality of the formed image.

[0226] The average circularity of the toner particles can be measured using, for example, an FPIA-3000 (manufactured by Sysmex Corporation).

[0227] The average circularity of the toner particles is measured, for example, as follows.

[0228] The measurement sample (toner) is soaked in a surfactant-containing aqueous solution and dispersed by ultrasonic dispersion treatment for 1 minute. After that, images are taken using an FPIA-3000 (manufactured by Sysmex) under the measurement conditions of HPF (high magnification imaging) mode at an appropriate concentration of 3,000 to 10,000 HPF detection counts.

[0229] If the HPF detection number is within the above range, reproducible measurement values ​​can be obtained. From the photographed particle image, the circularity of each toner particle is calculated according to the following formula (I), and the average circularity is obtained by adding up the circularity of each toner particle and dividing the sum by the total number of toner particles. Formula (I): Circularity of toner particle = (perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)

[0230] 5. Each step in the image formation method The image forming method of the present invention is not particularly limited as long as it includes a step of forming an image on a recording medium using a toner for developing an electrostatic image. The image forming method may include, for example, the following steps (1) to (3):

[0231] (1) A process for producing toner for developing electrostatic images (2) A process of forming an image on a recording medium using a toner for developing an electrostatic image. (3) A process of winding up the recording medium on which the fixed image has been formed.

[0232] The image forming method will be described in detail below in the order of (1) to (3) above.

[0233] (5.1) A process for producing a toner for developing electrostatic images Examples of methods for producing the toner according to the present invention include kneading and pulverization, emulsion dispersion, suspension polymerization, dispersion polymerization, emulsion polymerization, emulsion polymerization aggregation, mini-emulsion polymerization aggregation, encapsulation, and other known methods.

[0234] Considering the need to obtain a toner with a small particle size in order to achieve high image quality, it is preferable to use the emulsion polymerization aggregation method from the viewpoints of production cost and production stability.

[0235] The emulsion polymerization aggregation method is a method for producing a toner by the following procedure.

[0236] A dispersion of fine particles made of a binder resin produced by emulsion polymerization is mixed with a dispersion of fine particles made of a colorant to prepare a mixed liquid. Hereinafter, "fine particles made of a binder resin" will also be referred to simply as "binder resin fine particles." Also, "fine particles made of a colorant" will also be referred to as "colorant fine particles."

[0237] Next, in the mixed solution, the particles are slowly aggregated while balancing the repulsive force of the particle surfaces by adjusting the pH and the coagulation force by adding an aggregating agent made of an electrolyte. Then, while controlling the average particle size and particle size distribution, the particles are aggregated, and at the same time, the particles are heated and stirred to fuse together and control the shape. This process is used to produce toner.

[0238] In the method for producing a toner, when an emulsion polymerization aggregation method is used, the binder resin particles formed can have a structure of two or more layers made of binder resins with different compositions. In this case, a method can be adopted in which a polymerization initiator and a polymerizable monomer are added to a dispersion of first binder resin particles prepared by a conventional emulsion polymerization treatment (first-stage polymerization), and this system is polymerized (second-stage polymerization).

[0239] The toner may also be configured as a core-shell structure, and the method for producing the toner having this core-shell structure is carried out by the following procedure.

[0240] Core particles are produced by associating, aggregating, and fusing core binder resin particles with colorant particles. Next, shell binder resin particles for forming a shell layer are added to the dispersion of core particles, and these shell binder resin particles are aggregated and fused to the surface of the core particles to form a shell layer that covers the surface of the core particles. This procedure allows the production of a toner with a core-shell structure.

[0241] When the toner has a core-shell structure, the manufacturing method thereof will be specifically explained below, divided into (1) to (9).

[0242] (1) a colorant particle dispersion preparation step of preparing a colorant particle dispersion in which a colorant is dispersed in the form of fine particles; (2-1) a core binder resin particle polymerization step of obtaining core binder resin particles containing a main wax and an internal additive, and preparing a dispersion thereof; (2-2) a step of polymerizing shell binder resin particles, in which shell binder resin particles made of a shell binder resin are obtained and a dispersion thereof is prepared; (3) an aggregation and fusion step in which core binder resin particles and colorant particles are aggregated and fused in an aqueous medium to form associated particles that will become core particles; (4) a first aging step in which the aggregated particles are aged by thermal energy to control the shape and obtain core particles; (5) a shell layer forming step of adding fine particles of a binder resin for forming a shell layer to a dispersion of core particles, and agglomerating and fusing the fine particles of the binder resin for the shell to the surface of the core particles to form particles having a core-shell structure; (6) a second aging step in which the particles with a core-shell structure are aged by thermal energy to control the shape and obtain toner particles with a core-shell structure; (7) A process of separating the cooled toner particle dispersion (aqueous medium) into solid and liquid toner particles, and then filtering and washing the toner particles to remove surfactants and the like. (8) A drying process is performed to dry the washed toner particles. If necessary, after the drying process, (9) An external additive treatment step may be added to the dried toner particles.

[0243] (1) Colorant particle dispersion preparation process In this step, a colorant is added to an aqueous medium and dispersed using a disperser, thereby preparing a dispersion of colorant particles in which the colorant is dispersed in the form of fine particles.

[0244] Specifically, the colorant dispersion treatment is carried out in an aqueous medium in which the surfactant concentration is adjusted to a critical micelle concentration (CMC) or higher.

[0245] The dispersing machine used for the dispersion treatment is not particularly limited, but preferred examples include pressure dispersing machines such as ultrasonic dispersing machines, mechanical homogenizers, Manton-Gaulin and pressure homogenizers, and media-type dispersing machines such as sand grinders, Getzmann mills and diamond fine mills.

[0246] The dispersed diameter of the colorant particles in this colorant particle dispersion is preferably within a range of 40 to 200 nm in terms of volume-based median diameter.

[0247] The volume-based median diameter of the colorant fine particles is measured using a "MICROTRAC UPA-150 (manufactured by HONEYWELL)" under the following measurement conditions.

[0248] <Measurement conditions> Sample refractive index 1.59 Sample specific gravity: 1.05 (spherical particle equivalent) Solvent refractive index 1.33 Solvent viscosity: 0.797 (30°C), 1.002 (20°C) Zero point adjustment: Ion-exchanged water was added to the measurement cell to adjust the zero point.

[0249] (2-1) Core binder resin particle polymerization process In this step, a polymerization treatment is carried out to prepare a dispersion of core binder resin particles, which are made of a core binder resin containing a main wax and internal additives.

[0250] In a preferred example of the polymerization treatment in this step, a polymerizable monomer solution containing a main wax and internal additives as necessary is added to an aqueous medium containing a surfactant at a critical micelle concentration (CMC) or less, mechanical energy is applied to form droplets, and then a water-soluble polymerization initiator is added to cause the polymerization reaction to proceed in the droplets.

[0251] The droplets may contain an oil-soluble polymerization initiator. In such a process, it is essential to apply mechanical energy to forcibly emulsify (form droplets).Means for applying such mechanical energy include means for applying strong stirring or ultrasonic vibration energy such as a homomixer, ultrasonic wave, or Manton-Gaulin mixer.

[0252] [Surfactant] Here, the surfactant used in the aqueous medium used during polymerization of the colorant particle dispersion and the core binder resin particles will be described.

[0253] Suitable surfactants include, but are not limited to, ionic surfactants such as sulfonates, sulfate ester salts, and fatty acid salts.

[0254] Examples of sulfonates include sodium dodecylbenzenesulfonate and sodium arylalkyl polyether sulfonate.

[0255] Examples of sulfate ester salts include sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, and sodium octyl sulfate.

[0256] Examples of fatty acid salts include sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, and calcium oleate.

[0257] As the surfactant, a nonionic surfactant can also be used. Examples of nonionic surfactants include polyethylene oxide, polypropylene oxide, and a combination of polypropylene oxide and polyethylene oxide. Other examples include esters of polyethylene glycol and higher fatty acids, and alkylphenol polyethylene oxide. Other examples include esters of higher fatty acids and polyethylene glycol, esters of higher fatty acids and polypropylene oxide, and sorbitan esters.

[0258] The polymerization initiator and chain transfer agent used in the step of polymerizing the core binder resin particles will be described below.

[0259] [Polymerization initiator] Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0260] Examples of the oil-soluble polymerization initiator include azo or diazo polymerization initiators such as 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile; peroxide polymerization initiators such as benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine; and polymer initiators having a peroxide in the side chain.

[0261] [Chain transfer agent] For the purpose of adjusting the molecular weight of the binder resin for the core to be obtained, a commonly used chain transfer agent can be used.

[0262] The chain transfer agent is not particularly limited, and examples thereof include n-octyl mercaptan and n-decyl mercaptan, mercaptans such as tert-dodecyl mercaptan, mercaptopropionic acid esters such as n-octyl-3-mercaptopropionic acid ester, terpinolene, and α-methylstyrene dimer.

[0263] (2-2) Shell binder resin particle polymerization process The particle size of the amorphous polyester can be controlled by changing the reaction conditions during polymerization when preparing the dispersion of the binder resin particles for the shell.

[0264] In this step, a polymerization treatment is carried out in the same manner as in the core binder resin particle polymerization step (2-1) above, to prepare a dispersion of shell binder resin particles made of a shell binder resin.

[0265] [Volume average particle size of resin particles] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably in the range of 0.01 to 1 μm, more preferably in the range of 0.08 to 0.8 μm, and even more preferably in the range of 0.1 to 0.6 μm. The volume average particle size of the resin particles can be measured using a laser diffraction particle size distribution analyzer.

[0266] An example of a laser diffraction particle size distribution analyzer is the "LA-700" (manufactured by Horiba, Ltd.). Using the particle size distribution obtained by measurement using the above-mentioned device, the cumulative distribution for the volume of the divided particle size range (channel) is calculated from the small particle size side. The particle size that is cumulatively 50% of all particles is then determined as the volume average particle size D 50 The volume average particle diameter of particles in other dispersions is measured in the same manner.

[0267] (3) Agglomeration / fusion process In this step, core binder resin particles and colorant particles are aggregated and fused in an aqueous medium to form associated particles that will become core particles.

[0268] The aggregation and fusion method in this step is preferably a salting-out / fusion method using the colorant microparticles obtained in the colorant microparticle dispersion preparation step (1) and the core binder resin microparticles obtained in the core binder resin microparticle polymerization step (2-1).

[0269] In the aggregation and fusion step, it is possible to aggregate and fuse wax particles and internal additive particles such as charge control agents together with the core binder resin particles and colorant particles.

[0270] Here, "salting out / fusion" refers to a process in which aggregation and fusion are carried out in parallel, and when the particles have grown to a desired particle size, an aggregation terminator is added to stop the particle growth, and further heating is continued as necessary to control the particle shape.

[0271] The salting out / fusion method is carried out as follows.

[0272] A salting-out agent consisting of an alkali metal salt, an alkaline earth metal salt, a trivalent salt, or the like is added as a flocculating agent at a critical flocculation concentration or higher to an aqueous medium containing core binder resin particles and colorant particles. Next, the medium is heated to a temperature higher than the glass transition point of the core binder resin particles and higher than the melting peak temperature of the core binder resin particles and the colorant particles, thereby promoting salting-out and simultaneously flocculating and fusing the particles.

[0273] Here, examples of the alkali metal salt and alkaline earth metal salt that serve as salting-out agents include lithium, potassium, sodium, etc. as alkali metals, and magnesium, calcium, strontium, barium, etc. as alkaline earth metals, with potassium, sodium, magnesium, calcium, and barium being preferred.

[0274] When the aggregation and fusion step is carried out by salting out / fusion, it is preferable to keep the time of leaving the mixture after adding the salting out agent as short as possible.

[0275] The reason for this is not clear, but depending on the time left after salting out, the state of particle aggregation changes, causing problems such as unstable particle size distribution and changes in the surface properties of the fused toner.

[0276] The temperature at which the salting-out agent is added must be at least equal to or lower than the glass transition point of the core binder resin particles.

[0277] The reason for this is that if the temperature at which the salting-out agent is added is equal to or higher than the glass transition point of the core binder resin particles, the salting-out / fusion of the core binder resin particles proceeds quickly, but the particle size cannot be controlled, resulting in problems such as the generation of large particles.

[0278] The temperature range for this addition may be any temperature below the glass transition point of the binder resin, but is generally within the range of 5 to 55°C, and preferably within the range of 10 to 45°C.

[0279] The salting-out agent is added at a temperature below the glass transition point of the core binder resin particles, and then the temperature is raised as quickly as possible to a temperature above the glass transition point of the core binder resin particles and above the melting peak temperature (°C) of the core binder resin particles and the colorant particles.

[0280] The time required for this temperature increase is preferably less than 1 hour. Furthermore, the temperature increase must be carried out quickly, and the temperature increase rate is preferably 0.25°C / min or more.

[0281] Although the upper limit is not particularly clear, if the temperature is increased instantaneously, salting out will proceed rapidly, making it difficult to control the particle size, and therefore a rate of 5°C / min or less is preferable.

[0282] By the above salting out / fusion method, a dispersion of core binder resin fine particles and associated particles (core particles) formed by salting out / fusion of optional fine particles is obtained.

[0283] Furthermore, the term "aqueous medium" refers to a medium consisting of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent.

[0284] Examples of water-soluble organic solvents include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, tetrahydrofuran, etc. Among these, alcohol-based organic solvents that do not dissolve the resin produced are preferred.

[0285] (4) First aging process In this step, the associated particles are aged by thermal energy. By controlling the heating temperature in (3) the aggregation and fusion step and especially the heating temperature and time in (4) the first aging step, it is possible to control the core particles so that they have a uniform particle size with a narrow particle size distribution and a smooth, uniform surface.

[0286] Specifically, (3) in the aggregation and fusion process, the heating temperature is lowered to suppress the progress of fusion between the core binder resin particles and promote uniformity, and in the first aging process, the heating temperature is lowered and the time is extended to control the surface of the core particles to have a uniform shape.

[0287] (5) Shell layer formation process In this process, a dispersion of shell binder resin particles is added to a dispersion of core particles to aggregate and fuse the shell binder resin particles onto the surface of the core particles, thereby coating the surface of the core particles with the shell binder resin particles, thereby forming particles with a core-shell structure.

[0288] This step is a preferable manufacturing condition for imparting both low-temperature fixability and heat-resistant storage stability. Furthermore, when a color image is formed, it is preferable to form this shell layer in order to obtain high color reproducibility for secondary colors.

[0289] Specifically, the dispersion of core particles is added to the dispersion of shell binder resin particles while maintaining the heating temperature in (3) the aggregation and fusion step and (4) the first aging step. Then, while continuing to heat and stir, the shell binder resin particles are slowly coated on the surfaces of the core particles over several hours to form particles with a core-shell structure. The heating and stirring time is preferably within the range of 1 to 7 hours, and particularly preferably within the range of 3 to 5 hours.

[0290] (6) The second aging process In this process, when the core-shell structured particles reach the specified particle size in the shell layer formation process (5), a terminator such as sodium chloride is added to stop particle growth, and the mixture is then heated and stirred for several hours to fuse the shell binder resin particles attached to the core particles.

[0291] The thickness of the layer of the binder resin particles for shell that covers the surface of the core particle is set within the range of 100 to 300 nm.

[0292] In this way, the shell binder resin particles are fixed to the surface of the core particles to form a shell layer, and rounded toner particles with a uniform core-shell structure are formed.

[0293] (7) Filtration and washing process In this step, first, the dispersion of toner particles is cooled, preferably at a cooling rate of 1 to 20° C. / min.

[0294] The cooling method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

[0295] Next, the toner particles are subjected to solid-liquid separation from the dispersion liquid of the toner particles that has been cooled to a predetermined temperature, and then a washing process is performed to remove any adhering substances such as surfactants and salting agents from the solid-liquid separated toner cake (a cake-like aggregate of toner particles in a wet state).

[0296] Here, the filtration method is not particularly limited, and may be a centrifugation method, a vacuum filtration method using a Nutsche or the like, a filtration method using a filter press or the like.

[0297] (8) Drying process In this step, the washed toner cake is dried. Examples of dryers that can be used in this step include a spray dryer, a vacuum freeze dryer, a reduced pressure dryer, etc., and it is preferable to use a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, a rotary dryer, an agitator dryer, etc.

[0298] The moisture content of the dried toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less.

[0299] In addition, when the dried toner particles are aggregated with each other due to a weak inter-particle attractive force, the aggregates may be subjected to a crushing treatment.

[0300] Here, as the crushing device, a mechanical crushing device such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

[0301] (9) External additive processing process In this step, an external additive is added to the toner particles that have been dried in the drying step (8).

[0302] The external additives can be added using a mechanical mixer such as a Henschel mixer or a coffee mill.

[0303] (5.2) A process of forming an image on a recording medium using a toner for developing an electrostatic image The toner for developing an electrostatic image used in this step is not particularly limited as long as it contains toner base particles containing a release agent. However, in the finally formed fixed image, the polar component γ of the surface energy of the image p But 5mN / m 2 or more, and the dispersion component γ of the surface energy of the image d But 20mN / m 2 It is necessary to ensure that this is the case.

[0304] In the triple-belt system, the influence of pressure exerted by the fixing belt on the surface of the fixed image during fixed image formation is smaller than in the double-belt system.

[0305] FIG. 3 is an example of a schematic cross-sectional view of peripheral members of a fixed image forming portion in a biaxial belt type image forming apparatus.

[0306] FIG. 4 is an example of a schematic cross-sectional view of peripheral members of a fixed image forming portion in a triaxial belt type image forming apparatus.

[0307] In Figures 3 and 4, "61" is the fixing belt, "62" is the heating roller, "63" is the fixing roller, "64" is the pressure roller, "65" is the tension roller, and "P" is the recording medium, and the arrows in the figures indicate the direction of pressure from the fixing roller on the recording medium.

[0308] In FIG. 3, a heating roller 62 functions as the “heating section” of the present invention, and a fixing belt 61 is stretched between the heating roller 62 and a fixing roller 63 .

[0309] In FIG. 4, a heating roller 62 functions as the “heating section” of the present invention, and a fixing belt 61 is stretched by the heating roller 62 , a fixing roller 63 and a tension roller 65 .

[0310] As shown in Figure 3, in the biaxial belt method, pressure is applied to the recording medium by firmly sandwiching it between the upper and lower rollers. In contrast, as shown in Figure 4, in the triaxial belt method, the recording medium is sandwiched between the upper and lower rollers with a slight offset, which applies pressure. Therefore, the pressure applied to the recording medium P is dispersed.

[0311] By dispersing the pressure in this way, for example, the amorphous polyester contained in the fixed image is less likely to be buried in the toner, and the area of ​​the amorphous polyester or styrene-acrylic resin exposed on the surface of the fixed image increases, thereby improving the applicability of the liquid to the fixed image and the adhesion between the liquid and the fixed image.

[0312] Therefore, in the process of forming an image on a recording medium using toner for developing an electrostatic image, it is preferable to use a fixing device of the triaxial belt type, from the viewpoint of dispersing the pressure applied to the recording medium during image formation.

[0313] An example of an image forming apparatus that employs a three-axis belt system is that shown in FIG. 1 of Japanese Patent Application Laid-Open No. 2021-131517.

[0314] (5.3) Step of winding up the recording medium on which the fixed image has been formed The process of forming an image on a recording medium using toner for developing an electrostatic image and the process of winding up the recording medium on which the fixed image has been formed are linked. When forming an image on a recording medium, transporting the recording medium while wound up in a roll rather than simply transporting the recording medium reduces minute wrinkles and the like due to the tension applied to the recording medium. For this reason, winding up the recording medium in a roll when forming an image on the recording medium distributes the pressure on the recording medium.

[0315] Therefore, after the step of forming an image on a recording medium using the toner for developing an electrostatic image, it is preferable that the recording medium is wound up in a roll, from the viewpoint of dispersing the pressure applied to the recording medium during image formation.

[0316] From the above, it can be seen that a rotary press, which sets rolled paper and forms images on it, is more suitable as an image forming apparatus to be used in the image forming method of the present invention than a sheet-fed press, which uses paper cut one sheet at a time.

[0317] Compared to sheet-fed presses, rotary presses are better at dispersing the pressure applied to the recording medium during image formation, so for example, the amorphous polyester on the surface of the fixed image is less likely to be buried in the toner, and the amount of styrene-acrylic resin exposed on the surface of the fixed image increases, improving the application of the liquid to the fixed image and also improving the adhesion of the liquid to the fixed image.

[0318] Figure 5 shows an example of the configuration of an image forming apparatus equipped with a system for winding up a recording medium into a roll. In Figure 5, "1" is a photosensitive member, "4" is a developing device, "7" is an intermediate transfer belt, "9" is a secondary transfer roller, "P" is a recording medium, "SC" is a document image reading device, "13" is a transport roller, and "50" is a fixing device. Also, "200" is an image forming apparatus, "201" is a storage unit, "202" and "203" are transport units, "204" is a storage unit, "205" is a winding roller, and "206" is a feeding roller.

[0319] The image forming apparatus 200 has a storage section 201 that stores a roll of recording medium P, a transport unit 202 that transports successive sheets of the recording medium P to the upstream portion of the paper feed transport device, and a transport unit 203 that transports the recording medium P on which a fixed image has been formed. The image forming apparatus 200 also has a storage section 204 that stores the recording medium P transported from the transport unit 203 in a roll.

[0320] An example of an image forming apparatus equipped with a method for winding up a recording medium into a roll as described above is that shown in FIG. 2 of Japanese Patent Application Laid-Open No. 2019-203964. [Example]

[0321] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

[0322] [Preparation of dispersion] As dispersions for producing toner, amorphous vinyl resin particle dispersions [SA1] to [SA6], crystalline polyester particle dispersion [CP1], amorphous polyester particle dispersions [AP1] to [AP7], and colorant particle dispersion [1] were prepared.

[0323] A. Preparation of amorphous vinyl resin particle dispersions [SA1] to [SA5] (A.1) Preparation of amorphous vinyl resin particle dispersion [SA1] (A.1.1) First stage polymerization A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water. While stirring at a stirring speed of 230 rpm under a nitrogen stream, the internal temperature of the reaction vessel was raised to 80°C. This yielded a mixed solution.

[0324] To the above mixed solution, an aqueous solution prepared by dissolving 10 parts by mass of potassium persulfate (KPS) in 200 parts by mass of ion-exchanged water was added, the temperature of the mixed solution was again raised to 80°C, and a monomer mixed solution 1 having the following composition was added dropwise thereto over 1 hour. <Monomer mixture 1> Styrene (St) 470 parts by mass n-Butyl acrylate (BA) 245 parts by mass Methacrylic acid (MAA) 67 parts by mass

[0325] Thereafter, polymerization was carried out by heating and stirring at 80° C. for 2 hours, thereby preparing a dispersion liquid [a1] of resin fine particles.

[0326] (A.1.2) Second stage polymerization A solution of 7 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 3,000 parts by mass of ion-exchanged water was placed in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device. After heating the solution to 80°C, 289 parts by mass of a dispersion liquid [a1] of resin fine particles and a monomer mixture liquid 2 prepared by dissolving a monomer and a release agent having the following composition at 90°C were added. <Monomer mixture 2> Styrene (St) 240 parts by mass 2-Ethylhexyl acrylate (2EHA) 94.7 parts by mass Methacrylic acid (MAA) 36 parts by mass n-Octyl-3-mercaptopropionate (NOM) 5.14 parts by mass Fischer-Tropsch wax (mold release agent) 7.50 parts by mass

[0327] The Fischer-Tropsch wax is a hydrocarbon wax with a melting point of 82°C.

[0328] The mixture was then mixed and dispersed for 30 minutes using a mechanical disperser "CLEARMIX" ("CLEARMIX" is a registered trademark of M Technique Co., Ltd.) equipped with a circulation path, to prepare an emulsified particle dispersion liquid [a2] containing emulsified particles (oil droplets). This allowed for the particle size control of the release agent contained in the emulsified particle dispersion liquid [a2], and the particle size of the release agent was found to be 150 nm.

[0329] The particle size of the release agent was measured by measuring the volume-based median diameter of the release agent particles in the dispersion liquid using a laser diffraction particle size distribution analyzer "LA-750" (manufactured by HORIBA).

[0330] Next, an initiator solution prepared by dissolving 5.1 parts by mass of potassium persulfate (KPS) in 200 parts by mass of ion-exchanged water was added to the emulsified particle dispersion liquid [a2], and polymerization was carried out by heating and stirring at 84°C for 1 hour, thereby preparing a resin particle dispersion liquid [a3].

[0331] (A.1.3) Third stage polymerization 400 parts by mass of ion-exchanged water was added to the dispersion liquid [a3] of resin fine particles and mixed thoroughly, and then a solution of 6.9 parts by mass of potassium persulfate (KPS) dissolved in 400 parts by mass of ion-exchanged water was added. Furthermore, at a temperature of 82°C, a monomer mixture liquid 3 having the following composition was added dropwise over one hour to obtain a dispersion liquid [a4]. <Monomer mixture 3> Styrene (St) 341 parts by mass n-Butyl acrylate (BA) 165.7 parts by mass Methacrylic acid (MAA) 48.6 parts by mass n-Octyl-3-mercaptopropionate (NOM) 9.1 parts by mass

[0332] The dispersion [a4] was then polymerized by heating and stirring for 2 hours, and then cooled to 28°C to prepare an amorphous vinyl resin microparticle dispersion [SA1] consisting of a vinyl resin (styrene-acrylic resin).

[0333] (A.2) Preparation of amorphous vinyl resin particle dispersion [SA2] An amorphous vinyl resin fine particle dispersion [SA2] was prepared in the same manner as in the preparation of the amorphous vinyl resin fine particle dispersion [SA1], except that in the second-stage polymerization, the release agent used was changed to behenic acid behenate, an ester wax with a melting point of 73°C.

[0334] (A.3) Preparation of amorphous vinyl resin particle dispersion [SA3] An amorphous vinyl resin microparticle dispersion [SA3] was prepared in the same manner as in the preparation of the amorphous vinyl resin microparticle dispersion [SA2], except that in the second-stage polymerization, mixing and dispersion was carried out for 10 minutes using "CLEARMIX" ("CLEARMIX" is a registered trademark of the company).

[0335] (A.4) Preparation of amorphous vinyl resin particle dispersion [SA4] An amorphous vinyl resin microparticle dispersion [SA4] was prepared in the same manner as in the preparation of the amorphous vinyl resin microparticle dispersion [SA2], except that in the second-stage polymerization, mixing and dispersion was carried out for 20 minutes using "CLEARMIX" ("CLEARMIX" is a registered trademark of the company).

[0336] (A.5) Preparation of amorphous vinyl resin particle dispersion [SA5] An amorphous vinyl resin microparticle dispersion [SA5] was prepared in the same manner as in the preparation of the amorphous vinyl resin microparticle dispersion [SA2], except that in the second polymerization step, mixing and dispersion was carried out for 18 minutes using "CLEARMIX" ("CLEARMIX" is a registered trademark of the company).

[0337] (A.6) Preparation of amorphous vinyl resin particle dispersion [SA6] In the second polymerization step for preparing the vinyl resin particle dispersion [SA4], two types of release agents were used, and the types and amounts of the release agents were changed as follows: Release agent (behenic acid behenate) 3.75 parts by mass Release agent (Fischer-Tropsch wax) 3.75 parts by mass

[0338] Except for the above, a vinyl resin particle dispersion [SA6] was prepared in the same manner as in the preparation of the amorphous vinyl resin particle dispersion [SA4].

[0339] (A.7) Preparation table for amorphous vinyl resin particle dispersion Table I shows the results of preparing amorphous vinyl resin particle dispersions [SA1] to [SA6].

[0340] [Table 1]

[0341] B. Preparation of crystalline polyester microparticle dispersion [CP1] The following monomers were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 190° C. to dissolve them. <Monomer> Tetradecanedioic acid 450 parts by mass 1,6-Hexanediol 266 parts by mass

[0342] Next, 0.8 parts by mass of Ti(OBu)4 was added as an esterification catalyst, the temperature was raised to 240°C, and the reaction was carried out at normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0343] Then, the mixture was cooled to 200°C and reacted under reduced pressure (20 kPa) for 1 hour to prepare a crystalline polyester (cp1).

[0344] Next, 100 parts by mass of the crystalline polyester [1] was dissolved in 400 parts by mass of ethyl acetate (manufactured by Kanto Chemical Co., Inc.), and mixed with 638 parts by mass of a 0.26% by mass sodium lauryl sulfate solution that had been prepared in advance to prepare a mixed solution [C1].

[0345] While stirring the mixed solution [C1], ultrasonic dispersion treatment was carried out for 30 minutes at V-LEVEL 300 μA using an ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho Co., Ltd.).

[0346] After that, the mixture was heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump V-700 (manufactured by BUCHI) to completely remove the ethyl acetate, thereby preparing a crystalline polyester microparticle dispersion liquid [CP1].

[0347] C. Preparation of amorphous polyester particle dispersions [AP1] to [AP7] (C.1) Preparation of amorphous polyester microparticle dispersion [AP1] A mixed solution of the following vinyl resin monomer, a monomer having a substituent reactive with both the amorphous polyester and the vinyl resin, and a polymerization initiator was placed in the dropping funnel α. <Monomers and polymerization initiators> Styrene 80.0 parts by mass n-Butyl acrylate 20.0 parts by mass Acrylic acid 10.0 parts by mass Di-t-butyl peroxide (polymerization initiator) 16.0 parts by mass

[0348] The following amorphous polyester monomer was placed in a four-neck flask β equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve it. <Amorphous polyester monomer> Bisphenol A ethylene oxide 2 mole adduct 50.2 parts by mass Bisphenol A propylene oxide 2 mole adduct 249.8 parts by mass Terephthalic acid 120.1 parts by mass Dodecenyl succinic acid 46.0 parts by mass

[0349] With stirring, the mixed liquid placed in the dropping funnel was added dropwise to the four-necked flask over 90 minutes, and after aging for 60 minutes, the unreacted monomer was removed under reduced pressure (8 kPa).

[0350] Thereafter, 0.4 parts by mass of Ti(OBu)4 was added as an esterification catalyst, the temperature was raised to 235°C, and the reaction was carried out under normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0351] The mixture was then cooled to 200°C and reacted under reduced pressure (20 kPa), after which the solvent was removed to produce an amorphous polyester [ap1].

[0352] 100 parts by mass of amorphous polyester [ap1] was dissolved in 400 parts by mass of ethyl acetate (Kanto Chemical Co., Ltd.) and mixed with 638 parts by mass of a 0.26% by mass sodium lauryl sulfate solution prepared in advance. While stirring the mixture, ultrasonic dispersion treatment was performed for 15 minutes at V-LEVEL 200 μA using an ultrasonic homogenizer US-150T (Nippon Seiki Seisakusho).

[0353] The mixture was then heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump V-700 (BUCHI) to completely remove the ethyl acetate, thereby preparing an amorphous polyester microparticle dispersion [AP1] with a solid content of 13.5% by mass. The amorphous polyester microparticles in the amorphous polyester microparticle dispersion [AP1] had a volume-based median diameter of 195 nm.

[0354] (C.2) Preparation of amorphous polyester microparticle dispersions [AP2] to [AP7] Amorphous polyester microparticle dispersions [AP2] to [AP7] were prepared in the same manner as in the preparation of amorphous polyester microparticle dispersion resin dispersion [AP1], except for the following changes (1) to (3). (1) The vinyl resin monomer, the monomer having a substituent reactive with both the amorphous polyester and the vinyl resin, and the polymerization initiator placed in dropping funnel α were changed as shown in Table II. In Table II, the vinyl resin monomer, the monomer having a substituent reactive with both the amorphous polyester and the vinyl resin, and the polymerization initiator placed in dropping funnel α are referred to as monomer mixture α. (2) The amorphous polyester monomers placed in the four-neck flask β were changed as shown in Table II. (3) The processing conditions of the ultrasonic homogenizer US-150T were changed as shown in Table III.

[0355] [Table 2]

[0356] [Table 3]

[0357] D. Preparation of colorant particle dispersion [1] A dispersion liquid [Cu1] was prepared by gradually adding 420 parts by mass of copper phthalocyanine (CI Pigment Blue 15:3) to a solution prepared by adding 90 parts by mass of sodium dodecyl sulfate to 1600 parts by mass of ion-exchanged water while stirring the solution.

[0358] Next, dispersion liquid [Cu1] was dispersed using a stirring device "Clearmix" (manufactured by M Technique Co., Ltd.) to prepare colorant particle dispersion liquid [1]. The colorant particle in colorant particle dispersion liquid [1] had a volume-based median diameter of 120 nm.

[0359] [Toner and developer production] [1] Preparation of Toner 1 [1-1] Preparation of toner base particles A dispersion [SA1] was prepared by adding 180 parts by mass (solid content equivalent) of an amorphous vinyl resin microparticle dispersion [SA1] and 2,000 parts by mass of ion-exchanged water to a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube. Next, a 5 mol / L aqueous solution of sodium hydroxide was added at room temperature (25°C) to adjust the pH of the dispersion [SA1] in the reaction vessel to 10.

[0360] Furthermore, 40 parts by mass (solids equivalent) of colorant particle dispersion liquid [1] was added, and an aqueous solution of 30 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water as a flocculant was added over 10 minutes at 30°C while stirring.

[0361] After leaving the system for 3 minutes, the system was heated to 80°C over 60 minutes. Once the temperature reached 80°C, 50 parts by mass (solids equivalent) of crystalline polyester microparticle dispersion [CP1] was added over 10 minutes, and the stirring speed was adjusted so that the particle size growth rate was 0.01 μm / min. The particles were allowed to grow until the volume-based median diameter measured with a Coulter Multisizer 3 (Coulter-Beckman) reached 4.0 μm.

[0362] Next, 68 parts by mass (solid content equivalent) of the amorphous polyester microparticle dispersion [AP1] was added over 30 minutes. When the supernatant of the reaction solution became transparent, an aqueous solution of 190 parts by mass of sodium chloride dissolved in 760 parts by mass of ion-exchanged water was added to stop the growth of particle size.

[0363] The mixture was further stirred at 80°C, and the average circularity of the toner particles was measured using an "FPIA-3000" measuring device (manufactured by Sysmex Corporation). The particles were allowed to fuse together until the average circularity reached 0.970, and then the mixture was cooled to 30°C.

[0364] Next, solid-liquid separation was performed, and the dehydrated toner cake was redispersed in ion-exchanged water and subjected to solid-liquid separation. This procedure was repeated three times to wash the toner cake, and then the cake was dried at 40°C for 24 hours to prepare toner base particles [1].

[0365] [1-2] External additive treatment To 100 parts by mass of toner base particles [1], 0.6 parts by mass of hydrophobic silica having a number average primary particle diameter of 12 nm and a hydrophobicity degree of 68, and 1.0 part by mass of hydrophobic titanium oxide having a number average primary particle diameter of 20 nm and a hydrophobicity degree of 63 were added as external additives. This external additive is referred to as external additive [1].

[0366] Then, the external additive [1] was mixed with the toner base particles [1] for 20 minutes at 32°C and a rotor peripheral speed of 35 m / sec in a "Henschel Mixer" (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) to carry out external additive treatment, and coarse particles were removed using a sieve with 45 μm openings to produce toner 1.

[0367] [2] Preparation of Toners 2 to 12 and 14 to 16 Toners 2 to 12 and 14 to 16 were prepared in the same manner as Toner 1, except that the amorphous vinyl resin microparticle dispersion, crystalline polyester microparticle dispersion, and amorphous polyester microparticle dispersion used were as shown in Table IV.

[0368] [3] Preparation of Toner 13 Regarding Toner 13, the structure was confirmed by transmission electron microscopy (TEM), and it was found that no core-shell structure was formed.

[0369] [4] Measurement of resin particle size The particle sizes of the crystalline polyester and amorphous polyester in Table IV were measured using the respective resin particle dispersions with a laser diffraction particle size distribution analyzer "LA-700" (manufactured by Horiba, Ltd.).

[0370] [Table 4]

[0371] [5] Preparation of developer A ferrite carrier with a volume average particle diameter of 30 μm coated with a copolymer resin of cyclohexyl methacrylate and methyl methacrylate (monomer mass ratio = 1:1) was used. Developers 1 to 16 were prepared by mixing the ferrite carrier with the toner so that the toner concentration was 6 mass%.

[0372] Table V shows the composition of each developer.

[0373] [Table 5]

[0374] [Image formation evaluation] <1> Image formation <1-1> Image formation (1) The image forming device used was a commercially available full-color multifunction printer "AccurioPress C3080" manufactured by Konica Minolta. Hereinafter, this image forming device will be referred to as the sheet-fed press [1]. The image forming method of this sheet-fed press [1] is a biaxial belt method.

[0375] Load the developer [1] into the sheet-fed press [1], and print A4 size (basis weight 157 g / m) in a normal temperature and humidity environment (temperature 20°C, humidity 50% RH). 2 ) Gloss coated paper, toner adhesion amount 8.0 g / m 2 A solid image was formed at a fixing temperature of 180°C.

[0376] <1-2> Formation of images [2] to

[10] The above-mentioned sheet-fed press [1] was used as the image forming apparatus.

[0377] Images [2] to

[10] were formed in the same manner as image [1], except that developers [2] to

[10] were loaded in the sheet-fed press [1] in the order shown in Table VI.

[0378] <1-3> Image formation (11) The image forming device used was a commercially available color multifunction printer "bizhub PRESS C1100" manufactured by Konica Minolta. Hereinafter, this image forming device will be referred to as the sheet-fed press [2]. The image forming method of this sheet-fed press [2] is a triaxial belt method.

[0379] The developer

[11] was loaded into a sheet-fed press [2] that had been modified so that the temperature of the fixing roller could be set, as shown in Table VI, and A4 size paper (basis weight 157 g / m) was printed under normal temperature and humidity (temperature 20°C, humidity 50% RH) conditions. 2 ) Gloss coated paper, toner adhesion amount 8.0 g / m 2 A solid image was formed at a fixing temperature of 180°C.

[0380] <1-4> Image

[12] formation The image forming device used was a commercially available color multifunction printer "bizhub PRESS C71cf" manufactured by Konica Minolta. Hereinafter, this image forming device will be referred to as the rotary press [1]. The image forming method of the rotary press [1] uses a three-axis belt system.

[0381] In the rotary press [1], the recording medium is unwound from a roll and transported through the image forming device. After a toner image is formed on the recording medium, it is rolled up again. In this way, the recording medium set in the rotary press [1] is placed in a roll, and after a toner image is printed on the recording medium, it is rolled up again and stored.

[0382] The developer

[12] was loaded into the rotary press [1] as shown in Table VI, and the developer was printed on a 96 μm thick tack PP sheet at a toner adhesion rate of 8 g / m2 under normal temperature and humidity conditions (temperature 20°C, humidity 50% RH). 2 The fixing temperature, toner adhesion amount, and system speed were modified so that they could be freely set, and images were formed at a fixing temperature of 185° C. and a system speed of 270 mm / sec.

[0383] <1-5> Image formation (13) Developer 13 was made from toner 13 that did not have a core-shell structure, and therefore no image was formed.

[0384] <1-6> Image formation (14) to (16) The above-mentioned sheet-fed press [1] was used as the image forming apparatus.

[0385] Images

[14] to

[16] were formed in the same manner as image [1], except that developers

[14] to

[16] were loaded in the sheet-fed press [1] in the order shown in Table VI.

[0386] <1-7> Measurement of surface energy The prepared images [1] to

[12] and

[14] to

[16] were coated with water, diiodomethane, and n-hexadecane as liquids, respectively. The contact angles of the fixed images were measured for each liquid using a fully automatic contact angle meter "DMo-701" manufactured by Kyowa Interface Science Co., Ltd., and the surface energy components of each image were calculated based on the measurement results for each liquid using the Kitazaki-Hata theoretical formula. The calculation results are shown in Table VI.

[0387] <2> Fixation and separation evaluation When images [1] to

[12] and

[14] to

[16] were produced, the fixation separation between the heat fixing roller on the image side and the recording medium was evaluated according to the following evaluation criteria. A rating of "A" or "B" was deemed acceptable for practical use and was considered to be acceptable. The evaluation results are shown in Table VI.

[0388] (Evaluation criteria) A: The recording medium separates from the heat fixing roller without curling. B: The recording medium is separated from the heat fixing roller, but the leading edge of the recording medium curls slightly. C: The recording medium is separated from the heat fixing roller, but uneven gloss is observed on the image surface, or the recording medium is wrapped around the heat fixing roller and cannot be separated from the heat fixing roller.

[0389] <3> Varnish application and adhesion evaluation <3-1> Formation of varnish layer On the prepared images [1] to

[12] and

[14] to

[16] , T&K's "UV VECTA Coat Varnish PC-3KW2" was applied using a bar coater to a thickness of 5 μm.

[0390] Then, a high-pressure mercury lamp is used to measure the integrated light intensity of each image plane at 120-130 mJ / cm 2 The varnish was cured by irradiating it with ultraviolet light so that a varnish layer was formed on the images [1] to

[12] and

[14] to

[16] .

[0391] <3-2> Evaluation of varnish application The surfaces of images [1] to

[12] and

[14] to

[16] on which the varnish layer was formed were visually observed, and the varnish applicability was evaluated based on the presence or absence of repellency according to the following evaluation criteria. Cases where the evaluation criteria were "A," "B," or "C" were deemed to be acceptable for practical use and were considered to have passed. The evaluation results are shown in Table VI.

[0392] (Evaluation criteria) A: There are no pinholes within a 10cm x 10cm area. B: There are 1 to 2 tiny pinholes within an area of ​​10 cm x 10 cm. C: There are 3 to 10 tiny pinholes within a 10 cm x 10 cm area. D: There are 11 or more pinholes or pinholes in a 10cm x 10cm area.

[0393] <3-3> Varnish adhesion evaluation For images [1] to

[12] and

[14] to

[16] on which a varnish layer was formed, the varnish adhesion rate was calculated using the mending tape peeling method according to the following steps (1) to (6).

[0394] (1) Regarding the images, photographs are taken at a magnification of 100x using a digital microscope "VHX-6000" manufactured by Keyence Corporation, and binarized using "LUSEX-AP" manufactured by Nireco Corporation. (2) Lightly attach "Mending Tape" (No. 810-3-12) manufactured by Sumitomo 3M to the image. (3) Rub the tape back and forth 3.5 times with a pressure of 1 kPa. (4) Peel off the tape at a 180-degree angle with 200g of force. (5) After the tape is removed, a photograph is taken at 100x magnification using a Keyence digital microscope "VHX-6000" and then binarized using Nireco Corporation's "LUSEX-AP." (6) Calculate the varnish adhesion rate using the following formula. Varnish adhesion rate [%] = (1 - area of ​​the concealed area relative to the image area of ​​the varnish after tape removal) / area of ​​the concealed area relative to the resin image area by powder before tape removal) × 100

[0395] The adhesion between the varnish layer and each image, i.e., varnish adhesion, was evaluated based on the following evaluation criteria. Evaluation criteria of "A," "B," and "C" were deemed acceptable for practical use and were considered to be acceptable. The evaluation results are shown in Table VI.

[0396] (Evaluation criteria) A: There is no peeling of the varnish. B: The varnish adhesion rate [%] is less than 3%. C: The varnish adhesion rate [%] is 3% or more and less than 5%. D: The varnish adhesion rate [%] is 5% or more and less than 10%. E: The varnish adhesion rate [%] is 10% or more.

[0397] <4> Laminate Adhesion <4-1> Formation of protective layer A 35 μm thick overlaminate film "3210G" manufactured by ARLON was laminated over the entire surface of each image using a laminator "RS685HC" manufactured by Japan Office Laminator Co., Ltd., at a speed of 6 m / min, forming a protective layer for each image.

[0398] <4-2> Laminate adhesion evaluation The adhesion between each image on which a protective layer was formed by lamination and the laminate, i.e., the lamination adhesion, was evaluated by calculating the area ratio of the image peeled off by lamination using a cross-cut tape peeling method and using the following evaluation criteria. Cases with evaluation criteria of "A," "B," and "C" were deemed to be acceptable for practical use and were considered to be acceptable. The evaluation results are shown in Table VI.

[0399] (Evaluation criteria) A: No peeling due to lamination. B: The area of ​​the toner image peeled off by lamination is less than 3% of the area of ​​the solid image. C: The area of ​​the toner image peeled off by lamination is 3% or more and less than 5% of the area of ​​the solid image. D: The area of ​​the toner image peeled off by lamination is 5% or more and less than 10% of the area of ​​the solid image. E: The area of ​​the toner image peeled off by lamination is 10% or more of the area of ​​the solid image.

[0400] [Table 6]

[0401] <5> Overall Review As is clear from Table VI, the Examples are superior to the Comparative Examples in terms of fixation separation properties, varnish application properties, varnish adhesion properties, and lamination adhesion properties.

[0402] While embodiments of the present invention have been described and illustrated in detail above, the disclosed embodiments are made for purposes of illustration and example only, and not limitation, and the scope of the invention should be construed in terms of the appended claims. [Explanation of symbols]

[0403] 1 photoreceptor 4. Developing device 7 Intermediate transfer belt 9 Secondary transfer roller 13 Transport roller 50 Fixing device 61 Fixing belt 62 Heating roller 63 Fuser roller 64 Pressure Roller 65 Tension Roller 200 Image forming device 201 Storage Unit 202, 203 Transport unit 204 Storage area 205 Winding roller 206 Feed roller T1 Conventional toner base particles T2 Toner base particles according to the present invention C core particle WAX Apes amorphous polyester Cpes crystalline polyester StAc styrene-acrylic resin SC Document Image Reader P Recording medium TP1 Conventional fixed image TP2 Fixed image according to the present invention

Claims

1. 1. An image forming method having a step of forming an image on a recording medium using a toner for developing an electrostatic image, the toner for developing an electrostatic image contains toner base particles containing a release agent, The polar component γ of the surface energy of the image ｐ 5mN / m ２ And, The dispersion component γ of the surface energy of the image ｄ , but 20 mN / m ２ That's all An image forming method comprising:

2. The polar component γ of the surface energy of the image ｐ , but 30 mN / m ２ is less than or equal to, and The dispersion component γ of the surface energy of the image ｄ , but 30 mN / m ２ is 2. The image forming method according to claim 1.

3. the toner base particles contain a crystalline polyester, The content of the crystalline polyester is in the range of 0.5 to 3.0% by mass.

2. The image forming method according to claim 1.

4. The toner base particles contain at least an ester wax as the releasing agent.

2. The image forming method according to claim 1.

5. In a process of forming an image on a recording medium using a toner for developing an electrostatic image, Uses a three-axis belt type fixing device 2. The image forming method according to claim 1.

6. After forming an image on a recording medium using the toner for developing an electrostatic image, The recording medium is wound into a roll.

2. The image forming method according to claim 1.

Images