Toner and two-component developer

Abstract

The present invention provides a toner and a two-component developer that exhibit excellent low-temperature fixing properties, in that they can form images with superior bending strength while suppressing the occurrence of low-temperature offset when fixed at low temperatures, and also have sufficient heat resistance for storage. [Solution] The toner has the following configuration in which an external additive is attached to the surface of toner particles. The toner particles contain an amorphous polyester resin, a crystalline polyester resin, a release agent, and a first fatty acid metal salt. The first fatty acid metal salt contains metal ions of trivalent or higher. The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. The external additive contains a second fatty acid metal salt.

Description

[Technical Field]

[0001] This disclosure relates to toner and two-component developer. [Background technology]

[0002] Toner used in image forming devices such as photocopiers, multifunction printers, printers, and facsimile machines that utilize the electrophotographic method (toner for electrostatic image development) generally has a structure in which an external additive is attached to the surface of toner particles (toner core).

[0003] For example, Patent Document 1 discloses a toner having toner particles containing a crystalline polyester resin, an amorphous polyester resin, a higher fatty acid metal salt, and a colorant, wherein the crystalline polyester resin has a crystal nucleating agent site at the end of its molecular chain and is within a predetermined SP value range, the crystal nucleating agent site is a site derived from a predetermined aliphatic monoalcohol and / or aliphatic monocarboxylic acid, the number of carbon atoms in the higher fatty acid metal salt is within a predetermined range, and the higher fatty acid metal salt is a metal salt with a valency of 2 or higher (i.e., the valency of the metal ion is 2 or higher). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2015-118310 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Toner used in image forming machines is required to have smaller particle sizes in order to reduce toner consumption and improve toner's low-temperature fixing properties. Improving the low-temperature fixing properties of toner can reduce power consumption in image forming machines.

[0006] When using small-particle toner to form an image on a recording sheet (e.g., recording paper) with low toner consumption, the toner layer formed by the toner fixing on the recording sheet becomes thin. Therefore, it becomes necessary to increase the concentration of the colorant (e.g., pigment concentration) in the toner to ensure image density.

[0007] However, when toner is fixed at low temperatures, the higher the concentration of colorants in the toner, the more prone the image formed as a toner layer becomes to crack, starting from the colorants. This leads to a problem where the image's strength against bending of the recording sheet (hereinafter also referred to as "bending strength") decreases. If the bending strength of the formed image is insufficient, the toner cannot be fixed at low temperatures. Therefore, as the concentration of colorants in the toner increases, the low-temperature fixing performance decreases as a result.

[0008] The toner and two-component developer of this disclosure were discovered in view of these circumstances, and the main objective is to provide a toner and two-component developer that have excellent low-temperature fixing properties in that they can form an image with excellent bending strength while suppressing the occurrence of low-temperature offset when fixed at low temperatures, and that also have sufficient heat resistance for storage. [Means for solving the problem]

[0009] To solve the above problems, the toner of this disclosure is a toner in which an external additive is attached to the surface of toner particles, wherein the toner particles include an amorphous polyester resin, a crystalline polyester resin, a release agent, and a first fatty acid metal salt, the first fatty acid metal salt is a metal salt of trivalent or higher, the average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less, and the external additive includes a second fatty acid metal salt.

[0010] In the above-mentioned toner, it is preferable that the toner surface exposure rate of the first fatty acid metal salt, calculated as the area ratio of the first fatty acid metal salt to the surface of the toner particles, is 1% or more and 5% or less.

[0011] Also, in the above toner, the content of the first fatty acid metal salt in the toner particles is preferably 0.5% by mass or more and 2.0% by mass or less.

[0012] Also, in the above toner, let the content of the crystalline polyester resin in the toner particles be M C % by mass, and let the content of the first fatty acid metal salt in the toner particles be M TF % by mass. Then, it is preferable to satisfy the relationship of the following formula (1). 2 ≤ M C / M TF ≤ 10 ···(1)

[0013] Also, in the above toner, the average particle diameter of the second fatty acid metal salt is preferably 0.5 μm or more and 1.5 μm or less.

[0014] Also, in the above toner, the content of the second fatty acid metal salt is preferably 0.1 part by mass or more and 0.5 part by mass or less with respect to 100 parts by mass of the toner particles.

[0015] Also, in the above toner, the adhesion strength of the second fatty acid metal salt to the toner particles is preferably 20% or more.

[0016] Also, in the above toner, the first fatty acid metal salt preferably has a hydroxy group.

[0017] The two-component developer of the present disclosure made to solve the above problems includes the above toner and a carrier.

Effect of the Invention

[0018] According to the toner and the two-component developer of the present disclosure, when fixing at a low temperature, it is excellent in low-temperature fixing properties in that it can form an image excellent in bending strength while suppressing the occurrence of low-temperature offset, and has excellent effects such as sufficient heat-resistant storage properties.

Brief Description of the Drawings

[0019] [Figure 1] This is a schematic cross-sectional view showing a toner according to one embodiment of the present disclosure. [Figure 2] This is a schematic cross-sectional view showing the interface between adjacent toner particles during the fixing of toner according to one embodiment of the present disclosure. [Figure 3] This diagram shows the procedure for evaluating bending strength when assessing low-temperature fixability. [Figure 4] Figure 3 is an enlarged view of the dashed line area, illustrating the case where there is no peeling of the toner layer. [Figure 5] Figure 3 is an enlarged view of the dashed line area, illustrating an example where the toner layer is peeling off. [Modes for carrying out the invention]

[0020] The toner and two-component developer of this disclosure will be described below. In this disclosure, "internal addition" means adding the additive so that it is contained inside the material to be added, and "external addition" means adding the additive so that it adheres to the outer surface (surface) of the material to be added.

[0021] 1. Toner configuration The toner according to this embodiment is a toner in which an external additive is attached to the surface of toner particles, and satisfies the following requirements (A) to (D). (A) The toner particles include an amorphous polyester resin, a crystalline polyester resin, a release agent, and a first fatty acid metal salt. (B) The first fatty acid metal salt is a metal salt with a valency of 3 or higher. (C) The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. (D) The external additive contains a metal salt of the second fatty acid.

[0022] Figure 1 is a schematic cross-sectional view showing a toner 1 according to one embodiment of the present disclosure. Using Figure 1, the toner particles 10 of the toner 1 have a structure in which a crystalline polyester resin 12, a release agent 13, a colorant 14, and a first fatty acid metal salt 15 are dispersed in an amorphous polyester resin 11 as a binder resin. In addition, a second fatty acid metal salt 16 is attached to the surface of the toner particles 10.

[0023] Thus, the first fatty acid metal salt 15 is internally added to the toner particles 10, and the second fatty acid metal salt 16 is externally added to the toner particles 10. The toner 1 may contain other optional components as long as they do not impair the effects relating to this disclosure.

[0024] Here, we will explain the estimated mechanism by which the toner according to this embodiment exhibits the effect of "having excellent low-temperature fixability in that it can form an image with excellent bending strength while suppressing the occurrence of low-temperature offset when fixed at low temperatures, and also having sufficient heat resistance for storage."

[0025] In the toner particles 10, the miscible regions (for example, the peripheral region of reference numeral 12 in Figure 1) where a portion of the crystalline polyester resin 12 is miscible with the amorphous polyester resin 11 contain a large amount of long-chain fatty acid components. Fatty acid metal salts are composed of a central metal ion and fatty acid components.

[0026] The fatty acid component of the first fatty acid metal salt 15 added to the toner particles 10 blends well with the areas in the crystalline polyester resin 12 where long-chain fatty acid components are abundant, i.e., the compatible areas. Therefore, the first fatty acid metal salt 15 is well dispersed in the toner particles 10 via the crystalline polyester resin 12 and is present without bias. This prevents the deterioration of the toner's heat resistance during storage caused by the addition of the first fatty acid metal salt 15 to the toner particles 10.

[0027] The metal ions in the first fatty acid metal salt 15 interact with the colorant 14 (pigment as a colorant), and the crystalline polyester resin 12 interacts with the amorphous polyester resin 11. Therefore, the interaction between the metal ions in the first fatty acid metal salt 15 and the colorant 14, the interaction between the fatty acid components in the first fatty acid metal salt 15 and the long-chain fatty acid components in the crystalline polyester resin 12, and the interaction between the crystalline polyester resin 12 and the amorphous polyester resin 11 combine to enhance the interaction between the colorant 14 and the amorphous polyester resin 11 via the first fatty acid metal salt 15 and the crystalline polyester resin 12. As a result, peeling is less likely to occur at the interface between the colorant 14 and the amorphous polyester resin 11 in the toner particles 10, and the strength of the image formed by the fixing of the toner 1 can be increased. In other words, the bending strength of the image can be increased, and a toner with excellent low-temperature fixing properties can be realized.

[0028] These effects are obtained when the first fatty acid metal salt 15 is dispersed in the toner particles 10 at an appropriate size. Specifically, if the average dispersion diameter of the first fatty acid metal salt 15 is larger than 500 nm, the interaction between the colorant 14 and the amorphous polyester resin 11 may become insufficient. Conversely, if the average dispersion diameter of the first fatty acid metal salt 15 is smaller than 50 nm, the average dispersion diameter of the crystalline polyester resin 12 also becomes smaller, resulting in a state where the compatibility between the amorphous polyester resin 11 and the crystalline polyester resin 12 is too high. In such a state, the heat resistance and storage properties of the toner deteriorate.

[0029] Figure 2 is a schematic cross-sectional view showing the interface of adjacent toner particles 10 during the fixing of toner 1 according to one embodiment of the present disclosure. Because toner 1 contains a second fatty acid metal salt 16 (a fatty acid metal salt as an external additive), the second fatty acid metal salt 16 is located at the interface of adjacent toner particles 10 during the fixing of toner 1.

[0030] When toner contains fatty acid metal salts as an external additive, the fatty acid metal salts typically absorb heat during toner fixing due to an endothermic peak derived from their crystalline properties, thus worsening low-temperature fixing performance.

[0031] In contrast, the toner 1 according to this embodiment contains a first fatty acid metal salt 15, which is a metal salt of trivalent or higher, and a crystalline polyester resin 12 as internal additives. As a result, the second fatty acid metal salt 16 present between adjacent toner particles 10 during toner fixing exhibits the same effect as the first fatty acid metal salt 15 exhibits within the toner particles 10. This enhances the cohesive force between the toner particles 10.

[0032] Specifically, the metal ions in the second fatty acid metal salt 16 interact with the colorant 14 (pigment as a colorant) and the metal ions in the first fatty acid metal salt 15 in the toner particles 10. In addition, the fatty acid components in the second fatty acid metal salt 16 are compatible with the long-chain fatty acid components of the crystalline polyester resin 12 and the fatty acid components in the first fatty acid metal salt 15 in the toner particles 10. As a result, the second fatty acid metal salt 16 present at the interface of adjacent toner particles 10 exerts an effect that enhances the cohesive force between the toner particles 10.

[0033] Based on the estimated mechanism described above, by using a toner composition that includes both the first fatty acid metal salt 15 (a fatty acid metal salt as an internal additive) and the second fatty acid metal salt 16 (a fatty acid metal salt as an external additive), the cohesive force within the toner particles 10 and between the toner particles 10 can be increased. In other words, the cohesive force of the entire toner layer formed by the fixing of toner 1 can be increased. That is, an image with excellent bending strength can be formed.

[0034] Next, the toner particles and their constituent components according to this embodiment will be described.

[0035] 2. Toner particles (toner core) The toner particles contain an amorphous polyester resin as a binder resin and an internal additive. The internal additive is dispersed in the binder resin. An external additive adheres to the surface of the toner particles. The volume average particle size of the toner particles according to this embodiment can be appropriately selected depending on the purpose, but as described above, this disclosure solves the problems that arise when using small particle size toner, so it is preferably 4 μm to 10 μm, and more preferably 5 μm to 8 μm.

[0036] The following describes each component of the toner according to this embodiment.

[0037] <Polyester resin> The toner particles according to this embodiment include at least an amorphous polyester resin and a crystalline polyester resin as binder resins. The crystalline polyester resin can lower the softening temperature and melt viscosity of the toner, and when used in combination with the amorphous polyester resin, it can improve the low-temperature fixing properties of the toner. Furthermore, if the amorphous polyester resin and the crystalline polyester resin used in combination originate from different raw materials, specifically if the main components of the dicarboxylic acid monomer and polyhydric alcohol are different, the compatibility of the two resins can be suppressed more reliably, and a greater improvement in low-temperature fixing properties can be expected. However, by suppressing the compatibility of the two resins, the crystalline polyester resin becomes more easily detached from the amorphous polyester resin and more easily immobilized on the developing roller together with the filler components.

[0038] In this disclosure, amorphous polyester resins and crystalline polyester resins are distinguished by their crystallinity index. Resins with a crystallinity index of 0.6 or more and 1.5 or less are defined as crystalline polyester resins, and resins with a crystallinity index of less than 0.6 or greater than 1.5 are defined as amorphous polyester resins. Resins with a crystallinity index greater than 1.5 are amorphous, and resins with a crystallinity index less than 0.6 have low crystallinity and a large amorphous portion.

[0039] The crystallinity index is a physical property that indicates the degree of crystallization of a resin, and is defined by the ratio of the softening temperature to the highest endothermic peak temperature (softening temperature / highest endothermic peak temperature). Here, the highest endothermic peak temperature refers to the temperature of the highest-temperature peak among the observed endothermic peaks. In crystalline polyester resins, the highest peak temperature is defined as the melting temperature (melting point, Tmp), and in amorphous polyester resins, the highest-temperature peak is defined as the glass transition temperature (Tg).

[0040] The degree of crystallization of the resin can be controlled by adjusting the type and ratio of monomers used as raw materials, as well as the manufacturing conditions (e.g., reaction temperature, reaction time, cooling rate).

[0041] -Amorphous polyester resin- The amorphous polyester resin contained in the toner particles according to this embodiment can be obtained, for example, by a polycondensation reaction between a carboxylic acid monomer mainly composed of terephthalic acid or isophthalic acid and a polyhydric alcohol mainly composed of ethylene glycol.

[0042] The reaction conditions are the same as those for the production of ordinary polyester resins. For example, amorphous polyester resin can be obtained by reacting a dicarboxylic acid monomer with a polyhydric alcohol in a nitrogen gas atmosphere at 190°C to 240°C, optionally in the presence of an esterification catalyst. The reaction ratio of the polyhydric alcohol to the carboxylic acid monomer is preferably 1.3:1 to 1:1.2 in terms of the equivalent ratio of hydroxyl groups to carboxyl groups [OH]:[COOH].

[0043] The dicarboxylic acid monomer used in the synthesis of amorphous polyester resin mainly contains terephthalic acid or isophthalic acid. Here, the molar content of terephthalic acid or isophthalic acid in the dicarboxylic acid monomer is preferably 70% to 100%, and more preferably 80% to 100%.

[0044] Furthermore, the above-mentioned dicarboxylic acid monomer may also include aromatic dicarboxylic acids other than terephthalic acid and isophthalic acid, or aliphatic dicarboxylic acids. Examples of aromatic dicarboxylic acids other than terephthalic acid and isophthalic acid include fumaric acid, and examples of aliphatic dicarboxylic acids include adipic acid, sebacic acid, succinic acid, etc. The above-mentioned dicarboxylic acid monomer may also include ester-forming derivatives of terephthalic acid or isophthalic acid, ester-forming derivatives of aromatic dicarboxylic acids other than terephthalic acid and isophthalic acid, ester-forming derivatives of aliphatic dicarboxylic acids, etc. In this disclosure, ester-forming derivatives include acid anhydrides of carboxylic acids, alkyl esters, etc. These dicarboxylic acid monomers may be used individually or in combination of two or more.

[0045] In the synthesis of amorphous polyester resins, a polycarboxylic acid monomer with a valency of 3 or higher may be used in conjunction with the dicarboxylic acid monomer mentioned above. Examples of polycarboxylic acid monomers with a valency of 3 or higher include trimellitic acid, pyromellitic acid, and their ester-forming derivatives. These polycarboxylic acid monomers with a valency of 3 or higher may be used individually or in combination of two or more.

[0046] The diol monomer used in the synthesis of amorphous polyester resin contains ethylene glycol as its main component. Here, the molar content of ethylene glycol in the diol monomer is preferably 70% to 100%, and more preferably 80% to 100%.

[0047] The above-mentioned diol monomer may include 1,3-propylene glycol, 1,4-butanediol, etc. These diol monomers may be used individually or in combination of two or more.

[0048] Amorphous polyester resins are preferably configured to have a glass transition temperature (Tg) of 50°C to 70°C, from the viewpoint of toner fixation, storage, and durability. If the glass transition temperature falls outside this range, the balance between toner fixation, storage, and durability may be disrupted.

[0049] Furthermore, amorphous polyester resins preferably have a softening temperature (Tm) of 100°C to 150°C, from the viewpoint of achieving both low-temperature fixing properties and hot-off resistance of the toner. If the softening temperature falls outside this range, the balance between low-temperature fixing properties and hot-off resistance of the toner may be disrupted.

[0050] From the viewpoint of achieving both heat resistance and low-temperature fixation properties of the toner, amorphous polyester resins are preferably found to have a peak-top molecular weight (Mp) of 3000 to 10500. If the peak-top molecular weight falls outside this range, the balance between the heat resistance and low-temperature fixation properties of the toner may be disrupted.

[0051] Here, peak-top molecular weight (Mp) refers to the molecular weight that shows the highest peak height of the THF-soluble component in gel permeation chromatography (GPC) using tetrahydrofuran (THF) as the mobile phase and polystyrene as the standard substance.

[0052] Furthermore, the amorphous polyester resin preferably has an acid value of 0 mg KOH or more and 60 mg KOH / g or less from the viewpoint of the toner's electrostatic properties, and a hydroxyl value of 0 mg KOH / g or more and 50 mg KOH / g or less from the viewpoint of the toner's hot offset resistance. If the acid value exceeds 60 mg KOH / g, the toner's electrostatic properties may deteriorate, and if the hydroxyl value exceeds 50 mg KOH / g, the toner's hot offset resistance may become insufficient.

[0053] Amorphous polyester resins preferably have an SP value (solubility parameter) of 10.5 to 12.5. If the SP value is less than 10.5, the compatibility with crystalline polyester resins may progress too much, impairing the toner's blocking resistance and hot offset resistance. On the other hand, if the SP value exceeds 12.5, the compatibility with crystalline polyester resins may decrease too much, resulting in insufficient low-temperature fixation.

[0054] -Crystalline polyester resin- In the toner particles according to this embodiment, the crystalline polyester resin is dispersed in the amorphous polyester resin. The crystalline polyester resin is preferably composed of linear saturated aliphatic polyester units obtained by polycondensation of a carboxylic acid monomer mainly containing an aliphatic dicarboxylic acid having 9 to 22 carbon atoms and a polyhydric alcohol mainly containing an aliphatic diol having 2 to 10 carbon atoms.

[0055] The reaction conditions are the same as those for the production of ordinary polyester resins. For example, a crystalline polyester resin can be obtained by reacting a carboxylic acid monomer with a polyhydric alcohol in a nitrogen gas atmosphere at 190°C to 240°C, optionally in the presence of an esterification catalyst. From the viewpoint of toner storage, the reaction ratio of the polyhydric alcohol to the carboxylic acid monomer is preferably 0.83:1 to 1.3:1 in terms of the equivalent ratio of hydroxyl groups to carboxyl groups [OH]:[COOH].

[0056] The molar content of dicarboxylic acid in the carboxylic acid monomer is preferably 90% to 100%. If the molar content of dicarboxylic acid is low, the rate and speed of crystallization may decrease, resulting in insufficient toner agglomeration resistance (resistance to toner aggregation).

[0057] Examples of aliphatic dicarboxylic acids having 9 to 22 carbon atoms include azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. Furthermore, the dicarboxylic acid monomer may also include ester-forming derivatives of these aliphatic dicarboxylic acids. These dicarboxylic acid monomers may be used individually or in combination of two or more.

[0058] In the synthesis of crystalline polyester resins, a polycarboxylic acid monomer with a valency of 3 or higher may be used together with the above-mentioned dicarboxylic acid monomer. Examples of polycarboxylic acids with a valency of 3 or higher that can be used include trimellitic acid, pyromellitic acid, and their ester-forming derivatives. These polycarboxylic acid monomers with a valency of 3 or higher may be used individually or in combination of two or more.

[0059] The molar content of aliphatic diols with 2 to 10 carbon atoms in the polyhydric alcohol is preferably 80% to 100%.

[0060] Examples of aliphatic diols having 2 to 10 carbon atoms include ethylene glycol, 1,4-butanediol, and 1,6-hexanediol. These diol monomers may be used individually or in combination of two or more.

[0061] In the synthesis of crystalline polyester resins, polyol monomers with a valentity of 3 or higher may be used together with the above-mentioned diol monomers. Examples of polyol monomers with a valentity of 3 or higher include glycerin and trimethylolpropane. These polyol monomers with a valentity of 3 or higher may be used individually or in combination of two or more.

[0062] <Metal salts of the first fatty acid (metal salts of fatty acids used as internal additives)> The toner particles according to this embodiment contain a first fatty acid metal salt. That is, the first fatty acid metal salt in this disclosure means a fatty acid metal salt as an internal additive. A fatty acid metal salt is a salt composed of a fatty acid and a metal.

[0063] In this embodiment, a metal salt with a valent or higher valency is used as the first fatty acid metal salt. By using a metal salt with a valent or higher valency as the first fatty acid metal salt, a weak three-dimensional crosslink can be formed between the crystalline polyester resin and the colorant (pigment as a colorant) in the binder resin, thereby increasing the intensity of the formed image. As the first fatty acid metal salt, it is preferable that the metal is aluminum.

[0064] The fatty acid in the first fatty acid metal salt may be either a saturated or unsaturated fatty acid. Examples of aliphatic fatty acids include unsaturated fatty acids such as behenic acid, stearic acid, palmitic acid, myristic acid, and lauric acid; and unsaturated fatty acids such as oleic acid, linoleic acid, and ricinoleic acid. Among these fatty acids, those with 16 or more carbon atoms are preferred, and stearic acid, which has 18 carbon atoms, is more preferred.

[0065] Examples of fatty acid metal salts in which the metal is aluminum and the fatty acid is stearic acid include aluminum dihydroxystearate and aluminum tristearate.

[0066] The first fatty acid metal salt used in the toner particles according to this embodiment preferably has a hydroxyl group (i.e., an OH group). The presence of a hydroxyl group in the first fatty acid metal salt further strengthens the interaction between the first fatty acid metal salt and the colorant, resulting in a toner that can further exhibit the effects of this disclosure (improved low-temperature fixation effect due to the creation of images with high bending strength). Therefore, aluminum dihydroxystearate is particularly preferred as the first fatty acid metal salt used in the toner particles according to this embodiment.

[0067] The average dispersion diameter of the first fatty acid metal salt in the toner particles according to this embodiment is 50 nm or more and 500 nm or less, preferably 60 nm or more and 300 nm or less, and more preferably 70 nm or more and 150 nm or less. If the average dispersion diameter of the first fatty acid metal salt exceeds the above upper limit, sufficient interaction between the colorant and the amorphous polyester resin may not occur. Also, if the average dispersion diameter of the first fatty acid metal salt is below the above lower limit, the average dispersion diameter of the crystalline polyester resin will also become small, and the compatibility between the amorphous polyester resin and the crystalline polyester resin will become too high, which may lead to a deterioration in the heat resistance of the toner.

[0068] The toner surface exposure rate of the first fatty acid metal salt, calculated as the area ratio of the first fatty acid metal salt on the surface of the toner particles according to this embodiment, is preferably 1% to 5%, and more preferably 1.5% to 4%. When the average dispersion diameter of the first fatty acid metal salt is within the above range, the interaction between the first fatty acid metal salt and the second fatty acid metal salt can increase the cohesive force between toner particles, and an image with excellent bending strength can be formed. In other words, a toner with excellent low-temperature fixability can be realized. If the toner surface exposure rate of the first fatty acid metal salt exceeds the above upper limit, the heat resistance storage performance of the toner may deteriorate. If the toner surface exposure rate of the first fatty acid metal salt is below the above lower limit, the above-mentioned "interaction between the first fatty acid metal salt and the second fatty acid metal salt" may not occur sufficiently, and the effect of improving low-temperature fixability may not be obtained.

[0069] The content of the first fatty acid metal salt in the toner particles according to this embodiment is preferably 0.5% by mass or more and 2.0% by mass or less, and more preferably 0.7% by mass or more and 1.5% by mass or less. When the content of the first fatty acid metal salt in the toner particles is within the above range, the effect of improving low-temperature fixation by adding the first fatty acid metal salt to the toner particles can be further exhibited. If the content of the first fatty acid metal salt in the toner particles is below the above lower limit, this effect may not be sufficiently obtained. If the content of the first fatty acid metal salt in the toner particles exceeds the above upper limit, the heat resistance and storage properties of the toner may deteriorate.

[0070] Let the content of the crystalline polyester resin in the toner particles be M C in mass %, and let the content of the first fatty acid metal salt in the toner particles be M TF in mass %. It is preferable to satisfy the relationship of the following formula (1). M C / M TF As the lower limit of, it is more preferable to be 2.5 or more, and further preferably 4 or more. M C / M TF As the upper limit of, it is more preferable to be 8 or less, and further preferably 6 or less. 2 ≦ M C / M TF ≦ 10 ···(1)

[0071] By satisfying the relationship of the above formula (1), the first fatty acid metal salt in the toner particles can be controlled to a more appropriate particle size, and the effect of improving the low-temperature fixing property by adding the first fatty acid metal salt to the toner particles can be further exerted. M C / M TF If it is less than the above lower limit, this effect may not be obtained sufficiently. M C / M TF If it exceeds the above upper limit, the amount of the crystalline polyester resin may become too large, and the heat-resistant storage property of the toner may deteriorate.

[0072] <Colorant> The toner particles according to this embodiment preferably contain a colorant. As the colorant, organic pigments and inorganic pigments used in the electrophotography field can be used, and such pigments may be used in combination with organic dyes, inorganic dyes, etc.

[0073] Examples of the black colorant include carbon black, copper oxide, manganese dioxide, aniline black, activated carbon, non-magnetic ferrite, magnetic ferrite, magnetite, etc.

[0074] Examples of yellow colorants include CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, CI Pigment Yellow 180, and CI Pigment Yellow 185.

[0075] Examples of magenta colorants include CI Pigment Red 48:1, CI Pigment Red 53:1, CI Pigment Red 57:1, CI Pigment Red 122, CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 144, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 177, CI Pigment Red 178, and CI Pigment Red 222.

[0076] Examples of cyan colorants include CI Pigment Blue 15, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 16, and CI Pigment Blue 60.

[0077] The colorant content in the toner particles is preferably 3% to 15% by mass, and more preferably 5% to 10% by mass. The colorant may be used in the form of a masterbatch to ensure uniform dispersion in the binder resin. Furthermore, when forming a masterbatch, it is preferable to add a primary fatty acid metal salt in addition to the binder resin and colorant to create a masterbatch containing the binder resin, colorant, and primary fatty acid metal salt. By forming a masterbatch in this way, the dispersibility of the colorant and primary fatty acid metal salt in the toner particles can be improved, and consequently, a toner with superior low-temperature fixation and heat-resistant storage properties can be obtained.

[0078] <Release agent> The toner particles according to this embodiment contain a release agent. As the release agent, waxes used in electrophotography can be used, such as paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, carnauba wax, and synthetic ester wax. These waxes may be used individually or in combination of two or more. The wax content in the toner particles is typically 0.5% to 10% by mass, preferably between 1% and 5% by mass.

[0079] <Static control agent> The toner particles according to this embodiment preferably contain a charge control agent. As the charge control agent, charge control agents used in the field of electrophotography for controlling positive charge and negative charge can be used.

[0080] Examples of charge control agents for controlling positive charge include nigrosine dyes, basic dyes, quaternary ammonium salts, quaternary phosphonium salts, aminopyrine, pyrimidine compounds, polynuclear polyamino compounds, aminosilanes, nigrosine dyes and their derivatives, triphenylmethane derivatives, guanidine salts, and amidine salts.

[0081] Examples of charge control agents for controlling negative charge include oil-soluble dyes such as oil black and spiron black, metal-containing azo compounds, azo complex dyes, metal naphthenates, metal complexes and metal salts of salicylic acid and its derivatives (metals such as chromium, zinc, and zirconium), boron compounds, fatty acid soaps, long-chain alkyl carboxylates, and resin acid soaps.

[0082] In the toner according to this embodiment, one of the above-mentioned charge control agents may be used alone, or two or more may be used in combination.

[0083] The amount of charge control agent in the toner particles can be appropriately selected depending on the purpose, but it is preferably 0.5% by mass or more and 3.0% by mass or less, and more preferably 0.7% by mass or more and 2.5% by mass or less. By having the charge control agent content within the above range, it is possible to form high-density and high-quality images without impairing the various physical properties of the toner.

[0084] 3. External additives The toner according to this embodiment contains at least a second fatty acid metal salt as an external additive. That is, the second fatty acid metal salt in this disclosure means a fatty acid metal salt as an external additive.

[0085] A fatty acid metal salt is a salt composed of a fatty acid and a metal. Examples of metals in fatty acid metal salts include aluminum, calcium, potassium, magnesium, barium, lithium, zinc, copper, lead, nickel, strontium, cobalt, and sodium. However, in the toner particles according to this embodiment, it is preferable to use a divalent metal salt as the second fatty acid metal salt. Examples of divalent metals include magnesium, calcium, barium, and zinc. Among these, zinc is preferred.

[0086] The fatty acid in the second fatty acid metal salt may be either a saturated or unsaturated fatty acid. Examples of aliphatic fatty acids include unsaturated fatty acids such as behenic acid, stearic acid, palmitic acid, myristic acid, and lauric acid; and unsaturated fatty acids such as oleic acid, linoleic acid, and ricinoleic acid. Among these fatty acids, those with 16 or more carbon atoms are preferred, and stearic acid, which has 18 carbon atoms, is more preferred.

[0087] Examples of fatty acid metal salts include metal salts of stearic acid such as aluminum stearate, calcium stearate, potassium stearate, magnesium stearate, barium stearate, lithium stearate, zinc stearate, copper stearate, lead stearate, nickel stearate, strontium stearate, cobalt stearate, and sodium stearate; and metal salts of stearic acid such as zinc palmitate, cobalt palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, and calcium palmitate. Examples include metal salts of luminic acid; metal salts of lauric acid such as zinc laurate, manganese laurate, calcium laurate, iron laurate, magnesium laurate, and aluminum laurate; metal salts of oleic acid such as zinc oleate, manganese oleate, iron oleate, aluminum oleate, copper oleate, magnesium oleate, and calcium oleate; metal salts of linoleic acid such as zinc linoleate, cobalt linoleate, and calcium linoleate; and metal salts of ricinoleic acid such as zinc ricinoleate and aluminum ricinoleate.

[0088] These fatty acid metal salts may be used individually or in combination of two or more. Among these, stearic acid metal salts are preferred as the second fatty acid metal salt in this embodiment, and zinc stearate is more preferred.

[0089] There are no particular limitations on the method for producing fatty acid metal salts, but examples include cation substitution of fatty acid alkali metal salts and direct reaction of fatty acids with metal hydroxides. As an example of a method for producing zinc stearate as a fatty acid metal salt, examples include cation substitution of sodium stearate and reaction of stearic acid with zinc hydroxide.

[0090] In this embodiment, the average particle size of the second fatty acid metal salt in the toner is preferably 0.5 μm or more and 1.5 μm or less, and more preferably 0.5 μm or more and 1.0 μm or less. When the average particle size of the second fatty acid metal salt is within the above range, the effect of increasing the cohesive force between toner particles during toner fixing is further enhanced, and the intensity of the formed image can be further increased. If the average particle size of the second fatty acid metal salt is below the above lower limit, sufficient cohesive force between toner particles during toner fixing may not be obtained. If the average particle size of the second fatty acid metal salt exceeds the above upper limit, the effect of fixing inhibition by the second fatty acid metal salt may become stronger.

[0091] In the toner according to this embodiment, the content of the second fatty acid metal salt is preferably 0.1 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of toner particles, and more preferably 0.2 parts by mass or more and 0.4 parts by mass or less. When the content of the second fatty acid metal salt is within the above range, the effect of increasing the cohesive force between toner particles during toner fixing is further enhanced, and the intensity of the formed image can be further increased. If the content of the second fatty acid metal salt is below the above lower limit, sufficient cohesive force between toner particles during toner fixing may not be obtained. If the content of the second fatty acid metal salt exceeds the above upper limit, the effect of fixing inhibition by the second fatty acid metal salt may become stronger.

[0092] In the toner according to this embodiment, the adhesion strength of the second fatty acid metal salt to the toner particles is preferably 20% or more, more preferably 30% or more, and even more preferably 35% or more. When the adhesion strength of the second fatty acid metal salt to the toner particles is above the lower limit, the second fatty acid metal salt is less likely to detach from the surface of the toner particles as the toner moves from the developing tank to the fixing process, and a large amount of the second fatty acid metal salt remains on the surface of the toner particles until the toner is fixed. This further enhances the cohesive force between toner particles during toner fixing, and the intensity of the formed image can be further increased. This adhesion strength can be measured in accordance with the "Method for measuring the adhesion strength of the second fatty acid metal salt to toner particles" in the examples described later. The upper limit of the adhesion strength of the second fatty acid metal salt to the toner particles is 60% or less, preferably 50% or less, and more preferably 45% or less.

[0093] The toner according to this embodiment may contain other external additives besides the second fatty acid metal salt, to the extent that it does not impair the effects of this disclosure. In other words, other external additives besides the second fatty acid metal salt may be attached to the surface of the toner particles. As external additives other than the second fatty acid metal salt, external additives used in the field of electrophotography can be used, for example, inorganic particles such as silica can be used. The average particle size of the inorganic particles can be between 7 nm and 200 nm. Particles that have been surface-treated with a hydrophobic treatment agent such as a silane coupling agent, a titanium coupling agent, or a silicone oil to impart hydrophobicity are preferred because they reduce the decrease in electrical resistance and charge under high humidity. The other external additives besides the second fatty acid metal salt may be used individually or in combination of two or more.

[0094] The content of external additives other than the second fatty acid metal salt is preferably 0.5 parts by mass or more and 3 parts by mass or less per 100 parts by mass of toner particles. For example, if the content of silica particles as an external additive is below the lower limit, the effect of improving the fluidity of the toner may be insufficient. If the content of silica particles as an external additive exceeds the upper limit, the fixation performance may decrease.

[0095] The silica particles used as external additives can be of the following types: silica used in the field of electrophotography, such as fumed silica obtained by burning silicon tetrachloride, or dry silica such as arc silica which is atomized in the gas phase using high energy such as plasma; wet silica such as precipitated silica synthesized under alkaline conditions using an aqueous sodium silicate solution as a raw material, or gel silica synthesized under acidic conditions; colloidal silica obtained by polymerizing acidic silicic acid in an alkaline state; or sol-gel silica obtained by hydrolysis of organosilane compounds. In addition, commercially available hydrophobized silica particles may be used as external additives, or unhydrophobized silica particles may be treated before use.

[0096] One method for adding external additives to toner particles is to mix the toner particles and the external additives using an air-flow mixer such as a Henschel mixer.

[0097] 4. Two-component developer The two-component developer according to this embodiment comprises the toner according to this embodiment and a carrier. The two-component developer can be manufactured by mixing the toner and the carrier using a known mixer. The mass ratio of toner to carrier is not particularly limited and, for example, can be 3:97 to 12:88.

[0098] The carrier is agitated and mixed with the toner in the developing tank, imparting the desired charge to the toner. The carrier also acts as an electrode between the developing device and the photoreceptor, carrying the charged toner to the electrostatic latent image on the photoreceptor, thus forming the toner image. The carrier is held on the developing roller of the developing device by magnetic force, acts on the developing process, and then returns to the developing tank, where it is agitated and mixed again with new toner and reused repeatedly until the end of its lifespan.

[0099] Examples of carriers include those having a structure including a carrier core material and a resin coating layer that coats the carrier core material. The carrier core material is not particularly limited as long as it is used in the electrophotography field, and examples thereof include magnetic metals such as iron, copper, nickel, and cobalt; and magnetic metal oxides such as ferrite and magnetite. The volume average particle diameter of the carrier core material is not particularly limited, and examples thereof include 30 μm or more and 100 μm or less. The resin coating layer preferably contains a silicone resin or an acrylic resin. The silicone resin can delay the progress of contamination of the resin coating layer and is suitable for long-term use.

Examples

[0100] Hereinafter, based on examples and comparative examples, the toner and two-component developer of the present disclosure will be specifically described.

[0101] 1. Measurement and calculation methods <Method for calculating SP value> The SP value (solubility parameter) is calculated by the method described in "POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS. (pages 147 to 154)" proposed by Fedors et al.

[0102] <Method for measuring volume average particle diameter of toner particles> To 50 ml of an electrolytic solution (manufactured by Beckman Coulter, Inc., trade name: ISOTON-II), 20 mg of toner particles and 1 ml of sodium alkyl ether sulfate are added, and using an ultrasonic disperser (manufactured by AS ONE Corporation, tabletop type 2-frequency ultrasonic cleaner, model: VS-D100), dispersion treatment is performed at a frequency of 20 kHz for 3 minutes to obtain a measurement sample. The obtained measurement sample is measured using a particle size distribution measuring device (manufactured by Beckman Coulter, Inc., model: Multisizer3) under the conditions of aperture diameter: 100 μm and measurement particle number: 50,000 counts, and the volume average particle diameter is determined from the volume particle size distribution of the toner particles.

[0103] <Method for measuring the average dispersion diameter of primary fatty acid metal salts in toner particles> The toners prepared in the examples and comparative examples were embedded in epoxy resin, and the surfaces were prepared using an ultramicrotome (Reichert, product name: UltraCut N) to create samples of the toner particle cross-sections. The obtained samples were stained in the gas phase with a 0.5% aqueous solution of ruthenium(VIII) tetroxide and observed using a scanning transmission electron microscope and an energy-dispersive X-ray analyzer (EDX, Hitachi High-Technologies Corporation, model: S-4800). By comparing the microscope images with EDX images mapped to Al or Zn elements, the position and size of the first fatty acid metal salts were identified, and 50 to 100 first fatty acid metal salts were extracted. Image analysis software (Asahi Kasei Engineering Corporation, product name: A-Image-kun) was used to analyze the images and determine the equivalent circle diameter of the extracted first fatty acid metal salts. The average value of these values ​​was calculated as the average dispersion diameter of the first fatty acid metal salts.

[0104] <Method for measuring the surface exposure rate of toner containing the first fatty acid metal salt> Toner particles prepared in the examples and comparative examples (samples before the external additive step in the preparation procedure described below) are stained with a 0.5% aqueous solution of ruthenium(VIII) tetroxide and observed using a scanning transmission electron microscope and an energy-dispersive X-ray analyzer (EDX, Hitachi High-Technologies Corporation, model: S-4800). The position and size of the first fatty acid metal salt are identified by comparing the microscope image with the EDX image on which the Al or Zn elements are mapped. The areas where the first fatty acid metal salt is present are analyzed using image analysis software (Asahi Kasei Engineering Corporation, product name: A-zo-kun) to calculate the total area of ​​the first fatty acid metal salt on the toner particle surface. The ratio of the total area of ​​the first fatty acid metal salt to the surface area of ​​the toner particle in the microscope image is calculated as the toner surface exposure rate.

[0105] <Method for measuring the adhesion strength of di-fatty acid metal salts to toner particles> The toner sample obtained after performing the external additive removal treatment described in (1) to (6) below will be referred to as "Sample 1," and the toner sample before performing the external additive removal treatment described below will be referred to as "Sample 0." (1) Add 2.0 g of toner to 40 ml of a 0.2% by mass Triton (polyoxyethylene octylphenyl ether) aqueous solution and stir for 1 minute. (2) The above aqueous solution is subjected to ultrasonic irradiation (output: 40 μA, 4 minutes) using an ultrasonic homogenizer (manufactured by Nippon Seiki Seisakusho Co., Ltd., model: US-300T). (3) The aqueous solution after ultrasonic irradiation is left to stand for 3 hours to separate the toner from the liberated external additive. (4) After removing the supernatant liquid, add approximately 50 ml of pure water to the precipitate and stir for 5 minutes. (5) Perform suction filtration using a membrane filter with a pore size of 1 μm (manufactured by Advantec). (6) Vacuum dry any toner remaining on the filter overnight.

[0106] Next, the intensity of specific elements in the second fatty acid metal salts in 1g each of "Sample 0" and "Sample 1" is analyzed using a fluorescence X-ray analyzer (Rigaku Corporation, model: ZSX Primus II), and the adhesion intensity is calculated using the following formula (2). The specific elements are "Zn" for zinc fatty acid and "Mg" for magnesium fatty acid. Adhesion strength = (Strength in sample 1) / (Strength in sample 0) × 100 ... (2)

[0107] <Method for measuring the melting temperature (melting point) of release agents> Using a differential scanning calorimeter (Seiko Electronics Industries, Ltd., model number: DSC220), 1 g of the sample is heated from 20°C to 200°C at a heating rate of 10°C / min, and then rapidly cooled from 200°C to 20°C. This process is repeated twice, and the DSC curve is measured. The temperature of the endothermic peak corresponding to melting in the DSC curve measured in the second operation is defined as the melting temperature.

[0108] <Method for measuring the glass transition temperature (glass transition point) of polyester resin> Using a differential scanning calorimeter (Seiko Electronics Co., Ltd., model number: DSC220), 1 g of the sample is heated at a heating rate of 10°C / min in accordance with Japanese Industrial Standard (JIS) K7121-1987, and the DSC curve is measured. In the obtained DSC curve, the temperature at the intersection of a straight line extending from the high-temperature baseline of the endothermic peak corresponding to the glass transition to the low-temperature side, and a tangent line drawn at the point where the slope of the curve from the rising portion to the apex of the peak is maximum, is defined as the glass transition temperature (Tg).

[0109] <Method for measuring the softening temperature (softening point) of polyester resin> Using a flow characteristics evaluation device (Shimadzu Corporation, Flow Tester, Model: CFT-100C), 1 g of the sample was heated at a heating rate of 6°C / min while applying a load of 20 kgf / cm². 2 (9.8 × 10 5 Apply Pa and allow the sample to flow out of the die (nozzle diameter 1 mm, length 1 mm). The temperature at which half of the sample has flowed out is defined as the softening temperature (Tm).

[0110] <Method for measuring the melting temperature (melting point) of polyester resin> Using a differential scanning calorimeter (Seiko Electronics Industries, Ltd., model number: DSC220), 1 g of the sample is heated to 200°C, then cooled to 0°C at a rate of 10°C / min, and then heated again at a rate of 10°C / min to measure the DSC curve. The temperature corresponding to the maximum peak of endothermic and exothermic energy in the DSC curve is defined as the melting temperature (Tmp).

[0111] <Method for measuring the acid value and hydroxyl value of polyester resin> The acid value and hydroxyl value of polyester resin shall be measured in accordance with the 1992 edition of Japanese Industrial Standard (JIS) K0070. If the polyester resin contains solvent-insoluble components due to crosslinking, the sample shall be prepared by kneading it for 30 minutes at 130°C and 70 rpm using a kneading device (Toyo Seiki Co., Ltd., product name: Laboplastmill MODEL4M150).

[0112] <Method for measuring the peak top molecular weight of polyester resin> The peak-top molecular weight (Mp) of polyester resin is measured using gel permeation chromatography (GPC) under the following conditions. For molecular weight measurement, the polyester resin is dissolved in tetrahydrofuran (THF), and the insoluble components are filtered out using a glass filter to obtain the solution as the sample. The peak-top molecular weight refers to the molecular weight that shows the highest peak height in the chromatogram obtained by GPC measurement. • Device: HLC-8120, manufactured by Tosoh Corporation • Columns: Two TSK GEL GMH6 columns manufactured by Tosoh Corporation. ·Measurement temperature: 40℃ • Sample solution: 0.25% by mass THF solution ·Solution injection volume: 100μL • Detection device: Refractive index detector • Reference material: 12 samples of standard polystyrene (TSKstandard POLYSTYRENE) manufactured by Tosoh Corporation (molecular weight: 500, 1050, 2800, 5970, 9100, 18100, 37900, 96400, 190000, 355000, 1090000, 2890000)

[0113] 2. Preparation and manufacturing of raw materials <Career Creation> A coating resin solution was prepared by dissolving 0.375 parts by mass of coating resin 1 (silicone-based, manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR240) and 0.375 parts by mass of coating resin 2 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KR251) in 12 parts by mass of toluene. Conductive particles (manufactured by Cabot Co., Ltd., product name: VULCAN XC-72) and a coupling agent (manufactured by Toray Dow Corning Ltd., product name: AY43-059) were added and dispersed to this solution to prepare a coating resin solution. Using the immersion method, the surface of 100 parts by mass of ferrite carrier core material with a volume-average particle diameter of 40 μm was coated with 12.8 parts by mass of this coating resin solution. Subsequently, after a curing process at a curing temperature of 200°C for a curing time of 1 hour, the carrier was obtained by passing it through a sieve with a mesh size of 150 μm.

[0114] <Preparation of amorphous polyester resin A> In a reaction vessel, 440 g (2.7 mol) of terephthalic acid, 235 g (1.4 mol) of isophthalic acid, 7 g (0.05 mol) of adipic acid, 554 g (8.9 mol) of ethylene glycol, and 0.5 g of tetrabutoxytitanate as a polymerization catalyst were added. The mixture was reacted at 210°C under a nitrogen stream for 5 hours, while distilling off the water and ethylene glycol produced. Then, the mixture was reacted under reduced pressure of 5 mmHg to 20 mmHg for 1 hour. Next, 103 g (0.54 mol) of trimellitic anhydride was added, and the mixture was reacted under atmospheric pressure for 1 hour. After that, the mixture was reacted under reduced pressure of 20 mmHg to 40 mmHg, and the resin was removed at the predetermined softening point. The recovered ethylene glycol amounted to 219 g (3.5 mol). The obtained resin was cooled to room temperature and then pulverized to form particles. This was designated as amorphous polyester resin A. Amorphous polyester resin A had a Tg of 56°C, a Tm of 135°C, a peak-top molecular weight Mp of 5000, an SP value of 11.0, an acid value of 37 mgKOH / g, and a hydroxyl value of 50 mgKOH / g.

[0115] <Preparation of Styrene Acrylic Resin B> 74 parts by mass of styrene, 26 parts by mass of n-butyl acrylate, and 1.0 part by mass of methacrylic acid were placed in a nitrogen-purged flask, and after raising the internal temperature to 120°C, bulk polymerization was carried out for 10 hours. Next, 80 parts by mass of xylene was added, and 20 parts by mass of a xylene solution in which 1.5 parts by mass of di-t-butyl peroxide was uniformly dissolved was continuously added over 8 hours while maintaining the temperature at 130°C. The mixture was then flushed into a vessel at a temperature of 90°C and a pressure of 10 mmHg to remove solvents and other residues, and then coarse grinding was performed using a coarse grinder to obtain styrene-acrylic resin B. Styrene-acrylic resin B had a Tm of 140°C and an SP value of 10.4.

[0116] <Preparation of crystalline polyester resin C1> In a reaction vessel, 132 g (1.12 mol) of 1,6-hexanediol, 230 g (1.0 mol) of 1,10-decanedicarboxylic acid, and 3 g of tetrabutoxytitanate as a polymerization catalyst were added, and the reaction was carried out at 210°C under atmospheric pressure for 5 hours while distilling off the water produced. The reaction was then continued under reduced pressure of 5 mmHg to 20 mmHg, and the resin was removed when the acid value fell to 2 mg KOH / g or less. After the obtained resin was cooled to room temperature, it was pulverized into particles. This was designated as crystalline polyester resin C1. Crystalline polyester resin C1 had a Tmp of 80°C, a Tm of 88°C, a Tm / Tmp of 1.1, a peak-top molecular weight Mp of 30000, an SP value of 9.5, an acid value of 1 mg KOH / g, and a hydroxyl value of 10 mg KOH / g.

[0117] <Preparation of crystalline polyester resin C2> In a reaction vessel, 132 g (1.12 mol) of 1,6-hexanediol, 343 g (1.0 mol) of 1,18-octadecanedicarboxylic acid, and 3 g of tetrabutoxytitanate as a polymerization catalyst were added, and the reaction was carried out at 210°C under atmospheric pressure for 5 hours while distilling off the water produced. The reaction was then continued under reduced pressure of 5 mmHg to 20 mmHg, and the resin was removed when the acid value fell to 2 mg KOH / g or less. After the obtained resin was cooled to room temperature, it was pulverized to form particles, which were then designated as crystalline polyester resin C2. Crystalline polyester resin C2 had a Tmp of 75°C, a Tm of 90°C, a Tm / Tmp of 1.2, a peak-top molecular weight Mp of 25000, an SP value of 9.0, an acid value of 1 mg KOH / g, and a hydroxyl value of 5 mg KOH / g.

[0118] <Preparation of crystalline polyester resin C3> In a reaction vessel, 118 g (1.00 mol) of 1,6-hexanediol, 343 g (1.0 mol) of 1,18-octadecanedicarboxylic acid, and 3 g of tetrabutoxytitanate as a polymerization catalyst were added, and the reaction was carried out at 210°C under atmospheric pressure for 5 hours while distilling off the water produced. The reaction was then continued under reduced pressure of 5 mmHg to 20 mmHg, and the resin was removed when the acid value fell to 2 mg KOH / g or less. After the obtained resin was cooled to room temperature, it was pulverized to form particles, which were then used as crystalline polyester resin C3. Crystalline polyester resin C3 had a Tmp of 72°C, a Tm of 90°C, a Tm / Tmp of 1.3, a peak-top molecular weight Mp of 25000, an SP value of 9.9, an acid value of 0 mg KOH / g, and a hydroxyl value of 3 mg KOH / g.

[0119] <Preparation of the first fatty acid metal salt (fatty acid metal salt as an internal additive)> As the first fatty acid metal salt, the following trivalent fatty acid metal salts were used. • Fatty acid metal salt "TGM1": Aluminum dihydroxystearate (fatty acid metal salt containing an OH group, manufactured by NOF Corporation, product name: Aluminum Stearate 300) • Fatty acid metal salt "TGM2": Aluminum tristearate (fatty acid metal salt without OH groups, manufactured by NOF Corporation, product name: Aluminum Stearate 900)

[0120] <Preparation of second fatty acid metal salts (fatty acid metal salts as external additives)> - Preparation of fatty acid metal salt "DFM1" - 1422 parts by mass of stearic acid were added to 10,000 parts by mass of ethanol and mixed at a liquid temperature of 75°C. Then, 507 parts by mass of zinc hydroxide were added little by little, and the mixture was stirred for 1 hour after the addition was complete. After that, the liquid temperature was cooled to 20°C, and the product was filtered to remove the ethanol and reaction residue, and the solid was obtained. The extracted solid was dried at 150°C for 3 hours using a heated vacuum dryer. After removing the solid from the dryer and allowing it to cool, the obtained zinc stearate solid was coarsely ground using a power mill (manufactured by Dalton Co., Ltd., model: P-3) with a φ2 mm screen to obtain a coarse pulverized product.

[0121] The obtained coarse pulverized material was finely pulverized using a jet-type pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain fine pulverized material. This was then classified using an elbow-jet classifier (manufactured by Nippon Steel Mining Co., Ltd., model: EJ-LABO) to obtain DFM1, a metal salt of the second fatty acid, which is zinc stearate. The average particle size of the metal salt of the second fatty acid, DFM1, was 0.7 μm.

[0122] - Preparation of fatty acid metal salts "DFM2" to "DFM5" - Except for changing the grinding and classification conditions, fatty acid metal salts "DFM2" to "DFM5" with different average particle sizes were prepared in the same manner as described in "Preparation of fatty acid metal salt DFM1" above. Their average particle sizes are shown in Table 1 below.

[0123] - Preparation of fatty acid metal salt "DFM6" - The fatty acid metal salt "DFM6," which is magnesium stearate, was prepared in the same manner as described above for "Preparation of fatty acid metal salt "DFM1," except that 507 parts by mass of zinc hydroxide was replaced with 293 parts by mass of magnesium hydroxide, and the fine grinding and classification conditions were changed. The average particle size of the second fatty acid metal salt DFM6 was 1.0 μm. Table 1 below summarizes the compound names and average particle sizes of fatty acid metal salts DFM1 to DFM6.

[0124] [Table 1]

[0125] 3. Preparation of toner and two-component developer <Toner manufacturing process> [Example 1] -First melting and mixing process- The following raw materials were used in the first melting and kneading process. • Binding resin The above "amorphous polyester resin A": 65.0% by mass • Colorants Carbon black (manufactured by Cabot Co., Ltd., product name: Regal330): 30.0% by mass • Metal salts of the first fatty acid The above fatty acid metal salt "TFM1": 5.0% by mass

[0126] The above raw materials were pre-mixed for 5 minutes using a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd., model: FM20C), and then melt-kneaded under the following conditions using an open-roll type continuous kneader (manufactured by Nippon Coke Industries Co., Ltd., model: MOS320-1800) to obtain the first melt-kneaded product. • Heating roll supply side temperature / discharge side temperature: 130℃ / 100℃ • Cooling roll supply side temperature / discharge side temperature: 40℃ / 25℃ • Heating roll and cooling roll: Diameter 320mm, effective length 1550mm • Roll gap on the supply and discharge sides: 0.3 mm • Heating roll rotation speed / Cooling roll rotation speed: 75 rpm / 65 rpm ·Raw material supply rate: 5.0kg / hour

[0127] -Second melting and mixing process- The following raw materials were used in the second melting and kneading process. • Binding resin The above "amorphous polyester resin A": 71.0% by mass • "First molten mixture" obtained in the above first molten mixing process: 20.0% by mass • Crystalline polyester resin The above "crystalline polyester resin C1": 5.0% by mass • Antistatic agent Salicylic acid compound (manufactured by Orient Chemical Industries, Ltd., product name: Bontron E-84): 1.0% by mass • Release agent Ester wax (manufactured by NOF Corporation, product name: WE-15): 3.0% by mass

[0128] The above raw materials were pre-mixed for 5 minutes using a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd., model: FM20C), and then melt-kneaded using a twin-screw extruder at a cylinder temperature of 110°C, barrel rotation speed of 200 rpm, and raw material supply rate of 15 kg / hour to obtain a molten mixture.

[0129] -Coarse grinding and fine grinding processes- The resulting molten mixture was cooled using a cooling belt, and then coarsely ground using a power mill (manufactured by Dalton Co., Ltd., model: P-3) with a φ2 mm screen to obtain a coarsely ground product.

[0130] The obtained coarse pulverized material was finely pulverized using a jet-type pulverizer (manufactured by Nippon Pneumatic Mfg. Co., Ltd., model: IDS-2) to obtain fine pulverized material.

[0131] -Classification process- Next, the obtained pulverized material was classified using an elbow jet classifier (manufactured by Nippon Steel Mining Co., Ltd., model: EJ-LABO) to obtain toner particles with a volume-average particle diameter of 6.7 μm.

[0132] -External addition process- To 100 parts by mass of the obtained toner particles, 1.0 part by mass of silica particles (average particle size: 7 nm, manufactured by Nippon Aerosil Co., Ltd., product name: R976S) was added and stirred for 1 minute in a Henschel mixer (manufactured by Nippon Coke Industries Co., Ltd., model: FM20C) with the tip speed of the stirring blade set to 40 m / sec. Then, 0.3 parts by mass of the above fatty acid metal salt "DFM1" was added as the second fatty acid metal salt, and the mixture was stirred for 5 minutes with the tip speed of the Henschel mixer set to 40 m / sec to obtain toner. The adhesion strength of the second fatty acid metal salt to the toner particles in the obtained toner was 40%.

[0133] <Process for preparing two-component developer> The obtained toner and the carrier prepared in "Carrier Preparation" above were adjusted so that the toner concentration relative to the total amount of the two-component developer was 7%, and the mixture was then mixed for 20 minutes in a V-type mixer (manufactured by Tokuju Kogyosho Co., Ltd., model: V-5) to obtain a two-component developer with a toner concentration of 7%.

[0134] [Examples 2-22, Comparative Examples 1-7] Except for changing the types and amounts of raw material components as shown in Tables 2 and 3 below, and controlling the conditions in the external addition process (external addition conditions for the second fatty acid metal salt) to change the adhesion strength of the second fatty acid metal salt to the toner particles, the toners and two-component developers of Examples 2 to 22 and Comparative Examples 1 to 7 were obtained in the same manner as in Example 1. In Tables 2 and 3, "crystalline Pes" means crystalline polyester resin, "amorphous PesA" means amorphous polyester resin A, and "St-AcB" means styrene acrylic resin B.

[0135] In Examples 2-10 and Comparative Examples 1 and 2, the average dispersion diameter of the first fatty acid metal salt in the toner particles was controlled by adjusting the type of crystalline polyester resin and the ratio of the crystalline polyester resin to the amount of the first fatty acid metal salt added. More specifically, when "crystalline polyester resin C2" was used as the crystalline polyester resin, the average dispersion diameter of the first fatty acid metal salt tended to be larger, while when "crystalline polyester resin C3" was used as the crystalline polyester resin, the average dispersion diameter of the first fatty acid metal salt tended to be smaller. This is thought to be because the degree of compatibility between the crystalline polyester resin and the amorphous polyester resin affects the dispersion state of the crystalline polyester resin.

[0136] In Examples 19 and 20, toners and two-component developers with different adhesion strengths of the second fatty acid metal salt were obtained by changing the stirring time using a Henschel mixer after adding the second fatty acid metal salt in the external additive process, compared to Example 1. Specifically, Example 19 was carried out with the stirring time changed to 2 minutes, and Example 20 was carried out with the stirring time changed to 1 minute.

[0137] [Table 2]

[0138] [Table 3]

[0139] 4. Evaluation <Evaluation Item 1: Heat Resistance> The heat resistance of the toner was evaluated based on the presence or absence of aggregates after high-temperature storage.

[0140] 20g of toner was placed in a 250ml wide-mouthed cylindrical plastic container, sealed, and left at 50°C for 72 hours. After that, the toner was removed and sieved through a 230-mesh sieve. The mass of the toner remaining on the sieve was measured, and the remaining percentage, which is the ratio of this mass to the total toner mass (20g), was calculated. Based on this remaining percentage, the "heat resistance to storage" of the toner was evaluated according to the following criteria.

[0141] ◎ (Excellent): No aggregation. Remaining percentage is less than 0.5%. ○ (Good): Only trace amounts of aggregation. The remaining percentage is between 0.5% and less than 7%. △ (Acceptable): High aggregation. The remaining percentage is 7% or more but less than 12%. × (Unacceptable): Excessive aggregation. The remaining percentage is 12% or more.

[0142] <Evaluation Item 2: Low-temperature fixation> A commercially available photocopier (manufactured by Sharp Corporation, model: MX-5100FN) modified for evaluation purposes was used to create fixed images using a two-component developer.

[0143] First, a sample image containing a solid color image (a rectangle measuring 20mm vertically and 50mm horizontally) was formed as an unfixed image on recording paper (Sharp Corporation, PPC paper, product number: SF-4AM3). At this time, the amount of toner adhering to the recording paper in the solid color image was 0.5 mg / cm². 2 I adjusted it so that it would be as follows.

[0144] Next, a fixed image was formed using a belt fixing device. The fixing process speed was set to 140 mm / second, and the temperature of the fixing belt was increased in 5°C increments starting from 95°C to confirm a temperature range in which "low-temperature offset" did not occur and there were no problems with "evaluating bending strength".

[0145] Here, "low-temperature offset" is defined as the toner not fixing to the recording paper during the fixing process, but remaining attached to the fixing belt until it completes one rotation and then adhering to the recording paper.

[0146] Furthermore, the "evaluation of bending strength" was performed according to the procedure shown in Figure 3. Specifically, the recording paper (recording paper 3 in Figure 3) on which the solid image (toner layer 2 in Figure 3) was formed was folded, and a 1 kg weight was placed on the folded part and rubbed once to create a crease. Next, the folded recording paper was unfolded, another PPC paper (manufactured by Sharp Corporation, part number: PP106A4C) was placed on top of the creased part of the solid image, and a 1 kg weight was placed on top and rubbed. Visual inspection was then performed to check whether there were any areas where the image was missing (i.e., whether there were any areas where the toner layer 2 had peeled off in the dashed line area in Figure 3). Here, Figures 4 and 5 are enlarged views of the dashed line area in Figure 3, with Figure 4 illustrating the case where there is no peeling of the toner layer 2, and Figure 5 illustrating the case where there is peeling of the toner layer 2. As shown in Figure 5, when there is peeling of the toner layer 2, areas where the image is missing appear.

[0147] Based on the results of this visual inspection, the products were ranked on a five-point scale according to the following criteria, and a rank of 3 or higher was considered to indicate no problems with the "assessment of bending strength."

[0148] Rank 5: Almost no peeling along the fold. Rank 4: There is some minor peeling on a part of the fold. Rank 3: There are intermittent, fine linear peeling along the folds. Rank 2: There are continuous, thick, linear peeling marks along the folds. Rank 1: There is significant delamination along the fold.

[0149] If no "low-temperature offset" occurred and there were no problems with the "evaluation of bending strength," the low-temperature fixing performance at that temperature was deemed acceptable. This evaluation was performed for each temperature, and based on the lowest temperature at which it was deemed acceptable (i.e., the temperature at which fixing was possible on the low-temperature side), the "low-temperature fixing performance" was evaluated according to the following criteria.

[0150] ◎ (Excellent): The minimum temperature is below 105℃. ○ (Good): The minimum temperature is between 105°C and 120°C. △ (Acceptable): The minimum temperature is between 120°C and 130°C. × (Not acceptable): The minimum temperature is 130°C or higher.

[0151] [Table 4]

[0152] Table 4 shows the evaluation results of low-temperature fixability (the ability to form images with excellent bending strength while suppressing the occurrence of low-temperature offset) and heat-resistant storage in each example and comparative example. According to Table 4, the toners of Examples 1 to 22, in which an external additive is attached to the surface of the toner particles and which satisfy the following requirements (A) to (D), exhibited excellent low-temperature fixability and sufficient heat-resistant storage. (A) The toner particles include an amorphous polyester resin, a crystalline polyester resin, a release agent, and a first fatty acid metal salt. (B) The first fatty acid metal salt is a metal salt with a valency of 3 or higher. (C) The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. (D) The external additive contains a metal salt of the second fatty acid.

[0153] In contrast, Comparative Examples 1 to 7, which did not meet these requirements, were inferior to the examples in at least one of the evaluations of low-temperature fixability and heat-resistant storage.

[0154] Comparative Examples 1 and 2, in which the average dispersion diameter of the first fatty acid metal salt differs, are examples that do not satisfy requirement (C) above. Comparative Example 3, in which no fatty acid metal salt is added as an internal additive to the toner particles, Comparative Example 6, in which crystalline polyester resin is not contained in the toner particles, and Comparative Example 7, in which amorphous polyester resin is not contained in the toner particles, are examples that do not satisfy requirement (A) above. Comparative Example 4, in which zinc stearate (fatty acid metal salt "DFM1") is used as an internal additive, is an example that does not satisfy requirement (B) above because zinc stearate is a divalent metal salt. Comparative Example 5, in which no fatty acid metal salt is added as an external additive, is an example that does not satisfy requirement (D) above.

[0155] Example 4, in which the toner surface exposure rate of the first fatty acid metal salt, calculated as the area ratio of the first fatty acid metal salt on the surface of the toner particles, is 1% or more, is superior to Example 2, in terms of evaluation of low-temperature fixability and heat-resistant storage, and is particularly superior in the evaluation of heat-resistant storage.

[0156] Furthermore, Example 5, in which the toner surface exposure rate of the first fatty acid metal salt is 5% or less, is superior to Example 3, in terms of evaluation of low-temperature fixability and heat-resistant storage, and is particularly superior in terms of evaluation of low-temperature fixability.

[0157] Examples 4 and 6, in which the content of the primary fatty acid metal salt in the toner particles is 0.5% by mass or more, show superior evaluation of low-temperature fixability and heat-resistant storage compared to Example 7, in which the content is less than 0.5% by mass, and are particularly superior in the evaluation of heat-resistant storage.

[0158] Furthermore, Example 5, in which the content of the primary fatty acid metal salt in the toner particles is 2.0% by mass or less, is superior to Example 8, in terms of evaluation of low-temperature fixability and heat resistance, and is particularly superior in the evaluation of low-temperature fixability.

[0159] The content of crystalline polyester resin in toner particles is M C The content of the primary fatty acid metal salt in the toner particles is expressed as mass%, and M TF If expressed as mass%, then MC / M TF Example 8, where the value is 2 or more, is M C / M TF It can be seen that the evaluation of low-temperature fixation performance is superior to that of Example 9, where the value is less than 2. Also, M C / M TF Example 5, where is 2.5 or higher, is M C / M TF Compared to Examples 8 and 9, where the value was less than 2.5, this example shows superior evaluation of low-temperature fixability and heat-resistant storage, and is particularly superior in the evaluation of low-temperature fixability.

[0160] Also, M C / M TF Example 4, in which M is 10 or less, C / M TF It can be seen that this method is superior to Example 10, which has more than 10 examples, particularly in terms of heat resistance and storage performance.

[0161] Example 12, in which the average particle size of the second fatty acid metal salt is 0.5 μm or more, shows a lower minimum temperature (temperature at which low-temperature fixing is possible) in the low-temperature fixing performance evaluation compared to Example 13, in which the average particle size is less than 0.5 μm, indicating superior low-temperature fixing performance.

[0162] Furthermore, it can be seen that Example 11, in which the average particle size of the second fatty acid metal salt is 1.5 μm or less, is particularly superior to Example 14, in terms of evaluation of low-temperature fixation properties, compared to Example 14, in which the average particle size exceeds 1.5 μm.

[0163] Example 15, in which the content of the second fatty acid metal salt is 0.1 parts by mass or more per 100 parts by mass of toner particles, is found to be particularly superior in the evaluation of low-temperature fixation performance compared to Example 17, in which the content is less than 0.1 parts by mass.

[0164] Furthermore, it can be seen that Example 16, in which the content of the second fatty acid metal salt is 0.5 parts by mass or less per 100 parts by mass of toner particles, is particularly superior in the evaluation of low-temperature fixation performance compared to Example 18, in which the content exceeds 0.5 parts by mass.

[0165] Example 19, in which the adhesion strength of the second fatty acid metal salt to the toner particles is 20% or more, shows a lower minimum temperature (low-temperature fixing temperature) in the low-temperature fixing performance evaluation compared to Example 20, in which the adhesion strength is less than 20%, indicating superior low-temperature fixing performance.

[0166] Example 1, in which the first fatty acid metal salt has a hydroxyl group, is superior to Example 21, in terms of evaluation of low-temperature fixability and heat resistance to storage, compared to Example 21, in which the first fatty acid metal salt does not have a hydroxyl group.

[0167] Example 22 is an example in which magnesium stearate was used as the secondary fatty acid metal salt instead of zinc stearate, as used in Example 1 and other examples. In Example 22 as well, it can be seen that the material exhibits excellent low-temperature fixation and sufficient heat resistance for storage.

[0168] The embodiments disclosed herein are illustrative in all respects and are not intended to be restrictive. Therefore, the technical scope of this disclosure is not construed solely by the embodiments described above, but is defined by the claims. This includes all modifications within the meaning and scope of the claims. [Explanation of Symbols]

[0169] 1 Toner 10 toner particles 11. Amorphous polyester resin (binding resin) 12. Crystalline polyester resin 13 Release agent 14. Colorants 15. Metal salts of primary fatty acids (metal salts of fatty acids used as internal additives) 16. Secondary fatty acid metal salts (fatty acid metal salts as external additives) 2 Toner Layers 3. Record sheet

Claims

1. Toner in which an external additive is attached to the surface of toner particles, The toner particles comprise an amorphous polyester resin, a crystalline polyester resin, a mold release agent, and a first fatty acid metal salt. The aforementioned first fatty acid metal salt is a metal salt with a valent or higher valency. The average dispersion diameter of the first fatty acid metal salt in the toner particles is 50 nm or more and 500 nm or less. The toner is characterized by containing a second fatty acid metal salt as an external additive.

2. The toner according to claim 1, The toner is characterized in that the surface exposure rate of the first fatty acid metal salt, calculated as the area ratio of the first fatty acid metal salt to the surface of the toner particles, is 1% or more and 5% or less.

3. The toner according to claim 1 or claim 2, The toner is characterized in that the content of the first fatty acid metal salt in the toner particles is 0.5% by mass or more and 2.0% by mass or less.

4. The toner according to claim 1 or claim 2, The content of the crystalline polyester resin in the toner particles is M Ｃ The content of the first fatty acid metal salt in the toner particles is expressed as mass %, and M ＴＦ A toner characterized by satisfying the relationship shown in the following formula (1) when expressed as mass percent. 2≦M Ｃ / M ＴＦ ≦10 ・・・(1)

5. The toner according to claim 1 or claim 2, The toner is characterized in that the average particle size of the second fatty acid metal salt is 0.5 μm or more and 1.5 μm or less.

6. The toner according to claim 1 or claim 2, The toner is characterized in that the content of the second fatty acid metal salt is 0.1 parts by mass or more and 0.5 parts by mass or less per 100 parts by mass of the toner particles.

7. The toner according to claim 1 or claim 2, The toner is characterized in that the adhesion strength of the second fatty acid metal salt to the toner particles is 20% or more.

8. The toner according to claim 1 or claim 2, The toner is characterized in that the first fatty acid metal salt has a hydroxyl group.

9. A two-component developer comprising the toner described in claim 1 or claim 2 and a carrier.

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