JP6409705B2 - Toner for electrostatic latent image development - Google Patents

Description

  The present invention relates to an electrostatic latent image developing toner.

  As a toner having both blocking resistance, filming resistance, and low-temperature fixability, for example, a toner described in Patent Document 1 has been proposed. Patent Document 1 describes a toner having a core-shell structure having a toner core containing at least a resin and a shell formed by coating the surface of the toner core with a resin. The toner described in Patent Document 1 contains a copolymer whose shell is formed using at least a styrene monomer and a diene monomer.

JP 2011-150229 A

  However, in the toner described in Patent Document 1, since the binder resin contained in the toner core is one kind of styrene-acrylic acid resin, the fixing temperature range (from a temperature at which no cold offset occurs to a temperature at which hot offset does not occur). It is considered that it is difficult to satisfy a sufficient fixing property. Further, the toner described in Patent Document 1 is still insufficient to obtain filming resistance and blocking resistance.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a toner for developing an electrostatic latent image that is excellent in filming resistance, blocking resistance and fixability.

The electrostatic latent image developing toner of the present invention includes a plurality of toner particles. The toner particles include an amorphous polyester resin A, an amorphous polyester resin B, and a crystalline polyester resin C as binder resins. Satisfies a softening point T _A of the amorphous polyester resin A, and a softening point T _B of the amorphous polyester resin B, and a softening point T _C and the following formula of the crystalline polyester resin C (1) and (2) . In the CuKα characteristic X-ray diffraction spectrum, the Bragg angle 2θ has two or more peaks in the range of 19 ° or more and 25 ° or less. When the peak having the highest intensity among the two or more peaks is represented as the first peak, and the peak having the second largest intensity among the two or more peaks is represented as the second peak, the first peak and the second peak Among them, the peak intensity P _H located on the high angle side and the peak intensity P _L located on the low angle side satisfy the following formula (3).
_{1.30 ≦ T A / T B ≦} 1.60 ··· (1)
0.90 ≦ T _C / T _B ≦ 1.10 (2)
1.00 ≦ P _L / P _H ≦ 2.00 (3)

  According to the present invention, it is possible to provide a toner for developing an electrostatic latent image, which is excellent in filming resistance, blocking resistance and fixability.

3 is an image obtained by photographing a cross-section of toner particles contained in an electrostatic latent image developing toner according to an embodiment of the present invention with a scanning probe electron microscope (SPM).

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, about the location where description overlaps, although description may be abbreviate | omitted suitably, the summary of invention is not limited.

  The electrostatic latent image developing toner according to this embodiment (hereinafter sometimes simply referred to as “toner”) is a powder composed of a large number of toner particles. The toner particles contained in the toner according to the present embodiment may have a shell layer. An external additive may adhere to the surface of the toner particles contained in the toner according to the present embodiment. If not necessary, the external additive may be omitted. Hereinafter, the toner particles before the external additive adheres may be referred to as toner mother particles. The toner according to the exemplary embodiment can be used in, for example, an electrophotographic apparatus (image forming apparatus).

  In the image forming apparatus, the electrostatic latent image is developed using a developer containing toner. For example, when the image forming apparatus employs an intermediate transfer method, in the developing process, charged toner is attached to the electrostatic latent image formed on the photoconductor to form a toner image. In the subsequent transfer process, after the toner image on the photosensitive member is transferred to an intermediate transfer member (for example, an intermediate transfer belt), the toner image on the intermediate transfer member is further transferred to a recording medium (for example, paper). Thereafter, the toner is heated to fix the toner on the recording medium. As a result, an image is formed on the recording medium. For example, a full color image can be formed by superposing four color toner images of black, yellow, magenta, and cyan.

The toner according to the exemplary embodiment has the following configurations (A) and (B).
Configuration (A): The toner particles include an amorphous polyester resin A, an amorphous polyester resin B, and a crystalline polyester resin C as binder resins. Satisfies a softening point T _A of the amorphous polyester resin A, and a softening point T _B of the amorphous polyester resin B, and a softening point T _C and the following formula of the crystalline polyester resin C (1) and (2) .
_{1.30 ≦ T A / T B ≦} 1.60 ··· (1)
0.90 ≦ T _C / T _B ≦ 1.10 (2)

Configuration (B): In the CuKα characteristic X-ray diffraction spectrum, the Bragg angle 2θ has two or more peaks in the range of 19 ° or more and 25 ° or less. The peak having the highest intensity among the two or more peaks is represented as a first peak, and the peak having the second largest intensity among the two or more peaks is represented as a second peak. among the peaks, peaks located on the high angle side and the intensity P _H (hereinafter, high angle peak and is sometimes described), the peak located on the lower angle side (hereinafter, may be referred to as a low angle peak) The intensity P _L satisfies the following formula (3).
1.00 ≦ P _L / P _H ≦ 2.00 (3)

  The binder resin may be substantially composed of the amorphous polyester resin A, the amorphous polyester resin B, and the crystalline polyester resin C. The toner particles may further contain another resin as a binder resin. As other resin, a thermoplastic resin is mentioned, for example. Preferable examples of the thermoplastic resin that can be used as the binder resin include polyester resins, styrene resins, acrylic resins, olefin resins (more specifically, polyethylene resins or polypropylene resins, etc.), vinyl resins. (More specifically, vinyl chloride resin, polyvinyl alcohol resin, vinyl ether resin, or N-vinyl resin), polyamide resin, urethane resin, styrene-acrylic acid resin, or styrene-butadiene resin. Among these, the polyester resin is particularly preferable because it has excellent compatibility with the amorphous polyester resin A, the amorphous polyester resin B, and the crystalline polyester resin C.

  When the other resin is a polyester resin, for example, the toner particles may contain two or more crystalline polyester resins as a binder resin. When the toner particles contain two or more crystalline polyester resins as the binder resin, the crystalline polyester resin C is the resin having the largest content in the toner particles among the two or more crystalline polyester resins. Further, the binder resin may contain three or more kinds of amorphous polyester resins. When toner particles contain three or more types of amorphous polyester resins as binder resins, two of the three or more types of amorphous polyester resins selected from the order of the largest content in the toner particles are amorphous. And polyester resin A and amorphous polyester resin B.

The softening points (specifically, T _A , T _B and T _C ) can be obtained based on an S-shaped curve obtained by a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation). Details of the method for measuring the softening point will be described later.

The X-ray diffraction spectrum can be measured by an X-ray diffraction apparatus (“RINT (registered trademark) 1100” manufactured by Rigaku Corporation). From the obtained X-ray diffraction spectrum, it can be confirmed that the Bragg angle 2θ has a first peak and a second peak in a range of 19 ° to 25 °. Details of the measurement method of the X-ray diffraction spectrum will be described later. Further, the intensity P _H of the high angle peak and the intensity P _L of the low angle peak are obtained from the obtained X-ray diffraction spectrum. Then, it can be confirmed that the and P _H and P _L satisfies the equation (3).

The toner having the configuration (A) contains two types of amorphous polyester resins having different softening points. The fixable temperature range of toner containing such an amorphous polyester resin tends to be widened. In the toner having the configuration (A), the ratio T _A / T _B is 1.30 or more. The fixable temperature range of the toner having such a ratio T _A / T _B of 1.30 or more tends to be widened. The toner having the configuration (A) is less likely to cause fixing failure (more specifically, offset such as cold offset or hot offset), and is considered to have excellent fixability.

In the toner having the configuration (A), the ratio T _A / T _B is 1.60 or less. In such a toner having a ratio T _A / T _B of 1.60 or less, the compatibility between the amorphous polyester resin and the amorphous polyester resin in the binder resin is hardly lowered, and the dispersibility of the crystalline polyester resin is reduced. Tends to be difficult to decrease. For this reason, in the toner having the configuration (A), it is considered that uneven distribution of the crystalline polyester resin hardly occurs on the surface of the toner particles. In addition, in the toner having the configuration (A), it is considered that aggregation of the crystalline polyester resin in the toner particles hardly occurs.

The toner having the configuration (A) is considered to be excellent in blocking resistance. The ratio T _A / T _B is preferably 1.30 or more and 1.56 or less in order to achieve both toner fixing properties and blocking resistance.

The toner having the configuration (A) has a ratio T _C / T _B of 0.90 to 1.10. In a toner having such a ratio T _C / T _B , there is a large difference in sensitivity to the fixing temperature (the time required to start melting after being heated to the fixing temperature) between the crystalline polyester resin and the amorphous polyester resin. Therefore, the melting of the toner tends to be promoted. For this reason, the toner having the configuration (A) is considered to be excellent in fixability (particularly, low-temperature fixability).

The configuration (B) is useful for improving the fixing property of the toner. The inventor is excellent in fixing property and blocking resistance by setting the ratio (P _L / P _H ) of the intensity P _L of the low angle peak to the intensity P _H of the high angle peak to 1.00 or more and 2.00 or less. It has been found that a toner can be obtained. The high angle peak is considered to be derived from a crystalline polyester resin (for example, crystalline polyester resin C). The low-angle peak is considered to originate from a mixed portion of a crystalline polyester resin (for example, crystalline polyester resin C) and an amorphous polyester resin (for example, amorphous polyester resin A and amorphous polyester resin B). .

  In the toner having the configuration (A), it is considered that uneven distribution of the crystalline polyester resin hardly occurs on the surface of the toner particles. In addition, in the toner having the configuration (A), it is considered that aggregation of the crystalline polyester resin in the toner particles hardly occurs. For this reason, the toner having the configuration (A) tends to have excellent charging stability and filming resistance.

In order to further improve the blocking resistance, filming resistance, and charging stability of the toner, it is preferable to control the crystal state and dispersion state of the crystalline polyester resin C. Specifically, it is preferable that the toner further has the following configuration (C) in addition to the above configurations (A) and (B).
Configuration (C): The crystalline polyester resin C exists as a domain in the binder resin. In the dispersion diameter distribution on the basis of the number of domains in the binder resin, the dispersion diameter of the 99th domain in total from the smaller dispersion diameter is 1.0 μm or less.

  The presence of the crystalline polyester resin C as a domain in the binder resin can be confirmed by the SPM image of the cross section of the toner particle. This SPM image can be obtained using a scanning probe microscope (for example, “SPI3800N (probe station)” and “SPA400 (multifunctional unit)” manufactured by Hitachi High-Technology Corporation). The configuration (C) will be described with reference to FIG. The image shown in FIG. 1 is an image obtained by photographing a cross section of toner particles contained in the toner according to the present embodiment with a scanning probe electron microscope (SPM). In the SPM image of FIG. 1, a region having a relatively high brightness (for example, a region indicated by symbol C) indicates the crystalline polyester resin C. Regions with relatively low brightness indicate amorphous polyester resins A and B. Furthermore, the dispersion diameter of the domain can be measured from the obtained SPM image. Here, the dispersion diameter is the maximum length of the domain in the SPM image. A number-based dispersion diameter distribution is created from the obtained plurality of dispersion diameters, and the dispersion diameter of the 99th number-% domain can be obtained. Details of the method for measuring the dispersion diameter of the domain will be described later.

  When the dispersion diameter of the 99th number% domain is 1.0 μm or less, the aggregation of the crystalline polyester resin C in the toner particles and the uneven distribution of the crystalline polyester resin C on the surface of the toner particles tend to be suppressed. It is in. For this reason, it is considered that the toner having the configuration (C) is excellent in blocking resistance and charging stability even during long-time printing. The dispersion diameter of the 99th number domain is more preferably 0.28 μm or more and 0.59 μm or less, and further preferably 0.35 μm or more and 0.53 μm or less. Examples of a method for controlling the dispersion diameter of the 99% number of domains include a method in which the toner core obtained after melting and kneading is subjected to a heat treatment to crystallize the domains in the toner core.

In order to further improve the blocking resistance or charging stability of the toner, it is preferable that the toner further has the following configuration (D) in addition to the above configurations (A) and (B).
Configuration (D): The intensity P _L and the intensity P _H satisfy Expression (4).
_{1.21 ≦ P L / P H ≦} 1.73 ··· (4)

In order to further improve the fixing property of the toner, the toner preferably further has the following configuration (E) in addition to the above configurations (A) and (B).
Configuration (E): The softening point T _B and the softening point T _C satisfy Expression (5). The intensity P _L and the intensity P _H satisfy Expression (6).
1.00 ≦ T _C / T _B ≦ 1.10 (5)
1.55 ≦ P _L / P _H ≦ 1.69 (6)

  The toner may be used as a one-component developer. Further, a two-component developer may be prepared by mixing toner with a desired carrier.

  Hereinafter, the toner particles will be described. Acrylic and methacrylic are sometimes collectively referred to as “(meth) acrylic”. In addition, a compound and a derivative thereof may be generically named by adding “system” after the compound name. When the name of a polymer is expressed by adding “system” after the compound name, it means that the repeating unit of the polymer is derived from the compound or a derivative thereof.

[1. Toner particles]
The toner particles include a binder resin. In addition to the binder resin, the toner particles may include an internal additive (for example, a colorant, a release agent, a charge control agent, or a magnetic powder), or an external additive. Hereinafter, the binder resin, the colorant, the release agent, the charge control agent, the magnetic powder, and the external additive will be described.

(1-1. Binder resin)
The binder resin includes an amorphous polyester resin A, an amorphous polyester resin B, and a crystalline polyester resin C.

<1-1-1. Crystalline polyester resin C>
The crystalline polyester resin C is obtained, for example, by condensation polymerization or co-condensation polymerization of an alcohol component and a carboxylic acid component. A divalent or trivalent or higher alcohol can be used as the alcohol component. Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, di1,2-propanediol, polyethylene glycol, poly1,2-propanediol, or polytetramethylene glycol Bisphenols such as bisphenol A, hydrogenated bisphenol A, polyoxyethylene bisphenol A, or polyoxypropylene bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythris Tol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butane Triol, trimethylol ethane, trimethylol propane, or trivalent or higher alcohols such as 1,3,5-trihydroxymethylbenzene may be mentioned.

  Among these alcohol components, since crystallization of the polyester resin is easily promoted, aliphatic diols having 2 to 8 carbon atoms are preferable, and α, ω-alkanediols having 2 to 8 carbon atoms are preferable. More preferred is 1,4-butanediol or 1,6-hexanediol.

  In order to obtain the crystalline polyester resin C, the proportion of the aliphatic diol having 2 to 10 carbon atoms in the alcohol component is preferably 80 mol% or more, and more preferably 90 mol% or more. Similarly, the content of the component (single compound) contained in the largest amount in the alcohol component is preferably 70 mol% or more, more preferably 90 mol% or more, and 100 mol%. Most preferred.

  As the carboxylic acid component, a divalent or trivalent or higher carboxylic acid can be used. Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, alkyl succinic acid or alkenyl succinic acid (e.g. n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, divalent carboxylic acids such as n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid or isododecenyl succinic acid); 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5 , 7-Naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Trivalent or higher carboxylic acids such as methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, or empole trimer acid can be mentioned. These divalent or trivalent or higher carboxylic acid components may be transformed into an ester-forming derivative such as a carboxylic acid halide, a carboxylic acid anhydride, or a lower alkyl ester. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  Among these carboxylic acid components, an aliphatic dicarboxylic acid having 2 to 16 carbon atoms is preferable because α-ω has 2 to 16 carbon atoms. Alkanedicarboxylic acid is more preferred. The carboxylic acid component may further contain a monovalent carboxylic acid. Examples of the monovalent carboxylic acid include stearic acid.

  In order to obtain the crystalline polyester resin C, the aliphatic dicarboxylic acid having 2 to 16 carbon atoms in the carboxylic acid component is preferably 70 mol% or more, and more preferably 90 mol% or more. Similarly, the content of the component (single compound) contained in the largest amount in the carboxylic acid component is preferably 70 mol% or more, more preferably 90 mol% or more, and 100 mol%. Is most preferred.

  In the present specification, “crystalline” as shown in “crystalline polyester resin” indicates that a differential endothermic change has a clear endothermic peak in differential scanning calorimetry (DSC). Specifically, “crystallinity” means that the half-value width of the endothermic peak when measured at a heating rate of 10 ° C./min is 15 ° C. or less. On the other hand, a polyester resin in which the half-value width of the endothermic peak exceeds 15 ° C. or a polyester resin in which no clear endothermic peak is observed means amorphous (amorphous).

  Further, by measuring the hardness of the cross section of the toner particles using a scanning probe microscope (for example, “SPI3800N (probe station), SPA400 (multifunctional unit)” manufactured by Hitachi High-Technology Corporation), the crystallinity is measured. It can be easily confirmed that it is a resin. When the hardness of the cross section of the toner particles is measured, a relatively soft region can be confirmed as a region where the crystalline polyester resin C exists. Moreover, a comparatively hard area | region can be confirmed with the area | region where the crystalline polyester resin C, the amorphous polyester resin A, and the amorphous polyester resin B are mixed.

  The content of the crystalline polyester resin C is preferably 1 part by mass or more and 15 parts by mass or less, and more preferably 5 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the toner particles. When the content of the crystalline polyester resin is 1 part by mass or more and 15 parts by mass or less, the low-temperature fixability of the toner is improved and the toner is difficult to be negatively charged.

<1-1-2. Amorphous polyester resins A and B>
The amorphous polyester resin will be described. When preparing an amorphous polyester resin, it is necessary to suppress crystallization of the obtained polyester resin. The method for suppressing crystallization of the polyester resin is not particularly limited, and examples of general crystallization suppressing methods include the following methods (1) to (3).

  Method (1): A method in which only a small amount of alcohol and carboxylic acid that promotes crystallization of the crystalline polyester resin are used or not.

  Method (2): A method of using two or more compounds as alcohol and carboxylic acid.

  Method (3): A method of suppressing crystallization by using an alcohol such as an alkylene oxide adduct of bisphenol A or a carboxylic acid such as an alkyl-substituted succinic acid.

  Among these methods for suppressing crystallization, the method (3) is more preferable because the number of types of monomers is small and the preparation of an amorphous polyester resin is easy. In the method (3), the crystallization is more easily suppressed as the amounts of the alcohol (for example, the alkylene oxide adduct of bisphenol A) and the carboxylic acid (for example, the alkyl-substituted succinic acid) are increased. However, the amount of these monomers used is preferably adjusted as appropriate in consideration of the crystallinity index of the resulting polyester and other physical properties. In addition, an amorphous polyester resin may be used independently and may be used in combination of 2 or more type.

  The content of the amorphous polyester resin is preferably 75 parts by mass or more and 90 parts by mass or less, and more preferably 80 parts by mass or more and 85 parts by mass or less with respect to 100 parts by mass of the toner particles.

(1-2. Internal additive)
<1-2-1. Colorant>
The toner particles may contain a colorant. As the colorant, for example, a known pigment or dye can be used according to the color of the toner. The amount of the colorant to be used is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin.

  The toner particles may contain a black colorant. An example of a black colorant is carbon black. The black colorant may be a colorant that is toned to black using a yellow colorant, a magenta colorant, and a cyan colorant.

  The toner particles may contain a color colorant such as a yellow colorant, a magenta colorant, or a cyan colorant.

  Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, or arylamide compounds. Suitable examples of yellow colorants include C.I. I. Pigment Yellow (3, 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155 168, 174, 175, 176, 180, 181, 191, or 194), naphthol yellow S, Hansa yellow G, or C.I. I. Bat yellow is mentioned.

  Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, or perylene compounds. Suitable examples of magenta colorants include C.I. I. Pigment Red (2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177 184, 185, 202, 206, 220, 221 or 254).

  Examples of cyan colorants include copper phthalocyanine compounds, anthraquinone compounds, or basic dye lake compounds. Suitable examples of cyan colorants include C.I. I. Pigment blue (1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, or 66), phthalocyanine blue, C.I. I. Bat Blue, or C.I. I. Acid blue.

<1-2-2. Release agent>
The toner particles may contain a release agent. The release agent is used, for example, for the purpose of improving the fixing property or offset resistance of the toner. In order to improve the fixing property or offset resistance of the toner, the amount of the release agent used is preferably 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the binder resin. More preferably, it is 20 parts by mass or less.

  Preferable examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax, or aliphatic hydrocarbon wax such as Fischer-Tropsch wax; oxidized polyethylene wax Or an oxide of an aliphatic hydrocarbon wax such as a block copolymer of oxidized polyethylene wax; a plant wax such as candelilla wax, carnauba wax, wood wax, jojoba wax, or rice wax; beeswax, lanolin, or Animal waxes such as whale wax; mineral waxes such as ozokerite, ceresin, or petrolatum; waxes based on fatty acid esters such as montanate wax or castor wax; Such as carnauba wax, part or all of fatty acid esters are de-oxidized waxes.

  In order to improve the compatibility between the binder resin and the release agent, a compatibilizing agent may be added to the toner particles.

<1-2-3. Charge Control Agent>
The toner particles may contain a charge control agent. The charge control agent is used, for example, for the purpose of improving the charging stability or charge rising property of the toner. The toner charge rising property is an index of whether or not the toner can be charged to a predetermined charge level in a short time. Further, the anionic property of the toner core can be enhanced by including a negatively chargeable charge control agent in the toner core.

<1-2-4. Magnetic powder>
The toner particles may contain magnetic powder. Examples of magnetic powders include iron (more specifically, ferrite or magnetite), ferromagnetic metal (more specifically, cobalt or nickel), a compound containing iron and / or ferromagnetic metal (more specifically, In particular, an alloy or the like), a ferromagnetic alloy that has been subjected to a ferromagnetization treatment (more specifically, a heat treatment or the like), or chromium dioxide.

(1-3. External additive)
The toner particles may further have an external additive. Examples of the external additive include fine particles of metal oxide (more specifically, alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, or barium titanate), or silica fine particles. For example, the surface of the external additive may be modified with a coupling agent (specifically, a hydrophobic treatment or a positive charging treatment).

  The number average primary particle diameter of the external additive is preferably 0.01 μm or more and 1.0 μm or less. The amount of the external additive used is preferably 0.5 parts by mass or more and 10 parts by mass or less, more preferably 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner base particles.

[2. Toner production method]
Next, a toner manufacturing method will be described. The method for producing the toner is not particularly limited, but a preferred method for producing the toner according to the present embodiment will be described. The toner manufacturing method includes, for example, a toner base particle preparation step and an external addition step.

(2-1. Toner mother particle production process)
The toner base particle preparation step is a step of, for example, preparing toner base particles containing a binder resin and an internal additive. The toner base particle production step is not particularly limited as long as an internal additive (for example, a colorant, a charge control agent, or a release agent) can be satisfactorily dispersed in the binder resin, and a known method can be appropriately employed. Known methods include, for example, a melt-kneading method and an aggregation method.

  The toner mother particle preparation step by the melt kneading method includes, for example, a mixing step and a kneading step. The mixing step is a step of obtaining a mixture by mixing the binder resin and the internal additive. The kneading step is a step of kneading the obtained mixture while melting to obtain a kneaded product. The toner base particle preparation step by the melt kneading method may further include a pulverization step and a classification step. The pulverization step is a step of pulverizing the obtained kneaded product. In the classification step, the pulverized kneaded product is classified to obtain toner particles having a desired particle size. From the viewpoint of toner mother particle productivity or internal additive dispersibility, the melt-kneading method is preferred.

(2-2. External addition process)
The external addition step is a step of attaching an external additive to the surface of the toner base particles. As a suitable method for attaching the external additive, a toner (for example, FM mixer, Nauter mixer (registered trademark)) is used, under the condition that the external additive is not buried in the surface of the toner base particles. A method of mixing the base particles and the external additive can be mentioned.

  Examples will be described below. Tables 1 and 2 show the toners of Examples 1-7 and the toners of Comparative Examples 1-6 (each electrostatic latent image developing toner). The peak intensity indicates the peak intensity (cps) of the X-ray diffraction peak. The dispersion diameter indicates the dispersion diameter of the crystalline polyester resin C in the binder resin.

Example 1
(Preparation of toner base particles)
As binder resin, amorphous resin A-1 (“Toughton (registered trademark) K-1001” manufactured by Kao Corporation, amorphous polyester resin, T _A = 125 ° C.) 40 parts by mass, amorphous resin B- 1 (“Toughton (registered trademark) K-2001” manufactured by Kao Corporation), 40 parts by mass of an amorphous polyester resin, T _B = 80 ° C., and crystalline resin C-1 (“Toughton (registered trademark) manufactured by Kao Corporation) ) A-1006 ", crystalline polyester resin, T _C = 80 ° C) 10 parts by weight, colorant (" ECR-101 "manufactured by Dainichi Seika Kogyo Co., Ltd.), carnauba wax (Yoyuki Kato Co., Ltd.) 5 parts by mass of “Special Carnauba No. 1”) was mixed for 180 seconds at a rotational speed of 2400 rpm using an FM mixer (“FM-20B” manufactured by Nippon Coke Co., Ltd.). The resulting mixture was melted and kneaded using a twin screw extruder ("PCM-30" manufactured by Ikegai Co., Ltd.) under the conditions of a material supply rate of 5 kg / hour, a shaft rotation speed of 150 rpm, and a cylinder temperature of 150 ° C. did. After cooling the obtained kneaded material, the kneaded material was coarsely pulverized by a pulverizer (“Rohtoplex (registered trademark) 16/8 type” manufactured by Hosokawa Micron Corporation). Subsequently, the obtained coarsely pulverized product was finely pulverized by an impact plate type pulverizer (“Ultrasonic Jet Mill I Type” manufactured by Nippon Pneumatic Industry Co., Ltd.). Subsequently, the obtained coarsely pulverized product was finely pulverized with a pulverizer (“Turbo Mill” manufactured by Freund Turbo). Subsequently, the obtained finely pulverized product was classified with a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.) to obtain toner mother particles. The obtained toner base particles had a volume median diameter (D ₅₀ ) of 8.0 μm.

  100 parts by mass of the obtained toner base particles and 0.5 parts by mass of silica (“REA90” manufactured by Nippon Aerosil Co., Ltd.) were mixed for 5 minutes using a 10 L FM mixer (manufactured by Nippon Coke Industries, Ltd.). The external additive was attached. Thereafter, the toner was sieved using a 200 mesh (aperture 75 μm) sieve to obtain the toner of Example 1.

Example 2
Instead of amorphous resin B-1 (40 parts by mass), amorphous resin B-2 (“Toughton (registered trademark) K-2133” manufactured by Kao Corporation, amorphous polyester resin, T _B = 96 ° C.) , 40 parts by mass), instead of crystalline resin C-1 (10 parts by mass), crystalline resin C-2 (Toughton (registered trademark) A-1011 manufactured by Kao Corporation), crystalline polyester resin , T _C = 88 ° C., 10 parts by mass) The toner of Example 2 was obtained in the same manner as in the toner production method of Example 1.

Example 3
The toner of Example 3 was prepared in the same manner as in the toner production method of Example 1 except that the crystalline resin C-2 (10 parts by mass) was used instead of the crystalline resin C-1 (10 parts by mass). Obtained.

Example 4
Instead of amorphous resin A-1 (40 parts by mass), amorphous resin A-2 (“Toughton (registered trademark) K-1003” manufactured by Kao Corporation, amorphous polyester resin, T _A = 140 ° C. The toner of Example 4 was obtained in the same manner as in the toner production method of Example 2 except that 40 parts by mass) were used.

Example 5
Instead of crystalline resin C-2 (10 parts by mass), crystalline resin C-3 (“Toughton (registered trademark) A-1018” manufactured by Kao Corporation, crystalline polyester resin, T _C = 95 ° C., 10 mass) The toner of Example 5 was obtained in the same manner as in the toner production method of Example 4.

Example 6
Instead of amorphous resin A-1 (40 parts by mass), amorphous resin B-1 (40 parts by mass), and crystalline resin C-1 (10 parts by mass), amorphous resin A-1 ( 42.5 parts by mass), amorphous resin B-1 (42.5 parts by mass), and crystalline resin C-1 (5 parts by mass). The toner of Example 6 was used in the same manner as in the toner production method of Example 1 except that heat treatment was performed at a set temperature of 50 ° C. for 8 hours using “High Speed Vacuum Dryer” manufactured by Earth Technica Co., Ltd. Got.

Example 7
Comparative example to be described later, except that heat treatment was performed at a set temperature of 50 ° C. for 8 hours using a dryer (“High Speed Vacuum Dryer” manufactured by Earth Technica Co., Ltd.) after classification of the toner base particles and before external addition. The toner of Example 7 was obtained in the same manner as the toner manufacturing method of Example 6.

Comparative Example 1
The toner of Comparative Example 1 was obtained in the same manner as the toner of Example 1, except that the amorphous resin B-2 (40 parts by mass) was used instead of the amorphous resin B-1 (40 parts by mass).

Comparative Example 2
The toner of Comparative Example 2 was obtained in the same manner as the toner of Example 3, except that the amorphous resin A-2 (40 parts by mass) was used instead of the amorphous resin A-1 (40 parts by mass).

Comparative Example 3
Instead of amorphous resin B-2 (40 parts by mass), amorphous resin B-3 (“Toughton (registered trademark) K-2136” manufactured by Kao Corporation, amorphous polyester resin, T _B = 125 ° C., The toner of Comparative Example 3 was obtained in the same manner as the toner of Example 4 except that 40 parts by mass) was used.

Comparative Example 4
The toner of Example 4 was prepared in the same manner as in the toner production method of Example 1 except that the crystalline resin C-3 (10 parts by mass) was used instead of the crystalline resin C-1 (10 parts by mass). Obtained.

Comparative Example 5
Instead of amorphous resin A-1 (40 parts by mass), amorphous resin B-1 (40 parts by mass), and crystalline resin C-1 (10 parts by mass), amorphous resin A-1 ( 42.5 parts by mass), amorphous resin B-1 (42.5 parts by mass), and crystalline resin C-1 (5 parts by mass) were used in the same manner as in the toner production method of Example 1. Thus, a toner of Comparative Example 5 was obtained.

Comparative Example 6
Instead of amorphous resin A-1 (40 parts by mass), amorphous resin B-1 (40 parts by mass), and crystalline resin C-1 (10 parts by mass), amorphous resin A-1 ( Comparative Example 5 in the same manner as in the toner production method of Example 1, except that 30 parts by mass), amorphous resin B-1 (30 parts by mass), and crystalline resin C-1 (30 parts by mass) were used. No toner was obtained.

[Evaluation method]
The evaluation method of each sample (the toners of Examples 1 to 7 and the toners of Comparative Examples 1 to 6) is as follows.

(Softening point)
The softening point was measured as follows. Amorphous polyester resin A, amorphous polyester resin B, or crystalline polyester resin C was used as a sample for evaluation. The sample for evaluation was allowed to stand for 12 hours or more in an environment of normal temperature and high humidity (temperature: 23 ° C. ± 1 ° C., humidity: 50% RH ± 5% RH) to condition the binder resin. Subsequently, 1.1 parts by mass of the conditioned resin was pressure-molded at a pressure of 10 MPa using a pressure molding machine to produce a cylindrical molded sample having a diameter of 1 cm. Subsequently, the molded sample was subjected to a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation) in a normal temperature and high humidity environment (temperature: 23 ° C. ± 5 ° C., humidity 50% RH ± 10% RH). Used, the binder resin was melted and flowed out under predetermined conditions. Here, the predetermined conditions were a used nozzle of 1 mmφ × 10 mm, a load of 294 N (30 Kgf), a preheating time of 5 minutes, and a heating rate of 3 ° C./minute. In this way, the S-curve (horizontal axis: temperature, vertical axis: stroke) of the binder resin was measured. The softening point of the binder resin was read from the obtained S-shaped curve. Specifically, in the obtained S-shaped curve, when the maximum stroke value is S ₁ and the baseline stroke value on the low temperature side is S ₂ , the stroke value in the S-shaped curve is “(S ₁ + S _The temperature at 2 ° / 2 ”(° C.) was defined as the softening point of the binder resin.

(X-ray diffraction spectrum)
The sample (toner) was filled in a sample holder of an X-ray diffractometer (“RINT (registered trademark) 1100” manufactured by Rigaku Corporation). An X-ray diffraction spectrum was measured under the following conditions.
X-ray tube: Cu
Tube voltage: 40 kV
Tube current: 30 mA
CuKα characteristic X-ray wavelength: 1.542 mm
Measurement range (2θ): 20 ° to 25 ° Scanning speed: 10 ° / min

Of the peaks present in the range of the Bragg angle 19 ° to 25 ° of the obtained X-ray diffraction spectrum, the first peak having the maximum intensity and the second peak having the second highest intensity were determined. Here, the intensity means the frequency (cps), not the integrated value of the peak. Of the obtained first and second peaks, the intensity P _{H of} the peak located on the high angle side and the intensity P _L of the peak located on the low angle side were read. Moreover, the peak (Bragg angle) where the peak located in the high angle side and the peak located in the low angle side existed was read.

(Dispersion diameter)
A sample (toner) and a resin (room temperature curable epoxy resin) were mixed to prepare a mixture in which the sample was sufficiently dispersed. The obtained mixture was allowed to stand for 2 days in an environment at a temperature of 40 ° C. to be cured. As a result, a solidified product in which the toner was embedded was obtained. Using a microtome (“EMUC6” manufactured by Leica Co., Ltd.), a sample flake was prepared from the cured product.

Using a scanning probe microscope (“SPI3800N (probe station)” and “SPA400 (multifunctional unit)” manufactured by Hitachi High-Technology Corporation), the sample flakes were measured under the following conditions. A cross-sectional SPM image was obtained.
Measurement mode: Micro viscoelastic mode (VE-AFM)
Scanner: FS-100N (in-plane 100 μm, vertical 15 μm)
Micro cantilever: Silicon nitride SN-AF01 (spring constant 0.08 N / m)
Measurement environment: Room temperature (25 ° C. ± 5 ° C.), under atmospheric vibration frequency: 3 kHz to 5 kHz
Excitation amplitude: 4 nm to 6 nm
Four screens of amplitude A, Asin δ, and Acos δ were measured in a measurement area of 20 μm × 20 μm. A domain image of the crystalline resin dispersed in the sample (toner) was obtained from the obtained phase image. Note that the hardness of the cross section of the toner particles could be measured by the above measuring apparatus and measuring conditions.

  The obtained image was binarized using image analysis software (“WinROOF” manufactured by Mitani Corporation). The longest diameter of the crystalline resin domain was measured from the binarized image. In the number-based dispersion diameter distribution obtained from the longest diameter, a 99-number-% domain dispersion diameter was obtained from the smaller dispersion diameter.

(Toner blocking resistance)
Evaluation of toner blocking resistance was performed as follows. 3 g of a sample (toner) was allowed to stand in a plastic bottle adjusted to 60 ° C. for 3 hours. Subsequently, the sample that was allowed to stand was sieved with a vibrating sieve set with a 200-mesh sieve for 30 seconds and sieved. After sieving, the mass of the sample remaining on the sieve was measured. From the mass of the sample before sieving and the mass of the sample remaining on the sieving after sieving, the ratio of the toner passing through the mesh (passage (mass%)) was calculated according to Equation (7).
Passage (mass%) = (mass of sample remaining on sieve / mass of sample before sieving) × 100 (7)

From the calculated pass degree, the blocking resistance of the toner was evaluated according to the following criteria. ◎ and ○ were accepted.
A (very good): The degree of passage was 95% by mass or more.
○ (Good): The degree of passage was 90% by mass or more and less than 95% by mass.
Δ (Normal): The degree of passage was 80% by mass or more and less than 90% by mass.
X (Poor): The degree of passage was less than 80% by mass.

(Toner fixability)
Cu-Zn-based ferrite carrier (Powder Tech Co., Ltd., volume resistivity 1 × 10 ⁷ Ωcm, saturation magnetization 70 emu / g, particle diameter 35 μm) xylene of fluororesin (Soken Chemical “LF-40”) The Cu—Zn ferrite carrier coated with a solution (solid content concentration 5%) and then coated with a fluororesin was fired at 220 ° C. for 1 hour. Thereafter, the obtained fired product was cooled and crushed to obtain a resin-coated ferrite carrier having a resin coating amount of 20% by mass. The obtained resin-coated ferrite carrier and the sample (toner) were mixed for 30 minutes using a ball mill to prepare a developer for evaluation (two-component developer) having a toner concentration of 10% by mass.

A color printer (“FS-C5400DN” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. This evaluation machine is a color printer in which the fixing device is modified to a Roller-Roller type heat and pressure type. Using an evaluation machine, on a 90 g / m ² paper (A4 size evaluation paper) under the conditions of a linear speed of 200 mm / second, a nip passage time of 40 milliseconds, a nip width of 8 mm, and a toner loading of 1.0 mg / cm ^2. A solid image having a size of 25 mm × 25 mm and a printing rate of 100% was formed. Subsequently, the paper on which the image was formed was passed through a fixing device to form an image. The obtained image after fixing was folded and reciprocated 5 times with a 1 kg weight, and it was confirmed whether the width of the crease peeled was less than 1 mm. The setting range of the fixing temperature was 100 ° C. or higher and 200 ° C. or lower. Specifically, the fixing temperature of the fixing device is gradually increased from 100 ° C., and the minimum temperature (minimum fixing temperature) at which the toner (solid image) can be fixed on the paper without causing the so-called cold offset and the so-called hot offset The maximum temperature (maximum fixing temperature) at which toner (solid image) can be fixed on paper without occurrence was determined.

From the obtained minimum fixable temperature and the maximum fixable temperature, the toner fixability was evaluated based on the following evaluation criteria. When the minimum fixable temperature was 140 ° C. or lower, it was determined that the temperature was further excellent. The occurrence of hot offset was confirmed by the presence or absence of transfer to the transfer paper on the second round of the heat roller. Of the temperatures that do not transfer to the transfer paper on the second round of the heat roller, the highest temperature was set as the maximum fixable temperature, and when the temperature was 155 ° C. or higher, OK was determined. Fixability was evaluated based on the following criteria.
A (very good): The low-temperature fixable temperature was 135 ° C. or lower, and the high-temperature fixable temperature was 160 ° C. or higher.
○ (Good): The low-temperature fixable temperature was higher than 135 ° C and 140 ° C or lower, and the high-temperature fixable temperature was 155 ° C or higher. Alternatively, the low-temperature fixable temperature was 140 ° C. or lower, and the high-temperature fixable temperature was 155 ° C. or higher and lower than 160 ° C.
X (Poor): The low-temperature fixable temperature was over 140 ° C, or the high-temperature fixable temperature was less than 155 ° C.

(Charge stability of toner)
A two-component developer similar to the two-component developer used for fixing the toner was prepared. A color printer (“TASKalfa500ci” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. The developer for evaluation was put into the developing device of the evaluation machine, and the sample (toner) was put into the toner container of the evaluation machine. In the evaluation machine, the voltage (ΔV) between the developing sleeve and the magnet roll was set to 250 V, and the alternating voltage (Vpp) applied to the magnet roll was set to 2.0 kV. Using an evaluation machine, a solid image with a printing rate of 100% and a blank paper image with a printing rate of 0% were formed every 1000 sheets printed at a printing rate of 4% in a room temperature (25 ° C., 50% RH) environment. The image density of the formed solid image was measured using a reflection densitometer (“SpectroEye (registered trademark) LT” manufactured by Sakata Inx Engineering Co., Ltd.). Similarly, a blank paper image was output and the fog density was measured. For the measurement of the image density and the fog density, an image was output every 1000 sheets and evaluated up to 5000 sheets. From the image density and the fog density, the charging stability of the toner was evaluated according to the following criteria.
A (very good): The image density was 1.20 or more at the time of 5000 sheets, and the fog density was less than 0.010.
○ (Good): The image density was 1.20 or more at the time of 4000 sheets. Further, at the time of 5000 sheets, the image density was less than 1.20, or the fog density was 0.010 or more.
X (Poor): The image density was less than 1.20 at the time of 4000 sheets, or the fog density was 0.010 or more.

(Toner filming resistance)
A two-component developer similar to the two-component developer used for fixing the toner was prepared. A color printer (“TASKalfa500ci” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. The developer for evaluation was put into the developing device of the evaluation machine, and the sample (toner) was put into the toner container of the evaluation machine. In the evaluation machine, the voltage between the developing sleeve and the magnet roll was set to 250 V, and the alternating voltage (Vpp) applied to the magnet roll was set to 2.0 kV. Using an evaluator, 5000 images were continuously output at a printing rate of 4% in a room temperature (25 ° C., 50% RH) environment. After outputting 5000 images, a solid image with a printing rate of 100% was output on the entire surface of A4, and a halftone image with a printing rate of 50% was output on the entire surface of A4. The obtained solid image and halftone image were visually checked for color points and missing images. Further, after the solid image and the halftone image were formed, it was visually confirmed whether or not the toner component adhered to the surface of the photoreceptor. Based on the result of visual observation, the filming resistance of the toner was evaluated according to the following criteria. ○ was accepted.
○ (Good): There were no color points or image omission in the solid image and halftone image, and no toner component deposits were present on the surface of the photoreceptor.
X (Poor): There were color spots or image omission in the solid image and halftone image, or toner component deposits existed on the surface of the photoreceptor.

The toners according to Examples 1 to 7 were toners having the above-described configurations (A) and (B). Specifically, the toners according to Examples 1 to 7 each contained an amorphous polyester resin A, an amorphous polyester resin B, and a crystalline polyester resin C. The softening point T _A , the softening point T _B, and the softening point T _C satisfied Expressions (1) and (2). Further, in the CuKα characteristic X-ray diffraction spectrum, the Bragg angle has a first peak and a second peak in a range of 19 ° or more and 25 ° or less, and of the first peak and the second peak, The intensity P _H and the intensity P _L of the low angle side peak satisfied Expression (3).

  The toners of Examples 1 to 7 each had a filming resistance evaluation result of ◯, the blocking resistance evaluation result of ◎ or ◯, and the fixability evaluation result of ◎ or ◯. The toners of Comparative Examples 1 to 6 showed Δ or x in at least one of the evaluation results of filming resistance, fixing property and blocking resistance.

  Therefore, the toners according to Examples 1 to 7 were superior to the toners according to Comparative Examples 1 to 6, respectively, in filming resistance, blocking resistance and fixability.

  In addition, the toners of Examples 1 to 7 had an evaluation result of charging stability of ◎ or ◯. The toners according to Examples 1 to 7 were also excellent in charging stability.

The toners of Examples 1 to 4 and Example 6 were toners having the above-described configuration (D). Specifically, in the toners of Examples 1 to 4 and Example 6, the strength P _L and the strength P _H satisfied Expression (4). In the toner of Example 4, the evaluation result of blocking resistance was “◎”. In the toners of Examples 1 to 3 and Example 6, the evaluation results of the charging stability were ◎. The toners of Examples 1 to 4 and Example 6 were further superior to the toners of Examples 5 and 7 in terms of blocking resistance or charging stability.

The toners of Example 1 and Example 3 were toners having the above-described configuration (E). Specifically, in the toners of Examples 1 and 3, satisfy the softening point T _B softening point T _C are satisfied Equation (5), and the intensity P _L and intensity P _H Equation (6) It was. For the toners of Example 1 and Example 3, the evaluation result of fixability was “◎”. The toners of Examples 1 and 3 were more excellent in terms of fixability than the toners of Examples 2 and 4-7.

  The toner for developing an electrostatic latent image according to the present invention can be used for forming an image in, for example, a copying machine or a printer.

C Crystalline polyester resin

Claims (6)

An electrostatic latent image developing toner comprising a plurality of toner particles,
The toner particles include an amorphous polyester resin A, an amorphous polyester resin B, and a crystalline polyester resin C as binder resins.
The softening point T _A of the amorphous polyester resin A, the amorphous polyester softening point and T _B of the resin B, the crystalline polyester resin C softening point T _C and the following formula (1) and (2 )The filling,
The softening point T _A is 125 ° C. or higher and 140 ° C. or lower, the softening point T _B is 80 ° C. or higher and 96 ° C. or lower, and the softening point T _C is 80 ° C. or higher and 95 ° C. or lower.
The blending ratio of the amorphous polyester resin A, the amorphous polyester resin B, and the crystalline polyester resin C is 4: 4: 1.
In the CuKα characteristic X-ray diffraction spectrum, the Bragg angle 2θ has two or more peaks in the range of 19 ° or more and 25 ° or less,
When the peak having the highest intensity among the two or more peaks is represented as a first peak, and the peak having the second largest intensity among the two or more peaks is represented as a second peak, the first peak and the peak The electrostatic latent image developing toner in which the intensity P _{H of} the peak located on the high angle side and the intensity P _{L of} the peak located on the low angle side of the second peak satisfy the following formula (3).
_{1.30 ≦ T A / T B ≦} 1.60 ··· (1)
0.90 ≦ T _C / T _B ≦ 1.10 (2)
1.00 ≦ P _L / P _H ≦ 2.00 (3) The crystalline polyester resin C exists as a domain in the binder resin,
2. The dispersion diameter distribution based on the number of the domains in the binder resin, wherein the dispersion diameter of the 99th domain in total from the smaller dispersion diameter is 1.0 μm or less. Toner for developing electrostatic latent image.   The first peak is the peak having the largest intensity in the range where the Bragg angle 2θ is 19 ° or more and 22 ° or less, and the second peak is the second peak in the range where the Bragg angle 2θ is 22 ° or more and 25 ° or less. The toner for developing an electrostatic latent image according to claim 1, which is a peak having a large intensity. The electrostatic latent image developing toner according to claim 1, wherein the intensity P _L and the intensity P _H satisfy the following formula (4).
_{1.21 ≦ P L / P H ≦} 1.73 ··· (4) The softening point T _B and the softening point T _C satisfy the following formula (5):
The electrostatic latent image developing toner according to claim 1, wherein the intensity P _L and the intensity P _H satisfy the following formula (6).
1.00 ≦ T _C / T _B ≦ 1.10 (5)
1.55 ≦ P _L / P _H ≦ 1.69 (6) The softening point T _A Is 125 ° C. or 140 ° C. or less, and the softening point T _B Is 80 ° C. or 96 ° C. or lower, and the softening point T _C The toner for developing an electrostatic latent image according to claim 1, wherein is 80 ° C., 88 ° C., or 95 ° C. or lower.