JP2017198883A - Method of manufacturing electrostatic latent image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing electrostatic latent image developing toner that has excellent heat-resistant storage properties and electric charge stability, and can form an image of high quality, even when environment changes.SOLUTION: A method of manufacturing toner includes: a toner particle forming process of forming a toner particle 10 by sticking a plurality of external additive particles 14 on a surface of a toner base particle 13; and an exposing process of exposing the toner particle 10 to environment of 30°C or higher in temperature and 55% RH or larger in relative humidity. The exposing process is carried out simultaneously with the toner particle forming process or after the toner particle forming process. An area ratio of a surface region of a toner core 11 having a shell layer 12 to the entire surface region of the toner core 11 of the toner base particle 13 before the external additive particles 14 are stuck in the toner particle forming process is 60-80%. A BET specific surface area of the toner particle 10 when the toner particle 10 after the exposing process is placed in environment where volume absolute humidity is 10.27 g/mfor 24 hours, is 1.30 m/g-3.00 m/g.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a toner for developing an electrostatic latent image.

When an image is formed using an electrostatic latent image developing toner containing a large number of toner particles, the surface shape of the toner particles affects the development and transfer of the toner particles. Therefore, it is desired to reduce the change in the surface shape of the toner particles. In order to reduce the change in the surface shape of the toner particles, it has been studied to suppress the detachment of the external additive from the toner base particles. For example, the electrostatic latent image developing toner described in Patent Document 1 has toner base particles and an external additive. Resin particles having a nonspherical shape having a shape factor (SF) of 1.20 or more and having an outer shell layer on the surface are contained as external additives. The outer shell layer is formed from silica or modified silica. The shape factor of the resin particle as the external additive is calculated by the formula “shape factor (SF) = [(absolute maximum length of particle) ² / (projected area of particle)] × (π / 4)”.

JP 2014-85551 A

  However, in the electrostatic latent image developing toner described in Patent Document 1, the surface shape of the toner particles may change when the environment such as temperature and humidity changes. If the surface shape of the toner particles changes, the heat-resistant storage stability, charging stability and image quality of the electrostatic latent image developing toner may deteriorate.

  The present invention has been made in view of the above problems, and is an electrostatic latent image developing toner that is excellent in heat-resistant storage stability and charging stability and can form a high-quality image even when the environment fluctuates. It aims at providing the manufacturing method of.

The method for producing a toner for developing an electrostatic latent image according to the present invention is a method for producing a toner for developing an electrostatic latent image containing a plurality of toner particles. The toner particles include toner base particles and a plurality of external additive particles provided on the surface of the toner base particles. The toner base particles have a toner core and a shell layer provided on the surface of the toner core. A toner particle forming step of forming the toner particles by attaching a plurality of the external additive particles to the surface of the toner base particles, and exposing the toner particles to an environment having a temperature of 30 ° C. or higher and a relative humidity of 55% RH or higher. Exposure step. The exposing step is performed simultaneously with the toner particle forming step or after the toner particle forming step. The area ratio of the surface area of the toner core in which the shell layer is provided in the entire surface of the toner core in the toner base particles before the external additive particles are attached in the toner particle forming step is 60% or more and 80 % Or less. When the toner particles after the exposure step are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours, the BET specific surface area of the toner particles is 1.30 m ² / g or more and 3.00 m ² / g or less.

  According to the method for producing a toner for developing an electrostatic latent image of the present invention, the electrostatic latent image developing is excellent in heat-resistant storage stability and charging stability and capable of forming a high-quality image even when the environment changes. Toner can be manufactured.

It is sectional drawing which shows the toner particle contained in the toner for electrostatic latent image development manufactured with the manufacturing method which concerns on this invention.

  Embodiments of the present invention will be described below. However, the present invention is not limited to the following embodiments. The present invention 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. In the drawings, each component is schematically shown for easy understanding. The thickness, length, number, shape, dimension, and the like of each illustrated component are examples, and are not particularly limited.

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

Hereinafter, the average value means a number average value unless otherwise specified. In addition, an evaluation value (a value indicating a shape or physical property) regarding a powder (for example, toner, toner particles, external additive particles, and toner base particles described later) means a number average value unless specified. . The number average value is a value obtained by dividing the sum of the values measured for a considerable number of measurement objects by the measured number. Furthermore, the particle diameter of the powder is the equivalent-circle diameter of primary particles measured using an electron microscope unless otherwise specified. The equivalent circle diameter is the diameter of a circle having the same area as the projected area of the particles. The volume median diameter D ₅₀ is a median diameter calculated on a volume basis using a Coulter counter method.

  The present embodiment relates to a method for producing a toner for developing an electrostatic latent image (hereinafter sometimes referred to as toner). According to the toner manufacturing method of the present embodiment, it is possible to manufacture a toner that is excellent in heat-resistant storage stability and charging stability and can form a high-quality image even when the environment changes. The reason is presumed as follows.

  The toner produced by the production method of the present embodiment is a toner core surface area (hereinafter referred to as a toner core surface area) of the toner base particles before the external additive particles are adhered in the toner particle forming step (hereinafter referred to as a toner core surface area). The area ratio may be 60% or more and 80% or less. A part of the surface of the toner core is not covered with the shell layer. For this reason, some of the components contained in the toner core (hereinafter sometimes referred to as toner core components) from the surface region of the toner core not provided with the shell layer (hereinafter sometimes referred to as uncoated regions) May elute. When the toner core component is eluted, the surface shape of the toner particles may change, and the heat resistant storage stability, charging stability, and image quality of the toner may deteriorate.

  Here, the manufacturing method of this embodiment includes an exposure step. In the exposure step, the toner particles are exposed to an environment having a temperature of 30 ° C. or higher and a relative humidity of 55% RH or higher. Thereby, a part of the toner core component is eluted from the uncoated region of the toner core. When a part of the toner core component is eluted in the exposure process, the following advantages are obtained.

  The first advantage is as follows. By changing the surface shape of the toner particles in a high-temperature and high-humidity environment at the time of production, there is a tendency that the surface shape of the toner particles can be further prevented from changing during storage, transportation, and image formation. The toner core component once eluted in the high temperature and high humidity environment will be eluted even if it is placed in the high temperature and high humidity environment again after being placed in the normal temperature and normal humidity environment or low temperature and low humidity environment. This is because the surface shape of the toner particles is difficult to change.

  The second advantage is as follows. In the toner manufactured by the manufacturing method of the present embodiment, a plurality of external additive particles adhere to the surface of the toner base particles. For example, the external additive particles adhere to the surface of the shell layer and the surface of the uncoated region of the toner core. When a part of the toner core component is eluted from the uncoated region of the toner core in the exposure process, the external additive particles and the toner core adhering to the surface of the uncoated region of the toner core are firmly attached via the eluted toner core component. . Further, the external additive particles adhering to the surface of the uncoated region of the toner core are firmly attached via the eluted toner core component. As a result, the external additive particles are hardly detached from the toner base particles, and the surface shape of the toner particles is difficult to change.

  With such first and second advantages, the change in the surface shape of the toner particles can be reduced even when the environment changes. As a result, it is considered that a toner that is excellent in heat-resistant storage stability and charging stability and can form a high-quality image can be manufactured even when the environment fluctuates.

<1. Toner>
Next, the toner manufactured by the manufacturing method of this embodiment will be described. The toner manufactured by the manufacturing method of the present embodiment includes a plurality of toner particles. The toner is an aggregate (powder) of a plurality of toner particles.

  With reference to FIG. 1, the structure of the toner particle 10 contained in the toner manufactured by the manufacturing method of the present embodiment will be described. FIG. 1 is a cross-sectional view showing toner particles 10. The toner particles 10 include toner base particles 13 and a plurality of external additive particles 14. A plurality of external additive particles 14 are provided on the surface of the toner base particles 13. The toner base particles 13 have a toner core 11 and a shell layer 12. The shell layer 12 is provided on the surface of the toner core 11. The toner core 11 is covered with a shell layer 12. The external additive particles 14 adhere to the surface of the shell layer 12 or the surface of the uncoated region of the toner core 11. A part (for example, the bottom part) of the external additive particles 14 may be buried in the uncoated region of the shell layer 12 or the toner core 11. In addition, the area | region shown with the oblique line in FIG. 1 shows the shell layer 12, the area | region shown with the dot has shown the external additive particle | grains 14, and a part of code | symbol is abbreviate | omitted. The structure of the toner particles 10 included in the toner has been described above with reference to FIG.

(BET specific surface area)
The toner particles have a BET specific surface area (A _N ) of 1.30 m ² / g or more when the toner particles after the exposure step described below are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours. 00 m ² / g or less. When the BET specific surface area (A _N ) of the toner particles is 1.30 m ² / g or more, the image density of the formed image tends to be improved. When the BET specific surface area (A _N ) is 3.00 m ² / g or less, the charging stability of the toner tends to be improved.

The BET specific surface area (A _N ) of the toner particles can be adjusted, for example, by changing the content of the external additive particles with respect to the mass of the toner base particles. However, even if the content of the external additive particles with respect to the mass of the toner base particles is the same, the BET specific surface area (A _N ) of the toner particles varies depending on the degree of adhesion between the toner base particles and the external additive particles. Sometimes. For example, when the degree of adhesion of the external additive particles to the toner base particles is small and the contact area between the toner base particles and the external additive particles is small, the BET specific surface area (A _N ) of the toner particles increases. On the other hand, when the degree of adhesion of the external additive particles to the toner base particles is large and the contact area between the toner base particles and the external additive particles is large, the BET specific surface area (A _N ) of the toner particles is small. Therefore, by controlling the BET specific surface area of the toner particles (A _N) below 1.30 m ² / g or more 3.00 m ² / g, easily control the change in the surface shape of the toner particles.

The BET specific surface area (A _N ) of the toner particles when the toner particles after the exposure step are placed in an environment having a volume absolute humidity of 10.27 g / m ³ for 24 hours, and the toner particles after the exposure step have a volume absolute humidity of The absolute value of the difference (A _H −A _N ) from the BET specific surface area (A _H ) of the toner particles when placed in an environment of 26.99 g / m ³ for 24 hours is 0.00 m ² / g or more and 0.00. It is preferably 30 m ² / g or less. That is, it is preferable to satisfy the expression “0.00 m ² / g ≦ | A _H −A _N | ≦ 0.30 m ² / g”. When the absolute value of the difference (A _H −A _N ) is 0.00 m ² / g or more and 0.30 m ² / g or less, the environment is a high-temperature and high-humidity environment (for example, the volume absolute humidity is 26.99 g / m ³ ). ), The surface shape of the toner particles hardly changes. For example, when the toner core components are gradually eluted from the toner core in a high temperature and high humidity environment, the contact area between the toner base particles and the external additive particles increases, and the BET specific surface area (A _H ) of the toner particles decreases. Can be suppressed. Therefore, charging stability of the toner in a high temperature and high humidity environment can be improved. Furthermore, even when an image is formed in a high-temperature and high-humidity environment, an image with stable image density and color difference can be formed.

The BET specific surface area (A _N ) of the toner particles when the toner particles after the exposure step are placed in an environment having a volume absolute humidity of 10.27 g / m ³ for 24 hours, and the toner particles after the exposure step have a volume absolute humidity of The absolute value of the difference (A _L −A _N ) from the BET specific surface area (A _L ) of the toner particles when placed in an environment of 0.94 g / m ³ for 24 hours is 0.00 m ² / g or more and 0.00. It is preferably 30 m ² / g or less. That is, it is preferable to satisfy the expression “0.00 m ² / g ≦ | A _L −A _N | ≦ 0.30 m ² / g”. When the absolute value of the difference (A _L −A _N ) is 0.00 m ² / g or more and 0.30 m ² / g or less, a low temperature and low humidity environment (for example, an environment where the volumetric absolute humidity is 0.94 g / m ³ ) Even when toner particles are placed on the toner particles, the surface shape of the toner particles hardly changes. Therefore, even when the environment changes, the heat-resistant storage stability and charging stability of the toner can be improved, and a high-quality image can be formed.

  The BET specific surface area of the toner particles is measured using, for example, a BET specific surface area measuring device (for example, “Fully Automatic Specific Surface Area Measuring Device Macsorb (registered trademark) HM MODEL-1208” manufactured by Mountec Co., Ltd.). The BET specific surface area of the toner particles is a number average value measured using toner (many toner particles) as a sample.

Volumetric absolute humidity (Volume Humidity (VH), unit: g / m ³ ) is a mass per volume of water vapor contained in the atmosphere. Volume absolute humidity is the amount of water vapor per volume. The volumetric absolute humidity of the environment where the toner particles are placed is calculated by the following equation (1) from the temperature and relative humidity of the environment where the toner particles are placed. The formula (1) is derived from the following formulas (2), (3) and (4).

y = 6.11 × [10 ^ ((7.5 × p) / (237.3 + p))] × q × 18 / (8.314 × (273.15 + p)) (1)
r = 6.11 × 10 ^ ((7.5 × p) / (237.3 + p)) (2)
s = r × (q / 100) (3)
y = s × 100 × 18 / (8.314 × (273.15 + p)) (4)

In formulas (1) to (4), “^” indicates a power. For example, “10 ^ n” indicates 10 to the power of n. Moreover, in formula (1)-(4), y, p, q, r, and s respectively represent the following.
y: volumetric absolute humidity of the environment where the toner particles are placed (unit: g / m ³ )
p: temperature of the environment where the toner particles are placed (unit: ° C.)
q: relative humidity of the environment where the toner particles are placed (unit:% RH)
r: Saturated water vapor pressure (unit: hPa) in the environment where the toner particles are placed
s: Water vapor pressure of the environment where the toner particles are placed (unit: hPa)

For example, when the temperature in the environment where the toner particles are placed is 23 ° C. and the relative humidity is 50% RH, the absolute volumetric humidity of the environment is 10.27 g / m ³ . When the temperature in the environment where the toner particles are placed is 32 ° C. and the relative humidity is 80% RH, the volumetric absolute humidity of the environment is 26.99 g / m ³ . When the temperature in the environment where the toner particles are placed is 10 ° C. and the relative humidity is 10% RH, the absolute volumetric humidity of the environment is 0.94 g / m ³ .

<1-1. Toner mother particles>
The toner base particles have a toner core and a shell layer provided on the surface of the toner core. First, preferred examples of the resin contained in the toner core and the resin contained in the shell layer will be described.

(Suitable resin)
A thermoplastic resin is preferable as the resin contained in the toner core and the resin contained in the shell layer. Examples of the thermoplastic resin include a styrene resin, an acrylic resin (more specifically, an acrylic ester polymer or a methacrylic ester polymer), an olefin resin (more specifically, a polyethylene resin or Polypropylene resin, etc.), vinyl resin (more specifically, vinyl chloride resin, polyvinyl alcohol, vinyl ether resin or N-vinyl resin), polyester resin, polyamide resin, styrene-acrylic acid resin, styrene-butadiene resin, or A urethane resin is mentioned.

  The thermoplastic resin can be obtained by condensation polymerization or co-condensation polymerization of one or more thermoplastic monomers (more specifically, an acrylic acid monomer or a styrene monomer). The thermoplastic monomer is a monomer that becomes a thermoplastic resin by homopolymerization.

  The styrene-acrylic acid resin is a copolymer of one or more styrene monomers and one or more acrylic monomers. In order to synthesize a styrene-acrylic acid resin, for example, a styrene monomer and an acrylic acid monomer as shown below can be suitably used. By using an acrylic acid monomer, a carboxyl group can be introduced into the styrene-acrylic acid resin. Further, by using a monomer having a hydroxyl group (more specifically, p-hydroxystyrene, m-hydroxystyrene, (meth) acrylic acid hydroxyalkyl ester, or the like), the hydroxyl group can be introduced into the styrene-acrylic acid resin. The acid value of the styrene-acrylic acid resin obtained can be adjusted by adjusting the amount of the acrylic acid monomer used. Moreover, the hydroxyl value of the styrene-acrylic acid-type resin obtained can be adjusted by adjusting the usage-amount of the monomer which has a hydroxyl group.

  Suitable examples of the styrenic monomer include styrene, α-methylstyrene, p-hydroxystyrene, m-hydroxystyrene, vinyltoluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene or p-ethylstyrene is mentioned.

  Preferable examples of the acrylic acid monomer include (meth) acrylic acid, (meth) acrylic acid alkyl ester or (meth) acrylic acid hydroxyalkyl ester. Suitable examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, and (meth) acrylic. Examples thereof include butyl acid (for example, n-butyl (meth) acrylate, iso-butyl (meth) acrylate) or 2-ethylhexyl (meth) acrylate. Suitable examples of the (meth) acrylic acid hydroxyalkyl ester include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate or (meth) acrylic acid. 4-hydroxybutyl is mentioned.

  The acrylic resin is a polymer of one or more acrylic acid monomers. In order to synthesize an acrylic acid resin, the above-mentioned acrylic acid monomer can be preferably used.

  The polyester resin can be obtained by polycondensation or copolycondensation of alcohol and carboxylic acid. As the alcohol for synthesizing the polyester resin, for example, dihydric alcohols (more specifically, diols or bisphenols) as shown below or trihydric or higher alcohols can be suitably used. As the carboxylic acid for synthesizing the polyester resin, for example, divalent carboxylic acids or trivalent or higher carboxylic acids as shown below can be suitably used. Moreover, when synthesizing the polyester resin, the acid value and the hydroxyl value of the polyester resin can be adjusted by changing the amount of alcohol used and the amount of carboxylic acid used. When the molecular weight of the polyester resin is increased, the acid value and hydroxyl value of the polyester resin tend to decrease.

  Suitable examples of diols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, Examples include 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, or polytetramethylene glycol.

  Preferable examples of bisphenols include bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct or bisphenol A propylene oxide adduct.

  Preferable examples of trihydric or higher alcohols include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butane. Triol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane or 1,3,5-triol Hydroxymethylbenzene is mentioned.

  As preferable examples of the divalent carboxylic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, adipic acid, sebacic acid, azelaic acid, malonic acid Succinic acid, alkyl succinic acid (more specifically, n-butyl succinic acid, isobutyl succinic acid, n-octyl succinic acid, n-dodecyl succinic acid or isododecyl succinic acid, etc.) or alkenyl succinic acid (more specifically, N-butenyl succinic acid, isobutenyl succinic acid, n-octenyl succinic acid, n-dodecenyl succinic acid or isododecenyl succinic acid).

  Preferred examples of the trivalent or higher carboxylic acid include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl) Mention may be made of methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid or empole trimer acid.

  Alcohol and carboxylic acid may be used individually by 1 type, respectively, and may be used in combination of 2 or more type. Furthermore, the carboxylic acid may be derivatized into an ester-forming derivative. Examples of ester-forming derivatives include acid halides, acid anhydrides (eg, trimellitic anhydride) or lower alkyl esters. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

  When a thermoplastic resin is contained in the toner core or shell layer, one type of thermoplastic resin may be used alone, or two or more types may be used in combination. Moreover, you may add a crosslinking agent or a thermosetting resin to a thermoplastic resin. If a cross-linked structure is partially introduced into the binder resin, it is easy to improve the storage stability, form retention, and durability of the toner while ensuring the toner fixability.

  Thermosetting resins that can be used with thermoplastic resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins or cyanate type resins. preferable. One kind of thermosetting resin may be used alone, or two or more kinds may be used in combination.

  Next, the toner core and the shell layer will be described.

<1-1-1. Toner core>
The toner core may contain, for example, one or more of a binder resin, a colorant, a release agent, a charge control agent, and a magnetic powder. However, unnecessary components may be omitted depending on the use of the toner.

(Binder resin)
The toner core may contain a binder resin. In order to improve the dispersibility of the colorant and the low-temperature fixability of the toner to the recording medium (for example, paper), the binder resin is preferably a thermoplastic resin, and more preferably a polyester resin.

  When a polyester resin is used as the binder resin, the content of the polyester resin in the binder resin is preferably 70% by mass or more, more preferably 80% by mass or more, and 90% by mass or more. Particularly preferred is 100% by mass.

  Since it is easy to form a shell layer on the surface of the toner core, the acid value (AV) of the binder resin is preferably 5 mgKOH / g or more and 50 mgKOH / g or less. For the same reason, the hydroxyl value (OHV) of the binder resin is preferably 15 mgKOH / g or more and 80 mgKOH / g or less. The measurement method of each of AV and OHV is the same method as an example described later or an alternative method thereof.

  In order to improve toner fixability during high-speed fixing, the glass transition point (Tg) of the binder resin is preferably 20 ° C. or higher and 55 ° C. or lower. In order to improve the fixability of the toner during high-speed fixing, the softening point (Tm) of the binder resin is preferably 60 ° C. or higher and 150 ° C. or lower. Each measuring method of Tg and Tm is the same method as the Example mentioned later, or its alternative method.

  Generally, the binder resin occupies most of the toner core component (for example, 85% by mass or more). For this reason, it is considered that the properties of the binder resin greatly affect the properties of the entire toner core. By using a combination of a plurality of types of resins as the binder resin, the properties of the binder resin (more specifically, hydroxyl value, acid value, Tg, Tm, etc.) can be adjusted. For example, when the binder resin has a hydroxyl group, an ether group, an acid group (for example, an ester group) or a methyl group, the toner core tends to be anionic, and the binder resin has an amino group or an amide group. In other words, the toner core tends to become cationic.

(Coloring agent)
The toner core may contain a colorant. As the colorant, a known pigment or dye is used according to the color of the toner. The content of the colorant 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.

  When the toner is a black toner, a black colorant is used. An example of a black colorant is carbon black. You may use the black colorant adjusted to black using the yellow colorant, magenta colorant, and cyan colorant which are mentioned later.

  When the toner is yellow toner, a yellow colorant is used. Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, or arylamide compounds. More specifically, 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.

  If the toner is magenta toner, a magenta colorant is used. 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. More specifically, 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).

  When the toner is cyan toner, a cyan colorant is used. Examples of cyan colorants include copper phthalocyanine, copper phthalocyanine derivatives, anthraquinone compounds or basic dye lake compounds. More specifically, 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.

(Release agent)
The toner core may contain a release agent. The release agent is used, for example, for the purpose of improving the toner fixing property and offset resistance. In order to improve the toner fixing property and offset resistance, the content of the release agent 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.

  Examples of release agents include aliphatic hydrocarbon waxes, aliphatic hydrocarbon wax oxides, plant-derived waxes, animal-derived waxes, mineral-derived waxes, waxes based on fatty acid esters or fatty acid esters. A wax partially or completely deoxidized is mentioned. Examples of aliphatic hydrocarbon waxes include ester wax, polyethylene wax (eg low molecular weight polyethylene), polypropylene wax (eg low molecular weight polypropylene), polyolefin copolymer, polyolefin wax, microcrystalline wax, paraffin wax or Fischer-Tropsch A wax is mentioned. Examples of the oxide of the aliphatic hydrocarbon wax include an oxidized polyethylene wax or a block copolymer of oxidized polyethylene. Examples of plant-derived waxes include candelilla wax, carnauba wax, wood wax, jojoba wax or rice wax. Examples of animal-derived waxes include beeswax, lanolin or spermaceti. Examples of mineral-derived waxes include ozokerite, ceresin or petrolatum. Examples of the wax mainly composed of a fatty acid ester include montanic acid ester wax and caster wax. Deoxidized carnauba wax is an example of a wax in which a part or all of the fatty acid ester has been deoxidized. A mold release agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The melting point of the release agent is preferably 50 ° C. or higher and 100 ° C. or lower. When the melting point of the release agent is within such a range, the low-temperature fixability of the toner containing the release agent is improved, and the occurrence of offset at a high temperature of the toner tends to be suppressed. The melting point of the release agent can be measured using, for example, a differential scanning calorimeter (DSC) (for example, “DSC-6220” manufactured by Seiko Instruments Inc.).

(Charge control agent)
The toner core may contain a charge control agent. The charge control agent is used, for example, for the purpose of improving the charge stability or charge rising property of the toner. The charge rising characteristic of the toner is an index as to whether or not the toner can be charged to a predetermined charge level in a short time. By adding a negatively chargeable charge control agent to the toner core, the anionicity of the toner core can be enhanced. Further, the cationic property of the toner core can be increased by including a positively chargeable charge control agent in the toner core. However, if sufficient chargeability is ensured in the toner, it is not necessary to include a charge control agent in the toner core.

(Magnetic powder)
The toner core may contain magnetic powder. Examples of the magnetic powder include iron (more specifically, ferrite or magnetite), ferromagnetic metal (more specifically, cobalt or nickel), an alloy containing iron and / or ferromagnetic metal, ferromagnetic Ferromagnetic alloys or chromium dioxide that has been subjected to a heat treatment (more specifically, heat treatment or the like) can be suitably used. One type of magnetic powder may be used alone, or a plurality of types of magnetic powder may be used in combination.

<1-1-2. Shell layer>
A shell layer is provided on the surface of the toner core. In the toner base particles before attaching the external additive particles in the toner particle forming step described later, the area ratio of the surface area of the toner core in which the shell layer is provided in the entire surface area of the toner core (hereinafter referred to as shell coverage). Is) 60% or more and 80% or less. When the shell coverage is 60% or more, the charge amount of the toner does not become too low, and it becomes easy to adjust the charge amount of the toner to a desired value. When the shell coverage is 60% or more, the heat-resistant storage stability of the toner can be improved. When the shell coverage is 80% or less, the toner charge amount does not become too high, and the toner charge amount can be easily adjusted to a desired value. If the shell coverage is 80% or less, the toner charge amount distribution tends to be narrow.

  The shell coverage is expressed by the formula “shell coverage (unit:%) = 100 × area of the coating region / area of the entire surface of the toner core”. The method for measuring the shell coverage is the same method as in the examples described later or an alternative method thereof. The shell coverage can be adjusted, for example, by changing the addition amount of the shell material with respect to the mass of the toner core in the shell layer forming step described later.

  In order to improve the low-temperature fixability of the toner particles, the resin forming the shell layer is preferably a thermoplastic resin, more preferably a styrene-acrylic acid resin or an acrylic acid resin. A thermoplastic resin may be used individually by 1 type, and may be used in combination of 2 or more type.

  As described above, in order to improve the fixing property of the toner, it is preferable that the toner core contains a polyester resin. However, the polyester resin exhibits strong negative chargeability. For this reason, when the toner core contains a polyester resin, it is generally difficult for the toner to be positively charged. Therefore, when the toner core is positively charged and developed with a toner containing a polyester resin, the shell layer preferably contains a resin having a positive chargeability. For example, the positive chargeability of the toner may be adjusted by including in the shell layer first resin particles that do not have positive chargeability and second resin particles that have positive chargeability. Hereinafter, a toner including a shell layer containing first resin particles and second resin particles will be described.

  The first resin particles do not contain, for example, a charge control agent (particularly a positively chargeable charge control agent). The second resin particles contain, for example, a charge control agent (particularly a positively chargeable charge control agent). The shape of the resin particles constituting the shell layer may be spherical, or the spherical resin particles may be deformed into a flat shape in the course of film formation. The resin particles may be formed into a film by being heated in the drying step or receiving a physical impact force in the toner particle forming step (external addition step).

  In order to improve the charging stability of the toner, it is preferable that the resin constituting each of the first resin particles and the second resin particles has hydrophobicity.

  In order to achieve both heat-resistant storage stability and low-temperature fixability of the toner, each of the first resin particles and the second resin particles is substantially a thermoplastic resin (more specifically, the above-described preferred thermoplastic resin). It is preferable that it is comprised substantially from acrylic acid resin or styrene-acrylic acid resin. In order to uniformly cover the toner core with the first resin particles and ensure sufficient hydrophobicity on the surface of the toner base particles, the first resin particles are composed of 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid. It is preferably composed substantially of a styrene-acrylic acid resin containing a repeating unit having one or more alcoholic hydroxyl groups derived from 2-hydroxyethyl or 2-hydroxypropyl methacrylate.

  In order to contain the charge control agent in the second resin particles, a repeating unit derived from the charge control agent may be incorporated in the resin constituting the second resin particles, or the resin constituting the second resin particles may be charged. The particles may be dispersed. However, in order to obtain a toner having excellent chargeability, heat-resistant storage stability and low-temperature fixability, it is preferable that the second resin particles are substantially composed of a resin having a repeating unit derived from a charge control agent. It is particularly preferable that the resin is substantially composed of a resin having a repeating unit derived from a methacryloyl group-containing quaternary ammonium compound monomer. As the (meth) acryloyl group-containing quaternary ammonium compound monomer, for example, methacryloyloxyalkyltrimethylammonium salt (more specifically, 2- (methacryloyloxy) ethyltrimethylammonium chloride, etc.) can be preferably used.

  In order to improve the chargeability and durability of the developer, the number average particle diameter of each of the first resin particles and the second resin particles is preferably 30 nm or more and 60 nm or less. When the number average particle diameter of the shell particles is 60 nm or less, the resin particles are hardly detached from the toner core. On the other hand, if the number average particle diameter of the resin particles is 30 nm or more, the resin particles are difficult to be embedded in the toner core. In addition, when the number average particle diameter of the resin particles is 30 nm or more, it is considered that the resin particles function as a spacer between the toner particles and aggregation of the toner particles is suppressed. The number average particle diameter of the resin particles is the number average value of the equivalent circle diameters of the primary particles (diameter of a circle having the same area as the projected area of the particles) measured using a microscope.

<1-2. External additive particles>
Examples of the external additive particles include particles of silica particles or metal oxides (more specifically, particles of alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate or barium titanate). One kind of external additive particles may be used alone, or a plurality of kinds may be used in combination. The number average particle diameter of the external additive particles is preferably 1 nm or more and 1 μm or less, and more preferably 1 nm or more and 50 nm or less.

  The content of the external additive particles is preferably 1.1 parts by weight or more and 1.9 parts by weight or less, and 1.2 parts by weight or more and 1.8 parts by weight or less with respect to 100 parts by weight of the toner base particles. It is more preferable that When the content of the external additive particles is 1.1 parts by mass or more based on 100 parts by mass of the toner base particles, the fluidity of the toner is improved, and the development and transfer of the toner can easily proceed well. This tends to improve the image density of the formed image. When the content of the external additive particles is 1.9 parts by mass or less with respect to 100 parts by mass of the toner base particles, the external additive particles are easily detached from the toner base particles. The detached external additive particles may adhere to the surface of the carrier, and the charging ability of the carrier may be reduced. As a result, the charging stability of the toner tends to decrease.

<2. Two-component developer>
The toner may be mixed with a desired carrier and used as a two-component developer. When preparing a two-component developer, it is preferable to use a magnetic carrier. A carrier core coated with a resin may be used as the carrier. Further, as the carrier, a resin carrier in which a carrier core is dispersed in a resin may be used.

  Examples of carrier cores include iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel or cobalt particles; alloys of these materials with metals (eg, manganese, magnesium, zinc or aluminum) Particles of iron-nickel alloy; particles of iron-cobalt alloy; particles of ceramics; or particles of a high dielectric constant material. Examples of ceramics include titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, lead titanate, lead zirconate or lithium niobate Is mentioned. Examples of the high dielectric constant material include ammonium dihydrogen phosphate, potassium dihydrogen phosphate, or Rochelle salt. These carrier cores can be used singly or in combination of two or more.

  Examples of the resin covering the carrier core include acrylic acid polymer, styrene polymer, styrene-acrylic acid copolymer, olefin polymer, polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, and polyester resin. , Unsaturated polyester resin, polyamide resin, urethane resin, epoxy resin, silicone resin, fluorine resin, phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin or amino resin. Examples of olefin polymers include polyethylene, chlorinated polyethylene, or polypropylene. Examples of the fluororesin include polytetrafluoroethylene, polychlorotrifluoroethylene, or polyvinylidene fluoride. These resins can be used alone or in combination of two or more.

  The particle diameter of the carrier is preferably 20 μm or more and 120 μm or less, and more preferably 25 μm or more and 80 μm or less. The particle diameter of the carrier can be measured with an electron microscope.

  When the toner is used in the two-component developer, the toner content is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less with respect to the mass of the two-component developer. It is more preferable.

<3. Toner Production Method>
The manufacturing method of this embodiment includes a toner particle forming step (external addition step) and an exposure step. The manufacturing method of the present embodiment may further include a toner core forming step and a shell layer forming step as necessary.

<3-1. Toner core formation process>
Examples of the toner core manufacturing method include an agglomeration method or a pulverization method. The agglomeration method is easier to produce toner mother particles having a higher circularity than the pulverization method. Further, the aggregation method is easy to produce toner base particles having a uniform shape and particle size. On the other hand, the pulverization method can produce toner mother particles more easily than the aggregation method.

(Crushing method)
Hereinafter, an example of the pulverization method will be described. First, at least one of a binder resin, a colorant, a charge control agent, a release agent, and magnetic powder is mixed. Subsequently, the obtained mixture is melted and kneaded. Subsequently, the obtained kneaded product is pulverized and classified. As a result, a toner core having a desired particle size can be obtained.

(Aggregation method)
Hereinafter, an example of the aggregation method will be described. First, the fine particles of the binder resin, the colorant, the charge control agent, the release agent, and the magnetic powder are aggregated in an aqueous medium to obtain aggregated particles. Subsequently, the obtained aggregated particles are heated to unite the components contained in the aggregated particles. As a result, an aqueous dispersion containing toner base particles is obtained. Thereafter, an unnecessary substance (such as a surfactant) is removed from the dispersion liquid of the toner core to obtain the toner core.

<3-2. Shell layer formation process>
In the shell layer forming step, the toner core and a material for forming the shell layer (hereinafter sometimes referred to as shell material) are mixed in a liquid to form the shell layer on the surface of the toner core.

  In order to suppress dissolution or elution of the toner core components (particularly, the binder resin and the release agent) when forming the shell layer, it is preferable to use an aqueous medium as the liquid. The aqueous medium is a medium mainly composed of water. The aqueous medium may function as a solvent or may function as a dispersion medium. Specific examples of the aqueous medium include water or a mixed liquid of water and a polar solvent. Examples of the polar solvent contained in the aqueous medium include methanol or ethanol. The content of water in the aqueous medium is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, based on the mass of the aqueous medium. Most preferably, it is mass%.

  Examples of the shell material include resin particles (more specifically, the first resin particles and the second resin particles described above). The resin particles may be added in a suspension state. In order to favorably form the shell layer in the liquid, it is preferable that the toner core has an anionic property and the shell material (and thus the shell layer) has a cationic property.

  The pH of the liquid to which the toner core and shell material are added is preferably adjusted to about 4 using an acidic substance (for example, hydrochloric acid). By adjusting the pH of the liquid to the acidic side, the reaction of the shell material is easily promoted.

  By mixing the toner core and the shell material in the liquid, the shell material adheres to the surface of the toner core in the liquid. In order to uniformly adhere the shell material to the surface of the toner core, it is preferable that the shell material and the toner core are highly dispersed in the liquid. In order to highly disperse the toner core in the liquid, a surfactant may be included in the liquid. In order to highly disperse the toner core in the liquid, the liquid may be stirred using a powerful stirring device (for example, “Hibis Disper Mix” manufactured by Primics Co., Ltd.). When the toner core has an anionic property, aggregation of the toner core can be suppressed by using an anionic surfactant having the same polarity. Examples of the surfactant include a sulfate ester salt, a sulfonate salt, a phosphate ester salt, and a soap.

  Subsequently, while stirring the liquid containing the toner core and the shell material, the liquid temperature is set at a predetermined holding temperature (for example, 50 ° C. at a speed selected from 0.1 ° C./min to 3 ° C./min). Temperature up to 85 ° C. or higher). Furthermore, the temperature of the liquid is maintained at a predetermined holding temperature for a predetermined time (for example, a period of 30 minutes to 4 hours) while stirring the liquid. While the temperature of the liquid is maintained at a predetermined temperature, the shell material adheres to the surface of the toner core, and the shell material reacts with the toner core. Thereby, a shell layer is formed. By forming a shell layer on the surface of the toner core in the liquid, a dispersion of toner base particles can be obtained.

  The obtained dispersion of toner base particles is cooled to room temperature (about 25 ° C.), for example. Subsequently, the dispersion of the toner base particles is filtered using, for example, a Buchner funnel. Thereby, the toner base particles are separated from the liquid (solid-liquid separation), and wet cake-like toner base particles are obtained. Subsequently, the obtained wet cake-like toner base particles are washed. Subsequently, the washed toner base particles are dried. For drying the toner base particles, a vacuum stirring dryer having stirring blades may be used. For example, while maintaining the container at a predetermined drying temperature with a temperature control jacket (for example, a hot water jacket), the toner base particles are dried while being stirred at a predetermined speed in a container that has been depressurized (for example, depressurized to 10 kPa or less). Let There is a tendency that the shell coverage can be adjusted by changing the drying conditions (for example, drying temperature and stirring speed). For example, the shell coverage tends to increase as the drying temperature increases.

<3-3. Toner particle formation process (external addition process)>
In the toner particle forming step, a plurality of external additive particles are attached to the surface of the toner base particles to form toner particles. The toner particle forming step corresponds to a so-called external addition step. As an example of a method for attaching an external additive, a toner (for example, an FM mixer or a Nauter mixer (registered trademark)) is used, under a 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.

<3-4. Exposure process>
In the exposure step, the toner particles are exposed to an environment having a temperature of 30 ° C. or higher and a relative humidity of 55% RH or higher. The exposing step is performed simultaneously with the toner particle forming step or after the toner particle forming step. It is considered that a part of the toner core component is eluted from the uncoated region of the toner core by exposure to a predetermined high temperature and high humidity environment in the exposure process. As a result, as described above, the change in the surface shape of the toner particles can be reduced even when the environment changes. As a result, it is considered that a toner that is excellent in heat-resistant storage stability and charging stability and can form a high-quality image can be manufactured even when the environment fluctuates. In addition, it is considered that the toner base particles and the external additive are firmly bonded by being exposed to a predetermined high temperature and high humidity environment in the exposure process. If the environment to be exposed is high temperature and high humidity, many hydrogen bonds are formed between the hydroxyl groups of the toner base particles and the groups (for example, silanol groups) of the external additive particles due to the influence of water molecules in the air. It is thought. As a result, there is a tendency that the detachment of the external additive particles from the toner base particles can be suppressed.

  Regarding the environment in which the toner particles are exposed, the temperature is preferably 30 ° C. or higher and 45 ° C. or lower, and more preferably 30 ° C. or higher and 40 ° C. or lower. When the temperature is 45 ° C. or less, it is easy to suppress melting of the toner particles themselves. When the temperature is 40 ° C. or lower, it is easy to produce toner particles economically.

  Regarding the environment to which the toner particles are exposed, the relative humidity is preferably 55% RH or more and 90% RH or less, and more preferably 60% RH or more and 85% RH or less. When the relative humidity is 90% RH or less, it is easy to control the temperature and relative humidity, and it is easy to suppress the occurrence of condensation. When the relative humidity is 85% RH or less, it is easy to produce toner particles economically.

  In order to obtain toner particles having a small change in surface shape, the time for exposing the toner particles to an environment having a temperature of 30 ° C. or more and a relative humidity of 55% RH or more is preferably 10 minutes or more and 24 hours or less. If the exposure time is 10 minutes or more, the change in the surface shape of the toner particles tends to be small even when the environment changes. When the exposure time is 24 hours or less, the toner particles can be efficiently produced while reducing the change in the surface shape of the toner particles.

  In order to produce the toner efficiently, it is preferable that the exposure step is performed simultaneously with the toner particle forming step. For example, the exposure process can be performed simultaneously with the toner particle forming process by setting the environment (for example, the working environment) in which the toner particle forming process is performed to a temperature of 30 ° C. or higher and a relative humidity of 55% RH or higher.

  The toner manufacturing method can be arbitrarily changed according to the required configuration or characteristics of the toner. Further, unnecessary operations and processes may be omitted. In order to produce the toner efficiently, it is preferable to form a large number of toner particles simultaneously.

Examples of the present invention will be described. Table 1 shows toners (T1) to (T8) according to Examples or Comparative Examples. In Table 1, the content of external additive particles is the content of external additive particles with respect to 100.0 parts by mass of toner base particles. In Table 1, the BET specific surface area of the toner particles is determined when the toner particles are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours (when evaluation pretreatment is performed in a room temperature and humidity environment described later). BET specific surface area (A _N ).

Hereinafter, a production method, an evaluation method, and an evaluation result of toners (T1) to (T8) will be described. In the evaluation in which an error occurs, a considerable number of measurement values with sufficiently small errors are obtained, and the number average of the obtained measurement values is used as the evaluation value. In addition, Tg (glass transition point), Tm (softening point), AV (acid value), OHV (hydroxyl value), circularity, D ₅₀ (volume median diameter) and number average particle diameter were measured by the following methods. As shown in

(Measurement method of Tg)
A differential scanning calorimeter (“DSC-6220” manufactured by Seiko Instruments Inc.) was used to determine the endothermic curve (vertical axis: heat flow (DSC signal), horizontal axis: temperature) of the sample (for example, resin). Subsequently, the Tg (glass transition point) of the sample was read from the obtained endothermic curve. The temperature of the specific heat change point (intersection of the extrapolation line of the base line and the extrapolation line of the falling line) in the obtained endothermic curve corresponds to the Tg (glass transition point) of the sample.

(Measurement method of Tm)
A sample (for example, resin) is set on a Koka type flow tester (“CFT-500D” manufactured by Shimadzu Corporation), under conditions of a die pore diameter of 1 mm, a plunger load of 20 kg / cm ² , and a temperature rising rate of 6 ° C./min. A 1 cm ³ sample was melted out and the S curve (horizontal axis: temperature, vertical axis: stroke) of the sample was determined. Subsequently, the Tm of the sample was read from the obtained S-shaped curve. In the S-curve, if the maximum stroke value is S ₁ and the low-temperature baseline stroke value is S ₂ , the temperature at which the stroke value in the S-curve is “(S ₁ + S ₂ ) / 2” Corresponds to the Tm (softening point) of the sample.

(Measurement method of AV and OHV)
AV and OHV of a sample (for example, resin) were measured by a method based on JIS (Japanese Industrial Standard) K0070-1992.

(Measurement method of circularity)
The circularity of the sample (for example, toner core) was measured using a flow particle image analyzer (“FPIA (registered trademark) -3000” manufactured by Malvern).

(D ₅₀ measurement method)
The D ₅₀ of the sample (eg, toner core) was measured using a precision particle size distribution measuring device (“Coulter Counter Multisizer 3” manufactured by Beckman Coulter, Inc.).

(Method for measuring the number average particle diameter of suspension particles)
Using a transmission electron microscope (“JEM-2100F” manufactured by JEOL Ltd.), a sample (for example, resin particles) was photographed at a magnification of 30000 times. Images of 100 randomly selected samples were obtained. Subsequently, the obtained image was analyzed using image analysis software, and the particle size was measured for each of 100 samples. Subsequently, the sum of all measured particle sizes was divided by the number of measured samples (100). Thereby, the number average particle diameter of the sample was obtained.

<1. Toner Production Method>
Toners (T1) to (T8) were produced by the following method.

<1-1. Production Method of Toner (T1)>
(Toner core formation process)
First, a polyester resin used as a binder resin for the toner core was prepared. A polyester resin was synthesized by reacting a bisphenol A ethylene oxide adduct (specifically, an alcohol obtained by adding ethylene oxide with bisphenol A as a skeleton) and an acid having a polyfunctional group (specifically, terephthalic acid). The obtained polyester resin has a softening point (Tm) of 100 ° C., a glass transition point (Tg) of 48 ° C., a hydroxyl value (OHV) of 20 mgKOH / g, and an acid value (AV) of 40 mgKOH / g. there were.

Using an FM mixer (manufactured by Nihon Coke Kogyo Co., Ltd.), 100 parts by weight of a binder resin (polyester resin obtained as described above) and a colorant (CI Pigment Blue 15: 3, component: copper phthalocyanine) 5 parts by mass of a pigment) and 5 parts by mass of a release agent (“Nissan Electol (registered trademark)”, component: ester wax) manufactured by NOF Corporation were mixed. The obtained mixture was kneaded using a twin screw extruder ("PCM-30" manufactured by Ikegai Co., Ltd.) to obtain a kneaded product. The kneaded product was cooled. Subsequently, the kneaded product was pulverized using a pulverizer (“Turbo Mill RS Model” manufactured by Freund Turbo Inc.) to obtain a pulverized product. The pulverized product was classified using a classifier (“Elbow Jet EJ-LABO type” manufactured by Nippon Steel Mining Co., Ltd.) to obtain a toner core. The resulting toner core had a volume median diameter (D ₅₀ ) of 6 μm, a circularity of 0.93, a softening point (Tm) of 90 ° C., and a glass transition point (Tg) of 49 ° C. .

  The zeta potential of the toner core at pH 4 was −15 mV. The triboelectric charge amount of the toner core was −20 μC / g. From the measured values of the zeta potential and the triboelectric charge amount, it was confirmed that the toner core has an anionic property. The measurement methods of the zeta potential and the triboelectric charge amount of the toner core are as follows.

[Measurement method of zeta potential]
0.2 g of a sample (toner core), 80 g of ion-exchanged water, and 20 g of nonionic surfactant (“K-85”, polyvinylpyrrolidone manufactured by Nippon Shokubai Co., Ltd.) having a concentration of 1% by mass were mixed using a magnetic stirrer. . Subsequently, the sample (toner core) was uniformly dispersed in the liquid to obtain a dispersion. Subsequently, dilute hydrochloric acid was added to the obtained dispersion to adjust the pH of the dispersion to 4, and a dispersion with pH 4 was obtained. Then, using a zeta potential / particle size distribution measuring apparatus (“Delsa Nano HC” manufactured by Beckman Coulter, Inc.), electrophoresis is performed at a temperature of 25 ° C. and pH 4 (more specifically, laser Doppler electrophoresis). The zeta potential of the sample (toner core) in the dispersion was measured.

[Measurement method of triboelectric charge]
100 parts by mass of a standard carrier N-01 (standard carrier for negatively charged polar toner) provided by the Imaging Society of Japan and 7 parts by mass of a sample (toner core) were mixed with a mixer (Willie & Bacofen (WAB)) Using a tumbler (registered trademark) mixer T2F ”), the mixture was mixed for 30 minutes at a rotation speed of 96 rpm. Subsequently, the triboelectric charge amount of the sample in the obtained mixture was measured using a Q / m meter (“MODEL 210HS-2A” manufactured by Trek). Specifically, 0.10 g of the mixture (standard carrier and sample) was charged into a measurement cell of a Q / m meter, and only the sample (toner core) of the charged mixture was sucked through a sieve (metal mesh) for 10 seconds. The charge amount (unit: μC / g) of the sample was calculated based on the formula “total amount of electricity of sucked sample (unit: μC) / mass of sucked sample (unit: g)”.

(Preparation of suspension A)
Next, a suspension A was prepared. Specifically, a 1 L three-necked flask equipped with a thermometer and stirring blades was set in a water bath. In a flask, put 875 mL of ion-exchanged water and 75 mL of an anionic surfactant (“Latemul (registered trademark) WX” manufactured by Kao Corporation, component: sodium polyoxyethylene alkyl ether sulfate, solid content concentration: 26% by mass). It was. Thereafter, the temperature in the flask was raised to 80 ° C. using a water bath. Subsequently, two kinds of liquids (first liquid and second liquid) were dropped into the contents of the flask at 80 ° C. over 7 hours. The first liquid was a mixed liquid of 14 mL of styrene, 4 mL of 2-hydroxyethyl methacrylate (HEMA), and 2 mL of butyl acrylate. The second liquid was a solution in which 0.5 g of potassium persulfate was dissolved in 30 mL of ion exchange water. Subsequently, the temperature in the flask was kept at 80 ° C. for another 2 hours to polymerize the contents of the flask. As a result, a suspension A of thermoplastic resin (specifically, styrene-acrylic acid resin) was obtained. The number average particle diameter of the resin particles contained in the suspension A was 42 nm. Further, a test was performed in which the suspension A was placed in tetrahydrofuran (THF). As a result of this test, the resin particles contained in the suspension A swelled but did not dissolve. From this, it was confirmed that the resin particles contained in the suspension A are hydrophobic.

(Preparation of suspension B)
Next, a suspension B was prepared. In a 1 L three-necked flask equipped with a thermometer, a cooling pipe, a nitrogen introducing pipe and a stirring blade, 90 g of isobutanol, 100 g of methyl methacrylate, 35 g of butyl acrylate, and 2- (methacryloyloxy) ethyltrimethyl 30 g of ammonium chloride (Alfa Aesar) and 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propanamide) (polymerization initiator, “VA-086” manufactured by Wako Pure Chemical Industries, Ltd. ) 6g. Subsequently, the contents of the flask were reacted for 3 hours under conditions of a nitrogen atmosphere and a temperature of 80 ° C. Thereafter, 3 g of 2,2′-azobis (2-methyl-N- (2-hydroxyethyl) propanamide) (“VA-086” manufactured by Wako Pure Chemical Industries, Ltd.) was added to the flask, and the nitrogen atmosphere and temperature were increased. The flask contents were further reacted for 3 hours at 80 ° C. to obtain a polymer solution. Subsequently, the obtained polymer solution was dried under reduced pressure at a temperature of 150 ° C. Subsequently, the polymer dried under reduced pressure was crushed to obtain Resin B.

  Subsequently, 200 g of the resin B obtained as described above and ethyl acetate (Wako Pure Chemical Industries, Ltd.) were placed in a container of a mixing apparatus ("Hibismix (registered trademark) 2P-1 type" manufactured by PRIMIX Corporation). 184 mL of “Ethyl Acetate Special Grade”) was added. Subsequently, the container contents were stirred for 1 hour at a rotation speed of 20 rpm to obtain a highly viscous solution. Thereafter, an aqueous solution containing ethyl acetate was added to the resulting highly viscous solution. The aqueous solution containing ethyl acetate was 18 mL of 1N hydrochloric acid, an anionic surfactant (“Emar (registered trademark) 0” manufactured by Kao Corporation, component: sodium lauryl sulfate) and ethyl acetate (“Acetic acid” manufactured by Wako Pure Chemical Industries, Ltd.). It was an aqueous solution in which 16 g of ethyl special grade) was dissolved in 562 g of ion-exchanged water. As a result, a suspension B of a positively charged hydrophobic resin (specifically, an acrylic resin having a repeating unit derived from 2- (methacryloyloxy) ethyltrimethylammonium chloride) was obtained. The number average particle diameter of the resin particles contained in the obtained suspension B was 35 nm.

(Shell layer forming process)
A three-necked flask equipped with a thermometer and a stirring blade was prepared. In the flask, 2500 mL of ion-exchanged water and 250 g of sodium polyacrylate (“Julimer (registered trademark) AC-103” manufactured by Toagosei Co., Ltd.) were added. This obtained the sodium polyacrylate aqueous solution. To the sodium polyacrylate aqueous solution, 1000 g of toner core (powder) was added. The contents of the flask were thoroughly stirred at room temperature (about 25 ° C.). As a result, a toner core dispersion was obtained. The dispersion liquid of the toner core was filtered using a filter paper having an opening of 3 μm, and the toner core was taken out. Subsequently, the removed toner core was redispersed in ion exchange water. Thereafter, the toner core was washed by repeating filtration and redispersion five times. A suspension in which 500 g of the toner core was dispersed in 2500 mL of ion-exchanged water was prepared in the flask.

  Subsequently, 32.5 g of suspension A and 3.0 g of suspension B were added to the flask. Dilute hydrochloric acid was added to the flask to adjust the pH of the suspension in the flask to 4. The pH adjusted suspension was transferred to a 1 L separable flask. While stirring the contents of the flask, the temperature in the flask was increased to 65 ° C. at a rate of temperature increase of 0.5 ° C./min using a water bath. While stirring the flask contents, the temperature in the flask was kept at 65 ° C. for 50 minutes. As a result, a shell layer was formed on the surface of the toner core, and a dispersion liquid containing toner mother particles was obtained. Thereafter, the pH of the dispersion of the toner base particles was adjusted to 7 (neutralized) using sodium hydroxide, and the dispersion of the toner base particles was cooled to room temperature (about 25 ° C.).

(Washing and drying)
The obtained dispersion of toner base particles was filtered (solid-liquid separation), and the toner base particles were taken out. Thereafter, the extracted mother particles were redispersed in ion-exchanged water. Further, dispersion and filtration were repeated to wash the toner base particles. Subsequently, the toner base particles were dried in a reduced pressure atmosphere (pressure 3.5 kPa) using a vacuum stirring dryer (“Apex Mixer WB-5” manufactured by Taiheiyo Kiko Co., Ltd.).

(Toner particle formation and exposure process)
100.0 parts by weight of the dried toner base particles and 1.2 parts by weight of external additive particles (hydrophobic silica particles, “AEROSIL (registered trademark) RA-200H” manufactured by Nippon Aerosil Co., Ltd.) And it mixed for 10 minutes in the environment of relative humidity 80% RH using FM mixer (made by Nippon Coke Industries Co., Ltd.). Thus, the toner particle forming step and the exposure step of exposing the toner particles to an environment having a temperature of 32 ° C. and a relative humidity of 80% RH were simultaneously performed. As a result, a powder was obtained in which an external additive adhered (external addition) to the surface of the toner base particles. The obtained powder was sieved using a 300 mesh (aperture 48 μm) sieve. As a result, a toner (T1) containing a large number of toner particles was obtained.

<1-2. Manufacturing Method of Toners (T2) to (T4)>
Toners (T2) to (T4) were produced in the same manner as in the production method of the toner (T1) except that the following points were changed. The additive amount (content) of the external additive particles in the toner particle formation and exposure step is changed from 1.2 parts by mass in the production of the toner (T1) to the addition amounts shown in Table 1 (1.8 parts by mass, 1.0 parts by mass). Mass parts or 2.0 mass parts).

<1-3. Production Method of Toner (T5)>
A toner (T5) was produced in the same manner as the production method of the toner (T1) except that the following points were changed. The environment in the toner particle formation and exposure process was changed from an environment of 32 ° C. and 80% RH in the production of the toner (T1) to an environment of 23 ° C. and 50% RH.

<1-4. Production Method of Toner (T6)>
A toner (T6) was produced in the same manner as the production method of the toner (T1) except that the following points were changed. The amount of the suspensions A and B added in the shell layer forming step is changed from the suspension A (32.5 g) and the suspension B (3.0 g) in the production of the toner (T1) to the suspension A (25.2 g) and the suspension B (2 .3g). As a result, the shell coverage was changed from 62% of the toner (T1) to 54%.

<1-5. Production Method of Toner (T7)>
A toner (T7) was produced in the same manner as in the production method of the toner (T1) except that the following points were changed. Regarding the shell layer forming step, the suspension A (32.5 g) added in the production of the toner (T1) was changed to a suspension C (32.5 g) described later. As a result, the shell coverage was changed from 62% of the toner (T1) to 87%.

(Preparation of suspension C)
Suspension C was prepared. Specifically, a 1 L three-necked flask equipped with a thermometer and stirring blades was set in a water bath. In a flask, put 875 mL of ion-exchanged water and 75 mL of an anionic surfactant (“Latemul (registered trademark) WX” manufactured by Kao Corporation, component: sodium polyoxyethylene alkyl ether sulfate, solid content concentration: 26% by mass). It was. Thereafter, the temperature in the flask was raised to 80 ° C. using a water bath. Subsequently, two kinds of liquids (first liquid and second liquid) were dropped into the contents of the flask at 80 ° C. over 5 hours. The first liquid was a mixed liquid of 14 mL of styrene, 4 mL of 2-hydroxyethyl methacrylate (HEMA), and 2 mL of butyl acrylate. The second liquid was a solution in which 0.5 g of potassium persulfate was dissolved in 30 mL of ion exchange water. Subsequently, the temperature in the flask was kept at 80 ° C. for another 2 hours to polymerize the contents of the flask. As a result, a suspension C of thermoplastic resin (specifically, styrene-acrylic acid resin) was obtained. The number average particle diameter of the resin particles contained in the suspension C was 35 nm. Further, a test was performed in which the suspension C was placed in tetrahydrofuran (THF). As a result of this test, the resin particles contained in the suspension A swelled but did not dissolve. From this, it was confirmed that the resin particles contained in the suspension C are hydrophobic.

<1-6. Production Method of Toner (T8)>
A toner (T8) was produced in the same manner as the production method of the toner (T1) except that the toner particle formation and exposure steps were changed as follows.

(Toner particle formation and exposure process)
100.0 parts by mass of dried toner base particles and 1.2 parts by mass of external additive particles (hydrophobic silica particles, “AEROSIL (registered trademark) RA-200H” manufactured by Nippon Aerosil Co., Ltd.) And it mixed for 10 minutes in the environment of relative humidity 50% RH using FM mixer (made by Nippon Coke Industries Co., Ltd.). Thus, a toner particle forming step (external addition step) was performed. As a result, a powder was obtained in which an external additive adhered (external addition) to the surface of the toner base particles. The obtained powder was sieved using a 300 mesh (aperture 48 μm) sieve. An exposure step was performed after the toner particle formation step. Specifically, the obtained powder (toner particles) was allowed to stand for 24 hours in an environment having a temperature of 32 ° C. and a relative humidity of 80% RH. As a result, a toner (T8) containing a large number of toner particles was obtained.

<1-7. Method for measuring shell coverage>
Table 1 shows the measurement results of the shell coverage of the toners (T1) to (T8). The shell coverage was measured after the toner base particles were formed and before the toner particles were formed (external addition). The object of measurement of the shell coverage was toner base particles. The method for measuring the shell coverage is as follows. As a measuring device, an SPM probe station (“NanoNaviReal” manufactured by Hitachi High-Tech Science Co., Ltd.) equipped with a scanning probe microscope (SPM) (“Multifunctional Unit AFM5200S” manufactured by Hitachi High-Tech Science Co., Ltd.) was used. Prior to the measurement, an average toner particle is selected from the toner particles contained in the toner using a scanning electron microscope (SEM) (“JSM-6700F” manufactured by JEOL Ltd.), and the selected toner particles are measured. Targeted. The toner particles to be measured were set on a measurement table of a measuring device (SPM) without being cut. Then, the field of view (measurement site) was set so that the measurement range included a region having no external additive on the surface of the toner particles to be measured. With the following measurement mode (DFM), the toner can be controlled while controlling the distance between the probe and the toner particles so that the amplitude of the vibrating cantilever is constant while the cantilever (tip portion: probe) is in resonance. Particle shape images (images showing surface shapes) were obtained.

(SPM measurement conditions)
Measurement probe: Low spring constant silicon cantilever ("OMCL-AC240TS-C3" manufactured by Olympus Corporation, spring constant 2 N / m, resonance frequency 70 kHz, aluminum back reflection coating material)
・ Measurement mode: DFM (dynamic force mode)
・ Measurement range (one field of view): 1μm × 1μm
・ Resolution (X data / Y data): 256/256
・ Q gain: 1 × ・ Scanning frequency: 1 Hz

The obtained shape image is subjected to image analysis using image analysis software (“WinROOF” manufactured by Mitani Shoji Co., Ltd.) and GIMP (GNU Image Manipulation Program: image editing / processing software distributed by GNU General Public License). The area of the surface area (covering area) of the toner core provided with the shell layer was determined. Then, the shell coverage was calculated based on the formula “shell coverage (unit:%) = 100 × area of the coating area / area of the entire surface of the toner core”. In each field of view, the area of the entire surface of the toner core was 1 μm ² (area of measurement range). The shell coverage was measured at five locations while changing the field of view for one toner particle. Then, the arithmetic average value of the measured shell coverage at the five locations was used as the shell coverage of one toner base particle as a measurement target. The shell coverage was measured for each of the 10 toner base particles contained in the toner. The number average value of 10 toner base particles was used as the toner evaluation value (shell coverage).

<2. Toner Evaluation Method>
The toners (T1) to (T8) were subjected to pre-evaluation processing. Each toner subjected to the pre-evaluation treatment was evaluated for BET specific surface area and heat resistant storage stability. Next, a two-component developer was manufactured using each of the toners that had undergone the pre-evaluation treatment. The manufactured two-component developer was evaluated for charging stability and image quality.

<2-1. Evaluation pretreatment>
Each of the toners (T1) to (T8) is left in a normal temperature and normal humidity environment (temperature 23 ° C., relative humidity 50% RH and volume absolute humidity 10.27 g / m ³ ) for 24 hours, and then the temperature 23 ° C. The humidity was adjusted for 24 hours in an environment with a relative humidity of 50% RH. Separately, each of the toners (T1), (T2), (T5) and (T8) is placed in a low-temperature and low-humidity environment (temperature 10 ° C., relative humidity 10% RH and volume absolute humidity 0.94 g / m ³ ). ) For 24 hours and then conditioned for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50% RH. Separately, each of the toners (T1), (T2), (T5) and (T8) is subjected to a high temperature and high humidity environment (temperature 32 ° C., relative humidity 80% RH and volume absolute humidity 26.99 g / m ³ ). Environment) for 24 hours, and then the humidity was adjusted for 24 hours in an environment of a temperature of 23 ° C and a relative humidity of 50% RH.

<2-2. BET specific surface area>
The BET specific surface area was measured for the toners (T1) to (T8) subjected to pretreatment for evaluation in a normal temperature and humidity environment. Further, the BET specific surface area was measured for the toners (T1), (T2), (T5), and (T8) that were subjected to pretreatment for evaluation in a low temperature and low humidity environment and a high temperature and high humidity environment. The BET specific surface area was measured by measuring a sample (toner) using a BET specific surface area measuring device ("Full Automatic Specific Surface Area Measuring Device Macsorb (registered trademark) HM MODEL-1208" manufactured by Mountec Co., Ltd.). Tables 2 and 3 show the BET specific surface areas of the measured toner.

For toners (T1), (T2), (T5), and (T8), the difference (A _L −A _N ) was calculated as follows. From the measured BET specific surface area (A _L ) of the toner subjected to the evaluation pretreatment in the low temperature and low humidity environment and the BET specific surface area (A _N ) of the toner subjected to the evaluation pretreatment in the normal temperature and normal humidity environment, the formula “A _L was calculated difference (a _L -A _N) according -A _N ". The difference (A _L −A _N ) is shown in Table 2 and Table 3. The difference (A _L −A _N ) is the BET specific surface area of the toner particles when the toner particles after the exposure step are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours, and the toner after the exposure step. This corresponds to the difference from the BET specific surface area of the toner particles when the particles are placed in an environment having a volumetric absolute humidity of 0.94 g / m ³ for 24 hours.

For toners (T1), (T2), (T5) and (T8), the difference (A _H −A _N ) was calculated as follows. From the measured BET specific surface area (A _H ) of the toner subjected to the pretreatment for evaluation at high temperature and high humidity, and the BET specific surface area (A _N ) of the toner subjected to the pretreatment for evaluation in the normal temperature and normal humidity environment, the formula “A _The difference (A _H −A _N ) was calculated according to “ _H− A _N ”. The difference (A _H −A _N ) is shown in Table 2 and Table 3. The difference (A _H −A _N ) is the BET specific surface area of the toner particles when the toner particles after the exposure step are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours, and the toner after the exposure step. This corresponds to the difference from the BET specific surface area of the toner particles when the particles are placed in an environment having a volumetric absolute humidity of 26.99 g / m ³ for 24 hours.

<2-3. Heat-resistant storage stability>
Toners (T1) to (T8) subjected to evaluation pretreatment in a normal temperature and humidity environment, and toners (T1), (T2), (T5), and (T5) subjected to evaluation pretreatment in a low temperature and low humidity environment and a high temperature and high humidity environment With respect to T8), the heat resistant storage stability was evaluated. Specifically, 3 g of a sample (toner) was put in a 20 mL polyethylene container. The sample in the container was allowed to stand at 60 ° C. for 3 hours using a thermostat (oven). Then, the container taken out from the thermostat was left still for 30 minutes in an environment of a temperature of 25 ° C. and a relative humidity of 65% RH. Thus, an evaluation toner was prepared in the container.

Next, sieve A (aperture 105 μm), sieve B (aperture 63 μm), and sieve C (aperture 45 μm), each having a known mass, were prepared. Then, the total mass of the evaluation toner before sieving (hereinafter referred to as MT [g]) was determined by measuring the mass of the sieve A on which the evaluation toner was placed. Subsequently, sieves A, B and C were set in a powder tester (manufactured by Hosokawa Micron Corporation). Sieve B was set on Sieve A, and Sieve C was set on Sieve B. According to the manual of the powder tester, each sieve was vibrated for 30 seconds with the vibration strength of the rheostat scale 5. After sieving, the mass (unit: g) of the toner remaining on each sieve was measured by measuring the mass of each sieve containing residual toner. And aggregation degree (unit: mass%) was computed based on following formula (5)-(8).
Ratio A = 100 × (mass of residual toner on sieve A) / MT [mass%] (5)
Ratio B = 100 × (mass of residual toner on sieve B) / MT [mass%] (6)
Ratio C = 100 × (mass of residual toner on sieve C) / MT [mass%] (7)
Aggregation degree [mass%] = ratio A + ratio B × (3/5) + ratio C × (1/5) (8)

  A toner having an aggregation degree of less than 15% by mass was evaluated as having good heat-resistant storage stability (◯). A toner having an aggregation degree of 15% by mass or more was evaluated as having poor heat-resistant storage stability (x).

<2-4. Production of two-component developer>
First, a carrier core was manufactured. Specifically, a mixture of iron oxide (III) (Fe ₂ O ₃ ), copper oxide (II) (CuO) and zinc oxide (ZnO) is pulverized using a wet ball mill until the particle size of the mixture becomes 1 μm or less. did. Polyvinyl alcohol was added to the obtained pulverized product to obtain a liquid. The obtained liquid was granulated using a spray dryer to obtain a granulated product. The granulated product was fired in an electric furnace to obtain a fired product. The fired product was crushed. The obtained crushed material was sieved using a sieve having an opening of 20 μm. The powder remaining on the sieve (powder having a particle diameter of 20 μm or more) was used as a carrier core.

A carrier was manufactured using the obtained carrier core. Specifically, 4 parts by mass of octylic acid as a curing catalyst was added to 100 parts by mass of a methyl silicone resin (a resin having a mass average molecular weight of 1.5 × 10 ⁴ measured by gel permeation chromatography (GPC)). A resin for a coat layer was obtained. 3 parts by weight of the coating layer resin is sprayed on 100 parts by weight of the carrier core while feeding hot air at 80 ° C. using a fluidized bed coating apparatus (“Spiraflow (registered trademark) SFC-5” manufactured by Freund Sangyo Co., Ltd.). did. As a result, the carrier core was coated with an uncured organic layer (fluidized bed). The carrier core coated with the uncured organic layer (fluidized bed) was heated at 260 ° C. for 3 hours using a dryer. Thereby, the fluidized bed was hardened. As a result, a carrier having a carrier core and a resin layer (coat layer) covering the carrier core was obtained.

  Next, 100 parts by mass of the carrier and 8 parts by mass of the toner subjected to pre-evaluation processing were mixed into a powder mixer (“Rocking Mixer (registered trademark)” manufactured by Aichi Electric Co., Ltd., mixing method: container rotation / swing method) For 30 minutes. As a result, a two-component developer was obtained.

<2-5. Charge stability>
The charging stability of the toner was evaluated in an environment having a temperature of 23 ° C. and a relative humidity of 50% RH. In the evaluation of charging stability, a color multifunction machine (“TASKalfa 5550ci” manufactured by Kyocera Document Solutions Inc.) was used as an evaluation machine. As the paper, “ColorCopy (registered trademark)” (A4 size, 90 g / m ² ) manufactured by Mondi was used. The two-component developer was put into a cyan developing device. The toner corresponding to the charged two-component developer was charged into the cyan toner container of the evaluation machine.

  First, an image A (pattern image with a printing rate of 5%) was formed on one sheet of paper using an evaluation machine. After the image formation, the two-component developer was taken out from the developing device. 0.10 g of the two-component developer taken out was put into a measuring cell of a measuring device (suction type small charge amount measuring device, “MODEL 212HS” manufactured by Trek). Only the toner out of the charged two-component developer was sucked through a sieve for 10 seconds. The total electricity and mass of the sucked toner were measured using a measuring device. Then, based on the formula “total amount of sucked toner (μC) / mass of sucked toner (g)”, the charge amount of the toner in the two-component developer after forming an image on one sheet ( The initial charge amount, unit μC / g) was calculated.

  Subsequently, an image A was formed on 5000 sheets using an evaluation machine. After forming image A on 5000 sheets of paper, the two-component developer was taken out from the developing device. For the two-component developer taken out, the charge amount of the toner in the two-component developer after forming an image on 5000 sheets of paper (charge amount after printing 5000 sheets, in the same manner as the initial charge amount measurement) Unit μC / g) was measured.

  Tables 2 and 3 show the calculated initial charge amount of the toner and the charge amount after printing 5000 sheets. A toner in which the absolute value of the difference between the initial charge amount and the charge amount after printing 5000 sheets was less than 5 μC / g was evaluated as having good charging stability (◯). A toner in which the absolute value of the difference between the initial charge amount and the charge amount after printing 5000 sheets was 5 μC / g or more was evaluated as having poor charge stability (x).

<2-6. Image quality>
The image quality of the toner was evaluated in an environment having a temperature of 23 ° C. and a relative humidity of 50% RH. In the evaluation of image quality, the evaluation machine and paper used in the evaluation of charging stability were used. The two-component developer was put into a cyan developing device. The toner corresponding to the charged two-component developer was charged into the cyan toner container of the evaluation machine.

  An image B (solid image) was formed on one sheet using an evaluation machine. The image density of the formed image B was measured using a reflection densitometer (“RD914” manufactured by X-Rite). The measured image density (ID) is shown in Tables 2 and 3. A toner having an image density of 1.25 or higher was evaluated as having good (◯) image quality. A toner having an image density of less than 1.25 was evaluated as having poor (x) image quality.

For the toners (T1), (T2), (T5), and (T8), the color difference (ΔE _LN ) and color difference (ΔE _HN ) of the image B formed as described above were measured using a reflection densitometer (X-Rite). "RD914" manufactured by the manufacturer).

The method for calculating the color difference (ΔE _LN ) is as follows. The image B formed by using a two-component developer comprising a toner was evaluated pretreated with normal temperature and normal humidity environment, a coordinate point P _N in the color space (CIE1976L ^* a ^* b ^* color space), the reflection densitometer It measured using. The coordinate point P _N was used as a reference. Subsequently, the coordinate point P _L in the color space was measured using a reflection densitometer for the image B formed using the two-component developer containing the toner that was subjected to the evaluation pretreatment in the low temperature and low humidity environment. A distance P _N -P _L between the two measured coordinate points (a distance to the coordinate point P _{L based} on the coordinate point P _N ) was calculated. The distance P _N −P _L is the color difference (ΔE _LN ).

The calculation method of the color difference (ΔE _HN ) is as follows. The image B formed by using a two-component developer comprising a toner was evaluated pretreated with normal temperature and normal humidity environment, a coordinate point P _N in the color space (CIE1976L ^* a ^* b ^* color space), the reflection densitometer It measured using. The coordinate point P _N was used as a reference. Subsequently, the image B formed by using a two-component developer comprising a toner was evaluated pretreated with high-temperature and high-humidity environment, a coordinate point P _H in the color space was measured with a reflection densitometer. And calculates the distance P _N -P _H between the two measured coordinate points (distance to the coordinate point P _H relative to the coordinate point P _N). The distance P _N -P _H is the color difference (ΔE _HN ).

The calculated color difference (ΔE _LN ) and color difference (ΔE _HN ) are shown in Tables 2 and 3. A toner having an absolute value of color difference (ΔE _LN ) of 0.03 or less was evaluated as having good image quality (◯). A toner having an absolute value of color difference (ΔE _LN ) exceeding 0.03 was evaluated as having poor image quality (×). A toner having an absolute value of color difference (ΔE _HN ) of 0.03 or less was evaluated as having good image quality (◯). A toner having an absolute value of color difference (ΔE _HN ) exceeding 0.03 was evaluated as having poor image quality (x).

<3. Evaluation results>
Tables 2 and 3 show the results of evaluating the BET specific surface area, heat resistant storage stability, charging stability and image quality for each of the toners (T1) to (T8). In Table 3, since the evaluation of the image density was poor for the toner (T3) subjected to the evaluation pretreatment in a room temperature and humidity environment, the charging stability was not evaluated. For the toner (T6) that was pre-evaluated in a normal temperature and normal humidity environment, the evaluation of heat storage stability was poor, so the charging stability and image density were not evaluated. For the toner (T7) that was pre-evaluated in a normal temperature and normal humidity environment, the image density was not evaluated because the evaluation of charging stability was poor. For the toners (T3), (T4), (T6) and (T7), the evaluation of any of the heat-resistant storage stability, charging stability and image density of the toner subjected to the pre-evaluation treatment in a normal temperature and humidity environment was poor. It was. For this reason, the toner that was pre-evaluated in a low temperature and low humidity environment and the toner that was pre-evaluated in a high temperature and high humidity environment were not evaluated. As a result, since the BET specific surface areas (A _L ) and (A _H ) and the coordinate points P _L and P _H were not measured, the difference between the BET specific surface areas (A _L −A _N ) and (A _H −A _N ) And color difference (ΔE _LN ) and (ΔE _HN ) were not evaluated.

As shown in Table 2, the toners (T1), (T2), and (T8) were all good in heat-resistant storage stability, charging stability, and image quality. Further, in the toners (T1), (T2), and (T8), the absolute values of the differences (A _L −A _N ) and (A _H −A _N ) in the BET specific surface area are each 0.00m ² / g or more and 0. .30 m ² / g or less, and the change in the shape of the toner particles due to the environment was small.

The toner (T3) is a toner particle obtained when the toner particles after the exposure process are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours (when the pre-evaluation treatment is performed in a normal temperature and normal humidity environment). The BET specific surface area was less than 1.30 m ² / g. Therefore, as shown in Table 3, the image formed with the toner (T3) had low image density and poor image quality.

The toner (T4) is a toner particle obtained when the toner particles after the exposure step are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours (when evaluation pretreatment is performed in a normal temperature and humidity environment). The BET specific surface area exceeded 3.00 m ² / g. Therefore, as shown in Table 3, the toner (T4) was inferior in charging stability. In the toner (T4), many external additive particles were added to increase the BET specific surface area. For this reason, it is considered that when the image is continuously formed, the external additive particles are detached from the toner base particles, and the detached external additive particles adhere to the carrier, and the charging ability of the carrier is lowered. For this reason, it is considered that the charge amount of the toner (T4) is reduced when images are continuously formed.

In the toner (T5), the toner particles were not exposed to an environment having a temperature of 30 ° C. or higher and a relative humidity of 55% RH or higher in the exposure process. Therefore, as shown in Table 3, the charging stability of the toner (T5) subjected to pre-evaluation processing in a high temperature and high humidity environment was inferior and the image density was low. In addition, the absolute value of the color difference (ΔE _HN ) between the image formed by the pre-evaluation process (T5) in the normal temperature and humidity environment and the image formed by the pre-evaluation process (T5) in the high temperature and high humidity environment. The value was great. Further, in toner (T5), the absolute value of the difference in BET specific surface area (A _H −A _N ) exceeded 0.30 m ² / g, and the change in the shape of the toner particles due to the environment was large.

  The toner (T6) has an area ratio (shell coverage) of the surface area of the toner core in which the shell layer is provided in the entire surface of the toner core in the toner base particles before the external additive particles are adhered in the toner particle forming step. It was less than 60%. Therefore, as shown in Table 3, the toner (T6) was inferior in heat resistant storage stability.

  The toner (T7) has an area ratio (shell coverage) of the surface area of the toner core in which the shell layer is provided in the entire surface of the toner core in the toner base particles before the external additive particles are adhered in the toner particle forming step. It was over 80%. Therefore, as shown in Table 3, the toner (T7) was inferior in charging stability. This is presumably because the toner (T7) was charged up when images were continuously formed.

  From the above, it has been shown that the toner production method according to the present invention can produce a toner that is excellent in heat-resistant storage stability and charge stability and can form a high-quality image even when the environment changes. It was.

  The toner manufactured by the toner manufacturing method according to the present invention can be used for forming an image in an image forming apparatus employing, for example, an electrophotographic method, an electrostatic recording method, or an electrostatic printing method.

10 Toner particles 11 Toner core 12 Shell layer 13 Toner base particles 14 External additive particles

Claims (5)

A method for producing a toner for developing an electrostatic latent image, comprising a plurality of toner particles,
The toner particles include toner base particles and a plurality of external additive particles provided on the surface of the toner base particles.
The toner base particles have a toner core and a shell layer provided on the surface of the toner core;
A toner particle forming step of forming a plurality of the external additive particles on the surface of the toner base particles to form the toner particles;
Exposing the toner particles to an environment having a temperature of 30 ° C. or higher and a relative humidity of 55% RH or higher,
The exposing step is performed simultaneously with the toner particle forming step or after the toner particle forming step,
The area ratio of the surface area of the toner core in which the shell layer is provided in the entire surface of the toner core in the toner base particles before the external additive particles are attached in the toner particle forming step is 60% or more and 80 % Or less,
When the toner particles after the exposure step are placed in an environment having a volumetric absolute humidity of 10.27 g / m ³ for 24 hours, the BET specific surface area of the toner particles is 1.30 m ² / g or more and 3.00 m ² / A method for producing a toner for developing an electrostatic latent image, which is g or less. The BET specific surface area of the toner particles when the toner particles after the exposure step are placed in an environment having a volume absolute humidity of 10.27 g / m ³ for 24 hours, and the toner particles after the exposure step are The absolute value of the difference from the BET specific surface area of the toner particles when placed in an environment where the humidity is 26.99 g / m ³ for 24 hours is 0.00 m ² / g or more and 0.30 m ² / g or less. The method for producing a toner for developing an electrostatic latent image according to claim 1. The BET specific surface area of the toner particles when the toner particles after the exposure step are placed in an environment having a volume absolute humidity of 10.27 g / m ³ for 24 hours, and the toner particles after the exposure step are The absolute value of the difference from the BET specific surface area of the toner particles when placed in an environment where the humidity is 0.94 g / m ³ for 24 hours is 0.00 m ² / g or more and 0.30 m ² / g or less. The method for producing a toner for developing an electrostatic latent image according to claim 1.   The content of the external additive particles is 1.1 parts by mass or more and 1.9 parts by mass or less with respect to 100 parts by mass of the toner base particles. A method for producing a toner for developing an electrostatic latent image.   5. The exposure time according to claim 1, wherein in the exposure step, the time during which the toner particles are exposed to the environment having a temperature of 30 ° C. or more and a relative humidity of 55% RH or more is 10 minutes or more and 24 hours or less. Manufacturing method of electrostatic latent image developing toner.

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