JP6816427B2 - Toner for static charge image development, static charge image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

The present invention relates to an electrostatic charge image developing toner, an electrostatic charge image developing agent, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method.

In electrophotographic image formation, toner is used as an image forming material, and for example, a toner containing toner particles containing a binder resin and a colorant and an external additive added to the toner particles is used. It is widely used.

For example, in Patent Document 1, "in the positively charged toner for static charge image development containing a binder resin, colored resin particles containing a colorant, and an external agent, the external additive is primary in number on average. Spherical colloidal silica fine particles having a particle size of 30 to 80 nm and a frictional charge amount of -50 to +300 μC / g, and fumed silica fine particles having a number average primary particle size of 5 to 25 nm. The contents of the colloidal silica fine particles and the fumed silica fine particles are 0.3 to 2 parts by weight and 0.1 to 1 part by weight, respectively, with respect to 100 parts by weight of the colored resin particles. Sexual toner. ”Is disclosed.

Patent Document 2 states that "(1) primary inorganic fine particles having an average primary volume particle size of 20 nm or less and (2) average primary volume particle size on the surface of toner particles containing at least a binder resin and a colorant. Non-magnetic one-component development toner to which second inorganic fine particles of 30 nm to 1 μm and (3) third inorganic fine particles containing cerium oxide as an essential component and at least one of other rare earth element compounds are attached. A non-magnetic one-component developing toner characterized in that the surface of the third inorganic fine particles is treated with a hydrophobizing agent. "
Patent Document 3 states, "In a static charge image developing toner containing a colorant and a binder resin as main components, a compound represented by the following chemical formula 1 is contained as a colorant, and ethylene of bisphenol A is contained as a binder resin. Contains a polyester resin obtained by polycondensing an oxide adduct and a polyvalent carboxylic acid component selected from a divalent or higher carboxylic acid, a divalent or higher carboxylic acid anhydride, and a lower alkyl ester of a divalent or higher carboxylic acid. A yellow toner for non-magnetic one-component development, which comprises primary inorganic fine particles having an average primary volume particle size of 20 nm or less and secondary inorganic fine particles having an average primary volume particle size of 30 nm to 1 μm. ” It is disclosed.

International Publication No. 2009/044698 JP-A-2002-341587 Japanese Unexamined Patent Publication No. 2001-265063

Conventionally, in an electrophotographic image forming apparatus, for example, an image forming apparatus provided with a cleaning means having a cleaning blade has been used. In this image forming apparatus, for example, an image may be formed by using a toner for developing an electrostatic charge image containing silica particles as an external additive.

By the way, the cleaning blade is easily affected by the environment of temperature environment and humidity environment, and the cleaning blade becomes hard in a low temperature and low humidity environment. Therefore, for example, when an image having a high image density is repeatedly formed in a low temperature and low humidity environment using a toner for static charge image development containing silica particles as an external additive, color streaks may occur.

Therefore, an object of the present invention is that, in a toner for static charge image development having toner particles and an external additive containing silica particles, the number of silica particles in the circle equivalent diameter distribution is one maximum value. It is an object of the present invention to provide a toner for static charge image development in which the generation of color streaks is suppressed even when an image having a high image density is repeatedly formed in a low temperature and low humidity environment as compared with the case where only the particles are present.

The above problem is solved by the following means. That is,
The invention according to < 1 > is
Toner particles containing binder resin and
There are three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, an external addition containing silica particles in which the width of the adjacent maximum circle equivalent diameter is 20 nm or more and 50 nm or less. Agent and
Toner for static charge image development.

The invention according to < 2 > is
The toner for static charge image development according to < 1 > , wherein the three or more maximum circle-equivalent diameters are in the range of 3 nm or more and 300 nm or less.
The invention according to < 3 > is
The static charge image development according to < 1 > or < 2 > , wherein the circle-equivalent diameter of the maximum value located on the smallest diameter side of the circle-equivalent diameter distribution among the three or more maximum values is 3 nm or more and 100 nm or less. toner.
The invention according to < 4 > is
The item according to any one of < 1 > to < 3 > , wherein the circle-equivalent diameter of the maximum value located on the smallest diameter side of the circle-equivalent diameter distribution among the three or more maximum values is 50 nm or more and 100 nm or less. Toner for static charge image development.

The invention according to < 5 > is
The toner for developing an electrostatic charge image according to any one of < 1 > to < 4 > , wherein the silica particles contain sol-gel silica particles.
The invention according to < 6 > is
Any one of < 1 > to < 5 > , wherein the silica particles include silica particles having an average circularity of 0.6 or more and less than 0.9 and silica particles having an average circularity of 0.9 or more and 1.0 or less. The toner for developing an electrostatic charge image described in 1.

The invention according to < 7 > is
The toner for developing an electrostatic charge image according to any one of < 1 > to < 6 > , wherein the binder resin is a urea-modified polyester resin.
The invention according to < 8 > is
The toner for developing an electrostatic charge image according to any one of < 1 > to < 6 >, wherein the binder resin is a styrene (meth) acrylic resin.

The invention according to < 9 > is
A static charge image developer containing the toner for static charge image development according to any one of < 1 > to < 8 > .

The invention according to < 10 > is
The toner for static charge image development according to any one of < 1 > to < 8 > is accommodated, and the toner is accommodated.
A toner cartridge that is attached to and detached from the image forming device.

The invention according to < 11 > is
A developing means for accommodating the electrostatic charge image developing agent according to < 9 > and developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic charge image developing agent is provided.
A process cartridge that is attached to and detached from the image forming device.

The invention according to < 12 > is
Image holder and
A charging means for charging the surface of the image holder and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
A developing means that accommodates the electrostatic charge image developer according to < 9 > and develops the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic image developer.
A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A cleaning means having a cleaning blade for cleaning the surface of the image holder, and
A fixing means for fixing the toner image transferred to the surface of the recording medium, and
An image forming apparatus comprising.

The invention according to < 13 > is
The charging process that charges the surface of the image holder,
A static charge image forming step of forming a static charge image on the surface of the charged image holder, and
A development step of developing a static charge image formed on the surface of the image holder as a toner image by using the static charge image developer according to < 9 > .
A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A cleaning step of cleaning the surface of the image holder with a cleaning blade,
A fixing step of fixing the toner image transferred to the surface of the recording medium, and
An image forming method having.

According to the inventions relating to < 1 > , < 2 > , < 3 > , < 4 > , < 5 > , < 6 > , < 7 > , or < 8 > , an additive containing toner particles and silica particles. In the toner for static charge image development having the above, the image density of the silica particles is higher than that in the case where only one maximum value of the number frequency in the circle equivalent diameter distribution of the silica particles is present in a low temperature and low humidity environment. Provided is a toner for static charge image development in which the generation of color streaks is suppressed even when the particles are repeatedly formed.

According to the invention according to < 9 > , < 10 > , < 11 > , < 12 > , or < 13 > , silica is used in a static charge image developing toner having toner particles and an external agent containing silica particles. Higher image density under low temperature and low humidity environment than when a toner for static charge image development having an external additive containing silica particles in which only one maximum value of the number frequency exists in the equivalent circle diameter distribution of particles is applied. An electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method, which suppresses the generation of color streaks, is provided even when the above-mentioned images are repeatedly formed.

It is a schematic block diagram which shows the image forming apparatus which concerns on this embodiment. It is a schematic block diagram which shows the process cartridge which concerns on this embodiment.

Hereinafter, embodiments that are an example of the present invention will be described in detail.

<Toner for static charge image development>
The toner for developing an electrostatic charge image (hereinafter, referred to as “toner”) according to the present embodiment includes toner particles containing a binder resin and an external additive containing silica particles.
The silica particles have three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, the width of the adjacent maximum circle equivalent diameters is 20 nm or more and 50 nm or less.

Conventionally, in an electrophotographic image forming apparatus, for example, a method of cleaning residual toner remaining on an image holder by a cleaning means having a cleaning blade has been adopted. When an image is formed using this image forming apparatus, after the toner image on the image holder is transferred, the elastic cleaning blade is pressed against the image holder, and the toner is formed at the contact portion between the cleaning blade and the image holder. Is scraped off and the surface of the image holder is cleaned.
Here, when an image is formed using a developer having a toner containing silica particles as an external additive, when the residual toner reaches the contact portion between the cleaning blade and the image holder, the surface of the image holder is cleaned. A residue containing toner particles and silica particles (hereinafter sometimes referred to as "toner dam") is formed between the tip of the blade. Further, on the cleaning blade side of the toner dam, a residue containing silica particles (hereinafter, may be referred to as “external agent dam”) is formed. Then, the cleaning property is improved by forming the toner dam and the external additive dam.

On the other hand, the cleaning blade is easily affected by the environment of temperature environment and humidity environment, and the cleaning blade becomes hard in a low temperature and low humidity environment (for example, 15 ° C. and 10% RH). Then, when an image having a high image density (for example, an image density of 80% or more) is repeatedly formed in a low temperature and low humidity environment, color streaks may occur. This can be thought of as follows.
When forming a high image density image, the amount of toner for forming a high image density image is increased. Then, as the amount of silica particles desorbed from the toner also increases, the amount of silica particles supplied to the toner dam (external agent dam) also increases. Repeated formation of high image density images can result in agglomerated amounts of silica particles slipping through the cleaning blade. Since the cleaning blade is hard in a low-temperature and low-humidity environment, it is difficult for the shape of the cleaning blade to return to the place where the amount of silica particles gathered from the cleaning blade slips through. Then, it is considered that color streaks are generated by slipping through the toner particles.

On the other hand, the toner according to the present embodiment has three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, the width of the adjacent maximum circle equivalent diameter is 20 nm. By using silica particles having a characteristic of 50 nm or less as an external additive, the generation of color streaks is suppressed even when an image having a high image density is repeatedly formed in a low temperature and low humidity environment. The reason for this is not clear, but it is presumed as follows.

The silica particles having the above characteristics are silica particles in which the equivalent circle diameter distribution is widely distributed. Then, by using the silica particles having this property as an external additive, the silica particles supplied to the external additive dam are likely to be aggregated based on the closest packing, and a stronger external agent dam is formed. It is thought that.
On the other hand, if the silica particles are only supplied to the external additive dam, the silica particles agglomerate too strongly based on the closest packing, and the external additive dam becomes too strong. Since an external additive dam that has become too strong may cause a bundled amount of silica particles to slip through, it is preferable that the silica particles pass through and be replaced appropriately in the external additive dam.

Therefore, by using silica particles having three or more maximum values of the circle equivalent diameter distribution and the width of the adjacent maximum circle equivalent diameters of 20 nm or more and 50 nm or less as the external additive, the external agent dam can be used. Silica particles will slip through and replace. As a result, although a strong external additive dam is formed, the external additive dam does not become too strong, and it is considered that the slip-through of silica particles in a bundled amount is suppressed.

For the above reasons, it is presumed that the generation of color streaks is suppressed even when an image having a high image density is repeatedly formed from the cleaning blade in a low temperature and low humidity environment.

The details of the toner according to this embodiment will be described below.

The toner according to this embodiment is a toner particle and an external additive.

(Toner particles)
The toner particles are composed of, for example, a binder resin,, if necessary, a colorant, a mold release agent, and other additives.

-Bound resin-
Examples of the binder resin include styrenes (for example, styrene, parachlorostyrene, α-methylstyrene, etc.) and (meth) acrylic acid esters (for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (eg, acrylonitrile, Methacrylic acid, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, butadiene, etc.), etc. Examples thereof include a homopolymer of the above-mentioned monomer and a vinyl resin composed of a copolymer obtained by combining two or more kinds of these monomers.
Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosins, mixtures of these with the vinyl resins, or these. Examples thereof include a graft polymer obtained by polymerizing a vinyl-based monomer in the coexistence.
These binder resins may be used alone or in combination of two or more.

As the binder resin, a polyester resin is also suitable.
Examples of the polyester resin include known polyester resins.

Examples of the polyester resin include a condensed polymer of a polyvalent carboxylic acid and a polyhydric alcohol. As the polyester resin, a commercially available product may be used, or a synthetic resin may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.). , Alicyclic dicarboxylic acid (eg cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acid (eg, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), these anhydrides, or their lower grades (eg, 1 or more carbon atoms). (5 or less) Alkyl ester can be mentioned. Among these, as the polyvalent carboxylic acid, for example, an aromatic dicarboxylic acid is preferable.
As the polyvalent carboxylic acid, a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure may be used in combination with the dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, 1 to 5 carbon atoms) alkyl esters thereof.
The polyvalent carboxylic acid may be used alone or in combination of two or more.

Examples of the polyhydric alcohol include aliphatic diols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (for example, cyclohexanediol, cyclohexanedimethanol, etc.). Hydrogenated bisphenol A, etc.), aromatic diols (for example, ethylene oxide adduct of bisphenol A, propylene oxide adduct of bisphenol A, etc.) can be mentioned. Among these, as the polyhydric alcohol, for example, an aromatic diol and an alicyclic diol are preferable, and an aromatic diol is more preferable.
As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used in combination with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
The polyhydric alcohol may be used alone or in combination of two or more.

The glass transition temperature (Tg) of the polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically described in JIS K7121-1987 "Method for measuring transition temperature of plastics" for obtaining the glass transition temperature. It is determined by the "external glass transition start temperature".

The weight average molecular weight (Mw) of the polyester resin is preferably 5000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less.
The number average molecular weight (Mn) of the polyester resin is preferably 2000 or more and 100,000 or less.
The molecular weight distribution Mw / Mn of the polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed using a Tosoh GPC / HLC-8120GPC as a measuring device, a Tosoh column / TSKgel SuperHM-M (15 cm), and a THF solvent. The weight average molecular weight and the number average molecular weight are calculated from this measurement result using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

The polyester resin is obtained by a well-known manufacturing method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure inside the reaction system is reduced as necessary, and the reaction is carried out while removing water and alcohol generated during condensation.
When the raw material monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a dissolution aid to dissolve the monomer. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. If there is a monomer with poor compatibility, it is advisable to condense the monomer with poor compatibility with the monomer and the acid or alcohol to be polycondensed in advance, and then polycondensate with the main component. ..

Here, examples of the polyester resin include modified polyester resins in addition to the above-mentioned unmodified polyester resins. The modified polyester resin is a polyester resin having a bonding group other than an ester bond, or a polyester resin in which a resin component different from the polyester resin component is bonded by a covalent bond or an ionic bond. Examples of the modified polyester resin include a polyester resin in which a functional group such as an isocyanate group that reacts with an acid group or a hydroxyl group is introduced at the terminal, and a resin in which the terminal is modified by reacting with an active hydrogen compound.

As the modified polyester resin, a urea-modified polyester resin is particularly preferable. The content of the urea-modified polyester resin is preferably 5% by mass or more and 50% by mass or less, and more preferably 7% by mass or more and 20% by mass or less with respect to the total binder resin.

The urea-modified polyester resin is preferably a urea-modified polyester resin obtained by reacting a polyester resin having an isocyanate group (polyester prepolymer) with an amine compound (at least one reaction of a cross-linking reaction and an extension reaction). The urea-modified polyester resin may contain a urethane bond as well as a urea bond.

Examples of the polyester prepolymer having an isocyanate group include a polyester which is a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol, and a prepolymer obtained by reacting a polyester having active hydrogen with a polyhydric isocyanate compound. .. Examples of the group having active hydrogen contained in the polyester include hydroxyl groups (alcoholic hydroxyl groups and phenolic hydroxyl groups), amino groups, carboxyl groups, mercapto groups and the like, and alcoholic hydroxyl groups are preferable.

In the polyester prepolymer having an isocyanate group, examples of the polyvalent carboxylic acid and the polyhydric alcohol include compounds similar to the polyvalent carboxylic acid and the polyhydric alcohol described in the polyester resin.

Polyisocyanate compounds include aliphatic polyisocyanates (tetramethylene diisocyanate, hexamethylene diisocyanate, 2,6-diisocyanatomethyl caproate, etc.); alicyclic polyisocyanates (isophorone diisocyanate, cyclohexylmethane diisocyanate, etc.); aromatics. Diisocyanate (tolylene diisocyanate, diphenylmethane diisocyanate, etc.); aromatic aliphatic diisocyanate (α, α, α', α'-tetramethylxylylene diisocyanate, etc.); isocyanurates; the polyisocyanate is a phenol derivative, oxime, caprolactam, etc. Examples include those blocked with a blocking agent.
The polyisocyanate compound may be used alone or in combination of two or more.

The ratio of the polyisocyanate compound is preferably 1/1 or more and 5/1 or less, as the equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester prepolymer having a hydroxyl group. It is preferably 1.2 / 1 or more and 4/1 or less, and more preferably 1.5 / 1 or more and 2.5 / 1 or less. When [NCO] / [OH] is set to 5 or less, for example, a decrease in low temperature fixability is likely to be suppressed.

In the polyester prepolymer having an isocyanate group, the content of the component derived from the polyhydric isocyanate compound is preferably 0.5% by mass or more and 40% by mass or less, more preferably, with respect to the entire polyester prepolymer having an isocyanate group. It is 1% by mass or more and 30% by mass or less, more preferably 2% by mass or more and 20% by mass or less. When the content of the component derived from the polyisocyanate is 40% by mass or less, for example, the decrease in low temperature fixability is easily suppressed.

The number of isocyanate groups contained in one molecule of the polyester prepolymer having an isocyanate group is preferably 1 or more on average, more preferably 1.5 or more and 3 or less on average, and still more preferably 1.8 or more on average 2. .5 or less. When the number of isocyanate groups is one or more per molecule, the molecular weight of the urea-modified polyester resin after the reaction increases.

Examples of the amine compound that reacts with the polyester prepolymer having an isocyanate group include diamines, trivalent or higher polyamines, amino alcohols, amino mercaptans, amino acids, and compounds in which these amino groups are blocked.

Examples of the diamine include aromatic diamines (phenylenediamine, diethyltoluenediamine, 4,4'diaminodiphenylmethane, etc.); alicyclic diamines (4,4'-diamino-3,3'dimethyldicyclohexylmethane, diaminecyclohexane, isophoronediamine, etc.) ); And aliphatic diamines (ethylenediamine, tetramethylenediamine, hexamethylenediamine, etc.) and the like.
Examples of the triamine or higher polyamine include diethylenetriamine and triethylenetetramine.
Examples of the amino alcohol include ethanolamine and hydroxyethylaniline.
Examples of the amino mercaptan include aminoethyl mercaptan and aminopropyl mercaptan.
Examples of amino acids include aminopropionic acid and aminocaproic acid.
Examples of those that block these amino groups include amine compounds such as diamines, trivalent or higher polyamines, aminoalcohols, aminomercaptans, and amino acids, and ketimine compounds obtained from ketone compounds (acetones, methyl ethyl ketones, methyl isobutyl ketones, etc.). Examples include oxazoline compounds.
Of these amine compounds, ketimine compounds are preferred.
The amine compound may be used alone or in combination of two or more.

The urea-modified polyester resin is a polyester resin (polyester prepolymer) having an isocyanate group by a terminator that terminates at least one of the crosslinking reaction and the elongation reaction (hereinafter, also referred to as “crosslinking / elongation reaction terminator”). A resin in which the molecular weight after the reaction is adjusted by preparing a reaction with an amine compound (at least one of a cross-linking reaction and an extension reaction) may be used.
Examples of the cross-linking / extension reaction terminator include monoamines (diethylamine, dibutylamine, butylamine, laurylamine, etc.) and those that block them (ketimine compounds).

The ratio of the amine compound is preferably 1/2 or more as the equivalent ratio [NCO] / [NHx] of the isocyanate group [NCO] in the polyester prepolymer having an isocyanate group and the amino group [NHx] in the amines. It is 1/1 or less, more preferably 1 / 1.5 or more and 1.5 / 1 or less, and further preferably 1 / 1.2 or more and 1.2 / 1 or less. When [NCO] / [NHx] is set in the above range, the molecular weight of the urea-modified polyester resin after the reaction increases.

The glass transition temperature of the urea-modified polyester resin is preferably 40 ° C. or higher and 65 ° C. or lower, and more preferably 45 ° C. or higher and 60 ° C. or lower. The number average molecular weight (Mn) is preferably 2500 or more and 50,000 or less, and more preferably 2500 or more and 30,000 or less. The weight average molecular weight (Mw) is preferably 10,000 or more and 500,000 or less, and more preferably 30,000 or more and 100,000 or less.

A styrene (meth) acrylic resin is also suitable. The styrene (meth) acrylic resin is a copolymer of at least a styrene-based monomer (a monomer having a styrene skeleton) and a (meth) acrylic-based monomer (a monomer having a (meth) acryloyl skeleton). It is a polymer. The styrene (meth) acrylic resin contains, for example, a copolymer of the above-mentioned styrenes monomer and the above-mentioned (meth) acrylic acid esters monomer.
In addition, "(meth) acrylic" is an expression including both "acrylic" and "methacryl".

Specific examples of the styrene-based monomer include styrene and alkyl-substituted styrene (for example, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene). Ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrene (for example, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), vinylnaphthalene, and the like can be mentioned. The styrene-based monomer may be used alone or in combination of two or more.
Among these, as the styrene-based monomer, styrene is preferable in terms of ease of reaction, ease of control of reaction, and availability.

Specific examples of the (meth) acrylic monomer include (meth) acrylic acid and (meth) acrylic acid ester. Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl ester (for example, methyl (meth) acrylic acid, ethyl (meth) acrylic acid, n-propyl (meth) acrylic acid, n (meth) acrylic acid. -Butyl, n-pentyl (meth) acrylate, n-hexyl acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylate n-dodecyl, n-lauryl (meth) acrylate, n-tetradecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-octadecyl (meth) acrylate, isopropyl (meth) acrylate, (meth) Isobutyl acrylate, t-butyl (meth) acrylate, isopentyl (meth) acrylate, amyl (meth) acrylate, neopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, (meth) ) Isooctyl acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, etc.), aryl (meth) acrylate (eg, phenyl (meth) acrylate, Biphenyl (meth) acrylate, diphenylethyl (meth) acrylate, t-butylphenyl (meth) acrylate, tarphenyl (meth) acrylate, etc.), dimethylaminoethyl (meth) acrylate, diethylamino (meth) acrylate Examples thereof include ethyl, methoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, β-carboxyethyl (meth) acrylate, and (meth) acrylamide. The (meth) acrylic acid-based monomer may be used alone or in combination of two or more.
Among the (meth) acrylic monomers, among these (meth) acrylic esters, the number of carbon atoms is 2 or more and 14 or less (preferably 2 or more and 10 or less, more preferably 3 or more) from the viewpoint of fixability. A (meth) acrylic acid ester having an alkyl group (8 or less) is preferable.

The copolymerization ratio (mass standard, styrene-based monomer / (meth) acrylic-based monomer) of the styrene-based monomer and the (meth) acrylic-based monomer is, for example, 85/15 to 70/30. That is good.

The styrene (meth) acrylic resin may have a crosslinked structure. Examples of the styrene (meth) acrylic resin having a crosslinked structure include crosslinked products obtained by at least copolymerizing a styrene-based monomer, a (meth) acrylic acid-based monomer, and a crosslinkable monomer. ..

Examples of the crosslinkable monomer include bifunctional or higher functional crosslinkers.
Examples of the bifunctional cross-linking agent include divinylbenzene, divinylnaphthalene, and di (meth) acrylate compounds (for example, diethylene glycol di (meth) acrylate, methylenebis (meth) acrylamide, decanediol diacrylate, glycidyl (meth) acrylate, etc.). , Polyester-type di (meth) acrylate, 2-([1'-methylpropylideneamino] carboxyamino) ethyl methacrylate and the like.
Examples of the polyfunctional cross-linking agent include tri (meth) acrylate compounds (for example, pentaerythritol tri (meth) acrylate, trimethylolethanetri (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc.) and tetra (meth) acrylate. Compounds (eg, pentaerythritol tetra (meth) acrylate, oligoester (meth) acrylate, etc.), 2,2-bis (4-methacryloxy, polyethoxyphenyl) propane, diallyl phthalate, triaryl cyanurate, triaryl isocyanurate, Examples thereof include triaryltrimethylate and diallyl chlorendate.

The copolymerization ratio of the crosslinkable monomer to all the monomers (mass basis, crosslinkable monomer / total monomer) is preferably, for example, 2/1000 to 30/1000.

The glass transition temperature (Tg) of the styrene (meth) acrylic resin is preferably, for example, 50 ° C. or higher and 75 ° C. or lower, preferably 55 ° C. or higher and 65 ° C. or lower, and more preferably 57 ° C. or higher and 60 ° C. or lower in terms of fixability. Is.
The glass transition temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically described in JIS K 7121-1987 "Method for measuring transition temperature of plastics". It is obtained by the "external glass transition start temperature" of.

The weight average molecular weight of the styrene (meth) acrylic resin is, for example, preferably 30,000 or more and 200,000 or less, preferably 40,000 or more and 100,000 or less, and more preferably 50,000 or more and 80,000 or less in terms of storage stability.
The weight average molecular weight is measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed using a Tosoh GPC / HLC-8120GPC as a measuring device, a Tosoh column / TSKgel SuperHM-M (15 cm), and a THF solvent. The weight average molecular weight is calculated from this measurement result using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

Various polymerization methods (for example, solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.) are applied to the styrene (meth) acrylic resin. Further, a known operation (for example, batch type, semi-continuous type, continuous type, etc.) is applied to the polymerization reaction.

The content of the binder resin is, for example, preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and 60% by mass or more and 85% by mass or less with respect to the entire toner particles. More preferred.

-Release agent-
Examples of the release agent include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; ester waxes such as fatty acid esters and montanic acid esters. ; And so on. The release agent is not limited to this.

The melting temperature of the release agent is preferably 50 ° C. or higher and 110 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower.
The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) by the "melting peak temperature" described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperature of plastics". ..

The content of the release agent is, for example, preferably 1% 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 entire toner particles.

-Colorant-
Colorants include, for example, carbon black, chrome yellow, Hansa yellow, benzine yellow, slene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, brilliant. Carmin 6B, Dupont Oil Red, Pyrazolon Red, Resole Red, Rhodamin B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultra Marine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, or aclysine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black Examples thereof include various dyes such as system, polymethine type, triphenylmethane type, diphenylmethane type, and thiazole type.
One type of colorant may be used alone, or two or more types may be used in combination.

As the colorant, a surface-treated colorant may be used if necessary, or may be used in combination with a dispersant. Further, a plurality of kinds of colorants may be used in combination.

The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Other additives-
Examples of other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as an internal additive.

-Characteristics of toner particles, etc.-
The toner particles may be toner particles having a single layer structure, or are toner particles having a so-called core-shell structure composed of a core portion (core particles) and a coating layer (shell layer) that covers the core portion. You may.
Here, the toner particles having a core-shell structure include, for example, a core portion composed of a binder resin and, if necessary, other additives such as a colorant and a mold release agent, and a binder resin. It is preferably composed of a composed coating layer.

The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

The various average particle sizes and various particle size distribution indexes of the toner particles were measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolytic solution was measured using ISOTON-II (manufactured by Beckman Coulter). Toner.
At the time of measurement, as a dispersant, 0.5 mg or more and 50 mg or less of the measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate). This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolytic solution in which the sample is suspended is dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm or more and 60 μm or less is obtained by using a 100 μm aperture with a Coulter Multisizer II. Measure. The number of particles to be sampled is 50,000.
Cumulative distribution of volume and number is drawn from the small diameter side for each particle size range (channel) divided based on the measured particle size distribution, and the cumulative 16% particle size is volume particle size D16v and number particle size. The particle size having D16p and a cumulative 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size having a cumulative number of 84% is defined as the volume particle size D84v and the number particle size D84p.
Using these, the volume particle size distribution index (GSDv) is calculated as (D84v / D16v) ^1/2 , and the number particle size distribution index (GSDp) is calculated as (D84p / D16p) ^1/2 .

(External agent)
The external additive has three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, the width of the adjacent maximum circle equivalent diameter is 20 nm or more and 50 nm or less. including. The external additive may include other external additives and the like.

-Silica particles-
Here, in the present specification, the "number frequency" indicates the abundance ratio of the silica particles in the range in which the circle equivalent diameter is divided by 10 nm in the circle equivalent diameter distribution of the silica particles.
The "maximum value" (peak) is a curve of the number frequency in the circle equivalent diameter distribution (circle equivalent diameter distribution curve) in the division of every 10 nm based on the distribution of the circle equivalent diameter measured by the measurement method described later. It represents the point where the curve that repeats in the vertical direction of the circle equivalent diameter distribution curve turns from the ascending direction to the descending direction in the mountainous part where the curve can be drawn. Of the points (minimum values) that turn from the falling direction to the rising direction in the curve that repeats in the vertical direction of the circle equivalent diameter distribution curve adjacent to the point that turns in the falling direction, the difference in the number frequency from the one with the higher number frequency is 3 Represents the part that is% or more.
In the circle-equivalent diameter distribution curve, the part where a mountainous curve that repeats in the vertical direction cannot be drawn (the part where the slope becomes gentle in the upward or downward direction and the part where the slope becomes flat) is not visually recognized as a maximum value. It is a part. Even if a curved curve that repeats in the vertical direction can be drawn, if the difference between the minimum value adjacent to the maximum value and the minimum value with the higher number frequency is less than 3%, it is set as the maximum value. This is the part that is not considered.

The "adjacent maximum value" represents the nth maximum value on the small diameter side and the n + 1th maximum value on the large diameter side from the nth maximum value.
The "width of the circle equivalent diameter of the adjacent maximum value" represents the value obtained by subtracting the circle equivalent diameter of the nth maximum value on the small diameter side from the circle equivalent diameter of the n + 1th maximum value on the large diameter side.

Here, the equivalent circle diameter of the silica particles is measured by the following method.
An image was taken by observing the equivalent circle diameter of the silica particles with a scanning electron microscope SEM (Scanning Electron Microscope) device (S-4100, manufactured by Hitachi, Ltd.), and this image was taken by an image analyzer (LUZEX III, manufactured by Nireco). ), The area of each particle is measured by image analysis, and the equivalent circle diameter is calculated from this area value. This circle-equivalent diameter is calculated for 100 silica particles.
The average circularity of the silica particles is obtained as 50% circularity in the cumulative frequency of the circularity of 100 primary particles obtained by the above plane image analysis.
Further, the circle equivalent diameter distribution is calculated based on the calculated circle equivalent diameter in the range of every 10 nm. The circle equivalent diameter distribution curve draws a curve of the number frequency in the circle equivalent diameter distribution from this circle equivalent diameter distribution.

It should be noted that the width of the adjacent maximum circle-equivalent diameter of the silica particles is 20 nm or more and 50 nm or less, and the width of the adjacent maximum circle-equivalent diameter is an appropriate width under a low temperature and low humidity environment. Even when an image having an image density is repeatedly formed, the generation of color streaks is suppressed, so a curve of the number frequency in the circle equivalent diameter distribution is drawn in the range of every 10 nm. The width of the equivalent circle diameter of the adjacent maximum values is preferably in the range of 20 nm or more and 40 nm or less.

The silica particles have a maximum number frequency of 3 or more (preferably 4 or more) in the circle equivalent diameter distribution. The upper limit of the number of maximum values is not particularly limited, and examples thereof include 6 or less (preferably 5 or less).

The maximum value of 3 or more of the number frequency in the circle equivalent diameter distribution is that the generation of color streaks is further suppressed even when images with high image density are repeatedly formed in a low temperature and low humidity environment. The equivalent diameter is preferably in the range of 3 nm or more and 300 nm or less. In the same respect, it is preferably present in the range of 30 nm or more and 300 nm or less, more preferably in the range of 50 nm or more and 250 nm or less, and further preferably in the range of 50 nm or more and 220 nm or less.

Of the maximum values of the number frequency in the circle equivalent diameter distribution, the circle equivalent diameter of the maximum value on the smallest diameter side causes color streaks even when images with high image density are repeatedly formed in a low temperature and low humidity environment. Is more preferably in the range of 3 nm or more and 100 nm or less, preferably in the range of 30 nm or more and 100 nm or less, and more preferably in the range of 50 nm or more and 100 nm or less.

The maximum circle-equivalent diameter of three or more in the circle-equivalent diameter distribution suppresses the generation of color streaks even when images with high image density are repeatedly formed in a low-temperature and low-humidity environment. In terms of points, for example, it may be in the following range.
The maximum circle equivalent diameter on the smallest diameter side is 50 nm or more and 100 nm or less, the second maximum circle equivalent diameter from the smallest diameter side is in the range of 70 nm or more and 150 nm or less, and the third maximum circle equivalent diameter from the smallest diameter side. Is preferably present in the range of 90 nm or more and 200 nm or less. Further, the circle-equivalent diameter of the fourth maximum value from the small diameter side may exist in the range of, for example, 150 nm or more and 250 nm or less.
The maximum circle-equivalent diameter on the smallest diameter side is in the range of 50 nm or more and 100 nm or less, the second maximum circle-equivalent diameter from the small diameter side is in the range of 80 nm or more and 130 nm or less, and the third maximum value from the small diameter side. The equivalent circle diameter of is preferably in the range of 120 nm or more and 170 nm or less. Further, the circle-equivalent diameter of the fourth maximum value from the small diameter side preferably exists in the range of, for example, 140 nm or more and 220 nm or less.

The frequency ratio of adjacent maximums of the circle equivalent diameter distribution, that is, the ratio of the number frequency at the nth maximum value and the number frequency at the n + 1th maximum value (number frequency at the nth maximum value / n + 1th maximum value). The number frequency) is preferably 0.3 or more (preferably 0.5 or more). When the circle-equivalent diameter distribution curve of the silica particles satisfies this condition, the generation of color streaks is more likely to be suppressed even when an image having a high image density is repeatedly formed in a low temperature and low humidity environment.
Of the adjacent maximum values of the circle equivalent diameter distribution, the difference between the number frequency at the maximum value with the smaller number frequency and the number frequency at the minimum value sandwiched between the adjacent maximum values is 3% or more (preferably). May be 5% or more).

The silica particles may be silica, that is, particles containing SiO ₂ as a main component, and may be crystalline or amorphous. Further, the silica particles may be particles produced from a silicon compound such as water glass or alkoxysilane as a raw material, or particles obtained by pulverizing quartz.
Specifically, examples of the silica particles include solgel silica particles, aqueous colloidal silica particles, alcoholic silica particles, fumed silica particles obtained by a vapor phase method, and molten silica particles. The silica particles may be used alone or in combination of two or more.

Among these silica particles, the silica particles have three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, the width of the adjacent maximum circle equivalent diameter is 20 nm. It is preferable to contain at least solgel silica particles from the viewpoint of satisfying the above 50 nm or less. It also preferably contains fumed silica particles and sol-gel silica particles.

Sol-gel silica particles are obtained, for example, as follows. Tetramethoxysilane is added dropwise and stirred in the presence of water and alcohol while applying temperature using aqueous ammonia as a catalyst. Next, the solvent is removed from the silica sol suspension obtained by the reaction and dried to obtain the desired monodisperse spherical silica particles. After that, the obtained monodisperse spherical silica particles are subjected to surface treatment (hydrophobic treatment or the like), if necessary.

Silica particles include, for example, silica particles having different average circle-equivalent diameters in that the generation of color streaks is further suppressed even when images with high image density are repeatedly formed in a low-temperature and low-humidity environment. Is good.

Specifically, for example, it is preferable to include silica particles having a circularity of 0.6 or more and less than 0.9 and silica particles having a circularity of 0.9 or more and 1.0 or less. When silica particles having a circularity of 0.6 or more and less than 0.9 and silica particles having a circularity of 0.9 or more and 1.0 or less are included, for example, the circularity is 0.6 with respect to the entire silica particles. Silica particles of 30% by mass or more and less than 0.9 are 30% by mass or more and 70% by mass or less (preferably 40% by mass or more and 60% by mass or less), and silica particles having a circularity of 0.9 or more and 1.0 or less are 30% by mass or more. It is preferably 70% by mass or more (preferably 40% by mass or more and 60% by mass or less).
Further, the content ratio of the silica particles having a circularity of 0.6 or more and less than 0.9 and the silica particles having a circularity of 0.9 or more and 1.0 or less (silica particles having a circularity of 0.6 or more and less than 0.9). / Silica particles having a circularity of 0.9 or more and 1.0 or less) are preferably 30/70 or more and 70/30 or less (preferably 40/60 or more and 60/40 or less) in terms of mass ratio.

To include silica particles having a circularity of 0.6 or more and less than 0.9 and silica particles having a circularity of 0.9 or more and 1.0 or less, for example, sol-gel silica particles having a low average circularity And a method of combining with sol-gel silica particles having a high average circularity, a method of combining with fumed silica particles having a low average circularity and sol-gel silica particles having a high average circularity, and the like. The blending ratio when the silica particles are combined is the above-mentioned characteristic (there are three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, the width of the circle equivalent diameter of the adjacent maximum values is It may be adjusted according to the desired characteristics within a range satisfying (20 nm or more and 50 nm or less).

In addition, a mountainous portion from the minimum value to the minimum value having three or more maximum values of the number frequency in the circle equivalent diameter distribution and each maximum value of the circle equivalent diameter distribution curve (hereinafter, "the portion having the maximum value"). The relationship between the average circularity of the silica particles (also referred to as) is not particularly limited, but the generation of color streaks is further suppressed even when an image having a high image density is repeatedly formed in a low temperature and low humidity environment. In that respect, for example, the following relationship is preferable.
The average circularity of the silica particles in the portion having the maximum value on the smallest diameter side is 0.6 or more and less than 0.9 (preferably 0.7 or more and 0.85 or less), and the portion having the second maximum value from the smallest diameter side. The average circularity of the silica particles is 0.9 or more and 1.0 or less (preferably 0.91 or more and 0.96 or less), and the average circularity of the silica particles in the portion having the third maximum value from the small diameter side is 0.9. It is preferably 1.0 or more (preferably 0.91 or more and 0.96 or less). Further, the average circularity of the silica particles in the portion having the fourth maximum value from the small diameter side is preferably, for example, 0.6 or more and less than 1.0 (preferably 0.7 or more and 0.91 or less).

Here, the circularity of the silica particles is measured by the following method.
The circularity of the silica particles is obtained by observing the primary particles after dispersing the silica particles in a resin particle body (for example, polyester resin, weight average molecular weight Mw = 500,000) having a volume average particle diameter of 100 μm with an SEM device. It is obtained as "100 / SF2" calculated by the following formula from the plane image analysis of the obtained primary particles.
-Formula: Circularity (100 / SF2) = 4π × (A / I ² )
[In the formula, I represents the peripheral length of the primary particle on the image, and A represents the projected area of the primary particle.
Then, the average circularity of the silica particles is obtained as 50% circularity in the cumulative frequency of the circularity of 100 primary particles obtained by the plane image analysis.
Further, each average circularity in the portion having each maximum value is obtained as 50% circularity in the cumulative frequency of circularity for each portion having each maximum value.

The surface of the silica particles should be hydrophobized. The hydrophobizing treatment is performed, for example, by immersing silica particles in a hydrophobizing agent. The hydrophobizing agent is not particularly limited, and examples thereof include known organic silicon compounds having an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc.), and specific examples thereof include a silane compound (for example, a silazane compound). For example, a silane coupling agent of silane compounds such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylchlorosilane and trimethylmethoxysilane; hexamethyldisilazane; tetramethyldisilazane and the like can be mentioned. Examples of the hydrophobizing agent include silicone oil, titanate-based coupling agent, and aluminum-based coupling agent. These may be used alone or in combination of two or more.
The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 200 parts by mass or less with respect to 100 parts by mass of silica particles.

When a low image density image is repeatedly formed in a high temperature and high humidity environment using a toner having an external additive containing silica particles, color streaks may occur.
However, by using the toner according to the present embodiment, the generation of color streaks is likely to be suppressed even when an image having a low image density is repeatedly formed in a high temperature and high humidity environment. The reason for this is not clear, but it is presumed as follows.

When an image having a low image density is repeatedly formed in a high temperature and high humidity environment, the toner is less replaced in the developing means, the toner continues to receive a mechanical load, and the silica particles are easily buried in the toner particles. Therefore, the amount of silica particles supplied to the toner dam is reduced. In addition, since the amount of silica particles supplied to the toner dam is reduced, an excessively strong toner dam may be formed.
On the other hand, in a high-temperature and high-humidity environment, the cleaning blade becomes soft and easily deformed, and by repeatedly forming images with low image density, less external additive slips through the cleaning blade, so that the posture of the cleaning blade changes. It becomes unstable. Then, when an excessively strong toner dam is formed and the posture of the cleaning blade is destabilized, the cleaning blade is likely to be chipped, and when the cleaning blade is chipped, color streaks are generated. Conceivable.

On the other hand, there are three or more maximum values of the number frequency in the circle equivalent diameter distribution, and among the three or more maximum values, the width of the circle equivalent diameter of the adjacent maximum values is 20 nm or more and 50 nm or less. By using the above as an external additive, even if the toner receives a mechanical load, the mechanical load is dispersed. Therefore, the silica particles are easily suppressed from being embedded in the toner particles, and the silica particles are easily supplied to the toner dam. Further, by supplying the silica particles having the above characteristics to the toner dam, the toner dam has an appropriate hardness. Further, in the external additive dam formed on the cleaning blade side of the toner dam, the silica particles appropriately pass through the cleaning blade and are replaced, so that the posture of the cleaning blade is stabilized. As a result, it is considered that the generation of color streaks is suppressed because the generation of chipping of the cleaning blade is suppressed.
For the above reasons, it is presumed that the generation of color streaks is likely to be suppressed even when an image having a low image density is repeatedly formed in a high temperature and high humidity environment.

-Other external additives-
Examples of other external additives include inorganic particles other than silica particles.
Other inorganic particles include, for example, aluminum oxide (alumina), titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, magnesium oxide, zirconium oxide, charcoal. Examples include particles such as silicon and silicon nitride.

The surface of the other inorganic particles should be hydrophobized. The hydrophobizing treatment is performed, for example, by immersing the inorganic particles in a hydrophobizing agent. The hydrophobizing agent is not particularly limited, and examples thereof include a silane-based coupling agent, a silicone oil, a titanate-based coupling agent, and an aluminum-based coupling agent. These may be used alone or in combination of two or more.
The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of other inorganic particles.

Other external additives include resin particles (resin particles such as polystyrene, polymethylmethacrylate (PMMA), and melamine resin), cleaning activators (for example, metal salts of higher fatty acids typified by zinc stearate, and fluorine-based high-grade agents. Particles of molecular weight) and the like.

The amount (content) of the other external additives is preferably 0.05% by mass or more and 5.0% by mass or less, and 0.5% by mass or more and 3.0% by mass or less, based on the toner particles. The following is more preferable.

(Toner manufacturing method)
Next, a method for producing toner according to this embodiment will be described.
The toner according to the present embodiment can be obtained by externally adding an external additive to the toner particles after producing the toner particles.

The toner particles may be produced by any of a dry production method (for example, a kneading and pulverizing method) and a wet production method (for example, an agglomeration coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). The method for producing the toner particles is not particularly limited to these production methods, and a well-known production method is adopted.
Among these, it is preferable to obtain toner particles by the aggregation and coalescence method.

Specifically, for example, when the toner particles are produced by the aggregation and coalescence method,
A step of preparing a resin particle dispersion liquid in which resin particles to be a binder resin are dispersed (resin particle dispersion liquid preparation step) and a step of preparing the resin particle dispersion liquid and in the resin particle dispersion liquid (after mixing other particle dispersion liquids as necessary). (In the dispersion), resin particles (other particles if necessary) are agglomerated to form agglomerated particles (aggregated particle forming step), and the agglomerated particle dispersion in which the agglomerated particles are dispersed is heated. , Agglomerated particles are fused and coalesced to form toner particles (fusion and coalescence step), and toner particles are manufactured.

The details of each step will be described below.
In the following description, a method of obtaining toner particles containing a colorant and a mold release agent will be described, but the colorant and the mold release agent are used as needed. Of course, other additives other than colorants and mold release agents may be used.

-Resin particle dispersion liquid preparation process-
First, together with the resin particle dispersion liquid in which the resin particles to be the binder resin are dispersed, for example, a colorant particle dispersion liquid in which the colorant particles are dispersed and a release agent particle dispersion liquid in which the release agent particles are dispersed are prepared. To do.

Here, the resin particle dispersion liquid is prepared, for example, by dispersing the resin particles in a dispersion medium with a surfactant.

Examples of the dispersion medium used in the resin particle dispersion liquid include an aqueous medium.
Examples of the aqueous medium include distilled water, water such as ion-exchanged water, alcohols, and the like. These may be used alone or in combination of two or more.

Examples of the surfactant include anionic surfactants such as sulfate ester type, sulfonate type, phosphoric acid ester type and soap type; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol. Examples thereof include nonionic surfactants such as systems, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
The surfactant may be used alone or in combination of two or more.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion liquid include general dispersion methods such as a rotary shear type homogenizer, a ball mill having a medium, a sand mill, and a dyno mill. Further, depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion liquid by, for example, a phase inversion emulsification method.
In the phase inversion emulsification method, the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to the organic continuous phase (O phase) to neutralize the resin, and then the aqueous medium is used. A method in which the (W phase) is charged to convert the resin from W / O to O / W (so-called phase inversion) to discontinue the phase, and the resin is dispersed in an aqueous medium in the form of particles. Is.

The volume average particle diameter of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less. preferable.
The volume average particle size of the resin particles is determined by using the particle size distribution obtained by the measurement of a laser diffraction type particle size distribution measuring device (for example, manufactured by Horiba Seisakusho, LA-700) with respect to the divided particle size range (channel). , The cumulative distribution is subtracted from the small particle size side for the volume, and the particle size that is cumulative 50% of all particles is measured as the volume average particle size D50v. The volume average particle diameter of the particles in the other dispersion is also measured in the same manner.

The content of the resin particles contained in the resin particle dispersion is, for example, preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

In the same manner as the resin particle dispersion, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared. That is, regarding the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion, the colorant particles dispersed in the colorant particle dispersion and the release agent particle dispersion are used. The same applies to the disperse of the release agent particles.

-Agglomerated particle formation process-
Next, the colorant particle dispersion and the release agent particle dispersion are mixed together with the resin particle dispersion.
Then, in the mixed dispersion, the resin particles, the colorant particles, and the release agent particles are heteroaggregated to form the resin particles, the colorant particles, and the release agent particles having a diameter close to the diameter of the target toner particles. Form agglomerated particles containing.

Specifically, for example, a flocculant is added to the mixed dispersion, the pH of the mixed dispersion is adjusted to acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. The particles are heated to a temperature of the glass transition temperature of the resin particles (specifically, for example, the glass transition temperature of the resin particles is -30 ° C or higher and the glass transition temperature is -10 ° C or lower), and the particles dispersed in the mixed dispersion are aggregated. , Form agglomerated particles.
In the agglomerated particle forming step, for example, the mixed dispersion is stirred with a rotary shear type homogenizer, the above aggregating agent is added at room temperature (for example, 25 ° C.), and the pH of the mixed dispersion is acidic (for example, pH is 2 or more and 5 or less). ), And if necessary, a dispersion stabilizer may be added, and then the above heating may be performed.

Examples of the flocculant include a surfactant used as a dispersant added to the mixed dispersion, a surfactant having the opposite polarity, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of the surfactant used is reduced and the charging characteristics are improved.
If necessary, an additive that forms a complex or a similar bond with the metal ion of the flocculant may be used. As this additive, a chelating agent is preferably used.

Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride and aluminum sulfate, and inorganics such as polyaluminum chloride, polyaluminum hydroxide and calcium polysulfide. Examples include metal salt polymers.
As the chelating agent, a water-soluble chelating agent may be used. Examples of the chelating agent include oxycarboxylic acids such as tartrate acid, citric acid and gluconic acid, iminodic acid (IDA), nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid (EDTA).
The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the resin particles.

-Fusion / unification process-
Next, the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed is heated to, for example, a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10 to 30 ° C. higher than the glass transition temperature of the resin particles). Are fused and united to form toner particles.

Toner particles are obtained through the above steps.
After obtaining the agglomerated particle dispersion liquid in which the agglomerated particles are dispersed, the agglomerated particle dispersion liquid and the resin particle dispersion liquid in which the resin particles are dispersed are further mixed, and the resin particles are further added to the surface of the agglomerated particles. The step of aggregating so as to adhere to form the second agglomerated particles and the second agglomerated particle dispersion liquid in which the second agglomerated particles are dispersed are heated to fuse and unite the second agglomerated particles. , Toner particles may be produced through the steps of forming toner particles having a core / shell structure.

Here, after the fusion / coalescence step is completed, the toner particles formed in the solution are subjected to a known washing step, solid-liquid separation step, and drying step to obtain toner particles in a dried state.
In the cleaning step, it is preferable to sufficiently perform replacement cleaning with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, or the like may be performed from the viewpoint of productivity. The drying step is also not particularly limited, but from the viewpoint of productivity, freeze-drying, air-flow drying, fluid drying, vibration-type fluid drying and the like may be performed.

Next, a case of producing a toner having toner particles containing a urea-modified polyester resin will be described.
Toner particles containing a urea-modified polyester resin as a binder resin may be obtained by the following dissolution / suspension method. The method for obtaining the toner particles containing the unmodified polyester resin and the urea-modified polyester resin as the binder resin will be described, but the toner particles may contain only the urea-modified polyester resin as the binder resin.

-Oil phase liquid preparation process-
An oil phase liquid in which a toner particle material containing an unmodified polyester resin, a polyester prepolymer having an isocyanate group, an amine compound, a colorant, and a mold release agent is dissolved or dispersed in an organic solvent is prepared (oil phase liquid preparation step). .. This oil phase liquid preparation step is a step of dissolving or dispersing the toner particle material in an organic solvent to obtain a mixed liquid of the toner material.

The oil phase liquid is prepared by 1) a method of preparing by dissolving or dispersing the toner material in an organic solvent all at once, and 2) kneading the toner material in advance and then dissolving or dispersing this kneaded compound in an organic solvent. 3) A method of preparing by dissolving an unmodified polyester resin, a polyester prepolymer having an isocyanate group, and an amine compound in an organic solvent, and then dispersing a colorant and a mold release agent in the organic solvent. 4) A method of preparing by dissolving an unmodified polyester resin, a polyester prepolymer having an isocyanate group, and an amine compound in an organic solvent after dispersing a colorant and a mold release agent in an organic solvent. Toner particle materials (unmodified polyester resin, colorant, and mold release agent) other than the polyester prepolymer having a group and the amine compound are dissolved or dispersed in an organic solvent, and then the polyester pre having an isocyanate group is dissolved in this organic solvent. Method of dissolving and preparing polymer and amine compound, 6) Dissolve or disperse toner particle material (unmodified polyester resin, colorant, and mold release agent) other than polyester prepolymer or amine compound having isocyanate group in organic solvent. After that, a method of preparing by dissolving a polyester prepolymer having an isocyanate group or an amine compound in this organic solvent can be mentioned. The method for preparing the oil phase liquid is not limited to these.

Examples of the organic solvent of the oil phase liquid include ester solvents such as methyl acetate and ethyl acetate; ketone solvents such as methyl ethyl ketone and methyl isopropyl ketone; aliphatic hydrocarbon solvents such as hexane and cyclohexane; dichloromethane, chloroform, trichloroethylene and the like. Examples thereof include halogenated hydrocarbon solvents. It is preferable that these organic solvents dissolve the binder resin, dissolve in water at a rate of 0% by mass or more and 30% by mass or less, and have a boiling point of 100 ° C. or less. Among these organic solvents, ethyl acetate is preferable.

-Suspension preparation process-
Next, the obtained oil phase liquid is dispersed in the aqueous phase liquid to prepare a suspension (suspension preparation step).
Then, along with the preparation of the suspension, the reaction between the polyester prepolymer having an isocyanate group and the amine compound is carried out. Then, a urea-modified polyester resin is produced by this reaction. This reaction involves at least one of a molecular chain cross-linking reaction and an extension reaction. The reaction between the polyester prepolymer having an isocyanate group and the amine compound may be carried out together with the organic solvent removing step described later.
Here, the reaction conditions are selected based on the reactivity between the isocyanate group structure of the polyester prepolymer and the amine compound. As an example, the reaction time is preferably 10 minutes or more and 40 hours or less, and preferably 2 hours or more and 24 hours or less. The reaction temperature is preferably 0 ° C. or higher and 150 ° C. or lower, and preferably 40 ° C. or higher and 98 ° C. or lower. If necessary, a known catalyst (dibutyltin laurate, dioctyltin laurate, etc.) may be used to produce the urea-modified polyester resin. That is, the catalyst may be added to the oil phase liquid or suspension.

Examples of the aqueous phase liquid include an aqueous phase liquid in which a particle dispersant such as an organic particle dispersant and an inorganic particle dispersant is dispersed in an aqueous solvent. Further, as the aqueous phase liquid, an aqueous phase liquid in which a particle dispersant is dispersed in an aqueous solvent and a polymer dispersant is dissolved in an aqueous solvent can also be mentioned. A well-known additive such as a surfactant may be added to the aqueous phase liquid.

Examples of the aqueous solvent include water (usually ion-exchanged water, distilled water, pure water). The aqueous solvent is a solvent containing water and an organic solvent such as alcohol (methanol, isopropyl alcohol, ethylene glycol, etc.), dimethylformamide, tetrahydrofuran, cellsolves (methylcellsolve, etc.), lower ketones (acetone, methylethylketone, etc.). There may be.

Examples of the organic particle dispersant include hydrophilic organic particle dispersants. Examples of the organic particle dispersant include particles such as poly (meth) acrylic acid alkyl ester resin (for example, polymethyl methacrylate resin), polystyrene resin, and poly (styrene-acrylonitrile) resin. Examples of the organic particle dispersant include particles of styrene acrylic resin.

Examples of the inorganic particle dispersant include a hydrophilic inorganic particle dispersant. Specific examples of the inorganic particle dispersant include particles such as silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate, clay, diatomaceous earth, and bentonite, and calcium carbonate particles are preferable. As the inorganic particle dispersant, one type may be used alone, or two or more types may be used in combination.

The surface of the particle dispersant may be surface-treated with a polymer having a carboxyl group.
As the polymer having a carboxyl group, the carboxyl group of α, β-monoethylene unsaturated carboxylic acid or α, β-monoethylene unsaturated carboxylic acid is made of alkali metal, alkaline earth metal, ammonium, amine or the like. Examples include a copolymer of at least one selected from neutralized salts (alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts, etc.) and α, β-monoethylene unsaturated carboxylic acid esters. Be done. As the polymer having a carboxyl group, the carboxyl group of the copolymer of α, β-monoethylene unsaturated carboxylic acid and α, β-monoethylene unsaturated carboxylic acid ester is an alkali metal or an alkaline earth metal. , Alkali metal salts, alkaline earth metal salts, ammonium salts, amine salts, etc., which are neutralized with ammonium, amines and the like. As the polymer having a carboxyl group, one type may be used alone, or two or more types may be used in combination.

Typical examples of α, β-monoethylene unsaturated carboxylic acid are α, β-unsaturated monocarboxylic acid (acrylic acid, methacrylic acid, crotonic acid, etc.) and α, β-unsaturated dicarboxylic acid (maleic acid). Acid, fumaric acid, itaconic acid, etc.) and the like. Typical examples of α, β-monoethyl unsaturated carboxylic acid esters include alkyl esters of (meth) acrylic acid, (meth) acrylates having an alkoxy group, and (meth) acrylates having a cyclohexyl group. Examples thereof include (meth) acrylate having a hydroxy group and polyalkylene glycol mono (meth) acrylate.

Examples of the polymer dispersant include hydrophilic polymer dispersants. Specific examples of the polymer dispersant include water-soluble polymer dispersants (for example, carboxymethyl cellulose, carboxyethyl cellulose, etc.) having a carboxyl group and no parent oil group (hydroxypropoxy group, methoxy group, etc.). Sexual cellulose ether).

-Solvent removal process-
Next, the organic solvent is removed from the obtained suspension to obtain a toner particle dispersion (solvent removal step). This solvent removing step is a step of removing the organic solvent contained in the droplets of the aqueous phase liquid dispersed in the suspension to generate toner particles. The removal of the organic solvent from the suspension may be carried out immediately after the suspension preparation step, or may be carried out one minute or more after the completion of the suspension preparation step.
In the solvent removing step, it is preferable to remove the organic solvent from the suspension by cooling or heating the obtained suspension to, for example, 0 ° C. or higher and 100 ° C. or lower.

Specific methods for removing the organic solvent include the following methods.
(1) A method of forcibly updating the gas phase on the suspension surface by blowing an air flow on the suspension. In this case, gas may be blown into the suspension.
(2) A method of reducing the pressure. In this case, the gas phase on the suspension surface may be forcibly updated by filling with gas, or gas may be blown into the suspension.

Toner particles are obtained through the above steps.
Here, after the solvent removal step is completed, the toner particles formed in the toner particle dispersion liquid are subjected to a known washing step, solid-liquid separation step, and drying step to obtain toner particles in a dried state.
In the cleaning step, it is preferable to sufficiently perform replacement cleaning with ion-exchanged water from the viewpoint of chargeability.
The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, or the like may be performed from the viewpoint of productivity. The drying step is also not particularly limited, but from the viewpoint of productivity, freeze-drying, air-flow drying, fluid drying, vibration-type fluid drying and the like may be performed.

Then, the toner according to the present embodiment is produced, for example, by adding an external additive to the obtained dry toner particles and mixing them. The mixing may be carried out by, for example, a V blender, a Henschel mixer, a Ladyge mixer or the like. Further, if necessary, coarse particles of toner may be removed by using a vibration sieving machine, a wind sieving machine or the like.

<Static charge image developer>
The electrostatic charge image developer according to the present embodiment contains at least the toner according to the present embodiment.
The electrostatic charge image developer according to the present embodiment may be a one-component developer containing only the toner according to the present embodiment, or a two-component developer mixed with the toner and a carrier.

The carrier is not particularly limited, and examples thereof include known carriers. As the carrier, for example, a coating carrier in which the surface of a core material made of magnetic powder is coated with a coating resin; a magnetic powder dispersion type carrier in which magnetic powder is dispersed and blended in a matrix resin; a porous magnetic powder is impregnated with resin. Resin impregnated carrier; etc.
The magnetic powder dispersion type carrier and the resin impregnated type carrier may be carriers in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

Examples of the magnetic powder include magnetic metals such as iron, nickel and cobalt, and magnetic oxides such as ferrite and magnetite.

Examples of the coating resin and matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, and styrene-acrylic acid ester. Examples thereof include a copolymer, a straight silicone resin containing an organosiloxane bond or a modified product thereof, a fluororesin, a polyester, a polypropylene, a phenol resin, an epoxy resin and the like.
The coating resin and the matrix resin may contain other additives such as conductive particles.
Examples of the conductive particles include metals such as gold, silver and copper, and particles such as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate and potassium titanate.

Here, in order to coat the surface of the core material with the coating resin, a method of coating with a coating resin and, if necessary, a coating layer forming solution in which various additives are dissolved in an appropriate solvent can be mentioned. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, coating suitability, and the like.
Specific resin coating methods include a dipping method in which the core material is immersed in a coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the core material surface, and a state in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a solution for forming a coating layer is sprayed, a kneader coater method in which a core material of a carrier and a solution for forming a coating layer are mixed in a kneader coater, and a solvent is removed.

The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner: carrier = 1: 100 to 30: 100, and more preferably 3: 100 to 20: 100.

<Image forming device / Image forming method>
The image forming apparatus / image forming method according to the present embodiment will be described.
The image forming apparatus according to the present embodiment includes an image holder, a charging means for charging the surface of the image holder, a static charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and an electrostatic charge. A developing means that accommodates an image developer and develops an electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic image developer, and a recording medium that records the toner image formed on the surface of the image holder. It is provided with a transfer means for transferring to the surface of the image holder, a cleaning means having a cleaning blade for cleaning the surface of the image holder, and a fixing means for fixing the toner image transferred to the surface of the recording medium. Then, as the electrostatic charge image developer, the electrostatic charge image developer according to the present embodiment is applied.

In the image forming apparatus according to the present embodiment, a charging step of charging the surface of the image holder, a static charge image forming step of forming an electrostatic charge image on the surface of the charged image holder, and an electrostatic charge according to the present embodiment. A development step of developing an electrostatic charge image formed on the surface of an image holder as a toner image with an image developer, and a transfer step of transferring a toner image formed on the surface of the image holder to the surface of a recording medium. An image forming method (image forming method according to the present embodiment) having a cleaning step of cleaning the surface of the image holder with a cleaning blade and a fixing step of fixing the toner image transferred to the surface of the recording medium is carried out. To.

The image forming apparatus according to the present embodiment is a direct transfer type apparatus that directly transfers the toner image formed on the surface of the image holder to the recording medium; the toner image formed on the surface of the image holder is transferred to the intermediate transfer body. An intermediate transfer type device that first transfers the toner image to the surface and then secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium; after the toner image is transferred, static elimination light is applied to the surface of the image holder before charging. A well-known image forming apparatus such as an apparatus provided with a static elimination means for irradiating and eliminating static electricity is applied.
In the case of an intermediate transfer type apparatus, the transfer means is, for example, an intermediate transfer body in which a toner image is transferred to the surface and a primary transfer in which a toner image formed on the surface of an image holder is primarily transferred to the surface of the intermediate transfer body. A configuration comprising means and secondary transfer means for secondary transfer of the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium is applied.

In the image forming apparatus according to the present embodiment, for example, the portion including the developing means may have a cartridge structure (process cartridge) that is attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge including a developing means containing the electrostatic charge image developer according to the present embodiment is preferably used.

Hereinafter, an example of the image forming apparatus according to the present embodiment will be shown, but the present invention is not limited thereto. The main parts shown in the figure will be described, and the other parts will be omitted.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to the present embodiment.
The image forming apparatus shown in FIG. 1 is an electrophotographic first to output an image of each color of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. A fourth image forming unit 10Y, 10M, 10C, 10K (image forming means) is provided. These image forming units (hereinafter, may be simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged side by side at a predetermined distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are attached to and detached from the image forming apparatus.

An intermediate transfer belt 20 as an intermediate transfer body extends through each unit above the drawings of each unit 10Y, 10M, 10C, and 10K. The intermediate transfer belt 20 is provided by being wound around a drive roll 22 arranged apart from each other from the left to the right in the figure and a support roll 24 in contact with the inner surface of the intermediate transfer belt 20, and the first unit 10Y to the fourth It is designed to run in the direction toward the unit 10K. A force is applied to the support roll 24 in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the support roll 24. Further, an intermediate transfer body cleaning device 30 is provided on the side surface of the image holder of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, the developing devices (development means) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K each have yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. Toner containing the four colors of toner is supplied.

Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, here, the first unit forming a yellow image arranged on the upstream side in the traveling direction of the intermediate transfer belt. 10Y will be described as a representative. The second to fourth units are provided with reference numerals having magenta (M), cyan (C), and black (K) instead of yellow (Y) in the portion equivalent to the first unit 10Y. The description of the units 10M, 10C, and 10K of the above is omitted.

The first unit 10Y has a photoconductor 1Y that acts as an image holder. Around the photoconductor 1Y, a charging roll (an example of charging means) 2Y that charges the surface of the photoconductor 1Y to a predetermined potential, and a laser beam 3Y based on a color-separated image signal expose the charged surface. An exposure device (an example of a static charge image forming means) 3 for forming an electrostatic charge image, and a developing device (an example of a developing means) 4Y for developing a static charge image by supplying a charged toner to the static charge image. A primary transfer roll 5Y (an example of a primary transfer means) that transfers a toner image onto an intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer. Are arranged in order.
The primary transfer roll 5Y is arranged inside the intermediate transfer belt 20 and is provided at a position facing the photoconductor 1Y. Further, a bias power supply (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply changes the transfer bias applied to each primary transfer roll by control by a control unit (not shown).

Hereinafter, the operation of forming a yellow image in the first unit 10Y will be described.
First, prior to the operation, the surface of the photoconductor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y.
The photoconductor 1Y is formed by laminating a photosensitive layer on a conductive substrate (for example, volume resistivity at 20 ° C.: 1 × 10 ^-6 Ωcm or less). This photosensitive layer usually has a high resistivity (resistance of a general resin), but has a property that when the laser beam 3Y is irradiated, the specific resistance of the portion irradiated with the laser beam changes. Therefore, the laser beam 3Y is output to the surface of the charged photoconductor 1Y via the exposure apparatus 3 according to the image data for yellow sent from the control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoconductor 1Y, whereby an electrostatic charge image of a yellow image pattern is formed on the surface of the photoconductor 1Y.

The static charge image is an image formed on the surface of the photoconductor 1Y by charging. The laser beam 3Y reduces the specific resistance of the irradiated portion of the photosensitizer layer, and the charged charge on the surface of the photoconductor 1Y flows. On the other hand, it is a so-called negative latent image formed by the residual charge of the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoconductor 1Y is rotated to a predetermined development position as the photoconductor 1Y travels. Then, at this developing position, the electrostatic charge image on the photoconductor 1Y is converted into a visible image (developed image) as a toner image by the developing device 4Y.

In the developing apparatus 4Y, for example, a static charge image developing agent containing at least yellow toner and a carrier is housed. The yellow toner is triboelectrically charged by being agitated inside the developing apparatus 4Y, and has a charge having the same polarity (negative electrode property) as the charged charge on the photoconductor 1Y, and is a developer roll (developing agent holder). Example) It is held on. Then, as the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner is electrostatically adhered to the statically eliminated latent image portion on the surface of the photoconductor 1Y, and the latent image is developed by the yellow toner. .. The photoconductor 1Y on which the yellow toner image is formed is continuously traveled at a predetermined speed, and the toner image developed on the photoconductor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoconductor 1Y is transferred to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoconductor 1Y toward the primary transfer roll 5Y is applied to the toner image to act on the photoconductor. The toner image on 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (−) of the toner, and is controlled to +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the photoconductor 1Y is removed by the photoconductor cleaning device 6Y and recovered.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
In this way, the intermediate transfer belt 20 to which the yellow toner image is transferred in the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and multiplex transferred. Toner.

The intermediate transfer belt 20 on which four color toner images are multiplex-transferred through the first to fourth units is arranged on the image holding surface side of the intermediate transfer belt 20, the support roll 24 in contact with the inner surface of the intermediate transfer belt, and the intermediate transfer belt 20. It leads to a secondary transfer unit composed of the secondary transfer roll (an example of the secondary transfer means) 26. On the other hand, the recording paper (an example of the recording medium) P is fed to the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact with each other via the supply mechanism at a predetermined timing, and the secondary transfer bias is supported by the support roll. It is applied to 24. The transfer bias applied at this time has a (-) polarity that is the same as the polarity (-) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, and the transfer bias is applied on the intermediate transfer belt 20. The toner image of is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by the resistance detecting means (not shown) for detecting the resistance of the secondary transfer unit, and is voltage controlled.

After that, the recording paper P is sent to the pressure contact portion (nip portion) of the pair of fixing rolls in the fixing device (an example of the fixing means) 28, and the toner image is fixed on the recording paper P to form the fixing image.

Examples of the recording paper P for transferring the toner image include plain paper used in electrophotographic copiers, printers, and the like. Examples of the recording medium include an OHP sheet and the like in addition to the recording paper P.
In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is also preferably smooth, and for example, coated paper in which the surface of plain paper is coated with resin or the like, art paper for printing, or the like is preferably used. Will be done.

The recording paper P for which the color image has been fixed is carried out toward the ejection unit, and a series of color image forming operations is completed.

<Process cartridge / toner cartridge>
The process cartridge according to this embodiment will be described.
The process cartridge according to the present embodiment contains the electrostatic charge image developer according to the present embodiment, and is a developing means for developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic charge image developer. It is a process cartridge that is attached to and detached from the image forming apparatus.

The process cartridge according to the present embodiment is not limited to the above configuration, and includes a developing device and other means such as an image holder, a charging means, an electrostatic charge image forming means, and a transfer means, if necessary. It may be configured to include at least one selected from.

Hereinafter, an example of the process cartridge according to the present embodiment will be shown, but the present invention is not limited to this. The main parts shown in the figure will be described, and the other parts will be omitted.

FIG. 2 is a schematic configuration diagram showing a process cartridge according to the present embodiment.
The process cartridge 200 shown in FIG. 2 is provided around the photoconductor 107 (an example of an image holder) and the photoconductor 107 by, for example, a housing 117 provided with a mounting rail 116 and an opening 118 for exposure. The charged roll 108 (an example of the charging means), the developing device 111 (an example of the developing means), and the photoconductor cleaning device 113 (an example of the cleaning means) having the cleaning blade 113-1 are integrally combined and held. It is configured and made into a cartridge.
In FIG. 2, 109 is an exposure device (an example of an electrostatic charge image forming means), 112 is a transfer device (an example of a transfer means), 115 is a fixing device (an example of a fixing means), and 300 is a recording paper (an example of a recording medium). An example) is shown.

Next, the toner cartridge according to this embodiment will be described.
The toner cartridge according to the present embodiment is a toner cartridge that houses the toner according to the present embodiment and is attached to and detached from the image forming apparatus. The toner cartridge accommodates a replenishing toner for supplying to the developing means provided in the image forming apparatus.

The image forming apparatus shown in FIG. 1 is an image forming apparatus having a structure in which the toner cartridges 8Y, 8M, 8C, and 8K are attached and detached, and the developing apparatus 4Y, 4M, 4C, and 4K are each developing apparatus (color). ) Is connected to a toner cartridge (not shown). Further, when the amount of toner contained in the toner cartridge is low, the toner cartridge is replaced.

Hereinafter, the present embodiment will be described in more detail with reference to Examples and Comparative Examples, but the present embodiment is not limited to these Examples. In addition, "part" and "%" are based on mass unless otherwise specified.

[Manufacturing method of toner particles]
(Preparation of toner particles (A))
-Preparation of polyester resin particle dispersion (1A)-
・ Ethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd.): 37 parts ・ Neopentyl glycol (manufactured by Wako Pure Chemical Industries, Ltd.): 65 parts ・ 1,9 nonanediol (manufactured by Wako Pure Chemical Industries, Ltd.): 32 parts ・ Terephthalic acid (manufactured by Wako Pure Chemical Industries, Ltd.) Wako Pure Chemical Industries, Ltd.): 96 parts The above monomer was placed in a flask, the temperature was raised to 200 ° C over 1 hour, and after confirming that the inside of the reaction system was agitated, 1.2 parts of dibutyltin oxide was added. I put it in. Further, the temperature was raised from the same temperature to 240 ° C. over 6 hours while distilling off the generated water, and the dehydration condensation reaction was continued at 240 ° C. for another 4 hours, the acid value was 9.4 mgKOH / g, and the weight average molecular weight was increased. A polyester resin (1A) having a glass transition temperature of 13,000 and a glass transition temperature of 62 ° C. was obtained.

Next, the polyester resin (1A) was transferred to Cavitron CD1010 (manufactured by Eurotech) in a molten state at a rate of 100 parts per minute. In a separately prepared aqueous medium tank, 0.37% concentration of dilute ammonia water obtained by diluting reagent ammonia water with ion-exchanged water was placed, and the polyester was heated to 120 ° C. in a heat exchanger at a rate of 0.1 liter per minute. It was transferred to the above-mentioned Cavitron together with the resin melt. The Cavitron was operated under the conditions that the rotation speed of the rotor was 60 Hz and the pressure was 5 kg / cm ² .
A polyester resin particle dispersion (1A) was obtained in which resin particles having a volume average particle diameter of 160 nm, a solid content of 30%, a glass transition temperature of 62 ° C., and a weight average molecular weight of Mw of 13,000 were dispersed.

-Preparation of colorant particle dispersion (1A)-
・ Cyan pigment (copper phthalocyanine, CI Pigment volume 15: 3, manufactured by Dainichi Seika Co., Ltd.): 10 parts ・ Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts ・ Ion-exchanged water: 80 parts The above components are mixed and dispersed for 1 hour with a high-pressure impact disperser Ultimateizer (HJP30006, manufactured by Sugino Machine Limited) to prepare a colorant particle dispersion (1A) having a volume average particle size of 180 nm and a solid content of 20%. Obtained.

-Preparation of release agent particle dispersion (1A)-
-Carnauba wax (RC-160, melting temperature 84 ° C, manufactured by Toa Kasei Co., Ltd.): 50 parts by mass-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts by mass-Ion-exchanged water: 200 mass Part The above components are heated to 120 ° C., dispersed with Ultratarax T50 manufactured by IKA, and then dispersed with a pressure discharge type Goulin homogenizer. A release agent particle dispersion having a volume average particle size of 200 nm and a solid content of 20%. (1A) was obtained.

-Preparation of toner particles-
-Polyester resin particle dispersion (1A): 200 parts-Colorant particle dispersion (1A): 25 parts-Removing agent particle dispersion (1A): 30 parts-Polyaluminum chloride: 0.4 parts-Ion exchange water : 100 parts The above components were put into a stainless steel flask, mixed and dispersed using Ultratarax manufactured by IKA, and then heated to 48 ° C. while stirring the flask in a heating oil bath. After holding at 48 ° C. for 30 minutes, 70 parts of the polyester resin particle dispersion liquid (1A) was added thereto.

Then, after adjusting the pH in the system to 8.0 using an aqueous sodium hydroxide solution having a concentration of 0.5 mol / L, the stainless flask was sealed, the stirring shaft was magnetically sealed, and stirring was continued. It was heated to 90 ° C. and held for 3 hours. After completion of the reaction, the temperature was lowered at 2 ° C./min, filtered, washed with ion-exchanged water, and then solid-liquid separation was performed by Nucci-type suction filtration. This was further redispersed with 3 L of ion-exchanged water at 30 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was repeated 6 more times, and when the pH of the filtrate became 7.54 and the electric conductivity became 6.5 μS / cm, the No. 1 was obtained by suction filtration using the Nutche type. Solid-liquid separation was performed using 5A filter paper. Then, vacuum drying was continued for 12 hours to obtain toner particles (A).
The volume average particle size D50v of the toner particles (A) was 5.8 μm.

(Preparation of toner particles B)
-Preparation of unmodified polyester resin (1)-
-Terephthalic acid: 1243 parts-Bisphenol A ethylene oxide adduct: 1830 parts-Bisphenol A propylene oxide adduct: 840 parts After heating and mixing the above components at 180 ° C, add 3 parts of dibutyltin oxide and heat at 220 ° C. While distilling off water, a polyester resin was obtained. 1500 parts of cyclohexanone was added to the obtained polyester to dissolve the polyester resin, 250 parts of acetic anhydride was added to the cyclohexanone solution, and the mixture was heated at 130 ° C. Further, this solution was heated under reduced pressure to remove the solvent and unreacted acid to obtain an unmodified polyester resin (1).

-Preparation of polyester prepolymer (1)-
-Terephthalic acid: 1243 parts-Bisphenol A ethylene oxide adduct: 1830 parts-Bisphenol A propylene oxide adduct: 840 parts After heating and mixing the above components at 180 ° C, add 3 parts of dibutyltin oxide and heat at 220 ° C. While distilling off water, a polyester prepolymer was obtained. 350 parts of the obtained polyester prepolymer, 50 parts of tolylene diisocyanate, and 450 parts of ethyl acetate are placed in a container, and the mixture is heated at 130 ° C. for 3 hours to obtain a polyester prepolymer having an isocyanate group (isocyanate-modified polyester prepolymer (isocyanate-modified polyester prepolymer). 1)) was obtained.

(Preparation of ketimine compound (1))
50 parts of methyl ethyl ketone and 150 parts of hexamethylenediamine were placed in a container and stirred at 60 ° C. to obtain ketimine compound (1).

(Preparation of colorant particle dispersion liquid (1B))
-Cyan pigment (copper phthalocyanine, CI Pigment blue 15: 3, manufactured by Dainichi Seika Co., Ltd.): 100 parts-Ethyl acetate: 500 parts Mix the above components, filter the mixture and further mix with 500 parts of ethyl acetate. After repeating the operation 5 times, it was dispersed for about 1 hour using an emulsification disperser Cavitron (CR1010, manufactured by Pacific Kiko Co., Ltd.), and a colorant particle dispersion (1B) in which cyan pigment was dispersed (solid content concentration: 10%) ) Was obtained.

(Preparation of release agent particle dispersion liquid (1B))
-Paraffin wax (melting temperature 89 ° C.): 30 parts-Ethyl acetate: 270 parts Wet pulverization with a microbead type disperser (DCP mill) with the above components cooled to 10 ° C. 1B) was obtained.

(Preparation of oil phase liquid (1))
-Unmodified polyester resin (1): 136 parts-Colorant particle dispersion (1B): 330 parts-Ethyl acetate: 56 parts After stirring and mixing the above components, the release agent particle dispersion (1B) was added to the obtained mixture. 400 parts were added and stirred to obtain an oil phase liquid (1).

(Preparation of styrene acrylic resin particle dispersion (1B))
・ Styrene: 370 parts ・ n Butyl acrylate: 30 parts ・ Acrylic acid: 4 parts ・ Dodecanethiol: 24 parts ・ Carbon tetrabromide: 4 parts Mix the above components and dissolve the mixture as a nonionic surfactant ( After dispersing and emulsifying in an aqueous solution in which 6 parts of Nonipol 400 (manufactured by Sanyo Kasei Kogyo Co., Ltd.) and 10 parts of anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) are dissolved in 560 parts of ion-exchanged water. While mixing for 10 minutes, an aqueous solution prepared by dissolving 4 parts of ammonium persulfate in 50 parts of ion-exchanged water was added thereto, and after nitrogen substitution, the inside of the flask was stirred and oil was used until the contents reached 70 ° C. The mixture was heated in a bath and the emulsion polymerization was continued for 5 hours. In this way, a styrene acrylic resin particle dispersion liquid (1B) (resin particle concentration: 40% by mass) obtained by dispersing resin particles having an average particle size of 180 nm and a weight average molecular weight (Mw) of 15,500 was obtained. In addition, it should be noted

(Preparation of aqueous phase liquid (1))
・ Styrene acrylic resin particle dispersion (1B): 100 parts ・ 2% aqueous solution of cellogen BS-H (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.): 200 parts ・ Ion-exchanged water: 200 parts Stirring and mixing the above components, aqueous phase liquid (1) was obtained.

[Preparation of toner particles]
・ Oil phase liquid (1): 300 parts ・ Isocyanate-modified polyester prepolymer (1): 25 parts ・ Ketimine compound (1): 0.5 parts Put the above ingredients in a container and homogenizer (Ultra Tarax, manufactured by IKA). After stirring for 2 minutes to obtain an oil phase solution (1P), 500 parts of the aqueous phase solution (1) was added to the container, and the mixture was stirred with a homogenizer for 20 minutes. Next, the mixed solution is stirred with a propeller-type stirrer at room temperature (25 ° C.) and normal pressure (1 atm) for 48 hours to react the isocyanate-modified polyester prepolymer (1) with the ketimine compound (1), and urea. A modified polyester resin was produced, and the organic solvent was removed to form granules. Next, the granules were washed with water, dried and classified to obtain toner particles (B).

(Creation of toner particles C)
-Preparation of styrene acrylic resin particle dispersion (1C)-
-Styline: 320 parts by mass-n-Butyl acrylate: 80 parts by mass-Acrylic acid: 12 parts by mass-10-dodecanethiol: 2 parts by mass or more of components are mixed and dissolved to form a nonionic surfactant ( Nonipol 400, manufactured by Sanyo Kasei Kogyo Co., Ltd.) 6 parts by mass and anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were dissolved in 550 parts by mass of ion-exchanged water and emulsified and dispersed in a flask. While slowly mixing for 10 minutes, 50 parts by mass of ion-exchanged water in which 4 parts by mass of ammonium persulfate was dissolved was added thereto. After nitrogen substitution, the inside of the flask was heated with an oil bath until the content reached 70 ° C. while stirring, and emulsion polymerization was continued for 5 hours. As a result, a styrene acrylic resin particle dispersion (1C) having a volume average particle diameter D50v = 210 nm, a glass transition temperature Tg = 50 ° C., a weight average molecular weight Mw = 38000, and a solid content of 30% by mass was obtained.

-Preparation of colorant particle dispersion (1C)-
・ Cyan pigment (copper phthalocyanine, CI Pigment volume 15: 3, manufactured by Dainichi Seika Co., Ltd.): 10 parts ・ Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts ・ Ion-exchanged water: 80 parts The above components are mixed and dispersed for 1 hour with a high-pressure impact disperser Ultimateizer (HJP30006, manufactured by Sugino Machine Limited) to obtain a colorant particle dispersion (1C) having a volume average particle size of 180 nm and a solid content of 20%. Obtained.

-Preparation of mold release agent particle dispersion (1C)-
-Paraffin wax (melting point 75 ° C: HNP9, manufactured by Nippon Seikan Co., Ltd.): 50 parts by mass-Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 2 parts by mass-Ion-exchanged water: 200 parts by mass The components are heated to 120 ° C., dispersed with Ultratarax T50 manufactured by IKA, and then dispersed with a pressure discharge type paraffin homogenizer to obtain a release agent particle dispersion (1C) having a center diameter of 200 nm and a solid content of 20% by mass. Obtained.

-Preparation of toner particles-
-Stylic acrylic resin particle dispersion (1C): 200 parts by mass-Colorant particle dispersion (1C): 25 parts by mass-Release agent particle dispersion (1C): 30 parts by mass-Polyaluminum chloride: 0.4% by mass Part ・ Ion exchanged water: 100 parts by mass Put the above components into a stainless steel flask, mix and disperse using Ultratarax manufactured by IKA, and then stir the flask in a heating oil bath to 48 ° C. It was heated. After holding at 48 ° C. for 30 minutes, 70 parts of a styrene acrylic resin particle dispersion (1C) was added as an additional resin particle dispersion.

Then, after adjusting the pH in the system to 8.0 using an aqueous sodium hydroxide solution having a concentration of 0.5 mol / L, the stainless flask was sealed, the stirring shaft was magnetically sealed, and stirring was continued. It was heated to 90 ° C. and held for 3 hours. After completion of the reaction, the temperature was lowered at 2 ° C./min, filtered, washed with ion-exchanged water, and then solid-liquid separation was performed by Nucci-type suction filtration. This was further redispersed with 3 L of ion-exchanged water at 30 ° C., and stirred and washed at 300 rpm for 15 minutes. This washing operation was repeated 6 more times, and when the pH of the filtrate became 7.54 and the electric conductivity became 6.5 μS / cm, the No. 1 was obtained by suction filtration using the Nutche type. Solid-liquid separation was performed using 5A filter paper. Then, vacuum drying was continued for 12 hours to obtain toner particles (C).
The volume average particle size D50v of the toner particles was measured with a Coulter counter and found to be 5.8 μm.

[Preparation of silica particles]
(Preparation of silica particles (S1))
-Preparation of silica particle dispersion (1)-
To a 1.5 L glass reaction vessel equipped with a stirrer, a dropping nozzle and a thermometer, 300 parts of methanol and 70 parts of 10% aqueous ammonia were added and mixed to obtain an alkaline catalyst solution. After adjusting this alkaline catalyst solution to 30 ° C., 200 parts of tetramethoxysilane (TMS) and 55 parts of 8.0% ammonia water were added dropwise at the same time with stirring, and a hydrophilic silica particle dispersion (solid content concentration 12) was added. .7%) was obtained. Here, the dropping time was set to 33 minutes. Then, the obtained silica particle dispersion was condensed to a solid content concentration of 40% with a rotary filter R-fine (manufactured by Kotobuki Kogyo Co., Ltd.). This condensed product was used as a silica particle dispersion liquid (1).

-Preparation of silica particles (S1)-
100 parts of hexamethyldisilazane (HMDS) as a hydrophobizing agent is added to 250 parts of the silica particle dispersion (1), reacted at 130 ° C. for 2 hours, cooled, dried by spray drying, and silica. Hydrophobic silica particles (S1) whose surface was hydrophobized were obtained.

(Preparation of silica particles (S2) to (S8))
According to Table 1, the alkaline catalyst solution (methanol amount and 10% aqueous ammonia amount), silica particle formation conditions (total amount of tetramethoxysilane (TMS) and 8% aqueous ammonia added to the alkaline catalyst, and dropping time), and hydrophobicity. Silica particles (S2) to (S8) were produced in the same manner as the silica particles (S1) except that the type and amount of the chemical treatment agent were changed.

In addition, the average circularity and the average circle equivalent diameter of each of the obtained silica particles were measured by the methods described above. The results are shown in Table 1.

(Preparation of silica particles (S9) to (S13))
As silica particles (S9), commercially available fumed silica particles (circle equivalent diameter 100 nm, AEROSIL RX50, manufactured by Nippon Aerosil Co., Ltd.) were prepared. The average circularity of the silica particles was 0.73.
As silica particles (S10), commercially available fumed silica particles (circle equivalent diameter 70 nm, AEROSIL NY50, manufactured by Nippon Aerosil Co., Ltd.) were prepared. The average circularity of the silica particles was 0.78.

As silica particles (S11), commercially available fumed silica particles (circle equivalent diameter 30 nm, AEROSIL RX300, manufactured by Nippon Aerosil Co., Ltd.) were prepared. The average circularity of the silica particles was 0.81.

As silica particles (S12), commercially available fumed silica particles (circle equivalent diameter 50 nm, AEROSIL RX200, manufactured by Nippon Aerosil Co., Ltd.) were prepared. The average circularity of the silica particles was 0.82.

As silica particles (S13), commercially available fumed silica particles (circle equivalent diameter 150 nm, AEROSIL RY51, manufactured by Nippon Aerosil Co., Ltd.) were prepared. The average circularity of the silica particles was 0.76.

In Table 1, "TMS" represents tetramethoxysilane, "HMDS" represents hexamethyldisilazane, and "NH ₃ water" represents ammonia water.

<Example 1>
To 100 parts of the toner particles (A), 1 part of silica particles (S1), 1 part of silica particles (S2), 1 part of silica particles (S13), and 1 part of silica particles (S10) were added as an external additive. The toner of Example 1 was obtained by mixing with a Henschel mixer at a stirring peripheral speed of 30 m / sec for 15 minutes.
In addition, the particle size distribution index of the entire silica particles was also measured. The results are shown in Table 2.
For the particle size distribution index, the equivalent circle diameter is calculated according to the method for measuring the equivalent circle diameter described above, and the 16% diameter (D16) and 84% diameter (D84) in the volume-based cumulative frequency of the obtained equivalent circle diameter are calculated. I asked. The square root obtained by dividing the obtained 84% diameter (D84) by the 16% diameter (D16) was used as the particle size distribution index (= (D84 / D16) 1/2).

<Examples 2 to 16 and Comparative Examples 1 to 9>
Toners of each example were obtained in the same manner as in Example 1 except that the type and number of copies of silica particles were changed according to Table 2 and the types of toner particles were changed according to Tables 3 and 4.
Further, according to the method described above, the width of the circle equivalent diameter of the maximum value, the frequency ratio of the maximum value, the circularity in the portion having each maximum value, and the circularity of the silica particle with respect to the entire silica particle of 0.6 or more 0. Tables 3 and 4 show the results of measuring the ratio of less than 9 and the ratio of circularity of 0.9 or more and 1.0 or less.

The abbreviations in Table 1 are as follows.
-"P1", "P2", "P3", and "P4" are the maximum values of the number frequency in the circle equivalent diameter distribution, respectively, with the smallest diameter side as P1 and the fourth largest diameter in order from the smallest diameter side. The side is represented as P4.
"R1 (ave)", "R2 (ave)", "R3 (ave)", and "R4 (ave)" each represent the average circularity in the portion having the maximum value of each of the above.
-"ΔP12", "ΔP23", and "ΔP34" in the "maximum value width" column represent the widths of adjacent maximum value circle-equivalent diameters, respectively. “ΔP12” is the width of the equivalent circle diameter between the maximum value P1 on the smallest diameter side and the second maximum value P2 from the smallest diameter side, and “ΔP23” is the second maximum value P2 from the smallest diameter side and the third from the smallest diameter side. The width of the circle equivalent diameter with respect to the maximum value P3 of, "ΔP34" represents the width of the circle equivalent diameter of the third maximum value P3 from the small diameter side and the fourth maximum value P4 from the small diameter side.
"P1 / P2", "P2 / P3", and "P3 / P4" in the "maximum value frequency ratio" column represent the ratio (frequency ratio) of the number and frequency of adjacent maximum values, respectively. "P1 / P2" is the frequency ratio of the maximum value P1 on the smallest diameter side and the second maximum value P2 from the small diameter side, and "P2 / P3" is the second maximum value P2 from the small diameter side and the third from the small diameter side. The frequency ratio of the maximum value P3, "P3 / P4", represents the frequency ratio of the third maximum value P3 from the small diameter side and the fourth maximum value P4 from the small diameter side.
-The "Ratio of circularity" column represents the ratio of silica particles having a circularity of 0.6 or more and less than 0.9 and the ratio of silica particles having a circularity of 0.9 or more and 1.0 or less with respect to the entire silica particles.

<Evaluation>
-Preparation of developer-
The toner obtained in each example and the carrier prepared under the following conditions were placed in a V-blender at a ratio of toner: carrier = 8:92 (mass ratio) and stirred for 20 minutes to obtain a developer.

The carrier used was prepared as follows.
-Ferrite particles (volume average particle size: 36 μm) 100 parts-toluene 14 parts-styrene-methylmethacrylate copolymer 2 parts (component ratio: 90/10, Mw = 80000)
-Carbon black (R330: manufactured by Cabot Corporation) 0.2 part First, the above components excluding ferrite particles were stirred with a stirrer for 10 minutes to prepare a dispersed coating liquid, and then this coating liquid and ferrite particles were mixed. A carrier was obtained by placing the particles in a vacuum degassing type kneader, stirring at 60 ° C. for 30 minutes, degassing with reduced pressure while further heating, and drying.

(Image evaluation in a low temperature and low humidity environment)
The developing agents of each example were housed in the developing apparatus of the modified machine of the image forming apparatus "Apeos PortIVC5575 (manufactured by Fuji Xerox Co., Ltd.)". Using the modified machine of this image forming apparatus, after leaving for one day in a low temperature and low humidity environment (10 ° C., 15% RH environment), 15,000 images having an image density of 80% were continuously formed on A4 paper. The occurrence of color streaks was evaluated according to the following criteria. The results are shown in Table 5. The allowable range was up to G3.
-Evaluation criteria-
G1: No color streaks occur.
G2: Color streaks were generated between 12500 and 14999 sheets.
G3: A streak was generated between 10,000 and 12499 sheets.
G4: Color streaks were generated between 5000 sheets and 9999 sheets.
G5: Color streaks occurred between 4999 sheets or less.

(Image evaluation in a high temperature and high humidity environment)
The developing agents of each example were housed in the developing apparatus of the modified machine of the image forming apparatus "Apeos PortIVC5575 (manufactured by Fuji Xerox Co., Ltd.)". Using the modified machine of this image forming apparatus, after leaving for 1 day in a high temperature and high humidity environment (28 ° C., 85% RH environment), 15,000 images having an image density of 1% were continuously formed on A4 paper. The occurrence of color streaks was evaluated according to the following criteria. The results are shown in Table 5. The allowable range was up to G3.
-Evaluation criteria-
G1: No color streaks occur.
G2: Color streaks were generated between 12500 and 14999 sheets.
G3: A streak was generated between 10,000 and 12499 sheets.
G4: Color streaks were generated between 5000 sheets and 9999 sheets.
G5: Color streaks occurred between 4999 sheets or less.

From the above results, it can be seen that the results of the color streaks in this example are better than those in the comparative example when the images are repeatedly formed in a low temperature and low humidity environment.

1Y, 1M, 1C, 1K photoconductor (example of image holder)
2Y, 2M, 2C, 2K charging roll (example of charging means)
3 Exposure device (an example of static charge image forming means)
3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (example of primary transfer means)
6Y, 6M, 6C, 6K Photoreceptor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner Cartridge 10Y, 10M, 10C, 10K Image Forming Unit 20 Intermediate Transfer Belt (Example of Intermediate Transfer)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer member cleaning device 107 Photoreceptor (example of image holder)
108 Charging roll (an example of charging means)
109 Exposure device (an example of static charge image forming means)
111 Developing equipment (an example of developing means)
112 Transfer device (an example of transfer means)
113 Photoreceptor cleaning device (an example of cleaning means)
113-1 Cleaning blade 115 Fixing device (Example of fixing means)
116 Mounting rail 117 Housing 118 Opening for exposure 200 Process cartridge 300 Recording paper (an example of recording medium)
P Recording paper (an example of recording medium)

Claims (11)

Toner particles containing binder resin and
There maximum value of the number frequency in equivalent circle diameter distribution is three or more, the out of three or more local maxima state, and are width 20nm or 50nm or less in circle equivalent diameter of the maximum value adjacent, the three or more An external additive containing silica particles having a maximum circle-equivalent diameter of 50 nm or more and 100 nm or less, which is located on the smallest diameter side of the circle-equivalent diameter distribution .
Toner for static charge image development. The toner for static charge image development according to claim 1, wherein the three or more maximum circle-equivalent diameters are in the range of 3 nm or more and 300 nm or less. The toner for developing an electrostatic charge image according to claim 1 or 2 , wherein the silica particles contain sol-gel silica particles. Any one of claims 1 to 3 , wherein the silica particles include silica particles having an average circularity of 0.6 or more and less than 0.9 and silica particles having an average circularity of 0.9 or more and 1.0 or less. The toner for developing an electrostatic charge image described in 1. The toner for developing an electrostatic charge image according to any one of claims 1 to 4 , wherein the binder resin is a urea-modified polyester resin. The toner for developing an electrostatic charge image according to any one of claims 1 to 4, wherein the binder resin is a styrene (meth) acrylic resin. A static charge image developer containing the toner for static charge image development according to any one of claims 1 to 6 . The toner for developing an electrostatic charge image according to any one of claims 1 to 6 is accommodated.
A toner cartridge that is attached to and detached from the image forming device. A developing means for accommodating the electrostatic charge image developing agent according to claim 7 and developing the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic charge image developing agent is provided.
A process cartridge that is attached to and detached from the image forming device. Image holder and
A charging means for charging the surface of the image holder and
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image holder, and
A developing means that accommodates the electrostatic charge image developer according to claim 7 and develops the electrostatic charge image formed on the surface of the image holder as a toner image by the electrostatic image developer.
A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A cleaning means having a cleaning blade for cleaning the surface of the image holder, and
A fixing means for fixing the toner image transferred to the surface of the recording medium, and
An image forming apparatus comprising. The charging process that charges the surface of the image holder,
A static charge image forming step of forming a static charge image on the surface of the charged image holder, and
A developing step of developing an electrostatic charge image formed on the surface of the image holder as a toner image by using the electrostatic charge image developer according to claim 7 .
A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, and
A cleaning step of cleaning the surface of the image holder with a cleaning blade,
A fixing step of fixing the toner image transferred to the surface of the recording medium, and
An image forming method having.