JP2016050961A - Toner for electrostatic charge image development, electrostatic charge image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development that suppresses streak-like image defects.SOLUTION: There is provided a toner for electrostatic charge image development has toner particles including an amorphous resin and a crystalline polyester resin, and an external additive including silica particles, where the rate of change of the amount of the free silica particles after heating to the amount of the free silica particles before heating is 20% or more and 60% or less.SELECTED DRAWING: None

Description

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

  A method for visualizing image information through an electrostatic charge image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic charge image formed on a photoreceptor by a charging process and an electrostatic charge image forming process is developed with a developer containing toner, and visualized through a transfer process and a fixing process.

  For example, Patent Document 1 discloses that “at least toner particles and inorganic fine particles as external additives are contained, (a) the average circularity of the toner particles is 0.94 or more, and (b) a photoreceptor. There has been proposed an electrostatic latent image developing toner characterized in that the number release ratio of the inorganic fine particles to the toner particles is a value in the range of 20 to 60%.

  Patent Document 2 states that “a binder resin including a crystalline resin and a colorant are included, the content of the crystalline resin is in the range of 3 to 15% by mass, and the acid value of the toner is 10 to 30 mg KOH / g. A, and the presence ratio of sulfur element in the total existing element intensity by XPS (X-ray photoelectron spectroscopy) is A, and the total existing element intensity by XRF (fluorescence X-ray analysis) after treatment with an alcohol-based solvent There has been proposed a toner for developing an electrostatic image, wherein A / B is in the range of 0.01 to 0.3 when the sulfur element content is B.

  Patent Document 3 discloses that “a small particle size external additive having a number average particle size of 7 to 20 nm, a large particle size external additive having a number average particle size of 40 to 80 nm, and a volume average particle size of 4 to 4”. A toner containing 7 μm toner particles, wherein the external additive having a large particle size adheres to the surface of the toner particles in a semi-embedded state, and the liberation rate from the surface of the toner particles of less than 0.1 wt%. Toners characterized by having “a” are proposed.

JP 2006-337598 A JP 2008-233175 A JP 2009-36980 A

  An object of the present invention is to provide an electrostatic image developing toner that suppresses streak-like image defects.

The above problem is solved by the following means. That is,
The invention according to claim 1
Toner particles containing amorphous resin and crystalline polyester resin, and external additive containing silica particles,
The toner for developing an electrostatic charge image, wherein a change rate of the liberated amount of the silica particles after heating with respect to the liberated amount of the silica particles before heating is 20% or more and 60% or less.

The invention according to claim 2
The toner for developing an electrostatic charge image according to claim 1, wherein the number average particle diameter of the silica particles is from 80 nm to 500 nm.

The invention according to claim 3
The crystalline polyester resin is a polyester resin obtained by polycondensing at least a carboxylic acid component and an alcohol component containing an aliphatic polyhydric alcohol having 4 to 8 carbon atoms. The electrostatic charge image developing toner described.

The invention according to claim 4
An electrostatic charge image developer comprising the electrostatic charge image developing toner according to claim 1.

The invention according to claim 5
Containing the toner for developing an electrostatic charge image according to any one of claims 1 to 3,
The toner cartridge is detachable from the image forming apparatus.

The invention according to claim 6
A developing means for containing the electrostatic charge image developer according to claim 4 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer,
It is a process cartridge that can be attached to and detached from the image forming apparatus.

The invention according to claim 7 provides:
An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Development means for containing the electrostatic charge image developer according to claim 4 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Cleaning means having a cleaning blade for cleaning the surface of the image carrier;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus.

The invention according to claim 8 provides:
A charging step for charging the surface of the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 4;
A transfer step of transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
A cleaning step of cleaning the surface of the image carrier with a cleaning blade;
A fixing step of fixing the toner image transferred to the surface of the recording medium;
Is an image forming method.

  According to the first, second, or third aspect of the invention, streak-like image defects are suppressed as compared with the case where the change rate of the free amount of silica particles after heating with respect to the free amount of silica particles before heating exceeds 60%. An electrostatic charge image developing toner is provided.

  According to the invention of claim 4, 5, 6, 7 or 8, the toner for developing an electrostatic charge image in which the change rate of the liberated amount of silica particles after heating with respect to the liberated amount of silica particles before heating exceeds 60%. An electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method in which streak-like image defects are suppressed as compared with the case of application is provided.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows an example of the process cartridge which concerns on this embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

<Toner for electrostatic image development>
The toner for developing an electrostatic image according to the exemplary embodiment (hereinafter sometimes referred to as “toner”) includes toner particles including an amorphous resin and a crystalline polyester resin, and an external additive including silica particles. Have. And the rate of change of the liberation amount of the silica particles after heating with respect to the liberation amount of the silica particles before heating is 20% or more and 60% or less.

Here, in the toner used in the image forming apparatus, the adhesion of the silica particles to the surface of the toner particles is increased after heat storage (for example, temperature 45 ° C., humidity 50% RH, after storage for 1 day or more). The amount of liberation may decrease. When the amount of liberated silica particles decreases, the amount of silica particles supplied as an external additive to the contact portion (cleaning portion) between the image carrier (also referred to as “photosensitive member”) and the cleaning blade decreases, and the photosensitive member. The cleaning property of the is likely to deteriorate. As a result, a streak-like image defect is likely to be caused.
In particular, when a crystalline polyester resin is used as the binder resin, the crystalline polyester resin is easily exposed from the surface of the toner particles due to thermal storage of the toner, and the adhesion of the silica particles to the surface of the toner particles is further increased. This makes it difficult for the silica particles to be liberated, and the amount of silica particles supplied as an external additive to the cleaning unit is more likely to be reduced. As a result, the streak-like image defect is more likely to be caused.

  On the other hand, the toner according to the exemplary embodiment has a structure that does not greatly reduce the liberated amount of the external additive silica particles after heating (after storage for 17 hours under the conditions of a temperature of 45 ° C. and a humidity of 50% RH). That is, a structure having a small composition change on the toner particle surface is employed. Specifically, the change rate of the free amount of silica particles after heating relative to the free amount of silica particles before heating (hereinafter sometimes simply referred to as “change rate of free amount of silica particles after heating”). 20% or more and 60% or less. Thereby, the cleaning property of the photosensitive member is improved and the streak-like image defect is suppressed.

Although this reason is not certain, it is thought to be due to the following reasons.
If the amount of silica particles liberated due to thermal storage of the toner decreases and fluctuates too much, the silica particles required for cleaning the photoreceptor are less likely to be supplied to the cleaning section, and the cleaning performance of the photoreceptor is likely to deteriorate. .
Therefore, in the toner according to the present embodiment, the change rate of the free amount of the silica particles after heating is set in the above range, so that the fluctuation of the free amount of the silica particles before and after the heating is reduced, and the silica particles to the cleaning unit are changed. Secure supply. As a result, the silica particles are easily supplied to the cleaning section even after heat storage, and the cleaning property of the photoreceptor is improved.
From the above, in the toner according to the present exemplary embodiment, streak-like image defects are suppressed even after heat storage. Further, since the fluctuation of the free amount of the silica particles before and after heating is reduced, the fluidity of the toner is ensured even after heat storage, and the fluctuation of the image density is easily suppressed.

  Hereinafter, details of the toner according to the exemplary embodiment will be described.

  The toner according to the exemplary embodiment includes toner particles and an external additive including silica particles.

(Toner particles)
The toner particles include an amorphous resin and a crystalline polyester resin as a binder resin, and, if necessary, a colorant, a release agent, and other additives.

-Binder resin-
The binder resin includes an amorphous resin and a crystalline polyester resin.
The “crystallinity” of the resin means that it has a clear endothermic peak in differential scanning calorimetry (DSC) rather than a stepwise endothermic amount change. Specifically, the temperature rise rate is 10 (° C. / Min) indicates that the half-value width of the endothermic peak is 10 ° C. or less.
On the other hand, “amorphous” of the resin means that the half width exceeds 10 ° C., shows a stepwise endothermic change, or does not show a clear endothermic peak.

First, the amorphous resin will be described.
Examples of the amorphous resin include known amorphous resins such as polyurethane resin, polyester resin, styrene acrylic resin, epoxy resin, polyamide resin, cellulose resin, polyether resin, polyolefin resin, polystyrene, and styrene butadiene resin. . These amorphous resins may be modified with urethane, urea, or epoxy. Among these, amorphous polyester resins are particularly preferably used from the viewpoint of maintaining elasticity. In addition, an amorphous resin may be used individually by 1 type, and may use 2 or more types together.

  As an amorphous polyester resin, the condensation polymer of polyhydric carboxylic acid and polyhydric alcohol is mentioned, for example. In addition, as an amorphous polyester resin, a commercial item may be used and what was synthesize | combined may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (eg, 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 acids (for example, cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (for example, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or lower (for example, having 1 or more carbon atoms) 5 or less) alkyl esters. Among these, as polyvalent carboxylic acid, aromatic dicarboxylic acid is preferable, for example.
The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid or a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, having 1 to 5 carbon atoms) alkyl esters.
Polyvalent carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

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, Hydrogenated bisphenol A, etc.) and aromatic diols (for example, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, as the polyhydric alcohol, for example, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.
As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
A polyhydric alcohol may be used individually by 1 type, and may use 2 or more types together.

The glass transition temperature (Tg) of the amorphous 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 determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, described in the method for determining the glass transition temperature in JIS K-1987 “Method for Measuring Transition Temperature of Plastics”. It is determined by “extrapolated glass transition start temperature”.

The weight average molecular weight (Mw) of the amorphous polyester resin is preferably from 5,000 to 1,000,000, more preferably from 7,000 to 500,000.
The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2000 or more and 100,000 or less.
The molecular weight distribution Mw / Mn of the amorphous 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 with a THF solvent using a Tosoh GPC / HLC-8120GPC as a measuring device and a Tosoh column / TSKgel SuperHM-M (15 cm). The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample from this measurement result.

The amorphous polyester resin can be obtained by a known production method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure in the reaction system is reduced as necessary, and the reaction is performed while removing water and alcohol generated during the condensation.
In addition, when the monomer of the raw material is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added and dissolved as a solubilizing agent. In this case, the polycondensation reaction is performed while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, the monomer with poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polymerized together with the main component. It is good to condense.

Next, the crystalline polyester resin will be described.
The crystalline polyester resin is a polyester resin (polycondensate) obtained by polycondensing at least a carboxylic acid component and an alcohol component. In the case where the crystalline polyester is a copolymer obtained by copolymerizing other components with respect to the main chain, if the other components are 50% by mass or less, this copolymer is also called a crystalline polyester resin.
In addition, as a crystalline polyester resin, a commercial item may be used and what was synthesize | combined may be used.
Here, since the crystalline polyester resin easily forms a crystal structure, a polycondensate using a polymerizable monomer having a linear aliphatic group is preferable to a polymerizable monomer having an aromatic group.

  Examples of the carboxylic acid component include polyvalent carboxylic acids. Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (for example, oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid. Acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acid (eg phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid) Dibasic acids such as acids), anhydrides thereof, or lower (for example, having 1 to 5 carbon atoms) alkyl esters.

The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid or a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (for example, 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), these Examples thereof include anhydrides and lower (for example, having 1 to 5 carbon atoms) alkyl esters thereof.
As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids.
Polyvalent carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Examples of the alcohol component include polyhydric alcohols. Examples of the polyhydric alcohol include aliphatic diols (for example, linear aliphatic diols having a main chain portion having 7 to 20 carbon atoms). Examples of the aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8- Octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18- Examples include octadecanediol and 1,14-eicosandecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferable as the aliphatic diol.
The polyhydric alcohol may be used in combination with a diol and a trivalent or higher alcohol having a crosslinked structure or a branched structure. Examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like.
A polyhydric alcohol may be used individually by 1 type, and may use 2 or more types together.

  Here, the polyhydric alcohol may have an aliphatic diol content of 80 mol% or more, and preferably 90 mol% or more.

Among the crystalline polyester resins, from the viewpoint of making the rate of change in the free amount of silica particles after heating into a specific range, a carboxylic acid component, an alcohol component containing an aliphatic polyhydric alcohol having 4 to 8 carbon atoms, Polyester resins obtained by polycondensation of at least are preferred. A crystalline polyester resin using an aliphatic polyhydric alcohol having 4 to 8 carbon atoms as an alcohol component is less likely to be exposed on the surface of toner particles even after heat storage.
As the carboxylic acid component, an aliphatic dicarboxylic acid is preferable. The aliphatic dicarboxylic acid may be linear, branched, or cyclic, and may be saturated or unsaturated. Among these, a linear aliphatic dicarboxylic acid having 6 to 14 carbon atoms is preferable, and a linear aliphatic dicarboxylic acid having 8 to 12 carbon atoms is more preferable. Among these, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, and 1,8 octanedicarboxylic acid are more preferable. The carbon number of the aliphatic dicarboxylic acid is the carbon number including the carbon of the carboxyl group.

  As the aliphatic polyhydric alcohol having 4 to 8 carbon atoms, an aliphatic diol is preferable. The aliphatic diol may be linear, branched, or cyclic, and may be saturated or unsaturated. Among these, a linear aliphatic diol having 5 to 8 carbon atoms is preferable, and a linear aliphatic diol having 6 to 8 carbon atoms is more preferable. Among these, 1,4-butanediol, 1,6-hexanediol, and 1,8-octanediol are more preferable. In particular, 1,6-hexanediol is preferable.

The melting temperature of the crystalline polyester resin is preferably 50 ° C. or higher and 100 ° C. or lower, more preferably 55 ° C. or higher and 90 ° C. or lower, and further preferably 60 ° C. or higher and 85 ° C. or lower.
The melting temperature is determined from the “melting peak temperature” described in the method for determining the melting temperature of JIS K7121-1987 “Method for measuring the transition temperature of plastic” from the DSC curve obtained by differential scanning calorimetry (DSC).

  The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

  The crystalline polyester resin can be obtained by, for example, a well-known manufacturing method, similarly to the amorphous polyester resin.

  The crystalline polyester resin is preferably 2% by mass or more and 40% by mass or less, and more preferably 2% by mass or more and 20% by mass or less with respect to the total binder resin.

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

  The binder resin may contain other crystalline resin other than the crystalline polyester resin. Examples of other crystalline resins include known resins such as epoxy resins, polyurethane resins, cellulose resins, polyether resins, polyamide resins, vinyl resins, and modified rosins. Other crystalline resins are blended within a range that does not affect the toner characteristics.

-Colorant-
Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmine 6B, Dupont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, or acridine, xanthene, , Benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazole, and other dyes Etc.
A colorant may be used individually by 1 type and may use 2 or more types together.

  As the colorant, a surface-treated colorant may be used as necessary, or it may be used in combination with a dispersant. A plurality 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.

-Release agent-
Examples of mold release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; and 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) according to the “melting peak temperature” described in JIS K-1987 “Method for measuring the transition temperature of plastics”.

  The content of the release agent is, for example, preferably 1% by mass to 20% by mass and more preferably 5% by mass to 15% by mass with respect to the entire toner particles.

-Other additives-
Examples of other additives include known additives such as a magnetic material, a charge control agent, and inorganic powder. These additives are contained in the toner particles as internal additives.

-Toner particle characteristics-
The toner particles may be toner particles having a single layer structure, or toner particles having a so-called core / shell structure composed of a core (core particle) and a coating layer (shell layer) covering the core. May be.
Here, the toner particles having a core / shell structure include, for example, a binder resin (amorphous resin and crystalline polyester resin) and, if necessary, other additives such as a colorant and a release agent. It is preferable that it is comprised with the core part and the coating layer comprised including binder resin (amorphous resin).

  The volume average particle diameter (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 diameters and various particle size distribution indexes of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman-Coulter), and the electrolyte is measured using ISOTON-II (manufactured by Beckman-Coulter). The
In the measurement, 0.5 mg to 50 mg of a measurement sample is added as a dispersant to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate). This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolyte 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 to 60 μm is measured using a 100 μm aperture with a Coulter Multisizer II. taking measurement. The number of particles to be sampled is 50,000.
For the particle size range (channel) divided based on the measured particle size distribution, the cumulative distribution is drawn from the smaller diameter side to the volume and number, respectively, and the particle size to be 16% is the volume particle size D16v, the number particle size D16p, a particle size that is 50% cumulative is defined as a volume average particle size D50v, a cumulative number average particle size D50p, and a particle size that is 84% cumulative is defined as a volume particle size D84v and a number particle size D84p.
Using these, the volume average particle size distribution index (GSDv) is calculated as (D84v / D16v) ^1/2 and the number average particle size distribution index (GSDp) is calculated as (D84p / D16p) ^1/2 .

  The shape factor SF1 of the toner particles is preferably 110 or more and 150 or less, and more preferably 120 or more and 140 or less.

The shape factor SF1 is obtained by the following formula.
Formula: SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML represents the absolute maximum length of the toner, and A represents the projected area of the toner.
Specifically, the shape factor SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and is calculated as follows. That is, by capturing an optical microscope image of particles dispersed on the surface of a slide glass into a Luzex image analyzer using a video camera, obtaining the maximum length and projected area of 100 particles, calculating by the above formula, and obtaining the average value can get.

(External additive)
To the toner particles according to the exemplary embodiment, silica particles and other particles are externally added as necessary.

-Silica particles-
In the toner particles according to the present embodiment, the rate of change in the free amount of silica particles after heating is 20% to 60%, preferably 20% to 50%, more preferably 20% to 40%. .
Here, “after heating” means that the toner has been stored for 17 hours under the conditions of a temperature of 45 ° C. and a humidity of 50% RH. The rate of change in the free amount of silica particles after heating refers to the ratio of the silica particles released from the toner particles after heating to the silica particles released from the toner particles before heating.
By making the rate of change of the liberated amount of silica particles after heating 60% or less, a decrease in the liberated amount of silica particles after heating is suppressed, and a decrease in cleaning properties is suppressed. On the other hand, the release rate of the silica particles of the toner before heating is excessively high (that is, the silica particles are weakly adhered and the amount of silica particles adhering to the surface of the toner particles is small), or before heating. In a state where the release rate of the silica particles of the toner is excessively low (that is, a state where the silica particles have a strong adhesion force and a large amount of silica particles are attached to the surface of the toner particles), The rate of change is less than 20%.
When the release rate of the silica particles of the toner before heating is excessively high, aggregation between the toner particles occurs after heat storage, and the fluidity of the toner tends to deteriorate. Further, since the free silica particles are easily transferred to the carrier, the fluidity of the toner is further deteriorated. As a result, fluctuations in image density are likely to occur.
When the silica particle liberation rate of the toner before heating is excessively low, the liberation amount of the silica particles is excessively small, so that the cleaning properties are likely to deteriorate both before and after thermal storage.

  Examples of a method for setting the rate of change in the free amount of silica particles after heating include the above-described method of selecting a polymerization component of the binder resin contained in the toner particles; And a method of selecting a particle size. As a method for selecting the polymerization component of the binder resin contained in the toner particles, for example, when a crystalline polyester resin is applied as the binder resin, the polycondensation component includes a carboxylic acid component and a carbon number of 4 or more and 8 or less. And an alcohol component containing an aliphatic polyhydric alcohol.

-Free amount of silica particles before and after heating, rate of change of free amount of silica particles after heating-
2 g of toner to be measured is added to 40 ml of an aqueous solution of 0.2% surfactant (polyoxyethylene (10) octylphenyl ether having a degree of polymerization of 10 polyoxyethylene, manufactured by Wako Pure Chemical Industries, Ltd.) Disperse well so that it gets wet with the aqueous solution. In this state, an ultrasonic homogenizer US300T (manufactured by Nippon Seiki Seisakusho) is used, and ultrasonic vibration with an output of 20 W and a frequency of 20 kHz is applied for 1 minute to desorb (release) silica particles. Then, for the free silica particles, fluorescent X-ray measurement (manufactured by Rigaku Corporation: ZSX Primus II) is performed with an applied voltage of 30 kV, an applied current of 100 mA, and a spectral crystal of PET. By this measurement, the free amount of silica particles in the toner before heating (hereinafter also referred to as “silica particle free amount before heating”) and the free amount of silica particles in the heated toner “silica particle free amount after heating”. ”Respectively. And the change rate of the free amount of the silica particle after a heating is computed from a following formula.
Formula: Change rate of free amount of silica particles after heating (%) = [(free amount of silica particles after heating) / (free amount of silica particles before heating)] × 100

In addition, the liberation rate of the silica particles before heating is preferably 15% or more and 40% or less.
The liberation rate of the silica particles before heating is the ratio of the silica particles released from the toner particles to the total silica particles contained in the toner. The liberation rate of the silica particles before heating is determined by the following method.
First, with respect to 2 g of toner before heating, fluorescent X-ray measurement (manufactured by Rigaku Corporation: ZSX Primus II) was performed with an applied voltage of 30 kV, an applied current of 100 mA, and a spectral crystal of PET. The amount (hereinafter also referred to as “amount of silica particles before heating”) is determined. Next, with respect to 2 g of the toner before heating, the “silica particle liberation amount before heating” is obtained in the same procedure as the above measurement method. And the liberation rate of the silica particle before a heating is computed from a following formula.
Formula: Silica particle release rate (%) before heating = [(silica particle amount before heating) − (silica particle release amount before heating) / (silica particle amount before heating)] × 100

  The silica particles preferably have a number average particle size of 80 nm or more and 500 nm or less, more preferably 90 nm or more and 300 nm or less, and even more preferably 100 nm or more and 200 nm or less, from the viewpoint of setting the rate of change in the free amount of silica particles after heating to a specific range. . In particular, a toner in which a crystalline polyester resin containing 1,6-hexanediol as an alcohol component and silica particles having a number average particle diameter of 80 nm or more and 110 nm or less as an external additive is desirable, and the effect is improved.

  The number average particle diameter of the silica particles is suitably measured by Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) when silica particles separated from the toner are used. When the toner is directly observed and used, 100 primary particles are observed with a scanning electron microscope SEM (Scanning Electron Microscope) apparatus (manufactured by Hitachi, Ltd .: S-4100), and an image is taken. It is taken into an image analyzer (LUZEXIII, manufactured by Nireco Co., Ltd.) and calculated as a number average particle diameter of equivalent circle diameters obtained by image analysis of primary particles. Note that the magnification of the electron microscope is adjusted so that about 10 to 50 silica particles are captured in one field of view, and the equivalent circle diameter of the primary particles is obtained by observing a plurality of fields of view.

  Examples of the silica particles include fumed silica, colloidal silica, silica gel and the like, and are used without particular limitation. These silica particles may be used alone or in combination of two or more.

  For example, the external addition amount of the silica particles is preferably 0.3% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 5% by mass or less with respect to the total mass of the toner particles.

-Other particles-
Other particles include TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO · SiO _2. , K ₂ O. (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like.

The surface of the inorganic particles (silica particles, other particles) as an external additive is preferably subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing inorganic particles in a hydrophobic treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents and the like. These may be used individually by 1 type and may use 2 or more types together.
The amount of the hydrophobizing agent is usually 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles, for example.

  Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning activators (for example, metal salts of higher fatty acids typified by zinc stearate, fluorine-based high molecular weight substances). Particle) and the like.

  The external addition amount of the external additive is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less with respect to the toner particles.

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

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 aggregation coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). The production method of the toner particles is not particularly limited, and a known production method is adopted.
Among these, it is preferable to obtain toner particles by an aggregation and coalescence method.

Specifically, for example, when toner particles are produced by an aggregation coalescence method,
A step of preparing a resin particle dispersion in which resin particles to be a binder resin are dispersed (resin particle dispersion preparation step), and a resin particle dispersion (after mixing other particle dispersions as necessary) In the dispersion), the resin particles (other particles as necessary) are aggregated to form aggregated particles (aggregated particle formation step), and the aggregated particle dispersion in which the aggregated particles are dispersed is heated. Then, toner particles are manufactured through a step of fusing and coalescing the aggregated particles to form toner particles (fusing and coalescing step).

Details of each step will be described below.
In the following description, a method of obtaining toner particles containing a colorant and a release agent will be described. However, the colorant and the release agent are used as necessary. Of course, you may use other additives other than a coloring agent and a mold release agent.

-Preparation step of resin particle dispersion-
First, together with a resin particle dispersion in which resin particles serving as a binder resin are dispersed, for example, a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared. To do.

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

Examples of the dispersion medium used for the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together.

Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an anionic surfactant and a cationic surfactant are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
Surfactant may be used individually by 1 type and may use 2 or more types together.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion include a general dispersion method such as a rotary shear homogenizer, a ball mill having media, a sand mill, and a dyno mill. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method.
The phase inversion emulsification method is a method in which a 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 aqueous medium. (W phase) is added to convert the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase and disperse the resin in an aqueous medium in the form of particles. It is.

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

  As content of the resin particle contained in a resin particle dispersion liquid, 5 to 50 mass% is preferable, for example, and 10 to 40 mass% is more preferable.

  For example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. In other words, regarding the volume average particle diameter of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the content of the particles, the colorant particles dispersed in the colorant particle dispersion and the release agent particle dispersion The same applies to the release agent particles to be dispersed.

-Aggregated 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, resin particles, colorant particles, and release agent particles are hetero-aggregated to have resin particles, colorant particles, and release agent particles having a diameter close to the diameter of the target toner particles. Aggregated particles are formed.

Specifically, for example, the flocculant is added to the mixed dispersion, and 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 resin particles are heated to a glass transition temperature (specifically, for example, the glass transition temperature of the resin particles −30 ° C. or more and the glass transition temperature −10 ° C. or less), and the particles dispersed in the mixed dispersion liquid are aggregated. , Forming aggregated particles.
In the agglomerated particle forming step, for example, the aggregating agent is added at room temperature (for example, 25 ° C.) while stirring the mixed dispersion with a rotary shearing homogenizer, and the pH of the mixed dispersion is acidic (for example, the pH is 2 or more and 5 or less). ), And after adding a dispersion stabilizer as necessary, the heating may be performed.

Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher-valent 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 inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and inorganic substances such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include metal salt polymers.
A water-soluble chelating agent may be used as the chelating agent. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), and the like.
As addition amount of a chelating agent, 0.01 mass part or more and 5.0 mass part or less are preferable with respect to 100 mass parts of resin particles, for example, and 0.1 mass part or more and less than 3.0 mass parts are more preferable.

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

Through the above steps, toner particles are obtained.
In addition, after obtaining the aggregated particle dispersion liquid in which the aggregated particles are dispersed, the aggregated 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 aggregated particles. A process of aggregating to adhere to form second aggregated particles, and heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles. The toner particles may be manufactured through a step of forming toner particles having a core / shell structure.

Here, after completion of the coalescence / union process, toner particles formed in the solution are dried through a known washing process, solid-liquid separation process, and drying process to obtain toner particles.
In the washing step, it is preferable to sufficiently carry out substitution washing with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, etc. are preferably performed from the viewpoint of productivity. Also, the drying process is not particularly limited, but from the viewpoint of productivity, freeze drying, flash jet drying, fluidized drying, vibration fluidized drying, or the like is preferably performed.

  The toner according to the exemplary embodiment is manufactured, for example, by adding an external additive to the obtained dry toner particles and mixing them. Mixing may be performed, for example, with a V blender, a Henschel mixer, a Ladyge mixer, or the like. Furthermore, if necessary, coarse toner particles may be removed using a vibration classifier, a wind classifier, or the like.

<Electrostatic image developer>
The electrostatic charge image developer according to the exemplary embodiment includes at least the toner according to the exemplary embodiment.
The electrostatic image developer according to this embodiment may be a one-component developer including only the toner according to this embodiment, or may be a two-component developer mixed with the toner and a carrier.

There is no restriction | limiting in particular as a carrier, A well-known carrier is mentioned. As a carrier, for example, a coated carrier in which the surface of a core made of magnetic powder is coated with a coating resin; a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin; a porous magnetic powder is impregnated with a resin Resin impregnated type carriers; and the like.
Note that the magnetic powder-dispersed carrier and the resin-impregnated carrier may be a carrier 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, styrene-acrylic acid copolymer. Examples thereof include a polymer, a straight silicone resin containing an organosiloxane bond or a modified product thereof, a fluororesin, a polyester, a polycarbonate, a phenol resin, and an epoxy resin.
The coating resin and matrix resin may contain other additives such as conductive particles. Examples of the conductive particles include particles of metals such as gold, silver, and copper, 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 layer forming solution obtained by dissolving the coating resin and, if necessary, various additives in an appropriate solvent may 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 the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the core material, and a state in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed, a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater, and the 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 Apparatus / 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 carrier, a charging unit that charges the surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, and an electrostatic charge. Development means for containing an image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer, and the toner image formed on the surface of the image carrier as a recording medium A transfer unit that transfers the toner image transferred onto the surface of the recording medium, and a fixing unit that fixes the toner image transferred onto the surface of the recording medium. The electrostatic charge image developer according to this embodiment is applied as the electrostatic charge image developer.

  In the image forming apparatus according to this embodiment, a charging process for charging the surface of the image carrier, an electrostatic charge image forming process for forming an electrostatic image on the surface of the charged image carrier, and an electrostatic charge according to this embodiment. A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with an image developer; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of the recording medium; An image forming method (an image forming method according to this embodiment) including a cleaning process for cleaning the surface of the image carrier with a cleaning blade and a fixing process for fixing the toner image transferred to the surface of the recording medium is performed. The

The image forming apparatus according to the present embodiment is a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; the toner image formed on the surface of the image carrier is transferred to an intermediate transfer member Intermediate transfer system device that primarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the intermediate transfer body; then neutralizes the image on the surface of the image carrier after the toner image is transferred and before charging. A well-known image forming apparatus such as an apparatus provided with a neutralizing unit that performs neutralization by irradiating is applied.
In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred to the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body. And a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium.

  In the image forming apparatus according to the present embodiment, for example, the part including the developing unit may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including a developing unit 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 described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present embodiment.
The image forming apparatus shown in FIG. 1 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter sometimes simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged in parallel at a predetermined distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a drive roll 22 and a support roll 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other in the left to right direction in the drawing. The vehicle travels in the direction toward the unit 10K. The support roll 24 is applied with a force 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. An intermediate transfer member cleaning device 30 is provided on the side of the image carrier of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K has yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. The toner including the four color toners is supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. It should be noted that reference numerals with magenta (M), cyan (C), and black (K) are attached to the same parts as those of the first unit 10Y instead of yellow (Y). Description of the units 10M, 10C, and 10K will be omitted.

The first unit 10Y includes a photoreceptor 1Y that functions as an image holding member. Around the photoreceptor 1Y, a charging roll (an example of a charging unit) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal. Then, an exposure device (an example of an electrostatic image forming unit) 3 that forms an electrostatic image, and a developing device (an example of a developing unit) 4Y that develops the electrostatic image by supplying toner charged to the electrostatic image, developed A photoreceptor cleaning device having a primary transfer roll 5Y (an example of a primary transfer unit) that transfers a toner image onto the intermediate transfer belt 20, and a cleaning blade 6Y-1 that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer. (Example of cleaning means) 6Y are arranged in order.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (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 source varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described.
First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y.
The photoreceptor 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 resistance (general resin resistance), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image having a yellow image pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic charge image on the photoreceptor 1Y is visualized (developed image) as a toner image by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge image developer containing at least yellow toner and a carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged electric charge on the photoreceptor 1Y, and has a developer roll (a developer holding member). Example) is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y is applied to the toner image, so that the photoreceptor is exposed. 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 photoreceptor 1Y is removed and collected by the cleaning blade 6Y-1 of the photoreceptor cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled in accordance with the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The

  The intermediate transfer belt 20 on which the four color toner images are transferred in multiple ways through the first to fourth units is disposed on the image transfer surface side of the intermediate transfer belt 20, the support roll 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roll (an example of a secondary transfer unit) 26 is formed to a secondary transfer portion configured. On the other hand, recording paper (an example of a recording medium) P is fed at a predetermined timing into a gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact with each other via a supply mechanism, and the secondary transfer bias is supplied to the support roll. 24. The transfer bias applied at this time is a (−) polarity that is the same polarity 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, so The toner image is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording paper P is fed into the pressure contact portions (nip portions) of a pair of fixing rolls in a fixing device (an example of a fixing unit) 28, and the toner image is fixed on the recording paper P to form a fixed image.

Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, and the like. In addition to the recording paper P, the recording medium may be an OHP sheet.
In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is also preferably smooth. For example, coated paper with the surface of plain paper coated with resin, art paper for printing, etc. are preferably used. Is done.

  The recording paper P on which the color image has been fixed is carried out toward the discharge 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 accommodates the electrostatic image developer according to the present embodiment, and develops the electrostatic image formed on the surface of the image carrier as a toner image by the electrostatic image developer. And a process cartridge that can be attached to and detached from the image forming apparatus.

  Note that the process cartridge according to the present embodiment is not limited to the above-described configuration, and other means such as a developing device and other units such as an image carrier, a charging unit, an electrostatic charge image forming unit, and a transfer unit, if necessary. And at least one selected from the above.

  Hereinafter, an example of the process cartridge according to the present embodiment will be shown, but the present invention is not limited to this. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

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 and the photoconductor 107 by, for example, a housing 117 provided with an attachment rail 116 and an opening 118 for exposure. A charged roll 108 (an example of a charging unit), a developing device 111 (an example of a developing unit), and a photosensitive member cleaning device 113 (an example of a cleaning unit) having a cleaning blade 113-1 are held in an integrated combination. It is configured and made into a cartridge.
In FIG. 2, 109 is an exposure device (an example of an electrostatic charge image forming unit), 112 is a transfer device (an example of a transfer unit), 115 is a fixing device (an example of a fixing unit), and 300 is a recording paper (a recording medium). An example).

Next, the toner cartridge according to this embodiment will be described.
The toner cartridge according to the present exemplary embodiment is a toner cartridge that accommodates the toner according to the present exemplary embodiment and is detachable from the image forming apparatus. The toner cartridge contains toner for replenishment to be supplied 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 configuration in which toner cartridges 8Y, 8M, 8C, and 8K are attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are each developing devices (colors). And a toner supply pipe (not shown). Further, when the amount of toner stored in the toner cartridge becomes low, the toner cartridge is replaced.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention. In the text, “part” means “part by mass” and “%” means “mass%” unless otherwise specified.

[Preparation of crystalline polyester resin dispersion]
(Preparation of crystalline polyester resin dispersion)
Into a heat-dried three-necked flask, 44 mol parts of 1,9-nonanediol, 56 mol parts of dodecanedicarboxylic acid and 0.05 mol parts of dibutyltin oxide were introduced, and nitrogen gas was introduced into the container to maintain an inert atmosphere. After the temperature rise, the polycondensation reaction is carried out at 150 ° C. to 230 ° C. for 2 hours, and then the temperature is gradually raised to 230 ° C. and stirred for 5 hours. A synthetic polyester resin was synthesized.
Next, 3,000 parts of the obtained crystalline polyester resin, 10,000 parts of ion-exchanged water, and sodium dodecylbenzenesulfonate surfactant are added to an emulsification tank of a high-temperature / high-pressure emulsifier (Cabitron CD1010, slit: 0.4 mm). After 90 parts were added, the mixture was heated and melted to 130 ° C., dispersed at 110 ° C. at a flow rate of 3 L / m at 10,000 rotations for 30 minutes, passed through a cooling tank, and a crystalline polyester resin dispersion (high temperature / high pressure emulsification The apparatus (Cabitron CD1010, slit 0.4 mm, manufactured by Cavitron) was recovered to obtain a crystalline polyester resin dispersion.

[Preparation of Amorphous Polyester Resin Dispersion]
15 mol parts of polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane and 85 mol parts of polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane 10 mol parts of terephthalic acid, 67 mol parts of fumaric acid, 3 mol parts of n-dodecenyl succinic acid, 20 mol parts of trimellitic acid, and these acid components (terephthalic acid, n-dodecenyl succinic acid, trimellitic acid, 0.05 mol part of dibutyltin oxide is added to the total number of moles of fumaric acid), nitrogen gas is introduced into the container and the temperature is maintained in an inert atmosphere, and then heated at 150 to 230 ° C. The copolycondensation reaction was carried out for 20 hours. Thereafter, the pressure was gradually reduced at 210 ° C. to 250 ° C. to synthesize an amorphous polyester resin. The weight average molecular weight Mw of this resin was 65,000. Next, 3,000 parts of the obtained amorphous polyester resin, 10,000 parts of ion-exchanged water, and surfactant dodecylbenzenesulfonic acid were added to an emulsification tank of a high-temperature and high-pressure emulsifier (Cabitron CD1010, slit: 0.4 mm). After adding 90 parts of sodium, the mixture was heated and melted to 130 ° C., dispersed at 110 ° C. at a flow rate of 3 L / m for 30 minutes at 10,000 revolutions, passed through a cooling tank, and then an amorphous polyester resin dispersion (high temperature. A high-pressure emulsifier (Cavitron CD1010, slit 0.4 mm, manufactured by Cavitron) was recovered to obtain an amorphous polyester resin dispersion.

[Preparation of colorant dispersion]
-Cyan pigment (copper phthalocyanine B15: 3: manufactured by Dainichi Seika Kogyo Co., Ltd.): 1,000 parts-Ionic surfactant Neogen RK (Daiichi Kogyo Seiyaku Co., Ltd.): 150 parts-Ion-exchanged water: 4,000 parts The above compounded solution is mixed and dissolved, and dispersed for 1 hour with a high-pressure impact disperser Ultimizer (HJP30006, manufactured by Sugino Machine Co., Ltd.), and a colorant dispersion having a volume average particle size of 180 nm and a solid content of 20%. Got.

[Preparation of release agent dispersion]
Paraffin wax HNP9 (melting temperature 75 ° C .: manufactured by Nippon Seiki Co., Ltd.): 46 parts Cationic surfactant Neogen RK (produced by Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts Ion exchange water: 200 parts or more Is heated to 100 ° C. and sufficiently dispersed with IKA Ultra Turrax T50, and then dispersed with a pressure discharge type gorin homogenizer to obtain a release agent dispersion having a center diameter of 200 nm and a solid content of 20.0%. It was.

[Production of toner particles]
(Production of toner particles (1))
Amorphous polyester resin dispersion: 256.8 parts Crystalline polyester resin dispersion: 33.2 parts Colorant dispersion: 27.4 parts Release agent dispersion: 35 parts Above is made of round stainless steel In the flask, the mixture was thoroughly mixed and dispersed with Ultra Turrax T50. Next, 0.20 part of polyaluminum chloride was added thereto, and the dispersion operation was continued with an ultra turrax. The flask was heated to 48 ° C. with stirring in an oil bath for heating. After maintaining at 48 ° C. for 60 minutes, 70.0 parts of the amorphous polyester resin dispersion was added thereto. Thereafter, the pH of the system was adjusted to 8.0 with a 0.5 mol / L sodium hydroxide aqueous solution, and then the stainless steel flask was sealed and heated to 96 ° C. while continuing to stir using a magnetic seal for 3 hours. Retained. After completion of the reaction, the mixture was cooled, filtered, sufficiently washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 1,000 parts of ion-exchanged water at 30 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the pH of the filtrate was 7.5 and the electric conductivity was 7.0 μS / cm, No. 2 was obtained by Nutsche suction filtration. Solid-liquid separation was performed using 5A filter paper. Next, vacuum drying was continued for 12 hours to obtain toner particles (1).
The particle diameter of the obtained toner particles (1) was measured by Coulter Multisizer II (manufactured by Beckman Coulter, Inc.). The volume average particle diameter was 5.8 μm. In addition, the particle shape factor SF1 obtained by shape observation with Luzex was 129.

(Preparation of toner particles (2))
Toner particles (2) were prepared in the same manner as toner particles (1) except that 1,9-nonanediol was changed to 1,6-hexanediol in the composition of the crystalline resin.
The particle diameter of the obtained toner particles (2) was measured by Coulter Multisizer II (manufactured by Beckman Coulter, Inc.). The volume average particle diameter was 5.7 μm. Further, the shape factor SF1 of the particle determined by shape observation with Luzex was 130.

(Production of toner particles (3))
Toner particles (3) were prepared in the same manner as toner particles (1) except that 1,9-nonanediol was changed to 1,4-butanediol in the crystalline resin composition.

(Production of toner particles (4))
Toner particles (4) were prepared in the same manner as toner particles (1) except that 1,9-nonanediol was changed to 1,8-octanediol in the crystalline resin composition.

(Production of toner particles (5))
Same as the production of toner particles (1) except that in the composition of the crystalline resin, dodecanedicarboxylic acid is changed to 1,8-octanedicarboxylic acid and 1,9-nonanediol is changed to 1,6-hexanediol. Thus, toner particles (5) were produced.

(Production of toner particles (6))
Toner particles (6) were prepared in the same manner as toner particles (1) except that 1,9-nonanediol was changed to 1,3-propanediol in the crystalline resin composition.

  The carboxylic acid component and alcohol component of the crystalline polyester resin used in the production of the toner particles (1) to (6) are summarized in Table 1 below.

[Preparation of external additive (silica particles)]
(Preparation of silica particles a)
150 parts of tetramethoxysilane was stirred at 280 rpm while 150 parts of 25% aqueous ammonia was added dropwise at 30 ° C. over 5 hours in the presence of 100 parts of ion-exchanged water and 100 parts of 25% alcohol. The silica sol suspension obtained by this reaction is centrifuged, separated into wet silica gel, alcohol and aqueous ammonia, and the separated wet silica gel is dried at 120 ° C. for 2 hours, and then 100 parts of silica and 500 parts of ethanol are mixed. Was put into an evaporator and stirred for 15 minutes while maintaining the temperature at 40 ° C. Next, 10 parts of dimethyldimethoxysilane was added to 100 parts of silica, and the mixture was further stirred for 15 minutes. Finally, the temperature was raised to 90 ° C. and ethanol was dried under reduced pressure. The treated product was taken out and further vacuum dried at 120 ° C. for 30 minutes. The dried silica was pulverized to obtain silica particles a having a number average particle diameter of 60 nm.

(Preparation of silica particles b)
In the production of the silica particles a, an average particle size of 80 nm was prepared by the same production method as that for the silica particles a, except that 25% ammonia water was added at 150 rpm while dropping 150 parts of ammonia water over 4 hours. Of silica particles b were obtained.

(Preparation of silica particles c)
In the production of the silica particles a, an average particle size of 150 nm was obtained by the same production method as the silica particles a, except that 25% ammonia water was added at 150 rpm while dropping 150 parts of ammonia water over 4 hours. Of silica particles c were obtained.

(Preparation of silica particles d)
In the production of silica particles a, an average particle size of 500 nm was obtained by the same production method as silica particles a, except that 25% ammonia water was added at 150 rpm while dropping 150 parts of ammonia water over 1 hour. Of silica particles d were obtained.

(Preparation of silica particles e)
In the production of silica particles a, an average particle size of 600 nm was prepared by the same production method as silica particles a, except that 25% ammonia water was added at 150 rpm while dropping 150 parts of ammonia water over 1 hour. Of silica particles e were obtained.

  Table 2 shows the number average particle diameter of the obtained silica particles a to e.

[Examples 1 to 6 and Comparative Examples 1 to 5]
(Production of toner)
The toners of Examples 1 to 6 and Comparative Examples 1 to 5 shown in Table 3 were prepared by combining the toner particle types shown in Table 1 and the silica particle types shown in Table 2. Specifically, 3.6 parts of silica particles were mixed with 100 parts of toner particles by a Henschel mixer at 3,600 rpm for 10 minutes to prepare a toner.
Then, for each of the obtained toners, “silica particle amount before heating”, “silica particle liberation amount before heating”, and “silica particle liberation amount after heating” are determined according to the method described above, The release rate (%) of the silica particles and the change rate (%) of the release amount of the silica particles before heating were calculated. The results are shown in Table 3.

(Creation of carrier)
Ferrite particles (average particle size 50 μm, volume electrical resistance 3 × 10 ⁸ Ω · cm): 100 parts Toluene: 14 parts Perfluorooctylethyl acrylate / dimethylaminoethyl methacrylate copolymer (copolymerization ratio 90:10, Mw = 50,000): 1.6 parts Carbon black (VXC-72, manufactured by Cabot Corporation): 0.12 parts Among the above components, the components except for the ferrite particles are dispersed with a stirrer for 10 minutes to obtain a film-forming solution. Prepared, put this coating liquid and ferrite particles in a vacuum deaeration type kneader, and stirred for 30 minutes at 60 ° C., then reduced pressure to remove toluene, to form a resin film on the ferrite particle surface, A carrier was manufactured. The obtained carrier had a volume average particle diameter of 51 μm.

(Development of developer)
The toner and carrier prepared above were each placed in a V blender at a mass ratio of 5:95 and stirred for 20 minutes to obtain developers of Examples 1 to 6 and Comparative Examples 1 to 5, respectively.
The obtained developer was filled in Docu Center Color 400 (manufactured by Fuji Xerox Co., Ltd.), and the following evaluations were performed.

[Evaluation]
The Docu Center Color400 manufactured by Fuji Xerox Co., Ltd. with the obtained developer was left in a low-temperature, low-humidity environment (15 ° C., 20% RH) for 1 day (17 hours). 000 sheets were output continuously. Thereafter, using C2 paper manufactured by Fuji Xerox Co., Ltd., the image forming conditions were adjusted so that the image density was within the range of 1.0 to 1.5, and a 5 cm × 5 cm patch was output. The image density (density 1) of the obtained patch was measured by the method described later.
Subsequently, the developer was allowed to stand for one day (17 hours) in a chamber at a high temperature and high humidity (45 ° C., 50% RH), and then 10,000 images of 50% area coverage were output continuously. Thereafter, using a C2 paper manufactured by Fuji Xerox Co., Ltd., a patch of 5 cm × 5 cm was output again under the same image forming conditions as the formation of the patch having a density of 1, and the image density (density 2) was measured.

(Image defect evaluation)
Check the image every 100 sheets for 10,000 images with 50% area coverage obtained by continuous output after standing for one day (17 hours) in the chamber of high temperature and high humidity (45 ° C 50% RH) The total number of streak-like image defects was counted. The results are shown in Table 3.
A (◯): Number of streak image defects ≤ 1 B (Δ): 1 sheet <Number of streak image defects ≤ 3 C (X): 3 sheets <Strain image defect occurrence Number

(Image density fluctuation evaluation (Δ image density (SAD: Sum of Absolute Difference) evaluation))
The Δ image density (SAD) value represented by the following formula was calculated from the density 1 and the density 2 and evaluated according to the following criteria. The image density was measured with an image densitometer X-RITE 938 (manufactured by X-RITE). The results are shown in Table 3.
Expression: ΔImage density = | Density 1−Density 2 |
The evaluation criteria are as follows.
A (◯): 0 <ΔImage density (SAD) ≦ 0.1
B (Δ): 0.1 <ΔImage density (SAD) ≦ 0.2
C (x): 0.2 <Δ image density (SAD)

From the results of the image defect evaluation, in Examples 1 to 6, compared with Comparative Examples 1 and 3 to 5, the developer was changed from a low temperature and low humidity environment (15 ° C. and 20% RH) to a high temperature and high humidity environment (45 ° C. and 50%). It was found that streak-like image defects are suppressed even after being placed in (RH).
In Examples 1 to 3, in which the number average particle diameter of the silica particles is 80 nm or more and 500 nm or less, the streak-like image defects may be further suppressed as compared with Comparative Example 1 in which the number average particle diameter of the silica particles is less than 80 nm. all right.
In Examples 2, 4 to 6 in which the aliphatic polyhydric alcohol contained as the polycondensation component of the crystalline polyester resin has 4 to 8 carbon atoms, Comparative Examples 5 and 3 having less than 4 carbon atoms or more than 8 carbon atoms. It was found that the streak-like image defect was further suppressed as compared with.
Furthermore, from the results of the image density fluctuation evaluation, it was found that Examples 1 to 6 also suppressed the fluctuation of the image density (that is, the reduction of the image density). In Comparative Example 2, it was found that the fluidity of the toner deteriorates and the image density decreases.

1Y, 1M, 1C, 1K, photoconductor (an example of an image carrier)
2Y, 2M, 2C, 2K, charging roll (an example of charging means)
3. Exposure device (an example of electrostatic charge image forming means)
3Y, 3M, 3C, 3K Laser beams 4Y, 4M, 4C, 4K Developing device (an example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (an example of primary transfer means)
6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of an intermediate transfer member)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer member cleaning device 107 Photosensitive member (an example of an image holding member)
108 Charging roll (an example of charging means)
109 Exposure apparatus (an example of electrostatic charge image forming means)
111 Developing device (an example of developing means)
112 Transfer device (an example of transfer means)
113 photoconductor cleaning device (an example of cleaning means)
115 Fixing device (an example of fixing means)
116 Mounting rail 117 Housing 118 Opening 200 for exposure Process cartridge 300 Recording paper (an example of a recording medium)
P Recording paper (an example of a recording medium)

Claims (8)

Toner particles containing amorphous resin and crystalline polyester resin, and external additive containing silica particles,
A toner for developing an electrostatic charge image, wherein a change rate of the liberated amount of the silica particles after heating with respect to the liberated amount of the silica particles before heating is 20% or more and 60% or less.   The toner for developing an electrostatic charge image according to claim 1, wherein the number average particle diameter of the silica particles is from 80 nm to 500 nm.   The crystalline polyester resin is a polyester resin obtained by polycondensing at least a carboxylic acid component and an alcohol component containing an aliphatic polyhydric alcohol having 4 to 8 carbon atoms. The toner for developing an electrostatic image according to the description.   An electrostatic charge image developer comprising the electrostatic charge image developing toner according to claim 1. Containing the toner for developing an electrostatic charge image according to any one of claims 1 to 3,
A toner cartridge to be attached to and detached from the image forming apparatus. A developing means for containing the electrostatic charge image developer according to claim 4 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer,
A process cartridge attached to and detached from the image forming apparatus. An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Development means for containing the electrostatic charge image developer according to claim 4 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Cleaning means having a cleaning blade for cleaning the surface of the image carrier;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: A charging step for charging the surface of the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 4;
A transfer step of transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
A cleaning step of cleaning the surface of the image carrier with a cleaning blade;
A fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising: