JP4189586B2 - Toner and toner production method - Google Patents

Description

  The present invention relates to a toner and a toner manufacturing method, and more particularly to a highly durable toner and a toner manufacturing method.

  In recent years, image forming techniques such as copying machines, printers, and facsimiles have been remarkably developed, and the most frequently used one belongs to an image forming system using an electrostatic image represented by an electrophotographic system. The reason is that this image forming method can form high-quality images at high speed, can form not only monochrome images but also color images, and has durability and stability that can withstand long-term use. .

  However, recently, the required level has gradually increased, and in particular, there is a high demand for improving the image quality. For this reason, the tendency to reduce the toner particle size has become remarkable.

  However, since the toner having a reduced particle size has a tendency to increase its surface area by the smaller particle size and to increase the van der Waals force and the like, sufficient friction with the charging member is required. As a result, as the image forming apparatus is downsized and speeded up, charging start-up performance in a short time is required, and a toner diameter reduction technology that solves these problems has been demanded.

  As a technique for imparting sufficient charging performance to the toner, there is a technique for adding an external additive. The technique of adding such an external additive not only realizes the toner charge rising in a short time but also tends to occur in the photosensitive member and the intermediate transfer member in addition to the function of improving the toner transferability and cleaning performance. By polishing the filmed product and keeping it clean, it has an effect of outputting a good toner image over a long period of time (see, for example, Patent Document 1).

  There is also a technology that uses inorganic particles as an external additive. The inorganic particles have a specific gravity close to that of the toner, have excellent mixing / dispersibility, and also have excellent charge retention, so that the toner can be charged, that is, developability / transferability. Excellent.

As a technique for adding an external additive to a toner, for example, inorganic particles having a volume average primary particle diameter of 5 to 100 nm are fixed on the surface of organic particles having a size of 0.1 to 5.0 μm (hereinafter also referred to as resin particles). A toner technology using the composite particles as an external additive is disclosed (for example, see Patent Document 1).
JP 2002-62681 A

  However, it has been found that conventional toners to which external additives are added are not particularly resistant to long-term use. For example, when the toner disclosed in Patent Document 1 described above is subjected to long-term use such as printing exceeding 1 million sheets, the spent on the carrier surface becomes remarkable, and sufficient frictional power failure is difficult to be performed. Had a trend. Along with long-term use, there have been problems due to the life of the developer, such as toner scattering and non-image area fogging. Thus, it was not durable enough to withstand long-term use.

  In addition, the above-mentioned problem appears more remarkably in an apparatus that can be downsized and that can handle image formation at high speed because it continues to receive the impact generated during stirring in the developing unit for a long period of time.

  Thus, in an image forming apparatus corresponding to long-term use, downsizing, and high speed, long-term use represented by printing of 1 million sheets or more, and an image forming apparatus that generates a large impact force in a developer unit, An object of the present invention is to provide a highly durable toner and developer that can be used stably.

The object of the present invention is achieved by adopting the following configuration.
(1)
A toner obtained by mixing toner particles containing at least a resin and a colorant and composite crosslinked particles ,
The composite crosslinked particles are obtained by polymerizing or condensing a polymerizable monomer in the presence of inorganic particles in an aqueous medium, and having inorganic particles present on or near the surface thereof. Toner.
(2)
2. The toner according to 1 above, wherein the toner particles constituting the toner have a volume average particle diameter of 2 to 8 μm and an average value of circularity of 0.951 to 0.988.
(3)
3. The toner according to 1 or 2, wherein the inorganic particles are colloidal silica, titanium oxide, or aluminum oxide.
(4)
Any one of the above 1-3, wherein the composite crosslinked particles are obtained by forming a polymerizable monomer by polymerization or condensation reaction in the presence of inorganic particles and then hydrophobizing. The toner according to claim 1.
(5)
5. The toner according to any one of 1 to 4, wherein the composite cross-linked particles contain 0.05 to 746 ppm of a water-soluble component, and the water-soluble component contains less than 138 ppm of aldehydes.
(6)
The toner particles constituting the toner have a volume average particle diameter of 2 to 8 μm and an average value of circularity of 0.951 to 0.988. The composite crosslinked particles contained in the toner are inorganic in an aqueous medium. A water-soluble component formed by polymerization or condensation reaction of a polymerizable monomer in the presence of particles, containing inorganic particles on or near the surface of the composite crosslinked particles, and containing less than 138 ppm of aldehydes is 0.05. 2. The toner according to 1 above, containing ˜746 ppm.
(7)
A toner monomer dispersion obtained by a wet method is solid-liquid separated and dried, and a polymerizable monomer is formed by polymerization or condensation reaction in the presence of inorganic particles in an aqueous medium in a toner base. A toner production method comprising producing a toner by dry mixing composite cross-linked particles containing inorganic particles on or near the surface of particles.
(8)
Composite comprising inorganic particles on or near the surface of particles formed by polymerizing or condensing a polymerizable monomer in an aqueous medium in the presence of inorganic particles in a toner particle dispersion obtained by a wet method A toner production method comprising producing a toner by mixing crosslinked particles.

  The toner and the toner production method of the present invention include a composite crosslinked particle having inorganic particles present on or near the surface as an external additive, so that the composite crosslinked particle can be deformed or flattened even when a large amount of printing is performed. As a result, the life of the developer is prolonged, the leakage of the charge amount is small even if left as it is, the toner filming on the surface of the photoreceptor and the scratch and wear of the photosensitive layer (hereinafter also referred to as the coating layer) are caused. And an excellent effect that the toner transfer rate is good can be obtained.

  The toner of the present invention is characterized by containing composite cross-linked particles in which inorganic particles are present on or near the surface as an external additive.

  As a result of studying the composite particles described above as the prior art, composite particles in which inorganic particles having a volume average primary particle diameter of 5 to 100 nm are fixed to the surfaces of organic particles (hereinafter also referred to as resin particles) are organic particles and metal. Inorganic particles typified by oxides are treated with a surface treatment device that imparts mechanical impact force or by a pulverizer, thereby fixing inorganic particles typified by metal oxides on the surface of organic particles to form a composite. It was what advanced. That is, the principle of fixing is that the inorganic particles are slightly deformed on the surface of the organic particles by applying a mechanical impact force by the surface treatment apparatus, and are fixed so that a part of the particles are embedded.

  Therefore, the organic particles used here must have a property that the organic particles are somewhat deformed because the inorganic particles are buried by mechanical impact force. Due to this characteristic, the composite particles undergo deformation such as flattening due to the impact of stirring over a long period of time, especially in “compact, lightweight, and high-speed” image forming devices that are under development. This was a cause of shortening the life of the agent.

  The composite crosslinked particles according to the present invention are polymerized or condensed while interposing polymerizable monomer droplets as a raw material of resin particles as inorganic particle dispersion stabilizers, thereby forming composite crosslinked particles, and mechanical impact Since the inorganic particles are bonded to the surface of the resin particles without giving them, the adhesive force between the inorganic particles and the organic particles as a base is strong. In addition, deformation and flattening of the composite crosslinked particles can be prevented by increasing the degree of crosslinking of the resin particles as necessary.

Here, terms used in the above configuration will be described.
<Surface, near the surface>
In the present invention, the “surface” means a state existing on the surface of the composite crosslinked particle observed with a transmission electron microscope or a field effect scanning electron microscope, and the “near surface” means the surface of the composite crosslinked particle. To the center (center of gravity) of the particles, and the surface is present on the surface from 20% of the particle radius.
<Average value of volume average particle diameter and circularity>
The “volume average particle diameter” referred to in the present invention is a volume average particle diameter, and can be determined by a laser diffraction particle size distribution analyzer “HELOS” (manufactured by JEOL Ltd.).

  The “circularity” referred to in the present invention is a value obtained from the following formula (1) when 2000 or more toner particles having a particle diameter of 1 μm or more are measured.

Formula (1)
Circularity = (peripheral length equivalent to a circle) / (perimeter of toner particle projection image)
= 2π × (particle projected area / π) ^1/2 / (periphery length of toner particle projected image)
Here, the circle equivalent is a circle having the same area as the toner particle projection image, and the circle equivalent diameter is a diameter equivalent to the circle.

  The circularity can be measured using “FPIA-2000” (manufactured by Sysmec). At this time, the equivalent circle diameter is defined by the following formula (2).

Formula (2)
Equivalent circle diameter = 2 × (projected area of particle / π) ^1/2
<Water-soluble ingredients>
The “water-soluble component” in the present invention is a water-soluble component contained in the composite crosslinked particle.

  The amount of the water-soluble component contained in the composite crosslinked particles can be measured by boiling the composite crosslinked particles in 250 ml of water, evaporating and drying 100 ml of the filtrate obtained by filtering after cooling, and weighing the remaining amount. it can. The amount of the water-soluble component contained in the composite crosslinked particles used in the present invention is the above remaining amount expressed in mass% with respect to the original composite crosslinked particles. However, aldehydes are values obtained by adding hydroxyamine hydrochloride to 100 ml of the above filtrate and titrating the precipitated hydrochloric acid with an alkali standard solution.

  Hereinafter, the present invention will be described in detail.

  In the present invention, a so-called chemical toner (also referred to as a polymerization toner) manufactured by a wet method is preferably used in order to obtain an extremely high developer life and a high-quality image. In this toner, the toner particles themselves have a relatively high water content as compared with the conventional pulverization method. Therefore, the amount of the water-soluble component contained in the composite crosslinked particles greatly affects the chargeability of the toner.

  The amount of the water-soluble component contained in the composite crosslinked particles is preferably 0.05 to 746 ppm. The amount of the water-soluble component contained in the composite crosslinked particles can be controlled by limiting the amount of the water-soluble component used during production and repeatedly washing the obtained particles with water.

  Here, the water-soluble component refers to salts contained in inorganic particles used as a surfactant (anionic surfactant, nonionic surfactant, etc.) and a dispersion stabilizer.

  Aldehydes (especially formaldehyde), which tend to remain in melamine resin, even with water-soluble components, tend to act on water vapor in the air and leak charge. The amount of aldehydes contained in the crosslinked particles is preferably less than 138 ppm.

  In addition, the amount of the water-soluble component contained in the crosslinked particles in the prior art was 1000 to 5000 ppm, and the content of aldehydes was 180 to 540 ppm.

  Examples of the inorganic particles used in the present invention include, but are not limited to, colloidal silica, titanium oxide, aluminum oxide, zinc antimonate, tin oxide, and mixtures thereof.

  The colloidal silica is amorphous silica fine particles made of silicic acid or silicate oxide (including silicate and silicate ester) dispersed in a colloidal form in a liquid mainly composed of water.

  For the above-mentioned titanium oxide, anatase type titanium oxide or amorphous titanium oxide is preferably used in order to hydrophobize and increase the hydrophobization rate.

  The hydrophobization rate is not particularly limited, but a hydrophobization rate (methanol wettability) of 40 to 95 is preferable. Methanol wettability is an evaluation of wettability to methanol. In this method, 0.2 g of inorganic particles to be measured are weighed and added to 50 ml of distilled water placed in a 200 ml beaker. Methanol is slowly dropped from a burette whose tip is immersed in a liquid, with slow stirring, until the entire inorganic particles are wet. When the amount of methanol necessary to completely wet the inorganic particles is a (ml), the hydrophobization rate is calculated by the following formula (3).

Formula (3) Hydrophobization rate = (a / (a + 50)) × 100
It is preferable that 10-60 mass% of inorganic particles are contained in the composite crosslinked particles. The particle diameter of the inorganic particles that also function as a dispersion stabilizer is preferably 6 to 32 nm, more preferably 7 to 17 nm in terms of volume average primary particle diameter.

  Next, a method for producing composite crosslinked particles will be described.

  The composite crosslinked particles used in the present invention are those obtained by polymerization or condensation reaction of polymerizable monomer droplets serving as a base resin in the presence of inorganic particles in an aqueous medium, or by the above method. It can be prepared by treating with a hydrophobizing agent (eg, silane coupling agent, silicone oil, etc.).

  The production of the composite cross-linked particles can include a method using a styrene resin as a base resin, a method using a melamine resin, and the like, but is not limited thereto.

<Styrenic composite crosslinked particles>
Composite crosslinked particles using a styrene resin can be obtained by the following production method.

  Soluble in styrenic monomer or polyfunctional monomer that becomes styrenic monomer and cross-linking agent, monomer mixture of other copolymerizable monomer, monomer or monomer mixture Inorganic particles that also function as polymerization initiators, surfactants, and dispersants are added to an aqueous medium to form a primary suspension of monomers having a volume average particle size of 0.3 to 4.0 μm, The primary suspension is ejected from a nozzle under pressure to form a secondary suspension, and the secondary suspension is polymerized to produce composite crosslinked particles having a volume average particle diameter of 0.05 to 1.5 μm. can do.

  As the monomer, a styrene monomer or a styrene monomer and another copolymerizable monomer are mixed to use a monomer mixture. Here, it is preferable that a styrene-type monomer is 50 mass% or more with respect to the monomer whole quantity.

  Examples of the styrene monomer include styrene and p-methylstyrene. Other copolymerizable monomers include, for example, acrylic ester monomers such as ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate; methacrylic monomers such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate. Acid ester monomers; alkyl vinyl ethers such as methyl vinyl ether; vinyl ester monomers such as vinyl acetate and vinyl butyrate; N-alkyl substituted acrylamides such as N-methylacrylamide and N-ethylacrylamide; acrylonitrile, methacrylonitrile, etc. Nitrile monomers: polyfunctional monomers such as divinylbenzene, ethylene glycol (meth) acrylate, and trimethylolpropane tri (meth) acrylate.

  These monomers can be used alone or in admixture of two or more as required. It is also possible to add additives such as dyes and pigments that can be dispersed or dissolved in the monomer. In the above monomer, (meth) acrylate means acrylate or methacrylate.

  As the crosslinking agent, a covalent crosslinking agent such as divinylbenzene or diacrylate is preferably used.

  The ratio (mass ratio) between the monomer and the aqueous medium during polymerization is preferably in the range of 1/10 to 1/2.

  Here, examples of the aqueous medium include water and a mixture of water and a water-soluble organic compound (for example, a lower alcohol).

  The polymerization initiator is not particularly limited as long as it is a commonly used oil-soluble polymerization catalyst that is soluble in the above-mentioned monomers, and examples thereof include benzoyl peroxide, lauroyl peroxide, and t-butyl peroxyoctoate. An azo catalyst such as a peroxide catalyst, azobisisobutyronitrile, azobisisovaleronitrile, or the like can be used.

  After dissolving these polymerization initiators in the above monomers and adding them to an aqueous medium containing inorganic particles and an amphoteric surfactant or a dispersion stabilizing aid added as necessary, a primary suspension is prepared. The

  Examples of inorganic particles that also function as a dispersion stabilizer include colloidal silica, aluminum oxide, acid value zirconium, zinc antimonate, and titanium oxide having a volume average primary particle diameter of 6 to 32 nm, preferably a volume average primary particle diameter of 7 to 17 nm. , And mixtures thereof are preferably used.

  The primary suspension can be prepared using an apparatus having a mechanism for dispersing a monomer by a shearing force. Specifically, an ordinary stirring device or a high-speed rotating stirring device such as a homomixer or CLEARMIX is used, and this device is stirred at a predetermined stirring speed for a predetermined time to produce a primary suspension.

  In the primary suspension, the monomer is preferably a droplet having a volume average particle size of 0.3 to 4.0 μm.

  In the production method according to the present invention, a liquid having a volume average particle diameter of 0.05 to 1.5 μm is produced by pressurizing and spraying a primary suspension in the form of droplets having a volume average particle diameter of 0.3 to 4.0 μm. It is preferred to obtain a secondary suspension containing droplets. As an apparatus used for pressure injection, for example, an apparatus connected to a processor of a type that injects a suspension from a nozzle, a type that causes liquids or liquids to collide with a predetermined plane under pressure of the suspension Can be used. Specific examples of the apparatus include, but are not limited to, a nanomizer, a harmonizer, a microfluidizer, and an optimizer.

  When the secondary suspension thus obtained is polymerized, composite crosslinked particles are formed. At this time, since the secondary suspension already contains a polymerization initiator, the polymerization can be started only by heating the suspension, for example. The heating conditions are set to a temperature and time suitable for the polymerization initiator and the type of monomer, but are usually preferably in the range of 40 to 100 ° C and 0.5 to 10 hours, 50 to 90 ° C, 1 to A range of 8 hours is more preferred. When the secondary suspension is polymerized, the monomer becomes a polymer with the volume average particle diameter in the secondary suspension as it is, so that polymer particles (composite crosslinked particles) having a uniform size can be obtained. .

  After polymerization, the polymer particles (composite crosslinked particles) are preferably separated from the aqueous medium by filtration, centrifugation, etc., washed with water or a solvent, dried and used as a powder.

  The volume average particle diameter can be measured using a Coulter Multisizer “SD-2000” (manufactured by Sysmex Corporation) which is an electric resistance type particle size distribution measuring apparatus.

<Melamine composite cross-linked particles>
Composite crosslinked particles using a melamine-based resin can be obtained by a manufacturing method in the following steps.

Step (a): In a suspension of colloidal silica having an average particle diameter of 5 to 70 nm in an aqueous medium, a melamine compound and an aldehyde compound are reacted under basic conditions to form a water-soluble melamine resin. A step of generating an aqueous solution of an initial condensate, and a step (b): adding an acid catalyst to the aqueous solution obtained in step (a) to precipitate spherical composite melamine resin particles, A method for producing particles.

  The spherical composite cured melamine resin particles obtained by the above method are characterized by being spherical cured melamine resin particles in which colloidal silica is unevenly distributed in the vicinity of the particle surface and having an average particle diameter of 0.05 to 100 μm.

  In the production of the composite crosslinked particles used in the present invention, the mechanism of action of colloidal silica is not clear, but probably because the amino groups in the melamine resin and the silanol groups present on the surface of the colloidal silica particles act in a hydrogen bonding manner. It is considered that colloidal silica plays a role as a surfactant during the precipitation of melamine-based cured resin particles.

  The composite cross-linked particles in which the colloidal silica obtained in the present invention is unevenly distributed in the vicinity of the particle surface have primary particles that are spherical and independent, have no pores, and the colloidal silica is the outermost surface of the particle or from the outermost surface. It exists in the vicinity of the particle surface within a depth of about 0.2 μm. Colloidal silica is embedded in the melamine-based cured resin near the particle surface or exists in a fixed state on the particle surface, but the outermost surface component is usually a melamine-based cured resin. In such a form, the sliced piece of the composite crosslinked particle can be easily observed by a photograph taken using an electron microscope.

Furthermore, step (c):
Step (c): The composite crosslinked particles obtained in step (b) and the inorganic particles having an average particle size of 1/5 or less of the average particle size of the composite crosslinked particles are directly or in an aqueous medium. It is also a method for producing composite crosslinked particles, which comprises a step of mixing and coating the surface of the composite crosslinked particles with inorganic particles.

  “Surface coating with inorganic particles” means that the inorganic particles are fixed on the surface of the composite crosslinked particles.

  First, the step (a) will be specifically described. As the melamine compound used in the step (a), melamine, a substituted melamine compound obtained by substituting the hydrogen of the amino group of melamine with an alkyl group, an alkenyl group or a phenyl group [US Pat. No. 5,998,573 (corresponding) (Japanese Patent: JP-A-9-143238). And a substituted melamine compound in which the hydrogen of the amino group of melamine is substituted with a hydroxyalkyl group, a hydroxyalkyl (oxaalkyl) n group or an aminoalkyl group [US Pat. No. 5,322,915 (corresponding Japanese Patent: Special (Kaihei 5-202157). ] Can be used. Of these, inexpensive melamine is most preferred.

  In addition, melamine compounds and some of the melamine compounds are urea, thiourea, ureas such as ethylene urea, guanamines such as benzoguanamine and acetoguanamine, phenols, cresol, alkylphenol, resorcin, hydroquinone, pyrogallol and other phenols, and aniline. It can be replaced and used as a mixture.

  Examples of the aldehyde compound include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, furfural and the like, but formaldehyde and paraformaldehyde which are inexpensive and have good reactivity with the melamine compound are preferable. As the aldehyde compound, it is preferable to use an aldehyde compound having an amount of 1.1 to 6.0 mol, particularly 1.2 to 4.0 mol, per effective aldehyde group with respect to 1 mol of the melamine compound.

  Water is most preferred as the medium used in step (a). A mixed solution in which a part of water is replaced with an organic solvent soluble in water can also be used. In this case, an organic solvent capable of dissolving the initial condensate of melamine resin is preferably selected. Preferred organic solvents include alcohols such as methanol, ethanol, isopropanol and propanol, ethers such as dioxane, tetrahydrofuran and 1,2-dimethoxyethane, and polar solvents such as dimethylformamide and dimethyl sulfoxide.

  A preferable dispersion stabilizer is the same as that of the styrene type. That is, the inorganic particles include colloidal silica, aluminum oxide, acid value zirconium, zinc antimonate, titanium oxide, and mixtures thereof having a volume average primary particle diameter of 6 to 32 nm, preferably 7 to 17 nm. Preferably used.

  Next, the toner, toner base, and toner particle dispersion will be described.

  The toner of the present invention is obtained by mixing composite crosslinked particles with a toner base. The toner base is obtained by solid-liquid separation of the toner particle dispersion and drying.

  The toner base used in the present invention preferably has a volume average particle diameter of 2 to 8 μm and an average circularity of 0.951 to 0.988.

  The average value of the volume average particle diameter and the circularity of the toner and the toner base is the same even if the composite cross-linked particles are mixed with the toner base, because the composite cross-linked particles have a small particle size and are not affected.

  The average value of the volume average particle diameter and the circularity of the toner is within this range, so that the image resolution is high and a high transfer rate is obtained, and the toner is fused, that is, spent on a frictional charging member such as a carrier. And a very high developer life can be obtained.

  The toner base is not particularly limited as long as the average value of the particle diameter and the circularity can be obtained, and it can be obtained from a toner particle dispersion prepared by any method such as a suspension polymerization method, an emulsion association method, or a dissolution suspension method. Although it can be produced, it is preferable to use a emulsion produced by an emulsion association method that has a sharp particle size distribution, excellent images, and a long developer life.

  Hereinafter, a method for producing a toner particle dispersion by an emulsion association method will be described.

  A method for producing a toner particle dispersion by emulsion polymerization is a method for forming toner particles in an aqueous medium, and is disclosed in, for example, JP-A-2002-351142.

  In addition, the resin particles disclosed in JP-A-5-265252, JP-A-6-329947, and JP-A-9-15904 are salted out / fused in an aqueous medium to produce a toner particle dispersion. A method can be mentioned.

  Specifically, after resin particles are dispersed in water using an emulsifier, a coagulant having a critical coagulation concentration or higher is added for salting out, and at the same time, heat fusion is performed at or above the glass transition temperature of the formed polymer itself. Gradually grow the particle size while forming fused particles, add a large amount of water to stop the particle size growth when the target particle size is reached, and further smooth the particle surface while heating and stirring The shape is controlled to prepare a toner particle dispersion. Here, a solvent that is infinitely soluble in water, such as alcohol, may be added simultaneously with the flocculant.

  Examples of the aqueous medium include, but are not particularly limited to, water, methanol, ethanol, isopropanol, butanol, 2-methyl-2-butanol, acetone, methyl ethyl ketone, tetrahydrofuran, or a mixture thereof. . A suitable toner can be selected from among these.

  Examples of the organic solvent include toluene, xylene, or a mixture thereof, but are not particularly limited.

  Examples of the toner production method include a dry method in which the toner base and the composite crosslinked particle powder are mixed, and a wet method in which the toner particle dispersion and the composite crosslinked particle dispersion are mixed.

  The method for producing a toner by a dry method is a method in which a toner base obtained from a toner particle dispersion and a powder obtained by drying composite cross-linked particles are mixed by a dry method.

  The method for producing a toner by a wet method is a method for producing a toner by mixing a toner particle dispersion and a composite crosslinked particle dispersion by a wet method, followed by solid-liquid separation, and drying the obtained solid content.

  In the dry method and the wet method, the dry method is preferable from the viewpoint of manufacturing cost and environmental load reduction.

The toner of the present invention can be used as it is for a non-magnetic one component or mixed with a magnetic carrier for a two-component developer.
The

<Developer>
A developer using the toner of the present invention for two components will be described.

  The two-component developer according to the present invention can be formed by mixing the toner of the present invention with a magnetic carrier having a carrier core material particle surface coated with a resin. The mixing ratio is preferably such that the toner concentration is 1 to 15% by mass relative to the carrier.

<Photoconductor>
The toner of the present invention can be used in various toner image forming apparatuses. In particular, it is effective for long-term print creation exceeding 1 million sheets, and a small-sized image forming apparatus having a large impact on the toner in the developing unit, particularly a high-speed image forming apparatus that creates 50 or more prints per minute. It has been confirmed that it is expressed more effectively.

  The photoconductor used when forming an image using the toner according to the present invention is not particularly limited, but is described in JP-A Nos. 2003-202785 and 2003-208036. Even a photoreceptor having a surface protective layer called a so-called silicon hard coat layer, which has an organic photosensitive layer on a conductive support and a surface protective layer formed by condensing an organic silicon compound on the organic photosensitive layer. It has been confirmed that the effects can be fully expressed.

  That is, the toner according to the present invention is added as an external additive when an image is formed over a long period exceeding 1 million sheets even if it is used in an image forming apparatus using a photoconductor having such a hard surface. It has been confirmed that the composite crosslinked particles can continuously form a stable image without causing deformation such as flattening.

  The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited to these examples.

<Production of composite crosslinked particles>
<Preparation of composite crosslinked particle 1>
1 g of azobis-N, N-dimethylvaleronitrile is dissolved in a mixed solution of 60 g of styrene, 34 g of methyl methacrylate and 10 g of divinylbenzene, 0.5 g of sodium dodecylbenzenesulfonate, 15 g of colloidal silica having a volume average primary particle diameter of 16 nm ( In addition to 500 g of water containing 2 g of aluminum oxide dispersion liquid (corresponding to solid content) having a volume average primary particle size of 13 nm (corresponding to solid content), the mixture was stirred for 15 minutes at 8000 rpm using “CLEARMIX” (MTechnics). “Primary suspension 1” having a volume average particle diameter of about 1.5 μm was prepared.

  Next, a “collision processor (LD-500)” was connected to “Nanomizer LA-33” (manufactured by Nanomizer), and “Primary Suspension 1” was passed once under a pressure of 70 MPa. A secondary suspension 1 ”was prepared.

  This “secondary suspension 1” is put into a polymerization vessel equipped with a stirrer and a thermometer, and is subjected to suspension polymerization at 50 ° C. for 8 hours under mild stirring conditions to obtain “a dispersion of composite crosslinked particles 1”. It was.

  After adjusting the pH of the “dispersion of composite crosslinked particles 1” to 4.0, 5 g of n-hexyltrimethoxysilane was added and held for 4 hours, and then the pH was adjusted by adding 2N aqueous sodium hydroxide solution. The mixture was adjusted to 6.5, and further stirred and held for 2 hours, followed by solid-liquid separation and water washing to prepare “cake of composite crosslinked particles 1”. The “composite crosslinked particle 1 cake” was dried under reduced pressure, and then the agglomerate was pulverized with an air jet pulverizer to produce “composite crosslinked particle 1”.

  The obtained “composite crosslinked particles 1” had a volume average particle diameter of 233 nm, the amount of the water-soluble component was 97 ppm, and no aldehyde was detected. When this "composite crosslinked particle 1" was observed with a scanning electron microscope (SEM) as it was, and observed with a transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) in a sliced state, It was confirmed that the particles had a spherical shape and silica fine particles were unevenly distributed near the particle surface.

<Preparation of composite crosslinked particle 2>
0.5 g of 2,2′-azobisisobutyronitrile was dissolved in a mixed solution composed of 90 g of styrene and 10 g of divinylbenzene to obtain a polymerizable monomer component. Separately, 15 g of colloidal silica having a volume average primary particle diameter of 7 nm (corresponding to solid content) and anatase type titanium oxide dispersion having a volume average primary particle diameter of 20 nm are dissolved in an aqueous solution in which 0.2 g of sodium dodecylbenzenesulfonate is dissolved in 500 g of water. 2 g of liquid (corresponding to a solid-liquid component) was added, and the above polymerizable monomer component was mixed with this aqueous solution, and the mixture was stirred for 15 minutes at 8000 rpm using “CLEARMIX” (manufactured by M Technique Co., Ltd.). A W emulsion was obtained. The droplet diameter in the obtained O / W emulsion was about 0.4 μm.

  This emulsion was put in a 1 L reaction vessel equipped with a stirrer and a thermometer, and polymerized at 80 ° C. with stirring in a nitrogen stream to obtain “a dispersion of composite crosslinked particles 2”. In this example, the concentration of the sodium dodecylbenzenesulfonate aqueous solution at the time of preparing the emulsion was 0.2% by mass, and the concentration of sodium dodecylbenzenesulfonate in the polymerization reaction system was 0.04% by mass.

  The liquid temperature of the “dispersion of composite crosslinked particles 2” is cooled to 40 ° C., the pH is adjusted to 4.0, 5 g of n-hexyltrimethoxysilane is added, and the mixture is stirred and held for 4 hours. An aqueous sodium oxide solution was added to adjust the pH to 6.5, and the mixture was further stirred and maintained for 2 hours, and then separated into solid and liquid and washed with water to prepare “Cake of Composite Crosslinked Particles 2”. The “cake of composite crosslinked particles 2” was dried under reduced pressure, and then the agglomerates were pulverized by an air jet type pulverizer to produce “composite crosslinked particles 2”.

The volume average particle diameter of the obtained "complex crosslinked particles 2" 143 n m, the amount of water-soluble components are 721Ppm, aldehyde was detected. When this "composite crosslinked particle 2" was observed with a scanning electron microscope (SEM) as it was, and observed with a transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) in a sliced state, It was confirmed that the particles had a spherical shape and silica fine particles were unevenly distributed near the particle surface.

<Preparation of composite crosslinked particles 3>
In a 2 L reaction flask equipped with a stirrer, a reflux condenser and a thermometer, 50.0 g of melamine, 96.5 g of 37% acetaldehyde, 24.7 g of colloidal silica having a volume average primary particle size of 8 nm (corresponding to solid content), volume average primary Zinc antimonate having a particle size of 10 nm (corresponding to a solid content) of 2.0 g and 720 g of water were charged, and 25% aqueous ammonia was added to adjust the pH to 8.5 to prepare a mixed solution. The temperature of the mixture was increased while stirring, and the temperature was kept at 80 ° C., and the mixture was reacted for 30 minutes to prepare an aqueous solution of an initial condensate of melamine resin. The molecular weight of the melamine resin at this time was 280 as measured by gel permeation chromatography (GPC method) (polystyrene conversion).

  Next, while maintaining the temperature at 70 ° C., a 10% by mass aqueous solution of dodecylbenzenesulfonic acid was added to the obtained aqueous solution of the initial condensate to adjust the pH to 7.0. About 20 minutes later, the reaction system became clouded and cured melamine resin particles were precipitated. Thereafter, the temperature was raised to 90 ° C. and the curing reaction was continued for 24 hours to obtain “a dispersion of composite crosslinked particles 3”.

  After the liquid temperature of the “dispersion of composite crosslinked particles 3” is cooled to 40 ° C., the pH is adjusted to 4.0, 5 g of n-hexyltrimethoxysilane is added, and the mixture is stirred and held for 4 hours. An aqueous sodium oxide solution was added to adjust the pH to 6.5, and the mixture was further stirred and held for 2 hours, and then separated into solid and liquid and washed with water to prepare “Cake of Composite Crosslinked Particles 3”. The “cake of composite crosslinked particles 3” was first blown with steam and then dried under reduced pressure, and then the aggregate was crushed with a fine pulverizer using an air jet method to produce “composite crosslinked particles 3”.

The obtained volume average particle diameter of the "composite crosslinked particles 3" 210 n m, the amount of water-soluble components is 670 ppm, the aldehyde was detected 70 ppm. When this “composite crosslinked particle 3” was observed with a scanning electron microscope (SEM) as it was, and observed with a transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) in a sliced state, It was confirmed that the particles had a spherical shape and silica fine particles were unevenly distributed near the particle surface.

<Preparation of Composite Crosslinked Particle 4>
In Example 3, after the cured melamine resin particles were precipitated, the temperature was raised to 90 ° C. and the curing reaction was continued for 3 hours to obtain “a dispersion of composite crosslinked particles 4”. In addition, “composite crosslinked particles 4” were produced by changing the drying under reduced pressure to atmospheric drying.

The obtained volume average particle diameter of the "composite crosslinked particles 4" 230 n m, the amount of water-soluble components are 746Ppm, the amount of aldehyde was 136 ppm.

  When this "composite crosslinked particle 4" was observed with a scanning electron microscope (SEM) as it was, and with a transmission electron microscope-energy-dispersive X-ray analysis (TEM-EDX) in the state of a slice piece, It was confirmed that the particles had a spherical shape and silica fine particles were unevenly distributed near the particle surface.

<Preparation of composite particle 1>
Hydrophobic oxidation in which 100 g of non-crosslinked styrene / acrylic organic particles (electrical resistance 6.6 × 10 ¹³ Ω · cm) with a volume average particle size of 1.0 μm were treated with tetraoctyl titanate on the surface with a volume primary particle size of 15 nm 40 g of titanium was added and mixed with a turbula mixer.

  Next, a “hybridizer” (manufactured by Nara Machinery Co., Ltd.) with a modified pulverizer was treated for 3 minutes at a peripheral speed of 100 m / sec to produce “composite particles 1” in which titanium oxide was fixed on the surface of organic particles. did.

  The obtained “Composite 1 Particle 1” had a volume average particle diameter of 1.0 μm, the amount of the water-soluble component was 566 ppm, and no formaldehyde was detected.

<Manufacture of toner base>
<Preparation of Toner Particle Dispersion 1 (Example of Emulsion Association Method)>
(Preparation of latex (1HML))
(1) Preparation of core particles (first stage polymerization)
An anionic surfactant in a 5000 ml separable flask equipped with a stirrer, temperature sensor, condenser, and nitrogen inlet
C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na
A surfactant solution (aqueous medium) in which 7.08 g was dissolved in 3010 g of ion-exchanged water was charged, and the temperature in the flask was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

To this surfactant solution, an initiator solution prepared by dissolving 9.2 g of a polymerization initiator (potassium persulfate: KPS) in 200 g of ion-exchanged water was added, the temperature was adjusted to 75 ° C., and then 70.1 g of styrene, n -A monomer mixture consisting of 19.9 g of butyl acrylate and 10.9 g of methacrylic acid was added dropwise over 1 hour, and this system was polymerized by heating and stirring at 75 ° C for 2 hours (first stage polymerization). And a latex (a dispersion of resin particles made of a high molecular weight resin) was prepared. This is referred to as “latex (1H)”.
(2) Formation of intermediate layer (second stage polymerization)
In a flask equipped with a stirrer, a monomer mixture consisting of 105.6 g of styrene, 30.0 g of n-butyl acrylate, 6.2 g of methacrylic acid, and 5.6 g of n-octyl-3-mercaptopropionic acid ester was separated. As a mold, 98.0 g of a compound represented by the following formula (hereinafter referred to as “Exemplary Compound (19)”) was added, heated to 90 ° C. and dissolved to prepare a monomer solution.

Exemplary compound (19)
_{CH 3 (CH 2) 20 COOCH} 2 C (CH 2 OCO (CH 2) 20 CH 3) 3
On the other hand, a surfactant solution obtained by dissolving 1.6 g of an anionic surfactant (the above formula (101)) in 2700 ml of ion-exchanged water is heated to 98 ° C., and a dispersion of core particles is added to the surfactant solution. After adding 28 g of the above-mentioned “latex (1H)” in terms of solid content, a mechanical disperser “CLEARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path is used to The monomer solution was mixed and dispersed for 8 hours to prepare a dispersion (emulsion) containing emulsified particles (oil droplets) having a dispersed particle diameter of 284 nm.

  Next, an initiator solution prepared by dissolving 5.1 g of a polymerization initiator (KPS) in 240 ml of ion-exchanged water and 750 ml of ion-exchanged water are added to this dispersion (emulsion). Polymerization (second-stage polymerization) was performed by heating and stirring over time to obtain a latex (a dispersion of composite cross-linked particles having a structure in which the surface of resin particles made of a high molecular weight resin was covered with an intermediate molecular weight resin). This is referred to as “latex (1HM)”.

The “latex (1HM)” was dried and observed with a scanning electron microscope. As a result, particles (400 to 1000 nm) mainly composed of the exemplified compound (19) not surrounded by the latex were observed.
(3) Formation of outer layer (third stage polymerization)
An initiator solution in which 7.4 g of a polymerization initiator (KPS) is dissolved in 200 ml of ion-exchanged water is added to the “latex (1HM)” obtained as described above, and styrene is added at a temperature of 80 ° C. A monomer mixed liquid consisting of 300 g, 95 g of n-butyl acrylate, 15.3 g of methacrylic acid, and 10.4 g of n-octyl-3-mercaptopropionic acid ester was added dropwise over 1 hour. After completion of the dropwise addition, polymerization (third stage polymerization) was performed by heating and stirring for 2 hours, followed by cooling to 28 ° C. and latex (a central part made of a high molecular weight resin, an intermediate layer made of an intermediate molecular weight resin, A dispersion of composite crosslinked particles) having an outer layer made of a molecular weight resin and containing the exemplary compound (19) in the intermediate layer. This latex is referred to as “latex (1HML)”.

The composite crosslinked particles constituting this “latex (1HML)” have peak molecular weights (mass) at 138,000, 80,000 and 13,000, and the volume average particle diameter of the composite crosslinked particles is It was 122 nm.
(Preparation of toner particle dispersion)
Anionic surfactant (sodium dodecyl sulfate) 59.0 g was dissolved in 1600 ml of ion-exchanged water with stirring, and 420.0 g of “CI Pigment Blue 15: 3” was gradually added while stirring this solution. A “colorant particle dispersion” was prepared by dispersion treatment using “CLEARMIX” (manufactured by M Technique Co., Ltd.).

  Reaction in which 420.7 g of “latex (1HML)” (converted to solid content), 900 g of ion-exchanged water, and 166 g of “dispersion of colorant particles” were attached with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device. It stirred in the container (four necked flask). After adjusting the temperature in the container to 30 ° C., 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 8.

  Next, an aqueous solution obtained by dissolving 12.1 g of magnesium chloride hexahydrate in 1000 ml of ion-exchanged water was added at 30 ° C. over 10 minutes with stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 90 ° C. over 6 to 60 minutes to produce associated particles. In this state, the particle diameter of the associated particles was measured with “Coulter Counter TA-II” (manufactured by Coulter Counter Co., Ltd.). When the volume average particle diameter reached 6.4 μm, 80.4 g of sodium chloride was ionized. An aqueous solution dissolved in 1000 ml of exchange water was added to stop the particle growth, and further, the particles were fused by heating and stirring at a liquid temperature of 98 ° C. for 2 hours as an aging treatment.

  Thereafter, the mixture was cooled to 30 ° C., hydrochloric acid was added to adjust the pH to 4.5, and “Toner Particle Dispersion 1” was produced.

  The “toner particle dispersion 1” produced above was subjected to solid-liquid separation with a rotating cylindrical dehydrator “MARK III Model No. 60 × 40” (Matsumoto Machine Co., Ltd.) equipped with a filter to form a toner cake. The toner cake was washed with water in a rotary cylindrical dehydrator, and then the toner cake was scraped off by a scraper inserted into the machine, discharged from the machine, and stored in a container. Thereafter, the toner cake was supplied little by little to “Flash Jet Dryer” (manufactured by Seishin Enterprise Co., Ltd.) and dried until the water content of the toner particles became 0.5% by mass to produce the toner base “toner particle A”. .

The volume average particle diameter of “toner particles A” was 6 μm, and the average value of circularity was 0.970.
<Production of toner>
<Preparation of Toners 1-4, 6, 7>
100 parts by mass of the “toner particles A”, 1.0 parts by mass of “composite crosslinked particles 1 to 4” and “composite particles 1”, and fumed silica (volume average primary particle diameter 16 nm) treated with cyclic silazane 0 After adding 6 parts by mass and mixing with “Henschel mixer” (manufactured by Mitsui Miike Chemical Co., Ltd.), coarse particles are removed using a sieve having a mesh opening of 45 μm to produce “Toners 1 to 4, 6”. It was set as “Examples 1 to 4” and “Comparative Example 1”.

  Mixing with a Henschel mixer was carried out for 25 minutes while cooling the stirring blade peripheral speed to 40 m / sec and the toner temperature to 35 to 37 ° C.

  “Toner 7” to which no composite crosslinked particles were added was designated as “Comparative Example 2”.

<Preparation of Toner 5>
Add 5 g of n-hexyltrimethoxysilane to the “dispersion of composite cross-linked particles 3”, hold the mixture with stirring for 4 hours, add 2N aqueous sodium hydroxide solution to adjust the pH to 6.5, and hold the mixture with stirring for another 2 hours. The resulting liquid (5.0 parts by mass (solid content: 1.0 part by mass)) was mixed with “Toner Particle Dispersion 1” (corresponding to a solid content of 100 parts by mass) and n-hexyltrimethoxy was added to the toner particle surface. Composite crosslinked particles 3 hydrophobized with silane were adhered. This liquid was subjected to solid-liquid separation and dried to produce “Toner 5” containing “composite crosslinked particles 3” which was hydrophobized, and was designated as “Example 5”.

  The amount of the water-soluble component and the amount of aldehyde were not measurable because there was no separation method between the toner and the composite crosslinked particles.

  Table 1 shows the toner base used to produce the toner, the types of composite crosslinked particles, and the like.

<< Preparation of developer >>
Each of the “Toners 1 to 7” produced above is mixed with a ferrite carrier having a volume average particle diameter of 60 μm coated with a silicone resin so that the toner concentration is 6% by mass to produce “Developers 1 to 7”. did.
<< Production of photoconductor >>
A coating layer was formed by applying the following coating solution onto a cylindrical conductive support having a length of 380 mm and a diameter of 60 mm, to produce “Photoreceptor P1”.
<Underlayer>
Titanium chelate compound (TC-750, manufactured by Matsumoto Pharmaceutical) 30g
Silane coupling agent (KBM-503, Shin-Etsu Chemical Co., Ltd.) 17g
150 ml of 2-propanol
The coating solution was applied on a cylindrical conductive support so as to have a film thickness of 0.5 μm.
<Charge generation layer>
60 g of Y-type titanyl phthalocyanine (a titanyl phthalocyanine having a maximum peak at 27.2 ° with a Bragg angle 2 θ (± 0.2 °) of Cu-Kα characteristic X-ray diffraction spectrum measurement)
Silicone-modified butyral resin X-40-1211M: 700 g manufactured by Shin-Etsu Chemical Co., Ltd.
2-butanone 2000ml
Were mixed for 10 hours using a sand mill to prepare a charge generation layer coating solution. This coating solution was applied onto the undercoat layer by a dip coating method to form a charge generation layer having a thickness of 0.2 μm.
<Charge transport layer>
Charge transport material N- (4-methylphenyl) -N- {4- (β-phenylstyryl) phenyl} -p-toluidine 225 g
Polycarbonate (viscosity average molecular weight 30,000) 300g
Dichloromethane 2000ml
Were mixed and dissolved to prepare a charge transport layer coating solution. This coating solution was applied onto the charge generation layer by a dip coating method to form a charge transport layer having a dry film thickness of 20 μm.
<Surface protective layer>
150g of methyltrimethoxysilane
Dimethyldimethoxysilane 30g
Reactive charge transport compound 15g
Polyvinylidene fluoride particles (volume average particle size 0.2 μm) 10 g
2-propanol 75g
3% acetic acid 5g
Were mixed to prepare a coating solution for the surface protective layer. A resin layer having a thickness of 2 μm was formed on the charge transport layer on the charge transport layer using a circular amount-regulating coating apparatus, followed by heat curing at 120 ° C. for 1 hour to form a surface protective layer of siloxane resin.

<Evaluation>
<Live-action evaluation>
The toner prepared above was evaluated for the following evaluation items. A developer corresponding to each toner was used.

  As an evaluation machine, a commercially available multifunction machine “Sitoos 7085” (manufactured by Konica Minolta Business Technologies, Inc.) employing an electrophotographic method was used. The above-mentioned “photosensitive member P1” was set as the photosensitive member, and the printing conditions were set as follows.

(Print conditions)
Charging conditions Charger; Scorotron charger, initial charge potential of -750V
Exposure condition Set the exposure amount so that the potential of the exposed area is -50V, and the image area ratio is 5%.
Development condition DC bias; -550V
Amount of toner adhering to the maximum exposed area: 0.4 mg / cm ²
The transfer electrode used was a corotron corona charging method. In the fixing device, iron is used as the core metal, and the surface is coated with PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) having a thickness of 25 μm and the surface roughness Ra is 0.8 μm. A roller was used. The nip width is 3.8 mm, and the linear velocity is 550 mm / sec. The fixing temperature was controlled by the surface temperature of the heating roller, and was set to a set temperature of 175 ° C.

  For printing, the above “toners 1 to 7” and “developers 1 to 7” were sequentially set in the above-mentioned multi-function machine, and 5 million sheets were continuously printed under conditions of normal temperature and humidity (25 ° C., 55% RH).

<Developer life>
The quality of the printed image was visually evaluated to determine whether it can be used.

(Evaluation criteria)
◎: Image quality does not deteriorate up to 5 million prints, life is very long and good ○: Image quality deteriorates with 2 to 4 million prints, but life is long and good △: Image quality is less than 1 to 2 million prints Deteriorated and life is slightly short ×: Image quality deteriorates when printing is less than 1 million sheets, and life is short.

<Deformation and fusion of composite cross-linked particles>
The carrier surface after printing 2.5 million sheets was observed at a magnification of 10,000 using a microscope, and the degree of deformation of the composite crosslinked particles adhering to the carrier surface and the fusion of the composite crosslinked particles to the carrier surface were evaluated. . The charge amount is a value measured with a suction-type charge amount measuring device.

(Evaluation criteria)
A: Deformation in composite cross-linked particles, presence of composite cross-linked particles fused to carrier is not recognized. O: Deformation is not observed in composite cross-linked particles, and composite cross-linked particles fused to carrier are 2 to 10 μm square area. Although there are 10 particles, charging inhibition does not occur and there is no practical problem. X: Deformation is observed in the composite cross-linked particles, and 30 or more composite cross-linked particles fused to the carrier are present in an area of 10 μm square. Decreased by 10 μC / g or more compared to the initial stage, and toner scattering and fogging occurred.

<Charge amount leak at high temperature and high humidity>
The charge amount of the developer was measured with a suction-type charge meter before and after being left for 24 hours at high temperature and high humidity (30 ° C., 85% RH). The difference between the charge amount measured before leaving the developer and the charge amount measured after leaving at high temperature and high humidity was evaluated as a charge amount leak.

(Evaluation criteria)
A: Charge amount leak is less than 3.0 μC / g and good ○: Charge amount leak is 3.0 to 4.5 μC / g and almost good Δ: Charge amount leak is 4.5 to 6.0 μC / g *: Charge amount leakage is larger than 6.0 μC / g, which is poor.

<Toner filming on photoreceptor surface and amount of wear on coating layer>
After printing 5 million sheets, the toner filming on the surface of the photoreceptor and the amount of wear of the photoreceptor coating layer (the amount thinned by scraping) were evaluated.

  If there is toner filming, it is easy to cause image fogging, and if the coating layer of the photoconductor is polished and thinned by toner, it is likely to cause sensitivity abnormality, which is not preferable.

  The toner filming was evaluated by observing the surface of the photoreceptor with a microscope and evaluating the degree of filming. The amount of depletion was determined from the difference in film thickness before printing and after printing 5 million sheets using a film thickness measuring device “EDDY560C” (manufactured by HELMUT FISCHER GMBTE CO).

(Evaluation criteria)
A: There is no toner filming. In addition, the amount of wear of the coating layer is less than 3 μm, and excellent ○: No toner filming is present. In addition, the amount of wear of the coating layer is less than 6 μm and good. Δ: A little toner filming is observed, but no fog occurs in the printed image. The amount of wear of the coating layer is less than 10 μm and is practical.

  X: Toner filming is observed, and fog occurs in the printed image. The amount of wear of the coating layer is 10 μm or more, and fogging occurs due to a decrease in sensitivity. It is necessary to replace the photoconductor during printing 5 million sheets.

<Transfer rate>
The transfer rate was evaluated using a multifunction machine modified to remove the toner recycling mechanism of the multifunction machine and collect the residual toner. The transfer rate was obtained by calculating the amount of residual toner when the toner adhesion amount of a character image having a pixel rate of 5% (A4 size) was set to 20.00 mg per print, and calculating from that value. The smaller the transfer residual toner, the higher the transfer rate, the deterioration of the developer is suppressed, and a high density image is obtained, which is preferable.

A: Transfer rate is 99.7% or higher and excellent B: Transfer rate is 99.0 to 99.6%, good B: Transfer rate is 95.1 to 98.9%, practical use ×: Transfer rate is poor at 95.0% or less. Table 2 shows developer life, deformation and fusion of composite cross-linked particles, leakage of charge amount at high temperature and high humidity, toner filming on the photoreceptor surface, and amount of depletion of the coating layer. The evaluation results of the transfer rate are shown.

  As shown in Table 2, “Examples 1 to 5”, which are toners prepared using the composite crosslinked particles of the present invention, have an excellent effect as compared with “Comparative Examples 1 and 2”.

Claims (8)

A toner obtained by mixing toner particles containing at least a resin and a colorant and composite crosslinked particles ,
The composite crosslinked particles are obtained by polymerizing or condensing a polymerizable monomer in the presence of inorganic particles in an aqueous medium, and having inorganic particles present on or near the surface thereof. Toner. The toner according to claim 1, wherein the toner particles constituting the toner have a volume average particle diameter of 2 to 8 μm and an average value of circularity of 0.951 to 0.988. The toner according to claim 1, wherein the inorganic particles are any one of colloidal silica, titanium oxide, and aluminum oxide. The composite cross-linked particles are obtained by forming a polymerizable monomer by polymerization or condensation reaction in the presence of inorganic particles, and then hydrophobizing. The toner according to any one of the above. The toner according to claim 1, wherein the composite cross-linked particles contain 0.05 to 746 ppm of a water-soluble component, and the water-soluble component contains less than 138 ppm of aldehydes. The toner particles constituting the toner have a volume average particle diameter of 2 to 8 μm and an average value of circularity of 0.951 to 0.988.
The composite crosslinked particles contained in the toner are formed by polymerizing or condensing a polymerizable monomer in the presence of inorganic particles in an aqueous medium, and contain inorganic particles on or near the surface of the composite crosslinked particles. The toner according to claim 1, further comprising 0.05 to 746 ppm of a water-soluble component containing aldehydes of less than 138 ppm. A toner monomer dispersion obtained by a wet method is solid-liquid separated and dried, and a polymerizable monomer is formed by polymerization or condensation reaction in the presence of inorganic particles in an aqueous medium in a toner base. A toner production method comprising producing a toner by dry mixing composite cross-linked particles containing inorganic particles on or near the surface of particles. Composite comprising inorganic particles on or near the surface of particles formed by polymerizing or condensing a polymerizable monomer in an aqueous medium in the presence of inorganic particles in a toner particle dispersion obtained by a wet method A toner production method comprising producing a toner by mixing crosslinked particles.