JP2006235383A - Toner for electrostatic latent image development, electrostatic latent image developer, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner for electrostatic latent image development, an electrostatic latent image developer and an image forming method for obtaining favorable fluidity and aggregation property of the toner independent from the use environment without decreasing picture quality and for stably keeping favorable fixing property for a long time. <P>SOLUTION: The toner for electrostatic latent image development comprises toner particles containing at least a binder resin and a colorant and an external additive, wherein the external additive comprises inorganic particles which are hollow inorganic particles and contain a release agent having the melting point of 40°C or higher and less than 160°C inside the hollow particles, and/or resin particles which are hollow resin particles having 60 mass% or more gel fraction and contain a release agent having the melting point of 40°C or higher and less than 160°C inside the hollow particles. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrostatic latent image developing toner used for developing an electrostatic latent image in electrophotography and electrostatic recording, an electrostatic latent image developer using the same, and an image forming method.

  In electrophotography, an electrostatic latent image formed on a photoconductor (latent image carrier) is developed with a toner containing a colorant, and the resulting toner image is transferred onto a transfer material, which is then heated. The latent image carrier is cleaned to form an electrostatic latent image again.

  The dry developer used in such an electrophotographic method includes a one-component developer that uses a toner in which a colorant and the like are blended in a binder resin, and a two-component developer in which a carrier is mixed with the toner. Broadly divided. On the other hand, since the latter half of the 1980s, the market for electrophotography has been strongly demanded for miniaturization and high functionality with the key to digitization, and in particular, high-quality quality close to high-quality printing and silver halide photography is desired for full color image quality.

As means for achieving high image quality, digitization processing is indispensable, and as an effect of digitization related to such image quality, it is mentioned that complex image processing can be performed at high speed. This makes it possible to control the character image and the photographic image separately, and the reproducibility of the quality of both images is greatly improved compared to the analog technology. In particular, for photographic images, gradation correction and color correction are possible, and this is advantageous compared to analog in terms of gradation characteristics, definition, sharpness, color reproduction, and graininess.
However, on the other hand, it is necessary to faithfully create a latent image created by an optical system as an image output, and as a toner, an activity aiming at faithful reproduction is being accelerated as the particle size is increasingly reduced. It is difficult to stably obtain high image quality only by reducing the particle size of toner, and improvement of basic characteristics in development, transfer, and fixing characteristics is more important.

  In particular, in a color image, three or four color toners are superimposed to form an image. Therefore, if any one of these toners exhibits different characteristics from the initial stage in terms of development, transfer, and fixing, or performance different from other colors, it may cause a decrease in color reproduction, or a deterioration in image quality such as a deterioration in graininess and color unevenness. Become. In order to maintain a stable high-quality image over time as in the initial stage, it is important how to stably control the characteristics of each toner.

  As a toner that maintains such a high-quality image stably for a long period of time, for example, a toner having a volume average particle diameter of 7 to 14 μm has been proposed (see, for example, Patent Document 1). Have been proposed having a sharp particle size distribution (see, for example, Patent Document 2).

  By the way, generally, when the particle size of the toner is reduced, the fluidity is deteriorated or the surface area of the toner per unit mass is increased, so that the amount of fine particles called external additives added to the toner surface is increased. In general, inorganic fine powder, high glass transition temperature (Tg) or crosslinkable organic fine particles are used as the fine particles, and the above-described improvement in fluidity, chargeability and transferability are achieved. It has been found that the fixing property is deteriorated when the amount of the external additive added is increased correspondingly.

  As a method for fixing a toner image, there are a heating roll method and a heating fixing method using a heating film. Currently, the heating roll method is widely used because of its high thermal efficiency and high-speed fixing, but it has a short standby time from when the power is turned on until it can be used. From the merits of being able to reduce the amount, a heat fixing method (belt fixing method, film fixing method) using a heating film is being adopted.

  In fixing a color image, the surface of the heat-fixing member and the molten toner image are in contact with each other under pressure, so that a part of the toner image adheres to the surface of the heating member, and the adhered toner is re-transferred and copied. Therefore, a so-called offset phenomenon that contaminates the water tends to occur, and a method of supplying a release agent (a release liquid such as silicone oil) is used. However, this method is extremely effective in preventing the toner offset phenomenon, but the releasing agent (offset preventing agent) is heated to evaporate to give an unpleasant odor, or supply the releasing agent. In recent years, a fixing device that does not use release oil has been adopted due to a review of toner resin design and release agent resin design.

  Further, for the purpose of improving the fixability, various studies have been made on the molecular weight and Tg of the binder resin constituting the toner bulk, and the type and amount of the release agent. For example, for a release agent, a method for limiting the melt viscosity of the release agent (see, for example, Patent Documents 3 and 4), a method for limiting the diameter of the release agent domain and the abundance of the release agent on the toner surface ( For example, a method for limiting the shape of the release agent domain (see, for example, Patent Document 6) has been proposed.

  Further, various proposals have been made on the heat fixing method using a heating film from the viewpoint of more stable fixing properties and energy saving. For example, a method for limiting the viscosity of a binder resin and a release agent, which are constituent components of toner, for the purpose of further suppressing the offset phenomenon of fixing has been proposed (for example, see Patent Document 7).

  However, all of the above proposals still had points to be improved. For example, in order to obtain a release effect by adding a release agent to the toner, control of the release agent domain diameter in the binder (binder resin) is indispensable. When the ratio of the release agent present in the vicinity increases, there arises a problem that the cohesiveness and fluidity deteriorate. Further, if the dispersion diameter is too small, sufficient releasability cannot be obtained. Furthermore, the industrial stability of controlling the appropriate dispersion diameter of the release agent is not sufficient, and in particular, in the case of toner manufactured by a pulverization method, the release agent exposed on the surface increases. Thus, at present, the examination of the toner bulk material has a certain limit, and it is difficult to cope with the deterioration of the fixing property due to the toner having a smaller diameter.

  As a proposal outside the toner bulk, a toner is disclosed in which an inorganic compound surface-treated with low molecular weight polyethylene is added to the toner surface (see, for example, Patent Document 8), but this proposal does not mention fixability. . A proposal using an external additive that is uniformly coated with a release agent is also disclosed (see, for example, Patent Document 9). However, when the release agent is exposed on the surface of the toner as described above, or when the release agent surface-treated particles are used as an external additive, there is a concern about the deterioration of toner cohesion and fluidity. Further, even when the release agent itself is externally added to the toner, the cohesion and fluidity of the toner cannot be denied.

Further, in order to improve the fluidity, chargeability, and transferability of the toner, it has been proposed to make the toner shape close to a spherical shape (see, for example, Patent Document 10). However, only with the spheroidization of the toner, deterioration of the cohesiveness and fluidity due to the release agent present in the vicinity of the toner particle surface when the release agent is internally added or the release agent applied as the external additive. Improvement is inadequate.
JP-A-62-103675 Japanese Patent Laid-Open No. 2-13259 JP-A-3-260659 Japanese Patent Laid-Open No. 3-122660 Japanese Unexamined Patent Publication No. 7-84398 JP-A-6-161145 Japanese Patent Laid-Open No. 3-122661 JP-A-5-165250 JP 2004-109666 A Japanese Patent Laid-Open No. 62-184469

The present invention has been made in view of the above circumstances of the prior art.
That is, it is an object of the present invention to obtain a good toner fluidity and cohesiveness regardless of the use environment without degrading the image quality, and to ensure a good fixability over a long period of time. It is an object to provide a latent image developing toner, an electrostatic latent image developer, and an image forming method.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1> An electrostatic latent image developing toner comprising toner particles containing at least a binder resin and a colorant and an external additive,
The external additive contains inorganic particles containing a release agent having a melting point of 40 ° C. or higher and lower than 160 ° C. inside the hollow inorganic particles, and / or a melting point inside the hollow resin particles having a gel fraction of 60% by mass or higher. Is an electrostatic latent image developing toner containing resin particles containing a release agent having a temperature of 40 ° C. or higher and lower than 160 ° C.

<2> The electrostatic latent image developing toner according to <1>, wherein the void ratio of the hollow inorganic particles and the hollow resin particles is in the range of 40 to 80%.

<3> The electrostatic latent image developing toner according to <1> or <2>, wherein the inorganic particles and the resin particles are spherical.

<4> The external additive includes two or more kinds of fine particles having different number average primary particle diameters, and includes at least the number average primary particle diameters of 5 nm or more and less than 30 nm together with the inorganic particles and / or resin particles. >-<3> The electrostatic latent image developing toner according to any one of the above.

<5> The electrostatic latent image developing toner according to any one of <1> to <4>, wherein the volume average particle diameter is in a range of 3 to 10 μm.

<6> An electrostatic latent image developer including the electrostatic latent image developing toner according to any one of <1> to <5>.

<7> At least a charging step for charging the latent image carrier, an electrostatic latent image forming step for exposing the surface of the latent image carrier to form an electrostatic latent image, and a developer containing the electrostatic latent image with toner. In a method of forming an image using a toner image, the image forming method includes a developing step for forming a toner image, a transfer step for transferring the formed toner image to the surface of the transfer target, and a fixing step for fixing the transferred toner image to the transfer target.
In the image forming method, the developer is the electrostatic latent image developer according to <6>.

<8> The image forming method according to <7>, wherein the fixing step is a fixing step in which substantially no release agent is supplied.

  According to the present invention, an electrostatic latent image capable of obtaining good toner fluidity and agglomeration regardless of the use environment without degrading image quality, and further ensuring good fixability over a long period of time. A developing toner, an electrostatic latent image developer, and an image forming method can be provided.

  Hereinafter, the present invention will be described in detail. First, an electrostatic latent image developing toner (hereinafter sometimes referred to as “toner”) and an electrostatic latent image developer used in the present invention will be described, and then the entire configuration of the image forming method of the present invention. Will be explained.

<Toner for electrostatic latent image development>
The electrostatic latent image developing toner of the present invention is an electrostatic latent image developing toner comprising toner particles containing at least a binder resin and a colorant and an external additive, wherein the external additive is hollow inorganic particles. Of the inorganic particles containing a release agent having a melting point of 40 ° C. or more and less than 160 ° C. and / or a hollow resin particle having a gel fraction of 60% by mass or more having a melting point of 40 ° C. or more and less than 160 ° C. It includes resin particles containing a mold agent.

  In the toner of the present invention, a release agent is supported on an external additive so that the release agent is effectively present on the toner surface at the time of fixing. It does not cause problems based on chemicals. That is, as a method for supporting a release agent on an external additive such as inorganic fine particles, the release agent is not supported on the outside of the external additive by coating or the like, but hollow particles made of a shell of the external additive. It has been found that the above problem can be completed by the presence of a release agent in the interior.

  In the present invention, since the release agent is encapsulated in so-called hollow particles, the release agent exposed to the toner surface is in the same state as when a normal external additive is added when added to the toner particles. It is possible to suppress the deterioration of toner cohesiveness and fluidity due to the adhesion. On the other hand, since the hollow particles hold the release agent in fixing, it is possible to prevent deterioration of fixing properties due to the reduction in toner diameter. Furthermore, it is possible to ensure a good fixability of a certain level or more without adding a release agent to the toner particles.

  In particular, when the toner is used for a toner having a shape factor SF1 (described later) in the range of 100 to 140, improvement in developability and transferability can be expected, and higher image quality can be expected. Further, in a toner containing more release agent for the purpose of improving fixability and improving low-temperature fixability than conventional toners, a release agent such as wax existing in the toner particle or in the vicinity of the surface of the blade and the photosensitive member. The release agent in the present invention tends to cause a defect (wax filming) that oozes out and adheres to the surface of the photoreceptor due to the pressure between them, and also contaminates the charging roller etc. that contacts and charges the photoreceptor. When the encapsulated hollow particles are used, the amount of wax contained in the toner particles can be reduced, and the above-described defects can be suppressed.

The configuration of the toner of the present invention will be described below.
The toner of the present invention contains at least a binder resin, a colorant, and an external additive as components, and the external additive contains a release agent having a melting point of 40 ° C. or higher and lower than 160 ° C. inside the hollow particle. It contains at least particles and / or resin particles. Hereinafter, first, inorganic particles and resin particles containing the release agent will be described.

(Inorganic particles, resin particles)
Inorganic particles and resin particles containing a release agent used as the external additive (hereinafter referred to as “release agent-containing particles”) are shells made of inorganic fine particles or resin (hereinafter referred to as “hollow particles”). And a release agent having a specific melting point.
The hollow particles do not depend on organic or inorganic materials.

-Hollow resin particles (hollow particles made of resin)-
Various methods for producing hollow resin particles have been proposed as described below.
For example, by using a dispersion in which a hydrophilic monomer, a crosslinkable monomer, and an oily substance coexist at a certain ratio, and performing suspension polymerization or emulsion polymerization, polymer particles containing the oily substance in the inner pores are obtained. Thereafter, a method of obtaining hollow polymer particles by removing the oily substance; a method of preparing a W / O / W type emulsion and polymerizing monomers of the O layer (see JP-A-60-184004); a swellable core A core / shell particle having a particle size and expanding at a temperature equal to or higher than the Tg of the shell layer to make it hollow (see JP-A-56-32513); a method by two-stage polymerization of polymers having different solubility parameters (specially Japanese Laid-Open Patent Publication No. 60-223873); a polymerizable monomer component containing a crosslinkable monomer and a hydrophilic monomer and an oily substance are finely dispersed in water to form an O / W emulsion. A method of polymerizing monomers to remove oily substances; a method of spraying or emulsifying a liquid resin to form fine particles by suspension and heating and foaming; and a method of hollowing out in a wet process during polymerization granulation; However, the hollow resin particles used in the present invention may be produced by any manufacturing method.

  Specifically, by adjusting the combination and concentration of the emulsifiers used, the particle size of the hollow particles and the porosity described later can be adjusted. In this case, release agent-encapsulating particles (resin particles) can be obtained by allowing a release agent to coexist, and any of these methods may be used.

  The crosslinking monomer of the constituent material of the hollow resin particles that can be used in the present invention is at least one polyfunctional monomer having 2 or more polymerizable double bonds (in particular, divinylbenzene, divinylbiphenyl, divinylnaphthalene, diallylphthalate, At least one selected from the group consisting of triallyl cyanurate, ethylene glycol dimethacrylate and tetraethylene glycol dimethacrylate). Monofunctional monomers include monovinyl aromatic monomers and acrylic monomers. , A vinyl ester monomer, a vinyl ether monomer, a monoolefin monomer, a halogenated olefin monomer, and a diolefin are particularly preferred, but are not limited thereto. Absent.

  When the hollow particles are formed from a resin, the resin particles serve as an external additive, so that the hollow particles themselves need a certain level of strength and hardness. Since the organic resin particles are deformed by themselves and it is difficult to maintain the initial performance for a long time, the hollow resin particles in the present invention need to have a gel fraction of 60% by mass or more. .

  When the gel fraction is less than 60% by mass, it cannot withstand the stress in the developing device when externally added as a toner.

The gel fraction in the present invention is obtained by adding about 0.3 g of dried resin particles (or hollow resin particles, release agent-containing resin particles) in 30 g of an organic solvent, and vacuum-dissolving an undissolved material in the organic solvent. After drying with a machine, the mass was measured, and the gel fraction (mass%) was calculated by the following formula (1). The organic solvent may be any organic solvent that can dissolve the polymer composed of the monomer, and examples thereof include tetrahydrofuran.
Gel fraction (mass%) = (mass of hollow resin particles not dissolved in THF / mass of all hollow resin particles) × 100 Formula (1)
Moreover, when measuring about a resin particle, it can obtain | require by making a "hollow resin particle" into the "resin particle" in the said Formula (1), and subtracting a mold release agent content rate from the obtained value.

-Hollow inorganic particles (hollow particles made of inorganic particles)-
In producing the hollow inorganic particles, known materials can be used as the inorganic particles, such as silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, Clay, mica, wollastonite, diatomaceous earth, cerium chloride, bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, silicon nitride, calcium carbonate, magnesium carbonate, calcium phosphate, etc. it can.
Among these, it is more preferable to use silica, calcium carbonate, or the like because of its low specific gravity and low refractive index.

  As a method for producing hollow inorganic particles, a method of obtaining hollow inorganic particles by adding a treatment with a specific alcohol to a sol-gel method based on the Stover method; alkyl silicate, water, alcohol, acid amides, A process prepared by hydrolysis and condensation in the presence of at least one selected from diols and diol half ethers, a water-soluble polymer and a catalyst; a metal oxide is reacted with a base catalyst in water and an alcohol solvent; To form a hollow airgel microsphere by injecting an inert gas into the droplet of the alcogel to form a hollow alcogel microsphere, and then drying the alcogel microsphere supercritically. A method obtained by hydrolysis and condensation in the presence of a polymer and a catalyst; Precipitated onto the core material other than iodide, and then a method of preparing by removing the core material; and the like are disclosed.

  The hollow inorganic particles of the present invention can be produced by any of the above methods. In this case, the release agent-encapsulating particles can be obtained by allowing the release agent to coexist. Any of the above production methods may be used.

  The number average particle diameter of the hollow particles (hollow resin particles, hollow inorganic particles) produced as described above is preferably in the range of 50 nm to 3 μm. In particular, the number average particle diameter of the hollow particles is desirably in the range of 70 nm to 300 nm. If the number average particle diameter of the hollow particles is less than 50 nm, the amount of the release agent that can be contained inside the hollow particles is limited and stable production is industrially difficult. It will be difficult to provide. If the particle size of the hollow particles exceeds 3 μm, it may be difficult to supply the release agent uniformly during fixing depending on the image.

  In the present invention, as described above, the porosity in the hollow particles is preferably in the range of 40 to 80%. When the porosity is larger than 80%, the hollow particles are likely to be collapsed due to stress in the developing device, and it may be difficult to stably supply to the fixing unit. When the void ratio of the hollow particles is smaller than 40%, the hollow particles are not sufficiently collapsed at the time of fixing, and it is difficult to obtain the fixing characteristics stably for a long time.

In addition, the said porosity can be calculated | required by following formula (2).
Porosity (%) = (radius of hollow portion / radius of hollow particles) ³ × 100 Formula (2)
Further, when there are a plurality of hollow portions of the hollow particles instead of one, the void ratio (%) is calculated as follows: Porosity (%) = Σ (radius of hollow portion of hollow particles) ³ / (radius of hollow particles ( 1/2) ³ × 100 of the particle diameter.

-Release agent-
The release agent to be contained in the hollow particles is not particularly limited as long as the melting point is 40 ° C. or higher and lower than 160 ° C. For example, paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and components thereof Derivatives, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, silicone oil and the like.

  The derivative includes an oxide, a polymer with a vinyl monomer, and a graft modified product. In addition to the above, alcohol waxes, fatty acid waxes, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides and the like can also be used. Other known materials can also be used.

As described above, in the present invention, the melting point of the release agent needs to be 40 ° C. or higher and lower than 160 ° C. If the melting point is less than 40 ° C., it becomes difficult to produce inorganic particles and resin particles, which is not preferable. When the melting point is 160 ° C. or higher, the release agent does not dissolve at the time of fixing, and good fixability cannot be obtained.
The melting point of the release agent is preferably in the range of 40 to 160 ° C, more preferably in the range of 60 to 110 ° C.

  As a method of encapsulating the release agent in the hollow particles, the pressure difference between the inside and outside of the hollow part is utilized by reducing the pressure inside the hollow part under reduced pressure and contacting the release agent in a pressurized state. Then, the mold release agent is introduced in the process of making the release agent soaked from the micropores on the wall surface, or making the release agent into an emulsion and putting the release agent into the O layer of the W / O / W emulsion to produce hollow particles. A method of encapsulating (in the case of resin particles), a method of producing a hollow inorganic particle by performing a sol-gel reaction in a release agent-dispersed aqueous solution, or a method of forming an oxide film on a release agent fine particle by dipping or spraying ( In the case of inorganic particles), it is not limited thereto.

  The content of the release agent is preferably in the range of 3 to 30 parts by mass, more preferably in the range of 3 to 15 parts by mass with respect to 100 parts by mass of the hollow particles. If the amount of the release agent is less than 3 parts by mass, a large amount of hollow resin particles and / or hollow inorganic particles must be externally added in order to obtain a sufficient fixing property. In some cases, there may be problems such as adhesion of heat and scratches on the heating roll. If the amount of the release agent added is more than 30 parts by mass, it is difficult to control the release agent to be included, and the release agent is likely to be exposed on the surface, which may adversely affect the fluidity and cohesiveness of the toner.

  The release agent-containing hollow inorganic particles and the resin particles may be subjected to a surface treatment as necessary. The surface treatment is not limited, and examples thereof include a treatment using a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, various silicone oils, fatty acids, fatty acid metal salts, and the like. Particularly preferably, a silane coupling agent and various silicone oils can be used. The surface treatment amount is not limited, but is preferably in the range of 2.0 to 30% by mass in the treated inorganic particles and resin particles. If the amount is less than 2.0% by mass, the surface treatment effect cannot be obtained, and if it exceeds 30% by mass, aggregated particles are generated.

  In the present invention, two or more kinds of fine particles having different number average primary particle diameters are preferably used as external additives, and at least the number average primary particle diameter is 5 nm to 30 nm together with the inorganic particles and / or resin particles. It is preferable to contain less than fine particles. More preferably, it contains fine particles having a number average primary particle size of 5 nm or more and less than 30 nm and fine particles having a number average particle size of 30 to 70 nm.

  By setting the combination of the number average primary particle diameters of the fine particles used as the external additive in the above range, the fluidity and fixability of the small particle diameter toner can be controlled in a balanced manner.

  The number average particle size (primary particle size) of each particle contained in the external additive is the same as the outer diameter (number average particle size) of the release agent-encapsulated particles and hollow particles, but is diluted with ethanol. The sample is dried on a carbon grid for a scanning electron microscope (TEM), followed by TEM observation (50000 times), the image is printed, 50 samples are extracted as primary particles, and circular particles corresponding to the image area are extracted. The outer diameter (average value of major axis and minor axis) was taken as the outer diameter (number average particle diameter).

  The addition amount of the external additive particles having a smaller number average primary particle diameter is preferably in the range of 0.3 to 3 parts by mass, and 0.5 to 1.5 parts by mass with respect to 100 parts by mass of the toner particles. More preferably, it is the range. If the amount is less than 0.3 part by mass, sufficient fluidity may not be obtained. If the amount is more than 3 parts by mass, the toner charge maintaining property may be deteriorated.

  As particles for external additives other than the release agent-containing particles that can be used in the present invention, known particles can be used, for example, silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, Strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, cerium chloride, bengara, chromium oxide, cerium oxide, antimony trioxide, magnesium oxide, zirconium oxide, silicon carbide, silicon nitride, calcium carbonate , Magnesium carbonate, calcium phosphate and the like. Also, known materials such as silicone resin fine particles and styrene-methyl methacrylate copolymer can be used. It can also be used after surface treatment.

  Furthermore, you may add various additives as needed. Examples of these additives include other fluidizing agents, cleaning aids such as polystyrene fine particles, polymethyl methacrylate fine particles, and polyvinylidene fluoride fine particles, or transfer aids. Monodispersed spherical silica having a specific gravity in the range of 1.2 to 1.9 and a number average primary particle size in the range of 80 to 300 nm may be added. The amount of the monodispersed spherical silica added is preferably in the range of 0.5 to 5 parts by mass, more preferably in the range of 1 to 3 parts by mass with respect to 100 parts by mass of the toner particles. If the amount is less than 0.5 parts by mass, sufficient transferability cannot be obtained. If the amount is more than 5 parts by mass, toner fluidity and chargeability may be inevitably deteriorated. It can also be used after surface treatment.

In the present invention, the processing method of the external additive including the release agent-encapsulating particles to the toner particles is not particularly limited, and is performed by mixing each fine particle with the toner particles. Mixing can be performed by a known mixer such as a V-type blender, a Henschel mixer, or a ready-mixer.
Further, as an external addition method to the toner, the two or more types of external additive fine particles may be added and mixed simultaneously. In addition, it does not matter even if it goes through a sieving process after external addition mixing.

  The toner for developing an electrostatic latent image of the present invention contains at least a binder resin and a colorant, and the volume average particle diameter D50 is preferably in the range of 3 to 10 μm, more preferably in the range of 3 to 7 μm. preferable.

  The volume average particle diameter D50 can be measured, for example, using a Coulter counter [TA-II] type (manufactured by Beckman Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

  Further, by using the toner having a shape factor SF1 of 100 to 140, an image with high development, transferability, and high image quality can be obtained. The toner used in the present invention is not particularly limited by the production method as long as it satisfies the above shape index and particle size, and a known method can be used.

The toner shape factor SF1 is obtained by taking toner particles dispersed on a slide glass or an optical microscope image of the toner into a Luzex image analyzer through a video camera, and obtaining the maximum length and projected area of 50 or more toners. It is obtained by calculating by the equation (3) and obtaining the average value.
SF1 = (ML ² / A) × (π / 4) × 100 (3)
In the above formula (3), ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.

  The toner can be produced, for example, by mechanically mixing particles obtained by a kneading and pulverizing method in which a binder resin, a colorant and, if necessary, a release agent, a charge control agent, and the like are kneaded, pulverized, and classified. A method of changing the shape by impact force or thermal energy, emulsion polymerization of a polymerizable monomer of a binder resin, formation of a dispersion, a colorant, a release agent, and a charge control agent as required Emulsion polymerization aggregation method to obtain toner particles by mixing and aggregating and heat-fusing with dispersion, polymerizable monomer, colorant, release agent for obtaining binder resin, and charge control if necessary Suspension polymerization in which a solution such as an agent is suspended in an aqueous solvent for polymerization, a binder resin, a colorant, a release agent, and if necessary, a solution such as a charge control agent is suspended in an aqueous solvent. A granulating dissolution suspension method or the like can be used.

  In addition, a manufacturing method may be performed in which the toner particles obtained by the above method are used as a core, and aggregated particles are further adhered and heat-fused to have a core-shell structure. Among the above, a wet process toner that can easily obtain a spherical toner is preferably used, and toner particles obtained by an emulsion polymerization aggregation method are preferably used in that toner particles having a sharp distribution can be obtained. By combining with these toner particles, the effect becomes stable.

  Binder resins used include styrenes such as styrene and chlorostyrene; monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; Α-methylene aliphatic monocarboxylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate Homopolymers and copolymers such as vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone, vinyl isopropenyl ketone; In particular, typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene-anhydrous. Mention may be made of maleic acid copolymers, polyethylene, polypropylene and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, paraffin wax and the like.

  Further, from the viewpoint of excellent sharp melt property at the time of fixing and obtaining low temperature fixability and high glossiness in a fixed image, it may be used in combination with a crystalline resin.

  The crystalline resin is not particularly limited as long as it is a resin having crystallinity, and specifically includes a crystalline polyester resin, a crystalline vinyl resin, and the like. A crystalline polyester resin is preferred from the viewpoint of chargeability and adjustment of the melting point within a preferred range. An aliphatic crystalline polyester resin having an appropriate melting point is more preferable.

In addition, toner colorants include magnetic powders such as magnetite and ferrite, carbon black, aniline blue, caryl blue, chrome yellow, ultramarine blue, DuPont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, and malachite green oxa. Rate, lamp black, rose bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 17, C.I. I. Pigment blue 15: 1, C.I. I. Pigment Blue 15: 3 can be exemplified as a representative example.
The amount of the colorant added is in the range of 3 to 50 parts by mass with respect to 100 parts by mass of the binder resin.

Typical examples of the release agent include low molecular weight polyethylene, low molecular weight polypropylene, Fischer tropic wax, montan wax, carnauba wax, rice wax, and candelilla wax.
The addition amount of the release agent is preferably in the range of 3 to 20% by mass with respect to the whole toner particles. When the addition amount is less than 3% by mass, it becomes difficult to obtain a stable fixability for a long period of time even when the release agent-encapsulating particles of the present invention are used. On the other hand, when the addition amount is more than 20% by mass, the fluidity may be extremely deteriorated and the charge distribution may be very wide.

  In addition, a charge control agent may be added to the electrostatic latent image developing toner of the present invention as necessary. As the charge control agent, known ones can be used, and an azo metal complex compound, a metal complex compound of salicylic acid, a resin type charge control agent containing a polar group, and the like can be used. When the toner is manufactured by a wet manufacturing method, it is preferable to use a material that is difficult to dissolve in water in terms of controlling ionic strength and reducing wastewater contamination. The toner in the present invention may be either a magnetic toner containing a magnetic material or a non-magnetic toner containing no magnetic material.

<Electrostatic latent image developer>
The electrostatic latent image developer of the present invention is not particularly limited except that it contains the toner for developing an electrostatic latent image of the present invention, and can have an appropriate component composition depending on the purpose. The electrostatic latent image developer of the present invention becomes a one-component electrostatic image developer when the electrostatic latent image developing toner is used alone, and a two-component electrostatic latent image developer when used in combination with a carrier. It becomes an image developer.

  As the carrier, a resin-coated carrier having a resin coating layer in which a conductive material is dispersed and contained in a matrix resin on the core surface is preferably used. In particular, when spherical toner is used, the packing property is inevitably increased at the conveyance restriction portion in the developing device, and accordingly, a strong force is applied not only to the toner surface but also to the carrier. Therefore, by containing a conductive material dispersed in the resin coating layer of the carrier, even if the resin coating layer is peeled off, it is possible to achieve high image quality over the long term without greatly changing the volume resistivity. Can do.

  Examples of the matrix resin include polyethylene, polypropylene, polystyrene, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid. Examples include copolymers, straight silicone resins composed of organosiloxane bonds or modified products thereof, fluororesins, polyesters, polyurethanes, polycarbonates, phenol resins, amino resins, melamine resins, benzoguanamine resins, urea resins, amide resins, epoxy resins, etc. However, it is not limited to these.

Examples of the conductive material include metals such as gold, silver and copper, and titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate, tin oxide, and carbon black. Is not to be done.
The content of the conductive material is preferably in the range of 1 to 50 parts by mass and more preferably in the range of 3 to 20 parts by mass with respect to 100 parts by mass of the matrix resin.

Examples of the core material of the carrier include magnetic metals such as iron, nickel, and cobalt, magnetic oxides such as ferrite and magnetite, and glass beads. However, in order to adjust the volume resistivity using the magnetic brush method, a magnetic material is used. It is preferable that
The volume average particle diameter of the core material is generally in the range of 10 to 500 μm, preferably in the range of 30 to 100 μm, as the volume average particle diameter.

  As a method for forming the resin coating layer on the surface of the carrier core material, an immersion method in which the carrier core material is immersed in a coating layer forming solution containing a matrix resin, a conductive material and a solvent, or a coating layer forming solution is used as the carrier. Spray method for spraying on the surface of the core material, fluidized bed method for spraying the coating layer forming solution in a state where the carrier core material is suspended by fluid air, mixing the carrier core material and the coating layer forming solution in a kneader coater, A kneader coater method for removing the solvent may be mentioned.

The solvent used in the coating layer forming solution is not particularly limited as long as it dissolves the matrix resin. For example, aromatic hydrocarbons such as toluene and xylene, and ketones such as acetone and methyl ethyl ketone. , Ethers such as tetrahydrofuran and dioxane can be used.
The average film thickness of the resin coating layer is usually in the range of 0.1 to 10 μm, but in the present invention, it is in the range of 0.5 to 3 μm in order to develop a stable volume resistivity of the carrier over time. It is preferable.

The volume resistivity of the carrier formed as described above is 10 ⁶ to 10 ¹⁴ in the range of 10 ³ to 10 ⁴ V / cm corresponding to the upper and lower limits of a normal development contrast potential in order to achieve high image quality. A range of Ωcm is preferable. If the volume specific resistance of the carrier is less than 10 ⁶ Ωcm, the reproducibility of fine lines is poor, and toner fog is likely to occur on the background due to charge injection. Further, if the volume resistivity of the carrier is larger than 10 ¹⁴ Ωcm, reproduction of black solid and halftone becomes worse. In addition, the amount of carriers transferred to the photoconductor increases, and the photoconductor may be easily damaged. Further, as the electrostatic brush, a resin containing a conductive filler such as carbon black or a metal oxide or a fibrous substance coated on the surface can be used, but it is not limited thereto.

  The electrostatic latent image developer of the present invention is produced by mixing the above-described toner and carrier. The mixing ratio (mass ratio) of the toner and the carrier in the developer is preferably in the range of toner: carrier = 1: 100 to 20: 100, preferably in the range of 3: 100 to 12: 100. It is more preferable.

<Image forming method>
The image forming method of the present invention includes a charging step for uniformly charging a latent image carrier, a latent image forming step for exposing the charged latent image carrier surface to form an electrostatic latent image, and the electrostatic latent image. Developing means for developing the toner image into a toner image using a developer containing toner, a transfer step for transferring the formed toner image to the transfer target, and a fixing step means for fixing the transferred toner image on the surface of the recording target. And the developer is the electrostatic latent image developer of the present invention.

  That is, in the image forming method of the present invention, as an image forming apparatus for forming an image, a latent image carrier, a charging unit for charging the surface of the latent image carrier, and a latent image on the surface of the charged latent image carrier. An image forming apparatus comprising: a latent image forming unit that forms an image; a developing unit that develops the electrostatic latent image using toner; and a transfer unit that transfers the toner image onto a recording material (recording medium). The toner of the present invention described above is used as the toner. In particular, in full-color image formation in the image forming method of the present invention, from the viewpoint of paper versatility and high image quality, each color toner image is temporarily transferred to the surface of an intermediate transfer belt or intermediate transfer drum as an intermediate transfer member. After being laminated, it is preferable to transfer the laminated color toner images onto the surface of a recording material such as paper at a time. Therefore, the transfer target in the present invention includes both the intermediate transfer member and the recording material.

In the image forming apparatus used in the image forming method of the present invention, each component is not particularly limited, other than those defined in the present invention. For example, any known components such as a latent image carrier, an intermediate transfer belt (or an intermediate transfer drum), and a charger can be used.
However, the charging means is preferably a roll charging type charger in that environmental conservation due to the reduction of ozone generation can be realized at a high level.

  Also, known heat fixing rolls and / or fixing films in the fixing device can be used. For heat fixing rolls, the surface of the heating roll is a silicone rubber or fluororesin layer with excellent releasability from toner, PET (polyethylene terephthalate), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) with excellent heat resistance , PTFE (polytetrafluoroethylene), polyimide, polyamide, or other polymer sheet is preferable.

  In the fixing film, the film between the heating body and the pressure member is preferably a heat-resistant sheet having a thickness of 1 to 20 μm, and the material thereof is the above-described polymer sheet having excellent heat resistance, such as aluminum. It consists of a metal sheet, a polymer sheet and a metal sheet. More preferably, it is preferable to have a release layer so that the surface of the heat-resistant sheet can be released more smoothly. Further, if necessary, the electrostatic influence on the toner before fixing may be adjusted by controlling the electrical resistance.

Further, in the fixing step, by using the toner of the present invention, a stable fixing performance can be obtained without substantially supplying a release agent (silicone oil, etc.) to the surface of the fixing member (roll, belt, etc.). Became possible. Here, “substantially no release agent is supplied” means that the supply amount of the release agent to the fixing member per unit area is 0.1 μl / cm ² or less.

  The supply amount of the release agent can be measured as follows. That is, when a normal paper (for example, a copy paper manufactured by Fuji Xerox Co., Ltd., trade name J paper) used in a general copying machine is passed through a fixing member supplied with a release agent on the surface, the normal paper is used. A release agent adheres to the paper. The attached release agent is extracted using a Soxhlet extractor. Here, hexane is used as the solvent. By quantifying the amount of the release agent contained in the hexane with an atomic absorption analyzer, the amount of the release agent adhering to the plain paper can be quantified. This amount is defined as the amount of release agent supplied to the fixing member.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In the description of the toner and the carrier, “part” means “part by weight” and “%” means “mass%” unless otherwise specified.

<Method for measuring physical properties of each sample>
In the toner, carrier, and electrostatic latent image developer, each measurement was performed by the following method.
(Outer diameter (number average particle diameter) / inner diameter of release agent-containing resin particles, release agent-containing inorganic particles, and other external additives)
The external additive particles are diluted with ethanol, dried on a carbon grid for a transmission electron microscope (TEM: JEM-1010, manufactured by JEOL Datum Co., Ltd.), and subjected to TEM observation (50000 times). 50 samples were arbitrarily extracted using the primary particles as a sample after printing, and the outer diameter (average value of major axis and minor axis: obtained by approximating as a circle) and inner diameter (major axis) corresponding to the image area And the average value of the minor axis) were defined as the outer diameter (number average particle diameter) and inner diameter of the resin particles, respectively.

(Releasing agent content)
In the TEM observation image of the resin particles and the like, 1/2 of the area of the releasing agent part (major axis / minor axis) is considered as the radius of the releasing agent-containing part, and approximated to a circle to be the area occupied by the releasing agent . This was divided by the area occupied by the hollow particles (the area obtained by approximating the circle with the outer diameter of the hollow particles as the radius) and multiplied by 100 to obtain the release agent content (%).

(Gel fraction)
About 0.3 g of the dried hollow resin particles are weighed as a sample, put into 30 g of an organic solvent, and stirred for 60 minutes. Next, after centrifuging at a rotational speed of 10,000 rpm for 5 minutes, the supernatant liquid from which the lysate in the organic solvent has been extracted is removed. Next, after the undissolved material in the organic solvent is dried with a vacuum dryer, its mass is measured, and the gel fraction (mass%) is calculated by the above formula (1). The organic solvent may be any organic solvent that can dissolve the polymer composed of the monomer, and examples thereof include tetrahydrofuran.

(Porosity)
The outer diameter and inner diameter determined by the TEM observation were determined from the above formula (2) as the radius of the hollow particles and the radius of the hollow portion, respectively.

(Measurement method of molecular weight and molecular weight distribution of resin)
The molecular weight and molecular weight distribution of the resin and resin fine particles in the present invention were measured using gel permeation chromatography (GPC). GPC uses HLC-8120GPC, SC-8020 (manufactured by Tosoh Corporation), and column uses two TSKgel and SuperHM-H (manufactured by Tosoh Corporation, 6.0 mm ID × 15 cm). THF (tetrahydrofuran) was used. As experimental conditions, the sample concentration was 0.5 mass%, the flow rate was 0.6 ml / min, the sample injection amount was 10 μl, the measurement temperature was 40 ° C., and the experiment was performed using an IR detector. The calibration curve is “polystylen standard sample TSK standard” manufactured by Tosoh Corporation: “A-500”, “F-1”, “F-10”, “F-80”, “F-380”, “A-2500”. ”,“ F-4 ”,“ F-40 ”,“ F-128 ”, and“ F-700 ”. The data collection interval in sample analysis was 300 ms.

(Resin, glass transition point of resin fine particles, release agent melting point)
The glass transition point of the resin fine particles and the melting point of the release agent were determined by measurement using a differential scanning calorimeter (manufactured by Shimadzu Corporation: DSC-50) under a temperature rising rate of 10 ° C./min. The glass transition point was the temperature at the intersection of the extension line of the base line and the rising line in the endothermic part, and the melting point was the temperature at the apex of the endothermic peak.

(Toner shape factor SF1)
The toner shape factor SF1 means a value calculated by the following equation (3). In the case of a true sphere, SF1 = 100. The shape factor SF1 is obtained by taking toner particles dispersed on a slide glass or an optical microscope image of the toner into a Luzex image analyzer through a video camera, and obtaining the maximum length and projected area of 50 or more toners. ) And obtaining the average value.
SF1 = (ML ² / A) × (π / 4) × 100 (3)
In the above formula (3), ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.

(Volume average particle diameter of toner)
The toner particle size distribution measurement in the present invention will be described. A Coulter counter TA-II type (manufactured by Beckman-Coulter) was used as the measuring apparatus, and ISOTON-II (manufactured by Beckman-Coulter) was used as the electrolyte.

  As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate, as a dispersant. This was added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of particles of 2 to 60 μm is measured using the Coulter counter TA-II with an aperture diameter of 100 μm. Volume average distribution and number average distribution were determined. The number of particles to be measured was 50,000.

(Carrier resistance)
As shown in FIG. 1, the measurement sample 53 is sandwiched between the lower electrode 54 and the upper electrode 52 with a thickness H, the thickness is measured with a dial gauge while pressing from above, and the electrical resistance of the measurement sample 53 is measured by a high voltage ohmmeter. Measured at 55. Specifically, a measurement disk was produced by applying a pressure of 500 kg / cm ² to a sample of specific titanium oxide with a molding machine. Next, the surface of the disk was cleaned with a brush, sandwiched between the upper electrode 52 and the lower electrode 54 in the cell, and the thickness was measured with a dial gauge. Next, a voltage was applied and the current value was read to determine the volume resistivity.
The carrier sample was filled in the lower electrode 54 having a diameter of 100 mm, the upper electrode 52 was set, a load of 3.43 kg was applied from above, and the thickness was measured with a dial gauge. Next, a voltage was applied and the current value was read to determine the volume resistivity.

<Preparation of release agent-containing particles>
(Release-encapsulating inorganic particles (A))
10% purified carnauba wax (melting point: 82 ° C., manufactured by Toa Kasei Co., Ltd.) aqueous dispersion (dispersing agent) in an aqueous sodium silicate solution obtained by diluting 300 parts of silica (SiO ₂ concentration: 29%) with 90 parts of pure water 100 parts of 0.5 pph sodium dodecylbenzenesulfonate) was added and stirred at high speed to prepare a dispersion. This dispersion was put into a solution obtained by dissolving 4 parts of sorbitan monooleate in 960 parts of trichlorotrifluoroethane, and emulsified with a homomixer to obtain a W / O type emulsion.

  The emulsion was neutralized with an acid to gel the silica component, and the slurry after separating the trichlorotrifluoroethane was filtered, and the cake-like solid was washed and dried. This reaction product was dried at 120 ° C. to obtain a powder, and the powder was further baked at 150 ° C. to obtain silica particles containing a release agent (release agent-containing inorganic particles (A)).

  The number average primary particle diameter (= outer diameter) of the inorganic particles (A) is 0.1 μm, the inner diameter is 0.08 μm, the porosity is about 50%, the release agent content is about 40%, and the sphericity is 0. 4.

(Releasing agent-containing inorganic particles (B))
In a 2000 ml glass round bottom flask equipped with a stirrer and a thermometer, 300 parts of an aqueous calcium carbonate solution (calcium carbonate concentration: 1 mol / l) and a 2% ethyl acetate solution of polyoxyethylene (degree of polymerization n = 10) lauryl ether were added. 100 parts were added and stirred at high speed to prepare an oil-in-water emulsion. Next, this was added to 1500 parts of a 3% ethyl acetate solution of polyoxyethylene lauryl ether and stirred at high speed to prepare an oil-in-water oil-in-water emulsion. The oil-in-water emulsion in oil thus obtained was reacted by adding 300 parts of 1 mol / l ammonium sulfate and stirring for 5 hours.

  The reaction product liquid was dried at 200 ° C. to obtain a powder, and the powder was fired at 600 ° C. to obtain hollow inorganic particles. The number average primary particle diameter (= outer diameter) of the hollow particles was 0.07 μm, the inner diameter was 0.03 μm, and the porosity was about 80%.

  20 parts of these hollow inorganic particles were heated to 200 ° C., and impregnated with 50 parts of polywax 725 (melting point: 103 ° C., manufactured by Toyo Petrolite Co., Ltd.) that was heated and melted all day and night. What filtered this immersion liquid was dried at 120 degreeC, and obtained the powder, and also the powder was baked at 150 degreeC, and the release agent inclusion inorganic particle (B) containing a wax was obtained. The release agent content of the release agent-containing inorganic particles (B) was about 60%.

(Releasing agent-containing inorganic particles C)
In the production of the release agent-encapsulating inorganic particles (B), instead of impregnating the polywax 725 which is heated and melted by heating the hollow particles (B) to 200 ° C, the hollow particles (B) are heated to 40 ° C and heated and melted. Release agent-containing inorganic particles (C) were obtained in the same manner except that wax 230-2 (melting point: 27 to 37 ° C., manufactured by Kao Corporation) was used. The release agent content was about 40%. The surface exposure of the wax was large, and it was present as an aggregate when observed by TEM (number average particle size: 0.3 μm).

(Release-encapsulating resin particles (A))
As a dispersion stabilizer, 20 parts of an aqueous solution obtained by dissolving 0.1 part of polyvinyl alcohol (polymerization degree 1700, saponification degree: 88%) in water is mixed with divinylbiphenyl as a mixture of a crosslinkable monomer and a monofunctional monomer. A mixture consisting of 51.8%, ethyl vinyl biphenyl 23.4%, methyl vinyl biphenyl 6.3%, vinyl biphenyl 5.8% and other non-polymerizable components (diethyl biphenyl, ethyl biphenyl, etc.) 12.7% 0. 1 part, 25% polyethylene wax (PE130, melting point: 130 ° C., manufactured by Mitsui Chemicals) 0.025 part aqueous dispersion (containing 2.5 pph sodium dodecylbenzenesulfonate), benzoyl peroxide 0.002 as an initiator And 0.25 parts of hexadecane as a solvent were uniformly mixed to suspend the monomer and the like.

  The suspension was carried out using a homogenizer as an apparatus and a stirring speed of 5000 rpm at room temperature. The obtained suspension droplets had an average particle size of about 0.1 μm. Subsequently, the suspension was heated at 70 ° C. with stirring under a nitrogen gas atmosphere, and suspension polymerization was performed for 24 hours. The obtained dispersion was filtered using filter paper to isolate fine particles, and dried under conditions of a temperature of about 70 ° C. and atmospheric pressure, to obtain resin particles (A) containing a release agent.

  The number average primary particle size (= outer diameter) of the release agent-containing resin particles (A) is 0.1 μm, the inner diameter is 0.04 μm, the porosity is about 50%, the release agent content is about 40%, spherical The degree of conversion was 0.90, and the gel fraction was 50% by mass.

(Release-encapsulating resin particles (B))
As a dispersion stabilizer, 15 parts of an aqueous solution obtained by dissolving 0.05 parts of polyvinyl alcohol (polymerization degree 1700, saponification degree: 88%) in water is mixed with divinylbiphenyl as a mixture of a crosslinkable monomer and a monofunctional monomer. A mixture comprising 50.1%, ethyl vinyl biphenyl 22.9%, methyl vinyl biphenyl 6.00%, vinyl biphenyl 5.61% and other non-polymerizable components (diethyl biphenyl, ethyl biphenyl, etc.) 15.4% 25 parts, 25% purified granular carnauba wax (melting point: 82 ° C., manufactured by Toa Kasei Co., Ltd.) 0.07 parts dispersion (containing 2.5 pph sodium dodecylbenzenesulfonate), 0.005 parts benzoyl peroxide as an initiator Then, 0.25 part of hexadecane as a solvent was uniformly mixed to suspend the monomer and the like.

  The suspension was carried out using a homogenizer as an apparatus and a stirring speed of 5000 rpm and room temperature. The obtained suspension droplets had an average particle size of about 2 μm. Next, the suspension was heated at 70 ° C. with stirring under a nitrogen gas atmosphere and subjected to suspension polymerization for 20 hours. The obtained dispersion was filtered using a filter paper, the fine particles were isolated, and dried under conditions of a temperature of about 70 ° C. and an atmospheric pressure to obtain resin particles (B) containing a release agent. .

  The number average primary particle diameter (= outer diameter) of the resin particles (B) is 2 μm, the inner diameter is 1.85 μm, the porosity is about 80%, the release agent content is 70%, and the sphericity is 0.90. In addition, the gel fraction was 60% by mass.

<Preparation of Toner Particle A>
Styrene-n-butyl acrylate resin (Tg = 58 ° C., Mn = 4000, Mw = 25000): 100 parts Carbon black (Mogal L: manufactured by Cabot): 3 parts

  The above mixture is kneaded with an extruder, pulverized with a jet mill, and then dispersed with a wind classifier. Black toner particles (A) having a volume average particle diameter D50 of 5.0 μm and a shape factor SF1 of 148.8. Got.

<Preparation of Toner Particle B>
(Preparation of each dispersion)
-Resin fine particle dispersion (1)-
・ Styrene 370 parts ・ N-butyl acrylate 30 parts ・ Acrylic acid 8 parts ・ Dodecanethiol 24 parts ・ Carbon tetrabromide 4 parts

6 parts of nonionic surfactant (Nonipol 400: manufactured by Sanyo Chemical Co., Ltd.) and anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts dissolved in 550 parts of ion-exchanged water was emulsified and dispersed in a flask, and 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved was added thereto while slowly mixing for 10 minutes. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours.
As a result, a resin fine particle dispersion (1) in which resin particles having a number average particle diameter of 155 nm, a Tg of 59 ° C., and a weight average molecular weight Mw of 12000 was dispersed was obtained.

-Resin fine particle dispersion (2)-
・ Styrene 280 parts ・ n-butyl acrylate 120 parts ・ acrylic acid 8 parts

  6 parts of nonionic surfactant (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.) and anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 12 parts dissolved in 550 parts of ion-exchanged water was emulsified and dispersed in a flask. While slowly mixing for 10 minutes, 50 parts of ion-exchanged water in which 3 parts of ammonium persulfate was dissolved was added thereto. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion (2) was obtained in which resin particles having a number average particle size of 105 nm, a Tg of 53 ° C., and a weight average molecular weight Mw of 550000 were dispersed.

-Colorant dispersion (1)-
・ Carbon black (Mogal L, manufactured by Cabot): 50 parts ・ Nonionic surfactant (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.): 5 parts ・ Ion-exchanged water: 200 parts

  The above components are mixed, dissolved, and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA). Colorant (carbon black) particles having a volume average particle diameter of 250 nm are dispersed. Dispersion liquid (1) was prepared.

-Colorant dispersion (2)-
-Cyan pigment (Pigment Blue 15: 3): 70 parts-Nonionic surfactant (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.): 5 parts-Ion-exchanged water: 200 parts

  A colorant in which the above components are mixed, dissolved, and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA) to disperse colorant (Cyan pigment) particles having a volume average particle diameter of 250 nm. Dispersion liquid (2) was prepared.

-Colorant dispersion (3)-
-Magenta pigment (Pigment Red 122): 70 parts-Nonionic surfactant (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.): 5 parts-Ion-exchanged water: 200 parts

  A colorant in which the above components are mixed, dissolved, and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA) to disperse colorant (Magenta pigment) particles having a volume average particle diameter of 250 nm. Dispersion liquid (2) was prepared.

-Colorant dispersion (4)-
Yellow pigment (Pigment Yellow 180): 100 parts Nonionic surfactant (Nonipol 400, manufactured by Sanyo Chemical Co., Ltd.) 5 parts Ion-exchanged water: 200 parts

  The above components are mixed, dissolved, and dispersed for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA). Colorant (Yellow pigment) particles having a volume average particle diameter of 250 nm are dispersed. Dispersion (4) was prepared.

-Release agent dispersion-
-50 parts of paraffin wax (HNP0190, manufactured by Nippon Seiwa Co., Ltd., melting point: 85 ° C)-5 parts of cationic surfactant (Sanisol B50, manufactured by Kao Corporation)

  The above components are dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50, manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge homogenizer, and the volume average particle diameter is 550 nm. A release agent dispersion liquid in which release agent particles are dispersed was prepared.

(Production of toner particles)
-Toner particle B1-
Resin fine particle dispersion (1): 120 parts Resin fine particle dispersion (2): 80 parts Colorant dispersion (1): 200 parts Release agent dispersion: 40 parts Cationic surfactant (Sanisol B50: Kao Corporation): 1.5 parts

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50, manufactured by IKA), and then heated to 50 ° C. while stirring the inside of the flask in an oil bath for heating. . After maintaining at 45 ° C. for 20 minutes, it was confirmed with an optical microscope that it was confirmed that aggregated particles having a volume average particle diameter of about 4.3 μm were formed. Further, 60 parts of the resin fine particle dispersion (1) was gradually added to the dispersion. The temperature of the heating oil bath was raised to 50 ° C. and held for 30 minutes. When observed with an optical microscope, it was confirmed that adhered particles having a volume average particle diameter of about 5.3 μm were formed.

After adding 3 parts of an anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) to the particle dispersion, the inside of the stainless steel flask is sealed and stirred at 105 ° C. using a magnetic seal. And heated for 4 hours. Then, after cooling, the reaction product was filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles B1 (black).
The volume average particle diameter of the toner particles B1 is 5.8 μm, and the shape factor SF1 is 130.5.

-Toner particle B2-
Toner particles B2 (cyan) were obtained in the same manner as in the preparation of toner particles B1, except that the colorant dispersion (2) was used instead of the colorant dispersion (1).
The volume average particle diameter of the toner particles B2 is 5.5 μm, and the shape factor SF1 is 132.

-Toner particle B3-
Toner particles B3 (magenta) were obtained in the same manner except that the colorant dispersion (3) was used instead of the colorant dispersion (1) in the production of the toner particles B1.
The volume average particle diameter of the toner particles B3 is 5.6 μm, and the shape factor SF1 is 133.5.

-Toner particle B4-
Toner particles B4 (yellow) were obtained in the same manner except that the colorant dispersion (4) was used instead of the colorant dispersion (1) in the production of the toner particles B1.
The volume average particle diameter of the toner particles B4 is 5.4 μm, and the shape factor SF1 is 131.

<Manufacture of carriers>
Ferrite particles (volume average particle size: 50 μm): 100 parts Toluene: 14 parts Styrene-methacrylate copolymer (component ratio: 90/10): 2 parts Carbon black (R330, manufactured by Cabot): 0. 2 parts

First, the above components excluding ferrite particles are stirred with a stirrer for 10 minutes to prepare a dispersed coating solution. Next, the coating solution and ferrite particles are placed in a vacuum degassing type kneader and heated at 60 ° C. for 30 minutes. After stirring, the carrier was obtained by further degassing by depressurization while heating and drying. This carrier had a volume resistivity of 10 ¹¹ Ωcm when an applied electric field of 1000 V / cm was applied.

<Example 1>
(Development of developer)
100 parts of each of the black, cyan, magenta, and yellow toners of toner particles B1, B2, B3, and B4, 3 parts of release agent-containing inorganic particles (A), and hydrophobic titanium oxide (T805) having a number average primary particle diameter of 21 nm , Manufactured by Nippon Aerosil Co., Ltd.) and 1.3 parts of hydrophobic silica (RX50, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle size of 40 nm are mixed at a peripheral speed of 32 m / sec using a Henschel mixer. After blending for 10 minutes, coarse particles were removed using a 45 μm mesh sieve to obtain four types of toner.
Next, 100 parts of the carrier and 5 parts of each toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.

(Evaluation of toner)
−Offset resistance−
The above four types of developers are applied to Docu Center Color 400CP (Fuji Xerox Co., Ltd.) remodeling machine (fixing belt temperature can be freely set and remodeled so that it can be monitored, and the fixing device is oilless specification). The belt surface temperature was changed stepwise, and image formation and fixing of a solid toner image 5 cm long and 4 cm wide were performed on A4 transfer paper at each surface temperature. At this time, the toner adhesion amount was adjusted to 0.5 to 0.7 mg / cm ² .
Observation was made as to whether or not toner smearing occurred in the blank portion of the fixed image at each temperature, and a temperature region where no smearing occurred was defined as a non-offset temperature region.

-Toner cohesion-
At a temperature of 50 ° C., the toner is stored in a packaging container in an open state for 24 hours, and then 20 g of the left toner is placed on a mesh having a 45 μm wide mesh, and the mesh is vibrated for 90 seconds. The percentage of the toner mass remaining on the net to the total toner mass (aggregation rate P) was measured. From the results, the cohesiveness of the toner was judged according to the following criteria (in this evaluation, the cohesiveness evaluation is adopted as a simple index of toner fluidity).
○: P ≦ 10%
Δ: 10% <P ≦ 20%
×: 20% <P

-Toner chargeability-
The charge amount in a high temperature and high humidity and low temperature and low humidity environment is 24 hours for each of the toner and carrier in each atmosphere of a high temperature and high humidity environment (28 ° C., 85% RH) and a low temperature and low humidity environment (10 ° C., 15% RH). The toner and the carrier are collected in a glass bottle with a lid so that the toner concentration is 8%, and stirred by a tumbler in each atmosphere. The stirred developer is subjected to conditions of 25 ° C. and 55% RH. And measured by a blow-off method using TB200 manufactured by Toshiba Corporation.
The above results are summarized in Table 1.

<Example 2>
To 100 parts of toner particles B, 3 parts of release agent-containing inorganic particles (B) and 1.1 parts of hydrophobic silica (RY200, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle diameter of 12 nm are added as external additives. Then, blending was performed at a peripheral speed of 20 m / sec for 5 minutes, and coarse particles were removed using a sieve of 45 μm mesh to obtain a toner. 100 parts of the carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Example 3>
To 100 parts of toner particles B, 3 parts of release agent-encapsulating resin particles (A) are added as an external additive, blended with a Henschel mixer at a peripheral speed of 32 m / sec for 10 minutes, and then the number average primary particle diameter is 21 nm. 1 part of conductive titanium oxide (T805, manufactured by Nippon Aerosil Co., Ltd.) was added, blended at a peripheral speed of 20 m / s for 5 minutes, and coarse particles were removed using a 45 μm mesh sieve to obtain a toner. 100 parts of carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Example 4>
Toner particles A: 3 parts of release agent-encapsulating resin particles (B) are added to 100 parts of an external additive, blended with a Henschel mixer at a peripheral speed of 32 m / sec for 10 minutes, and then the number average primary particle diameter is 12 nm. 1 part of functional silica (RY200, manufactured by Nippon Aerosil Co., Ltd.) and 1 part of hydrophobic silica (RX50, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle size of 40 nm are added and blended at a peripheral speed of 20 m / sec for 5 minutes to form a 45 μm mesh. Coarse particles were removed using a sieve to obtain a toner. 100 parts of carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Comparative Example 1>
To 100 parts of toner particles B, as external additives, 1 part of hydrophobic titanium oxide having a number average primary particle diameter of 21 nm (T805, manufactured by Nippon Aerosil Co., Ltd.) and hydrophobic silica having a volume average primary particle diameter of 40 nm (RX50, Japan) 1.3 parts) (Aerosil Co., Ltd.) and blended for 5 minutes at a peripheral speed of 20 m / s, and coarse particles were removed using a sieve of 45 μm mesh to obtain a toner. 100 parts of the carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Comparative example 2>
Fine particles obtained by heat-sealing (coating) purified granular carnauba wax (melting point: 82 degrees, manufactured by Toa Kasei Co., Ltd.) on hydrophobic silica having a number average primary particle size of 100 nm as an external additive on 100 parts of toner particles B1: 3 parts, 1 part of hydrophobic titanium oxide (T805, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle size of 21 nm, and hydrophobic silica (RX50, manufactured by Nippon Aerosil Co., Ltd.) 1.3 having a number average primary particle size of 40 nm The toner was blended for 5 minutes at a peripheral speed of 20 m / sec, and coarse particles were removed using a 45 μm mesh sieve to obtain a toner. 100 parts of the carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Comparative Example 3>
Toner particles B1: 100 parts, 3 parts of granular carnauba wax fine particles dry-pulverized to a number average particle diameter of 5 μm as external additives, and hydrophobic silica (RY200, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle diameter of 12 nm Add 1 part and 1 part of hydrophobic silica (RX50, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle size of 40 nm, blend for 5 minutes at a peripheral speed of 20 m / sec, and remove coarse particles using a 45 μm mesh sieve. A toner was obtained. 100 parts of the carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Comparative example 4>
To 100 parts of toner particles B, 1 part of hydrophobic silica (RY200, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle diameter of 12 nm and 3 parts of silica particles having a number average primary particle diameter of 0.1 μm are added as external additives. Blending was carried out at a speed of 20 m / sec for 5 minutes, and coarse particles were removed using a sieve of 45 μm mesh to obtain a toner. 100 parts of the carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

<Comparative Example 5>
To 100 parts of toner particles B, 3 parts of release agent-containing inorganic particles (C) and 1.1 parts of hydrophobic silica (RY200, manufactured by Nippon Aerosil Co., Ltd.) having a number average primary particle size of 12 nm are added as external additives. Then, blending was performed at a peripheral speed of 20 m / sec for 5 minutes, and coarse particles were removed using a sieve of 45 μm mesh to obtain a toner. 100 parts of the carrier and 5 parts of the toner were stirred at 40 rpm for 20 minutes using a V-blender, and sieved with a sieve having a 177 μm mesh to obtain a developer.
The same evaluation as in Example 1 was performed using the toner and the developer. The results are summarized in Table 1.

As shown in Table 1, the toner and developer using the inorganic particles and resin particles in the present invention of the examples had good aggregation resistance and chargeability as can be seen from the table. In addition, it can be seen that the temperature range (non-offset temperature range) in which fixing offset does not occur is wide and the suitability for oilless fixing is high.
On the other hand, in the developers that do not use the resin particles or inorganic particles as shown in Comparative Examples 1 and 4, the non-offset temperature region is narrow and the oilless suitability is low. Further, a developer having externally added release agent-coated particles as described in Comparative Example 2, a system having externally added wax as described in Comparative Examples 3 and 5, and a low melting point release agent were contained. In the system in which the release agent-encapsulated particles are externally added, the non-offset temperature range is wide and the oilless suitability is high. However, the cohesiveness is poor, and when used in an actual machine, conveyance failure, transfer failure, contamination of members such as a photoreceptor, deterioration of image quality, and the like occurred.

It is a schematic explanatory drawing for demonstrating the method to measure the volume specific resistance value of a carrier.

Explanation of symbols

52 Upper electrode 53 Measurement sample 54 Lower electrode 55 High voltage resistance meter

Claims (3)

An electrostatic latent image developing toner comprising toner particles containing at least a binder resin and a colorant and an external additive,
The external additive contains inorganic particles containing a release agent having a melting point of 40 ° C. or higher and lower than 160 ° C. inside the hollow inorganic particles, and / or a melting point inside the hollow resin particles having a gel fraction of 60% by mass or higher. A toner for developing an electrostatic latent image, comprising resin particles containing a release agent having a temperature of 40 ° C. or higher and lower than 160 ° C.   An electrostatic latent image developer comprising the electrostatic latent image developing toner according to claim 1. At least a charging step for charging the latent image carrier, an electrostatic latent image forming step for forming an electrostatic latent image by exposing the surface of the latent image carrier, and using a developer containing toner. In an image forming method comprising a developing step for forming a toner image, a transfer step for transferring the formed toner image to the surface of the transfer target, and a fixing step for fixing the transferred toner image to the transfer target.
The image forming method according to claim 2, wherein the developer is the electrostatic latent image developer according to claim 2.

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