JP2000292971A - Toner, its manufacture, developer, and image forming method using this - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner capable of forming an image small in stains on the background and high in image quality. SOLUTION: This toner contains a binder resin and carbon black and a magnetic powder and it has a volume average grain distribution of >=1.25 and a form coefficient of 100-140 and a volume average grain diameter of 2-7 μm, and the toner is manufactured by 2 processes: (1) a process for dispersing the fine resin grains containing at least the binder resin and the carbon black and the magnetic powder into a solvent and forming agglomerated grains containing the binder resin and the carbon black and the magnetic powder, and (2) a process for heating a dispersed fluid containing these aggomerated grains and forming the toner grains comprising the binder resin and the carbon black and the magnetic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner, a method for producing the same, a developer, and an image forming method using the same. And an image forming method.

[0002]

2. Description of the Related Art Methods for visualizing image information via an electrostatic image, such as electrophotography, are currently used in various fields. In electrophotography, usually, an electrostatic charge image is formed on a photoreceptor by a charging and exposure process, and the electrostatic charge image is developed with a developer containing a toner to form a toner image. An image is formed through a transfer step of transferring to a recording medium and a fixing step of fixing the transferred toner image on the recording medium. In recent years, for the purpose of improving the image quality of an image, particularly a full-color image, a reduction in the size of toner particles used for development has been promoted. Reducing the particle size of the toner is effective not only in providing high-definition image quality but also in suppressing toner consumption and reducing the cost required to form one image.

[0003] Various methods for producing a toner having a small particle size have been studied. In addition to the conventional production method using a kneading and pulverizing method, an oil phase composed of a monomer as a raw material of a resin and a colorant is dispersed in an aqueous phase. A method has been proposed in which toner particles are produced by direct polymerization. According to this method, the toner particle size can be reduced, and the release of a release agent (wax) or the like on the surface of the manufactured toner particles can be suppressed, so that the fluidity of the toner is improved. be able to. Also,
It is also advantageous in that toner filming on the developing device and the photoconductor can be suppressed. Further, Japanese Unexamined Patent Publication
Japanese Patent Application Laid-Open Nos. 282752 and 6-250439 propose a method for producing a toner using an emulsion polymerization aggregation method. This method is based on the principle that the toner shape and surface structure can be controlled, and from the principle that an aggregate is formed from finely dispersed particles and the toner particles are manufactured through a process of fusing and coalescing the aggregates. This is an advantageous method for producing a toner having a small diameter.

However, when a two-component developer composed of a small particle size toner and a carrier is actually used, the toner is liable to be scattered outside the image area when being conveyed by a developing roll or the like or during development. Therefore, the background portion of the image tends to be stained. In particular, this phenomenon is remarkable in a black small particle size toner. Further, in recent years, a developing method in which an AC bias is applied also in two-component development for the purpose of improving the image quality of a color image has become widespread.
In the case of using a black toner having a small particle diameter of not more than a micron, background stains are extremely likely to occur. Such stains on the background portion become remarkable when an image is formed under high temperature and high humidity such as in a summer environment. Also, as a simplified image forming apparatus,
There is a so-called developer-less cleaner type cleaner-less system that collects the toner remaining on the photoreceptor with a developing roll after transfer. However, when a small particle size toner is applied to this system, the background is similarly contaminated. become.

[0005]

When the small particle size toner is used for the two-component development, the stain on the image background portion is reduced due to the small amount of charge per small particle size toner. This is considered to be due to a decrease in the holding power of the steel. That is, the toner having a reduced holding force on the carrier is easily scattered from above the developing roll due to, for example, centrifugal force when the developing roll rotates, and adheres to the background area of the photoconductor, and the background of the image is removed. It is considered that a phenomenon of partial contamination occurs. Under high temperature and high humidity, the charge amount of the toner tends to decrease particularly, and this phenomenon becomes remarkable. In particular, since a black small particle toner usually contains carbon black as a colorant, charge injection easily occurs from a developing machine or the like via the carbon black. It is believed that the amount is reduced. Furthermore, in a developing method using an AC bias as a developing bias,
Since the small particle toner has insufficient followability to the electric field, the toner once adhered to the background area of the photoconductor is difficult to be collected again by the electrostatic attraction to the developing roll side, and the stain on the background is removed. It is thought to be noticeable. In order to solve such a problem, it is conceivable to increase the toner charge amount to improve the electric field follow-up property. However, as a result, the developed toner amount is significantly reduced and the image density becomes insufficient. As described above, it has been conventionally difficult to achieve both suppression of background stain on an image and high image density by two-component development using a small particle size toner.

An object of the present invention is to solve the above problems. That is, an object of the present invention is to provide a toner and a developer that can form a high-quality image with less background stain. An object of the present invention is to provide a toner and a developer that achieve excellent image quality maintenance. It is an object of the present invention to provide a toner and a developer capable of forming an image in which image quality does not easily change in the environment. It is an object of the present invention to provide a toner and a developer capable of realizing a reduction in toner consumption.
It is another object of the present invention to provide an image forming method capable of forming an image which has a small amount of dirt on a background portion of the image, has high image quality, and hardly causes environmental fluctuation in image quality, particularly a full-color image.

[0007]

The means for solving the above problems are as follows. (1) It contains a binder resin, carbon black, and a magnetic material, has a volume average particle size distribution of 1.25 or less, and has a shape factor of 10
0 to 140, and a toner having a volume average particle size of 2 to 7 μm. (2) The toner according to (1), wherein the content of the magnetic substance is from 0.1% by weight to 20% by weight. (3) The toner according to (1), wherein the content of the magnetic material is 0.1% by weight or more and 10% by weight or less. (4) The toner according to any one of (1) to (3), wherein the volume average particle diameter is 6 μm or less. (5) The toner according to any one of (1) to (4), further comprising a release agent. (6) The toner according to any one of (1) to (5), wherein the dielectric loss factor is 70 or less.

(7) The solvent has an average particle size of 20 to 50.
0 nm, a step of dispersing resin fine particles containing at least a binder resin, carbon black, and a magnetic material to form aggregated particles containing a binder resin, carbon black, and a magnetic material; Heating the dispersion liquid produced to form toner particles containing a binder resin, carbon black, and a magnetic substance. (8) The method for producing a toner according to (7), wherein a trivalent or higher metal salt is used as an aggregating agent in the step of forming aggregated particles.

(9) A developer comprising the toner described in (1) and a carrier. (10) a latent image forming step of forming a latent image on the latent image carrier, and contacting the latent image with a developer to develop the latent image;
A developing step of forming a toner image on the latent image carrier, and an image forming method having a transfer step of transferring the toner image onto a transfer body, wherein in the developing step, at least an AC bias is applied as a developing bias; And (9)
An image forming method, comprising using the developer described in (1). (11) The image forming method according to (10), further including a step of collecting the toner remaining on the latent image carrier with a developing roll after the transfer step.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The toner of the present invention contains at least a binder resin, carbon black, and a magnetic substance.
The magnetic material functions as a black colorant together with the carbon black, and further has a function of increasing the holding power of the toner on the carrier. Conventionally, black toner used for two-component development generally uses only conductive carbon black as a colorant. Therefore, it is considered that charge is injected from a developing machine or the like via carbon black, and the charge amount of the toner is reduced. In the present invention, a magnetic material is contained together with carbon black as a colorant, thereby increasing the holding power of the toner to the carrier. As a result, the scattering of the toner from the developing roll can be suppressed, and the toner once attached to the background area such as the photoconductor can be attracted to the carrier side by the application of the AC bias, and the background of the image can be attracted. Dirt can be reduced.

If the content of the magnetic substance in the toner is too large (for example, the same as the content of the magnetic substance contained in the toner for a one-component developer), the holding power to the carrier becomes strong. Too long, and the developability may decrease. On the other hand, if the content is too small, the effect of increasing the holding power may not be exhibited. From such a viewpoint, the content of the magnetic substance in the toner is preferably 0.1% by weight or more and 20% by weight or less, more preferably 0.1% by weight or more and 15% by weight or less. More preferably, it is not less than 0.1 wt% and not more than 10 wt%. As the magnetic material, metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys, and compounds containing these metals can be used.

[0012] Carbon black has the function of supplementing the black coloring power of the magnetic substance and controlling the chargeability of the toner. As the carbon black, a known general product can be used. The content of carbon black in the toner is preferably from 0.1% by weight to 20% by weight, and more preferably from 0.5% by weight to 10% by weight.

As the binder resin, homopolymers and copolymers of vinyl monomers are preferably used. Further, a homopolymer and a copolymer of a vinyl monomer are
A crosslinkable polymer crosslinked with a crosslinkable monomer such as divinylbenzene, glycidyl acrylate, or alkyl diol diacrylate may be used. Examples of the vinyl monomer include styrenes such as styrene and parachlorostyrene, such as vinyl naphthalene, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate. Vinyl esters,
For example, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, phenyl acrylate, α-methyl acrylate, methyl methacrylate, methyl methacrylate, Methylene aliphatic carboxylic esters such as ethyl methacrylate and butyl methacrylate, acrylonitrile, methacrylonitrile, and acrylamide, for example, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; N-vinyl pyrrole, N-vinyl N-vinyl compounds such as carbazole, N-vinylindole and N-vinylpyrrolidone; for example, vinyl carboxylic acids such as methacrylic acid, acrylic acid and cinnamic acid; The binder resin may use two or more kinds of polymers in combination.

The content of the binder resin in the toner is preferably from 40% by weight to 98% by weight, more preferably from 50% by weight to 96% by weight.

The toner of the present invention has a volume average particle size distribution (G
SD) is 1.25 or less, preferably 1.25 or less, more preferably 1.25 or less. The volume average particle diameter of the toner of the present invention is 2 to 7 μm, preferably 3 to 6.5 μm, more preferably 3 to 6 μm. Here, the GSD was used to determine 84% of the volume average particle size d ₈₄ and 16% of the volume average particle size d ₁₆ in the volume average particle size distribution curve measured using a Coulter counter, and to calculate each value as (d ₈₄ / d ₁₆₎ can be obtained by substituting ^0.5. The volume average particle size is in the curve indicates the 50% volume average particle diameter d _50. Further, the toner of the present invention has a shape factor (SF1) of 100 to 140, preferably 100 to 130, and more preferably 100 to 140.
~ 125. SF1 refers to a value calculated by Equation 1 below. Formula 1 SF1 = {(ML) ² / A} × (π / 4) × 100 In Formula 1, ML represents the maximum length of the toner particles, and A represents the projected area of the toner particles. As ML and A, values obtained by digitizing an optical microscope image and an electron microscope image of the toner with an image analyzer can be used.

The toner of the present invention preferably has a dielectric loss factor of 70 or less, more preferably 60 or less.
When the dielectric loss factor is in the above range, the charge injection can be suppressed, and the stain on the background portion can be further reduced.
Further, the environment dependency of the developing property can be reduced.
The dielectric loss factor is the type of carbon black contained in the toner, the electrical resistance of carbon black, the content of carbon black, the dispersibility of carbon black, the type of magnetic material, the electrical resistance of magnetic material, the content of magnetic material, It can be adjusted by the dispersibility of the magnetic material and the like, and further can be adjusted by post-treatment such as washing and adding an external additive such as a fluidizing agent. Incidentally, the dielectric loss factor is described in JP-A-10-319.
No. 624 ([0045]).
It can be measured with a CR meter (Type 4274A, manufactured by Yokogawa Hewlett-Packard) under the condition of a frequency of 100 kHz.

The toner of the present invention may contain other additives, if desired. Such additives include:
Release agents, charge control agents and the like can be mentioned. For example, it is preferable to include a release agent because it is possible to suppress the toner from adhering to the fixing roll. Examples of the release agent include various polyesters, various waxes such as polyethylene, polypropylene, paraffin, rice wax, candelilla wax, and carnauba wax. When a release agent is contained, the content is usually 0.1 to 30% by weight.
And preferably 1 to 15% by weight. Examples of the charge control agent include a quaternary ammonium salt compound, a nigrosine compound, a dye composed of a complex of aluminum, iron, and chromium, and a triphenylmethane pigment. When the toner of the present invention is produced by the following method, it is preferable to use a water-insoluble material as the charge control agent.

An external additive may be externally added to the toner of the present invention. As the external additive, inorganic fine particles are preferably used. For example, fine particles of silica, alumina, titania, calcium carbonate, magnesium carbonate, tricalcium phosphate and the like can be used.

The toner of the present invention can be easily produced by the following method. First, a dispersion (hereinafter, referred to as “dispersion 1”) in which resin particles containing at least a binder resin and having an average particle diameter of 20 to 500 nm are dispersed is prepared. Dispersion liquid 1 is preferably prepared by emulsion polymerization. It is preferable that the dispersion liquid 1 is prepared by emulsion polymerization because the average particle diameter of the resin fine particles can be accurately adjusted to the above range. Specifically, while dispersing a reaction liquid obtained by dispersing or dissolving a monomer of a radically polymerizable binder resin and a polymerization initiator, heating and emulsion-polymerizing the monomer, resin fine particles comprising the binder resin Is prepared. A chain transfer agent such as dodecanethiol and carbon tetrachloride may be added to the solvent. By adjusting the dispersion conditions during the emulsion polymerization, the type and amount of the initiator and the like, the reaction temperature, the reaction time, and the like, the average particle size of the resin fine particles can be accurately adjusted to the above range. The dispersion liquid 1 may be prepared by dispersing a binder resin in a solvent together with a surfactant, or may be prepared by suspension polymerization. In addition, the average particle size of the resin fine particles in the dispersion liquid 1 can be measured by Microtrack UPA manufactured by Nikkiso Co., Ltd., a laser Doppler method, or the like.

For preparing the dispersion 1, a general disperser such as a rotary shearing homogenizer or a disperser having media such as a ball mill, a sand mill, and a dyno mill can be used. The solvent of the dispersion 1 is preferably water,
A mixed solvent of water and an organic solvent may be used. Also, when a surfactant or an inorganic dispersion stabilizer is added to the solvent,
It is preferable because the dispersibility of the resin fine particles can be stabilized. Examples of such a surfactant include anionic surfactants such as sulfate ester type, sulfonate type, phosphate ester type and soap type, and cationic surfactants such as amine salt type and quaternary ammonium salt type. Is mentioned. It is also effective to use a nonionic surfactant such as a polyethylene glycol, an alkylphenol ethylene oxide adduct, and a polyhydric alcohol together with the ionic surfactant. As the inorganic dispersion stabilizer,
Inorganic fine particles usually used as an external additive for toners such as calcium carbonate, magnesium carbonate, barium carbonate, tricalcium phosphate, hydroxyapatite, silicic acid, diatomaceous earth, and clay are mentioned. It can be used dispersed in a molecular base.

Next, at least carbon black and a magnetic material are dispersed in the dispersion liquid 1 to form agglomerated particles containing a binder resin, carbon black, and a magnetic material. Dispersion average particle size of carbon black is 10 to 30
0 nm is preferable, and the dispersion average particle size of the magnetic material is 3 nm.
It is preferably from 0 to 800 nm. The carbon black and the magnetic substance added to the dispersion liquid 1 are added such that the amounts thereof are equal to the respective contents in the toner to be manufactured. When the toner contains other additives such as a release agent, the other additives are preferably dispersed in the dispersion 1 together with the carbon black and the magnetic substance. The carbon black and the magnetic substance may be added to the dispersion 1 as they are, but it is preferable to prepare an aqueous dispersion in which the carbon black and the magnetic substance are dispersed, and to mix the dispersion with the dispersion 1. As for other additives such as a release agent, it is preferable to add the dispersion to the dispersion 1 after preparing the dispersion by dispersing in a solvent. Dispersion of carbon black or a magnetic material can be performed using a rotary shearing homogenizer, ball mill,
It can be prepared by using a general disperser such as a disperser having a medium such as a sand mill and a dyno mill. Further, each dispersion may be prepared by applying ultrasonic vibration. In order to stabilize the dispersibility, the surfactant or the inorganic dispersion stabilizer may be added to each dispersion.

The dispersion 1 in which the carbon black, the magnetic substance, and other additives as required are dispersed, is stirred,
Agglomerated particles containing a binder resin, carbon black, and a magnetic material (other additives as desired) are formed. Agglomerated particles are formed by electrostatic interaction, hydrophobic interaction, and the like of components including a surfactant in the dispersion. In the step of forming aggregated particles, the dispersion may be heated while being stirred. In the case of heating, heating is performed so that the glass transition point of the binder resin does not exceed 15 ° C. or more. Further, once the aggregated particles are formed in the dispersion, the dispersion 1 may be further mixed. As described above, it is preferable that the dispersion 1 is further added after the aggregated particles are formed, because the exposure of the carbon black and the magnetic material is suppressed and the surface of the aggregated particles is uniform. In the step of forming the aggregated particles, it is preferable to add an aggregating agent to the dispersion liquid 1 because the aggregated particles can be stably generated. As the flocculant, anionic or cationic surfactants, amines such as triethanolamine and the like, and respective salts such as magnesium, zinc, aluminum and iron are effective. The above metal salts are effective,
Among them, flocculants such as polyiron and polyaluminum chloride are effective.

Next, the dispersion liquid in which the aggregated particles are formed is heated with stirring to combine the components contained in the aggregated particles to produce toner particles. In this step, the toner particles maintain the same average particle size as the aggregated particles. The preferred range of the heating temperature varies depending on the type of the binder resin and the like, but is a temperature exceeding the glass transition point of the binder resin,
Further, under atmospheric pressure, heating is performed at a temperature lower than the boiling point of water. Also,
It is preferable to add a base such as a sodium hydroxide solution before heating because the stability of the aggregated particles under heating is improved.

Thereafter, the dispersion is filtered, and the generated toner particles can be collected from the dispersion. The obtained toner is preferably sufficiently washed with pure water or a dilute solution of an acid or a base to remove a dispersion stabilizer or the like remaining on the toner surface.

The developer of the present invention is a two-component developer comprising the toner and a carrier. As the carrier, known carriers such as ferrite, iron oxide powder, nickel or other magnetic metal powder, a coated carrier obtained by coating these with a resin, and a magnetic powder-dispersed carrier can be widely used. The average particle size of the carrier is usually 10
１００100 μm, preferably 20-60 μm.

An example of an image forming method using the developer of the present invention will be described below. The black developer of the present invention is stored in a developing machine of an image forming apparatus such as a copying machine. The image forming apparatus includes a photoconductor (latent image carrier), a charger, an exposure device, and a transfer device in addition to the developing device. After the photoreceptor is uniformly charged by the charger, it is imagewise exposed by an exposure device, and an electrostatic latent image is formed on the photoreceptor (latent image forming step). Thereafter, the electrostatic latent image is developed by a developing machine that stores the developer of the present invention, and a toner image is formed on the photoconductor (developing step). The toner image is transferred to a recording medium such as paper by a transfer device, and the transferred image is thereafter heated and pressed by a fixing roll or the like as desired, and is fixed on the recording medium to form an image.

The developing machine includes, for example, a developing roll including a magnetic roll. The developer is attracted to the developing roll by a magnetic force and adheres to the surface of the developing roll.
It is conveyed in the direction of the photoreceptor and contacts the latent image forming area of the photoreceptor at the developing nip. In the developing nip portion, the toner in the developer is electrostatically attracted to the latent image portion of the photoconductor by applying a developing bias. In the conventional small particle size toner, the charge amount per toner particle is small, so that the holding force on the carrier is small. As a result, when the toner is conveyed toward the photoconductor,
Due to the effect of centrifugal force generated by the rotation of the developing roll, the toner may be easily scattered and adhere to the photoreceptor, causing stains on the image background. Although the toner of the present invention has a small particle size, it contains a magnetic material together with carbon black, so it has a large holding power to a carrier, does not easily scatter during transportation, and suppresses stains on a background portion. Is done. Further, when an AC bias is applied together with a DC bias as a developing bias, a toner having a small particle diameter adheres to the background area of the photoreceptor by applying a reverse bias.
Although this may cause background stains, the toner of the present invention has a strong holding power to the carrier, so that the toner once attached to the background area of the photoconductor can be attracted again in the carrier direction. As a result, the stain on the image background can be reduced while maintaining the advantage of the AC bias application of improving the development efficiency.

After the toner image formed on the photoconductor is transferred onto a recording medium, the toner remaining on the photoconductor can be collected by a developing roll in a developing machine. By collecting the residual toner with the developing roll, the image quality of the formed image can be maintained for a long time by a simple device without providing a cleaning means such as a cleaning blade.

[0029]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples. Example 1 <Preparation of resin fine particle dispersion> Styrene 340 g n-butyl acrylate 60 g acrylic acid 6 g dodecanethiol 8 g 4 carbon bromide 4 g The above components were mixed and dissolved, and a nonionic surfactant "Nonipol 400" (Sanyo) The mixture was dispersed and emulsified in a solution prepared by dissolving 6 g of anionic surfactant “Neogen SC” (manufactured by Daiichi Kogyo Seiyaku) in 550 g of ion-exchanged water in a flask. While slowly mixing for 10 minutes, 50 g of ion-exchanged water in which 4 g of ammonium persulfate was dissolved was added, and the atmosphere in the flask was replaced with nitrogen. Then, while stirring the flask, the contents in the flask were heated to 70 ° C. using an oil bath, and emulsion polymerization was performed for 5 hours. As a result, a resin fine particle having a glass transition point of 59 ° C. and a weight average molecular weight of 28,000 was converted to an average particle diameter of 180 nm.
To obtain an anionic resin fine particle dispersion.
The average particle size of the resin fine particles was measured by using Microtrack UPA manufactured by Nikkiso Co., Ltd.

<Preparation of Carbon Particle Dispersion> Carbon black “REGAL 330” (manufactured by Cabot) 50 g Sodium alkylbenzenesulfonate 5 g Ion-exchanged water 200 g A mixture was mixed and dissolved, and the mixture was irradiated with a homogenizer (IKA Ultra Turrax) and ultrasonic irradiation. Dispersed, central particle size 125
Thus, a dispersion of carbon particles having a diameter of nm was obtained.

<Preparation of Magnetic Particle Dispersion> 200 g of magnetite “EPT1000” (manufactured by Toda Kogyo), 5 g of sodium alkylbenzenesulfonate, and 200 g of ion-exchanged water are mixed and dissolved, and the mixture is irradiated with a homogenizer (IKA Ultra Turrax) and ultrasonic irradiation. Disperse, center particle size 150
Thus, a dispersion of magnetic material particles having a diameter of nm was obtained.

<Preparation of Release Agent Particle Dispersion> 50 g of paraffin wax “HNP9” (manufactured by Nippon Seiro Co., Ltd.) 5 g of sodium dodecylbenzenesulfonate 200 g of ion-exchanged water And dispersed by a pressure discharge type homogenizer to obtain a release agent particle dispersion having a center diameter of 150 nm.

<Preparation of Toner 1> Resin fine particle dispersion liquid 162.5 g (corresponding to 65% by weight) Carbon particle dispersion liquid 15g (corresponding to 3% by weight) Magnetic substance particle dispersion liquid 20g (corresponding to 10% by weight) Release agent particle dispersion 28 g of liquid (equivalent to 7% by weight) 1.5 g of polyaluminum chloride solution (10% product) 1.5 g of each dispersion mixed in the above ratio, and "Ultra Turrax T50" (manufactured by IKA) in a round stainless steel flask
And heated to 48 ° C. while stirring the flask in an oil bath for heating. After maintaining at 48 ° C. for 30 minutes, observation with an optical microscope confirmed that aggregated particles of about 5.6 μm had been formed.

In the dispersion in which the formation of agglomerated particles was observed,
37.5 g (corresponding to 15% by weight) of the resin fine particle dispersion was gently added, and the temperature of the heating oil bath was increased, and the temperature was maintained at 50 ° C. for 1 hour. Observation with an optical microscope confirmed that aggregated particles of about 5.8 μm had been formed. Then, 1N sodium hydroxide solution was added,
In a stainless steel flask, with continuous stirring,
C. and held for 3 hours. After cooling, the dispersion was filtered to collect black particles in the dispersion. The particles were sufficiently washed with ion-exchanged water to obtain a black toner 1. The volume average particle diameter of the obtained toner 1 was 5.8 μm when measured by a Coulter counter. Also, the volume G
SD was 1.21 and shape factor SF1 was 128. The dielectric loss ratio measured with an LCR meter (model 4274A, manufactured by Yokogawa Hewlett-Packard Company) was 35.5.
Met.

To the obtained toner 1, 0.8 wt% of silica “TS720” manufactured by Cabot was externally added, and then a ferrite core having an average particle diameter of 50 μm was coated with 1 wt% of polymethyl methacrylate (manufactured by Soken Chemical). By mixing with a carrier, developer 1 was obtained. The mixing ratio of the toner (including the external additive) and the carrier was such that the toner concentration was 8% by weight. Using this developer 1, “A” manufactured by Fuji Xerox Co., Ltd.
color 620 "and used in a summer environment (30
(85 ° C., 85% RH), and an image quality was evaluated by visual observation. The obtained image was clear, excellent in developability, and a good image with no stain on the background. The developing conditions of the used “Acolor 620” modified machine are as follows:
It is as follows. Background area potential -700V Image section area potential -300V Development bias condition DC bias -560V AC bias Peak-to-peak voltage 1000V Frequency 9kHz

Example 2 <Preparation of Toner 2> Resin fine particle dispersion 125 g (equivalent to 50% by weight) Carbon particle dispersion 25 g (equivalent to 5% by weight) Magnetic particle dispersion 38 g (equivalent to 19% by weight) Release agent Particle dispersion 28 g (corresponding to 7% by weight) Polyaluminum chloride solution (10% product) 1.5 g Each dispersion was mixed at the above ratio, and "Ultra Turrax T50" (manufactured by IKA) in a round stainless steel flask. )
And heated to 45 ° C. while stirring the flask in an oil bath for heating. After maintaining at 45 ° C. for 30 minutes, observation with an optical microscope confirmed that aggregated particles of about 4.8 μm had been formed.

In the dispersion in which the formation of agglomerated particles was observed,
47.5 g (corresponding to 19% by weight) of the resin fine particle dispersion was gently added, and the temperature of the oil bath for heating was further increased and maintained at 50 ° C. for 1 hour. Observation with an optical microscope confirmed that aggregated particles of about 5.0 μm had been formed. Then, after adding a 1N sodium hydroxide solution, the mixture was stirred for 9 hours in a stainless steel flask.
Heated to 5 ° C and held for 3 hours. After cooling, the dispersion was filtered to collect black particles in the dispersion. The particles were sufficiently washed with ion-exchanged water to obtain a black toner 2. The volume average particle size of the obtained toner 2 was measured by a Coulter counter and found to be 5.0 μm. Also, the volume G
SD was 1.20 and shape factor was 132. The dielectric loss factor was 67.5.

To the obtained toner 2, 0.8 wt% of silica “TS720” manufactured by Cabot was externally added, and then 50 μm
Was mixed with a carrier in which 1% by weight of polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.) was coated on the ferrite core of Example 1 to obtain a developer 2. The mixing ratio of the toner (including the external additive) and the carrier was such that the toner concentration was 8% by weight. Using this developer, “Acolo” having the same specifications as in Example 1 was used.
r 620 ”in a summer environment (30 ° C, 85
% RH), an image was formed, and the image quality was visually evaluated. In Example 2, although the developability was slightly lower than that in Example 1, the image quality of the obtained image was in a range where there was no problem in practical use. Was.

Example 3 <Preparation of Toner 3> 175 g of resin fine particle dispersion (equivalent to 70% by weight) 15 g of carbon particle dispersion (equivalent to 3% by weight) 12 g of magnetic material particle dispersion (equivalent to 6% by weight) Release agent Particle dispersion 28 g (corresponding to 7% by weight) Polyaluminum chloride solution (10% product) 1.5 g Each dispersion was mixed at the above ratio, and "Ultra Turrax T50" (manufactured by IKA) in a round stainless steel flask. )
And heated to 45 ° C. while stirring the flask in an oil bath for heating. After maintaining at 45 ° C. for 30 minutes, observation with an optical microscope confirmed that aggregated particles of about 4.3 μm had been formed.

In the dispersion in which the formation of aggregated particles was observed,
32.5 g (corresponding to 13% by weight) of the resin fine particle dispersion was gently added, and the temperature of the oil bath for heating was further increased and maintained at 50 ° C. for 1 hour. Observation with an optical microscope confirmed that aggregated particles of about 4.5 μm had been formed. Then, after adding a 1N sodium hydroxide solution, the mixture was stirred for 9 hours in a stainless steel flask.
Heated to 5 ° C and held for 3 hours. After cooling, the dispersion was filtered to collect black particles in the dispersion. The particles were sufficiently washed with ion-exchanged water to obtain a black toner 3. The volume average particle diameter of the obtained toner 3 was 4.5 μm as measured by a Coulter counter. Also, the volume G
SD was 1.19 and shape factor was 122. The dielectric loss factor was 18.5.

To the obtained toner 3, 0.8% by weight of silica “TS720” manufactured by Cabot was externally added.
The ferrite core was mixed with a carrier in which polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.) was coated at 1% by weight to obtain a developer 3. The mixing ratio of the toner (including the external additive) and the carrier was such that the toner concentration was 8% by weight. Using this developer 3, “Acol” having the same specifications as in Example 1 was used.
or 620 ”using a remodeled machine in a summer environment (30 ° C, 8
5% RH), an image was formed, and the image quality was visually evaluated. The obtained image was clear and fine, had extremely high developability, and had good image quality with no stain on the background.

Example 4 <Preparation of Toner 4> Resin fine particle dispersion 125 g (corresponding to 50 wt%) Carbon particle dispersion 15 g (corresponding to 3 wt%) Magnetic particle dispersion 50 g (corresponding to 25 wt%) Release agent Particle dispersion 28 g (corresponding to 7% by weight) Polyaluminum chloride solution (10% product) 1.5 g Each dispersion was mixed at the above ratio, and "Ultra Turrax T50" (manufactured by IKA) in a round stainless steel flask. )
And heated to 47 ° C. while stirring the flask in an oil bath for heating. After maintaining at 47 ° C. for 30 minutes, observation with an optical microscope confirmed that aggregated particles of about 4.8 μm had been formed.

In the dispersion in which the formation of aggregated particles was observed,
37.5 g (corresponding to 15% by weight) of the resin fine particle dispersion was gently added, and the temperature of the oil bath for heating was further increased and maintained at 50 ° C. for 1 hour. Observation with an optical microscope confirmed that aggregated particles of about 5.0 μm had been formed. Then, after adding a 1N sodium hydroxide solution, the mixture was stirred for 9 hours in a stainless steel flask.
Heated to 5 ° C and held for 3 hours. After cooling, the dispersion was filtered to collect black particles in the dispersion. The particles were sufficiently washed with ion-exchanged water to obtain a black toner 4. The volume average particle diameter of the obtained toner 4 was measured by a Coulter counter and found to be 5.0 μm. Also, the volume G
SD was 1.22 and shape factor was 125. The dielectric loss factor was 78.5.

To the obtained toner 4, 0.8% by weight of Cabot silica "TS720" was externally added.
The ferrite core was mixed with a carrier in which polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.) was coated at 1% by weight to obtain a developer 4. The mixing ratio of the toner (including the external additive) and the carrier was such that the toner concentration was 8% by weight. Using this developer 4, “Acol” having the same specifications as in Example 1 was used.
or 620 ”using a remodeled machine in a summer environment (30 ° C, 8
Under 5% RH), an image was formed and the image quality was evaluated. The image quality of the obtained image was lower than that of Examples 1 to 3, and the developability was inferior. However, the stain on the background portion was less than that of the following Comparative Examples.

Comparative Example 1 <Preparation of Toner 5> Resin fine particle dispersion 150 g (equivalent to 60 wt%) Carbon particle dispersion 25 g (equivalent to 5 wt%) Release agent particle dispersion 28 g (equivalent to 7 wt%) Polychlorinated 1.5 g of an aluminum solution (10% product) Each dispersion was mixed in the above composition, and "Ultra Turrax T50" (manufactured by IKA) in a round stainless steel flask.
And heated to 46 ° C. while stirring the flask in a heating oil bath. After maintaining at 46 ° C. for 30 minutes, observation with an optical microscope confirmed that approximately 4.5 μm aggregated particles had been formed.

In the dispersion in which the formation of aggregated particles was observed,
67.5 g (corresponding to 27% by weight) of the resin fine particle dispersion was gently added, and the temperature of the oil bath for heating was further increased and kept at 48 ° C. for 1 hour. Observation with an optical microscope confirmed that aggregated particles of about 5.0 μm had been formed. Then, after adding a 1N sodium hydroxide solution, the mixture was stirred for 9 hours in a stainless steel flask.
Heated to 5 ° C and held for 3 hours. After cooling, the dispersion was filtered to collect black particles in the dispersion. The particles were sufficiently washed with ion-exchanged water to obtain a black toner 5. The volume average particle size of the obtained toner 5 was measured by a Coulter counter and found to be 5.0 μm. Also, the volume G
SD was 1.22 and shape factor was 122. The dielectric loss factor was 31.0.

To the obtained toner 5, 0.8 wt% of silica “TS720” manufactured by Cabot was externally added.
The ferrite core was mixed with a carrier in which polymethyl methacrylate (manufactured by Soken Chemical Co., Ltd.) was coated at 1% by weight to obtain a developer 5. The mixing ratio of the toner (including the external additive) and the carrier was such that the toner concentration was 8% by weight. Using this developer 5, “Acol” having the same specifications as in Example 1 was used.
or 620 ”using a remodeled machine in a summer environment (30 ° C, 8
Under 5% RH), an image was formed and the image quality was evaluated. The image quality of the obtained image was inferior to those of Examples 1 to 4, the developability was low, and the background portion had much stain.

Table 1 below shows the toners 1 to 4 used in Examples 1 to 4 and the toner 5 used in Comparative Example 1.
The results of visual evaluation of the various characteristics, the developability of the formed image, and the stain on the background are shown. Table 1
In the middle column, “◎” in the column of developability indicates that the image was clear and the developability was extremely excellent, “〇” indicates that the developability was excellent, and “△” indicates that the developability was practical. And "x" indicates that the developability was poor. In addition, `` 」'' in the column of background stain shows that there was no background stain, and` `〇 '' shows that the background stain was slightly observed, but it was within a range where there was no practical problem,
“△” indicates that background stain was observed, and “×” indicates that background stain was remarkable.

[0049]

[Table 1]

[0050]

According to the present invention, it is possible to provide a toner and a developer capable of forming a high-quality image with little background stain. Further, it is possible to provide a toner and a developer capable of forming an image in which image quality does not easily change in the environment. Further, according to the present invention, it is possible to provide an image forming method capable of forming an image with less background portion contamination, high image quality, and less likely to cause environmental fluctuations in image quality.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuo Kadokura 1600 Takematsu, Minamiashigara-shi, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Inventor Shuji Sato 1600 Takematsu, Minamiashigara-shi, Kanagawa F-term in Fuji Xerox Co., Ltd.

Claims (4)

[Claims] 1. A toner containing a binder resin, carbon black, and a magnetic material, having a volume average particle size distribution of 1.25 or less, a shape factor of 100 to 140, and a volume average particle size of 2 to 7 μm. 2. The solvent has an average particle size of 20 to 500 nm.
Is, resin fine particles containing at least a binder resin,
Disperse carbon black and magnetic material, binder resin,
A step of forming aggregated particles containing carbon black and a magnetic substance, and a step of heating the dispersion liquid in which the aggregated particles are formed to form toner particles containing a binder resin, carbon black, and a magnetic substance. And a method for producing a toner. 3. A developer comprising the toner according to claim 1 and a carrier. 4. A latent image forming step of forming a latent image on a latent image carrier, and developing the latent image by contacting the latent image with a developer to form a toner image on the latent image carrier. A developing step;
A transfer step of transferring the toner image onto a transfer member, wherein in the developing step, at least an AC bias is applied as a developing bias, and the developer according to claim 3 is used. Image forming method.