JPH07333888A - Production of magnetic toner and electrophotographic method - Google Patents

Abstract

PURPOSE:To provide a magnetic toner and an electrophotographic method by which high image quality is obtained, as an electrophotographic method using a compact and high-performance developing method. CONSTITUTION:In this electrophotographic method having a developing stage where toner at a non-image part is recovered by an electrode roller 8 after forming an electrostatic latent image by using a photoreceptor drum 1 having a fixed magnet 2 inside, and a transfer stage by a conductive elastic roller, the magnetic toner 7 possesses a charge control agent being metal complex dyestuff, magnetic substance having specified bulk density and binding resin having specified storage elastic modulus and is pulverized by a rotating body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner manufacturing method and an electrophotographic method used in copying machines, printers and facsimiles.

[0002]

2. Description of the Related Art In recent years, electrophotographic apparatuses are shifting from the purpose of office use to personal use, and there is a demand for a technology for realizing downsizing and maintenance-free operation.
Therefore, conditions such as maintainability such as recycling of waste toner and less ozone exhaust are required.

A printing process of an electrophotographic copying machine or printer will be described. First, an electrostatic latent image carrier (hereinafter referred to as a photoconductor) is charged for image formation. As a charging method, a conventionally used corona charger is used, and in recent years, a contact type charging method in which a conductive roller is directly pressed against the photoreceptor to reduce the amount of ozone generation is used. Charge the surface uniformly. After charging the photoreceptor,
In the case of a copying machine, a copy original is irradiated with light and reflected light is irradiated onto a photoconductor through a lens system. Alternatively, in the case of a printer, an image signal is sent to a light emitting diode or a laser diode as an exposure light source, and a latent image is formed on the photoconductor by turning the light on and off. When a latent image (high or low surface potential) is formed on the photoconductor, the photoconductor is visualized with toner (having a diameter of about 5 μm to 15 μm) which is precharged colored powder. The toner adheres to the surface of the photoconductor according to the level of the surface potential of the photoconductor, and is electrically transferred to the copy sheet. That is, the toner is charged positively or negatively in advance, and a charge having a polarity opposite to the polarity of the toner is applied from the back surface of the copy sheet and is electrically attracted. Up to now, a corona discharger has been widely used as the charge applying method as in the charging method, but in recent years, a transfer device using a conductive roller has been put into practical use in order to reduce the ozone generation amount. At the time of transfer, not all the toner on the photoconductor is transferred to the copy sheet, but a part of the toner remains on the photoconductor. This residual toner is scraped off by a cleaning blade or the like in the cleaning section to become waste toner.

Conventionally, there are a cascade developing method, a touch-down developing method, a jumping developing method and the like as a developing method for converting an electrostatic latent image into a visible image by an electrophotographic method. Among them,
Cascade development shown in US Pat. No. 3,105,770 is known as a developing method in which a developer is directly sprinkled on the photoreceptor. The cascade developing method is the first developing method used in a copying machine for electrophotography. Further, there is US Pat. No. 3,866,574 as a method of applying an AC bias to the developing roller to fly the one-component toner and develop the toner. According to the present invention, the AC bias applied to the developing roller is used for the purpose of activating the movement of the toner, and the toner flies to the image portion and returns to the non-image portion in the middle.

Further, as an improved technique for applying the AC bias, there is a jumping development disclosed in Japanese Patent Publication No. 63-42256. In this jumping developing method, toner is carried on a toner carrier, and a rigid or elastic regulating blade is installed on the toner carrier with a minute gap from the carrier. Then, the regulation blade regulates the toner in a thin layer, conveys the toner to a developing portion, and the toner is attached to the image portion of the photoconductor by an AC bias there. The technical idea of Japanese Patent Publication No. 63-42256 differs from the above-mentioned US Pat. No. 3,866,574 in that the toner reciprocates in the image portion and the non-image portion.

As is well known, the toner for electrostatic charge development used in these developing methods generally contains a resin component, a coloring component composed of a pigment or a dye and a plasticizer, a charge control agent and, if necessary, a magnetic component. It is composed of additional components such as a body and a release agent. As the resin component, natural or synthetic resins are used alone or in a proper mixture.

Then, the above additives are premixed in an appropriate ratio, heated and kneaded by hot melting, finely pulverized by an airflow type collision plate system, and finely powdered to complete a toner base.
After that, an external additive is externally added to the toner base to complete the toner.

[0008]

However, in the magnetic toner, the magnetic substance is internally added to the binder resin. Conventionally, toner is pulverized and finely divided by an airflow type collision plate method. Since magnetic particles having a resistance lower than that of the binder resin are present, the magnetic toner has a drawback that it is difficult to obtain a high charge amount.

Therefore, in the magnetic toner, in the binder resin,
A charge control agent such as a dye is internally added in order to have a negative charging property. As a result, the charging polarity of the toner can be strongly negatively charged. As an example of using a metal complex salt dye in a toner, for example, Japanese Patent Publication No. 4-6397 and Japanese Patent Publication No.
There are JP-A No. 1-112915, JP-B No. 41-20153, JP-B No. 51-29827 and the like, which show that high charging characteristics for the purpose of charge control can be obtained.

However, when a charge control agent of a metal complex salt dye and a magnetic substance are added to the magnetic toner in the binder resin, the magnetic substance and the metal complex salt dye having different specific gravities are added and mixed, and the binder resin is melted and kneaded. There is a drawback that the dispersibility in the inside deteriorates. Although the detailed cause is unknown, it is considered that the particles repelled electrostatically and the cohesiveness became stronger.

When the dispersibility is deteriorated, the amount of the oppositely charged toner particles is increased, so that the toner adheres to the non-image area, that is, the background fog is increased, and the image quality is deteriorated.

The developing method, which is well known in the art, is the cascade developing method.
I was not good at reproducing solid images. Further, there is a problem that the device becomes large and complicated. Further US Patent 38
The 66574 developing device has the drawback that the device requires high accuracy and is complicated and costly. In the jumping development method, it was essential to form a very uniform thin layer on a toner carrier carrying a toner layer. Further, in this method, so-called sleeve ghost development occurs in which the history of the previous image remains in the thin toner layer on the toner carrier and an afterimage appears in the image. Further, there is a drawback that the device is complicated and the cost is high.

Therefore, the inventors of the present invention have proposed the electrophotographic method of the present invention capable of realizing the downsizing and high performance of development (Japanese Patent Laid-Open No. 5-72).
890). In the developing method of this electrophotographic method, unnecessary toner in the non-image area is removed by a photoreceptor containing a fixed magnet and a toner recovery electrode roller (hereinafter referred to as an electrode roller) having a magnet facing the photoreceptor with a predetermined gap. It is a configuration to be removed. Therefore, this developing method faithfully reproduces a solid image, does not generate a sleeve ghost, and enables further downsizing, simplification, and cost reduction of the apparatus.

However, in order to obtain high image quality by using this developing method, higher performance toner characteristics are required.
Since this developing method does not use a regulating blade that regulates the toner in a thin layer, the toner is conveyed to the developing field, which is a space having a narrow gap between the photoconductor and the electrode roller, without regulating the layer. Therefore, there are few places and spaces required for the toner to be triboelectrically charged to obtain a desired charge amount, and the toner requires higher fluidity and higher charging characteristics than ever before.

With a toner having a low charge amount, unevenness occurs in a solid black image portion and a halftone image portion, and background fog increases in a non-image portion. Since the probability of contact with the developing member is low, a satisfactory triboelectrification amount cannot be obtained. Further, the triboelectric chargeability varies among the toners, and uniform toner chargeability cannot be obtained.

In the electrophotographic method of the present invention, toner is first sprinkled on the electrostatic latent image holding member and developed. The toner is always in contact with the entire surface of the photoconductor, and the electrode roller portion circulates the toner in the toner retainer and at the same time collects the toner in the non-image portion of the electrostatic latent image by magnetism and electrostatic force. Therefore, if the dispersibility of the charge control agent and the internal additive such as a magnetic substance in the toner varies, the consumed toner is extremely biased and the toner is selectively developed. For example, toner particles in which a large amount of magnetic material is unevenly distributed remain, and consumption of particles in which a large amount of charge control agent is unevenly distributed progresses, and the charging characteristics of the toner change during long-term use, which causes a problem that the image density decreases.

In view of the above problems, the present invention provides a method of producing a magnetic toner capable of realizing high image density and high image quality of low ground fog in a developing method which enables further downsizing, simplification and cost reduction of the apparatus. To provide an electrophotographic method.

Further, there is provided a method for producing a magnetic toner and an electrophotographic method, which are capable of prolonging the life without causing agglomerates by reducing the charge amount and fluidity of the toner even after long-term use and achieving image stability. The purpose is to do.

[0019]

In order to solve the above problems, in the magnetic toner and the electrophotographic method of the present invention, the magnetic toner comprises a magnetic toner base comprising at least a binder resin, a magnetic material and a charge control agent, The binder resin is composed of an external additive and has a storage elastic modulus of 1.0 × 10 ^{4 to} 2.0 × 10 ⁷ (d
yn / cm ² ) (a storage elastic modulus measuring device is a viscoelasticity spectrometer, measurement conditions are 200 ° C., 20 Hz), and a styrene-based polymer containing styrene as a main component or styrene containing styrene as a main component Or a styrene-based copolymer containing styrene as a main component or a mixture of styrene-based copolymers containing styrene as a main component, wherein the charge control agent is at least represented by the general formula (Formula 1). And a magnetic substance having a bulk specific gravity of 0.5 g / cm ³ or more, the magnetic toner base is finely pulverized, and the peripheral speed is 80 m / min. A cylindrical crushing rotary body that rotates at high speed for more than sec and a fixed ridged rotary body that is fitted on the outer side of the crushing rotary body with a narrow gap of 0.5 to 5 mm. When configured crushing section and a,
A method for producing a magnetic toner, which is performed by a fine pulverizing device, comprising: a supply port for supplying a magnetic toner base material of an object to be crushed and an air flow; and a discharge port for discharging the magnetic toner crushed by the crushing unit and the air flow. is there.

Further, the present invention is a method for producing a magnetic toner, wherein the charge control agent is contained in an amount of 0.01 to 5.0% by weight based on the weight of the magnetic toner.

Further, the present invention is a method for producing a magnetic toner containing a magnetic substance in an amount of 15 to 70% by weight based on the weight of the magnetic toner.

Further, in the present invention, the external additive is a negatively charged hydrophobic silica fine powder surface-treated with silicone oil, and the magnetic content is 0.1 to 5.0 parts by weight based on 100 parts by weight of the magnetic toner. It is a method of manufacturing a toner.

Further, according to the present invention, a fixed magnet is contained and moved.
The electrostatic latent image holding member, the toner hopper, and the electrostatic latent image holding member.
Place a magnet inside at a position with a specified gap from the surface of the holder.
And a toner recovery electrode roller having
After forming an electrostatic latent image on the holder,
Magnetic toner is magnetically applied to the surface of the electrostatic latent image holding member.
The magnetic toner on the surface of the electrostatic latent image carrier.
Support the electrostatic latent image carrier and move the electrostatic latent image carrier.
Of the electrostatic latent image holding member facing the toner collecting electrode roller.
The magnetic toner remains in the image area and the magnetic toner in the non-image area
There is a developing process that collects toner with an electrode roller.
An electrophotographic method that uses less magnetic toner
Magnetic toner consisting of binder resin, magnetic substance, and charge control agent
It is composed of a matrix and an external additive, and the binder resin is
The sex rate is 1.0 × 10 ^Four~ 2.0 x 10⁷(Dyn / c
m²) (A storage elastic modulus measuring device
Measurement conditions are 200 ° C. and 20 Hz), and
Styrene-based polymer or styrene containing styrene as the main component
Mixture of styrene-based polymers containing
Styrene-based copolymer or styrene containing mainly ethylene
Made of a mixture of styrene-based copolymers
And the charge control agent is at least represented by the general formula (Formula 1).
It is composed of a metal complex salt dye, and the magnetic substance is at least
Mokasa specific gravity 0.5g / cm³Do not use the above magnetic particles
The finely pulverized magnetic toner base has irregularities on the surface.
However, the cylindrical shape that rotates at a high speed at a peripheral speed of 80 m / sec or more
A crushing rotary body and the crushing rotary body on the outside of the crushing rotary body
And the surface is recessed by being fitted with a narrow gap of 0.5 to 5 mm.
A crushing unit composed of a fixed body having a protrusion and an object to be crushed
The magnetic toner base and the supply port for supplying the air flow, and the powder
A discharge port for discharging the magnetic toner crushed by the crushing unit and the air flow
Using a magnetic toner made by a fine pulverizer equipped with
It is an electrophotographic method.

Further, the present invention is an electrophotographic method using a magnetic toner containing a charge control agent in an amount of 0.01 to 5.0% by weight based on the weight of the magnetic toner.

Further, the present invention is an electrophotographic method using a magnetic toner containing a magnetic substance in an amount of 15 to 70% by weight based on the weight of the magnetic toner.

Further, in the present invention, the external additive is a negatively charged hydrophobic silica fine powder surface-treated with silicone oil, and the magnetic content is 0.1 to 5.0 parts by weight based on 100 parts by weight of the magnetic toner. This is an electrophotographic method using a toner.

Further, the present invention is an electrophotographic method in which the magnetic toner is a one-component toner.

[0028]

The present invention has the above-mentioned constitution and can obtain a high negative chargeability by using a metal complex salt dye as the charge control agent.
Also, the rising property of charging is improved. However, when the magnetic particles were added, the dispersibility was deteriorated, the charge amount was decreased, and there was a tendency for non-uniform charging.

However, at this time, the quietness density is 0.5 g / c
m ³ or more, further moved by the use of magnetic particles is density 1.1 g / cm ³ or more to improve the dispersibility of the metal complex dye of the present invention. As a result, although the magnetic particles are added, the negative charging property is improved and the highly charging toner property is obtained. It is considered that this is because the flowability of the magnetic material itself is improved, the cohesiveness is weakened, and the dispersibility is improved. Further, it is presumed that the charge control agent also has the effect of releasing the aggregation.

In order to increase the bulk specific gravity of the magnetic material, it is preferable to subject the magnetic material to degassing or to treat the surface with an organic material or the like. This surface treatment is titanium coupling treatment,
A silane coupling treatment or a surface treatment with a silicone resin, an acrylic resin, a styrene resin, a polyester resin, or the like can be considered.

When the quietness density is 0.5 g / cm ³ or less, the dispersibility of the magnetic material itself is poor and the dispersibility in the binder resin is deteriorated. Further, when the mobility density is 1.1 g / cm ³ or less, the cause is unknown, but the kneading property at the time of heat melting is poor and the dispersibility of the charge control agent is deteriorated.

The amount of the magnetic material added is preferably 15 to 70% by weight based on the weight of the magnetic toner. 15
If it is less than 50% by weight, the toner scattering increases, and if it is 70% by weight, the fixing property deteriorates.

The charge control agent is preferably added in an amount of 0.01 to 5.0% by weight based on the weight of the magnetic toner. 0.01
If it is less than weight%, high negative chargeability cannot be obtained. If it is 5.0% by weight or more, the fluidity is lowered under high humidity and the image quality is deteriorated.

The magnetic toner according to the present invention uses a styrene resin having a storage elastic modulus of 1.0 × 10 ^{4 to} 2.0 × 10 ⁷ dyn / cm ² . It has been found that by using this resin, a uniform kneading torque is applied during hot melt kneading, for example, when kneading is performed by a twin-screw extruder, and the dispersibility of the internal additive is greatly improved. It is speculated that the resin itself has appropriate meltability and viscoelasticity.

Storage elastic modulus of 1.0 × 10 ⁴ dyn / cm ²
In the following cases, torque is hardly applied during kneading and dispersibility is not improved. In addition, the generation of fine powder increases during crushing. 2.
When it is 0 × 10 ⁷ dyn / cm ² or more, the elasticity becomes too strong, the kneading ability is lowered, and the pulverizability is deteriorated.

The dynamic viscoelasticity measurement is a measuring method for observing the temperature dependence for a certain frequency or the frequency dependence for a certain temperature, and the storage elastic modulus can be calculated from the response to a stress of a certain frequency. The resin was melted to prepare a plate-shaped sample, which was sandwiched between cone plate-shaped sample supports, and the temperature dependence when a constant frequency was applied was measured. The measuring device is Rheometric
ics) Rheometrics Dynamic Spectrometer (Rheometrics Dynamic)
It was performed using a Spectrometer (RDS-2).

In the conventional crushing process, a method of finely crushing has been adopted by collision crushing with a jet mill crusher or the like. However, this method is a method of hitting the toner against the collision plate and crushing it, so the shape of the crushed toner is indefinite,
Moreover, it has a drawback that a large amount of fine powder is generated. It is thought that the charge control agent, which is a metal complex salt dye internally added to the resin at the time of this pulverization, and the magnetic substance are likely to be unevenly exposed on the surface of the toner base, resulting in uneven chargeability of the toner and deterioration of the image. To be

However, in the method of finely pulverizing by a vortex in the narrow gap space between the pulverizing rotating body and the fixed body of the present invention, the toner is pulverized in such a manner that the surface of the toner is peeled off, that is, the toner is pulverized by the so-called peel effect. . Therefore, the charge control agent or magnetic substance, which is the metal complex dye internally added to the resin during crushing, which is seen in the collision plate method, is not unevenly exposed on the surface of the toner base, and it is crushed in a shape that cuts corners. Therefore, the chargeability of the toner becomes uniform. Further, since the toner is spherical, the powder fluidity is greatly improved. At this time, the narrow gap between the rotating body and the fixed body is preferably 0.5 to 5 mm. When the thickness is 0.5 mm or less, generation of frictional heat increases, and the toner is fused. Further, when it is 5 mm or more, the vigorous flow of the high-speed airflow cannot be generated and the pulverizability is deteriorated.

However, at this time, the thermal characteristics of the binder resin have a great influence. This effect can be specified by the storage elastic modulus of the binder resin. The storage elastic modulus is 1.0 × 10 ⁴ (dy
n / cm ² ) or less, the resin becomes too soft,
It becomes over-pulverized and a large amount of fine powder is generated. Further, the peel effect cannot be effectively exhibited, and the amount of the metal complex salt dye exposed on the toner surface increases, resulting in non-uniform chargeability of the toner. The storage elastic modulus is 2.0 × 10 ⁷ (dyn /
If it is more than 1 cm ² , the pulverizability will be lowered and the fixing failure will be more likely to occur.

When negatively charged hydrophobic silica fine particles whose surface is treated with silicone oil are used as an external additive, a magnetic toner having a high negatively charged property can be obtained, which leads to an improvement in image quality. This is because the silanol groups, which are hydrophilic groups, present on the surface of the silica fine particles are completely covered and the siloxane groups are present on the surface, and the silica fine particles have a high negative chargeability. The conventional silica whose surface is treated with dichlorodimethylsilane has low hydrophobicity and cannot be sufficiently charged.

However, since the material itself has a high chargeability, the secondary agglomeration is strong, and many silica agglomerates are present, which promotes the deterioration of fluidity, the generation of white spot noise due to the silica soul, and the occurrence of filming. This phenomenon is remarkable when the dispersibility of the internal additive of the toner base is poor. Therefore, it has been found that the external addition treatment of the magnetic toner base pulverized by the peeling effect in which the internal additive is uniformly dispersed according to the present invention can significantly suppress the generation of silica aggregates. The cause is unknown, but it is presumed that the use of an electrostatically uniform toner base can eventually suppress the occurrence of silica aggregation. It was found that this has the effect of improving the fluidity of the toner and also enhancing the charging property.

Further, at this time, silica is BE due to nitrogen adsorption.
When the T specific surface area is 50 to 350 m ² / g, the characteristics are further improved.

BET specific surface area of 50 m ² due to nitrogen adsorption
If it is less than / g, the fluidity of the toner will decrease. When the BET specific surface area due to nitrogen adsorption is 350 m ² / g or more, the aggregating property becomes strong, and even if the BET specific surface area is mixed with the toner base of the present invention, the agglomeration cannot be suppressed.

Further, the electrophotographic method according to the present invention uses an electrostatic latent image holder containing a fixed magnet, and toner is sprinkled and magnetically adhered to the electrostatic latent image holder on which an electrostatic latent image is formed. The toner is carried and conveyed to the electrode roller portion, an AC bias is applied to the electrode roller, and the toner in the non-image portion of the electrostatic latent image holding member is removed by electrostatic force and magnetic force.

That is, the electrophotographic method presented in the present invention is a cascade development method in which a magnet is installed inside the electrostatic latent image carrier and an AC voltage is applied to the electrodes to further reduce the size and improve the performance.

In the electrophotographic method of the present invention, the development is almost completed when the toner is first sprinkled on the electrostatic latent image carrier. The electrode roller portion circulates the toner in the toner retainer and at the same time collects the toner in the non-image portion of the electrostatic latent image. That is, it is the electrostatic latent image carrier that carries and carries the toner from the toner hopper to the developing section. A bare surface of the electrode roller that does not carry the toner layer faces the electrostatic latent image holding member. The electrode roller and the electrostatic latent image carrier rotate in opposite directions.

The magnetic toner according to the present invention is preferably an insulating one-component toner. When the one-component toner is used, the mixing and stirring mechanism of the carrier and the toner, which is necessary for the two-component development, and the toner concentration control are unnecessary, so that the apparatus configuration can be simplified.

Since the developing method in the electrophotographic method according to the present invention has a simple structure, there are few toner charging occasions, it is difficult to obtain high charging characteristics, and if the dispersibility of the toner deteriorates, selective consumption occurs. proceed.

However, by using the magnetic toner of the present invention, a high negative charging property can be obtained and the rising property of charging can be improved. In addition, the dispersibility of the metal complex dye and the magnetic substance is improved. As a result, although the magnetic particles are added, the negative charging property is improved and the highly charging toner property is obtained. Therefore, by using a magnetic toner capable of maintaining high fluidity and high chargeability, a developing method capable of further downsizing, simplification, and low cost of the apparatus can obtain an image with high image density and low background fog. .

Further, even if it is used for a long period of time, there is no reduction in fluidity and charge amount, a high image density without background fog is obtained, and even if it is used for a long period of time, it is possible to maintain a good image with almost no selective consumption. Becomes

[0051]

EXAMPLES The magnetic toner according to the present invention is manufactured by the following method.

The toner is mixed, kneaded, pulverized, externally added, and if necessary classified. The mixing treatment is a treatment in which a binder resin, a charge control agent, a magnetic material, and other internal additives such as a release agent and a pigment, which are added as necessary, are uniformly dispersed by a mixer equipped with a stirring blade. Is used.

In the kneading process, the mixed material is heated to disperse the internal additive in the binder resin by shearing force. The kneading at this time can be performed using a known heating kneader. As the heating and kneading machine, it is possible to use an apparatus for heating a kneaded material such as a three-roll type, a single-screw type, a twin-screw type, and a banbury mixer type and applying a shearing force to knead the mixture. The agglomerates obtained by the kneading treatment are roughly pulverized by a cutter mill or the like, and then finely pulverized, and fine powder particles are further cut if necessary to obtain a desired particle size distribution.

The pulverizing method used in the method for producing the developer of the present invention will be described with reference to FIG. Reference numeral 100 denotes a crusher main body, and a cylindrical powder rotator 101 is provided in a central portion,
A fixed body 102 having a cylindrical shape is provided outside the rotating body 101. The rotating body 101 is rotatably supported by bearings (not shown) provided above and below, and is driven by a drive device (not shown) at its lower end. At the lower end of the main body 100, there are provided an object to be crushed 103 of a magnetic toner base and a supply port 104 for introducing an air stream having a predetermined temperature.
A discharge port 105 for letting out the crushed magnetic toner base particles and the air flow is provided at the upper end portion of 00. Further, a large number of projection members 106 parallel to the generatrix are continuously arranged on the outer surface of the rotating body 101, and a large number of projection members 1 parallel to the generatrix 1 are arranged on the inner surface of the fixed body 102.
07 are continuously arranged in the circumferential direction. Rotating body 101
The tip of the protrusion 106 and the tip of the protrusion of the fixed body 102 are fitted with a minute gap of 0.5 to 5 mm. When the rotator 101 rotates at a high speed, the crushed object flows at a high speed in a spiral and moves in the upward direction while forming a minute vortex in the gap, and moves in the upward direction. Crush in a peeling manner,
It is pulverized by the so-called peel effect.

To explain the overall flow, the constant quantity feeder 1
From 08, the pulverized material 103 of the magnetic toner base is charged. The airflow generated from the airflow generation means 109 is the heat exchanger 1
The temperature is raised to a predetermined temperature at 10, passes through the conduit 111, and reaches the supply port 103. In the middle of the process, the material 103 to be crushed is thrown in from the feeder 108 and flows into the main body 100 along with the air flow. The crushed magnetic toner base is discharged from the discharge port 105. A temperature sensor 112 measures the temperature of the discharge portion. The pulverized product discharged from the discharge port 105 passes through the discharge guide path 113 and flows into the coarse powder classifier 114, where the coarse powder is classified. The particles pulverized to a predetermined particle size are separated and collected by the cyclone separator 115 and the bag filter 116.
117 is a rotary valve. The toner separated and collected by the cyclone is collected in the collection box 118 via this rotary valve. The particles that have not reached the predetermined particle size are carried by the air flow again into the crusher main body 100 through the guide passage 111, and are crushed again. The arrows in the figure show the air flow and the toner flow in the guide path.

At this time, the gap between the rotating body and the fixed body is 1 m.
m, the peripheral speed of the rotating body 101 is 130 m / sec, and is rotating at high speed. It was supplied from the constant quantity feeder 108 at 5 kg / h.

At this time, assuming that the glass transition temperature of the binder resin is Tg, the toner outlet atmosphere temperature of the crushing portion is Tg-
It is preferable that the magnetic toner is finely pulverized at a temperature of 40 ° C. to Tg + 40 ° C. When the treatment is carried out within this temperature range, an appropriate thermal action is added to the toner surface, the peeling effect of the surface is further promoted, and the spheroidization of the toner is promoted.
If the temperature is higher than this temperature range, the toners are fused with each other or the toner is fused to the mechanical device, which is not preferable. The crushed toner is discharged from the discharge port together with the airflow.

In this example, the outlet atmosphere temperature was 45 ° C. The Tg of the binder resin is 62 ° C.

External additives are externally added to the magnetic toner base particles thus obtained. A known method such as a Henschel mixer or a super mixer is used for the external addition treatment.

The binder resin of the magnetic toner according to the present invention is a vinyl polymer obtained by polymerizing or copolymerizing vinyl monomers. Examples of the monomer styrene constituting the binder resin include styrene, α-methylstyrene, styrene such as P-chlorostyrene and its substitution products, and examples of the acrylic acid alkyl ester include acrylic acid, methyl acrylate and acryl. Ethyl acid, butyl acrylate, dodecyl acrylate, octyl acrylate, isobutyl acrylate, hexyl acrylate, alkyl methacrylates, for example, methyl methacrylate, ethyl methacrylate, butyl methacrylate, octyl methacrylate,
Examples include monocarboxylic acids having a double bond such as isobutyl methacrylate, dodecyl methacrylate, and hexyl methacrylate, and substituted products thereof.

As the method for producing these copolymers, known polymerization methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization are adopted.

The copolymer used in the magnetic toner according to the present invention preferably contains a styrene-based component as a 50 to 95% by weight component. 50% by weight of styrene
If it is less than the above range, the melting property of the toner is poor, the fixing property is insufficient, and the pulverizability is deteriorated.

The magnetic toner according to the present invention contains the binder resin as a main component as described above, but other known polymers or copolymers may be used, if necessary, in addition to such a main component. . For example, there are polyester resin, epoxy resin, polyurethane resin, and the like.

To the magnetic toner according to the present invention, by adding the negatively-charged hydrophobic silica fine particles surface-treated with the polydimethyl silicone oil represented by the general formula (Formula 2), the high chargeability of the present invention can be improved. A combination of the charge control agent having the above and the magnetic particles having a high quiet density can bring out the effect of further drawing out the negative charging property.

[0065]

[Chemical 2]

The silica fine particles are preferably silica fine particles produced by vapor phase oxidation of a silicic acid halogen compound, for example, those utilizing a thermal decomposition oxidation reaction in oxyhydrogen flame of silicon tetrachloride gas. The general formula of the reaction is shown in (Chemical Formula 3).

[0067]

[Chemical 3]

The silicone oil used for the surface treatment of the silica fine particles used in the present invention is preferably polydimethyl silicone oil, and in addition, alkyl-modified silicone oil, fluorine-modified silicone oil and the like are preferable.

As the surface treatment method, a known technique is used, and a method of mixing using a mixer such as a Henschel mixer or a method of spraying silicone oil may be used.

The amount of silica added is preferably 0.1 to 5.0 parts by weight with respect to 100 parts by weight of the magnetic toner. In order to prevent the toner particles from coagulating, the addition amount of 0.1 parts by weight or more is necessary, and if it is 5.0 parts by weight or more, the floating silica increases.

Further, the magnetic toner according to the present invention may further contain a release agent such as WAX if necessary.

Further, the magnetic toner according to the present invention contains magnetic particles. The magnetic particles include metal powders of iron, manganese, nickel, cobalt, etc., ferrites of iron, manganese, nickel, cobalt, zinc, etc. Magnetite fine particles having an average particle diameter of 1 μm or less, particularly preferably 0.6 μm or less are preferable.

Next, the electrophotographic method of the present invention will be described with reference to the drawings. The present invention is not limited to this.

(Embodiment 1) FIG. 1 shows a sectional view of an electrophotographic apparatus of an embodiment of the electrophotographic method of the present invention. The developing method is a one-component developing method. Reference numeral 1 denotes an organic photoreceptor, and a charge generation layer in which a charge generation substance of τ type metal-free phthalocyanine (manufactured by Toyo Ink) is dispersed in polyvinyl butyral resin (Elec BL-1 manufactured by Sekisui Chemical Co., Ltd.) on an aluminum conductive support, Polycarbonate resin (Mitsubishi Gas Chemical Z-
200) and a charge transport layer containing 1,1-bis (P-diethylaminophenyl) -4,4-diphenyl-1,3-butadiene (T-405 manufactured by Anan) are sequentially laminated. Reference numeral 2 is a non-rotating magnet fixed coaxially with the photoconductor 1, 3 is a corona charger for negatively charging the photoconductor, 4 is a grid electrode for controlling the charging potential of the photoconductor, 5
Is the signal light.

The developing device for visualizing the latent image after exposure includes a magnetic one-component toner 7; a toner hopper 6 for supplying the magnetic toner 7 to the surface of the photoconductor 1; and a gap 8 with the photoconductor 1. A non-magnetic electrode roller set to open, 9 is a non-rotating magnet installed inside the electrode roller 8, 10 is an AC high voltage power source for applying a voltage to the electrode roller 8, and 11 is polyester for scraping off toner on the electrode roller The scraper is made of a film, and the electrode roller 8 collects excess toner in the non-image area.

Reference numeral 12 is a damper for smoothing the flow of the toner in the toner hopper and for preventing the toner from being crushed by its own weight and clogged between the photosensitive member and the electrode roller.

Reference numeral 13 is a transfer charger for transferring the toner image on the photosensitive member onto the paper. Reference numeral 18 is a cleaning blade for scraping off the transfer residual toner, 19 is a cleaning box for storing waste toner, and 23 is waste toner.

An elastic urethane blade was used as the cleaning blade, but a fur brush to which a bias was applied,
A similar result is obtained with a conductive metal roller.

The magnetic flux density on the surface of the photoconductor 1 is 600 Gs. The magnetic force inside the electrode roller was strengthened to improve the transportability. Further, the magnetic pole angle θ of the magnet 2 shown in the figure was set to 15 degrees. The diameter of the photoconductor 1 is 30 mm and the peripheral speed is 60 m.
It was used by rotating in the direction of the arrow in the figure at m / s. The diameter of the electrode roller 8 is 16 mm and the peripheral speed is 40 mm / s.
It was used by rotating it in the direction opposite to the traveling direction (direction of arrow in the figure). The gap between the photoconductor 1 and the electrode roller 8 is 300μ
set to m.

The photoconductor 1 is connected to the corona charger 3 (applied voltage-
-50 at 4.5kV, voltage of grid 4 -500V)
It was charged to 0V. The photoconductor 1 was irradiated with laser light 5 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor 1 was −90V. Toner 7 was attached to the surface of the photoconductor 1 by a magnet in the toner hopper 6. Next, the photoconductor 1 was passed in front of the electrode roller 8. When passing through the uncharged area of the photoconductor 1, an AC high voltage power source 10 superimposes a DC voltage of 0V on the electrode roller 8 and an AC voltage of 750V0-p (peak-to-peak 1.5kV) (frequency 1k).
Hz) was applied. After that, when the photoconductor 1 charged with −500V and having the electrostatic latent image written thereon passes, the electrode roller 8
750V 0-p (peak-to-peak 1.5) with a DC voltage of -350V superposed by an AC high-voltage power supply 10.
An alternating voltage (frequency 1 kHz) of kV) was applied. Then, the toner adhering to the charged portion of the photoconductor 1 is removed by the electrode roller
Then, a toner image in which only the image portion was negative-positive inverted was collected on the photoconductor 1. The toner adhering to the electrode roller 8 rotating in the direction of the arrow was scraped off by the scraper 11, returned to the inside of the toner hopper 6 and used for the next image formation. The toner image thus obtained on the photoconductor 1 is transferred onto the transfer paper by the transfer charger 13, and then thermally fixed by a fixing device (not shown) to obtain a copied image.

Examples of the magnetic toner of the present invention will be described. The present invention is not limited to this.

Table 1 shows an example of the material composition of the magnetic toner A1 of the present invention. As the magnetic material, deaerated magnetite was used.

[0083]

[Table 1]

The measurement results of the fluidity and the charge amount of each magnetic toner are shown in (Table 2). Flowability was defined as static bulk density. For the measurement, a powder tester PT-E type manufactured by Hosokawa Micron was used. The charge amount was measured by the blow-off method by weighing 0.2 g of the sample and blowing it for 180 sec at an air pressure of 0.2 kgf / cm ² . As the measurement conditions, a non-coated ferrite carrier was mixed at a toner concentration of 10%, put in a 100 ml polyethylene bottle, and stirred at a rotation speed of 60 rpm for 10 minutes.

[0085]

[Table 2]

The production of the magnetic toner of the present invention will be described. A mixture other than the external additives shown in (Table 1) is mixed with a Henschel mixer FM20B (manufactured by Mitsui Miike Co., Ltd.). The mixture is a twin-screw kneading extruder PCM30 (made by Ikegai Tekko Co., Ltd.)
Knead by heating. The kneaded product is roughly crushed to a size of 2 mm or less with a coarse crusher Rotoplex (manufactured by Alpine). Then, fine pulverization was performed with the pulverizer shown in FIG. In this embodiment, a Kryptron crusher manufactured by Kawasaki Heavy Industries Ltd. (KT
Fine pulverization was performed with a M0 type). Air flow classifier DS
Fine powder is cut with Type 2 (manufactured by Nippon Pneumatic Mfg. Co., Ltd.). By the above treatment, magnetic toner base particles having an average particle diameter of 8 μm were obtained.

Thereafter, external additives were added to the Henschel mixer FM2.
OB (manufactured by Mitsui Miike Co., Ltd.) was externally added.

Using the electrophotographic apparatus shown in FIG. 1, a copy test was conducted using the magnetic toner A1 of the present invention. The image density was measured by a reflection densitometer (Macbeth) and evaluated.
As a result, an extremely high-resolution and high-quality image is obtained, in which horizontal lines are not disturbed, toner is not scattered, hollow characters are not present, and a solid black image is uniform and 16 lines / mm with a density of 1.4 are reproduced. Was given. A high-density image having an image density of 1.4 or more was obtained. No background fog has occurred in the non-image area.

Then, a long-term copying test of 10,000 sheets was conducted. After 10,000 sheets, there was no deterioration in the fluidity of the toner, a high charge amount was maintained, and a copy image of high density and low-level fog comparable to the initial image was obtained.

Example 2 The material composition of the magnetic toner A2 of the present invention is shown in (Table 3). The toner was manufactured by the same manufacturing method as in Example 1.

[0091]

[Table 3]

Using the electrophotographic apparatus shown in FIG. 1, a copy test was conducted with the magnetic toner A2 of the present invention. The image density was measured by a reflection densitometer (Macbeth) and evaluated.
As a result, an extremely high-resolution and high-quality image is obtained, in which horizontal lines are not disturbed, toner is not scattered, hollow characters are not present, and a solid black image is uniform and 16 lines / mm with a density of 1.4 are reproduced. Was given. A high-density image having an image density of 1.4 or more was obtained. No background fog has occurred in the non-image area.

Then, a long-term copying test of 10,000 sheets was conducted. After 10,000 sheets, there was no deterioration in the fluidity of the toner, a high charge amount was maintained, and a copy image of high density and low-level fog comparable to the initial image was obtained.

Comparative Example 1 Table 4 shows an example of the material composition of the magnetic toner B1.

[0095]

[Table 4]

The fine pulverization was carried out by the conventional pulverization method of the airflow type collision plate system. The other manufacturing method is the same as that of the first embodiment.

Using the electrophotographic method of FIG. 1 shown in Example 1, a copy test was conducted with magnetic toner B1. The image density was measured by a reflection densitometer (Macbeth) and evaluated. As a result, a large amount of toner scatters, voids in characters occur, uneven solid black images occur, a low image density and a large amount of background fog make it impossible to obtain a practical image.

In the long-term copying test, the image density decreased and the background fog in the non-image area increased. In addition, the scratches on the photoconductor were remarkably generated, and filming also occurred, so that a practical image could not be obtained.

Comparative Example 2 Table 5 shows an example of the material composition of the magnetic toner B2.

[0100]

[Table 5]

The grindability was poor and the production efficiency was lowered. (Comparative Example 3) A toner was experimentally manufactured with the same composition as in Example 1 except that the addition amount of the magnetic material was 10% by weight. Due to the large amount of toner scattering, practical characteristics could not be obtained.

(Comparative Example 4) The addition amount of the magnetic material was 80% by weight.
A toner was trial-produced with the same composition as in Example 1 except for the above. The amount of electrification was low, and there was a lot of background fog, and practical properties could not be obtained.

(Comparative Example 5) A toner was experimentally manufactured with the same composition as in Example 1 except that the amount of the charge control agent added was 7% by weight. Due to the large amount of toner scattering, practical characteristics could not be obtained.

Comparative Example 6 The amount of silica added was 0.0
A toner was experimentally manufactured with the same composition as in Example 1 except that the content was 5%. Poor fluidity and lots of background fog, and practical properties could not be obtained.

(Comparative Example 7) The amount of silica added was 6.0% by weight.
A toner was experimentally manufactured with the same composition as in Example 1 except that the content was changed to%. A lot of floating silica was not obtained, and practical properties could not be obtained.

[0106]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, an electrostatic latent image holding member that contains a fixed magnet and moves, is installed at a position having a predetermined gap with the surface of the electrostatic latent image holding member, and is internally provided. An electrophotographic method including a developing step including an electrode roller having a magnet has a binder resin defined by a predetermined storage elastic modulus, a metal complex dye, and a quiet density of 0.5 g / cm ^3.
By adding the above magnetic substance and finely pulverizing it by the peeling effect, it is possible to obtain the characteristics of high charging and excellent rising of charging. In addition, the dispersibility of the magnetic material and the charge control agent is improved, whereby high image density such as high image density and low background fog can be realized even in long-term use in a high-performance, small-sized, low-cost developing method.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an electrophotographic apparatus in which an electrophotographic method according to an embodiment of the present invention is used.

FIG. 2 is a flow chart of an embodiment of a toner crushing device of the present invention.

[Explanation of symbols]

 1 Photoconductor drum 2 Fixed magnet 3 contained in the photoconductor 3 Corona charger 4 Grid electrode 6 Toner hopper 7 Magnetic one-component toner 8 Electrode roller 9 Magnet installed inside the electrode roller 11 Scraper 13 Transfer charger 100 Crusher body 101 Grinding Rotating Body 102 Fixed Body 104 Supply Port 105 Discharge Port 108 Quantitative Supply Machine 114 Coarse Powder Classifier 115 Cyclone Separator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 9/08 321 325 346 381 (72) Inventor Hideki Tatematsu 1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric Sangyo Co., Ltd.

Claims (9)

[Claims] 1. A magnetic toner comprising at least a binder resin and a magnetic material.
Body, magnetic toner matrix consisting of charge control agent, and external additive
The binder resin has a storage elastic modulus of 1.0 × 10
^Four~ 2.0 x 10⁷(Dyn / cm ²) (Measurement of storage modulus
The measuring device is a viscoelasticity spectrometer and the measuring condition is 200
℃, 20Hz) and styrene as the main component
Styrene-based polymer or styrene based on styrene
Mixture of styrene-based polymer or styrene-based polymer
Styrene-based copolymer or styrene containing styrene as a main component
The charge control agent is a small amount.
If it is not composed of a metal complex dye represented by the general formula (Chemical formula 1)
And the magnetic material has a bulk specific gravity of at least 0.5 g / cm.
³It consists of the above magnetic particles,
Grinding has irregularities on the surface and at a peripheral speed of 80 m / sec or more
Cylindrical crushing rotating body rotating at high speed, and the crushing rotating body
A narrow gap of 0.5 to 5 mm with the crushing rotating body on the outside of the
It is composed of a fixed body fitted with a gap and having irregularities on the surface.
The crushing part to be crushed, the magnetic toner base of the crushed object and the air flow
A supply port for supplying the magnetic toner crushed by the crushing unit
By means of a fine pulverizer equipped with an outlet for discharging the air flow
A method for producing a magnetic toner, which is performed. [Chemical 1] 2. The method for producing a magnetic toner according to claim 1, wherein the charge control agent is contained in an amount of 0.01 to 5.0% by weight based on the weight of the magnetic toner. 3. The magnetic material comprises 15 to 15 parts by weight of the magnetic toner.
70% by weight is contained, The manufacturing method of the magnetic toner of Claim 1 characterized by the above-mentioned. 4. The external additive is composed of at least negatively charged hydrophobic silica fine powder surface-treated with silicone oil, and is contained in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the magnetic toner. The method for producing a magnetic toner according to claim 1, which is characterized in that. 5. An electrostatic latent image holding member that moves by containing a fixed magnet.
The toner hopper, the surface of the electrostatic latent image carrier, and
A toner cartridge with a magnet inside is located at a position with a constant gap.
An electrostatic latent image on the electrostatic latent image holder having a collecting electrode roller.
After the formation of the
The magnetic toner is magnetically attracted to the surface of the latent image carrier,
The developer is supported on the surface of the electrostatic latent image carrier,
The electrostatic latent image holder is moved to move the toner recovery electrode roller.
The magnetic toner on the image portion of the electrostatic latent image carrier.
, The magnetic toner in the non-image area remains in the toner recovery electrode roll.
Developing process in which the electrostatic latent image on the electrostatic latent image carrier is visualized.
A transfer step of transferring an image agent to a transfer paper by electrostatic force, and before partially remaining on the electrostatic latent image holder during the transfer step.
Cleaning agent for removing developer from the electrostatic latent image carrier
And an electrophotographic method, wherein the magnetic toner comprises at least a binder resin, a magnetic material, and an electric charge.
It consists of a magnetic toner base consisting of a control agent and an external additive.
The binder resin has a storage elastic modulus of 1.0 × 10.^Four~ 2.0
× 10⁷(Dyn / cm ²) (The storage elastic modulus measuring device
Elasticity spectrometer, measurement condition is 200 ℃, 20H
z) and styrene based on styrene
Polymer or styrene-based polymer containing styrene as a main component
Or a styrene-based resin containing styrene as a main component.
Styrene-based copolymer based on polymer or styrene
And a charge control agent represented by at least the general formula (Formula 1)
And a magnetic specific gravity of at least 0.5 g / cm.³Since
The above magnetic toner particles are finely pulverized to have irregularities on the surface,
Cylindrical crushing cycle that rotates at a high speed of 80 m / sec or more
A tumbling body, and the crushing rotator on the outside of the crushing rotator.
Fitted with a narrow gap of 5 to 5 mm and has irregularities on the surface
The crushing part consisting of a fixed body and the magnetism of the crushed object
In the crushing section and the supply port for supplying the toner base and the air flow
It has a discharge port for discharging the crushed magnetic toner and the air flow.
Use the magnetic toner that is produced by the fine pulverizer provided.
And an electrophotographic method. 6. The electrophotographic method according to claim 5, wherein the charge control agent is a magnetic toner containing 0.01 to 5.0% by weight based on the weight of the magnetic toner. 7. The magnetic material comprises 15 to 15 parts by weight of the magnetic toner.
The electrophotographic method according to claim 5, wherein a magnetic toner containing 70% by weight is used. 8. A magnetic toner 10 wherein the external additive is fine powder of negatively charged hydrophobic silica surface-treated with silicone oil.
The electrophotographic method according to claim 5, wherein the magnetic toner is used in an amount of 0.1 to 5.0 parts by weight based on 0 parts by weight. 9. The electrophotographic method according to claim 5, wherein the magnetic toner is a one-component toner.