JPS5938755A - Electrostatic charge image developing carrier - Google Patents

Abstract

PURPOSE:To obtain a carrier having low cost and stable characteristics, by using polyhedral particles obtained by bringing iron powdery particles into collision with a flat face. CONSTITUTION:Iron powdery particles having polyhedral forms each resembling a sphere or ellipse as a whole are obtained by mechanically treating them, that is, bringing them into collision with a flat face or bent face, or bringing a member having flat faces into collision with each particle. These polyhedral particles are used directly or they are used as a core and each coated with a resin coating layer on the outer surface, and used for an electrostatic charge image developing carrier. A preferable average particle diameter of the iron particles is 10-500mum. A favorable thickness of the resin coating layer is 0.1- 5mum.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is applicable to electrophotography, electrostatic printing, electrostatic recording,
It relates to a carrier that carries and images the electrostatic charge image formed in the image.

For example, in electrophotography, a photoreceptor consisting of a photoconductive element is given a uniform surface charge in the dark, and then imagewise exposed to light to form an electrostatic charge image, which is removed from toner and carrier. The developer is then used to develop the image to form a visible image.

Generally, there are two methods for developing such static ML images: liquid development method and dry development method.The liquid development method involves dispersing various pigments or V Yosomemine 1 as fine particles in an insulating organic liquid. This is a method of developing using a liquid developer consisting of a dry type 1
The one-image method is a developing method that uses a fine powder, called a toner, which is made of a binder made of natural or synthetic resin and a coloring agent such as carb/frac dispersed therein. This dry development method uses a developer whose main component is toner only (bristle brush method, impression method, powder method).
In addition to the cloud method, there are also known the magnetic flage method and the cascade method, which use a mixture of the toner and a carrier made of magnetic particles or glass beads as a developer1. In , the toner in the developer li
i. A visible image is formed by adhering to the electrostatic charge image, and this HJ visual image is fixed directly on a photoreceptor by heat, pressure, solvent vapor, etc., or is transferred to paper or other support. After this is fixed, it will be omitted.

Among the above-mentioned developing methods, the present invention provides a developer carrier used in the magnetic brush method, etc., in which the toner is stirred together with the toner, thereby imparting a desired charge to the toner, and the toner is transferred to the toner by the magnetic conveyance means of a magnetic flage. The present invention relates to a carrier that is adhered to a surface and transported, and eventually becomes a transport medium for developer.

The gear of the developer used in the conventional magnetic brush method is made of materials that are strongly magnetized in the direction of the magnetic field, such as alloys containing ferromagnetic elements such as ferrite, magnetite, iron, cobalt, and nickel. Compounds, or alloys that do not contain ferromagnetic elements but become ferromagnetic by appropriate heat treatment, such as Heusler alloys such as M/G/-Copper-Aluminum or M/G/-Copper-Tin. Toyoharare 8r iD
Alloys such as chromium dioxide and the like are known.

Since such a carrier is ferromagnetic, it is magnetically transported by a magnetic brush, so it can function as a developer transport medium, or if the particles of the toner in the developer are selected, it can impart an electric charge to the toner by friction. It has the function of However, since such a carrier has an extremely low resistance value and is a so-called conductive carrier, it leaks when it comes into contact with the charge of the electrostatic image on the photoreceptor, making it impossible to form a toner image having the desired θj 1 degree. .

For these reasons, a carrier consisting of conductive magnetic particles as bumps and an insulating resin layer formed on the surface has been proposed, and is in the process of being put into practical use.When this insulating carrier is used, the carrier This prevents contamination of toner particles on the surface of the particles, and prevents contamination between the carrier and toner.
Frictional IL% all 7 waves 1 size (☆ January n0 It is possible to control with citrus etc., it is durable and has a long service life, it is suitable for high speed glue ho, child copier etc. It has the advantage of being.

Conventionally, it has been desirable to use iron powder as the core of the carrier having this resin coating layer because it is easy to obtain raw materials, easy to manufacture and process, and low cost. The shape and surface state of the particles vary depending on the method of producing the iron powder, and there are the following advantages and disadvantages in forming a resin coating layer and using it as a carrier.

1) Iron powder produced by pulverizing raw iron material using a pulverizer has the advantage of being low in cost due to the ease of production, but its particle shape 7) - Irregular with many irregularities. Therefore, it is not possible to form a uniform resin coating layer on the surface of each particle, and for example, the resin coating layer is not formed on protrusions or corners, and the formed resin coating layer easily peels off. In addition, since the particle shape is irregular, it is difficult to obtain stable characteristics as a carrier.

2) Iron powder manufactured by a method in which iron powder raw material obtained by pulverizing yA iron material is treated with oxidizing flame to make the particles spherical, and then subjected to reduction treatment to restore the magnetization characteristics.
It has the advantage of being spherical in overall shape and low in cost, but in the reduction process that reduces iron oxide produced by oxidation flame treatment to make it spherical, oxygen is degassed, so it is a particulate or porous type. Therefore, a large amount of resin is consumed in forming the resin coating layer, and there is a drawback that a suitable resin coating I- cannot be formed and the coating layer may peel off.

3) Iron powder manufactured by a method in which a raw iron material made of pure iron is melted by an arc in a non-oxidizing atmosphere, and then blown into small droplets by an atomy day or the like and cooled is 1.
Since the particles are spherical and the surface is dense and smooth, it has the advantage of being able to form a resin coating layer advantageously and suitably, but has the disadvantage of being extremely expensive.

From the above-mentioned circumstances, a tree whose core is iron powder particles produced by the method 1) or 1l-12) above.
Coated carriers do not have stable properties, so although they are expensive, iron powder produced by method 3) above is currently used as the core, and therefore they are very commercially priced as carriers. It becomes.

The present invention has been made based on the above-mentioned circumstances, and its object is to provide an electrostatic charge material having a resin coating layer formed with iron powder particles as a core, which has low cost I and stable characteristics. One phenomenon is to provide a stage carrier.

The above object is to provide a carrier for developing an electrostatic image, characterized by comprising polyhedral particles obtained by processing iron powder particles to collide with a flat surface, or a carrier comprising polyhedral particles such as Id, lJl. This can be achieved by an electrostatic image developing carrier characterized by comprising a core and a resin coating layer formed on the surface of the core.

The present invention will now be described in detail.

In the present invention, by mechanically processing iron powder particles, each particle is made to collide with a flat plane or a curved surface, or a member having a flat surface is made to collide with each particle, whereby each of the iron powder particles For example, as shown in Fig. 1, the polyhedral particles are generally spherical or ellipsoidal in shape as a whole, and the polyhedral particles are used as they are, or they are used as cores and a resin coating layer is formed on the outer surface. This is used as a carrier for developing an electrostatic image.

In the above, in order to mechanically process iron powder particles, vc,
C. Equipment such as a ball mill, a vibration mill, an atrafter, etc. can be used, and the outer surface of the iron powder particles is formed by a large number of surfaces, preferably 8 or more, by this mechanical treatment. In addition, in order to form a layer on the outer surface of hTi iron powder particles as a core, a desired coating method can be applied using a dipping method, a soufflé method, or other known methods. It is easy to apply the solution and let it dry.

The carrier of the present invention is as described above, the core of which is mechanically treated with iron powder particles. Through this process, the shape force and completely irregular shell produced by crushing the raw wood + iron powder IJ'ik 1] and the irp sound 1
5 or consisting of particles forming a corner.j5. In this case, there is a cedar-shaped crab ball Ju in the valley particle.
The irregularities in the shape of each particle are greatly corrected and the particles are made into a polygonal shape approximating a t or ellipsoidal shape, resulting in only one Ni particle, and at the same time, the protrusions or corners are smoothed out, and the concave portions are flattened. become. In addition, if the raw material iron powder is produced by a method including oxidation flame treatment and reduction treatment, and if the surface has countless holes (or is made of porous particles), at least the surface is removed by mechanical 1.C treatment. The holes are crushed and the surface becomes almost a smooth surface.In this way, by mechanically processing the raw*;1 iron powder so that it collides with a flat surface, irregularities in shape and irregularities can be eliminated. Since the unevenness of the particles can be corrected, the particles have a uniform shape and have a smooth surface or a polyhedral shape that is substantially similar to a smooth surface.

Since the carrier of the present invention is obtained by forming a resin coating layer on the outer surface of such polyhedral particles as a core, iron powder produced by pulverization, oxidation flame treatment and It is possible to use iron powder produced by a method that includes reduction treatment, which has an irregular shape or a porous surface, but which has a very low cost. However, since the resin coating layer is formed using these multifaceted particles as described above, the outer surface of the iron powder particles used as the core is smooth or substantially similar to a smooth surface, and the shape is also uniform. Therefore, a preferable resin coating layer can be formed over the entire outer surface, the amount of resin consumed is small, and application is easy, and the resin coating layer formed is difficult to peel off. Because of this and because the particles maintain their uniform shape even after the resin coating layer is formed, the particles have properties as a stable carrier.

That is, the carrier of the present invention can be manufactured at an extremely low cost due to the low cost of the raw material iron powder used, and is manufactured by a method of melting and dividing the raw material iron material in a non-oxidizing atmosphere. It has characteristics that are 1Kr higher than IJ7 obtained using iron powder particles.

The iron powder particles used as the core of the carry f of the present invention preferably have an average particle size of lθ to 50 microns. The thickness of the resin coating layer is approximately 0.1 to 5 microns.

The protecting resin for forming the resin coating layer may be a natural resin, a thermoplastic resin, a partially cured thermosetting resin, or the like.

Examples of the natural resin include elastic rubber, rosin, copal, damar, and dragons.
d), jalap, atora
x), and mixtures thereof.

Examples of the thermoplastic resin include polyolefins such as polyethylene, polypropylene, chlorinated polyethylene, and corosulfonated polyethylene; polystyrene, polymethylstyrene, polymethylmethacrylate-1, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, and polyvinyl Livinyl or polyvinylidenes such as butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; Fluorocarbons such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene; Included are polyamides such as polycaprolactam and polyhexamethylene azobimide; polyesters such as polyethylene terephthalate; polyurethanes; polysulfides; polycarbonate; and mixtures thereof.

Examples of the thermosetting resin include phenolic resins such as phenol formaldehyde, phenol furfural and hisorcinol formaldehyde; amino resins such as urea formaldehyde and melamine formaldehyde; polyester resins; epoxy resins and mixtures thereof; Styrene-acrylic resin has its friction #
This is suitable because it is coated with electrical properties.

Examples of the present invention will be described below.

Example 1 Conductive deficient iron powder "MFJ (8*5% 0 mesh manufactured by Tetsuko Co., Ltd.) was processed in a ball mill for 10 hours to obtain a core material.

When the particle surface of this core material was observed using an electron microscope, it was found that each particle had an overall shape close to spherical or ellipsoidal, and had almost no protrusions or corners.

For 1 hp of this core material, 1 hp of styrene-acrylic oil
A coating solution obtained by dissolving 5 g of methyl ethyl ketone in 800 ml of methyl ethyl ketone was spray coated using a fluidization head device set at a temperature of 50 C to form a resin coating layer of approximately 1 micron thickness on the core material particles. Manufactured an invention carrier.

This carrier was highly fluid with no stickiness or agglomeration, and had an electrical resistance of 1013 Ω·on or more.

This carrier was manufactured using 100 parts by weight of polyester resin and 2101 parts of carboxylic resin with an average particle diameter of 1.
Mixed with 0 micron toner to prepare a current [W scraper with a toner tolerance of 2 flood areas, electrophotographic copying machine 1-U-Bix450
When we conducted a continuous copy test using 0J (manufactured by Konishi Roku Photo Industry Co., Ltd.), each copy obtained had excellent image quality with no capri, and the durability test also showed that it could be used more than 30,000 times. Copying was possible.

Example 2 Porous iron powder (manufactured by National Standard Company, USA, bulk density z, B, % mesh) was processed in a vibrating mill for 1 hour to obtain a core material.

When the surface of these grains was observed using an electron microscope, it was found that each particle had a polyhedral shape close to a spherical or ellipsoidal shape as a whole, and had almost no protrusions or corners.

To this core material I K51, a coating solution obtained by dissolving 15 g of epoxy resin in 800 ml of methyl ethyl ketone was spray coated using a fluidized bed device set at a temperature of 50 C, and the core material particles were coated with a thickness of about 1 micron. A carrier of the present invention was manufactured by forming a resin coating layer.

This carrier was a fluid product with no stickiness or agglomeration, and had an electrical resistance of IQ 13Ω/6 m or more.

This carrier was mixed with 1.7 ml of average particle size 10 microns manufactured using 100 parts by weight of polyester resin and 111 parts by weight of carbon black to form a toner with 2 parts by weight.
A#L for the 1st phenomenon of 1, 1 copying machine for 4 Ichiko copies [U-IJ
Ix 4500-1 (manufactured by Konishiroku Photo Industry Co., Ltd.) was used in a continuous copy test, and each copy obtained had excellent image quality with no fog, and it also achieved a durability test of 30,000. It was possible to make duplicate copies.

Example 3 Iron powder rTSSv 1oOJ (manufactured by Nippon Iron Powder Co., Ltd.), which was produced by processing porous spherical iron powder using a mechanical mixing device, was used as a core material.

When the particle surface of this core material was observed using an electron microscope, it was found that each particle had an almost spherical multifaceted shape as a whole, and had almost no protrusions or corners.

For this core material lK, styrene-acrylic resin 15
A coating solution obtained by dissolving g in methyl ethyl ketone aoomj was spray coated using a fluidized bed apparatus σ set at a temperature of 50 °C to form a resin coating layer of about 1 micron thick on the core material particles. A carrier of the present invention was manufactured.

This carrier was highly fluid with no stickiness or agglomeration, and had an electrical resistance of 10 r 3 Ω·m or more.

This carrier was manufactured using 100 parts by weight of polyester resin and 10 parts by weight of carbon black, with an average particle size of 1
A developer with a toner concentration of 2% by weight was prepared by mixing with 0.4 chlorine toner and used in a photocopying machine [U-Bix 4500].
J (manufactured by Konishiroku Photo Industry Co., Ltd.), a continuous copy test was conducted, and each copy obtained had excellent image quality with no fog, and the durability test also showed that it could be used more than aooooo times. It was possible to have more than one.

Example 4 Porous spherical iron powder was processed using a mechanical mixing device to form #
The remaining iron powder rT8FV 100J (manufactured by E1 Ifl Powder Co., Ltd.) was used as the core material.

When the particle surface of this core material was observed using an electron microscope, it was found that each particle had a polyhedral shape close to a spherical shape as a whole, with almost no protrusions or curved corners.

For this core material IQ, styrene-acrylic resin 15
A coating solution obtained by dissolving g in methyl ethyl ketone aoomg was spray coated using a fluidized bed device set at a temperature of 50 tll''K to form a resin coating IVI with a thickness of about 1 micron on the core material particles. Manufactured an invention carrier.

This carrier was highly fluid with no stickiness or agglomeration, and had an electrical resistance of 10 13 Ω·m or more.

This carrier was manufactured using 100 parts by weight of polyester resin and 10 parts by weight of carbon black, with an average particle size of 1
A dye with a toner concentration of 2% by weight was prepared by mixing with 0 micron toner, and an electrophotographic copying machine [U-Bix 450
When I conducted a continuous copy test using 0J (manufactured by Konishiroku Photo Industry Co., Ltd.), I found that... All of the copies made for $4 had excellent image quality with no fogging, and in the durability test, it was possible to print more than aooooo times.

Example 5 Iron powder [DSP 185cJ (manufactured by Dowa Iron Powder Co., Ltd.)] produced by processing porous spherical iron powder using a mechanical mixing device was used as the core material.

When the particle surface of this core material was observed using an electron microscope, it was found that each particle had a polygonal shape close to a spherical shape as a whole, and the protrusions L-< had almost no corners.

For this core material I Ky, styrene-acrylic resin 1
A coating solution obtained by dissolving 5 g of methyl ethyl ketone in 30077 il of methyl ethyl ketone was spray coated using a fluidized bed device set at a temperature of 50 G to form a resin coating layer of about 1 micron thickness on the core material particles. Manufactured carrier.

This carrier was highly fluid with no stickiness or agglomeration, and had an electrical resistance of 10 13 Ω·cm or more.

This carrier was mixed with a toner having an average particle size of 10 microns prepared using 100 parts by weight of polyester resin and 10 parts by weight of Carbo Black to prepare a toner concentrate (raw material). 'Electrophotographic copying machine [U-Bix 4
When we conducted a continuous copy test using 500J (manufactured by Konishiroku Photo Industry Co., Ltd.), we found that all of the copied images had excellent image quality with no fog, and the durability test also showed that the results were good even after 30,000 copies. Example 6 The above copying was possible. Iron powder [D8P 235CJ (manufactured by Dowa Iron Powder Co., Ltd.) manufactured by processing porous spherical iron powder with a mechanical mixing device was used as the core material.

When the particle surface of this core material was observed using an electron microscope, it was found that each particle had an almost spherical multifaceted shape as a whole, and had almost no protrusions or corners.

For this core material l Ky, styrene-acrylic resin 1
A coating solution obtained by dissolving 5 g of methyl ethyl ketone in 300 ml of methyl ethyl ketone was spray coated using a fluidizing Peller P device set at a temperature of 50 C to form a resin coating layer of approximately 1 micron thickness on the core material particles. Manufactured the invention Gearia.

This gear has high fluidity without stickiness or agglomeration, and has an electrical resistance of 1013 Ω·m or more.

This carrier was manufactured using 100 parts by weight of polyester resin and 10 parts by weight of carbon black with an average particle size of 1
A developer having a toner concentration of 2% by weight was prepared by mixing with 0 micron toner and used in an electrophotographic copying machine [U-Bix 450
0J (manufactured by Konishiroku Photo Industry Co., Ltd.) was used in a continuous sawing test, and all the copies obtained had excellent image quality with no fogging.

Also, in a durability test, it was possible to make over 80,000 copies.

Example 7 Iron powder produced by processing iron powder with a mechanical mixing device [
DsP 185CJ (manufactured by Dowa Iron Powder Co., Ltd.) was used as the core material.

When the particle surface of this core material was observed using an electron microscope, it was found that each particle had an overall spherical shape or a polyhedral shape close to (゛;A spherical shape), with almost no protrusions or corners. .

To this core material I Ky, a coating solution obtained by dissolving 15 g of epoxy resin in methyl ethyl ketone aooml was spray-coated using a fluidized bed device set at a temperature of 50C, and the particles of the core material were coated with a coating solution with a thickness of about 1 micron. A carrier of the present invention was manufactured by forming a resin coating layer.

This carrier was highly fluid with no stickiness or agglomeration, and had an electrical resistance of 10 13 Ω·α or more.

This carrier was mixed with a toner having an average particle size of 10 microns produced using 100 parts by weight of polyester resin and 10 parts by weight of carbon black to prepare a double-grained toner density phenomenon agent, which was then used for electrophotography. Copy machine [U-13ix
When we conducted a continuous copy test using '4500J (manufactured by Konishiroku Photo Industry Co., Ltd.), we found that all of the copied art dealers that were tested had crushed images with no fog, and in the durability test they also showed that they had more than aoooo times of copying. It was possible to make copies of

Comparative Example 1 The amorphous iron powder "EF" used in Example (2) was used as the core material.

When the particle list + Mr of this core material was examined using an electron microscope, each particle had an irregular shape.

It had many protrusions or corners.

For this core UIKy, styrene-acrylic resin 15
g"a? A coating solution obtained by dissolving in 300 ml of methyl ethyl ketone was coated using a fluidizing device set at a temperature of 50 U to coat the core material particles to a thickness of about 1 mil [1 ml of resin. A comparative carrier was manufactured by forming a heated layer.

This carrier had high fluidity without stickiness or agglomeration, but had a low electrical resistance of less than 9 Ω·m.

This carrier was manufactured using a polyester resin LOOO weight part and a carmen black 10 car# part with an average particle diameter of 1.
Mix with 0 micron toner to prepare toner (11 degrees 2% by weight developer) and use it in electrophotographic copying machine 1'-U-Bix
4500-1 (manufactured by Konishiroku Photo Industry Co., Ltd.), one copy obtained was unclear with a lot of fog, and in the durability test, 10t JUO copies were made. That was the limit.

Comparative Example 2 The porous iron powder used in Example 2 was used as it was as the core 4'A.

When the particle surface of this core material was silver-philized using an electron microscope, it was found that although Tanizuko had a spherical shape as a whole, there were countless holes on the surface.

For this core material I KF, styrene-acrylic resin 1
A coating solution obtained by dissolving 5 g of methyl ethyl ketone in 300 mL of methyl ethyl ketone was spray coated using a fluidized bed device set at a temperature of 50 C to form a resin coating layer on the core material particles to form a coating carrier. was made into coins.

This Kya IJ-f was a fluid madder material with no stickiness or agglomeration, but had an extremely low electrical resistance of 10'Ω·m or less.

This carrier was manufactured using 1001 parts of polyester resin and 1 part of Carmen Black with an average particle diameter of 1 part.
0-Bix 45% toner yield was prepared by mixing it with 0 micron toner.
When a continuous copy test was conducted using 00J (manufactured by Konishiroku Photo Industry Co., Ltd.), the resulting copies were extremely blurry and blurry.

Furthermore, in the durability test, the maximum number of copies was 10,000 times.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view schematically showing the form of a core of a carrier for electrostatic one-parameter development according to the present invention. Slow C11 figure

Claims (1)

[Claims] l) Processing so that iron powder particles collide with a peaceful surface
A carrier for developing electrostatic images characterized by comprising polyhedral particles. 2) Treat the iron powder particles so that they collide with the flat surface.
1. A carrier for developing an electrostatic image, comprising: a core made of polyhedral particles; and a resin coating formed on the surface a11 of the core.